CN104307330B - A kind of method absorbing nitrogen oxides of exhaust gas - Google Patents
A kind of method absorbing nitrogen oxides of exhaust gas Download PDFInfo
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- CN104307330B CN104307330B CN201410614888.8A CN201410614888A CN104307330B CN 104307330 B CN104307330 B CN 104307330B CN 201410614888 A CN201410614888 A CN 201410614888A CN 104307330 B CN104307330 B CN 104307330B
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Abstract
nullThe invention discloses a kind of method absorbing nitrogen oxides of exhaust gas，Including: waste gas is passed through oxidizing tower after O2 aoxidizes，The aluminium oxide of oxidizing tower filling modification is as catalyst，With steam, waste gas is heated to 20～100 DEG C，The oxygen in waste gas is made to react with NO，Reacted gas enters absorption tower and carries out Reducing and absorption reaction by bubbling and absorbing liquid，After reaction, gas is discharged by tower top，Waste gas processes through tertiary oxidation Reducing and absorption，Tail gas empties through exhaust port，Absorbing liquid is the mixed liquor of ammonium sulfite and ammonia，Mass content is 0.02～20%，Oxidizing tower 3 diameter 1m，High 3m bubble absorbing tower 4 diameter 0.4m，High 0.6m，Catalyst in oxidizing tower needs by aqueous slkali soaking 18～24h，It is washed with deionized water to neutrality，Use after drying under nitrogen or hydrogen shield，The method removal rate is high，Technique is easy to use.
Description
Technical field
The present invention relates to a kind of method absorbing nitrogen oxides of exhaust gas.
Background technology
Pollution Index in Air Nitric Oxides problem is day by day serious, and fuel combustion is NOXMain source, China has also formulated strict discharged nitrous oxides standard and has started to impose corresponding charges for disposing pollutants use, and the feasible gas denitrifying technology of high-efficiency and economic will have wide application market prospect.
Wet flue gas treatment technology is traditional fume treatment technology, and technical process is simple, invests less, high treating effect, and the absorbent being available for application is a lot.But wet flue gas denitration technology is made slow progress the most always, its main cause is that the character that flue gas is special.O in flue gas2Content is only 6～9%, NOxConcentration is relatively low, therefore NO in flue gasxOxidizability the lowest, i.e. in flue gas 90～the NO of 95%xFor NO, by NOxThe research of liquid phase reactor mechanism finds, NOxLiquid phase scrubbing be first to be proceeded to aqueous phase by gaseous state, this is mainly realized by gas absorption equilibrium in the solution, and absorption equilibrium meets Henry's law.And NO dissolubility in water is the lowest, under room temperature, (25 DEG C) its Henry's constant is 1.94 × 10-8Mol/L Pa, compares SO2Low 3 orders of magnitude of Henry's constant, which greatly increases the resistance to mass tranfer of liquid phase scrubbing, NO dissolubility in water all can not be made to significantly improve by changing the means such as the method for the pH value of temperature and solution.This characteristic causes current wet flue gas denitration technology and generally there is the series of problems such as removal efficiency is high, energy consumption is high, and wet flue gas denitration technology is difficult to real industrial applications.Therefore, make NO Quick Oxidation or to be transformed into other water-soluble form be the key that wet flue gas denitration technology is able to industrial applications.In order to enable effectively to remove nitrogen oxides in effluent, it is necessary to assure NO in nitrogen oxides2Content reaches 50～60%.
Photochemical catalytic oxidation (PCO) technology is the air purifying process grown up in recent years, has the advantages such as reaction condition is gentle, energy consumption is low, secondary pollution is few, in waste gas pollution control and treatment field, increasingly causes the concern of people.But the research of Treatment by Photocatalysis Oxidation nitrogen oxides is limited only to the process of low-concentration nitrogen oxide at present, and the treatment effeciency for high concentration nitrogen oxide is the highest.Improve photocatalysis oxidation technique to NOXOxidation efficiency particularly to higher concentration NOXOxidation efficiency, be the key that is used practically of this technology.
