CN100400962C - Method for reburning nitrogen oxides by coal combustion boiler and apparatus thereof - Google Patents
Method for reburning nitrogen oxides by coal combustion boiler and apparatus thereof Download PDFInfo
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- CN100400962C CN100400962C CNB2005100611222A CN200510061122A CN100400962C CN 100400962 C CN100400962 C CN 100400962C CN B2005100611222 A CNB2005100611222 A CN B2005100611222A CN 200510061122 A CN200510061122 A CN 200510061122A CN 100400962 C CN100400962 C CN 100400962C
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Abstract
The present invention relates to the improved technology of a boiler, which has the aim to provide a method for reducing the content of nitrogen oxide generated in the combustion process of a coal combusting boiler and a device for realizing the method. The method provided by the present invention comprises steps that coal as main fuel is loaded into a main combustion zone of a boiler; nitrogen oxide is generated in the combustion carried out under the condition that the excess air factor alpha of the main combustion zone ranges from 1.0 to 1.1; the rest coal as secondary combustion fuel is sprayed into a secondary combustion zone through a secondary combustion spraying opening; a reducing atmosphere is formed under the condition that the excess air factor alpha is smaller than one, and thereby, the nitrogen oxide is reduced. The present invention also provides a boiler device for realizing the method. The present invention directly uses the boiler for combusting coal, the discharge of nitrogen oxide is effectively reduced under the condition that the original combustion situations of a boiler are not influenced basically, and the existing boilers can be rebuilt easily.
Description
Technical field
The present invention relates to the improvement technology of boiler, relate in particular to a kind of device that can reduce the amount of nitrogen oxides that is produced in the coal-burning boiler combustion process.
Background technology
(NOx comprises NO, NO to nitrogen oxide
2And N
2O) be the gas that a class can cause the atmospheric environment severe contamination, be considered to one of main source of atmosphere pollution basically.Occupy significant proportion at the nitrogen oxide that world wide discharges because of combustion of fossil fuels every year in all discharged nitrous oxides.N in nitrogen oxide
2O may cause greenhouse effects (temperature rising), NO and NO
2Be considered to cause the major reason of ground level ozone, photochemical fog and acid rain formation.The environmental regulation of increasingly stringent requires the advanced technology of research and development, to reduce the discharging of pollutants such as NOx.The maximum characteristics of China's Energy Mix are based on coal at present, account for more than 70%, and this will produce a large amount of oxides of nitrogen gas, and economical and efficient is increased therefore such energy resource structure and ecological environment all can have a negative impact.The existing control measure that nitrogen oxide is taked are control its generations or with its reduction in fired coal combustion or after burning.The general method that adopts of control in the fired coal combustion process is the air classification burning, fuel-staged combustion, low oxygen combustion or flue gas recirculation method or the like; Though these method costs are lower, system's service condition requires lower, and existing shortcoming is that denitration efficiency is on the low side, can not fully reach the requirement that reduces discharged nitrous oxides.And the method for the discharging of control nitrogen oxide is to adopt wet chemistry absorption process or dry method selective catalytic reduction or the like behind the fired coal combustion; Though this control method denitration efficiency height is can make NO become N
2Conversion ratio reach more than 90%, but that its shortcoming is an initial cost is big, operating cost is too high, is not suitable for China's national situation, the possibility of applying on a large scale in the recent period is less.
Summary of the invention
Problem at above-mentioned existing technology status and existence, the invention provides a kind of method and device thereof that reduces exhaustion of nitrogen oxides from coal-fired boiler, by directly utilizing the boiler coal dust burning, under the prerequisite that does not influence original efficiency of combustion of coal-burning boiler and boiler performance, under condition cheaply, effectively reduce the discharging of nitrogen oxide, to reach the requirement of environment protection emission.
The invention provides a kind of coal-burning boiler and fire low NOx technology implementation method again, the steps include:
(1) the main fuel coal that will account for caloric value 65%-85% is sent into boiler master combustion zone, is that burning generates nitrogen oxide under 1.0～1.1 the condition at the excess air factor α of main combustion zone;
(2) the reburning fuel coal that all the other is accounted for caloric value 15%-35% sprays into the reburning district by firing spout again, forms reducing atmosphere at excess air factor α under less than 1 condition, makes the nitrogen oxide reduction;
(3) spray into hot-air from the after-flame wind snout, the uncombusted fuel combustion is complete.
