JP4043199B2 - Method and apparatus for separating volatile organic compounds from wastewater - Google Patents

Description

【００１８】
すなわち，廃水を入れた密閉容器３０内を，実験２のように，単に大気以下に減圧するだけでは，前記廃水中のトリクロロエチレンを廃水から殆ど分離することができず，また，実験１のように，前記密閉容器３０内の廃水に対して超音波を照射すること，更には，前記実験１と実験２とを併用することでは，トリクロロエチレンの廃水からの分離率をさほど向上することができないのであった。
【００１９】
これに対し，前記密閉容器３０内における廃水を，実験４のように，その水面より低い水中の部分において沸騰するようにした場合には，トリクロロエチレンの廃水からの分離率を大幅に向上できたのであり，しかも，このように，廃水をその水面から液深さが深い部分より沸騰することに，超音波の照射を併用することにより，前記トリクロロエチレンの廃水からの分離率を更に向上できるのであった。
【００２０】
このように，廃水をその水面より低い水中の部分において沸騰することによってトリクロロエチレンの分離率を大幅に向上できることの理由は，以下によるものと考えられる。
【００２１】
すなわち，廃水に含まれているトリクロロエチレンは，廃水の沸騰によって発生する蒸気の気泡側に集まり，この蒸気の気泡が破裂するときに気相に移行（気化）して廃水から分離するのであるが，廃水の沸騰が，廃水の水面，又は水面の近傍においてのみで行われているときには，この沸騰にて発生する蒸気の気泡が廃水に対して接触する時間がきわめて短く，従って，この蒸気の気泡に集まるトリクロロエチレンが少ないので，トリクロロエチレンの分離率は低い。
【００２２】
これに対し，前記廃水の沸騰を，当該廃水の水面より低い水中の部分において行うようにした場合には，前記沸騰による蒸気の気泡は，廃水中のうち水面より低い水中の部分において発生し，この蒸気の気泡が水面に向かって上昇する。その上昇の途中において，この蒸気の気泡に，廃水中におけるトリクロロエチレンが多く集まり，徐々に気泡内に蒸発して気泡が大きくなる。そして，前記蒸気の気泡が，水面において破裂するとき，この蒸気の気泡に集まっているトリクロロエチレンが気相の移行（気化）して廃水から分離するものである。
【００２３】
そこで，本発明は，前記図１に示す実施の形態の装置において明らかにしたように，減圧に保持した蒸発缶１内に廃水を，その底部におけるノズル４から供給したのち，これよりも適宜高さＨだけ高い部位に設けた排出口５から排出することによって，前記蒸発缶１内に廃水Ａを所定の液深さＨだけ常時蓄えて，この廃水Ａを，前記蒸発缶１内における真空ポンプ１３による減圧度と廃水が蒸発缶１内に流入するときの温度とを適宜設定することにより，その水面Ａ′より低い水中の部分において沸騰するようにしたのであり，この廃水Ａの水面Ａ′より低い水中の部分における沸騰により，この廃水Ａ中の揮発性有機化合物を気化して廃水Ａから分離することを，高い分離率で行うことができるのである。
【００２４】
また，前記蒸発缶１内に所定の液深さＨに溜めた廃水Ａを，その水面Ａ′より低い水中の部分において沸騰することに加えて，この廃水Ａに対して，超音波発信手段１７にて超音波を照射することにより，沸騰で発生した蒸気の気泡を微細化することができ，この蒸気の気泡の微細化により，廃水Ａとの接触面積が増加し，これに多くの揮発性有機化合物を集めることができるから，前記揮発性有機化合物の廃水からの分離率を更に向上できるのである。
【００２５】
更にまた，前記蒸発缶１内に所定の液深さＨに溜めた廃水Ａを，その水面Ａ′より低い水中の部分において沸騰することに加えて，この廃水Ａにおける水面Ａ′より低い水中の部分に，前記蒸発缶１内おける水蒸気及び不凝縮性ガスを前記ブロワー等の圧縮機８で圧縮したのちその一部を吹き込むことにより，前記廃水Ａにおける液深さが深い部分での沸騰をより促進できるとともに，蒸気の気泡の微細化及び増加を図ることができるから，前記揮発性有機化合物の廃水からの分離率を更に向上できるのである。
【００２６】
このように，蒸発缶１内おける水蒸気及び不凝縮性ガスを前記ブロワー等の圧縮機８で圧縮したのちその一部を，蒸発缶１内における廃水Ａのうち水面Ａ′より低い水中の部分に吹き込むことに代えて，或いは，これに加えて，ボイラーから送られて来る加熱用蒸気を，廃水Ａのうち水面Ａ′より低い水中の部分に吹き込むか，蒸発缶１内における底部に電熱ヒーターを設けることにより，廃水の水面Ａ′より低い水中の部分における沸騰をより活発にすることによっても，分離率を向上できる。
【００２７】
