JPH07308544A - Device for purifying organic chlorine compound stained soil - Google Patents

Abstract

PURPOSE:To make harmless by recovering organic chlorine compounds in soil constitutionally easily, economically and effectively. CONSTITUTION:Organic chlorine compounds and steam-contg. polluted gas in soil Z is sucked by a non-water sealed Roots blower type vacuum pump 11 to extract gas while the moisture is separated on the suction side by a gas- liquid separator 9. The sucked polluted gas is heated by a heater 17. The polluted gas after heating is fed to a reaction tank 20, where it is brought into contact with a solid catalyst 19 and heat-decomposed. Thereafter, the heat- decomposed combustion gas is fed to a pollution removing device 22 to subject chlorine and/or hydrochloric acid to a pollution removing treatment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the mechanical industry, the electronic industry,
Trichloroethylene, 1,1,1 after degreasing and use as a cleaning agent in various industries such as cleaning industry
-Trichloroethane, tetrachloroethylene, carbon tetrachloride, 1,1,2-trichloroethane, 1,2-dichloroethane and their biodegradation products 1-1 dichloroethylene, 1,2-cis-dichloroethylene, 1,2
The present invention relates to a purification treatment facility for organic chlorine compound-contaminated soil, which purifies soil contaminated with organic chlorine compounds such as trans-dichloroethylene and volatile organic chlorine gas.

[0002]

2. Description of the Related Art In the industrial area as described above, the site and the soil in the vicinity are polluted by an organic chlorine compound which is a harmful substance in the waste liquid, and the organic chlorine compound passes through an unsaturated zone above the groundwater level. , It penetrates into the saturated zone below it and pollutes groundwater.

In order to purify such contaminated soil, conventionally, the contaminated soil is dug out and dried in the sun or heat is applied to remove the contained organic chlorine compounds, or the soil The organic chlorine compounds are desorbed by contacting the soil with solid-liquid contact or gas-liquid contact by pouring water or injecting water vapor, and the desorbed organic chlorine compounds are discharged together with water and steam. However, there was a problem that the purification efficiency was low for the trouble.

In order to solve the above-mentioned inconvenience, in the prior art, for example, as disclosed in Japanese Unexamined Patent Publication No. 5-76618, a large number of soils may be contaminated with organic chlorine compounds. In addition to burying the perforated pipes formed by dispersing the ventilation holes of the above, connect a vacuum pump configured as a water seal type to those perforated pipes and extract the polluted gas containing the organochlorine compound in the soil by vacuum suction. Further, the extracted polluted gas is separated by a gas-liquid separator, and the polluted gas after gas-liquid separation is supplied to a solvent recovery device equipped with an activated carbon material adsorbent, and an organic chlorine compound is adsorbed on the activated carbon material adsorbent. In some cases, the organic chlorine compound was recovered by adsorbing it on a substrate and thermally desorbing it to prevent contamination of groundwater.

[0005]

However, in the case of the conventional example, when the water vapor content of the pollutant gas containing the organochlorine compound sucked from the soil is high, the water vapor is absorbed without adsorbing the organochlorine compound. There is a problem of adsorption,
In addition, there is still room for improvement in that the organic chlorine compound that has been thermally desorbed must be recovered and then the organic chlorine compound must be separately detoxified.

The present invention has been made in view of the above circumstances, and the purification treatment facility for organic chlorine compound-contaminated soil according to the first aspect of the invention is structurally simple and economical. The purpose of the present invention is to efficiently recover and detoxify organic chlorine compounds in soil, and the purification treatment facility for organic chlorine compound-contaminated soil according to the second aspect of the present invention further improves economic efficiency. The purpose is to be able to improve.

[0007]

In order to achieve the above-mentioned object, the purification treatment facility for organochlorine compound-contaminated soil according to the invention as claimed in claim 1 contaminates soil containing organochlorine compound and water vapor. A non-water-sealed vacuum pump that extracts gas by vacuum suction, a gas-liquid separator that separates moisture from the polluted gas that is sucked by the non-water-sealed vacuum pump, and pollution that is sucked by the non-water-sealed vacuum pump. A heater that heats the gas, a reaction tank that heats and decomposes the heated contaminated gas with the solid catalyst, and a combustion gas that is supplied from the reaction tank to detoxify chlorine and / or hydrochloric acid And a processing device.

In order to achieve the above-mentioned object, the purification treatment facility for organic chlorine compound-contaminated soil according to the second aspect of the invention is a purification treatment facility for organic chlorine compound-contaminated soil according to the first aspect of the invention. And a heat exchanger for preheating the pollutant gas supplied to the reaction tank by the combustion gas from the reaction tank.

