CN103752160B - Realize the method for CFBB ultra-low emission of NOx - Google Patents
Realize the method for CFBB ultra-low emission of NOx Download PDFInfo
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- CN103752160B CN103752160B CN201410040857.6A CN201410040857A CN103752160B CN 103752160 B CN103752160 B CN 103752160B CN 201410040857 A CN201410040857 A CN 201410040857A CN 103752160 B CN103752160 B CN 103752160B
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Abstract
A kind of method realizing CFBB ultra-low emission of NOx of SNCR technical field, there is SNCR by the NOx sprayed in CFBB in ammoniacal liquor and hydrogen and recirculating fluidized bed flue gas to react, to realize the minimum discharge of CFBB NOx.The present invention can meet up-to-date discharge standard 100mg/Nm
3limit value, and solve the too high problem of reaction temperature that SNCR denitration technology exists in CFBB application, make recirculating fluidized bed cigarette temperature and SNCR denitration temperature window have the matching degree of broadness.
Description
Technical field
What the present invention relates to is a kind of method of SNCR technical field, specifically a kind ofly realizes the method that denitration efficiency reaches the CFBB ultra-low emission of NOx of 70%;
Background technology
The atmosphere pollutants emission standards (GB13223-2011) of latest edition goes into effect on January 1st, 2012, and newly-built fired power generating unit needs strict implement 100mg/Nm
3emission limits of nitrogen oxides, and existing fired power generating unit also will start to perform on July 1st, 2014 this discharge standard; Recirculating fluidized bed (CFB) boiler, low stain, clean-burning technology efficient as one, at home and abroad in power industry by extensive concern with fast-developing; CFB boiler adopt be low-temperature burning technology, relative coal-powder boiler, CFB boiler is low-temperature burning, and the existing low-NO_x combustion technology of CFB boiler can make its NOx discharge very low, generally can be controlled in 200 ?300mg/Nm
3, also well below the NOx discharge of coal-powder boiler; Before 2012, the NOx discharge that CFB boiler normally runs can meet original standard (GB13223 ?2003), eliminates the installation of equipment for denitrifying flue gas, operating cost, and this also show the environmental protection characteristic of CFB boiler on the one hand; But along with the execution of up-to-date discharge standard (GB13223 ?2011), the environment-friendly advantage of existing CFB boiler has been cannot meet will control at 100mg/Nm NOx emission
3following strict demand, so it is extremely urgent for seeking a kind of method realizing CFBB ultra-low emission of NOx;
Comprehensively analyze from aspects such as technique, economy, performance, benefit and practice situations, industry generally believes that CFB boiler adopts the denitration of SNCR (SNCR) technology to be the NOx in CFB boiler smoke can be controlled at 100mg/Nm by final concentration of emission
3below, realize the minimum discharge of CFB boiler NOx, meanwhile, technique is simple, and Transformation of Unit is few, invests little, meets China's fundamental realities of the country;
SNCR gas denitrifying technology (SNCR) refers in suitable temperature range (850 ?1100 DEG C), under not having catalyst action, NOx is optionally reduced to N by reducing agent (urea, ammoniacal liquor, liquefied ammonia etc.)