その上，本実施の形態の場合，前記蒸発缶１から排出口５に繋がるポンプ２２にて汲み出した処理済廃水の一部を，管路２３より取り出し，これを，前記蒸発缶１内の上部に設けた散布ノズル２４から，当該散布ノズル２４に設けられている超音波発信手段（図示せず）に超音波を照射したのち散布するように構成することにより，前記処理済廃水中に残存している揮発性有機化合物を，超音波の照射と，散布による蒸発とで分離できるから，前記揮発性有機化合物の廃水からの分離率を更に向上できるのである。
【００２８】
次に，図２は，第２の実施の形態における蒸発缶１′を示す。
【００２９】
この第２の実施の形態は，その蒸発缶１′の内部に，ラシヒリング等の充填材を投入した充填層２５を設け，この充填層２５の下部又はこの充填層２５の下側の部分に，廃水供給管路２′からの廃水をノズル４′より供給し，この廃水を，前記充填層２５より上部又はこれより高い部位に設けた排出口５′から排出することにより，前記蒸発缶１内に，廃水Ａを所定の液深さＨだけ常時蓄えるように構成され，且つ，この蒸発缶１′に所定の液深さＨに溜められる廃水Ａを，前記図１に示す実施の形態の場合と同様に，前記蒸発缶１′内における減圧度と廃水が蒸発缶１′内に流入するときの温度とを適宜設定することにより，その水面Ａ′より低い水面下のうち前記充填層２５の上面より低い部分において沸騰する一方，蒸発缶１内における水蒸気及び不凝縮性ガスを，前記第１の実施の形態の場合と同様にダクト９′を介してブロワー等の圧縮機に吸引するように構成したものである。なお，その他の構成は，前記第１の実施の形態と同じである。
【００３０】
この構成において，廃水Ａの水面Ａ′より低い水面下のうち前記充填層２５の上面より低い部分での沸騰で発生したのち水面Ａ′に浮上する蒸気の気泡は，前記充填層２２を通過するときにおいて，気泡面積が増大し，且つ，急浮上することなく滞留することにより，当該蒸気の気泡が水面に浮上するまでの時間が長くなり，従って，廃水との接触時間が長くなるから，この蒸気の気泡により多くの揮発性有機化合物を集めることができる。
【００３１】
一方，前記蒸発缶１′内の廃水Ａにおける揮発性有機化合物の濃度は，液深さが深い水中の部分での沸騰により水面Ａ′において最も低くなるが，水面Ａ′における揮発性有機化合物濃度の低い廃水は，前記液深さが深い部分における蒸気の気泡が水面Ａ′に浮上することで発生する対流現象のために，水面より深い部分に混合されることになるから，前記排出口５′からは，揮発性有機化合物濃度が最も低い濃度の廃水を排出することができないことになる。
【００３２】
しかし，前記したように，充填層２５を設けた場合には，この充填層２５の存在によって，前記対流現象を抑制することができるから，前記排出口５′からは，廃水Ａのうちその水面Ａ′の部分における低濃度の廃水のみを排出することができる。
【００３３】
従って，この第２の実施の形態によると，充填層２５の存在によって，前記蒸気の気泡が水面Ａ′に浮上するまでの時間が長くなりこれに多くの揮発性有機化合物を集めることができること，及び対流現象の抑制にて水面Ａ′の部分における低濃度の廃水を排出できることとが相俟って，揮発性有機化合物の分離率を，前記第１の実施の形態の場合よりも向上できるのであり，もちろん，この第２の実施の形態に，前記第１の実施の形態と同様に，超音波の照射，及び圧縮した水蒸気及び不凝縮性ガスの吹き込み，並びに，処理済廃水の蒸発缶内への散布のうち少なくとも一つ以上を適用することができる。
【００３４】
なお，前記蒸発缶内１における水蒸気及び不凝縮性ガスは，給水加熱器７に入り，前記蒸発缶１に供給される廃水を加熱（給水加熱）したのち気液分離室１１に入り，凝縮水は管路１２を介して取り出される一方，不凝縮性ガスは管路１２′を介して液封式の真空ポンプ１３に吸引される。或いは，前記給水加熱器７における凝縮水及び不凝縮性ガス，又は不凝縮性ガスのみは，二点鎖線で管路１２″を介して液封式の真空ポンプ１３に吸引される。
【００３５】
この液封式真空ポンプ１３に吸引された不凝縮性ガスは，当該液封式真空ポンプ１３に対する液封用液体に混合されることにより，前記液封式真空ポンプ１３から排出される液封用液体には，前記不凝縮性ガス中における気体の揮発性有機化合物が高い濃度で溶解する。
【００３６】
この液封用液体を，気液分離容器１７内に導き，ここで，前記液封用液体に溶解していない空気等の気体を気体放出管路１６から大気中に放出するように分離したのち，分離容器１９内に導き，この分離容器１９内で液封用液体に対して，超音波発信手段１８にて超音波を照射することにより，前記液封用液体に溶解している揮発性有機化合物を，水，炭酸ガス及び塩酸等の最終分解化合物に分解する。
【００３７】
