JP6298603B2 - Cleaning system and cleaning liquid purification device - Google Patents

Description

  The present invention relates to a cleaning system configured to remove emulsified processing oil from a used cleaning liquid so that the cleaning liquid can be reused for a long period of time, and a cleaning liquid purification apparatus.

  In any machining that can cut, polish, or plasticize a metal, a machining oil such as a cutting oil is used. Therefore, it is necessary to clean and remove the machining oil adhering to the workpiece. In the cleaning process, shower cleaning, spray cleaning, jet cleaning, immersion cleaning, ultrasonic cleaning, rocking / rotational cleaning, bubbling cleaning, steam cleaning (vacuum cleaning), and the like are appropriately selected and executed.

  The cleaning agent used in the cleaning process is generally classified into an aqueous cleaning agent, a non-aqueous cleaning agent, and a semi-aqueous cleaning agent. Aqueous detergents are usually composed of inorganic / organic builders, surfactants, chelating agents, rust inhibitors, etc., provided in the form of concentrates or powders, diluted with water about 10 to 100 times and used. Is done.

  On the other hand, non-aqueous cleaning agents are oil-based solvents, and are roughly classified into combustible cleaning agents that are subdivided into hydrocarbons, alcohols, silicones, and the like, and other non-combustible cleaning agents. However, since non-flammable cleaning agents have a problem of environmental destruction, recently, flammable cleaning agents, particularly hydrocarbon-based cleaning agents are preferably used.

  Semi-aqueous cleaning agents are intermediate cleaning agents between water-based cleaning agents and non-aqueous cleaning agents. Combustible types that contain non-aqueous solvents and surfactants, and water-soluble solvents contain a small amount of water. And non-combustible types.

JP-A-9-66266 JP 2001-149760 A

  As described above, there are various types of cleaning agents used in cleaning devices. Of these, water-based cleaning agents are not flammable or explosive and can also remove solid dirt and are toxic. There is an advantage that the running cost is very low and the running cost is low.

  In addition, water-based cleaning agents are also characterized by good compatibility with ultrasonic cleaning. Ultrasonic cleaning is a cleaning method that generates ultrasonic vibrations by placing an ultrasonic vibrator in the cleaning tank, and is extremely effective in that oil stains including the details of workpieces can be removed by the cavitation effect. Is.

  However, in ultrasonic cleaning, since emulsification and dispersion of the processing oil is promoted by ultrasonic vibration, removal of the processing oil in an emulsified state becomes a big problem. That is, an oil-water separation filter such as a coalescer cannot effectively remove emulsified processing oil.

  Here, if it is a hydrocarbon-based cleaning agent, it can be regenerated by distillation, but if it is a water-based cleaning agent, it cannot be regenerated by distillation. There was a problem that the merit in running cost of the water-based cleaning agent could not be fully utilized.

  By the way, regarding the use of the hollow fiber membrane module, there are proposals in Patent Document 1 and Patent Document 2, but these configurations do not suggest any purification treatment for the cleaning liquid. Moreover, as in the invention described in Patent Document 1, when the total amount filtration method is adopted (see FIG. 2), although the filtration efficiency is excellent, a backwash process is required after a short period of operation, and a long-term steady state is required. I can't expect driving. On the other hand, the invention described in the cited document 2 has a separation accuracy of the hollow fiber membrane of 0.5 to 3 μm and can only remove suspended substances in the coolant. It does not suggest a cleaning process for cleaning liquids containing oil.

  The present invention has been made in view of the above problems, and can effectively remove the emulsified processing oil and replace the cleaning liquid, and can continue normal operation over a long period of time, and It is an object of the present invention to provide a cleaning liquid purification device.

In order to achieve the above object, the present invention emulsifies a washing tank for washing an object to be washed using a washing liquid diluted with an alkaline detergent or a neutral detergent, and the washing liquid used in the washing tank. And a purification device that regenerates the cleaning liquid by removing the processing oil in a state, wherein the purification device passes through a specific gravity separation tank that processes the cleaning liquid used in the cleaning tank An introduction passage through which the cleaning liquid is introduced, a discharge passage for discarding the entire amount of the contaminated liquid when necessary, an upstream passage forming one circulation passage, a concentration tank communicating with the downstream passage, and the upstream passage The washing liquid received from the inlet to the inlet is circulated through the inner space of the membrane surface of the hollow fiber membrane and output from the outlet to the downstream passage, while the regenerated liquid that has passed through the hollow fiber membrane is output from the outlet. The module and the washing via the upstream passage. A liquid feed pump that supplies the liquid to the inflow port in a predetermined pressurized state and returns the liquid to the concentration tank via the downstream passage, and the regenerated liquid output from the regeneration port is, It is configured to be reused in the cleaning tank, manages the flow rate ratio of the cleaning liquid and the regenerating liquid, and the flushing process of the hollow fiber membrane module is executed under a predetermined condition. In the flushing process, in the cleaning liquid circulation path, The hot water and the neutral cleaning liquid are each circulated for a predetermined time.

