CN105889904A - Method for reducing nitrogen oxides of pulverized coal boiler mixed combustion gas fuel - Google Patents

Method for reducing nitrogen oxides of pulverized coal boiler mixed combustion gas fuel Download PDF

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Publication number
CN105889904A
CN105889904A CN201410645422.4A CN201410645422A CN105889904A CN 105889904 A CN105889904 A CN 105889904A CN 201410645422 A CN201410645422 A CN 201410645422A CN 105889904 A CN105889904 A CN 105889904A
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China
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combustion
fuel
zone
reburning
gas
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CN201410645422.4A
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Chinese (zh)
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刘德举
莫春秀
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Chongqing Aogemei Gas Co Ltd
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Chongqing Aogemei Gas Co Ltd
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Abstract

The invention discloses a method for reducing nitrogen oxides of a pulverized coal boiler mixed combustion gas fuel, and relates to the pulverized coal boiler low-NOx combustion technology. The invention solves the problems that in a conventional gas re-combustion technology, re-combustion fuel of a re-combustion zone is consumed too much and formation of a reducing atmosphere in the re-combustion zone is affected because excess oxygen in a main combustion zone enters the re-combustion zone. An air staged combustion technology, a fuel staged combustion technology and a horizontal dense-dilute air combustion technology are combined, and the method comprises the steps: gas fuel is divided into two stages to be introduced to a pulverized fuel combustion chamber, the first-stage gas fuel is introduced to the bottom of a main combustor in the main combustion zone to be used as combustion-supporting fuel, and the fuel is combusted in a low excess-air-coefficient or entire reducing atmosphere while the main combustion zone adopts the horizontal dense-dilute air combustion technology; the second-stage gas fuel is introduced to the top of the main combustion zone, and the re-combustion zone of the reducing atmosphere is formed; and overfire air is introduced to the top of the re-combustion zone, and overfiring is completed. Initial investment and operating costs are moderate, and the method can be applied in new building of boilers and reconstruction of active-service coal-fired boilers.