このようにして，前記分離容器１９内において揮発性有機化合物の分解した後の液封用液体は，これに前記超音波を照射する場合におけるエネルギーにて発生する熱，及び，前記液封式真空ポンプ１３の箇所でエネルギーにて発生する熱によってその温度が上昇しているから，これを，前記蒸発缶１への廃水供給管路２中に設けられている副給水加熱器２１に導いて，前記蒸発缶１に供給される廃水を給水加熱するというように熱回収したのち，前記液封式真空ポンプ１３に戻して，当該液封式真空ポンプ１３に対する液封用液体に繰り返して使用するのである。
【００３８】
なお，前記大気への気体放出管路１６の途中には，活性炭等によるガス浄化器２６，又は，ガスを触媒の存在のもとで燃焼するという二次燃焼式のガス浄化器を設けて，揮発性有機化合物を大気中に放出しないように構成している。
【００３９】
また，前記液封式真空ポンプ１３に対する液封用液体としては，水を使用することができるが，この水に変えて，前記揮発性有機化合物を溶解することができ，且つ，１００℃よりも高い沸点を有する可溶性の液体，例えば，エチレングリコールを使用することにより，この液封用液体が蒸発等による消費される量を少なくできるとともに，この液封用液体を，高い濃度の塩素有機化合物を含む水溶液として取り出すことができる。
【００４０】
一方，液封用液体として水を使用した場合には，この液封用液体として循環する水の一部を，管路２６より取り出し，この水を超音波発信手段（図示せず）を備えた分解器２７にて超音波を照射して，これに溶解している揮発性有機化合物を分解したのち，管路２８より系外に排出するか，或いは，前記管路２６より取り出した水を，二点鎖線で示す管路２９を介して前記蒸発缶１に供給される廃水に混合するように構成する。
【００４１】
また，前記の実施の形態は，蒸発缶１，１′において廃水から気化して分離した揮発性有機化合物を，液封式真空ポンプ１３に対する液封用液体に溶解したのち，超音波の照射にて分解する場合であったが，廃水から気化して分離した揮発性有機化合物は，前記以外の分解手段，例えば，紫外線の照射にて分解するようにしても良い。
【００４２】
【発明の作用・効果】
このように，本発明によると，廃水に含まれている揮発性有機化合物を廃水から分離することを，従来のバブリングでなく，水中で沸騰するという極く簡単な方法が高い分離率で分離することができるから，装置の大幅に小型化できるとともに，騒音及び消費電力の低減を達成できる効果を有する。
【００４３】
また，本発明は，揮発性有機化合物の分離が，廃水を水中で沸騰することであるために，揮発性有機化合物を高い濃度のガスとして廃水から分離できるから，この分離した揮発性有機化合物を分解することが，前記従来の場合よりも簡単にできるという利点がある。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態を示すフローシートである。
【図２】本発明の第２の実施の形態を示すフローシートである。
【図３】実験装置を示す縦断正面図である。
【符号の説明】
１，１′ 蒸発缶
２，２′ 廃水供給管路
４，４′ ノズル
５，５′ 処理済廃水の排出口
６ 超音波発信手段
７ 給水加熱器
８ 圧縮機
２４ 散布ノズル
２５ 充填層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for separating a volatile organic compound from wastewater when the wastewater such as groundwater or industrial wastewater contains a volatile organic compound such as trichlorethylene or tetrachloroethylene.
[0002]
[Prior art]
Conventionally, in the treatment of wastewater such as groundwater or industrial wastewater, volatile organic compounds such as trichlorethylene or tetrachloroethylene contained therein are separated from the wastewater by using a gas such as air. A method is adopted in which bubbling (aeration) is performed and volatile organic compounds in the wastewater are volatilized in the gas blown into the wastewater to separate it from the wastewater.
