CN107339691A - A kind of combustion system of circulating fluidized bed boiler and burning process - Google Patents
A kind of combustion system of circulating fluidized bed boiler and burning process Download PDFInfo
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- CN107339691A CN107339691A CN201710469608.2A CN201710469608A CN107339691A CN 107339691 A CN107339691 A CN 107339691A CN 201710469608 A CN201710469608 A CN 201710469608A CN 107339691 A CN107339691 A CN 107339691A
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- flue gas
- reducing agent
- secondary air
- circulating flue
- circulating
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- 238000002485 combustion reaction Methods 0.000 title claims abstract description 47
- 238000000034 method Methods 0.000 title claims abstract description 23
- 230000008569 process Effects 0.000 title claims abstract description 16
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 162
- 239000003546 flue gas Substances 0.000 claims abstract description 162
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 102
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 47
- 229910021529 ammonia Inorganic materials 0.000 claims description 21
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 20
- 239000001301 oxygen Substances 0.000 claims description 20
- 229910052760 oxygen Inorganic materials 0.000 claims description 20
- 238000002347 injection Methods 0.000 claims description 19
- 239000007924 injection Substances 0.000 claims description 19
- 239000007789 gas Substances 0.000 claims description 18
- 238000003860 storage Methods 0.000 claims description 8
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 6
- 239000004202 carbamide Substances 0.000 claims description 6
- 239000012530 fluid Substances 0.000 claims description 6
- 239000000446 fuel Substances 0.000 claims description 6
- 230000008676 import Effects 0.000 claims description 6
- 239000007921 spray Substances 0.000 claims description 6
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 4
- 238000011084 recovery Methods 0.000 claims description 4
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 3
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 3
- 239000003795 chemical substances by application Substances 0.000 claims description 2
- 230000001939 inductive effect Effects 0.000 claims 1
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 abstract description 68
- 230000003134 recirculating effect Effects 0.000 abstract description 8
- 230000001737 promoting effect Effects 0.000 abstract description 5
- 230000009467 reduction Effects 0.000 abstract description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 12
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 11
- 238000006722 reduction reaction Methods 0.000 description 10
- 238000005516 engineering process Methods 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 7
- 238000005243 fluidization Methods 0.000 description 6
- 229910052757 nitrogen Inorganic materials 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 150000003254 radicals Chemical class 0.000 description 5
- GQPLMRYTRLFLPF-UHFFFAOYSA-N Nitrous Oxide Chemical compound [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 description 4
- 235000019504 cigarettes Nutrition 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 230000000977 initiatory effect Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000000779 smoke Substances 0.000 description 2
- 230000008901 benefit Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000003500 flue dust Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- DOTMOQHOJINYBL-UHFFFAOYSA-N molecular nitrogen;molecular oxygen Chemical compound N#N.O=O DOTMOQHOJINYBL-UHFFFAOYSA-N 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C10/00—Fluidised bed combustion apparatus
- F23C10/02—Fluidised bed combustion apparatus with means specially adapted for achieving or promoting a circulating movement of particles within the bed or for a recirculation of particles entrained from the bed
- F23C10/04—Fluidised bed combustion apparatus with means specially adapted for achieving or promoting a circulating movement of particles within the bed or for a recirculation of particles entrained from the bed the particles being circulated to a section, e.g. a heat-exchange section or a return duct, at least partially shielded from the combustion zone, before being reintroduced into the combustion zone
- F23C10/08—Fluidised bed combustion apparatus with means specially adapted for achieving or promoting a circulating movement of particles within the bed or for a recirculation of particles entrained from the bed the particles being circulated to a section, e.g. a heat-exchange section or a return duct, at least partially shielded from the combustion zone, before being reintroduced into the combustion zone characterised by the arrangement of separation apparatus, e.g. cyclones, for separating particles from the flue gases
- F23C10/10—Fluidised bed combustion apparatus with means specially adapted for achieving or promoting a circulating movement of particles within the bed or for a recirculation of particles entrained from the bed the particles being circulated to a section, e.g. a heat-exchange section or a return duct, at least partially shielded from the combustion zone, before being reintroduced into the combustion zone characterised by the arrangement of separation apparatus, e.g. cyclones, for separating particles from the flue gases the separation apparatus being located outside the combustion chamber
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C10/00—Fluidised bed combustion apparatus
- F23C10/18—Details; Accessories
- F23C10/20—Inlets for fluidisation air, e.g. grids; Bottoms
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C10/00—Fluidised bed combustion apparatus
- F23C10/18—Details; Accessories
- F23C10/24—Devices for removal of material from the bed
- F23C10/26—Devices for removal of material from the bed combined with devices for partial reintroduction of material into the bed, e.g. after separation of agglomerated parts
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Treating Waste Gases (AREA)
Abstract
The invention provides a kind of combustion system of circulating fluidized bed boiler and burning process.The combustion system includes：CFBB, there is circulating flue gas outlet and secondary air inlet；Secondary air channel, the tail end of secondary air channel are connected with secondary air inlet, and circulating flue gas entrance is provided with secondary air channel；Circulating flue gas pipeline, one end are connected with circulating flue gas outlet, and the other end is connected with circulating flue gas entrance；Reducing agent entrance, is arranged on secondary air channel, and between circulating flue gas entrance and secondary air inlet.The application is by the way that reducing agent entrance, circulating flue gas pipeline and secondary air channel are attached, reducing agent is set to be sufficiently mixed with the flue gas in CFBB using the high speed of Secondary Air, further lift residence time of the reducing agent in flue gas, reach the purpose for promoting nitrogen oxides reduction, therefore improve the denitration efficiency that is reacted in whole recirculating fluidized bed to more than 75%.