Description

The method of reducing nitrogen oxide of powder coal boiler mixed burning gas fuel
Technical field
The present invention relates to pulverized-coal fired boiler low nitrogen oxide burning technology.
Background technology
Nitrogen oxides (NOx) is one of Air Pollutants of discharged from coal-fired boiler, and nitrogen oxides is except being formed Acid rain, destroys ecological environment, moreover it is possible to forms photochemical fog, directly endangers human health.At present, nitrogen oxidation Thing has become as the atmosphere pollution being only second to sulfur dioxide in China, to acid rain, air quality and ground level ozone The impact of concentration is increasing.Come into effect new " thermal power plant atmosphere pollution row on January 1st, 2004 Put standard " (GB13223-2003), " discharge standard " is stricter than standard in the past.July 1 in 2004 Play country day to nitrogen oxides by each pollutional equivalent (the blowdown equivalent of nitrogen oxides is 0.95 kilogram) 0.6 yuan Directly to the unit charge discharged pollutants, control coal-fired boiler NOx discharge extremely the most urgent.
The measure controlling NOx emission at present is roughly divided into two classes, and a class is flue-gas denitrification technology, in removing flue gas NOx;Another kind of is low NOx combusting technology, by various technological means, controls combustion process, suppression or The NOx generated in reduction combustion process, reduces the purpose of NOx emission.Flue-gas denitrification technology reduces NOx Amplitude is relatively big, but initial cost and operating cost are higher, and some flue-gas denitrification technology based on amino are it also occur that ammonia Leakage.Low NOx combusting technology mainly includes that low excess air coefficient runs, flue gas recirculation, low NOx Burner Technology, air classification, firing low NOx combusting technology etc. again, low NOx combusting technology cost is relatively low, but General reduction NOx amplitude is less.Generally, low excess air coefficient runs, flue gas recirculation, low NOx combustion The NOx percent reduction of the low NOx combusting technologies such as device technology, air classification is 10%~40%, and fires low NOx again Technology can reach 50%.In reburning technology, reburning fuel is typically chosen reactivity higher natural gas or brown Coal, bituminous coal, the effect fired again with gaseous fuel is better than coal powder recombustion.It is low that gaseous fuel reburning technology compares other NOx combustion technology has some superiority in terms of NOx removal, especially to using anthracite, soft coal Pulverized-coal fired boiler, other low NOx combusting technology controls the reaction condition of NOx generation and ensures that coal dust fully burns Reaction condition contradicts, and reburning technology can ensure that the burning condition that primary zone coal dust is good.But employing gas The oxygen entrance reburning zone that the primary zone of fuel reburning technology is unnecessary can consume more reburning fuel, is unfavorable for firing again The formation of district's reducing atmosphere, adds the share of reburning fuel.
Summary of the invention
Enter reburning zone to solve the unnecessary oxygen in primary zone present in existing gas reburning technology, cause firing again The reburning fuel in district consumes too much and affects reburning zone and forms the problem of reducing atmosphere, the invention provides a kind of coal Powder boiler mixed burning gas fuel reduces the method for nitrogen oxides, concretely comprises the following steps:
Step one: introduce one-level gaseous fuel in the bottom of primary zone burner as combustion-supporting fuel;Improve main combustion The flue-gas temperature in district, makes the coal dust in primary zone stably burn;
Step 2: introduce secondary gas fuel at the top in primary zone, forms reducing atmosphere in reburning zone, makes main CHi, NHi, HCN, CO group that the NOx that combustion district generates is formed by reburning fuel burning through reburning zone is also Former;
Step 3: introduce burnout degree at the top of reburning zone, make the product not having after-flame in reburning zone in reburning zone The burning-out zone on top fully burns.
In the method, using horizontal bias combustion with side air technology in primary zone, the excess air coefficient in primary zone is 0.8-0.9, the excess air coefficient of reburning zone is 0.85-1, and the excess air coefficient of burning-out zone is 1.15-1.2.
The caloric value of the one-level gaseous fuel introduced in step one accounts for the 5%-10 of boiler oil gross calorific power %, the caloric value of the secondary gas fuel introduced in step 2 accounts for the 10%-15 of boiler oil gross calorific power %.
The present invention compares advantageously with existing gas reburning low NOx combusting technology:
One, air staged combustion technology, fuel-staged combustion technology and " horizontal bias wind " combustion technology are tied Close, it is ensured that while coal powder boiler combustion efficiency, NOx emission can be greatly reduced, NOx emission can be reduced 50%~70%.
Two, according to ature of coal situation, primary zone uses overall hypoxia or reducing atmosphere burning, reduces primary zone and enters The oxygen amount of reburning zone, reduces the consumption of reburning fuel, beneficially reburning zone and forms reducing atmosphere, improves combustion more also The efficiency of former NOx.
Three, primary zone uses gaseous fuel combustion-supporting, uses " horizontal bias wind " combustion technology simultaneously, improves coal Catching fire and after-flame of the burning condition of powder, beneficially coal dust, alleviates primary zone in overall hypoxia or reducing gases simultaneously Slagging scorification and high temperature corrosion is there is under atmosphere.
Four, primary zone uses " horizontal bias wind " combustion system, and air classification is sent into, and primary zone is overall in addition Low excess air coefficient burns, and reduces primary zone NOx and generates, the beneficially final NOx abatement of boiler.