[0003]
[Problems to be solved by the invention]
However, in this bubbling method, in order to increase the separation rate from volatile organic compounds, the amount of bubbling gas blown into the wastewater must be increased, and in order to handle a large amount of gas, There is a problem that not only an increase in the size of the entire apparatus cannot be avoided, but also an increase in noise and power consumption due to an increase in the size of a blower that pumps air.
[0004]
In the conventional bubbling method, the volatile organic compound separated from the wastewater is discharged from the wastewater by being diluted with a large amount of gas blown in order to separate the volatile organic compound by the wastewater. Since the concentration of volatile organic compounds contained in the gas is extremely low, it is very troublesome to decompose volatile organic compounds with very low concentrations, which requires large equipment and a large running cost. There was also a problem.
[0005]
The present invention provides a method capable of reliably separating volatile organic compounds contained in wastewater from wastewater with high separation efficiency without incurring an increase in the size of the apparatus. It is to be an issue.
[0006]
[Means for Solving the Problems]
The method of the present invention to achieve this technical problem, as described in claim 1,
“Waste water containing volatile organic compounds is introduced into the evaporator containing the packed bed from the lower or lower part of the packed bed and discharged from the upper or higher part of the packed bed. The accumulated waste water is boiled at a portion below the upper surface of the packed bed below the water surface by setting the degree of decompression in the evaporator and the temperature of the waste water .
It is characterized by that.
[0007]
Further, the device of the present invention, as described in claim 4 ,
“ Equipped with an evaporator with a packed bed inside, and into this evaporator, waste water containing volatile organic compounds is introduced from the lower part of the packed bed or lower part thereof, and the upper part of the packed bed or higher. It is constructed so that it can be appropriately stored at a liquid depth by discharging from the part, and further, a vacuum pump is provided for reducing the pressure so that the waste water stored in the evaporator can boil in the part of the water below the water surface. Yes . "
It is characterized by that.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0009]
FIG. 1 shows a first embodiment.
[0010]
In this figure, reference numeral 1 denotes a decompression type evaporator, and reference numeral 2 denotes waste water that supplies waste water containing a volatile organic compound such as trichlorethylene or tetrachloroethylene sent from a supply pump 3 to the evaporator 1. A supply line is shown, and a nozzle 4 for ejecting waste water sent from the waste water supply line 2 is provided at the bottom of the evaporator 1, and the evaporator 1 is provided with a nozzle 4. A discharge port 5 for the treated wastewater is provided at a portion that is appropriately high by a height H, whereby the wastewater A is always stored in the evaporator 1 by a predetermined liquid depth H, and The evaporator 1 is provided with ultrasonic transmission means 6 for irradiating the waste water A stored at the predetermined liquid depth H with ultrasonic waves.
[0011]
An indirect heat exchange type feed water heater 7 is provided in the middle of the waste water supply pipe 2, and water vapor and noncondensable gas generated by boiling / evaporation in the evaporator 1 are provided in the feed water heater 7. Is sucked into a compressor 8 such as a blower that is rotationally driven by an electric motor through a duct 9 and then compressed through a duct 10 to be introduced into the evaporator 1 through the waste water supply line 2. Heat the wastewater to be sent (heated water heating). Condensed water and non-condensable gas in the feed water heater 7 are introduced into the gas-liquid separation chamber 11, of which condensed water is taken out via the conduit 12, while non-condensable gas is introduced via the conduit 12 ′. Then, the inside of the evaporator 1 is maintained at a reduced pressure below atmospheric pressure by suctioning with a liquid-sealed vacuum pump 13, or condensed water and non-condensable gas in the feed water heater 7, or non-condensing Only the volatile gas is sucked by the liquid-sealed vacuum pump 13 through the pipe line 12 ″ indicated by a two-dot chain line without passing through the gas-liquid separation chamber 11. Maintain a reduced pressure below atmospheric pressure.
[0012]
In this case, the waste water A stored in the evaporator 1 at a predetermined liquid depth H by appropriately setting the degree of decompression in the evaporator 1 and the temperature at which the waste water flows into the evaporator 1. However, it is configured such that it boils at a portion of the water below the water surface A ′, preferably at a portion of the nozzle 4 at the deepest position.
[0013]
Further, a part of the vapor and non-condensable gas compressed by the compressor 8 is taken out from the duct 14 and blown into the evaporator 1 from the nozzle 15 at the bottom.
