A SO2 emission control method based on coordinated regulation of a booster fan and a slurry circulating pump

Abstract

The application discloses a SO2 emission control method based on coordinated regulation of a booster fan and a slurry circulating pump, which adjusts the inlet flue gas pressure of a wet desulfurization system by using the booster fan, and the adjustment instruction of the inlet flue gas pressure of the wet desulfurization system is obtained based on a genetic algorithm, a particle swarm algorithm or an ant colony algorithm and a unit power, a slurry pH, a SO2 inlet concentration of the wet desulfurization system and a flue gas flow rate of the wet desulfurization system. The SO2 outlet concentration is adjusted by using the slurry circulating pump flow, and the deviation of the flue gas pressure and the instruction thereof is calculated by using a PID to serve as a feedforward of the slurry circulating pump adjustment, and the slurry pH, the SO2 inlet concentration of the wet desulfurization system and the flue gas flow rate of the wet desulfurization system serve as a feedforward of the slurry circulating pump flow instruction. The control method can realize the coordinated control of the booster fan and the slurry circulating pump in a variable load transient process of a coal-fired unit, and ensures the lowest energy consumption of the booster fan and the slurry circulating pump under the premise of meeting the SO2 emission of the unit.

Description

Technical Field

[0001] This invention relates to the field of coal-fired power generation technology, specifically to a method for controlling SO2 emissions based on the coordinated regulation of a booster fan and a slurry circulation pump. Background Technology

[0002] Coal-fired power units are the "ballast" for my country's energy security and stable supply. In the future, coal-fired power units will undertake more peak shaving and frequency regulation tasks to absorb more wind and solar energy. Therefore, coal-fired power units will frequently operate in large load ranges and at rapid load change rates, which will inevitably affect the efficient operation of wet desulfurization systems.

[0003] Wet desulfurization technology is the most widely used desulfurization technology in coal-fired power plants. When coal-fired units are operating under frequent load changes or low loads, the energy consumption of wet desulfurization systems is relatively high, which greatly increases the plant power consumption rate and significantly reduces the power generation efficiency of coal-fired units. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the purpose of this invention is to provide an SO2 emission control method based on the coordinated regulation of booster fan and slurry circulation pump, so as to reduce the energy consumption of coal-fired units during low load and frequent load change processes.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for SO2 emission control based on the coordinated regulation of booster fans and slurry circulation pumps is proposed. The deviation between the flue gas pressure and the flue gas pressure command in the wet desulfurization system is used to obtain the booster fan command through PID calculation. The flue gas pressure command of the wet desulfurization system is obtained by optimizing the calculation based on unit power, slurry pH, SO2 inlet concentration, and flue gas velocity using a genetic algorithm, particle swarm optimization, or ant colony optimization.

[0007] F2(x)=k1×f op (x1,x2,x3,x4)

[0008] In the formula, F2(x) is the flue gas pressure command of the wet desulfurization system, in Pa; f op Genetic algorithm, particle swarm optimization, or ant colony optimization; x1 is the unit power (MW); x2 is the slurry pH; x3 is the SO2 inlet concentration of the wet desulfurization system (mg / m³). -3 x4 represents the flue gas velocity in the wet desulfurization system, in milliseconds (ms). -1 k1 is a calculation coefficient and is a constant.

[0009] Once the flue gas pressure command F2(x) of the wet desulfurization system is determined, the SO2 emission concentration of the coal-fired unit can be controlled by adjusting the flow rate of the slurry circulation pump; the slurry circulation pump flow rate command S...pv The SO2 emission concentration and its deviation from the setpoint are obtained through PID calculation. The slurry pH, SO2 inlet concentration of the wet desulfurization system, and flue gas velocity of the wet desulfurization system are used as the slurry circulation pump flow command S. pv Feedforward 1:

[0010] F1(x) = k2x2 + k3x3 + k4x4

[0011] In the formula, F1(x) is the feedforward of the slurry circulation pump flow command in the wet desulfurization system, and k2, k3 and k4 are calculation coefficients, which are constants;

[0012] The deviation between the flue gas pressure and its command in the wet desulfurization system is calculated using PID control and used as the command S for the slurry circulation pump. pv Feedforward 2:

[0013] F3(x) = K6 × PID(k5(P) gas -F2(x)))

[0014] In the formula, F3(x) is the feedforward of the command for the slurry circulation pump flow rate of the wet desulfurization system, k5 and k6 are calculation coefficients, and P is a constant; gas The pressure of the flue gas in the wet desulfurization system is Pa; PID is the PID control algorithm.

