Background technology
Industrial discharge combustion product gases is one of primary pollution source causing atmosphere pollution, and main atmosphere pollution comprises NOx and SOx.For the improvement of NOx in combustion product gases and SOx, developed multiple flue gas pollutant both at home and abroad and removed device.To different fuel, the atmosphere pollution producing after burning is also slightly identical.To gas fuel, the pollutant after burning is mainly NOx.In coal, owing to containing sulphur, in the flue gas after coal burning, main pollutant is SOx and NOx.Therefore to the main pollutant control measure of combustion of natural gas flue gas, being denitration, is desulphurization denitration to the main pollutant control measure of coal burning and gas burning.
Reduce NOx discharge in combustion product gases and mainly contain two kinds of measures.The one, in control combustion process, the generation of NOx, comprises low NOx combusting technology etc.; The 2nd, the NOx that burning is generated processes, i.e. gas denitrifying technology.Typical gas denitrifying technology has SCR(Selective Catalytic Reduction) and SNCR(Selective Non-Catalytic Reduction) two kinds.Wherein SCR technology is very remarkable to NOx control effect in flue gas, is the most ripe denitration technology, has obtained commercial Application widely.SCR technology refers under the effect of uniform temperature and catalyst, reacts and generate " selective " N2 and the H2O of nontoxic pollution-free with the NOx in flue gas.Reducing agent can be hydrocarbons (as methane, propylene), NH3, urea etc.Commercial Application be mainly ammoniacal liquor, liquefied ammonia, be secondly urea.
In industry at present, applying maximum SCR catalyst is carrier mainly with TiO2 greatly, with V
2o
5or V
2o
5-WO
3/ V
2o
5-MO
3for active component.Because vanadium Titanium series catalyst typical activity temperature range is 290-430 ℃, SCR reactor mostly is middle temperature reactor, and position is generally before electric precipitation.Because flue gas does not carry out dedusting, so high concentrate dust and SO
2easily cause and reduce in catalyst poisoning and service life.If SCR reactor can be arranged on to the low-temperature space after electric precipitation, will greatly improve the life-span of catalyst, reduce investment and operating cost.
The core of low-temperature SCR technology is low-temperature SCR catalyst.Have at present report to propose the low-temperature denitration catalyst of two kinds of forms, a kind of is TiO
2for carrier, another kind of for take active carbon as carrier.Wherein the active temperature of low-temperature SCR catalyst is generally 80-300 ℃.The development of low temperature catalyst is that the exploitation of low-temperature SCR technology is laid a good foundation.Utilize low-temperature SCR technology, the life-span of catalyst will be significantly improved, and size SCR reactor and flue can reduce, thereby reduce denitrating system floor space.Low temperature SCR denitration technology can be widely used in take the NOx of combustion product gases in the technical process such as electric power, metallurgy and building materials industry that natural gas or coal is fuel and reduces discharging.
But, adopt low-temperature SCR technology also to have significant shortcoming.Because the activity of the specific activity middle temperature catalyst of low temperature catalyst is low, this makes in Combined Cycle Unit, to adopt in SCR technology the escaping of ammonia very serious under cryogenic conditions.Because ammonia has certain toxicity, there is comparatively strict requirement in country to the discharge of ammonia in Air Pollutant Emission.For the environmental problem of avoiding the escaping of ammonia to bring, need the reaction unit for a kind of novel low-temperature denitration of low-temperature SCR technological development and reduction the escaping of ammonia badly.
