JP2001149716A - Cleanig method for working liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning method for working liquid by which a cleaning performance of the working liquid is greatly enhanced, enabling repeated uses of the working liquid for a long period, and also a running cost and a waste liquid treating cost, etc., are reduced. SOLUTION: This cleaning method for the working liquid comprises a first cleaning process for removing impurities mixed in the working liquid flowing in a circulation path, and a second cleaning process for further more cleaning the working liquid. In the second cleaning process, the working liquid cleaned by the first cleaning process is diffused and flowed out to the lower part of a second storage tank 40 through a working liquid introduction cylinder 42a, and the working liquid diffused and flowed out to the lower part in the second storage tank 40 is filtered from the lower side to the upper side with a filter 44, and the working liquid filtered with the filter 44 is subjected to oil-liquid separation with an oil-liquid separation wall 46, and the resulting working liquid is collected with a liquid collection groove 47 arranged at the outer periphery of a weir 45.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying a working fluid for removing impurities mixed in a working fluid used in a production process.

[0002]

2. Description of the Related Art Working fluids used in a production process include:
For example, there are a cleaning liquid used in a cleaning operation, a grinding liquid (coolant) used in a grinding operation, and the like. In general, various impurities are mixed in these working liquids, and therefore, when they are reused, they need to be purified once.

Various proposals have been made as means for purifying the working fluid. For example, JP-A-58-1742
No. 11 discloses that a magnetic drum is made to adsorb impurities such as cutting powder mainly composed of a magnetic substance, the impurities adsorbed on the magnet drum are removed by a scraper, and non-magnetic substances such as precipitated abrasive grains are removed. A technique of scraping and removing body impurities with a scraper chain has been disclosed.

In Japanese Patent Application Laid-Open No. 59-39309, an ultrasonic vibration plate is provided on the side wall of a tank, and mainly oil contained in the working liquid is turbid by ultrasonic waves oscillated from the ultrasonic vibration plate. A technique is disclosed in which impurities are vibrated by coagulation and floating, and the floating impurities are removed by a schema.

Further, Japanese Patent Application Laid-Open No. H4-129643 discloses that the lower side of a rotary plate having a plurality of grooves spirally or concentrically on its surface is vertically immersed in a working liquid stored in a tank and slowly rotated. By doing so, impurities mainly composed of oil floating on the liquid surface of the working liquid adhere to the surface of the rotating plate and are separated from the working liquid, and thereafter, the impurities attached to the surface of the rotating plate are wiped off with a scraper. A technology for performing predetermined integration is disclosed.

In Japanese Patent Application Laid-Open No. 3-294142, a filter cloth filter is provided on the body of a rotary drum, and cutting oil passing through the filter cloth and entering the rotary drum is discharged from a conduit into a recovery tank. Techniques are disclosed.

[0007]

However, in a purification system employing any of the conventional purification methods or a combination thereof, although a certain purification effect can be expected,
It was not possible to remove finer impurities mixed in the working liquid.

For this reason, in the working fluid purified by the conventional purification system employing each of the above-mentioned purification methods, the working fluid is easily deteriorated due to corrosion of dense residues and the like, and there is a limit to prolonging the replacement cycle. This leads to high running costs and waste liquid treatment costs.

The present invention has been made in view of the above circumstances, and greatly improves the purifying action of a working fluid, thereby enabling the working fluid to be repeatedly used for a long time.
It is an object of the present invention to provide a method for purifying a working liquid that can reduce running costs, waste liquid treatment costs, and the like.

[0010]

According to a first aspect of the present invention, there is provided a method of purifying a working fluid according to the present invention, wherein working fluid used in a production process is passed through a circulation circuit and mixed into the working fluid. A first purification step for removing the impurities that have been removed;
A second purification step for further purifying the working fluid purified in the first purification step.
In the second purification step, the working liquid purified in the first purification step is diffused and discharged downward into the storage tank by a working liquid introduction cylinder provided in a storage tank for storing the working liquid. A step of filtering the working liquid diffused and drained downward in the storage tank upward from below by a filtration filter provided to partition the middle of the storage tank up and down; and The working liquid filtered by the filter is disposed along the inner periphery of a weir formed at the upper end of the storage tank, and the oil is separated by an oil-liquid separating wall whose lower end faces a lower position than the weir. A liquid separating step; and a step of collecting the working liquid separated by the oil-liquid separating wall by a collecting groove arranged on an outer periphery of the weir.