[0015] The SO2 emission concentration can be controlled by adjusting the total flow rate of the slurry circulation pump in the wet desulfurization system. The command for the total flow rate of the slurry circulation pump is as follows:

[0016] S total =S pv +F1(x)+F3(x)

[0017] In the formula, S total This is an instruction for the total flow rate of the slurry circulation pump in the wet desulfurization system.

[0018] Preferably, when using a genetic algorithm, particle swarm optimization algorithm, or ant colony optimization algorithm to obtain the flue gas pressure command of the wet desulfurization system based on the unit power, slurry pH, SO2 inlet concentration of the wet desulfurization system, and flue gas velocity of the wet desulfurization system, the optimization objective is to minimize the energy consumption of the slurry circulation pump and the booster fan.

[0019] Preferably, the flue gas pressure command of the wet desulfurization system meets the following requirements:

[0020] M1≤F2(x)≤M2

[0021] In the formula, M1 is the minimum value of the flue gas pressure of the wet desulfurization system, which is taken as 101.325 kPa; M2 is the maximum value of the flue gas pressure of the wet desulfurization system, which is taken as 103~105 kPa.

[0022] Preferably, the instruction S for the total slurry circulation flow rate. total satisfy:

[0023] k7×M s ≤S total ≤M s

[0024] In the formula, M s The total set flow rate for the slurry circulation pump is mg m -3 k7 is the adjustment coefficient, which is 0.5 to 0.6.

[0025] Preferably, the SO2 emission concentration setpoint is 25–30 mg / m³. -3 .

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1) The control method of the present invention is based on the real-time changes in unit power, slurry pH, SO2 inlet concentration of wet desulfurization system and flue gas velocity of wet desulfurization system during the load change process of coal-fired unit. The optimization algorithm is used to obtain the pressure command of the booster fan of wet desulfurization system of coal-fired unit in real time during the load change process, thereby realizing the adaptive adjustment of the booster fan pressure of coal-fired unit during the transient process of load change.

[0028] 2) The control method of the present invention first realizes that the pressure of the booster fan of the coal-fired unit is operated according to the optimal flue gas pressure command during the load change process. On this basis, the SO2 emission concentration is controlled by adjusting the flow rate of the slurry circulation pump of the wet desulfurization system. The coordinated control of the booster fan and the slurry circulation pump during the load change transient process of the coal-fired unit can be realized, and the energy consumption of the booster fan and the slurry circulation pump is minimized while meeting the SO2 emission standards of the unit. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the control method of the present invention. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0031] like Figure 1 As shown, this invention proposes an SO2 emission control method based on the coordinated regulation of a booster fan and a slurry circulation pump. The deviation Δ2 between the flue gas pressure and the flue gas pressure command in the wet desulfurization system is calculated using PID control to obtain the booster fan command. The flue gas pressure command F2(x) for the wet desulfurization system is obtained by optimizing the calculation based on unit power, slurry pH, SO2 inlet concentration of the wet desulfurization system, and flue gas velocity of the wet desulfurization system using a genetic algorithm, particle swarm optimization algorithm, or ant colony optimization algorithm, and taking into account unit power, slurry pH, SO2 inlet concentration of the wet desulfurization system, and flue gas velocity of the wet desulfurization system.

[0032] F2(x)=k1×fop (x1,x2,x3,x4)

[0033] In the formula, F2(x) is the flue gas pressure command of the wet desulfurization system, in Pa; f op Genetic algorithm, particle swarm optimization, or ant colony optimization; x1 is the unit power (MW); x2 is the slurry pH; x3 is the SO2 inlet concentration of the wet desulfurization system (mg / m³). -3 x4 represents the flue gas velocity in the wet desulfurization system, in milliseconds (ms). -1 k1 is a calculation coefficient and is a constant.

