CN105233682A - Technique for purifying flue gas - Google Patents
Technique for purifying flue gas Download PDFInfo
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- CN105233682A CN105233682A CN201510780767.5A CN201510780767A CN105233682A CN 105233682 A CN105233682 A CN 105233682A CN 201510780767 A CN201510780767 A CN 201510780767A CN 105233682 A CN105233682 A CN 105233682A
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Abstract
The invention discloses a technique for purifying flue gas. The technique comprises first-level wet process purification and second-level absorption purification; flue gas from a coal-fired boiler or a gas-fired boiler is subjected to first-level wet process treatment, and then the purified flue gas enters a purifying flue; second-level absorption purification is utilized to retreat the purified flue gas acquired from the first-level wet process purification. The technique comprises a first-level wet process purification device and a second-level absorption purification device, wherein the first-level wet process purification device comprises a flue, an absorbing tower and a purifying flue which are connected in turn; the second-level absorption purification device is respectively connected with the purifying flue and the absorbing tower; the second-level absorption purification device comprises a catalyst layer; a catalyst adopted by the catalyst layer comprises a carrier, an active component and a promoter. According to the technique provided by the invention, pollutants, such as grout material gas liquid, dust and aerosol, carried by the purifying flue gas are effectively treated; substances, such as sulfinic acid nitrites in the flue gas, forming PM2.5, are effectively prevented from being discharged to the atmosphere; secondary pollution caused by the purifying fuel gas to the atmosphere is effectively prevented.
Description
Technical field
The present invention relates to flue gas technical field, be specifically related to a kind of flue gas purifying technique.
Background technology
Flue gas, particularly coal-fired flue-gas, containing a large amount of flue dust, sulfide, itrated compound and heavy metal (particularly mercury).Flue gas as inadequate without purified treatment or degree for the treatment of, then easily forms the pollutions such as floating dust, acid rain and heavy metal, serious environment pollution.In every profession and trade, power industry is the rich and influential family of China's Air Pollutant Emission, particularly China is raw material with fossil fuels such as fire coals thermal power generation proportion is comparatively large, and the discharge of the flue dust of its discharge, sulfur dioxide, nitrogen oxide, mercury and/or carbon dioxide all occupies national every profession and trade prostatitis.The pollutant emission standard of therefore promulgating national each period first for be power industry.
At present, the International or National emission request for pollutant is more and more stricter.Before 1980, " Industrial " three Waste " discharge tentative standard " (GBJ4-1973) regulation that thermal power plant performs, smoke discharge amount, by chimney height restriction, utilizes high chimney emission countermeasure efficiency of dust collection to be 80% ~ 90% can be up to standard." Emission standards of air pollutants for coal-fired " (GB13223-1991) regulation of 1991, as long as dust concentration reaches 2000mg/Nm3, as long as even≤3300mg/Nm3 can be up to standard." fossil-fuel power plant atmospheric pollutant emission standard " (GB13223-1996) in 1996 improve discharge standard, and dust exhausting concentration limit value is brought up to 200 ~ 600mg/Nm3." fossil-fuel power plant atmospheric pollutant emission standard " (GB13223-2003) in 2003 further increase discharge standard, and it specifies that newly-built fired power generating unit dust exhausting concentration performs 50mg/Nm3 standard, and sulfur dioxide emissioning concentration performs 400mg/Nm3.After this regulation is put into effect, the whole nation starts to start on a large scale desulfurization equipment.
Except national standard, provincial standard is launched respectively in each province and city, the discharge of pollutant in strict restriction flue gas, such as Beijing provincial standard DB11/139-2002 " boiler pollutant comprehensive discharge standard " regulation, new construction of coal-fired boiler dust exhausting concentration performs 30mg/Nm3 standard, and sulfur dioxide emissioning concentration performs 50mg/Nm3 standard.Provincial standard, far away higher than the national standard of the same period to the restriction of pollutant in flue gas.
