JP2003019420A - Method for cleaning volatile organic halogen compound- containing air - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a continuous method for cleaning a volatile halogen compound by which a volatile halogen compound contained in the air, and harmful for the human body is recovered and concentrated by activated carbon or a hollow fiber membrane, and is decomposed by silent discharge or creeping discharge, and the produced inorganic halogen is neutralized with an inorganic alkaline substance such as calcium carbonate. SOLUTION: The apparatus consists of a recovering and concentrating part, a discharge decomposing part, and an inorganic halogen neutralizing part, and the air containing a volatile halogen compound is introduced into the recovering and concentrating part, and is cleaned; wherein, activated carbon or a hollow fiber membrane provided with a heater for reproduction is used in the recovering and concentrating part, silent or creeping discharge is performed in the discharge decomposing part, and inorganic alkaline substance such as calcium carbonate is used in the inorganic halogen neutralizing part.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a technology for purifying air contaminated with harmful volatile organic halogen compounds (hereinafter referred to as pollutants) such as trichloroethylene, tetrachloroethylene, and methyl bromide.

[0002]

2. Description of the Related Art There are several techniques for purifying air containing pollutants such as trichlorethylene, which are harmful to the human body, but the adsorption method using activated carbon is generally used. The used activated carbon that has absorbed pollutants is either reused by regeneration with superheated steam or incinerated. However, in the case of regeneration with superheated steam, not only a generator for heating steam is separately required, but also decontamination treatment of regenerated pollutants and condensed water contaminated with the pollutants is further required. On the other hand, in the incineration method, the inorganic halogen generated during combustion causes severe damage to the incinerator, and furthermore, there is a possibility that toxic dioxins are generated. Although a decomposition method using ultraviolet rays has also been proposed, this method is effective when the concentration of pollutants is low, but it has the drawback that it cannot be decomposed sufficiently at high concentrations. It is difficult to process.

[0003]

Among the conventional methods for purifying air containing pollutants, the activated carbon method requires incineration of used activated carbon or a treatment step of regenerated pollutants, and the ultraviolet method requires high processing. In the case of air containing a high concentration of pollutants, the processing equipment becomes large and a large installation area is required for sufficient purification. In the present invention, the device is downsized by devising the collection and detoxification treatment of pollutants in the same device, and is particularly associated with soil purification such as a small-scale cleaning shop in a city where there is no room on the site. It contributes to the purification of polluted air generated as a result. Also, in the discharge treatment,
Even if the temperature is low, it decomposes hardly-decomposable organic substances, so that generation of dioxins can be virtually eliminated.

[0004]

DISCLOSURE OF THE INVENTION According to the present invention, regenerated air containing pollutants at a high concentration is obtained by recovering and concentrating pollutants with heated air regenerated activated carbon or hollow fiber membranes to purify air containing pollutants. Alternatively, it is a continuous method in which the permeated air is immediately introduced into the discharge part and decomposed to render it harmless. With this method, the volume of regenerated air or permeated air can be made much smaller than the amount of air to be treated, so the amount of air to be treated in the discharge part is reduced and the electric power required for discharge treatment is minimized, resulting in purification cost. Can be significantly reduced. Further, sodium halide or calcium halide generated by the treatment is a harmless substance and does not require further treatment.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, first, contaminated air is brought into contact with an activated carbon portion to remove and release pollutants. Immediately before the pollutant begins to leak from the activated carbon, the ventilation is stopped, and the activated carbon is heated while ventilating a small amount of air to expel the adsorbed contaminant. Air containing a high concentration of the pollutant is directly introduced into the discharge part to decompose it. The air discharged from the discharge part is introduced into a neutralization part containing an inorganic alkaline substance to remove the inorganic halogen generated by the decomposition. Here, two activated carbon parts are provided so that one is adsorbed and the other is regenerated. By replacing two immediately before the end point of adsorption, it becomes possible to continuously purify contaminated air.
The activated carbon part used in the present invention is equipped with a heater for heating on the outside or inside. Specifically, divert a two-cylinder heatless air dryer to replace the filler with granular activated carbon,
Equipped with a heater, the timer alternately switches between adsorption and regeneration.

On the other hand, when a hollow fiber membrane is used for collecting and concentrating pollutants, contaminated air is introduced into the hollow fiber and the outside is depressurized by a vacuum pump. The pump exhaust is introduced into the discharge section. Here, the material of the membrane is preferably non-porous silicone.

As the discharge part, a commercially available ozone generator of silent discharge type or creeping discharge type can be used if the gas contact part is acid resistant.

As the neutralizing section, a packed cylinder of granular limestone or soda lime, or a washing tower of sodium carbonate aqueous solution or lime milk is suitable. Here, the inorganic halogen becomes a harmless substance such as sodium or calcium halide, or sodium or calcium hypohalite and can be discharged into the sewer.

In practicing the present invention, the recovery concentrator is selected according to the concentration of contaminants. That is, it is desirable to use a hollow fiber membrane when the concentration of pollutants in the air is relatively low, and to use activated carbon when the concentration is high. In addition, the discharge part uses silent discharge when pollutants are relatively easy to decompose,
In the case of persistent chlorine-based materials, creeping discharge is suitable.

[00010]

EFFECTS OF THE INVENTION Volatile organic halogen compounds which are rendered harmless in the present invention include tetrachloroethylene, trichloroethylene, 1.2-dichloroethylene, chloroethylene, carbon tetrachloride, chloroform, methylene chloride, and 1.
1.1-trichloroethane, 1.2-dichloroethane,
Examples thereof include methylene bromide and methyl bromide. Since the apparatus according to the present invention can be easily made compact due to its structure, it requires a small installation area. For example, it is possible to carry out soil purification on a site contaminated with tetrachlorethylene while operating in a cleaning plant in the city. Further, since maintenance in normal times is only replenishment of the neutralizing agent, labor can be saved.

[00011]

EXAMPLES In the present invention, a suitable combination of the collecting and concentrating section and the discharging section is selected according to the kind and concentration of the pollutant. An example is shown in Table-1.

[0012]

According to the present invention, the pollutants can be collected and detoxified in the same apparatus, the miniaturization can be adapted to a small-scale scene, and the maintenance can be minimized. The effect of contributing to cost reduction is great.

Claims (6)

[Claims] 1. A continuous air purification method in which a volatile organic halogen compound in the air is recovered and concentrated by a hollow fiber membrane or activated carbon, decomposed by a discharge part, and then the produced inorganic halogen is neutralized with an alkaline substance. 2. The purification method according to claim 1, wherein the material of the hollow fiber membrane is silicone. 3. The purification method according to claim 1, wherein the activated carbon is an air heat regeneration type. 4. The cleaning method according to claim 1, wherein the discharge part is a silent discharge type. 5. The purification method according to claim 1, wherein the discharge part is a creeping discharge type. 6. The purification method according to claim 1, wherein the alkaline substance is sodium carbonate, calcium carbonate, calcium hydroxide or soda lime.