CN106439796A - Flue gas volume/nitric oxide emission reduction system of low-load coal-fired boiler - Google Patents

Flue gas volume/nitric oxide emission reduction system of low-load coal-fired boiler Download PDF

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Publication number
CN106439796A
CN106439796A CN201610987345.XA CN201610987345A CN106439796A CN 106439796 A CN106439796 A CN 106439796A CN 201610987345 A CN201610987345 A CN 201610987345A CN 106439796 A CN106439796 A CN 106439796A
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China
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flue gas
unit
air
boiler
controller
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CN201610987345.XA
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Chinese (zh)
Inventor
张凡
黄家玉
朱金伟
王洪昌
束韫
王凡
石应杰
田刚
张辰
崔宇韬
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Chinese Research Academy of Environmental Sciences
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Chinese Research Academy of Environmental Sciences
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Priority to CN201610987345.XA priority Critical patent/CN106439796A/en
Publication of CN106439796A publication Critical patent/CN106439796A/en
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23CMETHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C9/00Combustion apparatus characterised by arrangements for returning combustion products or flue gases to the combustion chamber
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23CMETHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN  A CARRIER GAS OR AIR 
    • F23C9/00Combustion apparatus characterised by arrangements for returning combustion products or flue gases to the combustion chamber
    • F23C9/08Combustion apparatus characterised by arrangements for returning combustion products or flue gases to the combustion chamber for reducing temperature in combustion chamber, e.g. for protecting walls of combustion chamber

Abstract

The invention provides a flue gas volume/nitric oxide emission reduction system of a low-load coal-fired boiler. The system comprises a flue gas purification unit of the coal-fired boiler and a flue gas recirculation reduction unit. A circulation port is formed in a connecting pipeline between a dust removing plant and a desulphurization device of the flue gas purification unit. A flue gas inlet of the flue gas recirculation reduction unit is connected with the circulation port. A flue gas outlet of the flue gas recirculation reduction unit is connected with an air inlet of the coal-fired boiler. A part of dedusted flue gas is distributed and circulated into the boiler to serve as a combustion-supporting gas, and the purpose of flue gas reduction emission is achieved. The flue gas volume/nitric oxide emission reduction system is used for the low-load coal-fired boiler with high flue gas oxygen content, is provided with a flue gas purification system with the independent dedusting and desulphurization treatment devices and can realize the purposes of flue gas emission reduction and atmospheric pollutant total discharge amount reduction. After flue gas is recirculated, the oxygen content in flue gas is greatly reduced, and the atmospheric pollutant benchmark emission concentration is obviously reduced by 30%-60%.

Description

A kind of underload fire coal boiler fume amount/nitrogen oxides emission-reducing system
Technical field
The present invention relates to fume treatment technical field, more particularly to a kind of underload fire coal boiler fume amount/nitrogen oxides Emission-reducing system.
Background technology
At present, coal-burning boiler is still one of important source of China's urban atmospheric pollution.How coal-burning boiler cigarette is effectively cut down The discharge capacity of pollutant in gas is significant to improving city atmospheric environment air quality.In flue gas, gross contamination emission is Exhausted air quantity and the product of Pollutant emission concentration.At present, China control air dirt only by formulating strict discharge standard The concentration of emission of dye thing, and the control as the key factor exhaust gas volumn of impact gross contamination emission does not cause enough Pay attention to.China's coal-burning boiler, especially coal-fired boiler in power plant Air Pollutant Emission concentration reach most tight discharge standard in history, Only it is difficult to make PM in flue gas by pollutant discharge in compliance with the standard2.5And PM2.5Precursor (SO2、NOx) etc. gross contamination emission persistently drop Low.As any atmosphere pollution control technology can not possibly all reach 100% removal efficiency, and exhaust gas volumn is reduced discharging and can be blocked Once with secondary PM2.5The way of production, to China's air Contaminations of Coal Burning Boilers overall control, there is irreplaceable work With.