That is, according to the working fluid purifying method of the present invention, the working fluid purified in the first purifying step is supplied to the working fluid introducing cylinder by the working fluid introducing cylinder in the second purifying step. The impurities are separated and settled when they are diffused and discharged downward in the storage tank, and then the impurities are filtered by the filtration filter, and then the impurities are separated by the oil and liquid by the oil and liquid separation wall. The liquid is collected by the liquid collecting groove.

The method for purifying working fluid according to the present invention according to claim 2 is the method for purifying working fluid according to claim 1, wherein
Between the first purification step and the second purification step, the working liquid purified in the first purification step is separated into a clean working liquid and a working liquid containing impurities by a centrifuge. A centrifugal separation step is provided, and the second purification step is characterized in that the working fluid containing impurities, which is separated by the centrifugation step, is purified.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 to FIG. 9 show, as an embodiment of the present invention, purification of a working fluid (cleaning fluid) used in a cleaning machine in a cleaning step after a lapping operation by a compound lapping machine for finishing tooth surfaces of a hypoid gear set. 1 shows a system.
FIG. 1 is a top view schematically showing a purification system, FIG. 2 is a sectional view taken along line II of FIG. 1, FIG. 3 is a sectional view taken along line II-II of FIG.
Is a cross-sectional view showing a main part of the scraper conveyor, FIG. 5 is a front view showing a main part of the scraper, FIG. 6 is a cross-sectional view taken along line IV-IV of FIG. 5, FIG. 7 is a top view of the float suction, and FIG. FIG. 9 is a sectional view taken along line V-V, and FIG. 9 is a sectional view taken along line III-III of FIG.

[0015] As shown in FIG.
A first purifier 1 for purifying the working fluid after being used in a washing machine (not shown), and a first purifier 1 downstream of the first purifier 1 which is connected to the first purifier 1 so as to be connectable to the first purifier 1. A second purification device 2 for performing secondary purification. Reference numeral 3 in the figure denotes a clean tank that stores the working fluid that has been purified by the present purification system.

The first purifying apparatus 1 is provided with a first working liquid storage tank 5 capable of storing a working liquid.

The first working liquid storage tank 5 is formed in a substantially box shape, and the inside thereof is divided into a first tank chamber 7 and a second tank chamber 8 by a partition plate 6.

Further, the first working liquid storage tank 5 is provided on the partition plate 6 at a substantially central position in the longitudinal direction of the partition plate 6.
A communication port 6a for communicating between the first tank chamber 7 and the second tank chamber 8 is opened at a position near the level of the working liquid stored in the tank (see FIGS. 2 and 3).

Further, a working liquid supply groove 9 is provided in the upper part of the first working liquid storage tank 5. The downstream end of the working liquid supply groove 9 faces the first tank chamber 7, and the working liquid used in the washing machine is supplied to the first tank chamber 7 through the working liquid supply groove 9. It has become so.

Here, a leg 5a is provided at an important position at the bottom of the first working liquid storage tank 5, and the first working liquid storage tank 5 is provided at a predetermined height from the installation surface by the legs 5a. (See FIGS. 2 and 3).

As shown in FIG. 3, the first tank chamber 7
Is provided with a scraper conveyor 11 for removing sludge precipitated on the bottom surface 10 and oils and fats floating on the liquid surface of the working liquid.
Is provided.

The scraper conveyor 11 is slidably disposed along the bottom surface 10 of the first tank chamber 7 and has one end slidably provided on one side wall of the first tank chamber 7. The other end protrudes from the other end of the first tank chamber 7.

That is, the bottom surface 1 of the first tank chamber 7
0 has an inclined surface 10a which is inclined upward from the middle of the longitudinal direction to the other end, and the other end of the scraper conveyor 11 is inclined along the inclined surface 10a and the other end of the first tank chamber 7 is formed. It is projected from the side. In addition, the first
A curved surface 10b is formed at one end of the bottom surface 10 of the tank chamber 7, and one end of the scraper conveyor 11 is slid along the curved surface 10b.

Here, the scraper conveyor 11 is
It has a conveyor body 12 and a plurality of scrapers 13 formed in a rectangular plate-like member having a length substantially equal to the width of the first tank chamber 7 (see FIG. 2) and disposed on the conveyor body 12. It is configured.

More specifically, as shown in FIG.
The conveyor body 12 is provided with mounting plates 12a for mounting the scrapers 13 at predetermined intervals. The scraper 13 is provided with a long hole 13a (see FIG. 5), and the scraper 13 is provided with a bolt 15 inserted through the long hole 13a via a spacer 14.
It is displaceably mounted on the mounting plate 12a (see FIG. 6).

