JP2003053327A - Equipment for separation treatment of volatile organic compound in waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate volatile organic compounds like trichloroethylene or tetrachloroethylene, etc., from the waste water, such as underground water or industrial waste water, containing the volatile organic compounds by a small- sized and high the thermal-efficiency equipment when the waste water contains the volatile organic compound described above. SOLUTION: The waste water to be treated which contains the volatile organic compounds, is boiled and evaporated in an evaporation vessel 1 and the stream thereof is sucked by suction compressing means 3 so as to decompress the inside of the evaporation vessel down to atmospheric pressure or below and is then condensed by a condenser 6. On the other hand, the waste water to be treated is passed as the cooling water for steam condensation in the condenser 6 and is then supplied to the evaporation vessel 1.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a case where wastewater such as groundwater or industrial wastewater contains a volatile organic compound such as trichlorethylene or tetrachloroethylene,
The present invention relates to an apparatus for separating and treating this volatile organic compound from wastewater.

[0002]

2. Description of the Related Art Conventionally, when treating wastewater such as groundwater or industrial wastewater, volatile organic compounds such as trichlorethylene or tetrachlorethylene contained therein are separated from the wastewater and then decomposed. Bubbling (aeration) is performed by blowing air into the wastewater to be treated, and volatile organic compounds in the wastewater to be treated are volatilized into the air blown into the wastewater to be treated, thereby separating it from the wastewater to be treated, Next, a method of decomposing the volatile organic compound by introducing the air containing the volatile organic compound to a decomposing device by adsorption treatment with activated carbon or irradiation with ultraviolet rays is adopted.

[0003]

However, in this bubbling method, the amount of bubbling air blown into the wastewater to be treated must be increased in order to increase the separation rate from the volatile organic compounds. In addition, since a large amount of air is handled, the size of the entire apparatus cannot be avoided, and the size of the blower for pumping air also increases noise and power consumption.

In the bubbling method, the volatile organic compound separated from the treated wastewater is diluted with a large amount of air blown to separate the volatile organic compound from the treated wastewater. Since the concentration of the volatile organic compound contained in the exhaust air from the wastewater to be treated is extremely low, a large apparatus and a great running cost are required for decomposing the volatile organic compound having an extremely low concentration. There is also the problem that there is.

The present invention ensures that the volatile organic compounds contained in the wastewater to be treated can be separated and treated from the wastewater to be treated with high thermal efficiency without increasing the size of the apparatus. It is a technical object to provide such a device.

[0006]

In order to achieve this technical object, the first aspect of the present invention is that "an evaporator for boiling and evaporating a waste water containing a volatile organic compound, a steam in this evaporator, Gas containing volatile organic compound gas,
A suction compression unit for sucking the inside of the evaporation can to a pressure lower than the atmospheric pressure and then compressing it to a higher pressure than the inside of the evaporation can, and a condenser for compressed gas from the suction compression unit, Furthermore, the waste water to be treated is configured to be supplied to the evaporator after passing through the condenser as cooling water for steam condensation in the condenser. It is characterized by

[0007] The second aspect of the present invention is that "a first evaporator and a second evaporator for boiling and evaporating waste water containing a volatile organic compound.
The evaporation can and the gas containing the vapor and the volatile organic compound gas in both evaporation cans are sucked so as to reduce the pressure in both evaporation cans to atmospheric pressure or less, and then compressed to a pressure higher than that in the evaporation cans. And a condenser for compressed gas from the suction compression means, further comprising:
The treated wastewater is supplied to the first evaporator after passing through the condenser as cooling water for steam condensation in the condenser, and the treated wastewater discharged from the first evaporator is
As cooling water for steam condensation in the condenser, the cooling water is passed through the condenser and then supplied to the second evaporator. It is characterized by

Still further, a third aspect of the present invention is, "In the above-mentioned first or second aspect, the condensed water containing the volatile organic compound discharged from the condenser is decomposed with an ultrasonic transmitter. It is introduced into the container. ”

[0009]

[Operation and effect of the invention] The waste water to be treated containing a volatile organic compound is boiled by introducing it into an evaporator that is depressurized below atmospheric pressure.
By evaporating, a part of the wastewater to be treated becomes water vapor, and at the same time, the volatile organic compounds contained in the wastewater to be treated are volatilized to gas at the same time as boiling and evaporation of the water to become the wastewater to be treated. Can be separated from.

