CN110624412A - SCR denitration system and ammonia injection control method thereof - Google Patents

SCR denitration system and ammonia injection control method thereof Download PDF

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Publication number
CN110624412A
CN110624412A CN201910871574.9A CN201910871574A CN110624412A CN 110624412 A CN110624412 A CN 110624412A CN 201910871574 A CN201910871574 A CN 201910871574A CN 110624412 A CN110624412 A CN 110624412A
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China
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ammonia
catalyst layer
ammonia injection
unit
section
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Inventor
胡小夫
汪洋
王云
郝正
高春昱
王争荣
夏怀鹏
王凯亮
沈建永
李伟
王桦
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China Huadian Engineering Group Co Ltd
Huadian Environmental Protection Engineering and Technology Co Ltd
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China Huadian Engineering Group Co Ltd
Huadian Environmental Protection Engineering and Technology Co Ltd
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Priority to CN201910871574.9A priority Critical patent/CN110624412A/en
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    • 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
    • B01D53/46—Removing components of defined structure
    • B01D53/54—Nitrogen compounds
    • B01D53/56—Nitrogen oxides
    • 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
    • B01D53/88—Handling or mounting catalysts
    • B01D53/885—Devices in general for catalytic purification of waste gases
    • 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
    • B01D53/90—Injecting reactants
    • 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

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Exhaust Gas Treatment By Means Of Catalyst (AREA)

Abstract

The invention provides an SCR denitration system and an ammonia injection control method thereof. The ammonia spraying control method adopted by the ammonia spraying control system can realize the real-time control of the ammonia spraying processes of the first ammonia spraying unit and the second ammonia spraying unit, and the first ammonia spraying unit and the second ammonia spraying unit spray ammonia towards the flue gas according to the instruction of the ammonia spraying control system. Unreacted NO is present when the flue gas flows out of the first catalyst layerxAnd a small amount of NH3The second ammonia spraying unit sprays ammonia towards the flue gas according to the instruction of the ammonia spraying control system, so that the mixing of a nitrogen-ammonia mixture is facilitated, the ammonia-containing flue gas can fully react when flowing through the second catalyst layer, and the removal of the SCR denitration system is improvedNitre efficiency, reducing ammonia escape and preventing blockage of the air preheater.

Description

SCR denitration system and ammonia injection control method thereof
Technical Field
The invention relates to the field of flue gas denitration, in particular to an SCR denitration system and an ammonia injection control method thereof.
Background
The nitrogen oxide can form acid rain and photochemical smog, can destroy the ozone layer and is a main pollutant of the atmosphere, so that the nitrogen oxide is fully treated, and the perfection of the denitration technology has very important significance for protecting the ecological environment. Selective Catalytic Reduction (SCR) technology is the mainstream technology for nitrogen oxide emission control of thermal power plants, and NH is injected into flue gas3The reducing agent reacts with NOx in the catalyst layer to generate N2So as to realize the removal of nitrogen oxides.
In the SCR denitration system, generally, guide plates having different shapes are arranged at a horizontal connection flue at an inlet of a reactor, and a series of rectification grids having the same height are uniformly arranged at positions of support beams on a first catalyst layer, so that flue gas is distributed in order to obtain a better flow field before flowing through the first catalyst layer. However, this design also cannot be guaranteed during actual operationThe flue gas is proved to have completely uniform velocity field and concentration field, so that unreacted NO still existsxAnd NH3. Unreacted NOxAnd NH3The ammonia nitrogen molar ratio is more unevenly distributed, the ammonia nitrogen can not fully react when flowing through the second catalyst layer or the third catalyst layer, and finally the unreacted NOx and NH3The flue gas is discharged into the atmosphere, which not only causes the denitration efficiency of the system to be lower, but also causes NOxThe phenomenon of overemission and ammonia escape.
Aiming at harsh environmental protection requirement (NO)xThe emission standard is reduced to 30mg/Nm3Or lower), the actual denitration efficiency of the SCR denitration system of some projects needs to be improved to more than 90%. Part of power plants adopt a mode of excessive ammonia injection to improve the denitration efficiency of the SCR system, and the mode can cause a large amount of ammonia escape and escaped NH3Can react with SO in the flue gas3And H2And the O reaction generates Ammonium Bisulfate (ABS), the ABS is easy to adhere to the surface of the air preheater along with the reduction of smoke temperature, the air preheater is blocked, the system resistance is increased, even the blower is stalled, and negative effects are brought to the safe operation of the unit.
Disclosure of Invention
Therefore, the invention aims to solve the technical problems that the actual denitration efficiency of an SCR denitration system is low and NO is not generatedxThe defects of excessive emission, high ammonia escape rate and blockage of a subsequent air preheater are overcome, and the SCR denitration system and the ammonia injection control method thereof are provided.
The technical scheme provided by the invention is as follows:
the invention provides an SCR denitration system, which comprises a main body, wherein the main body comprises a circulation section and a reaction section which are sequentially communicated, the SCR denitration system also comprises a reaction section,
the first ammonia injection unit is arranged in the circulation section close to the flue gas inlet of the circulation section;
the ammonia injection device comprises a first catalyst layer and a second ammonia injection unit, wherein the second ammonia injection unit is arranged in the reaction section, and the first catalyst layer is arranged between the first ammonia injection unit and the second ammonia injection unit and is positioned in the reaction section;
the second catalyst layer is arranged in the reaction section and is far away from the first catalyst layer relative to the second ammonia spraying unit;
and the ammonia injection control system is used for controlling the ammonia injection amount of the first ammonia injection unit and the second ammonia injection unit.
Further, the ammonia injection control system comprises a gas concentration detection system arranged in the reaction section and used for monitoring NO in the SCR denitration systemxAnd NH3The actual concentration of (c);
and the plug-in PLC is plug-in to the gas concentration detection system, is connected with the gas concentration detection system, and is used for calculating the theoretical total ammonia injection amount of the SCR denitration system, the actual ammonia injection amount of each catalyst layer and the actual denitration efficiency, and realizing the control of the theoretical total ammonia injection amount of the SCR denitration system, the actual ammonia injection amount of each catalyst layer and the actual denitration efficiency.
