Technological properties of metals and alloys depend on the chemical composition. Technological characteristics Definition and characteristics

22. Main technological characteristics of buildings

For organizing SMEs, it is recommended to use one-story buildings, because in this case, the installation of technological equipment is facilitated, and transport connections between workshops are simplified. A multi-storey building is designed with small equipment. When choosing a building, determine the footprint. characteristics - span height, span length, column grid, which is characterized by span width and column spacing. Typically a building has 1 or more spans. A span is a part of a building limited in the longitudinal direction by two rows of columns. The span width is the distance between the axes of the columns in the longitudinal direction. Span height - the distance from the floor level to the bottom of the load-bearing structures of the building's roof.

The width of the building span is chosen such that it is possible to rationally place an even number of rows of machines, depending on the overall dimensions and placement option. The column spacing for most building schemes is 12 m for internal rows of columns and 6 m for perimeter columns of the building. Column grid for one-story craneless buildings 12x6, 18x6, 18x12, 24x6, 24x12.

For one-story buildings equipped with overhead cranes up to 50 tons 18x6, 18x12, 24x6, 24x12, 30x12.

Span length L = n*t, where n is the number of steps, t is the pitch of columns. The span length is determined by the length of the technological line of the installed equipment. The length of production lines is greater than the length of a highly specialized section of non-production production. For mechanical workshops of the automotive industry, it is recommended to limit the length of the production line to 50-60 m. If it is necessary to have a longer length, the flow usually changes its direction.

23. Selection of the optimal layout of a workshop for continuous, large-scale and mass production

In continuous and large-scale production, subject-specific workshops have the following layout diagrams. The MSC consists of a number of parallel machining sections of alternating or continuous production lines and a line or section of the unit assembly. The subassembly workstation is located at the end of the machining line. During conveyor general assembly, the machining and subassembly areas are placed in accordance with the sequence of installation of the assembly unit. and parts in the product on the main conveyor located perpendicular to the machining lines after the unit assembly at the end of the body (a) or in the middle (b). This ensures the principle of direct production. Option b is used in the production of products with a large number of short machining lines and relatively low labor intensity of the overall assembly. When choosing a layout for a new building, the following principles are adhered to:

1) an industrial building should be designed with spans of the same direction, the same width and height;

2) the industrial building must be rectangular in shape.

24. Selection of the optimal layout of a workshop for small-scale and individual production

In serial and individual production, layout schemes are used with the general assembly shop located in a separate bay parallel or perpendicular to the mechanical bays. They use a non-flow stationary assembly, so the relative placement of the mechanical sections. determines to a greater extent the technological homogeneity of the processed parts and the types of transport used. The general assembly area must be equipped with an overhead crane to enable the assembly of large, heavy products. In addition, one of the flights of mechanical equipment. in which equipment for the production of heavy parts is concentrated. equipped with an overhead crane. With a parallel arrangement of spans, it is advisable to locate the section of basic parts nearby in order to minimize cargo flows.

It is not advisable to locate processing areas for high- and low-precision parts nearby due to the inevitable influence of vibrations from imprecise equipment on the accuracy of manufacturing critical parts. The adjacent placement of abrasive processing and assembly areas is also unacceptable (abrasive dust settles on the parts). Fire hazardous or hazardous areas must be isolated from other industries by partitions and equipped with air purification systems.

25. Preliminary determination of workshop area

During the preliminary development of the layout diagram, the total area of the site (shop) So is determined by the indicator of the specific area of the workshop, the site - the area per 1 machine or one workplace. So = Sud.o.*Sprin, where Sprin is the accepted number of machines in the workshop (the number of jobs for assembly) Sud.o. depends on the overall dimensions of the equipment and vehicles used. For medium-sized machines 18...22 m^2 with the largest dimension 4 m, for small machines 14...18 m^2 1.8 m.

26. Selecting an option for the location of equipment for continuous and variable flow lines

The sequence of equipment placement is almost unambiguously determined by the sequence of TP operations. The task of placing equipment comes down to choosing the option for placing machines relative to the vehicle, determining the number of rows of machines and the general configuration of the production line.

Regarding the vehicle:

1) longitudinal placement. The layout provides favorable conditions for mechanization and automation of interoperational transport (conveyor), but if there is equipment of different sizes, the layout may turn out to be non-compact

2) Transverse arrangement - provides greater compactness, but the workplace is removed from the conveyor with parts, it is difficult to implement a chip conveyor. The scheme is rational for the use of robots.

3) The corner location is used to ensure a more compact layout.

4) The ring arrangement is rational for multi-machine service. Difficulties in using interoperational transport.

Depending on the length of the technological flow and the length of the machine section, single-row or multi-row placement of machines is used. At the same time, to ensure the direct flow of the production process, the beginning of the line (workpiece zone) is located on the side of one passage, and the end of the line on the opposite side. The following placement options are used: single-row, sequential placement, production lines with a large number of machines are placed in several rows so that the beginning of the line is located on the side of the workpiece area, and the end on the opposite side, an odd number of lines.

