CN108325357B - SCR system of power plant boiler and reducing agent supply adjusting method thereof - Google Patents
SCR system of power plant boiler and reducing agent supply adjusting method thereof Download PDFInfo
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- CN108325357B CN108325357B CN201810174778.2A CN201810174778A CN108325357B CN 108325357 B CN108325357 B CN 108325357B CN 201810174778 A CN201810174778 A CN 201810174778A CN 108325357 B CN108325357 B CN 108325357B
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- 239000003638 chemical reducing agent Substances 0.000 title claims abstract description 114
- 238000000034 method Methods 0.000 title claims abstract description 32
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 270
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims abstract description 257
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 124
- 238000010790 dilution Methods 0.000 claims abstract description 46
- 239000012895 dilution Substances 0.000 claims abstract description 46
- 238000004364 calculation method Methods 0.000 claims abstract description 42
- 230000001105 regulatory effect Effects 0.000 claims description 71
- 238000002347 injection Methods 0.000 claims description 48
- 239000007924 injection Substances 0.000 claims description 48
- 230000001276 controlling effect Effects 0.000 claims description 18
- 238000001514 detection method Methods 0.000 claims description 4
- 238000010531 catalytic reduction reaction Methods 0.000 abstract description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 23
- 239000003546 flue gas Substances 0.000 description 23
- 238000005259 measurement Methods 0.000 description 16
- 238000010586 diagram Methods 0.000 description 10
- 238000004590 computer program Methods 0.000 description 7
- 230000008569 process Effects 0.000 description 7
- 239000000243 solution Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 230000009471 action Effects 0.000 description 4
- 239000003245 coal Substances 0.000 description 4
- 238000007865 diluting Methods 0.000 description 4
- 238000001704 evaporation Methods 0.000 description 4
- 230000008020 evaporation Effects 0.000 description 4
- 230000006870 function Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- BIGPRXCJEDHCLP-UHFFFAOYSA-N ammonium bisulfate Chemical compound [NH4+].OS([O-])(=O)=O BIGPRXCJEDHCLP-UHFFFAOYSA-N 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8621—Removing nitrogen compounds
- B01D53/8625—Nitrogen oxides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/20—Reductants
- B01D2251/206—Ammonium compounds
- B01D2251/2062—Ammonia
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/02—Other waste gases
- B01D2258/0283—Flue gases
Abstract
The application discloses an SCR (selective catalytic reduction) of a power plant boiler and a supply regulation method of a reducing agent of the SCR, which are applied to an SCR system of the power plant boiler, wherein the SCR system at least comprises a reactor, a reducing agent supply device and a reducing agent dilution mixing device, and the supply regulation method specifically comprises the steps of detecting a plurality of operating parameters of the reactor related to the content of nitrogen oxides; and calculating a plurality of operation parameters according to a preset calculation model, and outputting an opening control instruction to the reducing agent supply device according to the obtained calculation result, wherein the opening control instruction is used for controlling the reducing agent supply device to convey the ammonia gas serving as the reducing agent to the reducing agent dilution mixing device. According to the scheme, the ammonia is controlled according to the operation parameters of the power plant boiler, so that the accurate control of the reducing agent ammonia can be realized, and the stable denitration efficiency of the coal-fired power plant is ensured.
Description
Technical Field
The application relates to the technical field of environmental protection, in particular to an SCR system of a power plant boiler and a reducing agent supply adjusting method thereof.
Background
According to the requirements of national energy saving, emission reduction, upgrading and reformation action plan (2014-2020), in order to ensure that the nitrogen oxides (NOx) in the flue gas reach the standard, the emission control of the nitrogen oxides is required by the coal-fired power plant, namely the flue gas is required to be subjected to denitration treatment for emission. At present, in coal-fired power plants, a Selective Catalytic Reduction (SCR) system based on an SCR technology is commonly utilized for denitration treatment, and the SCR technology is considered as the most dominant flue gas denitration technology in quite a long time at present or even in the future.