When the conveyor body 12 is driven in the direction of arrow A (see FIG. 3), the scraper 13 is displaceably attached to the conveyor body 12 so that the scraper 13 is in contact with the bottom surface 10 of the first tank chamber 7. The first tank chamber 7 is slid reliably and discharges sludge, oil, and the like to the outside of the other end side of the first tank chamber 7 along the inclined surface 10a. In addition, a collection box 16 for collecting discharged sludge, oil, and the like is provided outside the other end of the first tank chamber 7 at a position where the other end of the scraper conveyor 11 is exposed.

The first tank chamber 7 is provided with an oil / liquid separating plate for separating the oil / fat floating on the liquid surface from the working liquid flowing into the second tank chamber 8 through the communication port 6a. 1
7 are provided.

The oil-liquid separation plate 17 is formed in a box shape with one side surface and a bottom surface opened, and the lower end portion is below the liquid surface and surrounds the communication port 6a. Installed.

The second tank chamber 8 is provided with a heating plate 20 for heating the working fluid flowing from the first tank chamber 7 at a position facing the communication port 6a.

Here, the lower end of the heating plate 20 is disposed so as to be separated from the bottom surface of the second tank chamber 8 by about 10 cm above. Note that this arrangement is an arrangement in which convection is easily generated in the working liquid that has flowed in.

At the four corners of the second tank chamber 8,
Corner plates 21 are provided at the four corners to form curved portions to improve the flow of the working liquid in the second tank chamber 8 and to prevent sludge or the like from being deposited at the four corners. I have.

A substantially central portion of the bottom surface 22 of the second tank chamber 8 is provided with a recess 22a for collecting and depositing settled sludge and the like in one place.
Is provided with a drain valve 22b at the lower end thereof.

At a substantially central position of the second tank chamber 8, oil or the like floating on the liquid surface of the working liquid is sucked up and the first liquid is sucked.
A float suction 23 for returning to the tank chamber 7 is provided.

The float suction unit 23 is provided with an oil / fat suction unit 24 that can float on the vicinity of the liquid level of the working fluid and suck the floating oil / fat near the liquid level.

As shown in FIGS. 7 and 8, the oil / fat suction unit 24 is, for example, a plate member 24 of a triangular stainless member.
a and floats 24b provided at three corners of the plate 24a.
And a fat and oil suction port 24 provided at the center of the plate body 24a.
c.

The fat / oil suction part 24 is provided with a fat / oil suction port 24c.
Is set so as to float at a position where the upper end is slightly lower than the liquid level of the working liquid, so that the floating oil and fat mainly at the liquid level can be sucked from the oil and fat suction port 24c.

At the lower end of the oil / fat suction port 24c,
The oil guide pipe 26 is connected. The other end of the oil guide pipe 26 faces the first tank chamber 7, and the oil and fat sucked from the oil and oil suction port 24 c is transferred to the first tank chamber 7 by the pump 25 interposed in the middle of the oil guide pipe 26. It is to be returned.

Here, the plate body 24a is provided with a plurality of through holes 24d for preventing sludge or the like from accumulating on the plate body 24a.
The buoyancy is kept constant and the floating position is kept constant.

The second purifier 2 is movably installed near the first purifier 1.

The second purifier 2 is connected to the second tank chamber 8 via a liquid guide pipe 29, a first centrifuge 30, and a second centrifuge 31.

More specifically, a pump 32 is interposed in the middle of the liquid guide pipe 29, and the pump 32 pumps up the primary purified working liquid in the second tank chamber 8. .

Further, the first and second centrifuges 30,
Reference numeral 31 denotes a well-known type provided with a separation tube (not shown), which separates sludge and the like contained in the working liquid by passing the working liquid flowing from the inlets 30a and 31a in a vortex shape in the separation tube. It is supposed to. Then, the working liquid purified by the above-mentioned separation cylinder is discharged from the outlets 30b and 31b, while the working liquid containing sludge and the like is discharged from the drain port 30b.
c, 31c. In the present embodiment, the first and second centrifuges 30, 3
For example, a Laval separator (registered trademark; manufactured by Nippon Laval Co., Ltd.) is employed in the first embodiment.

The inlet 30a of the first centrifuge 30
Is connected to the downstream end of the liquid guide tube 29.