Further, the gas concentration detection system includes a first monitoring device including a first monitoring unit and a second monitoring unit, the first monitoring unit is disposed at the inlet cross section of the first catalyst layer for acquiring NO at the inlet cross section of the first catalyst layerxAnd NH3The concentration of (c); the second monitoring unit is arranged at the outlet section of the first catalyst layer and used for acquiring NO at the outlet section of the first catalyst layerxAnd NH3The concentration of (c);
the second monitoring device comprises a third monitoring unit and a fourth monitoring unit, wherein the third monitoring unit is arranged at the inlet section of the second catalyst layer and is used for acquiring NO at the inlet section of the second catalyst layerxAnd NH3The concentration of (c); the fourth monitoring unit is arranged at the outlet section of the second catalyst layer and used for acquiring NO at the outlet section of the second catalyst layerxAnd NH3The concentration of (c).
Further, the SCR denitration system also comprises a rectification grid which is arranged in the reaction section and is far away from the second ammonia spraying unit relative to the first catalyst layer.
Further, the second ammonia spraying unit is provided with a second nozzle, and the included angle beta between the spraying direction of the second nozzle and the axial direction of the reaction section is 0-90 degrees.
Further, the SCR denitration system further includes a third catalyst layer disposed in the reaction section and far away from the first catalyst layer relative to the second catalyst layer;
the third ammonia spraying unit is arranged in the reaction section and is arranged between the second catalyst layer and the third catalyst layer; preferably, the third ammonia spraying unit is provided with a third nozzle, and the included angle gamma between the spraying direction of the third nozzle and the axial direction of the reaction section is 0-90 degrees;
the third monitoring device comprises a fifth monitoring unit and a sixth monitoring unit, wherein the fifth monitoring unit is arranged at the inlet section of the third catalyst layer and is used for acquiring NO at the inlet section of the third catalyst layerxAnd NH3The concentration of (c); the sixth monitoring unit is arranged at the outlet section of the third catalyst layer and used for acquiring NO at the outlet section of the third catalyst layerxAnd NH3The concentration of (c).
Further, the ammonia injection control system is used for controlling the ammonia injection amount of the first ammonia injection unit, the second ammonia injection unit and the third ammonia injection unit.
The SCR denitration system further comprises a reducing agent supply device which is communicated with the first ammonia injection unit, the second ammonia injection unit and/or the third ammonia injection unit respectively so as to provide a reducing agent for the first ammonia injection unit, the second ammonia injection unit and the third ammonia injection unit respectively;
flow regulating valves are arranged among the reducing agent supply device and the first ammonia spraying unit, the second ammonia spraying unit and/or the third ammonia spraying unit and are connected with the plug-in PLC;
the equal unit that mixes, set up in the circulation section, including first equal unit and the second of mixing, first ammonia unit that spouts set up in first even unit and the second of mixing are even between the unit.
Further, the distance between the first ammonia spraying unit and the first uniform mixing unit is 50-500 mm;
the distance between the first ammonia spraying unit and the second uniform mixing unit is 50-500 mm.
Further, the first ammonia injection units are ammonia injection grids, preferably, the first ammonia injection units are any one of partition ammonia injection grids and mixed ammonia injection grids, and the number of the first ammonia injection units is 1-3;
the second ammonia spraying units are ammonia spraying grids, preferably, the second ammonia spraying units are linear ammonia spraying grids, and the number of the second ammonia spraying units is 1 set;
the third ammonia injection unit is an ammonia injection grid, preferably, the third ammonia injection unit is a linear ammonia injection grid, and the number of the third ammonia injection units is 1 set.
The invention also provides an ammonia injection control method of the SCR denitration system, which comprises the following steps:
1) according to NO at inlet cross section of the first catalyst layerxCalculating the theoretical total ammonia injection amount according to the concentration, the flue gas flow and the target denitration efficiency;
2) obtaining the maximum NO which can be processed by the first catalyst layer according to the flow rate of flue gas, the activity of the first catalyst layer and the volume of the first catalyst layerxConcentration;
3) maximum NO treatable by the first catalyst layerxCalculating the concentration, the flue gas flow and the ammonia nitrogen molar ratio of the chemical reaction to obtain the theoretical ammonia injection amount of the first ammonia injection unit; according to the flow of flue gas and NO at the inlet section of the first catalyst layerxAnd NO at the outlet cross section of said first catalyst layerxCalculating the actual concentration of said first catalyst layer NOxActual throughput of (d); according to the first catalyst layer NOxActual throughput of the first catalyst layer, NH at the outlet cross section of the first catalyst layer3Calculating the actual ammonia injection amount of the first ammonia injection unit according to the actual concentration and the ammonia nitrogen molar ratio of the chemical reaction so as to correct the theoretical ammonia injection amount of the first ammonia injection unit. Wherein the actual ammonia injection amount of the first ammonia injection unit and the first injectionThe ratio of the theoretical ammonia spraying amount of the ammonia unit is a correction coefficient of the first ammonia spraying unit, and the correction coefficient is 0.85-1.25;
4) calculating the actual ammonia injection amount of the second ammonia injection unit according to the theoretical total ammonia injection amount and the actual ammonia injection amount of the first ammonia injection unit;
5) NH at the outlet section of the second catalyst layer3Is determined by the actual concentration of NO at the inlet cross section of said first catalyst layer, i.e. the first actual ammonia slip ratexConcentration and NO at the outlet cross section of the second catalyst layerxThe first actual denitration efficiency of the system is calculated.
Further, the ammonia injection rate of the second ammonia injection unit is 0.2-1.2 times of the flow speed of the flue gas in the reaction section;
the ammonia injection amount of the first ammonia injection unit is not less than that of the second ammonia injection unit.