Description
Technical field
The present invention relates to field of combustion technology, in particular to a kind of combustion system of circulating fluidized bed boiler and combustion
Firing technique.
Background technology
Recently as expanding economy, Industrial Boiler quantity increases rapidly, therewith caused atmosphere polluting problem also by
Fade in existing or even become seriously.CFBB relies on wide fuel tolerance, high combustion efficiency and nitrogen oxides
Low advantage is discharged to be welcome by more and more enterprises now.With the implementation of the new boiler smoke discharge standard of country, state
Indices requirement of the family for boiler emission flue gas pollutant all increases substantially.Flue dust and sulfur dioxide are by existing at present
Efficient dedusting technology and Wet Flue Gas Desulfurization Technique can basically reach requirement.For nitrogen oxides, with the raising of national standard,
Even if the relatively low CFBB of nitrogen oxide emission also is difficult to reach in the case where not increasing extra denitrification apparatus
The requirement of national standard, thus develop in prior art basis new denitration technology have become each enterprise it is urgent highly necessary
Ask.
For relatively large CFBB, such as the electricity generation boiler in thermal power plant, using SCR denitration system
Reach preferable denitration effect.But investment height again for more small-sized CFBB, SCR denitration system be present, build
Make the cycle it is long the shortcomings of, thus select SNCR denitration system more.The principle of SNCR denitration system be in suitable temperature range,
Reducing agent decomposes rapidly, with nitrogen oxides hybrid reaction, is transformed into the environmentally safe product such as nitrogen and water.But
As concern of the country to environmental issue is increasingly lifted, control of the country for discharged nitrous oxides can stricter, this technology
Increasingly strict environmental requirement can not be met.
The content of the invention
It is a primary object of the present invention to provide a kind of combustion system of circulating fluidized bed boiler and burning process, to solve
The problem of discharged nitrous oxides of CFBB are excessive in the prior art.
To achieve these goals, according to an aspect of the invention, there is provided a kind of burning in circulating fluid bed boiler system
System, including：CFBB, there is circulating flue gas outlet and secondary air inlet；Secondary air channel, the tail end of secondary air channel with
Secondary air inlet is connected, and circulating flue gas entrance is provided with secondary air channel；Circulating flue gas pipeline, one end export phase with circulating flue gas
Even, the other end is connected with circulating flue gas entrance；Reducing agent entrance, is arranged on secondary air channel, and positioned at circulating flue gas entrance and
Between secondary air inlet.
Further, above-mentioned combustion system also includes air preheater, and secondary air channel and circulating flue gas pipeline pass through air
Preheater, circulating flue gas entrance are located at air preheater downstream.
Further, above-mentioned combustion system also includes reducing agent injection apparatus, reducing agent injection apparatus and reducing agent entrance
It is connected.
Further, air-introduced machine is provided with above-mentioned circulating flue gas pipeline, air-introduced machine is arranged on air preheater and circulation
Between smoke inlet, circulating fan is additionally provided with preferred cycle flue, circulating fan is arranged on air-introduced machine and circulation cigarette
Between gas entrance.
