CN104226095B - Based on the synchronous denitrating technique of flue gas wet ammonia process desulfurizing - Google Patents

Abstract

The present invention discloses a kind of synchronous denitrating technique based on flue gas wet ammonia process desulfurizing, solves existing technique and there is running cost and equipment investment cost height, complex process, problem that energy consumption is high. Technical scheme sends into concentrated solution contact reacts in upgrading tower and tower after comprising flue gas supercharging, the flue gas going out upgrading tower sends into the absorbing liquid contact reacts in absorption tower and tower, ammonium sulfate crystallization system sent into by the reacted concentrated solution of small portion at the bottom of upgrading tower tower, in the absorbing liquid on absorption tower, add complexing agent EDTA-Fe (II) or add EDTA-Na salt and ferrous sulfate at 1: 1 in molar ratio, make the EDTA-Fe in absorbing liquid (II & III) concentration be 0.015��0.05mol/L; Absorbing liquid a small amount of in described absorption tower is sent in described upgrading tower and mixes with concentrated solution. Technique of the present invention is simple, running cost and facility investment is low, can high efficiency synchronous desulphurization denitration, energy consumption low.

Description

Based on the synchronous denitrating technique of flue gas wet ammonia process desulfurizing

Technical field

The present invention relates to a kind of filed of flue gas purification, the specifically technique of a kind of synchronous denitration based on flue gas wet ammonia process desulfurizing.

Background technology

The fast development since the nineties in 20th century of China's steel industry, result in a large amount of discharges of atmospheric polluting material, wherein SO₂It is only second to power-plant flue gas with the quantity discharged of NOx. The Iron And Steel Industry SO of China's emphasis statistics in 2011₂Quantity discharged at 2,510,000 tons, wherein agglomerates of sintered pellets operation SO before iron₂Quantity discharged reaches 2,180,000 tons, accounts for more than the 87% of iron and steel enterprise's total emission volumn, and SO₂Processing rate only 32%. The feature of sinter fume is that exhaust gas volumn is big, flue gas carries that Dust Capacity is relatively big, the quantity discharged of sulfurous gas and change in concentration is relatively big, flue-gas temperature fluctuation is big, smoke components is complicated, humidity of flue gas is big. Compared with boiler smoke, deal with more difficult, it is difficult to directly adopt power plant desulfurization denitration technology.

In denitration, owing to sinter fume has above singularity, and for existing sintering (pelletizing) system, to such an extent as to existing SCR denitration technology and be not exclusively applicable to the improvement of sinter fume, if taking substep administration way, capital investment will be caused costly, the shortcoming such as device floor space is big and flue gas system is complicated, and, in mature technology-SCR denitration technology, to flue gas heating to catalyst temperature window 300-400 DEG C, the problem that energy consumption is high need to be caused.

In actual production, adopt the technology of the independent desulphurization and denitration of multisystem very ripe. But result in greatly facility investment and working cost height due to its system complex, floor space, so research high-efficiency desulfurization denitrification integral process becomes the focus that Chinese scholars is paid close attention to. From the eighties in last century, foreign study person just starts the correlative study of synchronized desulfuring and denitrifying, have developed a lot of synchronized desulfuring and denitrifying method, and in these methods, some has dropped into actual production, and what have is also in laboratory stage. In China, synchronized desulfuring and denitrifying research work is started late. Existing synchronized desulfuring and denitrifying method can be divided into five big classes according to technological process: solid phase adsorption/regenerate synchronous desulphurization denitration technology, gas-solid catalysis synchronized desulfuring and denitrifying technology, sorbent injection synchronized desulfuring and denitrifying technology, high-energy electron active oxidation synchronized desulfuring and denitrifying technology, wet flue gas synchronized desulfuring and denitrifying technology.

In numerous method, the ammonia process of desulfurization because of its desulfuration efficiency height, the advantage such as water is few for consumption, byproduct can effectively utilize, non-secondary pollution and being widely used, and this kind of method also has certain denitration effect while ensureing sweetening effectiveness. Du Zhen, Gao Xiang etc. have studied (NH in ammonia process of desulfurization process₄)₂SO₃Solution absorbs NO_XFeature, it is determined that SO₂Exist NO be absorbed with promoter action, demonstrate the feasibility of ammonia method simultaneous SO_2 and NO removal. Owing in flue gas, NO accounts for NO_X95%, although and the low solubility of NO in water causes the effect that ammonia method has synchronized desulfuring and denitrifying, but denitration efficiency is low, cannot reach requirement. Complexed absorption method is the most effective one method in wet denitration, and denitration effect is remarkable, and reactive adaptation is strong. At present, complexing agent is taken off separately except NO has carried out careful research by Chinese scholars, as Jing Guohua have studied the processing parameter that Fe (II) EDTA absorbs NO, found that SO₃ ^2-Can partial reduction complexing NO and by O₂Fe (III) EDTA of oxidation, is conducive to the out of stock process of complexing.

