CN101201162A - Combustion system and process - Google Patents
Combustion system and process Download PDFInfo
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- CN101201162A CN101201162A CNA2007101942289A CN200710194228A CN101201162A CN 101201162 A CN101201162 A CN 101201162A CN A2007101942289 A CNA2007101942289 A CN A2007101942289A CN 200710194228 A CN200710194228 A CN 200710194228A CN 101201162 A CN101201162 A CN 101201162A
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Abstract
A method and apparatus for reducing NO x emissions in a coal burning furnace of a power plant without utilizing techniques downstream of the furnace, such as SCR and SNCR, is provided. In a primary combustion zone, a fuel is combusted in the presence of a first oxidant gas comprised substantially of N 2 , to produce a first effluent gas that include one or more NO x species. Downstream a re-burn zone is operated in a sub-stoichiometric manner, combusting a second fuel in presence of the first effluent gas and a second oxidant wherein the second oxidant gas comprises a stream of oxygen. The effluent gas from the re-burn zone is introduced to overfire airflow so as to establish a super-stoichiometric zone prior to discharged from the furnace.
Description
The cross reference of related application
The application requires the priority of the U.S. Provisional Patent Application 60/874326 of submission on December 11st, 2006, and the full text of this application is incorporated herein by reference.
Federal government's sponsored research/development statement
The present invention plans under government contract RCD1459.Federal Government Ministry of Energy can keep some right to the present invention.
Technical field
The present invention relates generally to the method and apparatus of burning as the fossil fuel of coal, particularly, relates to minimizing nitric oxide forms in combustion process new effective ways and equipment.
Background technology
The burning of fossil fuel produces nitrogen oxide, as NO and NO
2, be referred to as NO
XIn atmosphere, discharge NO
XBecome the problem of healthy and environmental concern day by day.The fixed NO of U.S. environment protection mechanism (EPA)
XDischarge regulation is necessary, and is suitable, therefore is badly in need of the more effective NO of exploitation
XThe control technology of discharging.
In traditional fossil-fuel-fired device, after mixing, combustion air and fossil fuel deliver to the main combustion zone in the stove.Form the byproduct NO of burning when nitrogen that in fuel, exists naturally and/or the nitrogen molecular oxidation in the combustion air
X
Fuel reburning is a kind ofly can reduce NO
XThe technology of discharging.This technology is included in the combustion zone again that the oxygen deprivation second-time burning is provided on the oxygen enrichment master combustion zone.The postcombustion that is conducted to again the combustion zone produces alkyl, amine and cyanogen class material, and they and the main combustion product reaction of introducing are with NO
XChange into N
2By the fiery windward (overfire air) that is positioned at again combustion zone top (OFA) spout introduce extra air, remaining fuel and fuel gas burn.
The application of fuel reburning utilizes flue gas circulation (FGR) technology to reduce NO usually
XDischarging.Be back to the intermediate zone as the oxygen deprivation carrier gas from the flue gas in boiler downstream through the pipeline circulation,, improve the fuel penetration and mix with the gas and the product of main combustion zone to keep rich fuel environment.Use further is suppressed at combustion zone NO again from the quenching that the flue gas in boiler export downstream causes as carrier gas
XFormation.
The general use of combustion pulverized coal boiler and similar device two kinds or three kinds of gaseous streams.First kind is first order air stream, accounts for about 10-20% of the gas gross of introducing the combustion chamber usually.The main purpose of first order air is that fuel (as fine coal) is sent to burner.Therefore should keep sufficiently high flow velocity to reach the function of particle transmission.Based on this main purpose, transport gas need not contain oxidant, but considers that cost and being easy to get property generally select air for use.
The air stream that second kind of logistics normally injected with burner level (burner level) is approximately or near first order air/fuel mixture.The main purpose of this logistics provides the oxidant of fuel combustion.Because cost and being easy to get property, this logistics generally adopts air.
The 3rd logistics that is generally used for the air segmenting application is injected into the downstream of burner in the intermediate zone.The 3rd logistics is generally injected by auxiliary air (OFA) spout, because cost and being easy to get property, the 3rd logistics is generally air.In air classification is used, use the OFA spout to show NO
XReduced about 20-35%.Usually classification relates to the rich fuel in main combustion zone, with about 0.75 burning to the substoichiometric of about 0.95 scope, and the poor fuel in intermediate zone, the burn operation of hyperstoichiometry (super-stoichiometric) with about 1.10 to about 1.25.