Further, the outlet 30 of the first centrifuge 30
b is connected to the inflow port 31a of the second centrifuge 31 via the liquid guide tube 35.

On the other hand, the drain port 30 c of the first centrifugal separator 30 is connected to the second purification device 2 via the liquid guide tube 36.

The outlet 31 b of the second centrifugal separator 31 is connected to the clean tank 3 via a liquid guide tube 37.

On the other hand, the drain port 31 c of the second centrifugal separator 31 is connected to the second purification device 2 via the liquid guide tube 38.

That is, the first and second centrifuges 3
Reference numerals 0 and 31 are connected in series, and the clean working liquid purified by the first and second centrifuges 30 and 31 is directly supplied to the clean tank 3 while the working liquid containing sludge or the like is provided. Only is supplied to the second purification device 2.

A branch pipe 29a for branching the working liquid flowing through the liquid guide pipe 29 is provided in the middle of the liquid guide pipe 29 downstream of the pump 32, and the upstream side of the branch pipe 29a is connected to the branch pipe 29a. It faces the vicinity of the heating plate 20 in the second tank chamber 8. That is, a part of the working liquid pumped by the pump 32 is returned into the tank chamber 8 by the branch pipe 29a, and is discharged near the heating plate 20. The working fluid discharged from the branch pipe 29a causes the working fluid in the second tank chamber 8 to flow into the recess 2.
It is circulated around 2a.

The second purifying apparatus 2 is provided with a second working liquid storage tank 40 capable of storing a working liquid.

The second working liquid storage tank 40 has a cylindrical tank body 40a and a tapered bottom surface 40b formed integrally with the lower end of the tank body 40a and on which sludge or the like can be deposited, and a mat hole under the tank body 40a. And a unit 40c.

Here, the second working liquid storage tank 40
Is placed on the trolley 41, whereby the first
Is installed movably in the vicinity of the purifying device 1.

At a substantially central position of the second working liquid storage tank 40, a square working liquid introducing cylinder 42 is provided upright.

The first and second centrifugal separators 3 are provided above the working liquid introducing cylinder 42 via the liquid guide pipes 36 and 38.
The drain ports 30c and 31c of 0 and 31 are connected, and the working liquid is supplied.

A plurality of diffusion holes 42a are formed in the lower portion of the working liquid introduction cylinder 42, and the working liquid supplied to the working liquid introduction cylinder 42 is supplied from the diffusion holes 42a to the second working liquid storage tank. 40 so that it is uniformly diffused.

Further, a filter holding portion 43 is provided at a position slightly above the middle portion of the tank body 40a.

A filtration filter 44 is detachably held in the filtration filter holding portion 43.
With this, the inside of the tank main body 40a is partitioned.

As the filter 44, for example, a heat insulating and soundproofing material for building materials, which is formed by laminating glass wool having a wire diameter of about 5 μmφ to a thickness of about 5 cm, is employed.

A step is formed in a semicircular portion on one side of the upper end of the tank body 40a, and this step functions as a weir 45 for overflowing the purified working liquid. .

An oil-liquid separation plate 46 is provided on the inner periphery of the weir 45. The oil-liquid separation plates 46 are provided at predetermined intervals along the inner periphery of the weir 45. The upper end of the oil-liquid separation plate 46 is located at a predetermined height above the weir 45, and the lower end of the oil-liquid separation plate 46 is immersed in the working liquid below the weir 45.

A collecting groove 47 for collecting the working liquid overflowing from the weir 45 is provided on the outer periphery of the weir 45.
Is provided. The liquid collecting groove 47 is connected to the clean tank 3 via a liquid guide tube 48.

In the second working liquid storage tank 40, a drain valve 49 is provided below the filter 44 of the tank body 40a, and a drain valve 50 is provided at the lower end of the mat hole 40c.

Next, the operation of the purification system having the above configuration will be described. The working fluid that has flowed into the first tank chamber 7 from a washing machine (not shown) via the working fluid supply groove 9 is
The fluid flows slowly and is diffused into the first tank chamber 7.

At the time of this diffusion, among the impurities contained in the working fluid, sludge having a relatively large particle size is precipitated on the bottom surface 10 of the first tank chamber 7 and oils and the like are deposited on the surface of the working fluid. Be suspended.

At this time, the scraper conveyor 11 is
It is operated in the direction of the middle arrow A, and the settled sludge and floating oils and the like are scraped by the scraper 13 to the bottom surface 1.
It is scraped up along the 0 inclined surface 10 a and collected in the collection box 16.