Studying maximum in complexed absorption method is exactly Fe (II) EDTA method, from the seventies in 20th century, Japan and some scholars of the U.S. just start and Fe (II) EDTA method are carried out big quantifier elimination, and research shows that complexing agent Fe (II) EDTA can generate 2Fe with oxynitride generation complex reaction²⁺EDTA (NO), reaches the object of denitration, and absorption reaction formula is as follows:

2Fe²⁺EDTA+NO��2Fe²⁺EDTA(NO)

But, on the one hand Fe (II) is although EDTA denitration efficiency height, but expensive, generates 2Fe²⁺Not reclaiming complexing agent after EDTA (NO) very uneconomic, high cost can cause cannot industrial practicality;

On the other hand, in Fe (II) EDTA and flue gas in the complexation process of NO, self also it is easy to by O entrained in flue gas₂Being oxidized, formed Fe (III) EDTA of NO without assimilating activity, consume complexing agent, reaction formula is as follows:

4Fe²⁺EDTA+0₂+4H⁺��4Fe³⁰EDTA+2H₂0

And the regeneration recycling of the complexing agent of this part is also extremely important.

In a word, it is desirable to the complexing agent added regenerates recovery as much as possible, can reduce costs while ensureing high-efficiency desulfurization denitration, it is to increase the quality of ammonium sulfate product, ensure the normal operation of system.

Summary of the invention

It is an object of the invention to solve the problems of the technologies described above, it is provided that a kind of technique is simple, running cost and facility investment is low, can high efficiency synchronous desulphurization denitration, the synchronous denitrating technique based on flue gas wet ammonia process desulfurizing that energy consumption is low.

A kind of synchronous denitrating technique based on flue gas wet ammonia process desulfurizing of the present invention, concentrated solution contact reacts in upgrading tower and tower is sent into after comprising flue gas supercharging, the flue gas going out upgrading tower send in the middle part of absorption tower with the reverse contact reacts of circulating absorption solution sprayed into from tower top, draw bottom absorption tower absorbing liquid as circulating absorption solution be recycled to tower top spray drench contact with flue gas recirculation, ammonium sulfate crystallization system sent into by the reacted concentrated solution of small portion at the bottom of upgrading tower tower, in the absorbing liquid on absorption tower, add complexing agent EDTA-Fe (II) or add EDTA-Na salt and ferrous sulfate at 1: 1 in molar ratio, the EDTA-Fe in absorbing liquid (II & III) concentration is made to be 0.015��0.05mol/L, absorbing liquid a small amount of in described absorption tower is sent in described upgrading tower and mixes with concentrated solution, ammonium sulfate and the ammonium sulphite total concn of absorbing liquid in absorption tower is made to control at 5��15% (wt), pH value controls 5.0��6.5, in upgrading tower, in concentrated solution, ammonium sulfate and ammonium sulphite total concn control at 30��40% (wt), and pH value controls 4.0��4.5.

First send in the first deironing reaction tank by the reacted concentrated solution of small portion drawn at the bottom of upgrading tower tower, under stirring, the pH value of concentrated solution carries out deironing reaction after 6.8��7.6 to regulate to add ammonia soln or sal volatile in the first deironing reaction tank, reaction solution send the first settling tank precipitated and separated, lower floor sends further process containing solid slurries, and supernatant liquid sends into ammonium sulfate crystallization system.

By the 30-40% (v) that the reacted concentrated liquid measure of small portion drawn bottom upgrading tower is the absorption liquid measure being incorporated into upgrading tower from absorption tower.

Being divided into two portions by the circulating absorption solution drawn bottom absorption tower, the circulating absorption solution accounting for total lead body accumulated amount 20��60% drenches contact with flue gas recirculation by being pumped into the spray of tower top; Rest part circulating absorption solution is divided into two portions again, and part circulating absorption solution is sent into and is provided with the first regenerator column of iron filings packing layer, and by being pumped into, the spray pouring of top, absorption tower enters in tower through complexing agent recycled pulp liquid bath to go out the reaction solution of the first regenerator column; Another part circulating absorption solution sends into the 2nd deironing reaction tank, under stirring, adding ammonia soln or sal volatile in the 2nd deironing reaction tank regulates circulating absorption solution pH value to be carry out deironing reaction after 6.8��7.6, reaction solution send the 2nd settling tank precipitated and separated, lower floor sends further process containing solid slurries, and supernatant liquid sends into complexing agent recycled pulp liquid bath.