The another kind of NO that reduces
XThe technology top, main combustion zone that is included in common rich oxidant inject air and additional fossil fuel, stoichiometric proportion is at least 1.0, to form the combustion zone again of local oxygen deprivation.Postcombustion produces active material, and they have suppressed NO
XProduce.Generally combustion fuel injection effluent gas temperature is the district of about 1250 ℃ to about 1650 ℃ (about 2300-3000 ) again, shows to reduce NO
XEfficient improve with the rising of implantation temperature with in the prolongation of the combustion zone time of staying more usually.The fuel reburning technology can produce and be up to 60% NO
XReduce, depend on commercial system.Can introduce extra air, after-flame combustible in the side of making, combustion zone again by wind snout on the fire subsequently.
U.S. Patent Application Publication 2006/0257800A1 number (Sarv) has been described the burner that a kind of usefulness burns again and has been reduced NO
XThe method of reactive compound.Fuel is by the burner (oxy-fired burner) and the oxygen combustion of oxygen burning, and described oxygen flame burner is positioned at the rich fuel reburning district in downstream, main combustion zone, and described main combustion zone is oxidizing gas with the air, burns in the mode of poor fuel.
Summary of the invention
In brief, the invention provides a kind of fossil-fuel-fired method and apparatus, wherein, obviously reduced combustion by-products NO
X, and can eliminate needs potentially to downstream technology such as SCR and SNCR.
One aspect of the present invention provides a kind of method that nitrogen oxide forms that reduces, and described nitrogen oxide is fossil fuel burning and exhaustings in nitrogenous gas.Said method comprising the steps of: the stove that burning mineral fuel is provided, (air fired) burner of many emptyings gas firing is provided, the one oxygen flame combustion burner again that comes described last row's of air flame burner downstream is provided, provide one to come described oxygen flame wind snout (overfire air port) on the fire in combustion burner downstream again, provide stoichiometric proportion less than 1.0 air and fossil fuel to many emptyings bluster burner, combustion burner again to the oxygen burning provides fossil fuel and gaseous stream, described gaseous stream comprises at least 90% oxygen, present in an amount at least sufficient to produce the ratio of combustion stoichiometry again of about 0.35-0.65, and wind snout provides the air of capacity on this row's fire, produces combustion stoichiometry ratio greater than 1.10 with the downstream of wind snout on fire.
The present invention provides a kind of combustion furnace on the other hand, described combustion furnace comprises the fossil-fuel-fired device of a plurality of air burnings that are arranged at least two rows, and the improvements of described combustion furnace comprise the burner that substitutes the air burning of going up row most with a combustion burner again of arranging the oxygen burning.
One side more of the present invention provides a kind of method of controlling discharged nitrous oxides, and described nitrogen oxide produces discharging because of fossil fuel burn in utility boiler.Described method comprises in the following manner to stop the sectional combustion step that forms nitroxide precursors: the burner that at least two emptying gas firings are provided, each burner air supply and fossil fuel, and with less than the burning of 1.0 stoichiometric number, and wind snout on row's fire is placed in the downstream of last row in the burner of at least two emptying gas firings; Wherein, wind snout provides the air of capacity on the described fire, produces to be higher than 1.10 combustion stoichiometry value; The improvements of described method are included in the downstream of burner of air burning and the combustion burner again that upstream that fire is gone up wind snout provides the oxygen burning, combustion burner again to the oxygen burning provides fossil fuel and the steam flow that comprises at least 90% oxygen, operate the combustion burner again of this oxygen burning, produce about 0.35 to 1.0 combustion stoichiometry value in its exit.
The various features that characterize novelty of the present invention are specifically noted in the claim of the part of appended formation content of the present invention.For a better understanding of the present invention, advantage of the present invention and use beneficial effect of the present invention can be with reference to the accompanying drawings and description of the preferred embodiment of the present invention.
Brief Description Of Drawings
Fig. 1 is the perspective view of an embodiment of stove of the present invention, and wherein all burners all are positioned on the wall of this device.
