CN1330038A - Automatic control method of sodium sulfate production line - Google Patents

Abstract

An autocontrol method for the production line of sodium sulfate is disclosed, which can effectively control the temp of heating chamber and the liquid level, temp and pressure of each evaporating chamber for ensuring high granularity of crystal grains, no adhesion of crystal grains to pipeline and a certain flow speed. A programmable PLC logic controller or DCS distribution controller is used. The self-stabilized PID parameter is used to regulate relative variables for balancing between material feed, evaporated quantity and discharged material. Its advantages are high productivity and quality, high granularity, high whiteness and low water content.

Description

Automatic control method of sodium sulfate production line

Technical field

The present invention is the method for Sodium sulfate anhydrous.min(99) Automation of Manufacturing Process control.

Background technology

(formal name used at school: mainly main processes such as halogen, evaporation, centrifugal and drying realize production technique anhydrous sodium sulphate) Sodium sulfate anhydrous.min(99) by adopting.In actual applications, can be divided into quadruple effect evaporation and five again and imitate evaporation, but all be consistent from Controlling System.Traditional sodium sulfate production line control method, be based on instrumental system, because the difference and the whole production device logistics matching problem of Controlling System, it is poor that each control loop is coordinated, and makes that in control process, it is big level fluctuation to occur, temperature, pressure fluctuate bigger thereupon, material often occurs and the bonding and the instability of quality product in batch turning and course of conveying, occur, problem such as the particle of product is little.Particularly when temperature fluctuation changes greatly, be prone to bonding or blocking pipe in the batch turning process, thereby complete assembly is stopped production, production efficiency is low.

Summary of the invention

Liquid level, temperature, pressure that the present invention can be to the heating chamber temperature, respectively imitate evaporator room are controlled effectively, make vaporizer materials at different levels big in the crystallizer grain size number, and both non-caked when flowing in pipeline, guarantee the velocity of flow of material again.

Automatic control method of sodium sulfate production line of the present invention can adopt the collecting and distributing controller of PLC programmable logic controller or DCS, and in-situs tester table and variable valve are carried out data gathering and red-tape operati; It is characterized in that:

(1) applying pressure transmitters sense 1 is imitated the pressure of heating chamber steam-gas inlet, adopts from adjusting pid parameter, makes the valve of control steam reach little inertia action; According to constant heat-up time of 1 effect heating chamber, formulate one group of loop pid regulator parameters, carry out the loop of steam admission variable valve and regulate; Simultaneously, according to the time constant of actual temperature change, the one group of new pid parameter of adjusting out certainly with this self study, certainly the one group of another group of new pid parameter of adjusting, carries out the loop and regulates, to reach heating chamber temperature stability and controllability;

(2) use the changing conditions that two flange fluid level transmitters detect 1 effect evaporator room liquid level, adopt multiparameter, from the pid parameter control mode of adjusting, regulate the clear solution variable valve, carry out the control of nitre liquid inlet amount, utilize the little principle of inertia of regulated valve, thereby guarantee that 1 imitates the small fluctuation in span of control of evaporator room liquid level;

(3) use two flange fluid level transmitters and detect 2 effect evaporator room liquid levels, from adjusting, regulate the batch turning variable valve by the multiparameter pid parameter, the minimum aperture of batch turning valve when determining to guarantee minimum steam output and minimum load simultaneously; As basic aperture, guarantee that 2 effect evaporator room liquid levels fluctuate in span of control, with this aperture to guarantee the residence time in crystallization time and the crystal device;

(4) adjusting of dry air quantity is to detect blast and temperature transmitter detection inlet temperature by pressure unit, speed control by frequency variation is regulated blast volume, blast and is detected vapor pressure by pressure unit and regulate interchanger steam inlet variable valve, guarantees best blast, air quantity, wind-warm syndrome;

(5) use two each condensation balance bucket liquid level of flange transmitters sense, regulate, regulate each condensation balance bucket variable valve,, play the effect of fluid-tight simultaneously to guarantee balance bucket liquid level through pid parameter.

Appliance computer automatic control system of the present invention, detecting has related parameter, adopts the pid parameter mode aspect control, regulates related variable, makes that inlet amount multi-recycling amount, steam output and load balance each other in the evaporative process.For avoiding the latch up phenomenon in the batch turning, guarantee the prerequisite of material balance simultaneously; The minimum flow and the lowest temperature control that keep batch turning promptly by the little inertia control of steam valve being reached the maintenance minimum flow rate servo-actuated control of the stable and batch turning valve of temperature, realize the batch turning balance of evaporation unit.Thereby guarantee certain production efficiency and improve the quality of products, can reduce hand labor intensity again, increase productivity.The quality of the product that the present invention produced reaches the index of the desired macrobead of Sodium sulfate anhydrous.min(99), high whiteness and low moisture content.