In technique scheme, the reburning fuel coal is a coal dust, and the temperature at the reburning fuel nozzle place when coal dust sprays in the stove is in 1200 ℃ of-1600 ℃ of scopes; Described coal-fired again powder is the fuel coal dust, need not to handle through special processing, perhaps adopts other fuel.
In technique scheme, in order to improve the percent reduction of nitrogen oxide (NOx), the time of staying of reburning fuel in the reburning zone is not less than 0.3 second; According to gas stream in the stove speed difference, the reburning zone height is 1～3m.
Be to realize the boiler of said method, comprise body of heater and mounted thereto 's burner, burner hearth is divided into main combustion zone, reburning zone and burning-out zone three parts from the bottom up successively; 2～3 wind snouts, 3～4 overfire air ports and 1～2 tertiary air spout layered arrangement are formed main combustion zone; Each spout height carries out reasonable Arrangement according to the boiler furnace actual conditions, and tertiary air spout pulverized coal borne air flow speed is 40～60m/s.
Firing the above stove inner region to the after-flame wind snout of spout again is the reburning zone, and the reburning zone keeps reducing atmosphere, and furnace air/chemistry of fuel equivalent proportion is 0.8～1.0, to help reductive NO; The spout of combustion again of reburning zone is arranged in 300～1000mm place, tertiary air spout top, preferred 500mm, and to reduce the tertiary air jet to firing the influence of jet again, the burning for main combustion fuel simultaneously provides more time.
The above zone to furnace outlet of after-flame wind snout is a burning-out zone.In burning-out zone, according to coal characteristic, excess air coefficient is 1.15～1.25 in the stove, guarantees that pulverized coal particle has enough after-flame degree.The after-flame wind snout is arranged in and fires vertical height 1000～3000mm place, spout top, preferred 2000mm again.
The after-flame wind snout is made of with following after-flame wind snout is two-layer last after-flame wind snout, controls flow separately.When the after-flame wind snout is arranged, consider the abundant after-flame of coal dust, guarantee that the burning-out zone time of staying was greater than 1 second.
The advantage that the present invention is had compared with the prior art is:
1, directly utilizes boiler fired coal, substantially do not influencing under the condition of the original combustion position of boiler, effectively reduce the discharging of nitrogen oxide, the discharge capacity that can reduce nitrogen oxide is more than 50%, and can be with out of stock effect, control cost and operability well combines.
2, be easy to existing boiler is transformed, only need to transform burner, with original the superiors wind wind powder air-flow as firing wind powder air-flow again, and the position of burner made corresponding adjustment, can realize corresponding environmental requirement, substantially all very suitable for now moving burning smoke coal, boiler using brown coal.
3, this technology is convenient and easy on the implementation, and is reliable and do not increase the operation amount.
The remodeling method of the low NOx of a kind of coal-burning boiler of the present invention and the middle warehouse formula boiler that device is applicable to burning smoke coal, brown coal thereof all are suitable for for medium-sized, large-sized boiler, have broad application prospects.
Description of drawings
Fig. 1 uses a kind of quadrangle tangential circle that reduces the method for exhaustion of nitrogen oxides from coal-fired boiler of the present invention to arrange combustion system coal-fired boiler reform schematic diagram.
Specific embodiment
In conjunction with specific embodiments a kind of method and device thereof that reduces exhaustion of nitrogen oxides from coal-fired boiler of the present invention is described in further detail with reference to the accompanying drawings below.
Shown in figure one is a kind of four jiaos of coal-burning boiler devices of arranging the straight flow combustion mode, and right side 12 is existing coal-burning boiler device, and left side 11 is for implementing the coal-burning boiler device after the inventive method is improved.Boiler after the improvement is divided into main combustion zone, reburning zone and burning-out zone three parts from the bottom up successively to burner hearth.
(1) main combustion zone: by following overfire air port 1, next time wind snout 2, middle overfire air port 3, last wind snout 4, go up overfire air port 5 and 6 six layers of spout of tertiary air spout are formed main combustion zone, by adjusting air distribution between each spout of main combustion zone, realize the classification low oxygen combustion.Main combustion zone can be that 2～3 wind snouts, 3～4 overfire air ports and 1～2 tertiary air spout layered arrangement are formed; Reduce tertiary air spout 6 height of existing coal-burning boiler, be arranged in upper strata, main combustion zone.Tertiary air spout 6 and fire 7 squares of spout again and keep certain distance 900mm, to reduce the tertiary air jet to firing the influence of jet again, the burning for main combustion fuel simultaneously provides more time, and tertiary air spout pulverized coal borne air flow speed is 45m/s.