In SCR systems, regulation and control of the injection amount of ammonia as a reducing agent is a key in order to ensure a high removal rate of nitrogen oxides while reducing the consumption amount of ammonia and reducing the ammonia slip rate. If the ammonia supply amount is low, the reaction between ammonia and nitrogen oxides in the system is insufficient, and the emission of the nitrogen oxides exceeds the standard; if the ammonia supply amount is higher, the ammonia consumption is increased, and ammonia escape is increased, so that ammonium bisulfate is increased, an air preheater of a power plant boiler is blocked, the flow resistance of flue gas is increased, and the safety of a boiler system is reduced; at the same time, too much ammonia enters the environment and causes secondary pollution. Therefore, the injection amount of ammonia must be precisely adjusted to ensure stable denitration efficiency, prolong the catalyst replacement period, and improve the safety and reliability of the boiler system.
Disclosure of Invention
In view of the above, the present application provides an SCR system of a power plant boiler and a reducing agent supply adjusting method thereof for precisely controlling an injection amount of ammonia as a reducing agent in the power plant boiler to ensure stable denitration efficiency of a coal-fired power plant.
In order to achieve the above object, the following solutions have been proposed:
a supply adjustment method of reducing agent of an SCR system of a power plant boiler, the SCR system being applied to the power plant boiler, the SCR system comprising at least a reactor, a reducing agent supply device and a reducing agent dilution mixing device, the supply adjustment method comprising the steps of:
detecting a plurality of operating parameters of the power plant boiler related to nitrogen oxides;
calculating the operation parameters according to a preset calculation model, and outputting an opening control instruction to the reducing agent supply device according to the obtained calculation result, wherein the opening control instruction is used for controlling the reducing agent supply device to convey ammonia serving as a reducing agent to the reducing agent dilution mixing device.
Optionally, the plurality of operating parameters include an inlet nitrogen oxide concentration of the reactor, an outlet nitrogen oxide concentration of the reactor, a total air volume of the power plant boiler, an actual ammonia flow rate of the reducing agent supply device, a dilution air flow rate of the reducing agent dilution mixing device, and an outlet nitrogen oxide concentration set point of the reactor.
Optionally, the reducing agent supply device includes a first adjusting valve, the opening control instruction includes a first opening instruction, the calculating the plurality of operation parameters according to a preset calculation model, and outputting the opening control instruction to the reducing agent supply device according to an obtained calculation result, including:
calculating the inlet nitrogen oxide concentration, the outlet nitrogen oxide concentration set value and the total air quantity according to a first preset formula to obtain an ammonia injection demand set value;
outputting a first opening instruction to the first regulating valve according to the ammonia injection demand set value, wherein the first opening instruction is used for controlling the first regulating valve to convey ammonia to the reducing agent dilution mixing device according to the ammonia injection demand set value.
Optionally, the reducing agent supply device further includes a second adjusting valve, the opening control instruction further includes a second opening instruction, the calculating the plurality of operating parameters according to a preset calculation model, and outputting the opening control instruction to the reducing agent supply device according to an obtained calculation result, and the method further includes:
calculating the inlet nitrogen oxide concentration and the outlet nitrogen oxide concentration set value according to a second preset formula, and correcting the ammonia injection demand set value according to a calculation result to obtain a final ammonia flow set value;
outputting a second opening instruction to the second regulating valve according to the final ammonia flow set value, wherein the second opening instruction is used for performing inching regulation on the second regulating valve, so that the total amount of ammonia output by the first regulating valve and the second regulating valve accords with the final ammonia flow set value.
An SCR system of a power plant boiler, the SCR system comprising at least a reactor, a reductant supply, a reductant dilution mixing device, and a supply adjustment device, the supply adjustment device comprising:
the parameter detection module is used for detecting a plurality of operation parameters related to the nitrogen oxides of the power plant boiler;
the calculation control module is used for calculating the operation parameters according to a preset calculation model, outputting an opening control instruction to the reducing agent supply device according to the obtained calculation result, and controlling the reducing agent supply device to convey the ammonia serving as the reducing agent to the reducing agent dilution mixing device.
