CN106705090A - SCR system based on flue gas waste heat gradient utilization and SCR denitration method - Google Patents

SCR system based on flue gas waste heat gradient utilization and SCR denitration method Download PDF

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Publication number
CN106705090A
CN106705090A CN201611109905.8A CN201611109905A CN106705090A CN 106705090 A CN106705090 A CN 106705090A CN 201611109905 A CN201611109905 A CN 201611109905A CN 106705090 A CN106705090 A CN 106705090A
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China
Prior art keywords
scr
heat exchanger
flue
bypass
flue gas
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Pending
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CN201611109905.8A
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Chinese (zh)
Inventor
郑文广
何胜
李乾坤
刘沛奇
邹阳军
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Huadian Electric Power Research Institute Co Ltd
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Huadian Electric Power Research Institute Co Ltd
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Priority to CN201611109905.8A priority Critical patent/CN106705090A/en
Publication of CN106705090A publication Critical patent/CN106705090A/en
Pending legal-status Critical Current

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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23JREMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J15/00Arrangements of devices for treating smoke or fumes
    • F23J15/003Arrangements of devices for treating smoke or fumes for supplying chemicals to fumes, e.g. using injection devices
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23JREMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J15/00Arrangements of devices for treating smoke or fumes
    • F23J15/006Layout of treatment plant
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23JREMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J15/00Arrangements of devices for treating smoke or fumes
    • F23J15/02Arrangements of devices for treating smoke or fumes of purifiers, e.g. for removing noxious material
    • F23J15/022Arrangements of devices for treating smoke or fumes of purifiers, e.g. for removing noxious material for removing solid particulate material from the gasflow
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23JREMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J15/00Arrangements of devices for treating smoke or fumes
    • F23J15/06Arrangements of devices for treating smoke or fumes of coolers
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23JREMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J15/00Arrangements of devices for treating smoke or fumes
    • F23J15/08Arrangements of devices for treating smoke or fumes of heaters
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23JREMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J2215/00Preventing emissions
    • F23J2215/10Nitrogen; Compounds thereof
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23JREMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J2217/00Intercepting solids
    • F23J2217/10Intercepting solids by filters
    • F23J2217/102Intercepting solids by filters electrostatic
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23JREMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J2219/00Treatment devices
    • F23J2219/10Catalytic reduction devices
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00Combustion technologies with mitigation potential
    • Y02E20/30Technologies for a more efficient combustion or heat usage

Abstract

The invention relates to an SCR system based on flue gas waste heat gradient utilization and an SCR denitration method. The SCR system based on flue gas waste heat gradient utilization structurally comprises a boiler and a denitration device arranged in a boiler flue. The denitration device comprises an SCR first catalyst layer and an SCR follow-up catalyst layer. The SCR first catalyst layer and the SCR follow-up catalyst layer are sequentially arranged in the flowing direction of flue gas in the boiler flue. The SCR system further comprises an SCR denitration heat exchanger system. The SCR denitration heat exchanger system is arranged between the SCR first catalyst layer and the SCR follow-up catalyst layer and is used for lowering the temperature of the flue gas in the flue. The principle of 'temperature matching and gradient utilization' is adopted by flue gas waste heat on the tail portion of the boiler, and the overall net coal consumption rate is decreased. Meanwhile, efficient operation of the SCR system is achieved, a flow field inside the SCR system is optimized, and the blocking danger of an air preheater is greatly lowered.

