JPH08299716A - Washing system - Google Patents

Abstract

PURPOSE: To prevent washing liquid and permeated liquid from entering a washing tank during backward washing in a washing system equipped with a membrane utilizing type oil-water separation system by providing a discharge route for water containing oils with a check valve and installing an oily water accumulation means placed in the uppermost part of the washing system on the downstream side of the check valve. CONSTITUTION: In a washing system equipped with a membrane utilizing type oil-water separation means 22, a discharge route 3 for water containing oils discharged from a washing tank 1 is provided with a check valve 41, and besides, an accumulation tank 43 as an accumulation means for water containing oils placed in the uppermost part of the washing system is installed at the downstream side of the check valve 41 of the discharge route 3. The check valve 41 prevents a washing liquid being present in the 2nd circulation route 20 and the 1st circulation route 10 during backwashing from backflowing to the washing tank 1 through the discharge route 3. The accumulation tank 43 accumulates the washing liquid being present in the 2nd circulation route 20 and the 1st circulation route 10 which has been temporarily increased during backward washing. The washing liquid L6 accumulated in the accumulation tank 43 flows to the 1st circulation route 10 after the washing system finishes backward washing and starts normal filtration again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a membrane-utilizing type oil / water separating means used for, for example, reusing a cleaning liquid or treating waste water, and a membrane permeating liquid by causing a membrane permeate to flow backward through the membrane-utilizing type oil / water separating means. The present invention relates to a cleaning system provided with a backwash means for reversing the direction.

[0002]

2. Description of the Related Art Conventionally, there is a cleaning system used for reusing a cleaning liquid or treating waste water, which employs a membrane-utilizing oil-water separating means utilizing an ultrafiltration membrane.

In this method, oil / water is filtered by passing through a membrane having fine pores much smaller than the size of an oil droplet, and oil and water are separated to obtain an oil-free cleaning liquid.

FIG. 3 shows an example of a conventional cleaning system using a membrane-based oil / water separating means. This cleaning system 10
Numeral 0 is for removing dirt and oil attached to the work W101 to be cleaned. A cleaning liquid L101 containing water and a detergent as main components is put into the cleaning tank 101, and the work W101 is immersed therein. It removes dirt and oil by physical actions such as ultrasonic waves, stirring, and rocking. Here, 102 is illustrated as an ultrasonic oscillator.

When the workpieces W101 are continuously and successively put into the cleaning tank 101, the cleaning liquid L
Since the oil content concentration of 101 increases and the cleaning ability for the work decreases, the cleaning system 100 includes an oil / water separating means as described below.

This is a two-stage oil / water separating means provided downstream of the discharge route 103, and the first stage is the first circulation route 11
0, and the pump 111 and the floating oil recovery means 1
12 are provided.

The second stage is due to the second circulation path 120 downstream of the first circulation path 110, and the pump 121
And a membrane-utilizing type oil / water separating means 122, and a cleaning liquid L101 in which relatively large oil droplets are separated in the first-stage circulation path 110.
And returns the filtered cleaning liquid into the cleaning tank 101 through the return path 131.

The principle of the floating oil recovery means 112 is that, as shown in FIG. 4, the cleaning liquid L110 is stored in the retention tank 112a so that the oil droplets L111a can easily come into contact with each other, and the water component L1.
12 and the oil droplet L111a collect minute oil droplets (for example, several to several tens of μm) and float upward as large oil droplets (for example, several hundreds of μm) to cause the water component L112 and the oil component in the cleaning liquid L101. L111 is separated.
In the retention tank 112a, the oil component L111 is separated in the order of FIG. 4 (a), FIG. 4 (b), and FIG. 4 (c).

Further, though not shown in FIG. 4, a coalescer filter having an ultrafine fiber structure is provided in the retention tank 105, and the cleaning liquid L101 is allowed to pass through the coalescer filter to further increase the oil droplet L111a. Some promote specific gravity separation.

Next, as the membrane-utilizing oil / water separating means 122, a hollow fiber membrane module 123 using a bundle of a large number of hollow fiber membranes 124 as an ultrafiltration membrane is used, and the second circulation path is used. A cross flow in which a cleaning liquid supplied by a pump 121 provided in 120 is flown in parallel to the inner surface of the membrane wall of the hollow fiber membrane 124, and a part of oil water at that time is filtered by passing through the membrane wall. It has become a type. This cross-flow type is a membrane-based oil / water separating means 12
2 for long-term operation, the hollow fiber membrane module 123
In the circulation path of the cleaning liquid to be filtered (circulation path 12
It is a method to prevent the contamination and clogging of the film surface to the minimum by always providing a flow parallel to the film by providing it in 0).