Due to by season thermic load change and production in terms of etc. reason affected, China's industry coal-boiler long-term existence is low Load operation operating mode, average operating load only has the 30%~80% of rated load.Boiler capacity is less, and average load rate is got over Low.Under the conditions of underrun, as Coal-fired capacity reduces, excess air factor becomes big, and boiler export flue gas oxygen content is obvious Improve.In actual motion, part boiler export flue gas oxygen content is even above more than 15%, far above Industrial Boiler exiting flue gas Benchmark oxygen content concentration (9%).For the hyperoxic feature of this underload fire coal boiler fume, by being followed using flue gas again Loop technique, makes a part of high temperature rich oxygen content flue gas substitute the combustion air of boiler, realizes exhaust gas volumn reduction of discharging.
At present, it is to realize the reduction of discharging of fire coal boiler fume amount, the technology of flue gas recirculation mainly has:1. in boiler plant, flue gas is again Circulating technology;Which is primarily adapted for use in the utilization of small scall coal-fired boiler flue gas recirculation, and flue gas is not filled with desulfurization through independent dedusting Put process.2. boiler smoke has independent dedusting to process with desulfurizer, relies on input pure oxygen, mixes with part boiler smoke recirculation As boiler auxiliary combustion gas after conjunction, typical technology has " oxygen-enriched or O2/CO2Combustion technology ";As oxygen processed is relatively costly, thus, Overall operation is relatively costly.3. boiler smoke has independent dedusting with desulfurizer process, boiler part flue gas recirculation and cold sky Gas directly mixes the combustion air as boiler;As flue gas recycled humidity is high and contains a small amount of SO3, with the air not heated Directly after combination cooling, flue-gas temperature is less than acid dew-point temperature, easily causes boiler preheater and the corruption of partial fume pipeline low temperature Erosion, affects the stable operation of system.Further, since circulation is helped higher than existing air as the temperature of the partial fume of combustion-supporting gas The problem of combustion gas body, necessarily improves the temperature of boiler emission flue gas, causes thermal loss.
Content of the invention
Drawbacks described above and problem for prior art, it is an object of the invention to provide a kind of underload fire coal boiler fume Amount/nitrogen oxides emission-reducing system.The irrational technical problem of emission-reducing system of existing coal-burning boiler is solved, leads to not realize most The reduction of discharging of the exhaust gas volumn/nitrogen oxides of limits, and reach heat maximization recycling.
In order to achieve the above object, the present invention provides following technical scheme:
A kind of underload fire coal boiler fume amount/nitrogen oxides emission-reducing system, including the gas cleaning unit of coal-burning boiler, Wherein, also include flue gas recirculation decrement unit, the connection between the cleaner and desulphurization plant of the gas cleaning unit Circulation port is opened up on pipeline, the smoke inlet of the flue gas recirculation decrement unit is connected with the circulation port, outlet flue and coal-fired pot The air intake connection of stove;Flue gas shunting after the dedusting of part is recycled to as combustion-supporting gas in boiler, is reached exhaust gas volumn and subtract The purpose of amount discharge.
Specifically, the flue gas recirculation decrement unit includes circulating line, loop control valve and circulating fan, described follows The smoke inlet in endless tube road is connected with the circulation port, and outlet flue is connected with the air intake of coal-burning boiler, the circulation control valve Door and circulating fan are arranged on the circulating line.
Further, the emission-reducing system also includes compensated with air unit, and the compensated with air unit is followed to the flue gas Make-up air in the dedusting flue gas of bypassing circulation in ring decrement unit, adjusts the oxygen content in the dedusting flue gas after make-up air For 15%~21%.
Specifically, the compensated with air unit includes to compensate pipeline, compensating control valve door and heater, the compensation pipeline Gas outlet connect with the circulating line of dedusting flue gas in the flue gas recirculation decrement unit;The heater is arranged on the benefit Repay on pipeline, heat air;The compensating control valve door is arranged on the compensation pipeline.
