CN101157003B - Wet-type ammonia flue gas purification technics for associated desulfuration demercuration and system - Google Patents

Wet-type ammonia flue gas purification technics for associated desulfuration demercuration and system Download PDF

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CN101157003B
CN101157003B CN2007100528794A CN200710052879A CN101157003B CN 101157003 B CN101157003 B CN 101157003B CN 2007100528794 A CN2007100528794 A CN 2007100528794A CN 200710052879 A CN200710052879 A CN 200710052879A CN 101157003 B CN101157003 B CN 101157003B
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flue gas
mercury
wet
liquid phase
demercuration
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CN2007100528794A
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CN101157003A (en
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韩旭
高翔鹏
余福胜
徐尹生
徐志安
李雄浩
李瑞鑫
朱敬
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武汉凯迪电力环保有限公司
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Abstract

The invention relates to a wet ammonia flue gas purification process for the combined sulfur and mercury removing and the system thereof. The process adopts chlorine gas as oxidizing agent to completely oxidize elemental mercury in the flue gas, and gas phase divalent mercuric ion after being oxidized is converted into liquid phase divalent mercuric ion through the improved wet ammonia desulphurization process, and further the liquid phase divalent mercuric ion is converted into stable mercuric sulfide sendimentation through liquid phase divalent mercuric ion stabilizing agent. The system comprises a flue gas oxidizing demercuration preprocessing system composed of an oxidizing agent injection device and an electrostatic precipitator, a wet ammonia flue gas sulfur and mercury removing system composed of a reaction absorbing tower, a sulfur removing accessory substance processing system composed of a cyclone cleaner, a dewaterer, and a dryer, and a mercuric sulfide HgS sendimentation processing system composed of a wastewater buffer pool, a liquid phase mercuric ion reaction chamber, and a settling pond. The process and the system can effectively improve the oxidation rate of the elemental mercury in the flue gas, overcome the defaults that the divalent mercuric ion is easy to be reduced and released and the secondary pollution problem is caused by excess oxidizing agent, and greatly improve the efficiency of sulfur removing and mercury removing.

Description

The Wet-type ammonia process flue gas purifying method and the system thereof of combined desulfurization demercuration

Technical field

The present invention relates to the gas cleaning treatment technology of coal fired power plant, refer to a kind of Wet-type ammonia process flue gas purifying method and system thereof of combined desulfurization demercuration particularly.

Background technology

Coal is the main body that China reaches interior quite over a long time from now on power station fuel at present, and coal dust firing also can bring serious mercury Hg and sulfur dioxide SO when essential thermal source and electric power resource are provided 2Pollute.According to statistics, the mercury that China's coal fired power plant in 2003 discharges in atmosphere is 86.8 tons, and the waste residue mercury emission is 28.94 tons, and mercury has severe toxicity, high volatile volatile, is easy to characteristics such as deposition and hysteresis are long in vivo, particularly enter the mercury of atmosphere, its pollution has global.The total sulfur dioxide of China's coal fired power plant discharging in 2005 is up to 2,549 ten thousand tons, and the acid rain zone of causing has thus brought tremendous loss for China's ecological environment and industrial and agricultural production near 40% of area.Therefore, fundamentally control coal fired power plant mercury Hg and sulfur dioxide SO 2Discharging extremely urgent.

At present, the means of coal-fired flue gas mercury removal mainly contain in demercuration before the burning, the burning three kinds of demercurations and burning back demercuration.Because the technology of demercuration is limited in one's ability to the removal of mercury in the fire coal in preceding demercuration of burning and the burning, so burning back demercuration is still topmost control approach.Mercury in the coal fired power plant flue gas is mainly with gaseous elemental mercury Hg 0, gaseous state divalent ion mercury Hg 2+With particle mercury Hg PThese three kinds of forms exist, wherein gaseous elemental mercury Hg 0Account for 30~80% of flue gas total mercury content.Usually, simple substance mercury Hg 0Water insoluble, and volatility is extremely strong, and difficulty removes, and divalent ion mercury Hg 2+Soluble in water, more easily remove.

For the flue gas demercuration technology of burning back, people adopt the absorbent demercuration usually.The absorbent demercuration can be removed most gaseous state divalent ion mercury Hg 2+, and simple substance mercury Hg 0But be difficult to administer, even adopt the active carbon flue gas injection technology (ACI) of external widespread usage, to simple substance mercury Hg 0Removal effect also undesirable, and the active carbon consumption is too high, influences flying dust and utilizes, operating cost is also very high simultaneously.Can scientific and technical personnel are making great efforts research always directly utilize existing smoke eliminator such as desulphurization plant, by reasonable improvement, makes it to have concurrently the effect of demercuration.