2and H
2o; SNCR course of reaction is very responsive to temperature conditions, and suitable reaction temperature is the key ensureing that SNCR denitration efficiency is high; Because CFB boiler is low-temperature burning, run bed temperature 800 ?about 950 DEG C, so CFB boiler furnace outlet smoke temperature is lower relative to coal-powder boiler, for guaranteeing higher denitrification percent, SNCR conversion zone cigarette temperature must can have good matching degree with SNCR temperature window, therefore need manage temperature window to be expanded to low temperature direction or moves, make the flue-gas temperature of boiler hearth of circulating fluidized bed outlet or separator import and export section can be near best denitration temperature;
200810102373.4 disclose a kind of method promoting selective non-catalytic reduction of nitrogen oxides, are for additive is to promote selective non-catalytic reduction of nitrogen oxides with microfine coal, natural gas or synthesis gas; It is that additive is to promote selective non-catalytic reduction of nitrogen oxides with biomass gasified gas that Chinese patent application 200810209608.X discloses a kind of; Two above patents, all mainly for coal-powder boiler, are not carry out denitrogenation for this distinctive clean burning type of furnace of CFBB, and the technique of adding coal dust, gasification gas or natural gas is also comparatively complicated;
Through finding the retrieval of prior art, Chinese patent literature CN101422689, publication date 2009.05.06, disclose a kind of method of denitration of storing and reducing nitrogen oxides in circulating fluid bed flue gas, comprise the steps: a. by flue gas through accelerate or directly spray into catalyst after pressurization be bed material fluid bed depot reaction device in, the oxidation and absorbing realizing NOx while band movable bed stream moves stores; B. the gas-solid separator by being arranged on depot reaction device afterbody realizes gas-solid and is separated, and gas phase can directly be discharged or enter subordinate's NOx purification system and be purified, and solid-phase catalyst enters fluid bed reduction regeneration reactor; C. the catalyst storing NOx contacts with reducing agent in fluid bed reduction regeneration reactor, the NOx that reduction is stored, and realizes catalyst regeneration; D. the catalyst after regeneration is introduced fluid bed depot reaction device; But this technology must adopt transition metal composite oxide catalytic agent, and the storage of NOx and reduction need to carry out respectively in two different fluidized-bed reactors, both operating temperature, atmosphere, gas flow rate etc. have strict demand, make this technology and are not suitable for being generalized in actual industrial;
Summary of the invention
The present invention is directed to prior art above shortcomings, a kind of method realizing CFBB ultra-low emission of NOx of simple and feasible is proposed, without the need to adding any type catalyst, also without the need to considering regeneration and the renewal of catalyst, only that reducing agent (urea, ammoniacal liquor, liquefied ammonia etc.) is directly sprayed in fluidized bed smoke, just can realize the reduction of NOx, operationally possess flexibility, investment and maintenance cost also lower; The present invention can meet up-to-date discharge standard 100mg/Nm
3limit value, and solve the too high problem of reaction temperature that SNCR denitration technology exists in CFBB application, make recirculating fluidized bed cigarette temperature and SNCR denitration temperature window have the matching degree of broadness;
The present invention is achieved by the following technical solutions, and the present invention by the NOx sprayed in CFBB in ammoniacal liquor and hydrogen and recirculating fluidized bed flue gas, SNCR occurs and reacts, to realize the minimum discharge of CFBB NOx;
Described spraying into specifically refers to: spray into the ammonia spirit as reducing agent and the hydrogen as additive in boiler hearth of circulating fluidized bed exit position section, utilize ammoniacal liquor and H
2the ultimate density that coordinative role realizes CFBB NOx meets 100mg/Nm
3limit value; Preferably, the reducing agent sprayed into and the consumption of additive and temperature match;
Described temperature refers to: reaction temperature be 700 ?1000 DEG C;
Described consumption is specially: the amount of ammoniacal liquor is with the NH in ammoniacal liquor
3represent with the mol ratio of NOx in flue gas, be preferably 1.5 ?2; The amount of hydrogen with the mol ratio of NOx in hydrogen and flue gas be 1 ?3;
The mist of described flue gas and ammoniacal liquor and hydrogen was determined by flue gas flow rate and flue size in the time of staying of conversion zone:
wherein: τ is the time of staying, s; L is the longitudinal length of the conversion zone counted from eject position, namely along flue gas
Flow direction, unit is m; U is the flow velocity of flue gas, and unit is m/s;
The described time of staying is preferably more than 0.6s;
The amount of hydrogen represents with the mol ratio of NOx in hydrogen and flue gas, is specially:
1) reaction zone cigarette temperature 825 ?925 DEG C time, H
2the preferred ratio of/NOx mol ratio gets 1;
2) reaction zone cigarette temperature 760 ?890 DEG C time, H
2the preferred ratio of/NOx mol ratio gets 2;
3) reaction zone cigarette temperature 700 ?800 DEG C time, H
2the preferred ratio of/NOx mol ratio gets 3;
Technique effect
Compared with prior art, the invention has the advantages that:
1. under this overall background of environmental protection new national standard execution, propose a kind of method realizing its ultra-low emission of NOx for this clean burning type of furnace of CFBB, and technique simply, is easily implemented, be beneficial to commercial introduction application
2. the specific embodiments of CFBB SNCR denitration technique and preferred operating mode is clearly given
3. additive H
2add, cause denitration temperature window to move to low temperature direction, solve the problem that SNCR denitration technology reaction temperature existing in CFBB application is too high, make recirculating fluidized bed cigarette temperature and SNCR denitration temperature window have the matching degree of broadness;
Accompanying drawing explanation
Fig. 1 is the invention process environmental structure schematic diagram;
Fig. 2 is comparative example effect schematic diagram;
Fig. 3 is embodiment 2 effect schematic diagram;
Fig. 4 is embodiment 3 effect schematic diagram;
Fig. 5 is embodiment 4 effect schematic diagram;
In figure: 1 burner hearth, 2 air compartments, 3 upper furnace (containing curtain wall), 4 cyclone inlet flues, 5 cyclone separator cylindrical shells, 6 cyclone separator cone sections, 7 cyclone separator standpipes, 8 material returning devices, 9 refeed lines, 10 central cylinder of separators, 11 separator outlet flues, 12 separator outlet flue reversal chambers, 13 back-end surfaces, 14 back-end ductwork cones, 15 back-end ductwork horizontal segments, 16 additives gas H
2the eject position of conveyance conduit, 17 reducing agents (ammoniacal liquor) solution line, 18 ammonia water spray gun, 19 reducing agents and additive;
Detailed description of the invention
Elaborate to embodiments of the invention below, the present embodiment is implemented under premised on technical solution of the present invention, give detailed embodiment and concrete operating process, but protection scope of the present invention is not limited to following embodiment;
Embodiment 1
As shown in Figure 1, the present embodiment implementation environment comprises: burner hearth, air compartment, cyclone separator, material-returning device and back-end ductwork; CFBB due to himself characteristic, its NOx initial concentration generally can be controlled in 200 ?300mg/Nm
3, higher in up-to-date concentration limit 100mg/Nm
3; The spray gun of reducing agent is arranged in the internal face of furnace outlet flue, entrance temperature be 700 ?1000 DEG C; Nitrogen reductant adopts solution form, selection to be mass fraction be 10% ammoniacal liquor, additives gas H
2being carried by ammoniacal liquor is injected in high-temperature flue gas through same entrance, reduces the NOx concentration in flue gas with ammoniacal liquor coordinative role, and additive H
2reasonable addition to determine according to the cigarette temperature of entrance and reaction zone, to ensure that recirculating fluidized bed cigarette temperature can be mated preferably with SNCR denitration temperature window
Fig. 2 is that CFBB does not add any H
2sNCR denitration characteristic curve; Experiment condition is: the initial NO concentration of flue gas is 268mg/Nm
3, oxygen concentration is 6%, NH
3/ NOx mol ratio is 1.5, and the time of staying is 0.6s; The experiment value of the best denitration temperature of ammoniacal liquor is 920 DEG C (corresponding simulation value is 930), now the best denitration efficiency of gained can reach about 70%, ensure the reaction temperature window of denitration rate more than 50% be 910 ?980 DEG C, window width is 70 DEG C;
Embodiment 2
Fig. 3 is that CFBB adds quantitative H
2(H
2/ NH
3mol ratio is taken as 1) SNCR denitration characteristic curve; Experiment condition is: the initial NO concentration of flue gas is 268mg/Nm
3, oxygen concentration is 6%, NH
3/ NOx mol ratio is 1.5, H
2/ NH
3mol ratio is 1, and the time of staying is 0.6s; The experiment value of the best denitration temperature of ammoniacal liquor is 870 DEG C (corresponding simulation value is 820 DEG C), best denitration efficiency is 64%, now ensure the reaction temperature window of denitration rate more than 50% be 825 ?925 DEG C, window width is 100 DEG C, and caused best denitration temperature is 50 DEG C to the side-play amount in low temperature direction;
Embodiment 3
Fig. 4 is that CFBB adds quantitative H
2(H
2/ NH
3mol ratio is taken as 2) SNCR denitration characteristic curve; Experiment condition is: the initial NO concentration of flue gas is 268mg/Nm
3, oxygen concentration is 6%, NH
3/ NOx mol ratio is 1.5, H
2/ NH
3mol ratio is 2, and the time of staying is 0.6s; The experiment value of the best denitration temperature of ammoniacal liquor is 820 DEG C (corresponding simulation value is 785 DEG C), best denitration efficiency is 62%, now ensure the reaction temperature window of denitration rate more than 50% be 760 ?890 DEG C, window width is 130 DEG C, and caused best denitration temperature is 100 DEG C to the side-play amount in low temperature direction;
Embodiment 4
Fig. 5 is that CFBB adds quantitative H
2(H
2/ NH
3mol ratio is taken as 3) SNCR denitration characteristic curve; Experiment condition is: the initial NO concentration of flue gas is 268mg/Nm
3, oxygen concentration is 6%, NH
3/ NOx mol ratio is 1.5, H
2/ NH
3mol ratio is 3, and the time of staying is 0.6s; The experiment value of the best denitration temperature of ammoniacal liquor is 750 DEG C (corresponding simulation value is 760 DEG C), best denitration efficiency is 58%, now ensure the reaction temperature window of denitration rate more than 50% be 700 ?800 DEG C, window width is 100 DEG C, and caused best denitration temperature is 170 DEG C to the side-play amount in low temperature direction.