(2) reburning district: adjust existing wind snout 41 of coal-burning boiler the 3rd floor (being former last wind snout 41) and arrange height, widen the distance between last wind snout 41 and the top after-flame wind snout, use last wind snout 41 as firing spout 7 again.Guarantee to fire again the reducing atmosphere between spout and after-flame wind snout, form and fire the reducing zone again, reduce the NOx of main combustion zone formation.
(3) burning-out zone: on move the last overfire air port 51 and after-flame wind snout 10 positions of existing coal-burning boiler, as the last after-flame wind snout 9 and the following after-flame wind snout 8 of this programme.The after-flame wind snout divides two-layer layout, can control separately.
(4) fire spout 7 again apart from after-flame wind snout vertical height 2000mm, the after-flame wind snout is apart from furnace bottom vertical height 10m.Guarantee that the reburning zone time of staying is 0.4 second, 2 seconds burning-out zone time of staying.
Take the method for following reduction nitrogen oxide in the coal-burning boiler device application process after the improvement: (1) will account for the main fuel coal of caloric value 65%～85% and send into boiler master combustion zone, be that burning generates nitrogen oxide under 1.1 the condition at the excess air factor α of main combustion zone; (2) the reburning fuel coal that all the other is accounted for caloric value 15%～35% sprays into the reburning district by firing spout again, the time of staying of reburning fuel in the reburning zone is not less than 0.3 second, the temperature at the reburning fuel nozzle place when coal dust sprays in the stove is at 1400 ℃, form reducing atmosphere at excess air factor α under less than 1 condition, make the nitrogen oxide reduction; (3) add remaining air at burning-out zone, excess air coefficient returns to normal value 1.2～1.25, and last completing combustion product is fully burnt, to guarantee the after-flame effect.
The hypoxemia fractional combustion can be adopted in main simultaneously combustion zone, reduces main combustion zone NOx growing amount.
After method of the present invention and the device practical application, not only can effectively reduce nitrogen oxide NOx discharging 40～60%, easy operating and control do not increase the operation amount.And be easy to transform existing coal-burning boiler device, keeping cheaply under the situation,, install necessary nozzle, spout additional, so this method and device thereof have application and popularization value widely only to existing coal-burning boiler appropriate reconstruction.
In the specific embodiment of the invention 1, account for whole heat output of fuel ratios: the main fuel coal is 75%, and wherein bunker coal is 10% in the tertiary air; The reburning fuel coal is 25%, and the excess air factor α of main combustion zone is 1.05, and reburning district excess air factor α is 0.9; The temperature at reburning fuel nozzle place is 1400 ℃, and the time of staying of reburning fuel in the reburning zone is 0.5 second; The spout of combustion again of reburning zone is arranged in 600mm place, tertiary air spout top, and the after-flame wind snout is arranged in and fires vertical height 2000mm place, spout top again.
In the specific embodiment of the invention 2, account for whole heat output of fuel ratios: the main fuel coal is 65%, and tertiary air is stopped transport; The reburning fuel coal is 35%, and the excess air factor α of main combustion zone is 1.1, and reburning district excess air factor α is 0.8; The temperature at reburning fuel nozzle place is 1200 ℃, and the time of staying of reburning fuel in the reburning zone is 0.3 second; The spout of combustion again of reburning zone is arranged in 300mm place, tertiary air spout top, and the after-flame wind snout is arranged in and fires vertical height 1000mm place, spout top again.
In the specific embodiment of the invention 3, the primary zone by following overfire air port, next time wind snout, in down overfire air port, in wind snout, in go up overfire air port, last wind snout, go up overfire air port and 2 layers of tertiary air spout.Account for whole heat output of fuel ratios: the main fuel coal is 85%, and wherein bunker coal is 10% in the tertiary air, and the reburning fuel coal is 15%; The excess air factor α of main combustion zone is 1.0, and reburning district excess air factor α is 0.95; The temperature at reburning fuel nozzle place is 1600 ℃, and the time of staying of reburning fuel in the reburning zone is 0.7 second; The spout of combustion again of reburning zone is arranged in 1000mm place, tertiary air spout top, upper strata, and the after-flame wind snout is arranged in and fires vertical height 3000mm place, spout top again.