The position of the element in the Periodic Table, i.e. the structure of the electronic shells of atoms and ions ultimately determines all the basic chemical and a number of physical properties of a substance. Therefore, a comparison of the catalytic activity of solids with the position in the Periodic Table of the elements that form them led to the identification of a number of patterns in the selection of catalysts.

Share your work on social networks

If this work does not suit you, at the bottom of the page there is a list of similar works. You can also use the search button

Classification of technological indicators of catalysts. Basic technological characteristics of heterogeneous catalysts. Laboratory methods for their determination.

3.1 Classification of technological indicators of catalysts.

In catalysis, the most fruitful ideas are those that take into account the chemical correspondence between the catalyst and the catalyzed reaction.

For general orientation in the selection of catalysts, it is useful to classify catalytic processes according to the mechanism of action of the catalysts.

When creating a new solid catalyst or improving an existing catalyst, the following basic parameters for catalysts must be taken into account:

Physico-mechanical;

Chemical;

Operational and economic.

The physical and mechanical properties or parameters of the catalyst include porosity, bulk density, true density, specific surface area, average pore volume and pore radius distribution, fractional composition, particle size, amorphousness or crystallinity, particle shape, heat capacity, heat resistance or water-vapor resistance. , the ability to poison and regenerate.

The chemical parameters of catalysts include the chemical composition, impurity content, ability to activate (promote, modify) and poisoning by poisons, form alloys, modifications and phases, graft activators to the surface of solid catalysts.

Operational and economic indicators or properties of catalysts are activity and selectivity, easy regenerability from various deposits and inclusions (coke, oxides, reversible poisons), the possibility of creating simple methods for synthesizing the catalyst on an industrial scale, increased heat capacity, bulk density, low sensitivity to poisons, long operating time in the reactor without regeneration, ease of transportation and storage, ease of separation from the reaction mixture, availability of raw materials for catalyst production and environmental friendliness.

Technological characteristics of solid catalysts.

Selecting catalysts for industrial processes is an extremely complex task. Catalysts are very specific to different chemical reactions. Existing theories of catalysis explain this specificity by a number of energetic and geometric factors, as a result of which a given catalyst affects the rate of only one reaction or a very narrow group of reactions. It is not always possible to strictly scientifically select a specific catalyst for a given chemical technological process, although the theory of catalytic processes has received significant development in recent decades and is characterized by many new achievements.

Solid catalysts are, as a rule, highly porous substances with a developed internal surface, characterized by a certain porous and crystalline structure, activity, selectivity and a number of other technological characteristics.

3.2 Main characteristics of solid catalysts.

3.2.1 Activity.

When comparing different catalysts, the more active one is usually chosen if it meets the basic technological requirements.

Catalyst activity is a measure of the accelerating effect on a given reaction.

To quantify activity in industrial conditions, determine:

general transformation of feedstock;

yield of the target product;

rate of transformation of a certain amount of raw materials per unit of time;

per unit mass of catalyst;

per unit volume of catalyst;

per unit surface area of the catalyst;

per single active center, which is of scientific interest as an objective criterion for comparing the activity of identical or different catalysts.

Due to the wide variety of catalytic processes, there is no single quantitative criterion for activity. This is due to the fact that the use of different catalysts, even for the same chemical reaction, can change its mechanism differently. As a rule, the use of a catalyst leads to a change in the reaction order, activation energy, and pre-exponential factor.

A quantitative criterion for the activity of a catalyst for a given reaction can be, for example, a rate constant measured for different catalysts under comparable (standard) conditions. This approach is applicable if the reaction order remains the same for all compared catalysts of a given group.

If the catalytic reaction has the same order as the non-catalytic one, i.e. their rate constants k kt and k have the same units of measurement, then the activity of catalyst A can be defined as the ratio of constants

where E° and E are the activation energies of catalytic and non-catalytic reactions, exp is the exponential factor.

From the equation of the exponential dependence it follows that the higher the activity, the more the activation energy decreases in the presence of a catalyst. However, it must be kept in mind that in the presence of a catalyst, not only the activation energy changes, but also the pre-exponential factor. An increase in activity due to a decrease in activation energy is restrained by a decrease

K o km compared to K O (there is a so-called compensation effect).

Sometimes catalysts are compared by reaction rate or by the degree of conversion of reagents under standard conditions, by the number of reagents that interact per unit time on a unit surface of the catalyst (productivity, or tension, of the catalyst), etc.

The activity of a catalyst for a process occurring in the kinetic region is determined, first of all, by the nature of the reagents and the specificity of the catalysts, i.e. The activity of a catalyst corresponds to its activity in a chemical reaction.

However, in cases where the rates of the chemical and diffuse stages of catalysis are comparable, the activity of the catalyst does not coincide with its activity in the chemical reaction.

To compare the activity of a catalyst in a reaction under different conditions, the intensity of the process on a given catalyst is used as a measure of activity. It is expressed by the amount of product obtained per unit of time from one volume of catalyst.

