Full-working-condition slurry supply control system and method for flue gas desulfurization system

Abstract

The invention belongs to the technical field of industrial process control. According to the full-working-condition slurry supply control system and method for the flue gas desulfurization system, by designing the judgment logic of the change amplitude of the total amount of SO2 in the original flue gas, two control modes of cascade adjustment of the concentration value of SO2 in the purified flue gas and the pH value of slurry in an absorption tower and adjustment of the concentration of SO2 in the purified flue gas are automatically selected, and the limestone slurry supply amount needed by absorption of SO2 in the original flue gas is corrected in time; the problems that the control of the existing system is lagged and the emission of flue gas pollutants exceeds the standard under the working condition that the total amount of SO2 in the original flue gas is greatly changed are solved; according to the method, the pH value set value of the slurry is automatically corrected by adopting a logic signal that the SO2 concentration of the purified flue gas is close to an emission limit value, a unit load instruction change signal and a dust content change signal in the flue gas, the disturbance of unit parameter change on the pH value of the slurry is quickly responded, the dynamic compensation of the pH value control of the slurry under the full working condition of desulfurization is realized, the SO2 in the flue gas is more effectively absorbed, and the desulfurization efficiency is improved. The waste of the limestone slurry is avoided; meanwhile, the emission environment-friendly standard requirement is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of industrial process control, in particular to a full-condition slurry supply control system and method for a flue gas desulfurization system. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] In a limestone-gypsum wet flue gas desulfurization system of a power plant, the existing control strategy calculates the limestone (CaCO3) slurry supply amount required by the desulfurization absorption tower according to the SO2 content of the original flue gas at the desulfurization inlet, and simultaneously corrects the slurry supply amount target value through cascade regulation of the SO2 concentration of the clean flue gas at the desulfurization outlet and the pH value of the slurry in the absorption tower, changes the opening of the limestone slurry supply regulating valve to control the slurry supply amount of the absorption tower, and controls the SO2 concentration of the clean flue gas and the pH value of the slurry within the normal range.

[0004] In the conventional control scheme, the pH value of the slurry in the absorption tower is only used to determine whether the limestone slurry supply amount and the sulfur content of the flue gas being reacted in the current absorption tower are matched. Due to the large volume of the desulfurization absorption tower slurry pool, the pH value has characteristics such as large delay and large inertia. When the SO2 content of the original flue gas changes greatly, the response of the slurry pH value is relatively slow, and the system is difficult to increase or decrease the slurry supply amount in time according to the change of the pH value, resulting in that the SO2 concentration of the clean flue gas exceeds the standard or the slurry supply is excessive. In addition, the desulfurization conventional control system only controls the pH value according to the deviation of the SO2 concentration of the clean flue gas outlet from the flue gas pollutant emission limit value, and does not consider the influence of other operating parameter disturbances of the desulfurization system on the pH value. When the SO2 concentration of the clean flue gas is close to the emission limit value, the unit load changes greatly, or the dust content in the flue gas is continuously too high, the pH value set value of the absorption tower slurry is not automatically adjusted accordingly, the slurry supply amount of the absorption tower is not accurately controlled, and the SO2 emission in the flue gas exceeds the standard or the slurry supply is excessive for a long time. The conventional control scheme obviously does not meet the requirements of the full-condition slurry supply control of the flue gas desulfurization system. SUMMARY

[0005] In order to solve the problems in the prior art, the present application provides a flue gas desulfurization system full-condition slurry supply control system and method, which automatically selects a clean flue gas SO2 concentration value and absorption tower slurry pH value cascade regulation and clean flue gas SO2 concentration regulation two control modes by designing original flue gas SO2 mass flow variation range judgment logic, and timely corrects limestone slurry supply amount required for original flue gas SO2 absorption, solves the problems of existing system control lag and flue gas pollutant emission exceeding the standard under the condition of large amplitude variation of original flue gas SO2 mass flow; the slurry pH value set value is automatically corrected by using a clean flue gas SO2 concentration close to emission limit value logic signal, unit load instruction variation signal and flue gas dust content variation signal, the disturbance of unit parameter variation on the slurry pH value is quickly responded, and dynamic compensation of slurry pH value control under the condition of desulfurization is realized, while meeting the requirement of emission environmental protection standard, the limestone slurry supply amount is effectively saved.