Claims (1)
1. one kind realizes the method for CFBB ultra-low emission of NOx, it is characterized in that, there is SNCR by the NOx sprayed in CFBB in ammoniacal liquor and hydrogen and recirculating fluidized bed flue gas to react, to realize the minimum discharge of CFBB NOx;
Described spraying into specifically refers to: spray into the ammonia spirit as reducing agent and the hydrogen as additive in boiler hearth of circulating fluidized bed exit position section, and the reducing agent sprayed into and the consumption of additive and temperature match;
Described temperature refers to: reaction temperature is 700-925 DEG C, and consumption is specially: the amount of ammoniacal liquor is with the NH in ammoniacal liquor
3be 1.5-2 with the mol ratio of NOx in flue gas; The amount of hydrogen with the mol ratio of NOx in hydrogen and flue gas is: when reaction zone cigarette temperature [700 DEG C, 760 DEG C) time, H
2/ NOx mol ratio is 3; When reaction zone cigarette temperature [760 DEG C, 825 DEG C) time, H
2/ NOx mol ratio is 2; When the cigarette temperature of reaction zone is when [825 DEG C, 925 DEG C], H
2/ NOx mol ratio is 1;
The mist of described flue gas and ammoniacal liquor and hydrogen was determined by flue gas flow rate and flue size in the time of staying of conversion zone:
wherein: τ is the time of staying, s; L is the longitudinal length of the conversion zone counted from eject position, and namely along flow of flue gas direction, unit is m; U is the flow velocity of flue gas, and unit is m/s;
The described time of staying is more than 0.6s.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114377533A (en) * | 2015-03-26 | 2022-04-22 | 康宁股份有限公司 | For selective non-catalytic NOxReduction method and system |
| CN106139871B (en) * | 2015-04-13 | 2019-10-11 | 北京美斯顿科技开发有限公司 | A kind of improved CO incinerator SNCR denitration device and its method of denitration |
| CN110327754A (en) * | 2019-07-26 | 2019-10-15 | 启明星宇节能科技股份有限公司 | A kind of tunnel stove denitrating system |
| CN111097268A (en) * | 2020-01-08 | 2020-05-05 | 上海交通大学 | Composite laminated reducing agent high-speed injection device |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1646209A (en) * | 2002-04-09 | 2005-07-27 | 犹德有限公司 | Denitrification method |
| CN1691977A (en) * | 2002-06-05 | 2005-11-02 | 埃克森美孚研究工程公司 | Selective non-catalytic reduction of nox |
| CN102626588A (en) * | 2012-04-12 | 2012-08-08 | 浙江天蓝环保技术股份有限公司 | SNCR (Selective Non Catalytic Reduction) denitrification process and device for flue gas purification of circulating fluidized bed (CFB) |
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2014
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1646209A (en) * | 2002-04-09 | 2005-07-27 | 犹德有限公司 | Denitrification method |
| CN1691977A (en) * | 2002-06-05 | 2005-11-02 | 埃克森美孚研究工程公司 | Selective non-catalytic reduction of nox |
| CN102626588A (en) * | 2012-04-12 | 2012-08-08 | 浙江天蓝环保技术股份有限公司 | SNCR (Selective Non Catalytic Reduction) denitrification process and device for flue gas purification of circulating fluidized bed (CFB) |
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Granted publication date: 20160316 Termination date: 20190128 |