Optionally, the plurality of operating parameters include an inlet nitrogen oxide concentration of the reactor, an outlet nitrogen oxide concentration of the reactor, a total air volume of the power plant boiler, an actual ammonia flow rate of the reducing agent supply device, a dilution air flow rate of the reducing agent dilution mixing device, and an outlet nitrogen oxide concentration set point of the reactor.
Optionally, the reducing agent supply device includes a first regulating valve, the opening control instruction includes a first opening instruction, and the calculation control module includes:
the parameter calculation unit is used for calculating the inlet nitrogen oxide concentration, the outlet nitrogen oxide concentration set value and the total air quantity according to a first preset formula to obtain an ammonia injection demand set value;
the instruction output unit is used for outputting the first opening instruction to the first regulating valve according to the ammonia injection demand set value, and the first opening instruction is used for controlling the first regulating valve to convey ammonia to the reducing agent dilution mixing device according to the ammonia injection demand set value.
Optionally, the reducing agent supply device further includes a second regulating valve, the opening control instruction further includes a second opening instruction, and the calculation control module further includes:
the first controller is used for calculating the concentration of the outlet nitrogen oxides and the set value of the concentration of the outlet nitrogen oxides according to a second preset formula, and correcting the set value of the ammonia injection demand according to a calculation result to obtain a final ammonia flow set value;
and the second controller is used for outputting the second opening instruction to the second regulating valve according to the final ammonia flow set value, and the second opening instruction is used for performing inching regulation on the second regulating valve so that the total amount of ammonia output by the first regulating valve and the second regulating valve accords with the final ammonia flow set value.
As can be seen from the above technical solution, the present application discloses a method for regulating the supply of a reducing agent to an SCR system of a power plant boiler, the method being applied to an SCR system of a power plant boiler, the SCR system comprising at least a reactor, a reducing agent supply device and a reducing agent dilution mixing device, the method for regulating the supply specifically detecting a plurality of operating parameters of the reactor related to the content of nitrogen oxides; and calculating a plurality of operation parameters according to a preset calculation model, and outputting an opening control instruction to the reducing agent supply device according to the obtained calculation result, wherein the opening control instruction is used for controlling the reducing agent supply device to convey the ammonia gas serving as the reducing agent to the reducing agent dilution mixing device. According to the scheme, the ammonia is controlled according to the operation parameters of the power plant boiler, so that the accurate control of the reducing agent ammonia can be realized, and the stable denitration efficiency of the coal-fired power plant is ensured.
Drawings
In order to more clearly illustrate the embodiments of the application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for regulating the supply of reductant to an SCR system of a power plant boiler in accordance with an embodiment of the present application;
FIG. 2 is a block diagram of an SCR system of a power plant boiler according to an embodiment of the present application;
FIG. 3 is a control block diagram of an SCR system of a power plant boiler according to an embodiment of the present application;
fig. 4 is a block diagram of a reducing agent supply adjusting device of an SCR system of a power plant boiler according to an embodiment of the present application.
Detailed Description
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
Example 1
FIG. 1 is a flow chart of a method for regulating the supply of reductant to an SCR system of a power plant boiler, according to an embodiment of the present application.
As shown in fig. 1, the supply adjustment method provided in this embodiment is applied to an SCR system of a power plant boiler, where the SCR system is used for performing denitration treatment on flue gas exhausted from the power plant boiler, that is, removing nitrogen oxides therein. The SCR system includes a plurality of sections including at least a reactor, a reductant supply, and a reductant dilution mixing device.
The reducing agent supply device comprises two regulating valves which are connected in parallel, namely a first regulating valve and a second regulating valve, wherein two ends of the regulating valve are respectively connected with ammonia supply equipment such as an ammonia tank or an ammonia pipeline, and the other end of the regulating valve is connected to the reducing agent dilution mixing device for conveying ammonia to the reducing agent dilution mixing device.