Therefore, the gas containing the water vapor and the gas of the volatile organic compound in the evaporator is sucked and compressed by the suction compression means and then guided to the condenser to be condensed.

Thus, it is possible to separate the volatile organic compounds contained in the treated wastewater from the treated wastewater,
Since it is possible to surely perform at a high separation rate by evaporation and subsequent condensation instead of the above-described conventional bubbling, it is possible to achieve a large downsizing of the apparatus and a large reduction in noise and operating costs at the same time.

Moreover, after the gas containing the vapor and the volatile organic compound gas in the evaporator is sucked by the suction compression means so as to reduce the pressure in both the evaporators to the atmospheric pressure or lower, By compressing to a high pressure, the pressure inside the evaporator is reduced by suction by the suction compression means, and the waste water to be treated is boiled under reduced pressure.
Evaporation can be performed.

Furthermore, in addition to compressing the gas containing water vapor and the gas of the volatile organic compound in the evaporator by the suction compression means to a pressure higher than that in the evaporator, the gas is supplied to the condenser. , The treated wastewater is supplied to the evaporator after passing through the condenser as cooling water for steam condensation in the condenser, whereby the steam generated in the evaporator is treated wastewater in the evaporator. Since it can be used as a heat source for boiling and evaporating, the heat efficiency can be improved.

According to the structure described in claim 2,
In addition to the above-mentioned effects, boiling and evaporation of the waste water to be treated, and then separation of volatile organic compounds from the waste water to be treated by the boiling and evaporation are performed twice for the first evaporator and the second evaporator. Therefore, the separation rate of volatile organic compounds from the wastewater to be treated can be further improved.

On the other hand, the separation of the volatile organic compounds from the waste water to be treated is carried out by boiling and evaporating the waste water to be treated in the evaporator, so that in the condenser, water vapor and volatile organic compounds in the evaporator are The condensation of the gas containing the compound gas is performed. For this reason, since the condensed water condensed in the condenser has a high concentration of the volatile organic compound contained therein, the condensed water containing the volatile organic compound discharged from the condenser is As described in 3,
By introducing it into a decomposition container equipped with an ultrasonic transmitter,
By irradiating ultrasonic waves in this decomposition vessel, the volatile organic compound in the condensed water is efficiently and easily obtained with a simple device.
The decomposition treatment can be performed reliably at low running cost.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawing of FIG.

In this figure, reference numeral 1 is a first pressure-reducing type.
Reference numeral 2 denotes an evaporation can, and second reference numeral 2 denotes a pressure reducing second evaporation can.

Reference numeral 3 indicates a suction compressor which is one embodiment as a suction compression means, and the suction compressor 3 includes water vapor in the first and second evaporators 1 and 2. A gas containing a gas of a volatile organic compound is sucked through the steam ducts 4 and 5 so that the pressure inside the first evaporator 1 is reduced to atmospheric pressure or lower (for example, about 20 Torr),
The pressure inside the second evaporator 2 is reduced to atmospheric pressure or less (for example, about 20T).
orr), and is compressed to a pressure (for example, about 780 Torr) higher than that in both the evaporators 1 and 2, and the compressed gas is supplied to the condenser 6 described later via the vapor duct 3a.

The suction / compression of the gas containing water vapor and the gas of the volatile organic compound in the first evaporator 1 and the second evaporator 2 is replaced by a single suction compressor 3. Alternatively, a plurality of suction compressors arranged in series may be used.

The condenser 6 is of a multi-tube type in which a large number of heat transfer tubes 6a are bundled, and the gas compressed by the suction compressor 3 is introduced to the outside of each heat transfer tube 6a. Further, the inside of the entrance header 6b at one end is the first entrance chamber 6
b ′ and the second inlet chamber 6b ″, and the inside of the outlet header 6c at the other end is the first outlet chamber 6c ′ and the second outlet chamber 6c ″.
It is divided into and respectively.