Further, it is additionally provided with above-mentioned circulating flue gas pipeline：Superheater, is arranged on circulating flue gas outlet and air is pre-
Between hot device；Optional reheater, is arranged between superheater and air preheater；Optional economizer, is arranged on reheater
Between air preheater.
Further, above-mentioned CFBB has First air entrance, and combustion system also includes primary air piping, once
The tail end of airduct is connected with First air entrance, and primary air piping is in parallel with secondary air channel to pass through air preheater.
Further, above-mentioned CFBB includes：CFBB main body, there is combustion tail gas to export,
Reclaim fuel inlet and secondary air inlet；Cyclone separator, cyclone separator pass through the tail that burns with CFBB main body
Gas exports to be connected with recovery fuel inlet, and circulating flue gas outlet is arranged on cyclone separator.
Further, above-mentioned combustion system also includes：Ammonia storage tank；Metered dispensing unit, there is reducing agent outlet, ammonia import
And air intake, ammonia import are connected with ammonia storage tank；Equipartition device, there is reducing agent entrance, reducing agent outlet, compressed air inlet
And compressed air outlet, reducing agent entrance are connected with reducing agent outlet, reducing agent outlet and compressed air outlet spray with reducing agent
Injection device is connected；Air compressor machine, it is connected with compressed air inlet.
According to the another aspect of the application, there is provided a kind of burning in circulating fluid bed boiler technique, burning process include：Follow
Circulation fluidized bed boiler burns and produces flue gas；Using at least part flue gas as circulating flue gas, and by circulating flue gas and reducing agent with
Secondary Air is burnt into CFBB.
Further, above-mentioned reducing agent is mixed with spray regime with circulating flue gas and Secondary Air.
Further, above-mentioned reducing agent is the urea or ammonia solution that mass concentration is 5%~10%, and reducing agent is with 50m/
More than s flow velocity injection mixes with circulating flue gas and Secondary Air；Reducing agent is anhydrous ammonia, and reducing agent is with more than 100m/s flow velocity
Injection mixes with circulating flue gas and Secondary Air.
Further, above-mentioned burning process includes：Before the Secondary Air enters the CFBB, by institute
Flue gas is stated to be exchanged heat with the Secondary Air.
Further, above-mentioned circulating flue gas is less than the 10% of the amount of flue gas emission, preferably controls the circulating flue gas
For oxygen volume content below 12%, the temperature of the further preferred circulating flue gas is more preferably described between 140~180 DEG C
The flow velocity of Secondary Air is between 20-30m/s.
Apply the technical scheme of the present invention, the application is by the way that reducing agent entrance, circulating flue gas pipeline and secondary air channel are entered
Row connection, makes reducing agent be sufficiently mixed with the flue gas in CFBB using the high speed of Secondary Air, further lifting
Residence time of the reducing agent in flue gas, reach the purpose for promoting nitrogen oxides reduction, therefore improve whole recirculating fluidized bed
The denitration efficiency of middle reaction is to more than 75%；Meanwhile simultaneously because circulating flue gas temperature and oxygen content are relatively low relative to Secondary Air,
Therefore circulating flue gas, which enters in CFBB, can reduce oxygen content therein and temperature, so can further subtract
The generation of few thermal NO；Further, since reducing agent and nitrogen oxides could be suitable with one at 800-1000 DEG C
Speed reacts, and this temperature province typically passes through above-mentioned in the convective region of upper furnace, the application under existing SNCR technologies
Set-up mode makes reducing agent with the flue gas in CFBB after fluidisation area further mixes, at the same time due to stove
Temperature is controlled to suitable denitration reduction reaction in the presence of circulating flue gas and obtains temperature window, and reducing agent begins to decompose into NH3Base
With free radical, nitrogen oxides again with NH3React generation nitrogen and water, it is possible thereby in the case of improving boiler at low load, instead
Answer temperature too low the problem of causing denitration efficiency to decline.
Brief description of the drawings
The Figure of description for forming the part of the application is used for providing a further understanding of the present invention, and of the invention shows
Meaning property embodiment and its illustrate be used for explain the present invention, do not form inappropriate limitation of the present invention.In the accompanying drawings：
Fig. 1 shows the structural representation of the combustion system provided according to a preferred embodiment of the present invention.
