JPH0445827A - Exhaust gas treatment method - Google Patents

Abstract

PURPOSE:To efficiently remove harmful materials by adding Ca(OH)2 to an exhaust gas to effect the reaction thereof with the SOx, etc., in the exhaust gas, collecting dust at a specific temp. or above, adding an assistant to the exhaust gas after the treatment and collecting the dust of Hg, etc., in the exhaust gas at a specific temp. or below. CONSTITUTION:The Ca(OH)2 is added to the exhaust gas to effect the reaction thereof with the acidic harmful materials, such as HCl and SOx in the exhaust gas and the generated products are collected at >=150 deg.C in a 1st stage 1. Further, the assistant (e.g., active carbon) is added to the exhaust gas after the above- mentioned treatment and the harmful materials, such as Hg and org. chlorine compd. and assistant remaining in the exhaust gas are collected at <=150 deg.C in a 2nd stage 4. Consequently, all of the harmful materials in the exhaust gas are removed with a high removal rate and the exhaust gas is cleaned.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a method for treating combustion exhaust gas discharged from various boilers, various heating furnaces, garbage incinerators, etc. HCl, SOx, Hg,
This invention relates to an exhaust gas treatment method that removes harmful substances such as organic chlorine compounds with a high removal rate.

[Prior art and problems to be solved] In general, methods for treating combustion exhaust gas containing HCl include:
Ca (OH)2 is added to the exhaust gas as a desalinating agent, and HC
Ca produced by the reaction between L and Ca (OH) 2
A method of collecting and removing C/2 using a dust collector such as a bag filter is used. However, this reaction product C
Since aC/2 exhibits a strong deliquescent property especially at low temperatures below 150°C, the deliquescent liquid of Ca C/2 may pass through a filter cloth, or the deliquescent liquid of Ca C/2 and the accompanying dust may They may cause damage to the filter cloth and cause clogging of the filter cloth, and furthermore, these may adhere to the das I-1 and II outlet mechanisms and impede the smooth operation of the mechanisms. ,
There is a problem in that the sealing performance of the mechanism is reduced. Therefore, in order to avoid such troubles caused by the deliquescence of CaC/2, the dust collector is operated at a temperature that does not cause deliquescence of CaCl2, that is, 1.50'C or higher.

However, at high temperatures of 150°C or higher, the vapor pressure of Hg, which is a harmful component other than HCI contained in exhaust gas, increases, and the vaporized Hg does not pass through the filter cloth.
g removal rate is significantly reduced. In addition, activated carbon,
The use of auxiliary agents such as sulfides and alumina-based silicates has also been proposed, but in the one-step treatment described above,
The problem is that the auxiliary agent gets mixed into a large amount of dust and its function is not fully demonstrated.

In view of the above-mentioned circumstances, the present invention prevents the deliquescence of CaC/, eliminates clogging of the filter cloth, operational failure of the dust discharge mechanism, and poor sealing performance, and eliminates the problem of H2O in the exhaust gas.
Acidic harmful substances such as C/ and SOx can be removed at a high removal rate, and the function of the auxiliary agent is fully demonstrated to remove residual harmful substances such as Hg and organic chlorine compounds at a high removal rate. The purpose of the present invention is to provide an exhaust gas treatment method that can

[Means for solving the problem] The exhaust gas treatment method according to the present invention has been devised to achieve the above object, and it adds Ca(OH)2 to the exhaust gas to eliminate acidic harmful substances such as HCe and SOX in the exhaust gas. In the first stage, the generated product is collected at a temperature of 150°C or higher to avoid the reaction, and an auxiliary agent is added to the exhaust gas after the above treatment, and υ] gas 1
The second stage collects harmful substances such as Hg and organic chlorine compounds and auxiliary agents remaining in the air at a temperature of 150°C or less.

As the high temperature dust collector to be used for the first stage dust collection, a bag filter-1 electric dust collector, an inertial dust collector, ie, a cyclone, etc. can be used. A bag filter is suitable as a low-temperature dust collector to be used for first-stage dust collection.

The reaction aid used in the second stage works to promote the removal of harmful substances such as Hg and organic chlorine compounds remaining in the exhaust gas. Examples include activated carbon, sulfide, Examples include alumina-based silicates.

