CN102553522A - Oxidative adsorbent for removing mercury from coal-burning flue gas - Google Patents

Abstract

The invention provides a preparation method of an oxidative adsorbent for removing mercury from coal-burning flue gas and an application condition thereof. The adsorbent is prepared by taking a mixture of montmorillonite and active carbon as a carrier, taking loaded copper chloride and manganese chloride as active ingredients and taking a mixed solution of water and acetone as a solution as well as a suspending agent through procedures including soaking, evaporative drying, baking, activating, grinding and the like. The adsorbent is used by injecting into flue gas of which the temperature is 60-340 DEG C. The preparation and use costs of the adsorbent are lower than those of an active carbon adsorbent, and over 85 percent of flue gas mercury removing rate can be reached.

Description

A kind of oxidisability adsorbent that is used for the coal-fired flue-gas mercury removal

Affiliated technical field

Patent of the present invention relates to a kind of coal-fired flue-gas that is used for and pollutes control, removes the adsorbent of heavy metal contaminants mercury in the flue gas.

Technical background

Mercury and compound thereof are a kind of important environmental contaminants, and it threatens people's life and central nervous system, has tangible toxicity.Mercury very easily discharges into environment because of mankind's activity or natural source, and in environment its long-term existence.Mercury can move through food chain, and accumulation in vivo; And, can between different areas, move through multiple environment circulation.Have research to show, big bicycle pump sedimentation is the important channel of causing mercury pollution in wide area and migration, therefore suppresses the important channel that the discharging of mercury in atmosphere is the control mercury pollution.

According to estimates, about 5000 tons of annual global atmosphere mercury emissions, and the mercury emission of China surpasses 650 tons, wherein because of about 300 tons of the coal-fired mercury emissions that forms.China has been considered to the maximum country of mercury emission, and wherein coal-fired maximum mercury pollution source.Other industry, as coloured, chlor-alkali, cement, waste incineration also can cause the mercury pollution of atmosphere.

In combustion product gases, the chemical species of mercury comprises simple substance mercury Hg usually⁰, and the mercury (Hg of oxidation state⁺And Hg²⁺), but in coal-fired flue-gas, mercury simple substance Hg⁰It is principal mode.With respect to the mercury of oxidation state, the simple substance mercury Hg in the coal-fired flue-gas⁰, have higher volatility, the slightly solubility in water, thereby be difficult to remove.

Also do not have a kind of method now, can remove all the various mercury in the flue gas effectively.Existing mercury control technology is included in carries out flue gas washing in the wet flue gas desulfurizer, and uses based on the adsorbent of activated carbon and the adsorbent of other types and carry out mercury absorption, is removed by inertial settling, electric sedimentation methods etc. such as filtrations then.For example, the phyllosilicate after exchanging through tin and iron ion can be used as the adsorbent of flue gas mercury, yet the production of these adsorbents and regenerate expensively and is wasted time and energy and is difficult to realize commercialization.

Although various demercuration methods are arranged, because most of coal-burning boilers all are equipped with dust pelletizing system, therefore adsorbent is injected flue gas, thereby the demercuration purification that realizes flue gas is a kind of mercury control technology that is hopeful to realize commercial Application most.In the middle of the present adsorbent of researching and developing, modal is activated carbon adsorbent, and its mercury to elemental and oxidation state all shows certain adsorption capacity.Yet some used restriction below activated carbon adsorbent existed: 1) cost an arm and a leg; 2) need very high carbon mercury ratio.Common carbon mercury mass ratio is 3000 to 100000, the flue gas lower to HCl content, and then the ratio of required carbon is higher, and is difficult to reach the mercury clearance more than 90%; 3) adding of active carbon has reduced the quality of flying dust, has influenced it as commercial exploitation, for example sells as the cement raw material additive.

Therefore developing the new oxidizing absorbent, is a kind of active demand that current practical promotion reduces mercury emissions.In general, this adsorbent can effectively be removed simple substance mercury, keep the flying dust quality, and this adsorbent also should be cheap simultaneously, to reduce the operating cost of flue gas demercuration.This adsorbent also should be to have than high-adsorption-capacity, to reduce the practical amount of adsorbent in the technical process; And spraying equipment there be not harsh the requirement to reduce equipment cost; This adsorbent also should be acidproof, with actual state of adapting to flue gas etc.All these has brought difficulty for the exploitation of novel mercury absorbent.