Wherein, above-mentioned accompanying drawing marks including the following drawings：
1st, secondary air channel；01st, overfire air fan；2nd, circulating flue gas pipeline；3rd, primary air piping, 03, primary air fan；
10th, CFBB；11st, CFBB main body；12nd, cyclone separator；20th, superheater；30th, again
Hot device；40th, economizer；50th, air preheater；60th, air-introduced machine；70th, circulating fan；80th, reducing agent injection apparatus；91st, ammonia stores up
Tank；92nd, metered dispensing unit；93rd, equipartition device；94th, air compressor machine, 95, control system.
Embodiment
It should be noted that in the case where not conflicting, the feature in embodiment and embodiment in the application can phase
Mutually combination.Describe the present invention in detail below with reference to the accompanying drawings and in conjunction with the embodiments.
When present inventor is studied the out of stock systems of SNCR and CFBB, find because reducing agent sprays
Mouth is normally at furnace outlet, and when in boiler at low load, temperature is relatively low at furnace outlet, does not reach suitable reaction temperature
Degree, suppress denitration reduction reaction, so as to cause denitration efficiency to decline.In order to solve the problem, this application provides one kind to circulate
Fluidized-bed combustion boiler combustion system and burning process.
In a kind of typical embodiment of the application, there is provided a kind of combustion system of circulating fluidized bed boiler, such as Fig. 1 institutes
Show, the combustion system includes CFBB 10, secondary air channel 1, circulating flue gas pipeline 2 and reducing agent entrance, recycle stream
Fluidized bed boiler 10 has circulating flue gas outlet and secondary air inlet；The tail end of secondary air channel 1 is connected with secondary air inlet, Secondary Air
Circulating flue gas entrance is provided with pipe 1；One end of circulating flue gas pipeline 2 is connected with circulating flue gas outlet, the other end and circulation cigarette
Gas entrance is connected；Reducing agent entrance is arranged on secondary air channel 1, and between circulating flue gas entrance and secondary air inlet.
The application utilizes Secondary Air by the way that reducing agent entrance, circulating flue gas pipeline 2 and secondary air channel 1 are attached
High speed makes reducing agent be sufficiently mixed with the flue gas in CFBB 10, further lifts reducing agent and stops in flue gas
The time is stayed, reaches the purpose for promoting nitrogen oxides reduction, therefore improve the denitration efficiency reacted in whole recirculating fluidized bed and arrive
More than 75%；Meanwhile simultaneously because circulating flue gas temperature and oxygen content are relatively low relative to Secondary Air, therefore circulating flue gas entrance follows
Oxygen content therein and temperature can be reduced in circulation fluidized bed boiler 10, so can further reduce thermal NO
Generation；Further, since reducing agent and nitrogen oxides could be reacted at 800-1000 DEG C with a suitable speed, it is existing
This temperature province is typically in the convective region of upper furnace under SNCR technologies, the application by above-mentioned set-up mode make reducing agent with
Flue gas in CFBB 10 is after fluidisation area further mixes, at the same time because furnace temperature is in the work of circulating flue gas
Suitable denitration reduction reaction is controlled under and obtains temperature window, reducing agent begins to decompose into NH3Base and free radical, nitrogen oxides
Again with NH3React generation nitrogen and water, it is possible thereby in the case of improving boiler at low load, reaction temperature is too low to cause denitration
The problem of efficiency declines.
Introducing for above-mentioned Secondary Air can set overfire air fan 01 by the initiating terminal in secondary air channel.
According to the conventional arrangement of this area, Secondary Air needs to be heated before CFBB 10 is entered, because
This can set heater to realize the heating to Secondary Air around secondary air channel 1, in order to simplify the combustion system of the application,
It is preferred that as shown in figure 1, above-mentioned combustion system also includes air preheater 50, secondary air channel 1 and circulating flue gas pipeline 2 pass through air
Preheater 50, circulating flue gas entrance are located at the downstream of air preheater 50.Circulating flue gas pipeline 2 and secondary air channel 1 are passed through into air
Preheater 50 is exchanged heat, and realizes the heating to Secondary Air.By after air preheater 50, circulating flue gas pipeline 2 can be with
Flue gas discharge opening is set, to control the amount into the circulating flue gas of CFBB 10.
In the application another kind preferred embodiment, preferably as shown in figure 1, above-mentioned combustion system also includes reducing agent spray
Injection device 80, reducing agent injection apparatus 80 are connected with reducing agent entrance.Injected reduce agent into using reducing agent injection apparatus 80
Secondary air channel 1, ensure that reducing agent is smoothly brought into CFBB 10 by Secondary Air.Due to reducing agent injection apparatus 80 not
Implement transformation on the body of CFBB 10, on the one hand can reduce the efficiency of combustion shadow to CFBB 10
Ring, on the other hand can reduce the implementation cost of traditional SNCR systems.
