Chemical industry automation. Automation maintenance Maintenance of automation equipment in the chemical industry
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The purpose of this course project is to acquire practical skills in analyzing the technological process, the choice of automatic control tools, the calculation of measuring circuits of devices and control devices, as well as teaching the student independence in solving engineering problems of constructing automatic control schemes for various technological parameters.
Introduction
Automation is the use of a set of tools that allow production processes to be carried out without direct human participation, but under his control. Automation production processes leads to an increase in output, a decrease in costs and an improvement in product quality, reduces the number of maintenance personnel, increases the reliability and durability of machines, saves materials, improves working conditions and safety measures.
automation and monitoring their action. If automation facilitates the physical work of a person, then automation has the goal of facilitating mental work as well. The operation of automation equipment requires high qualification of the operating personnel.
this is the production of heat and electrical energy at any given time must correspond to the consumption (load). Almost all operations at thermal power plants are mechanized, and transient processes in them develop relatively quickly. This explains the high development of automation in thermal power engineering.
Parameter automation offers significant benefits:
1) ensures a decrease in the number of working personnel, that is, an increase in the productivity of its labor,
3) increases the accuracy of maintaining the parameters of the generated steam,
Steam generator automation includes automatic regulation, remote control, process protection, thermal control, process interlocks and alarms.
Automatic control ensures the course of continuously running processes in the steam generator (water supply, combustion, steam overheating, etc.)
Remote control allows the personnel on duty to start and stop the steam generator installation, as well as switch and regulate its mechanisms at a distance, from the console where the control devices are located.
flowing in a steam generator installation, or are connected to the object of measurement by service personnel or an information-computing machine. Thermal control devices are placed on panels, control panels as convenient as possible for observation and maintenance.
exclude incorrect operations during maintenance of the steam generator set, provide shutdown in the required sequence of equipment in the event of an accident.
emergency state of the steam generator and its equipment. Sound and light alarms are used.
The operation of boilers must ensure reliable and efficient production of steam of the required parameters and safe working conditions for personnel. To fulfill these requirements, operation must be carried out in strict accordance with the legal provisions, rules, norms and guidelines, in particular, in accordance with the "Rules for the construction and safe operation of steam boilers" of Gosgortechnadzor, "Rules for the technical operation of power plants and networks", "Technical operation of heat-using installations and heating networks ".
A steam boiler is a complex of units designed to produce steam. This complex consists of a number of heat exchange devices connected to each other and serving to transfer heat from the products of fuel combustion to water and steam. The initial carrier of energy, the presence of which is necessary for the formation of steam from water, is fuel.
The main elements of the work process carried out in the boiler plant are:
1) the process of fuel combustion,
2) the process of heat exchange between combustion products or the burning fuel itself with water,
3) the process of vaporization, consisting of heating water, evaporating it and heating the resulting steam.
During operation, two flows interacting with each other are formed in the boilers: the flow of the working fluid and the flow of the heat carrier formed in the furnace.
As a result of this interaction, steam of a given pressure and temperature is obtained at the outlet of the object.
One of the main tasks that arises during the operation of a boiler unit is to ensure equality between the produced and consumed energy. In turn, the processes of vaporization and energy transfer in the boiler unit are unambiguously associated with the amount of matter in the flows of the working fluid and the coolant.
Fuel combustion is a continuous physical and chemical process. The chemical side of combustion is the process of oxidation of its combustible elements with oxygen. passing at a certain temperature and accompanied by the release of heat. The combustion intensity, as well as the efficiency and stability of the fuel combustion process, depend on the method of supplying and distributing air between the fuel particles. It is conventionally accepted to divide the process of fuel combustion into three stages: ignition, combustion and afterburning. These stages generally proceed sequentially in time, partially overlap one another.
The calculation of the combustion process usually comes down to determining the amount of air in m3 required for the combustion of a unit of mass or volume of fuel, the amount and composition of the heat balance and the determination of the combustion temperature.
The value of heat transfer consists in the heat transfer of thermal energy released during fuel combustion to water, from which it is necessary to obtain steam, or steam, if it is necessary to increase its temperature above the saturation temperature. The heat exchange process in the boiler goes through the water-gas-tight heat-conducting walls, called the heating surface. Heating surfaces are made in the form of pipes. Inside the pipes there is a continuous circulation of water, and outside they are washed by hot flue gases or perceive thermal energy by radiation. Thus, all types of heat transfer take place in the boiler unit: heat conduction, convection and radiation. Accordingly, the heating surface is subdivided into convective and radiation. The amount of heat transferred through a unit of heating area per unit of time is called the thermal stress of the heating surface. The magnitude of the stress is limited, firstly, by the properties of the heating surface material, and secondly, by the maximum possible intensity of heat transfer from the hot coolant to the surface, from the heating surface to the cold coolant.
The intensity of the heat transfer coefficient is the higher, the higher the temperature difference of the heat carriers, the speed of their movement relative to the heating surface, and the higher the surface cleanliness.
lies in the fact that individual molecules of a liquid located at its surface and possessing high speeds, and, consequently, more kinetic energy in comparison with other molecules, overcoming the force effects of neighboring molecules, which creates surface tension, fly out into the surrounding space. With an increase in temperature, the intensity of evaporation increases. The reverse process of vaporization is called condensation. The liquid that forms during condensation is called condensate. It is used to cool metal surfaces in superheaters.
The steam generated in the boiler is subdivided into saturated steam and superheated steam. Saturated steam, in turn, is divided into dry and wet. Since superheated steam is required at thermal power plants, a superheater is installed to overheat it, in which the heat obtained as a result of the combustion of fuel and exhaust gases is used to superheat the steam. The resulting superheated steam at a temperature of T = 540 C and a pressure of P = 100 atm. goes to technological needs.
The principle of operation of the boiler plant is to transfer the heat generated during the combustion of fuel to water and steam. In accordance with this, the main elements of boiler plants are a boiler unit and a combustion device. The combustion device serves for fuel in the most economical way and converting the chemical energy of the fuel into heat. The boiler unit is a heat exchange device in which heat is transferred from the products of fuel combustion to water and steam. Steam boilers produce saturated steam. However, during transportation over long distances and use for technological needs, as well as at CHPPs, the steam must be superheated, since in a saturated state, when cooled, it immediately begins to condense. The boiler includes: a firebox, a superheater, a water economizer, an air heater, lining, a frame with ladders and platforms, as well as fittings and fittings. Ancillary equipment includes: draft and feeding devices, water treatment equipment, fuel supply, as well as instrumentation and automation systems. The boiler plant also includes:
1. Tanks for collecting condensate.
2. Installations for chemical water treatment.
3. Deaerators for removing air from chemically treated water.
4. Feed pumps for feeding feed water.
5. Installations for gas pressure reduction.
6. Fans for air supply to burners.
Smoke exhausters for removing flue gases from furnaces. Let us consider the process of obtaining steam with given parameters in a boiler house operating on gas fuel. Gas from the gas distribution point enters the boiler furnace, where it burns, releasing the corresponding amount of heat. The air necessary for fuel combustion is pumped by a blower fan into the air heater located in the last gas duct of the boiler. To improve the fuel combustion process and increase the efficiency of the boiler operation, the air can be preheated by flue gases and an air heater before being fed into the furnace. The air preheater, perceiving the heat of the exhaust gases and transferring it to the air, firstly, reduces the loss of heat with the exhaust gases, and secondly, it improves the conditions for fuel combustion by supplying heated air to the boiler furnace. This increases the combustion temperature and the efficiency of the installation. Part of the heat in the furnace is transferred to the evaporating surface of the boiler - a screen that covers the walls of the furnace. The flue gases, having given up part of their heat to the radiation heating surfaces located in the combustion chamber, enter the convective heating surface, are cooled and are removed by the smoke exhauster through the chimney into the atmosphere. The water continuously circulating in the screen forms a steam-water mixture, which is discharged into the boiler drum. In the drum, steam is separated from the water - so-called saturated steam is obtained, which enters the main steam line. The flue gases coming out of the furnace wash the coil economizer, in which the feed water is heated. Heating water in an economizer is expedient from the point of view of fuel economy. A steam boiler is a device that works in difficult conditions - at high temperatures in the furnace and significant steam pressure. Violation of the normal operation of the boiler plant can cause an accident. Therefore, each boiler plant has a number of devices that give a command to stop the fuel supply to the boiler burners under the following conditions:
1. When the pressure in the boiler rises above the permissible value;
2. When the water level in the boiler drops;
3. When the pressure in the fuel supply line to the boiler burners decreases or increases;
4. When the air pressure in the burners decreases;
To control the equipment and control its operation, the boiler room is equipped with instrumentation and automation devices.
1. Lowering the pressure of the gas coming from the hydraulic fracturing;
2. Decrease of vacuum in the boiler furnace;
3. Increase of steam pressure in the boiler drum;
5. Extinction of the torch in the top.
3. The choice of measuring instruments of technological parameters and their comparative characteristics
3.1 Selection and justification of control parameters
The choice of monitored parameters provides the most complete measurement information about the technological process, about the operation of the equipment. Temperature and pressure are subject to control.
4. Selection of monitoring and control parameters
The control system must ensure the achievement of the control goal due to the specified accuracy of technological regulations in any production conditions, while observing the reliable and trouble-free operation of the equipment, explosion and fire hazard requirements.
The purpose of power consumption management is: to reduce the specific consumption of electricity for the production of products; rational use of electricity by technological services of divisions; correct planning of electricity consumption; control of consumption and specific consumption of electricity per unit of manufactured products in real time.
The main task in the development of a control system is the choice of parameters involved in control, that is, those parameters that need to be monitored, regulated and analyzing the change in values of which it is possible to determine the pre-emergency state of the technological control object (TOC).
Those parameters are subject to control, according to the values of which operational management technological process (TP), as well as starting and stopping technological units.
4.1 Pressure measurement
manovacuum meters; pressure gauges (for measuring low (up to 5000 Pa) excess pressures); traction meters (for measuring small (up to hundreds of Pa) discharges); draft gauges; differential pressure gauges (for measuring the pressure difference); barometers (for measuring atmospheric pressure). According to the principle of operation, the following pressure measuring instruments are distinguished: liquid, spring, piston, electrical and radioactive.
For measuring gas and air pressure up to 500 mm of water. Art. (500 kgf / m2) use a glass U-shaped liquid pressure gauge. The pressure gauge is a glass U-shaped tube attached to a wooden (metal) panel that has a scale in millimeters. The most common pressure gauges with scales of 0-100, 0-250 and 0-640 mm. The value of pressure is equal to the sum of the heights of the levels of the liquid, dropped below and raised above zero.
In practice, sometimes double-scale manometers are used, in which the scale division is changed by half and the numbers from zero up and down go with an interval of 20: 0-20-40-60, etc., while there is no need to indicate the heights of liquid levels , it is enough to measure the readings of the manometer at the level of one elbow of the glass tube. Measurement of small pressures or vacuum up to 25 mm of water. Art. (250 Pa) single-tube or U-shaped liquid pressure gauges leads to large errors in the reading of measurement results. The tube is tilted to scale up the readings of the one-tube pressure gauge. This principle is used for liquid draft gauges TNZh, which are filled with alcohol with a density of r = 0.85 g / cm3. in them, liquid from a glass vessel is displaced into an inclined tube, along which a scale is located, graduated in mm of water. Art. When measuring vacuum, the impulse is connected to a nipple, which is connected to an inclined tube, and when measuring pressure, to a nipple, which is connected to a glass vessel. Spring pressure gauges. Spring pressure gauges are used to measure pressure from 0.6 to 1600 kgf / cm2. The working element of the manometer is a curved tube of elliptical or oval section, which is deformed under the influence of pressure. One end of the tube is sealed, and the other is connected to a fitting, which is connected to the measured medium. The closed end of the tube is connected through a rod to the toothed sector and the central toothed wheel, on the axis of which the arrow is mounted.
The pressure gauge is connected to the boiler through a siphon tube, in which steam is condensed or water is cooled and the pressure is transferred through the chilled water, which prevents damage to the mechanism from the thermal effect of steam or hot water, and the pressure gauge is protected from water hammer.
In this process, it is advisable to use the Metran-55 pressure sensor. The selected sensor is ideal for measuring the flow rate of liquid, gas, steam. This sensor has the required measurement limits - min. 0-0. 06 MPa up to max. 0-100 MPa. Provides the required accuracy of 0. 25%. It is also very important that this sensor has an explosion-proof design, the output signal is unified - 4-20 mA, which is convenient when connecting a secondary device since it does not require additional installation of an output signal converter. The sensor has the following advantages: 10: 1 readjustment range, continuous self-diagnosis, built-in RFI filter. Microprocessor electronics, the ability to easily and conveniently configure the parameters with 2 buttons.
The measured pressure is supplied to the working cavity of the sensor and acts directly on the measuring membrane of the strain gauge, causing it to bend.
The sensing element is a single-crystal sapphire plate with silicon film strain gauges. Connected to the metal plate of the strain gauge. Strain gages are connected in a bridge circuit. Deformation of the measuring diaphragm leads to a proportional change in the resistance of the strain gages and an imbalance in the bridge circuit. The electrical signal from the output of the bridge circuit of the sensors goes to the electronic unit, where it is converted into a unified current signal.
