Flue gas nitric oxide control method for combined cycle unit waste heat boiler

Abstract

The invention provides a flue gas nitrogen oxide control method for a combined cycle unit waste heat boiler. The flue gas nitrogen oxide control method comprises the steps that the target value of the nitrogen oxide content in outlet flue gas of the combined cycle unit waste heat boiler, the outlet flue gas flow, the actual value of the nitrogen oxide content in the outlet flue gas and the current urea solution supply amount are determined; determining a target value and an actual value of the nitrogen oxide emission amount and determining the amount of urea needing to be increased; then determining the supply amount of the urea solution needing to be increased and the supply amount of the urea solution needing to be reached; the urea solution supply amount needing to be increased serves as feedforward of the PID controller, the urea solution supply amount is adjusted to be increased from the current urea solution supply amount to the urea solution supply amount needing to be achieved, and therefore the actual value of the nitrogen oxide content is equal to the target value, blindness and hysteresis in the control process are effectively eliminated, and the control accuracy is improved. Therefore, the control accuracy and the control response speed are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas nitrogen oxide control, and in particular to a flue gas nitrogen oxide control method for a waste heat boiler of a combined cycle unit. Background Art

[0002] As the international and domestic requirements for power plant emission indicators become more and more stringent, power plants are required to further reduce the nitrogen oxide content in the outlet flue gas of the waste heat boiler of the combined cycle unit. At present, in order to reduce the nitrogen oxide content in the outlet flue gas of the waste heat boiler of the combined cycle unit, the control method adopted is to directly use the deviation between the actual value and the target value of the nitrogen oxide content as the feedforward of the PID controller, and then the PID controller adjusts the supply of urea solution.

[0003] However, due to the limitations of its own principles, this method has blindness and lag in the control process, resulting in poor control accuracy and slow control response speed. Summary of the invention

[0004] The present invention provides a flue gas nitrogen oxide control method for a waste heat boiler of a combined cycle unit, which is used to solve the defects of the flue gas nitrogen oxide control method in the prior art, such as poor control accuracy and slow control response speed.

[0005] In a first aspect, the present invention provides a method for controlling flue gas nitrogen oxides of a waste heat boiler of a combined cycle unit, comprising:

[0006] Determine a target value of the nitrogen oxide content in the outlet flue gas of the waste heat boiler of the combined cycle unit, and collect operating parameters of the waste heat boiler of the combined cycle unit, including: outlet flue gas flow rate, actual value of the nitrogen oxide content in the outlet flue gas, and current urea solution supply;

[0007] Determining a target value of nitrogen oxide emissions based on the outlet flue gas flow rate and the target value of nitrogen oxide content in the outlet flue gas;

[0008] Determining an actual value of nitrogen oxide emissions based on the outlet flue gas flow rate and the actual value of the nitrogen oxide content in the outlet flue gas;

[0009] Determining a required increase in urea amount based on the target value of nitrogen oxide emissions and the actual value of nitrogen oxide emissions;

[0010] Based on the required increased urea amount, determining the required increased urea solution supply amount;

[0011] Determining a urea solution supply amount to be achieved based on the current urea solution supply amount and the required increased urea solution supply amount;

[0012] The required increased urea solution supply amount is used as a feedforward of a PID controller, and the PID controller is used to adjust the opening of a urea solution supply regulating valve to adjust the urea solution supply amount from a current urea solution supply amount to a desired urea solution supply amount, thereby making an actual value of the nitrogen oxide content in the outlet flue gas equal to a target value of the nitrogen oxide content in the outlet flue gas.

[0013] According to a flue gas nitrogen oxide control method for a waste heat boiler of a combined cycle unit provided by the present invention, the step of determining the amount of urea required to be increased based on the target value of the nitrogen oxide emission and the actual value of the nitrogen oxide emission includes:

[0014] determining a difference between the target value of the nitrogen oxide emission and the actual value of the nitrogen oxide emission;

[0015] Based on the difference and a preset formula, determining the amount of urea that needs to be increased;

[0016] The preset formula is:

[0017] ΔM=(M2-M1) / 1000 / 180×120 / 1000

[0018] Wherein, ΔM represents the required increase in the amount of urea, M1 represents the target value of nitrogen oxide emissions, and M2 represents the actual value of nitrogen oxide emissions.