The reducing agent diluting and mixing device is used for diluting the ammonia gas conveyed by the reducing agent supply device, conveying the diluted ammonia gas to the reactor, and reacting the ammonia gas with nitrogen oxides conveyed by the power plant boiler in the reactor so as to remove the nitrogen oxides in the ammonia gas. The reducing agent dilution mixing apparatus includes a dilution blower 5, an ammonia/air mixer 7, and an ammonia injection device 11, as shown in fig. 2.
The reducing agent supply adjustment method in this embodiment specifically includes the steps of:
s101: a plurality of operating parameters of a power plant boiler related to nitrogen oxides are detected.
In particular, a plurality of operating parameters related to a power plant boiler and to the content of nitrogen oxides related to a reactor of the power plant boiler are detected. These operating parameters include in particular the inlet nitrogen oxide concentration of the reactor, the outlet nitrogen oxide concentration of the reactor, the total air quantity of the power plant boiler, the actual ammonia flow of the reducing agent supply device, the dilution air flow of the reducing agent dilution mixing device and the outlet nitrogen oxide concentration setpoint of the reactor. The final outlet nitrogen oxide concentration set value is preset by a user according to actual conditions in the system operation.
As shown in fig. 2, the nitrogen oxide concentration measuring instrument 10 provided at the inlet of the reactor of the SCR system is used to measure the inlet nitrogen oxide concentration of the reactor, the nitrogen oxide concentration measuring instrument 13 provided at the outlet of the reactor is used to measure the outlet nitrogen oxide concentration of the reactor, the total air volume measuring instrument 8 provided at the outside of the boiler 9 is used to measure the total air volume at the boiler side, and the ammonia gas flow measuring instrument 1 provided on the ammonia supply flow master 41 is used to measure the actual ammonia gas flow.
In fact, in the technical solution of the present application, the determination of the flue gas flow is critical. The flue gas flow is not suitable to adopt an actual measurement value, and the fluctuation of the measurement value is large, so that the measurement value has large error and low precision, and automatic command jump of ammonia injection control can be caused in the measurement process, so that the control requirement cannot be met if direct measurement is adopted; the flue gas flow sometimes adopts a calculated value corresponding to the evaporation capacity, but the flue gas flow cannot be reacted in real time due to the lag of the evaporation capacity measurement, so that the effect of real-time tracking control is affected; in addition, a calculated flue gas flow value corresponding to the coal amount is sometimes adopted, but the flue gas flow value cannot be accurately reflected in real time due to large coal quality change, so that the corresponding control requirement is difficult to meet. Therefore, in the application, the total air quantity of the boiler side is introduced to calculate the flue gas flow so as to achieve the purpose of real-time tracking control.
S102: and calculating a plurality of operation parameters to obtain and output opening control instructions.
Specifically, the operation parameters are calculated according to a preset calculation model, so that an opening control instruction is obtained, the opening control instruction is output to a reducing agent dilution mixing device of the SCR system, and the opening control instruction is used for controlling the delivery amount of ammonia gas delivered to the reducing agent dilution mixing device by a reducing agent supply device, so that the ammonia gas entering a reactor can be accurately matched with the amount of nitrogen oxides in the reactor.
From the above technical solution, it can be seen that the present application provides a method for regulating the supply of a reducing agent, applied to an SCR system of a power plant boiler, comprising at least a reactor, a reducing agent supply device and a reducing agent dilution mixing device, in particular for detecting a plurality of operating parameters of the reactor related to the content of nitrogen oxides; and calculating a plurality of operation parameters according to a preset calculation model, and outputting an opening control instruction to the reducing agent supply device according to the obtained calculation result, wherein the opening control instruction is used for controlling the reducing agent supply device to convey the ammonia gas serving as the reducing agent to the reducing agent dilution mixing device. According to the scheme, the ammonia is controlled according to the operation parameters of the power plant boiler, so that the accurate control of the reducing agent ammonia can be realized, and the stable denitration efficiency of the coal-fired power plant is ensured.