[0014]
As the liquid sealing liquid in the liquid ring vacuum pump 13, a soluble liquid in which a volatile organic compound is dissolved such as trichloroethylene or tetrachloroethylene contained in the waste water, such as water or ethylene glycol, is used. The gas-liquid discharged from the liquid-sealed vacuum pump 13 is introduced into a gas-liquid separation container 17 having a gas discharge pipe 16 to the atmosphere, and the gas is introduced into the atmosphere through the gas discharge pipe 16. On the other hand, a liquid, that is, a liquid sealing liquid is introduced into a decomposition container 19 provided with an ultrasonic transmission means 18, and ultrasonic waves from the ultrasonic transmission means 18 are irradiated into the decomposition container 19. Next, the liquid sealing liquid in the decomposition vessel 19 is pumped out by the circulation pump 20, and then the indirect heat exchange type sub-feed water heater 21 provided in the waste water supply pipe 2 is supplied. Feeding to be configured to repeat the circulation of returning to the suction side of the liquid ring vacuum pump 13 from the sub-feed water heater 21. That is, the liquid sealing liquid for the liquid ring vacuum pump 13 is circulated from the liquid ring vacuum pump 13 back to the liquid ring vacuum pump 13 via the gas-liquid separation container 17, the decomposition container 19, and the auxiliary feed water heater 21. Configure in the pipeline.
[0015]
In this configuration, the waste water containing a volatile organic compound such as trichlorethylene or tetrachloroethylene is supplied to the waste water supply pipe 2 by two feed water heaters 7 and 21, and then the evaporator 1 held at a reduced pressure. enters the inside, by boiling here, at the same time as part of the waste water becomes steam, the volatile organic compounds contained in the waste water is boiled at the same time as evaporation of water become gas separation from the waste water Therefore, in the evaporator 1, water vapor and non-condensable gas including the gas of the volatile organic compound and air are generated, while the volatile organic compound is separated in the evaporator 1. The treated waste water is pumped out from the discharge port 5 by the pump 22.
[0016]
By the way, as shown in FIG. 3, the present inventors put waste water containing trichlorethylene as a volatile organic compound into a sealed container 30 having an ultrasonic transmission means 31 on the bottom surface by a predetermined liquid depth H. In this state,
(i) When the waste water in the sealed container 30 is irradiated with 20 W ultrasonic waves at a frequency of 2.3 MHz by the ultrasonic transmission means 31 (Experiment 1).
(ii). When the temperature of waste water in the sealed container 30 is set to 30 ° C., and the pressure in the sealed container 30 is reduced to 35 torr by suction of the vacuum pump 32 (Experiment 2).
(iii). The temperature of the waste water in the sealed container 30 is set to 30 ° C., the pressure in the sealed container 30 is set to 35 torr by suction of the vacuum pump 32, and the waste water is supplied to the waste water by the ultrasonic transmission means 31 at a frequency of 2.3 MHz. When sound waves are applied (Experiment 3).
(iv). When the temperature of the waste water in the sealed container 30 is 43.5 ° C. and the pressure in the sealed container 30 is reduced to 41 torr by suction of the vacuum pump 32, the waste water boils in a portion of the water below the water surface. (Experiment 4).
(v). While the temperature of the waste water in the sealed container 30 is set to 48 ° C. and the pressure in the sealed container 30 is reduced to 50 torr by suction of the vacuum pump 32, the waste water is boiled and evaporated in a portion of the water below the water surface. When the waste water is irradiated with 20 W ultrasonic waves at a frequency of 2.3 MHz by the ultrasonic transmission means 31 (Experiment 5).
Table 1 shows the results of experiments for measuring the trichlorethylene concentration (ppm) in the wastewater at each treatment time.
[0017]
[Table 1]

[0018]
That is, the trichlorethylene in the waste water cannot be separated from the waste water by simply depressurizing the inside of the sealed container 30 containing the waste water to below the atmosphere as in Experiment 2, and as in Experiment 1. However, by irradiating the waste water in the sealed container 30 with ultrasonic waves, and further using the experiment 1 and the experiment 2 together, the separation rate of trichlorethylene from the waste water cannot be improved so much. It was.
[0019]
On the other hand, when the waste water in the sealed container 30 was boiled in the portion of the water below the water surface as in Experiment 4, the separation rate of trichlorethylene from the waste water could be greatly improved. In addition, the separation rate of the trichlorethylene from the wastewater can be further improved by using the ultrasonic irradiation in combination with boiling the wastewater from the portion where the liquid depth is deep from the surface. .
[0020]
As described above, the reason why the separation rate of trichlorethylene can be greatly improved by boiling the wastewater in a portion of the water below the surface of water is considered to be as follows.