[0034] Once the flue gas pressure command F2(x) of the wet desulfurization system is determined, the SO2 emission concentration of the coal-fired unit can be controlled by adjusting the flow rate of the slurry circulation pump; the slurry circulation pump flow rate command S... pv The SO2 emission concentration and its deviation Δ1 from the setpoint are obtained through PID calculation. The slurry pH, SO2 inlet concentration of the wet desulfurization system, and flue gas velocity of the wet desulfurization system are used as the slurry circulation pump flow command S. pv Feedforward 1:

[0035] F1(x) = k2x2 + k3x3 + k4x4

[0036] In the formula, F1(x) is the feedforward of the slurry circulation pump flow command in the wet desulfurization system, and k2, k3 and k4 are calculation coefficients, which are constants;

[0037] The deviation Δ2 between the flue gas pressure and the command of the wet desulfurization system is calculated using PID control and used as the command S for the slurry circulation pump. pv Feedforward 2:

[0038] F3(x) = K6 × PID(k5(P) gas -F2(x)))

[0039] In the formula, F3(x) is the feedforward of the command for the slurry circulation pump flow rate of the wet desulfurization system, k5 and k6 are calculation coefficients, and P is a constant; gas The pressure of the flue gas in the wet desulfurization system is Pa; PID is the PID control algorithm.

[0040] SO2 emission concentration can be controlled by adjusting the total flow rate of the slurry circulation pump in the wet desulfurization system. The setpoint for SO2 emission concentration is 25–30 mg / m³. -3 Command S for total flow rate of slurry circulation pump total for:

[0041] S total =S pv +F1(x)+F3(x)

[0042] In the formula, S totalThis is an instruction for the total flow rate of the slurry circulation pump in the wet desulfurization system.

[0043] Preferably, when using genetic algorithms, particle swarm optimization, or ant colony optimization to obtain the flue gas pressure command for the wet desulfurization system based on unit power, slurry pH, SO2 inlet concentration, and flue gas velocity, the optimization objective is to minimize the energy consumption of the slurry circulation pump and the booster fan. This is because the energy consumption of the wet desulfurization system in a coal-fired unit mainly comes from the slurry circulation pump and the booster fan. Optimizing to minimize the energy consumption of these components ensures that the wet desulfurization system operates at its lowest energy consumption during load changes, thereby reducing the plant power consumption rate of the coal-fired unit.

[0044] The flue gas pressure command of the wet desulfurization system meets the following requirements:

[0045] M1≤F2(x)≤M2

[0046] In the formula, M1 is the minimum value of the flue gas pressure of the wet desulfurization system, which is taken as 101.325 kPa, and this value is the atmospheric standard pressure; M2 is the maximum value of the flue gas pressure of the wet desulfurization system, which is taken as 103~105 kPa. This value can ensure that the adjustment range of the flue gas pressure of the wet desulfurization system is expanded as much as possible without affecting the safe operation of the coal-fired unit.

[0047] The instruction S for total slurry circulation flow rate total satisfy:

[0048] k7×M s ≤S total ≤M s

[0049] In the formula, M s The total set flow rate for the slurry circulation pump is mgm -3 k7 is the adjustment coefficient, ranging from 0.5 to 0.6. The total slurry circulation flow rate instruction S... total The value of k7 must be lower than the sum of the set flow rates of the total slurry circulation pumps; otherwise, the safe operation of the slurry circulation pumps cannot be guaranteed. Considering both the adjustment range of the slurry circulation pump frequency converter and the minimum safe operating flow rate of the slurry circulation pumps, a value of 0.5 to 0.6 is more suitable.

[0050] The setpoint for SO2 emission concentration is 25–30 mg / m³. -3 This ensures that the energy consumption of the wet desulfurization system is reduced as much as possible while meeting the SO2 emission concentration requirements.

