Automation of the process of epurification and rectification of ethyl alcohol at Biokimyo OJSC

Contents

Introduction

Process Description

Brief description of alcohol production process

BRU Process Description

Functional Diagram Description

Specification for Automation Equipment............. 

Process Simulation

Introduction

Brief description of the process

Mathematical description of rectification process

Static calculation algorithm

Description of the management system architecture

Automation object

Technical aspect

Software aspect

Functions to be performed

Composition of the complex

    Calculation of ECS

Feasibility Study

Safety of life

Conclusion

Literature

Introduction

Ethyl alcohol is one of the important products and raw materials for many industries. We will not delve into discussing its importance in the life of the country. Note only that alcohol has, in addition to the main, a variety of other uses in such industries as perfumery, medicine, pharmaceuticals, etc.

Since absolutized 100% is practically not found in industry, we will talk about a binary mixture of ethyl alcohol and water (hereinafter simply alcohol), the concentration of ethyl alcohol in which, depending on the grade, is 96.2... 96.6% (boiling point -78.15 ° C).

In such alcohol, in addition to water, various impurities (aldehydes, ethers, higher alcohols and other chemical compounds) are contained in small doses, which form the flavor and aroma characteristic of the alcohol depending on the type of processed raw materials.

The most significant steps in the production of food alcohol are the processes of distilling and rectification. Alcohol production is carried out at the bragorectification plant (BRU) from brushes of starch-containing and sugar-containing raw materials. During alcohol rectification, the main task is to obtain a mixture with a concentration of ethyl alcohol in it of at least 96% with a minimum content of foreign impurities.

The process of bragorectification, this is the final and most responsible stage in the production of the final product - alcohol. The quality of alcohol production largely depends on the accuracy of maintaining the process modes of operation of the bragorectification plant. In traditional systems, the monitoring and control of process parameters is assigned to the duty operator, who ensures the monitoring of current parameters and their maintenance within the specified technological regulations.

The alcohol production process is continuous and round-the-clock, the operator needs to constantly monitor the readings of control devices for measuring temperature and pressure throughout his shift, control the corresponding valves to maintain the production process in accordance with the specified technological standards. Here we are faced with the human factor in production. Considering that measuring and actuating devices are distributed throughout the entire bragorectification workshop, the operator has to constantly move throughout the workshop territory throughout the shift.

The nature of the work causes physical fatigue, reduced attention and provokes the operator to take a rather "cool" attitude to his work duties (especially on night shifts, when control by the plant administration is weakened), and this directly affects the quality of the product produced. Administrative control methods do not, as a rule, bring positive results, the ingenuity of working personnel allows you to simply bypass administrative "slingshots" in the form of registration logs, planned and unscheduled inspections, etc.

The only way out of this situation is to automatically monitor the parameters of the technological process with maintaining the corresponding logs of parameters whose objectivity does not depend on the human factor. The natural continuation of automatic monitoring is the use of the obtained data to introduce automatic control and process control circuits.

Functional Diagram Description

The functional diagram is the main technical document defining the functional-block structure of separate units of automatic control, control and regulation of the technological process and equipping the object of control of instruments and automation facilities.

When developing functional diagrams, it is necessary to solve the following:

- obtaining information on the state of the process and equipment,

- direct impact on the process for its management,

- stabilization of process parameters,

- monitoring and recording of process parameters and state of process equipment.

With a stable feed flow of columns, the amount of alcohol content fluctuates due to the instability of such parameters as grain quality, the operation of the fermentation compartment, etc. An optimal column control scheme was developed depending on the percentage at the entrance to the fragrance column. If the alcohol content in the feed is increased, the valves for distillate extraction and reflux flow are simultaneously opened. Thus R = const is supported. This leads to an increase in the amount of vapors (G = P + F) due to the fact that F = const, and F will increase. In this case, the temperature is controlled by means of a steam supply valve (cover) and by means of a cooling water supply valve during vapor condensation (open). When the alcohol content in the feed decreases, the corresponding valves begin to work in the opposite direction.

All process parameters are monitored and controlled through the controller. When labeled in the functional diagram table, some controlled parameters are connected by a line below. So the parameters that are subject to control are indicated. Points on the line indicate the parameters by which this control will occur. To do this, a special is recorded in the computer memory. program. The program continuously calculates the optimal parameters based on the created models and generates control actions for real conditions, thereby maintaining the specified mode of operation according to the technological regulations. This guarantees the quality of the product produced.