[0019] According to a flue gas nitrogen oxide control method for a waste heat boiler of a combined cycle unit provided by the present invention, the required increase in the supply amount of urea solution is determined based on the required increase in the amount of urea, comprising:

[0020] Determine the efficiency of the pyrolysis furnace in decomposing ammonia, the reaction efficiency of ammonia and nitrogen oxides, the mass concentration of the urea solution, and the density of the urea solution at the current temperature;

[0021] Inputting the required increased amount of urea, the efficiency of the pyrolysis furnace in decomposing ammonia, the reaction efficiency of ammonia and nitrogen oxides, the mass concentration of the urea solution and the density of the urea solution at the current temperature into the formula for determining the required increased amount of urea solution supply, to obtain the required increased amount of urea solution supply;

[0022] The formula for determining the required increase in urea solution supply is:

[0023] Δt=ΔM / N1 / N2 / q / p

[0024] Among them, ΔM represents the amount of urea required to be increased, N1 represents the efficiency of the pyrolysis furnace in decomposing ammonia, N2 represents the reaction efficiency of ammonia and nitrogen oxides, q represents the mass concentration of urea solution, and p represents the density of urea solution at the current temperature.

[0025] According to a flue gas nitrogen oxide control method for a waste heat boiler of a combined cycle unit provided by the present invention, the determining of the amount of urea solution supply to be achieved includes:

[0026] t=t0+Δt

[0027] Wherein, t represents the desired urea solution supply, t0 represents the current urea solution supply, and Δt represents the required increase in urea solution supply.

[0028] According to a flue gas nitrogen oxide control method for a waste heat boiler of a combined cycle unit provided by the present invention, the target value of determining the nitrogen oxide emission amount is:

[0029] M1=f×Q1

[0030] The actual value for determining the nitrogen oxide emissions is:

[0031] M2=f×Q2

[0032] Among them, M1 represents the target value of nitrogen oxide emissions, M2 represents the actual value of nitrogen oxide emissions, f represents the outlet flue gas flow rate, Q1 represents the target value of nitrogen oxide content in the outlet flue gas, and Q2 represents the actual value of nitrogen oxide content in the outlet flue gas.

[0033] According to a flue gas nitrogen oxide control method for a waste heat boiler of a combined cycle unit provided by the present invention, the step of determining a target value of nitrogen oxide content in the outlet flue gas of the waste heat boiler of the combined cycle unit comprises:

[0034] Determine the maximum allowable emission concentrations and fuel types, including natural gas, coal and biomass;

[0035] Based on the unit efficiency and economic cost, taking into account the maximum allowable emission concentration and fuel type, the target value of the nitrogen oxide content in the outlet flue gas is determined to be 50% of the maximum allowable emission concentration.

[0036] According to a flue gas nitrogen oxide control method for a waste heat boiler of a combined cycle unit provided by the present invention, the adjusting the opening of the urea solution supply regulating valve to adjust the urea solution supply amount from the current urea solution supply amount to the urea solution supply amount to be achieved comprises:

[0037] Determining the corresponding relationship between the opening of the regulating valve and the supply amount of urea solution;

[0038] Based on the target speed increase and the corresponding relationship, the opening of the regulating valve is adjusted according to a preset speed.

[0039] In a second aspect, the present invention provides a flue gas nitrogen oxide control device for a waste heat boiler of a combined cycle unit, comprising:

[0040] A collection module, used to determine the target value of the nitrogen oxide content in the outlet flue gas of the waste heat boiler of the combined cycle unit, and collect the operating parameters of the waste heat boiler of the combined cycle unit, including: the outlet flue gas flow rate, the actual value of the nitrogen oxide content in the outlet flue gas and the current urea solution supply;

[0041] a determination module, for determining a target value of nitrogen oxide emission based on the outlet flue gas flow rate and the target value of nitrogen oxide content in the outlet flue gas; determining an actual value of nitrogen oxide emission based on the outlet flue gas flow rate and the actual value of nitrogen oxide content in the outlet flue gas; determining a required increase in urea amount based on the target value of nitrogen oxide emission and the actual value of nitrogen oxide emission; determining a required increase in urea solution supply amount based on the required increase in urea amount; and determining a urea solution supply amount to be achieved based on the current urea solution supply amount and the required increase in urea solution supply amount;

[0042] The regulating module is used for taking the required increased urea solution supply amount as a feedforward of a PID controller, and using the PID controller to regulate the opening of a urea solution supply regulating valve, so as to regulate the urea solution supply amount from a current urea solution supply amount to a desired urea solution supply amount, thereby making the actual value of the nitrogen oxide content in the outlet flue gas equal to the target value of the nitrogen oxide content in the outlet flue gas.