The sensor has two modes of operation:
Pressure measurement mode; - the mode of setting and controlling the measurement parameters.
In the pressure measurement mode, the sensors provide constant monitoring of their operation and, in the event of a malfunction, generate a message in the form of a decrease in the output signal below the limit.
4.2 Temperature measurement
One of the parameters that must not only be monitored but also signaled the maximum allowable value is the temperature.
resistance thermometers and radiation pyrometers.
In boiler rooms for measuring temperature, devices are used whose principle of operation is based on the properties manifested by substances when heated: Change in volume - expansion thermometers; Pressure change - manometric thermometers; The appearance of thermoEMF - thermoelectric pyrometers;
Change in electrical resistance - resistance thermometers.
extensions are used for local temperature measurements in the range from -190 to + 6000C. The main advantages of these thermometers are simplicity, low cost and accuracy. These instruments are often used as reference instruments. Disadvantages - impossibility of repair, lack of automatic recording and the possibility of transmitting readings over a distance. The limits of measurement of bimetallic and dilatometric thermometers are from - 150 to +700 0С, error is 1-2%. Most often they are used as sensors for automatic control systems.
Gauge thermometers. Serve for remote temperature measurement. Their principle of operation is based on changing the pressure of liquids, gas or steam in a closed volume, depending on the temperature.
The type of working substance determines the type of a manometric thermometer:
Gas - inert gas (nitrogen, etc.)
Their advantage is simplicity of design and maintenance, the possibility of remote measurement and automatic recording of readings. Also, the advantages include their explosion safety and insensitivity to external magnetic and electric fields. Disadvantages - low accuracy, significant inertia and a relatively short distance for remote transmission of readings.
Thermoelectric pyrometer. It is used to measure temperatures up to 16000C, as well as transmit readings to the heat shield and consists of a thermocouple, connecting wires and a measuring device.
A thermocouple is a connection of two conductors (thermoelectrodes) made of different metals (platinum, copper) or alloys (chromel, copel, platinum rhodium), isolated from each other with porcelain beads or tubes. Some ends of thermoelectrodes are soldered, forming a hot junction, while others remain free.
For ease of use, the thermocouple is placed in a steel, copper or quartz tube.
When the hot junction is heated, a thermoelectromotive force is generated, the magnitude of which depends on the temperature of the hot junction and the material and material of the thermoelectrodes.
electrical resistance of conductors or semiconductors with temperature changes. Resistance thermocouples: platinum (TSP) are used for long-term measurements in the range from 0 to +650 0С; copper (TCM) for measuring temperatures in the range from –200 to +200 0С. Automatic electronic balanced bridges with an accuracy class of 0.25 to 0.5 are used as secondary devices. Semiconductor resistance thermometers (thermistors) are made from oxides of various metals with additives. The most widespread are cobalt-manganese (KMT) and copper-manganese (MMT) semiconductors, used to measure temperatures in the range from -90 to +300 0C. Unlike conductors, the resistance of thermistors decreases exponentially with increasing temperature, due to which they have high sensitivity. However, it is almost impossible to manufacture thermistors with strictly identical characteristics, so they are calibrated individually. Resistance thermocouples complete with automatic electronic balanced bridges allow you to measure and record temperature with high accuracy, as well as transmit information over long distances .. The most widespread, as primary measuring transducers of such thermometers, are currently received: platinum-rhodium - platinum (TPP) converters with measurement limits from - 20 to + 1300 0С; chromel-copel (TChK) transducers with measurement ranges from -50 to + 600 ° C and chromel-alumel (TXA) converters with measurement ranges from -50 to + 1000 ° C. For short-term measurements, the upper temperature limit for the THK converter can be increased by 200 ° C, and for TPP and TXA converters by 300 ° C. To measure the temperature on pipelines and boilers, I decided to choose thermoelectric converters of the THK type - the choice of these particular converters is due to the fact that in the measurement range from -50 to +600 0С it has a higher sensitivity than the TXA converter. Main characteristics of thermoelectric converter of ТХК-251 type manufactured by CJSC PG "Metran":
· Purpose: for measuring temperatures of gaseous and liquid media;
· Range of measured temperatures: from - 40 to +600 0С;
· The length of the mounting part of the converter is 320 mm;
· Material of a protective cover; stainless steel, grade 12X18H10T, and its diameter is 10 mm;
· Average service life not less than 2 years;
· Sensing element: thermocouple cable KTMS-HK TU16-505. 757-75;
4.3 Level measurement
The level is called the height of the filling of the technological apparatus with the working medium - liquid or granular body. The working environment level is technological parameter, information about which is necessary to control the operating mode of the technological apparatus, and in some cases to control the production process.
By measuring the level, information about the mass of the liquid in the tank can be obtained. The level is measured in units of length. Measuring instruments are called level gauges.
There are level gauges designed to measure the level of the working environment; measurements of the mass of liquid in the technological apparatus; signaling of limit values of the working medium level - level alarms.
According to the measuring range, level gauges of wide and narrow ranges are distinguished. Wide-range level gauges (with measurement limits of 0.5 - 20 m) are intended for carrying out inventory operations, and narrow-range level gauges (measurement limits (0 ÷ ± 100) mm or (0 ÷ ± 450) mm) are usually used in automatic control systems.
At present, level measurement in many industries is carried out by level gauges of various principles, of which float, buoy, hydrostatic, electrical, ultrasonic and radioisotope ones have become widespread. Visual measuring instruments are also used.
Indicator or level gauge glasses are made in the form of one or more chambers with flat glasses connected to the apparatus. The principle of operation is based on the property of communicating vessels. They are used for local level measurement. The length of the glasses does not exceed 1500 mm. The advantages include simplicity, high accuracy: disadvantages - fragility, impossibility of transmitting readings over a distance.
When calculating float level gauges, the design parameters of the float are selected, which ensure the equilibrium state of the "float-counterweight" system only at a certain depth of immersion of the float. If we neglect the force of gravity of the cable and friction in the rollers, the equilibrium state of the "float-counterweight" system is described by the equation
where Gr, Gп are the gravity forces of the counterweight and the float; S - float area; h1 is the depth of immersion of the float; pzh is the density of the liquid.
An increase in the liquid level changes the immersion depth of the float and an additional buoyancy force acts on it.
The advantage of these level gauges is their simplicity, sufficiently high measurement accuracy, the ability to transmit over a distance, the ability to work with corrosive liquids. A significant disadvantage is the sticking of a viscous substance to the float, which affects the measurement error.
The principle of operation of capacitive level gauges is based on a change in the transducer capacity from a change in the level of the controlled environment. The measurement limits of these level gauges are from 0 to 5 meters, the error is not more than 2.5%. Information can be transmitted over a distance. The disadvantage of this method is the impossibility of working with viscous and crystallizing liquids.
The principle of operation of hydrostatic level gauges is based on the measurement of the pressure that a liquid column creates. Measurement of hydrostatic pressure is carried out:
· A manometer connected at a height corresponding to the lower limit value of the level;
· Measuring the pressure of the gas pumped through the tube, which is lowered into the liquid filling the tank at a fixed distance.
In our case, the most suitable is a water indicator with round and flat glass, lowered level indicators and water taps. Water indicating devices with round glass are installed on boilers and tanks with pressure up to 0.7 kgf / cm2. the height of the glass can be from 200 to 1500 mm, the diameter is 8 -20 mm, the thickness of the glass is 2.5-3.5 mm. Flat glass can be smooth or corrugated. Corrugated glass "Klinger" has vertical prismatic grooves on the inside, polished on the outside. In such glass, the water appears dark, and the steam is light. If, during the operation of the steam boiler, the taps of the water indicating device are not dirty, then the water level in it fluctuates slightly.
4.4 Flow measurement
One of the most important parameters of technological processes is the flow rate of substances flowing through pipelines. High accuracy requirements are imposed on the means that measure the consumption and amount of substances during inventory transactions.
Let us consider the main types of flow meters: variable pressure drop meters, constant pressure drop meters, tachometric flow meters, pressure head flow meters, electromagnetic (induction) flow meters, ultrasonic ones.
One of the most common principles for measuring the flow of liquids, gases and steam is the variable differential pressure principle.
The principle of operation of constant pressure drop meters is based on the vertical movement of the sensing element, depending on the flow rate of the substance, while the flow area changes so that the pressure drop across the sensing element remains constant. The main condition for a correct reading is a strictly vertical installation of the rotameter.
Flow meters. Flow meters belong to a large group of flow meters, also called constant pressure differential flow meters. In these flow meters, the streamlined body receives a force action from the side of the incident flow, which increases with increasing flow rate and moves the streamlined body, as a result of which the displacement force decreases and is again balanced by the opposing force. The counter force is the weight of the streamlined body when the flow moves vertically from bottom to top or the force of the counter spring in the case of an arbitrary direction of flow. The output signal of the considered flow transducers is the movement of the streamlined body. To measure the flow rate of gases and liquids on process streams, rotameters equipped with converting elements with an electrical or pneumatic output signal are used.
The outflow of liquid from the vessel occurs through an opening in the bottom or in the side wall. Vessels for receiving liquid are cylindrical or rectangular.
a thin disk (washer) with a cylindrical hole, the center of which coincides with the center of the cross-section of the pipeline, the device for measuring the differential pressure and connecting pipes. The totalizing device determines the flow rate of the medium according to the speed of rotation of the impeller or rotor installed in the housing or impeller.
For gas and steam flow measurements, I opted for a Rosemount Type 8800DR Intelligent Vortex Flowmeter with integral tapered transitions, which reduces installation costs by 50%. The principle of operation of a vortex flowmeter is based on determining the frequency of vortices formed in the flow of the measured medium when flowing around a body of a special shape. The vortex frequency is proportional to the volumetric flow rate. It is suitable for measuring the flow rate of liquid, steam and gas. For digital and pulse output, the basic permissible error limit is ± 0. 65%, and for current additionally ± 0. 025%, 4-20 mA output signal. The advantages of this sensor include a non-clogging design, the absence of impulse lines and seals increases reliability, increased resistance to vibration, the ability to replace sensors without stopping the process, and a short response time. Ability to simulate verification, there is no need to narrow the pipeline during operation. A-100 can be used as a secondary device. To measure the water flow rate, we use the correlation water flow sensor DRK-4. The sensor is designed to measure the flow and volume of water in completely filled pipelines. Main advantages:
· No resistance to flow and pressure loss;
· The ability to mount primary converters on the pipeline at any orientation relative to its axis;
· Correction of indications taking into account inaccuracy of installation of primary converters;
· Non-spill, imitation method of verification;
· Check interval - 4 years;
· Unified current signal 0-5.4-20 mA;
· Self-diagnostics;
temperature of liquid fuel in the common pressure line; vapor pressure in the line for atomizing liquid fuel; pressure of liquid or gaseous fuel in common pressure lines; consumption of liquid or gaseous fuel in the whole boiler house. The boiler room should also provide for the registration of the following parameters: temperature of superheated steam intended for technological needs; water temperature in the supply pipelines of the heating network and hot water supply, as well as in each return pipe; steam pressure in the supply manifold; water pressure in the return pipe of the heating network; steam consumption in the supply manifold; water consumption in each supply pipeline of the heating network and hot water supply; the flow rate of water used to feed the heating network. Deaerator - feeding installations are equipped with indicating devices for measuring: water temperature in storage and feeding tanks or in corresponding pipelines; steam pressure in deaerators; feed water pressure in each line; water pressure in the suction and discharge pipes of the feed pumps; water level in storage and feed tanks.
| Controlled parameter | The presence of indicating devices on boilers | |||
| <0,07 | >0,07 | <115 | >115 | |
|
4. Temperature of flue gases behind the boiler 6. Steam pressure in the boiler drum 7. Steam (water) pressure after the superheater (after the boiler) 8. Steam pressure supplied for fuel oil spraying 9. Water pressure at the boiler inlet 11. Air pressure after the blower fan 12. Air pressure in front of burners (after control dampers) 15. Vacuum in front of the chimney damper or in the flue 16. Vacuum in front of and behind the tail heating surfaces 18. Water flow through the boiler (for boilers with a capacity of more than 11.6 MW (10 Gcal / h)) 19. Level in the boiler drum |
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* For boilers with a capacity of less than 0.55 kg / s (2 t / h) - pressure in the common supply line 6. Basic information about the fuel.
Fuel refers to combustible substances that are burned to produce heat. According to the physical state, the fuel is divided into solid, liquid and gaseous. Gaseous includes natural gas, as well as various industrial gases: blast furnace, coke oven, generator and others. High quality fuels include coal, anthracites, liquid fuels and natural gas. All fuels are composed of combustible and non-combustible parts. The combustible part of the fuel includes: carbon C, hydrogen H2, sulfur S. The non-combustible part includes: oxygen O2, nitrogen N2, moisture W and ash A. Fuel is characterized by working, dry and combustible masses. Gas fuel is most convenient for mixing it with air, which is necessary for combustion, since fuel and air are in the same state of aggregation.