The main method that reduces SOx in coal combustion flue gas also has two kinds of measures.A Desulphurization of fuels, as by Techniques For Reducing sulfur contents in fuel such as coal washing, selexol process, thereby reduces the SOx growing amount in combustion product gases.Another kind of be that the SOx in combustion product gases is carried out to post processing, i.e. flue gas desulfurization technique.Typical flue gas desulfurization technique can be divided into calcium base, magnesium base, amino sulfur removal technology according to the desulfurization absorbent difference adopting, and at present most widely used is calcium-based desulfurization technique, and principle is by calcium-base absorbing agent, to react with SOx to generate gypsum.From absorption mechanism, analyze, calcium-base absorbing agent absorbs SO
2be gas-solid reaction, reaction speed is slower, and reaction not exclusively, and absorbent utilization rate is low; Need the processes such as it is levigate, atomization, circulation to improve the utilization rate of absorbent for this reason, but will make whole system energy consumption increase.In addition,, although adopt calcium-base absorbing agent can produce gypsum, from current domestic application present situation, most desulfurated plaster is substantially gone up all and is abandoned, and realizes and recycling.Utilize ammonia to absorb SO
2be gas-liquid reaction or gas-solid/liquid/gas reactions, reaction rate is fast, reacts completely, and absorbent utilization rate is high, and desulfuration efficiency is also high.Only, with regard to absorption process, compare with calcium base absorption equipment, ammonia absorption equipment small volume, energy consumption is also low.Many companies both domestic and external have all developed ammonia-process desulfurization technique separately.Wherein domestic south of the River environmental protection limited company has applied its ammonia-process desulfurization technique in a plurality of engineerings, has verified feasibility and the technical advantage of the ammonia process of desulfurization.Utilize the ammonia process of desulfurization SOx can be converted into ammonium sulfate, and can by acidification reaction, further generate other compound, widened the product line of the ammonia process of desulfurization, there is higher economy.Meanwhile, the ammonia process of desulfurization also can remove a certain amount of NOx.It is reported, ammonia-method denitration efficiency is generally in 30% left and right, relatively low, cannot meet the requirement of the pollutant emission standard of domestic increasingly stringent, need carry out in conjunction with other denitration technology the control of NOx discharge.
In addition, directly discharge and in combustion product gases, contain a large amount of waste heats, if can be when realizing pollutant removing Mist heat recovering, will significantly promote efficiency of energy utilization.
Utility model content
The technical problem that the utility model solves is, provides a kind of low-temperature multi-effect flue gas processing device to realize the improvement of low-temperature flue gas pollutant and the recovery of low-temperature flue gas waste heat.
For achieving the above object, the utility model adopts following technical scheme.
A flue gas processing device, it comprises interconnective low-temperature denitration section and low temperature exhaust heat exhausting section; Wherein, this low-temperature denitration section from left to right sets gradually smoke inlet, ammonia-spraying grid, catalyst layer and the first demister, by the first demister, is connected with low temperature exhaust heat exhausting section; Be connected with low-temperature denitration section position top of this low temperature exhaust heat exhausting section, sets gradually spraying layer, the second demister and exhanst gas outlet from down to up, and this low temperature exhaust heat exhausting section is connected with low-temperature denitration section and ,Gai pond, pond is set below position and is provided with delivery port.
A flue gas processing device, it comprises interconnective low-temperature denitration section and ammonia process of desulfurization section; Wherein, this low-temperature denitration section from left to right sets gradually smoke inlet, ammonia-spraying grid, catalyst layer and the first demister, by demister, is connected with ammonia process of desulfurization section; This ammonia process of desulfurization section is connected with low-temperature denitration section above position, set gradually from down to up spraying layer, the second demister and exhanst gas outlet, be connected with low-temperature denitration section position below of this ammonia process of desulfurization section arranges ,Gai pond, pond and is provided with in delivery port ,Gai pond and is provided with oxidation air distributor pipe; This spraying layer is divided into high-order spraying layer and low level spraying layer; High-order spraying layer is connected with water pipe, shower water; Low level spraying layer is connected with pond, and spray is containing ammonia solution.
Between second demister and exhanst gas outlet of this ammonia process of desulfurization section, be provided with low temperature exhaust heat exhausting section, this low temperature exhaust heat exhausting section top is connected with the second demister, and be provided with up the second spraying layer, bottom is provided with the second pond, between this second spraying layer and the second pond, sidewall is connected exhanst gas outlet, and the 3rd demister is set in this exhanst gas outlet; This second pond is provided with the second delivery port.
The beneficial effects of the utility model are: the utility model provides the solution of low-temperature flue gas integrated treatment, provided a kind of low-temperature multi-effect flue gas processing device, utilize this low-temperature multi-effect flue gas processing device, under the effect of low-temperature denitration section low-temperature denitration catalyst, realize the low-temperature denitration of flue gas; Utilize the ammonia process of desulfurization can realize removing of SOx in flue gas; Utilize spraying cooling to realize flue gas waste heat recovery.The utility model can realize that low-temperature flue gas pollutant is controlled and low temperature exhaust heat recovery simultaneously, wherein desulfuration efficiency and denitration efficiency all can > 90%.
The specific embodiment
As shown in Fig. 1 and Fig. 4, be first embodiment of this case.