At last, it is also to be noted that what more than enumerate only is specific embodiments of the invention.Obviously, the invention is not restricted to above embodiment, many distortion can also be arranged.The present invention can summarize with other the concrete form without prejudice to spirit of the present invention and principal character.Therefore, no matter from which point, above-mentioned embodiment of the present invention all can only be thought can not limit the present invention to explanation of the present invention, claims have been pointed out scope of the present invention, and scope of the present invention is not pointed out in above-mentioned explanation, therefore, in implication suitable and any change in the scope, all should think to be included in the scope of claims with claims of the present invention.
Claims (2)
1. coal-burning boiler device that fires nitrogen oxide again comprises body of heater and mounted thereto 's burner, and it is characterized in that: burner hearth is divided into main combustion zone, reburning zone and burning-out zone three parts from the bottom up successively; 2～3 wind snouts, 3～4 overfire air ports and 1～2 tertiary air spout layered arrangement are formed main combustion zone; The spout of combustion again of reburning zone is arranged in 300～1000mm place, tertiary air spout top; The after-flame wind snout is arranged in and fires vertical height 1000～3000mm place, spout top again.
2. according to the described coal-burning boiler device that fires nitrogen oxide again of claim 1, it is characterized in that: the after-flame wind snout is made of last after-flame wind snout and two of following after-flame wind snouts, controls flow separately.
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| Application Number | Priority Date | Filing Date | Title |
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| CNB2005100611222A CN100400962C (en) | 2005-10-14 | 2005-10-14 | Method for reburning nitrogen oxides by coal combustion boiler and apparatus thereof |
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| CNB2005100611222A CN100400962C (en) | 2005-10-14 | 2005-10-14 | Method for reburning nitrogen oxides by coal combustion boiler and apparatus thereof |
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| CN1773168A CN1773168A (en) | 2006-05-17 |
| CN100400962C true CN100400962C (en) | 2008-07-09 |
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Families Citing this family (9)
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| CN101639226B (en) * | 2008-08-01 | 2011-05-11 | 中国神华能源股份有限公司 | Method for burning coal in boiler |
| CN102003701B (en) * | 2010-11-23 | 2012-12-26 | 浙江大学 | Low NOx coal dust combustion method and device based on underfire air and overfire air |
| CN102588956B (en) * | 2012-03-15 | 2014-09-10 | 北京志源恒通科技有限公司 | Novel rotational flow impact boiler and manufacturing method thereof |
| CN103672863B (en) * | 2013-12-31 | 2016-02-10 | 北京国电龙高科环境工程技术有限公司 | The using method of the low nitrogen combustion apparatus of middle warehouse formula pulverized coal carried by hot air boiler |
| CN105299638A (en) * | 2014-06-30 | 2016-02-03 | 四川川锅锅炉有限责任公司 | Low-NOx combustor arrangement mode and structure for intermediate storage bunker coal pulverizing system |
| CN104251487A (en) * | 2014-09-24 | 2014-12-31 | 西安西热锅炉环保工程有限公司 | Method for improving boiler combustion economy of tangential combustion anthracite coal boiler |
| CN104964286A (en) * | 2015-05-19 | 2015-10-07 | 华中科技大学 | Sludge treatment method capable of reducing discharge of nitrogen oxide in pulverized coal boiler at the same time |
| CN105716074B (en) * | 2016-02-29 | 2018-07-31 | 徐州杰能电力设备有限公司 | Tiny-oil ignition low nitrogen burning system |
| CN108087867A (en) * | 2018-01-11 | 2018-05-29 | 西安热工研究院有限公司 | It is a kind of to be used to balance underload nitrogen oxides and the low nitrogen burning system and method for carbonated drink parameter |
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Assignee: Hangzhou Baineng Technology Co.,Ltd. Assignor: Zhejiang University Contract fulfillment period: 2008.9.10 to 2018.9.9 Contract record no.: 2008330000569 Denomination of invention: Method for reburning nitrogen oxides by coal combustion boiler and apparatus thereof Granted publication date: 20080709 License type: Exclusive license Record date: 20080921 |
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