CN117582798B - Low-resistance efficient composite denitration device for boiler flue gas and control method thereof - Google Patents
Low-resistance efficient composite denitration device for boiler flue gas and control method thereof Download PDFInfo
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- CN117582798B CN117582798B CN202410055740.9A CN202410055740A CN117582798B CN 117582798 B CN117582798 B CN 117582798B CN 202410055740 A CN202410055740 A CN 202410055740A CN 117582798 B CN117582798 B CN 117582798B
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- 239000003546 flue gas Substances 0.000 title claims abstract description 159
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 158
- 238000000034 method Methods 0.000 title claims abstract description 45
- 239000002131 composite material Substances 0.000 title claims abstract description 15
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 200
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 91
- 238000006243 chemical reaction Methods 0.000 claims abstract description 80
- 238000005507 spraying Methods 0.000 claims abstract description 71
- 230000008569 process Effects 0.000 claims abstract description 21
- 239000000779 smoke Substances 0.000 claims abstract description 13
- 238000010438 heat treatment Methods 0.000 claims description 20
- 238000000926 separation method Methods 0.000 claims description 16
- 238000001514 detection method Methods 0.000 claims description 15
- 238000007667 floating Methods 0.000 claims description 9
- 238000007790 scraping Methods 0.000 claims description 5
- 230000000712 assembly Effects 0.000 claims description 2
- 238000000429 assembly Methods 0.000 claims description 2
- 150000001875 compounds Chemical class 0.000 claims 1
- 239000007921 spray Substances 0.000 abstract description 17
- 230000009467 reduction Effects 0.000 abstract description 13
- 230000007423 decrease Effects 0.000 abstract description 4
- 239000003054 catalyst Substances 0.000 description 21
- 238000005516 engineering process Methods 0.000 description 16
- 239000003638 chemical reducing agent Substances 0.000 description 13
- 238000006722 reduction reaction Methods 0.000 description 12
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 10
- 239000004202 carbamide Substances 0.000 description 10
- 238000010531 catalytic reduction reaction Methods 0.000 description 9
- 230000001276 controlling effect Effects 0.000 description 6
- 238000000354 decomposition reaction Methods 0.000 description 6
- 239000000428 dust Substances 0.000 description 6
- 230000001105 regulatory effect Effects 0.000 description 6
- 230000009471 action Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 238000007789 sealing Methods 0.000 description 3
- 150000001412 amines Chemical class 0.000 description 2
- 238000006477 desulfuration reaction Methods 0.000 description 2
- 230000023556 desulfurization Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000010881 fly ash Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 231100000167 toxic agent Toxicity 0.000 description 1
- 239000003440 toxic substance Substances 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
Classifications
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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
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/75—Multi-step processes
-
- 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
- B01D53/30—Controlling by gas-analysis apparatus
-
- 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
- B01D53/346—Controlling the process
-
- 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
- B01D53/77—Liquid phase processes
- B01D53/79—Injecting reactants
-
- 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
- B01D53/8631—Processes characterised by a specific device
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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
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8696—Controlling the catalytic process
-
- 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 invention relates to the technical field of denitration devices, in particular to a low-resistance high-efficiency composite denitration device for boiler flue gas and a control method thereof, comprising the following steps: the top of the boiler is provided with a smoke exhaust pipeline; the air inlet end of the SCR reactor is fixedly communicated with the end part of the smoke exhaust pipeline; the first ammonia spraying component is arranged on the inner wall of the boiler and is used for spraying ammonia gas into the boiler; in the denitration process, the temperature of the flue gas at the spraying position of the first spray head is detected through the first temperature sensor, when the flue gas does not reach or exceed a preset reaction temperature range, the first spray head corresponding to the flue gas is controlled to be closed, and ammonia gas spraying is stopped, so that NO caused by overhigh reaction temperature is avoided x The reduction rate decreases, or when the reaction temperature is too low, the ammonia slip increases.
Description
Technical Field
The invention relates to the field of denitration devices, in particular to a low-resistance high-efficiency composite denitration device for boiler flue gas and a control method thereof.
Background
At present, the domestic traditional denitration technology is a single selective catalytic reduction technology, namely SCR (selective catalytic reduction) technology or a single selective non-catalytic reduction technology, namely SNCR (selective non-catalytic reduction).