The developed automation system for the production of ethyl alcohol at Biokimyo JSC is based on primary converters of the Metran type with unified outputs and a Siemens controller of the SIMATIC S7400 type. The measured parameter values are recorded on the operator interfaces and the main computer of the process archive.

During the development of the functional diagram, the following circuits of automatic control and regulation were built:

1. The flow rate of the mature muzzle is controlled using an intelligent flow converter (pos. 1-1) and control positioner with valve (1-4). Flow values are recorded on control system operator interface monitors (12, 1-3).

2. Control of temperature of mature distiller's beer (up to 30 wasps) is exercised by resistance thermoconverter (NSH: 100M) with the unified output signal (poses. 2-1). The temperature value is recorded on the control system operator interface monitors.

3. The level of the vinasse in the bottom of the barge column is controlled using a radar level meter with a unified output signal (pos. 3-1) and control positioner with valve (3-2). The level value is logged on the control system operator interface monitors.

4. Level control in the vinasse collector is carried out using a radar level gauge. The level value is recorded and signaled on the control system operator interface monitors.

5. The flow rate of reflux and distillate flow in the fragrance column is controlled by an automatic flow analyzer (pos. 5-1) and control positioners with valves (pos.52, 5-3) to stabilize the alcohol content in the feed. Alcohol content values in% are recorded on control system operator interface monitors (12, 1-3).

6. Temperature control in the folding column is carried out using the resistance thermal converter (pos. 6-1) with unified output signal and control positioner with valve installed on the pipeline for acute steam supply (pos. 6-2). This loop is part of the control loop below point 5 (column optimization). Temperature values are recorded on control system operator interface monitors.

7. Pressure monitoring at the bottom of BC is performed using thermoresistive intelligent overpressure converter (pos. 7-1). Pressure value is recorded on monitors of operator interface of control system, and also serves for correction of control signals in positions 52, 5-3, 62, 11-2 by means of special. programs.

8. Control of temperature in the bottom of a column is exercised by means of resistance thermoconverter (NSH: 100M) with the unified output signal (poses. 8-1). Temperature value is recorded on monitors of operator interface of control system, and also serves for correction of control signals in positions 52, 5-3, 62, 11-2 by means of special. programs.

9. Pressure monitoring at the top of BC is performed with the help of resistive intelligent overpressure converter (pos. 9-1). Pressure value is recorded and signaled on monitors of operator interface of control system, and also serves for correction of control signals in positions 52, 5-3, 62, 11-2 by means of special. programs.

10. Control of the liquid composition at the outlet of the BK reflux generator is carried out using a chromatograph (pos. 101). Data is recorded on control system operator interface monitors and is also used for correction of control signals in positions 52, 5-3, 62, 11-2 with the help of special. programs.

11. Control of temperature above a brazhny column is exercised by means of resistance thermoconverter (NSH: 100M) with the unified output signal (111) and the regulating positioner with the valve, established on the pipeline, for supply of cold water (poses. 112). Temperature values are recorded and signaled on control system operator interface monitors.

12. Flow rate of BC reflux is controlled using ultrasonic flowmeter with transducer (pos. 121). The flow value is recorded on the control system operator interface monitors.

13. Control of the flow rate of alcohol condensate to EC is carried out using an ultrasonic flowmeter with a converter (pos. 131). The flow value is recorded on the control system operator interface monitors.

14. Control of temperature of the cooling water after a dephlegmator of BQ is exercised by means of resistance thermoconverter (NSH: 100M) with the unified output signal (141). The temperature value is recorded on the control system operator interface monitors.

15. Level control in the EC cube is carried out using a radar level meter. The level value is logged on the control system operator interface monitors.

16. Control of the flow rate of hydroselection water in ECU for the separation of azeotropes is carried out using an ultrasonic flowmeter with a converter (pos. 161) and control positioner with valve (pos.162). Flow values are recorded on control system operator interface monitors (12, 1-3).

17. Control of temperature of hydroselection water is exercised later by means of resistance thermoconverter (NSH: 100M) with the unified output signal (171). The temperature value is recorded on the control system operator interface monitors.

18. The reflux and distillate flow rates for the epuration column are controlled by an automatic flow analyzer (pos. 181) and control positioners with valves (pos.182, 18-3) to stabilize the alcohol content. Alcohol content values in% are recorded on control system operator interface monitors (12, 1-3).