5. Physical and chemical properties of natural gases
Natural gases are colorless, odorless and tasteless. The main indicators of combustible gases that are used in boiler rooms: composition, heat of combustion, density, temperature of combustion and ignition, explosion limits and flame propagation speed. Natural gases from pure gas fields consist mainly of methane (82-98%) and other heavier hydrocarbons. Any gaseous fuel contains flammable and non-flammable substances. Fuels include: hydrogen (H2), hydrocarbons (CmHn), hydrogen sulfide (H2S), carbon monoxide (CO2), non-combustible - carbon dioxide (CO2), oxygen (O2), nitrogen (N2) and water vapor (H2O). Calorific value - the amount of heat released during the complete combustion of 1m3 of gas, measured in kcal / m3 or kJ / m3. Distinguish between the highest heat of combustion Qvc, when the heat released during the condensation of water vapor that is in the flue gases is taken into account, and the lower Qnc, when this heat is not taken into account. When performing calculations, Qwc is usually used, since the temperature of the flue gases is such that condensation of water vapor of the combustion products does not occur. The density of a gaseous substance pr is determined by the ratio of the mass of the substance to its volume. Density unit kg / m3. The ratio of the density of a gaseous substance to the density of air under the same conditions (pressure and temperature) is called the relative density of the gas pо. Gas density pr = 0.73 - 0.85 kg / m3 (pо = 0.57-0.66) Combustion temperature is the maximum temperature that can be reached with complete combustion of the gas if the amount of air required for combustion exactly matches chemical formulas combustion, and the initial temperature of the gas and air is 0 ° C, and this temperature is called the heat output of the fuel. The combustion temperature of individual gases is 2000-2100 o C. The actual combustion temperature in the furnaces of boilers is much lower, it is 1100-1600 o C and depends on the combustion conditions. The ignition temperature is the temperature at which the fuel starts burning without the influence of the ignition source, for natural gas it is 645-700 o C. Explosive limits. The gas-air mixture, in which the gas is up to 5%, does not burn; from 5 to 15% - explodes; more than 15% - lit when air is supplied. The flame propagation speed for natural gas is 0.67 m / s (CH4 methane). The use of natural gas requires special precautions, since it may leak through leaks at the junction of the gas pipeline with the gas valve. The presence of more than 20% of the gas in the room causes suffocation, its accumulation in a closed volume from 5 to 15% can lead to an explosion of the gas-air mixture, with incomplete combustion, carbon monoxide CO is released, which, even at a low concentration, has a toxic effect on the human body.
6. Description of the scheme of automatic control of technological parameters
6.1 Functional diagram of automatic control of technological parameters
The principle of building a control system for this process is two-level. The first level consists of devices located in place, the second - devices located on the operator's panel.
Table 2.
Name and technical characteristics of equipment and materials. Manufacturing plant |
Type, brand of equipment Identification Document and Questionnaire No. | Unit measurements |
Quantity |
|
| Temperature control in the pipeline | ||||
| 1a | Gas temperature in the pipeline Thermoelectric converter |
THK-251-02-320-2-I-1-N10-TB-T6-U1. 1-PG |
PCS. | 1 |
| 1b | Secondary indicating recording device, speed of 5s, time of one revolution 8h | DISK250-4131 | PCS. | 1 |
| 2a |
PG "Metran", Chelyabinsk |
TSM254-02-500-V-4-1- |
PCS. | 1 |
| 2b | PCS. | 1 | ||
| 2c | PRB-2M | PCS. | 1 | |
| 2g | Actuator, power supply 220V, frequency 50Hz | MEO-40 / 25-0.25 | 1 | |
| 3a | Copper resistance thermocouple nominal static characteristic 100M |
TSM254-02-500-V-4-1- TU 422700-001-54904815-01 |
1 | |
| 3b | Electromagnetic converter, flow rate 5 l / min, output signal 20-100 kPa | EPP | 1 | |
| 3c | 1 | |||
| 3d | PR 3.31-M1 | 1 | ||
| 3d | Actuator, nominal pressure 1.6 MPa | 25h30nzh | 1 | |
| Pipeline flow control | ||||
| 4a | Chamber diaphragm, nominal pressure 1.6 MPa | DK 16-200 | 1 | |
| 4b | Differential transducer, error 0.5%, measurement limit 0.25 MPa | Sapphire 22DD-2450 | 1 | |
| 4c | Secondary indicating recording device. The speed is 5 s, the time of one revolution is 8 hours. | DISC 250-4131 | 1 | |
| Flow control | ||||
| 5a | IR-61 | 1 | ||
| 5 B |
PG "Metran", Chelyabinsk Self-recording, 2-channel, scale in Percentage. Cl. T. 0. 5, speed 1s. |
Rosemount 8800DR A100-BBD, 04. 2, TU 311-00226253. 033-93 |
1 | |
| 5c | Contactless reversible starter, discrete input signal 24V, power supply 220V, 50Hz | PBR-2M | 1 | |
| 5g | Actuating mechanism, power supply 220V, frequency 50Hz | 1 | ||
| Level control | ||||
| 6a | Equalizer, upper measurement limit 6m, maximum permissible overpressure 4 MPa, supply pressure 0.14 MPa, pneumatic output signal 0.08 MPa | UB-PV | 1 | |
| 6b | Pressure gauge, power supply 220V, power 10 W | EKM-1U | 1 | |
| 6c | Secondary pneumatic indicating and recording device, with control station. Air consumption 600 l / h | PV 10.1E | 1 | |
| 6g | 25h30nzh | 1 | ||
| Measurement of pressure |
7. Basic principles of automation of boiler plants
The volume of automation systems for a boiler plant depends on the type of boilers installed in the boiler room, as well as on the presence of specific auxiliary equipment in its composition. Boiler plants provide for the following systems: automatic regulation, safety automation, heat engineering control, signaling and control of electric drives. Automatic control systems. The main types of automatic control systems of boiler plants: for boilers - regulation of combustion and power supply processes; for deaerators - water level regulation and steam pressure. Automatic control of combustion processes should be provided for all boilers operating on liquid or gaseous fuels. When using solid fuel ACP combustion processes are provided in cases of installation of mechanized combustion devices.
ACP fuels are not provided.
Power regulators are recommended to be installed on all steam boilers. For boiler plants operating on liquid fuel, it is necessary to provide for the ACP of the temperature and pressure of the fuel. Boilers with a superheated steam temperature of 400 ° C and above must be equipped with an ACP of the superheated steam temperature. Safety automation. Safety automation systems for gaseous and liquid fuel boilers must be provided. These systems provide fuel cut-off in emergency situations.
Table3.
| Deviation of parameters | Fuel cut-off for boilers | |||
| Steam with steam pressure pfrom, MPa | Hot water with water temperature, 0С | |||
| <0,07 | >0,07 | <115 | >115 | |
1. Increasing the steam pressure in the boiler drum 2. Raising the water temperature behind the boiler 3. Decrease in air pressure 4. Decrease in gas pressure 5. Increase in gas pressure 6. Lowering the water pressure behind the boiler 7. Reduction of vacuum in the furnace 8. Lowering or raising the level in the boiler drum 9.Reduction of water consumption through the boiler 10. Extinction of the torch in the boiler furnace 11. Malfunction of safety automation equipment |
||||
Conclusion
In the course of the course project, practical skills were acquired in analyzing the technological process, choosing automatic controls according to the tasks set, calculating the measuring circuits of devices and controls. The skills of designing a system for automatic control of technological parameters were also obtained.
Literature
1. AS Boronikhin Yu. S. Grizak "Fundamentals of production automation and instrumentation at enterprises of the building materials industry" M. Stroyizdat 1974 312s.
2. VM Tarasyuk "Operation of boilers" a practical guide for boiler operators; edited by B. A. Sokolov. - M .: ENAS, 2010 .-- 272p.
3. V. V. Shuvalov, V. A. Golubyatnikov “Automation of production processes in the chemical industry: Textbook. For technical schools. - 2nd ed. revised and add. - M .: Chemistry, 1985. - 352 p. silt
4. Makarenko VG, Dolgov KV Technical measurements and devices: Methodical guidelines for course design. South -Ros. state tech. un-t. Novocherkassk: YRSTU, 2002 .-- 27p.
When developing and implementing automation systems chemical processes and industries use the same approaches that are used in other industries. At the same time, the conditions of chemical production and the production process itself have a number of features, which we will consider in this article.
A typical structural diagram of chemical processes is as follows:
raw material → raw material preparation → chemical synthesis → product isolation → product
At the entrance to any chemical process, there is always a source of raw materials, which must be stored and, to one degree or another, prepared for further processing. This is followed by the actual process of obtaining products. At this stage, from the previously prepared raw materials using special devices (mixers, separators, columns, reactors, etc.) and / or substances (catalysts), chemical product... Usually, devices for obtaining one product are combined into technological units. Further, the resulting product goes through the processes of separation and purification. Automation of chemical production allows you to reduce the cost of each of these stages.
Let's consider some of the features of chemical production.
Continuity
Basically, all chemical industries are characterized by continuity, i.e. the technological process is carried out in a steady state. There are also chemical industries with a periodic nature, where the sequence of operations for loading and preparing raw materials, chemical synthesis, isolation and purification of products has a finite duration.
The continuity of chemical production imposes special requirements for the development of automation systems, such as, for example, redundancy of field equipment, controllers, communication channels, workstations and servers, organization of backup power supply for equipment, etc.
Distribution
One of the features of chemical production is the placement of technological installations and equipment in open areas, which occupy a large area. A typical chemical plant covers an area from a few square kilometers to several tens of square kilometers. All this must be taken into account when designing automation systems. As a rule, in such cases, geographically distributed automated systems are used. High-speed communication channels, including those based on optical lines, are also of great importance. not all interfaces and communication protocols provide an acceptable data exchange rate over long distances.
During the operation of chemical industry enterprises, various hazardous substances are constantly present in the working area, technological processes in the devices take place at high 
pressures and temperatures. This is especially typical for petrochemical enterprises, cracking, resin and carbon production. All this places increased demands on systems for the automation of chemical processes. As a rule, control cabinets with controllers, workstations and servers are located in special rooms with forced supply of purified air. Field equipment is selected with a special design in accordance with the operating conditions. All this helps to reduce the harmful effects of hazardous substances on automation equipment.
To reduce the harmful effects of hazardous substances on operating personnel, the automation of chemical production should also provide for automated notification systems for the presence in the working area of maximum concentrations of substances hazardous to humans.
Explosion hazard
Most chemical enterprises, and especially at petrochemical enterprises, there are explosive zones. It is forbidden to use conventional automation tools in such cases. Explosion-proof automation means are used. In such areas, pneumatic actuators are widely used. The explosion protection level of the automation equipment must correspond to the explosion hazard class of the zone where it will be installed.
High energy consumption
Chemical industries, as a rule, are characterized by significant energy consumption. Depending on the type of production, it can be electricity, coal, fuel oil, natural gas, steam. On large enterprises electricity and steam are generated at their own CHPPs. In this regard, the problem of accounting for energy carriers arises. Therefore, the automation of chemical production should include an automated system for the integrated accounting of energy resources.
Conclusion
As already mentioned, the automation of chemical production occurs in the same way as in other industries.
Automation of chemical production makes it possible to improve product quality, reduce costs, reduce the number of operating personnel, increase labor productivity and improve production standards.
But the conditions of chemical production and the production process itself have a number of features that were discussed in this article.
Enterprises "Automated Systems", which has extensive experience in the automation of chemical production, will help you automate your chemical production, develop and agree on all the necessary design and estimate documentation, develop software, perform installation and commissioning.
Introduction
Introduction
The development of automation of the chemical industry is associated with the increasing intensification of technological processes and the growth of production, the use of units of large unit capacity, the complication of technological schemes, the imposition of increased requirements for the products obtained.
A technological process is understood as a set of technological operations carried out on the feedstock in one or more apparatuses, the purpose of which is to obtain a product with desired properties; they are carried out in rectification columns, reactors, extractors, absorbers, dryers and other devices. Usually, for the purpose of processing chemicals and obtaining target products from these devices, complex technological schemes are assembled.
