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Mercury removal for smoke desulfurizing system by fortified wetting method

A wet flue gas desulfurization and flue gas technology, applied in chemical instruments and methods, separation methods, dispersed particle separation, etc., can solve the problems of secondary pollution, elimination of mercury efficiency, low mercury removal efficiency, etc. The effect of reducing operating costs, thorough treatment, and solving the problem of secondary pollution

Inactive Publication Date: 2007-01-17
SHANGHAI JIAO TONG UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the existing wet desulfurization system for mercury removal still has the following problems: 1) Because the elemental mercury in the flue gas is difficult to dissolve in water, when the mercury in the flue gas mostly exists in the form of elemental mercury, the mercury removal efficiency of this method is not high. High; 2) Divalent mercury ions absorbed into the desulfurization solution are easily reduced by sulfite plasma, and re-enter the flue gas in the form of elemental mercury, thereby offsetting the actual mercury removal efficiency; 3) into the desulfurization solution or desulfurization residue Mercury still has the possibility of secondary pollution

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Embodiment 1 (utilizes bromine simple substance as vapor phase oxidant)

[0024] The gas-phase oxidation effect of bromine molecules on elemental mercury: take 2mL of liquid elemental bromine (analytical purity, >98%), put it into a 50mL glass vaporizer (with inlet and outlet pipes), and use a water bath to vaporize The temperature of the bottle was controlled at about 2°C. The dry air is continuously passed through the vaporizing bottle containing liquid bromine at a flow rate of 5-50ml / min, and the bromine vapor is taken out and mixed with air to form a mixed gas with a concentration of about 2%.

[0025] Using a method similar to the above, use dry air to prepare a concentration of about 100μg / m 3 The elemental mercury vapor, the flow rate of mercury-containing gas is 10-30L / min.

[0026] The above two gases are rapidly mixed in the reaction and flowed through the reactor. The reactor adopts a three-necked flask with a volume of 1000mL and is equipped with a micro...

Embodiment 2

[0033] Embodiment 2 (use bromine simple substance as gas-phase oxidant, have the oxidation reaction that fly ash participates in)

[0034] The gas distribution conditions and reaction device used are the same as in Example 1, but 1 g of about 200 mesh coal-burning fly ash is added to the reactor in advance, and the fly ash is evenly dispersed in the air flow by the fan installed inside the reactor. In order to prevent the fly ash from being taken out of the reactor by the air flow, a layer of glass wool filter layer is added at the gas outlet.

[0035] Experiments were carried out in a method similar to Example 1, at a temperature of 120°C, a gas residence time of 6 seconds, and a bromine concentration of 10mg / m 3 Under certain conditions, the oxidation rate of elemental mercury can reach 95%. It can be seen that the presence of fly ash can significantly improve the oxidation efficiency of elemental mercury.

[0036] After being washed by the lye in the absorption bottle, all...

Embodiment 3

[0037] Embodiment 3 (using calcium hypochlorite as oxygenant)

[0038] A quartz tube with a diameter of 20mm and a length of 500mm is used as the reactor, with a 200mm water jacket cooling device downstream, heated by a tubular heating furnace, and a vertically placed settling furnace. Use simulated flue gas prepared on site ([NO]=300mg / m 3 , [NO 2 ]=5mg / m 3 , [Hg 0 ]=100μg / m 3 , [SO2]=2000mg / m 3 , the rest is air), the air flow of 800ml / min passes through the reactor continuously, and passes through the total mercury, Hg in the reactor outlet gas 0 concentration to determine the effect.

[0039] Block calcium hypochlorite (analytically pure) was ground and sieved to obtain fine particles of about 200 mesh, and the calcium hypochlorite powder was added to the reaction tube at a feed rate of 2 g / h by a micro-feeder. When the temperature of the reaction tube is 600°C and the reaction is stable, [Hg 0 ] is 12μg / m 3 , so the oxidation rate of elemental mercury reaches 88%...

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PUM

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Abstract

A process for intensifying the Hg removing action of a wet fume desulfurizing system includes such steps as spraying chemical oxidant into the fume generated by burning coal, gas-phase (or catalytic) oxidizing reaction to oxidize Hg, absorbing the mercury oxide along with the 2-valence Hg in the fume by desufurizing liquid, adding the S-contained chemical additive to said desulfurizing liquid, and converting the Hg ions in desulfurizing liquid to stable Hg compound.

Description

technical field [0001] The invention relates to a method for strengthening the mercury removal effect of a wet flue gas desulfurization system. By oxidizing the elemental mercury in the flue gas and inhibiting the reduction and release of mercury ions in the desulfurization liquid, the wet desulfurization system can effectively remove mercury from the flue gas. The mercury has a high removal efficiency and converts the captured mercury into stable mercury sulfide, so as to achieve a more thorough treatment of flue gas mercury. Background technique [0002] Mercury has serious physiological toxicity. In its "Global Mercury Status Assessment" report published in February 2003, the United Nations Environment Program warned against the global mercury pollution problem. Since coal contains a certain amount of mercury, the use (mainly combustion) of a large amount of coal is one of the main causes of mercury pollution. For this reason, many countries have begun to pay attention t...

Claims

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Application Information

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IPC IPC(8): B01D53/64B01D53/50
Inventor 晏乃强吴忠标贾金平徐新华汪大翚
Owner SHANGHAI JIAO TONG UNIV
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