1. Selective catalytic reduction technology, SCR for short;
the current popular SCR technology is mainly divided into two types, namely ammonia SCR and urea SCR. Both of these methods utilize ammonia pair No x Is carried out by reacting No with catalyst x (mainly NO) reduction to N with little effect on the atmosphere 2 And water. The reducing agent is NH 3 The difference is that in the urea method SCR, urea is firstly converted into ammonia by a device and then is conveyed to SCR catalyst reactionThe conversion is to inject urea into a decomposition chamber which provides the mixing time, residence time and temperature required for urea decomposition, whereby the amino products of the decomposition of the chamber become the reductant of the SCR to produce ammonia and water after chemical reaction over the catalyst. The decomposition method for ammonia in the urea decomposition chamber comprises a pyrolysis method and a hydrolysis method, and the main chemical reaction equation is as follows:
in the design of the overall process, ammonia is usually vaporized, mixed with dilution air or flue gas, and finally sprayed into the flue gas upstream of the SCR reactor through a distribution grid.
Within the SCR reactor, NO is reduced by the following reaction:
when oxygen is present in the flue gas, the reaction first takes place preferentially, so that the ammonia consumption has a one-to-one relationship with the NO reduction.
NO in the flue gas of the boiler 2 Generally about total No x Concentration of 5%, NO 2 The reactions involved are as follows:
the two reactions above indicate the reduction of NO 2 More ammonia is required than for the reduction of NO.
In most boiler flue gases, NO 2 Only occupy No x A small fraction of the total amount, thus NO 2 The effect of (2) is not significant.
SCR System No x The removal efficiency is generally high, and the ammonia injected into the flue gas is almost complete and No x And (3) reacting. A small portion of the ammonia does not react but rather escapes the reactor as ammonia. Generally, ammonia slip is low for new catalysts. However, as the catalyst becomes deactivated or the surface becomes covered or clogged with fly ash, the ammonia slip increases to maintain the desired No x The NH content in the reactor must be increased 3 /No x Molar ratio. When the performance criteria of the pre-set denitration efficiency and ammonia slip cannot be ensured, a new catalyst must be added or replaced in the reactor to restore the activity of the catalyst and the reactor performance. The period of time from the start of use of a new catalyst to being replaced is referred to as catalyst life.
No in the Selective catalytic reduction Process x With NH 3 The reduction takes place under the action of the catalyst. The catalyst is placed in a fixed reactor through which the flue gas passes in parallel across the catalyst surface. The catalyst units are generally vertically arranged and the flue gas flows from top to bottom.
The SCR system generally comprises an ammonia storage system, an ammonia and air mixing system, an ammonia spraying system, a reactor system, a detection control system and the like.
Selective non-catalytic reduction technology, SNCR for short;
selective catalytic reduction for removal of NO x The operating costs of (a) are mainly affected by the catalyst lifetime, and a selective reduction process that does not require a catalyst may be more advanced, which is a selective non-catalytic reduction technique. The technique is to use NH 3 Reducing agent such as urea and the like is sprayed into the furnace and is sprayed with NO x The selective reaction is carried out without a catalyst, and therefore a reducing agent must be added in a high temperature zone. The reducing agent is sprayed into the area with the hearth temperature of 850-1100 ℃ and is quickly thermally decomposed into NH 3 And with NO in the flue gas x SNCR reaction is carried out to generate N 2 The method takes a hearth as a reactor.
According to the prior art, the denitration effect of a single SNCR process and a single SCR process is low;
although some SNCR and SCR hybrid denitration methods are provided in the prior art, studies have found that in the SNCR denitration system:
the reducing agent is NH 3 Or an amino reducing agent such as urea;
NH at 850-1100 deg.C 3 Or urea reduction of NO x The main reactions of (a) are:
NH 3 is a reducing agent
Urea as reducing agent
When the temperature is higher than 1100 ℃, NH 3 Will be oxidized into
Different reducing agents have different reaction temperature ranges, which are referred to as temperature windows. NH (NH) 3 The optimal reaction temperature range is 850-110O deg.C. When the reaction temperature is too high, NO is generated due to decomposition of ammonia x The reduction rate decreases, and on the other hand, when the reaction temperature is too low, ammonia slip increases, and NO is also caused x The reduction rate decreases. NH (NH) 3 Is a high-volatility and toxic substance, and the escape of ammonia can cause new environmental pollution;
in summary, the SNCR process has low investment cost, but has high ammonia escape and low denitration efficiency, the SNCR+SCR combined denitration technology combines the characteristics of the SCR process and the SNCR process, and the SNCR technology is adopted to remove most of NO in the front stage of the denitration process x And only a small amount of SCR catalyst is needed at the tail part of the denitration process to enable the NO in the flue gas x In the existing denitration technology, however, it is difficult to adaptively adjust a denitration system according to the temperature of the flue gas, SNCR denitration is performed when the temperature of the flue gas reaches a range of 850-1100 ℃, and SCR denitration is performed on the flue gas when the temperature of the flue gas does not reach a temperature range of SNCR denitration.