Described rest part circulating absorption solution is divided into two portions again, wherein, the a part of circulating absorption solution accounting for this part cyclic absorption liquid measure 35��60% (v) is sent to the first regenerator column, and another part circulating absorption solution accounting for this part cyclic absorption liquid measure 40��65% (v) sends into the 2nd deironing reaction tank.

After system is normally run, when EDTA-Fe (the II & III) concentration in absorbing liquid in absorption tower is lower than 0.015mol/L, then in absorption tower, fill into EDTA-Na salt so that EDTA-Fe (the II & III) concentration in absorbing liquid controls at 0.015��0.05mol/L.

Described supernatant liquid from the first reaction tank is sent into after ammonium sulfate crystallization system evaporative crystallization goes out ammonium sulfate and is formed saturated liquid, this saturated liquid is at system internal recycle, discharge by ammonium sulfate crystallization system when EDTA concentration reaches 0.2��0.35mol/L in saturated liquid and it is sent to pH regulator pond, adopting sulphuric acid soln to regulate the saturated liquid pH value in pH regulator pond to be that 5.8��6.5 rear feedings are provided with in the 2nd regenerator column of iron filings packing layer, the reaction solution going out the 2nd regenerator column sends into complexing agent recycled pulp liquid bath.

In described first regenerator column and the 2nd regenerator column, liquid is from lower to upper through iron filings packing layer, and the residence time is 15��60s.

In upgrading tower, the ammonium sulfate of concentrated solution and ammonium sulphite total concn control at 30��40% (wt), and pH value controls 4.0��4.5.

The tail gas of described evaporation and crystallization system is introduced directly in upgrading tower.

In the present invention, described EDTA concentration is the concentration summation of EDTA, EDTA-Na and EDTA-Fe in liquid (II & III).

Flue gas, based on flue gas wet ammonia process desulfurizing method, under the prerequisite not changing original wet ammonia process desulfurizing technology, is implemented synchronized desulfuring and denitrifying in conjunction with Fe (II) EDTA method by contriver. By adding complexing agent EDTA-Fe (II) in absorption tower, or add EDTA-Na salt and ferrous sulfate at 1: 1 in molar ratio, EDTA-Na salt and ferrous sulfate are reacted in absorption tower and generates EDTA-Fe (II), EDTA-Fe (II) can with reaction of nitrogen oxides, reaction formula is: 2Fe²⁺EDTA+NO��2Fe²⁺EDTA (NO) (reaction formula 1). Although kind method is more simple before adopting, but the purchase cost of complexing agent EDTA-Fe (II) is high, adopt EDTA-Na salt and ferrous sulfate purchase cost then then much low. Thus initially in absorption tower, EDTA-Na salt is being added and ferrous sulfate more directly adds complexing agent EDTA-Fe (II) effect more. Control makes EDTA-Fe (the II & III) concentration in absorbing liquid be 0.015��0.05mol/L, it is preferable that 0.03mol/L, too high can increase running cost, too low can reduce denitration efficiency.

In order to ensure the effect of denitration, absorbing liquid a small amount of in described absorption tower is sent in described upgrading tower and mixes with concentrated solution, EDTA-Fe in concentrated solution (II & III) concentration is made to be 0.04��0.1mol/L, ammonium sulfate and the ammonium sulphite total concn of absorbing liquid in absorption tower are controlled at 5��15% (wt), and pH value controls 5.0��6.5. Owing to concentrated solution containing EDTA-Fe (II), also flue gas can be carried out preliminary denitration when flue gas enters upgrading tower and concentrated solution contact desulfuriation is concentrated like this.

Further, by the reacted concentrated solution of small portion drawn at the bottom of upgrading tower tower contains a small amount of iron ion, make iron ion enter ammonium sulfate crystallization system if not adding removal, then can affect the Apparent character of desulfurizing byproduct. Therefore, need to send into deironing reaction tank by the concentrated solution drawn bottom upgrading tower and carry out deironing process. Under stirring, the pH value adding ammoniacal liquor or sal volatile adjustment solution is to 6.8��7.6, major part iron ion in concentrated solution is separated with solid phase, removed by the method for precipitated and separated, in this step, the iron of 30��80% mass percents of total iron content in concentrated solution can be made to be separated, ensure that the quality of ammonium sulfate product after crystallization.