[0006] In order to achieve the above object, the present application adopts the following technical scheme: In a first aspect, the present application provides a flue gas desulfurization system full-condition slurry supply control system.

[0007] The flue gas desulfurization system full-condition slurry supply control system at least comprises: an analog quantity switch, a first adder, a delay device and a high value overrun module; The original flue gas mass flow is input to the first adder and the delay device respectively, the first adder compares the original flue gas mass flow with the output result of the delay device to generate an original flue gas SO2 mass flow variation, and the high value overrun module receives the original flue gas SO2 mass flow variation and compares it with an internal limit value; When the original flue gas SO2 mass flow variation is greater than the limit value, or the slurry pH value meter is in a flushing state, the analog quantity switch is turned on to correct the slurry supply set value; otherwise, the analog quantity switch selects to turn on the clean flue gas SO2 concentration value control and absorption tower slurry pH value cascade regulation signal to correct the slurry supply set value.

[0008] In an implementation form of the first aspect of the present application, the generation of the clean flue gas SO2 concentration value control signal comprises: The first lead-lag module receives a clean flue gas SO2 concentration measured value, the clean flue gas SO2 controller receives the output of the first lead-lag module and a clean flue gas SO2 concentration set value, generates a clean flue gas SO2 concentration value control signal, and the output of the clean flue gas SO2 controller is connected with a one-way selection switch contact of the analog quantity switch.

[0009] In an implementation form of the first aspect of the present application, the generation of the clean flue gas SO2 concentration value control and absorption tower slurry pH value cascade regulation signal comprises: The first lead-lag module receives a measured value of SO2 concentration of the flue gas, and the flue gas SO2 controller receives an output of the first lead-lag module and a set value of the SO2 concentration of the flue gas to generate a control signal of the SO2 concentration of the flue gas; The first function generator receives the control signal of the SO2 concentration of the flue gas, the second function generator receives the output of the first lead-lag module, the third function generator receives the load instruction signal of the unit, and the fourth function generator receives the dust concentration of the raw flue gas. The outputs of the first function generator, the second function generator, the third function generator and the fourth function generator are superimposed by the second adder to generate the set value of the slurry pH. The second lead-lag module receives a measured value of the slurry pH, and the slurry pH controller receives an output of the second lead-lag module and a set value of the slurry pH. The output of the slurry pH controller is connected to another select switch contact of the analog switch after being limited by the limiter.

[0010] As a further limitation of the first aspect of the application, the third function generator and the fourth function generator have the same structure, and each includes a differential controller, a filter module and a polyline function generator connected in series.

[0011] In an implementation form of the first aspect of the application, the raw flue gas mass flow is obtained by: The first filter module is configured to receive the flue gas volume flow, the second filter module is configured to receive the SO2 mass volume concentration of the raw flue gas, and the first multiplier is configured to multiply the outputs of the first filter module and the second filter module to output the raw flue gas mass flow.

[0012] In an implementation form of the first aspect of the application, the second multiplier multiplies the raw flue gas mass flow with a constant value of the molar ratio to output to the third multiplier. The third multiplier multiplies the output of the second multiplier with the output of the analog switch to input to the slurry supply controller. The slurry supply controller also receives the limestone content, and the output of the slurry supply controller acts on the slurry supply regulating valve.

[0013] As a further limitation of the first aspect of the application, the fourth multiplier multiplies the output of the third filter module with the output of the fourth filter module to obtain the limestone content. The third filter module is configured to filter the input slurry mass flow, and the fourth filter module is configured to filter the input slurry mass concentration.

[0014] The second aspect of the application provides a full-condition slurry supply control method for a flue gas desulfurization system.