Here, one end of the bottom surface 10 has a curved surface 10b.
Is formed, and the scraper 13 slides on the curved surface 10b, so that it is possible to prevent the settled sludge or the like from remaining on the bottom surface 10 and decay.

Next, the working liquid diffused in the first tank chamber 7 flows into the second tank chamber 8 through the communication port 6a. At this time, the working liquid passes below the oil-liquid separation plate 17 and reaches the communication port 6a, so that the oil and the like floating on the liquid surface are dammed by the oil-liquid separation plate 17.

The working liquid flowing into the second tank chamber 8 is
First, convection is generated by collision with the heating plate 20, and the plate is heated. As a result, fine sludge of 10 μm or less that cannot be completely removed in the first tank chamber 7 floats on the liquid surface, and oils and fats remaining in the working fluid are decomposed and float on the liquid surface. .

Next, the working liquid is filled in the second tank chamber 8 by the working liquid discharged from the branch pipe 29a.
It flows at a gentle flow velocity around a. Thereby, the settled sludge and the like are concentrated and deposited on the concave portion 22a which is the center of the flow, and the fine sludge and the oil and the like floating on the liquid surface are also concentrated above the concave portion 22a.

The sludge and the like accumulated in the concave portion 22a are removed by appropriately opening the drain valve 22b, and the floating fine sludge and oils and the like are returned to the first tank chamber 7 by the float suction 23.

Here, since the corner plates 21 are provided at the four corners of the second tank chamber 8, the flow of the working liquid in the second tank chamber 8 can be made favorable.
It is possible to prevent sludge and the like from accumulating in the four corners and decomposing.

The working liquid thus purified is sucked up from the liquid guide pipe 29 and flows into the first centrifuge 30. Here, since the working fluid sucked up from the liquid guide pipe 29 is subjected to the primary purification in the first purification device 1, a relatively clean working fluid having a small amount of sludge, oil or the like remains therein. It is.

The first centrifuge 30 further purifies the working fluid, supplies the purified working fluid to the second centrifuge 31 via the liquid guide tube 36, and includes sludge and the like. The working liquid is supplied to the second purification device 2 via the liquid introduction pipe 36.

The second centrifugal separator 31 further purifies the working fluid, and supplies the purified clean working fluid to the liquid introduction pipe 3.
The working fluid containing sludge and the like flows into the clean tank 3 through the pipe 7 and is supplied to the second purification device 2 through the liquid guide pipe 38.

Here, the drain ports 30c and 31c have
A drain valve (not shown) is provided, and by adjusting the opening of these drain valves, the flow amount of the working liquid into the second purification device 2 can be adjusted.

As described above, the working fluid is purified by the first and second centrifuges 30 and 31, whereby
The burden of purifying the working fluid by the second purifying device 2 described below can be reduced. When the amount of the working liquid to be purified is small or the like, the first and second centrifuges 30 and 31 are omitted, and the liquid guide pipe 29 is directly connected to the second purification device 2. You may.

When the working liquid is supplied to the working liquid introducing cylinder 42 through the liquid guide pipes 36 and 38, the working liquid is supplied to the diffusion holes 42.
The fluid flows into the lower part of the second working liquid storage tank 40 through the a at a gentle flow rate, and is uniformly diffused in almost all directions.

The diffused working fluid flows above the tank body 40a at a gentle flow rate, and at this time, impurities such as sludge slightly remaining in the working fluid are separated by settling and formed on the tapered bottom surface 40b. After being deposited, the tapered surface is further settled and accumulated in the mat hole portion 40c.

The working liquid flows further above the tank body 40a, and when passing through the filter 44, impurities such as sludge slightly remaining in the working liquid without being separated by sedimentation are filtered.

Here, the amount of impurities trapped by the filtration filter 44 is small, and the filtration of the working fluid is a filtration from the bottom to the top. Is deposited on the tapered tank bottom surface 40b when it reaches a certain amount. Therefore, the replacement life of the filtration filter 44 can be maintained long.

The working liquid filtered by the filtration filter 44 flows further upward, overflows from the weir 45 and flows into the liquid collecting groove 47. At this time, the oil or the like slightly floating on the surface of the working liquid is blocked by the oil-liquid separating plate 46, and only the clean working liquid flows into the liquid collecting groove 47. The clean working liquid that has flowed into the liquid collecting groove 47 flows into the clean tank 3 via the liquid guide tube 48.