Disclosure of Invention
The invention aims to solve the defect that a denitration system is difficult to adaptively adjust according to the temperature of flue gas in the prior art, and provides a low-resistance high-efficiency composite denitration device for boiler flue gas and a control method thereof.
To achieve the above object, in a first aspect, the present invention provides a low-resistance efficient composite denitration device for boiler flue gas, comprising:
the top of the boiler is provided with a smoke exhaust pipeline;
the air inlet end of the SCR reactor is fixedly communicated with the end part of the smoke exhaust pipeline;
the first ammonia spraying component is arranged on the inner wall of the boiler and is used for spraying ammonia gas into the boiler;
the first temperature detection component is used for detecting the temperature of the flue gas at the spraying position of the first ammonia spraying component so as to determine whether the flue gas is in a preset reaction temperature range;
the controller is used for controlling the first ammonia spraying component to stop spraying ammonia to the corresponding position when the flue gas does not reach or exceed a preset reaction temperature range;
in the exhaust process of the flue gas, ammonia gas is sprayed into the boiler through the first ammonia spraying component, so that the ammonia gas and NO in the flue gas x The SNCR denitration is completed after the reaction;
in the denitration process, the temperature of the flue gas at the spraying position of the first spray head is detected through the first temperature sensor, when the flue gas does not reach or exceed a preset reaction temperature range, the first spray head corresponding to the flue gas is controlled to be closed, and ammonia gas spraying is stopped, so that the condition that the NOx reduction rate is reduced due to overhigh reaction temperature or the escape amount of ammonia is increased due to overlow reaction temperature is avoided;
flue gas that temperature is not up to standard flows to SCR reactor through exhaust pipe, carries out SCR denitration, and the device detects flue gas temperature in advance, and its denitration system of rational regulation has reduced ammoniaEscape amount, flue gas is treated in advance by combining SCR and SNCR for denitration, and in a subsequent SCR system, NO in the flue gas can be realized by adopting a small amount of SCR catalyst x And (5) discharging after reaching the standard.
Preferably, the method further comprises:
the flue gas separation grid is arranged in the flue gas exhaust pipeline and is internally provided with a plurality of flow guide cavities;
the second ammonia spraying assembly is used for spraying ammonia into each flue gas separation grid;
the second temperature detection assemblies are arranged in the diversion cavities and are used for detecting the temperature of the flue gas in each diversion cavity so as to determine whether the flue gas is in a preset reaction temperature range;
the controller is further used for controlling the second ammonia spraying component to introduce ammonia into the flow guiding cavity when the temperature of the flue gas in the flow guiding cavity reaches a preset reaction temperature range, and controlling the second ammonia spraying component to stop introducing ammonia into the flow guiding cavity when the temperature of the flue gas does not reach or exceeds the preset reaction temperature range.
In a second aspect, the invention provides a control method of a low-resistance efficient composite denitration device for boiler flue gas, comprising the following steps:
detecting the temperature of the flue gas at the spraying position of the first ammonia spraying component through the first temperature detecting component so as to determine whether the flue gas is in a preset reaction temperature range;
and when the temperature does not reach or exceed the preset reaction temperature range, the controller controls the first ammonia spraying component to stop spraying ammonia to the corresponding position.
Preferably, the method further comprises:
detecting the temperature of the flue gas in the diversion cavity through a second temperature detection assembly to determine whether the flue gas is in a preset reaction temperature range;
when the temperature of the flue gas in the diversion cavity reaches a preset reaction temperature range, controlling the second ammonia spraying component to introduce ammonia gas into the diversion cavity through the controller;
when the temperature of the flue gas does not reach or exceed a preset reaction temperature range, the controller controls the second ammonia spraying component to stop introducing ammonia into the flow guiding cavity.
Preferably, the method further comprises:
detecting the temperature of the flue gas in the diversion cavity through a second temperature detection assembly;
when the temperature of the flue gas in the flow guiding cavity reaches a preset floating reaction temperature range, the controller controls the heating assembly to heat the inside of the flow guiding cavity.