In order to set the second-stage dust collection temperature to 150° C. or lower, a method is used in which the exhaust gas that has passed through the first-stage high-temperature dust collector is passed through, for example, a cooling tower.

[Function] In the first stage, Ca(OH)2 is added to the exhaust gas to react with acidic harmful substances such as HC/ and SOx in the exhaust gas, and the resulting products are collected at a temperature of 150°C or higher. , C
It prevents deliquescence of aCe2, eliminates clogging of the filter cloth, operational failure of the dust discharge mechanism, and deterioration of sealing performance, and converts acidic FF harmful substances such as HC/ and SOx in the υI gas into salts such as CaCe2 and CaSOx. Can be removed with high removal rate.

In addition, in the second stage, since CaCl2 has already been removed in the first stage, operation is possible even at temperatures below 150°C, and since dust is also removed in the first stage, it can be added to the exhaust gas. The function of the auxiliary agent can be fully exhibited at a temperature of 150° C. or lower, and harmful substances such as residual Hg and organic chlorine compounds can be removed at a high removal rate.

[Example] Next, the present invention will be specifically explained with reference to the illustrated example.

In the attached drawing, H
Reacts with acidic toxic substances such as C/ and SOx. The generated products, ie, salts such as CaC/2 and CaSOx, and dust are collected at a temperature of 15% using an electrostatic precipitator (1) as a high-temperature precipitator.
Collect dust at temperatures above 0℃. The obtained collected dust is transported to the detoxification treatment equipment (2), rendered harmless, and then disposed of in a landfill. In this way, the exhaust gas is treated in the first stage (1).

The exhaust gas after the above treatment is passed through the exhaust gas cooling tower (3) to lower the temperature to 1509C or less, and then the exhaust gas is treated by adding the required amount of activated carbon as an auxiliary agent to the exhaust gas to remove the I remaining in the exhaust gas. (bag filter as a low-temperature dust collector for harmful substances such as g and organic chlorine compounds and the above auxiliary agents.
Dust is collected at a temperature of 1508C or less. The obtained collected dust is transported to the detoxification treatment equipment (2) in the same manner as above, and after being detoxified, it is disposed of in a landfill. In this way, the exhaust gas is processed in two stages "1".

[Effect of the invention] According to the exhaust gas treatment method of the present invention, in the first stage,
Adding Ca (OH)2 to exhaust gas to reduce HC/
It reacts with acidic harmful substances such as and SOx, and the resulting products are collected at a temperature of 150°C or higher, preventing deliquescence of CaCl2 and preventing clogging of the filter cloth, malfunction of the dust discharge mechanism, and reduction in sealing performance. H in exhaust gas
Acidic harmful substances such as Cρ and SOx are converted to CaCl2 and CaS.
It can be removed as a salt such as Ox at a high removal rate.

In addition, in "2nd stage 1", CaCl2 is already in 1st stage 1
-1, so operation is possible even at temperatures below 150℃, and since dust is also removed in the first stage, the function of the auxiliary agent added to the exhaust gas is fully demonstrated at temperatures below 150℃. As a result, harmful substances such as residual Hg and white organic compounds can be removed at a high removal rate.

In this way, all of the harmful substances in the exhaust gas can be removed at a high removal rate and the exhaust gas can be purified.

[Brief explanation of drawings]

The drawing is a flow sheet showing an embodiment of the invention. (1)...electrostatic precipitator, (2)...detoxification treatment equipment, (3')...exhaust gas cooling tower, (4)...bag filter etc.''2

Claims (1)

[Claims] HCl in the exhaust gas is reduced by adding Ca(OH)_2 to the exhaust gas.
The first stage involves reacting with acidic harmful substances such as and SO_x, and collecting the resulting products at a temperature of 150°C or higher.The first stage involves adding an auxiliary agent to the exhaust gas after the above treatment, and removing the Hg and organic substances remaining in the exhaust gas. An exhaust gas treatment method consisting of a second stage that collects harmful substances such as chlorine compounds and auxiliary agents at a temperature of 150°C or less.