In order to control cost while desulphurization denitration as far as possible, the EDTA in the complexing agent of input or EDTA-Na salt all needs regeneration to reclaim. And drop into the EDTA-Fe in absorption tower (II) part and can generate 2Fe with reaction of nitrogen oxides²⁺EDTA (NO), part then may generate 2Fe with the oxygen generation oxidizing reaction in flue gas³⁺EDTA. Part circulation fluid in absorption tower is introduced in the first regenerator column being full of iron filings filler, multiple reaction is carried out under the first regenerator column inner acidic environment, finally making the Fe in absorbing liquid (III) be become Fe (II) by iron reduction, the NO of EDTA-Fe (II) complexing is also reduced into NH₃Entering in absorbing liquid, the principal reaction formula related in regenerator column is: (anaerobic and aerobic state deposit):

Anaerobic state:

2Fe²⁺EDTA(NO)+Fe+8H⁺��2Fe²⁺EDTA+Fe²⁺(OH)₂+2NH₃(3)

NH₃+H⁺��NH₄ ⁺(4)

Aerobic state:

2Fe²⁺EDTA(N0)+Fe+8H⁺One 2Fe²⁺EDTA+Fe²⁺(0H)₂+2NH₃(5)

4Fe²+EDTA+0₂+4H⁺��4Fe³⁰EDTA+2H₂0(6)

2Fe³⁺EDTA+Fe+20H��2Fe²⁺EDTA+Fe²⁺(OH)(7)

2Fe²⁺(0H)₂+2H⁺+O₂��2Fe³⁺(0H)₃(8)

2Fe³⁺(OH)₃+Fe��3Fe²⁺(0H)₂(9)

Major part EDTA can be reclaimed by regenerator column, but contriver finds, actual moving process is deposited a serious problem: absorbing liquid is when passing through the iron filings packing layer of regenerator column, have the oxidation that is corroded of part ferro element and enter in absorbing liquid (every time in solution after regeneration ferro element increasing amount greatly about 2��10%wt), if long-time running, iron ion content in tower can be caused constantly to increase, the normal operation of influential system, to this problem, contriver considers the part of the reacted absorbing liquid drawn is carried out deironing (being mainly ferric iron), and the clear liquid after deironing is mixed with the absorbing liquid after regeneration, with the iron level reduced in the rear absorbing liquid of regeneration. by repeatedly testing and calculate, limit the 40-80% (v) accounting for absorption tower circulating absorption solution extraction total amount for regenerating the circulating absorption solution with deironing drawn, and taking draw for regenerating the circulating absorption solution with deironing as 100%, the circulating absorption solution being sent to the first regenerator column accounts for 35��60% (v), the absorbing liquid sending into the 2nd deironing reaction tank accounts for 40��65% (v), ensure the balance of iron level in absorbing liquid with this, avoid the continuous accumulation of iron ion.

No matter it is in the first deironing reaction tank, or in the 2nd deironing reaction tank, deironing reaction process all can make a small amount of EDTA also thereupon separated, if EDTA-Fe (II & III) concentration is too low in absorbing liquid, then need absorption tower fills into EDTA to ensure that complex reaction is abundant, now only fill into EDTA-Na salt, because after system normally runs, iron ion is not lacked, therefore without the need to supplementing ferrous sulfate separately in system.

In addition, for the saturated liquid that ammonium sulfate crystallization system is drawn, when its EDTA concentration reaches 0.2��0.35mol/L, after being sent into pH regulator pond adjust ph, send into be provided with in the 2nd regenerator column of iron filings packing layer again and regenerate, the reaction solution going out the 2nd regenerator column also sends into complexing agent recycled pulp liquid bath, to increase the recovery of complexing agent further.

Useful effect:

(1) on the basis of original wet ammonia process desulfurizing technology, the nitre in complexing agent simultaneous removing flue gas is applied, thus can significantly decrease relevant facility investment and the running cost of denitration, compared with traditional substep SCR denitration technique, can reduce investment outlay and running cost more than 70%, after art breading of the present invention, can to de-except the sulfurous gas of 95% and the oxynitride of 45-50% in flue gas, sulfureous in flue gas content can be down to below 100mg/Nm3, and amount of nitrogen oxides can be down to below 200mg/Nm3.

(2) compared with tradition SCR denitration technique, adopt complexometry denitration without the need to being heated by flue gas, energy consumption can be reduced further.