For the coal-fired flue gas desulfurization technology, the coal-burning power plant mainly adopts limestone-gypsum doctor treatment, sea water desulfuration method, circulating fluid bed flue-gas desulfurizing method and wet type ammoniacal liquor doctor treatment etc.Desulfurization method of limestone-gypsum and sea water desulfuration method exist big, the system complex of floor space, the defective that energy consumption is big, operating cost is high.Though circulating fluid bed flue-gas desulfurizing method system is simple, floor space is little, operating cost is low, to the quality requirement height of desulfurizing agent, and the desulfuration byproduct calcium sulfite is difficult to comprehensive utilization.Wet type ammoniacal liquor doctor treatment has that floor space is little, investment and operating cost is low, desulfuration byproduct is valuable chemical raw material and advantage such as crops chemical fertilizer.Therefore, utilizing existing wet ammonia process desulfurizing equipment, strengthen its demercuration performance by reasonable improvement, is a kind of flue gases purification that has potentiality of realizing the combined desulfurization demercuration.

Studies show that: the wet ammonia process desulfurizing system is to the divalent ion mercury Hg in the flue gas 2+Higher absorption efficiency is arranged, can realize desulfuration demercuration simultaneously, but adopt existing wet ammonia process desulfurizing system demercuration also to have following problem: one, because of the simple substance mercury in the flue gas is insoluble in water, when the mercury in the flue gas is many when existing with simple substance mercury form, the demercuration efficient of this method is not high; Its two, absorb divalent ion mercury in the desulfurizer slurry easily by metal ion such as iron, manganese, nickel and sulfite ion reduction, and reenter flue gas, thereby reduced the efficient of the actual removal of mercury with the form of simple substance mercury; Its three, enter the possibility that still there is secondary pollution in mercury in desulfurization wastewater or the desulfurization slag.Therefore, improve the demercuration ability of wet ammonia process desulfurizing system, reduce divalent ion mercury Hg simultaneously 2+Reduction, and collected mercury rationally handled, make it to form material stable, low toxicity, be to need the key problem that solves.

Publication number is that the Chinese invention patent ublic specification of application of CN1923337A has been introduced a kind of ozone O that utilizes 3As oxidant simultaneous oxidation sulfur dioxide SO 2, nitric oxide NO and simple substance mercury Hg 0, utilize the method for the desulfurization simultaneously of alkali liquid washing tower, denitration and demercuration then, but this method does not solve the divalent ion mercury Hg that is absorbed 2+Reduction problem in scrubbing tower, its actual demercuration efficient is not high, utilizes ozone O simultaneously 3With sulfur dioxide SO 2Be oxidized to sulfur trioxide SO 3Be unfavorable for desulfurization on the contrary, this is because sulfur trioxide SO 3In scrubbing tower, form tiny aerosol particle easily, stop to absorb slurries and sulfur trioxide SO 3Further reaction.

Publication number is the method that the Chinese invention patent ublic specification of application of CN1895745A has proposed a kind of mercury removal for smoke desulfurizing system by fortified wetting, and this method is by spraying into halogenic molecule or its compound with simple substance mercury Hg in flue 0Be oxidized to divalent ion mercury Hg 2+, again flue gas is imported wet desulfurization system, and in desulfurizer slurry, add liquid phase mercury stabilizing agent, reach the purpose of demercuration.But this method does not solve divalent ion mercury Hg in the absorption tower equally 2+Reduction discharge problem.In addition, this method is to simple substance mercury Hg 0Carry out stair oxidation and handle,, must spray into excessive oxidant, and the calcium-based desulfurizing agent slurries are limited to the absorbability of excessive oxidant in the wet desulphurization device, will inevitably cause secondary pollution thus if will realize higher mercury oxidation rate.

Summary of the invention

Purpose of the present invention is exactly Wet-type ammonia process flue gas purifying method and the system thereof that a kind of combined desulfurization demercuration will be provided.This method is based on the wet ammonia process desulfurizing system, can effectively improve the oxygenation efficiency of simple substance mercury in the flue gas, the reduction that can effectively overcome the divalent ion mercury that generates again discharges defective, can also effectively solve the secondary pollution problem that excessive oxidant brings, and then significantly improve the desulfuration demercuration efficient of wet ammonia process desulfurizing system.