[0021]
In other words, trichlorethylene contained in the wastewater collects on the bubble side of the steam generated by the boiling of the wastewater, and when the vapor bubble bursts, it moves to the gas phase (vaporizes) and separates from the wastewater When the boiling of the waste water is performed only at or near the surface of the waste water, the time when the bubble of steam generated by this boiling comes into contact with the waste water is extremely short. Since the amount of trichlorethylene collected is small, the separation rate of trichlorethylene is low.
[0022]
On the other hand, when boiling of the wastewater is performed in a portion of the water below the surface of the wastewater, steam bubbles due to the boiling are generated in the portion of the wastewater below the surface of the water, The vapor bubbles rise toward the water surface. In the middle of the rise, a large amount of trichlorethylene in the wastewater collects in the vapor bubbles, and gradually evaporates into the bubbles to enlarge the bubbles. When the vapor bubbles burst on the water surface, the trichlorethylene collected in the vapor bubbles is transferred (vaporized) in the gas phase and separated from the waste water.
[0023]
Therefore, the present invention, as clarified in the apparatus of the embodiment shown in FIG. 1, supplies the waste water into the evaporator 1 kept at a reduced pressure from the nozzle 4 at the bottom thereof, and then appropriately raises the waste water. The waste water A is always stored in the evaporator 1 by a predetermined liquid depth H by being discharged from the discharge port 5 provided at a part higher than the height H, and this waste water A is stored in the evaporator 1 by a vacuum pump. By appropriately setting the degree of decompression by 13 and the temperature at which the wastewater flows into the evaporator 1, the water is boiled in a portion of the water below the water surface A ′. By boiling in the lower part of the water, the volatile organic compounds in the waste water A can be vaporized and separated from the waste water A at a high separation rate.
[0024]
Further, in addition to boiling the waste water A stored in the evaporator 1 at a predetermined liquid depth H in a portion of the water below the water surface A ′, the ultrasonic transmission means 17 is applied to the waste water A. By irradiating ultrasonic waves at, the bubbles of steam generated by boiling can be refined, and by the refinement of the bubbles of steam, the contact area with the wastewater A increases, and this has a lot of volatility. Since organic compounds can be collected, the separation rate of the volatile organic compounds from wastewater can be further improved.
[0025]
Furthermore, in addition to boiling the waste water A stored in the evaporator 1 at a predetermined liquid depth H in a portion of the water lower than the water surface A ′, The steam and non-condensable gas in the evaporator 1 are compressed into the portion by the compressor 8 such as the blower, and then a part thereof is blown to further boil the portion in the waste water A where the liquid depth is deep. In addition to being able to promote, the vapor bubbles can be refined and increased, so that the separation rate of the volatile organic compound from the wastewater can be further improved.
[0026]
As described above, after the water vapor and the non-condensable gas in the evaporator 1 are compressed by the compressor 8 such as the blower, a part thereof is converted into a portion of the waste water A in the evaporator 1 that is lower than the water surface A ′. Instead of or in addition to blowing, the heating steam sent from the boiler is blown into a portion of the waste water A that is lower than the water surface A ′, or an electric heater is installed at the bottom of the evaporator 1. By providing this, the separation rate can also be improved by making the boiling in the portion of the water below the water surface A ′ of the waste water more active.
[0027]
In addition, in the case of the present embodiment, a part of the treated waste water pumped out by the pump 22 connected from the evaporator 1 to the discharge port 5 is taken out from the pipe 23 and is taken up in the upper part in the evaporator 1. The spray nozzle 24 provided in the spray nozzle 24 is configured to irradiate the ultrasonic wave transmission means (not shown) provided in the spray nozzle 24 after the ultrasonic wave is applied, so that it remains in the treated wastewater. Since the volatile organic compound can be separated by ultrasonic irradiation and evaporation by spraying, the separation rate of the volatile organic compound from the wastewater can be further improved.
[0028]
Next, FIG. 2 shows an evaporator 1 ′ in the second embodiment.
[0029]
In the second embodiment, a filling layer 25 filled with a filler such as Raschig ring is provided in the evaporator 1 ', and a lower part of the filling layer 25 or a lower part of the filling layer 25 is provided. Waste water from the waste water supply pipe 2 'is supplied from the nozzle 4', and this waste water is discharged from a discharge port 5 'provided above or higher than the packed bed 25, thereby allowing the inside of the evaporator 1 to be discharged. In the embodiment shown in FIG. 1 , the waste water A is configured to always store the waste water A by a predetermined liquid depth H and is stored in the evaporator 1 'at the predetermined liquid depth H. Similarly, the degree of pressure reduction in the evaporator 1 'and the temperature at which the waste water flows into the evaporator 1' are appropriately set, so that the packed bed 25 below the water surface A 'is below the water surface A'. while boiling in lower than the upper surface portion, put into the evaporator 1 Steam and noncondensable gas, which is constituted so as to suction into the compressor such as a blower through the first embodiment in a manner similar to duct 9 '. Other configurations are the same as those in the first embodiment.