A = G ave. / (V cat. t) 3.2

Or per unit of weight

A beat = G pr /(G cat t) 3.3

The activity of different catalysts in this process under given standard conditions is compared by the degree of conversion of the main substance, and the activity is determined by the degree of conversion.

The main factors affecting the activity of catalysts.

Catalyst concentration There is almost always an excess of catalyst in the reaction system, because part of the catalyst mass either does not participate at all in the reaction or participates only slightly.

Concentration of activator or promoter if the amount of activator or promoter is high, then some of the active sites of the catalyst are screened and the overall activity decreases.

Concentration of starting substances if they differ greatly from the required substances in the reaction, then the limiting stages of the process can be replaced, i.e. for example, a transition from the external diffusion region to the kinetic region or vice versa.

The concentration of the products formed - usually an increase in concentration slows down the overall reaction rate, because in this case, the adsorption equilibrium shifts and the surface of the catalyst occupied by the product increases. This surface is either excluded from further operation of the catalyst, or, even worse, secondary side reactions begin to occur on it.

A strong increase in the concentration of products sometimes leads to complete poisoning of the catalyst. Sometimes these phenomena occur so quickly that after 5 15 minutes the catalyst is inactive and requires regeneration.

Example: Catalytic cracking, residence time 15 30 minutes.

Impurity concentration Impurities always reduce the reaction rate. If the impurities are inert, then this decrease is not significant; if these are “contact poisons,” then their influence is very strong; preliminary purification of the raw materials is necessary.

Medium temperature and pressure this influence is ambiguous for each reaction in its own way.

T has a significant impact on the rate of the process occurring in both the kinetic and diffusion regions.

A series of catalytic processes are carried out at elevated pressure to shift the equilibrium towards the product.

Structural characteristics of catalysts the general trend is that fine-pored catalysts are preferable.

The molecular weight of the starting substances this factor has almost no effect when occurring in the kinetic region, slightly in the external diffusion region, and strongly in the internal diffusion region.

3.2.2 Selectivity (selectivity) of catalysts.

Selectivity is especially important for multi-route parallel reactions, as well as for reactions of a series of sequential transformations.

Complex catalytic reactions can proceed along several thermodynamically possible directions with the formation of a large number of different products. The predominant course of the reaction depends on the catalyst used, and the process that is thermodynamically the most favorable of several possible ones is not always accelerated.

From a number of thermodynamically possible reactions, a selective catalyst should accelerate only the reaction to obtain the target product. Typically, as a result of the action of a selective catalyst, the temperature of the target transformation is lowered and side reactions are thereby suppressed.

The selectivity or selectivity of a catalyst is its ability to selectively accelerate the target reaction in the presence of several side reactions.

The selectivity of a catalyst can be quantitatively assessed as the selectivity of the process - integral or differential. If several parallel reactions occur simultaneously, then different selective catalysts can be selected for each of these reactions.

For example: in the presence of aluminum oxide or thorium oxide, ethanol decomposes predominantly into ethylene and water:

C 2 H 5 OH ---> C 2 H 4 + H 2 O

In the presence of silver, copper and other metals, practically only the dehydrogenation reaction of alcohol takes place with the formation of acetaldehyde:

C 2 H 5 OH ---> CH 3 CHO + H 2

In the presence of a mixed catalyst (A1 2 Oz + ZnO ) dehydration and dehydrogenation reactions occur with fairly high selectivity to form butadiene:

2 C 2 H 5 OH --->C 4 H 6 +2H 2 O + H 2,

Selectivity depends not only on the selected catalyst, but also on the conditions of the process, on the area of the heterogeneous catalytic process (kinetic, external or internal diffusion), etc.

An example of the selective action of catalysts is the oxidation of ammonia during the production of nitric acid.

Several parallel and sequential reactions are possible:

4 NH 3 + 3 O 2 = 2 N 2 + 6 H 2 O + 1300 KJ;
4 NH 3 + 4 O 2 = 2 N 2 O + 6 H 2 O + 1100 KJ;
4 NH 3 + 5 O 2 = 4 N O + 6 H 2 O + 300 KJ;

The 3rd reaction is more active on Pt catalyst; oxide catalyst 1 and 2 the same.

Selectivity is estimated using the following formula:

A > B + C,

Where B target, C secondary.

S = ,

The overall selectivity of the catalyst can be expressed by the ratio of the amount of the target product (B) to the total amount of target and by-products (C).

Selectivity is affected by the same parameters as activity, but the nature of the influence of the parameters is somewhat different:

Selectivity, as a rule, decreases with increasing time of contact of the reagents with the catalyst, i.e. with a decrease in the volumetric feed rate of raw materials, especially for those reactions in which the target product is intermediate: A --- B --- C.

Space velocity determines the achievement of equilibrium in the system, the direction of reactions and the yield of products.

It represents the ratio of the volume of the gas mixture, reduced to normal conditions (n.s.), passing per unit time to the bulk volume of the catalyst.