[0043] In a third aspect, the present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, a method for controlling flue gas nitrogen oxides of a waste heat boiler of a combined cycle unit as described in any one of the above is implemented.

[0044] In a fourth aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the above-described methods for controlling flue gas nitrogen oxides for a waste heat boiler of a combined cycle unit.

[0045] In a fifth aspect, the present invention further provides a computer program product, comprising a computer program, which, when executed by a processor, implements any of the above-described methods for controlling flue gas nitrogen oxides in a waste heat boiler of a combined cycle unit.

[0046] The present invention provides a flue gas nitrogen oxide control method for a waste heat boiler of a combined cycle unit, comprising: determining a target value of the nitrogen oxide content in the outlet flue gas of the waste heat boiler of the combined cycle unit, and collecting operating parameters of the waste heat boiler of the combined cycle unit, including: an outlet flue gas flow rate, an actual value of the nitrogen oxide content in the outlet flue gas, and a current urea solution supply; determining a target value of nitrogen oxide emissions based on the outlet flue gas flow rate and the target value of the nitrogen oxide content in the outlet flue gas; determining an actual value of nitrogen oxide emissions based on the outlet flue gas flow rate and the actual value of the nitrogen oxide content in the outlet flue gas; and determining an actual value of nitrogen oxide emissions based on the target value of nitrogen oxide emissions and The actual value of nitrogen oxide emission is used to determine the amount of urea required to be increased; based on the amount of urea required to be increased, the amount of urea solution supply required to be increased is determined; based on the current amount of urea solution supply and the amount of urea solution supply required to be increased, the amount of urea solution supply to be achieved is determined; the amount of urea solution supply required to be increased is used as the feedforward of the PID controller, and the PID controller is used to adjust the opening of the urea solution supply regulating valve to adjust the urea solution supply from the current urea solution supply to the amount of urea solution supply to be achieved, so that the actual value of the nitrogen oxide content in the outlet flue gas is equal to the target value of the nitrogen oxide content in the outlet flue gas. By using the required amount of urea solution supply to be increased as the feedforward of the PID controller, the blindness and hysteresis in the control process are effectively eliminated, thereby effectively improving the control accuracy and control response speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 It is a flow chart of the method for controlling flue gas nitrogen oxides of a waste heat boiler of a combined cycle unit provided in this embodiment. ;

[0049] Figure 2 is a structural schematic diagram of a flue gas nitrogen oxide control device for a waste heat boiler of a combined cycle unit provided in this embodiment;

[0050] Figure 3 It is a schematic diagram of the structure of the electronic device provided in this embodiment. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] Figure 1 It is a flow chart of the method for controlling flue gas nitrogen oxides of a waste heat boiler of a combined cycle unit provided in this embodiment.

[0053] like Figure 1 As shown, the method for controlling flue gas nitrogen oxides for a waste heat boiler of a combined cycle unit provided in an embodiment of the present invention mainly comprises the following steps:

[0054] 101. Determine the target value of the nitrogen oxide content in the outlet flue gas of the waste heat boiler of the combined cycle unit, and collect the operating parameters of the waste heat boiler of the combined cycle unit, including: outlet flue gas flow rate, actual value of the nitrogen oxide content in the outlet flue gas and current urea solution supply.

[0055] In a specific implementation process, the target value of nitrogen oxide content in the outlet flue gas refers to the most reasonable emission amount, which is determined based on environmental emission standards. Specifically, the maximum allowable emission concentration and fuel type of the environment are first determined. The combustion types include natural gas, coal and biomass; based on the unit efficiency and economic cost, the maximum allowable emission concentration and fuel type are combined to determine the target value of nitrogen oxide content in the outlet flue gas as 50% of the maximum allowable emission concentration. Different fuel types have different corresponding combustion rates, and different unit efficiencies and economic costs are also different. Therefore, considering the fuel type, unit efficiency and economic cost, the target value of nitrogen oxide content in the outlet flue gas is set within the maximum allowable emission concentration range to ensure the most reasonable.