[0030]
In this configuration, the bubbles of steam that are generated by boiling in the portion below the water surface A ′ of the waste water A and below the upper surface of the packed bed 25 and then float on the water surface A ′ pass through the packed bed 22. In some cases, the bubble area increases and stays without rising rapidly, so that the time until the bubble of the vapor rises to the surface of the water becomes longer, and thus the contact time with the wastewater becomes longer. More volatile organic compounds can be collected by vapor bubbles.
[0031]
On the other hand, the concentration of the volatile organic compound in the waste water A in the evaporator 1 'is lowest on the water surface A' due to boiling in the portion of the water where the liquid depth is deep, but the concentration of the volatile organic compound on the water surface A '. The waste water having a low liquid depth is mixed in a portion deeper than the water surface due to the convection phenomenon that occurs when the bubbles of the vapor in the portion where the liquid depth is deep rises to the water surface A ′. From ′, wastewater with the lowest concentration of volatile organic compounds cannot be discharged.
[0032]
However, as described above, when the packed bed 25 is provided, the convection phenomenon can be suppressed by the presence of the packed bed 25, and therefore, the water surface of the waste water A is discharged from the discharge port 5 ′. Only low-concentration wastewater in the portion A ′ can be discharged.
[0033]
Therefore, according to the second embodiment, due to the presence of the packed bed 25, it takes a long time for the bubbles of the vapor to rise to the water surface A ', so that a large amount of volatile organic compounds can be collected. Since the low concentration waste water in the water surface A ′ can be discharged by suppressing the convection phenomenon, the separation rate of the volatile organic compound can be improved as compared with the case of the first embodiment. Yes, of course, in the second embodiment, similarly to the first embodiment, the irradiation of ultrasonic waves, the blowing of compressed water vapor and non-condensable gas, and the inside of the evaporator of the treated wastewater At least one of the sprays can be applied.
[0034]
The water vapor and the non-condensable gas in the evaporator 1 enter the feed water heater 7 and heat the waste water supplied to the evaporator 1 (feed water heating), then enter the gas-liquid separation chamber 11 and the condensed water. Is taken out via the conduit 12, while the noncondensable gas is sucked into the liquid ring vacuum pump 13 via the conduit 12 '. Alternatively, only the condensed water and the non-condensable gas or the non-condensable gas in the feed water heater 7 are sucked into the liquid-sealed vacuum pump 13 through the pipe line 12 ″ by a two-dot chain line.
[0035]
The non-condensable gas sucked into the liquid ring vacuum pump 13 is mixed with the liquid ring liquid for the liquid ring vacuum pump 13 to be discharged from the liquid ring vacuum pump 13. In the liquid, the gaseous volatile organic compound in the non-condensable gas dissolves at a high concentration.
[0036]
After this liquid sealing liquid is introduced into the gas-liquid separation container 17, the gas such as air not dissolved in the liquid sealing liquid is separated from the gas discharge pipe 16 so as to be released into the atmosphere. The volatile organic dissolved in the liquid sealing liquid by being guided into the separation container 19 and irradiating the liquid sealing liquid in the separation container 19 with ultrasonic waves by the ultrasonic transmission means 18. the compound, water, that construed minute final degradation compounds such as carbon dioxide and hydrochloric acid.
[0037]
In this manner, the liquid sealing liquid after the volatile organic compound is decomposed in the separation container 19 is heat generated by energy when the ultrasonic wave is irradiated to the liquid sealing liquid, and the liquid sealing vacuum. Since the temperature is raised by heat generated by energy at the location of the pump 13, this is led to a sub-feed water heater 21 provided in the waste water supply pipe 2 to the evaporator 1, Since the waste water supplied to the evaporator 1 is heat-recovered such as by heating the feed water, it is returned to the liquid ring vacuum pump 13 and repeatedly used as the liquid ring liquid for the liquid ring vacuum pump 13. is there.
[0038]
In the middle of the gas discharge pipe 16 to the atmosphere, a gas purifier 26 made of activated carbon or the like, or a secondary combustion type gas purifier that burns gas in the presence of a catalyst, It is configured not to release volatile organic compounds into the atmosphere.