Further, the emission-reducing system also includes oxygen concentration automatic adjustment unit, and the oxygen concentration is automatically adjusted Unit includes controller and oxygen concentration sensor, and the collection terminal of the oxygen concentration sensor is arranged on flue gas recirculation decrement list At the smoke inlet of unit, outfan is connected with the input of the controller;The outfan of the controller and the compensated with air The control end connection of the loop control valve of the control end of the compensating control valve door of unit and flue gas recirculation decrement unit;
The oxygen concentration sensor collection enters the oxygen density value of the circulating flue gas of flue gas recirculation decrement unit, and defeated Go out to controller;Controller is according to the oxygen density value of the circulating flue gas, the oxygen content value of default mixed flue gas and fire coal The combustion-supporting gas total amount of boiler, obtains the circulating flue gas flow of flue gas recirculation decrement unit and the make-up air of compensated with air unit Flow, and according to the circulating flue gas flow and make-up air flow control and regulation compensating control valve door and the opening of loop control valve Qi Liang, so as to adjust to circulating flue gas flow and make-up air flow.
Further, the emission-reducing system also includes make-up air thermostat unit, the make-up air temperature adjustment Unit includes temperature sensor and controller;The collection terminal of the temperature sensor is arranged in the compensated with air unit and heats On the pipeline of device outlet, outfan is connected with the input of the controller;The outfan of the controller and the heater Control end connection;Air temperature value after the temperature sensor collection heating, and export to controller;When controller is received Air temperature value less than the circulating flue gas in default flue gas recirculation decrement unit in controller dew point temperature value when, control Device control heater improves heating intensity and improves air themperature;Conversely, when air temperature value is higher than default circulation in controller During the dew point temperature value of flue gas, controller control heater reduces heating intensity and reduces air themperature.
Further, the emission-reducing system also includes blender, and the blender is arranged on the flue gas recirculation decrement list On the circulating line of the dedusting flue gas in unit, the gas outlet of the compensated with air unit is connected with the blender;Circulated removes After the air of cloud of dust gas and compensation mixes in a mixer, boiler is entered back into.
Further, the gas cleaning unit of the coal-burning boiler includes cleaner unit and desulfurizing tower, goes out in the flue gas of boiler The cleaner unit and desulfurizing tower are sequentially connected on mouthful;Wherein, also include low-level (stack-gas) economizer, the connection between boiler and cleaner unit Connect low-level (stack-gas) economizer on pipeline, the heat of boiler smoke is reclaimed.
Further, the gas cleaning unit of the coal-burning boiler also includes chimney, and the chimney is connected to the desulfurization In the purifying smoke outlet of tower.
In the present invention, the underload refers to the 30%~80% of rated load.
The emission-reducing system of the present invention has the advantages that:
(1) the present invention be directed to underload fire coal boiler fume oxygen content is high, and with independent dedusting, desulfurization process device Flue gas purification system emission-reducing system.The reduction of discharging of underload fire coal boiler fume amount can be realized, effectively cuts down atmosphere pollution Total emission volumn.And in flue gas, oxygen content is substantially reduced after flue gas recirculation, less than 9%, thus, according to the dirt of coal-burning boiler air The translation method of dye thing benchmark oxygen content (9%) concentration of emission, atmosphere pollution benchmark concentration of emission substantially reduces, and cuts down 30% ~60%.
(2) the hyperoxic feature of underload fire coal boiler fume is directed to, circulating flue gas supplement partial air is used as helping Combustion gas body, you can meet oxygen amount needed for boiler combustion, realizes " low oxygen combustion ".Therefore, with some need to inject O at present2Boiler Flue gas recirculation technology is compared, and the emission-reducing system of the present invention can reduce temperature levels and oxygen concentration in burner hearth, suppress fuel NOx Formation, part NOxReduced by coal dust catabolite (as red-hot coal tar and reducibility gas), NO is greatly loweredxDischarge Amount.Meanwhile, supplementing partial air can meet oxygen amount needed for boiler combustion, need note with some boiler smoke circulating technologies current Enter O2Compare, oxygen cost processed can be greatlyd save, overall operation cost reduces.