[0056] At the same time, the outlet flue gas flow rate of the waste heat boiler, the actual value of the nitrogen oxide content in the outlet flue gas and the current urea solution supply are collected. Usually, the flue gas flow rate and other parameters are collected by sensors.

[0057] 102. Determine the target value of nitrogen oxide emissions based on the target value of the outlet flue gas flow rate and the nitrogen oxide content in the outlet flue gas.

[0058] The target value of nitrogen oxide emissions is determined by formula (1):

[0059] M1=f×Q1 (1)

[0060] Among them, M1 represents the target value of nitrogen oxide emissions, f represents the outlet flue gas flow rate, and Q1 represents the target value of nitrogen oxide content in the outlet flue gas.

[0061] The unit of M1 is mg / h, and the unit of Q1 is mg / m 3 , the unit of f is m 3 / h.

[0062] 103. Based on the actual values ​​of the outlet flue gas flow rate and the nitrogen oxide content in the outlet flue gas, the actual value of the nitrogen oxide emission is determined.

[0063] The target value of nitrogen oxide emissions is determined by formula (2):

[0064] M2=f×Q2 (2)

[0065] Among them, M2 represents the actual value of nitrogen oxide emissions, f represents the outlet flue gas flow rate, and Q2 represents the actual value of the nitrogen oxide content in the outlet flue gas.

[0066] The unit of M2 is mg / h, and the unit of Q2 is mg / m 3 , the unit of f is m 3 / h.

[0067] 104. Determine the amount of urea that needs to be increased based on the target value of nitrogen oxide emissions and the actual value of nitrogen oxide emissions.

[0068] Determine the difference between the target value of nitrogen oxide emissions and the actual value of nitrogen oxide emissions; determine the amount of urea to be added based on the difference and a preset formula;

[0069] The default formula is (3):

[0070] ΔM=(M2-M1) / 1000 / 180×120 / 1000 (3)

[0071] Wherein, ΔM represents the required additional amount of urea, M1 represents the target value of nitrogen oxide emissions, M2 represents the actual value of nitrogen oxide emissions, and the unit of ΔM is mg / h.

[0072] 105. Based on the required increased amount of urea, determine the required increased amount of urea solution supply.

[0073] First, the efficiency of the pyrolysis furnace in decomposing ammonia, the reaction efficiency of ammonia and nitrogen oxides, the mass concentration of the urea solution and the density of the urea solution at the current temperature are determined; then, the required amount of urea to be increased, the efficiency of the pyrolysis furnace in decomposing ammonia, the reaction efficiency of ammonia and nitrogen oxides, the mass concentration of the urea solution and the density of the urea solution at the current temperature are input into the formula for determining the required amount of urea solution to be increased, and the required amount of urea solution to be increased is obtained;

[0074] The formula for determining the required increase in urea solution supply is (4):

[0075] Δt=ΔM / N1 / N2 / q / p (4)

[0076] Among them, ΔM represents the amount of urea required to be added, N1 represents the efficiency of the pyrolysis furnace in decomposing ammonia, N2 represents the reaction efficiency of ammonia and nitrogen oxides, q represents the mass concentration of urea solution, p represents the density of urea solution at the current temperature, and the unit of Δt is m 3 / h.

[0077] 106. Based on the current urea solution supply and the required increased urea solution supply, determine the urea solution supply that should be achieved.

[0078] The required urea solution supply is determined by formula (5):

[0079] t=t0+Δt (5)

[0080] Where, t represents the desired urea solution supply, t0 represents the current urea solution supply, Δt represents the required increase in urea solution supply, and the unit of t is m 3 / h.

[0081] 107. The required increase in the urea solution supply is used as the feedforward of the PID controller, and the PID controller is used to adjust the opening of the urea solution supply regulating valve to adjust the urea solution supply from the current urea solution supply to the desired urea solution supply, so that the actual value of the nitrogen oxide content in the outlet flue gas is equal to the target value of the nitrogen oxide content in the outlet flue gas.

[0082] Specifically, the corresponding relationship between the opening of the regulating valve and the supply of urea solution can be determined; based on the target growth rate and the corresponding relationship, the opening of the regulating valve is adjusted at a preset speed, that is, the supply of urea solution is adjusted by the opening of the regulating valve, and due to the corresponding relationship between the two, the supply of urea solution can be stably and accurately controlled by the opening size.