[0039]
Moreover, water can be used as the liquid sealing liquid for the liquid ring vacuum pump 13, but the volatile organic compound can be dissolved in place of the water, and the temperature is higher than 100 ° C. By using a soluble liquid having a high boiling point, such as ethylene glycol, the amount of the liquid sealing liquid consumed by evaporation or the like can be reduced, and the liquid sealing liquid can be added with a high concentration of chlorinated organic compounds. It can be taken out as an aqueous solution containing it.
[0040]
On the other hand, when water is used as the liquid sealing liquid, a part of the water circulating as the liquid sealing liquid is taken out from the pipe 26, and this water is provided with ultrasonic transmission means (not shown). After decomposing the volatile organic compound dissolved in the decomposer 27 by irradiating ultrasonic waves, it is discharged out of the system from the pipe 28 or the water taken out from the pipe 26 is It mixes with the waste water supplied to the said evaporator 1 through the pipe line 29 shown with a dashed-two dotted line.
[0041]
In the above embodiment, the volatile organic compound vaporized and separated from the waste water in the evaporators 1, 1 ′ is dissolved in a liquid sealing liquid for the liquid ring vacuum pump 13, and then irradiated with ultrasonic waves. However, the volatile organic compound vaporized and separated from the wastewater may be decomposed by other decomposition means, for example, irradiation with ultraviolet rays.
[0042]
[Operation and effect of the invention]
Thus, according to the present invention, separation of volatile organic compounds contained in wastewater from wastewater is achieved by a very simple method of boiling in water instead of conventional bubbling at a high separation rate. Therefore, it is possible to greatly reduce the size of the apparatus, and to achieve reductions in noise and power consumption.
[0043]
In addition, since the separation of the volatile organic compound in the present invention is that the wastewater is boiled in water , the volatile organic compound can be separated from the wastewater as a high-concentration gas. There is an advantage that the disassembly can be made easier than in the conventional case.
[Brief description of the drawings]
FIG. 1 is a flow sheet showing a first embodiment of the present invention.
FIG. 2 is a flow sheet showing a second embodiment of the present invention.
FIG. 3 is a longitudinal front view showing an experimental apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,1 'Evaporator 2,2' Wastewater supply line 4,4 'Nozzle 5,5' Outlet of treated wastewater 6 Ultrasonic transmission means 7 Feed water heater 8 Compressor 24 Spray nozzle 25 Packing bed

Claims (7)

The waste water containing the volatile organic compound is introduced into the evaporator containing the packed bed from below or below the packed bed and discharged from above or above the packed bed. The accumulated waste water is boiled in a portion below the upper surface of the packed bed below the water surface by setting the degree of decompression in the evaporator and the temperature of the waste water. A method for separating volatile organic compounds from wastewater. In the description of claim 1, a part of water vapor and non-condensable gas in the evaporator can be compressed and blown into a portion below the upper surface of the packed bed of the waste water in the evaporator. Alternatively, a volatile organic compound in the wastewater, characterized by blowing steam for heating or heating the wastewater below the surface of the wastewater below the upper surface of the packed bed with a heating means such as an electric heater. A method for separating compounds. In the claim 1 or 2, a part of the treated waste water discharged from the surface of the waste water in the evaporator can be sprayed on the upper part in the evaporator by irradiating ultrasonic waves. To separate volatile organic compounds in wastewater. An evaporator having a packed bed inside is provided, and waste water containing a volatile organic compound is introduced into the evaporator from the lower part of the packed bed or a lower part thereof, and the upper part or higher part of the packed bed. And a vacuum pump for reducing the pressure so that the waste water stored in the evaporator can be boiled in a portion of the water below the water surface. An apparatus for separating volatile organic compounds from wastewater . 5. The means according to claim 4, wherein means for compressing and blowing a part of water vapor and non-condensable gas in the evaporator into the lower part of the surface of the waste water in the evaporator is lower than the upper surface of the packed bed. Or an apparatus for separating a volatile organic compound in wastewater, characterized by comprising means for blowing steam for heating or heating means for heating wastewater in a portion of the water below the water surface . 6. The method according to claim 4, further comprising means for irradiating a part of the treated waste water discharged from the water surface of the waste water in the evaporator to the upper part in the evaporator by irradiating ultrasonic waves. An apparatus for separating volatile organic compounds from wastewater. In any one of the said Claims 4-6, The indirect heat exchange type feed water heater provided in the waste-water supply conduit | pipe into the said evaporator and the compressor of the water vapor | steam generated in the said evaporator are provided. An apparatus for separating volatile organic compounds in wastewater , characterized in that the water vapor compressed by the compressor is supplied to the feed water heater and the wastewater introduced into the evaporator is heated. .

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