Compared with the prior art, the invention has the following beneficial effects:
1. in the exhaust process of the flue gas, ammonia gas is sprayed into the boiler through the first ammonia spraying component, so that the ammonia gas and NO in the flue gas x The SNCR denitration is completed after the reaction; in the denitration process, the temperature of the flue gas at the spraying position of the first spray head is detected through the first temperature sensor, when the flue gas does not reach or exceed a preset reaction temperature range, the first spray head corresponding to the flue gas is controlled to be closed, and ammonia gas spraying is stopped, so that NO caused by overhigh reaction temperature is avoided x The reduction rate decreases, or when the reaction temperature is too low, the ammonia slip increases;
2. flue gas that temperature is not up to standard carries out SCR denitration through exhaust pipe flow direction SCR reactor, and the device detects flue gas temperature in advance, and its denitration system of rational adjustment has reduced the escape volume of ammonia, still combines the denitration through SCR and SNCR, carries out the preliminary treatment to the flue gas, in follow-up SCR system, only needs to adopt a small amount of SCR catalyst can make flue gas NO x And (5) discharging after reaching the standard.
Drawings
FIG. 1 is a flow chart of a control method of the present invention.
Fig. 2 is a schematic diagram of the overall structure of the present invention.
FIG. 3 is a schematic cross-sectional view of the boiler according to the present invention.
Fig. 4 is an enlarged schematic view of the structure of fig. 3 according to the present invention.
Fig. 5 is a schematic cross-sectional view of a smoke exhaust duct according to the present invention.
Fig. 6 is an enlarged schematic view of the structure of fig. 5 at B according to the present invention.
Fig. 7 is a schematic diagram of a cross-sectional structure of a smoke exhaust duct according to the present invention.
Fig. 8 is an enlarged schematic view of the structure of fig. 7 at C according to the present invention.
Fig. 9 is a schematic diagram of a cross-sectional structure of a smoke exhaust duct according to the present invention.
In the figure: 1. a boiler; 2. a smoke exhaust duct; 3. an SCR reactor; 4. a controller; 5. a communicating pipe; 6. a first nozzle; 7. a first temperature sensor; 8. a flue gas separation grid; 9. a diversion cavity; 10. a second nozzle; 11. a second temperature sensor; 12. a heating member; 13. a regulating valve; 14. a shielding plate; 15. a deflector aperture; 16. a pushing member; 17. a sealing gasket; 18. a moving plate; 19. scraping the strip; 20. a mounting cavity; 21. an elastic member.
Detailed Description
The following description is presented to enable one of ordinary skill in the art to make and use the invention. The preferred embodiments in the following description are by way of example only and other obvious variations will occur to those skilled in the art.
The low-resistance high-efficiency composite denitration device for boiler flue gas as shown in fig. 2 to 9 comprises:
the boiler 1, the top of the boiler 1 is provided with a smoke exhaust pipeline 2;
the SCR reactor 3, the air inlet end of the SCR reactor 3 is fixedly communicated with the end part of the smoke exhaust pipeline 2;
the first ammonia spraying component is arranged on the inner wall of the boiler 1 and is used for spraying ammonia gas into the boiler 1;
the first temperature detection component is used for detecting the temperature of the flue gas at the spraying position of the first ammonia spraying component so as to determine whether the flue gas is in a preset reaction temperature range;
the controller 4 is used for controlling the first ammonia spraying component to stop spraying ammonia to the corresponding position when the flue gas does not reach or exceed the preset reaction temperature range;
the SNCR technology has low investment cost, but has high ammonia escape and low denitration efficiency, the SNCR+SCR combined denitration technology combines the characteristics of the SCR technology and the SNCR technology, and the SNCR technology is adopted to remove most of NO in the front stage of the denitration technology x And only a small amount of SCR catalyst is needed at the tail part of the denitration process to enable the NO in the flue gas x In the denitration process, however, the denitration system is difficult to adaptively adjust according to the temperature of the flue gas, SNCR denitration is performed when the temperature of the flue gas reaches the range of 850-1100 ℃, and SCR denitration is performed on the flue gas when the temperature of the flue gas does not reach the temperature range of SNCR denitration;
as an alternative embodiment, the first ammonia injection assembly comprises a communicating pipe 5, the communicating pipe 5 is fixed on the inner wall of the boiler 1, a plurality of first spray heads 6 are fixed on the surface of the communicating pipe 5, and the communicating pipe 5 is fixedly communicated with an external reducing agent conveying device through a pipeline;
the first temperature detection assembly comprises a plurality of first temperature sensors 7, wherein the first temperature sensors 7 are fixed on the surface of the communicating pipe 5, and the number of the first temperature sensors 7 corresponds to the number of the first spray heads 6 one by one;
the preset reaction temperature range is 850-1100 ℃;
specifically, during the exhaust process of the flue gas, ammonia gas is sprayed into the boiler 1 through the first ammonia spraying component, so that the ammonia gas and NO in the flue gas x The SNCR denitration is completed after the reaction;
in the denitration process, the temperature of the flue gas at the spraying position of the first spray head 6 is detected by the first temperature sensor 7, when the flue gas does not reach or exceed a preset reaction temperature range, the first spray head 6 corresponding to the flue gas is controlled to be closed, and ammonia gas spraying is stopped, so that the condition that the reduction rate of NOx is reduced due to overhigh reaction temperature or the escape amount of ammonia is increased due to overlow reaction temperature is avoided;
flue gas that temperature is not up to standard carries out SCR denitration through exhaust pipe 2 flow direction SCR reactor 3, and the device detects flue gas temperature in advance, and its denitration system of rational adjustment has reduced the escape volume of ammonia, still combines the denitration through SCR and SNCR, carries out the advanced treatment to the flue gas, in subsequent SCR system, only needs to adopt a small amount of SCR catalyst can make flue gas NOx discharge up to standard.