19. Control of temperature in EK is exercised by means of resistance thermoconverter (NSH: 100M) with the unified output signal (191) and the regulating positioner with the valve, established on the pipeline, for supply of sharp steam (poses. 192). This loop is part of the control loop below item 18 (column optimization). Temperature values are recorded on control system operator interface monitors.

20. Pressure monitoring at the bottom of the electric power plant is carried out using resistive intelligent overpressure converter (pos. 201). Pressure value is recorded on monitors of operator interface of control system, and also serves for correction of control signals in positions 182, 18-3, 192, 22-2 by means of special. programs.

21. Control of temperature above EK is exercised by means of resistance thermoconverter (NSH: 100M) with the unified output signal (poses. 211). Temperature value is recorded on monitors of operator interface of control system, and also serves for correction of control signals in positions 182, 18-3, 192, 22-2 by means of special. programs.

22. Control of temperature above EK is exercised by means of resistance thermoconverter (NSH: 100M) with the unified output signal (221) and the regulating positioner with the valve, established on the pipeline, for supply of cold water (poses. 222). Temperature values are recorded and signaled on control system operator interface monitors.

23. Control of temperature of the cooling water after a dephlegmator of EK is exercised by means of resistance thermoconverter (NSH: 100M) with the unified output signal (231). The temperature value is recorded on the control system operator interface monitors.

24. Control of liquid composition after EC dephlegmator is performed using chromatograph (241). Data is recorded on control system operator interface monitors.

25. The pressure in the acute steam header is controlled by a resistive intelligent pressure transducer (251). Pressure values are recorded and signaled on control system operator interface monitors.

26. The flow rate is monitored using an ultrasonic flowmeter with a transducer (261). Flow values are recorded on control system operator interface monitors.

27. The flow rate of reflux and distillate flow for RC is controlled using an automatic flow analyzer (pos. 271) and control positioners with valves (p.272, 27-3) to stabilize the alcohol content. Alcohol concentrations in% are also recorded on control system operator interface monitors (12, 1-3).

28. Control of temperature in EK is exercised by means of resistance thermoconverter (NSH: 100M) with the unified output signal (281) and the regulating positioner with the valve, established on the pipeline, for supply of sharp steam (poses. 282). This loop is an integral part of the control loop below 27 (column optimization). Temperature values are recorded on control system operator interface monitors.

29. Pressure monitoring at the bottom of RK is carried out using resistive intelligent overpressure converter (pos. 291). The pressure value is recorded on the monitors of the operator interface of the control system, and also serves to correct the control signals in positions 272, 27-3, 282, 33-1, 332, 33-3, 334, 33-5, 341 using a special. programs.

30. Control of temperature in the bottom of RK is exercised by means of resistance thermoconverter (NSH: 100M) with the unified output signal (poses. 301). The temperature value is recorded on the monitors of the operator interface of the control system, and also serves to correct the control signals in positions 272, 27-3, 282, 33-1, 332, 33-3, 334, 33-5, 341 using a special. programs.

31. Pressure monitoring at the top of CV is performed with the help of intelligent overpressure converter (pos. 311). The pressure value is recorded on the monitors of the operator interface of the control system, and also serves to correct the control signals in positions 272, 27-3, 282, 33-1, 332, 33-3, 334, 33-5, 341 using a special. programs.

32. Control of the alcohol composition at the outlet of the reactor is carried out using a chromatograph (pos. 321). Data is recorded on control system operator interface monitors, and is also used for correction of control signals in positions 272, 27-3, 282, 33-1, 332, 33-3, 334, 33-5, 341 with the help of a specialist. programs.

33. Electro-pneumatic positioners with actuating valves (pos. 331, 33-2, 333, 33-4, 335). Calculated specialists. control actions are transmitted from the controller by the program.

34. Regulation of temperature above RK is carried out by means of resistance thermoconverter (NSH: 100M) with the unified output signal (poses. 341) and control positioner with valve installed on the pipeline for cold water supply (pos. 342). Temperature values are recorded and signaled on control system operator interface monitors.

35. Level control in RK cube is performed using radar level gauge (pos. 351). The level value is logged on the control system operator interface monitors.

36. Control of temperature of alcohol after RK is made by means of resistance thermoconverter (NSH: 100M) with the unified output signal (poses. 361). The temperature value is recorded on the control system operator interface monitors.

37. Monitoring of cooling water temperature at the outlet of IH reflux regulator (pos. 371) it is made by means of resistance thermoconverter (NSH: 100M) with the unified output signal. The temperature value is recorded on the control system operator interface monitors.