[0015] A full-condition slurry supply control method for a flue gas desulfurization system includes the following processes: The original flue gas SO2 mass flow and the original flue gas SO2 mass flow after being processed by the time delay device are compared to generate the original flue gas SO2 mass flow change data in unit time; When the original flue gas SO2 mass flow change data is greater than the set limit value or the slurry pH meter is in the flushing state signal, the clean flue gas SO2 concentration control is executed to correct the slurry supply amount set value; When the original flue gas SO2 mass flow change data is less than or equal to the set limit value and the slurry pH meter is not in the flushing state signal, the cascade regulation of the clean flue gas SO2 concentration control and the absorption tower slurry pH value control is executed to correct the slurry supply amount set value.

[0016] In an implementation form of the second aspect of the present application, the limestone slurry pH feedforward signal composed of the clean flue gas SO2 concentration close to the emission limit value logic signal, the unit load instruction change amount logic signal and the flue gas dust content change amount logic signal is superimposed and calculated with the output signal of the clean flue gas SO2 concentration controller, and then output as the limestone slurry pH set value; The limestone slurry pH measured value is compared with the limestone slurry pH set value after being processed by a lead-lag device, and the comparison result is processed by a limiting device to be used as the flue gas SO2 concentration value and the absorption tower slurry pH cascade regulation signal.

[0017] In an implementation form of the second aspect of the present application, the flue gas volume flow data is filtered, and then multiplied with the filtered original flue gas SO2 concentration mass volume concentration data to generate the original flue gas SO2 mass flow, which is multiplied with the fixed molar ratio of CaCO3 and SO2 to obtain the theoretical limestone mass set value, which is multiplied with the slurry supply amount set value correction coefficient output by the analog quantity switching switch to be used as the set value of the actual required limestone mass; The filtered slurry supply mass flow data and the filtered slurry concentration data are multiplied to generate the limestone mass flow data in the slurry as the real-time limestone content measurement value; The limestone mass set value and the real-time limestone content measurement value are controlled by the slurry supply amount controller to be output as the instruction signal of the limestone slurry regulating valve opening degree.

[0018] Compared with the prior art, the present application has the following beneficial effects: 1. The full working condition slurry supply control system of the flue gas desulfurization system is innovatively provided in the present application, through design of the original flue gas SO2 mass flow variation range judgment logic, when the original flue gas SO2 mass flow variation range is large, or the absorption tower slurry pH value meter is in the flushing state, the net flue gas SO2 concentration is selected as the feedback control correction slurry supply amount set value, the limestone slurry supply amount is adjusted in time, the flue gas SO2 emission is ensured to be not over standard, when the unit operation is stable, the original flue gas SO2 mass flow variation is not large, the net flue gas SO2 concentration value and the absorption tower slurry pH value are selected to correct the slurry supply amount set value through cascade regulation, the limestone slurry flow is accurately adjusted, the given desulfurization efficiency is realized, and meanwhile the appropriate slurry pH value is maintained, and the limestone slurry supply amount and the sulfur content in flue gas are ensured to be matched.

[0019] 2. The full working condition slurry supply control method of the flue gas desulfurization system is innovatively provided in the present application, the net flue gas SO2 concentration close to the emission limit value logic signal, the unit load instruction variation signal and the dust content variation signal in flue gas are used as the feedforward signals of the absorption tower slurry pH value controller, the pH set value is automatically adjusted according to the variation of the running working condition, the limestone slurry amount can be timely and accurately adjusted, the SO2 in flue gas is more effectively absorbed, the flue gas SO2 concentration can meet the requirements of the environmental protection emission standard, and the limestone slurry waste is avoided.

[0020] 3. The full working condition slurry supply control method of the flue gas desulfurization system is innovatively provided in the present application, which is suitable for various boiler control system DCS (Distributed Control System) or PLC (Programmable Logic Controller), convenient to configure, and has good application prospect.

[0021] The advantages of the additional aspects of the present application will be partly given in the following description, partly will become obvious from the following description, or will be known by the practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0022] The drawings accompanying the specification of the present application serve to provide further understanding of the present application, the illustrative embodiments of the present application and the description thereof serve to explain the present application, and do not constitute improper limitation on the present application.

[0023] Figure 1 The schematic diagram of the full working condition slurry supply control system of the flue gas desulfurization system provided for one exemplary embodiment of the present application is shown. DETAILED DESCRIPTION

[0024] The present application will be further described below in combination with the drawings and embodiments.