  Any of the above inventions is characterized in that the cleaning liquid is purified while cleaning the membrane surface of the hollow fiber membrane with the cleaning liquid. Specifically, since the cleaning liquid containing the emulsified processing oil flows at an appropriate flow rate based on the function of the circulation unit, the cleaning liquid is refluxed to the concentration tank while cleaning the membrane surface of the hollow fiber membrane module, Further, in the process of passing through the hollow fiber membrane, the processing oil is removed and the regenerated liquid is purified. Then, since the purified regenerated liquid is reused in the washing tank, the normal operation of the washing system can be continued for a long time without replacing the washing liquid.

  Moreover, in the present invention, the cleaning liquid received at the inlet is circulated along the membrane surface of the hollow fiber membrane and output to the outlet (cross-flow filtration method), so that the inner surface of the hollow fiber membrane is constantly cleaned with the cleaning liquid. As a result, the hollow fiber membrane can function stably over a long period of time, and in this sense, the normal operation of the cleaning system can be continued for a long period of time.

  The cleaning tank of the present invention is not particularly limited, but preferably, an ultrasonic cleaning tank in which an ultrasonic vibrator is disposed to perform ultrasonic cleaning corresponds to this. By adopting the configuration of the present invention, the processing oil emulsified by ultrasonic vibration can be effectively removed.

  The cleaning liquid of the present invention is a cleaning liquid based on an aqueous or semi-aqueous cleaning agent excluding a non-aqueous cleaning agent. The water-based cleaning agent is classified into an alkaline cleaning agent, a neutral cleaning agent, and an acidic cleaning agent, and an alkaline cleaning agent and a neutral cleaning agent are used as the cleaning agent of the present invention.

  Here, alkaline detergents generally include (1) surfactants, (2) inorganic and organic builders such as caustic soda, phosphates, silicates, carbonates, chelating agents, and (3) rust inhibitors. Consists of Further, the neutral detergent is generally composed of (1) a surfactant, (2) an inorganic / organic builder, and (3) a rust preventive agent, and exhibits a cleaning effect due to the surface activity.

  The material of the hollow fiber membrane of the present invention is not particularly limited, but includes polysulfone, polyethersulfone, polyimide, polyaramid, polyacrylonitrile, polycardinate, polyamide, PMMA, polypropylene, polyethylene, polyvinyl alcohol, cellulose acetate, fluorine group-containing Resin etc. can be illustrated.

  Among these organic materials, hydrophobic polymers such as polysulfone, polyethersulfone, polyvinylidene fluoride, polyacrylonitrile, polyimide, polyaramid, polypropyne, and polyethylene are particularly preferable. In addition, it is not prohibited to contain inorganic fine powder in the organic material.

  In the present invention, the cleaning liquid for the concentration tank is preferably maintained in a temperature range of 40 ° C. to 70 ° C., and the cleaning effect can be enhanced by managing the temperature range of 40 ° C. or higher, and adhesion. Material deposition can be effectively suppressed. Moreover, a hollow fiber membrane is not deteriorated by managing in the temperature range below 70 degreeC. More preferably, the cleaning liquid for the concentration tank should be managed in a temperature range of 50 ° C to 60 ° C.

  The hollow fiber membrane of the present invention is composed of an ultrafiltration membrane having a molecular weight cut-off of about 3,000 to 50,000 and an average pore size of 0.005 μm to 0.05 μm. More preferably, an ultrafiltration membrane having a molecular weight cut-off of about 15,000 and an average pore size of 0.005 μm to 0.02 μm is used.

Since the hollow fiber membrane of the present invention performs flushing treatment (Flushing) when necessary, washing is performed including a concentration tank in a liquid flow path during normal operation without requiring an auxiliary facility for backwashing treatment. Can do. However, in the case of the present invention, since the inner surface of the hollow fiber membrane is constantly washed with the washing liquid, the period until the flushing treatment is so long as not to be compared with other configurations.