The wastewater to be treated sent from the wastewater supply pipe 7 is the first wastewater in the inlet header 6b of the condenser 6.
It is sent to the inlet chamber 6b ', passes through each heat transfer pipe 6a, and comes from the first outlet chamber 6c' in the outlet header 6c through the pipe line 8 into the first evaporator 1 and the nozzle 9 provided at the bottom thereof. Erupted from.

The waste water to be treated, which has entered the first evaporator 1, flows out from an outlet 10 provided at a position higher than the nozzle 9 by an appropriate height H, and is condensed via a conduit 12 with a pump 11. Inside the second evaporator 2 via the pipe 13 from the second outlet chamber 6c ″ in the outlet header 6c passing through each heat transfer pipe 6a and being sent to the second inlet chamber 6b ″ in the inlet header 6b of the container 6. On the bottom of the nozzle 1
Eject from 4.

The waste water to be treated, which has entered the first evaporator 1, flows out from a discharge port 15 provided at a position higher than the nozzle 14 by an appropriate height H, and is discharged through a conduit 17 with a pump 16. It

In this structure, the waste water to be treated containing a volatile organic compound such as trichloroethylene or tetrachloroethylene is heated in the condenser 6 and then enters the first evaporator 1 which is kept at a reduced pressure. By boiling and evaporating, a part of this wastewater becomes water vapor, and at the same time, the volatile organic compounds contained in this wastewater to be treated volatilize to gas at the same time as the boiling and evaporation of the wastewater to be treated become vaporized. While being separated from the treated wastewater, the gas containing the vapor and the volatile organic compound gas in the first evaporator 1 is compressed to a higher pressure in the first evaporator 1 by the suction compressor 3. It is sent to the condenser 6 and used for heating the feed water of the treated waste water.

The waste water to be treated discharged from the first evaporator 1 is heated again by the condenser 6 and then enters the second evaporator 2 which is kept at a reduced pressure, where it is boiled and evaporated. As a result, a part of the wastewater becomes water vapor, and at the same time, the volatile organic compounds contained in the wastewater to be treated are volatilized into gas at the same time as boiling and evaporation of the wastewater to be treated and separated from the wastewater to be treated. On the other hand, the gas containing the vapor and the volatile organic compound gas in the second evaporator 2 is compressed to a higher pressure in the second evaporator 2 by the suction compressor 3, and then the condenser 6 is used. Sent to and heated for the supply of waste water to be treated.

The waste water to be treated after separating the volatile organic compounds in the second evaporator 2 in this way is
It is discharged from the inside of the second evaporator 2 via the pipe line 17 with the pump 16.

On the other hand, the condensed water in the condenser 6 is introduced into the decomposition container 19 through the pipe 18, and the ultrasonic wave is emitted by the ultrasonic wave transmission means 20 provided therein.

By the irradiation of this ultrasonic wave, the volatile organic compounds in the condensed water are decomposed into final decomposed compounds such as water, carbon dioxide gas and hydrochloric acid, and the condensed water is discharged from the pipe line 21, or While part or all of which is joined to the wastewater supply pipeline 7 via a pipeline 22 indicated by a chain double-dashed line,
The gas is introduced into the gas purifier 24 from the gas discharge pipe 23, where the undecomposed volatile organic compound is adsorbed or decomposed, and then released into the atmosphere.

In this case, according to the experiments by the present inventors, when the ultrasonic wave is applied, the ultrasonic wave is, for example, 200
By setting the frequency to KHz, cavitation is generated in the decomposition container 19, so that the generation of bubbles in the cavitation and the collapse and disappearance of the bubbles are vigorously repeated, and Decomposing a volatile organic compound dissolved in a liquid into a final decomposition compound such as water, carbon dioxide gas and hydrochloric acid in a reaction field at high temperature and high pressure when bubbles generated in the cavitation collapse and disappear. Therefore, the decomposition efficiency of the volatile organic compound by the irradiation of ultrasonic waves can be significantly improved.

