Slurry supply control method for coal power wet desulfurization system

Abstract

The application provides a slurry supply control method of a coal power wet desulfurization system, and belongs to the technical field of flue gas desulfurization control. The method can at least partially solve the problem that the existing technology has obvious hysteresis in the response of slurry pH value to inlet working condition changes, and in the case of large fluctuations of unit load and inlet sulfur dioxide concentration, it is difficult to timely adjust the slurry supply amount by simply relying on pH value feedback control, which easily leads to the problems of increased energy consumption of the desulfurization system, waste of absorbent, and even the risk of outlet sulfur dioxide emission exceeding the limit in extreme working conditions. The application can improve the anti-disturbance ability of slurry supply control when the inlet working condition changes rapidly, reduce the energy consumption of the desulfurization system when the working condition is stable, reduce the waste of absorbent, and improve the safety, stability and economy of the desulfurization system under the conditions of deep peak shaving and wide load operation.

Description

Technical Field

[0001] This invention belongs to the field of flue gas desulfurization control technology, specifically relating to a slurry supply control method for a coal-fired power plant wet desulfurization system. Background Technology

[0002] SO2 produced by coal combustion is one of the major air pollutants in my country. Wet flue gas desulfurization (FGD) technology is widely used in thermal power plants due to its advantages such as low desulfurization cost and high efficiency. This desulfurization process uses limestone slurry as an absorbent to remove SO2 from flue gas. Real-time replenishment of limestone slurry is crucial in the entire desulfurization system, and slurry supply control is the most important part of wet FGD operation. Automatic control of the slurry supply is of great significance for improving desulfurization efficiency and reducing operating costs.

[0003] In existing power plants, most desulfurization systems still operate in a manual or semi-automatic manner. Even if some power plants have achieved automatic control, they mainly adopt a single-loop feedback control method with the pH value of the absorber slurry as the controlled variable. That is, the pH controller drives the slurry regulating valve or the slurry pump frequency converter to maintain the pH value of the slurry at the set value.

[0004] The aforementioned control method has a simple structure, but its anti-disturbance capability is weak. During the operation of the desulfurization system, the slurry pH value is easily affected by changes in slurry flow rate, as well as changes in the flue gas volume and sulfur dioxide concentration at the desulfurization system inlet. The former is a process input disturbance, while the latter is a measurable external disturbance. Although existing technologies have introduced cascade control or feedforward control strategies based on PID algorithms to mitigate the impact of slurry flow rate disturbances, the slurry pH value is still treated as the sole primary control variable.

[0005] Because the pH value of the slurry has a significant lag in response to changes in inlet operating conditions, when the unit load and inlet sulfur dioxide concentration fluctuate greatly, it is difficult to adjust the slurry supply in a timely manner by simply relying on pH feedback control. This can easily lead to increased energy consumption of the desulfurization system, waste of absorbent, and even the risk of exceeding the limit of outlet sulfur dioxide emissions under extreme operating conditions. Therefore, we propose a slurry supply control method for coal-fired power wet desulfurization systems. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art, and to provide a slurry supply control method for a coal-fired wet desulfurization system.

[0007] This invention provides a slurry supply control method for a coal-fired power plant wet desulfurization system, comprising the following steps: S1: Real-time acquisition of the inlet flue gas volume flow rate and sulfur dioxide concentration in the inlet flue gas of the coal-fired power plant wet desulfurization system, and calculation of the actual inlet sulfur dioxide mass flow rate; S2: Obtain the design inlet flue gas volume flow rate and design inlet sulfur dioxide concentration based on the design parameters of the coal-fired power plant wet desulfurization system, and calculate the design sulfur dioxide mass flow rate. S3: Calculate the ratio between the actual sulfur dioxide mass flow rate at the inlet and the designed sulfur dioxide mass flow rate, and calculate the rate of change of the ratio over time; S4: Based on the ratio and the fluctuation rate, select the slurry supply control strategy of the coal-fired wet desulfurization system, and switch between a safety control mode that aims to stabilize the pH value of the slurry and an energy-saving control mode that aims to achieve 80% to 90% of the emission limit of the outlet emission value of the coal-fired wet desulfurization system.

[0008] Further, in step S1, the step of obtaining the actual sulfur dioxide mass flow rate at the inlet is as follows: The volumetric flow rate of the inlet flue gas of the coal-fired power plant wet desulfurization system is multiplied by the sulfur dioxide concentration in the inlet flue gas, and the units are converted to obtain the sulfur dioxide mass flow rate per unit time.