For achieving the above object, the present invention organically combines a plurality of processing steps and is one, and synergy realizes simple substance mercury Hg in the flue gas by different level mutually 0Oxidation, flue gas desulfurizing and hydrargyrum-removing and divalent ion mercury Hg 2+Curing.The Wet-type ammonia process flue gas purifying method of designed combined desulfurization demercuration adopts chlorine Cl 2As oxidant to the simple substance mercury Hg in the flue gas 0Carry out abundant oxidation, and make gas phase divalent ion mercury Hg after the oxidation by improved wet ammonia process desulfurizing technology 2+Be converted into liquid phase divalent ion mercury Hg 2+, and then by liquid phase divalent ion mercury Hg 2+Stabilizing agent makes liquid phase divalent ion mercury Hg 2+Be converted into stable mercuric sulphide HgS precipitation.Its specific embodiment comprises the steps:

1) adopts chlorine Cl 2As oxidant, it is ejected in the flue gas that the coal-burning boiler unit given off, make flue gas and chlorine Cl 2Fully mix the simple substance mercury Hg in the flue gas 0With chlorine Cl 2Oxidation reaction takes place, and generates the gas phase divalent ion mercury Hg that is easy to remove rapidly 2+

2) to process chlorine Cl 2The flue gas of oxidation processes carries out electrostatic precipitation to be handled, and the most of grit that removes in the flue gas to be contained comprises mereurous sulfate, these particulate form solid phase mercury compounds of mercury oxide Hg P

3) will import the wet ammonia process desulfurizing system through the flue gas that electrostatic precipitation is handled, make sulfur in smoke SO 2With gas phase divalent ion mercury Hg 2+React with absorbent slurry respectively, generate ammonium sulfite (NH 4) 2SO 3With liquid phase divalent ion mercury Hg 2+, excessive chlorine Cl in the flue gas 2Also be absorbed the agent slurries and absorb, generate ammonium chloride NH 4Cl;

4) absorbent slurry through the desulfuration demercuration reaction is carried out forced oxidation, make ammonium sulfite (NH wherein 4) 2SO 3Change into ammonium sulfate (NH 4) 2SO 4, with the liquid phase divalent ion mercury Hg that is generated 2+, ammonium chloride NH 4Cl exports from the plasma discharge mouth of wet ammonia process desulfurizing system together;

5) slurries from the plasma discharge mouth output of wet ammonia process desulfurizing system are carried out rotational flow separation, dehydration and dry the processing, obtain byproduct of ammonium sulfate (NH 4) 2SO 4With ammonium chloride NH 4The Cl composite chemical fertilizer is realized the innoxious and recycling of desulfuration demercuration product, and is isolated desulfuration demercuration waste water;

6) in the desulfuration demercuration waste water of being discharged, add flocculation aid and liquid phase divalent ion mercury Hg 2+Stabilizing agent makes liquid phase divalent ion mercury Hg wherein 2+Be converted into stable mercuric sulphide HgS precipitation fully, prevent liquid phase divalent ion mercury Hg 2+Reduction is released into simple substance mercury Hg 0

7) flue gas through the desulfuration demercuration reaction is carried out demist and handle, remove drop entrained in the flue gas, clean flue gas is from the exhanst gas outlet output of wet ammonia process desulfurizing system.

Above-mentioned steps 1) in, preferably with chlorine Cl 2Be ejected into temperature and be in 130~150 ℃ the flue gas, simple substance mercury Hg in its emitted dose and the flue gas 0Stoichiometric proportion be 10~10 3: 1.Under this preferred temperature range and metering proportion, help chlorine Cl more 2With simple substance mercury Hg 0Oxidation reaction.The chemical equation of its reaction is as follows:

Hg+Cl 2=HgCl 2

Meanwhile, the fly ash granule in the flue gas also can catalysed promoted simple substance mercury Hg 0Oxidation, thereby realize simple substance mercury Hg in the flue gas 0To gas phase divalent ion mercury Hg 2+Efficient conversion.

Above-mentioned steps 2) in, through chlorine Cl 2Most solid phase mercury compound mereurous sulfates, mercury oxide and most grit that oxidation processes generated are disposed by electrostatic precipitator, have only gas phase divalent ion mercury Hg 2+Enter into follow-up wet ammonia process desulfurizing system, thereby subsequent technique is oversimplified.