As a further embodiment, further comprising:
the flue gas separation grid 8 is arranged in the flue gas exhaust pipeline 2, and a plurality of flow guide cavities 9 are formed in the flue gas separation grid 8;
the second ammonia spraying component is used for spraying ammonia into each flue gas separation grid 8;
the second temperature detection assembly is arranged inside each flow guide cavity 9 and is used for detecting the temperature of the flue gas in each flow guide cavity 9 so as to determine whether the flue gas is in a preset reaction temperature range;
the controller 4 is further configured to control the second ammonia spraying component to introduce ammonia into the flow guiding cavity 9 when the temperature of the flue gas in the corresponding flow guiding cavity 9 reaches a preset reaction temperature range, and control the second ammonia spraying component to stop introducing ammonia into the flow guiding cavity 9 when the temperature of the flue gas does not reach or exceed the preset reaction temperature range;
as an alternative embodiment, a plurality of groups of second ammonia spraying components are arranged in each diversion cavity 9, each group of second ammonia spraying components comprises a plurality of second spray heads 10, the second spray heads 10 are mutually communicated through pipelines, and the second spray heads 10 are fixed on the inner wall of the diversion cavity 9 through pipelines;
when needing to be described, all the second spray heads 10 are mutually communicated through pipelines, and the pipelines of the second spray heads 10 are communicated with an external reducing agent conveying device;
the second temperature detection assembly comprises a plurality of second temperature sensors 11, and the second temperature sensors 11 are respectively fixed on the inner walls of the diversion cavities 9;
in particular, NO x The distribution in the hearth is changed frequently, if too few spraying control points or uneven distribution of ammonia sprayed on a certain section in the furnace occurs, high ammonia escape amount with higher distribution can occur, and in a larger coal-fired boiler, the reducing agent is uniformly distributedEven distribution is more difficult because the longer injection distance is required to cover a relatively large furnace cross section to ensure that the denitration reaction proceeds adequately with minimal NH injection 3 The amount to achieve the best reduction must be managed to achieve the injected NH 3 Well mixed with flue gas;
therefore, by arranging the flue gas separation grid 8, on one hand, the flue gas is separated to be in a smaller cavity, and ammonia gas is sprayed into each small diversion cavity 9, so that the flue gas and the ammonia gas can be fully reacted;
on the other hand, as the temperature of the flue gas is also uneven, after the flue gas is separated into small spaces, the temperature of the flue gas in each space can be better detected, the temperature of the flue gas in the corresponding flow guide cavity 9 is detected through the second temperature sensor 11, when the temperature of the flue gas in the flow guide cavity 9 reaches a preset reaction temperature range, the second spray head 10 is controlled by the controller 4 to be introduced into the flow guide cavity 9 for SNCR denitration, when the temperature of the flue gas does not reach or exceed the preset reaction temperature range, the second spray head 10 is controlled to be closed, the introduction of the ammonia into the flow guide cavity 9 is stopped, so that the flue gas can directly flow to the SCR reactor 3 for SCR denitration, and then the denitration method of the flue gas is better adjusted in time according to the temperature of the flue gas.
