CN105561755A - Clean flue gas bio-desulfurization and denitrification method and apparatus thereof - Google Patents

Abstract

The invention belongs to the biotechnical field of environment, and concretely relates to a clean flue gas bio-desulfurization and denitrification method and an apparatus thereof. Four bio-reactions comprising denitrification, sulfate reduction, methane production and sulfur oxidation elemental sulfur production and sulfide stripping/hydrogen sulfide absorption combination are adopted to collect oxysulfides in flue gas and directly convert the oxysulfides into highly pure sulfur and convert nitrogen oxide into nitrogen; and an absorption liquid can be regenerated, so the consumption of alkalis and water is saved. Solid wastes and wastewater are not generated in the treatment process, and secondary pollution is avoided.

Description

A kind of clean flue gas biological desulphurization method of denitration and device

Technical field

The invention belongs to field of environmental biotechnology, particularly, the present invention relates to a kind of clean flue gas biological desulphurization method of denitration and device.

Background technology

Containing a large amount of sulfur and nitrogen oxides in the flue gas that the fuel combustions such as coal produce, these oxides are Air Pollutant Discharges.Flue gas sulfur and nitrogen oxides has been classified as the main monitor control index of Air Pollution Control by country.At present, people have proposed multiple flue gas desulfurization and denitration method, and Part Methods achieves industrial applications.But these methods still also exist serious secondary pollution problem, produce a large amount of difficult waste liquids and give up solid, as high sulfate-containing wastewater and calcium sulphate solid etc.In actual production, because processing cost height maybe can not process, the simple processing method such as the stacking that these discarded objects often only adopt and landfill is disposed.A kind of flue gas desulfurization and denitration technique of clean non-secondary pollution is urgently developed in atmosphere pollution.

Due to sulfureous in flue gas oxide easily and water react and generate sulfuric acid, see reaction equation 1-2, so flue gas desulfurization often adopts the methods such as washing, alkali cleaning, wherein limestone-gypsum method is the most ripe, the most widely used method that flue gas oxysulfide removes.The principle of limestone-gypsum method is that the sulfuric acid that utilizes lime stone and oxysulfide to generate and sulfurous acid react the solid calcium sulphate (gypsum) generated, and sees reaction equation 3.The desulfurated plaster that calcium salt method flue gas desulfurization generates is calcium sulfate hydrate, there is significant difference with plaster of paris character, and recycling difficulty is comparatively large, and cost is high, and majority of case is disposed in stacking mode.

SO ₂+H ₂O→H ₂SO ₃(1)

SO ₃+H ₂O→H ₂SO ₄(2)

Limestone-gypsum method absorbs oxysulfide with lime white, very easily fouling and clogging, affects the continuous operation of equipment.For overcoming this problem, the Dual alkali being representative with soda Dual alkali is grown up.Soda Dual alkali is with NaOH or Na ₂cO ₃solution absorbs the SO in flue gas _x, and then with lime stone or lime treatment regeneration of absorption solution NaOH or Na ₂cO ₃, see formula 4 and 5.Although soda Dual alkali is the problem that the Dual alkali of representative solves limestone-gypsum method fouling, but still creates a large amount of calcium sulfate hemihydrates, also need treatedly could obtain gypsum, solid waste processing cost is higher.It is still unresolved that flue gas desulfurization produces a large amount of desulfurated plaster problem.

$\mathrm{Ca}{\left(\mathrm{OH}\right)}_2+{2\mathrm{Na}}_2{\mathrm{SO}}_3+\frac{1}{2}{H}_{2}O\→2\mathrm{NaOH}+{\mathrm{Ca}}_2{\mathrm{SO}}_3\·\frac{1}{2}{H}_{2}O---\left(4\right)$

$\mathrm{Ca}{\mathrm{CO}}_3+2N{a}_2{\mathrm{SO}}_3+\frac{1}{2}{H}_{2}O\→{\mathrm{Na}}_2{\mathrm{CO}}_3+{\mathrm{Ca}}_2{\mathrm{SO}}_3\·\frac{1}{2}{H}_{2}O---\left(5\right)$

Research shows, solving the unmanageable most effective way of desulfurated plaster is by biological respinse sulfate and sulphite be converted into elemental sulfur and reclaim, principle is that sulfate and sulphite are first reduced to sulfide by sulfate reducing bacteria, then is oxidized to elemental sulfur by sulfur oxidizing bacterium, sees formula 6 and 7.