[0025] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0026] This implementation proposes a full-condition slurry supply control system for a flue gas desulfurization system, such as... Figure 1 As shown, it includes: a first lead-lag module 1, a clean flue gas SO2 concentration controller 2, an analog quantity switching switch 3, a first function generator 4, a first adder 5, a second function generator 6, a third function generator 7, a fourth function generator 8, a slurry pH controller 9, a limiter 10, a second lead-lag module 11, a first filter module 12, a first multiplier 13, a second filter module 14, a second multiplier 15, a delay unit 16, a second adder 17, a high value over-limit module 18, an OR gate logic module 19, a third multiplier 20, a slurry supply controller 21, a third filter module 22, a fourth filter module 23, a fourth multiplier 24, a slurry supply regulating valve 25, a differential controller 26, a fifth filter module 27, and a piecewise linear function generator 28.

[0027] The flue gas SO2 concentration controller 2 is used to receive the set value of flue gas SO2 concentration and the measured value of flue gas SO2 concentration after passing through the first lead-lag module 1. The output terminal of the flue gas SO2 concentration controller 2 is connected to the first input port of the analog quantity switch 3. The slurry pH controller 9 is used to receive the set value of slurry pH value output from the first adder 5 and the measured value of slurry pH value after passing through the second lead-lag module 10. The output terminal of the slurry pH controller 9 is connected to the second input port of the analog quantity switch 3.

[0028] The output of the clean flue gas SO2 concentration controller 2 is connected to the first input port of the first adder 5 after being output from the first function generator 4. The measured value of the clean flue gas SO2 concentration is connected to the second input port of the first adder 5 after being output from the first lead-lag module 1 and the second function generator 6 in sequence. The unit load command signal is connected to the third input port of the first adder 5 after being output from the third function generator 7. The original flue gas dust concentration value is connected to the fourth input port of the first adder 5 after being output from the fourth function generator 8. The first adder 5 simultaneously receives the signals from the above four input terminals. The output value of the first adder 5 is used as the set value of the slurry pH value, and its output terminal is connected to the negative input terminal of the slurry pH controller 9. Among them, the third function generator 7 is composed of... Figure 1 The differential controller 26, the fifth filter module 27, and the piecewise linear function generator 28 within the dashed frame are connected in series; the fourth function generator 8 is also composed of... Figure 1 The differential controller 26, the fifth filter module 27, and the piecewise linear function generator 28 within the dashed frame are connected in series.

[0029] The first multiplier 13 is used to receive the flue gas volume flow signal after the first filtering module 12 and the raw flue gas SO2 concentration mass volume concentration signal after the second filtering module 14 and generate the raw flue gas SO2 mass flow data (i.e. the raw flue gas SO2 total amount data), the output end of the first multiplier 13 and its output end after the time delay device 16 are respectively connected to the second adder 17 and generate the raw flue gas SO2 mass flow change amount data per unit time after comparison, the output end of the second adder 17 is connected to the input end of the high value overrun module 18, the output end of the high value overrun module 18 and the flushing state signal of the slurry pH meter are respectively connected to the input end of the or gate logic module 19, and the output end of the or gate logic module 19 is connected to the switching trigger signal input end of the analog quantity switching switch 3.

[0030] The second multiplier 15 is used to receive the raw flue gas SO2 mass flow data of the output end of the first multiplier 13 and the fixed molar ratio of SO2 and desulfurizer limestone (CaCO3) and generate the limestone mass flow data in the slurry, the output end of the second multiplier 15 and the output end of the analog quantity switching switch 3 (outputting the slurry amount setting value correction coefficient) are respectively connected to the two input ends of the third multiplier 20, and the output end of the third multiplier 20 is connected to the positive input end of the slurry amount controller 21.

[0031] The fourth multiplier 24 is used to receive the slurry mass flow signal after the third filtering module 22 and the slurry concentration signal after the fourth filtering module 23 and generate the limestone mass flow data in the slurry, the output end of the fourth multiplier 24 is connected to the negative input end of the slurry amount controller 21, and the output end of the slurry amount controller 21 is connected to the input end of the slurry adjusting valve 25.