The fine chemistry industry process such as production processes such as pharmaceutical factory exists nitrification, nitrosation reaction, discharges NO in waste gasxContent is higher, forms " HUANGLONG " phenomenon, is one of important pollutant causing atmospheric pollution at present.NOxThe most not only form photochemical fog, form acid rain, acid mist, also closely related with the destruction of ozone layer, and also the serious harm mankind's is healthy, therefore NOxProcess be not only the important topic of environmental area, be also the inevitable requirement realizing China's sustainable economic development.The removal methods of nitrogen oxides is broadly divided into dry and wet two class: in dry method, SCR method is widely used in Europe, the United States, but it requires flue-gas temperature typically more than 300 DEG C, is suitable for the process of coal-fired flue-gas；And wet method is relatively suitable for the process of industrial production waste gas, to oxidizability (NO2/(NO2+ NO) concentration proportion) high NOxExhaust-gas treatment effect is preferable.
NO in commercial productionxWaste gas discharges the most at normal temperatures and pressures, and typically containing steam, oxygen etc., wherein oxygen content is higher, sometimes identical with air, is not suitable for applying SCR method to process.Meanwhile, NOxIn be mainly composed of NO, oxidizability is the lowest ,～10～20%, due to NO low solubility in the absorbing liquid such as water, alkali liquor, makes the wet absorption liquid of routine to this type of NOxRemoval efficiency is the lowest, it is difficult to reach emission request.At present, liquid Absorption Study shows that the denitration effect of reducing absorping method is preferable, when off-gas oxidizing degree is more than 50%, the denitration efficiency [poplar nitrogen oxides emission-reduction technology with Flue Gas Denitrification Engineering 2007 metallurgical industry publishing house] of more than 90% can be obtained, hence with oxidant, NO in waste gas is oxidized to NO2, improving off-gas oxidizing degree is to remove this type of NOxOne of effective way.
Wet flue gas denitration technique mainly has the techniques such as alkali liquor absorption, liquid phase oxidation absorption, liquid-phase reduction absorption at present, and the absorbing liquid that alkali absorption method uses has NaOH, Ca (OH)2、Na2CO3And NH4OH etc., the absorbing liquid that liquid phase oxidation uses has KMnO4、NaClO2Deng, the absorbing liquid that liquid phase reduction uses has Na2SO3、Na2S、Na2S2O3、(NH2)2CO and (NH4)2SO3Deng.
It is currently used for light-catalysed quasiconductor and is mainly the N-type semiconductor of broad stopband, mainly have TiO2、ZnO、CdS、WO3、Fe2O3、PbS、SnO2、InO3、ZnS、SiO2Several Deng ten, wherein TiO2Relative low price, good stability, catalysis activity is high, can reuse and become the most the most frequently used photocatalyst.There are some researches show, TiO2At least can experience 12 times reuse and keep photolysis efficiency to be basically unchanged.
The Main Function of carrier of photocatalyst has: (1) fixed catalyst, prevents the loss of catalyst, and is easily recycled；(2) improve catalyst utilization, i.e. increase surface availability of catalyst and amass；(3) photocatalytic activity is improved；(4) light source utilization rate etc. is improved.Due to nano-TiO2In the sun can decomposing organic matter, therefore the used carrier overwhelming majority is inorganic material.The most it is used as loading TiO2Mineral-type carrier have silica gel, zeolite, sheet glass, mesopore molecular sieve, firebrick particle, hollow glass micro-ball etc..
Patent 200610012414.1,200610051721.0,200710052129.7,200610012525.2,200610051737.1,200510062185.X, 200710067082.1,200710061515.2 etc. utilize chloric strong oxidant (sodium chlorite, sodium hypochlorite etc.), hydrogen peroxide, ozone oxidation and photochemical catalytic oxidation mode that the NO in waste gas is aoxidized, being used alone or in combination of these mode of oxidizing improves more greatly NOxRemoval efficiency, but owing to employing extra oxidant, investment, running cost strengthen, in, small enterprise's application difficulty strengthens, and works as NOxWhen exhaust-gas treatment amount is bigger there is some problems in photochemical catalytic oxidation application；Patent 01105698.3,02110646.0 with the oxygen in air as oxidant, triethylenediamine cobalt solution liquid phase oxidation NO, NO can be realizedxQualified discharge, but the use of triethylenediamine cobalt will increase exhaust-gas treatment cost, and be likely present some problems in commercial plant in terms of Engineering Control；Patent 200510062296.0,200510062297.5 realizes the complexed absorption to NOx by adding effective additive in FeIIEDTA solution, when the response time is 20-30s, NOx removal rate can be made to reach 65-95%, but the cost of absorbing liquid puts into and strengthens, and component of effluent is complicated after absorbing, it is more difficult to process.