V = V g.s. / V cat. 3.4

Example:

Let's consider systems for converting n-paraffins.

At high temperatures and low speeds of n-paraffins C 6 C 8 turn into Pt catalysts, the main reaction is the reaction of aromatization or dehydrocyclization of n-paraffins.

At high temperatures and medium speeds, Pt catalysts, the main reaction is an isomerization reaction, n-paraffins are converted to olefins and isomerized. Since the speed is higher in the 1st case, cyclization does not have time to occur.

At high temperatures and high speeds, the hydrocracking process paraffins are split, olefin radicals are saturated with hydrogen and converted into other paraffins, but since the speeds are high, the resulting paraffins do not have time to isomerize or cyclize.

Temperature influences these processes much like volumetric velocity. At high temperatures monocyclic A r hydrocarbons, when the temperature rises to 500 O C - bicyclic A r hydrocarbons.

The interaction between the catalyst and the environment is not limited to the influence of the catalyst on the reagents, but there is also feedback between the environment and the catalyst. We can talk about the catalytic activity of the entire system, including the contact mass and the reaction mixture.

In a catalyst, under the influence of the environment, the following can change: surface condition; structural characteristics of the contact mass; chemical composition and properties of the entire volume of the catalyst without the formation of new phases; chemical composition with the formation of new phases.

3.2.3 Ignition temperature.

Along with activity and selectivity, an important technological characteristic is the ignition temperature of the catalyst Tzazh.

The concept of “ignition” means that when the temperature increases above a limit equal to Tzazh, a sharp, abrupt increase in the reaction rate occurs. “Ignition” can also occur in non-catalytic reactions.

Ignition temperature is the minimum temperature at which the technological process begins to proceed at a speed sufficient for practical purposes.

Catalyst ignition temperature is the minimum temperature at which the catalyst has activity sufficient to carry out the process in an autothermal mode under industrial conditions.

This factor is primarily taken into account when carrying out high-temperature reversible reactions in adiabatic fixed-bed reactors.

An adiabatic reactor is a system that is deprived of the possibility of supplying it from the outside or discharging it into the environment.

When graphically solving the system of equations for the material and heat balances of a flow reactor when an exothermic reaction is carried out in it. Let us assume that the relative position of the lines describing the equations of material and heat balances corresponds to that shown in the drawing, i.e. line 2 of the heat balance equation is tangent at point A to line 1 of the material balance equation. Then a small change in the initial temperature at the reactor inlet from T 1 - T to T 1 T will lead to an abrupt change in the degree of conversion achieved in the reactor from X A;1 to X A,2 . This means that at the same values of the reactor volume and the volume flow of reagents through it, a sharp increase in the reaction rate (and at the same time the rate of heat release) occurred.

Therefore, temperature T 1 and is the ignition temperature. Numerical value of T 1 in the drawing (and, accordingly, the position of point A) is determined primarily by the kinetic features of the reaction, affecting the position of line 1 of the material balance equation. Since each catalyst is characterized by its own kinetic parameters, the ignition temperatures will be different for different catalysts.

Drawing. Joint solution of the equations of material and heat balances of a flow reactor:

1 material balance equation line; 2line of heat balance equation

From a technological point of view, it is better to use catalysts with a low ignition temperature, which reduces energy costs for preheating the reaction mixture.

For exothermic reactions, the concept of “ignition temperature” can be specified quantitatively. The lower the temperature of the process, the lower the reaction rate and the less heat generated. At a certain minimum temperature (ignition temperature), the rate of heat release becomes equal to the rate of heat removal (heat consumption for heating the initial reaction mixture and heat removal with reaction products). Thus, the ignition temperature for exothermic reactions is the minimum temperature at which the process can be carried out in an autothermal mode, without supplying heat from the outside.

It is especially important to have a low ignition temperature of the catalyst when carrying out reversible exothermic reactions, then low temperatures of the process make it possible to shift the equilibrium of the reaction towards its products.

3.2.4 Catalyst service life.

The service life of the catalyst is extremely difficult to estimate in laboratory conditions, because catalytic activity is characterized by many factors that are difficult to take into account in the laboratory, for example: coking; chemical poisoning; recrystallization, in the case of using a carrier having a crystalline structure.

The service life of the catalyst can be expressed:

In units of time (for example: for catalytic cracking - several seconds, and ammonia synthesis - several years);
In the intermediate time between regeneration or the total duration until complete loss of activity.

Resistance to oxidative regenerations: the total service life of the catalyst divided by the period between regenerations.

The mass of product obtained during the entire operation of the catalyst.

Sometimes it is more profitable to replace a catalyst that has residual activity than to keep it in the reactor until it completely loses activity.

Catalyst reloading costs

Duration of work

The longer the catalyst has worked, the lower the cost of replacing it, but this should be correlated with the activity of the catalyst; it decreases with the duration of operation.