Further, when the system is provided with the third catalyst layer and the third ammonia injection unit, the ammonia injection control method of the SCR denitration system further includes, on the basis of step 3),
6) obtaining the maximum NO which can be processed by the second catalyst layer according to the smoke flow, the activity of the second catalyst layer and the volume of the second catalyst layerxConcentration;
7) maximum NO treatable by the second catalyst layerxCalculating the concentration, the flue gas flow and the ammonia nitrogen molar ratio of the chemical reaction to obtain the theoretical ammonia injection amount of the second ammonia injection unit; according to the flow of flue gas and NO at the inlet section of the second catalyst layerxAnd NO at the outlet cross section of said second catalyst layerxCalculating the actual concentration of the second catalyst layer NOxActual throughput of (d); according to the second catalyst layer NOxActual throughput of the second catalyst layer, NH at the outlet cross section of the second catalyst layer3Calculating the actual ammonia injection amount of the second ammonia injection unit according to the actual concentration and the ammonia nitrogen molar ratio of the chemical reaction so as to correct the theoretical ammonia injection amount of the second ammonia injection unit. Wherein the actual ammonia injection amount of the second ammonia injection unit and the second ammonia injection unitThe ratio of the theoretical ammonia spraying amount of the unit is the correction coefficient of the second ammonia spraying unit, and the correction coefficient is 0.85-1.25.
8) Calculating the actual total ammonia injection amount of the third ammonia injection unit according to the theoretical total ammonia injection amount, the actual ammonia injection amount of the first ammonia injection unit and the actual ammonia injection amount of the second ammonia injection unit;
9) NH at the outlet cross section of the third catalyst layer3The actual concentration of (i.e. the second actual ammonia slip) from the NO at the inlet cross section of the first catalyst layerxConcentration and NO at the outlet cross section of the third catalyst layerxThe second actual denitration efficiency of the system is calculated.
Further, the ammonia injection rate of the third ammonia injection unit is 0.2-1.2 times of the flow speed of the flue gas in the reaction section;
the ammonia injection amount of the first ammonia injection unit is not less than the ammonia injection amount of the second ammonia injection unit and the ammonia injection amount of the third ammonia injection unit.
Defining: the surface of the catalyst, where the flue gas enters, is the inlet section of the catalyst, and the surface of the catalyst, where the flue gas flows out, is the outlet section of the catalyst.
The technical scheme of the invention has the following advantages:
1. the SCR denitration system provided by the invention is characterized in that a first ammonia spraying unit is arranged in the circulation section, a first catalyst layer and a second catalyst layer are arranged in the reaction section, and a second ammonia spraying unit is arranged between the first catalyst layer and the second catalyst layer. In addition, an ammonia injection control system is also arranged. The first ammonia spraying unit sprays ammonia into the flue gas to obtain ammonia-containing flue gas, and the ammonia-containing flue gas flows through the first catalyst layer to react. Unreacted NO is present when ammonia-containing flue gas flows out of the first catalyst layerxAnd NH3And unreacted NOxAnd NH3The second ammonia spraying unit sprays ammonia towards the flue gas, the flue gas flow field is disturbed to realize the further mixing of the nitrogen and ammonia mixture, the ammonia-containing flue gas can fully react when flowing through the second catalyst layer, and a large amount of NO is avoidedxAnd NH3The denitration efficiency of the whole SCR denitration system is improved. The above-mentionedThe ammonia injection control system can realize the real-time control of the ammonia injection process of the first ammonia injection unit and the ammonia injection process of the second ammonia injection unit, the ammonia injection process of the first ammonia injection unit and the ammonia injection process of the second ammonia injection unit are performed towards flue gas according to the instruction of the ammonia injection control system, and the ammonia injection control system is favorable for mixing of a nitrogen-ammonia mixture, so that the emission of a large amount of ammonia is avoided, the system has lower ammonia escape rate while obtaining higher denitration efficiency, and the air preheater is prevented from being blocked.
2. The invention provides an SCR denitration system, wherein an ammonia spraying control system comprises a gas concentration detection system arranged in a reaction section and an externally-hung PLC hung on the gas concentration detection system and connected with the gas concentration detection system. The gas concentration detection system comprises a first monitoring device and a second monitoring device, wherein the first monitoring device comprises a first monitoring unit arranged at the inlet section of the first catalyst layer and a second monitoring unit arranged at the outlet section of the first catalyst layer, and the second monitoring device comprises a third monitoring unit arranged at the inlet section of the second catalyst layer and a fourth monitoring unit arranged at the outlet section of the second catalyst layer. Further, when the system is provided with a third ammonia spraying unit and a third catalyst layer, the gas concentration detection system further comprises a third monitoring device, and the third monitoring device comprises a fifth monitoring unit arranged at the inlet section of the third catalyst layer and a sixth monitoring unit arranged at the outlet section of the third catalyst layer. The gas concentration detection system is arranged to realize the adjustment of NO at the inlet section and the outlet section of each catalyst layer in the SCR denitration systemxAnd NH3The external PLC can realize the calculation and control of the theoretical total ammonia injection amount of the SCR denitration system, the actual ammonia injection amount of each catalyst layer and the actual denitration efficiency, and the gas concentration detection system and the external PLC are matched to realize the real-time control of the theoretical total ammonia injection amount of the SCR denitration system, the actual ammonia injection amount of each catalyst layer and the actual denitration efficiency, so that the system has lower ammonia escape rate while obtaining higher denitration efficiency.
3. The invention provides an SCR denitration system, which is characterized in thatThe ammonia injection device is provided with a first catalyst layer, a second catalyst layer, a first ammonia injection unit, a second ammonia injection unit, a third catalyst layer and a third ammonia injection unit. After the flue gas passes through the first ammonia spraying unit, the first catalyst layer, the second ammonia spraying unit and the second catalyst layer in sequence, a small amount of unreacted NO existsxAnd NH3Unreacted NOxAnd NH3With non-uniform flow and concentration fields. Third ammonia injection unit for unreacted NOxAnd NH3Spraying ammonia to disturb gas atmosphere and make NOxAnd NH3More uniform mixing, and then full reaction in the third catalyst layer, reducing NOxAnd NH3The denitration efficiency of the system is improved and the escape rate of ammonia is reduced.