${2\mathrm{CH}}_3\mathrm{CHOHCO}{O}^{-}+{\mathrm{SO}}_4^{2-}\→{2\mathrm{CH}}_3{\mathrm{COO}}^{-}+2\mathrm{HC}{O}_3^{-}+{\mathrm{HS}}^{-}+H^{+}---\left(6\right)$

2HS ^-+O ₂→2S ⁰+OH ^-(7)

Based on above-mentioned principle, flue gas biological desulphurization method is grown up, first organic wastewater is utilized to absorb oxysulfide, oxysulfide is converted into sulfate and sulphite, in anaerobic reactor, by the sulfate reduction of microorganism, sulfate and sulphite are reduced to sulfide, the water outlet of sulfur compound enters in aerobic reactor, is oxidized to elemental sulfur (CN2010105553188, CN200510076816) by sulfur oxidizing bacterium.But, there are two prominent questions in above-mentioned flue gas biological desulphurization technical process: one, high sulfate-containing wastewater belongs to one of the most difficult waste water, it is field of waste water treatment study hotspot, the sulfide that sulfate reduction produces has strong inhibition effect to anaerobic digestion, sulfureous in flue gas oxides adsorb is entered in waste water, adds intractability and the cost of waste water.As Chinese patent CN201220477214 and CN201110133900 proposes solution for the unmanageable problem of high-sulfate waste water.Further, due to the restriction of sulphates content in waste water, the gas liquid ratio that flue gas oxysulfide absorbs is lower, and absorbent consumption is large, and energy consumption is high.Two, contain a large amount of organic matters in wastewater treatment system, not only produce elemental sulfur in aerobic sulphur oxidizing process, and produce a large amount of mud, define sulphur and mud mixture, sulfur content is low, cost recovery.Such as Chinese patent CN200910077456 proposes the method that halogenated hydrocarbons, alkyl or aryl disulphide or Fluhyzon and Naphtha solvent extract sulphur, but, the method not only also exists the high problem of cost, and can produce the unmanageable waste water containing organic solvent.Because sulphur economic worth is lower, so the sulphur mud mixture of low sulfur content does not have recovery value.Therefore, existing flue gas biological desulphurization method can not realize cost-effective sulphur recovery.

In addition, flue gas biological desulphurization and sulfate wastewater treatment are significantly different, and flue gas pollutant is gaseous sulfur oxide, not containing organic matter.Ideally, oxysulfide should be converted into elemental sulfur by flue gas biological desulphurization, does not produce any waste water and waste gas.Because sulfate reducing bacteria needs electron donor to complete sulfate reduction, thus flue gas biological desulphurization want additional organic matter, but organic kind and quantity can select, controlled.The absorbing liquid of flue gas biological desulphurization is answered renewable and can recycle, thus reduce the water consumption of flue gas biological desulphurization, avoid discharge of wastewater, avoid producing secondary pollution, the difference of flue gas biological desulphurization and sulfate wastewater treatment is also, nitrate nitrogen can be contained in absorbing liquid, and sulfate wastewater is containing ammonium nitrogen.

In flue gas biological desulphurization process, while oxysulfide absorbs, nitrogen oxide also can be absorbed, and can realize the biological synchronized desulfuring and denitrifying of flue gas.Forming the absorbing liquid of containing sulfate and nitrate nitrogen thus, there is substrate competition relation in anaerobic denitrifying and sulfate reduction.Flue gas biological desulphurization technique needs the associated treatment considering sulfate and nitrate nitrogen, can solve the problem that denitrification and sulfate reduction vie each other, set up the biological synchronized desulfuring and denitrifying of flue gas by technological design.

Summary of the invention

The object of the invention is to provide a kind of cleaning flue gases biological desulphurization denitrating technique, for realizing this technical goal, the present invention adopts following technical scheme:

Cleaning flue gases biological desulphurization method of denitration of the present invention, comprises the following steps:

(1) flue gas biological desulphurization coproduction elemental sulfur:

(1-1) absorb the sulfur and nitrogen oxides in flue gas with weak lye, form acid absorption rich solution;

(1-2) in the acidity absorption rich solution of step (1-1), add organic matter, form acid mixed solution, utilize acid mixed solution acidifying, sulfide is converted into hydrogen sulfide by stripping;

(1-3) hydrogen sulfide gas of stripping generation is by alkali liquor absorption, and the sulfur compound rich solution of generation is converted into elemental sulfur by biological sulphur oxidation reaction;

(2) denitrification associating sulfate reduction:

(2-1) to supplementary carbon source in the absorption rich solution after step (1-2) stripping hydrogen sulfide, by double oxygen anti-nitration reaction, be nitrogen by nitrate-nitrogen reduction in absorption rich solution;

(2-2) sulfate wherein and sulphite, by anaerobism sulfate reduction, are reduced to sulfide by the absorption rich solution after step (2-1) denitration;

(2-3) make the waste water after step (2-2) sulfate reduction be reacted by anaerobic methane production, remaining organic matter is converted into methane;

(2-4) carry out aerobic reaction through the reacted waste water of step (2-3) anaerobic methane production, remove carbon source.