Naturally, the cleaning liquid that has not permeated the hollow fiber membranes 124 in the hollow fiber membrane module 123 is the second circulation path 12.
0 will be circulated, and the oil component concentration will rise, so
The oil component passes through the secondary pressure control valve 113, returns to the first circulation path 110, and the oil component is separated by the floating oil recovery means 112.

[0012] In the cleaning system 100, therefore, the oil component emulsified and dispersed in the cleaning liquid is also discharged as it circulates through the first and second circulation paths 110 and 120, so that finally the work is brought in. It is designed so that the amount of oil carried in and the amount of oil component discharged from the floating oil recovery means 112 become equal, and at the same time, the cleaning tank 101,
The oil component concentrations in the first and second circulation paths 110 and 120 are also stable within their respective predetermined ranges.

It should be noted that although the description of the constituent elements included in FIG. 3 which are unnecessary for explanation is omitted, 125 is the primary side pressure regulating valve and 126 and 127 are the primary parts of the hollow fiber membrane module 123, respectively. The secondary pressure gauge.

[0014]

However, although the cleaning system 100 described above employs the cross-flow type membrane-utilizing oil / water separating means 122, if filtration is continued for a long time, the oil component Since a large number of hollow fiber membranes 124 of the hollow fiber membrane module 123 are clogged due to airborne contaminants, suspended contaminants, or the like, a predetermined interval (for example, 10 to 60) is required.
Once every minute), high-pressure air is introduced into the hollow fiber membrane module 123 from the backwash valve 132, and the permeated liquid in the hollow fiber membrane module 123 is permeated from the opposite direction of the membrane of the hollow fiber membrane 124 to prevent clogging. It is done to eliminate it (called backwashing).

During the backwash, the motor 121 and the motor 111 are stopped, so that the permeated liquid that has permeated the hollow fiber membrane 124 in the opposite direction pushes the inside of the second circulation path 120 and the first circulation path 110. Circulating cleaning fluid with high oil component concentration, and
The permeated liquid in which high oil components and floating pollutants mixed in the reverse direction through the membrane of the hollow fiber membrane 124 are mixed is the discharge path 1
Back into the cleaning tank 101, and the cleaning tank 10
There was a problem that the oil component concentration in 1 was extremely increased, and the cleaning degree of the work was temporarily reduced. Therefore, at the time of backwashing, it may be necessary to temporarily stop the introduction of the work or confirm the cleanliness of the washing liquid after the backwashing, and the washing capacity (throughput) is lowered.

The present invention has been made to solve the above-mentioned problems of the prior art, and its object is to determine the concentration of the oil component circulating in the circulation path during backwashing of the membrane-utilizing type oil-water separating means. This is to prevent the high cleaning liquid or the permeated liquid that has flowed back from invading the cleaning tank and keep the concentration of the cleaning liquid in the cleaning tank within a certain range.

[0017]

In order to achieve the above object, according to the present invention, there is provided a first aspect including a discharge path for oil water discharged from a cleaning tank and a floating oil recovery means connected to the discharge path. A first circulation path, a second circulation path provided with a membrane-utilizing oil / water separating means that shares a part of the first circulation pathway downstream of the floating oil recovery means of the first circulation pathway, and the membrane-utilizing oil / water. A cleaning system comprising a return path for returning the membrane permeate from the separation means to the cleaning tank, and a backwash means for reversing the membrane permeate in the middle of the membrane permeate return path to reverse the membrane permeation direction. It is characterized in that the discharge path is provided with a check valve, and the oil water storage means arranged at the top of the cleaning system is connected to the discharge path downstream of the check valve.

It is also preferable that the oil-water accumulating means arranged at the top of the cleaning system is an accumulator for accumulating oil-water flowing back into the discharge path.

[0019]

In the oil-water separator having the above structure, when the backwash means is operated to cause the membrane permeate to flow backward in a direction opposite to the normal permeation direction of the membrane-utilizing oil-water separator,
Even if the cleaning liquid existing in the circulation path and the first circulation path flows back to the discharge path of the oil water discharged from the cleaning tank, it does not flow into the cleaning tank due to the check valve provided in the discharge path.

Then, the cleaning liquid existing in the second circulation path and the first circulation path, which has been temporarily increased during the backwash, is accumulated in the oil / water accumulating means.

The cleaning liquid stored in the oil-water storage means is
After the cleaning system finishes the backwash and starts the normal filtration again, the cleaning system flows into the first circulation path.

Further, the cleaning liquid existing in the second circulation path and the first circulation path, which is temporarily increased during the backwash, can be accumulated by the accumulator which accumulates oil water.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments.

(First Embodiment) FIG. 1 is a first embodiment of a cleaning system to which the present invention is applied. This cleaning system S
1 is the cleaning system 100 of FIG. 3 described as a conventional example.
It follows the basic configuration of.