A kind of low-temperature multi-effect flue gas processing device of the present utility model, it comprises interconnective low-temperature denitration section 1 and low temperature exhaust heat exhausting section 2; Wherein, this low-temperature denitration section 1 from left to right sets gradually smoke inlet 11, ammonia-spraying grid 12, catalyst layer 13 and the first demister 14, by the first demister 14, is connected with low temperature exhaust heat exhausting section 2; This low temperature exhaust heat exhausting section 2 is connected with low-temperature denitration section 1 above position, set gradually from down to up spraying layer 4, the second demister 5 and exhanst gas outlet 15, be connected with low-temperature denitration section 1 position below of this low temperature exhaust heat exhausting section 2 arranges 6 ,Gai ponds 6, pond and is provided with delivery port 61.
The present embodiment is generally applicable to the low-temperature multi-effect flue gas processing that the smoke evacuation of combustion and steam combined cycle power plant waste heat boiler is processed.Pollutant in the smoke evacuation of combustion and steam combined cycle waste heat boiler is mainly NOx, and general need be carried out denitration and process the NOx discharge standard that can reach national regulation.In addition, because combined cycle waste heat boiler exhaust gas temperature is generally at 90 ℃, after low temperature exhaust heat exhausting section, flue-gas temperature is down to approximately 30 ℃-60 ℃, and the heat that utilizes heat pump that shower water is absorbed utilizes, and can reach the target of energy-saving and emission-reduction.
Idiographic flow is: the flue gas coming from waste heat boiler back-end ductwork enters low-temperature denitration section 1 from smoke inlet 11, and flue-gas temperature is about 90 ℃.Low-temperature denitration section is provided with ammonia-spraying grid 12 and catalyst layer 13.The ammonia that ammonia-spraying grid is 5% by concentration enters catalyst layer after spraying into and mixing with flue gas.Catalyst layer is low-temperature denitration catalyst, and can multilayer setting.Under catalyst effect, the NOx in flue gas is by NH<sub TranNum="103">3</sub>be reduced to nitrogen G&W.Flue gas after denitration enters low temperature exhaust heat exhausting section 2 after the first demister 14.Low temperature exhaust heat exhausting section 2 is provided with spraying layer 4, the second demister 5 and pond 6.Spraying layer 4 can be put mode for laminates.Water as spray medium from spraying layer 4 ejection and flue gas adverse current contact heat-exchanging from low-temperature denitration section, and the ammonia of escaping by spray-absorption low-temperature denitration section.The shower water of heating falls into the pond 6 that is arranged on bottom after sedimentation.Pond 6 is provided with delivery port, can utilize water pump that the hot water in pond 6 is extracted out and sent heat pump to carry out UTILIZATION OF VESIDUAL HEAT IN.
The technique of embodiment mono-is: it at least comprises: a. low-temperature denitration, is characterized in that removing nitrogen oxide by cryogenic selective reduction technique; B. low temperature exhaust heat reclaims; It is characterized in that low-temperature denitration and low temperature exhaust heat reclaim carries out successively, and low temperature exhaust heat reclaims and adopts spraying cooling method Mist heat recovering also to reduce the amount of ammonia slip in denitration flue gas.
In low-temperature denitration process, flue gas flow rate is generally at 2m/s-6m/s, and in low temperature exhaust heat removal process, flue gas flow rate is generally at 1m/s-6m/s.Smoke inlet temperature is 80-180 ℃, and exhanst gas outlet temperature is 30-60 ℃.
As shown in Fig. 2 and Fig. 5, be second embodiment of this case.
A kind of low-temperature multi-effect flue gas processing device of the present utility model, it comprises interconnective low-temperature denitration section 1 and ammonia process of desulfurization section 3; Wherein, this low-temperature denitration section 1 from left to right sets gradually smoke inlet 11, ammonia-spraying grid 12, catalyst layer 13 and the first demister 14, by the first demister 14, is connected with ammonia process of desulfurization section 3; This ammonia process of desulfurization section 3 is connected with low-temperature denitration section 1 above position, set gradually from down to up spraying layer 4, the second demister 5 and exhanst gas outlet 15, be connected with low-temperature denitration section 3 position below of this ammonia process of desulfurization section 1 arranges pond 6, this pond 6 is provided with in delivery port 61,Gai pond and is provided with oxidation air distributor pipe 7; This spraying layer 4 is divided into high-order spraying layer 41 and low level spraying layer 42; High-order spraying layer is connected with water pipe, shower water; Low level spraying layer is connected with pond, and spray is containing ammonia solution.