Above-mentioned steps 3) in, sulfur in smoke SO 2At first be dissolved in water H 2O generates sulfurous acid H 2SO 3, sulfurous acid H 2SO 3Again with absorbent slurry in ammonium sulfate (NH 4) 2SO 4/ ammonium sulfite (NH 4) 2SO 3React, generate ammonium hydrogen sulfate NH 4HSO 4With ammonium bisulfite NH 4HSO 3, remove sulfur in smoke.The chemical equation of its reaction is as follows:

(1)SO 2+H 2O=H 2SO 3

(2)H 2SO 3+(NH 4) 2SO 4=NH 4HSO 4+NH 4HSO 3

(3)H 2SO 3+(NH 4) 2SO 3=2NH 4HSO 3

And preferred concentration is that 28% ammoniacal liquor constantly injects from the bottom section of wet ammonia process desulfurizing system, the pH value of absorbent slurry is controlled in 5.0~5.9 the scope, with in and flue gas desulfurization react the acidic materials that produced, with sulfurous acid H 2SO 3, ammonium hydrogen sulfate NH 4HSO 4, ammonium bisulfite NH 4HSO 3Be converted into ammonium sulfate (NH 4) 2SO 4/ ammonium sulfite (NH 4) 2SO 3, its chemical equation is:

(4)H 2SO 3+NH 3=NH 4HSO 3

(5)NH 4HSO 3+NH 3=NH 4HSO 3

(6)NH 4HSO 4+NH 3=(NH 4) 2SO 4

Meanwhile, gas phase divalent ion mercury Hg 2+Be absorbed agent slurries absorption becoming liquid phase divalent ion mercury Hg 2+, the chemical equation of its reaction is as follows:

HgCl 2+(NH 4) 2SO 4=HgSO 4+2NH 4Cl

Excessive oxidant chlorine Cl 2Also be absorbed the agent slurries and absorb generation ammonium chloride, in desulfuration demercuration, also removed excessive oxidant chlorine Cl like this 2, can effectively avoid chlorine Cl 2Produce secondary pollution.

Above-mentioned steps 4) in, from the air of wet ammonia process desulfurizing system bottom section input constantly with ammonium sulfite (NH 4) 2SO 3Oxidation reaction takes place, and generates ammonium sulfate (NH 4) 2SO 4, the oxidation air that sprays into simultaneously can also stop liquid phase divalent ion mercury Hg 2+Become simple substance mercury by the inferior sulfate radical plasma reduction, the equation of its chemical reaction is as follows:

(7)(NH 4) 2SO 3+1/2O 2=(NH 4) 2SO 4

Above-mentioned steps 6) in, preferred flocculation aid is a policapram, preferred liquid phase divalent ion mercury Hg 2+Stabilizing agent is vulcanized sodium Na 2S or organic sulfur, the amount of flocculation aid that is added and divalent ion mercury stabilizing agent is determined by the content of liquid phase divalent ion mercury in the desulfurization wastewater.Vulcanized sodium Na 2S can effectively suppress liquid phase divalent ion mercury Hg 2+By metal ion and sulfite ion reduction releases such as iron, manganese, nickel, cobalts, generate stable mercuric sulphide HgS precipitation.The equation of its chemical reaction is as follows:

Hg 2++S 2-=HgS

By gravitational settling, mercuric sulphide HgS precipitation can be separated from desulfurization waste liquor again, be obtained byproduct mercuric sulphide HgS, discharge sulfur removal technology waste water simultaneously through the allow compliance with emission standards of purified treatment.

Be to realize the Wet-type ammonia process flue gas purifying system of the custom-designed combined desulfurization demercuration of said method, mainly by the electrostatic precipitator that is used for the pre-dust removal process of flue gas, be used for the reaction absorption tower that flue gas desulfurizing and hydrargyrum-removing handles and cyclone separator, dehydrator and the drier etc. that constitute desulfuration demercuration accessory substance treatment system are formed.

Flue before the described electrostatic precipitator import is provided with oxidizer injection device, described oxidizer injection device preferably adopts the injection apparatus that has the barrier structure, can make the oxidant uniform atomizing, the import of described oxidizer injection device links to each other with the exhanst gas outlet of coal-burning boiler, and the flue after the described electrostatic precipitator outlet links to each other with the import on reaction absorption tower.