38. The cooling water flow rate for alcohol cooling is monitored using an ultrasonic flowmeter (pos. 381) and electro-pneumatic positioner with valve (pos. 382). The flow value is recorded on the control system operator interface monitors.

39. The alcohol composition after the refrigerator is controlled by an automatic flow analyzer (pos.391). The alcohol content in% is recorded on control system operator interface monitors.

Description of the control system

6.1 Automation object

The BRU process is divided into stages, which are implemented sequentially in separate columns. Typical industrial BRU typically has the following composition:

● Braga column (distillation of braga to obtain braga distillate).

● Epuration column (separation from distillate and concentration of head impurities).

● rectification column for concentration of alcohol and its pasteurization, at the same time extraction of intermediate impurities in the form of luminal fractions).

In BRU columns, excess pressure is established, which must be maintained within strictly defined limits. Heating steam providing overpressure is distributed over BRU columns through common steam header. The main performance indicators of each column are readings of pressure sensors located in the upper and lower parts of the columns, and readings of temperature sensors installed in different zones of each column. Almost the most significant indicator of the rectification process is the degree of approximation of the real distribution of the temperature field in the column to the given, corresponding to the BRU process schedule. It should be borne in mind that the temperature deviation on the feed tray of the distillation column from the specified one by more than 1 ° C leads to excess normative losses of alcohol or to the selection of alcohol with unsatisfactory organoleptic indicators (smell, taste, color, etc.).

Theoretical and practical experience indicate the same thing - BRU columns as control objects have significant inertia, significant transport delay and non-stationary parameters in connection with the continuous heat and mass exchange occurring inside each column, as well as the fact that control is largely carried out by an indirect parameter - temperature.

One of the main tasks assigned to BRU APCS is to stabilize the current values ​ ​ of pressures and temperatures measured at given installation points within a certain, fairly narrow range. Another important task is to select the finished product (alcohol) from the distillation column, since the quality of the alcohol largely depends on what values ​ ​ of indirect parameters will be taken.

Thus, APCS BRU was developed to solve several production problems at once:

● stabilisation of BRU regimes and ensuring stable production of the final product with the specified characteristics at minimum energy and raw materials costs;

● improving the reliability of BRU operation;

● creation of automated emergency and emergency prevention tools;

● creation of favorable working conditions for service personnel.

6.2 Technical Aspect

APCS of the bragorectification plant can be conditionally divided into the following levels, focusing on implemented functions and used hardware and software:

● level of sensors and actuators (lower level);

● Level of programmable logic controllers (process control level)

● the level of interaction between the system and operators (interface or upper layer).

Consider each of these levels in more detail.

Lower level

The APCS BRU design uses pressure sensors having a unified current output (4... 20 mA); to measure temperature, copper resistance thermometers (100M) with a unified signal are used, and ultrasonic flow meters with a current output are used to measure the flow rate of liquids.

As actuators membrane actuators controlled by current signals through electro-pneumatic positioners.

Process Control Level

The controller layer in the system performs the following functions:

● reception of signals from sensors installed on the control object;

● signal processing and adjustment of measurement ranges to engineering units;

● generation of control signals for actuators of the control object;

● implementation of object control algorithms in real time;

● transmission and reception of data from the network.

The process control level is represented by the Siemens Controller S7400.

The control controller, in addition to collecting data and issuing control signals, provides the implementation of the process plant control algorithm.

The use of controllers provides the APCS developer with a number of advantages:

● easy installation and easy maintenance;

● simplicity of system expansion and ability to increase the number of controller I/O modules without increasing system redundancy ;

● availability of a convenient multi-function controller programming environment

● large amount of internal RAM and high speed (less than 3 ms is required to execute a program of 1000 operators and input _ output 256 signals), which allows developers to organize the implementation of control algorithms of great complexity directly on the PLC.

Basic controllers are equipped with the necessary input _ output modules, which provide reception of signals from sensors and output of control actions to actuators. In the design of APCS BRU alcohol of the plant, the following input _ output modules are used:

→ Discrete signal input modules. On their front panels there are green LEDs indicating the state of the input circuits, a red LED for indicating failures and errors, a protective cover, on which the marking of the input circuits is applied. Front connectors make it possible to replace modules without dismantling external circuits.

← Discrete signal output modules. On their front panels there are green LEDs indicating the state of the input circuits, a red LED for indicating failures and errors, a protective cover, on which the marking of the input circuits is applied. Front connectors make it possible to replace modules without dismantling external circuits.