The present embodiment is generally applicable to the low-temperature multi-effect flue gas processing device that coal-burning boiler smoke evacuation is processed.Main gas pollutant in coal-burning boiler smoke evacuation has NOx and SOx.Ammonia can be removed respectively NOx and SOx as the reducing agent of denitration and the absorbent of desulfurization.The present embodiment adopts the scheme of substep NO_x removal and SOx.
Idiographic flow is: the flue gas coming from boiler back end ductwork enters low-temperature denitration section after dedusting, and flue-gas temperature is between 110 ℃-180 ℃.Low-temperature denitration section is provided with ammonia-spraying grid 12 and catalyst layer 13.The ammonia that ammonia-spraying grid 12 is 5% by concentration enters catalyst layer 13 after spraying into and mixing with flue gas.Catalyst layer 13 is low-temperature denitration catalyst.Under catalyst effect, the NOx in flue gas is by NH<sub TranNum="110">3</sub>be reduced to nitrogen G&W.Flue gas after denitration enters ammonia process of desulfurization section 3 after the first demister 14.Ammonia process of desulfurization section 3 is provided with spraying layer 4, the second demister 5 and pond 6.Spraying layer 4 is multilayer arrangement in short transverse.Be arranged in high-order spraying layer and using water as spray liquid, Main Function is to reduce the escaping of ammonia.It is spray liquid containing ammonia solution that the spraying layer that is arranged in low level be take in pond, and Main Function is to carry out desulphurization reaction.Spray liquid from spraying layer ejection contacts with the flue gas adverse current from low-temperature denitration section, and the ammonia of escaping by spray-absorption low-temperature denitration section.Spray liquid falls into the pond that is arranged on bottom after sedimentation.Pond is provided with outlet, can utilize water pump that the solution in solution pool pond is extracted out and sent spraying layer spray to carry out desulfurization.Solution pool bottom is provided with oxidation air distributor pipe, and air absorbs SO with ammonia after entering solution pool by oxidation air distributor pipe<sub TranNum="111">2</sub>the ammonium sulfite reaction generating generates ammonium sulfate, can carry out separation by centrifuge and send after ammonium sulfate crystallization.Flue gas after desulfurization is discharged after the second demister is removed the drop that flue gas carries.
The technique of embodiment bis-is: it at least comprises: a. low-temperature denitration, removes nitrogen oxide by cryogenic selective reduction technique; B. the ammonia process of desulfurization, adopts ammonia to carry out desulfurization as absorbent; It is characterized in that low-temperature denitration and the ammonia process of desulfurization carry out successively.
In low-temperature denitration process, flue gas flow rate is at 2m/s-6m/s, and in sweetening process, flue gas flow rate is at 3m/s-8m/s.Smoke inlet temperature is 110-180 ℃, and exhanst gas outlet temperature is 50-100 ℃.
As shown in Figure 3 and Figure 6, be the 3rd embodiment of this case.
A kind of low-temperature multi-effect flue gas processing device of the present utility model, it comprises interconnective low-temperature denitration section 1 and ammonia process of desulfurization section 3; Wherein, this low-temperature denitration section 1 from left to right sets gradually smoke inlet 11, ammonia-spraying grid 12, catalyst layer 13 and the first demister 14, by the first demister 14, is connected with ammonia process of desulfurization section 3; This ammonia process of desulfurization section 3 is connected with low-temperature denitration section 1 above position, set gradually from down to up spraying layer 4, the second demister 5 and exhanst gas outlet 15, be connected with low-temperature denitration section 3 position below of this ammonia process of desulfurization section 1 arranges pond 6, this pond 6 is provided with in delivery port 61,Gai pond and is provided with oxidation air distributor pipe 7; This spraying layer 4 is divided into high-order spraying layer 41 and low level spraying layer 42; High-order spraying layer is connected with water pipe, shower water; Low level spraying layer is connected with pond, and spray is containing ammonia solution.
Between second demister 5 and exhanst gas outlet 15 of this ammonia process of desulfurization section 3, be provided with low temperature exhaust heat exhausting section 2, these low temperature exhaust heat exhausting section 2 tops are connected with the second demist 5 devices, and be provided with up the second spraying layer 8, bottom is provided with the second pond 9, between this second spraying layer 8 and the second pond 9, sidewall is connected exhanst gas outlet 15, interior the 3rd demister 10 that arranges of this exhanst gas outlet 15.This second pond 9 is provided with the second delivery port 91.