Described reaction absorption tower is provided with stock tank district, bottom from bottom to top successively, flue gas input area, bottom, absorbent spray district, middle part, and flue gas demist district, top, wherein: the stock tank district, bottom on reaction absorption tower is connected with ammoniacal liquor device for supplying and air apparatus for feeding, the flue gas input area, bottom on reaction absorption tower is provided with gas approach, the absorbent spray district, middle part on reaction absorption tower is furnished with the absorbent slurry spraying layer, the flue gas demist district, top on reaction absorption tower is furnished with demister, links to each other by external slurry circulating pump between stock tank district, bottom and the absorbent slurry spraying layer on reaction absorption tower.

The bottom plasma discharge mouth on described reaction absorption tower links to each other with the import of cyclone separator by slurry pump, the underflow opening of described cyclone separator links to each other with dehydrator, described dehydrator communicates with drier, the overfall of described cyclone separator links to each other with the waste water Buffer Pool, described waste water Buffer Pool links to each other with ionic liquid phase mercury reaction chamber by infusion pump, and described ionic liquid phase mercury reaction chamber communicates with depositing reservoir.

Compared with prior art, the present invention has following advantage:

One, the present invention organically is combined into a complete process system with flue gas desulfurizing and hydrargyrum-removing technology and device, has both simplified technological process and system architecture, has reduced occupation area of equipment, has significantly reduced the investment and the operating cost of equipment again.

They are two years old, the present invention has solved the problem of traditional wet desulphurization system a little less than to simple substance mercury removal ability in the flue gas well, the reduction that has effectively suppressed simultaneously liquid phase divalent ion mercury again discharges, and the mercury that captures is converted into stable low toxicity compounds, obtain demercuration byproduct mercuric sulphide HgS, efficiently solve mercury once with the secondary pollution problem, thereby efficiently removed the mercury in the coal-fired flue-gas.

They are three years old, the present invention has effectively controlled the excessive and secondary pollution that causes of demercuration oxidant, simultaneously desulfurization and oxidant are absorbed ammonium sulfate and the ammonium chloride recycling that generates, obtained ammonium sulfate/ammonium chloride composite chemical fertilizer, its purity can reach 99%, have good market prospects, meet the national conditions of China especially as large agricultural country.

In sum, the present invention has little, the characteristics such as energy consumption is low, process system is simple, operating cost is low, absorbent utilization rate height, operational reliability height of investment, it can not only effectively suppress the primary pollution and the secondary pollution of mercury and oxidant, and increased substantially the desulfuration demercuration efficient of wet ammonia process desulfurizing technology, its desulfuration efficiency can reach more than 95%, demercuration efficient can reach more than 90%, and treated flue gas meets the national standard of coal-fired flue-gas pollutant emission fully.

Description of drawings

Accompanying drawing is a kind of structural representation of Wet-type ammonia process flue gas purifying system of combined desulfurization demercuration.

The specific embodiment

Below at a coal-fired power station boiler unit, the present invention is described in further detail in conjunction with the accompanying drawings:

The Wet-type ammonia process flue gas purifying system of the combined desulfurization demercuration shown in the figure, by oxidizer injection device 4 with electrostatic precipitator 5 equipment such as grade and be connected flue and form flue gas oxidation demercuration pretreatment system; By equipment such as flue gas heat exchange device 6, reaction absorption tower 7, air-introduced machine 8 and chimney 9 and be connected flue and constitute wet ammonia method for flue gas desulfurizing demercuration system; Constitute the desulfurizing byproduct treatment system by equipment such as cyclone separator 10, dehydrator 16 and drier 15 and connecting line thereof; Constitute mercuric sulphide HgS precipitation process system by equipment such as waste water Buffer Pool 11, ionic liquid phase mercury reaction chamber 13 and depositing reservoir 14 and connecting line thereof.

Oxidizer injection device 4 is arranged on the electrostatic precipitator 5 imports flue before, oxidizer injection device 4 is for having the injection apparatus of barrier structure, can some female pipes and arm specifically be set according to the flue cross-sectional sizes, and the quantity of atomizer on the arm, to satisfy the needs of oxidant uniform atomizing.Flue after electrostatic precipitator 5 outlets links to each other by the import of flue gas heat exchange device 6 with reaction absorption tower 7.

