CN112387114A - Device and method for effectively improving SCR denitration efficiency - Google Patents
Device and method for effectively improving SCR denitration efficiency Download PDFInfo
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- CN112387114A CN112387114A CN202011312106.7A CN202011312106A CN112387114A CN 112387114 A CN112387114 A CN 112387114A CN 202011312106 A CN202011312106 A CN 202011312106A CN 112387114 A CN112387114 A CN 112387114A
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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
- B01D53/8621—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
- B01D53/90—Injecting reactants
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- 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
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- 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 discloses a device and a method for effectively improving SCR denitration efficiency, wherein the device comprises an SCR inlet flue, an SCR outlet flue and a reactor, wherein the SCR inlet flue is communicated with the SCR outlet flue through the reactor; the SCR inlet flue inner space is divided into a plurality of virtual reactor inlet flues, the SCR outlet flue inner space is divided into a plurality of virtual reactor outlet flues, the reactor inner space is divided into a plurality of virtual reaction zones, wherein one virtual reactor inlet flue corresponds to one virtual reaction zone and one virtual reactor outlet flue, each virtual reactor inlet flue is communicated with the corresponding virtual reactor outlet flue through the corresponding virtual reaction zone, each virtual reactor inlet flue is provided with a subarea flue gas mixer capable of fully and uniformly mixing flue gas components, the device can provide the requirement of good ammonia nitrogen molar ratio distribution uniformity for high-efficiency denitration of the catalyst, and the dynamically controlled ammonia escape level reaches the standard.
Description
Technical Field
The invention belongs to the technical field of denitration, and relates to a device and a method for effectively improving SCR denitration efficiency.
Background
The conventional SCR flow field can only control the relative standard deviation (hereinafter referred to as "CV value") of the ammonia nitrogen molar ratio of the cross section of the catalyst inlet to be about 5% under the condition that NOx at the SCR inlet is uniform, even if the amount of the catalyst is sufficient, the maximum denitration efficiency of the conventional SCR flow field can be stably operated for a long time and the ammonia escape does not exceed the standard is about 90% -93%, otherwise, a large amount of ammonia nitrogen escapes because the local ammonia nitrogen molar ratio exceeds 1.0. In addition, the NOx at the inlet of the SCR is not uniformly distributed when the boiler is under different working conditions, the distribution rule is not stable, and the ammonia injection amount of each local area cannot be automatically adjusted by the conventional ammonia injection grid of the SCR; and because SCR entry flue is short, and the flue gas mixing condition is limited, can't carry out intensive mixing with ammonia and NOx on full section in order to reach the requirement that highly even ammonia nitrogen mole ratio distributes, consequently even denitration efficiency is not higher than 90% -93%, also can't guarantee that ammonia escapes and reaches standard all the time.
Thus, the initial NOx concentration is 650mg/m3And above, ultra-low emission needs to be achieved, and the concentration of NOx at the outlet is controlled to be lower than 50mg/m3In general, the SNCR system is required to be added to pre-remove the NOx concentration to 650mg/m3And finally, the ultra-low emission is achieved through SCR. The technical route not only has high investment and operation cost, but also has extremely difficult control of ammonia escape, and finally leads to blockage of subsequent equipment such as an air preheater and the like due to deposition of ammonium bisulfate.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a device and a method for effectively improving SCR denitration efficiency, wherein the device can dynamically control the ammonia escape level to reach the standard.
In order to achieve the aim, the device for effectively improving the SCR denitration efficiency comprises an SCR inlet flue, an SCR outlet flue and a reactor, wherein the SCR inlet flue is communicated with the SCR outlet flue through the reactor;
the internal space of the SCR inlet flue is divided into a plurality of virtual reactor inlet flues, the internal space of the SCR outlet flue is divided into a plurality of virtual reactor outlet flues, and the internal space of the reactor is divided into a plurality of virtual reaction zones, wherein one virtual reactor inlet flue corresponds to one virtual reaction zone and one virtual reactor outlet flue, and each virtual reactor inlet flue is communicated with the corresponding virtual reactor outlet flue through the corresponding virtual reaction zone;
an ammonia injection grid, a subarea flue gas mixer and a flue gas mixing section are sequentially arranged in the inlet flue of the virtual reactor along the flue gas flowing direction, and a flue gas outlet flue of the virtual reactor is internally provided with a device for detecting NOx and O at the flue gas measuring point in the outlet flue of the virtual reactor2The flue gas on-line monitoring system of concentration, wherein, the entrance of each ammonia injection grid all is provided with the ammonia governing valve, and flue gas on-line monitoring system's output is connected with control system's input, and control system's output respectively with the entrance of each ammonia injection gridThe ammonia regulating valve is connected.