When replacing a catalyst with a new one or seeking intensification, the following factors should be considered:

Easy to replace catalyst;
Dimensions of industrial reactors;
Cost of replacing catalysts;
Losses associated with a decrease in the total power of the catalysts;
Difficulty in preparing new active catalysts.

3.2.5 Thermal conductivity of catalyst grains.

The thermal conductivity of catalyst grains helps to equalize the temperature in the catalyst layer and reduces the temperature difference in an adiabatic reactor.

If the thermal effect is very high, then the thermal conductivity of the catalyst, in addition to activity, is the most significant factor, because such a catalyst is able to eliminate local overheating, which leads to a decrease in product yield due to the fact that coke formation occurs in the area (in isothermal conditions).

And in exothermic processes, low thermal conductivity leads to the following: the adsorption of raw materials on the catalyst grains is disrupted and capillary condensation of raw material vapors and reagents in the pores of the catalyst begins - all essentially in a fixed layer.

3.2.6 Strength and wear resistance.

Strength and wear resistance should ensure normal operation of the catalyst for several years.

In a fixed catalyst bed, strength loss occurs for the following reasons:

1. due to temperature changes;

2. due to erosion of the catalyst grain by a gas or liquid flow of reagents;

3. due to the pressure of the layer of overlying catalyst grains.

The crushing strength of fixed bed catalysts should be 0.7 11 MPa.

In a moving catalyst bed, strength refers to the wear resistance of the catalyst grains during friction and impacts against each other, against the walls of the reactor, regenerator, elevator or pipeline.

Wear resistance is characterized by two reasons: abrasion strength and splitting strength.

The relationship between strength and cleavage determines the strength of the catalyst in the fluidized bed.

The concept of “catalyst consumption per ton of raw material” or catalyst consumption per ton of freshly loaded catalyst is introduced.

3.2.7 Catalyst cost.

The cost of the catalyst is a small percentage of the cost of the resulting product.

The reforming catalyst costs 300,000 0.01% of the total cost of the reforming process.

Catalyst components are very expensive Pt.

Ways to reduce cost:

1.Applying an expensive catalyst component to a carrier;

2. Rational technology of its production.

All these consumer characteristics are determined by two factors:

Composition of contact masses;
Porous structure.

Other similar works that may interest you.vshm>
6300.		Requirements for carriers of industrial heterogeneous catalysts. Basic media types. Their physicochemical characteristics and technological properties	20.07 KB
	It is a mixture of sodium potassium calcium aluminum magnesium iron silicates. Before use, iron and aluminum impurities are removed from pumice with acids. Aluminum oxides. αА12О3 corundum is the most stable form of aluminum oxide containing approximately 99 А12О3 and a small amount of impurities of titanium and silicon oxides.
6303.		Basic requirements for the selection and synthesis of catalysts. Composition of contact masses. Main types of promoters. Concepts about the active component, carrier (matrix) and binder of heterogeneous catalysts and adsorbents	23.48 KB
	Along with the chemical composition, an active catalyst requires a high specific surface area and an optimal porous structure. Note that to obtain a highly selective catalyst, a high specific surface area is not necessary. In particular, it is desirable to minimize the deposition of coke on the surface of the catalyst in organic reactions and to maximize the period of operation of the catalyst before regeneration. The preparation of the catalyst should be highly reproducible.
6302.		Physical properties of catalysts. Porosity of adsorbents and catalysts. Characteristics of a porous body	22.41 KB
	By adjusting the physical characteristics of the carrier or catalyst, the desired properties of the catalytic system can be achieved. Creating a catalyst and, accordingly, a carrier with optimal properties constantly forces us to look for a compromise solution between physical and chemical characteristics. The volume of a solid catalyst determines such physicochemical properties as bulk density and true density texture, which in turn depend on the polyhedral structure of the lattice of its packing and nature. They can completely...
6304.		Interaction of catalysts with the reaction medium. Reasons for deactivation and methods for regenerating catalysts	18.85 KB
	Changes in the composition of catalysts during the reaction can be as follows: 1 chemical changes leading to phase transformations of the active component; 2 changes in volumetric composition without phase transformations; 3 changes in the composition of the surface layer of the catalyst. Exposure to the reaction medium can lead to a change in the ratio of the components included in the catalyst, as well as to the dissolution of new components or partial removal of old ones. The stable composition of the catalyst is determined by the ratio of the rates of binding or consumption...
6305.		Main methods for the production of solid catalysts	21.05 KB
	Main methods for the production of solid catalysts Depending on the area of application of the required properties, catalysts can be produced in the following ways: chemical: using a double exchange reaction, oxidation of hydrogenation, etc. Solid catalysts synthesized in various ways can be divided into metallic amorphous and crystalline simple and complex oxide sulfide. Metal catalysts can be individual or alloy. Catalysts can be single-phase SiO2 TiO2 А12О3 or...
12003.		Development of polymetallic catalysts	17.67 KB
	The process of producing polymetallic catalysts includes three stages: 1 autowave synthesis of SHS ingots of multicomponent intermetallic compounds based on CoMnl; 2 production of polymetallic granules by crushing an ingot; 3 chemical activation of granules and creation of an active, highly developed nano-sized structure. Polymetallic catalysts have shown high efficiency in the process of neutralization of combustion products of hydrocarbon fuels in the Fischer-Tropsch process and hydrotreating of diesel fuels and oils by cold oxidation of hydrogen in...
6306.		Fundamentals of industrial technology for the production of catalysts using the deposition method of contact masses	20.57 KB
	Depending on the precipitate that falls out, contact masses are conventionally divided into: 1. Dissolution, precipitation, filtration, washing of the precipitate, drying of the precipitate, calcination of the catalyst, grinding, dry molding. Dissolution, precipitation, filtration, washing of precipitate, molding of catalyst, wet drying, calcination. crystal growth this refers to crystalline precipitates in the case of amorphous: the enlargement of gel-like particles during their simultaneous formation.
11997.			38.77 KB
	The production of ethylbenzene occupies one of the leading places among petrochemical synthesis processes. More than 70 ethylbenzenes produced in the Russian Federation are obtained by a combined method of alkylation of benzene with ethylene and transalkylation of benzene with diethylbenzene using lCl3 as a catalyst. A pilot plant for the transalkylation of benzene with diethylbenzenes has been created; a production process using the promising nanostructured catalyst HYBS has been developed and tested in a pilot workshop.
17678.		Main characteristics and measurement methods	39.86 KB
	Measurement refers to the process of physically comparing a given quantity with a certain value taken as a unit of measurement. Measurement is a cognitive process consisting in experimentally comparing a measured value with a certain value taken as a unit of measurement. parameters of real objects; measurement requires experiments; To conduct experiments, special technical means are required - measuring instruments; 4, the result of the measurement is the value of a physical quantity.
6032.		Features of subjective and objective examination. Main symptoms and syndromes. Laboratory and instrumental examination methods. General characteristics of diseases of the genitourinary system	16.39 KB
	The human urinary system includes the urethra, bladder, ureters and kidneys. It regulates the amount and composition of fluid in the body and removes waste products (toxins) and excess fluid.