Description

SCR system and SCR denitration method based on fume afterheat cascade utilization
Technical field
The present invention relates to a kind of flue gas denitrification system and method, particularly a kind of SCR based on fume afterheat cascade utilization System and SCR denitration method.
Background technology
With the development of power industry, the energy-saving and emission-reduction requirement of fossil-fired unit is increasingly urgent, for boiler tail cigarette Gas residual-heat utilization technology, has substantial amounts of patented technology to be formed, portion of techniques engineer applied, but currently existing scheme fails to realize energy The temperature counterpart of amount, cascade utilization, the amount of energy saving of tail flue gas UTILIZATION OF VESIDUAL HEAT IN have the space of further lifting;In recent years with country The strict demand of environmental protection policy, the implementation of large quantities of fossil-fired unit minimum discharge transformations, part fossil-fired unit after transformation Occur in that amount of ammonia slip is bigger than normal, SO3 conversion ratios are higher, the low problem of SCR denitration system efficiency, hydrogen sulfate ammonia is in air preheater Heat accumulating element surface deposits, and causes air preheater heat accumulating element to block, and air preheater resistance is significantly increased, has a strong impact on The safety of unit, economical operation.Under above-mentioned background, patent combination fossil-fired unit super low energy consumption of the present invention, minimum discharge Transformation background, with reference to produced problem after preliminary project transformation, considers boiler tail flue gas UTILIZATION OF VESIDUAL HEAT IN and SCR denitration System high efficiency runs, it is proposed that systematic solution, forms patented technology of the present invention.
The content of the invention
The technical problems to be solved by the invention are to provide a kind of SCR system and SCR denitration method, by patent of the present invention In practicing for engineering project, principle of the boiler tail flue gas waste heat by " temperature counterpart, cascade utilization ", maximum limit are realized The effect that improve boiler tail flue gas UTILIZATION OF VESIDUAL HEAT IN of degree, reduces overall net coal consumption rate;Realize SCR system simultaneously Effec-tive Function, optimizes the flow field inside SCR system, reduces amount of ammonia slip, from SO3Formation mechanism angle reduces SO3Life Cheng Liang, reduces deposition of the hydrogen sulfate ammonia on air preheater heat accumulating element surface, greatly mitigates what air preheater was blocked Risk.
The ratio resistance of dust in flue gas can be changed by patent working of the present invention, the efficiency of dust collection of electric precipitation is improved;It is logical Reduction temperature is crossed, flying dust is to SO in enhancing flue gas3Absorption, reduce flue gas in SO3Discharge;Tail temperature is reduced, flue gas is reduced Flow velocity, improves dedusting, desulphurization system desulfuration efficiency, while reducing air-introduced machine consumption rate.
Patented technology of the present invention, it is island integrated using mechanism, therrmodynamic system equivalent enthalpy drop mechanism, environmental protection with reference to fume afterheat Removing sulfuldioxide mechanism, takes into full account the coupling between tripartite system, efficiently solves existing influence unit safety, economical operation Problem.
The present invention solves the technical scheme that is used of above-mentioned technical problem:
A kind of SCR system based on fume afterheat cascade utilization, its structure includes boiler and is arranged in boiler flue Denitrification apparatus, the denitrification apparatus include the catalyst layers of SCR first and SCR subsequent catalyst oxidant layer, the catalyst layers of the SCR first Prolong the flue gas flow direction in boiler flue with SCR subsequent catalyst oxidant layer to set gradually;Also include SCR denitration heat exchanger system, it is described SCR denitration heat exchanger system is arranged between the catalyst layers of SCR first and SCR subsequent catalyst oxidant layer the cigarette for being used to reduce in flue Temperature degree.
The mechanism of SCR system is that to complete denitration reaction, the second layer and the above are catalyzed the Main Function of ground floor catalyst The Main Function of oxidant layer is to eliminate the unreacted ammonia of ground floor catalyst, but it has been investigated that, after ground floor catalyst, SCR system flow field deviation is larger, and amount of ammonia slip increases, and ammonia in flue gas nitrogen mol ratio further increases, and causes SCR efficiency relatively low; Simultaneously in SCR ground floor catalyst, because ammonia density is higher, it is suppressed that SO2It is converted into SO3Efficiency, by system research table It is bright, SO2It is converted into SO3The main second layer and third layer catalyst in denitrating system is carried out, and temperature is to SO2It is converted into SO3Play Conclusive effect.Therefore by arranging that SCR heat exchanger systems not only reduce second