[0032] Based on the above-mentioned flue gas desulfurization system full working condition slurry control system, Figure 1 A flue gas desulfurization system full working condition slurry control method is shown, which includes the following processes: The raw flue gas SO2 mass flow data and the raw flue gas SO2 mass flow data after the time delay device 16 are compared to generate the raw flue gas SO2 mass flow change amount data per unit time; When the raw flue gas SO2 mass flow change amount data is greater than the limit value set by the high value overrun module 18 or the slurry pH meter is in the flushing state, the analog quantity switching switch 3 is automatically triggered to select the output signal of the clean flue gas SO2 concentration controller 2 to be conducted to correct the slurry amount setting value and timely adjust the limestone slurry flow; When the raw flue gas SO2 mass flow change amount data is not greater than the limit value set by the high value overrun module 18 and the slurry pH meter is not in the flushing state, the analog quantity switching switch 3 is automatically triggered to select the clean flue gas SO2 concentration value and the absorption tower slurry pH value to be conducted to correct the slurry amount setting value and accurately adjust the limestone slurry flow; The limestone slurry pH value feedforward signal composed of the net flue gas SO2 concentration close to the emission limit value logic signal, the unit load instruction change amount logic signal and the flue gas dust content change amount logic signal is superimposed and calculated with the output signal of the net flue gas SO2 concentration controller 2, and the output is taken as the limestone slurry pH value set value; the limestone slurry pH measured value is compared with the limestone slurry pH value set value after being processed by a lead-lag processor, and the comparison result is processed by a limiter 10 and taken as the flue gas SO2 concentration value and the absorption tower slurry pH value cascade regulation signal.

[0033] In the present implementation, the net flue gas SO2 concentration measured value is sequentially output as one of the slurry pH value feedforward signals after being output by the first lead-lag module 1 and the second function generator 2, which realizes that when the net flue gas SO2 concentration measured value approaches the exceeding limit value, the desulfurization slurry pH value set value is automatically increased appropriately to speed up the absorption of SO2 in the flue gas and avoid flue gas emission exceeding the standard; the unit load instruction signal is output by the third function generator 7 as one of the slurry pH value feedforward signals, wherein the third function generator 7 is specifically composed of a derivative controller 26, a filter module 27 and a polyline function generator 28 in series, which realizes that when the unit load instruction signal changes greatly, the desulfurization slurry pH value set value is automatically adjusted appropriately to avoid that the slurry pH cannot meet the requirements when the load is increased too quickly, and the limestone slurry supply amount does not match the sulfur content in the flue gas; the original flue gas dust concentration value is output by the fourth function generator 8 as one of the slurry pH value feedforward signals, wherein the fourth function generator 8 is specifically composed of a derivative controller 26, a filter module 27 and a polyline function generator 28 in series, which realizes that when the original flue gas dust concentration value changes greatly, the desulfurization slurry pH value set value is automatically adjusted appropriately to avoid that the slurry is supplied excessively when the dust concentration in the flue gas is too high for a long time.

[0034] The flue gas volume flow data is multiplied by the filtered original flue gas SO2 concentration mass volume concentration data to generate the original flue gas SO2 mass flow (mass flow), the original flue gas SO2 mass flow is multiplied by the fixed molar ratio of CaCO3 to SO2 to obtain the theoretical limestone mass set value, and the theoretical limestone mass set value is multiplied by the slurry supply amount set value correction coefficient output by the analog quantity switching switch 3 to obtain the set value of the actual required limestone mass. The data of the slurry supply mass flow after the filtering module and the data of the slurry concentration after the filtering module are multiplied to generate the limestone mass flow data in the slurry as the real-time measurement value of the limestone content. The set value of the limestone mass and the real-time measurement value of the limestone content are controlled by the slurry supply amount controller 21 to output as the instruction signal of the limestone slurry regulating valve 25 opening degree, and finally realize the limestone slurry flow control.