In addition, national standard also has the strict trend limiting pollutant emission in flue gas further." fossil-fuel power plant atmospheric pollutant emission standard " secondary exposure draft of new revision sends, and first meeting in 2011 is promulgated and performed.According to the regulation of this suggestion original text, it strictly limits the discharge of each pollutant component further, and the newly-increased restriction to discharged nitrous oxides.Meanwhile, in " 12 " planning, also clear and definite nitrogen oxide overall control will be carried out in China.Since then, do not have equipment for denitrifying flue gas, then the nitrogen oxides in effluent being discharged to air can exceed the restriction of national standard, the carrying out that impact is produced.Therefore in existing flue-gas purification equipment, increase purification of nitrogen oxides device, become industry inexorable trend.
Although the content of mercury is only within the scope of 0.012 ~ 33mg/L in raw coal, due to a large amount of burnings of coal, the mercury total amount overflowed every year in the whole world from fire coal reaches more than 3000t.U.S. EPA is estimated, the mercury of US Coal-fired Power Plants boiler emission in 1999 is about 75t, and wherein about 48t has entered in air.A large amount of mercury, by dry deposition or wet deposition polluted-water, forms the methyl mercury (MeHg) of severe toxicity, can circulate again and enter human body, cause great harm to the mankind in fish and other biological body after enrichment after biological respinse.The research of American science association finds, takes in the harm that can cause nerve to a certain degree and development by the fish of Methylmercury pollution Riverfish and seafood.In December, 2000, U.S. EPA is announced to start the discharge controlling coal-fired plant boiler mercury in flue gas.
China also strengthens the restriction to mercury in flue gas discharge gradually.On May 11st, 2010, the General Office of the State Council issues " instruction about advancing the work of atmosphere pollution groupcontrol to improve region air quality ", the wherein content of existing " building the multi-pollutant Collaborative Control show-how engineerings such as fired power generating unit flue gas desulfurization, denitration, dedusting and the removal of mercury ".It is expected to, national standard will make strict restriction to the discharge of mercury in flue gas in the near future.
Therefore, the enterprise, particularly coal-burning power plant of existing generation coal-fired flue-gas, must realize coal-fired flue-gas dust-removing, desulphurization and denitration, demercuration and smoke evacuation operation.In existing purifying coal-fired flue gas process, be all adopt separate unit to realize dedusting, desulphurization and denitration, demercuration and smoke evacuation operation respectively.Wherein:
The technique of dedusting mainly contains dry dust removal and wet dust removal technique.The main representative technique of dry dust removal is filtering technique or electrostatic precipitation technique.
In filtering technique, the most typical with sack cleaner, bag-type dusting utilizes sock filtration dust.Sack cleaner is a kind of dry type dust filtration device, and it is applicable to trap tiny, dry, non-fiber dust.Filter bag adopts the filter cloth of weaving or nonwoven felt to become, the filtration of fabric is utilized to filter dusty gas, when dusty gas enters sack cleaner, large, the heavy dust of particle, because the effect of gravity settles down, fall into ash bucket, containing the gas compared with fine dusts when by filtrate, dust, by detention, makes gas be purified.But along with dust gathering at filter material surface, the resistance of deduster can be made too high, cause the air quantity of dust pelletizing system significantly to decline.Therefore, after the resistance of deduster reaches certain numerical value, timely deashing, can not destroy bonding layer during deashing, otherwise efficiency of dust collection can decline, this just causes dust removal operation not carry out continuously simultaneously.
The operation principle of electrostatic precipitation utilizes high voltage electric field that flue gas is ionized, the dust in air-flow charged under electric field action with flow separation.The negative pole of electrostatic precipitator is made up of the plain conductor of different section shape, is sparking electrode, and positive pole is made up of the metallic plate of different geometries, is collecting electrode.The performance of electrostatic precipitator is subject to the impact of three factors such as dust characteristic, equipment structure and flue gas flow rate.The ratio resistance of dust is the index evaluating electric conductivity, and it has direct impact to efficiency of dust collection.Ratio resistance is too low, grit is difficult to remain on collecting electrode, it is caused to return to air-flow, ratio resistance is too high, the grit electric charge arriving collecting electrode is not easily released, between knoisphere, coating-forming voltage gradient can produce partial breakdown and electric discharge phenomena, and these situations all can cause efficiency of dust collection to decline, and therefore electrostatic precipitator is stricter to equipment requirement.