And a subarea flue gas mixer is arranged in the inlet flue of each virtual reactor to fully and uniformly mix the flue gas components in the section.
The number of virtual reactors is related to the size of the cross section of the flue, the cross section of the virtual reactors is close to a square, and the number of the SCR single side can be 3-5.
The flue gas is reasonably organized, and the flue gas diffusion does not exist or rarely exists between the adjacent virtual reactors.
And arranging online measuring points of NOx and O2 for outlet flues of the virtual reactors, and guiding the adjustment of ammonia regulating valves at inlets of the virtual reactors in real time to level the concentration of the outlet NOx.
The invention has the following beneficial effects:
the device and the method for effectively improving the SCR denitration efficiency can obviously improve the ammonia nitrogen molar ratio distribution uniformity in the cross section of the catalyst inlet, and can obviously improve the denitration efficiency when the catalyst amount is enough and the ammonia escape control requirement is not changed. During specific operation, the internal space of the SCR inlet flue is divided into a plurality of virtual reactor inlet flues, the internal space of the SCR outlet flue is divided into a plurality of virtual reactor outlet flues, and the internal space of the reactor is divided into a plurality of virtual reaction zones, wherein the virtual reactor inlet flues, one virtual reaction zone and one virtual reactor outlet flue correspond to one virtual reactor system, and the partitioned flue gas mixers in the virtual reactor inlet flues fully mix flue gas components in the virtual reactor inlet flues uniformly, so that each virtual reactor does not have a region with the ammonia nitrogen molar ratio exceeding 1.0. Then according to NOx and O of flue gas in outlet flue of each virtual reactor2And the concentration is controlled, the ammonia injection amount of the ammonia injection grid in each virtual reactor system is respectively controlled, the ammonia injection amount of each virtual reactor system is dynamically measured and adjusted, the dynamic uniformity of the concentration of NOx in the outlet flue of each virtual reactor is ensured, the requirements of high denitration efficiency and low ammonia escape are met, and the dynamic control of the ammonia escape level is realized.
Drawings
FIG. 1 is a schematic structural diagram of the present invention.
Wherein, 1 is an SCR inlet flue, 2 is an ammonia regulating valve, 3 is a virtual reactor inlet flue, 4 is an ammonia injection grid, 5 is a subarea flue gas mixer, 6 is a flue gas mixing section, 7 is a virtual subarea partition board, 8 is a control system, 9 is a virtual reaction zone, 10 is an on-line flue gas monitoring system, 11 is a flue gas measuring point, and 12 is an SCR outlet flue.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings:
referring to fig. 1, the apparatus for effectively improving SCR denitration efficiency according to the present invention includes an SCR inlet flue 1, an SCR outlet flue 12, and a reactor, wherein the SCR inlet flue 1 is communicated with the SCR outlet flue 12 through the reactor; the internal space of the SCR inlet flue 1 is divided into a plurality of virtual reactor inlet flues 3, the internal space of the SCR outlet flue 12 is divided into a plurality of virtual reactor outlet flues, and the internal space of the reactor is divided into a plurality of virtual reaction zones 9, wherein one virtual reactor inlet flue 3 corresponds to one virtual reaction zone 9 and one virtual reactor outlet flue, and each virtual reactor inlet flue 3 is communicated with the corresponding virtual reactor outlet flue through the corresponding virtual reaction zone 9; an ammonia injection grid 4, a subarea flue gas mixer 5 and a flue gas mixing section 6 are sequentially arranged in the inlet flue 3 of the virtual reactor along the flue gas flowing direction, and NOx and O at a flue gas measuring point 11 in the outlet flue of the virtual reactor are detected in the outlet flue of the virtual reactor2The online concentration flue gas monitoring system 10 comprises an ammonia regulating valve 2 arranged at each inlet of an ammonia injection grid 4, an output end of the online concentration flue gas monitoring system 10 is connected with an input end of a control system 8, and an output end of the control system 8 is respectively connected with the ammonia regulating valve 2 at each inlet of the ammonia injection grid 4; the number of the virtual reactor inlet flues 3 is related to the section characteristics of the flues, the section of each virtual reactor inlet flue 3 is approximate to a square, and the number of the virtual reactors of the single-side SCR is generally 3-5.
