JP2015003307A - Cleaning liquid regeneration method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning liquid regeneration method which can separate water contaminated in the cleaning liquid from the cleaning liquid with smaller heat energy.SOLUTION: A cleaning liquid to which water is contaminated is stored in an evaporation tank 11. The inside of the evaporation tank 11 is decompressed to pressure in which water boils and the component of the cleaning liquid does not boil, and in an upper space of the evaporation tank 11, a cooling body 12 having temperature higher than the boiling point of the water at the pressure is provided, for discharging gas phase from the evaporation tank 11. Thereby without boiling the cleaning liquid component, water can be separated from the cleaning liquid. Therefore, heat energy consumption is suppressed.

Description

  The present invention relates to a method and an apparatus for regenerating a cleaning liquid by removing moisture mixed in a cleaning liquid used when cleaning a workpiece to which a water-soluble foreign matter adheres, such as a water-soluble cutting agent.

  In the past, oil-based cutting agents used for friction suppression and cooling when cutting metal or the like have been used, but in recent years, additives have been added to the main component of water. Water-soluble cutting agents have become mainstream because of their higher cooling efficiency. In general, a workpiece with such a water-soluble cutting agent is surface-active with a water-soluble cleaning solution such as an alcoholic solvent or a glycol ether solvent, or a solvent that is itself water-insoluble such as a hydrocarbon solution. Cleaning is performed using a cleaning liquid that can remove water-soluble foreign matters by adding an agent.

  When the above-described cleaning is repeatedly performed using the same cleaning liquid, the amount of the water-soluble cutting agent in the cleaning liquid gradually increases and the cleaning ability decreases. Therefore, in the past, in many cases, a disposable was used in which the cleaning liquid was replaced with a new one every time it was used a certain number of times. However, this would increase the consumption of the cleaning liquid. Actually, water accounts for most of the components of the water-soluble cutting agent, so if the water-soluble cutting agent mixed in the cleaning liquid after use can remove even water, the cleaning ability of the cleaning liquid will be sufficiently restored to practical use. The cleaning liquid can be reused.

  Patent Document 1 describes an apparatus for removing water from such a used cleaning liquid. In this apparatus, the cleaning liquid mixed with water is put into a distillation kettle and depressurized to a predetermined pressure. At the pressure, the boiling point of water and the components of the cleaning liquid (hereinafter, the components of the pure cleaning liquid are called “cleaning liquid components” Distinguish from cleaning liquid mixed with water.) Heat to a temperature higher than the boiling point. Thereby, both the water and the cleaning liquid components are vaporized, and a gas in which both are mixed is generated. This gas is introduced into a first gas cooler whose inside is depressurized, and at that pressure, the temperature is higher than the boiling point of water and lower than the boiling point of the cleaning liquid component (in general, the boiling point of the cleaning liquid component is higher than the boiling point of water. Therefore, this is possible.) Thereby, only the cleaning liquid component is liquefied and recovered while the water remains in a gas (water vapor) state. Thus, a cleaning liquid from which water has been removed is obtained and can be reused. The remaining water vapor is liquefied by cooling to a temperature below the boiling point in the second gas cooler, becomes water, and is discarded.

JP 2009-172468

  In the apparatus of Patent Document 1, since both are evaporated (vaporized) by making the temperature higher than the boiling points of both the water and the cleaning liquid components in the distillation pot, a large amount of heat energy including latent heat of vaporization is required. In addition, the gas generated in the distillation kettle contains an overwhelmingly larger amount of cleaning liquid components than water as in the case of the cleaning liquid before treatment. For this reason, it is difficult to completely liquefy the cleaning liquid component in the first gas cooler, and a part of the cleaning liquid component gas is introduced into the second gas cooler while being mixed in the water vapor. Therefore, a part of the cleaning liquid is wasted and the component is mixed into the water finally discarded.

  The problem to be solved by the present invention is to provide a cleaning liquid regeneration method and apparatus capable of separating water mixed in the cleaning liquid from the cleaning liquid with less thermal energy and higher accuracy.

The cleaning liquid regeneration method according to the present invention made to solve the above problems is as follows.
Store the cleaning liquid mixed with water in the evaporation tank,
The inside of the evaporation tank is depressurized to a pressure at which water boils and the components of the cleaning liquid do not boil,
In the upper space in the evaporation tank, a cooling body having a temperature higher than the boiling point of water at the pressure is provided,
Gas is discharged from the evaporation tank.

  According to the method of the present invention, by depressurizing the inside of the evaporation tank as described above, water is boiled but the cleaning liquid component is not boiled. Therefore, water is separated (vaporized) from the cleaning liquid with lower energy than the conventional method. be able to. In addition, since the cleaning liquid component evaporates until reaching the saturated vapor pressure but does not boil, water accounts for most of the gas components evaporated by the cleaning liquid. Therefore, water can be separated from the cleaning liquid with higher accuracy than the conventional method.

  The gas vaporized by the cleaning liquid is cooled by the cooling body in the upper space in the evaporation tank. Here, since the temperature of the cooling body is higher than the boiling point of water (although lower than the temperature of the gas), the water in the gas hardly liquefies and the cleaning liquid component liquefies. Thereby, the water in the gas is discharged from the evaporation tank as it is, and the liquefied cleaning liquid component returns to the cleaning liquid stored in the evaporation tank, so that it is not wasted.

  In the cleaning liquid regeneration method according to the present invention, it is not necessary to heat the cleaning liquid in the evaporation tank. Thus, energy consumption can be suppressed by not performing heating. But in order to accelerate | stimulate vaporization of water, you may heat a washing | cleaning liquid within the temperature range in which a washing | cleaning-liquid component does not boil.

  In the cleaning liquid regeneration method according to the present invention, secondary cooling may be performed in which the gas discharged from the evaporation tank is further cooled within a temperature range higher than the boiling point of water. Thereby, it is possible to remove a cleaning liquid component slightly remaining in the gas.

  In the cleaning liquid regeneration method according to the present invention, the water content in the liquid generated by cooling the gas with the cooling body is detected, and the water content is reduced based on the detection result. You may perform operation which adjusts the temperature of the said cooling body. The water content can be determined, for example, by measuring the specific gravity or refractive index of the liquid.

The cleaning liquid regenerating apparatus according to the present invention includes:
a) an evaporation tank for storing a cleaning solution mixed with water;
b) Depressurizing means for depressurizing the inside of the evaporation tank to a pressure at which water boils and components of the cleaning liquid do not boil;
c) a cooling body having a temperature higher than the boiling point of water at the pressure, provided in the upper space in the evaporation tank;
d) Discharging means for discharging gas from the evaporation tank.

  A common decompression pump can be used for the decompression means and the discharge means.

  According to the cleaning liquid regeneration method and apparatus of the present invention, water mixed in the cleaning liquid can be separated from the cleaning liquid with lower thermal energy and higher accuracy than in the past.

1 is a schematic configuration diagram showing an embodiment of a cleaning liquid regenerating apparatus according to the present invention. The graph which shows the pressure change of a boiling point about the washing | cleaning-liquid component and water which were used when implementing a present Example. The graph which expanded the graph of FIG. 2, and showed the change of the temperature and pressure in a present Example by->. The graph which shows the relationship between the content rate of the water in washing | cleaning liquid S110, and specific gravity (temperature: 22 degreeC). The graph which shows the relationship between the content rate of water in cleaning liquid S110, and refractive index. The schematic block diagram which shows the modification of the washing | cleaning-liquid reproduction | regeneration apparatus of a present Example.

  Embodiments of the cleaning liquid regeneration method and apparatus according to the present invention will be described with reference to FIGS. In the following, first, the configuration of the embodiment of the cleaning liquid regenerating apparatus will be described, and then the embodiment of the cleaning liquid regenerating method will be described together with the operation of the apparatus.

  As shown in FIG. 1, the cleaning liquid regenerating apparatus 10 of this embodiment includes an evaporation tank 11, a cooling body 12, a discharge pipe 13, a decompression pump 14, and a secondary cooling unit 15.

  The evaporation tank 11 has a shape in which both ends of the cylinder are hemispherical. The evaporation tank 11 includes an introduction pipe 111 for introducing the cleaning liquid before the regeneration process stored in the cleaning tank 21 provided outside the cleaning liquid regeneration apparatus 10 into the evaporation tank 11, and the cleaning liquid in the evaporation tank 11 after the regeneration process. A return pipe 112 is connected to the cleaning tank 21. A specific configuration for introducing and returning the cleaning liquid will be described later.

  The cooling body 12 is a coiled tube that is provided in the upper space in the evaporation tank 11 and is wound along the cylindrical inner surface of the evaporation tank 11. The pipe is connected to a cooling water source (not shown) outside the evaporation tank 11 so that cooling water can flow.

  One end of the discharge pipe 13 is connected to the upper end of the evaporation tank 11, and a decompression pump 14 and a secondary cooling unit 15 are provided in the middle of the discharge pipe 13. A pressure adjustment valve 131 is provided on the upstream side (evaporation tank 11 side) of the discharge pipe 13 from the decompression pump 14. By adjusting the opening degree of the pressure adjusting valve 131, the pressure in the evaporation tank 11 and the discharge speed of the gas in the evaporation tank 11 can be controlled. The other end of the discharge pipe 13 functions as a discharge port for water removed from the cleaning liquid.

  The secondary cooling unit 15 includes a gas passage through which the gas discharged from the decompression pump 14 passes, and a cooling water passage (a gas passage and a cooling water passage are not shown) provided around the gas passage. The second return pipe 151 for returning the liquid liquefied in the gas flow path to the cleaning tank 21 is provided. Cooling water is supplied to the cooling water flow path from the outside of the secondary cooling unit 15.

  Below a part of the cooling body 12, a liquid receiving part 116 that receives liquid falling from the surface of the part of the cooling body 12 is provided. Further, a pipe for collecting the received liquid outside the evaporation tank 11 is connected to the liquid receiving unit 116, and this pipe passes through the wall of the evaporation tank 11 and is provided outside the evaporation tank 11. A recovery container 117 is connected. As will be described later, the liquid receiver 116 and the recovery container 117 are used for recovering a sample for measuring the content of water in the liquid in which the gas in the evaporation tank 11 is liquefied.

  Next, a specific configuration for introducing and returning the cleaning liquid will be described. The introduction pipe 111 and the return pipe 112 are provided with an introduction valve 111V and a return valve 112V, respectively. A ball tap 113 for measuring the height of the liquid level is provided in the evaporation tank 11. The ball tap 113 is interlocked with the introduction valve 111V so that the introduction of the cleaning liquid is stopped when the liquid level reaches a predetermined height during the introduction of the cleaning liquid. A liquid feed pump 114 is provided in the middle of the return pipe 112. Since the liquid level in the evaporation tank 11 is always set to be lower than the liquid level in the cleaning tank 21, it is only necessary to open the introduction valve 111V at the time of introduction, whereas the return valve 112V is set at the time of return. After opening, the cleaning liquid is moved using the liquid feeding pump 114. In the middle of the return pipe 112, a filter 115 for removing solid foreign matters in the cleaning liquid is provided.

  Next, the operation of the cleaning liquid regeneration apparatus 10 (an embodiment of the cleaning liquid regeneration method according to the present invention) will be described with reference to FIGS. Here, as a cleaning liquid, “Fine Top S110” and “Fine Top NS110” (both made by Kuraray Co., Ltd.), whose main components (content ratio: 99% by weight or more) are glycol ethers, hereinafter “S110” and “NS110 ")") Is shown.

(1) Introduction of the cleaning liquid into the evaporation tank 11 First, the pre-regeneration cleaning liquid stored in the cleaning tank 21 is introduced into the evaporation tank 11 through the introduction pipe 111 by opening the introduction valve 111V. When the cleaning liquid is stored up to a predetermined amount in the evaporation tank 11, the ball tap 113 detects this and the introduction valve 111V is closed.

(2) Decompression in the evaporation tank 11 Next, the pressure adjusting valve 131 is opened, and the gas in the evaporation tank 11 is discharged out of the evaporation tank 11 by the decompression pump 14. At that time, by setting the pressure adjustment valve 131 to a predetermined opening, the inside of the evaporation tank 11 is depressurized to a pressure corresponding to the opening, and is balanced at the pressure. Here, since the relationship between the opening degree of the pressure adjustment valve 131 and the ultimate pressure in the evaporation tank 11 is the same cleaning liquid and has a certain degree of reproducibility if the storage amount and temperature are similar, the opening degree is What is necessary is just to use the thing which calculated | required the magnitude | size corresponding to required ultimate pressure (after-mentioned) by the preliminary experiment. Of course, the ultimate pressure in the evaporation tank 11 may be measured each time using a pressure gauge, and the opening degree may be finely adjusted according to the value.

Here, the graph shown in FIG.2 and FIG.3 is demonstrated as a premise for demonstrating the required ultimate pressure in the evaporation tank 11. FIG. FIG. 2 is a graph showing the relationship between pressure and boiling point (temperature) in water and a cleaning liquid (which does not contain impurities such as water), and FIG. 3 is an enlarged view thereof. As described above, since the glycol ether which is the main component of the cleaning liquid accounts for 99% by weight or more, the graph regarding the cleaning liquid may be regarded as a graph regarding the cleaning liquid component (glycol ether). The boiling points of S110 and NS110 are higher than the boiling point of water in all pressure ranges. For example, at atmospheric pressure (760 mmHg = 1.013 × 10 ⁵ Pa. Also referred to as “normal pressure”), the boiling points of S110 and NS110 are both about 175 ° C. A region between the curve indicating the boiling point of water and the curve indicating the boiling point of the cleaning liquid component (in FIG. 2, the region is indicated by a slanted line with respect to S110) indicates that “water is boiling and the cleaning liquid component is not boiling. Area. Hereinafter, this region is referred to as “intermediate pressure region”.

The necessary ultimate pressure in the evaporation tank 11 is the pressure in this intermediate pressure region. That is, as shown in FIG. 3, when the inside of the evaporation tank 11 is at a certain temperature T ₁ , the temperature T ₁ is kept as it is so as to move downward on the graph, and only the pressure is set to a predetermined value P ₁ in the intermediate pressure region. (Arrow (a) in FIG. 3).

Since the temperature of the cleaning liquid exceeds the boiling point of water at the pressure P ₁ due to this pressure reduction, the water mixed in the cleaning liquid boils and vaporizes. On the other hand, the cleaning solution components, although its temperature is below the boiling point at the pressure P _1, slightly vaporizes. The vaporized water and the gas of the cleaning liquid component move to the upper space in the evaporation tank 11.

(3) Cooling of gas In the upper space in the evaporating tank 11, cooling water is flowing into the pipe of the cooling body 12, and the water and the gas of the cleaning liquid component are cooled to the temperature T _{2 on} the surface of the pipe ( Arrow (b) in FIG. The temperature T ₂ is lower than the temperature T ₁ and higher than the boiling point of water at the pressure P ₁ . As a result, the gas is cooled within a range that falls within the intermediate pressure region. Then, the water of the in gas with little liquefied due to the high temperature T ₂ than its boiling point, the cleaning solution components are liquefied. This temperature T ₂ can be adjusted by the flow rate of the cooling water, and has a certain degree of reproducibility as with the temperature T ₁ described above. For this reason, in this embodiment, an appropriate flow rate is obtained in a preliminary experiment, and adjustment is not performed while the flow rate is set to the flow rate during the cleaning liquid regeneration method. The flow rate may be adjusted while constantly monitoring the temperature of the cooling body 12.

  The liquid liquefied when the gas is cooled by the cooling body 12 falls from the surface of the cooling body 12 into the cleaning liquid stored in the evaporation tank 11. Since the water in the gas hardly liquefies, most of the components of the liquid are cleaning liquid components, so that the concentration of the cleaning liquid component in the cleaning liquid in the evaporation tank 11 is increased by the operations so far. Therefore, the liquid falling from the surface of the cooling body 12 may be collected by the liquid receiving unit 116 and the collection container 117, and the water content in the liquid may be measured. By referring to this measurement result, the efficiency of separating water from the cleaning liquid can be increased by adjusting the flow rate of the cooling water flowing through the cooling body 12 so that the content rate decreases. The water content can be determined from, for example, a graph showing the relationship between the water content and the specific gravity in S110 shown in FIG. 4 after measuring the specific gravity of the recovered liquid. Or after measuring the refractive index of the collect | recovered liquid, the content rate of water can also be calculated | required from the graph which shows the relationship between the content rate of water and refractive index in S110 shown in FIG. The refractive index does not depend so much on the temperature, but the specific gravity strongly depends on the temperature. Therefore, FIG. 4 shows the relationship between the content and specific gravity at a specific temperature (22 ° C.).

(4) Discharge of gas from the evaporation tank 11 The gas remaining after the cleaning liquid component is liquefied by being cooled by the cooling body 12 is discharged out of the evaporation tank 11 by the decompression pump 14. The exhausted gas is mostly composed of water, but there may be a slight residual cleaning liquid component that could not be liquefied by the cooling body 12. Therefore, this gas is sent to the secondary cooling unit 15 and cooled to a temperature higher than the boiling point of water and lower than the temperature of the gas. Thereby, the cleaning liquid component remaining in the gas is liquefied. Then, the water that remains in a gas state without being liquefied is discarded after being in a gas state or liquefied. The cleaning liquid component liquefied here is returned to the cleaning tank 21 through the second return pipe 151.

(5) Returning the cleaning liquid after the regeneration process to the cleaning tank 21 If the above processes (2) to (4) are performed for a sufficient time, the cleaning liquid in the evaporation tank 11 is hardly left in the secondary cooling. Water is hardly discharged from the part 15. At that time, the decompression in the evaporation tank 11 is stopped, and a leak valve (not shown) is opened to bring the inside of the evaporation tank 11 to atmospheric pressure. Then, the return valve 112 </ b> V is opened, and the cleaning liquid in the evaporation tank 11 is returned to the cleaning tank 21 through the return pipe 112 by the liquid supply pump 114. Here, solid foreign matters in the cleaning liquid are removed by the filter 115 provided in the middle of the return pipe 112.

The present invention is not limited to the above embodiments.
For example, the secondary cooling unit 15, the liquid receiving unit 116, and the collection container 117 used in the above embodiment are not essential requirements of the present invention, and these may not be used.

  Further, as shown in FIG. 6, a heater 19 for heating the cleaning liquid may be provided in the evaporation tank 11. This heater 19 is not intended to heat the cleaning liquid above its boiling point, but to reduce the temperature change of the cleaning liquid by heating so as to compensate for the temperature drop when the inside of the evaporation tank 11 is depressurized. Used for. Of course, it is not necessary to use such a heater as long as the pressure is simply reduced and within the intermediate pressure region.

  In the above embodiment, the cooling body 12 is configured by providing a pipe for flowing cooling water in the evaporation tank 11. For example, a pipe for flowing cooling water is provided so as to be in contact with the outer wall surface of the evaporation tank 11. The wall surface may be used as a cooling body.

DESCRIPTION OF SYMBOLS 10 ... Cleaning-liquid reproduction | regeneration apparatus 11 ... Evaporating tank 111 ... Introducing pipe 111V ... Introducing valve 112 ... Returning pipe 112V ... Returning valve 113 ... Ball tap 114 ... Liquid feeding pump 115 ... Filter 116 ... Liquid receiving part 117 ... Collection container 12 ... Cooling body 13 ... Exhaust pipe 131 ... Pressure adjustment valve 14 ... Decompression pump 15 ... Secondary cooling section 151 ... Second return pipe 19 ... Heater 21 ... Cleaning tank

Claims (6)

Store the cleaning liquid mixed with water in the evaporation tank,
The inside of the evaporation tank is depressurized to a pressure at which water boils and the components of the cleaning liquid do not boil,
In the upper space in the evaporation tank, a cooling body having a temperature higher than the boiling point of water at the pressure is provided,
A cleaning liquid regeneration method, wherein gas is discharged from the evaporation tank.   2. The cleaning liquid regeneration method according to claim 1, wherein the pressure reduction is performed without heating the cleaning liquid.   The cleaning liquid regeneration method according to claim 1, wherein the pressure reduction is performed while heating the cleaning liquid within a temperature range in which the components do not boil.   The cleaning liquid regeneration method according to any one of claims 1 to 3, wherein secondary cooling is performed to cool the gas discharged from the evaporation tank within a temperature range higher than the boiling point of water.   Detecting the content of water in the liquid produced by cooling the gas with the cooling body, and adjusting the temperature of the cooling body so as to reduce the water content based on the detection result The method for regenerating a cleaning liquid according to claim 1. a) an evaporation tank for storing a cleaning solution mixed with water;
b) Depressurizing means for depressurizing the inside of the evaporation tank to a pressure at which water boils and components of the cleaning liquid do not boil;
c) a cooling body having a temperature higher than the boiling point of water at the pressure, provided in the upper space in the evaporation tank;
d) A cleaning liquid regenerating apparatus comprising a discharging means for discharging gas from the evaporation tank.

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