[0009] Specifically, in step S2, the step of obtaining the designed sulfur dioxide mass flow rate is as follows: Multiply the designed inlet flue gas volume flow rate of the coal-fired power plant wet desulfurization system by the designed inlet sulfur dioxide concentration of the desulfurization system, and perform unit conversion to obtain the sulfur dioxide mass flow rate per unit time under the design operating conditions.

[0010] Specifically, the formula for calculating the ratio between the actual sulfur dioxide mass flow rate at the inlet and the designed sulfur dioxide mass flow rate is as follows:

[0011] in, This represents the actual sulfur dioxide mass flow rate at the inlet. To design the mass flow rate of sulfur dioxide.

[0012] Preferably, in step S3, the method for obtaining the fluctuation rate of the ratio is as follows: The ratio is continuously sampled within a preset time window, and the percentage change of the ratio per unit time is calculated.

[0013] Specifically, when the fluctuation rate of the ratio is less than 3% / min, the corresponding slurry supply control strategy of the desulfurization system is selected according to the magnitude of the ratio.

[0014] Furthermore, when the fluctuation rate of the ratio is less than 3% / min and the ratio is greater than or equal to 75%, the desulfurization system adopts the energy-saving control mode to make the sulfur dioxide emission concentration at the outlet of the coal-fired wet desulfurization system reach 80% to 90% of the emission limit, and reduces the energy consumption of the coal-fired wet desulfurization system by adjusting the limestone slurry supply in the coal-fired wet desulfurization system.

[0015] Furthermore, when the fluctuation rate of the ratio is less than 3% / min and when the ratio is less than 75%, the coal-fired wet desulfurization system adopts a safety control mode to stabilize the pH value of the slurry, and controls the pH value of the slurry in the absorption tower of the coal-fired wet desulfurization system within the range of 5.4 to 5.8.

[0016] Furthermore, the slurry supply control method is applicable to the coal-fired wet desulfurization system with a peak-shaving operation capacity of 30% or less of the rated load.

[0017] Specifically, when the fluctuation rate of the ratio is greater than or equal to 3% / min, the slurry supply control of the coal-fired wet desulfurization system adopts the energy-saving control mode. The energy-saving control mode enables the sulfur dioxide emission concentration at the outlet of the coal-fired wet desulfurization system to reach 80%~90% of the emission limit, and reduces the energy consumption of the coal-fired wet desulfurization system by adjusting the limestone slurry supply in the coal-fired wet desulfurization system.

[0018] The beneficial effects of this invention are as follows: This technology introduces the ratio of the actual sulfur dioxide mass flow rate at the inlet to the designed sulfur dioxide mass flow rate, and combines this ratio's fluctuation rate to identify the operating conditions of the desulfurization system. This allows slurry supply control to no longer rely solely on the single, lagging process variable of the absorber slurry pH value, but rather on key parameters that comprehensively reflect the load level and inlet boundary condition changes of the desulfurization system. This fundamentally improves the adaptability and targeting of the slurry supply control strategy to changes in operating conditions. Based on the ratio and its fluctuation rate, the system can switch between a safe slurry supply control mode that aims to stabilize the slurry pH value and an energy-saving slurry supply control mode that aims to achieve 80%~90% of the desulfurization system outlet emission value of the stated emission limit. This enables the desulfurization system to automatically select a more reasonable control target under different operating conditions. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the steps of a slurry supply control method for a coal-fired wet desulfurization system according to a specific embodiment of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] like Figure 1 As shown in the figure, a slurry supply control method for a coal-fired wet desulfurization system provided by a specific embodiment of the present invention includes the following steps: S1: Real-time acquisition of the inlet flue gas volume flow rate and sulfur dioxide concentration in the inlet flue gas of the coal-fired power plant wet desulfurization system, and calculation of the actual inlet sulfur dioxide mass flow rate; S2: Obtain the design inlet flue gas volume flow rate and design inlet sulfur dioxide concentration based on the design parameters of the coal-fired power plant wet desulfurization system, and calculate the design sulfur dioxide mass flow rate. S3: Calculate the ratio between the actual sulfur dioxide mass flow rate at the inlet and the designed sulfur dioxide mass flow rate, and calculate the rate of change of the ratio over time; S4: Based on the ratio and fluctuation rate, select the slurry supply control strategy for the coal-fired power plant wet desulfurization system, switching between a safety control mode aimed at stabilizing the slurry pH value and an energy-saving control mode aimed at achieving 80%~90% of the emission limit at the outlet of the coal-fired power plant wet desulfurization system; where the emission limit is 35mg / m³. 3 At that time, the export emission value is set at 85% to 90% of the limit; the emission limit is less than 20 mg / m³. 3 At that time, the export emission value is set at 80% to 85% of the limit.