Young Sun Mok [Absorption-reduction technique assisted by ozoneinjection and sodium sulfidefor NOx removal from exhaust gas, ChemicalEngineering Journal, 2006] by 300ppm NO through ozone oxidation, Na2After the aqueous slkali of S absorbs, removal efficiency is up to more than 95%；CN101036851A will contain NOxWaste gas through ozone oxidation, Polyethylene Glycol absorb after, nearly reached the removal efficiency of 100%.But ozone generating-device investment big, relatively costly, in, small enterprise application difficulty bigger.[the Oxidation of NOinto NO such as Isao Mochida2Over Active Carbon Fibers, Energy&Fuels 1994,8:1341-1344] utilize modified NACF (ACF) at room temperature to carry out the oxidation experiment of NO (400ppm).Under 25 DEG C of drying conditions, conversion ratio is 73%, but in waste gas, the existence of steam seriously inhibits the conversion of NO, and under saturation vapour, conversion ratio is only 21%, it is seen that in industrial waste gas, the existence of high-load steam seriously hinders the application of ACF catalytic oxidation NO.
Summary of the invention
It is an object of the invention to propose a kind of method absorbing nitrogen oxides of exhaust gas.
For reaching this purpose, the present invention by the following technical solutions:
A kind of method absorbing nitrogen oxides of exhaust gas, including: waste gas is passed through oxidizing tower through O2After oxidation, the aluminium oxide of oxidizing tower filling modification is as catalyst, with steam, waste gas is heated to 20～100 DEG C, the oxygen in waste gas is made to react with NO, reacted gas enters absorption tower and carries out Reducing and absorption reaction by bubbling and absorbing liquid, after reaction, gas is discharged by tower top, waste gas processes through tertiary oxidation-Reducing and absorption, tail gas empties through exhaust port, absorbing liquid is the mixed liquor of ammonium sulfite and ammonia, mass content is 0.02～20%, oxidizing tower diameter 1m, high 3m, bubble absorbing tower diameter 0.4m, high 0.6m, catalyst in oxidizing tower needs by aqueous slkali soaking 18～24h, it is washed with deionized water to neutrality, use after drying under nitrogen or hydrogen shield.
Detailed description of the invention
Embodiment 1
A kind of method absorbing nitrogen oxides of exhaust gas, including: waste gas is passed through oxidizing tower through O2After oxidation, the aluminium oxide of oxidizing tower filling modification is as catalyst, with steam, waste gas is heated to 40 DEG C, the oxygen in waste gas is made to react with NO, reacted gas enters absorption tower and carries out Reducing and absorption reaction by bubbling and absorbing liquid, after reaction, gas is discharged by tower top, waste gas processes through tertiary oxidation-Reducing and absorption, tail gas empties through exhaust port, absorbing liquid is the mixed liquor of ammonium sulfite and ammonia, mass content is 5%, oxidizing tower diameter 1m, high 3m, bubble absorbing tower diameter 0.4m, high 0.6m, catalyst in oxidizing tower needs by aqueous slkali soaking 18～24h, it is washed with deionized water to neutrality, use after drying under nitrogen or hydrogen shield.