4. The ammonia injection control method of the SCR denitration system comprises the steps of firstly calculating the theoretical total ammonia injection amount, obtaining the actual ammonia injection amount of the first ammonia injection unit by correcting the theoretical ammonia injection amount of the first ammonia injection unit, finally obtaining the actual ammonia injection amount of the second ammonia injection unit, and performing ammonia injection according to the actual ammonia injection amount of each catalyst layer. This spout ammonia control system adopts total amount control regulation mode, can realize spouting the real-time regulation and accurate control of ammonia volume to the total ammonia volume of spouting of system and each ammonia unit and spout ammonia volume, makes the system not spout ammonia excessively to reach the effect that reduces ammonia escape rate and improve holistic denitration efficiency.
5. According to the SCR denitration system provided by the invention, the partition ammonia injection grid or the mixed ammonia injection grid is used as the first ammonia injection unit, the aperture of the nozzle is large, and the blocking probability is reduced. And meanwhile, the partition ammonia injection grating or the mixed ammonia injection grating has higher mixing efficiency, so that the denitration efficiency of ammonia-containing flue gas when passing through the first catalyst can be improved, and the pressure of the second ammonia injection unit is further reduced, thereby improving the overall denitration efficiency and ammonia overflow rate and reducing the blocking condition of the air preheater. The second ammonia spraying unit and the third ammonia spraying unit are linear ammonia spraying grids which meet the use requirements of the second ammonia spraying unit and the third ammonia spraying unit and can ensure that unreacted NOxAnd NH3Is uniformly mixed and has construction cost and transportationThe maintenance cost is relatively low, so the construction cost of the system is reduced.
6. According to the ammonia injection control method of the SCR denitration system, the ammonia injection rate of the second ammonia injection unit and/or the third ammonia injection unit is 0.2-1.2 times of the flow speed of the flue gas in the reaction section, ammonia can be effectively mixed with the flue gas by injecting ammonia at the injection rate, and the nitrogen-ammonia mixture flowing through the second catalyst layer has a uniform flow field and a uniform concentration field, so that the denitration efficiency of the second catalyst layer and the denitration efficiency of the third catalyst layer are improved, and the denitration efficiency of the denitration system is finally improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic structural diagram of an SCR denitration system according to an embodiment of the present invention;
FIG. 2 is a schematic structural view of a second nozzle in example 1 of the present invention;
FIG. 3 is a schematic structural view of a third nozzle in embodiment 2 of the present invention;
FIG. 4 is a schematic flow chart illustrating an ammonia injection control method for an SCR ammonia injection system according to embodiment 1 of the present invention;
FIG. 5 is a schematic flow chart illustrating an ammonia injection control method for an SCR ammonia injection system according to embodiment 2 of the present invention;
reference numerals:
1-a flue gas inlet; 2-a flow-through section; 3-a reaction section; 4-a homogenizing unit; 4-1-a first homogenizing unit; 4-2-a second homogenizing unit; 5-a first ammonia injection unit; 6-a second ammonia injection unit; 7-a third ammonia injection unit; 8-a rectifying grid; 9-a first catalyst layer; 10-a second catalyst layer; 11-a third catalyst layer; 12-an ammonia injection control system; 13-flue gas outlet.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Example 1
The embodiment provides an SCR denitration system, as shown in fig. 1, the main body includes a flow section 2 and a reaction section 3 which are sequentially communicated, a flue gas inlet 1 is arranged at one end of the flow section 2 far away from the reaction section 3, a flue gas outlet 13 is arranged at one end of the reaction section 3 far away from the flow section 2, the SCR denitration system further includes,
the first ammonia spraying units 5 are arranged in the circulation section 2 close to the flue gas inlet 1 of the circulation section 2, further, the first ammonia spraying units 5 are ammonia spraying grids, preferably, the first ammonia spraying units 5 are one of partition ammonia spraying grids and mixed ammonia spraying grids, the number of the first ammonia spraying units 5 is 1-3, and the first ammonia spraying units can be selected according to the situation;
the ammonia spraying device comprises a first catalyst layer 9 and second ammonia spraying units 6, wherein the second ammonia spraying units 6 are arranged in a reaction section 3, the first catalyst layer 9 is arranged between the first ammonia spraying unit 5 and the second ammonia spraying unit 6 and is positioned in the reaction section 3, the second ammonia spraying units 6 are ammonia spraying grids, preferably, the second ammonia spraying units 6 are linear ammonia spraying grids, and the number of the second ammonia spraying units 6 is 1;
the second catalyst layer 10 is arranged in the reaction section 3 and is far away from the first catalyst layer 9 relative to the second ammonia spraying unit 6;
and the ammonia injection control system 12 is used for controlling the ammonia injection amount of the first ammonia injection unit 5 and the second ammonia injection unit 6.
In the SCR denitration system, the first ammonia injection unit 5 injects ammonia into the flue gas to obtain ammonia-containing flue gas, and the ammonia-containing flue gas flows through the first catalyst layer 9 to react. Unreacted NO is present when ammonia-containing flue gas flows out of the first catalyst layer 9xAnd NH3And unreacted NOxAnd NH3The second ammonia spraying unit 6 sprays ammonia towards the flue gas, so that the flue gas flow field is disturbed to realize further mixing of the nitrogen and ammonia mixture, the ammonia-containing flue gas can fully react when flowing through the second catalyst layer 10, and a large amount of NO is avoidedxAnd NH3The denitration efficiency of the second catalyst layer 10 is improved, and finally, the denitration efficiency of the whole SCR denitration system is improved. Spout ammonia control system 12 can realize spouting the real time control of ammonia process to first ammonia unit 5, the second is spouted ammonia unit 6, and first ammonia unit 5, the second is spouted ammonia unit 6 and is spouted ammonia towards the flue gas according to spouting ammonia control system 12 instruction, is favorable to the mixture of nitrogen ammonia mixture to avoid the emission of a large amount of ammonia, then made the system have lower ammonia escape rate when obtaining higher denitration efficiency, the jam takes place for the prevention air preheater.