Particularly, cleaning flue gases biological desulphurization method of denitration of the present invention, comprises the following steps:

(1) flue gas biological desulphurization coproduction elemental sulfur:

(1-1) absorb the sulfur and nitrogen oxides in flue gas with weak lye, form acid absorption rich solution;

(1-2) in the acidity absorption rich solution of step (1-1), add organic matter, form acid mixed solution, acid mixed solution enters sulfide stripping tower, and utilize acid mixed solution acidifying, sulfide is converted into hydrogen sulfide by stripping;

(1-3) hydrogen sulfide gas that stripping produces is absorbed by the hydrogen sulfide absorption tower containing soda ash liquid, and the sulfur compound rich solution of generation is sent in biological sulphur oxidation reactor and is converted into elemental sulfur;

(2) denitrification associating sulfate reduction:

(2-1) the absorption rich solution after step (1-2) stripping hydrogen sulfide enters in double oxygen denitrification reactor, and nitrate-nitrogen reduction in absorption rich solution is nitrogen by supplementary carbon source;

(2-2) the absorption rich solution after step (2-1) denitration enters anaerobism sulfate reduction device, and sulfate and sulphite are reduced to sulfide;

(2-3) make the waste water after step (2-2) sulfate reduction enter anaerobic methane production reactor for treatment, remaining organic matter is converted into methane;

(2-4) enter aerobic aeration pond through the reacted waste water of step (2-3) anaerobic methane production, remove carbon source.

The present invention absorbs the sulfur and nitrogen oxides in flue gas with weak lye, forms acid absorption rich solution.Adding appropriate organic matter for absorbing in rich solution, first nitrate nitrogen in absorption rich solution being converted into nitrogen, then being sulfide by sulfate reduction wherein.Utilize the acidifying of acid absorption rich solution, be hydrogen sulfide by sulphidic conversion, adopt the method for gas stripping that the hydrogen sulfide of conversion is transferred to gas phase, with soda ash liquid, hydrogen sulfide absorption is transformed back sulfide again, complete the separating-purifying of sulfide, sulfide is separated with organic matter.Sulfide after purification is converted into elemental sulfur by chemoautotroph sulfur oxidizing bacterium, obtains biological sulphur through pelleting centrifugation.Because sulfide is free from foreign meter, so Recovered sulphur purity is high, the not treated requirement that can reach commodity sulphur.Absorb rich solution through denitrification and sulfate reduction process, the nitrate nitrogen that nitrogen oxide and oxysulfide absorption are formed and sulfate are substantially completely removed.But denitrification and sulfate reduction all can not degradable organic matters, therefore need again through anaerobic methane production process by degradable for residual organic substances be methane and carbon dioxide.The reaction of denitrification, sulfate reduction, methane phase three all can produce alkali, and smoke absorption liquid can regenerate, and recycles, and significantly reduces flue gas biological desulphurization denitration water, alkali consumption.

According to cleaning flue gases biological desulphurization method of denitration of the present invention, for realizing recycling of intermediate product, reach the environmental protection object of cleaning flue gases, as preferably, the obtained nitrogen of described step (2-1) enters gas collection and treatment system, for the inertia circulating carried between step (1-2) hydrogen sulfide stripping and step (1-3) hydrogen sulfide absorption after purification pressurization.After described step (2-2) anaerobism sulfate reduction, the return of waste water step (1-2) of sulfur compound participates in hydrogen sulfide conversion.Waste water after described (2-4) aerobic reaction enters Buffer Pool as the weak lye in step (1-1), absorbs the sulfur and nitrogen oxides in flue gas.

According to cleaning flue gases biological desulphurization method of denitration of the present invention, step (1-1) described weak lye is the NaHCO of 0.2 ~ 0.5M ₃solution.