Five, the present invention is that main objective for implementation, initial outlay and operating cost are moderate with coal-powder boiler, can apply In newly constructed boiler, it is also applied for the transformation of active service coal-burning boiler unit.
Accompanying drawing explanation
Fig. 1 is the coal-burning boiler structural representation of the method using the present invention.
Detailed description of the invention
Detailed description of the invention one:
The step of the method for the reducing nitrogen oxide of powder coal boiler mixed burning gas fuel of present embodiment is:
Step one: introduce one-level gaseous fuel in the bottom of primary zone main burner as combustion-supporting fuel;Improve main The flue-gas temperature in combustion district, makes the coal dust in primary zone stably burn;
Step 2: introduce secondary gas fuel at the top in primary zone, forms reducing atmosphere in reburning zone, makes main The groups such as CHi, NHi, HCN, CO that the NOx that combustion district generates is formed by reburning fuel burning through reburning zone Reduction;
Step 3: introduce burnout degree at the top of reburning zone, make the product not having after-flame in reburning zone in reburning zone The burning-out zone on top fully burns.
In the present embodiment, horizontal bias combustion with side air technology, the excess air system in primary zone are used in primary zone Number is 0.8-1.1, and the excess air coefficient of reburning zone is 0.85-1, and the excess air coefficient of burning-out zone is 1.15-1.2。
The caloric value of the one-level gaseous fuel introduced in step one accounts for the 5%-10 of boiler oil gross calorific power %, the caloric value of the secondary gas fuel introduced in step 2 accounts for the 10%-15 of boiler oil gross calorific power %.
One-level gaseous fuel described in present embodiment and secondary gas fuel typically use the gas of middle and high calorific value Fluid fuel, such as natural gas, it would however also be possible to employ the production waste gas of enterprise, such as blast furnace gas, coke-stove gas etc.. The combustibility of the gaseous fuel of middle and high calorific value is preferable, and combustion-supporting effect is obvious, can play in primary zone very well Combustion-supporting effect;It addition, the gaseous fuel of middle and high calorific value typically all contains more hydrocarbons, hydro carbons Substance advantageous, in NO reduction by reburning x, is conducive to being formed reducing atmosphere in reburning zone.
For completing the device of the reducing nitrogen oxide of powder coal boiler mixed burning gas fuel of said method, it is existing Pulverized-coal fired boiler device on improve, on the basis of existing pulverized-coal fired boiler, increase the spray of one group of one-level gaseous fuel Mouth 3-1 and secondary gas fuel nozzle 3-2, described one-level gas fuel nozzle 3-1 are fixedly mounted on former main combustion The bottom of burner 1, is used for spraying into one-level gaseous fuel, and described secondary gas burner 3-2 is fixedly mounted on master The combustion top of district A, the top of main burner 1, be used for spraying into secondary gas fuel, and described primary zone uses water Flat bias pulverized coal burner burner (sees the patent documentation of Application No. 96122581: a kind of bias pulverized coal burner fires Burning mode and device).
Gaseous fuel classification is introduced burning in burner hearth, rationalization's stove by present embodiment, integrates multiple low NOx Combustion technology, primary zone use the overall air staged combustion technology of horizontal bias combustion with side air technology bonded boiler and Fuel-staged combustion technology, the final oxide emissions of boiler can reduce nitrogen 60%~70%, higher than using Single low NOx combusting technology reduces the efficiency of NOx.While ensureing boiler combustion efficiency, this embodiment party It is poor that formula can also solve to reduce NOx effect when conventional low NOx combusting technology uses anthracite and soft coal Problem, the gaseous fuel that present embodiment uses should use middle and high value heat fuel, can be natural gas, May also be and utilize enterprise to produce the waste gas produced, such as blast furnace gas, coke-stove gas, or increase equipment for gasification system Standby coal gas or biomass coal gas.
Detailed description of the invention two:
In the method for the reducing nitrogen oxide of powder coal boiler mixed burning gas fuel of present embodiment, use bio-coal Gas introduces burner hearth as multifuel combustion gas, the biomass coal gas accounting for boiler heat 10% in coal burner bottom, Primary zone uses horizontal bias combustion with side air technology, and it is 1.05 that primary zone excess air coefficient controls, and accounts for boiler hot The biomass coal gas of amount 12% introduces burner hearth on coal burner top, and forms the reburning zone of reducing atmosphere, The excess air coefficient of reburning zone is 0.85, at the NOx that the group reduction primary zones such as reburning zone CHi, NHi generate, Burning-out zone excess air coefficient is 1.2.
Detailed description of the invention three: the method for the reducing nitrogen oxide of powder coal boiler mixed burning gas fuel of present embodiment In, use natural gas to draw in coal burner bottom as multifuel combustion gas, the natural gas accounting for boiler heat 10% Entering burner hearth, primary zone uses horizontal bias combustion with side air technology, and it is 0.9 that primary zone excess air coefficient controls, and accounts for The natural gas of boiler heat 10% introduces burner hearth on coal burner top, and forms the reburning zone of reducing atmosphere, The excess air coefficient of reburning zone is 0.85, raw in group reduction primary zones such as reburning zone CHi, HCN, NHi The NOx become, burning-out zone excess air coefficient is 1.2.Heating value of natural gas is preferable, be good reburning fuel and Combustion-supporting fuel, reduces NOx up to 70%.

