CN103706241B - For the SNCR denitration method for flue gas of CFBB full load mode - Google Patents
For the SNCR denitration method for flue gas of CFBB full load mode Download PDFInfo
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- CN103706241B CN103706241B CN201310620062.8A CN201310620062A CN103706241B CN 103706241 B CN103706241 B CN 103706241B CN 201310620062 A CN201310620062 A CN 201310620062A CN 103706241 B CN103706241 B CN 103706241B
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Abstract
The invention discloses a kind of SNCR denitration method for flue gas for CFBB full load mode, belong to SNCR denitrating flue gas field, it by injecting reducing agent in flue gas, in reducing agent and flue gas, NOx reacts and denitration, comprise: when fire box temperature is more than 850 DEG C, or boiler load higher than 50% time, injection of reducing agent exit point is chosen as: essential cyclone inlet horizontal flue, and optional other spray site; Be less than 850 DEG C when fire box temperature is greater than 800 DEG C, or boiler load is when 30-50%, injection of reducing agent exit point is chosen as: essential furnace wall, and optional other spray site; When fire box temperature is below 800 DEG C, or boiler load lower than 30% time, injection of reducing agent exit point is chosen as: essential secondary air duct, and optional other spray site.The present invention be a kind of can denitration and make SNCR gas denitrifying technology denitration efficiency reach the method for more than 85% under CFB boiler full load mode.
Description
Technical field
The invention belongs to SNCR denitrating flue gas field.
Background technology
SNCR (SNCR) denitrating flue gas is a kind of full-fledged NOx control technology.SNCR cardinal principle is not having under catalyst action, in 850 ~ 1170 DEG C of high-temperature flue gas, inject reducing agent, and in reducing agent and flue gas, NOx reacts and generates N
2.Compared with SCR (SCR) denitrating technique, SNCR has that technique is simple, investment and the low feature of operating cost, is particularly suitable for the relatively low recirculating fluidized bed of furnace outlet NOx concentration (CFB) boiler.
Existing CFB-SNCR technology mainly sprays into reducing agent at CFB boiler cyclone inlet horizontal flue place, and reducing agent mixes with flue gas and reacts with NOx in flue gas in cyclone separator.Although flue gas mixes with reducing agent acutely in cyclone separator, but because reducing agent time of staying in separator is short, be difficult to ensure that reducing agent mixes with flue gas is full and uniform, the enough reaction time can not be provided for the reduction reaction of NOx, make the denitration efficiency of existing CFB-SNCR technology only can reach 50% under the load condition of 100%, also only can reach the denitration efficiency of 70% in optimal conditions, more high efficiency denitration requirement can not be met; And when CFB boiler at low load runs, as 30-70% boiler load operating mode, when fire box temperature is lower than 850 DEG C, SNCR denitration efficiency is very low or to no effect, can not meet boiler full load denitration requirement.Therefore, when CFB boiler furnace outlet NOx concentration is more than 300mg/Nm
3time, CFB emission of NOx of boiler concentration can not control at 100mg/Nm by existing CFB-SNCR technology
3below (GB13223-2011) and lower.Therefore, CFB-SNCR technology must be promoted further, improve CFB-SNCR technology denitration efficiency and the adaptability to boiler load, up to standard to ensure that CFB boiler meets NOx emission under full load mode, and keep the advantage of CFB boiler in pollutant catabolic gene.
There is the arrangement that various reducing agent sprays in prior art, but all can not meet the SNCR denitrating flue gas requirement of boiler full load mode.The present inventor is by finding the research of prior art, such as, in burner hearth, bottom by boiler First air or/and Secondary Air sprays into reducing agent carry out SNCR denitration: when reducing agent sprays into burner hearth by First air, because CFBB bottom concentration of solid particles is comparatively large, the easier active component Fe in solid particle of reducing agent
2o
3, be oxidized to NOx under the catalytic action such as CaO, do not reach the object of NO_x removal, furnace outlet NOx concentration can be caused on the contrary to increase; And spray into reducing agent by means of only Secondary Air and carry out SNCR denitration reaction, be also difficult to realize the denitration efficiency more than 70%.Therefore, if adopt the method, the object reaching efficient removal NOx is difficult to.