Described step (1-1), in absorption sulfur and nitrogen oxides process, need, by controlling gas liquid ratio, make the acid pH value absorbing rich solution be down to 4.0 ~ 5.0.Oxysulfide absorbs formation sulfuric acid and sulfurous acid can reduce pH value, controls oxysulfide uptake and makes the pH value of rich solution be down to 4.0 ~ 5.0, be conducive to sulfide stripping.

According to cleaning flue gases biological desulphurization method of denitration of the present invention, the organic matter of step (1-2) described interpolation is one or more in ethanol, lactic acid or lactate or glucose.

Alkali lye in step of the present invention (1-3) is the NaHCO of concentration 0.2 ~ 0.5M ₃.The elemental sulfur generated in step (1-3) can make the finished product sulphur of purity >=99% further after precipitation and centrifugation.

Step of the present invention (2-1) described carbon source is one or more in ethanol, lactic acid or lactate and glucose.

The pH value >7.0 of step of the present invention (2-4) described aerobic reaction.The waste water that sulfate reduction produces, after stripping, enters Aerobic Pond process.The water inlet of Aerobic Pond contains the sulfide of stripping remnants and the carbon source of sulfate reduction remnants, and these substance oxidations produce the pH value that acid can reduce Aerobic Pond, needs to mend alkali and keeps Aerobic Pond pH to stablize.In addition, Aerobic Pond water outlet is directly used in sulfureous in flue gas oxides adsorb, maintains higher ph and is conducive to absorbing.

Biological sulphur oxidation reaction of the present invention, oxygen anti-nitration reaction, anaerobism sulfate reduction and methane phase reaction of holding concurrently all use the existing bacterial strain that can carry out above-mentioned reaction, preferably use the anaerobism of municipal sewage plant, double oxygen and aerobic activated sludge.

Originally the device based on above-mentioned cleaning flue gases biological desulphurization method of denitration provided, comprises flue gas biological desulphurization coproduction elemental sulfur system and combines sulfate reduction system with denitrification;

Described flue gas biological desulphurization coproduction elemental sulfur system comprises smoke absorption tower 1, mixing tank 2, sulfide stripping tower 7, hydrogen sulfide absorption tower 8 and biological sulphur oxidation reactor 9;

Described denitrification associating sulfate reduction system comprises double oxygen denitrification reactor 3, anaerobism sulfate reduction device 4, anaerobic methane production reactor 5 and aerobic aeration pond 6;

Described smoke absorption tower 1 connects mixing tank 2, sulfide stripping tower 7, hydrogen sulfide absorption tower 8 and biological sulphur oxidation reactor 9 in turn;

Described double oxygen denitrification reactor 3 and sulfide stripping tower 7, and connect anaerobism sulfate reduction device 4, anaerobic methane production reactor 5 and aerobic aeration pond 6 in turn.

According to cleaning flue gases biological desulphurization denitrification apparatus of the present invention, preferably, between sulfide stripping tower 7 and hydrogen sulfide absorption tower 8, be provided with gas flow cycle; Described double oxygen denitrification reactor 3 is connected with gas collection and treatment system 12 further, and described connection gas collection and treatment system 12 are communicated in the gas flow cycle between sulfide stripping tower 7 and hydrogen sulfide absorption tower 8.

Further preferably, described anaerobism sulfate reduction device 4 is connected with mixing tank 2.

A step preferably again, and described aerobic aeration pond 6 is connected with smoke absorption tower 1 by Buffer Pool 14.

Biological sulphur oxidation reactor 9 of the present invention also connects sulphur sedimentation basin 10 and sulphur centrifuge 11 further in turn, for sulphur of purifying.

Advantage of the present invention is: compared with prior art, and the oxysulfide in flue gas is converted into elemental sulfur by technique provided by the invention, and can obtain high-purity elemental sulfur through simple physical method, really achieves sulphur recovery; Utilize biological denitrification, anaerobism sulfate reduction and methane phase to react and produce alkali effect, realize regeneration of absorption solution and recycle; Sulfur and nitrogen oxides in flue gas is separately converted to elemental sulphur and nitrogen, and sulfur recovery rate is higher than 90%, thoroughly solves flue gas desulfurization and denitrification secondary pollution problem, achieves the denitration of cleaning flue gases biological desulphurization.

Accompanying drawing explanation

Fig. 1 is cleaning flue gases biological desulphurization denitrating technique flow chart of the present invention.

Fig. 2 is the result to different sulfoxide concentration simulated flue gas.