[0035] In the present application, the full working condition slurry supply control system of the flue gas desulfurization system is used, the SO2 concentration of the clean flue gas, the slurry pH value, the unit load instruction, the original flue gas dust concentration, the flue gas volume flow, the original flue gas SO2 concentration, the slurry supply mass flow and the slurry supply concentration are detected, and the measured data are introduced into the DCS system, so that the full working condition slurry supply control logic of the flue gas desulfurization system can be designed, and specifically, the following processes are included: The PI controller is designed for the slurry supply regulator 25 because the introduction of the differential control can easily cause the regulation system to shake and the execution structure of the regulator to be damaged easily, the PID controller is designed for the SO2 concentration controller 2 of the clean flue gas and the slurry pH value controller 9; The set value of the pH value controller is set to be 5.2-5.8; The set value of the limiter 10 of the pH value controller is set to be 0.85-1.15; The fixed molar ratio of CaCO3 (limestone) to SO2 is 100 / 64; The time of the time delay device 16 is set to be 10 seconds; The set value of the high value over-limit module 18 is set to be 10% of the original flue gas SO2 mass flow; The filter time of the first filter module 12 and the second filter module 14 is set to be 5 seconds, the filter time of the third filter module 22 and the fourth filter module 23 is set to be 2 seconds, and the filter time of the filter modules in the third function generator 7 and the fourth function generator 8 is set to be 3 seconds; According to the above scheme, the full working condition slurry supply control logic of the flue gas desulfurization system is designed by using the DCS configuration software; After the control logic is compiled, the DCS configuration software is checked, and then the control logic is downloaded to the DCS controller; The SO2 concentration controller 2 of the clean flue gas, the slurry pH value controller 9 and the slurry supply amount controller 21 are designed in the picture of the DCS operator station, so that the operation personnel of the unit can manually correct the controller setting parameters, set the bias amount and switch the manual / automatic state and the like on the DCS picture.

[0036] The above only describes the preferred embodiments of the present application and is not used to limit the present application, and the present application can have various modifications and changes for the person skilled in the art. Any modification, equivalent replacement, improvement and the like within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A full-condition slurry supply control system for a flue gas desulfurization system, characterized in that, It includes at least: an analog quantity switching switch, a first adder, a timer, and a high-value over-limit module; The raw flue gas mass flow rate is input to the first adder and the delay unit respectively. The first adder compares the raw flue gas mass flow rate with the output result of the delay unit to generate the change in the raw flue gas SO2 mass flow rate. The high-value over-limit module receives the change in the raw flue gas SO2 mass flow rate and compares it with the built-in limit value. When the change in the mass flow rate of SO2 in the raw flue gas exceeds the limit, or when the pH meter of the slurry is in the flushing state, the analog switch activates the control signal for the SO2 concentration of the clean flue gas to correct the slurry supply setpoint; otherwise, the analog switch selects to activate the cascade adjustment signal between the SO2 concentration control of the clean flue gas and the pH value of the absorber slurry to correct the slurry supply setpoint.

2. The flue gas desulfurization system full-condition slurry supply control system as described in claim 1, characterized in that, The generation of the control signal for the SO2 concentration value in the clean flue gas includes: The first lead-lag module receives the measured value of SO2 concentration in the clean flue gas. The clean flue gas SO2 controller receives the output of the first lead-lag module and the set value of SO2 concentration in the clean flue gas, generates a control signal for SO2 concentration in the clean flue gas, and connects the output of the clean flue gas SO2 controller to one of the selector contacts of the analog quantity switching switch.

3. The flue gas desulfurization system full-condition slurry supply control system as described in claim 1, characterized in that, The generation of signals for controlling SO2 concentration in clean flue gas and cascading pH adjustment in the absorber slurry includes: The first lead-lag module receives the measured value of SO2 concentration in the clean flue gas, and the clean flue gas SO2 controller receives the output of the first lead-lag module and the set value of SO2 concentration in the clean flue gas, and generates a control signal for SO2 concentration in the clean flue gas. The first function generator receives the SO2 concentration control signal of the clean flue gas, the second function generator receives the output of the first lead-lag module, the third function generator receives the unit load command signal, and the fourth function generator receives the dust concentration of the original flue gas. The second adder superimposes the outputs of the first function generator, the second function generator, the third function generator and the fourth function generator to generate the slurry pH set value. The second lead-lag module receives the measured pH value of the slurry, and the slurry pH controller receives the output of the second lead-lag module and the set pH value of the slurry. The output of the slurry pH controller is connected to the other selector switch contact of the analog quantity switching switch after passing through the limiter.