(3) utilizing the regenerator column with iron filings packing layer to be regenerated by complexing agent, the de-oxynitride removed also can react generation ammonia and be back to system, such that it is able to reduce the amount filling into ammoniacal liquor, saves the ammonia source consumption of wet ammonia process desulfurizing.

(4) complexing agent can adopt EDTA-Na salt to become with ferrous sulfate proportioning, system normally run after directly to adding EDTA-Na salt in system to keep the concentration of EDTA-Fe (II & III) in absorbing liquid in absorption tower, reduce purchasing of raw materials cost.

(5) to entering the concentrated solution deironing before ammonium sulfate crystallization system, meet requirement to ensure the proterties of desulfurizing byproduct, adopt sal volatile adjust ph, be conducive to ensureing the quality of subsequent product. The volatile salt simultaneously introduced also is a kind of desulfurization absorbent, it is possible to reduce the consumption of sweetening agent-ammonia further.

(6) deironing has also been carried out for the liquid that partially absorbs drawing absorption tower, to ensure the balance of iron level in absorbing liquid in absorption tower, adopted sal volatile adjust ph, be conducive to ensureing the quality of subsequent product. The volatile salt simultaneously introduced also is a kind of desulfurization absorbent, it is possible to reduce the consumption of sweetening agent ammonia further.

Accompanying drawing explanation

Fig. 1 is process flow sheet of the present invention and system diagram.

Wherein, 1-upgrading tower, 1.1-discharge opeing mouth, 1.2-smoke inlet, 2-absorption tower, 2.1-draining hole, 2.2-exhanst gas outlet, 2.3-discharge opeing mouth, 2.4-circulation port, 3-flue, 4-wire gauzee filter, 5-concentrated solution circulated sprinkling pipeline, 6-first deironing reaction tank, 7-first settling tank, 7.1-purified liquor outlet, 7.2-slurries export, 8-ammonium sulfate crystallization system, 9-first concentration basin, 10-complexing agent recycled pulp liquid bath, 11-first regenerator column, 11.1-iron filings packing layer, 12-the 2nd deironing reaction tank, 13-the 2nd settling tank, 13.1-purified liquor outlet, 13.2-slurries export, 14-the 2nd concentration basin, the saturated liquid pipeline of 15-, 16-the 2nd regenerator column, 17-pH equalizing tank, 18-absorbing liquid circulated sprinkling pipeline.

Embodiment

System embodiment:

The stage casing of the flue 3 with absorption tower 2 of the stage casing of upgrading tower 1 through being provided with wire gauzee filter 4 is connected, and the top of institute's upgrading tower 1 is provided with smoke inlet 1.2, and the top on absorption tower 2 is provided with exhanst gas outlet 2.2. Draining hole 2.1 bottom described absorption tower 2 is connected with the concentrated solution circulated sprinkling pipeline 5 of upgrading tower 1 through pipeline. The discharge opeing mouth 1.1 of described upgrading tower 1 is connected with the first settling tank 7 through the first deironing reaction tank 6, on described first settling tank 7, the purified liquor outlet 7.1 of section is connected with ammonium sulfate crystallization system 8, the slurries outlet 7.2 of hypomere is connected with the first concentration basin 6, described ammonium sulfate crystallization system 8 is connected with pH value equalizing tank 17 through saturated liquid pipeline 15, described pH value equalizing tank 15 is connected with the 2nd regenerator column 16 of iron filings packing layer, and described 2nd regenerator column 16 connects complexing agent recycled pulp liquid bath 10 through pump and pipeline.

Circulation port 2.4 and discharge opeing mouth 2.3 it is provided with bottom described absorption tower 2, described circulation port 2.4 through absorbing liquid circulated sprinkling pipeline 18 and absorption tower 2 upper section be connected, described discharge opeing mouth 2.3 is connected 12 with the first regenerator column 11 and the 2nd deironing reaction tank respectively, described first regenerator column 11 is provided with iron filings packing layer 11.1, and described first regenerator column 11 is connected with absorption tower 2 through complexing agent recycled pulp liquid bath 10; Described 2nd deironing reaction tank 12 is connected with the 2nd settling tank 13, and the purified liquor outlet 13.1 of described 2nd settling tank 13 is also connected with complexing agent recycled pulp liquid bath 10, and the mixture export 13.2 of hypomere is connected with the 2nd concentration basin 14.