(3) under " low oxygen combustion " mode, the oxygen content in compensated with air flue gas can be adopted;Existing " oxygen-enriched combusting " flue gas Circulating technology, need to adopt the oxygen generating plants such as space division to supplement a large amount of oxygen;Flue gas recirculation technology phase with existing employing supplemental oxygen Than for, the equipment investment of the emission-reducing system of the present invention reduces, and power consumption also reduces.
(4) compared with conventional boiler flue gas recirculating technique, the present invention passes through, under the conditions of flue gas recirculation, to increase before cleaner unit If low-level (stack-gas) economizer reduces exhaust gas temperature, it is possible to resolve after fire coal boiler fume recirculation, exhaust gas temperature is too high causes heat The problem that efficiency reduces, improves boiler thermal output;It also avoid the too high impact sack cleaner of exhaust gas temperature after flue gas recirculation Safe and stable operation;Additionally, setting up low-level (stack-gas) economizer to reduce exhaust gas temperature, also correspond to reduce smoke discharge amount, Follow-up dedusting, the treatment effeciency of desulfurization environmental protection facility is improve indirectly, reduces the discharge capacity of atmosphere pollution.
(5) by the way of the air after heating is mixed with high-temperature flue gas as boiler auxiliary combustion gas, can be prevented effectively from The cold end corrosion problem of air preheater and flue gas recirculation pipeline.Additionally, the high-temperature flue gas after dedusting are recycled to boiler, it is also possible to big Big minimizing pipeline, blower fan and boiler furnace inter deterioration.
Description of the drawings
In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing Accompanying drawing to be used needed for technology description is had to be briefly described, it should be apparent that, drawings in the following description are only this Some embodiments of invention, for those of ordinary skill in the art, without having to pay creative labor, may be used also To obtain other accompanying drawings according to these accompanying drawings.
Fig. 1 is the structure connection diagram of the underload fire coal boiler fume amount/nitrogen oxides emission-reducing system of the present invention.
Specific embodiment
Below in conjunction with embodiments of the invention, technical scheme is clearly and completely described, it is clear that Described embodiment is only a part of embodiment of the present invention, rather than whole embodiments.Based on the enforcement in the present invention Example, the every other embodiment obtained under the premise of creative work is not made by those of ordinary skill in the art, belong to The scope of protection of the invention.
A kind of underload fire coal boiler fume amount/nitrogen oxides emission-reducing system of the present invention, according to Fig. 1, is described.This Invention is oxygen content height in the flue gas for producing for underload coal-burning boiler, and the cigarette with independent dedusting, desulfurization process device The emission-reducing system of gas clean unit.
The gas cleaning unit of existing coal-burning boiler includes cleaner unit 4 and desulfurizing tower 6, boiler 1 exhanst gas outlet (i.e. The exhanst gas outlet of the air preheater 2 that boiler 1 is carried) on be sequentially connected the cleaner unit 4 and desulfurizing tower 6, through 6 desulfurization process of desulfurizing tower Purifying smoke afterwards is emitted in air, and arranges air-introduced machine 5 on the pipeline of gas cleaning unit, it is ensured that the flowing of flue gas. Typically also include chimney 7, chimney 7 is connected in the purifying smoke outlet of the desulfurizing tower 6, and purifying smoke is discharged via chimney 7 To air.