As a further embodiment, further comprising:
the heating component is used for heating the flue gas in each diversion cavity 9;
the controller 4 is further configured to control the heating component to heat the interior of the corresponding flow guiding cavity 9 when the temperature of the flue gas in the flow guiding cavity 9 does not reach the preset reaction temperature range, but reaches the preset floating reaction temperature range;
the minimum value of the preset floating reaction temperature range is lower than the minimum value of the preset reaction temperature range;
as an alternative embodiment, the heating assembly comprises a plurality of heating elements 12, and the plurality of heating elements 12 are respectively fixed on the inner wall of the diversion cavity 9;
the heating element 12 can be a heating plate or a heating wire;
it should be noted that, the preset floating reaction temperature range can be adaptively adjusted according to the heating efficiency of the heating assembly, and in this embodiment, the preset floating reaction temperature range is 840-860 ℃;
specifically, detect the inside flue gas temperature of getting into water conservancy diversion chamber 9 through second temperature sensor 11, under the condition that the temperature of flue gas and preset reaction temperature range differ little, can carry out instantaneous heating to the flue gas through heating element, the temperature of rising flue gas to make the flue gas can carry out denitration reaction in water conservancy diversion chamber 9 inside, be favorable to avoiding the temperature of flue gas to differ little with preset reaction temperature range under the condition, the flue gas directly gets into SCR reactor 3, leads to SCR reactor 3 denitration pressure great, influences desulfurization efficiency's condition emergence.
As a further embodiment, further comprising:
the regulating valves 13 are arranged at the tail ends of the corresponding diversion cavities 9, and the regulating valves 13 are used for regulating the exhaust amount of the diversion cavities 9;
the controller 4 is further used for controlling the regulating valve 13 to reduce the exhaust gas amount of the diversion cavity 9 in the process of spraying the amine by the second ammonia spraying assembly;
as an alternative embodiment, the adjusting valve 13 can be arranged at the end part of the diversion cavity, and the opening and closing of the adjusting valve 13 can be controlled in an electric control mode to adjust the exhaust amount of the diversion cavity 9;
specifically, when the flue gas enters the guide cavity 9 to carry out the desulfurization reaction, the controller 4 controls the regulating valve 13 to reduce the exhaust amount of the guide cavity 9, thereby being beneficial to prolonging the residence time of the flue gas in the guide cavity 9 and further enabling the flue gas to be fully denitrated.
As a further embodiment, further comprising:
a shielding plate 14, wherein a plurality of diversion holes 15 are formed on the surface of the shielding plate 14;
a pushing member 16, wherein the pushing member 16 is used for pushing the shielding plate 14 to move towards one side close to the diversion cavity 9;
the controller 4 is further configured to control the pushing member 16 to push the shielding plate 14 to shield the end of the flow guiding cavity 9 during the amine spraying process of the second ammonia spraying assembly, so as to reduce the exhaust amount of the flow guiding cavity 9;
as an alternative embodiment, the pusher 16 may be an electric cylinder or an air cylinder;
a frame type sealing gasket 17 is fixed on one side of the shielding plate 14 facing the diversion cavity 9;
specifically, the pushing piece 16 pushes the shielding plate 14 to move to the side close to the diversion cavity 9 until the sealing gasket 17 of the shielding plate 14 contacts with the end part of the diversion cavity 9 and seals the end part of the diversion cavity 9, so that the flue gas in the diversion cavity 9 can only flow out from the position of the diversion hole 15 of the shielding plate 14, the exhaust capacity of the diversion cavity 9 is reduced, the stay time of the flue gas in the diversion cavity 9 is prolonged, and the flue gas can be fully denitrated;
however, this embodiment is different from the adjusting valve 13 in that the flow guiding chamber 9 is a rectangular body in this example, and by moving the shielding plate 14, not only the amount of exhaust gas in the flow guiding chamber 9 can be adjusted, but also the end portion of the flow guiding chamber 9 can be in a completely opened state after the shielding plate 14 is completely separated from the flow guiding chamber 9, thereby facilitating the discharge of dust inside the flow guiding chamber 9.