layer catalyst inlet temperature, reduce SO2It is converted into SO3Efficiency, by flow field simulation analysis shows SO2It is converted into SO3Conversion ratio reduction about 60-70%, Er Qietong Heating surface arrangement is crossed, the flow field of second layer catalyst inlet is optimized, is shown by analog result, flow field concentration deviation reduction More than 20%, the concentration distribution of ammonia nitrogen is optimized, amount of ammonia slip is reduced, SCR system reaction efficiency is improve, efficiency is improved about 3%-5%.The escaping of ammonia and SO of SCR denitration system are reduced by such scheme3Generation after, directly reduce sulfureous in flue gas acid The generation of hydrogen ammonia, directly reduces deposition of the hydrogen sulfate ammonia on air preheater heat accumulating element surface, it is to avoid air preheater Block, it is ensured that unit safety, reliability, economical operation.
Further, also including heater system, the SCR denitration heat exchanger system connects heater system.Reducing SO2It is converted into SO3Efficiency and improve SCR system reaction efficiency while, by denitration SCR heat exchanger systems, by heater system System condensate is introduced, and heats the condensate, reduces the amount of drawing gas, and improves the acting ability of high-temperature steam, is efficiently reduced unit and is supplied Electric coal consumption, realizes the cascade utilization of energy.
Further, the flue after the denitrification apparatus is divided into main road flue and bypass flue, is set on the main road flue It is the air preheater of boiler inlet air heating to be equipped with;Bypass heat exchanger system is provided with the bypass flue, the bypass is changed Hot device system connects heater system.Still there is flue gas after denitrification apparatus temperature higher to be suitable for heating boiler air inlet but turn Change the inefficient situation for occurring that heat exchange is insufficient, be the effective utilization for further improving energy, flue is separated into bypass It is used to heat heater system afterwards.
Preferably, the bypass heat exchanger system includes the first bypass heat exchanger and the second bypass heat exchanger, described the The flue gas flow direction that one side pipeline heat exchanger and the second bypass heat exchanger prolong in boiler flue sets gradually;The heater system includes Number high-pressure heater, No. two high-pressure heaters and No. three high-pressure heaters, a high-pressure heater, No. two hyperbaric heatings Heating-up temperature in device and No. three high-pressure heaters is reduced successively;The SCR denitration heat exchanger system and the first bypass heat exchanger No. two high-pressure heaters are connected respectively, and the second bypass heat exchanger connects No. three high-pressure heaters.By temperature counterpart principle, SCR denitration heat exchanger system and the first bypass heat exchanger are adapted to heat No. two condensates of high-pressure heater, and the first bypass is changed Hot device flue-gas temperature after heat-shift is still adapted to No. three condensates of high-pressure heater of heating, therefore bypasses heat exchanger first Setting the second bypass heat exchanger afterwards further carries out heat exchange.
Preferably, also including low cryogenic heat exchanger and cold wind heat exchanger system, the low cryogenic heat exchanger is arranged on sky After air preheater and bypass heat exchanger system, the low cryogenic heat exchanger connection cold wind heat exchanger system, the cold wind heat exchanger System and air preheater prolong boiler air inlet flow direction and set gradually.The flue-gas temperature after air preheater and bypass heat exchanger system Further reduce, but still the air-flow before air inlet preheater can be preheated, further realize the cascade utilization of energy.
Preferably, the cold wind heat exchanger system includes cold First air heat exchanger and cold Secondary Air heat exchanger, it is described cold First air heat exchanger and cold Secondary Air heat exchanger connect low cryogenic heat exchanger and air preheater respectively.The heat of flue gas is low Warm heat exchanger is swapped, and respectively by cold First air heat exchanger, cold Secondary Air heat exchanger to cold First air and cold Secondary Air Heated, improved heat exchanger effectiveness and efficiency of energy utilization, while improving air preheater heat accumulating element cold junction temperature, entered one Step mitigates air preheater accumulation of heat original paper blockage problem.
Preferably, also include electric cleaner, after the electric cleaner is arranged on low cryogenic heat exchanger.Through too low low temperature Flue-gas temperature is reduced to 95 DEG C or so after heat exchanger, and electric dust removing system fly ash resistivity is reduced at such a temperature, improves electric precipitation The efficiency of dust collection of device, additionally, due to flue-gas temperature close to flue gas acid dew point temperature, the SO being in a liquid state3Easily by the dust in flue gas Grain absorption, so as to be removed by electric cleaner, reaches cooperation-removal SO3Effect.