Fig. 2 is the perspective view of another embodiment of stove of the present invention, and wherein burner is positioned on the relative wall of this device.
Fig. 3 is the perspective view of the another embodiment of stove of the present invention, and wherein all burners are located in the tangential firing mode.
Fig. 4 is the single wall side view after the part of cutting of stove of the present invention single wall embodiment during operation.
Similarly Reference numeral is represented similar elements herein.
The specific embodiment
System and method of the present invention relates to the air segmenting furnace apparatus of burnable solid fuel.Fig. 1-3 shows three kinds of general relatively solid fuel furnace structures, and they can be applied to the present invention separately.Especially, Fig. 1 is the schematic of single wall burner 10, and Fig. 2 shows the signal representative of relative wall burner 20, and Fig. 3 shows tangentially the signal representative of (or angle burning) device 30.These embodiments various antetheca 11 that includes, rear wall 13 and sidewall 15 and 17.Tangential unit 30 also comprises four jiaos of walls 19.
In each design, first-stage burning device 12 is drawn together in the upstream of spout (bottom) package, promptly is configured at oxidant gas, as contains high relatively percentage N
2Air have the burner of combustion fuel down, and the combustion burner again 14 of the oxidant gas that uses oxygen enrichment is drawn together in the package in spout downstream.Term " row " is used to refer to the imaginary line that connects a series of similar burners in the text.Though the height of single burner can change in actual use, should understand small variation still within protection scope of the present invention.
OFA spout 16 generally is positioned at the downstream of combustion burner 14 again.After body of heater was Once you begin exported, flue gas 18 was directed to outside the stove through the windward spout 16 that overdoes.Though the present invention can remove unnecessary NO
X, needn't the employing additional treatment step relevant just can reach existing NO with SCR and SNCR
XThe emission regulation level is if still the limit trading system is to NO
XMore regulation is set up in discharging, and it may be useful using this subsequent handling to confirm.
Describe the operation of method of the present invention and furnace system referring to Fig. 4, the figure shows the another kind of structure of single wall burner.In this manual, use fine coal (PC) as exemplary solid fuel, though do not think and be limited to this, those of ordinary skills can recognize the multiple solid fuel that can burn in this device.
The mixture of fine coal and oxidant gas first pipeline 32 of flowing through is supplied with furnace apparatus 50, enter the first-stage burning device 12 that is positioned at upstream spout 22.Feed stream is generally sufficiently high speed and feeds, to carry fine coal.The oxidant gas of feed stream is generally air, generally comprises a large amount of N
2, be generally 70%.This feed stream burning formation first combustion zone 42.Described combustion zone 42 forms rich fuel environment usually, that is, stoichiometric proportion is preferably about zone of 0.8 to 1.0 less than 1.0.In another embodiment, the stoichiometric number of first combustion zone 42 can be higher than 1.0, and is up to 1.10.
Second mixture of fine coal and oxidant gas, second pipeline, 34 feedwaies 50 of flowing through, and enter the combustion burner again 14 that is positioned at downstream spout 24.Feed stream generally feeds with sufficiently high speed, to carry fine coal.N in the oxidant gas of this logistics
2Concentration reduce usually, preferably less than 50%, concentration reduce be will circulation flue gas and the result of relative purer oxygen logistics mixing, at the particularly preferred N that do not contain substantially
2Embodiment in, use the logistics of pure relatively oxygen.
Oxidant gas is a high-purity O
2The time, available mode as pressing plate (spud) or spray gun (lance) is carried; Referring to for example, U.S. Patent Application Publication has been described a kind of multiple-blade injection apparatus of oxygen being introduced again combustion burner 14 for 2006/0257800A1 number.
Feed stream burning, near second combustion zone 44 of the partial flame temperature that formation raises combustion burner again.In certain embodiments, second feed stream can comprise O
2And/or the flue gas of recirculation.Pipeline can be installed in steam generator system Anywhere so that the flue gas of aequum is recycled to device 50.The flue gas of recirculation can with the oxygen premixed, or directly inject second combustion zone 44.