[0083] In this embodiment, since the deviation between the actual value and the target value of the nitrogen oxide content is no longer directly used as the feedforward of the PID controller, the required increase in the supply of urea solution is first calculated, and then the required increase in the supply of urea solution is used as the feedforward of the PID controller, the blindness and hysteresis in the control process are effectively eliminated, thereby effectively improving the control accuracy and control response speed.

[0084] Based on the same general inventive concept, the present invention also protects a flue gas nitrogen oxide control device for a waste heat boiler of a combined cycle unit. The flue gas nitrogen oxide control device for a waste heat boiler of a combined cycle unit provided by the present invention is described below. The flue gas nitrogen oxide control device for a waste heat boiler of a combined cycle unit described below and the flue gas nitrogen oxide control method for a waste heat boiler of a combined cycle unit described above can be referenced to each other.

[0085] Figure 2 It is a structural schematic diagram of the flue gas nitrogen oxide control device for the waste heat boiler of a combined cycle unit provided in this embodiment.

[0086] like Figure 2 As shown, this embodiment provides a flue gas nitrogen oxide control device for a waste heat boiler of a combined cycle unit, comprising:

[0087] The acquisition module 201 is used to determine the target value of the nitrogen oxide content in the outlet flue gas of the waste heat boiler of the combined cycle unit, and to acquire the operating parameters of the waste heat boiler of the combined cycle unit, including: the outlet flue gas flow rate, the actual value of the nitrogen oxide content in the outlet flue gas, and the current urea solution supply;

[0088] The determination module 202 is used to determine the target value of nitrogen oxide emission based on the target value of the outlet flue gas flow rate and the nitrogen oxide content in the outlet flue gas; determine the actual value of nitrogen oxide emission based on the actual value of the outlet flue gas flow rate and the nitrogen oxide content in the outlet flue gas; determine the required increase in urea amount based on the target value of nitrogen oxide emission and the actual value of nitrogen oxide emission; determine the required increase in urea solution supply amount based on the required increase in urea amount; determine the urea solution supply amount to be achieved based on the current urea solution supply amount and the required increase in urea solution supply amount;

[0089] The regulating module 203 is used to use the required increased urea solution supply as a feedforward of the PID controller, and use the PID controller to adjust the opening of the urea solution supply regulating valve to adjust the urea solution supply from the current urea solution supply to the urea solution supply that should be achieved, so that the actual value of the nitrogen oxide content in the outlet flue gas is equal to the target value of the nitrogen oxide content in the outlet flue gas.

[0090] Furthermore, the determination module 202 in this embodiment is specifically configured to:

[0091] determining a difference between the target value of the nitrogen oxide emission and the actual value of the nitrogen oxide emission;

[0092] Based on the difference and a preset formula, determining the amount of urea that needs to be increased;

[0093] The preset formula is:

[0094] ΔM=(M2-M1) / 1000 / 180×120 / 1000

[0095] Wherein, ΔM represents the required increase in the amount of urea, M1 represents the target value of nitrogen oxide emissions, and M2 represents the actual value of nitrogen oxide emissions.

[0096] Furthermore, the determination module 202 in this embodiment is specifically configured to:

[0097] Determine the efficiency of the pyrolysis furnace in decomposing ammonia, the reaction efficiency of ammonia and nitrogen oxides, the mass concentration of the urea solution, and the density of the urea solution at the current temperature;

[0098] Inputting the required increased amount of urea, the efficiency of the pyrolysis furnace in decomposing ammonia, the reaction efficiency of ammonia and nitrogen oxides, the mass concentration of the urea solution and the density of the urea solution at the current temperature into the formula for determining the required increased amount of urea solution supply, to obtain the required increased amount of urea solution supply;

[0099] The formula for determining the required increase in urea solution supply is:

[0100] Δt=ΔM / N1 / N2 / q / p

[0101] Among them, ΔM represents the amount of urea required to be increased, N1 represents the efficiency of the pyrolysis furnace in decomposing ammonia, N2 represents the reaction efficiency of ammonia and nitrogen oxides, q represents the mass concentration of urea solution, and p represents the density of urea solution at the current temperature.

[0102] Furthermore, the determination module 202 in this embodiment is specifically configured to:

[0103] t=t0+Δt

[0104] Wherein, t represents the desired urea solution supply, t0 represents the current urea solution supply, and Δt represents the required increase in urea solution supply.