Fig. 3 is the result to different sulfur and nitrogen oxides scale modeling flue gas.

Fig. 4 is the result of true flue gas.

Reference numeral

1, smoke absorption tower 2, mixing tank 3, oxygen denitrification reactor of holding concurrently

4, anaerobism sulfate reduction device 5, anaerobic methane production reactor

6, aerobic aeration pond 7, sulfide stripping tower 8, hydrogen sulfide absorption tower

9, biological sulphur oxidation reactor 10, sulphur sedimentation basin 11, sulphur centrifuge

12, gas collection and treatment system 13, methane recovery system 14, Buffer Pool

Detailed description of the invention

Below in conjunction with embodiment, the present invention is described in further detail, but working of an invention mode is not limited thereto.

Embodiment 1 cleaning flue gases biological desulphurization denitrating technique flow process

As shown in Figure 1, cleaning flue gases biological desulphurization denitrification integral process of the present invention produces elemental sulfur, sulphur recovery and aerobic aeration tank composition primarily of smoke absorption, sulfide stripping/hydrogen sulfide absorption, oxygen denitrification of holding concurrently, anaerobism sulfate reduction, anaerobic methane production, the oxidation of micro-oxygen sulphur.Concrete technology flow process is as follows:

1) with 0.2 ~ 0.5MNaHCO ₃for absorbing liquid, absorbing in absorption tower 1 through de-dirt and the sulfur and nitrogen oxides in the pending flue gas of cooling process, by controlling gas liquid ratio, making the pH value of absorption rich solution be down to 4.0 ~ 5.0.

2) absorb rich solution and anaerobism sulfate reduction device 4 to reflux be mixed to form acid mixed solution in mixing tank 2, mixed liquor enters sulfide stripping tower 7, and sulfide is converted into hydrogen sulfide by stripping, and pH is increased to 5.5 ~ 6.0.

3) the H 2 S-containing gas hydrogen absorption tower 8 that cures that stripping produces absorbs, and the sulfur compound rich solution of generation is sent in biological sulphur oxidation reactor 9 and is converted into elemental sulfur.The elemental sulfur generated makes the finished product sulphur of purity >=99% through precipitation (sulphur sedimentation basin 10) and centrifugation (sulphur centrifuge 11).The waste liquid of centrifugal generation is got back in biological sulphur oxidation reactor 9.The sulfide that anaerobism sulfate reduction produces, through sulfide stripping/hydrogen sulfide absorption, the oxidation of chemautotrophy sulfur oxidizing bacterium, is finally converted into elemental sulfur.

4) through the absorption rich solution of stripping process, enter double oxygen denitrification reactor 3, supplement the carbon sources such as ethanol, lactic acid, glucose, be uniformly mixed, absorb nitrate nitrogen in rich solution and be reduced nitrogen, nitrogen enters gas collection and treatment system 12, is used as the inertia circulating carried between sulfide stripping/hydrogen sulfide absorption after purification pressurization; Described gas collection and treatment system 12, can comprise gas holder, filter and pressue device etc.

5) the absorption rich solution after denitration process enters anaerobism sulfate reduction device 5, and sulfate and sulphite are reduced to sulfide, and sulfur compound waste liquid enters the outer circulation of anaerobism sulfate reduction device, is back to step 2).

6) because anaerobism sulfate reduction can not degradable carbon source, the water outlet of anaerobism sulfate reduction enters anaerobic methane production reactor 5 and processes, and remaining organic matter is converted into methane, and the methane of generation enters methane recovery system 13.

7) through the reaction of denitrification, anaerobism sulfate reduction and methane phase, the sulfate in absorption rich solution and nitrate nitrogen are substantially completely removed, and additional carbon is totally consumed.Because above three biological respinses all produce alkali, therefore anaerobic methane production reactor 5 water outlet pH value is gone up to about 7.0.

8) enter aerobic aeration pond 6 through the circulation fluid of denitrification, anaerobism sulfate reduction and methane phase reaction treatment and remove a small amount of additional carbon that may remain, add NaHCO as required ₃solution, adjusted to ph to 7.5.

9) circulation fluid through aerobic aeration process completes regeneration, enters Buffer Pool 14, is again used as smoke absorption liquid, is pumped to smoke absorption tower, enters circulation next time.

The pH test point of native system: the absorption rich solution of smoke absorption tower 1, sulfide stripping tower 7 and hydrogen sulfide absorption tower 8, holds concurrently in oxygen denitrification reactor 3 and aerobic aeration tank 6, the water outlet of anaerobism sulfate reduction device 4 and anaerobic methane production reactor 5.