Stoichiometry ratio in Ran Shao the burner 14 generally depends on the composition of oxidant gas and the flow velocity of feed stream again.Combustion burner 14 is preferably operated under rich fuel condition again, makes stoichiometry ratio be lower than 1.0, is preferably about 0.35 to 0.85.For high-end combustion burner again, non-oxidized gas wherein is as N
2, H
2O and CO
2Flue gas stream through transmission air and/or one or many circulation is introduced combustion burner 14 again, and its stoichiometric number is preferably 0.65 to 0.85.And, observing the introducing amount minimum of non-oxidized gas to the combustion burner again of low side, its stoichiometric number is preferably about 0.35 to 0.65.In all cases, the stoichiometric number in the combustion burner 14 should remain on and be equal to or less than the stoichiometric number that adopts in the combustion burner again of the air burning of equivalence again.In such system, the combustion zone at utmost reduces NO because of the stoichiometry ratio of first-stage burning device 12 and the merging of combustion burner 14 generations again is preferably maintained in the range of from about 06. to 1.0 to reach
X
Because high temperature and high oxygen concentration in second combustion zone, produce the flame free radical (flame radical) of high local concentrations, its most of can and NO
XMaterial reacts.
Other oxidizing gas passes through pipeline 26 accesss to plant, and introduces the downstream of intermediate zones 44 by OFA spout 16.Though oxidizing gas is formed obvious variation can be arranged, consider being easy to get property and cost, adopt air usually.The oxidizing gas of introducing through OFA spout 16 will install 50 integral combustion stoichiometric number and bring up at least about 1.10, and this helps the combustibles that burnout, as charcoal, and hydro carbons and CO.It is about 980 ℃ to about 1550 ℃ (about 1800-2800 ) parts that OFA spout 16 generally is positioned at effluent gas temperature, to be easy to reach completing combustion.
In another embodiment of the present invention, existing stove is improved, make it to have said structure.In other words, convert O to by existing burner with downstream row
2The combustion burner again of burning just needn't be installed new or other burner nozzle on the existing combustion furnace.Like this, Fig. 1 both can be regarded as the device of coming of new to device shown in Figure 4, also can be considered as having carried out the device that improved prior art is made.
The advantage of system and method for the present invention is from different in the technology of main combustion zone whole process using oxygen, No matter the application of restriction oxygen can reduce oxygen in conduct in the again combustion burner of the degree of depth segmentation of combustion zone Overall consumption during the enriched composition of pure gas or other gas. More particularly, combustion burner is required again The mass air flow rate that total oxygen gas flow rate is equivalent to substitute 23% or littler.
Unless there is opposite implication to represent, all percentage is meant percent by volume in the full text.All patents that more than relate to and patent disclosure all are incorporated herein by reference.
Claims (13)
1. a combustion furnace comprises a plurality of fossil-fuel-fired devices that are arranged in two rows' air burning at least, and the improvements of described combustion furnace comprise with the replacement of combustion burner again of deoxygenation burning goes up the burner of row's air burning most.
2. combustion furnace as claimed in claim 1 is characterized in that, described burner is positioned on the single wall of described combustion furnace, and wind snout is positioned at the top of combustion burner again of described oxygen burning on the fire.
3. combustion furnace as claimed in claim 1 is characterized in that, described burner is positioned on the relative wall of described combustion furnace, and wind snout is positioned at the top of combustion burner again of described oxygen burning on the fire.
4. combustion furnace as claimed in claim 1 is characterized in that described burner is arranged to the tangential firing pattern, and wind snout is positioned at described oxygen flame combustion burner top again on the fire.
5. one kind is reduced fossil fuel and burns in nitrogenous gas and form the method for nitrogen oxide, and this method comprises:
The stove of burning mineral fuel is provided,
The burner of a row or multi-row air burning is provided,
The again combustion burner of one ranking in the oxygen burning in the burner downstream of air burning is provided,
One ranking wind snout on the fire in the row of the combustion burner again downstream of described oxygen burning is provided,
To the burner supplying chemical variable of described a row or multi-row air burning less than 1.0 air and fossil fuel
To the supply fossil fuel of combustion burner again of described oxygen burning with comprise the gaseous stream of at least 90% oxygen, described gaseous stream amount be enough to produce about 0.35 to 0.65 the value of combustion stoichiometry again and
Go up the air that wind snout is supplied capacity to described row's fire, be higher than 1.10 combustion stoichiometry value with the generation of wind snout downstream on fire.