According to the reducing agent supply device, the maximum ammonia passing amount of the first regulating valve is 130% of the maximum ammonia passing amount required by the system, the maximum ammonia passing amount of the second regulating valve is 20% of the maximum ammonia passing amount of the first regulating valve, and the two regulating valves are connected in parallel, so that the total ammonia passing amount can be accurately controlled. Correspondingly, the opening control instruction comprises a first opening instruction and a second opening instruction.
In the process of calculating a plurality of operation parameters according to a preset calculation model and outputting an opening control instruction to a reduction supply device according to a calculation result, the present application specifically uses the following steps to operate, and a specific control block diagram is shown in fig. 3:
firstly, calculating the concentration of the nitrogen oxides at the inlet, the concentration set value of the nitrogen oxides at the outlet and the total air quantity according to a first preset formula to obtain the set value of the ammonia injection demand. The ammonia injection demand set value=total air volume× (inlet nox: concentration-outlet nox concentration set point) ×17×46×22.4×17.
And then, outputting a first opening instruction to the first regulating valve according to the ammonia injection demand set value, wherein the first opening instruction is used for controlling the first regulating valve to convey ammonia gas to the reducing agent dilution mixing device according to the ammonia injection demand set value.
In addition, calculating the outlet nitrogen oxide concentration and the outlet nitrogen oxide concentration set value according to a second preset formula, and correcting the ammonia injection demand set value according to a calculation result to obtain a final ammonia flow set value;
and finally, outputting a second opening instruction to the second regulating valve according to the final ammonia flow set value, wherein the second opening instruction is used for micro-adjusting the second regulating valve, so that the total amount of ammonia output by the first regulating valve and the second regulating valve accords with the final ammonia flow set value.
Through the actual control of the technical scheme, the following beneficial effects can be generated:
according to the reducing agent supply regulation control device, two regulating valves with different circulation capacities are arranged in parallel, according to the size of the ammonia injection requirement, a plurality of operation parameters are combined to carry out logic operation, then an opening control instruction is sent out, the regulating valve with large circulation capacity is adopted to achieve the effect of rough regulation of the ammonia injection requirement, the regulating valve with small circulation capacity is adopted to achieve the effect of fine regulation of the ammonia injection requirement, and therefore the purposes of wide-range and high-precision control of the ammonia injection quantity of an SCR system are achieved, and further the concentration of discharged nitrogen oxides is guaranteed not to exceed standard and ammonia injection is guaranteed not to be excessive.
In addition, the application introduces measurement parameters such as the concentration of nitrogen oxides at the inlet of a reactor of the SCR system, the concentration of nitrogen oxides at the outlet of the reactor, the total air quantity at the boiler side, the actual ammonia flow and the set value of the concentration of nitrogen oxides at the outlet of the reactor, wherein the introduction of the total air quantity at the boiler side of the measurement parameters can achieve the purpose of tracking and controlling the flue gas flow in real time, thereby realizing the purpose of controlling the ammonia injection quantity of the SCR system in real time and finally ensuring that the concentration of the discharged nitrogen oxides does not exceed the standard and the ammonia injection quantity is not excessive.
Example two
The embodiment provides an SCR system of a power plant boiler, which is used for performing denitration treatment on flue gas exhausted by the power plant boiler, namely removing nitrogen oxides in the flue gas. The SCR system includes a plurality of sections including at least a reactor, a reductant supply, a reductant dilution mixing device, and a supply adjustment device.
The reducing agent supply device comprises two regulating valves which are connected in parallel, namely a first regulating valve and a second regulating valve, wherein two ends of the regulating valve are respectively connected with ammonia supply equipment such as an ammonia tank or an ammonia pipeline, and the other end of the regulating valve is connected to the reducing agent dilution mixing device for conveying ammonia to the reducing agent dilution mixing device.