The pH point of adjustment of native system is aerobic aeration tank 6.

Oxysulfide absorption, hydrogen sulfide stripping, hydrogen sulfide absorption principle are acid-base neutralization, detect the absorption rich solution pH value everywhere of aerobic aeration pond 6, smoke absorption tower 1, sulfide stripping tower 7 and hydrogen sulfide absorption tower 8, not only can control to absorb or stripping, also can the absorption of indirect calculation oxysulfide and hydrogen sulfide or stripping amount.Double oxygen denitrification reactor 3, anaerobism sulfate reduction device 4, anaerobic methane production reactor 5 are three main reactions of the present invention, and biologically active affects comparatively large by pH value, therefore need on-line checkingi pH value.

The waste water that sulfate reduction produces, after stripping, enters Aerobic Pond process.The water inlet of Aerobic Pond contains the sulfide of stripping remnants and the carbon source of sulfate reduction remnants, and these substance oxidations produce the pH value that acid can reduce Aerobic Pond, needs to mend alkali and keeps Aerobic Pond pH to stablize.In addition, Aerobic Pond water outlet is directly used in sulfureous in flue gas oxides adsorb, maintains higher ph and is conducive to absorbing.Therefore, the pH point of adjustment of system is located at aerobic aeration pond.

Embodiment 2 the present invention is to the treatment effect of different sulfoxide concentration simulated flue gas

Simulated flue gas: SO _xconcentration is (with SO ₂meter) be 500,1000,2000,3000,4000mg/Nm ³(Stage1 ~ 5).

Gas flow rate: 1.0Nm ³/ h.

Absorb lean solution: with 0.2MNaHCO ₃solution adjusts pH to 7.5.

Hydrogen sulfide absorption liquid: Na ₂cO ₃solution.

Supplementary carbon source: control system is poor according to the pH value absorbed between lean solution and rich solution, automatically adds ethanol.

Does is what bacterial classification biological sulphur oxidation reactor? denitrifying bacterium takes from municipal sewage plant denitrification mud, is inoculated in double oxygen denitrification reactor; Separately get municipal sewage plant anaerobic sludge and be inoculated in anaerobism sulfate reduction device and methane-producing reactor respectively.

Regulate gas liquid ratio, controlling to absorb rich solution pH is 4.0 ~ 5.0.

All the other experiment conditions are arranged with reference to embodiment 1.

Experimental result as shown in Figure 2, the treated SO of simulated flue gas _xremoval efficiency >99%, SO _xconcentration is down to <40mg/Nm ³.Sulfur recovery rate (reclaiming ratio with the form of elemental sulfur) >90%.After measured, sulfur purity >99%.The COD concentration <20mg/m of aerobic aeration pond water outlet ³.As calculated, alkali average consumption (in NaOH) is 43.5g/kgSO ₂, be 3.5% of theoretical consumption.

The present embodiment illustrates, the present invention can efficient removal oxysulfide, and the overwhelming majority is converted into elemental sulfur, and is effectively reclaimed.Processing procedure produces outer draining, and not only the water yield is little, and COD concentration is lower than discharge standard, can directly discharge.Quantity of alkali consumption is only 3.5% of theoretical consumption.As can be seen here, the present invention is a kind of cleaning flue gases sulfur removal technology not producing secondary pollution, water saving, province's medicament.

Embodiment 3 the present invention is to the treatment effect of different sulfur and nitrogen oxides scale modeling flue gas

Simulated flue gas: SO _xconcentration is (with SO ₂meter) 2000mg/Nm ³, NO _xconcentration is (with NO ₂meter) 50,100,200,400mg/Nm ³(Stage1 ~ 4).

Other process conditions are identical with embodiment 2.

Experimental result as shown in Figure 3.The treated SO of simulated flue gas _xconcentration is down to <10mg/Nm ³, SO _xremoval efficiency >99%.Due to NO _xcomprise the NO being insoluble in water, NO _xremoval efficiency is lower is 50 ~ 70%.Flue gas after biological desulphurization denitrogenation processing, NO _xconcentration is down to 200mg/Nm ³below, nitrogen oxide is 100% by the removal efficiency absorbing the nitrate nitrogen of rear generation.The indexs such as sulfur recovery rate, sulfur purity, outer draining COD are similar to embodiment 2, are respectively >90%, >98%, <20mg/m ³.