1. Scheme number: 1.

3. Span: L = 9 m.

6. Column pitch: R=12 m

7. Number of digital axes: 23pcs.

8. Step number: n-1=22 pcs.

10. Soil group: III.

V r

V pl

V upl

Slope diagram.

Composition of the complex process of zero-cycle work.

Technological sequence.

The production process of zero-cycle work, as a rule, includes:

Preparatory work:

1. breakdown of earthworks, m2;

2. uprooting of stumps and bushes, m2;

3. device for drainage, drainage, water reduction, m 2.

Excavation:

1. removal of the plant layer, m2;

2. soil loosening, m 3;

3. development of soil with a bulldozer or excavator, m3;

4. unloading soil into a dump or vehicle, m3;

5. soil transportation by dump trucks, m3;

6. development of soil shortage, m 3;

7. backfilling of sinuses (after erection of the underground part of the building), m 3;

8. soil compaction, m3.

Installation of the underground part:

1. arrangement of a leveling layer (sand, ready-mixed concrete), m 3 ;

2. installation of foundation slabs, m 3;

3. installation of concrete wall blocks (basement), m 3;

4. sealing joints of concrete wall blocks of the basement (concrete, mortar), m 3;

5. electric welding of embedded parts of welded reinforced concrete structures;

6. waterproofing of basement walls;

7. installation of floor slabs at elevation. 0.000;

8. sealing joints of floor slabs (concrete), m 3.

Layout of the structural part of the foundation

Based on the initial data, the structural part of the building foundations is assembled, the number of standard sizes of structures is determined and, in accordance with Appendix 17, prefabricated reinforced concrete structures are compiled according to Form 2.

Table 2 - Specification of precast concrete structures

№№	Brand of reinforced concrete structure	Main dimensions, mm	Volume of one element. Vel, m 3	Weight of one element. Q el, t	Number of elements N el	Total mass of elements.	Concrete class	Note	Total volume of elements.
	b	h
	F1				1,34	3,40			B22.5	L=9M	241,2
	F-2				1,70	4,85		87,3	B22.5	distemper, seam	30,6
	FB				0,35	1,8		97,2	B22.5	L=12m	18,9
										Total:	290,7

Calculation of soil volumes for backfilling

Taking into account the structures installed below the surface of the horizon, it is necessary to determine the volume of soil for backfilling the pit sinuses and other volumes.

The volume of soil backfill should take into account the volume of cavities along the perimeter of the structure, taking into account the coefficient of residual loosening of the LG op.

The volume of soil to be backfilled into the pit bosoms is determined by the formula:

V oz =V k -V zhbzh

where: V reinforced concrete is the volume of reinforced concrete and concrete structures of individual columnar or strip foundations.

V oz =198

Figure 4 - Determining the size of the pit sinuses for counting

backfilling of soil

Technology and organization of complex mechanized work on

Development of a pit.