The technological process implemented on the appropriate technological equipment is called technological object of management... TOU is a separate apparatus, unit, installation, department, workshop, production, enterprise. Various external disturbing influences (change in the consumption or composition of the feedstock, condition and characteristics of technological equipment, etc.) disrupt the operation of the TOU. Therefore, in order to maintain its normal functioning, as well as if it is necessary to change the conditions of its operation, for example, with the aim of conducting a technological process according to a certain program or obtaining a target product of a different quality or composition, the TOU must be controlled. Controlis a purposeful impact on an object, which ensures its optimal functioning and is quantitatively assessed by the value of the quality criterion (indicator). The criteria can be of a technological or economic nature (productivity of a technological unit, cost of production, etc.). With automatic control, the impact on the object is carried out by a special automatic device in closed loop; such a combination of elements forms an automatic control system. Regulation is a special case of management. Regulationis called the maintenance of the output values of the object near the required constant or variable values in order to ensure the normal mode of its operation by applying control actions to the object. An automatic device that maintains the output values of the object near the required values is called automatic regulator.
automatic regulation hydrocracking chemical 1. Research of the technological process
1.1 general characteristics production facility
Installations for hydrocracking, catalyst regeneration and diesel hydrodearomatization (RK and GDA) are designed to produce: 1.2 Description of the technological object of control
The technological object of control is the fractionation column 10-DA-201, in which the liquid reaction products are separated into target fractions. The main raw material of the 10-DA-201 column is the liquid from the 10-FA-201 gas condensate mixture (hydrogenated product) heated in the 10-VA-201 furnace to 370-394 ° C. From the 10-VA-201 furnace, the raw material is fed to the 6th plate of the 10-DA-201 column. Light raw material from the 10-FA-202 separator after heat exchangers 10-ЕА-201, 10-ЕА-202, 10-ЕА-203 and 10-ЕА-204 with a temperature of 205-237 ° С is fed to the 19 or 16th fractionation plate columns 10-DA-201 depending on the release of summer or winter type of diesel fuel. For stripping and reducing the partial pressure of light hydrocarbon fractions, superheated medium-pressure steam with a temperature of not more than 390 ° C is fed to the bottom of the 10-DA-201 fractionating column through the 10-FA-206 separator. The steam flow rate into the column is regulated by the 10-FICA-0067 flow controller with an alarm for a low 2.5 t / h steam flow rate into the 10-DA-201 column. The condensate from the 10-FA-206 separator is discharged through the condensate drain to the condensate collector. The condensate level in the 10-FA-206 separator is monitored by the 10-LISA-0033 device with 71% alarm and 79% high level blocking for closing the 10-FV-0067 valve on the steam supply line to the 10-DA-201 column. From the top of the fractionating column 10-DA-201 vapors of hydrocarbons, hydrogen sulfide, ammonia and water vapor with a temperature of 120-150 ° C and a pressure of 1.5-1.95 kgf / cm 2enter the air-cooled condenser 10-EC-202A I F. The column top temperature is controlled by the 10-TICA-0143 device with alarms for low 120 ° С and high 150 ° С temperatures. The vapor pressure at the top of the column is controlled by devices 10-PISA-0170, 10-PISA-0423A / B with a low alarm of 1 kgf / cm 2and high pressure 3 kgf / cm 2.
Upon reaching the emergency high pressure of 3.5 kgf / cm at the top of the column 10-DA-201 2from two devices out of three 10-PISA-0170, 10-PISA-0423A / B, blocking is triggered to stop the furnace 10-VA-201: shut-off devices 10-XV-0023, 10-XV-0024, valve 10-FV-0145 on the fuel gas supply line and shut-off device 10-XV-0007 on the line for supplying regeneration gases to the furnace are closed, shut-off devices 10-XV-0025, 10- XV-0006 into the atmosphere; is automatically reset from automatic to manual regulation of the 10-FICA-0142A flow controller on the air supply line to the furnace and the 10-FV-0067 valve on the steam supply line to the 10-DA-201 fractionation column is closed. The temperature of the cube, feed zone, diesel fuel extraction zones, kerosene and the top of the column 10-DA-201 is monitored using instruments 10-TI-0149, 10-TI-0148, 10-TI-0147, 10-TI-0146, 10-TI -0145, 10-TI-0144. The pressure difference between trays from 1 to 21 and from 21 to 32 by the height of the column 10-DA-201 is controlled by devices 10-PDIA-0176, 10-PDIA-0173 with alarm for a high differential of 0.3 kgf / cm 2.
Vapors leaving the top of the column enter the 10-EC-202A air-cooled condensers I F. Cooled and partially condensed steam-gas mixture from air-cooled condensers 10-EC-202A I F with a temperature of 48-52 ° С, which is controlled by the device 10-TI-0181, enters the shell space of water coolers 10-ЕА-205А / В, where it is cooled with circulating water, and with a temperature of 30-45 ° С, which is controlled is carried out according to 10-TIA-0183A / B instruments, enters the 10-FA-203 separator. Hydrocarbon gas from the separator 10-FA-203 with a temperature of 30-45 ° C and a pressure of 1.2-1.45 kgf / cm 2enters for hydrogen sulfide treatment in a low pressure scrubber 10-DA-207. Condensed and separated from water unstable gasoline from the 10-FA-203 separator through the 10-HV-0119 cut-off device enters the pump suction 10-GA-204A / S. The main part of unstable gasoline with a temperature of 35-45 ° C by the pump 10-GA-204A / S through the flow regulator 10-FICA-0066 with alarm for a low value of 32 t / h is returned as reflux to the column 10-DA-201 on 32 plates columns 10-DA-201. The balance amount of unstable gasoline through the 10-FIC-0095 flow regulator with correction for the 10-LICSA-0037C level in the 10-FA-203 separator is pumped into the 10-DA-204 debutanizer. The fractionating column 10-DA-201 has two blank plates 17 and 25 for the selection of diesel and kerosene fractions. From the 25th blank plate of the 10-DA-201 column, the kerosene fraction with a temperature of 170-195 ° C is fed through the 10-FIC-0072 flow regulator to the 10-DA-203 stripping plate to the 6th upper plate for stripping light hydrocarbons. The temperature of the kerosene fraction before stripping 10-DA-203 is controlled by the 10-TI-0152 device. Vapors of light hydrocarbons from the top of stripping 10-DA-203 with a pressure of 1.97 kgf / cm 2and a temperature of 165-210 ° C, which is controlled by the device 10-TI-0158, are returned to 10-DA-201 under the 30th plate in 10-DA-201. The 10-DA-203 stripping cube is divided by a partition that provides a constant level of kerosene fraction in the annular space of the 10-EA-207 thermosyphon reboiler. The kerosene fraction from the lower tray enters the bottom of the stripping on the side of the flow outlet to the 10-EA-207 reboiler. The steam-condensate mixture from 10-EA-207 with a temperature of 203-220 ° C is returned to the bottom of the stripping. The temperature of the kerosene fraction streams before and after 10-EA-207 is monitored using devices 10-TI-0154, 10-TI-0155. The clarity of the separation of the kerosene and unstable gasoline fraction is ensured by maintaining the set temperature between the 2nd and 3rd stripping plates 10-DA-203, corrected by the pressure from the 10-PI-0428 device. The diesel fraction from the 17th blank plate of the 10-DA-201 column with a temperature of 244-295 ° C, which is monitored using the 10-TI-0151 device, is divided into two streams: a diesel circulation reflux stream and a stream fed to stripping for stripping 10-DA-202. The flow of circulating reflux by the pump 10-GA-206A / S is fed into the tube space of the heat exchanger 10-EA-202, where, giving off heat to the light raw material of the fractionating column, entering through the annular space, it is cooled and with a temperature of 170-225 ° C is supplied as circulating reflux to 21 plate in column 10-DA-201. The flow rate of circulating reflux to the 10-DA-201 column in the amount of 110-130 t / h is regulated by the 10-FIC-0057 flow controller, the 10-FV-0057 valve of which is installed at the outlet of the circulating reflux from 10-EA-202. The temperature of the circulating reflux to the 10-DA-201 column at the outlet of the 10-EA-202 is controlled by the 10-TIC-0125 temperature controller, the 10-TV-0125 valve of which is installed on the bypass of the 10-EA-202 heat exchanger. The presence of liquid at the suction of the 10-GA-206A / S pumps is controlled by the 10-LS-0068 level switch with a blocking for stopping the 10-GA-206A / S pump due to the lack of liquid. The main flow of diesel fraction, withdrawn from column 10-DA-201 with a constant flow rate from 10-FIC-0076 through valve 10-FV-0076, goes to stripping of light hydrocarbons to the upper 6th tray in stripping 10-DA-202. Vapors of light fraction from the top of stripping 10-DA-202 with pressure up to 2.04 kgf / cm 2and a temperature of 246-252 ° C, which is controlled by the 10-TI-0160 device, and the GDA unit from 10-DA-501 is returned under the blank 25th plate in 10-DA-201. The 10-DA-202 stripping cube is divided by a baffle to ensure a constant level of diesel fraction and the creation of driving force in the annular space of the 10-EA-206 reboiler. The steam-condensate mixture from 10-EA-206 with a temperature of 250-293 ° C is returned to the bottom of the stripping. From the cube 10-DA-201, a gravity line for emergency release of the column is provided through the shut-off valve 10-HV-0157 into the tank of emergency discharges 10-FA-412. The level in the cube of the column 10-DA-201 is regulated by the level regulator 10-LICA-0032, the valves 10-FV-0109, 10-FV-0112 of which are installed on the lines for the withdrawal of hot and cold gas oil from the installation after the heat exchangers 10-ЕА-214А / В and 10-EC-203. The choice of level control in the cube of the 10-DA-201 column from the 10-LICSA-0032A and 10-LICSA-0032B devices is carried out by means of the 10-HS-0309 selector, with an alarm for a low 25% and a high level of 80%. When the emergency low 7% level is reached from the 10-LICSA-0032A / B devices, the blocking for stopping the pump 10-GA-202A / S is triggered, and when the emergency high level of 93% is reached, the blocking for closing the valve 10-FV-0067 on the supply line is triggered steam into the column 10-DA-201. Commercial gas oil from the bottom of the 10-DA-201 column with a temperature of 342-370 ° С through the 10-HV-0075 cut-off device is fed by the 10-GA-202A / S pump to the 10-EA-206, 10-EA-207, 10-EA reboilers -506, from where the combined gas oil stream with a temperature of 328-358 ° C enters in two parallel streams into the shell side of heat exchangers 10-EA-217C / B / A and 10-EA-217F / E / D, where it heats the hydrocracking feedstock. 2. Identification of the control object
To synthesize ACP, it is necessary to know the mathematical model of the control object. The mathematical model of the control object was obtained by the method of active experiment. It consists in removing the transient characteristics and determining the transfer function coefficients from them. The transient response is a solution to the differential equation of the system with a step input action and zero initial conditions. This characteristic, as a differential equation, characterizes the dynamic properties of a linear system (stationarity of object properties, linearity of a control object, concentration of object parameters). 2.1 Identification by job channel
The transient response for the reference channel was taken after changing the valve position 10FV0076 from 40.4% to 42% opening. The object's response to the disturbance was measured by a sensor at position 10TI0147 and recorded on the SCADA system. The Simoyu method of integral areas will be used to identify the object. To improve accuracy this method the acceleration curve will be smoothed using the moving average method. Delay time: τs = 25 min. 2.2 Object identification by disturbance channel
A sharp change in the irrigation flow rate into the 10DA201 column, measured by the device at position 10FI0066, was chosen as a stepwise effect on the object along the disturbance channel. Such an effect can be considered stepwise with sufficient accuracy. Similarly to the identification of an object by the reference channel, to improve the accuracy, it is necessary to smooth the transient response. Calculation of the transmission coefficient of the object: Lag time: The object was identified using the LinReg program. As a result, the object model looks like this: 3. Synthesis of the control system
3.1 Synthesis of a single-loop temperature control system on the 17th tray of the fractionation column 10DA201
The temperature control in the column is carried out by changing the flow rate of the diesel fuel discharge from the 17 tray. In this system, the irrigation flow rate into the column will be an external disturbance. A system with a PI controller was considered as a single-loop level control system. The calculation of the optimal settings for the PI regulator was carried out by the Rotach method of V.Ya. using the LinReg program. PI controller setting parameters: Ti = 13.6.res = 0.046 3.2 Synthesis of a single-loop temperature control system on the 17th tray of the fractionation column 10DA201 with disturbance compensation along the irrigation channel
One of the perturbations affecting the operation of the column is the change in the reflux rate supplied under the 31 trays of the column. This disturbance is measurable, which makes it possible to create a system to compensate for this disturbance. The structural diagram of such a system will take the form shown in Fig. 8. To ensure the condition of absolute invariance of the controlled variable with respect to the disturbance, the condition must be satisfied After substituting the real values of the transfer functions Wυ (s), Wµ (s), and Wp (s), we obtain This function cannot be implemented due to the presence of the e20s lookahead. It is impossible to achieve absolute invariance in such a system; therefore, the problem should be solved with invariance up to ε. Let us determine the vector of this function at the most dangerous resonant frequency: WK (jwres) = -2.9 + 3.2i The CFC vector at the resonant frequency falls into the 2nd quadrant of the complex plane, therefore it makes sense to use a real differentiating link of the second order as a device for inputting an action from a disturbance, since its CFC is also partially located in the 2nd quadrant. V general view the second-order differentiating link has the form Neglecting the lead in the transfer function of the ideal compensating element, we obtain the transfer function of the compensator After analyzing the function in Matlab, we can conclude that the coefficient at the first degree in the numerator is insignificant. Also, neglecting the coefficients at the third degree (since they do not have a significant effect on the properties of the transfer function), we bring the transfer function to the form of a real differentiating link of the second order Fig. 9 Correction of the compensator coefficients. As a result, the transfer function of the compensator was obtained 4. Simulation of the automatic control system in the Simulink application of the MatLab package
4.1 Modeling an ideal ATS
Fig. 11 Working out the task of single-loop automatic control system and automatic control system with disturbance compensation. Fig. 12 Working out the disturbance of a single-circuit automatic control system and automatic control system with disturbance compensation. 4.2 Comparison of the operation of single-circuit ACS and ACS with disturbance compensation
Parameter Single-circuit automatic control system Single-circuit automatic control system with disturbance compensation By reference By disturbance By reference By disturbance Maximum overshoot 1,313,11,313.1 Regulation time, min 16924016995 Degree of damping 0.870,870,870.99 4.3 Simulation of real ATS