In order to the reduction of discharging of underload fire coal boiler fume amount is realized, Air Pollutant Emission total amount is effectively cut down, the present invention exists On the basis of the gas cleaning unit of existing coal-burning boiler, flue gas recirculation decrement unit is increased, in the gas cleaning unit Cleaner (cleaner unit 4) and desulphurization plant (desulfurizing tower 6) between connecting pipe on open up circulation port, the flue gas recirculation The smoke inlet of decrement unit is connected with the circulation port, and (i.e. boiler 1 is carried the air intake 15 of outlet flue and coal-burning boiler 1 The air intake 15 of air preheater 2) connection;Using the dedusting flue gas after the dedusting of part as circulating flue gas bypassing circulation to boiler 1 in As combustion-supporting gas, the purpose of exhaust gas volumn decrement discharge is reached.
Specifically, the flue gas recirculation decrement unit includes circulating line 8, loop control valve 9 and circulating fan 10, institute The smoke inlet for stating circulating line 8 is connected with the circulation port, and outlet flue is connected with the air intake 15 of coal-burning boiler 1, described is followed Ring control valve 9 and circulating fan 10 are arranged on the circulating line 8.The loop control valve 9 is using flue gas with automatically Regulating valve etc., such as model ZAJW automatic regulating valve, are conveniently connected with existing supporting control system, realize Automated condtrol.
When flue gas recirculation is introduced boiler as combustion-supporting gas, needs consider the oxygen content in the flue gas being introduced into, by Oxygen content in the discharge flue gas of underload coal-burning boiler is higher than Industrial Boiler exiting flue gas benchmark oxygen content concentration (9%), Had even can reach more than 15%, and the present invention, will i.e. using the oxygen content feature of the flue gas of underload discharged from coal-fired boiler Control for Oxygen Content in circulating flue gas realizes " low oxygen combustion " in boiler 15%~21%.In order to effective control circulates cigarette Oxygen content in gas, in the emission-reducing system of the present invention, also includes compensated with air unit, and the compensated with air unit is to the flue gas Make-up air in the dedusting flue gas of bypassing circulation in circulation decrement unit, adjusts the compensation sky of the air intake for entering coal-burning boiler The oxygen content in mixed flue gas after gas.Specifically can adopt following structure compensated with air unit, including compensate pipeline 16, Compensating control valve door 12 and heater 13, remove the cloud of dust in the gas outlet of the compensation pipeline 16 and the flue gas recirculation decrement unit The circulating line 8 of gas is connected;The heater 13 is arranged on the compensation pipeline 16, is air heating;The compensation control Valve 12 is arranged on the compensation pipeline 16.The compensating control valve door 12 is using flue gas automatic regulating valve etc., such as model For ZAJW automatic regulating valve.
In order to the oxygen content in combustion-supporting gas in real time to entrance coal-burning boiler is monitored, and timely automated adjustment, this Also include oxygen concentration automatic adjustment unit (not shown), the oxygen concentration automatic adjustment unit bag in the emission-reducing system of invention Controller and oxygen concentration sensor is included, the collection terminal of the oxygen concentration sensor is arranged on entering for flue gas recirculation decrement unit At mouth, outfan is connected with the input of the controller;The outfan of the controller and the compensated with air unit The control end connection of the loop control valve 9 of the control end of compensating control valve door 12 and flue gas recirculation decrement unit.The oxygen Concentration sensor will gather the oxygen density value of the circulating flue gas for entering flue gas recirculation decrement unit, and export to controller.Control Device processed is according to the oxygen density value (c) of the circulating flue gas, the oxygen content value (C) of default mixed flue gas and helping for coal-burning boiler Combustion gas gross (V), obtains the circulating flue gas flow (V of flue gas recirculation decrement unit1) and compensated with air unit make-up air Flow (V2), and according to circulating flue gas flow (V1) and make-up air flow (V2) control to adjust compensating control valve door 12 and follow The open amount of ring control valve 9, so as to adjust to circulating flue gas flow (V1) and make-up air flow (V2).
Specifically, in the present invention, in make-up air, oxygen content (21%) is definite value, true in the range of 15%~21% Fixed, V is determined according to operating experience value under actual coal-burning boiler difference working condition.Therefore, V1=[(21%-C)/(21%-c)] ×V;V2=[(C-c)/(21%-c)] × V.Controller can obtain corresponding theoretical circulation cigarette according to the theoretical formula analysis Throughput (V1) and theoretical com-pensation air mass flow (V2).