[0022] Specifically, to achieve the above-mentioned slurry supply control method, the measuring components, the control and calculation components, and the execution components need to work together. The components are arranged around the inlet flue, the absorption tower, the slurry supply pipeline and the outlet flue of the desulfurization system, and form a complete closed-loop control structure through the control system.

[0023] Furthermore, to achieve step S1, a flue gas volumetric flow rate measuring device is installed in the inlet flue of the absorber tower of the coal-fired power plant wet desulfurization system to measure the flue gas volumetric flow rate entering the desulfurization system in real time; simultaneously, a sulfur dioxide concentration measuring device is installed in the same inlet flue to obtain the sulfur dioxide concentration in the inlet flue gas in real time. Both the flue gas volumetric flow rate measuring device and the sulfur dioxide concentration measuring device are connected to the control system. The control system periodically collects the two measurement signals, performs validity judgment and necessary filtering on the signals, calculates the real-time flue gas volumetric flow rate and the real-time sulfur dioxide concentration, and completes the unit conversion to obtain the actual inlet sulfur dioxide mass flow rate per unit time.

[0024] Furthermore, to achieve step S2, the control system obtains the design inlet flue gas volumetric flow rate and the design inlet sulfur dioxide concentration based on the design documents or engineering configuration parameters of the desulfurization system, and stores them within the control system. The control system uses the same calculation method and unit system as the actual inlet sulfur dioxide mass flow rate to calculate and convert the design inlet flue gas volumetric flow rate and the design inlet sulfur dioxide concentration, obtaining the design sulfur dioxide mass flow rate under the design conditions, which serves as the benchmark for subsequent calculations.

[0025] Based on the above basic implementation method, the step of obtaining the actual sulfur dioxide mass flow rate at the inlet in step S1 is as follows: The volumetric flow rate of the inlet flue gas of the coal-fired power plant wet desulfurization system is multiplied by the sulfur dioxide concentration in the inlet flue gas, and the units are converted to obtain the sulfur dioxide mass flow rate per unit time.

[0026] Specifically, in the above steps, it is important to ensure that the inlet flue gas volumetric flow rate and sulfur dioxide concentration use a unified state reference and unit of measurement to avoid introducing systematic errors due to inconsistencies between the operating condition volumetric flow rate and the standard condition volumetric flow rate, and between the dry basis concentration and the wet basis concentration.

[0027] In one specific embodiment, the step of obtaining the design sulfur dioxide mass flow rate in step S2 is as follows: Multiply the designed inlet flue gas volume flow rate of the coal-fired power plant wet desulfurization system by the designed inlet sulfur dioxide concentration of the desulfurization system, and perform unit conversion to obtain the sulfur dioxide mass flow rate per unit time under the design operating conditions.

[0028] In this embodiment, the formula for calculating the ratio between the actual sulfur dioxide mass flow rate at the inlet and the designed sulfur dioxide mass flow rate is as follows:

[0029] in, This represents the actual sulfur dioxide mass flow rate at the inlet. To design the mass flow rate of sulfur dioxide.

[0030] Furthermore, in the above-mentioned steps, anomaly judgment should be made on the measurement signal. When the sulfur dioxide analyzer is in a backflushing, calibration or fault state, the calculation of the actual sulfur dioxide mass flow rate at the inlet should adopt the method of maintaining the previous effective value or entering degraded control to ensure the continuity and stability of the control process.

[0031] In another specific embodiment, the method for obtaining the fluctuation rate of the ratio in step S3 is as follows: The comparison values ​​are continuously sampled within a preset time window, and the percentage change of the ratio per unit time is calculated.

[0032] Specifically, to achieve step S3, the control system calculates the ratio between the actual sulfur dioxide mass flow rate at the inlet and the designed sulfur dioxide mass flow rate, and continuously samples the ratio within a preset time window; the control system processes the sampled data to calculate the percentage change of the ratio per unit time, thereby obtaining the fluctuation rate of the ratio, which is used to reflect the speed of change of the boundary conditions at the inlet of the desulfurization system.