  In the hollow fiber membrane of the present invention, it is preferable that the cleaning liquid is circulated in the inner space of the membrane surface formed in a tube shape. In this case, for example, if the cleaning liquid pressurized by the pump arranged in the circulation section is introduced into the inlet, the cleaning liquid is further pressurized in the inner space of the membrane surface and presses the hollow fiber membrane outward. The filtration performance can be improved.

  In the case of the configuration of the present invention, the pressure difference between the inside and outside of the hollow fiber membrane can be limited to 300 kPa or less by managing the hydraulic pressure at the upstream position of the inlet of the hollow fiber membrane module to about 30 to 200 kPa. . Moreover, it is preferable to manage the flow rate ratio between the cleaning liquid output from the outlet and the regenerating liquid output from the regeneration port to 40: 1 to 10: 1. When the flow rate of the regenerating liquid is below the control range, flushing is performed. What is necessary is just to transfer to a process, and after a flushing process, a normal driving | operation can be restarted, without replacing | exchanging a hollow fiber membrane module.

  As described above, according to the present invention, it is possible to realize a cleaning system and a cleaning liquid purification device that can effectively remove the emulsified processing oil and continue normal operation for a long period of time.

It is drawing which shows the principal part of the washing | cleaning system SYS. It is a conceptual diagram explaining a hollow fiber membrane.

  Hereinafter, although an Example is described, the specific description content does not specifically limit this invention. FIG. 1 illustrates a main part of a cleaning system SYS provided with multiple stages of ultrasonic cleaning tanks, and shows upstream processes of a series of cleaning processes.

  As shown in the figure, the main part of the cleaning system SYS receives the cleaning liquid from the primary cleaning tank 1A and the secondary cleaning tank 1B in multiple stages and the cleaning liquid from the primary cleaning tank 1A and separates unnecessary components by specific gravity. A separation tank 2, a first filtration unit 3 that filters the washing liquid after separation of specific gravity, a purification device 4 that receives a part of the output of the first filtration unit 3 and separates the processing oil and the washing liquid, and a secondary washing tank And a second filtration unit 5 that filters the cleaning liquid from 1B.

  In each of the primary cleaning tank 1A and the secondary cleaning tank 1B, an ultrasonic vibrator US is arranged, and the workpieces cleaned in the primary cleaning tank 1A are transferred to the secondary cleaning tank 1B, thereby allowing two-stage super-cleaning. Sonic cleaning is being performed. As the cleaning liquid, a cleaning liquid obtained by appropriately diluting an aqueous cleaning agent that is an alkaline cleaning agent or a neutral cleaning agent is suitably used, and the cleaning liquid overflowing from the secondary cleaning tank 1B is introduced into the primary cleaning tank 1A, and the primary cleaning tank The cleaning liquid overflowed from the cleaning tank 1 </ b> A is introduced into the separation tank 2.

  Then, the cleaning liquid that has passed through the separation tank 2 circulates in the purification device 4 to remove impurities such as emulsified processing oil, and the purified cleaning liquid is introduced into the secondary cleaning tank 1B. Although not particularly limited, the circulation of the cleaning liquid is continuously performed without being stopped until the cleaning liquid that has been contaminated more than the limit is discarded or the flushing process of the purification device 4 is reached.

  The purification device 4 includes a concentration tank 10 managed in a temperature range of 50 ° C. to 60 ° C., a hollow fiber membrane module 11 in which a hollow fiber membrane is housed in a case, a liquid feed pump 12 for circulating a cleaning liquid, and a hollow fiber. A cleaning liquid circulation path 13 that circulates through the membrane module 11, an introduction path 14 that introduces the treatment liquid in the first filtration unit 3 into the concentration tank 10, a discharge path 15 that discharges the contaminated liquid when necessary, and a hollow fiber membrane module 11 and a supply passage 16 for supplying the cleaning / regenerating liquid purified in 11 to the secondary cleaning tank 1B.

  The hollow fiber membrane module 11 of the example is configured by bundling a plurality of polyethersulfone hollow fiber membranes having an inner diameter of about 0.6 mm to 1.0 mm. The ultrafiltration membrane has a molecular weight cut-off of about 15,000 and an average pore diameter of 0.01 μm (nominal value).

  The hollow fiber membrane module 11 of the embodiment is operated by a cross flow filtration method, and the cleaning liquid output from the concentration tank 10 is pressurized by the liquid feed pump 12 and introduced into the inner space of the membrane surface of the hollow fiber membrane. And is configured to circulate along the membrane surface. According to the confirmation experiment by the inventor, unnecessary components such as processing oil can be reliably removed by the configuration of the hollow fiber membrane module 11 described above, while an aqueous detergent (alkaline or neutral detergent) is effective. It has been confirmed that the components can be maintained at normal levels even when the hollow fiber membrane is repeatedly circulated.