Process example:

In the present embodiment, (exhaust gas volumn is 1400000��1600000Nm about from the sinter fume of 435m2 sinter machine for flue gas³/ h), SO₂Concentration: 800��1200mg/Nm³, NOx concentration (is mainly NO): 300��400mg/Nm³. Flue-gas temperature is 90-110 DEG C (enter fly-ash separator temperature: 100-120 DEG C, go out fly-ash separator: about 100 DEG C, after supercharging, temperature slightly increases).

1) flue gas enters upgrading tower 1 downwards by the smoke inlet 1.2 of upgrading tower 1 tower top, and with circulation concentrated solution (the i.e. ammoniumsulphate soln sprayed from concentrated solution circulated sprinkling pipeline 5, concentrated solution circulation is extracted out from the bottom of tower by concentrated solution circulated sprinkling pipeline 5, drenching by tower top spray, in the present embodiment, internal circulating load is 1800m again³/ h. ) the concurrent biochemical absorption reaction of co-current contact, owing to concentrated solution containing ammonia and the EDTA-Fe (II & III) from absorption tower, thus the sulfurous gas in flue gas and oxynitride can synchronously be absorbed, most of particle in flue gas is washed simultaneously, the flue gas of high temperature takes away the part moisture content in circulation concentrated solution, circulation concentrated solution is concentrated further, when the ammonium sulfate concentrations in concentrated solution reaches 5��15% (wt), partial concentration liquid sends into the first deironing reaction tank 6 by the discharge opeing mouth 1.1 of upgrading tower 1; The concentrated liquid measure entering the first deironing reaction tank 6 is the 30-40% (volume ratio) of the absorption liquid measure introducing upgrading tower 1 from absorption tower 2; The a small amount of absorbing liquid in the described end, absorption tower 2 is sent in the concentrated solution circulated sprinkling pipeline 5 of described upgrading tower 1 together with concentrated solution by tower top circulation ejection. The ammonium sulfate and the ammonium sulphite total concn that control absorbing liquid in absorption tower control at 5��15% (wt), and pH value controls 5.0��6.5; In upgrading tower, in concentrated solution, EDTA-Fe (II & III) concentration controls at 0.04��0.1mol/L, and ammonium sulfate and ammonium sulphite total concn control at 30��40% (wt), and pH value controls 4.0��4.5. The amount of the absorbing liquid sent in reduced concentration tower 1 can be drawn by above-mentioned state modulator, the present embodiment such as, it is 60m³/ h. Sulfur dioxide in flue gas content decline 30-50% after upgrading tower 1 washs, amount of nitrogen oxides decline 5-15%, flue-gas temperature is down to 75-85 DEG C.

2) under stirring, 15-20% (wt) ammoniacal liquor or 5��10% (wt) sal volatile is added in the concentrated solution in the first deironing reaction tank 6, react after regulating concentrated solution pH value to 6.8��7.6, reaction time is 300��600s, reaction solution send the first settling tank 7 to carry out precipitated and separated, lower floor exports 7.2 feeding the first concentration basins 9 containing solid slurries through slurries and carries out press filtration, the liquid after filter pressure can loopback complexing agent regeneration tank 11, mud is discharged, supernatant liquid is sent into after ammonium sulfate crystallization system 8 evaporative crystallization goes out ammonia sulfate crystal through purified liquor outlet 7.1 and is formed saturated liquid, this saturated liquid is at system internal recycle, when EDTA concentration in saturated liquid, (described EDTA concentration is EDTA in liquid, EDTA-Na, the concentration summation of EDTA-Fe (II & III)) when reaching 0.2��0.35mol/L, saturated liquid is sent to pH value equalizing tank 17 through saturated liquid pipeline 15, the sulphuric acid soln of 10-20% (wt) is added to pH value equalizing tank 17, pH value is adjusted to 5.8-6.5, saturated liquid after adjust ph is sent in the 2nd regenerator column 16 and is regenerated, reaction solution after regeneration is sent to complexing agent recycled pulp liquid bath 10. the tail gas (gas phase) of described evaporation and crystallization system 8 is introduced directly in upgrading tower 1.