[0033] In one specific implementation, when the fluctuation rate of the ratio is less than 3% / min, the corresponding slurry supply control strategy of the desulfurization system is selected according to the magnitude of the ratio.

[0034] In this embodiment, when the fluctuation rate of the ratio is less than 3% / min and the ratio is greater than or equal to 75%, the desulfurization system adopts an energy-saving control mode to make the sulfur dioxide emission concentration at the outlet of the coal-fired wet desulfurization system reach 80% to 90% of the emission limit, and the energy consumption of the coal-fired wet desulfurization system is reduced by adjusting the limestone slurry supply in the coal-fired wet desulfurization system.

[0035] Specifically, when the fluctuation rate of the ratio is less than 3% / min and the ratio is less than 75%, the coal-fired wet desulfurization system adopts a safety control mode with the goal of stabilizing the pH value of the slurry and controlling the pH value of the slurry in the absorption tower of the coal-fired wet desulfurization system within the range of 5.4 to 5.8.

[0036] In another specific embodiment, the slurry supply control method is applicable to coal-fired wet desulfurization systems with peak-shaving operation capacity of 30% or less of rated load.

[0037] Furthermore, when the fluctuation rate of the ratio is greater than or equal to 3% / min, the slurry supply control of the coal-fired wet desulfurization system adopts an energy-saving control mode. The energy-saving control mode enables the sulfur dioxide emission concentration at the outlet of the coal-fired wet desulfurization system to reach 80%~90% of the emission limit, and reduces the energy consumption of the coal-fired wet desulfurization system by adjusting the limestone slurry supply in the coal-fired wet desulfurization system.

[0038] Furthermore, the advantage of switching between safe slurry supply control mode and energy-saving slurry supply control mode lies in the ability to dynamically select a more suitable control objective based on the load level and inlet operating condition changes of the desulfurization system. When inlet operating conditions fluctuate significantly or the load is low, priority is given to ensuring system operational stability and rational utilization of absorbent. When inlet operating conditions are relatively stable and the desulfurization load is heavy, priority is given to ensuring economic efficiency and low energy consumption, thereby achieving a coordinated balance between the safety and economy of the desulfurization system. Setting the threshold for the ratio fluctuation rate to 3% aims to distinguish between rapidly changing and relatively stable inlet boundary conditions of the desulfurization system. When the fluctuation rate is less than this threshold, the system considers the inlet operating condition changes to be relatively gradual, and the slurry supply control strategy can be further optimized based on the ratio. When the fluctuation rate is greater than or equal to this threshold, the system considers the inlet operating condition changes to be relatively drastic, and prioritizes an energy-saving slurry supply control strategy that aims to achieve 80% to 90% of the emission limit at the desulfurization system outlet, preventing excessive fluctuations in outlet emissions or system instability.

[0039] To aid in a better understanding of the present invention, a more comprehensive and specific embodiment is described, in which the present invention provides a slurry supply control method for a coal-fired wet desulfurization system, comprising the following steps: S1: Real-time acquisition of the inlet flue gas volume flow rate and sulfur dioxide concentration in the inlet flue gas of the coal-fired power plant wet desulfurization system, and calculation of the actual inlet sulfur dioxide mass flow rate; S2: Obtain the design inlet flue gas volume flow rate and design inlet sulfur dioxide concentration based on the design parameters of the coal-fired power plant wet desulfurization system, and calculate the design sulfur dioxide mass flow rate. S3: Calculate the ratio between the actual sulfur dioxide mass flow rate at the inlet and the designed sulfur dioxide mass flow rate, and calculate the rate of change of the ratio over time; S4: Based on the ratio and fluctuation rate, select the slurry supply control strategy for the coal-fired wet desulfurization system, and switch between a safety control mode that aims to stabilize the pH value of the slurry and an energy-saving control mode that aims to achieve 80%~90% of the emission limit at the outlet of the coal-fired wet desulfurization system.

[0040] In this embodiment, the step of obtaining the actual sulfur dioxide mass flow rate at the inlet in step S1 is as follows: multiply the real-time collected flue gas volume flow rate at the inlet of the coal-fired power plant wet desulfurization system with the real-time collected sulfur dioxide concentration in the inlet flue gas, and perform unit conversion to obtain the sulfur dioxide mass flow rate per unit time. In step S2, the steps to obtain the design sulfur dioxide mass flow rate are as follows: multiply the design inlet flue gas volume flow rate of the coal-fired power plant wet desulfurization system by the design inlet sulfur dioxide concentration of the desulfurization system, and perform unit conversion to obtain the sulfur dioxide mass flow rate per unit time under the design operating conditions. The formula for calculating the ratio of the actual sulfur dioxide mass flow rate at the inlet to the designed sulfur dioxide mass flow rate is as follows:

[0041] in, This represents the actual sulfur dioxide mass flow rate at the inlet. To design the mass flow rate of sulfur dioxide; In step S3, the fluctuation rate of the ratio is obtained as follows: the ratio is continuously sampled within a preset time window, and the percentage change of the ratio per unit time is calculated.