Summary of the invention

Cost an arm and a leg for solving the activated carbon mercury absorbent, practical amount is big, and the problem that causes the flying dust quality to descend, and the present invention provides a kind of oxidisability mercury absorbent composition that is used for removing coal-fired flue-gas mercury, and the preparation method is with the use method.This oxidisability mercury absorbent injects flue gas through the method for spraying, and in 60～340 ℃ of scopes, can realize the clearance of mercury more than 80% in the flue gas.

This oxidisability mercury absorbent is by the montmorillonite of copper chloride and manganese chloride modification and activated carbon amalgam.Montmorillonite is adopted by a large amount of in catalyst, its wide material sources, and price is relatively cheap, and has higher specific surface area (50～350m²/ g), possess absorption property and ion-exchange performance.The interpolation of active carbon is used can significantly improve the seizure absorption property of adsorbent to mercury, and copper and manganese can provide oxidisability.

The preparation method of this oxidisability mercury absorbent is an infusion process.Concrete grammar is, places the solution that contains active component to soak montmorillonite and absorbent charcoal carrier, makes adsorbent through steps such as drying, calcining, activation, grindings again.The basic principle of dipping is when porous carrier contacts with solution, and owing to the capillary pressure that surface tension effects produces, it is inner to make solution get into capillary, and the active component in the solution is adsorbed on the pore inner surface more then.

The oxidisability mercury absorbent prepares in the process, and the mass ratio of carrier active carbon and montmorillonite is 0.01～0.3, and the particle diameter of the two is 100～200 orders, i.e. 0.075～0.15mm; Active component is by copper chloride CuCl₂With manganese chloride MnCl₂Composite forming, wherein the mass ratio of manganese chloride and copper chloride is 0.1～0.5; Solvent is the mixed liquor of acetone and water, and wherein the volume ratio of acetone and water is 0.3～1.0; The total mass concentration of copper chloride and manganese chloride solution is 1～10%, and the total addition of active component is 1～20% of a carrier gross mass.Mixed solution kept 1～3 hour under vigorous stirring and room temperature condition; Be lower than evaporation drying under 60 ℃ the condition then; Solid was calcined 1～4 hour under 250～400 ℃ under nitrogen protection; Product obtains 200-400 order, the i.e. absorbent of particle diameter 0.037-0.074mm through grinding, sieving at last.

The operating temperature of this oxidisability mercury absorbent is 60～340 ℃, and more excellent serviceability temperature is 100-140 ℃; The work flue gas flow rate is 0.25-30m/s, 0～45 minute adsorbent time of staying.Its operation principle is, at first is with the simple substance mercury Hg that contains in the flue gas⁰Be oxidized into monovalence mercury Hg at adsorbent surface⁺Perhaps divalence mercury Hg²⁺, and then just mercury is adsorbed on adsorbent surface, thus mercury is removed from flue gas.

Description of drawings

Below in conjunction with accompanying drawing and embodiment the present invention is further specified.

Accompanying drawing is the device for evaluating performance figure of oxidisability mercury absorbent of the present invention.

In the accompanying drawing: 1, O₂, 2, CO₂, 3, SO₂/ N₂, 4, NO/N₂, 5, N₂, 6, mass flowmenter, 7, preheater, 8, triple valve, 9, thermometer; 10, reaction tube, 11, electric tube furnace, 12, absorbent, 13, triple valve, 14, mercury analyzer; 15, mercury absorption plant, 16, the water evaporation tube, 17, the mercury osmos tube, 18, water bath with thermostatic control, 19, super thermostatic oil bath.