Summary of the invention
The object of the invention is to: the defect existed for existing CFB-SNCR denitration technology and deficiency, the present invention is based on experimental study, according to the temperature window under CFB boiler different load, choose denitrification reducing agent in the different jeting area of boiler and the combinations of injections implementing denitrification reducing agent in boiler zones of different, strengthening denitrification reducing agent mixes with the full and uniform of flue gas, extend reducing agent and NOx reaction time, provide a kind of can denitration and make SNCR gas denitrifying technology denitration efficiency reach the method for more than 85% under CFB boiler full load mode.
The present inventor by the research of prior art and the CFB-SNCR injection of reducing agent exit point screening test of carrying out on CFBC experimental rig, obtains as drawn a conclusion:
1, be spray into reducing agent all without denitration effect from First air within the scope of 700-930 DEG C in fire box temperature, and NOx concentration have certain increase;
2, when fire box temperature is changed to 700 DEG C from 930 DEG C, best injection of reducing agent exit point position moves forward to furnace wall by cyclone inlet gradually, then moves forward to Secondary Air pipeline by furnace wall;
3, spray into reducing agent from positions such as separator outlet, fluidized wind pipeline, material returning device, external bed and there is certain denitration effect, but be not best injection of reducing agent exit point.
Thus, the object of the invention is realized by following technical proposals:
For a SNCR denitration method for flue gas for CFBB full load mode, it by injecting reducing agent in flue gas, and in reducing agent and flue gas, NOx reacts and denitration, comprising:
1) when fire box temperature is more than 850 DEG C, or boiler load higher than 50% time, injection of reducing agent exit point is chosen as: essential cyclone inlet horizontal flue, and optional Cyclone outlet, secondary air duct, furnace wall, fluidisation air channel, material returning device, one or more in external bed;
2) 850 DEG C are less than when fire box temperature is greater than 800 DEG C, or boiler load is when 30-50%, injection of reducing agent exit point is chosen as: essential furnace wall, and optional cyclone inlet horizontal flue, Cyclone outlet, secondary air duct, fluidisation air channel, material returning device, one or more in external bed;
3) when fire box temperature is below 800 DEG C, or boiler load lower than 30% time, injection of reducing agent exit point is chosen as: essential secondary air duct, and optional cyclone inlet horizontal flue, Cyclone outlet, furnace wall, fluidisation air channel, material returning device, one or more in external bed.
As selection, when injection of reducing agent exit point comprises secondary air duct, mixing arrangement is set in described secondary air duct.
As selection, when injection of reducing agent exit point comprises fluidisation air channel, mixing arrangement is set in described fluidisation air channel.
In such scheme, the mixture homogeneity of reducing agent and Secondary Air/fluidized wind can be strengthened.
The main scheme of aforementioned the present invention and each further selection scheme thereof can independent assortment to form multiple scheme, be the present invention and can adopt and claimed scheme.As in the present invention, each select can and main scheme and other select any combination, those skilled in the art can understand there is multiple combination according to prior art and common practise after understanding the present invention program, do not do exhaustive at this.
Beneficial effect of the present invention: the present invention can generate level according to the fire box temperature window under CFB boiler different load and NOx, for CFB boiler provides different SNCR denitration reducing agents to spray arrangement and the strategy that puts into operation, ensure that CFB-SNCR denitration efficiency all can meet or exceed 85% under CFB boiler full load operating condition.The invention enables and reach 400mg/Nm in CFB boiler NOx generation concentration
3level time, still can only adopt SNCR denitration technology just can meet NOx emission concentration limit <100mg/Nm
3requirement (GB13223-2011), and even lowlyer reach 50mg/Nm
3below.
Accompanying drawing explanation
Fig. 1 is the technology arrangement schematic flow sheet of the embodiment of the present invention;
1 be cyclone inlet horizontal flue, 2 be wherein Cyclone outlet, 3 be secondary air duct, 4 be furnace wall, 5 be fluidisation air channel, 6 be material returning device, 7 be external bed, 8 be burner hearth, 9 be cyclone separator, 10 be back-end ductwork, 11 be external bed, 12 be fluidized air blower, 13 be First air preheater, 14 be primary air fan, 15 be Secondary Air preheater, 16 for overfire air fan.
