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Method for removing total mercury from coal burning smoke

A coal-fired flue gas removal technology, which is applied in separation methods, chemical instruments and methods, dispersed particle separation, etc., can solve the problems of difficult removal, large addition amount, and increased operation difficulty, and achieves simple method and convenient operation. Effect

Inactive Publication Date: 2010-10-06
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0020] Through analysis, we found that this technology still has two deficiencies: (1) Na 2 S 4 The amount of addition is particularly large, and the cost of mercury removal is very expensive
This has also greatly increased the cost of mercury removal (as we have learned: Na 2 S 4 The market price is about 6000 yuan / t, the content is 30%)
(2) There are problems in the mechanism of mercury removal
[0040] A higher mercury removal rate can be obtained by using the PAC injection method, but the particle size of the activated carbon is extremely fine (μm level), the ratio of Hg / C is extremely small (1:3000-1:18000), and the dispersibility in the flue gas Better and burning specific coal types, which will greatly increase the difficulty of operation, resulting in higher removal costs
Although the sodium tetrasulfide injection method can remove different forms of mercury in the flue gas, the removal cost is also very expensive, and toxic H may also be produced during the removal process. 2 S gas
FGD device can mainly remove water-soluble Hg 2+ , while for Hg 0 Difficult to remove

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0064] The concentration of sulfur dioxide in the coal-fired flue gas of a power plant in Guangdong is 1300mg / Nm 3 , the content of total mercury in flue gas is 11.1μg / Nm 3. The plant uses lime (stone)-gypsum wet method for flue gas desulfurization, and the desulfurization rate is 87Wt.%. Add 3mol / L alkali sulfide solution accounting for 1.5‰ of its volume to the lime (stone) circulating absorbent (i.e. desulfurizer), mix well and desulfurize and demercurize in the absorption tower. %, the total mercury content in the treated flue gas is only 2.3μg / Nm 3 , The mercury removal rate reaches 79.3%. The removal cost is low and the operation is convenient. And it will not cause secondary pollution to the environment.

Embodiment 2

[0066] The concentration of sulfur dioxide in the coal-fired flue gas of an industrial boiler factory in Guangzhou is 95mg / Nm 3 , the total mercury content in flue gas is 14.8μg / Nm 3 . The plant adopts lime (stone)-gypsum wet method for flue gas desulfurization, and the desulfurization rate is above 85Wt.%. Add a 3mol / L alkali sulfide solution with a volume of 4‰ into the lime (stone) circulating absorbent, mix well and then carry out desulfurization and mercury removal in the absorption tower. Under the condition that the desulfurization rate is still stable above 85%, after treatment The total mercury content in the flue gas is only 3.2μg / Nm 3 , The mercury removal rate reaches 78.4%. The removal cost is low and the operation is convenient. And it will not cause secondary pollution to the environment.

Embodiment 3

[0068] The concentration of sulfur dioxide in the coal-fired flue gas of a thermal power plant in Shaoguan, Guangdong is 1400mg / Nm 3 , the content of total mercury in flue gas is 17.9μg / Nm 3 . The plant uses lime (stone) - gypsum wet method for flue gas desulfurization, with an average desulfurization rate of 84%. Add 9 / 10,000 volume of 2.4mol / L alkali sulfide solution into the lime (stone) circulating absorbent, mix well and then desulfurize and demercurize in the absorption tower, and the desulfurization rate is stable within the range of 81-87% , the total mercury content in the treated flue gas is only 5.8μg / Nm 3 , The mercury removal rate reaches 67.6%. The removal cost is low and the operation is convenient. And it will not cause secondary pollution to the environment.

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Abstract

The invention discloses a method for removing total mercury from coal burning smoke, which comprises the following steps of: mixing a lime (limestone) desulfurizing agent and a sodium sulfide mercury remover uniformly, spraying the uniformly mixed solution into a desulfurizing tower during lime (limestone)-gypsum wet smoke desulfuration, and removing the total mercury from the smoke at the same time during the lime (limestone)-gypsum wet smoke desulfuration. The method is simple and convenient to operate, does not need great reformation on the conventional desulfuration facilities, has lower mercury removal cost, and does not produce secondary pollution to the environment.

Description

technical field [0001] The invention relates to a method for removing mercury pollutants in coal-fired flue gas, in particular to a method for removing mercury pollutants in flue gas discharged by coal-fired enterprises such as major power plants and industrial boiler factories. Background technique [0002] Mercury has become the most concerned air pollutant of toxic metal elements due to its unique volatility, persistence and bioaccumulation. 2 and NO X Then there is another category of air pollutants that need to be controlled on a large scale. According to statistics: the global annual atmospheric mercury emission caused by human factors is 2000-3400t. Among them, the mercury emissions caused by coal burning process accounted for about 1 / 3, becoming the largest source of man-made mercury pollution. [0003] my country is a country where coal is the main energy source, and coal accounts for about 2 / 3 of the primary energy consumption. Analysis of coal samples from maj...

Claims

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Application Information

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IPC IPC(8): B01D53/78B01D53/50B01D53/64
Inventor 石林
Owner SOUTH CHINA UNIV OF TECH
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