4. The flue gas desulfurization system full-condition slurry supply control system as described in claim 3, characterized in that, The third function generator has the same structure as the fourth function generator, both including a differential controller, a filter module, and a piecewise linear function generator connected in series.

5. The flue gas desulfurization system full-condition slurry supply control system as described in any one of claims 1-4, characterized in that, Obtaining the raw flue gas mass flow rate includes: The first filter module is used to receive the flue gas volume flow rate, the second filter module is used to receive the original flue gas SO2 mass volume concentration, and the first multiplier is used to multiply the output of the first filter module and the output of the second filter module to output the original flue gas mass flow rate.

6. The flue gas desulfurization system full-condition slurry supply control system as described in any one of claims 1-4, characterized in that, The second multiplier multiplies the original flue gas mass flow rate by the molar ratio constant and outputs the result to the third multiplier. The third multiplier multiplies the output of the second multiplier with the output of the analog quantity switch, and then inputs the result to the grout supply controller. The grout supply controller also receives the limestone content, and its output acts on the grout supply regulating valve.

7. The flue gas desulfurization system full-condition slurry supply control system as described in claim 6, characterized in that, The fourth multiplier multiplies the output of the third filter module with the output of the fourth filter module to obtain the limestone content. The third filter module is used to filter the input slurry mass flow rate, and the fourth filter module is used to filter the input slurry mass concentration.

8. A method for controlling slurry supply under all operating conditions in a flue gas desulfurization system, characterized in that, Includes the following processes: The mass flow rate of SO2 in the raw flue gas is compared with the mass flow rate of SO2 in the raw flue gas after the delay device to generate data on the change in mass flow rate of SO2 in the raw flue gas per unit time. When the change in the mass flow rate of SO2 in the raw flue gas exceeds the set limit, or when the pH meter of the slurry is in the flushing state signal, the SO2 concentration of the clean flue gas is controlled to correct the slurry supply set value. When the change in the mass flow rate of SO2 in the raw flue gas is less than or equal to the set limit, and the pH meter of the slurry is not in the flushing state signal, the cascade regulation of the SO2 concentration control in the clean flue gas and the pH control of the absorber slurry is executed to correct the slurry supply set value.

9. The method for controlling the slurry supply under all operating conditions of a flue gas desulfurization system as described in claim 8, characterized in that, The limestone slurry pH value feedforward signal, which is composed of the logic signal of SO2 concentration in clean flue gas approaching the emission limit, the logic signal of unit load command change, and the logic signal of dust content change in flue gas, is superimposed with the output signal of SO2 concentration controller in clean flue gas and output as the set value of pH value of limestone slurry. The measured pH value of limestone slurry was compared with the set pH value of limestone slurry after being processed by lead-lag. The comparison result was then processed by amplitude limiting and used as the cascade adjustment signal for flue gas SO2 concentration and absorption tower slurry pH value.

10. The method for controlling the slurry supply under all operating conditions of a flue gas desulfurization system as described in claim 8, characterized in that, The flue gas volume flow rate data is filtered and multiplied with the original flue gas SO2 concentration mass volume concentration data to generate the original flue gas SO2 mass flow rate. The original flue gas SO2 mass flow rate is multiplied with the fixed molar ratio of CaCO3 to SO2 to obtain the theoretical limestone mass set value. The theoretical limestone mass set value is multiplied with the correction coefficient of the slurry supply set value output by the analog quantity switch to obtain the actual required limestone mass set value. The filtered data of slurry mass flow rate and the filtered data of slurry concentration are multiplied together to generate limestone mass flow rate data in the slurry, which is used as the real-time measurement value of limestone content. The set value of limestone quality and the real-time measured value of limestone content are controlled by the slurry supply controller, which outputs a command signal as the opening degree of the limestone slurry supply regulating valve.

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