Preferably, the low cryogenic heat exchanger uses aqueous medium, the flue gas flow direction in the aqueous medium flow direction and flue Conversely.It is to maximally utilize flue gas heat in last low cryogenic heat exchanger, using counter-flow arrangement mode.
A kind of SCR denitration method, its step is:
S1) boiler smoke is by anti-with SCR ground floor catalyst layers after denitration ammonia-gas spraying device and SCR denitration mixing arrangement Should;
S2) cooling treatment is carried out through the reacted flue gases of S1;
S3 the flue gas after) being processed through S2 reacts with SCR subsequent catalysts oxidant layer.
Preferably, temperature range of the flue gas before and after with the reaction of SCR ground floors catalyst layer in the step S1 and S2 330 DEG C to 400 DEG C are, the cooling scope for the treatment of of lowering the temperature in the step S2 is 20 DEG C to 50 DEG C.In the temperature range condition Lower SO2It is converted into SO3Conversion ratio can be reduced and reach 70% and SCR system reaction efficiency brings up to 5%.
The present invention compared with the existing technology has advantages below and effect:
1st, by setting denitrating system heat exchanger, the first bypass heat exchanger, the second bypass heat exchanger, low cryogenic heat exchanger system System, according to equivalent enthalpy drop theoretical foundation in thermodynamics, it then follows cascaded utilization of energy principle, by boiler smoke according to its Temperature Distribution Trend, point four parts carry out UTILIZATION OF VESIDUAL HEAT IN, and depth has reclaimed fume afterheat, reduces exhaust gas temperature, reduces heat loss due to exhaust gas, High efficiente callback fume afterheat, improves boiler efficiency, realizes by the fume afterheat step profit of " temperature counterpart, cascade utilization " principle With.
2nd, more traditional SCR denitration system ratio, optimizes the flow field of second layer catalyst inlet flue gas, reduces ammonia nitrogen concentration point Cloth deviation, improves the efficiency of SCR denitration system, reduces the flue-gas temperature of second layer catalyst inlet, reduces the escaping of ammonia Amount;Significantly reduce SO2It is converted into SO3Efficiency, reduce the output of hydrogen sulfate ammonia, reduce air preheater accumulation of heat unit The risk that part burn into is blocked.
3rd, into the flue-gas temperature reduction of electric cleaner, fly ash resistivity is effectively reduced, improves the dedusting effect of electric cleaner Rate, additionally, due to flue-gas temperature close to flue gas acid dew point temperature, the SO being in a liquid state3Easily adsorbed by the dust granules in flue gas, from And removed by electric cleaner, reach cooperation-removal SO3Effect, it is to avoid the acid corrosion of follow-up environmental protection equipment.
4th, coupled by between tail flue gas system and the therrmodynamic system of steam turbine, the partial heat heating of flue gas heat-exchange unit Steam turbine condensate system, reduces steam turbine system high pressure and draws gas and part low-pressure pumping steam, significantly improves the economy of unit operation Property.
5th, flue-gas temperature reduction, exhaust gas volumn is reduced, and reduces air-introduced machine power consumption;The reduction of desulfuration absorbing tower entrance flue gas temperature, Desulfuration absorbing tower entrance spray water flux is reduced, exhaust gas volumn in desulfuration absorbing tower is entered in addition and is reduced, improve the desulfurization of desulphurization system Efficiency.
6th, the cold First air of air preheater entrance, cold Secondary Air are heated by low cryogenic system, improves air preheater and store Thermal element cold junction temperature, it is to avoid the risk that air preheater cold-end air heat accumulating element burn into is blocked.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing The accompanying drawing to be used needed for having technology description is 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 Other accompanying drawings are obtained with according to these accompanying drawings.
Fig. 1 is structural representation of the invention.
Label declaration:
1st, boiler 2, SCR denitration spray ammonia system
3rd, SCR denitration blender 4, guiding device
5th, SCR flow straightening grids 6, the catalyst layer of SCR system first
7th, second and third catalyst layer of SCR denitration heat exchanger system 8, SCR system
9th, air preheater 10, cold First air heat exchanger
11st, the bypass of cold Secondary Air heat exchanger 12, first heat exchanger
13rd, the second bypass heat exchanger 14, low cryogenic heat exchanger
15th, 16, high-pressure heater of electric cleaner
17th, 18, No. three high-pressure heaters of No. two high-pressure heaters
19th, 20, No. four low-pressure heaters of oxygen-eliminating device
21st, 22, No. six low-pressure heaters of No. five low-pressure heaters
Specific embodiment
With reference to embodiment, the present invention is described in further detail, following examples be explanation of the invention and The invention is not limited in following examples.
Embodiment 1:
As shown in figure 1, the present embodiment includes boiler 1 and the denitration ammonia-gas spraying device being sequentially connected along the back-end ductwork of boiler 1 2nd, SCR denitration mixing arrangement 3, SCR flues guiding device 4, SCR flow straightening grids 5, the heat exchange of SCR the first catalyst layers 6, SCR denitration Device system 7, SCR system second and third catalyst layer 8, air preheater 9, low cryogenic heat exchanger system 14, electric dust removing system 15, Air-introduced machine, desulfuration absorbing tower, chimney and heater system.Heater system includes No. six low-pressure heatings set according to water (flow) direction The low-pressure heater 21, four of device 22, five low-pressure heater 20, the hyperbaric heating of high-pressure heater 18, two of oxygen-eliminating device 19, three Device 17 and a high-pressure heater 16.The present embodiment arranges that SCR denitration exchanges heat behind the first catalyst layer of SCR denitration system 6 Device system 7, wherein SCR denitration heat exchanger system 7 are connected with the water inlet conduit and delivery port pipeline of the second high-pressure heater 17 Composition;In parallel on air preheater 9 to draw a bypass flue, wherein bypass flue passes through regulation by the first bypass heat exchanger 12 Valve and connecting line are connected composition with the water inlet conduit and delivery port pipeline of the second high-pressure heater 17 respectively;Bypass flue The second bypass heat exchanger 13 is in series with after first bypass heat exchanger 12, the second bypass heat exchanger 13 passes through regulating valve and connecting line Respectively composition is connected with the water inlet conduit and delivery port pipeline of the 3rd high-pressure heater 18.Flue gas temperature before denitration is entered exists 330 DEG C -400 DEG C, flue gas is by after the catalyst layer of SCR denitration system first, flue-gas temperature remains unchanged substantially;Then flue gas enters Enter to SCR denitration system heat exchanger 7, after denitrating system heat exchanger is by 20 DEG C -50 DEG C of flue-gas temperature reduction, flue-gas temperature is about Between for 280-380 DEG C, and then the second catalyst layer entrance flow field structure can be improved, reduce flow field velocity distribution bias and Ammonia nitrogen concentration distribution bias, reduce amount of ammonia slip, improve SCR system efficiency.Entered by reducing SCR system second layer catalyst Mouth flue-gas temperature, significantly reduces SO2It is converted into SO3Efficiency, reduce sulfate of ammoniac, hydrogen sulfate ammonia generation after in air preheater Heat accumulating element surface deposits.The height of steam bleeding system is reduced by the structure design of SCR denitration heat exchanger system 7 and bypass flue Temperature, the high steam amount of drawing gas, improve the acting ability of therrmodynamic system, realize fume afterheat according to temperature counterpart, cascade utilization Principle efficiently utilize.
Cloth sets low cryogenic heat exchanger 14 between air preheater 9 and electric cleaner 15, and the low cryogenic heat exchanger 14 is distinguished It is connected with cold First air heat exchanger 10, cold Secondary Air heat exchanger 11, is made up of corresponding circulating line, valve and control system Closed system.Recirculated water absorbs flue gas heat in low cryogenic heat exchanger 14, in cold First air heat exchanger 10 and cold secondary after intensification Wind heat exchanger 11 heats cold First air and cold Secondary Air respectively, and part substitutes conventional steam steam air heater, improves efficiency of energy utilization, The heat accumulating element cold junction temperature of air preheater 3 is improved simultaneously, it is to avoid the accumulation of heat original paper blockage problem of air preheater 9.Flue gas is entering Temperature is reduced to 95 DEG C or so before entering electric cleaner 15, reduces electric dust removing system fly ash resistivity, improves removing for electric cleaner 15 Dirt efficiency, additionally, due to flue-gas temperature close to flue gas acid dew point temperature, the SO being in a liquid state3Easily inhaled by the dust granules in flue gas It is attached, so as to be removed by electric cleaner 15, reach cooperation-removal SO3Effect.By low low-level (stack-gas) economizer reduction flue-gas temperature, change Become the ratio resistance characteristic of ash in flue gas, improve dust-collecting efficiency, improve the efficiency of dust collection of electric precipitation, while flue gas flow is reduced, drop Low air-introduced machine consumption rate, improves Unit Economic benefit.
Furthermore, it is necessary to explanation, the specific embodiment described in this specification, is named the shape of its parts and components Title etc. can be with difference.The equivalent or simple change that all constructions according to described in inventional idea of the present invention, feature and principle are done, wraps Include in the protection domain of patent of the present invention.Those skilled in the art can be to described specific implementation Example is made various modifications or supplement or is substituted using similar mode, without departing from structure of the invention or surmounts this Scope as defined in the claims, all should belong to protection scope of the present invention.