Here, sludge and the like deposited in the mat hole portion 40c are removed by appropriately opening the drain valve 50. Oil and the like floating on the surface of the working liquid are appropriately removed by vacuum air or the like. In addition, a drain valve for removing oils and fats may be provided above the second working liquid storage tank 40.

As described above, the second working liquid storage tank 40
Works as a precipitation tank, a filtration tank, and an oil-liquid separation tank in order from the bottom to purify the working liquid.

The working liquid stored in the clean tank 3 is supplied again to the washing machine.

When cleaning the second purifying device 2, first, the drain valve 49 is opened to extract the supernatant of the working liquid, and then the drain valve 50 is opened and the mat hole 40c is opened. A working liquid containing a large amount of sludge or the like is removed, and then the mat hole 40
Cleaning is performed by opening c. The supernatant of the working liquid can be reused.

According to such a purification system, purification at a high level can be performed, so that the working fluid exchange cycle can be extended up to about 60 weeks.

Therefore, it is possible to reduce the number of times of processing the waste liquid of the working liquid, and it is possible to reduce the usage amount of the working liquid.

Further, since the amount of waste liquid discharged can be reduced, the cost of waste liquid treatment can be reduced, and the environment is also good.

Further, the number of maintenance steps required for exchanging the working liquid and the like can be greatly reduced.

Further, a concave portion 22a on which sludge or the like can be deposited is provided on the bottom surface 22 of the first tank chamber 5, and this concave portion 22a
Since a drain valve is provided at the lower end of the container, the sludge and the like that have settled out can be easily removed.

Further, a sludge or the like is deposited below the second working liquid storage tank 40, and a tapered bottom surface 40b capable of sedimentation and accumulation is provided.
Since the drain valve 50 is provided at the lower end of the container, the sludge and the like that have settled out can be easily removed.

In the present embodiment, the cleaning liquid used in the cleaning machine is used as the working liquid, and the cleaning of the cleaning liquid has been described. However, the working liquid purified by the present cleaning system is not limited to the cleaning liquid. The grinding fluid (coolant) used in the machine may be purified.

[0093]

As described above, according to the present invention, the purifying action of the working fluid is greatly improved, and the working fluid can be used repeatedly over a long period of time. Etc. can be reduced.

[Brief description of the drawings]

FIG. 1 is a top view schematically showing a purification system.

FIG. 2 is a sectional view taken along line II of FIG. 1;

FIG. 3 is a sectional view taken along line II-II of FIG.

FIG. 4 is a sectional view showing a main part of the scraper conveyor.

FIG. 5 is a front view showing a main part of the scraper.

6 is a sectional view taken along line IV-IV of FIG.

FIG. 7 is a top view of the float suction.

8 is a sectional view taken along line VV in FIG. 7;

9 is a sectional view taken along the line III-III in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st purification apparatus 2 ... 2nd purification apparatus 30 ... Centrifuge 31 ... Centrifuge 40 ... 2nd working liquid storage tank (working liquid storage tank) 42 ... Working liquid introduction cylinder 44 ... Filtration filter 45 … Weir 46… Oil-liquid separation plate 47… Collection groove

Claims (2)

[Claims] 1. A first purifying step of flowing a working fluid used in a production process through a circulation circuit to remove impurities mixed in the working fluid; and a working fluid purified in the first purifying process. And a second purification step for further purifying the working fluid, wherein the second purification step comprises: storing the working fluid purified in the first purification step in the working fluid. A step of diffusing and flowing down the inside of the storage tank by a working liquid introducing cylinder installed upright in the tank; and dividing the working liquid diffused and flowed down in the storage tank vertically in the middle of the storage tank. A step of filtering upward from below by a filtration filter provided as described above, and disposing the working liquid filtered by the filtration filter along an inner periphery of a weir formed at an upper end of the storage tank. ,That A step of separating the oil and liquid by an oil and liquid separation wall whose end faces a position lower than the weir; and a liquid collecting method in which the working liquid separated by the oil and liquid separation wall is disposed on the outer periphery of the weir A method for purifying a working fluid, comprising: collecting a liquid by a groove. 2. The method according to claim 1, wherein the working fluid purified by the first purification process is cleaned by a centrifuge between the first purification process and the second purification process. 2. The purification method according to claim 1, further comprising a centrifugal separation step of separating the liquid into a liquid and the second purification step, wherein the second purification step purifies the working liquid containing impurities, which is separated by the centrifugation step. Method.