[0042] Specifically, when the fluctuation rate of the ratio is less than 3% / min, the corresponding slurry supply control strategy of the desulfurization system is selected according to the magnitude of the ratio. When the fluctuation rate of the ratio is less than 3% / min and the ratio is greater than or equal to 75%, the desulfurization system adopts an energy-saving control mode to make the sulfur dioxide emission concentration at the outlet of the coal-fired wet desulfurization system reach 80% to 90% of the emission limit, and the energy consumption of the coal-fired wet desulfurization system is reduced by adjusting the limestone slurry supply in the coal-fired wet desulfurization system. When the fluctuation rate of the ratio is less than 3% / min and the ratio is less than 75%, the coal-fired power plant wet desulfurization system adopts a safety control mode with the goal of stabilizing the slurry pH value and controlling the slurry pH value in the absorption tower of the coal-fired power plant wet desulfurization system within the range of 5.4 to 5.8. The slurry supply control method is applicable to coal-fired power wet desulfurization systems with peak-shaving operation capacity of 30% or less of rated load; When the fluctuation rate of the ratio is greater than or equal to 3% / min, the slurry supply control of the coal-fired wet desulfurization system adopts the energy-saving control mode. The energy-saving control mode enables the sulfur dioxide emission concentration at the outlet of the coal-fired wet desulfurization system to reach 80%~90% of the emission limit, and reduces the energy consumption of the coal-fired wet desulfurization system by adjusting the limestone slurry supply in the coal-fired wet desulfurization system.

[0043] In summary, the embodiments disclosed herein have at least the following technical effects: This technology introduces the ratio of the actual sulfur dioxide mass flow rate at the inlet to the designed sulfur dioxide mass flow rate, and combines the fluctuation rate of this ratio to identify the operating conditions of the desulfurization system. This makes the slurry supply control no longer rely solely on the single, lagging process variable of the absorber slurry pH value, but rather on key parameters that comprehensively reflect the load level and inlet boundary condition changes of the desulfurization system. This fundamentally improves the adaptability and pertinence of the slurry supply control strategy to changes in operating conditions. Based on the ratio and its fluctuation rate, the system switches between a safe slurry supply control mode that aims to stabilize the slurry pH value and an energy-saving slurry supply control mode that aims to achieve 80%~90% of the emission limit at the desulfurization system outlet. This allows the desulfurization system to automatically select a more reasonable control target under different operating conditions. Compared to existing slurry supply control methods that use slurry pH value as the sole primary control variable, this method effectively avoids the problems of increased system energy consumption or waste of absorbent caused by improper pH setpoint selection. When the inlet flue gas volume and inlet sulfur dioxide concentration fluctuate rapidly, this technology prioritizes the slurry supply control mode aimed at system stability by judging the fluctuation rate of the comparative value. It can promptly suppress the impact of disturbances on the operation of the desulfurization system when there is a lag in the change of slurry pH, significantly improve the anti-interference ability of slurry supply control against external disturbances, and reduce the risk of exceeding the limit of outlet sulfur dioxide emissions. Under relatively stable inlet conditions and high desulfurization load, this technology uses the outlet emission value of the desulfurization system as the slurry supply control target, so that the outlet sulfur dioxide concentration is close to the emission limit. Under the premise of meeting environmental emission requirements, the supply of limestone slurry is reduced to the minimum, thereby reducing the power consumption, absorbent consumption and slurry treatment burden of the desulfurization system, and improving the overall economic efficiency of the system. By integrating inlet condition identification, control target selection, and slurry supply adjustment process into the automatic control logic, this technology reduces the need for operators to frequently adjust the slurry supply or pH setting, improves the automation level and operational consistency of the desulfurization system, and is especially suitable for long-term stable operation of the unit under deep peak shaving and wide load fluctuation conditions at 30% rated load and below.