Embodiment 2
A kind of method absorbing nitrogen oxides of exhaust gas, including: waste gas is passed through oxidizing tower through O2After oxidation, the aluminium oxide of oxidizing tower filling modification is as catalyst, with steam, waste gas is heated to 20 DEG C, the oxygen in waste gas is made to react with NO, reacted gas enters absorption tower and carries out Reducing and absorption reaction by bubbling and absorbing liquid, after reaction, gas is discharged by tower top, waste gas processes through tertiary oxidation-Reducing and absorption, tail gas empties through exhaust port, absorbing liquid is the mixed liquor of ammonium sulfite and ammonia, mass content is 0.02%, oxidizing tower diameter 1m, high 3m, bubble absorbing tower diameter 0.4m, high 0.6m, catalyst in oxidizing tower needs by aqueous slkali soaking 18～24h, it is washed with deionized water to neutrality, use after drying under nitrogen or hydrogen shield.
Embodiment 3
A kind of method absorbing nitrogen oxides of exhaust gas, including: waste gas is passed through oxidizing tower through O2After oxidation, the aluminium oxide of oxidizing tower filling modification is as catalyst, with steam, waste gas is heated to 80 DEG C, the oxygen in waste gas is made to react with NO, reacted gas enters absorption tower and carries out Reducing and absorption reaction by bubbling and absorbing liquid, after reaction, gas is discharged by tower top, waste gas processes through tertiary oxidation-Reducing and absorption, tail gas empties through exhaust port, absorbing liquid is the mixed liquor of ammonium sulfite and ammonia, mass content is 15%, oxidizing tower diameter 1m, high 3m, bubble absorbing tower diameter 0.4m, high 0.6m, catalyst in oxidizing tower needs by aqueous slkali soaking 18～24h, it is washed with deionized water to neutrality, use after drying under nitrogen or hydrogen shield.
Embodiment 4
A kind of method absorbing nitrogen oxides of exhaust gas, including: waste gas is passed through oxidizing tower through O2After oxidation, the aluminium oxide of oxidizing tower filling modification is as catalyst, with steam, waste gas is heated to 100 DEG C, the oxygen in waste gas is made to react with NO, reacted gas enters absorption tower and carries out Reducing and absorption reaction by bubbling and absorbing liquid, after reaction, gas is discharged by tower top, waste gas processes through tertiary oxidation-Reducing and absorption, tail gas empties through exhaust port, absorbing liquid is the mixed liquor of ammonium sulfite and ammonia, mass content is 19%, oxidizing tower diameter 1m, high 3m, bubble absorbing tower diameter 0.4m, high 0.6m, catalyst in oxidizing tower needs by aqueous slkali soaking 18～24h, it is washed with deionized water to neutrality, use after drying under nitrogen or hydrogen shield.
Obviously, the above embodiment of the present invention is only for clearly demonstrating example of the present invention, and is not the restriction to embodiments of the present invention.For those of ordinary skill in the field, can also make other changes in different forms on the basis of the above description.Here without also cannot all of embodiment be given exhaustive.And these spirit belonging to the present invention are extended out obvious change or variation still in protection scope of the present invention among.
Claims (1)
1. the method absorbing nitrogen oxides of exhaust gas, it is characterised in that including: waste gas is passed through oxidizing tower
Through O2After oxidation, waste gas, as catalyst, is heated to by the aluminium oxide of oxidizing tower filling modification with steam
20～100 DEG C, make the oxygen in waste gas react with NO, reacted gas enter absorption tower by bubbling with
Absorbing liquid carries out Reducing and absorption reaction, and after reaction, gas is discharged by tower top, and waste gas is through tertiary oxidation-reduction
Absorption processes, and tail gas empties through exhaust port, and absorbing liquid is the mixed liquor of ammonium sulfite and ammonia, quality
Content is 0.02～20%, oxidizing tower diameter 1m, high 3m, bubble absorbing tower diameter 0.4m, high 0.6m,
Catalyst in oxidizing tower needs by aqueous slkali soaking 18～24h, is washed with deionized water to neutrality, nitrogen or
Use after drying under hydrogen shield.
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Effective date of registration: 20170206 Address after: 225510 Zhenlong City, Jiangsu Province, Jiangyan Creek Creek Industrial Concentration Area Patentee after: Taizhou Shuming Plastics & Nubber Co., Ltd. Address before: Lake Town, Xishan District People's road 214000 Jiangsu city of Wuxi province and red Ju Wei Village No. 100 Patentee before: Zhu Zhongliang |
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