The partition ammonia injection grid or the mixed ammonia injection grid is used as the first ammonia injection unit 5, the aperture of a nozzle is large, and the blocking probability is reduced. And meanwhile, the partition ammonia injection grating or the mixed ammonia injection grating has higher mixing efficiency, so that the denitration efficiency of ammonia-containing flue gas when passing through the first catalyst can be improved, and the pressure of the second ammonia injection unit 6 is further reduced, thereby improving the overall denitration efficiency and ammonia overflow rate and reducing the blocking condition of the air preheater. The second ammonia spraying unit 6 is a linear ammonia spraying grid which meets the use requirement of the second ammonia spraying unit 6 and can ensure that the unreacted NOxAnd NH3The uniform mixing of the components has the advantages of relatively low construction cost and operation and maintenance cost, so that the construction cost of the system is reduced.
As a specific embodiment, the ammonia injection control system 12 comprises a gas concentration detection system disposed in the reaction section 3 for monitoring NO in the SCR denitration systemxAnd NH3The actual concentration of (c);
and the plug-in PLC is plug-in to the gas concentration detection system, is connected with the gas concentration detection system, and is used for calculating the theoretical total ammonia injection amount of the SCR denitration system, the actual ammonia injection amount of each catalyst layer and the actual denitration efficiency, and realizing the control of the theoretical total ammonia injection amount of the SCR denitration system, the actual ammonia injection amount of each catalyst layer and the actual denitration efficiency.
Further, the gas concentration detection system includes a first monitoring device including a first monitoring unit and a second monitoring unit, the first monitoring unit being disposed at the inlet cross section of the first catalyst layer 9 for acquiring NO at the inlet cross section of the first catalyst layer 9xAnd NH3The concentration of (c); the second monitoring unit is arranged at the outlet cross section of the first catalyst layer 9 and is used for acquiring NO at the outlet cross section of the first catalyst layer 9xAnd NH3The concentration of (c);
a second monitoring device including a third monitoring unit and a fourth monitoring unit, wherein the third monitoring unit is arranged at the inlet section of the second catalyst layer 10 for obtaining NO at the inlet section of the second catalyst layer 10xAnd NH3The concentration of (c); the fourth monitoring unit is arranged on the outlet section of the second catalyst layer 10To obtain NO at the outlet cross section of the second catalyst layer 10xAnd NH3The concentration of (c).
By arranging the gas concentration detection system, NO at the inlet section and the outlet section of each catalyst layer in the SCR denitration system is detectedxAnd NH3The real-time monitoring of the actual concentration, the calculation and the control of the theoretical total ammonia injection amount of the SCR denitration system, the actual ammonia injection amount of each catalyst layer and the actual denitration efficiency can be realized by the aid of the plug-in PLC, and the real-time control of the theoretical total ammonia injection amount of the SCR denitration system, the actual ammonia injection amount of each catalyst layer and the actual denitration efficiency can be realized by the aid of the cooperation of the gas concentration detection system and the plug-in PLC, so that the system has low ammonia escape rate while high denitration efficiency is obtained.
Further, SCR deNOx systems still includes rectification grid 8, sets up in the reaction section, and is kept away from the setting of second ammonia injection unit for first catalyst layer.
As an alternative embodiment, the SCR denitration system further includes a third catalyst layer 11 disposed in the reaction section 3 and away from the first catalyst layer 9 with respect to the second catalyst layer 10. After the flue gas passes through the first ammonia spraying unit 5, the first catalyst layer 9, the second ammonia spraying unit 6 and the second catalyst layer 10 in sequence, a small amount of unreacted NO existsxAnd NH3Unreacted NOxAnd NH3Reaction occurs in the third catalyst layer 11, reducing NOxAnd NH3The denitration efficiency of the system is improved and the escape rate of ammonia is reduced.
Further, the second ammonia spraying unit 6 is provided with a second nozzle, as shown in fig. 2, the spraying direction of the second nozzle forms an included angle beta of 0-90 degrees with the axial direction of the reaction section 3;
in an embodiment, the SCR denitration system further includes a reducing agent supply device, which is respectively communicated with the first ammonia injection unit 5 and the second ammonia injection unit 6, so as to respectively supply the reducing agent to the first ammonia injection unit 5 and the second ammonia injection unit 6;
flow regulating valves are arranged between the reducing agent supply device and the first ammonia spraying unit 5 and between the reducing agent supply device and the second ammonia spraying unit 6, and are connected with the plug-in PLC;
the uniform mixing unit 4 is arranged in the circulation section 2 and comprises a first uniform mixing unit 4-1 and a second uniform mixing unit 4-2, and the first ammonia spraying unit 5 is arranged between the first uniform mixing unit 4-1 and the second uniform mixing unit 4-2.
Further, the distance between the first ammonia spraying unit 5 and the first uniform mixing unit 4-1 is 50mm-500 mm;
the distance between the first ammonia spraying unit 5 and the second uniform mixing unit 4-2 is 50mm-500 mm.
The embodiment also provides an ammonia injection control method for the SCR denitration system, as shown in fig. 4, including the following steps:
1) according to NO at inlet cross section of first catalyst layerxConcentration (A)0) Flue gas flow (V) and target denitration efficiency (eta)0) Calculating the theoretical total ammonia injection amount (B);
B＝A0*V*η0
2) according to the flue gas flow (V) and the activity (K) of the first catalyst layer1) And the first catalyst layer volume (Vm)1) Obtaining the maximum NO that the first catalyst layer can processxConcentration (Am)1)；
Am1＝(K1*Vm1)/V
3) Maximum NO treatable by the first catalyst layerxConcentration (A)m1) Calculating the theoretical ammonia spraying amount (B) of the first ammonia spraying unit by the flow rate (V) of the flue gas and the ammonia nitrogen molar ratio (1:1) of the chemical reactionPrinciple 1)；
BPrinciple 1＝Am1*V
According to the flow rate (V) of flue gas and NO at the inlet section of the first catalyst layerxActual concentration of (A)0) And NO at the outlet cross section of the first catalyst layerxActual concentration of (A)1) Calculating first catalyst layer NOxActual throughput of (A)Example 1)；
AExample 1＝(A0-A1)*V
According to the actual treatment amount (A) of the first catalyst layer NOxExample 1) NH at the outlet cross section of the first catalyst layer3Actual concentration of (B)1) And transformingCalculating the actual ammonia injection amount (B) of the first ammonia injection unit according to the ammonia nitrogen molar ratio (1:1) of the chemical reactionExample 1) In the theoretical ammonia injection amount (B) of the first ammonia injection unitPrinciple 1) And (6) correcting. Wherein the actual ammonia injection amount (B) of the first ammonia injection unitExample 1) Theoretical ammonia injection amount (B) of first ammonia injection unitPrinciple 1) The ratio of (c) is the correction coefficient (xi) of the first ammonia injection unit1) Correction coefficient (xi)1) 0.85 to 1.25.