The compensated with air unit of the present invention includes heater, and effect is that make-up air is heated.Due to circulating cigarette Gas is with uniform temperature, therefore, when the low air of the temperature circulating flue gas high with temperature meet and mix, and causes circulation The temperature of flue gas reduces, and when flue-gas temperature is less than acid dew-point temperature, easily causes boiler preheater and partial fume pipeline low temperature Corrosion, affects the stable operation of system.Therefore, using heater, make-up air is heated, when by the temperature of make-up air More than the dew point temperature value (typically at 85-100 DEG C) of the circulating flue gas being heated in flue gas recirculation decrement unit, higher than the circulation The generation of above-mentioned phenomenon can be avoided during the dew point of flue gas.In order to accurately control the temperature of heating post-compensation air, the present invention Make-up air thermostat unit is increased, the make-up air thermostat unit includes temperature sensor (make-up air temperature Degree sensor) and controller;The collection terminal of the temperature sensor is arranged on going out for the heater 13 of the compensated with air unit On the pipeline of mouth, the air temperature value after heating is gathered, outfan is connected with the input of the controller, the air that will gather Temperature value is exported to controller.The outfan of the controller is connected with the control end of the heater, the temperature sensor Air temperature value after collection heating, and export to controller.When the air temperature value that controller is received is less than in controller in advance If circulating flue gas dew point temperature (85-100 DEG C) when, controller control heater improve heating intensity improve air themperature; Conversely, when air temperature value is higher than the dew point temperature of default circulating flue gas, controller control heater reduces heating intensity Reduce air themperature.Realize automatically controlling for heater heating intensity.
In order to improve the mixability of the dedusting flue gas of supplementary air and circulation, also add in the emission-reducing system of the present invention Blender 11, the blender 11 is arranged on the circulating line 8 of the dedusting flue gas in the flue gas recirculation decrement unit, described The gas outlet of the compensation pipeline 16 of compensated with air unit is connected with the blender 11;The air of circulating flue gas and compensation is in mixing After mixing in device, boiler 1 is entered back into.
In the present invention, due to using partial fume bypassing circulation as boiler combustion-supporting gas, therefore, the temperature of combustion-supporting gas Improve, and then the temperature of the flue gas of boiler generation is also correspondingly improved, then partial heat energy is increased in the flue gas for discharging.Therefore, In order to the partial heat energy is reclaimed, heat energy recovery rate is improved, the emission-reducing system of the present invention is preferably net to existing flue gas Change the Optimal improvements that unit is carried out, be connected low-level (stack-gas) economizer 3 on the connecting pipe between boiler 1 and cleaner unit 4, to boiler smoke The heat of gas is reclaimed.By controlling the parameter of low-level (stack-gas) economizer 3, the temperature of boiler smoke is made to be reduced to existing flue gas net Change the input gas temperature of cleaner unit 4 in unit (not setting up flue gas recirculation decrement unit), ensure the safety and stability of cleaner unit Operation.
In the present invention, the oxygen concentration automatic adjustment unit and make-up air thermostat unit can adopt same control Device processed completes to automatically control, it would however also be possible to employ independent controller is realized automatically controlling, it is also possible to by the control of the two units The function of device is integrated in the control system in the gas cleaning unit of existing coal-burning boiler, realizes unified Automated condtrol.
The invention provides specific examples below is illustrating the environment of emission-reducing system of the present invention and economic benefit.
Embodiment 1
35t/h circulating fluidized bed combustion coal boiler, runs under 50% loading condiction, in the process of existing gas cleaning unit Under, after cleaner unit, in desulfurizing tower preceding pipeline, flue gas oxygen content reaches 15%.Using the emission-reducing system of the present invention, 45% dedusting is taken Flue gas afterwards introduces gas mixing box via the circulating line booster fan of flue gas recirculation decrement unit, and by compensated with air unit After the air for being heated to 85 DEG C for introducing mixes in gas mixing box, the oxygen content concentration of mixed gas reaches 16%, then Enter boiler air preheater entrance.