[0009]

According to the constitution of the purification treatment facility for organic chlorine compound-contaminated soil of the invention according to claim 1, the non-water-sealed vacuum pump vacuum sucks the pollutant gas containing the organic chlorine compound and water vapor in the soil, Moisture is separated by a gas-liquid separator on the suction side, the temperature of the pollutant gas after gas-liquid separation is increased by adiabatic compression on the discharge side, and the pollutant gas containing an organic chlorine compound and water vapor is heated by a heater, Supplying the polluted gas to the reaction tank, heating and decomposing it in the presence of water vapor, detoxifying the decomposed chlorine and / or hydrochloric acid with a detoxification treatment device, and preventing contamination of groundwater with organic chlorine compounds. You can

According to the structure of the purification treatment facility for organic chlorine compound-contaminated soil according to the second aspect of the invention, the reaction tank is utilized by utilizing the thermal energy of the high-temperature combustion gas after the thermal decomposition taken out from the reaction tank. The temperature of the combustion gas supplied to the detoxification processing device can be lowered while preheating the contaminated gas supplied to the device.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a flow sheet showing an embodiment of a purification treatment facility for soil contaminated with organochlorine compounds. In this figure, reference numeral 1 denotes a vacuum extraction well, which is groundwater contaminated with organochlorine compounds such as trichlorethylene. It is buried in the soil Z, which is an unsaturated zone above the saturated zone W in the region.

Each of the vacuum extraction wells 1 and 1 has four lines as shown in the side view of the main part of FIG. 2A and the cross-sectional view of the main part of FIG. A wire 3 is spirally wound around the steel rods 2, and in a portion embedded in the soil Z, a pollutant gas containing an organic chlorine compound and water vapor is sucked from a gap formed between the steel rods 2 and the wire 3. It is configured to be able to. The vacuum extraction well 1 is buried by inserting it into a hole that is larger than the diameter of the vacuum extraction well 1, such as inserting a 150 mm vacuum extraction well 1 into a 200 mm diameter drill hole. . At this time, according to the property of the soil Z, coarse sand is packed around the vacuum extraction well 1 or a palm or a screen is provided in order to prevent intrusion of soil or the like.

The upper ends of the steel rods 2 are integrally connected to the steel pipe 4 by welding, and the steel pipe 4 has a first pipe 6 having a first opening / closing valve 5 interposed therein and a second opening / closing connected thereto. A gas-liquid separator 9 is connected via a second pipe 8 having a valve 7 interposed therebetween. A roots blower type vacuum pump 11 which is a non-water-sealing type vacuum pump is connected to the gas-liquid separator 9 via a third pipe 10. A screw vacuum pump or the like may be used as the non-water-sealed vacuum pump.

With the above structure, the pollutant gas containing the organic chlorine compound and water vapor in the soil Z can be extracted by vacuum suction, and the mixed water can be separated by the gas-liquid separator 9 on the suction side. There is. It is desirable that the separated water be blown into the container to expel the organic chlorine in the water by aeration, or it is expelled by heating to release it as water containing no organic chlorine compound.

Then, as shown in the graph of the relationship between the vacuum pressure and the discharge temperature and discharge amount in FIG. 3, as the vacuum pressure rises as the vacuum pump 11 sucks and discharges, the discharge amount increases. Although it decreases, the discharge temperature of the pollutant gas after gas-liquid separation can be raised by adiabatic compression on the discharge side. For example, if the temperature at the inlet side of the vacuum pump 11 is 17 [deg.] C. and suction is performed at a vacuum pressure of -200 mmHg, then the discharge temperature will rise to 80 [deg.] C.

A first heat exchanger 13 is connected to the vacuum pump 11 via a fourth pipe 12, and an electric power is supplied to the first heat exchanger 13 via a fifth pipe 14. A heater 17 composed of a second heat exchanger 16 by a heater 15 is connected to the second heat exchanger 16, and a solid composed of a titanium-silicon composite catalyst is further connected to the second heat exchanger 16 via a sixth pipe 18. A reaction tank 20 filled with the catalyst 19 is connected.

The reaction tank 19 and the first heat exchanger 13 are connected to each other through a seventh pipe 21, and the first
The heat exchanger 13 and the detoxification treatment device 22 of the eighth pipe 2
3 are connected. Although not shown, a temperature sensor for measuring the temperature of the combustion exhaust gas at the exit of the combustion exhaust gas from the reaction tank 20 of the sixth pipe 18 is provided, and the temperature sensor is connected to the controller of the electric heater 15. , For example, turn on the electric heater 15 so that the outlet temperature of the combustion exhaust gas is maintained at a set temperature such as 350 ° C.
It is configured to control −OFF.