Reaction absorption tower 7 is a tubular construction, be provided with stock tank district, bottom, flue gas input area, bottom, middle part absorbent spray district and flue gas demist district, top from bottom to top successively, wherein: the stock tank district, bottom on reaction absorption tower 7 is connected with ammoniacal liquor device for supplying 19 and air apparatus for feeding 20.The flue gas input area, bottom on reaction absorption tower 7 is provided with gas approach.The absorbent spray district, middle part on reaction absorption tower 7 is furnished with multiple tracks absorbent slurry spraying layer 21, and the layout quantity of absorbent slurry spraying layer 21 depends primarily on parameters such as institute's exhaust gas volumn to be processed, arranges 3~5 layers and can realize good gas-liquid mass transfer.The flue gas demist district, top on reaction absorption tower 7 is furnished with demister 22, demister 22 adopts the combination demister, constitute by upper and lower layer demist filter screen and the cleaning sprinkler part between upper and lower layer demist filter screen, can completely effectively the moisture content that is contained in the flue gas be separated.The top exhanst gas outlet on reaction absorption tower 7 communicates with chimney 9 by flue gas heat exchange device 6, air-introduced machine 8.Link to each other by external slurry circulating pump 18 between stock tank district, bottom and the absorbent slurry spraying layer 21 on reaction absorption tower 7, uninterruptedly circulate to guarantee absorbent slurry.

The bottom plasma discharge mouth on reaction absorption tower 7 links to each other with the import of cyclone separator 10 by slurry pump 17, and the underflow opening of cyclone separator 10 links to each other with dehydrator 16, and dehydrator 16 communicates with drier 15.The overfall of cyclone separator 10 links to each other with waste water Buffer Pool 11, and waste water Buffer Pool 11 links to each other with ionic liquid phase mercury reaction chamber 13 by infusion pump 12, and ionic liquid phase mercury reaction chamber 13 communicates with depositing reservoir 14.

The technical process of the Wet-type ammonia process flue gas purifying method of combined desulfurization demercuration of the present invention is such:

At first, the flue gas that coal-fired power station boiler 1 produces, enters in the oxidizer injection device 4 after its temperature is reduced to 130~150 ℃ by economizer 2 and air preheater 3, and oxidizer injection device 4 sprays into an amount of chlorine Cl to flue gas 2, simple substance mercury Hg in its emitted dose and the flue gas 0Stoichiometric proportion be 10~10 3: 1, make the simple substance mercury Hg in the flue gas 0With chlorine Cl 2Sufficient oxidation reaction takes place, and generates the gas phase divalent ion mercury Hg that is easy to remove 2+

Secondly, the flue gas of process chlorine oxidation enters electrostatic precipitator 5, and most of dust that is contained in the flue gas and particulate form solid phase mercury compound are removed by electrostatic precipitator 5.

Once more, flue gas through peroxidating and dedusting enters into reaction absorption tower 7 by flue gas heat exchange device 6, simultaneously concentration is that 28% ammoniacal liquor constantly injects from reaction stock tank district, 7 bottom, absorption tower by ammoniacal liquor device for supplying 19, and be forced into absorbent slurry spraying layer 21 by slurry circulating pump 18, the pH value of absorbent slurry is controlled in 5.0~5.9 the scope.Flue gas with from absorbent slurry spraying layer 21 ejection ammonium sulfate/the ammonium sulfite slurries are reverse contacts, fierce gas-liquid two-phase reaction takes place, make sulfur in smoke change into ammonium sulfite, simultaneously with the gas phase divalent ion mercury Hg in the flue gas 2+Change into liquid phase divalent ion mercury Hg 2+Excessive oxidant chlorine Cl in the flue gas 2Also can generate ammonium chloride NH with the absorbent slurry reaction 4Cl.