Wet dust removal is commonly called as " water dedusting ", and it makes dusty gas and liquid (water) close contact, utilizes the inertial collision of water droplet and particle and other devices acting on arrested particles or particle is increased.According to the purification mechanism of wet scrubber, it roughly can be divided into seven classes: (1) gravity spray washer, (2) cyclone scrubber, (3) self-excitation spray jet scrubber, (4) scrubber, (5) padding washing device, (6) Venturi scrubber, (7) mechanical induction spray jet scrubber.In existing technique, for saving space, reducing the considerations such as cost, wet dust removal is how integrated with desulfurization unit.
Flue gas desulfurization (Fluegasdesulfurization is called for short FGD), in FGD technology, divides by the kind of desulfurizing agent, can be divided into following Lung biopsy: with CaCO
3calcium method based on (lime stone), the magnesium processes based on MgO, with Na
2sO
3based on sodium method, with NH
3based on ammonia process, the organic alkaline process based on organic base.The commercial technologies generally used in the world is calcium method, and proportion is more than 90%.
By absorbent and desulfurization product, the dry and wet state in sweetening process can be divided into again wet method, dry method and half-dried (half is wet) method to desulfur technology.
Wet FGD technology mainly uses lime stone (CaCO
3), lime (CaO) or sodium carbonate (Na
2cO
3) etc. slurries make washing agent, in reaction tower, flue gas is washed, thus removing flue gas in oxysulfide.Wet FGD technique has the history of 50 years, and after constantly Improvement and perfection, Technical comparing is ripe, and there is desulfuration efficiency high (90% ~ 98%), unit capacity is large, and coal adaptability is strong, and operating cost lower and byproduct such as easily to reclaim at the advantage.According to the statistics of EPA (EPA), the whole America thermal power plant adopts in wet desulfurizer, and wet type lime method accounts for 39.6%, and limestone-based process accounts for 47.4%, and two methods account for 87% altogether; Dual alkali accounts for 4.1%, and sodium carbonate method accounts for 3.1%.Countries in the world (as German, Japanese etc.), in large thermal power plant, more than 90% adopts wet type lime/lime stone-gypsum method flue gas desulfurization technique flow process.Although this method has, desulphurization reaction speed is fast, equipment simple, desulfuration efficiency advantages of higher, and ubiquity seriously corroded, operation and maintenance cost are high and easily cause secondary pollution problems.
Desulfurization absorption and the product process of dry method FGD technology are all carried out under dry state, this method have discharge without sewage spent acid, equipment corrosion degree is lighter, the advantages such as flue gas is high without cigarette temperature after significant hypothermal, purification in purification process, be beneficial to chimney exhaust diffusion, secondary pollution is few, but it is low to there is desulfuration efficiency, the problems such as reaction speed is comparatively slow, equipment is huge.
Semidry method FGD technology refers to desulfurizing agent desulfurization in the dry state, regenerate under wet condition (as washing regenerating active carbon flow process), or desulfurization under wet condition, under dry state, processes the flue gas desulfurization technique of desulfurization product (as spray drying process).Particularly desulfurization under wet condition, under dry state, process the semidry method of desulfurization product, with its advantage that existing wet desulphurization reaction speed is fast, desulfuration efficiency is high, have again that dry method is discharged without sewage spent acid, an easy-to-handle advantage of desulfurization afterproduct and be subject to people and pay close attention to widely.
In desulfurization process, only have and be removed in acid nitrogen oxide, NO, N
2the non-acid gases such as O are still present in flue gas, and the nitrogen oxide more than 90% in flue gas exists with the form of NO, therefore must be further processed the nitrogen oxide in flue gas.Because NO is insoluble in water, therefore simple washing method can not be used to the process of NO.The main technique of denitrating flue gas has: oxidizing process, O
3oxidative absorption method, ClO
2oxidation-reduction method, selective catalytic reduction and SNCR method.
The principle of flue gas oxidizing process denitration is, with oxidant, NO is oxidized to NO
2, the NO of generation
2again with water or alkaline solution absorption, thus realize denitration.
O
3oxidative absorption method O
3nO is oxidized to NO
2, then absorb with water, the product HNO of this method
3liquid need through concentration, and O
3need high voltage to produce, invest and operating cost is high.
ClO
2oxidation-reduction method uses ClO
2nO is oxidized to NO
2, then use Na
2sO
3nO2 is reduced into N2 by the aqueous solution, and this method can be combined with the Wet Flue Gas Desulfurization Technique adopting NaOH as desulfurizing agent, the product Na of desulfurization
2sO
3can be used as NO again
2reducing agent.ClO
2the denitration rate of method can reach 95%, and can simultaneously desulfurization, but ClO
3higher with the price of NaOH, operating cost increases.