6. method as claimed in claim 5, this method also comprises the step with single wall fuel element operation combustion furnace, the combustion burner again of the burner of wherein said air burning and oxygen burning is positioned on the single wall of described combustion furnace, and wind snout is positioned at the top of combustion burner again of described oxygen burning on the fire.
7. method as claimed in claim 5, this method also comprises the step with relative wall fuel element operation combustion furnace, the combustion burner again of the burner of wherein said air burning and oxygen burning is positioned on a plurality of walls of described combustion furnace, and wind snout is positioned at the top of combustion burner again of described oxygen burning on the fire.
8. method as claimed in claim 5, this method also comprises the step with tangential firing unit operations combustion furnace, the combustion burner again of the burner of wherein said air burning and oxygen burning is set to the tangential firing pattern, and wind snout is positioned at the top of combustion burner again of described oxygen burning on the fire.
9. method that is controlled at the discharged nitrous oxides that burning mineral fuel produced in the utility boiler, this method comprises in the following manner to stop the sectional combustion step that forms nitroxide precursors: the burner that at least two emptying gas firings are provided, each burner air supply and fossil fuel, described burner burns with the stoichiometric number less than 1.0, and last row's downstream provides wind snout on row's fire in the burner of at least two emptying gas firings; Wherein, wind snout provides the air of capacity to be higher than 1.10 combustion stoichiometry value with generation on the described fire, the improvements of this method are included in the downstream of burner of air burning and the combustion burner again that upstream that fire is gone up wind snout provides the oxygen burning, supply with fossil fuel and the gaseous stream that comprises at least 90% oxygen to the combustion burner again of this oxygen burning, operate the combustion burner again of this oxygen burning, produce about 0.35 to 0.85 combustion stoichiometry value in the outlet of this burner.
10. method as claimed in claim 9 is characterized in that, operates the combustion burner again of described oxygen burning, and the combustion stoichiometry value in its exit is about 0.35 to 0.65.
11. method as claimed in claim 10, this method also comprises the step of operating described combustion furnace with the single wall fuel element, and wherein, the combustion burner again of the burner of described air burning and oxygen burning is positioned on the single wall of described combustion furnace.
12. method as claimed in claim 10, this method also comprises the step of operating described combustion furnace with relative wall fuel element, and wherein, the combustion burner again of the burner of described air burning and oxygen burning is positioned on a plurality of walls of described combustion furnace.
13. method as claimed in claim 10, this method also comprises the step with the described combustion furnace of tangential firing unit operations, and wherein, the combustion burner again of the burner of described air burning and oxygen burning is arranged to the tangential firing pattern.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US87432606P | 2006-12-11 | 2006-12-11 | |
| US60/874,326 | 2006-12-11 | ||
| US11/940,575 | 2007-11-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101201162A true CN101201162A (en) | 2008-06-18 |
Family
ID=39516451
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA2007101942289A Pending CN101201162A (en) | 2006-12-11 | 2007-12-10 | Combustion system and process |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN101201162A (en) |
| ZA (1) | ZA200710051B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103697464A (en) * | 2012-09-28 | 2014-04-02 | 烟台龙源电力技术股份有限公司 | Intermediate silo-type pulverizing boiler |
| CN109563986A (en) * | 2016-07-01 | 2019-04-02 | 芬兰国家技术研究中心股份公司 | Combustion exhausted wind apparatus and method |
-
2007
- 2007-11-21 ZA ZA200710051A patent/ZA200710051B/en unknown
- 2007-12-10 CN CNA2007101942289A patent/CN101201162A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103697464A (en) * | 2012-09-28 | 2014-04-02 | 烟台龙源电力技术股份有限公司 | Intermediate silo-type pulverizing boiler |
| CN103697464B (en) * | 2012-09-28 | 2016-10-05 | 烟台龙源电力技术股份有限公司 | Warehouse formula powder process boiler in the middle of a kind of |
| CN109563986A (en) * | 2016-07-01 | 2019-04-02 | 芬兰国家技术研究中心股份公司 | Combustion exhausted wind apparatus and method |
Also Published As
| Publication number | Publication date |
|---|---|
| ZA200710051B (en) | 2008-10-29 |
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Open date: 20080618 |