Using above-mentioned emission-reducing system, and after stable operation, oxygen content in the flue gas of chimney is drained into outside boiler smoke and is less than 8%.Exhaust gas volumn can reduce discharging 55%, PM2.5、NOxTotal release can reduce about 20%~30%, save mark coal about 5~8t/h.
As a comparison, in the emission-reducing system of the present embodiment 1, the air for introducing in compensated with air unit is replaced by oxygen Gas, passes through the compensated with air unit compensation after oxygen generating plant prepares oxygen to circulating flue gas, adjusts containing for circulating flue gas Oxygen amount concentration reaches 16%.In the case of the contrast, equipment investment increases, and power consumption increases.That is, O need to be injected with existing2's Boiler smoke circulation (oxygen-enriched combusting) system is compared, and can save equipment (including making oxygen by air separation equipment) investment about 20%~30%, Power consumption can save about 8-15%.
As a comparison, the present invention changes the temperature of the air that compensated with air unit is introduced, no on the basis of embodiment 1 Heating will be mixed with heat smoke in the cold air introducing cycle flue of ambient temperature, and remaining structure is as embodiment 1.Should When operation causes to enter circulating line, cause circulating flue gas temperature to reduce, humidity is improved, acid dew-point temperature is reduced to, is easily made Become boiler preheater and partial fume pipeline cold end corrosion, affect the stable operation of system.With the correlation technique scheme (by cold sky Gas is introduced directly into the technical scheme of circulating line) to compare, the emission-reducing system of the present invention can save air preheater and flue gas recirculation subtracts The pipeline corrosion protection expense about 30% of amount unit.
As a comparison, the emission-reducing system thermal efficiency by the emission-reducing system of the present invention with no low-level (stack-gas) economizer is compared, point Analysis is obtained, and the emission-reducing system after the present invention arranges low-level (stack-gas) economizer can improve boiler thermal output about 1%~3%, reduce flue gas Amount about 10%~15%.
The above, the only specific embodiment of the present invention, but protection scope of the present invention is not limited thereto, and any Those familiar with the art the invention discloses technical scope in, change or replacement can be readily occurred in, should all be contained Cover within protection scope of the present invention.Therefore, protection scope of the present invention described should be defined by scope of the claims.

Claims (9)

1. a kind of underload fire coal boiler fume amount/nitrogen oxides emission-reducing system, including the gas cleaning unit of coal-burning boiler, its It is characterised by:Also include flue gas recirculation decrement unit, between the cleaner and desulphurization plant of the gas cleaning unit Circulation port is opened up on connecting pipe, the smoke inlet of the flue gas recirculation decrement unit is connected with the circulation port, outlet flue and combustion The air intake connection of coal burning boiler;Flue gas shunting after the dedusting of part is recycled to as combustion-supporting gas in boiler, reaches flue gas The purpose of amount decrement discharge.
2. a kind of underload fire coal boiler fume amount/nitrogen oxides emission-reducing system according to claim 1, its feature exists In:The flue gas recirculation decrement unit includes circulating line, loop control valve and circulating fan, the circulating line enter cigarette Mouthful it is connected with the circulation port, outlet flue is connected with the air intake of coal-burning boiler, the loop control valve and circulating fan It is arranged on the circulating line.
3. a kind of underload fire coal boiler fume amount/nitrogen oxides emission-reducing system according to claims 1 or 2, which is special Levy and be:The emission-reducing system also includes compensated with air unit, and the compensated with air unit is to the flue gas recirculation decrement unit Make-up air in the dedusting flue gas of middle bypassing circulation, adjusts the mixing cigarette after the make-up air of the air intake for entering coal-burning boiler Oxygen content in gas is 15%~21%.