Claims (4)

1. the method for reducing nitrogen oxide of powder coal boiler mixed burning gas fuel, it is characterised in that the step of described method For:
Step one: introduce one-level gaseous fuel in the bottom of primary zone main burner as combustion-supporting fuel;Improve main The flue-gas temperature in combustion district, makes the coal dust in primary zone stably burn;
Step 2: introduce secondary gas fuel at the top in primary zone, forms reducing atmosphere in reburning zone, makes main CHi, NHi, HCN, CO group that the NOx that combustion district generates is formed by reburning fuel burning through reburning zone is also Former;
Step 3: introduce burnout degree at the top of reburning zone, make the product not having after-flame in reburning zone in reburning zone The burning-out zone on top fully burns;
Described primary zone uses horizontal bias combustion with side air technology;
The excess air coefficient in described primary zone is 0.8-0.9;
The caloric value of the one-level gaseous fuel introduced in step one accounts for the 5%-10 of boiler oil gross calorific power %;The caloric value of the secondary gas fuel introduced in step 2 accounts for the 10%-15% of boiler oil gross calorific power.
The method of reducing nitrogen oxide of powder coal boiler mixed burning gas fuel the most according to claim 1, it is special Levying the excess air coefficient being in described reburning zone is 0.85-1.
The method of reducing nitrogen oxide of powder coal boiler mixed burning gas fuel the most according to claim 1, it is special Levy and be that at the excess air coefficient of described burning-out zone be 1.15-1.2.
The method of reducing nitrogen oxide of powder coal boiler mixed burning gas fuel the most according to claim 1, it is special Levy and be that described one-level gaseous fuel and secondary gas fuel are natural gas, blast furnace gas or coke-stove gas.
CN201410645422.4A 2014-11-02 2014-11-02 Method for reducing nitrogen oxides of pulverized coal boiler mixed combustion gas fuel Pending CN105889904A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106895435A (en) * 2017-02-06 2017-06-27 中国国电集团公司谏壁发电厂 A kind of advanced denitration operation method of 1000MW ultra supercriticals tower-type furnace
CN107270279A (en) * 2017-08-04 2017-10-20 内蒙古岱海发电有限责任公司 The decomposer of nitrogen oxides in a kind of boiler
CN108905590A (en) * 2018-08-13 2018-11-30 中国华能集团有限公司 A kind of denitrating system and method for station boiler low NO collaboration high temperature spray ammonia

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106895435A (en) * 2017-02-06 2017-06-27 中国国电集团公司谏壁发电厂 A kind of advanced denitration operation method of 1000MW ultra supercriticals tower-type furnace
CN107270279A (en) * 2017-08-04 2017-10-20 内蒙古岱海发电有限责任公司 The decomposer of nitrogen oxides in a kind of boiler
CN108905590A (en) * 2018-08-13 2018-11-30 中国华能集团有限公司 A kind of denitrating system and method for station boiler low NO collaboration high temperature spray ammonia
CN108905590B (en) * 2018-08-13 2023-05-12 中国华能集团有限公司 Denitration system and method for low-nitrogen burner of power station boiler in cooperation with high-temperature ammonia injection

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Application publication date: 20160824