Organization and technology for performing complex mechanized work includes:

Determination of the technological sequence for the production of complex mechanized work;

Drawing up schemes for organizing the operation of machines;

Determination of the replacement operational productivity of all machines and justification of the number of machines in the set.

The technological sequence of work when digging pits and trenches consists of: developing the soil with an excavator and unloading it into a dump or onto vehicles; in transporting soil and cleaning the bottom and slopes.

When determining the technology for excavating soil from pits and trenches, the groundwater level specified in the task should be taken into account and methods of water reduction or open drainage should be provided with the necessary calculations and selection of technical means.

Calculation of the productivity of leading machines.

To excavate foundation pits and trenches for buildings with strip foundations, backhoe excavators are used.

Calculation of the hourly productivity of an excavator

where: q=0.65 - bucket capacity, m 3

t c = 30 sec

Required number of excavators

where: V cm = 1511.235 m 3

n= 1511.235/(38.61*8) = 5 pcs.

Required number of vehicles

– time of one cycle of operation of a transport unit;

– estimated loading time of the transport unit,

- travel time,

– unloading time (1 min)

– time of maneuvering of the transport unit before loading and unloading (2 min.).

When determining, first count the number of buckets with soil “n” required to fill 1 transport unit:

– carrying capacity of the transport unit;

– soil density, =1.95;

– ladle filling coefficient taking into account loosening, ;

– bucket volume, .

According to Appendix G, we accept as a vehicle the YAZ 210E (KrAZ222) dump truck, for which Q = 10 tons.

Let us determine the capacity of the transport unit using the formula:

Let's determine the loading time:

Let's determine the travel time:

– distance of soil transportation, km;

Number of dump trucks

We accept 10 YAZ 210E (KrAZ222) dump trucks.

We backfill the foundation cavities with a bulldozer.

Installation of structures of the basement of the building

No.	Basis of norms and prices	Description and conditions of work	Unit	Calculation formula	Scope of work
	E6-1-25	Structure breakdown	100 p/m	(1584+1035)/100	26,19
	E49-1-57	Uprooting stumps and bushes	1 stump	based on
	E2-1-5	Cutting off the vegetation layer	1000 m 2	(272*53)/1000	14,416
	E2-1-11	Development of group III soil with an excavator with a backhoe, volume 0.65: for sweeping	100 m 3	V oz /100	59,58
with loading into vehicles	100 m 3	(Voz – Vtotal)/100	0,87
	E2-1-47	Cleaning the bottom of the pit	1 m 3	vn	178,2
	E1-73	Sand tray	1 m 3	∑0.1*Sole	93,6
	E1-73	Sand cushion device	1 m 3	∑0.1*Sole	93,6
	E4-1-1	Installation F-1	PC.	from the decomposition plan
	E4-1-1	Installation F-2	PC.	from the decomposition plan
	E4-1-6	Installation of foundation beams FB-1	PC.	from the decomposition plan
	E4-1-6	Installation of foundation beams FB-2	PC.	from the decomposition plan
	E11-37	Installation of coating waterproofing (with hot bitumen or bitumen mastics)	100 m 2	∑S b.p Ф /100	14,4
	E2-1-34	Backfilling of foundation cavities with a bulldozer	100 m 2	V O3 /100	59,58

According to the specification of prefabricated reinforced concrete and concrete elements, a statement of calculation of the volume of work of the zero cycle is drawn up.

Literature

1. EniR E2. Excavation. Mechanized and manual excavation work. - M.: Stroyizdat, 1988.-Issue. 1.

2. EniR E4. Installation of prefabricated and installation of monolithic reinforced concrete structures. - M.: Stroyizdat, 1987. - Issue. 1.

3. SNiP 12-03-2001. Occupational safety in construction. 4.1. General requirements / Gosstroy RF.-M.: Stroizdat, 2001.

4. SNiP 4.02-91. Collection 1. Estimated norms and prices for earthworks.

5. SNiP 4.03-91. Collection of estimated standards and prices for the operation of construction machines.

6. Jib self-propelled cranes and slinging of loads: Sprav, ed. / Tkach JI. P., Slenchuk N.A., Nosov A.I. et al. - M.: Metallurgy, 1990. 272 p.

7. technology of construction processes: Textbook / A. A. Afanasyev, N. N. Danilov, V. D. Kopylov and others; edited by N. N. Danilova, O. M. Terentyeva. - M.: Higher School, 2001.-464 e.: ill.

8. Technological maps for complex mechanized processes for the production of earthworks using new mass-produced machines / Gosstroy of the USSR. UNIIOMTP.-M., 1983, - 140 p.

9. Khamzin S.K., Karasev A.K. Technology of construction production. Coursework and diploma design. Textbook A manual for construction specialists. Universities. M.: Higher School, 1989.

Assignment for completing a course project.