With the above-described structure, the pollutant gas containing the organic chlorine compound and water vapor that has been sucked and discharged by the vacuum pump 11 and has increased in temperature is preheated by the combustion gas from the reaction tank 20 by the first heat exchanger 13, Further, it is heated by the electric heater 15 by the second heat exchanger 16, and further, in the reaction tank 20, it is thermally decomposed in the presence of water vapor in the presence of water vapor by contact with the solid catalyst 19, and the chlorine gas or / and the decomposition gas produced there is generated. By cooling the hydrochloric acid with the first heat exchanger 13, the temperature is supplied to the detoxification treatment device 22 at a temperature of, for example, 90 to 100 ° C. which does not cause dew condensation.

In the detoxification treatment device 22, limestone is filled, and a chlorine gas or / and hydrochloric acid is passed through the layer of the limestone to generate a salt so as to be absorbed and removed so that the pH range can be discharged, Then release it.

The relative humidity and the temperature shown in FIG. 4 are associated with the discharge accompanying the suction by the vacuum pump 11, the preheating in the first heat exchanger 13 and the heating in the second heat exchanger 16, respectively. As shown in the graph, the relative humidity of the pollutant gas containing the organic chlorine compound and water vapor is reduced, but the absolute humidity remains unchanged, and the reaction tank 20 can be thermally decomposed in the presence of water vapor.

In FIG. 1, 24 is a vacuum gauge for measuring the degree of vacuum, 25 is a flow meter for measuring the amount of gas to be sucked, and both the vacuum gauge 24 and the flow meter 25 are the third opening / closing valve. It is connected to the first pipe 5 via a ninth pipe 27 having 26 interposed therein, so that the degree of vacuum and the amount of sucked gas can be respectively confirmed.

Next, the experimental results will be described. (First Experimental Example) In the contaminated soil Z, two first and second vacuum extraction wells each having a diameter of 150 mm and a length of 5 m were buried, and a contaminated gas containing an organic chlorine compound and water vapor was vacuum pumped. Aspirated. At this time, the suction amount in the first vacuum extraction well is 1.01 m ³ / min, and the ultimate vacuum is 738.5 mmHg (-21.5
mmHg), the concentration of trichlorethylene in the sucked polluted gas from the start of suction to the end of suction is 290 to 762 ppm, while the suction amount in the second vacuum extraction well is 1.00 m ³ / min,
The ultimate vacuum was 728.3 mmHg (-31.7 mmHg), and the concentration of trichlorethylene in the sucked polluted gas from the start of suction to the end of suction was 650 to 896 ppm. Further, the suctionable range (influence radius) was a radius of 5 m.

The pollutant gas containing the organic chlorine compound and water vapor sucked in as described above was put into a reaction tank filled with 25 liters of a solid catalyst composed of titanium-silicon composite catalyst, and the outlet temperature thereof was adjusted to 350 ° C. Space velocity 2000 (50m ³ / H) per hour while controlling the electric heater to maintain
And the concentration of trichlorethylene at the inlet of the reaction tank is 180
When the pollutant gas, which was 0 ppm, was treated, the concentration of trichlorethylene at the outlet decreased to 1.8 ppm, and the decomposition rate of trichlorethylene was 99.9%, which was extremely high.

(Second Experimental Example) The first and second vacuum extraction wells were buried in the contaminated soil Z in the same manner as in the first experimental example.
A vacuum pump sucked a pollutant gas containing an organic chlorine compound and water vapor. At this time, the suction amount in the first vacuum extraction well is 1.02 m ³ / min, and the ultimate vacuum is 739.8 mmHg (-20.2 mmH
g), the concentration of trichlorethylene in the sucked polluted gas from the start of suction to the end of suction is 376-468ppm, while the suction amount in the second vacuum extraction well is 1.01m ³ / min,
The ultimate vacuum was 724.1 mmHg (-35.9 mmHg), and the concentration of trichlorethylene in the sucked polluted gas from the start of suction to the end of suction was 475 to 1040 ppm. Further, the suctionable range (influence radius) was a radius of 5 m.

When the second experimental example was treated in the same manner as the first experimental example, the decomposition rate of trichlorethylene was 99.9%, which was extremely high.

In the above-mentioned embodiment, the vacuum extraction well 1 is constructed by spirally winding the wire 3 around the steel rods 2 which are integrally connected to the steel pipe 4, and the opening ratio for suction is increased while ensuring the required strength. However, the vacuum extraction well 1 may be configured, for example, by forming a large number of ventilation holes dispersed in a steel pipe or forming slits.

The solid catalyst used in the reaction tank 20 is not limited to the titanium-silicon based composite catalyst, and for example, a titanium-zirconium based composite catalyst or a titanium-silicon-zirconium based composite catalyst can be used.