In order to ensure the stability of the transporting velocity of circulating flue gas, preferably as shown in figure 1, on above-mentioned circulating flue gas pipeline 2
Air-introduced machine 60 is provided with, air-introduced machine 60 is arranged between air preheater 50 and circulating flue gas entrance.In order to promote circulating flue gas
Circulation, circulating fan 70 is additionally provided with preferred cycle flue 2, circulating fan 70 is arranged on air-introduced machine 60 and circulation cigarette
Between gas entrance.
In the application another kind preferred embodiment, preferably as shown in figure 1, being also set up on above-mentioned circulating flue gas pipeline 2
There are superheater 20, optional reheater 30 and optional economizer 40, superheater 20 is arranged on circulating flue gas outlet and air is pre-
Between hot device 50；Reheater 30 is arranged between superheater 20 and air preheater 50；Economizer 40 is arranged on the He of reheater 30
Between air preheater 50.Circulating flue gas is cooled by the setting of superheater 20 and reheater 30, to ensure it short
Mixed in time with suitable temperature with Secondary Air.
In addition, as shown in figure 1, above-mentioned CFBB 10 has First air entrance, combustion system also includes once
Airduct 3, the tail end of primary air piping 3 are connected with First air entrance, excellent in order to improve the heating efficiency of the application combustion system
Choose and state that primary air piping 3 is in parallel with secondary air channel 1 to pass through air preheater 50.The introducing of above-mentioned First air can be by once
The initiating terminal of airduct 3 sets primary air fan 03.
In order to avoid the blocking of circulating flue gas pipeline 2, preferably as shown in figure 1, above-mentioned CFBB 10 includes following
Circulation fluidized bed boiler main body 11 and cyclone separator 12, CFBB main body 11 have combustion tail gas outlet, recovery combustion
Expect entrance and secondary air inlet；Cyclone separator 12, which is exported and reclaimed by combustion tail gas with CFBB main body 11, to be fired
Material entrance is connected, and circulating flue gas outlet is arranged on cyclone separator 12.Combustion tail gas is carried out using cyclone separator 12
Separating treatment, fuel powder therein or particle are separated from combustion tail gas, avoid it from being flowed with circulating flue gas
When be deposited in circulating flue gas pipeline 2, cause circulating flue gas pipeline 2 to block.
In the application another preferred embodiment, as shown in figure 1, above-mentioned combustion system also includes ammonia storage tank 91, meter
Distributor 92, equipartition device 93 and air compressor machine 94 are measured, there is metered dispensing unit 92 reducing agent outlet, ammonia import and air to enter
Mouthful, ammonia import is connected with ammonia storage tank 91；Equipartition device 93 has reducing agent entrance, reducing agent outlet, compressed air inlet and pressure
Contracting air outlet slit, reducing agent entrance are connected with reducing agent outlet, and reducing agent outlet and compressed air outlet fill with reducing agent injection
Put 80 to be connected, air compressor machine 94 is connected with compressed air inlet.Utilize above-mentioned ammonia storage tank 91, metered dispensing unit 92, equipartition device
93 and air compressor machine 94 adjust reducing agent intake, to adapt to the combustion reaction under different condition.In order to improve control efficiency and
Accuracy, preferably above-mentioned ammonia storage tank 91, metered dispensing unit 92, equipartition device 93 and air compressor machine 94 are connected to control system
95。
In another typical embodiment of the application, there is provided a kind of burning in circulating fluid bed boiler technique, burning
Technique includes：Burning in circulating fluid bed boiler simultaneously produces flue gas；Using at least part flue gas as circulating flue gas, and by circulating flue gas
Burnt with reducing agent with Secondary Air into CFBB.
The application makes reducing agent and circulating flue gas mix and be sent into by Secondary Air entrance in CFBB, and utilization is secondary
The high speed of wind makes reducing agent be sufficiently mixed with the flue gas in CFBB, further lifts reducing agent in flue gas
Residence time, reach the purpose for promoting nitrogen oxides reduction, therefore improve the denitration efficiency reacted in whole recirculating fluidized bed
To more than 75%；Meanwhile simultaneously because circulating flue gas temperature and oxygen content are relatively low relative to Secondary Air, therefore circulating flue gas enters
Oxygen content therein and temperature can be reduced in CFBB, so can further reduce thermal NO
Generation；In addition, reducing agent with the flue gas in CFBB after fluidisation area further mixes, at the same time due to
Furnace temperature is controlled to suitable denitration reduction reaction in the presence of circulating flue gas and obtains temperature window, and reducing agent begins to decompose into NH3
Base and free radical, nitrogen oxides again with NH3React generation nitrogen and water, it is possible thereby in the case of improving boiler at low load,
Reaction temperature too low the problem of causing denitration efficiency to decline.