The present embodiment is generally applicable to the low-temperature multi-effect flue gas processing device of coal-burning boiler smoke evacuation.Compare with embodiment bis-, the present embodiment has increased waste heat recovery section, and desulfurization fume waste heat is reclaimed.Idiographic flow is: the flue gas coming from boiler back end ductwork enters low-temperature denitration section 1 by smoke inlet 11 after dedusting, and flue-gas temperature is between 110 ℃-180 ℃.Low-temperature denitration section 1 is provided with ammonia-spraying grid 12 and catalyst layer 13.The ammonia that ammonia-spraying grid 12 is 5% by concentration enters catalyst layer 13 after spraying into and mixing with flue gas.Catalyst layer 13 is low-temperature denitration catalyst.Under catalyst effect, the NOx in flue gas is by NH<sub TranNum="118">3</sub>be reduced to nitrogen G&W.Flue gas after denitration enters ammonia process of desulfurization section 3 after the first demister 14.Ammonia process of desulfurization section 4 is provided with spraying layer 4, the second demister 5 and pond 6.Spraying layer 4 is multilayer arrangement in short transverse.Be arranged in high-order high-order spraying layer 41 and using water as spray liquid, Main Function is to reduce the escaping of ammonia.Being arranged in the low level spraying layer 42Yi pond 6 of low level is spray liquid containing ammonia solution, and Main Function is to carry out desulphurization reaction.Spray liquid from spraying layer 4 ejections contacts with the flue gas adverse current from low-temperature denitration section, and the ammonia of escaping by spray-absorption low-temperature denitration section.Spray liquid falls into the pond 6 that is arranged on bottom after sedimentation.Pond 6 is provided with outlet 61, can utilize water pump that the solution extraction in pond 6 is sent into low level spraying layer 42 sprays and carry out desulfurization.Solution pool bottom is provided with oxidation air distributor pipe 7, and air absorbs SO with ammonia after entering solution pool by oxidation air distributor pipe 7<sub TranNum="119">2</sub>the ammonium sulfite reaction generating generates ammonium sulfate, carries out separation send after ammonium sulfate crystallization by centrifuge.Flue gas after desulfurization enters low temperature exhaust heat exhausting section 2 after the second demister 5 is removed the drop that flue gas carries.Low temperature exhaust heat exhausting section 2 is provided with the second spraying layer 8, the second pond 9 and the 3rd demister 10.From the flue gas of ammonia process of desulfurization section and the water contact heat-exchanging of the second spraying layer 8 ejections, flue gas is discharged through the 3rd demister 10 after supercooling.The shower water of heating is deposited to the second pond 9 of bottom.The second pond 9 is provided with the second delivery port 91, can utilize water pump that the hot water in the second pond 9 is extracted out and sent heat pump to carry out UTILIZATION OF VESIDUAL HEAT IN.
The technique of embodiment tri-is:, at least comprise: a. low-temperature denitration, removes nitrogen oxide by cryogenic selective reduction technique; B. the ammonia process of desulfurization, adopts ammonia to carry out flue gas desulfurization as absorbent; C. low temperature exhaust heat reclaims; It is characterized in that low-temperature denitration, the ammonia process of desulfurization and low temperature exhaust heat reclaim carries out successively, and low temperature exhaust heat reclaims and adopts spraying cooling method Mist heat recovering also to reduce the amount of ammonia slip in denitration flue gas.
In low-temperature denitration process, flue gas flow rate is at 2m/s-6m/s, and in sweetening process, flue gas flow rate is at 3m/s-8m/s, and in low temperature exhaust heat removal process, flue gas flow rate is at 1m/s-6m/s.Smoke inlet temperature is 110 ℃-180 ℃, and exhanst gas outlet temperature is 30-60 ℃.
Above-mentioned the first embodiment is applicable to the flue gas processing and the waste heat recovery that contain single a small amount of pollutant and comparatively cleaning that the fuel combustions such as natural gas produce.Adopt above-mentioned the first embodiment, temperature is that the flue gas of 80 ℃-180 ℃ enters the low-temperature denitration section in low-temperature multi-effect flue gas processing device from smoke inlet.In low-temperature denitration section, the NOx in flue gas carries out following reaction with the ammonia of ammonia-spraying grid ejection under the effect of low-temperature denitration catalyst:
4NH
3+4NO+O
2→4N
2+6H
2O
4NH
3+2NO
2+O
2→3N
2+6H
2O
Flue gas after the denitration of low-temperature denitration section enters low temperature exhaust heat exhausting section through the connectivity part of low-temperature denitration section and low temperature exhaust heat exhausting section.Low temperature exhaust heat exhausting section is provided with spraying layer, and shower water contacts with flue gas adverse current after denitration after spraying layer ejection, washs on the one hand the ammonia of escaping in flue gas, and shower water absorbs the waste heat of flue gas on the other hand.Shower water declines and falls into the spray pond that is arranged in low temperature exhaust heat exhausting section bottom.Flue gas is separating device after exhanst gas outlet.In exhanst gas outlet, be provided with demister, can reduce the water that flue gas carries.Technical scheme A has also realized the recovery of waste heat when realizing higher denitration efficiency, and the waste heat of recovery can further utilize by heat pump techniques.