BExample 1＝AExample 1+B1
4) The theoretical total ammonia injection amount (B) and the actual ammonia injection amount (B) of the first ammonia injection unit are calculatedExample 1) Calculating to obtain the actual ammonia injection amount (B) of the second ammonia injection unitExample 2)；
BExample 2＝B-BExample 1
5) NH at the outlet cross section of the second catalyst layer3Actual concentration of (B)2) I.e. the first actual ammonia slip rate (T)1) NO at the inlet cross section of the first catalyst layerxConcentration (A)0) And NO at the outlet cross section of the second catalyst layerxActual concentration of (A)3) Calculating to obtain the first actual denitration efficiency (eta) of the system1)；
η1＝A3/A0
Spraying ammonia to the flue gas through the second ammonia spraying unit to enable NH at the outlet section of the first catalyst layer3Actual concentration of (B)1) Not greater than NH at the inlet cross section of the second catalyst layer3Actual concentration of (1), NO at the outlet cross section of the first catalyst layerxActual concentration of (A)1) NO at the inlet cross section of the second catalyst layerxActual concentration of (A)2) The same is true.
According to the ammonia injection control method of the ammonia injection control system, the theoretical total ammonia injection amount is calculated, the actual ammonia injection amount of the first ammonia injection unit is obtained by correcting the theoretical ammonia injection amount of the first ammonia injection unit, the actual ammonia injection amount of the second ammonia injection unit is finally obtained, and ammonia injection is carried out according to the actual ammonia injection amount of each catalyst layer. This spout ammonia control system adopts total amount control regulation mode, can realize spouting the real-time regulation and accurate control of ammonia volume to the total ammonia volume of spouting of system and each ammonia unit and spout ammonia volume, makes the system not spout ammonia excessively to reach the effect that reduces ammonia escape rate and improve holistic denitration efficiency.
Further, the ammonia injection amount of the first ammonia injection unit 5 is not less than that of the second ammonia injection unit 6, the ammonia injection rate of the second ammonia injection unit 6 is 0.2-1.2 times of the flow speed of the flue gas in the reaction section, and the ammonia is injected at the injection rate, so that the flue gas can be effectively mixed with the ammonia, the nitrogen-ammonia mixture flowing through the second catalyst layer 10 has a uniform flow field and a uniform concentration field, the denitration efficiency of the second catalyst layer 10 is improved, and the denitration efficiency of the denitration system is finally improved.
Example 2
The embodiment provides an SCR denitration system, which is provided with a third catalyst layer 11, disposed in the reaction section 3 and far away from the first catalyst layer 9 relative to the second catalyst layer 10; in addition to the above embodiment 1, there is provided,
the third ammonia spraying units 7 are arranged in the reaction section 3, the third ammonia spraying units 7 are arranged between the second catalyst layer 10 and the third catalyst layer 11, the third ammonia spraying units 7 are ammonia spraying grids, preferably, the third ammonia spraying units 7 are linear ammonia spraying grids, and the number of the third ammonia spraying units 7 is 1;
a third monitoring device comprising a fifth monitoring unit and a sixth monitoring unit, wherein the fifth monitoring unit is arranged at the inlet section of the third catalyst layer 11 and is used for acquiring NO at the inlet section of the third catalyst layer 11xAnd NH3The concentration of (c); a sixth monitoring unit is arranged at the outlet cross section of the third catalyst layer 11 for obtaining NO at the outlet cross section of the third catalyst layer 11xAnd NH3The concentration of (c).
After the flue gas passes through the first ammonia spraying unit 5, the first catalyst layer 9, the second ammonia spraying unit 6 and the second catalyst layer 10 in sequence, a small amount of unreacted NO existsxAnd NH3Unreacted NOxAnd NH3With non-uniform flow and concentration fields. Third ammonia injection unit 7 for unreacted NOxAnd NH3Spraying ammonia to disturb gas atmosphere and make NOxAnd NH3More uniform mixing and then sufficient reaction occurs in the third catalyst layer 11, reducing NOxAnd NH3The denitration efficiency of the system is improved and the escape rate of ammonia is reduced.
The linear ammonia injection grid meets the use requirement of the third ammonia injection unit 7 and can ensure the unreacted NOxAnd NH3The uniform mixing of the components has the advantages of relatively low construction cost and operation and maintenance cost, so that the construction cost of the system is reduced.
Further, the reducing agent supply device is respectively communicated with the first ammonia injection unit 5, the second ammonia injection unit 6 and the third ammonia injection unit 7 so as to respectively supply the reducing agent to the first ammonia injection unit 5, the second ammonia injection unit 6 and the third ammonia injection unit 7; flow regulating valves are arranged among the reducing agent supply device, the first ammonia spraying unit 5, the second ammonia spraying unit 6 and the third ammonia spraying unit 7, and the flow regulating valves are connected with an external PLC;
further, the ammonia injection control system 12 is configured to control the ammonia injection amount of the first ammonia injection unit 5, the second ammonia injection unit 6, and the third ammonia injection unit 7.
Further, the third ammonia injection unit 7 is provided with a third nozzle, as shown in fig. 3, and the injection direction of the third nozzle forms an angle gamma of 0-90 degrees with the axial direction of the reaction section 3.