In order to ensure that reducing agent is smoothly brought into CFBB by Secondary Air, preferably above-mentioned reducing agent is with the side of injection
Formula mixes with circulating flue gas and Secondary Air.
In a kind of preferred embodiment of the application, above-mentioned reducing agent is the urea liquid that mass concentration is 5%~10%
Or ammonia solution, reducing agent are mixed with more than 50m/s flow velocity injection with circulating flue gas and Secondary Air；Or reducing agent is anhydrous
Ammonia, reducing agent are mixed with more than 100m/s flow velocity injection with circulating flue gas and Secondary Air.Mixed with above-mentioned flow velocity same
When, the intake of reducing agent is adjusted according to the fluctuation of nitrous oxides concentration in boiler.Nitrogen oxygen is reduced using above-mentioned reducing agent
The chemical equation of compound is as follows：
If reducing agent is urea liquid：
Urea decomposes：
CO(NH2)2+H2O→2NH3+CO2
NH3Reacted with nitrogen oxides：
4NH3+4NO+O2→4N2+6H2O
8NH3+6NO2→7N2+12H2O。
If reducing agent is ammonia：
4NH3+4NO+O2→4N2+6H2O
4NH3+2NO+2O2→3N2+6H2O
8NH3+6NO2→7N2+12H2O。
In order to realize that the heat of burning process makes full use of and controlled secondary point to enter recirculating fluidized bed with circulating flue gas
The temperature of boiler, preferably above-mentioned burning process include：Before Secondary Air enters CFBB, by flue gas and Secondary Air
Exchanged heat.
It is preferred that above-mentioned circulating flue gas is less than the 10% of amount of flue gas emission, it can further be reduced and followed by the control of the content
The fire box temperature and oxygen content of circulation fluidized bed boiler, reduce thermal NO in combustionXYield.
In order to reduce the generation of thermal NO as far as possible, the oxygen volume content of preferred cycle flue gas 12% with
Under.Oxygen volume content is adjusted by controlling burning degree in above-mentioned circulating flue gas, will not be repeated here.
In addition, for the fire box temperature for the control CFBB that improves, the temperature of circulating flue gas is preferably controlled 140
Between~180 DEG C.In order to ensure the mixed effect of reducing agent and circulating flue gas, preferably the flow velocity of Secondary Air 20-30m/s it
Between.
Embodiment 1
Implement the burning process of embodiment 1 using structure shown in Fig. 1.Secondary Air is secondary by entering after air preheater 50
Airduct 1, the flue gas after air preheater 50 enter Secondary Air by air-introduced machine 60 and recirculation blower 70 by recirculating gas duct
Road mixes with Secondary Air, the ammonia that the reducing agent injection apparatus 80 on secondary air duct is sprayed and the gas mixing in secondary air channel 1.
Ammonia, Secondary Air and flue gas recycled the three preliminary mixing in secondary air channel 1 enter recirculating fluidized bed pot by Secondary Air outlet
The fluidisation area of the burner hearth of stove 10 is further mixed with burner hearth flue gas.Wherein the high speed of Secondary Air can promote reducing agent
Ammonia is sufficiently mixed with burner hearth flue gas, while circulating flue gas temperature and oxygen content are relatively low, and circulating flue gas, which enters burner hearth, to be reduced
The oxygen content and temperature of burner hearth, it so can further reduce the generation of thermal NO.Reducing agent ammonia and burner hearth
Flue gas boiler fluidisation area further mix after, at the same time due to furnace temperature be reduced in the presence of flue gas recycled it is suitable
Close denitration reduction reaction and obtain temperature window, reducing agent ammonia begins to decompose into NH3Base and free radical, nitrogen oxides again with NH3Occur
Reaction generation nitrogen and water.Above-mentioned circulating flue gas is the 9% of amount of flue gas emission, and the oxygen volume content of circulating flue gas is 8% or so, temperature
Degree is at 160 DEG C or so, and for Secondary Air gas flow rate in 30m/s or so, reductant nozzle exit velocity is 100m/s.