4. a kind of underload fire coal boiler fume amount/nitrogen oxides emission-reducing system according to claim 3, its feature exists In:The compensated with air unit includes to compensate pipeline, compensating control valve door and heater, the gas outlet of the compensation pipeline and institute State the circulating line connection of dedusting flue gas in flue gas recirculation decrement unit;The heater is arranged on the compensation pipeline, plus Hot-air;The compensating control valve door is arranged on the compensation pipeline.
5. a kind of underload fire coal boiler fume amount/nitrogen oxides emission-reducing system according to claim 4, its feature exists In:The emission-reducing system also includes oxygen concentration automatic adjustment unit, and the oxygen concentration automatic adjustment unit includes controller And oxygen concentration sensor, the collection terminal of the oxygen concentration sensor is arranged at the smoke inlet of flue gas recirculation decrement unit, Outfan is connected with the input of the controller;The outfan of the controller is controlled with the compensation of the compensated with air unit The control end connection of the loop control valve of the control end of valve and flue gas recirculation decrement unit;
Oxygen concentration sensor collection enters the oxygen density value of the circulating flue gas of flue gas recirculation decrement unit, and export to Controller;Controller is according to the oxygen density value of the circulating flue gas, the oxygen content value of default mixed flue gas and coal-burning boiler Combustion-supporting gas total amount, obtain the circulating flue gas flow of flue gas recirculation decrement unit and the compensation airstream of compensated with air unit Amount, and the unlatching according to the circulating flue gas flow and make-up air flow control and regulation compensating control valve door and loop control valve Amount, so as to adjust to circulating flue gas flow and make-up air flow.
6. a kind of underload fire coal boiler fume amount/nitrogen oxides emission-reducing system according to claim 4, its feature exists In:The emission-reducing system also includes make-up air thermostat unit, and the make-up air thermostat unit includes that temperature is passed Sensor and controller;The collection terminal of the temperature sensor is arranged on the pipeline of heater outlet in the compensated with air unit On, outfan is connected with the input of the controller;The outfan of the controller is connected with the control end of the heater; Air temperature value after the temperature sensor collection heating, and export to controller;When the air temperature value that controller is received Less than the circulating flue gas in default flue gas recirculation decrement unit in controller dew point temperature value when, controller control heater Improve heating intensity and improve air themperature;Conversely, when air temperature value is higher than the dew point temperature of default circulating flue gas in controller During angle value, controller control heater reduces heating intensity and reduces air themperature.
7. a kind of underload fire coal boiler fume amount/nitrogen oxides emission-reducing system according to claim 3, its feature exists In:The emission-reducing system also includes blender, and the blender is arranged on the dedusting flue gas in the flue gas recirculation decrement unit Circulating line on, the gas outlet of the compensated with air unit is connected with the blender;The air of circulating flue gas and compensation exists After mixing in blender, boiler is entered back into.
8. a kind of underload fire coal boiler fume amount according to claim 1,2,4,5,6 or 7/nitrogen oxides reduce discharging system System, it is characterised in that:The gas cleaning unit of the coal-burning boiler includes cleaner unit and desulfurizing tower, on the exhanst gas outlet of boiler It is sequentially connected the cleaner unit and desulfurizing tower;Wherein, also include low-level (stack-gas) economizer, the connecting pipe between boiler and cleaner unit Upper connection low-level (stack-gas) economizer, reclaims to the heat of boiler smoke.
9. a kind of underload fire coal boiler fume amount/nitrogen oxides emission-reducing system according to claim 8, its feature exists In:The gas cleaning unit of the coal-burning boiler also includes chimney, and the chimney is connected to the purifying smoke of the desulfurizing tower and goes out On mouth.
CN201610987345.XA 2016-11-09 2016-11-09 Flue gas volume/nitric oxide emission reduction system of low-load coal-fired boiler Pending CN106439796A (en)

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