1. Scheme number: 1.

2. Depth of the foundation base: H = 2.1 m.

3. Span: L = 9 m.

4. Number of letter axes: N = 6 pcs.

5. Number of spans: N – 1 = 5 pcs.

6. Column pitch: R=12 m

7. Number of digital axes: 23pcs.

8. Step number: n-1=22 pcs.

9. Duration of excavation work: T = 2 days.

10. Soil group: III.

11. Soil transportation range: 30 km.

Type of soil: heavy loam with an admixture of crushed stone over 10% by volume. Volumetric weight 1950

Main technological characteristics of the developed soil

We determine the name of the soil and its density when excavating with a single-bucket excavator. According to Table 1 E2-1, we determine the soil group according to the difficulty of development - III.

According to Appendix 1 of the guidelines, according to the name of the soil, we determine the soil loosening coefficients:

V r-volume of soil in the developed state;

V pl- volume of soil in a dense body.

Residual soil loosening coefficient:

V upl- volume of loosened soil after compaction during development.

Slope diagram.

Soil stability on slopes is characterized by the physical properties of the soil (the adhesion force of particles, the pressure of overlying layers, the angle of internal friction, etc.), at which the soil is in a state of stability.

According to Appendix 5 of the guidelines, the maximum permissible steepness of the slope with an excavation depth of up to 3 m is 63°, and the slope of the slope is:

Characteristics of soil development conditions.

Main characteristics

Endurance limit (- with a symmetrical change in load, - with an asymmetrical change in load) - the maximum stress that the material can withstand for an arbitrarily large number of loading cycles N.

Limited endurance limit - the maximum stress that a material can withstand for a certain number of loading cycles or time. Vitality is the difference between the number of cycles until complete failure and the number of cycles before the appearance of a fatigue crack.

Technological properties

Technological properties characterize the ability of a material to be subjected to various methods of cold and hot processing.

1. Foundry properties.

Characterize the ability of a material to produce high-quality castings from it.

Fluidity - characterizes the ability of molten metal to fill a casting mold.

Shrinkage (linear and volumetric) - characterizes the ability of a material to change its linear dimensions and volume during the process of solidification and cooling. To prevent linear shrinkage when creating models, non-standard meters are used.

Liquation is the heterogeneity of the chemical composition by volume.

2. The ability of the material to be processed by pressure.

This is the ability of a material to change size and shape under the influence of external loads without collapsing.

It is controlled as a result of technological tests carried out under conditions as close as possible to production ones.

The sheet material is tested for bending and stretching of the spherical dimple. The wire is tested for bending, twisting, and winding. Pipes are tested for expansion, flattening to a certain height and bending.

The criterion for the suitability of a material is the absence of defects after testing.

3. Weldability.

This is the ability of a material to form permanent connections of the required quality. Evaluated by the quality of the weld.

4. Cutting ability.

Characterizes the ability of a material to be processed by various cutting tools. It is assessed by tool life and the quality of the surface layer.

The main task of a technologist is to create high-performance technological processes.

In structural terms, the technological process consists of a set of technological operations (TO) necessary for the manufacture of products in accordance with the requirements of regulatory and technical documents.

The technological process is divided into technological operations. Establishing the content and sequence of operations is included in the task of developing a technological process.

In addition to technological operations, there are auxiliary operations. These include transportation, control, labeling, etc.

The organization of flexible production, like any other, is subject to such general principles:

proportionality, that is, ensuring the same throughput of different GPS systems due to the possibility of partial redistribution of the load between them;
specializations, that is, the distribution of work between various enterprises, workshops, sections, individual GPS and flexible production modules (GPM) according to the manufacturing method;
standardization, which is the main tool for reducing the range of manufactured products, which makes it possible to limit the range of products for one purpose, increase the scale of production and promotes the transition from multi-product HPS to more productive flexible automated production (GAP);
rhythmicity, i.e. ensuring product release on schedule, which helps reduce defects;
straightness- in this case, all material flows of production are moved in the shortest possible way;
automaticity, i.e. automation of all technological operations, which helps to increase labor productivity and quality of products.

However basic principles production organizations that fully reveal all the capabilities of GAP are:

continuity of processes, eliminating or significantly reducing various interruptions in the production of a particular product;
process parallelism- provides for the simultaneous execution of various parts of the production process. In fact, there is an organic merger of design and technological preparation of production, main and auxiliary processes. Parallelism is also ensured by centralization and integration of management processes.

The main parameters of the technological process are:

accuracy (the degree of compliance of the parameters of the manufactured product with those specified in the regulatory and technological documentation). It should be understood that the cause of non-conformity is production errors (systematic or random), and be able to analyze the reasons for their occurrence and the result of their impact on the technical process;
stability - the property of a technological process (TP) to maintain the values of product quality indicators within specified boundaries for a certain time;
productivity - the property of a technological process to ensure the production of a certain number of products over a specified period of time. There are hourly, shift, monthly, etc. productivity;
the cost of production, which is determined by the costs of its production.

In addition, an important parameter is also the manufacturability of product design, which can be assessed both qualitatively and quantitatively - by calculating certain indicators.

It might be useful to read: