JP7308508B2 - Cleaning liquid recovery device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus for recovering cleaning liquid that adheres to the surface of a work when the work is cleaned and evaporates from the surface when the work is dried.

Conventionally, vacuum drying is performed in order to remove the cleaning liquid adhering to the work after steam cleaning the work. In the steam cleaning/vacuum drying, first, the workpiece is placed in a closed tank, and after the inside of the closed tank is evacuated by a vacuum pump, steam generated by heating the cleaning liquid is introduced into the closed tank. As a result, part of the steam exchanges heat with the work and liquefies on the surface of the work, thereby cleaning the work. After that, by rapidly reducing the pressure in the closed tank with a vacuum pump, the cleaning liquid adhering to the surface of the workpiece is bumped and vaporized, and is discharged from the closed tank together with the vapor that has not been liquefied. This removes the cleaning liquid from the surface of the work and dries the surface of the work. The workpiece may be cleaned by immersing it in a cleaning liquid before performing steam cleaning.

Cleaning fluids usually contain volatile organic compounds (VOCs) and other components that are subject to emissions regulations. must be kept below. In addition, if the vapor of the cleaning liquid is discharged into the environment, the cleaning liquid is lost, and it is necessary to replenish the cleaning liquid, which increases the running cost of cleaning. Therefore, conventionally, a cleaning liquid recovery device has been used to recover the cleaning liquid discharged as steam from the closed tank (for example, Patent Document 1). In this type of cleaning liquid recovery apparatus, a condenser (cooler) is provided on the intake side (between the closed tank and the vacuum pump) and/or the exhaust side of the vacuum pump. Vapor of the cleaning liquid is liquefied by this condenser, recovered and reused.

Japanese Patent Application Laid-Open No. 09-042832

It is difficult for the condenser to liquefy all of the vapor of the cleaning liquid, and a portion of the vapor is discharged from the cleaning liquid recovery device into the environment. In order to further reduce the adverse effects on the environment and further reduce the running cost of cleaning, it is required to reduce the amount of vapor of the cleaning liquid discharged without being collected by the cleaning liquid recovery device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cleaning liquid recovery apparatus capable of reducing the amount of cleaning liquid vapor discharged without being recovered.

In order to solve the above problems, the cleaning liquid recovery device according to the present invention includes:
a) a vacuum pump whose intake side is connected to a closed vessel containing the workpiece;
b) a compressor for compressing gas, the suction side of which is connected to the exhaust side of the vacuum pump;
c) a condenser configured to cool and condense the gas, the intake side of which is connected to the exhaust side of the compressor;

The cleaning liquid recovery apparatus according to the present invention includes a compressor having an intake side connected to the exhaust side of the vacuum pump and an exhaust side connected to the intake side of the condenser, in addition to the vacuum pump and condenser of the conventional cleaning liquid recovery apparatus. . With such a configuration, in the cleaning liquid recovery apparatus according to the present invention, the cleaning liquid vapor is discharged from the closed tank by the vacuum pump, compressed by the compressor, and then condensed by the condenser. Here, by compressing the vapor of the cleaning liquid with a compressor, the amount of the components of the cleaning liquid per unit volume is increased. Therefore, when the compressed cleaning liquid vapor is cooled in the condenser, the amount of cleaning liquid components exceeding the saturated vapor amount increases, and the amount of cleaning liquid that liquefies increases, compared to the case of cooling to the same temperature without compression. . Therefore, according to the cleaning liquid recovery apparatus according to the present invention, the amount of cleaning liquid vapor discharged without being recovered is reduced as compared with the conventional cleaning liquid recovery apparatus without a compressor.

Preferably, the cleaning liquid recovery apparatus according to the present invention further comprises a buffer tank between the vacuum pump and the compressor. As a result, the vapor of the cleaning liquid can be supplied to the compressor at a nearly constant pressure, and the operation of the compressor can be stabilized.

The cleaning liquid recovery apparatus according to the present invention may further include a second condenser (hereinafter referred to as "second condenser") between the closed tank and the vacuum pump. As a result, a certain amount of steam is removed by the second condenser, and the remaining steam is supplied to the condenser via the vacuum pump and the compressor, thereby increasing the efficiency of condensation in the condenser. It is possible to prevent vapor from liquefying in the vacuum pump.

In the case of having the second condenser, a bypass flow path provided between the closed tank and the vacuum pump and connecting the closed tank and the vacuum pump without passing through the second condenser; A switching valve for switching a channel through which gas passes between the second condenser and the bypass channel may be provided. According to this configuration, when the vapor of the cleaning liquid starts to be discharged from the closed tank, the flow path is switched by the switching valve so that the vapor flows through the second condenser, thereby increasing the efficiency of condensation in the condenser. It is possible to prevent vapor from liquefying in the vacuum pump. On the other hand, after a certain amount of time has passed since the start of steam discharge from the closed tank, the amount of steam in the closed tank decreases, so the need to use the second condenser decreases, and the second condenser exhausts. Since this causes resistance, by switching the flow path through which the gas passes to the bypass flow path with the switching valve, the efficiency of evacuation can be made higher than in the case of passing through the second condenser.

The cleaning liquid recovery apparatus according to the present invention can reduce the amount of cleaning liquid vapor that is discharged without being recovered.

1 is a schematic configuration diagram showing an embodiment of a cleaning liquid recovery device according to the present invention; FIG.

One embodiment of a cleaning liquid recovery device according to the present invention will be described with reference to FIG.

(1) Configuration of cleaning liquid recovery apparatus of the present embodiment The cleaning liquid recovery apparatus 10 of the present embodiment is a device connected to a closed tank 20, and includes a vacuum pump 11, a buffer tank 12, a compressor 13, a condenser 14, It has a second condenser 15 , a bypass flow path 16 , a switching valve 17 and a cleaning liquid recovery tank 18 .

The closed tank 20 is used for vapor cleaning and vacuum drying, and accommodates the work in a sealed state inside, and is supplied with steam of the cleaning liquid from a steam supply source (not shown) (vapor cleaning/vacuum drying tank, vacuum tank). The sealed tank 20 can be evacuated (reduced pressure) by a vacuum pump 11 . A lid 21 is provided on the upper surface of the closed tank 20 . The lid 21 is opened when the work is carried into the closed tank 20 and when the work is unloaded from the closed tank 20, and the closed tank 20 is closed during steam cleaning and vacuum drying. can be sealed inside.

The intake side of the vacuum pump 11 is connected to the sealed tank 20 via the gas flow path 191 passing through the second condenser 15 and the bypass flow path 16 . Also, the exhaust side of the vacuum pump 11 is connected to the intake side of the compressor 13 via the aftercooler 111 and the buffer tank 12 by the gas flow path 192 . Here, the aftercooler 111 is a cooler attached to the vacuum pump 11 that cools the gas discharged from the vacuum pump 11 . The aftercooler 111 is provided with a drain port for recovering the liquid obtained by liquefying the cooled gas. One end of the bypass flow path 16 is connected to the gas flow path 191 on the closed tank 20 side of the second condenser 15 , and the other end of the bypass flow path 16 is connected to the gas flow path 11 on the vacuum pump 11 side of the second condenser 15 . 191 is connected. The switching valve 17 is an on-off valve provided between two connection points with the bypass flow path 16 in the gas flow path 191 and in the bypass flow path 16, respectively. The gas (vapor of cleaning liquid) flows to the second condenser 15 side when the former is opened and the latter is closed, and flows to the bypass channel 16 side when the former is closed and the latter is opened.

The buffer tank 12 is a tank provided in the gas flow path 192 connecting the vacuum pump 11 and the compressor 13 as described above. The buffer tank 12 temporarily stores the gas sucked by the vacuum pump 11 and exhausted from the exhaust side of the vacuum pump 11 . The buffer tank 12 is provided to stabilize the operation of the compressor 13 by supplying the gas (vapor of cleaning liquid) exhausted from the vacuum pump 11 to the compressor 13 at a nearly constant pressure.

The compressor 13 has an intake side connected to the exhaust side of the vacuum pump 11 via the gas flow path 192 as described above, and an exhaust side connected to the intake side of the condenser 14 via the gas flow path 193 . The compressor 13 compresses the gas discharged from the vacuum pump 11 to a predetermined pressure. It is desirable that the pressure after compression is high in order to more reliably liquefy the vapor of the cleaning liquid in the condenser 14, but the pressure may be appropriately determined in consideration of the apparatus cost. In this embodiment, the pressure after compression is 0.6 MPa.

The condenser 14 has its intake side connected to the exhaust side of the compressor 13 by the gas passage 193 as described above, and its exhaust side is open to the atmosphere. The condenser 14 cools the gas supplied from the compressor 13 to a predetermined temperature, thereby liquefying the gas, that is, the vapor of the cleaning liquid. Part of the vapor of the cleaning liquid is liquefied in the aftercooler 111 described above, but most of the vapor of the cleaning liquid passes through the aftercooler 111 and reaches the condenser 14 because the vacuum pump 11 does not have the ability to compress the gas. liquefy. Although the predetermined temperature should be low in order to more reliably liquefy the vapor of the cleaning liquid, it may be determined as appropriate in consideration of the cost of the apparatus. In this embodiment, the predetermined temperature is 10°C.

The second condenser 15, when the flow path is set by the switching valve 17 so that the gas from the closed tank 20 passes through, the gas at a predetermined temperature (although it is irrelevant to the predetermined temperature in the condenser 14 , may be the same). As with the condenser 14, the detailed configuration of the second condenser 15 is not particularly limited.

Vacuum pump 11, buffer tank 12, compressor 13, condenser 14, and second condenser 15 are each connected to a liquid feed pipe 195 for feeding liquid liquefied in each component to cleaning liquid recovery tank 18 and recovering it. It is A check valve is provided in the liquid feed pipe 195 to prevent backflow of the liquid. The cleaning liquid recovery tank 18 stores the cleaning liquid which is the liquid sent from each of the components described above, which is liquefied from the steam discharged from the closed tank 20 . The cleaning liquid stored in the cleaning liquid recovery tank 18 can be reused for cleaning the workpiece.

In addition, the cleaning liquid recovery device 10 has a control unit (not shown) that controls operations of the vacuum pump 11 , the compressor 13 , the condenser 14 , the second condenser 15 and the switching valve 17 .

Here, a specific example of main constituent elements in the cleaning liquid recovery device 10 according to this embodiment will be shown (of course, the present invention is not limited to this specific example). A sealed tank 20 having a capacity of 140 L was used. As the vacuum pump 11, a pump having an intake air volume per unit time of 3.6 m ³ /min was used. A buffer tank 12 having a capacity of 200 L was used. As the compressor 13, one that compresses atmospheric pressure gas to 0.6 MPa (approximately 6 atmospheres) was used. As the condenser 14, one that cools the gas to 10°C was used.

(2) Operation of cleaning liquid recovery apparatus, etc. of the present embodiment Next, the operation of the cleaning liquid recovery apparatus 10 of the present embodiment, and the operation of steam cleaning and vacuum drying in the sealed tank 20 that precedes it, will be described.

(2-1) Vapor Cleaning/Vacuum Drying Operation First, the lid 21 of the sealed tank 20 is opened, and the work is carried into the sealed tank 20 . At this point, the workpiece may have been cleaned to some extent by being immersed in the cleaning liquid in advance, or may not be cleaned if it is not very dirty. Next, the inside of the closed tank 20 is sealed by closing the lid 21 .

Next, after opening the channel on the gas channel 191 side by the switching valve 17 , the inside of the closed tank 20 is evacuated by the vacuum pump 11 . At this time, it is basically not necessary to operate the cleaning liquid recovery device 10 (except for the vacuum pump 11). The discharged gas passes through the buffer tank 12, the compressor 13 and the condenser 14 and is discharged to the outside. However, when the work is washed by immersing it in the cleaning liquid in advance, the vaporized cleaning liquid adhering to the surface of the work during the cleaning is exhausted. It is desirable to evacuate the tank 20 .

After the inside of the closed tank 20 is evacuated to a predetermined pressure or less, all the switching valves 17 are closed, and the steam of the cleaning liquid is introduced into the closed tank 20 from a steam supply source (not shown). As a result, part of the steam exchanges heat with the workpiece and liquefies on the surface of the workpiece, thereby cleaning the workpiece (steam cleaning).

Next, while the cleaning liquid recovery device 10 including the vacuum pump 11 is operating as described later, the switching valve 17 opens the gas flow path 191 to rapidly reduce the pressure in the closed tank 20 . As a result, the cleaning liquid adhering to the surface of the work bumps and vaporizes, and is discharged from the closed tank 20 together with the vapor that has not been liquefied. In this way, the cleaning liquid is removed from the work surface and the work surface is dried (vacuum drying). While vacuuming for vacuum drying is being performed, the flow path for discharging the gas from the closed chamber 20 is switched from the gas flow path 191 to the bypass flow path 16 by the switching valve 17. The details are as follows. The operation of the cleaning liquid recovery device 10 of the present embodiment described in 1. will be described.

(2-2) Operation of cleaning liquid recovery device 10 When vacuum drying is performed in the closed tank 20, the vacuum pump 11, the aftercooler 111, the compressor 13, and the condenser are operated before the switching valve 17 opens the gas flow path 191. 14 and the second condenser 15 are activated. When the vacuum drying is started, the vacuum pump 11 sucks the gas and the vapor of the cleaning liquid in the closed tank 20 is introduced into the second condenser 15 . In the second condenser 15, part of the introduced steam is condensed and liquefied.

Vapor that has not been liquefied in the second condenser 15 is discharged after being sucked into the vacuum pump 11 and introduced into the compressor 13 via the aftercooler 111 and the buffer tank 12 . At that time, the pressure of the steam exhausted from the vacuum pump 11 becomes a value close to the atmospheric pressure, but it fluctuates to some extent due to changes in the pressure inside the closed tank 20 . By temporarily storing the steam in the buffer tank 12, this pressure fluctuation is alleviated and the steam is supplied to the compressor 13 at a nearly constant pressure. Thereby, the operation of the compressor 13 can be stabilized.

The compressor 13 compresses the steam introduced from the vacuum pump 11 through the aftercooler 111 and the buffer tank 12, thereby supplying the steam to the condenser 14 at a pressure higher than that at the time of introduction.

The condenser 14 liquefies the vapor compressed by the compressor 13 by cooling it to a predetermined temperature. Here, since the vapor is compressed, the amount of the components of the cleaning liquid per unit volume of vapor is increased compared to when compression is not performed. Therefore, the amount of cleaning liquid components that liquefy in excess of the saturated vapor amount in the condenser 14 also increases compared to when compression is not performed. As a result, the vapor is liquefied and the amount of cleaning liquid recovered is greater than without compression. Although the vapor that is not condensed in the condenser 14 is vented to the atmosphere, the amount is less than if the compressor 13 were not used to compress the vapor.

Specifically, when the pressure of the steam is multiplied by x (>1) by the compressor 13, the amount of steam supplied to the condenser 14 per unit volume is x times that when not compressed by the compressor 13. On the other hand, the amount of vapor remaining without being condensed in the condenser 14 is only the amount determined by the partial pressure corresponding to the saturated vapor pressure at the temperature in the condenser 14, so the compression in the compressor 13 is with or without Therefore, the amount of remaining steam that is not condensed in the condenser 14 and is discharged to the atmosphere is 1/x (<1) times the amount in the case where the pressure is increased by x times in the compressor 13 than when compression is not performed. . Therefore, compressing the vapor using the compressor 13 can reduce the amount of vapor discharged to the atmosphere as compared to the case where the compression is not performed.