The present embodiment illustrates, the present invention also has certain denitration ability while flue gas desulfurization, although NO _xremoval efficiency is not high, but still can be used for NO _xthe lower fume treatment of content, and realize qualified discharge.In flue gas desulfurization and denitrification process, still there is characteristic that do not produce secondary pollution, that economize on water, economize medicament.The present invention is a kind of cleaning flue gases biological desulphurization denitrating technique.

Embodiment 4 take different carbon source as the operational effect of electron donor simulated flue gas biological desulphurization denitration

Simulated flue gas: SO _xconcentration is (with SO ₂meter) 2000mg/Nm ³, NO _xconcentration is (with NO ₂meter) 500mg/Nm ³.

Respectively with ethanol, lactic acid, sodium lactate, glucose, mixed carbon source for adding carbon source.

Mixed carbon source: ethanol: lactic acid: glucose=5:2:1

Other process conditions are identical with embodiment 2.

Experimental result shows, ethanol, lactic acid, sodium lactate, glucose can as the carbon sources of flue gas biological desulphurization denitration, in table 1.With carbon source consumption for index, ethanol experimental group is for often to process 1Nm ³the consumption of simulated flue gas is minimum.With Aerobic Pond water inlet for index, the effluent COD concentration of mixed carbon source experimental group is minimum.

The consumption of table 1 different carbon source and Aerobic Pond influent COD

The present embodiment illustrates, it is carbon source that the present invention can select ethanol, lactic acid, sodium lactate, glucose etc. wherein a kind of, also can use the mixed carbon source that ethanol, lactic acid and glucose form.The effect of ethanol list carbon source and mixed carbon source is best.

Embodiment 5 cleaning flue gases biological desulphurization denitrating technique is to the treatment effect of true flue gas

Flue gas: SO _xconcentration is (with SO ₂meter) 1,000 ~ 2,000mg/Nm ³, NO _xconcentration is (with NO ₂meter) 400 ~ 500mg/Nm ³, through cooling, dust removal process.

Mixed carbon source: ethanol: lactic acid: glucose=5:2:1

Other process conditions are identical with embodiment 2.

Experimental result as shown in Figure 4.Flue gas SO after process _xconcentration <20mg/Nm ³, NO _xconcentration is (with NO ₂meter) <180mg/Nm ³.SO _xand NO _xremoval efficiency is respectively >95% and >62%.Draining COD concentration <30mg/L outside aerobic aeration pond, total nitrogen <10mg/L reaches direct discharge standard.Alkali average consumption (in NaOH) is 45.2g/kgSO ₂, be 3.6% of theoretical consumption.

As calculated, the sulfate removal rate >95% of rich solution is absorbed, sulfur recovery rate >90%, sulfur purity >95%.The nitrate nitrogen removal efficiency absorbing rich solution is 100%.

The present embodiment illustrates, the present invention may be used for actual flue gas desulfurization and denitrification, and treated flue gas reaches discharging standards.What is more important, oxysulfide is converted into high-purity elemental sulfur through a series of biological respinse and reclaims, and nitrogen oxide is converted into nitrogen.Utilize regenerating biological reaction absorbing liquid, save >95% quantity of alkali consumption, decrease medicament and water consumption.Do not produce solid waste in processing procedure, in the waste water of generation, COD and total nitrogen concentration are lower than the strictest discharge standard of country.Therefore, the present invention is the cleaning flue gases biological desulphurization denitrating technique of a kind of water saving, joint alkali, non-secondary pollution.

Certainly; the present invention can also have various embodiments; when not deviating from the present invention's spirit and essence thereof; those of ordinary skill in the art can openly make various corresponding change and modification according to of the present invention, but these change accordingly and are out of shape the protection domain that all should belong to the claim appended by the present invention.

Claims (14)

1. a cleaning flue gases biological desulphurization method of denitration, comprises the following steps:

(1) flue gas biological desulphurization coproduction elemental sulfur:

(1-1) absorb the sulfur and nitrogen oxides in flue gas with weak lye, form acid absorption rich solution;

(1-2) in the acidity absorption rich solution of step (1-1), add organic matter, form acid mixed solution, utilize acid mixed solution acidifying, sulfide is converted into hydrogen sulfide by stripping;

(1-3) hydrogen sulfide gas of stripping generation is by alkali liquor absorption, and the sulfur compound rich solution of generation is converted into elemental sulfur by biological sulphur oxidation reaction;

(2) denitrification associating sulfate reduction:

(2-1) to supplementary carbon source in the absorption rich solution after step (1-2) stripping hydrogen sulfide, by double oxygen anti-nitration reaction, be nitrogen by nitrate-nitrogen reduction in absorption rich solution;

(2-2) sulfate wherein and sulphite, by anaerobism sulfate reduction, are reduced to sulfide by the absorption rich solution after step (2-1) denitration;

(2-3) make the waste water after step (2-2) sulfate reduction be reacted by anaerobic methane production, remaining organic matter is converted into methane;

(2-4) carry out aerobic reaction through the reacted waste water of step (2-3) anaerobic methane production, remove carbon source.