The cleaning system S1 removes dirt and oil adhering to the work W1 to be cleaned. The cleaning tank 1 is filled with a cleaning liquid L1 containing water and a detergent as main components.
The work W1 is dipped in it to remove dirt and oil by physical actions such as ultrasonic waves, stirring, and shaking. Here, 2 is exemplified as an ultrasonic oscillator. When the works W1 are continuously introduced into the cleaning tank 1 one after another, the oil concentration of the cleaning liquid L1 in the cleaning tank 1 is increased and the cleaning ability for the work is lowered.
1 includes an oil / water separating means OS1 as described below.

This is a two-stage oil / water separation means OS1 provided downstream of the discharge route 3, and the first stage is the first circulation route 1
0, and the pump 11 and the floating oil recovery means 12
It has. The floating oil recovery means 12 is the same as that described in FIG.

The second stage is formed by the second circulation route 20 downstream of the first circulation route 10, and is provided with a pump 21 and a membrane-utilizing oil / water separating means 22.
The cleaning liquid L2 in which relatively large oil droplets are separated at 0 is filtered, and the filtered cleaning liquid L4 is returned to the cleaning tank 1 through the return path 31.

A part of the cleaning liquid that has not been filtered by the membrane-utilizing oil / water separating means 22 circulates through the second circulation path 20 to become a cleaning liquid L3 containing a large amount of oil components further concentrated, and
The other part of the cleaning liquid that is not filtered is the secondary pressure control valve 13
The cleaning liquid L5 flows through the first circulation path 10 to return to the floating oil recovery means 12 and the oil component is separated.

Here, as the membrane-utilizing oil / water separating means 22, a hollow fiber membrane module 23 using a bundle of a large number of hollow fiber membranes 24 as an ultrafiltration membrane is used, and the second circulation path is used. The cleaning liquid L2 and the cleaning liquid L3 supplied by the pump 21 provided in 20 are made to flow in parallel to the inner surface of the membrane wall of the hollow fiber membrane 24, and part of the oil water at that time passes through the membrane wall. It is a cross-flow type that filters.

The cross-flow type means that the hollow fiber membrane module 23 is provided in the circulation path (circulation path 20) of the cleaning liquid to be filtered so that the membrane-utilizing oil / water separation means 22 can be operated for a long period of time, and the membrane is always used. It is a method to prevent the contamination and clogging of the membrane surface by making a flow parallel to the above.

In the cleaning system 1, therefore, the oil component emulsified and dispersed in the cleaning liquid is concentrated and discharged as it circulates through the first and second circulation paths 10 and 20 described above. The amount of oil brought into the work W1 is designed to be equal to the amount of oil component recovered by the floating oil recovery means 12, and at the same time, the cleaning tank 1, the first and second circulation paths 10 are provided. The oil component concentrations in the oils 20 and 20 are also stable within their respective predetermined ranges.

Incidentally, 25 is a primary side pressure adjusting valve, and 26, 27.
Are pressure gauges on the primary and secondary sides of the hollow fiber membrane module 23, respectively.

Further, the cleaning system 1 described above
Employs a cross-flow type membrane-utilizing oil / water separating means 22, but if filtration is continued for a long time, a large number of hollow fiber membranes of the hollow fiber membrane module 23 may be generated due to oil components, floating pollutants and the like. In order to cause the membrane of 24 to be clogged, high-pressure air is introduced into the hollow fiber membrane module 23 from the backwash valve 32 as a backwash means once at a predetermined interval (for example, 10 to 60 minutes). The permeated liquid in the membrane module 23 is permeated from the direction opposite to the membrane of the hollow fiber membrane 24 to eliminate clogging (called backwashing).

Reference numeral 41 is a check valve for preventing backwashing of the washing liquid into the washing tank 1 during backwashing. Also, 43
Is a storage tank 43 as an oil / water storage means for storing the cleaning liquid present in the second circulation path and the first circulation path, which temporarily increases during backwashing. It is conceivable to adopt an atmosphere open tank as the storage tank 43. In this case, if the storage tank 43 is in a lower position, the cleaning liquid may overflow, and the cleaning liquid L1 from the cleaning tank 1 may leak. It must be placed at the top of the cleaning system 1 via the path 42 so that it does not flow in.

The operation of the cleaning system 1 having the above structure is as follows.
When high pressure air is introduced into the hollow fiber membrane module 23 from the backwash valve 32 to cause the membrane permeate to flow backward in a direction opposite to the normal permeation direction of the hollow fiber membrane module 23, Cleaning liquid L3 existing in the first circulation path 10
Even if L5 tries to flow back to the discharge path 3, it does not flow into the cleaning tank 1 due to the check valve 41 provided in the discharge path 3.