As a further embodiment, further comprising:
the movable plate 18, the movable plate 18 is slidably arranged in the diversion cavity 9;
the elastic pushing component is used for pushing the tail end of the moving plate 18 to extend out of the tail end of the diversion cavity 9;
a scraper bar 19, the scraper bar 19 being disposed above the moving plate 18;
when the shielding plate 14 moves towards the tail end of the diversion cavity 9, the shielding plate 14 pushes the moving plate 18 to move towards the inside of the diversion cavity 9;
when the shielding plate 14 is far away from the diversion cavity 9, the elastic pushing component pushes the moving plate 18 to slide towards the tail end of the diversion cavity 9, and the moving plate 18 and the scraping strip 19 slide relatively;
as an alternative embodiment, the elastic pushing rod assembly comprises a mounting cavity 20, the mounting cavity 20 is arranged on the inner wall of the diversion cavity 9, an elastic piece 21 is fixed in the mounting cavity 20, the end part of the elastic piece 21 is fixed on the moving plate 18, the elastic piece 21 can be a spring or a pushing strip with elasticity, and the elastic piece 21 shown in fig. 6 is a spring;
under the pushing action of the elastic piece 21, the moving plate 18 has a trend of moving towards the tail end of the diversion cavity 9, when the shielding plate 14 is in contact with the end part of the diversion cavity 9, the moving plate 18 is pushed to compress the elastic piece 21, so that the elastic piece 21 generates elastic force due to the accumulation force, when the shielding plate 14 is reset towards the side far away from the diversion cavity 9, the moving plate 18 is pushed to slide towards the tail end of the diversion cavity 9 through the elastic piece 21, and the scraping strip 19 moves relatively, so that the surface of the moving plate 18 is scraped through the scraping strip 19, so that dust is separated from the moving plate 18, and under the blowing action of air flow, the dust can move along with the air flow, enter the inside of the SCR reactor 3 and be collected through a dust collecting device inside the SCR reactor 3;
and at this time, the tail end of the diversion cavity 9 is in a completely opened state, which is more beneficial to dust discharge.
As a further embodiment, the flue gas separation grid 8 is in an inclined state and the lowest end of the flue gas separation grid 8 is close to one end of the SCR reactor 3; specifically, by inclining the flue gas separation grid 8 towards one end of the SCR reactor 3, the discharge of dust in the flue gas is further facilitated under the action of gravity.
The control method of the low-resistance high-efficiency composite denitration device for the boiler flue gas shown in fig. 1 comprises the following steps:
detecting the temperature of the flue gas at the spraying position of the first ammonia spraying component through the first temperature detecting component so as to determine whether the flue gas is in a preset reaction temperature range;
when the temperature does not reach or exceed the preset reaction temperature range, the controller 4 controls the first ammonia spraying component to stop spraying ammonia to the corresponding position.
As a further embodiment, further comprising:
detecting the temperature of the flue gas in the diversion cavity 9 through a second temperature detection assembly to determine whether the flue gas is in a preset reaction temperature range;
when the temperature of the flue gas in the flow guiding cavity 9 reaches a preset reaction temperature range, the controller 4 controls the second ammonia spraying component to introduce ammonia gas into the flow guiding cavity 9;
when the temperature of the flue gas does not reach or exceed the preset reaction temperature range, the controller 4 controls the second ammonia spraying component to stop introducing ammonia into the flow guiding cavity 9.
As a further embodiment, further comprising:
detecting the temperature of the flue gas in the diversion cavity 9 through a second temperature detection assembly;
when the temperature of the flue gas in the diversion cavity 9 reaches a preset floating reaction temperature range, the controller 4 controls the heating assembly to heat the interior of the diversion cavity 9.
The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the foregoing embodiments, but rather, the foregoing embodiments and description illustrate the principles of the invention, and that various changes and modifications may be effected therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.
Claims (7)
1. A high-efficient compound denitrification facility of low resistance for boiler flue gas, its characterized in that includes:
the boiler comprises a boiler (1), wherein a smoke exhaust pipeline (2) is arranged at the top of the boiler (1);
the system comprises an SCR reactor (3), wherein the air inlet end of the SCR reactor (3) is fixedly communicated with the end part of the smoke exhaust pipeline (2);
the first ammonia spraying component is arranged on the inner wall of the boiler (1) and is used for spraying ammonia gas into the boiler (1);
the first temperature detection component is used for detecting the temperature of the flue gas at the spraying position of the first ammonia spraying component so as to determine whether the flue gas is in a preset reaction temperature range;
the controller (4) is used for controlling the first ammonia spraying component to stop spraying ammonia to the corresponding position when the smoke does not reach or exceed a preset reaction temperature range;
further comprises:
the flue gas separation grid (8), the flue gas separation grid (8) is arranged in the flue gas exhaust pipeline (2), and a plurality of flow guide cavities (9) are formed in the flue gas separation grid (8);
the second ammonia spraying component is used for spraying ammonia into each flue gas separation grid (8);
the second temperature detection assemblies are arranged inside the diversion cavities (9) and are used for detecting the temperature of the flue gas in each diversion cavity (9) so as to determine whether the flue gas is in a preset reaction temperature range;
the controller (4) is further used for controlling the second ammonia spraying component to introduce ammonia into the flow guiding cavity (9) when the temperature of the flue gas in the corresponding flow guiding cavity (9) reaches a preset reaction temperature range, and controlling the second ammonia spraying component to stop introducing ammonia into the flow guiding cavity (9) when the temperature of the flue gas does not reach or exceed the preset reaction temperature range;
further comprises:
the device comprises a shielding plate (14), wherein a plurality of diversion holes (15) are formed in the surface of the shielding plate (14);
a pushing piece (16), wherein the pushing piece (16) is used for pushing the shielding plate (14) to move towards one side close to the diversion cavity (9);
the controller (4) is further used for controlling the pushing piece (16) to push the shielding plate (14) to shield the tail end of the flow guiding cavity (9) in the ammonia spraying process of the second ammonia spraying assembly, so that the exhaust amount of the flow guiding cavity (9) is reduced.