2. cleaning flue gases biological desulphurization method of denitration according to claim 1, it is characterized in that, the obtained nitrogen of described step (2-1) enters gas collection and treatment system, for the inertia circulating carried between step (1-2) hydrogen sulfide stripping and step (1-3) hydrogen sulfide absorption after purification pressurization.

3. cleaning flue gases biological desulphurization method of denitration according to claim 1, is characterized in that, after described step (2-2) anaerobism sulfate reduction, the return of waste water step (1-2) of sulfur compound participates in hydrogen sulfide conversion.

4. cleaning flue gases biological desulphurization method of denitration according to claim 1, it is characterized in that, waste water after described (2-4) aerobic reaction enters Buffer Pool as the weak lye in step (1-1), absorbs the sulfur and nitrogen oxides in flue gas.

5. cleaning flue gases biological desulphurization method of denitration according to claim 1, is characterized in that, step (1-1) described weak lye is the NaHCO of 0.2 ~ 0.5M ₃solution.

6. cleaning flue gases biological desulphurization method of denitration according to claim 1, is characterized in that, described step (1-1), by controlling gas liquid ratio, makes the acid pH value absorbing rich solution be down to 4.0 ~ 5.0.

7. cleaning flue gases biological desulphurization method of denitration according to claim 1, is characterized in that, the organic matter of step (1-2) described interpolation is one or more in ethanol, lactic acid or lactate or glucose.

8. cleaning flue gases biological desulphurization method of denitration according to claim 1, is characterized in that, step (2-1) described carbon source is one or more in ethanol, lactic acid or lactate and glucose.

9. cleaning flue gases biological desulphurization method of denitration according to claim 1, is characterized in that, the pH value of step (2-4) described aerobic reaction is 7.0 ~ 7.5.

10. based on a device for cleaning flue gases biological desulphurization method of denitration according to claim 1, it is characterized in that, comprise flue gas biological desulphurization coproduction elemental sulfur system and combine sulfate reduction system with denitrification;

Described flue gas biological desulphurization coproduction elemental sulfur system comprises smoke absorption tower (1), mixing tank (2), sulfide stripping tower (7), hydrogen sulfide absorption tower (8) and biological sulphur oxidation reactor (9);

Described denitrification associating sulfate reduction system comprise double oxygen denitrification reactor (3, anaerobism sulfate reduction device (4), anaerobic methane production reactor (5) and aerobic aeration pond (6);

Described smoke absorption tower (1) connects mixing tank (2), sulfide stripping tower (7), hydrogen sulfide absorption tower (8) and biological sulphur oxidation reactor (9) in turn;

Described double oxygen denitrification reactor (3) and sulfide stripping tower (7), and connect anaerobism sulfate reduction device (4), anaerobic methane production reactor (5) and aerobic aeration pond (6) in turn.

11. cleaning flue gases biological desulphurization denitrification apparatus according to claim 10, is characterized in that, be provided with gas flow cycle between sulfide stripping tower (7) and hydrogen sulfide absorption tower (8); Described double oxygen denitrification reactor (3) is connected with gas collection and treatment system (12) further, and described connection gas collection and treatment system (12) are communicated in the gas flow cycle between sulfide stripping tower (7) and hydrogen sulfide absorption tower (8).

12. cleaning flue gases biological desulphurization denitrification apparatus according to claim 10, is characterized in that, described anaerobism sulfate reduction device (4) is connected with mixing tank (2).

13. cleaning flue gases biological desulphurization denitrification apparatus according to claim 10, is characterized in that, described aerobic aeration pond (6) is connected with smoke absorption tower (1) by Buffer Pool (14).

14. cleaning flue gases biological desulphurization denitrification apparatus according to claim 10, is characterized in that, described biological sulphur oxidation reactor (9) also connects sulphur sedimentation basin (10) and sulphur centrifuge (11) further in turn.