Claims

1. A SO2 emission control method based on synergistic regulation of a booster fan and a slurry circulating pump, characterized in that: The deviation of the flue gas pressure of the wet desulfurization system and the flue gas pressure command is calculated by PID to obtain the command of the booster fan, and the flue gas pressure command of the wet desulfurization system is obtained by using a genetic algorithm, a particle swarm algorithm or an ant colony algorithm and based on the unit power, the slurry pH, the SO2 inlet concentration of the wet desulfurization system and the flue gas flow rate of the wet desulfurization system: F2(x) = k1 x f op (x1, x2, x3, x4) In the formula, F2(x) is the flue gas pressure instruction of the wet desulfurization system, Pa; f op is a genetic algorithm, a particle swarm algorithm or an ant colony algorithm; x1 is the unit power, MW; x2 is the slurry pH; x3 is the SO2 inlet concentration of the wet desulfurization system, mg / m -3 ; x4 is the flue gas flow rate of the wet desulfurization system, m / s -1 ; k1 is a calculation coefficient, which is a constant; When the flue gas pressure instruction F2(x) of the wet desulfurization system is determined, the SO2 emission concentration of the coal-fired unit is controlled by adjusting the flow of the slurry circulating pump; the instruction S pv of the slurry circulating pump flow is obtained by PID calculation from the deviation of the SO2 emission concentration and its set value, and the slurry pH, the SO2 inlet concentration of the wet desulfurization system and the flue gas flow rate of the wet desulfurization system are used as the feedforward of the slurry circulating pump flow instruction S pv : F1(x)=k2x2+k3x3+k4x4 In the formula, F1(x) is the feedforward one of the slurry circulating pump flow command of the wet desulfurization system, k2, k3 and k4 are calculation coefficients, and are constants; The deviation of the flue gas pressure of the wet desulfurization system and its instruction is calculated by PID as the slurry circulating pump instruction S pv Feedforward two: F3(x) = K6 x PID(k5(P gas - F2(x))) In the formula, F3(x) is a feedforward two of the command of the slurry circulating pump flow of the wet desulfurization system, k5 and k6 are calculation coefficients, which are constants; P gas P is the flue gas pressure of the wet desulfurization system, Pa; PID is a PID control algorithm; The SO2 emission concentration is controlled by adjusting the total flow of the slurry circulating pump of the wet desulfurization system, and the command of the total flow of the slurry circulating pump is: S total = S pv + F1(x) + F3(x) In the formula, S total is the total flow of the slurry circulating pump of the wet desulfurization system.

2. The SO2 emission control method based on the coordinated regulation of the booster fan and the slurry circulating pump according to claim 1, characterized in that, When the flue gas pressure command of the wet desulfurization system is obtained by using a genetic algorithm, a particle swarm algorithm or an ant colony algorithm and based on the unit power, the slurry pH, the SO2 inlet concentration of the wet desulfurization system and the flue gas flow rate of the wet desulfurization system, the minimum energy consumption of the slurry circulating pump and the booster fan is taken as the optimization target.

3. The SO2 emission control method based on the coordinated regulation of the booster fan and the slurry circulating pump according to claim 1, characterized in that, The flue gas pressure command of the wet desulfurization system satisfies: M1≤F2(x)≤M2 In the formula, M1 is the minimum value of the flue gas pressure of the wet desulfurization system, and is 101.325 kPa; and M2 is the maximum value of the flue gas pressure of the wet desulfurization system, and is 103-105 kPa.

4. The SO2 emission control method based on the coordinated regulation of the booster fan and the slurry circulating pump according to claim 1, characterized in that, Command S of total slurry circulation flow rate total Satisfies: k7 x M s ≤ S total ≤ M s In the formula, M s The sum of the flow rates set for the total pulp circulating pumps, mg m -3 k7 is a regulation coefficient, and is 0.5-0.

6.

5. The SO2 emission control method based on the coordinated regulation of the booster fan and the slurry circulating pump according to claim 1, characterized in that, SO2emission concentration set value is taken 25-30 mg m -3 .

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