The operation of a real system differs from ideal in some nonlinearities, such as insensitivity of sensors, limited travel and backlash of the actuator. The following elements are used to model them: Deadzone - the block generates zero output within the specified area, called the dead zone (measurement range * accuracy class * 0.05 = 0.06; measurement range * accuracy class * 0.05 = - 0.06); Backlash - simulates the backlash present in the actuator ( Δy *0,05=0,5);
Saturate - nonlinear limiter element simulates limiting the travel of the actuator (70; - 30); Fig. 13 Model of a real single-loop ACS and a real ACS with disturbance compensation. 4.4 comparison of characteristics of ideal and real ATS
Fig. 14 Working out the task with an ideal and real system. Fig. 15 Perturbation testing of a real and ideal single-loop ACS Fig.16 Working out the disturbance of the ideal and real ACS with disturbance compensation. Parameter Job processing Single-loop ACS disturbance processing without disturbance compensation Single-loop ACS disturbance processing with disturbance compensation Ideal and real systems practically do not differ in maximum overshoot and in the degree of attenuation, however, the real system has a much slower response. It was experimentally found that the main influence on the speed is exerted by the backlash of the actuator. Therefore, when choosing automation tools Special attention should be given to the choice of the actuator. 5. Calculation of the regulatory body and the choice of automation tools
5.1 Calculation of the regulatory body
P1 = P2 = 2kgf / cm2 Fmax = 115000kg / h = 160 m3 / h Dvn = 0.3m Determination of the total pressure drop in the network: Let's calculate the value of the Reynolds criterion at the maximum flow rate: Condition of hydraulic smoothness of pipes: the condition is fulfilled, hence the pipe is not hydraulically smooth. We determine the coefficient of friction λ = 0.0185, based on the value of the criterion Re and the ratio of the inner diameter of the pipe to the height of the protrusions of the pipeline roughness according to the nomogram. We find the total length of straight sections of the pipeline: Determination of the average speed in the pipeline at maximum flow rate: Let's calculate the pressure loss in straight sections of the pipeline: Let us determine the total coefficient of local resistances of the pipeline: Let's calculate the pressure loss in the local resistances of the pipeline: Total line pressure loss: Differential pressure across the regulator at maximum flow: Find the maximum throughput regulatory body: Table of conditional capacities of regulatory bodies We select a regulating body with a nominal capacity and nominal diameter. Let's check the effect of viscosity on the throughput of the regulator, for this we will recalculate the value of the Reynolds criterion, in accordance with the nominal diameter of the regulator: We select this regulating body without determining the correction factor for the viscosity of the liquid. Let us determine the updated value of the maximum flow rate: Let's define the relative values of expenses: Determination of the travel range for n = 0 with a linear characteristic Determine the range of displacement for: a) With a linear characteristic: b) With equal percentage characteristic: 0.23< S < 0,57 Determine the maximum and minimum value of the transmission coefficient for the operating range of loads: a) For linear bandwidth: b) For equal percentage bandwidth: The value of the ratio of the minimum and maximum values of the transmission coefficient with a linear bandwidth is greater than with an equal percentage. Therefore, we choose a linear flow characteristic. Static shutter imbalance: Maximum possible pressure on the valve; The difference in the areas of the upper lower body; Medium pressure force on the stem: Rod diameter; Maximum pressure behind the valve 5.2 Selection technical means automation
Small-sized control valve manufactured by LG Avtomatika... The pneumatic actuator is supplied complete with the valve. Nominal pressure PN, MPa 1.6 Nominal bore, mm 200 Throughput characteristic linear Temperature range of controlled medium -40. + 500 Temperature range the environment-50 ... + 70 Initial positions of the valve plunger NZ - normally closed Body material 12Х18Н10Т Throttle pair material 12Х18Н10Т Leakage class for control valves according to GOST 23866-87 (according to DIN) V Leakage class according to GOST 9544-93В Isobar 631 Isobar Isolating Barrier Basic error of the barrier when transmitting an analog signal: 0.05% Supply input current limitation: 200mA Limiting the input supply current from the sensor side: 23.30mA Supply voltage, V: 20.30 Explosion protection mark: ExiaIIC Response time, ms: 50 MTBF, hours: 50,000 Thermal converter with unified output signal THAU Metran 271 Output signal: 4.20mA Temperature range: - 40 ... 800 O WITH Limit of permissible basic error: 0.25% Signal versus temperature: linear Vibration resistance: V1 Explosion protection mark: ExiaIICT5 Supply voltage, V: 14.34 Rosemount 8800D Vortex Flowmeter Output signal: 4.20mA with digital signal based on HART protocol, pulse frequency 0.10kHz, digital FF Medium temperature range: - 40 ... 427 O WITH Measurement range of volumetric flow rate m 3/ h: 27 ... 885 Limit of permissible basic error: 0.65% Dust and water protection: IP65 Vibration resistance: V1 Explosion protection mark: ExiaIICT6 Maximum input supply voltage: 30V Maximum input current: 300mA 6. Metrological calculation of measuring channels
The block diagram of the channels for measuring temperature and flow is as follows: Fig. 17 Block diagram of measuring channels. The error of this measuring system consists of the errors introduced by the sensitive element of the temperature sensor, the normalizing converter, the spark protection barrier, the communication line, the input board of the microprocessor complex. At the moment, manufacturers of cables and data transmission interfaces have practically reduced the error introduced by the communication line to zero, therefore, they do not take it into account in the calculations. In turn, the errors of the normalizing converter, the sensing element and the I / O board of the microprocessor complex are determined by the manufacturer, then the limit of the permissible error of the measuring channel is determined as: γ dt= 0.25% - the error of the thermal converter; γ biz= 0.05% - error introduced by the spark protection barrier; γ hp= 0% - the error introduced by the communication line; γ i / v γ dt= 0.65% - the error of the thermal converter; γ biz= 0.05% - error introduced by the spark protection barrier; γ hp= 0% - the error introduced by the communication line; γ i / v= 0.1% - error of the I / O board. This error will provide the required channel measurement accuracy. 7. Calculation of the reliability of the automatic control system
The reliability of the control system is understood as the ability of the system to fulfill the requirements imposed on it for a given time within the limits set by its technical characteristics. It is impossible to completely exclude equipment failure, therefore, the CS reliability cannot be 100%. Let's calculate the probability of sudden failures of the measuring channel if it is known that: for ExperionC300 controllers the mean time between failures tWed n =
150,000 hours; for TCAU Metran 271 thermal converter MTBF tWed n= 20,000 hours; for Rosemount 8800D Flowmeter MTBF tWed n= 50,000 hours; for barriers of intrinsic protection Metran 631 MTBF tWed n= 50,000 hours; for connecting wires, the probability of failure in 2000 hours is 0.004. We will conventionally assume that the failure distribution law is exponential, then the probability of failure-free operation is determined by the formula:, where λ
= 1 / tWed n. ExperionC300 Controller Uptime: Probability of failure-free operation of the THAU Metran 271 thermal converter: Probability of failure-free operation of the Metran 631 spark protection barrier: Rosemount 8800D Flow Meter Uptime: Probability of failure-free operation of communication lines:
annotation
The purpose of this course project is to acquire practical skills in analyzing the technological process, the choice of automatic control tools, the calculation of measuring circuits of devices and control devices, as well as teaching the student independence in solving engineering problems of constructing automatic control schemes for various technological parameters.
Introduction
Automation is the use of a set of tools that allow production processes to be carried out without direct human participation, but under his control. Automation of production processes leads to an increase in output, a decrease in costs and an improvement in product quality, reduces the number of maintenance personnel, increases the reliability and durability of machines, saves materials, improves working conditions and safety measures.
Automation frees a person from the need to directly control mechanisms. In the automated production process, the role of a person is reduced to adjustment, adjustment, maintenance of automation equipment and monitoring their operation. If automation facilitates the physical work of a person, then automation has the goal of facilitating mental work as well. The operation of automation equipment requires high qualification of the operating personnel.
In terms of the level of automation, thermal power engineering takes one of the leading places among other industries. Heat power plants are characterized by the continuity of the processes taking place in them. At the same time, the production of heat and electric energy at any moment of time must correspond to the consumption (load). Almost all operations at thermal power plants are mechanized, and transient processes in them develop relatively quickly. This explains the high development of automation in thermal power engineering.
Parameter automation offers significant benefits:
1) ensures a decrease in the number of working personnel, i.e. increasing the productivity of his labor,
2) leads to a change in the nature of the work of the service personnel,
3) increases the accuracy of maintaining the parameters of the generated steam,
4) increases labor safety and reliability of equipment operation,
5) increases the efficiency of the steam generator.
Steam generator automation includes automatic regulation, remote control, process protection, thermal control, process interlocks and alarms.
Automatic control ensures the course of continuously running processes in the steam generator (water supply, combustion, steam overheating, etc.)
Remote control allows the personnel on duty to start and stop the steam generator installation, as well as switch and regulate its mechanisms at a distance, from the console where the control devices are located.
Thermal control over the operation of the steam generator and equipment is carried out using indicating and recording devices that operate automatically. The devices continuously monitor the processes taking place in the steam generator installation, or are connected to the measurement object by service personnel or an information computer. Thermal control devices are placed on panels, control panels as convenient as possible for observation and maintenance.
Technological interlocks perform, in a predetermined sequence, a number of operations when starting and stopping the mechanisms of a steam generating unit, as well as in cases of triggering of technological protection. Interlocks exclude incorrect operations during the maintenance of the steam generator set, provide shutdown in the required sequence of equipment in the event of an emergency.
Process signaling devices inform the personnel on duty about the state of the equipment (in operation, stopped, etc.), warn about the approach of a parameter to a dangerous value, report on the occurrence of an emergency state of the steam generator and its equipment. Sound and light alarms are used.
The operation of boilers must ensure reliable and efficient production of steam of the required parameters and safe working conditions for personnel. To fulfill these requirements, operation must be carried out in strict accordance with the legal provisions, rules, norms and guidelines, in particular, in accordance with the "Rules for the construction and safe operation of steam boilers" of Gosgortechnadzor, "Rules for the technical operation of power plants and networks", "Technical operation of heat-using installations and heating networks ".
1. Description of the technological process
A steam boiler is a complex of units designed to produce steam. This complex consists of a number of heat exchange devices connected to each other and serving to transfer heat from the products of fuel combustion to water and steam. The initial carrier of energy, the presence of which is necessary for the formation of steam from water, is fuel.
The main elements of the work process carried out in the boiler plant are:
1) the process of fuel combustion,
2) the process of heat exchange between combustion products or the burning fuel itself with water,
3) the process of vaporization, consisting of heating water, evaporating it and heating the resulting steam.
During operation, two flows interacting with each other are formed in the boilers: the flow of the working fluid and the flow of the heat carrier formed in the furnace.
As a result of this interaction, steam of a given pressure and temperature is obtained at the outlet of the object.
One of the main tasks that arises during the operation of a boiler unit is to ensure equality between the produced and consumed energy. In turn, the processes of vaporization and energy transfer in the boiler unit are unambiguously associated with the amount of matter in the flows of the working fluid and the coolant.
Fuel combustion is a continuous physical and chemical process. The chemical side of combustion is the process of oxidation of its combustible elements with oxygen, which takes place at a certain temperature and is accompanied by the release of heat. The combustion intensity, as well as the efficiency and stability of the fuel combustion process, depend on the method of supplying and distributing air between the fuel particles. It is conventionally accepted to divide the process of fuel combustion into three stages: ignition, combustion and afterburning. These stages generally proceed sequentially in time, partially overlap one another.
The calculation of the combustion process usually comes down to determining the amount of air in m3 required for the combustion of a unit of mass or volume of fuel, the amount and composition of the heat balance and the determination of the combustion temperature.
The value of heat transfer consists in the heat transfer of thermal energy released during fuel combustion to water, from which it is necessary to obtain steam, or steam, if it is necessary to increase its temperature above the saturation temperature. The heat exchange process in the boiler goes through the water-gas-tight heat-conducting walls, called the heating surface. Heating surfaces are made in the form of pipes. Inside the pipes there is a continuous circulation of water, and outside they are washed by hot flue gases or perceive thermal energy by radiation. Thus, all types of heat transfer take place in the boiler unit: heat conduction, convection and radiation. Accordingly, the heating surface is subdivided into convective and radiation. The amount of heat transferred through a unit of heating area per unit of time is called the thermal stress of the heating surface. The magnitude of the stress is limited, firstly, by the properties of the heating surface material, and secondly, by the maximum possible intensity of heat transfer from the hot coolant to the surface, from the heating surface to the cold coolant.
The intensity of the heat transfer coefficient is the higher, the higher the temperature difference of the heat carriers, the speed of their movement relative to the heating surface, and the higher the surface cleanliness.
Steam generation in boilers proceeds in a specific sequence. Steam starts to form in the wall tubes. This process takes place at high temperatures and pressures. The phenomenon of evaporation consists in the fact that individual molecules of a liquid, which are at its surface and have high speeds, and, consequently, greater kinetic energy in comparison with other molecules, overcoming the force effects of neighboring molecules that create surface tension, fly out into the surrounding space. With an increase in temperature, the intensity of evaporation increases. The reverse process of vaporization is called condensation. The liquid that forms during condensation is called condensate. It is used to cool metal surfaces in superheaters.