Description of drawings

Fig. 1 is 1 an effect heating chamber temperature regulating and controlling functional block diagram of the present invention;

Fig. 2 is 1 an effect evaporator room liquid level regulating and controlling functional block diagram of the present invention;

Fig. 3 is the regulating and controlling schematic diagram that liquid level is imitated in batch turning of the present invention and 2;

Fig. 4 is the Principles of Regulation block diagram of dry air quantity of the present invention;

Fig. 5 is each condensation balance bucket Liquid level adjusting valve control principle block diagram of the present invention;

Fig. 6 is sodium sulfate production line control hardware circuit embodiment of the present invention;

Fig. 7 is that pid parameter of the present invention is from adjusting self study Principle of Process block diagram.

Specific embodiments

Pid parameter is from adjusting, and the detailed process of self study is as follows: in described each control process, after loop control drops into, earlier with one group of initial p ID parameter (P: scale-up factor, I: integral coefficient, D: differential coefficient) control.Note the difference between the target of process parameter and setting simultaneously, in the one-period of initial p ID parameter control, note from beginning to control to time when difference is less than expected error value between process parameter and the target component as the foundation of adjust I, D parameter.Time constant in cycle is generally decided the control effect of whole flow process on the realization time of target value in the particular loop by processing condition, after this time constant of artificial input, sequence of control will generate the synopsis of a difference and time constant, fixedly the P value is a constant, carry out the record of difference and time constant with the rule of each cycle I+ (1-n) back D-1 or I-(1-n) back D+1, and note corresponding pid parameter, and n is+1 or-1 number of times, concrete numerical value is decided on effect.When error is less than expected value in the time constant of input, current pid parameter is promptly controlled as preset parameter, when the fluctuation owing to process parameter produces new difference, sequence of control will be selected corresponding error amount from synopsis the pid value process of adjusting again, in the time of should not being worth in the tabulation, adjust with initial p ID value.In the whole production periodic process, the number of times of process parameter fluctuation is many more, and then the control value of synopsis generation is many more, thereby makes system be tending towards intelligent stable after several production cycles.Concrete control block diagram is seen Fig. 7.

1. 1 imitate the control of heating chamber temperature:

The evaporative process unstable temperature phenomenon that causes at the vapor pressure fluctuation, applying pressure transmitters sense 1 is imitated the pressure of heating chamber steam inlet, adopts from adjusting pid parameter, makes the valve of control steam reach little inertia action.According to constant heat-up time of 1 effect heating chamber, formulate one group of loop pid regulator parameters, carry out the loop of steam admission variable valve and regulate.Simultaneously, according to the time constant of actual temperature change, the one group of new pid parameter of adjusting out certainly with this self study, certainly the one group of another group of new pid parameter of adjusting, carries out the loop and regulates, thereby reach heating chamber temperature stability and controllability.Principles of Regulation figure such as Fig. 1.

2. 1 imitate the control of evaporator room liquid level:

The liquid level of evaporator room be since the variation of the variation of steam output and xln derived quantity at any time with changing quarter, stablizing of only guaranteed evaporator room liquid level, could guarantee xln dwell speed and crystalline time in crystallizer, thus the macrobead of assurance product and high-quality.At above situation, use the changing conditions that two flange fluid level transmitters detect 1 effect evaporator room liquid level, adopt multiparameter, from the pid parameter control thought of adjusting, regulate the clear solution variable valve, carry out the control of nitre liquid inlet amount, utilize the little principle of inertia of regulated valve, thereby guarantee that 1 imitates the small fluctuation in span of control of evaporator room liquid level, thereby satisfy the demand of producing high-quality product.Principles of Regulation such as Fig. 2.

3. the control of liquid level is imitated in batch turning and 2

The liquid level of 2 single-effect evaporators is to change owing to 2 effect steam output with by 1 variations of imitating the 2 solid-liquid amounts that contain xln of imitating that import and 2 effect loads; In this course, following key point is arranged:

(1) steam output will remain under a certain amount of situation, and variation range is less.

(2) by 1 multi-recycling amount of imitating in 2 fuel shuffling tubes of imitating, remain under the prerequisite of minimum steam output and minimum multi-recycling amount, must keep a minimum flow rate, thereby guarantee that solid liquid that can not causes the obstruction of fuel shuffling tube, will guarantee that simultaneously 2 imitate the stable of liquid level.