Using the amount of nitrogen oxides before and after moral figure flue gas analyzer denitrating flue gas, the denitration efficiency for calculating embodiment 1 can
Up to 78%.
Embodiment 2
Difference with embodiment 1 is that above-mentioned circulating flue gas is the 10% of amount of flue gas emission, the oxygen volume content of circulating flue gas
8% or so, temperature is at 140 DEG C or so, and for Secondary Air gas flow rate in 20m/s or so, reductant nozzle exit velocity is 100m/
s.Using the amount of nitrogen oxides before and after moral figure flue gas analyzer denitrating flue gas, the denitration efficiency of embodiment 2 is calculated up to 75%.
Embodiment 3
Difference with embodiment 1 is that above-mentioned circulating flue gas is the 8% of amount of flue gas emission, the oxygen volume content of circulating flue gas
12% or so, temperature is in 30m/s or so, reductant nozzle exit velocity in 160 DEG C or so, Secondary Air gas flow rate
100m/s.Using the amount of nitrogen oxides before and after moral figure flue gas analyzer denitrating flue gas, the denitration efficiency for calculating embodiment 3 is reachable
76%.
Embodiment 4
Difference with embodiment 1 is that reducing agent is the urea liquid that mass concentration is 5%, and above-mentioned circulating flue gas is cigarette
The 8% of gas total amount, the oxygen volume content of circulating flue gas is 9% or so, and at 160 DEG C or so, Secondary Air gas flow rate exists temperature
30m/s or so, reductant nozzle exit velocity are 70m/s.Using the nitrogen oxides before and after moral figure flue gas analyzer denitrating flue gas
Content, the denitration efficiency of embodiment 4 is calculated up to 79%.
Embodiment 5
Difference with embodiment 1 is that reducing agent is the ammoniacal liquor that mass concentration is 10%, and above-mentioned circulating flue gas is that flue gas is total
The 8% of amount, the oxygen volume content of circulating flue gas is 9% or so, and for temperature at 160 DEG C or so, Secondary Air gas flow rate is left in 30m/s
The right side, reductant nozzle exit velocity are 50m/s.Using the amount of nitrogen oxides before and after moral figure flue gas analyzer denitrating flue gas, meter
The denitration efficiency of embodiment 5 is calculated up to 76%.
As can be seen from the above description, the above embodiments of the present invention realize following technique effect：
The application utilizes the height of Secondary Air by the way that reducing agent entrance, circulating flue gas pipeline and secondary air channel are attached
Speed makes reducing agent be sufficiently mixed with the flue gas in CFBB, when further lifting stop of the reducing agent in flue gas
Between, reach the purpose for promoting nitrogen oxides reduction, therefore improve the denitration efficiency that is reacted in whole recirculating fluidized bed to 75%
More than；Meanwhile simultaneously because circulating flue gas temperature and oxygen content are relatively low relative to Secondary Air, therefore circulating flue gas enters recycle stream
Oxygen content therein and temperature can be reduced in fluidized bed boiler, so can further reduce the production of thermal NO
It is raw；Further, since reducing agent and nitrogen oxides could be reacted at 800-1000 DEG C with a suitable speed, existing SNCR
This temperature province typically makes reducing agent and circulation in the convective region of upper furnace, the application by above-mentioned set-up mode under technology
Flue gas in fluidized-bed combustion boiler after fluidisation area further mixes, at the same time due to furnace temperature in the presence of circulating flue gas quilt
Suitable denitration reduction reaction is controlled to obtain temperature window, reducing agent begins to decompose into NH3Base and free radical, nitrogen oxides again with NH3
Reacted generation nitrogen and water, it is possible thereby in the case of improving boiler at low load, reaction temperature is too low to be caused under denitration efficiency
The problem of drop.
The preferred embodiments of the present invention are the foregoing is only, are not intended to limit the invention, for the skill of this area
For art personnel, the present invention can have various modifications and variations.Within the spirit and principles of the invention, that is made any repaiies
Change, equivalent substitution, improvement etc., should be included in the scope of the protection.