Detailed description of the invention
Following non-limiting examples is for illustration of the present invention.
embodiment 1:
Certain 300MWCFB boiler adopts CFB boiler full-power SNCR high effective flue gas denitration technology reduce NOx emission, specifically takes measures as follows:
1, as shown in Figure 1, reducing agent injection is provided with at cyclone inlet horizontal flue 1, Cyclone outlet 2, secondary air duct 3, furnace wall 4, fluidisation air channel 5, material returning device 6 and external bed 7 place;
2, when spray gun/jet pipe is arranged on secondary air duct 3 or fluidisation air channel 5, ensures that reducing agent mixes with Secondary Air or fluidized wind as far as possible, mixing arrangement can be set and strengthen mixing; Spray gun/jet pipe be arranged on cyclone inlet horizontal flue 1 or/and Cyclone outlet 2 or/and furnace wall 4 or/and external bed 7 time, cyclone separator horizontal flue 1 must be inserted or/and Cyclone outlet 2 is or/and furnace wall 4 is or/and 0.05-0.5m injection in external bed 7, to avoid refractory material in cyclone separator or/and furnace wall cooling pipe is or/and the corrosion of external bed heat-transfer surface;
3, when fire box temperature is more than 850 DEG C, or boiler load higher than 50% time, injection of reducing agent exit point is chosen as: essential cyclone inlet horizontal flue, and optional Cyclone outlet, secondary air duct, furnace wall, fluidisation air channel, material returning device, one or more in external bed; 850 DEG C are less than when fire box temperature is greater than 800 DEG C, or boiler load is when 30-50%, injection of reducing agent exit point is chosen as: essential furnace wall, and optional cyclone inlet horizontal flue, Cyclone outlet, secondary air duct, fluidisation air channel, material returning device, one or more in external bed; When fire box temperature is below 800 DEG C, or boiler load lower than 30% time, injection of reducing agent exit point is chosen as: essential secondary air duct, and optional cyclone inlet horizontal flue, Cyclone outlet, furnace wall, fluidisation air channel, material returning device, one or more in external bed.
Adopt aforementioned schemes, under CFB boiler full load operating condition, CFB-SNCR denitration efficiency all can meet or exceed 85%.When CFB boiler NOx generate concentration reach the level of 400mg/Nm3 time, it still can meet the requirement (GB13223-2011) of NOx emission concentration limit <100mg/Nm3, and even lowlyer reaches below 50mg/Nm3.
comparative example 1:
Fire box temperature 880-900 DEG C, load is at 90-100%, and when injection of reducing agent exit point is arranged in cyclone inlet horizontal flue, its denitration efficiency is 76.4%.
comparative example 2:
Fire box temperature 880-900 DEG C, load is at 90-100%, and when injection of reducing agent exit point is arranged in furnace wall, its denitration efficiency is 71.9%.
comparative example 3:
Fire box temperature 880-900 DEG C, load is at 90-100%, and when injection of reducing agent exit point is arranged in Cyclone outlet, its denitration efficiency is 52.1%.
comparative example 4:
Fire box temperature 880-900 DEG C, load is at 90-100%, and when injection of reducing agent exit point is arranged in material returning device, its denitration efficiency is 33.1%.
comparative example 5:
Fire box temperature 880-900 DEG C, load is at 90-100%, and when injection of reducing agent exit point is arranged in cyclone inlet horizontal flue and furnace wall, its denitration efficiency is 91.8%.
comparative example 6:
Fire box temperature 810-830 DEG C, load is 50%, and when injection of reducing agent exit point is arranged in furnace wall and cyclone inlet horizontal flue, its denitration efficiency is 89.9%.
comparative example 7:
Fire box temperature 760 DEG C, load is 30%, and when injection of reducing agent exit point is arranged in secondary air duct, its denitration efficiency is 67.2%.
comparative example 8:
Fire box temperature 760 DEG C, load is 30%, and when injection of reducing agent exit point is arranged in fluidisation air channel, its denitration efficiency is 36.2%.
comparative example 9:
Fire box temperature 760 DEG C, load 30%, injection of reducing agent exit point be arranged in secondary air duct, cyclone inlet horizontal flue and fluidisation air channel time, its denitration efficiency is 86.5%.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.