The steam generated in the boiler is subdivided into saturated steam and superheated steam. Saturated steam, in turn, is divided into dry and wet. Since superheated steam is required at thermal power plants, a superheater is installed to overheat it, in which the heat obtained as a result of the combustion of fuel and exhaust gases is used to superheat the steam. The resulting superheated steam at a temperature of T = 540 C and a pressure of P = 100 atm. goes to technological needs.
2. Technology of heat energy production in boiler houses
Boiler plants in industry are intended to produce steam used in steam engines and for various technological processes, as well as for heating, ventilation and domestic needs.
Chapter 7. OPERATION OF AUTOMATION SYSTEMS
7.1. OBJECTIVES AND STRUCTURE OF THE SERVICE FOR OPERATION OF AUTOMATION SYSTEMS AT THE ENTERPRISE
The main task in the operation of instruments and automation equipment is to ensure reliable and correct operation of individual links and the entire complex of these devices. The task is solved by continuous monitoring, creating normal operating conditions and timely elimination of all arising defects, for which the company organizes an automation system operation service.
Start-up, normal operation, shutdown and repair - these are the main stages of the operational cycle of both technological equipment and instruments and automation equipment serving this equipment. At each of these stages, the operation service performs work that ensures the reliable and correct functioning of the automation system.
In the 70s, the Regulation on the service of instrumentation and automation at enterprises was in force. Food Industry developed by NPO Pishcheprom-Avtomatika. In connection with the introduction in our country of the USSR metrological service, which consists of state and departmental metrological services, a departmental metrological service is organized at each enterprise. Therefore, this provision was replaced by a new Standard Regulation on the metrological service of a food industry enterprise, in accordance with which a metrological service is organized at each food enterprise.
The structure of the metrological service (MS) of a food enterprise determines the links that make up it, the distribution of functions between the links, their subordination and interrelation. The structure of the MS is developed taking into account the structure and features of the functioning of the enterprise (its subordination, category, number and interrelationships of industries, the seasonality of their work, the number of shifts in the shops), the equipment and features of the functioning of the service (the amount of work, the quantitative and qualitative composition of measuring and automation equipment, the availability of material and technical base, the condition and location of the service premises, the availability and qualifications of personnel, the possibility of cooperation in repairs, etc.), as well as the prospects for the development of the service
For the next 3-5 years.
At enterprises of the 1-3rd categories, MS is organized in the form of a laboratory, at enterprises of the 4-6th categories, in the form of a laboratory or group. The category of the enterprise depends on the volume of production and the complexity of obtaining the product. Metrological service is headed by chief metrologist enterprise, which is subordinate to the main
To the engineer of the enterprise.
The following structural chain is the cornerstone of the MS construction:
Link (group) - brigade. The laboratory at the enterprises of the 1-3rd category includes six links: metrological support of production; maintenance of automation systems, measuring instruments and automation (SIA); repair of SIA; development and implementation of production automation systems; verification of measuring instruments; accounting, storage and issuance of SIA. The first three links are also part of the laboratory (group), which is organized at enterprises of 3-6 categories.
SIA service and repair units usually consist of special and general-purpose teams. The level of specialization of personnel in a group or service team should ensure the possibility of interchangeability within two to three service areas. Depending on the nomenclature, quantity and complexity of SIA, the repair link is organized from teams with the assignment of repairs of one or several types of SIA to them: pyrometric and heat engineering; pressure, vacuum and flow; electronic and pneumatic;
Weights and Fine Mechanics; the amount and composition of substances containing mercury; radioactive and ionizing radiation; electrical and electromechanical; executive mechanisms and
Mechanical devices.
At the head (base) enterprise of the plant, industrial or agro-industrial association, a central MS (laboratory) can be organized, which, along with six links of the metrological service of an enterprise of the 1-3rd category, can also contain links for coordination and planning, installation and commissioning, supply and assembly and etc. In this case, technical service units are created at the remaining enterprises (production) of the association. Metrologists who head the MS of these enterprises are subordinate to the chief metrologist of the association (combine, base enterprise).
With a small number of SIAs at the enterprise, in agreement with the base organization at enterprises of 4-6 categories, it is allowed to organize a metrological support and maintenance group as part of the service of the chief mechanic or power engineer, who in this case performs the duties of the chief metrologist of the enterprise. The MC group is headed by the head of the group - a senior engineer. Leadership of a group performing maintenance and repairs is allowed by a senior foreman or foreman. The specialists working in these positions carry out the administrative and technical management of the teams. The deputy chief metrologist is usually the head of one of the most important links.
The number and composition of the MS is determined by calculation, taking into account the number and nomenclature of the FORC, the types and volumes of work performed, the category of the enterprise, the operating conditions of the automation system and the FORC, the working conditions of production (shift and seasonality), the level of labor organization and the established structure of the MS. Apparent number of service personnel
Where T I, - the time spent on the implementation of a specific i-th type of work; And I, is the average number of shifts in a calendar year for service personnel performing the 1st type of work (with one-shift performance of such work as repair, verification, etc., A I, = 1); k I, - coefficient taking into account the operating conditions of the SIA and the frequency of work; (Сд - coefficient taking into account various additions and restrictions; Ф N - nominal fund of working time during the year (Ф N = 2050 ... 2100 h); fee - coefficient of the payroll staff of the service (k C = 0,8...0,9).
When determining the number of categories of work, calculations are made separately for each category.
The group and the brigade are usually organized in the composition of at least five people and include workers of the following professions: mechanic-repairman; mechanic; locksmith on duty; adjuster of automation and power systems; assembler of electromechanical, radio engineering systems and SIA; laboratory assistant of the measuring laboratory; laboratory assistant for electromechanical tests and measurements; tester of measuring instruments;
Tester of electrical machines and devices, etc. If an enterprise has an automated control system, the metrological service is included in this service as independent units. Such a subdivision of the enterprise is usually headed by the deputy chief engineer of the enterprise or the head of the service, who simultaneously performs the duties of the chief metrologist.
Structurally, the ACS service consists of those links that are part of the metrological service of the enterprise, and the ACS laboratory. The main functions of the latter are related to the operation of the computing center (CC) and its external devices (the structure of the ACS service is discussed in detail in clause 3.1).
7.2. METROLOGICAL SUPPORT
Metrological support is a complex of scientific and technical foundations and organizational measures that ensure the unity and required accuracy of measurements. The scientific and technical foundations of the Ministry of Defense include metrology as a science of measurements, methods and means of ensuring the uniformity of measurements and the required accuracy and the standards of the State System for Ensuring the Uniformity of Measurements (GSI) as a set of interrelated rules, regulations, requirements and norms established by standards that determine the organization and methodology of work. to assess and ensure
Measurement accuracy.
GSI includes two types normative documents: basic standards, including GOST "Units of physical quantities", and standards of four other groups - state standards, methods and means of verification of measures and measuring instruments, measurement accuracy standards and measurement procedures (MVI). This also includes the typical test programs.
The organizational basis of the Ministry of Defense is the USSR metrological service, which, in accordance with GOST 1.25-76, consists of state and departmental metrological services. The State Metrological Service (GMS), headed by the USSR Gosstandart, includes the following divisions:
The main center of the HMS (All-Union Scientific Research Institute of the Metrological Service - VNIIMS), which carries out scientific and methodological management of the country's metrological service and the state service of standard data;
The main centers and centers of state standards (research institutes in Moscow, Kharkov, Sverdlovsk, etc. and their branches), which carry out research and other work to improve metrological support in
Country; territorial bodies of Gosstandart in the union republics,
Led by the republican departments of the USSR Gosstandart and including the republican centers of metrology and standardization;
Republican, interregional, regional and interdistrict laboratories of state supervision (LGN) for standards and measuring
Technique, as well as their departments.
Along with those listed, the State Service for Certified Materials also includes the state service of reference materials, headed by the main center for reference materials, civil service standard reference data, headed by the main center of standard reference data, the state time and frequency service of the USSR, the All-Union Association "Etalon", which unites the factories that manufacture and
Model SI is being repaired.
The main activities of the HMS are the creation and continuous improvement state system standards of units; ensuring continuous improvement of the SI fleet used in the country; transfer of the sizes of units of physical quantities to all measuring instruments used in the national economy;
State supervision over the state and correctness of the use of measuring instruments at enterprises and organizations; standardization of measurement techniques.
The departmental metrological service, headed by the chief metrologist of the ministry or department, consists of a subdivision of the ministry or department that manages the service; the head organization of the service, which methodically, scientifically, technically and in an organized manner, manages the work of the base organizations of the metrological service (MS) and MS of enterprises; basic organizations of the departmental MS, which carry out scientific, technical and organizational and methodological guidance on metrological support (MO) of the production of the groups of products or activities assigned to them, as well as on the MO of the attached enterprises or organizations; metrological services of enterprises or organizations.
Metrological support of production is aimed at obtaining high-quality and reliable information through measurement. Deficiencies in MO production lead to erroneous conclusions and significantly increase waste; an increase in the level of MO production makes it possible to improve the quality and economic indicators manufactured products.
The main tasks of the department of the Ministry of Defense of the metrological service of a food enterprise are: coordination and implementation of methodological guidance of work aimed at ensuring the uniformity and required accuracy of measurements in all divisions of the enterprise;
Systematic analysis of the state of measurements, development and implementation of measures to improve the enterprise's MO, including proposals for the purpose of SIA and measurement methods for managing technological processes, controlling raw materials and testing products; introduction of normative and technical documentation (NTD), regulating standards of measurement accuracy, metrological characteristics of SIA, measurement procedures, methods and means of verification and other requirements for metrological support of production preparation; development of technical specifications for the design and manufacture of non-standard SIA, auxiliary equipment, stands, devices for carrying out the necessary measurements, tests and control; organization and participation in carrying out a metrological examination of normative-technical, design, project and technological documentation, including those developed at the enterprise; participation in the analysis of the reasons for the violation of technological regimes, product rejects, unproductive consumption of raw materials, materials and other losses associated with the state of the SIA; advanced training of workers of the enterprise's MS and training of personnel for the enterprise's Ministry of Defense.
The link of the Ministry of Defense also communicates with the bodies of the State Standard of the USSR when they exercise state supervision over the Ministry of Defense of preparation for production and testing of products, the state, use, repair and verification of the SIA at the enterprise, and other activities of the enterprise's MS. To the territorial bodies of the USSR Gosnadzor and the base organization of the metrological service (BOMS) of the industry, the MO link provides information on the state of plans for the introduction of new "methods and SIA, which, after development and agreement with the base organization, are approved by the management of the enterprise. Standards and other NTDs of the enterprise are also agreed with BOMS. The department of metrological support is also involved in the development and implementation of tasks stipulated by the complex programs of the Ministry of Defense of the industry, develops proposals for the projects of annual and long-term plans of the Ministry of Defense of the industry.
The planning of the activities of the MS, carried out by the department of the Ministry of Defense, is regulated by the methodological instructions of VNIIMS and is carried out taking into account the production capacity of the enterprise, the range of products and technical capabilities. These plans include work aimed at ensuring plans state and sectoral standardization and metrological support of the activities of the enterprise divisions; development or revision of enterprise standards (STP), verification diagrams, measurement procedures, as well as tasks for the implementation of STO, GOST and OST.
Metrological expertise is, as follows from the above list of tasks of the Ministry of Defense, a part of the general set of works on metrological support of production. Metrological expertise (ME) includes the analysis and assessment of technical solutions for the selection of parameters to be measured, the establishment of accuracy standards and the provision of methods and means of measurement.
The sections of documents reflecting the requirements for the established accuracy standards or containing information about the means and methods of measurement are subjected to a metrological examination. During the metrological examination of technical documentation, which solves the problem of choosing measuring instruments - technological regulations, technological process charts with control operations, functional and schematic diagrams of devices with measuring instruments, the correctness of the choice of a measuring device or device is assessed.
During the metrological examination of technical documentation, which determines the parameters, properties or characteristics of machines, materials or processes, they first identify which elements, parameters or properties are subject to control during their production or operation, and then by enumerating options of standard methods determine the testability of the object. If at the same time it turns out that, due to unreasonably narrow tolerance fields of the controlled parameters, it is impossible to ensure control using standard devices, it is necessary first of all to analyze the possibility of expanding the tolerance fields.
Of particular importance is the ME of the production process, during which the compliance of the technological process with the requirements of design, technological and other NTD for metrological support is established. One of the main documents that must be passed by the ME at the enterprise is the technological regulations for the production of products.
7.3. TESTING WORKS
Verification of measuring instruments, like other measures for metrological control, is the task of the MC verification link of a food enterprise. Verification is designed to ensure the uniformity and reliability of measurements in the country and contributes to the continuous improvement of measuring instruments.
Measuring instruments, like any other automation equipment, are subject to wear and tear over time, even if all the requirements for their operation and storage are strictly observed. Wear and aging are the main reasons for the gradual change in the metrological characteristics of measuring instruments, therefore, it is necessary to systematically check them so that the deviations of the readings do not go beyond the permissible limits.
Verification of measuring instruments(SI) is the determination by the metrological authority of the uncertainty and the establishment of its suitability for use. In the process of verification, the size of the units of physical quantities is transferred from the standard to the working SI. In the general case, the transfer of the size of units is finding the metrological characteristics of the verified or certified SI using a more accurate SI. Schemes of such a transfer include standards, exemplary and working SI (Fig. 7.1).