The reducing agent diluting and mixing device is used for diluting the ammonia gas conveyed by the reducing agent supply device, conveying the diluted ammonia gas to the reactor, and reacting the ammonia gas with nitrogen oxides conveyed by the power plant boiler in the reactor so as to remove the nitrogen oxides in the ammonia gas. The reducing agent dilution mixing apparatus includes a dilution blower 5, an ammonia/air mixer 7, and an ammonia injection device 11, as shown in fig. 2.
The supply adjustment device in this embodiment specifically includes a parameter detection module 100 and a calculation control module 200, as shown in fig. 4.
The parameter detection module is used for detecting a plurality of operation parameters of the power plant boiler related to the nitrogen oxides.
In particular, a plurality of operating parameters related to a power plant boiler and to the content of nitrogen oxides related to a reactor of the power plant boiler are detected. These operating parameters include in particular the inlet nitrogen oxide concentration of the reactor, the outlet nitrogen oxide concentration of the reactor, the total air quantity of the power plant boiler, the actual ammonia flow of the reducing agent supply device, the dilution air flow of the reducing agent dilution mixing device and the outlet nitrogen oxide concentration setpoint of the reactor. The final outlet nitrogen oxide concentration set value is preset by a user according to actual conditions in the system operation.
As shown in fig. 2, the nitrogen oxide concentration measuring instrument 10 provided at the inlet of the reactor of the SCR system is used to measure the inlet nitrogen oxide concentration of the reactor, the nitrogen oxide concentration measuring instrument 13 provided at the outlet of the reactor is used to measure the outlet nitrogen oxide concentration of the reactor, the total air volume measuring instrument 8 provided at the outside of the boiler 9 is used to measure the total air volume at the boiler side, and the ammonia gas flow measuring instrument 1 provided on the ammonia supply flow master 41 is used to measure the actual ammonia gas flow.
In fact, in the technical solution of the present application, the determination of the flue gas flow is critical. The flue gas flow is not suitable to adopt an actual measurement value, and the fluctuation of the measurement value is large, so that the measurement value has large error and low precision, and automatic command jump of ammonia injection control can be caused in the measurement process, so that the control requirement cannot be met if direct measurement is adopted; the flue gas flow sometimes adopts a calculated value corresponding to the evaporation capacity, but the flue gas flow cannot be reacted in real time due to the lag of the evaporation capacity measurement, so that the effect of real-time tracking control is affected; in addition, a calculated flue gas flow value corresponding to the coal amount is sometimes adopted, but the flue gas flow value cannot be accurately reflected in real time due to large coal quality change, so that the corresponding control requirement is difficult to meet. Therefore, in the application, the total air quantity of the boiler side is introduced to calculate the flue gas flow so as to achieve the purpose of real-time tracking control.
The calculation control module is used for calculating a plurality of operation parameters to obtain and output opening control instructions.
Specifically, the operation parameters are calculated according to a preset calculation model, so that an opening control instruction is obtained, the opening control instruction is output to a reducing agent dilution mixing device of the SCR system, and the opening control instruction is used for controlling the delivery amount of ammonia gas delivered to the reducing agent dilution mixing device by a reducing agent supply device, so that the ammonia gas entering a reactor can be accurately matched with the amount of nitrogen oxides in the reactor.
From the above technical solution, it can be seen that the present application provides a method for regulating the supply of a reducing agent, applied to an SCR system of a power plant boiler, comprising at least a reactor, a reducing agent supply device and a reducing agent dilution mixing device, in particular for detecting a plurality of operating parameters of the reactor related to the content of nitrogen oxides; and calculating a plurality of operation parameters according to a preset calculation model, and outputting an opening control instruction to the reducing agent supply device according to the obtained calculation result, wherein the opening control instruction is used for controlling the reducing agent supply device to convey the ammonia gas serving as the reducing agent to the reducing agent dilution mixing device. According to the scheme, the ammonia is controlled according to the operation parameters of the power plant boiler, so that the accurate control of the reducing agent ammonia can be realized, and the stable denitration efficiency of the coal-fired power plant is ensured.