In addition to compressing the steam, the amount of steam discharged to the atmosphere can also be reduced by lowering the saturated steam pressure by lowering the temperature when the steam is cooled in the condenser 14. can. For example, in NS100 (sold by ENEOS Sun Energy Co., Ltd.), which is one of the hydrocarbon-based cleaning solutions, the saturated vapor pressure of the hydrocarbons contained in the cleaning solution is 0.48 MPa at 40°C and 10°C at 10°C. 0.055 MPa. In this case, by lowering the cooling temperature in the condenser 14 from 40°C to 10°C, the saturated vapor pressure becomes 0.055/0.48≒0.11 times, so the amount of steam discharged to the atmosphere is also reduced by about 0.11 times. can do. Therefore, by combining pressure application in the compressor 13 and temperature reduction in the condenser 14, the amount of vapor discharged to the atmosphere can be further reduced.

The cleaning liquid liquefied by the second condenser 15 and the condenser 14 is recovered in the cleaning liquid recovery tank 18 through the liquid sending pipe 195 . Also, in the vacuum pump 11, the buffer tank 12 and the compressor 13, part of the vapor may be cooled and liquefied, and the liquefied cleaning liquid is also collected in the cleaning liquid recovery tank 18 through the liquid sending pipe 195. be done.

As time elapses after starting the vacuum drying, the amount of steam discharged from the closed tank 20 per unit time decreases, and the second condenser 15 hardly liquefies the steam. Then, when the steam passes through the second condenser 15, an exhaust resistance is generated, which reduces the efficiency of evacuation. Therefore, when a predetermined time has passed since the start of vacuum drying, the switching valve 17 switches the steam flow path from the closed tank 20 to the vacuum pump 11 from the gas flow path 191 to the bypass flow path 16 . As a result, the efficiency of vacuuming can be improved, and the amount of steam discharged from the closed tank 20 per unit time can be increased, so that the time required for collecting the cleaning liquid can be shortened.

The present invention is not limited to the above embodiments. For example, although the bypass flow path 16 and the switching valve 17 are provided in the above embodiment, these may be omitted so that the steam discharged from the closed tank 20 always passes through the second condenser 15 . Alternatively, instead of the second condenser 15, the bypass flow path 16, and the switching valve 17, a gas flow path that directly connects the closed tank 20 and the suction side of the vacuum pump 11 is provided, and the vapor is condensed by the second condenser 15. You can choose not to do it. Furthermore, a gas passage may be provided to directly connect the exhaust side of the vacuum pump 11 and the intake side of the compressor 13, and the buffer tank 12 may be omitted.

DESCRIPTION OF SYMBOLS 10... Cleaning liquid recovery apparatus 11... Vacuum pump 111... After cooler 12... Buffer tank 13... Compressor 14... Condenser 15... Second condenser 16... Bypass flow path 17... Switching valve 18... Cleaning liquid recovery tanks 191, 192, 193 ... Gas flow path 195 ... Liquid sending pipe 20 ... Closed tank 21 ... Closed tank lid

Claims (2)

a vacuum pump whose intake side is connected to a sealed tank containing the workpiece ;
a compressor whose intake side is connected to the exhaust side of the vacuum pump and compresses the gas discharged from the closed tank by the vacuum pump;
a condenser for cooling and condensing gas compressed in the compressor, the intake side of which is connected to the exhaust side of the compressor ;
a second condenser provided between the closed tank and the vacuum pump;
a bypass flow path provided between the closed tank and the vacuum pump and connecting the closed tank and the vacuum pump without passing through the second condenser;
a switching valve that switches a channel through which gas passes between the second condenser and the bypass channel;
A cleaning liquid recovery device comprising: 2. The cleaning liquid recovery apparatus according to claim 1, further comprising a buffer tank between said vacuum pump and said compressor.

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