Primary standard - it is the standard of the highest achievable accuracy at the moment, officially approved as the national primary standard. There can only be one in one country. Working standards (their number is not limited) are designed to transfer the dimensions of physical quantities to exemplary SI of the first category and the most accurate working SI. To relieve the primary standard from work on the transfer of sizes of units of physical quantities and reduce its wear, create a copy master, which is a secondary standard and is designed to transfer the sizes of physical quantities to the working standard. Model SI are also intended to convey the dimensions of physical quantities and are divided into digits (there can be a maximum of five), and the number of the digit means the number of steps in transferring the size of a unit to this exemplary SI. A decrease in the number of digits reduces the error in transferring the size of units, however, it also reduces the verification productivity. Working SIs are used only
Rice. 7.1. The scheme of transferring the sizes of units from the standard "to the working measuring instruments
For measurements not related to the transfer of sizes of units of physical quantities, and, as can be seen from Fig. 7.1 are also divided into five classes.
To determine the reliable error of the working measuring instrument, it is sufficient that the error of the exemplary means is 10 times less than the error of the working measuring instrument. Due to the difficulties in implementing such a ratio, ratios of 1: 3, 1: 4, 1: 5 are usually used, as an exception, a ratio of 1: 2 is allowed.
The main source document for organizing the verification of specific working measuring instruments is the verification scheme. Verification schemes can be all-union and local. All-Union calibration charts are developed by metrological institutes and approved by the USSR State Standard. They are the basis for the development of local verification schemes, state standards and procedures for methods and means of verification of exemplary and working measuring instruments. Local verification schemes are developed, if necessary, and implemented by the MC verification link. They are coordinated with the territorial bodies of the State Standard, which perform verification of the original exemplary measuring instruments included in the local calibration scheme. The latter covers exemplary and all working measuring instruments of a given physical quantity that are in operation at the enterprise or are put into circulation by the industry, as well as methods for their verification. In the drawing of the verification scheme, carried out in accordance with GOST 8.061-73, indicate the name of the SI, the ranges of values of physical quantities, designations and estimates of errors, the name of the verification method.
Of the verification methods, the following are the most common:
Direct comparison, which consists in comparing the readings of the verified and exemplary SI;
Comparison - in comparing the SI with the exemplary one using a measuring comparison device (comparator);
By exemplary measures - in measuring the value of a physical quantity that is reproduced by an exemplary measure or is simultaneously compared with the value of an exemplary measure.
By the time of carrying out, primary, periodic, extraordinary and inspection verification are distinguished. Initial verification is carried out when measuring instruments are released from production or repair, periodic verification during operation at established calibration intervals. An extraordinary verification is carried out regardless of the timing of periodic verification in cases where it is necessary to make sure that the measuring instruments are in good working order or before putting into operation imported measuring instruments. The need for extraordinary verifications also arises when monitoring the results of periodic verification or carrying out work to correct the calibration intervals, if the verification mark, seal is damaged and the documents confirming the verification are lost.
Extraordinary verification is also carried out during the commissioning of measuring instruments after storage, during which there was no periodic verification, or during installation their as components after the expiration of half of the warranty period for them, specified by the supplier in the accompanying documentation. Inspection verification accompanies the metrological audit of measuring instruments of enterprises that carry out the repair, operation, storage and sale of these instruments.
Depending on the purpose of the verified measuring instruments, verification can be state or departmental. Of those used at food industry enterprises, the following measuring instruments are subject to mandatory state verification:
Used as initial exemplary measuring instruments (SI) in the bodies of departmental metrological services; owned by enterprises and used as exemplary measuring instruments by the bodies of the state metrological service; produced by instrument repair enterprises after repairs carried out for other enterprises; intended for use as working instruments for measurements related to accounting for material values, mutual settlements and trade, health protection of workers, ensuring safety and health of work in accordance with the list approved by the USSR State Standard. The rest of the working measuring instruments used in the food industry are subject to departmental verification.
In accordance with the nomenclature list approved by the USSR State Standard, mandatory state verification, in particular, are subject to flow meters for liquids, steam and gas with secondary devices, industrial gas, water and heat meters, meters of oil, oil products, alcohol and other industrial liquids and food products. , dispensers of liquid food products, mass measuring instruments and devices, bar length measures, industrial three-phase current meters, refractometers, saccharimeters, photoelectric colorimeters and densitometers used for settlements with consumers.
State verification of instruments is carried out by metrologists-testers of bodies of the state metrological service. In the presence of the necessary premises, all regulatory documents, exemplary measuring instruments that have passed state verification, as well as metrologists-verifiers, the bodies of the USSR State Standard issue registration certificates to the bodies of departmental metrological services for the right to carry out verification, which can be combined with certificates for the right to manufacture and repair measuring instruments ... Verification metrologists undergo special training and take exams in the bodies of the state metrological service.
If the verification link of the MS of a food enterprise does not have the right to conduct departmental verification of certain measuring instruments, then the latter are verified in the basic bodies of the departmental MS of the industry or the bodies of the state metrological service. The verification of measuring instruments of enterprises is carried out by the bodies of the USSR State Standard in stationary or mobile laboratories, as well as directly at enterprises by the state inspectors.
Measuring and automation instruments subject to verification are verified in accordance with the schedules of state or departmental verification, drawn up by the verification link of the enterprise's MS, agreed with the local state supervision authority and approved by the chief engineer of the enterprise. Typically, verification schedules are drawn up for instruments and automation equipment by type of measurement.
The frequency of calibration of measuring instruments is established in accordance with the methodological instructions of the USSR State Standard for determining the calibration interval of working measuring instruments, taking into account the actual stability of the indications, operating conditions and the degree of workload of measuring instruments. The frequency of verification of measuring instruments belonging to the enterprise and subject to departmental verification must be agreed with the base organization. Measuring instruments at food industry enterprises undergo departmental verification, as a rule, once a year. The exceptions are potentiometers and bridges, ammeters and voltmeters, milliammeters, millivoltmeters, wattmeters and phase meters, which are verified every 6 months.
For measuring instruments in storage, the calibration intervals are determined equal to twice the calibration intervals for similar measuring instruments in operation. An exception is made up of measuring instruments that have entered storage after their release, for which the calibration interval should not exceed the manufacturer's warranty period, and measuring instruments that are stored in conditions that ensure their serviceability, and which are verified only before starting operation.
Measuring instruments are verified in accordance with state standards for methods and means of verification or according to the instructions of the USSR State Standard and the methodological instructions of its metrological institutes. In the absence of these regulatory documents, the developers of the corresponding measuring instruments should draw up methodological guidelines or instructions for their verification, which are approved by the head of the departmental metrological service of the enterprise using these measuring instruments, or by the head of a higher departmental metrological organization.
In the verification process, a protocol is kept, where its results are entered and the conclusion about the suitability of measuring instruments for use. A suitable device is sealed or stamped with a verification mark. The suitability of the device for operation during the calibration interval can also be certified by a certificate or other technical document. A note on the verification of instruments, indicating the date and its results, is made in the instrument passport or other document replacing the passport. Passports for measuring instruments are drawn up by the MS accounting group of the enterprise at the request of the technical service link of the enterprise. The passport contains detailed technical characteristics of the device, information on verification, operation and repair.
At some food industry enterprises, measuring instruments of non-serial production, import supplies, or serially produced measuring instruments with the introduced changes are used, as a result of which, in terms of metrological characteristics, they do not meet the requirements of regulatory and technical documentation. For such measuring instruments, the MC verification group of the enterprise carries out metrological certification, during which the nomenclature of metrological characteristics to be determined is established;
Numerical values of metrological characteristics; the procedure for metrological maintenance of instruments during their operation (certification or verification). Based on the results of metrological certification, a protocol is drawn up in two copies, which are signed by the group leader and performers. In case of a positive outcome of metrological certification, a certificate (certificate) is issued for each measuring instrument.
The MC verification group of a food enterprise, along with the listed functions, also performs a number of others:
provides storage and comparison in the established manner of working standards and standard samples of the composition and properties of substances and materials; maintains exemplary measuring instruments and ensures their operation;
monitors the state and application of SIA, product testing facilities, the availability and correctness of application of measurement procedures and compliance with metrological rules in all divisions of the enterprise;
performs acceptance and certification of non-standardized SIA entering the enterprise;
monitors the metrological support of all production activities of the enterprise divisions, the implementation of plans for organizational and technical measures for the metrological support of their activities, the introduction of new SIAs into production.
7.4. MAINTENANCE
INSTRUMENTS AND AUTOMATION MEANS
The main tasks of maintenance are continuous monitoring of the operation of instruments and automation equipment and the creation of conditions that ensure their serviceability, operability and the required resource during operation. To accomplish these tasks, a link (group) of maintenance of automation systems and SIA, consisting of shift teams, is created as part of the metrological service.
The shift team of the MS of a food enterprise includes locksmiths on duty and a foreman (foreman or highly qualified worker of V-VI categories). MS shift personnel are part of the shift technological workshop and therefore has a dual subordination. Administratively and technically, he is subordinate to the chief metrologist, and operatively - to the shift supervisor (engineer on duty) of the technological department. Operational subordination consists in the fact that shift personnel perform work on the instructions or with the knowledge of the Shift Supervisor.
Maintenance work on automation systems includes the scheduling of maintenance and their implementation, as well as unscheduled maintenance associated primarily with the prompt repair or replacement of failed power lines; implementation of operational control over the state and operation of automation systems and SIA, ensuring their proper technical condition, including current repair of SIA and pipe routes, removal and installation of SIA for repair and verification; control over the correct operation and rational use of automation systems and compliance current regulations exploitation.
Operational control over the state and operation of automation systems consists in systematic daily or shift monitoring of the operation of the SIA installed both at control points and in production facilities in order to identify emerging malfunctions and prevent their development. These works are performed by visual observation of the state of the SIA. During such inspections, violations of the seals of connecting pipe lines and fittings are identified and eliminated, the instruments are examined and cleaned, the correct installation of the recorder diagram in terms of time and the value of the monitored value is checked, as well as the presence of the necessary records on the diagram (instrument positions and recording dates), replace the diagram , fill the pens of the recorders with ink, check the operation of switches, the presence of power and lubrication, control the operation of automatic regulators.
When changing diagrams and rolls of recorders for devices with an integrator, the time of their replacement and the readings of the integrator are put down on the diagram or roll, and first of all, the diagrams and rolls of the devices are changed, according to the readings of which they are calculating for the raw material or energy used. The control over the operation of automatic regulators is carried out by comparing the nature of the change in the regulated value with the readings and records of the instruments that control the values associated with the regulated one.
Maintenance(Maintenance) of automation systems and SIA, carried out in accordance with the maintenance schedule, which is approved by the chief engineer of the enterprise, includes the following operations:
External examination, cleaning from dust and residues of technological products, checking the serviceability of communication lines and the safety of seals;
Checking the performance by checkpoints, identifying and eliminating minor defects that have arisen during operation;
Replacing charts, cleaning recorders and refilling them with ink, lubricating motion mechanisms, refilling or changing special fluids, eliminating their leakage;
Checking the operation of the automation system in the event of a discrepancy in the course of the process and the readings of measuring instruments;
Flushing the measuring chambers, filling differential pressure gauges with mercury, correcting seals and fasteners, checking selected pressure and flow devices, etc.;
Drying of SIA elements and cleaning of contacts;
checking refrigerators, filters, water-jet pumps, power supplies, indicating and registering units for measuring the composition and properties of substances;
cleaning, lubrication and testing of relays, sensors and regulator actuators;
check for the density of impulse and connecting lines, replacement of faulty individual elements and assemblies;
checking the availability of power in the control and signaling circuits, testing the sound and light signaling;
checking the operation of the circuits and the correctness of the tasks for their operation;
inspection of automation panels, interlocking devices, alarm and protection equipment.
The maintenance intervals are on average once every
I-2 months For counters of the amount of liquid and gas, pipe differential pressure gauge, hydraulic regulators of vacuum, pressure and flow with a membrane measuring device, hydraulic actuators, a regulator for electronic control devices, electrical measuring instruments and relay equipment, the frequency of maintenance can be increased to 6 months, and for air reducers , pneumatic remote control panels, control valves with pneumatic diaphragm or electric motor drive, electric actuators, direct-acting gas or fuel oil pressure regulators, pneumatic control units, induction flow meters, thermocouples and resistance thermometers - up to 3 months. Converters of pH meters and mass measuring devices are subject to maintenance once every 10 days. In rooms where the temperature long time exceeds 30 ° C, the frequency of planned work is reduced by 2 times, in dusty rooms (process dust penetrates into the equipment) - by 3 times, in rooms with a chemically active (relative to insulation and other parts of the equipment) environment - by 4 times.
In accordance with the scheduled preventive maintenance (PM) schedules, shift personnel also replace devices sent for repair. The procedure for carrying out scheduled work during the shift is regulated by the job descriptions of the shift personnel of the MS.