Then, the cleaning liquids L3 and L5 existing in the second circulation path and the first circulation path, which temporarily increase during the backwash, are
It is stored in the storage tank 43.

Cleaning liquid L6 stored in the storage tank 43
Flows into the first circulation path 10 after the cleaning system 1 finishes backwashing and starts normal filtration again.

In this embodiment, the backwashing means is constructed so that high pressure air is blown from the backwash valve 32. However, a backwash tank is provided in the middle of the return passage 31 to store the filtered washing liquid L4, and the stored washing liquid L4. It is also possible to flow back into the hollow fiber membrane module 23.

Further, although the position where the oil storage tank 43 is disposed is the uppermost part of the cleaning system 1, the position can be changed depending on the pressure of the high pressure air and the amount of the cleaning liquid to be backflowed.

(Second Embodiment) FIG. 2 shows a second embodiment to which the present invention is applied. The cleaning system 2 of the second embodiment has the same basic configuration as the cleaning system 1 described in the first embodiment, but an accumulator capable of accumulating oil water instead of the accumulation tank 43 as oil water accumulating means. 51 is adopted.

The accumulator 51 is also preferably a pressure-filled type, for example, like a bladder or piston type, in which a partition wall 52 is provided between the filled gas G1 and the accumulated cleaning liquid L6.

In the second embodiment, the accumulator 51 is used as the oil / water accumulating means, and by changing the pressure of the enclosed gas G1, the installation position of the accumulator 51 is not restricted and the accumulator 51 can be installed at any place. become. Further, since the cleaning liquid L6 does not directly contact the atmosphere or the enclosed gas G1 due to the partition wall 52 of the accumulator 51, these gases are entrained in the cleaning liquid L6, and the first and second circulation paths 1
It is possible to prevent the intrusion into the 0, 20.

The other structure and operation are the same as those of the first embodiment described above, and therefore, the same components are designated by the same reference numerals and their description is omitted.

[0044]

EFFECT OF THE INVENTION The present invention has the above-mentioned structure and action, and when the membrane-utilizing type oil / water separating means is backwashed, the washing liquid having a high oil component concentration circulating in the circulation path and the permeated liquid which has flowed back are discharged. The check valve provided in the path does not infiltrate into the cleaning tank, and the backwash does not change the concentration of the cleaning liquid in the cleaning tank, thus preventing the cleaning efficiency from decreasing.

The cleaning liquid present in the circulation path increased by the backwash is temporarily accumulated in the oil / water accumulating means, and when the backwash is completed, the cleaning solution returns to the circulation path, so that unnecessary consumption of the cleaning fluid does not occur.

Further, by using the accumulator as the oil / water accumulating means, there is no restriction on the installation position of the accumulator, and it is possible to install the accumulator at any place.
The gas is prevented from being entrained in the cleaning liquid and entering the circulation path.

[Brief description of drawings]

FIG. 1 is a diagram of a cleaning system according to a first embodiment of the present invention.

FIG. 2 is a diagram of a cleaning system according to a second embodiment of the present invention.

FIG. 3 is a diagram of a conventional cleaning system.

FIG. 4 is an explanatory view of floating oil recovery means.

[Description of Reference Signs] 1 cleaning tank 2 ultrasonic oscillator 3 discharge path 10 first circulation path 20 second circulation path 11,21 pump 12 floating oil recovery means 22 membrane-utilizing oil / water separation means 23 hollow fiber membrane module 31 return path 32 Backwash valve 41 Check valve 43 Storage tank (oil-water storage means) 51 Accumulator (oil-water storage means) L1, L2, L3, L4, L5, L6 Cleaning liquid OS1 Oil-water separation means S1, S2 Cleaning system W1 Work

Claims (2)

[Claims] 1. A discharge path of oil water discharged from a cleaning tank, a first circulation path including a floating oil recovery means connected to the discharge path, and a downstream side of the floating oil recovery means of the first circulation path. First
A second circulation path having a membrane-utilizing oil / water separating means that shares a part of the circulation path; a membrane-permeating liquid returning path that returns the membrane-permeating fluid from the membrane-utilizing oil / water separating means to the cleaning tank; A backwashing means for reversing the flow rate of the membrane permeate in the middle of the membrane permeate return path to reverse the direction of membrane permeation, the cleaning system comprising a check valve in the discharge path, A cleaning system characterized in that an oil / water accumulating means arranged at the top of the cleaning system is connected to the downstream side of the check valve. 2. The cleaning system according to claim 1, wherein the oil water storage means arranged at the uppermost part of the cleaning system is an accumulator that stores oil water flowing back to the discharge path.