SNCR method (SNCR) does not use catalyst, in 850 ~ 1100 DEG C of temperature ranges, with reducing agent (NH3, urea), NOx is reduced to N
2.
Selective catalytic reduction (SCR) is denitration method for flue gas the most ripe at present, and it utilizes reducing agent (NH
3, urea) under metallic catalyst effect, within the scope of 400 ~ 800 DEG C optionally with NO
xreaction generates N
2and H
2o.
Summary of the invention
The object of the invention is to propose a kind of flue gas purifying technique, the nitrogen oxide in flue gas and sulfur oxides level significantly reduce by this technology utilization catalyst, decrease haze odds.
For reaching this object, the present invention by the following technical solutions:
A kind of flue gas purifying technique, it comprises one-level wet cleaning and secondary absorption purification, neat stress after the flue gas of coal-burning boiler or gas fired-boiler is carried out one-level wet cleaning process enters clean flue, and secondary absorption purification carries out reprocessing to the neat stress of gained in one-level wet cleaning; It comprises one-level Wet purifier and secondary absorption purifier, and one-level Wet purifier comprises interconnective flue, absorption tower and clean flue successively; Secondary absorption purifier is connected with absorption tower respectively with clean flue, and described adsorptive purifier comprises catalyst layer, and described catalyst layer comprises following component,
A) nano-TiO of 6%-20%
2the platinum cerium cobalt kalium composite oxides of load, the mol ratio Ti:Pt:Ce:Co:K of its each component is 1:(0.05-0.1): (0.05-0.1): (0.05-0.1): (0.05-0.1);
B) the ferrotitanium molybdenum composite oxides of the zirconium doping of 3%-8%, the mol ratio of Zr:Fe:Ti:Mo is (0.02-0.2): 1:(0.5-1): (0.5-1), described ferrotitanium molybdenum composite oxides possess the composite oxides crystallite system of Fe-O-Ti, Mo-O-Ti and Fe-O-Mo structure;
C) active carbon of surplus.
The present invention is by choosing specific components A and B component, this catalyst is made to produce cooperative effect, the treatment effeciency of this catalyst to nitrogen oxides in effluent and oxysulfide is made to reach close to 100%, effectively can administer the pollutants such as serum materials gas-liquid, dust and the aerosol carried secretly in neat stress, especially the mass emissions such as the cigarette sulfurous acid nitrite anions forming PM2.5 effectively can be stoped to enter air, effectively prevent neat stress from causing secondary pollution to air.
Detailed description of the invention
The present invention is described catalyst of the present invention by following embodiment.
Embodiment 1
Catalyst comprises following component,
A) nano-TiO of 10%
2the platinum cerium cobalt kalium composite oxides of load, the mol ratio Ti:Pt:Ce:Co:K of its each component is 1:0.1:0.1:0.1:0.1;
B) 5% zirconium doping ferrotitanium molybdenum composite oxides, the mol ratio of Zr:Fe:Ti:Mo is 0.1:1:1:1, and described ferrotitanium molybdenum composite oxides possess the composite oxides crystallite system of Fe-O-Ti, Mo-O-Ti and Fe-O-Mo structure;
C) active carbon of surplus.
Described catalyst is positioned over secondary absorption purifier.The flue gas purifying technique utilizing the present invention following processes the flue gas from coal-burning boiler: it comprises one-level wet cleaning and secondary absorption purification, neat stress after the flue gas of coal-burning boiler or gas fired-boiler is carried out one-level wet cleaning process enters clean flue, and secondary absorption purification carries out reprocessing to the neat stress of gained in one-level wet cleaning; It comprises one-level Wet purifier and secondary absorption purifier, and one-level Wet purifier comprises interconnective flue, absorption tower and clean flue successively; Secondary absorption purifier is connected with absorption tower respectively with clean flue.
Flue gas after treatment, the content of its nitrogen oxide and oxysulfide all reaches the indoor breathe air standard of GB, its content is all less than 0.05 milligram/cubic metre, be far smaller than the requirement of the Indoor Air Quality standards that GB/T18883-2002 specifies, the farther regulation far below GB13271-2001 emission standard of air pollutants for boilers.