Embodiment bis-be applicable to produce with coal or wet goods fuel combustion the flue gas that contains multiple a large amount of pollutants process.Adopt above-described embodiment two, temperature is that the flue gas of 110 ℃-180 ℃ enters the low-temperature denitration section in low-temperature multi-effect flue gas processing device from smoke inlet.In low-temperature denitration section, spray into excess of ammonia, the NOx in flue gas under the effect of low-temperature denitration catalyst with ammonia carry out following reaction:
4NH
3+4NO+O
2→4N
2+6H
2O
4NH
3+2NO
2+O
2→3N
2+6H
2O
Flue gas after the denitration of low-temperature denitration section enters desulfurization section and utilizes remaining ammonia to carry out the ammonia process of desulfurization, and the reaction of generation is:
SO
2+2NH
3+H
2O→(NH
4)
2SO
3
SO
2+(NH
4)
2SO
3+H
2O→2NH
4HSO
3
NH
3+NH
4HSO
3→(NH
4)
2SO
3
2(NH
4)
2SO
3+O
2→2(NH4)
2SO
4
Ammonia process of desulfurization section is provided with spraying layer, and spray liquid contacts with flue gas adverse current after denitration after spraying layer ejection, absorbs the ammonia in flue gas, reduces the escape of ammonia.Spray liquid declines and falls into the solution pool that is arranged in desulfurization section bottom.Flue gas is separating device after exhanst gas outlet.In exhanst gas outlet, be provided with demister, can reduce the drop amount that flue gas carries.Ammonia process of desulfurization desulfuration efficiency is general > 90%, denitration efficiency only has an appointment 30%, and the ammonia process of desulfurization and low-temperature SCR technology are combined and can make up the shortcoming that ammonia process of desulfurization denitration efficiency is low, can realize > 90% desulfuration efficiency and denitration efficiency.
Embodiment tri-be applicable to produce with coal or wet goods fuel combustion the flue gas that contains multiple a large amount of pollutants process.Adopt above-described embodiment three, temperature is that the flue gas of 110 ℃-180 ℃ enters the low-temperature denitration section in low-temperature multi-effect flue gas processing device from smoke inlet.In low-temperature denitration section, spray into excess of ammonia, the NOx in flue gas under the effect of low-temperature denitration catalyst with ammonia carry out following reaction:
4NH
3+4NO+O
2→4N
2+6H
2O
4NH
3+2NO
2+O
2→3N2+6H
2O
Flue gas after the denitration of low-temperature denitration section enters desulfurization section and utilizes remaining ammonia to carry out the ammonia process of desulfurization, and the reaction of generation is:
SO
2+2NH
3+H
2O→(NH
4)
2SO
3
SO
2+(NH
4)
2SO
3+H
2O→2NH
4HSO
3
NH
3+NH
4HSO
3→(NH
4)
2SO
3
2(NH
4)
2SO
3+O
2→2(NH
4)
2SO
4
Ammonia process of desulfurization section is provided with spraying layer, and spray liquid contacts with flue gas adverse current after denitration after spraying layer ejection, absorbs the ammonia in flue gas, reduces the escape of ammonia.Spray liquid declines and falls into the solution pool that is arranged in desulfurization section bottom.Flue gas after the ammonia process of desulfurization carries out waste heat recovery after demist.Waste heat recovery still adopts the method for spraying cooling, and shower water is rear and flue gas heat exchange from spraying layer ejection, realizes waste heat recovery, and further reduces the ammonia amount of escaping.Flue gas is separating device after exhanst gas outlet.In exhanst gas outlet, be provided with demister, the drop amount of carrying to reduce flue gas.Utilize embodiment tri-both can realize > 90% desulfuration efficiency and denitration efficiency, also can realize low temperature exhaust heat and reclaim, the waste heat wherein reclaiming can further utilize by heat pump techniques.