Maintenance link along with maintenance and operational control participates in the consideration of the causes of accidents due to failures of automation systems and SIA and the development of measures for their elimination; organizes and trains production personnel in the rules of technical operation of automation systems and SIA; controls the quality of installation and commissioning and their compliance with technical documentation when performing these works by specialized organizations; participates in testing and commissioning of newly installed and adjusted automation systems from installation and commissioning organizations; carries out adjustment work before the launch of seasonal production and when introducing new and improving existing automation and power systems; improves the organization of maintenance of automation systems.
During the shift, an operational log of the duty personnel is kept, in which all cases of failures of devices and automation equipment are recorded, regardless of the reasons their occurrence, Taken measures on elimination of failures, operational switching, replacement of devices and automation equipment, technical inspections and other work performed by the duty officers. The delivery and acceptance of shifts is documented by the signatures of the senior officers on duty in the operational log. The person who handed over the shift should draw the attention of the receiver to the bottlenecks of the automation system.
The shift personnel must have specific production skills and knowledge. Therefore, the attendants are preliminarily instructed on safety precautions and a knowledge test on the automation system of the technological object that them to be serviced. The attendants should be well aware of the technological scheme of the industrial complex being serviced, the process of managing it, the layout of the technological equipment and pipelines, the purpose of each element of the automation system, the location of the primary perceiving elements and regulatory bodies ^ devices in place, their interconnection, the location and direction of the routes.
For the entire complex preventive work operation areas are equipped with portable laboratory instruments (potentiometers, bridges, resistance boxes, control manometers, voltammeters, mercury thermometers, megohmmeters, voltage indicators), tools (a set of plumbing tools, an electric drill, soldering irons, a portable lamp) and materials (ink and graph paper, wires and insulating tape, fasteners, dry electrochemical cells, cleaning material, lubricating oils, gasoline, kerosene, alcohol).
For maintenance, the locksmiths on duty additionally receive special devices and instruments for checking individual units and parts of automatic control and regulation devices. In addition, the operation area should have backup devices and automation equipment instead of those sent for repair in accordance with the maintenance schedule and those that have failed as a result of unplanned failures. The group of accounting, storage and issuance of SIA closely interacts with this MS division, which creates an exchange and rental fund of SIA, maintains their technical records, etc.
COMPUTER SYSTEMS AND EQUIPMENT
Computer maintenance includes a set of organizational and technical measures to ensure the required reliability parameters. It can be individual and centralized. In the first case, the composition of the shift serving the computer is completed taking into account the considerations given in clause 7.1. With centralized service, maintenance is carried out by special centers under contracts concluded with enterprises.
When servicing systems and facilities computing technology also distinguish between scheduled and unscheduled work. Scheduled work is carried out in accordance with the schedule of planned preventive work (PM), which determine the frequency, schedule and type of work. For example, for the EC-1030 machine, the following regulations and frequency of PPR (in hours) are recommended: daily check 1, two-week 4, monthly 8 and semi-annual 72.
Daily preventive maintenance usually includes inspection of devices, running a quick check test their operability, as well as cleaning, lubricating, adjusting and other work provided for in the instruction manual for external devices. Every two weeks, a run of diagnostic tests is carried out, as well as all types of two-week preventive maintenance provided for in the instructions for external devices. The functioning of the technical means of the machine, which are part of its software, is checked monthly at rated voltage values and preventive changes by ± 5 %. Defective standard elements are replaced with serviceable ones. The same work is carried out with six-month prophylaxis. During the monthly and semi-annual maintenance, the corresponding maintenance work is also carried out, provided for in the instructions for the operation of external devices.
To work on the maintenance of computers are allowed specialists who have passed exams on computer devices, circuit documentation and technical description, who have studied the operating instructions and received a certificate of the right their exploitation. To carry out the entire complex of preventive work, maintenance personnel are provided with fault diagnostics, spare tools, instruments, parts, etc. (spare parts), service equipment for checking external devices, replaceable functional units and power supplies. The service equipment includes stands for testing power supplies, logical and special typical elements, cells of external devices.
The main operational documents of a computer are the form "instructions for the operation of computers and devices, manuals for the operation of diagnostic and functional tests, diagnostic reference books and a computer operation log.
7.5. REPAIR WORKS
INSTRUMENTS AND MEANS AUTOMATION
Repair work is carried out in order to eliminate defects that have caused a change in the technical characteristics of instruments and automation equipment. For measuring instruments, these are primarily metrological characteristics, as well as appearance device (state of the reading device, housing and its elements, connecting and auxiliary devices). Requirements for the technical characteristics of instruments and automation equipment are regulated by the normative and technical documentation.
The repair of instruments and automation equipment at a food enterprise is carried out by the repair group of the metrological service. In the absence of subdivisions in this group that carry out the repair of some measuring instruments, the repair of the latter is carried out in special instrument-repair organizations that have a registration certificate from the USSR State Standard bodies for the right to repair measuring instruments.
There are scheduled repairs, which are carried out according to the maintenance schedule, and unscheduled ones. The need for the first is due to constant change characteristics of devices and automation equipment as a result of wear and tear. Wear is associated primarily with a change in the state of rubbing surfaces and the size of products, contamination of kinematic units in the junction points arising under the influence of an electric current by electrochemical processes, etc. However, even in an inoperative state, instruments and automation equipment are subject to aging associated with irreversible chemical changes.
The rate of wear and aging processes depends primarily on the operating conditions of instruments and automation equipment: ambient temperature and humidity, dust content, the presence of aggressive vapors and gases, the action of magnetic and electric fields, vibration and various radiation. In constant operating conditions, the influence of all the listed factors can be assessed from the point of view of determining the planned overhaul intervals that ensure the operation of instruments and automation equipment, provided that the specified functions are performed normally.
Premature failure of devices and automation equipment occurs as a result of overloading the device due to improper switching on or careless handling. Such types of failures are detected either directly as a result of work, or during periodic verification of measuring instruments. In this case, unscheduled repairs are required.
Scheduled repair of devices and automation equipment is most often carried out during the repair of technological equipment after the end of the season for processing food raw materials. It is advisable to carry out unscheduled repairs with the replacement of the repaired instruments and automation equipment with backup devices.
Instruments and automation equipment sent for repair must be accompanied by passports, certificates or other technical documents on the verification (if any) and defective labels indicating the type of repair (planned or unscheduled). In the event of an unscheduled repair, the label indicates the nature of the malfunction that caused the repair.
Depending on the nature of the device malfunction and the extent of damage, a distinction is made between current and overhaul repairs. The first is usually carried out at the installation site of the device by the repair personnel, but it can also be carried out in a repair shop. Routine repair is the minimum type of repair in terms of the volume of work performed, in which the normal operation of measuring and automation devices (SIA) is ensured. Along with the maintenance work of the SIA, current repairs include the following work:
Partial disassembly and assembly of measuring systems with the replacement of individual unusable parts (rings, screws, arrows);
Partial disassembly and adjustment of moving systems, repair or replacement of damaged parts (springs, tubes, screws, fasteners), cleaning and lubrication of units;
Replacement of SIA elements that have exhausted their resource, elimination of minor breakdowns;
Checking the quality of insulation and the state of the measurement and power supply circuits of the SIA;
Correction of seals, elimination of backlash in individual mechanisms, stuffing of oil seals, replacement of glasses and scales;
Elimination of malfunctions in the joints of moving parts.
At food enterprises, most SIAs are subject to routine repair once every 6 months, and temperature measuring devices and gas analyzers - every 4 months. Verification completes the current repair.
Overhaul of SIA is carried out in an MS repair shop or in a specialized organization. Devices that have significant wear of parts, as well as damage, and therefore require restoration of a full or close to full service life with the replacement or repair of any parts or assemblies, are exposed to it.
At overhaul along with the execution of a part of the work included in the current repair, the following work can also be carried out:
Installation and adjustment of new scales or dials;
Repair of the case with straightening of the mounting surfaces;
Complete disassembly and assembly of the measuring part and individual units, flushing, repair or replacement of parts (thrust bearings, springs, suspensions, weights, etc.), repair of units or their complete replacement;
Dismantling and assembly of mechanisms for recording SI, their revision, cleaning and replacement;
Checking the measuring circuit of the measuring instrument (MI), adjusting and adjusting the readings by control points, preparing the measuring instrument for delivery to the verifier.
The overhaul of the SI at a food enterprise is usually carried out every 12 months. The MS repair group also issues applications to the company's divisions for the manufacture and purchase of parts, materials and spare parts for the repair of the SIA.
WIRING AND EQUIPMENT
Repair of wiring and equipment includes dismantling, repair and installation of selected devices and units for installing primary sensing elements built into technological equipment, pipe wiring and cable lines, panels, consoles, etc. central MS - a group of installation and commissioning during the shutdown and repair of technological equipment.
The shutdown of technological equipment can be emergency and planned. The first is usually short-lived. Therefore, during this period, priority urgent work is performed that cannot be performed during the normal operation of the installation. At the same time, those nodes of automation systems are subject to inspection and verification, the serviceability of which raised doubts during the current maintenance of instruments and automation equipment. The results of emergency installation and repair work are recorded in the operational log of the duty personnel.
In case of a planned shutdown of the technological unit in accordance with the current instructions and instructions, the shift supervisor sequentially turns off the devices and automation equipment, about which notes are made in the operational log. Installation and repair work is started only after a complete shutdown of the process unit and shutdown of devices and automation equipment. First, they dismantle those devices and automation equipment, cable and pipe wiring, which, due to their location near technological equipment and pipelines, can be damaged during repairs.
Installation- renovation work are carried out on the basis of a defective statement, which indicates the sequence and timing of work, and the general schedule for the repair work. When compiling a defective statement, the comments of the operating personnel are taken into account.
With a planned shutdown, installation and repair work is carried out in the following sequence. First of all, they perform work that cannot be performed on the operating technological equipment, which is associated with a violation of the tightness of the technological equipment and pipelines. These include the repair of selection devices, regulating bodies, orifices, pipe wiring connected to selection devices without shut-off valves, etc. Secondly, work is carried out, the performance of which on existing equipment is associated with significant difficulties or danger, such as , repair of connecting routes laid in hard-to-reach places with high ambient temperatures. In the third stage, repair work of automation systems is carried out, for which there is no operational reserve, and then all other installation and repair work. The results of planned installation and repair work are recorded in a defective statement or special journals.
CONTROL QUESTIONS To chapter 1
1. Name the types of technical documentation.
2. What are the main sections of the project you know?
3. In what modes can the APCS function?
4. How is the design of local automation systems carried out?
5. How is the design carried out automated systems management?
To chapter 2
1. What are structural diagrams?
2. What tasks are solved during the design structural diagrams management and control?
3. What is an automation scheme?
4. What are the tasks of designing automation schemes.
5. How are measuring instruments selected?
6. How is the selection of control devices carried out?
7. What is the order of execution of automation schemes?
8. What is a schematic diagram?
9. What are the requirements for schematic diagrams?
10. What kind of management is called centralized?
11. What is the algorithm of the circuit?
12. What are the methods for developing a structural diagram.
13. What requirements should be considered when moving to a schematic diagram?
14. How should the elements be depicted on circuit diagrams?
15. What are the features of the development of fundamental pneumatic schemes.
16. What are the tasks of designing power supply systems.
17. How is the implementation of electrical power supply circuits?
18. How is the choice of the type and design of boards and consoles carried out?
19. What are the methods of making the wiring diagrams of the internal panel wiring.
20. What are the tasks in the design of electrical wiring? pipe wiring?
To chapter 3
1. Name the types of ACS support.
2. What structures of APCS do you know?
3. Name the functions of the operating personnel of the automated process control system.
4. What is included project documentation for organizational support?
5. What subsystems are included in the technical support?
6. What documents are included in the project documentation for the technical support of the process control system?
7. What is the structure of the software?
8. Name the operating systems.
9. What concerns information support?
10. What is metrological support?
11. What are the characteristics of technological complexes?
To chapter 4
1. What types of support are typical for computer-aided design systems?
2. What caused the need to create a CAD system?
3. Name the CAD levels.
4. Name the tasks of CAD methodological support.
5. What are the main types of computer technology you know?
6. What is a workstation?
7. What are the specific operators of the BASIC language,
8. How is the information modified?
9. What are the principles of preserving mathematical and software.
10. How are graphic operations implemented on a microcomputer?
11. Describe the technique of using primitives when entering graphical information.
12. What is the arrangement of the equipment according to panels and consoles?
13. What are the placement objectives?
To chapter 5
1. How are the installation and commissioning works organized?
2. How are selected devices and primary measuring transducers mounted?
3. How is the installation of devices, regulators and actuators carried out?
4. What are the stages of setting up local automation systems.
To chapter 6
1. What is the organization of work during the installation and implementation of ACS?
2. Name the stages of work during the installation of the automated control system.
3. What is included in the installation project?
4. What are the stages of setting up technical means.
5. Name the types of debugs.
6. What methods do you know for detecting and localizing errors in software complexes?
7. What is testing and what is it? kinds of it?
8. What is the complex commissioning and debugging of the system?
To chapter 7
1. Name the tasks of operating devices and automation equipment.
2. What does the metrological support of the automation systems operation service include?
3. What is the verification of measuring instruments?
4. What is the purpose of the primary standard?
5. What are the tasks of maintenance of the automation systems operation service?
6. Name the purpose and means of repair work.
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