Comparative example 1
Component A content 15%, not containing B component, all the other conditions are constant, and the value of nitrogen oxide and oxysulfide is all higher than 10 milligrams/cubic metre.
Comparative example 2
B component content 15%, not containing component A, all the other conditions are constant, and the value of nitrogen oxide and oxysulfide is all higher than 10 milligrams/cubic metre.
Above-described embodiment and comparative example illustrate, there is specific contact between several component of catalyst of the present invention, omit or replace wherein one or more, all can not reach the certain effects of the application, prove to which create cooperative effect.
Applicant states, the present invention illustrates catalyst of the present invention by above-described embodiment, but the present invention is not limited to above-mentioned catalyst, does not namely mean that the present invention must rely on above-mentioned detailed catalysts and could implement.Person of ordinary skill in the field should understand, any improvement in the present invention, to equivalence replacement and the interpolation of auxiliary element, the concrete way choice etc. of each raw material of product of the present invention, all drops within protection scope of the present invention and open scope.
Claims (1)
1. a flue gas purifying technique, it comprises one-level wet cleaning and secondary absorption purification, neat stress after the flue gas of coal-burning boiler or gas fired-boiler is carried out one-level wet cleaning process enters clean flue, and secondary absorption purification carries out reprocessing to the neat stress of gained in one-level wet cleaning; It comprises one-level Wet purifier and secondary absorption purifier, and one-level Wet purifier comprises interconnective flue, absorption tower and clean flue successively; Secondary absorption purifier is connected with absorption tower respectively with clean flue, and described adsorptive purifier comprises catalyst layer, and described catalyst layer comprises following component,
A) nano-TiO of 6%-20%
2the platinum cerium cobalt kalium composite oxides of load, the mol ratio Ti:Pt:Ce:Co:K of its each component is 1:(0.05-0.1): (0.05-0.1): (0.05-0.1): (0.05-0.1);
B) the ferrotitanium molybdenum composite oxides of the zirconium doping of 3%-8%, the mol ratio of Zr:Fe:Ti:Mo is (0.02-0.2): 1:(0.5-1): (0.5-1), described ferrotitanium molybdenum composite oxides possess the composite oxides crystallite system of Fe-O-Ti, Mo-O-Ti and Fe-O-Mo structure;
C) active carbon of surplus.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4187282A (en) * | 1976-02-12 | 1980-02-05 | Babcock-Hitachi K.K. | Process for treating a waste gas containing sulfur oxides |
| CN101411984A (en) * | 2008-11-27 | 2009-04-22 | 中国科学院生态环境研究中心 | Other transitional metals doped ferrotitanium composite oxides catalyst for selectively reducing nitrous oxides by ammonia |
| CN101721911A (en) * | 2008-10-31 | 2010-06-09 | 中国石油化工股份有限公司 | Composition for desorbing sulfur and nitrogen oxide in fume |
| CN202751950U (en) * | 2012-07-24 | 2013-02-27 | 徐州市龙泰臭氧设备制造有限公司 | Waste gas oxidation treatment system |
| CN103406021A (en) * | 2013-07-25 | 2013-11-27 | 昆明理工大学 | Method for removing phosphine through double liquid phases |
-
2015
- 2015-11-13 CN CN201510780767.5A patent/CN105233682A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4187282A (en) * | 1976-02-12 | 1980-02-05 | Babcock-Hitachi K.K. | Process for treating a waste gas containing sulfur oxides |
| CN101721911A (en) * | 2008-10-31 | 2010-06-09 | 中国石油化工股份有限公司 | Composition for desorbing sulfur and nitrogen oxide in fume |
| CN101411984A (en) * | 2008-11-27 | 2009-04-22 | 中国科学院生态环境研究中心 | Other transitional metals doped ferrotitanium composite oxides catalyst for selectively reducing nitrous oxides by ammonia |
| CN202751950U (en) * | 2012-07-24 | 2013-02-27 | 徐州市龙泰臭氧设备制造有限公司 | Waste gas oxidation treatment system |
| CN103406021A (en) * | 2013-07-25 | 2013-11-27 | 昆明理工大学 | Method for removing phosphine through double liquid phases |
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