2. The low resistance high efficiency composite denitration device for boiler flue gas of claim 1, further comprising:
the heating component is used for heating the flue gas in each diversion cavity (9);
the controller (4) is further used for controlling the heating component to heat the inside of the corresponding flow guiding cavity (9) when the temperature of the flue gas in the flow guiding cavity (9) does not reach a preset reaction temperature range but reaches a preset floating reaction temperature range;
the minimum value of the preset floating reaction temperature range is lower than the minimum value of the preset reaction temperature range.
3. The low resistance high efficiency composite denitration device for boiler flue gas of claim 2, further comprising:
the movable plate (18) is arranged in the diversion cavity (9) in a sliding manner;
the elastic pushing assembly is used for pushing the tail end of the moving plate (18) to extend out of the tail end of the flow guiding cavity (9);
a scraper bar (19), the scraper bar (19) being arranged above the moving plate (18);
when the shielding plate (14) moves towards the tail end of the diversion cavity (9), the shielding plate (14) pushes the moving plate (18) to move towards the inside of the diversion cavity (9);
when the shielding plate (14) is far away from the diversion cavity (9), the elastic pushing assembly pushes the moving plate (18) to slide towards the tail end of the diversion cavity (9), and the moving plate (18) and the scraping strip (19) slide relatively.
4. A low resistance efficient composite denitration device for boiler flue gas according to claim 3, characterized in that the flue gas separation grid (8) is in an inclined state and the lowest end of the flue gas separation grid (8) is close to one end of the SCR reactor (3).
5. A control method for a low-resistance high-efficiency composite denitration device for boiler flue gas according to claim 4, characterized by comprising the steps of:
detecting the temperature of the flue gas at the spraying position of the first ammonia spraying component through the first temperature detecting component so as to determine whether the flue gas is in a preset reaction temperature range;
and when the temperature does not reach or exceed the preset reaction temperature range, the controller (4) controls the first ammonia spraying component to stop spraying ammonia to the corresponding position.
6. The control method of the low-resistance high-efficiency composite denitration device for boiler flue gas according to claim 5, further comprising:
detecting the temperature of the flue gas in the diversion cavity (9) through a second temperature detection assembly to determine whether the flue gas is in a preset reaction temperature range;
when the temperature of the flue gas in the flow guiding cavity (9) reaches a preset reaction temperature range, the controller (4) controls the second ammonia spraying component to introduce ammonia into the flow guiding cavity (9);
when the temperature of the flue gas does not reach or exceed a preset reaction temperature range, the controller (4) controls the second ammonia spraying component to stop introducing ammonia into the flow guiding cavity (9).
7. The control method of the low-resistance high-efficiency composite denitration device for boiler flue gas according to claim 5, further comprising:
detecting the temperature of the flue gas in the diversion cavity (9) through a second temperature detection assembly;
when the temperature of the flue gas in the diversion cavity (9) reaches a preset floating reaction temperature range, the controller (4) controls the heating assembly to heat the interior of the diversion cavity (9).
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| CN112675698A (en) * | 2020-12-23 | 2021-04-20 | 山东祥桓环境科技有限公司 | Desulfurization, denitrification and dust removal device of turbulent bed in separate bin and process thereof |
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2024
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| JPH10211417A (en) * | 1998-03-16 | 1998-08-11 | Dale Goodon Jones | Method and apparatus for injecting into two-stage boiler to reduce nitrogen oxide |
| EP2151272A2 (en) * | 2008-08-08 | 2010-02-10 | Lab Sa | Method and installation for purifying combustion fumes containing nitrogen oxides |
| CN102179171A (en) * | 2011-03-28 | 2011-09-14 | 浙江大学 | Multi-stage themolysis coupled denitration method using front flow field uniformizing device and device thereof |
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| CN112675698A (en) * | 2020-12-23 | 2021-04-20 | 山东祥桓环境科技有限公司 | Desulfurization, denitrification and dust removal device of turbulent bed in separate bin and process thereof |
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| CN117582798A (en) | 2024-02-23 |
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