According to the reducing agent supply device, the maximum ammonia passing amount of the first regulating valve is 130% of the maximum ammonia passing amount required by the system, the maximum ammonia passing amount of the second regulating valve is 20% of the maximum ammonia passing amount of the first regulating valve, and the two regulating valves are connected in parallel, so that the total ammonia passing amount can be accurately controlled. Correspondingly, the opening control instruction comprises a first opening instruction and a second opening instruction.
The calculation control module specifically comprises a parameter calculation unit, an instruction output unit, a first controller and a second controller.
The parameter calculation unit is used for calculating the inlet nitrogen oxide concentration, the outlet nitrogen oxide concentration set value and the total air quantity according to a first preset formula to obtain an ammonia injection demand set value. The ammonia injection demand set value=total air volume× (inlet nox: concentration-outlet nox concentration set point) ×17×46×22.4×17.
The mass output unit is used for outputting a first opening instruction to the first regulating valve according to the ammonia injection demand set value, and the first opening instruction is used for controlling the first regulating valve to convey ammonia gas to the reducing agent dilution mixing device according to the ammonia injection demand set value.
The first controller is configured to calculate the outlet nox concentration and the outlet nox concentration set value according to a second preset formula, and correct the ammonia injection demand set value according to the calculation result to obtain a final ammonia flow set value, as shown in fig. 3;
the second controller is used for outputting a second opening instruction to the second regulating valve according to the final ammonia flow set value, and the second opening instruction is used for performing inching regulation on the second regulating valve so that the total amount of ammonia output by the first regulating valve and the second regulating valve accords with the final ammonia flow set value, as shown in fig. 3.
Through the actual control of the technical scheme, the following beneficial effects can be generated:
according to the reducing agent supply regulation control device, two regulating valves with different circulation capacities are arranged in parallel, according to the size of the ammonia injection requirement, a plurality of operation parameters are combined to carry out logic operation, then an opening control instruction is sent out, the regulating valve with large circulation capacity is adopted to achieve the effect of rough regulation of the ammonia injection requirement, the regulating valve with small circulation capacity is adopted to achieve the effect of fine regulation of the ammonia injection requirement, and therefore the purposes of wide-range and high-precision control of the ammonia injection quantity of an SCR system are achieved, and further the concentration of discharged nitrogen oxides is guaranteed not to exceed standard and ammonia injection is guaranteed not to be excessive.
In addition, the application introduces measurement parameters such as the concentration of nitrogen oxides at the inlet of a reactor of the SCR system, the concentration of nitrogen oxides at the outlet of the reactor, the total air quantity at the boiler side, the actual ammonia flow and the set value of the concentration of nitrogen oxides at the outlet of the reactor, wherein the introduction of the total air quantity at the boiler side of the measurement parameters can achieve the purpose of tracking and controlling the flue gas flow in real time, thereby realizing the purpose of controlling the ammonia injection quantity of the SCR system in real time and finally ensuring that the concentration of the discharged nitrogen oxides does not exceed the standard and the ammonia injection quantity is not excessive.
In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described by differences from other embodiments, and identical and similar parts between the embodiments are all enough to be referred to each other.
It will be apparent to those skilled in the art that embodiments of the present application may be provided as a method, apparatus, or computer program product. Accordingly, embodiments of the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, embodiments of the application may take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.
Embodiments of the present application are described with reference to flowchart illustrations and/or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiment and all such alterations and modifications as fall within the scope of the embodiments of the application.
Finally, it is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article or terminal device comprising the element.
The foregoing has outlined rather broadly the more detailed description of the application in order that the detailed description of the application that follows may be better understood, and in order that the present principles and embodiments may be better understood; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present application, the present description should not be construed as limiting the present application in view of the above.