The virtual reactor inlet flue 3, one virtual reaction zone 9 and one virtual reactor outlet flue correspond to one virtual reactor system. The cross-section of the inlet flue 3 of each virtual reactor is approximately a square flue section, so that the smoke components in the area are conditionedFully mixing the mixture under the condition that the newly added resistance is acceptable, wherein the newly added resistance is generally less than 100Pa, and the mol ratio of the ammonia nitrogen in each subarea is mixed to be within 1-2% of the relative standard deviation. The number of the virtual reactors is related to the section characteristics of the flue, generally, 3-5 virtual reactors can be arranged on one side, and compared with the conventional accurate ammonia spraying technology, the method can obviously reduce the number of the subareas, improve the measurement representativeness of the smoke components in the subareas, improve the correspondence of the smoke components before and after the virtual reactors, improve the measurement response speed of the outlet subareas and reduce the adjustment difficulty. The flue gas on-line monitoring system 10 is used for detecting NOx and O of flue gas at the outlet flue of each virtual reactor2And thereby controlling the amount of ammonia injection corresponding to the ammonia injection grid 4 in the virtual reactor inlet flue 3. During actual operation, the SCR inlet flue 1, the SCR outlet flue 12 and the reactor can be actually separated by arranging the virtual partition plate 7, or the SCR inlet flue 1, the SCR outlet flue 12 and the reactor can be simulated and separated without arranging the virtual partition plate 7, so that the aim that smoke components are basically not diffused among partitions is fulfilled, and the smoke components before and after the same partition are strictly corresponding to each other.
Through tests, the method can improve the SCR denitration efficiency from the conventional highest 90-93% to the 95% level, and dynamically control the ammonia escape level to reach the standard, so that the inlet NOx boundary when the SCR directly achieves ultralow emission is 650mg/m3Greatly increased to 1000mg/m3。
Finally, the invention can stably ensure the distribution uniformity of the ammonia nitrogen molar ratio, improve the SCR denitration efficiency, reduce the whole ammonia escape level and ensure the safety of subsequent equipment under the condition that the NOx distribution at the SCR inlet is frequently changed or the concentration distribution is not uniform in a large range.
Claims (6)
1. The device and the method for effectively improving the SCR denitration efficiency are characterized by comprising an SCR inlet flue (1), an SCR outlet flue (12) and a reactor, wherein the SCR inlet flue (1) is communicated with the SCR outlet flue (12) through the reactor;
the internal space of the SCR inlet flue (1) is divided into a plurality of virtual reactor inlet flues (3), the internal space of the SCR outlet flue (12) is divided into a plurality of virtual reactor outlet flues, and the internal space of the reactor is divided into a plurality of virtual reaction zones (9), wherein one virtual reactor inlet flue (3) corresponds to one virtual reaction zone (9) and one virtual reactor outlet flue, and each virtual reactor inlet flue (3) is communicated with the corresponding virtual reactor outlet flue through the corresponding virtual reaction zone (9);
an ammonia injection grid (4), a subarea flue gas mixer (5) and a flue gas mixing section (6) are sequentially arranged in the inlet flue (3) of the virtual reactor along the flue gas flowing direction, and NOx and O at a flue gas measuring point (11) in the outlet flue of the virtual reactor are detected in the outlet flue of the virtual reactor2Flue gas on-line monitoring system (10) of concentration, wherein, the entrance of each ammonia injection grid (4) all is provided with ammonia governing valve (2), and the output of flue gas on-line monitoring system (10) is connected with the input of control system (8), and the output of control system (8) is connected with ammonia governing valve (2) of each ammonia injection grid (4) entrance respectively.