→Moduli input of analog signals. Front connectors with mechanical coding, as well as marking strips and their protective coatings are installed on the front panels of the modules. The presence of front connectors allows you to replace modules without dismantling external communication lines. The modules can be tuned to operate with a resolution of 13 to 16 bits, to various limits of changes in input signals, generation of interrupt requests when the limit values ​ ​ of input signals are reached. Modules are available for diagnosis.

← Analog signal output modules. Front connectors with mechanical coding, as well as marking strips and their protective coatings are installed on the front panels of the modules. The presence of front connectors allows you to replace modules without dismantling external communication lines.

SIMATIC S7400 is a powerful programmable controller for medium- and high-complexity automation. Its modular design, natural cooling operation, flexible expansion capabilities, powerful communication capabilities, easy creation of distributed control systems and serviceability make the SIMATIC S7400 ideal for solving almost any automation tasks.

Top Level

At the upper level of the system, the following functions are implemented:

● polling through the network of controllers and processing of operational information on the process progress;

● implementation of the user interface in a convenient and intuitive form for the operator;

● maintenance of archives of process parameters, event protocols and operator actions;

● reception of setpoints for control algorithms from operating personnel and their transmission via the network to control controllers.

The upper level in the described APCS BRU project is implemented on the basis of IBM PC compatible personal computers (PCMs) of the standard configuration running Microsoft Windows 7.

PCMs, equipped with SCADA HMI system Trace Mode (fully Russified), form modern and quite powerful APMs of process operators. Operator _ technologist AWS are duplicated to ensure continuity of process control in case of PC failure.

The top-level computers (operator APCs) and process control level controllers (I/O controllers) are combined by a Profibus network. Using the Profibus network allows you to connect additional APCs to the system, located on remote PCMs.

The power supply of the operator's AWS equipment, controller rack and network switching devices is provided through the Smart _ UPS uninterruptible power supply (UPS), which, in addition to filtering network interference, ensure the system operation for at least 20 minutes after the primary power supply is disconnected.

6.3 Software Aspect

I&C BRU used the STEP 7 controller programming environment as software development tools.

BRU APCS control logic application software is developed by means of the STEP 7 controller programming environment and consists of software modules:

● BRU common signal control module;

● Brave column control module;

● Control Module of the Epure Column;

● rectification column control module;

The BRU Common Signal Control Module controls the header steam pressure.

The column control modules include the following controls:

● steam supply regulators to the columns,

● control valves for cooling water supply to the columns,

● control of the gloss supply to the folding column,

● regulator of hydroselection water supply to the epuration column ,

● alcohol extraction regulator from the distillation column,

Regulators are units implementing PID control laws.

The application software that forms the operator interface is implemented by Trace Mode.

The operator interface uses mnemonic diagrams that display the state of each of the columns individually and the entire bragorectification plant. In addition, the operator interface tools include

a protocol of events and actions of operators, as well as a set of historical trends that store information about the operation of the installation over the past five days.

Conclusion

In this course project, an optimal column control scheme was developed depending on the percentage of alcohol in the feed, and a program was developed that simulates the rectification process.

The obtained distributions of components along the height of the column make it possible to optimize the technological and structural parameters of the column apparatuses. In addition, programs created to calculate the distribution of concentrations written using modern programming languages, Borland Delphi, respectively, can be used to calculate any rectification processes. The use of the latest applications contributed to solving one of the main problems of describing and predicting equilibrium ratios in columns - the complexity of the analytical solution of the system of nonlinear algebraic equations describing the technological process of rectification. Developed on the basis of the Trace Mode 5 integrated control environment, BRU ACS solved the problems of controlling distributed technological equipment and centralizing the regulation of multi-link technological parameters .

Usually, automation systems at alcohol plants are engaged only in stabilization of pressure and temperature in BRU columns and mostly consist of local control circuits, which are not connected in any way. Such decentralized systems, although they solve a certain range of private problems, are not able to provide through much coherent control of technological parameters. The developed centralized APCS BRU allows, after accumulating a certain amount of statistical data, to implement algorithms for multi-link parameter control, as well as to carry out integrated process control. The introduction of the system leads to stabilization of the quality of products, reduction of losses and, in addition, to a significant improvement in the working conditions of process operators.

In addition to industrial applications at Biochim OJSC, the developed project can be used as a training manual for training SCA1S student systems in the specialty "Automation of technological processes and industries."