(3) since load change with taking place quarter at any time, thereby cause the variation of liquid level, affect the variation of multi-recycling amount.

Go up according to this situation, design according to steam output, multi-recycling amount, use two flange fluid level transmitters and detect 2 effect evaporator room liquid levels, from adjusting, regulate the batch turning variable valve by the multiparameter pid parameter, calculate simultaneously and guarantee minimum steam output and minimum load, the minimum aperture of batch turning valve as basic aperture, guarantees that 2 imitate the interior fluctuation of span of control of evaporator room liquid level with this aperture, thereby guarantee crystallization time and crystal residence time in crystallizer, guarantee the high-quality of product.Principles of Regulation figure such as Fig. 3.

4, the adjusting of dry air quantity

Through the wet stock of whizzer, deliver to drying tube through feeding machine and worm conveyor.Carry drying pipe drying by gas blower malleation hot blast, guarantee that the water content of product is lower than 0.01%, but can not be too high owing to temperature, the too high dust of product flavescence or blast is raised outward, cause dust pollution.So just require air quantity, wind-warm syndrome keeps an optimum regime, detect blast and temperature transmitter detection inlet temperature by pressure unit, speed control by frequency variation is regulated gas blower air quantity, blast and is detected vapor pressure by pressure unit and regulate interchanger (heat interchanging area is fixed) steam inlet variable valve, guarantee best blast, air quantity, wind-warm syndrome, guarantee the optimum drying effect with this, and according to processing requirement, calculate the minimum air quantity and the parameter value minimum, top temperature that guarantee ridity, being worth with this is the adjusting that basic value carries out air quantity, blast, wind-warm syndrome.Regulate block diagram such as Fig. 4.

5. 3 effect evaporator rooms requires process identical with 1 effect evaporator room.

6. 4 effect evaporator rooms requires process identical with 2 effect evaporator rooms.

7. after heat exchange, produce a large amount of water of condensation because each imitates heating chamber, use two each condensation balance liquid level of flange transmitters sense, regulate through pid parameter, regulate each condensation balance bucket variable valve, to guarantee balance bucket liquid level, play the effect of fluid-tight simultaneously, guarantee the heating chamber temperature-stable.

Claims (1)

1. an automatic control method of sodium sulfate production line can adopt the collecting and distributing controller of PLC programmable logic controller or DCS, and in-situs tester table and variable valve are carried out data gathering and red-tape operati; It is characterized in that:

(1) applying pressure transmitters sense 1 is imitated the pressure of heating chamber steam-gas inlet, adopts from adjusting pid parameter, makes the valve of control steam reach little inertia action; According to constant heat-up time of 1 effect heating chamber, formulate one group of loop pid regulator parameters, carry out the loop of steam admission variable valve and regulate; Simultaneously, according to the time constant of actual temperature change, the one group of new pid parameter of adjusting out certainly with this self study, certainly the one group of another group of new pid parameter of adjusting, carries out the loop and regulates, to reach heating chamber temperature stability and controllability;

(2) use the changing conditions that two flange fluid level transmitters detect 1 effect evaporator room liquid level, adopt multiparameter, from the pid parameter control mode of adjusting, regulate the clear solution variable valve, carry out the control of nitre liquid inlet amount, utilize the little principle of inertia of regulated valve, thereby guarantee that 1 imitates the small fluctuation in span of control of evaporator room liquid level;

(3) use two flange fluid level transmitters and detect 2 effect evaporator room liquid levels, certainly adjust by the multiparameter pid parameter, regulate the batch turning variable valve, determine to guarantee minimum steam output and minimum load simultaneously, the minimum aperture of batch turning valve, as basic aperture, guarantee that 2 imitate the interior fluctuation of span of control of evaporator room liquid level, with this aperture to guarantee the residence time in crystallization time and the crystal device;

(4) adjusting of dry air quantity is to detect blast and temperature transmitter detection inlet temperature by pressure unit, speed control by frequency variation is regulated blast volume, blast and is detected vapor pressure by pressure unit and regulate interchanger steam inlet variable valve, guarantees best blast, air quantity, wind-warm syndrome;

(5) use two each condensation balance bucket liquid level of flange transmitters sense, regulate, regulate each condensation balance bucket variable valve,, play the effect of fluid-tight simultaneously to guarantee balance bucket liquid level through pid parameter.

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