[0105] Furthermore, the determination module 202 in this embodiment is specifically configured to:

[0106] M1=f×Q1

[0107] The actual value for determining the nitrogen oxide emissions is:

[0108] M2=f×Q2

[0109] Among them, M1 represents the target value of nitrogen oxide emissions, M2 represents the actual value of nitrogen oxide emissions, f represents the outlet flue gas flow rate, Q1 represents the target value of nitrogen oxide content in the outlet flue gas, and Q2 represents the actual value of nitrogen oxide content in the outlet flue gas.

[0110] Furthermore, the acquisition module 201 in this embodiment is specifically used for:

[0111] Determine the maximum allowable emission concentrations and fuel types, including natural gas, coal and biomass;

[0112] Based on the unit efficiency and economic cost, taking into account the maximum allowable emission concentration and fuel type, the target value of the nitrogen oxide content in the outlet flue gas is determined to be 50% of the maximum allowable emission concentration.

[0113] Furthermore, the adjustment module 203 in this embodiment is specifically used for:

[0114] Determining the corresponding relationship between the opening of the regulating valve and the supply amount of urea solution;

[0115] Based on the target speed increase and the corresponding relationship, the opening of the regulating valve is adjusted according to a preset speed.

[0116] Figure 3 It is a schematic diagram of the structure of the electronic device provided in this embodiment.

[0117] like Figure 3As shown, the electronic device may include: a processor 310, a communication interface 320, a memory 330 and a communication bus 340, wherein the processor 310, the communication interface 320 and the memory 330 communicate with each other through the communication bus 340. The processor 310 may call the logic instructions in the memory 330 to execute the flue gas nitrogen oxide control method for the waste heat boiler of the combined cycle unit, the method comprising: determining the target value of the nitrogen oxide content in the outlet flue gas of the waste heat boiler of the combined cycle unit, and collecting the operating parameters of the waste heat boiler of the combined cycle unit, including: the outlet flue gas flow rate, the actual value of the nitrogen oxide content in the outlet flue gas and the current urea solution supply; based on the outlet flue gas flow rate and the target value of the nitrogen oxide content in the outlet flue gas, determining the target value of the nitrogen oxide emission; based on the outlet flue gas flow rate and the actual value of the nitrogen oxide content in the outlet flue gas, determining the actual value of the nitrogen oxide emission; based on the nitrogen oxide emission The invention relates to a method for determining a required increase in urea amount based on a target value of urea release and an actual value of the nitrogen oxide emission; determining a required increase in urea solution supply amount based on the required increase in urea amount; determining a urea solution supply amount that should be achieved based on the current urea solution supply amount and the required increase in urea solution supply amount; using the required increase in urea solution supply amount as a feedforward of a PID controller, and using the PID controller to adjust the opening of a urea solution supply regulating valve to adjust the urea solution supply amount from the current urea solution supply amount to the urea solution supply amount that should be achieved, so that the actual value of the nitrogen oxide content in the outlet flue gas is equal to the target value of the nitrogen oxide content in the outlet flue gas.

[0118] In addition, the logic instructions in the above-mentioned memory 330 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0119] On the other hand, the present invention also provides a computer program product, which includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the flue gas nitrogen oxide control method for a waste heat boiler of a combined cycle unit provided by the above methods. The method includes: determining a target value of the nitrogen oxide content in the outlet flue gas of the waste heat boiler of the combined cycle unit, and collecting operating parameters of the waste heat boiler of the combined cycle unit, including: outlet flue gas flow rate, actual value of the nitrogen oxide content in the outlet flue gas and current urea solution supply; based on the outlet flue gas flow rate and the target value of the nitrogen oxide content in the outlet flue gas, determining a target value of nitrogen oxide emissions; based on the outlet flue gas flow rate and the nitrogen oxide content in the outlet flue gas The invention relates to a method for controlling the nitrogen oxide content in the outlet flue gas to determine the actual value of the nitrogen oxide content; determining the required amount of urea to be increased based on the target value of the nitrogen oxide emission and the actual value of the nitrogen oxide emission; determining the required amount of urea to be increased based on the required amount of urea to be increased; determining the urea solution supply amount to be achieved based on the current urea solution supply amount and the required amount of urea solution to be increased; using the required amount of urea solution to be increased as a feedforward of a PID controller, and using the PID controller to adjust the opening of a urea solution supply regulating valve to adjust the urea solution supply amount from the current urea solution supply amount to the urea solution supply amount to be achieved, so that the actual value of the nitrogen oxide content in the outlet flue gas is equal to the target value of the nitrogen oxide content in the outlet flue gas.