Claims (10)

1. a kind of SCR system based on fume afterheat cascade utilization, including boiler and the denitrification apparatus being arranged in boiler flue, It is characterized in that:The denitrification apparatus include the catalyst layers of SCR first and SCR subsequent catalyst oxidant layer, the catalyst of the SCR first The flue gas flow direction that layer and SCR subsequent catalyst oxidant layer are prolonged in boiler flue sets gradually;Also include SCR denitration heat exchanger system, institute State during SCR denitration heat exchanger system is arranged between the catalyst layers of SCR first and SCR subsequent catalyst oxidant layer and is used to reduce flue Flue-gas temperature.
2. the SCR system based on fume afterheat cascade utilization according to claim 1, it is characterised in that:Also include heating Device system, the SCR denitration heat exchanger system connects heater system.
3. the SCR system based on fume afterheat cascade utilization according to claim 2, it is characterised in that:The denitration dress The flue for postponing is divided into main road flue and bypass flue, and the air preheat of promising boiler inlet air heating is set on the main road flue Device;Bypass heat exchanger system is provided with the bypass flue, the bypass heat exchanger system connects heater system.
4. the SCR system based on fume afterheat cascade utilization according to claim 3, it is characterised in that:The bypass is changed Hot device system includes the first bypass heat exchanger and the second bypass heat exchanger, the first bypass heat exchanger and the second bypass heat exchanger The flue gas flow direction prolonged in boiler flue sets gradually;The heater system includes high-pressure heater, No. two hyperbaric heatings Device and No. three high-pressure heaters, the heating in a high-pressure heater, No. two high-pressure heaters and No. three high-pressure heaters Temperature is reduced successively;The SCR denitration heat exchanger system and the first bypass heat exchanger connect No. two high-pressure heaters respectively, described Second bypass heat exchanger connects No. three high-pressure heaters.
5. the SCR system based on fume afterheat cascade utilization according to claim 3, it is characterised in that:Also include low Warm heat exchanger and cold wind heat exchanger system, after the low cryogenic heat exchanger is arranged on air preheater and bypass heat exchanger system, The low cryogenic heat exchanger connection cold wind heat exchanger system, the cold wind heat exchanger system and air preheater prolong boiler inlet air flow To setting gradually.
6. the SCR system based on fume afterheat cascade utilization according to claim 5, it is characterised in that:The cold wind is changed Hot device system includes cold First air heat exchanger and cold Secondary Air heat exchanger, the cold First air heat exchanger and cold Secondary Air heat exchanger Low cryogenic heat exchanger and air preheater are connected respectively.
7. the SCR system based on fume afterheat cascade utilization according to claim 5, it is characterised in that:Also removed including electricity Dirt device, after the electric cleaner is arranged on low cryogenic heat exchanger.
8. the SCR system based on fume afterheat cascade utilization according to claim 5, it is characterised in that:The low temperature Heat exchanger uses aqueous medium, and the aqueous medium flow direction is opposite with the flue gas flow direction in flue.
9. SCR denitration method according to claim 1, its step is:
S1) boiler smoke with SCR ground floors catalyst layer after denitration ammonia-gas spraying device and SCR denitration mixing arrangement by reacting;
S2) cooling treatment is carried out through the reacted flue gases of S1;
S3 the flue gas after) being processed through S2 reacts with SCR subsequent catalysts oxidant layer.
10. SCR denitration method according to claim 9, it is characterised in that:In the step S1 and S2 flue gas with SCR Temperature range before and after the reaction of ground floor catalyst layer is 330 DEG C to 400 DEG C, the cooling model for the treatment of of lowering the temperature in the step S2 Enclose is 20 DEG C to 50 DEG C.
CN201611109905.8A 2016-12-02 2016-12-02 SCR system based on flue gas waste heat gradient utilization and SCR denitration method Pending CN106705090A (en)

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CN109084320A (en) * 2018-08-01 2018-12-25 中国电建集团江西省电力设计院有限公司 Flue gas recirculation system based on bypass heat exchanger
CN109210956A (en) * 2018-10-19 2019-01-15 上海孚旺炉业有限公司 It is a kind of industry furnace flue gas exhaust heat step condensation utilize and desulfurization and denitrification integral system
CN109945227A (en) * 2019-05-08 2019-06-28 北京国电龙源环保工程有限公司 Reduce system and process that exhaust gas temperature inhibits air preheater low-temperature corrosion
CN110404378A (en) * 2019-07-12 2019-11-05 华电电力科学研究院有限公司 A kind of Multifunctional smoke SO3Remove experimental rig and its working method
US11850550B2 (en) 2019-12-18 2023-12-26 Sumitomo SHI FW Energia Oy Arrangement for and a method of operating a steam boiler system

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