Method for eliminating dioxins in flue gas

A technology for dioxin and flue gas, applied in separation methods, chemical instruments and methods, and separation of dispersed particles, etc., can solve the problems that the background technology cannot achieve and will offset the degradation effect, so as to achieve no equipment bottleneck and dioxin content The effect of reducing and the process is simple and easy

Inactive Publication Date: 2008-08-27
TONGJI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At the same time, the effective reaction range of the SCR process is 250°C-427°C, and this is also the temperature range for the resynthesis of dioxins, which will offset part o

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0018] Example 1

[0019] A rotary kiln-type incinerator burns paper-making residues containing a large amount of plastics. The incineration capacity is 120 tons / day. The flue gas contains high concentrations of NOx, HCl, and SO. 2 After the heat recovery heating surface, the spray tower is used to spray lime and other lye to absorb the acid gas. The temperature of the flue gas entering the tower body is 360-380℃, and the temperature of the flue gas leaving the tower body is 180℃-200℃ , When the present invention is not adopted, the dioxin toxicity equivalent in the flue gas is 1.12ngI-TEQ / Nm 3 . During the implementation of the present invention, carbohydrazide is added to the alkaline spray liquid preparation tank used in the spray tower with a concentration of 0.10%wt. After use, the flue gas enters the bag filter at about 180°C, and the smoke after the dust collector The toxic equivalent of dioxin in the air is reduced to 0.1ngI-TEQ / Nm 3 .

Example Embodiment

[0020] Example 2

[0021] A 350t / d grate type garbage incinerator adopts fly ash collected by electrostatic precipitator, and then uses wet spray tower system to purify acid gas, Hg, etc. in the flue gas. When the method of the invention is not used, the dioxin in the flue gas is exhausted. The toxic equivalent of dioxin is 0.225ngI-TEQ / g, and the toxic equivalent of dioxin in fly ash is 4.2ng I-TEQ / g. When the method of the present invention is implemented, a 1% wt carbohydrazide solution is sprayed into the flue temperature zone around 650℃ in front of the superheater, and the moisture content is evaporated in the range of 650℃~550℃, then enters the superheater, and finally exhausts the dioxins in the flue gas The toxicity equivalent is 0.05ngI-TEQ / Nm 3 , The toxicity equivalent of dioxin in fly ash is 0.8ng I-TEQ / g.

Example Embodiment

[0022] Example 3

[0023] A fluidized bed waste incinerator is equipped with a heating surface after cyclone separation, and a semi-dry flue gas purification system is installed behind the heating surface. When the method of the present invention is not used, the dioxin toxicity equivalent in fly ash is 2.06ng I-TEQ / g, and the dioxin toxicity equivalent in flue gas is 0.6ng I-TEQ / Nm 3 . When the method of the present invention is implemented, the urea solution containing 4.6%wt hydrazine hydrate is sprayed into the inlet of the cyclone separator at a temperature of about 800°C to fully mix with the flue gas, and the automatic control system is used to control the spraying amount, so that the The smoke temperature drop caused by the process does not exceed 50-70℃. The toxic equivalent of dioxins in the final smoke is 0.078ngI-TEQ / Nm 3 , The dioxin toxicity equivalent in semi-dry fly ash is 0.42ngI-TEQ / g, and the NOx in exhaust smoke is reduced to below 43ppm.

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PUM

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Abstract

The invention relates to a method used for eliminating dioxin in fume. The method has the following steps that water solution containing substance of hydrazine type is sprayed into the fume containing dioxin or potentially containing dioxin so that the fume fully touches and reacts with the water solution, and the water in the solution is completely evaporated at the temperature above 160 DEG C. In this way, dioxin in the fume is eliminated. The water solution with hydrazine type substance is fresh solution prepared based on 0.05 percent to 1 percent by weight before use, and is sprayed into the fume with the temperature ranging from 200 DEG C to 600 DEG C, or into the fume with the temperature ranging from 600 DEG C to 850 DEG C. At the temperature ranging from 600 DEG C to 850 DEG C, the water in the water solution containing hydrazine can adopt urea or ammonia. At the temperature ranging from 200 DEG C to 600 DEG C, the water to dissolve hydrazine can adopt alkaline solution or urea solution in combination with purification of other noxious gases such as SOx and NOx by using a prior or a late established purification device or system, so that NOx and acidic gases in the fume are eliminated, and toxicant content in fly ash is reduced. By adopting the method, dioxin in the fume is eliminated without production of noxious byproducts. Throughout the course, no waste water or waste solid is produced; the concentration of dioxin in fly ash is reduced; the treating process is simple, and the cost of disposal is low.

Description

Technical field [0001] The invention relates to the field of energy and environmental protection, and refers to a non-transferable method for eliminating dioxins contained in flue gas or avoiding re-synthesis of dioxins in flue gas, and is suitable for various incinerator flue gases and sintering furnaces. , Electric furnace exhaust gas and other flue gas occasions that need to purify dioxin. Background technique [0002] Dioxins are persistent organic pollutants (POPs), which are particularly harmful to human health and the natural environment. In order to protect the ecological environment and protect people's health, research on pollution control and treatment of dioxin POPs has become imminent. According to the "Dioxin and Furan Emission Identification and Quantification Standard Toolkit" compiled by the United Nations Environment Programme, waste incineration and the smelting of steel and non-ferrous metals are the first two emission sources in the top ten dioxin emission so...

Claims

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Application Information

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IPC IPC(8): B01D53/70B01D53/79
Inventor 陈德珍李咸伟王永基林瑜
Owner TONGJI UNIV
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