Claims (2)
1. A method of regulating the supply of reductant to an SCR system of a power plant boiler, the SCR system comprising at least a reactor, a reductant supply and a reductant dilution mixing device, the reductant supply comprising a first regulating valve and a second regulating valve, the method comprising the steps of:
detecting a plurality of operating parameters related to nitrogen oxides of the power plant boiler, wherein the operating parameters comprise inlet nitrogen oxide concentration of the reactor, outlet nitrogen oxide concentration of the reactor, total air quantity of the power plant boiler, actual ammonia flow of the reducing agent supply device, dilution air flow of the reducing agent dilution mixing device and outlet nitrogen oxide concentration set value of the reactor;
calculating the plurality of operation parameters according to a preset calculation model, and outputting opening control instructions to the reducing agent supply device according to the obtained calculation result, wherein the opening control instructions comprise a first opening instruction and a second opening instruction, and specifically comprise the following steps:
calculating the inlet nitrogen oxide concentration, the outlet nitrogen oxide concentration set value and the total air quantity according to a first preset formula to obtain an ammonia injection demand set value;
outputting a first opening instruction to the first regulating valve according to the ammonia injection demand set value, wherein the first opening instruction is used for controlling the first regulating valve to convey ammonia to the reducing agent dilution mixing device according to the ammonia injection demand set value;
calculating the inlet nitrogen oxide concentration and the outlet nitrogen oxide concentration set value according to a second preset formula, and correcting the ammonia injection demand set value according to a calculation result to obtain a final ammonia flow set value;
outputting a second opening instruction to the second regulating valve according to the final ammonia flow set value, wherein the second opening instruction is used for performing inching regulation on the second regulating valve, so that the total amount of ammonia output by the first regulating valve and the second regulating valve accords with the final ammonia flow set value.
2. An SCR system of a power plant boiler, the SCR system comprising at least a reactor, a reductant supply, a reductant dilution mixing device and a supply regulator, the reductant supply comprising a first regulator valve and a second regulator valve, characterized in that the supply regulator comprises:
the parameter detection module is used for detecting a plurality of operation parameters related to the nitrogen oxides of the power plant boiler, wherein the operation parameters comprise inlet nitrogen oxide concentration of the reactor, outlet nitrogen oxide concentration of the reactor, total air quantity of the power plant boiler, actual ammonia flow of the reducing agent supply device, dilution air flow of the reducing agent dilution mixing device and outlet nitrogen oxide concentration set value of the reactor;
the calculation control module is used for calculating the plurality of operation parameters according to a preset calculation model and outputting opening control instructions to the reducing agent supply device according to the obtained calculation result, wherein the opening control instructions comprise a first opening instruction and a second opening instruction, and the calculation control module comprises:
the parameter calculation unit is used for calculating the inlet nitrogen oxide concentration, the outlet nitrogen oxide concentration set value and the total air quantity according to a first preset formula to obtain an ammonia injection demand set value;
the instruction output unit is used for outputting the first opening instruction to the first regulating valve according to the ammonia injection demand set value, and the first opening instruction is used for controlling the first regulating valve to convey ammonia to the reducing agent dilution mixing device according to the ammonia injection demand set value;
the first controller is used for calculating the concentration of the nitrogen oxides at the inlet and the concentration set value of the nitrogen oxides at the outlet according to a second preset formula, and correcting the ammonia injection demand set value according to a calculation result to obtain a final ammonia flow set value;
the second controller is used for outputting a second opening instruction to the second regulating valve according to the final ammonia flow set value, and the second opening instruction is used for performing inching regulation on the second regulating valve so that the total amount of ammonia output by the first regulating valve and the second regulating valve accords with the final ammonia flow set value;
ammonia injection demand set value = total air volume× (inlet nox concentration-outlet nox concentration set value) ×17 ≡46×22.4 ≡17.
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| CN112807944B (en) * | 2021-02-02 | 2022-11-25 | 浙江物产环能浦江热电有限公司 | Adjusting method of ammonia water flow adjusting system for tail gas denitration |
| CN114682084A (en) * | 2022-03-28 | 2022-07-01 | 西安热工研究院有限公司 | Parallel denitration reducing agent flow adjusting system and method |
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