Claims (13)
- A kind of 1. combustion system of circulating fluidized bed boiler, it is characterised in that including：CFBB (10), there is circulating flue gas outlet and secondary air inlet；Secondary air channel (1), the tail end of the secondary air channel (1) are connected with the secondary air inlet, are set on the secondary air channel (1) It is equipped with circulating flue gas entrance；Circulating flue gas pipeline (2), one end are connected with circulating flue gas outlet, and the other end is connected with the circulating flue gas entrance；Reducing agent entrance, it is arranged on the secondary air channel (1), and is located at the circulating flue gas entrance and the secondary air inlet Between.
- 2. combustion system according to claim 1, it is characterised in that the combustion system also includes air preheater (50), the secondary air channel (1) and the circulating flue gas pipeline (2) pass through the air preheater (50), the circulating flue gas Entrance is located at the air preheater (50) downstream.
- 3. combustion system according to claim 1, it is characterised in that the combustion system also includes reducing agent injection apparatus (80), the reducing agent injection apparatus (80) is connected with the reducing agent entrance.
- 4. combustion system according to claim 2, it is characterised in that be provided with air inducing on the circulating flue gas pipeline (2) Machine (60), the air-introduced machine (60) is arranged between the air preheater (50) and the circulating flue gas entrance, preferably described Be additionally provided with circulating fan (70) on circulating flue gas pipeline (2), the circulating fan (70) be arranged on the air-introduced machine (60) and Between the circulating flue gas entrance.
- 5. combustion system according to claim 2, it is characterised in that be additionally provided with the circulating flue gas pipeline (2)：Superheater (20), it is arranged between the circulating flue gas outlet and the air preheater (50)；Optional reheater (30), is arranged between the superheater (20) and the air preheater (50)；Optional economizer (40), is arranged between the reheater (30) and the air preheater (50).
- 6. combustion system according to claim 2, it is characterised in that the CFBB (10) has First air Entrance, the combustion system also include primary air piping (3), and the tail end of the primary air piping (3) is connected with the First air entrance, The primary air piping (3) is in parallel with the secondary air channel (1) to pass through the air preheater (50).
- 7. combustion system according to claim 1, it is characterised in that the CFBB (10) includes：CFBB main body (11), there is combustion tail gas outlet, recovery fuel inlet and the secondary air inlet；Cyclone separator (12), the cyclone separator (12) pass through the burning with the CFBB main body (11) Offgas outlet is connected with the recovery fuel inlet, and circulating flue gas outlet is arranged on the cyclone separator (12).
- 8. combustion system according to claim 3, it is characterised in that the combustion system also includes：Ammonia storage tank (91)；Metered dispensing unit (92), there is reducing agent outlet, ammonia import and air intake, the ammonia import and the ammonia storage tank (91) it is connected；Equipartition device (93), there is reducing agent entrance, reducing agent outlet, compressed air inlet and compressed air outlet, it is described to go back Former agent entrance is connected with reducing agent outlet, and the reducing agent outlet and the compressed air outlet spray with the reducing agent Device (80) is connected；Air compressor machine (94), is connected with the compressed air inlet.
- 9. a kind of burning in circulating fluid bed boiler technique, it is characterised in that the burning process includes：Burning in circulating fluid bed boiler simultaneously produces flue gas；At least partly described flue gas is entered into recycle stream as circulating flue gas, and by the circulating flue gas and reducing agent with Secondary Air Fluidized bed boiler is burnt.
- 10. burning process according to claim 9, it is characterised in that the reducing agent is with spray regime and the circulation Flue gas and Secondary Air mixing.
- 11. burning process according to claim 10, it is characterised in that the reducing agent be mass concentration be 5%~ 10% urea or ammonia solution, the reducing agent is with the injection of more than 50m/s flow velocity and the circulating flue gas and described secondary Wind mixes；The reducing agent is anhydrous ammonia, and the reducing agent is with more than 100m/s flow velocity injection and the circulating flue gas and institute State Secondary Air mixing.
- 12. burning process according to claim 9, it is characterised in that the burning process includes：Enter in the Secondary Air Before entering the CFBB, the flue gas and the Secondary Air are exchanged heat.
- 13. burning process according to claim 9, it is characterised in that the circulating flue gas is the amount of flue gas emission Less than 10%, the oxygen volume content of the circulating flue gas is preferably controlled below 12%, the further preferred circulating flue gas Temperature is between 140~180 DEG C, and the flow velocity of more preferably described Secondary Air is between 20-30m/s.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110986031A (en) * | 2019-12-05 | 2020-04-10 | 西安交通大学 | System for avoiding water vapor condensation in gas boiler flue gas recirculation pipeline |
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