This embodiment further provides an ammonia injection control method for an SCR denitration system, as shown in fig. 5, on the basis of step 3) of the foregoing embodiment 1, the method further includes the following steps:
6) according to the flue gas flow (V) and the activity (K) of the second catalyst layer2) And the volume (Vm) of the second catalyst layer2) Obtaining the maximum NO that the second catalyst layer can processxConcentration (Am)2)；
Am2＝(K2*Vm2)/V
7) Maximum NO treatable by the second catalyst layerxConcentration (A)m2) Calculating the theoretical ammonia spraying amount (B) of the second ammonia spraying unit by the flow rate (V) of the flue gas and the ammonia nitrogen molar ratio (1:1) of the chemical reaction2 of Chinese character)；
B2 of Chinese character＝Am2*V
According to the flue gas flow (V) and NO at the inlet section of the second catalyst layerxActual concentration of (A)2) And NO at the outlet cross section of the second catalyst layerxActual concentration of (A)3) Calculating the second catalyst layer NOxActual throughput of (A)Example 2)；
AExample 2＝(A2-A3)*V
According to the second catalyst layer NOxActual throughput of (A)Example 2) NH at the outlet cross section of the second catalyst layer3Actual concentration of (B)2) And calculating the actual ammonia spraying amount (B) of the second ammonia spraying unit by the ammonia nitrogen molar ratio (1:1) of the chemical reactionExample 2) In the theoretical ammonia injection amount (B) for the second ammonia injection unit2 of Chinese character) And (6) correcting. Wherein the actual ammonia injection amount (B) of the second ammonia injection unitExample 2) Theoretical ammonia injection amount (B) of second ammonia injection unit2 of Chinese character) The ratio of (c) is the correction coefficient (xi) of the second ammonia injection unit2) Correction coefficient (xi)2) 0.85 to 1.25.
BExample 2＝AExample 2+B2
8) The theoretical total ammonia injection amount (B) and the actual ammonia injection amount (B) of the first ammonia injection unitExample 1) And the actual ammonia injection amount (B) of the second ammonia injection unitExample 2) Calculating to obtain the actual total ammonia injection amount B of the third ammonia injection unitExample 3；
BExample 3＝B-BExample 1-BExample 2
9) NH at the outlet cross section of the third catalyst layer3Actual concentration of (B)3) I.e. the second actual ammonia slip rate (T)2) NO at the inlet cross section of the first catalyst layerxConcentration (A)0) And NO at the outlet cross section of the third catalyst layerxActual concentration of (A)4) Calculating to obtain the second actual denitration efficiency (eta) of the system2)。
η2＝A4/A0
Spraying ammonia to the flue gas through a third ammonia spraying unit to enable NH at the outlet section of the second catalyst layer3Actual concentration of (B)2) Not greater than NH at the inlet cross section of the third catalyst layer3OfBoundary concentration, NO at outlet cross section of second catalyst layerxActual concentration of (A)3) NO at the inlet cross section of the third catalyst layerxActual concentration of (A)4) The same is true.
Further, the ammonia injection amount of the first ammonia injection unit 5 is not less than that of the second ammonia injection unit 6 and that of the third ammonia injection unit 7, the ammonia injection rate of the second ammonia injection unit 6 and that of the third ammonia injection unit 7 are 0.2-1.2 times of the flow speed of the flue gas in the reaction section, and ammonia is injected at the injection rate so that the ammonia and the flue gas can be more effectively mixed, and the nitrogen-ammonia mixture flowing through the second catalyst layer 10 and the third catalyst layer 11 has a uniform flow field and a uniform concentration field, so that the denitration efficiency of the second catalyst layer 10 and the denitration efficiency of the third catalyst layer 11 are improved, and the denitration efficiency of the denitration system is finally improved.
Comparative example 1
This comparative example provides an SCR deNOx systems, and with embodiment 1, the difference lies in: the first ammonia injection unit is a linear ammonia injection grid, and the system does not relate to the second ammonia injection unit. The ammonia injection amount of the SCR denitration system was the same as the total ammonia injection amount of example 1.
Test example 1
The SCR denitration systems of examples 1 to 3 and comparative example 1 were subjected to performance tests. The test results are shown in table 1. Wherein the flow rate of flue gas is 15m/s, the temperature of the flue gas is 360 ℃, and NO is at the inlet of a denitration systemxThe mass concentration was 550 ppm.
TABLE 1 Performance index of the catalyst
Numbering Denitration efficiency (%) Outlet NOx value (ppm) Ammonia slip (ppm)
Example 1 95.6 24 3
Example 2 96.3 20 2
Comparative example 1 85.5 80 6
As can be seen from table 1, the denitration efficiency of the denitration system is improved and the ammonia escape rate is reduced by providing the second ammonia injection unit and/or the third ammonia injection unit and controlling the ammonia injection amount.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims (10)

1. An SCR denitration system comprises a main body, the main body comprises a circulation section and a reaction section which are sequentially communicated, and the SCR denitration system is characterized by also comprising,
the first ammonia injection unit is arranged in the circulation section close to the flue gas inlet of the circulation section;
the ammonia injection device comprises a first catalyst layer and a second ammonia injection unit, wherein the second ammonia injection unit is arranged in the reaction section, and the first catalyst layer is arranged between the first ammonia injection unit and the second ammonia injection unit and is positioned in the reaction section;
the second catalyst layer is arranged in the reaction section and is far away from the first catalyst layer relative to the second ammonia spraying unit;
and the ammonia injection control system is used for controlling the ammonia injection amount of the first ammonia injection unit and the second ammonia injection unit.
2. The SCR denitration system of claim 1, wherein the ammonia injection control system comprises,
a gas concentration detection system arranged in the reaction section for monitoring NO in the SCR denitration systemxAnd NH3The actual concentration of (c);
and the plug-in PLC is plug-in to the gas concentration detection system, is connected with the gas concentration detection system, and is used for calculating the theoretical total ammonia injection amount of the SCR denitration system, the actual ammonia injection amount of each catalyst layer and the actual denitration efficiency, and realizing the control of the theoretical total ammonia injection amount of the SCR denitration system, the actual ammonia injection amount of each catalyst layer and the actual denitration efficiency.