In the middle of the gas discharge line 23 to the atmosphere, an adsorption type gas purifier 24 using activated carbon or the like, or a pyrolysis type gas purification in which gas is burned in the presence of a catalyst. A device is provided to prevent volatile organic compounds from being released into the atmosphere.

According to the experiments conducted by the present inventors, the boiling / evaporation of the waste water to be treated stored in the first and second evaporators 1 and 2 at the liquid depth H is determined as follows. And by setting the degree of pressure reduction below atmospheric pressure in the second evaporator 2 and / or the supply temperature of the waste water to be treated so that the liquid depth from the water surface of the waste water to be treated is deeper. ,
The separation rate when volatile organic compounds are separated from the wastewater to be treated by boiling / evaporation can be greatly improved compared to the case where the wastewater to be treated is boiled / evaporated only on the surface of the wastewater. It was.

Further, according to the experiments conducted by the present inventors, the discharge ports 10 and 15 of the first evaporator 2 and the second evaporator 2 are shown.
A part of the waste water to be treated flowing out from the pipes 25 and 26 is taken out, and the waste water is discharged from the nozzles 27 and 28 provided in the upper portions of the first and second evaporators 1 and 2, respectively.
It was possible to further improve the separation rate of the volatile organic compounds from the wastewater by irradiating ultrasonic waves with an ultrasonic wave transmitting means (not shown) provided in Nos. 7 and 28 and then ejecting them.

Furthermore, the inventors of the present invention conducted an experiment in which the treated wastewater having a tetrachloroethylene concentration of 4.2 ppm was treated in the above-mentioned apparatus. As a result, the treatment with only the first evaporator 1 resulted in 0.39 ppm. It was possible to reduce to 0.14 ppm by treating both the first evaporator 1 and the second evaporator 2.

In the above-mentioned embodiment, the case where the two volatile evaporators are used to separate the volatile organic compounds in two stages, the present invention is not limited to three or more evaporations. Needless to say, it is possible to use a can to configure the separation of volatile organic compounds in multiple stages of three or more stages, which further improves the separation rate of volatile organic compounds from wastewater. You can do it.

[Brief description of drawings]

FIG. 1 is a flow sheet showing an embodiment of the present invention.

[Explanation of symbols]

1 first evaporation can 2 second evaporation can 3 suction compressor 4,5 steam duct 6 condenser 7 Wastewater supply pipeline

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshiaki Miho             6-7-5 Minejima, Nishiyodogawa-ku, Osaka             Ceremony Company Sakura F-term (reference) 4D034 AA26 CA12                 4D037 AA11 AB14 BA26                 4D076 AA01 AA12 AA22 BA02 BA08                       BC02 DA03 HA06 JA04

Claims (3)

[Claims] 1. An evaporator for boiling and evaporating a wastewater to be treated containing a volatile organic compound and a gas containing water vapor and a gas of the volatile organic compound in the evaporator are reduced to a pressure below atmospheric pressure in the evaporator. And a suction compression unit for compressing to a pressure higher than that in the evaporator, and a condenser for compressed gas from the suction compression unit,
Further, the waste water to be treated is configured to be supplied to the evaporator after passing through the condenser as cooling water for steam condensation in the condenser, for separation treatment of volatile organic compounds in the waste water. Device to do. 2. A first evaporator and a second evaporator for boiling and evaporating wastewater containing a volatile organic compound, and a gas containing water vapor and a volatile organic compound gas in both the evaporators in both the evaporators. Is suctioned so as to reduce the pressure to atmospheric pressure or less and then is compressed to a pressure higher than that in the evaporator, and a condenser for compressed gas from the suction compression means is provided. The treated wastewater is supplied as cooling water for steam condensation in the condenser to the first evaporator after passing through the condenser, and the treated wastewater discharged from the first evaporator is treated with the steam in the condenser. An apparatus for separating and treating volatile organic compounds in waste water, characterized in that the cooling water for condensation passes through the condenser and is then supplied to the second evaporator. 3. The waste water according to claim 1 or 2, wherein condensed water containing a volatile organic compound discharged from the condenser is introduced into a decomposition vessel equipped with an ultrasonic wave transmitter. A device that separates and processes volatile organic compounds.