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 PDFInfo
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- 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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- 239000003546 flue gas Substances 0.000 title claims abstract description 64
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 61
- 238000000034 method Methods 0.000 title claims abstract description 10
- 239000002918 waste heat Substances 0.000 title abstract description 5
- 239000003054 catalyst Substances 0.000 claims abstract description 41
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 27
- 239000003517 fume Substances 0.000 claims description 16
- 238000010438 heat treatment Methods 0.000 claims description 12
- 238000006243 chemical reaction Methods 0.000 claims description 9
- 239000007800 oxidant agent Substances 0.000 claims description 9
- 230000001590 oxidative effect Effects 0.000 claims description 9
- 239000012736 aqueous medium Substances 0.000 claims description 4
- 238000001816 cooling Methods 0.000 claims description 4
- 239000000779 smoke Substances 0.000 claims description 3
- 238000005507 spraying Methods 0.000 claims description 3
- 230000002035 prolonged effect Effects 0.000 claims 2
- 230000005611 electricity Effects 0.000 claims 1
- 239000003245 coal Substances 0.000 abstract description 3
- 230000000903 blocking effect Effects 0.000 abstract 1
- 230000003247 decreasing effect Effects 0.000 abstract 1
- 229910021529 ammonia Inorganic materials 0.000 description 12
- 239000000428 dust Substances 0.000 description 11
- 239000007789 gas Substances 0.000 description 9
- 230000009467 reduction Effects 0.000 description 8
- 238000005516 engineering process Methods 0.000 description 7
- 238000006477 desulfuration reaction Methods 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 239000002253 acid Substances 0.000 description 5
- BIGPRXCJEDHCLP-UHFFFAOYSA-N ammonium bisulfate Chemical compound [NH4+].OS([O-])(=O)=O BIGPRXCJEDHCLP-UHFFFAOYSA-N 0.000 description 5
- 230000007246 mechanism Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 230000009466 transformation Effects 0.000 description 4
- 238000009825 accumulation Methods 0.000 description 3
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 239000010881 fly ash Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 235000019504 cigarettes Nutrition 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 239000004744 fabric Substances 0.000 description 2
- 239000008187 granular material Substances 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 229940095054 ammoniac Drugs 0.000 description 1
- 239000002956 ash Substances 0.000 description 1
- 230000000740 bleeding effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 206010022000 influenza Diseases 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
- 238000000844 transformation Methods 0.000 description 1
- 238000010977 unit operation Methods 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/003—Arrangements of devices for treating smoke or fumes for supplying chemicals to fumes, e.g. using injection devices
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/006—Layout of treatment plant
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/02—Arrangements of devices for treating smoke or fumes of purifiers, e.g. for removing noxious material
- F23J15/022—Arrangements of devices for treating smoke or fumes of purifiers, e.g. for removing noxious material for removing solid particulate material from the gasflow
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/06—Arrangements of devices for treating smoke or fumes of coolers
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/08—Arrangements of devices for treating smoke or fumes of heaters
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J2215/00—Preventing emissions
- F23J2215/10—Nitrogen; Compounds thereof
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J2217/00—Intercepting solids
- F23J2217/10—Intercepting solids by filters
- F23J2217/102—Intercepting solids by filters electrostatic
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J2219/00—Treatment devices
- F23J2219/10—Catalytic reduction devices
-
- Y—GENERAL 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/30—Technologies for a more efficient combustion or heat usage
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
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
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.
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| CN201611109905.8A CN106705090A (en) | 2016-12-02 | 2016-12-02 | SCR system based on flue gas waste heat gradient utilization and SCR denitration method |
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Application publication date: 20170524 |