[0120] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to execute the flue gas nitrogen oxide control method for a waste heat boiler of a combined cycle unit provided by the above-mentioned methods, the method comprising: determining a target value of the nitrogen oxide content in the outlet flue gas of the waste heat boiler of the combined cycle unit, and collecting operating parameters of the waste heat boiler of the combined cycle unit, including: an outlet flue gas flow rate, an actual value of the nitrogen oxide content in the outlet flue gas, and a current urea solution supply; determining a target value of nitrogen oxide emissions based on the outlet flue gas flow rate and the target value of the nitrogen oxide content in the outlet flue gas; determining a target value of nitrogen oxide emissions based on the outlet flue gas flow rate and the actual value of the nitrogen oxide content in the outlet flue gas The invention relates to a method for controlling the nitrogen oxide content in the flue gas outlet to determine the actual value of the nitrogen oxide emission; determining the required amount of urea to be increased based on the target value of the nitrogen oxide emission and the actual value of the nitrogen oxide emission; determining the required amount of urea solution to be increased based on the required amount of urea to be increased; determining the urea solution supply amount to be achieved based on the current urea solution supply amount and the required amount of urea solution to be increased; using the required amount of urea solution to be increased as a feedforward of a PID controller, and using the PID controller to adjust the opening of a urea solution supply regulating valve to adjust the urea solution supply amount from the current urea solution supply amount to the urea solution supply amount to be achieved, so that the actual value of the nitrogen oxide content in the outlet flue gas is equal to the target value of the nitrogen oxide content in the outlet flue gas.

[0121] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0122] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling nitrogen oxides in flue gas of a waste heat boiler of a combined cycle unit, characterized in that: include: Determine a target value of the nitrogen oxide content in the outlet flue gas of the waste heat boiler of the combined cycle unit, and collect operating parameters of the waste heat boiler of the combined cycle unit, including: outlet flue gas flow rate, actual value of the nitrogen oxide content in the outlet flue gas, and current urea solution supply; Determining a target value of nitrogen oxide emissions based on the outlet flue gas flow rate and the target value of nitrogen oxide content in the outlet flue gas; Determining an actual value of nitrogen oxide emissions based on the outlet flue gas flow rate and the actual value of the nitrogen oxide content in the outlet flue gas; Determining a required increase in urea amount based on the target value of nitrogen oxide emissions and the actual value of nitrogen oxide emissions; Based on the required increased urea amount, determining the required increased urea solution supply amount; Determining a urea solution supply amount to be achieved based on the current urea solution supply amount and the required increased urea solution supply amount; The required increased urea solution supply amount is used as a feedforward of a PID controller, and the PID controller is used to adjust the opening of a urea solution supply regulating valve to adjust the urea solution supply amount from a current urea solution supply amount to a desired urea solution supply amount, thereby making an actual value of the nitrogen oxide content in the outlet flue gas equal to a target value of the nitrogen oxide content in the outlet flue gas.

2. The method for controlling flue gas nitrogen oxides of a waste heat boiler of a combined cycle unit according to claim 1, characterized in that: The step of determining the amount of urea to be increased based on the target value of the nitrogen oxide emission and the actual value of the nitrogen oxide emission includes: determining a difference between the target value of the nitrogen oxide emission and the actual value of the nitrogen oxide emission; Based on the difference and a preset formula, determining the amount of urea that needs to be increased; The preset formula is: ΔM=(M2-M1) / 1000 / 180×120 / 1000 Wherein, ΔM represents the required increase in the amount of urea, M1 represents the target value of nitrogen oxide emissions, and M2 represents the actual value of nitrogen oxide emissions.

