After developing the operating scheme start drawing up process flow diagram, which, in fact, is equipment design operating. It can be considered as consisting of a number of process units. Processing unit is called the unit (car) or group of strapping machines with pipelines and valves, which begins and ends in one of a fully physico-chemical or chemical processes.

In technology nodes include such objects, as collections, the measuring tanks, pumps, compressors, blower, separators, heat exchangers, distillation columns, reactors, recovery boilers, filters, centrifuge, septic tanks, crusher, classifiers, dryer, evaporators, pipelines, valves piping, safety devices, sensors and monitoring devices and automation, Executive and regulatory mechanisms and devices.

The absolute majority of the aforementioned vehicles and machines produced by the industry and standardized. Information about the types of manufactured machines and devices, their designs and characteristics can be obtained from various handbooks, the catalogue of plants, industry publications and information institutions, from promotional materials and industry scientific and technical journals.

But, before you make up the technological scheme, it is necessary to clarify a number of tasks, which are solved at this stage. It, first of all, ensuring occupational health and safety. Therefore, the technological scheme needs to provide means to prevent excessive pressure (safety valves, explosive membrane, the locks, emergency capacity), system create a protective atmosphere, the emergency core cooling system and t. d.

At the stage of synthesis of the technological scheme solved the question of reduction of costs for pumping products. Maximum use should be made of control for transportation of fluids from one device to another. Therefore already includes the necessary excess of one device over another.

In this step, determine the set of heat- and coolants, to be used during the implementation process. The cost per unit of heat or cold depends on the availability at the enterprise of energy source and its parameters. The cheapest refrigerants are air and circulating industrial water. Economically, the main amount of heat transfer to these cheaper coolants and only the residual heat to remove expensive refrigerants (Zabolotna water, brine, liquid ammonia and
t. p.). The cheapest fluids are flue gases, but they are not transportable.

For making process flow diagram on a sheet of graph paper first, hold the line collectors feed and output material flows, coolants and refrigerants, leaving in the bottom of the sheet free lane height 150 mm, where later will be placed tools Instrumentation. Recommended line gas reservoirs to hold at the top of the sheet, and liquid in the lower part. After this, on the plane of the sheet between the collectors include cosmetic devices and machines, required to perform operations, in accordance with the developed operating scheme. Cosmetic machines are not scale. The distance between them horizontally is not regulated, it should be sufficient to accommodate the material flow lines and controls and automation. The location of the conditional vertical images should reflect the real excess over the other device not to scale. Placed in the plane of the sheet cosmetic of machines and devices connect lines material flows, down the line of refrigerants and coolants. Is the numbering of the positions of vehicles and machinery from left to right.

Rice. 5.3. The binding site of absorption: I – IV–main pipelines; 1 – absorber; 2 –pump; 3 fridge absorbent

Special attention in the design of the technological scheme should be given to tying in individual nodes. An example of such piping is shown in
rice. 5.3. This shows the site of absorption of the component gas mixture liquid. Normal operation of the site of absorption depends on the constancy of the temperature, pressure and on the ratio of the amount of gas and absorbent. The satisfaction of these conditions is achieved by installing the following fixtures and fittings.

On the gas supply lines (I: orifice flowmeter, the sampler, boss to measure the pressure and boss to measure temperature.

On line gas outlet (II): orifice flowmeter, the sampler, boss to measure temperature, boss to measure the pressure, control valve, maintain a constant pressure "up yourself", t. e. in the absorber.

On line feed of fresh absorbent (III): orifice flowmeter, or rotameter, the sampler, boss to measure temperature, control valve, associated with control of ratio of gas and absorbent.

The line output of the saturated absorbent (IV): diaphragm flow meter, or rotameter, boss to measure temperature, control valve, associated with level control of liquid in the bottom of the absorber.

During the development of the technological scheme it should be borne in mind, that the control valves could not serve as shut-off devices. Therefore, the pipeline should be provided with shutoff valves with manual or mechanical drive (valves, valves), to turn off and control valves – by-pass (bypass) line.

Drawn diagram is preliminary. After the preliminary material and thermal calculations the developed technological scheme should be analyzed the possibility of heat recovery and cooling of process material flows.

In the design process in the technological scheme may be made and other modifications and additions. The final design of the technological scheme is made after the adoption of the main design solutions for the calculation and selection of reactors and apparatus, after clarification of all questions, associated with placement and equipment layout design production.

So, sometimes when selecting equipment have to face the fact, that some species are either not produced in Russia, or are currently under development. The absence of any machine or apparatus desired characteristics, made from structural material, sustainable in this environment, often necessitates a change in individual units of the technological scheme and may cause transition to another, economically less advantageous method of obtaining the target product.

Technological scheme may not be final, held until equipment layout. For example, the original version was supposed to transfer fluid from one device to another by gravity, which could not be implemented during the project development of equipment placement. In this case, it is necessary to provide extra gear capacity of the pump and applied to the technology scheme.

The final flowsheet is drawn up following the development of all sections of the project and draws on standard sheets of paper in accordance with the requirements of ESKD.

After that, the description is made of the technological scheme, which is supplied with specification. In the specification, the number of all vehicles and machines.

The reserve equipment is subject to the schedule of preventative maintenance of properties and technological process.

Description of the technological scheme is part of a settlement-explanatory note. It is advisable to describe the circuit in individual stages of the process. In the beginning you should specify, what raw material is fed into the workshop, as it comes, where and how is stored in the shop, what primary treatment is subjected, how is metered and loaded in the vehicles.

When describing the actual process operations briefly reported on the construction of the apparatus, the method of loading and unloading, specify the characteristics of the flowing process and the method (periodic, continuous), lists the main parameters of the process (temperature, pressure, etc.), methods of control and regulation, waste and by-products.

Describes the accepted methods and interplant intrashop transportation of products. The description should list all depicted on the schematic drawing, the devices and machines showing assigned to them under the scheme of the rooms.

Analyzed the reliability of the technological scheme and indicates the means, used to increase its stability.