2. The device and the method for effectively improving the SCR denitration efficiency according to claim 1 are characterized in that an ammonia spraying grid and a subarea flue gas mixer are arranged in the inlet flue of each virtual reactor, the subarea flue gas mixer fully and uniformly mixes flue gas components in the section of the flue, the measurement representativeness is obviously improved, and the number of the virtual reactors is reduced.
3. The apparatus and method for improving SCR denitration efficiency according to claim 1, wherein the number of the inlet flues (3) of the virtual reactor is 3-5, and the cross section of each inlet flue of the virtual reactor is close to a square, so as to improve the mixing effect and reduce the additional resistance.
4. The device and the method for effectively improving SCR denitration efficiency according to claim 1, wherein the number of the inlet flues (3) of each virtual reactor is equal to that of the outlet flues (12) of each virtual reactor, the flue gas corresponds to the flue gas from front to back one by one, and no or little flue gas diffusion occurs between the flues of the inlet and the outlet of the adjacent virtual reactors.
5. The device and the method for effectively improving the SCR denitration efficiency according to claim 1, wherein a NOx and O2 online measuring point is arranged in each virtual reactor outlet flue (12), and an automatic ammonia injection regulating valve is arranged in an ammonia injection grid in each virtual reactor inlet flue.
6. The apparatus and method for improving efficiency of SCR denitration according to claim 1, wherein each virtual reactor inlet ammonia injection automatic regulating valve adjusts the ammonia injection amount in real time according to the outlet NOx distribution to level the outlet NOx distribution.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011312106.7A CN112387114A (en) | 2020-11-20 | 2020-11-20 | Device and method for effectively improving SCR denitration efficiency |
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| CN202011312106.7A CN112387114A (en) | 2020-11-20 | 2020-11-20 | Device and method for effectively improving SCR denitration efficiency |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4820492A (en) * | 1986-02-12 | 1989-04-11 | Babcock-Hitachi Kabushiki Kaisha | Apparatus for denitration |
| CN205627632U (en) * | 2016-05-12 | 2016-10-12 | 西安西热锅炉环保工程有限公司 | High performance SCR minimum discharge control system based on subregion mixes to be adjusted |
| CN106621804A (en) * | 2016-11-15 | 2017-05-10 | 国家电网公司 | Fume ammonia injection mixing device and SCR (selective catalytic reduction) fume denitrification system |
| CN106984191A (en) * | 2017-03-29 | 2017-07-28 | 华电电力科学研究院 | A kind of efficient hybrid system of reducing agent ammonia and its method of work for SCR denitrating flue gas |
| CN207996570U (en) * | 2018-01-04 | 2018-10-23 | 湖南华电常德发电有限公司 | A kind of SCR denitration system |
| CN109529614A (en) * | 2018-12-28 | 2019-03-29 | 西安西热锅炉环保工程有限公司 | A kind of NOx subregion patrols survey dynamic spray ammonia balance control system and method |
-
2020
- 2020-11-20 CN CN202011312106.7A patent/CN112387114A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4820492A (en) * | 1986-02-12 | 1989-04-11 | Babcock-Hitachi Kabushiki Kaisha | Apparatus for denitration |
| CN205627632U (en) * | 2016-05-12 | 2016-10-12 | 西安西热锅炉环保工程有限公司 | High performance SCR minimum discharge control system based on subregion mixes to be adjusted |
| CN106621804A (en) * | 2016-11-15 | 2017-05-10 | 国家电网公司 | Fume ammonia injection mixing device and SCR (selective catalytic reduction) fume denitrification system |
| CN106984191A (en) * | 2017-03-29 | 2017-07-28 | 华电电力科学研究院 | A kind of efficient hybrid system of reducing agent ammonia and its method of work for SCR denitrating flue gas |
| CN207996570U (en) * | 2018-01-04 | 2018-10-23 | 湖南华电常德发电有限公司 | A kind of SCR denitration system |
| CN109529614A (en) * | 2018-12-28 | 2019-03-29 | 西安西热锅炉环保工程有限公司 | A kind of NOx subregion patrols survey dynamic spray ammonia balance control system and method |
Non-Patent Citations (1)
| Title |
|---|
| 岳涛等: "《工业锅炉大气污染控制技术与应用》", 中国环境出版社, pages: 307 - 308 * |
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