Further, in the above embodiment, the detoxification processing device 2
In No. 2, chlorine or / and hydrochloric acid are treated to be harmless by contacting with limestone, but oyster shells are used instead of limestone, or sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, calcium hydroxide aqueous solution, ammonia is used. A conventionally known device that has been used when removing fume gas such as hydrochloric acid fumes by contacting with various alkaline solutions such as an aqueous solution can be adopted.

In carrying out the present invention, for example, groundwater may be previously pumped up to a saturated zone by a pump to lower the groundwater level, and the range of the unsaturated zone may be expanded. .

The depth of the vacuum extraction well 1 ranges from 5 m to 100 m or more. For example, the depth corresponds to the area where the pollutant gas exists in the soil Z, and corresponds to the depth portion where the pollutant gas does not exist. The part is covered with a sheet so as not to be sucked so that the pollutant gas can be sucked from a predetermined region.

The heater 17 is an electric heater 15.
However, it may be configured to be heated by a high temperature gas burned by a burner.

[0032]

EFFECTS OF THE INVENTION According to the purification treatment facility for organic chlorine compound-contaminated soil according to the first aspect of the invention, the contaminated gas containing the organic chlorine compound and water vapor in the soil is absorbed by the gas-liquid separator on the suction side. Since the vacuum is sucked by the non-water-sealed vacuum pump in the state of separating the water, not only the structure for supplying water for water-sealing becomes unnecessary as in the case of the water-sealed vacuum pump,
Since the sucked polluted gas comes into contact with the water for water sealing under pressure and dissolves, add a configuration such as installing an aeration treatment facility to remove the organic chlorine compounds dissolved in the water for water sealing. Eliminates the need for simple configuration.

Moreover, on the discharge side, since the temperature of the polluted gas after gas-liquid separation can be raised by adiabatic compression, the heat energy for heating in the post-treatment can be reduced, and the heater can be downsized. It is economical because the electric heater can reduce the power consumption, and the burner or the like can reduce the fuel consumption.

Further, a pollutant gas containing an organic chlorine compound and water vapor is supplied to the reaction tank to be thermally decomposed in the presence of water vapor, and the decomposed chlorine or / and hydrochloric acid is detoxified by a detoxification processing apparatus. As a result, the water vapor sucked from the soil can be used as a hydrogen source required for the decomposition reaction, and there is no need to add a separate component for replenishing the hydrogen source. Therefore, the organic chlorine compounds in the soil can be efficiently recovered and detoxified.

According to the purification treatment facility for organic chlorine compound-contaminated soil according to the second aspect of the present invention, the contaminated gas supplied to the reaction tank is preheated by using the thermal energy of the high temperature combustion gas from the reaction tank. Therefore, it is possible to further reduce the size of the heater and further reduce the power consumption or the amount of fuel used. On the other hand, the temperature of the combustion gas supplied to the detoxification treatment device can be lowered without adding a separate cooling device. It has become possible to further improve economic efficiency.

[Brief description of drawings]

FIG. 1 is a flow sheet showing an example of a purification treatment facility for organic chlorine compound-contaminated soil according to the present invention.

2A is a side view of a main part of a vacuum extraction well, and FIG. 2B is a cross-sectional view of the vacuum extraction well.

FIG. 3 is a graph showing the correlation between vacuum pressure, discharge temperature, and discharge amount.

FIG. 4 is a graph showing a correlation between temperature and relative humidity.

[Explanation of symbols]

1 ... Vacuum extraction well 9 ... Gas-liquid separator 11 ... Roots blower type vacuum pump as a non-water-sealing type vacuum pump 13 ... 1st heat exchanger 17 ... Heater 19 ... Solid catalyst 20 ... Reaction tank 22 ... Detoxification treatment Device Z ... soil

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location B01D 53/68 B01D 53/34 134 E 134 A (72) Inventor Noboru Takei 5-5 Hongo, Bunkyo-ku, Tokyo No. 16 Organo Co., Ltd.

Claims (2)

[Claims] 1. A non-water-sealed vacuum pump for extracting a pollutant gas containing an organic chlorine compound and water vapor from soil by vacuum suction, and separating water from the pollutant gas sucked by the non-water-sealed vacuum pump. A gas-liquid separator, a heater for heating the pollutant gas sucked by the non-water-sealed vacuum pump, a reaction tank for heating and decomposing the polluted gas after heating with a solid catalyst, and a reactor from the reaction tank A detoxification treatment device for detoxifying chlorine and / or hydrochloric acid by supplying combustion gas, and a purification treatment facility for organic chlorine compound-contaminated soil. 2. A purification treatment facility for organic chlorine compound-contaminated soil, comprising a heat exchanger for preheating the pollutant gas supplied to the reaction tank by the combustion gas from the reaction tank according to claim 1.