3. The SCR denitration system of claim 2, wherein the gas concentration detection system comprises,
the first monitoring device comprises a first monitoring unit and a second monitoring unit, wherein the first monitoring unit is arranged at the inlet section of the first catalyst layer and is used for acquiring NO at the inlet section of the first catalyst layerxAnd NH3The concentration of (c); the second monitoring unit is arranged at the outlet section of the first catalyst layer and used for acquiring NO at the outlet section of the first catalyst layerxAnd NH3The concentration of (c);
the second monitoring device comprises a third monitoring unit and a fourth monitoring unit, wherein the third monitoring unit is arranged at the inlet section of the second catalyst layer and is used for acquiring NO at the inlet section of the second catalyst layerxAnd NH3The concentration of (c); the fourth monitoring unit is arranged at the secondAt the outlet cross section of the second catalyst layer for obtaining NO at the outlet cross section of the second catalyst layerxAnd NH3The concentration of (c).
4. The SCR denitration system of claim 2 or 3, wherein the second ammonia injection unit is provided with a second nozzle, and the injection direction of the second nozzle forms an included angle beta of 0-90 degrees with the axial direction of the reaction section.
5. The SCR denitration system of claim 4, further comprising,
a third catalyst layer disposed within the reaction section and disposed distal to the first catalyst layer relative to the second catalyst layer;
the third ammonia spraying unit is arranged in the reaction section and is arranged between the second catalyst layer and the third catalyst layer; preferably, the third ammonia spraying unit is provided with a third nozzle, and the included angle gamma between the spraying direction of the third nozzle and the axial direction of the reaction section is 0-90 degrees;
the third monitoring device comprises a fifth monitoring unit and a sixth monitoring unit, wherein the fifth monitoring unit is arranged at the inlet section of the third catalyst layer and is used for acquiring NO at the inlet section of the third catalyst layerxAnd NH3The concentration of (c); the sixth monitoring unit is arranged at the outlet section of the third catalyst layer and used for acquiring NO at the outlet section of the third catalyst layerxAnd NH3The concentration of (c).
6. The SCR denitration system of claim 5, further comprising,
the reducing agent supply device is communicated with the first ammonia injection unit, the second ammonia injection unit and/or the third ammonia injection unit respectively so as to provide the reducing agent for the first ammonia injection unit, the second ammonia injection unit and the third ammonia injection unit respectively;
flow regulating valves are arranged among the reducing agent supply device and the first ammonia spraying unit, the second ammonia spraying unit and/or the third ammonia spraying unit and are connected with the plug-in PLC;
the equal unit that mixes, set up in the circulation section, including first equal unit and the second of mixing, first ammonia unit that spouts set up in first even unit and the second of mixing are even between the unit.
7. The SCR denitration system of claim 6, wherein the distance between the first ammonia injection unit and the first uniform mixing unit is 50mm-500 mm;
the distance between the first ammonia spraying unit and the second uniform mixing unit is 50-500 mm.
8. The SCR denitration system according to claim 7, wherein the first ammonia injection unit is an ammonia injection grid, preferably the first ammonia injection unit is any one of a partition ammonia injection grid and a mixed ammonia injection grid, and the number of the first ammonia injection units is 1-3;
the second ammonia spraying units are ammonia spraying grids, preferably, the second ammonia spraying units are linear ammonia spraying grids, and the number of the second ammonia spraying units is 1 set;
the third ammonia injection unit is an ammonia injection grid, preferably, the third ammonia injection unit is a linear ammonia injection grid, and the number of the third ammonia injection units is 1 set.
9. An ammonia injection control method of an SCR denitration system is characterized by comprising the following steps:
1) according to NO at inlet cross section of first catalyst layerxCalculating the theoretical total ammonia injection amount according to the concentration, the flue gas flow and the target denitration efficiency;
2) obtaining the maximum NO which can be processed by the first catalyst layer according to the flow rate of flue gas, the activity of the first catalyst layer and the volume of the first catalyst layerxConcentration;
3) maximum NO treatable by the first catalyst layerxThe theory of the first ammonia spraying unit is obtained by calculating the concentration, the flue gas flow and the ammonia nitrogen molar ratio of the chemical reactionSpraying ammonia amount; according to the flow of flue gas and NO at the inlet section of the first catalyst layerxAnd NO at the outlet cross section of said first catalyst layerxCalculating the actual concentration of said first catalyst layer NOxActual throughput of (d); according to the first catalyst layer NOxActual throughput of the first catalyst layer, NH at the outlet cross section of the first catalyst layer3Calculating the actual ammonia injection amount of the first ammonia injection unit according to the actual concentration and the ammonia nitrogen molar ratio of the chemical reaction so as to correct the theoretical ammonia injection amount of the first ammonia injection unit;
4) calculating the actual ammonia injection amount of the second ammonia injection unit according to the theoretical total ammonia injection amount and the actual ammonia injection amount of the first ammonia injection unit;
5) NH at the outlet cross section of the second catalyst layer3Is determined by the actual concentration of NO at the inlet cross section of said first catalyst layer, i.e. the first actual ammonia slip ratexConcentration and NO at the outlet cross section of the second catalyst layerxThe first actual denitration efficiency of the system is calculated.
10. The ammonia injection control method for an SCR denitration system according to claim 8,
the ammonia injection rate of the second ammonia injection unit is 0.2-1.2 times of the flow speed of the flue gas in the reaction section;
the ammonia injection amount of the first ammonia injection unit is not less than that of the second ammonia injection unit.
CN201910871574.9A 2019-09-16 2019-09-16 SCR denitration system and ammonia injection control method thereof Pending CN110624412A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111966060A (en) * 2020-07-23 2020-11-20 湖南大唐节能科技有限公司 SCR ammonia injection control optimization method, device, equipment and storage medium
CN112379035A (en) * 2020-10-28 2021-02-19 山东电力研究院 System and method for evaluating performance of catalyst of SCR (selective catalytic reduction) denitration device on line

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111966060A (en) * 2020-07-23 2020-11-20 湖南大唐节能科技有限公司 SCR ammonia injection control optimization method, device, equipment and storage medium
CN112379035A (en) * 2020-10-28 2021-02-19 山东电力研究院 System and method for evaluating performance of catalyst of SCR (selective catalytic reduction) denitration device on line
CN112379035B (en) * 2020-10-28 2022-11-01 国网山东省电力公司电力科学研究院 System and method for evaluating performance of SCR (selective catalytic reduction) denitration device catalyst on line

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