The present invention adopts the small fixed adsorption system that the mercury absorption property of adsorbent is estimated.Evaluating apparatus is seen accompanying drawing, mainly by oxygen 1, and carbon dioxide 2, sulfur dioxide 3, nitric oxide 4; Nitrogen 5, mass flowmenter 6,preheater 7, triple valve 8, thermometer 9; Reaction tube 10, electric tube furnace 11, absorbent 12, triple valve 13,mercury analyzer 14; Mercuryabsorption plant 15,water evaporation tube 16, mercury osmos tube 17, water bath with thermostatic control 18, super thermostatic oil bath 19 is formed.Simulated flue gas obtains containing certain density Hg after through the mercury osmos tube⁰Simulated flue gas, mercury concentration can be controlled through changing oil bath temperature.Simulated flue gas gets into fixed bed reactors after reaching through preheating.Fixed bed reactors are formed (length is 1200mm, external diameter 4.03mm, internal diameter 2.8mm) by a quartz glass tube.Quartz ampoule inserts tube furnace, Controllable Temperature.Active testing carries out under the condition of stable state, continuous-flow.Adsorbent is got 30mg, and simulated flue gas consists of 10v% CO₂, 4v% O₂, 250ppm NO, 600ppm SO₂With 7v% steam, N₂Balance.Mercury vapour generating means mercury osmos tube carrier gas flux is 100mL/min, and import mercury concentration is 200ng/L, time of staying 0.1s.The measurement of the active size of adsorbent adopts mercury to remove ability (η), is defined as:

Hg wherein_ImportBe the molar concentration of fixed adsorbent bed import department element mercury, Hg_OutletThe molar concentration of fixed pattern adsorbent bed exit element mercury.Mercury is removed ability η and is shown that more greatly the ability of adsorbent removal element mercury is strong more.

The specific embodiment:

Below in conjunction with embodiment the present invention is described further.

Embodiment one: mix 150 purpose active carbon 20g and 150 purpose montmorillonite 80g subsequent use.Remove the 50mL ionized water and 50mL acetone is put into beaker, add 0.3g MnCl₂Manganese chloride and 0.7g CuCl₂The copper chloride powder is stirred to dissolving formation solution fully, in above-mentioned solution, adds the mixture 9.0g of active carbon and montmorillonite; Vigorous stirring 60 minutes places the decompression rotary dryer dry under 50 ℃, at last in Muffle furnace and under the nitrogen protection; Under 300 ℃, carry out activation 4 hours, the product that makes grinds, and collects between the 400-200 order; Be the particle of 0.037-0.074mm, obtain oxidisability mercury absorbent.Adsorbent can obtain to surpass 85% mercury clearance in evaluating apparatus shown in the drawings.

Embodiment two: mix 150 purpose active carbon 8g and 150 purpose montmorillonite 92g subsequent use.Remove the 20mL ionized water and 80mL acetone is put into beaker, add 0.06g MnCl₂Manganese chloride and 0.54g CuCl₂The copper chloride powder is stirred to dissolving formation solution fully, in above-mentioned solution, adds the mixture 9.4g of active carbon and montmorillonite; Vigorous stirring 60 minutes places the decompression rotary dryer dry under 50 ℃, in the Muffle furnace of nitrogen protection, under 300 ℃, carries out activation 3 hours at last; The product that makes grinds; Collection is between the 400-200 order, and promptly the particle of 0.037-0.074mm obtains oxidisability mercury absorbent.Adsorbent can obtain to surpass 80% mercury clearance in evaluating apparatus shown in the drawings.

Claims (6)

1. an oxidisability adsorbent that is applicable to the coal-fired flue-gas mercury removal is characterized in that the amalgam with montmorillonite and active carbon is a carrier, and load copper chloride and manganese chloride are as active component; With the mixed solution of water and acetone as solution and suspending agent; Through dipping, evaporation drying, calcination activation; The absorbent that grinding makes, its method for using is that sorbent injection is injected flue gas.

2. by the described oxidisability adsorbent that is applicable to the coal-fired flue-gas mercury removal of claim 1, the preparation mass ratio that it is characterized in that active carbon and montmorillonite is 0.01～0.3.

3. by the described oxidisability adsorbent that is applicable to the coal-fired flue-gas mercury removal of claim 1, the preparation mass ratio that it is characterized in that active component manganese chloride and copper chloride is 0.1～0.5; The total amount of copper chloride and manganese chloride is 1～20% of a carrier gross mass.

4. by the described oxidisability adsorbent that is applicable to the coal-fired flue-gas mercury removal of claim 1, it is characterized in that in the mixed liquor of acetone and water that the volume ratio of acetone and water is 0.3～1.0.

5. by the described oxidisability adsorbent that is applicable to the coal-fired flue-gas mercury removal of claim 1, it is characterized in that absorbent needs to calcine 1～4 hour down at 250～400 ℃.

6. by the described oxidisability adsorbent that is applicable to the coal-fired flue-gas mercury removal of claim 1, it is characterized in that the absorbent particle diameter is between 200-400 order, i.e. 0.037-0.074mm.

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