Then, the force air oxidation that the absorbent slurry that reacts through desulfuration demercuration is sprayed into by air apparatus for feeding 20, ammonium sulfite wherein is converted into ammonium sulfate, the plasma discharge mouth output of the slurries of sulfur acid ammonium and ammonium chloride 7 bottoms from the absorption tower, deliver to cyclone separator 10 by slurry pump 17, the underflow of cyclone separator 10 enters in the dehydrator 16 and dewaters, and the material after the dehydration enters drier 15 and carries out the drying processing, finally obtains desulfuration byproduct ammonium sulfate/ammonium chloride composite chemical fertilizer.The overflow of cyclone separator 10 enters waste water Buffer Pool 11, and the waste water in the waste water Buffer Pool 11 is delivered to ionic liquid phase mercury reaction chamber 13 by infusion pump 12 again.In ionic liquid phase mercury reaction chamber 13, add flocculation aid and liquid phase divalent ion mercury Hg 2+Stabilizing agent, flocculation aid adopts policapram, liquid phase divalent ion mercury Hg 2+Stabilizing agent then adopts vulcanized sodium Na 2S or organic sulfur, the amount of flocculation aid that is added and divalent ion mercury stabilizing agent is determined by the content of liquid phase divalent ion mercury in the desulfurization wastewater.Residual liquid phase divalent ion mercury Hg in the waste water 2+Can be converted into the mercuric sulphide HgS precipitation of stablizing low toxicity fully at this.The waste water of discharging from ionic liquid phase mercury reaction chamber 13 flows to depositing reservoir 14, utilizes the gravitational settling effect to obtain demercuration byproduct mercuric sulphide HgS, and the desulfuration demercuration technique waste water that reaches discharge standard is discharged by depositing reservoir 14 top gaps.

At last, the flue gas of handling through desulfuration demercuration enters in the demister 22 on reaction 7 tops, absorption tower, removes drop entrained in the flue gas, and isolated clean flue gas is discharged by the top exhanst gas outlet, through flue gas heat exchange device 6 temperature is raised to about 80 ℃, pumps to chimney 9 by air-introduced machine 8 again.

Claims (7)

1. the Wet-type ammonia process flue gas purifying method of a combined desulfurization demercuration comprises the steps:
1) adopts chlorine Cl 2As oxidant, it is ejected into temperature that the coal-burning boiler unit given off is in 130~150 ℃ the flue gas, chlorine Cl 2Simple substance mercury Hg in emitted dose and the described flue gas 0Stoichiometric proportion be 10~10 3: 1, make flue gas and chlorine Cl 2Fully mix the simple substance mercury Hg in the flue gas 0With chlorine Cl 2Oxidation reaction takes place, and generates the gas phase divalent ion mercury Hg that is easy to remove rapidly 2+
2) to process chlorine Cl 2The flue gas of oxidation processes carries out electrostatic precipitation to be handled, and the most of grit that removes in the flue gas to be contained comprises mereurous sulfate, these particulate form solid phase mercury compounds of mercury oxide Hg P
3) will import the wet ammonia process desulfurizing system through the flue gas that electrostatic precipitation is handled, make sulfur in smoke SO 2With gas phase divalent ion mercury Hg 2+React with absorbent slurry respectively, generate ammonium sulfite (NH 4) 2SO 3With liquid phase divalent ion mercury Hg 2+, excessive chlorine Cl in the flue gas 2Also be absorbed the agent slurries and absorb, generate ammonium chloride NH 4Cl;
4) absorbent slurry through the desulfuration demercuration reaction is carried out forced oxidation, make ammonium sulfite (NH wherein 4) 2SO 3Change into ammonium sulfate (NH 4) 2SO 4, with the liquid phase divalent ion mercury Hg that is generated 2+, ammonium chloride NH 4Cl exports from the plasma discharge mouth of wet ammonia process desulfurizing system together;
5) slurries from the plasma discharge mouth output of wet ammonia process desulfurizing system are carried out rotational flow separation, dehydration and dry the processing, obtain byproduct of ammonium sulfate (NH 4) 2SO 4With ammonium chloride NH 4The Cl composite chemical fertilizer, and isolate desulfuration demercuration waste water;
6) in the desulfuration demercuration waste water of being discharged, add flocculation aid and liquid phase divalent ion mercury Hg 2+Stabilizing agent makes liquid phase divalent ion mercury Hg wherein 2+Be converted into stable mercuric sulphide HgS precipitation fully, prevent liquid phase divalent ion mercury Hg 2+Reduction is released into simple substance mercury Hg 0
7) flue gas through the desulfuration demercuration reaction is carried out demist and handle, remove drop entrained in the flue gas, clean flue gas is from the exhanst gas outlet output of wet ammonia process desulfurizing system.
2. the Wet-type ammonia process flue gas purifying method of combined desulfurization demercuration according to claim 1 is characterized in that: in the said step 3), the pH value of absorbent slurry is controlled in 5.0~5.9 the scope.
3. the Wet-type ammonia process flue gas purifying method of combined desulfurization demercuration according to claim 1 and 2 is characterized in that: in the said step 6), flocculation aid adopts policapram, liquid phase divalent ion mercury Hg 2+Stabilizing agent adopts vulcanized sodium Na 2S or organic sulfur.
4. one kind is adopted the described method of claim 1 and the Wet-type ammonia process flue gas purifying system of custom-designed combined desulfurization demercuration, comprise cyclone separator (10), dehydrator (16) and the drier (15) of the electrostatic precipitator (5) that is used for the pre-dust removal process of flue gas, the reaction absorption tower (7) that is used for the flue gas desulfurizing and hydrargyrum-removing processing and formation desulfuration demercuration accessory substance treatment system, it is characterized in that:
Flue before described electrostatic precipitator (5) import is provided with oxidizer injection device (4), the import of described oxidizer injection device (4) links to each other with the exhanst gas outlet of coal-burning boiler (1), and the flue after described electrostatic precipitator (5) outlet links to each other with the import on reaction absorption tower (7);
Described reaction absorption tower (7) is provided with stock tank district, bottom from bottom to top successively, flue gas input area, bottom, absorbent spray district, middle part, and flue gas demist district, top, wherein: the stock tank district, bottom on reaction absorption tower (7) is connected with ammoniacal liquor device for supplying (19) and air apparatus for feeding (20), the flue gas input area, bottom on reaction absorption tower (7) is provided with gas approach, the absorbent spray district, middle part on reaction absorption tower (7) is furnished with absorbent slurry spraying layer (21), the flue gas demist district, top on reaction absorption tower (7) is furnished with demister (22), links to each other by external slurry circulating pump (18) between stock tank district, bottom and the absorbent slurry spraying layer (21) on reaction absorption tower (7);
The bottom plasma discharge mouth on described reaction absorption tower (7) links to each other with the import of cyclone separator (10) by slurry pump (17), the underflow opening of described cyclone separator (10) links to each other with dehydrator (16), described dehydrator (16) communicates with drier (15), the overfall of described cyclone separator (10) links to each other with waste water Buffer Pool (11), described waste water Buffer Pool (11) links to each other with ionic liquid phase mercury reaction chamber (13) by infusion pump (12), and described ionic liquid phase mercury reaction chamber (13) communicates with depositing reservoir (14).
5. the Wet-type ammonia process flue gas purifying system of combined desulfurization demercuration according to claim 4 is characterized in that: said oxidizer injection device (4) is the injection apparatus that has the barrier structure, can make the oxidant uniform atomizing.
6. according to the Wet-type ammonia process flue gas purifying system of claim 4 or 5 described combined desulfurization demercurations, it is characterized in that: said demister (22) adopts the combination demister, is made of upper and lower layer demist filter screen and the cleaning sprinkler part between upper and lower layer demist filter screen.
7. according to the Wet-type ammonia process flue gas purifying system of claim 4 or 5 described combined desulfurization demercurations, it is characterized in that: said absorbent slurry spraying layer (21) is provided with 3~5 layers.
CN2007100528794A 2007-08-02 2007-08-02 Wet-type ammonia flue gas purification technics for associated desulfuration demercuration and system CN101157003B (en)