3. The method for controlling flue gas nitrogen oxides for a waste heat boiler of a combined cycle unit according to claim 1, characterized in that: The step of determining the required increased urea solution supply amount based on the required increased urea amount includes: Determine the efficiency of the pyrolysis furnace in decomposing ammonia, the reaction efficiency of ammonia and nitrogen oxides, the mass concentration of the urea solution, and the density of the urea solution at the current temperature; Inputting the required increased amount of urea, the efficiency of the pyrolysis furnace in decomposing ammonia, the reaction efficiency of ammonia and nitrogen oxides, the mass concentration of the urea solution and the density of the urea solution at the current temperature into the formula for determining the required increased amount of urea solution supply, to obtain the required increased amount of urea solution supply; The formula for determining the required increase in urea solution supply is: Δt=ΔM / N1 / N2 / q / p Among them, ΔM represents the amount of urea required to be increased, N1 represents the efficiency of the pyrolysis furnace in decomposing ammonia, N2 represents the reaction efficiency of ammonia and nitrogen oxides, q represents the mass concentration of urea solution, and p represents the density of urea solution at the current temperature.

4. The method for controlling flue gas nitrogen oxides for a waste heat boiler of a combined cycle unit according to claim 3, characterized in that: The step of determining the amount of urea solution supplied to be achieved comprises: t=t0+Δt Wherein, t represents the desired urea solution supply, t0 represents the current urea solution supply, and Δt represents the required increase in urea solution supply.

5. The method for controlling flue gas nitrogen oxides for a waste heat boiler of a combined cycle unit according to claim 1, characterized in that: The target value for determining nitrogen oxide emissions is: M1=f×Q1 The actual value for determining the nitrogen oxide emissions is: M2=f×Q2 Among them, M1 represents the target value of nitrogen oxide emissions, M2 represents the actual value of nitrogen oxide emissions, f represents the outlet flue gas flow rate, Q1 represents the target value of nitrogen oxide content in the outlet flue gas, and Q2 represents the actual value of nitrogen oxide content in the outlet flue gas.

6. The method for controlling flue gas nitrogen oxides for a waste heat boiler of a combined cycle unit according to claim 1, characterized in that: The step of determining a target value of nitrogen oxide content in the outlet flue gas of the waste heat boiler of the combined cycle unit comprises: Determine the maximum allowable emission concentrations and fuel types, including natural gas, coal and biomass; Based on the unit efficiency and economic cost, taking into account the maximum allowable emission concentration and fuel type, the target value of the nitrogen oxide content in the outlet flue gas is determined to be 50% of the maximum allowable emission concentration.

7. The method for controlling flue gas nitrogen oxides for a waste heat boiler of a combined cycle unit according to claim 1, characterized in that: The adjusting the opening of the urea solution supply regulating valve to adjust the urea solution supply amount from the current urea solution supply amount to the desired urea solution supply amount includes: Determining the corresponding relationship between the opening of the regulating valve and the supply amount of urea solution; Based on the target speed increase and the corresponding relationship, the opening of the regulating valve is adjusted according to a preset speed.

8. A flue gas nitrogen oxide control device for a waste heat boiler of a combined cycle unit, characterized in that: include: A collection module, used to determine the target value of the nitrogen oxide content in the outlet flue gas of the waste heat boiler of the combined cycle unit, and collect the operating parameters of the waste heat boiler of the combined cycle unit, including: the outlet flue gas flow rate, the actual value of the nitrogen oxide content in the outlet flue gas and the current urea solution supply; a determination module, for determining a target value of nitrogen oxide emission based on the outlet flue gas flow rate and the target value of nitrogen oxide content in the outlet flue gas; determining an actual value of nitrogen oxide emission based on the outlet flue gas flow rate and the actual value of nitrogen oxide content in the outlet flue gas; determining a required increase in urea amount based on the target value of nitrogen oxide emission and the actual value of nitrogen oxide emission; determining a required increase in urea solution supply amount based on the required increase in urea amount; and determining a urea solution supply amount to be achieved based on the current urea solution supply amount and the required increase in urea solution supply amount; The regulating module is used for taking the required increased urea solution supply amount as a feedforward of a PID controller, and using the PID controller to regulate the opening of a urea solution supply regulating valve, so as to regulate the urea solution supply amount from a current urea solution supply amount to a desired urea solution supply amount, thereby making the actual value of the nitrogen oxide content in the outlet flue gas equal to the target value of the nitrogen oxide content in the outlet flue gas.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method for controlling flue gas nitrogen oxides for a waste heat boiler of a combined cycle unit as described in any one of claims 1 to 7 is implemented.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for controlling flue gas nitrogen oxides for a waste heat boiler of a combined cycle unit as claimed in any one of claims 1 to 7 is implemented.

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