[0044] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for controlling the slurry supply in a coal-fired power plant wet desulfurization system, characterized in that, Includes the following steps: S1: Real-time acquisition of the inlet flue gas volume flow rate and sulfur dioxide concentration in the inlet flue gas of the coal-fired power plant wet desulfurization system, and calculation of the actual inlet sulfur dioxide mass flow rate; S2: Obtain the design inlet flue gas volume flow rate and design inlet sulfur dioxide concentration based on the design parameters of the coal-fired power plant wet desulfurization system, and calculate the design sulfur dioxide mass flow rate. S3: Calculate the ratio between the actual sulfur dioxide mass flow rate at the inlet and the designed sulfur dioxide mass flow rate, and calculate the rate of change of the ratio over time; S4: Based on the ratio and the fluctuation rate, select the slurry supply control strategy of the coal-fired wet desulfurization system, and switch between a safety control mode that aims to stabilize the pH value of the slurry and an energy-saving control mode that aims to achieve 80% to 90% of the emission limit of the outlet emission value of the coal-fired wet desulfurization system.

2. The slurry supply control method for a coal-fired wet desulfurization system according to claim 1, characterized in that, In step S1, the steps for obtaining the actual sulfur dioxide mass flow rate at the inlet are as follows: The volumetric flow rate of the inlet flue gas of the coal-fired power plant wet desulfurization system is multiplied by the sulfur dioxide concentration in the inlet flue gas, and the units are converted to obtain the sulfur dioxide mass flow rate per unit time.

3. The slurry supply control method for a coal-fired wet desulfurization system according to claim 1, characterized in that, In step S2, the steps for obtaining the designed sulfur dioxide mass flow rate are as follows: Multiply the designed inlet flue gas volume flow rate of the coal-fired power plant wet desulfurization system by the designed inlet sulfur dioxide concentration of the desulfurization system, and perform unit conversion to obtain the sulfur dioxide mass flow rate per unit time under the design operating conditions.

4. The slurry supply control method for a coal-fired power plant wet desulfurization system according to claim 1, characterized in that, The formula for calculating the ratio of the actual sulfur dioxide mass flow rate at the inlet to the designed sulfur dioxide mass flow rate is as follows: in, This represents the actual sulfur dioxide mass flow rate at the inlet. To design the mass flow rate of sulfur dioxide.

5. The slurry supply control method for a coal-fired power plant wet desulfurization system according to claim 1, characterized in that, In step S3, the method for obtaining the fluctuation rate of the ratio is as follows: The ratio is continuously sampled within a preset time window, and the percentage change of the ratio per unit time is calculated.

6. The slurry supply control method for a coal-fired power plant wet desulfurization system according to claim 5, characterized in that, When the fluctuation rate of the ratio is less than 3% / min, the corresponding slurry supply control strategy of the desulfurization system is selected according to the magnitude of the ratio.

7. The slurry supply control method for a coal-fired wet desulfurization system according to claim 6, characterized in that, When the fluctuation rate of the ratio is less than 3% / min and the ratio is greater than or equal to 75%, the desulfurization system adopts the energy-saving control mode to make the sulfur dioxide emission concentration at the outlet of the coal-fired wet desulfurization system reach 80% to 90% of the emission limit, and reduces the energy consumption of the coal-fired wet desulfurization system by adjusting the limestone slurry supply in the coal-fired wet desulfurization system.

8. The slurry supply control method for a coal-fired power plant wet desulfurization system according to claim 6, characterized in that, When the fluctuation rate of the ratio is less than 3% / min and when the ratio is less than 75%, the coal-fired wet desulfurization system adopts a safety control mode to stabilize the pH value of the slurry and control the pH value of the slurry in the absorption tower of the coal-fired wet desulfurization system within the range of 5.4 to 5.

8.

9. The slurry supply control method for a coal-fired power plant wet desulfurization system according to claim 1, characterized in that, The slurry supply control method is applicable to the coal-fired wet desulfurization system with peak-shaving operation capacity of 30% or less of the rated load.

10. The slurry supply control method for a coal-fired power plant wet desulfurization system according to any one of claims 1 to 9, characterized in that, When the fluctuation rate of the ratio is greater than or equal to 3% / min, the slurry supply control of the coal-fired wet desulfurization system adopts the energy-saving control mode. The energy-saving control mode enables the sulfur dioxide emission concentration at the outlet of the coal-fired wet desulfurization system to reach 80%~90% of the emission limit, and reduces the energy consumption of the coal-fired wet desulfurization system by adjusting the limestone slurry supply in the coal-fired wet desulfurization system.

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