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CN101347710B (en) * 2008-09-04 2012-10-03 北京博奇电力科技有限公司 Purification system of flue gas and method
CN101822940B (en) * 2010-05-07 2012-02-08 海宁瑞星皮革有限公司 Device for gas recovery and desulfurization at deamination tower top
CN102258936B (en) * 2011-05-31 2013-06-19 北京现代绿源环保技术有限公司 Device and method for recycling mercury in smoke multi-pollutant control technology
CN102294171B (en) * 2011-06-30 2014-07-02 光大环保能源(苏州)有限公司 Flue gas purifying system
CN102489116A (en) * 2011-12-16 2012-06-13 国电环境保护研究院 Coal flue gas mercury adsorbing removal process capable of recovering adsorbent and device utilizing same
CN102949926B (en) * 2012-11-16 2014-10-01 昆明理工大学 Method for recycling sulfur dioxide (SO2) and heavy metal in metallurgical gas
JP6217845B2 (en) * 2014-04-15 2017-10-25 株式会社Ihi Desulfurization apparatus and exhaust gas treatment system using the same
CN104474866B (en) * 2014-11-25 2016-08-24 安徽省鸿福新型建材科技有限公司 A kind of environmental protecting device for administering kiln gas
CN104743727B (en) * 2015-03-27 2017-06-06 山东大学 A kind of desulfurization wastewater cooperates with the System and method for of demercuration
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