3) flue gas is sent into the stage casing on absorption tower 2 after upgrading tower 1 carries out once desulfurization denitration and washs by upgrading tower 1 stage casing through flue 3, and flue gas is filtered by wire gauzee filter 4 when through flue 3, ensures that macrobead dust can not enter in absorption tower 2;

4) flue gas enters circulating absorption solution (the i.e. ammoniumsulphate soln that the rear absorbing liquid circulated sprinkling pipeline 18 with absorption tower 2 that rises in absorption tower 2 sprays, absorbing liquid circulation is extracted out from the bottom of tower by absorbing liquid circulated sprinkling pipeline 18, drenching by tower top spray, in the present embodiment, internal circulating load is 3600m again³/ h) counter current contact reaction, then rise and discharge by exhanst gas outlet 2.2. When going into operation, in the absorbing liquid on absorption tower 2, add complexing agent EDTA-Fe (II) or add EDTA-Na salt and ferrous sulfate as complexing agent at 1: 1 in molar ratio, make the EDTA-Fe in absorbing liquid (II & III) concentration be 0.015��0.05mol/L; After system is normally run, by filling into EDTA-Na salt in absorbing liquid, taking EDTA-Fe (the II & III) concentration that maintains in absorbing liquid as 0.015��0.05mol/L; A small amount of absorbing liquid in described absorption tower 2 is sent in described upgrading tower 1 through draining hole 2.1 and mixes with concentrated solution, make EDTA-Fe in concentrated solution (II & III) concentration maintain 0.04��0.1mol/L. Interpolation and the filling into of EDTA-Na salt of described complexing agent all fill in system by complexing agent recycled pulp liquid bath 10.

5) by the bottom of the tower of absorption tower 2 absorbing liquid circulation draw as circulating absorption solution, wherein the total extraction of circulating absorption solution (or claim global cycle amount, in the present embodiment, circulating fluid volume is 3600m³/ h) 20��60% (v) circulating absorption solution by pump through absorbing liquid circulated sprinkling pipeline 18 send into tower top spray drench contact with flue gas recirculation; The circulating absorption solution of all the other 80-40% (v) is divided into two portions again in 100%, wherein, it is sent to the part circulating absorption solution (accounting for 35��60% (v) of total amount) of the first regenerator column 11, by the first regenerator column 11 bottom feed, absorbing liquid is from lower to upper through iron filings packing layer 11.1 (residence time is 15��60s), finally go out by the first regenerator column 11 top outlet overflow, in sour environment, Fe (III) in absorbing liquid is become Fe (II) by iron reduction, also has the oxidation that is corroded of part ferro element to enter in absorbing liquid simultaneously; The NO of EDTA-Fe (II) complexing is also reduced into NH₃Entering in absorbing liquid, the reaction solution going out the first regenerator column 11 sends into complexing agent recycled pulp liquid bath 10, and through being pumped into, the spray pouring of top, absorption tower 2 enters in tower the reaction solution in complexing agent recycled pulp liquid bath 10, rest part circulation fluid (accounts for the 65-40% (v) of total amount) and sends into the 2nd deironing reaction tank 12, under stirring, 15��20% ammonia solns are added or 10��20% sal volatiles react with adjust ph 6.8��7.6 in the 2nd deironing reaction tank 12, reaction time is 300��600s, reaction solution send the 2nd settling tank 13 precipitated and separated, lower floor exports 13.2 feeding the 2nd concentration basins 14 containing solid slurries through slurries and processes further, supernatant liquid sends into complexing agent recycled pulp liquid bath 10 through purified liquor outlet 13.1, reaction solution in described complexing agent slurry tank 10 can be sent into the spray of top, absorption tower 2 and drench and go out and contact with flue gas adverse current. circulation fluid in 2nd deironing reaction tank 12 can remove the ferric ion of 60��90% mass percents after reacting, the EDTA of 8��12% (wt) is precipitated in addition simultaneously enters in solid phase.

The flue-gas temperature discharged through absorption tower 2 is about 50-60 DEG C, and content of sulfur dioxide has below 100mg/Nm3, and amount of nitrogen oxides is below 200mg/Nm3.

Claims (8)