Claims (3)
1. for a SNCR denitration method for flue gas for CFBB full load mode, it by injecting reducing agent in flue gas, and in reducing agent and flue gas, NOx reacts and denitration, it is characterized in that comprising:
1) when fire box temperature is more than 850 DEG C, or boiler load higher than 50% time, injection of reducing agent exit point is chosen as: essential cyclone inlet horizontal flue, and optional Cyclone outlet, secondary air duct, furnace wall, fluidisation air channel, material returning device, one or more in external bed;
2) 850 DEG C are less than when fire box temperature is greater than 800 DEG C, or boiler load is when 30-50%, injection of reducing agent exit point is chosen as: essential furnace wall, and optional cyclone inlet horizontal flue, Cyclone outlet, secondary air duct, fluidisation air channel, material returning device, one or more in external bed;
3) when fire box temperature is below 800 DEG C, or boiler load lower than 30% time, injection of reducing agent exit point is chosen as: essential secondary air duct, and optional cyclone inlet horizontal flue, Cyclone outlet, furnace wall, fluidisation air channel, material returning device, one or more in external bed.
2., as claimed in claim 1 for the SNCR denitration method for flue gas of CFBB full load mode, it is characterized in that: when injection of reducing agent exit point comprises secondary air duct, mixing arrangement is set in described secondary air duct.
3., as claimed in claim 1 for the SNCR denitration method for flue gas of CFBB full load mode, it is characterized in that: when injection of reducing agent exit point comprises fluidisation air channel, mixing arrangement is set in described fluidisation air channel.
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Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106051751B (en) * | 2016-06-27 | 2018-04-06 | 东方电气集团东方锅炉股份有限公司 | The CFBB of Collaborative Control pollutant emission |
| CN106268261B (en) * | 2016-10-10 | 2018-12-14 | 福建龙净环保股份有限公司 | A kind of method of SNCR denitrating flue gas |
| CN109058979B (en) * | 2018-08-13 | 2023-11-03 | 中国华能集团有限公司 | Cyclone furnace denitration system and method |
| CN108905568A (en) * | 2018-08-20 | 2018-11-30 | 山东省建设高压容器有限公司 | A kind of circulating fluidized bed boiler flue gas desulfuration and denitrification system and its remodeling method |
| CN109794149B (en) * | 2019-03-20 | 2021-09-21 | 中国华能集团清洁能源技术研究院有限公司 | Automatic control method and system for flue gas denitration of CFB boiler |
| CN110064285B (en) * | 2019-04-12 | 2023-07-14 | 华电电力科学研究院有限公司 | High-temperature-resistant and intensified-mixing high-efficiency SNCR (selective non-catalytic reduction) injection device and working method thereof |
| CN111298643A (en) * | 2020-02-28 | 2020-06-19 | 西安华电清洁能源技术有限公司 | Be applicable to circulating fluidized bed boiler full load denitration control system |
| CN114832589B (en) * | 2022-04-01 | 2023-07-07 | 清华大学山西清洁能源研究院 | SNCR denitration optimal control method of circulating fluidized bed and cyclone separator |
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| EP2522417A1 (en) * | 2011-05-13 | 2012-11-14 | Hitachi Power Europe GmbH | Flue gas conduit jetting device |
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| JP2000279751A (en) * | 1999-03-29 | 2000-10-10 | Electric Power Dev Co Ltd | Method and device for denitrating pressure fluidized bed boiler |
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2013
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| DE3626039A1 (en) * | 1986-08-01 | 1988-02-11 | Hoelter Heinz | NOx reduction by ammonia in a fluidised-bed furnace |
| EP2522417A1 (en) * | 2011-05-13 | 2012-11-14 | Hitachi Power Europe GmbH | Flue gas conduit jetting device |
| CN103252163A (en) * | 2013-04-24 | 2013-08-21 | 浙江富春江环保热电股份有限公司 | Device for removing NOX from smoke by combining ammonia agent spraying and built-in catalytic reaction |
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| Title |
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| 中温条件下烟气De-NOx技术的研究现状与发展;陈慧等;《中国电机工程学报》;20130715;第33卷(第2期);第17-27页 * |
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