1. the synchronous denitrating technique based on flue gas wet ammonia process desulfurizing, concentrated solution contact reacts in upgrading tower and tower is sent into after comprising flue gas supercharging, the flue gas going out upgrading tower send in the middle part of absorption tower with the reverse contact reacts of circulating absorption solution sprayed into from tower top, draw bottom absorption tower absorbing liquid as circulating absorption solution be recycled to tower top spray drench contact with flue gas recirculation, ammonium sulfate crystallization system sent into by the reacted concentrated solution of small portion at the bottom of upgrading tower tower, it is characterized in that, in the absorbing liquid on absorption tower, add complexing agent EDTA-Fe (II) or add EDTA-Na salt and ferrous sulfate at 1: 1 in molar ratio, the EDTA-Fe in absorbing liquid (II & III) concentration is made to be 0.015��0.05mol/L, absorbing liquid a small amount of in described absorption tower is sent in described upgrading tower and mixes with concentrated solution, ammonium sulfate and the ammonium sulphite total concn of absorbing liquid in absorption tower is made to control at 5��15% (wt), pH value controls 5.0��6.5, in upgrading tower, in concentrated solution, ammonium sulfate and ammonium sulphite total concn control at 30��40% (wt), pH value controls 4.0��4.5, first send in the first deironing reaction tank by the reacted concentrated solution of small portion drawn at the bottom of upgrading tower tower, under stirring, the pH value of concentrated solution carries out deironing reaction after 6.8��7.6 to regulate to add ammonia soln or sal volatile in the first deironing reaction tank, reaction solution send the first settling tank precipitated and separated, lower floor sends further process containing solid slurries, supernatant liquid sends into ammonium sulfate crystallization system, wherein, it is the 30-40% (v) of the absorption liquid measure being incorporated into upgrading tower from absorption tower by the reacted concentrated liquid measure of small portion drawn bottom upgrading tower.

2. as claimed in claim 1 based on the synchronous denitrating technique of flue gas wet ammonia process desulfurizing, it is characterized in that, being divided into 2 parts by the circulating absorption solution drawn bottom absorption tower, the circulating absorption solution accounting for total lead body accumulated amount 20��60% drenches contact with flue gas recirculation by being pumped into the spray of tower top; Rest part circulating absorption solution is divided into two portions again, and part circulating absorption solution is sent into and is provided with the first regenerator column of iron filings packing layer, and by being pumped into, the spray pouring of top, absorption tower enters in tower through complexing agent recycled pulp liquid bath to go out the reaction solution of the first regenerator column; Another part circulating absorption solution sends into the 2nd deironing reaction tank, under stirring, adding ammonia soln or sal volatile in the 2nd deironing reaction tank regulates circulating absorption solution pH value to be carry out deironing reaction after 6.8��7.6, reaction solution send the 2nd settling tank precipitated and separated, lower floor sends further process containing solid slurries, and supernatant liquid sends into complexing agent recycled pulp liquid bath.

3. as claimed in claim 2 based on the synchronous denitrating technique of flue gas wet ammonia process desulfurizing, it is characterized in that, described rest part circulating absorption solution is divided into two portions again, wherein, the a part of circulating absorption solution accounting for this part cyclic absorption liquid measure 35��60% (v) is sent to the first regenerator column, and another part circulating absorption solution accounting for this part cyclic absorption liquid measure 40��65% (v) sends into the 2nd deironing reaction tank.

4. as claimed in claim 2 based on the synchronous denitrating technique of flue gas wet ammonia process desulfurizing, it is characterized in that, after system is normally run, when EDTA-Fe (the II & III) concentration in absorbing liquid in absorption tower is lower than 0.015mol/L, then in absorption tower, fill into EDTA-Na salt so that EDTA-Fe (the II & III) concentration in absorbing liquid controls at 0.015��0.05mol/L.

5. as claimed in claim 2 based on the synchronous denitrating technique of flue gas wet ammonia process desulfurizing, it is characterized in that, described supernatant liquid from the first reaction tank is sent into after ammonium sulfate crystallization system evaporative crystallization goes out ammonium sulfate and is formed saturated liquid, this saturated liquid is at system internal recycle, discharge by ammonium sulfate crystallization system when EDTA concentration reaches 0.2��0.35mol/L in saturated liquid and it is sent to pH regulator pond, sulphuric acid soln is adopted to regulate the saturated liquid pH value in pH regulator pond to be that 5.8��6.5 rear feedings are provided with in the 2nd regenerator column of iron filings packing layer, the reaction solution going out the 2nd regenerator column sends into complexing agent recycled pulp liquid bath.

6. as claimed in claim 5 based on the synchronous denitrating technique of flue gas wet ammonia process desulfurizing, it is characterised in that, in described first regenerator column and the 2nd regenerator column, liquid is from lower to upper through iron filings packing layer, and the residence time is 15��60s.

7. as claimed in claim 1 based on the synchronous denitrating technique of flue gas wet ammonia process desulfurizing, it is characterised in that, in control upgrading tower, EDTA-Fe (the II & III) concentration in concentrated solution is at 0.04��0.1mol/L.

8. as claimed in claim 1 based on the synchronous denitrating technique of flue gas wet ammonia process desulfurizing, it is characterised in that, the tail gas of described ammonium sulfate crystallization system is introduced directly in upgrading tower.