  FIG. 2A illustrates the relationship between the cleaning liquid flowing in the axial direction through the inner space of the hollow fiber membrane HO and the regenerating liquid passing radially outward through the hollow fiber membrane HO. Since the hollow fiber membrane HO of the example is an ultrafiltration membrane having an average pore diameter of about 0.01 μm, even emulsified processing oil cannot pass through the hollow fiber membrane and flows straight through the inner space. To do.

  FIG. 2B illustrates the schematic configuration of the hollow fiber membrane module 11, and the inlet IN into which the cleaning liquid pressurized by the liquid feeding pump 12 is introduced and the inner space of the hollow fiber membrane HO are straightened. The outlet OUT from which the cleaning liquid flowing through the outlet is led out and the regeneration outlet RE from which the regeneration liquid that has passed through the hollow fiber membrane HO outward in the radial direction is led out are shown.

  In the case of the example, the fluid pressure at the upstream position of the inlet of the hollow fiber membrane module 11 is controlled to about 50 kPa, so that the flow rate ratio between the cleaning liquid and the regenerated liquid is set to about 100: 3. . The flow rate of the regenerated liquid tends to decrease in accordance with the operation use period of the cleaning system SYS, suggesting that the cleaning liquid in the concentration tank is contaminated with oil and the performance of the hollow fiber membrane is deteriorated.

  Therefore, when it is determined that the oil stain of the cleaning liquid in the concentration tank 10 exceeds the limit, the entire amount of the cleaning liquid in the concentration tank 10 is discarded from the discharge path 15. On the other hand, when deterioration of the filtration performance of the hollow fiber membrane is assumed, the cleaning line including the ultrasonic cleaning is stopped and the process is shifted to the flushing process.

  However, unlike the devices described in Cited Document 1 and Cited Document 2, in this embodiment, since the cleaning liquid steadily circulates in the internal space of the hollow fiber membrane, the inner surface of the hollow fiber membrane is not clogged and is stationary. The period until the performance of the hollow fiber membrane is deteriorated is very long.

  The flushing liquid is not particularly limited, but it is preferable to use warm water of 50 ° C. to 70 ° C. (typically about 60 ° C.) or a neutral aqueous cleaning agent. In this case, it is more effective to follow the flow of warm water (preliminary cleaning) → the flow of neutral cleaning agent → the flow of warm water (finish rinsing) rather than continuously circulating the water-based cleaning agent.

  The embodiment shown in FIG. 1 has been described above, but the specific description can be changed as appropriate. For example, in the embodiment of FIG. 1, a multi-stage cleaning tank is illustrated, but when the ultrasonic cleaning tank is a single tank, the purified cleaning liquid is introduced into the primary cleaning tank 1A. When the cleaning tank has a multistage configuration, the purified cleaning liquid may be introduced not only into the most downstream cleaning tank but also into other cleaning tanks.

  In addition, the application of the present invention is not limited to the ultrasonic cleaning tank, and the present invention can also be suitably applied to a downstream cleaning tank into which the cleaning liquid attached to the workpiece is brought. For example, when the present invention is applied to a finishing washing tank, the rinsing water used for finishing washing can be regenerated into clean rinsing water from which impurities are removed by circulating the concentration tank and the hollow fiber membrane module. Including such a case, the purification device 4 shown in FIG. 1 can be disposed at an appropriate position of the cleaning system as a cleaning liquid purification device.

DESCRIPTION OF SYMBOLS 1 Washing tank 4 Purification apparatus 10 Concentration tank 11 Hollow fiber membrane module 12 Circulation part 13 Circulation part SYS Cleaning system.

Claims (7)

A cleaning tank that cleans an object to be cleaned using a cleaning liquid diluted with an alkaline cleaning agent or a neutral cleaning agent, and a cleaning liquid used in the cleaning tank is received to remove the emulsified processing oil and regenerate the cleaning liquid. A cleaning system comprising a purification device,
The purification device comprises:
An introduction path through which the cleaning liquid is introduced via a specific gravity separation tank for processing the cleaning liquid used in the cleaning tank, a discharge path for discarding the entire amount of the contaminated liquid when necessary, an upstream path forming one circulation path, and A concentration tank in communication with the downstream passage;
The cleaning liquid received at the inlet from the upstream passage flows through the inner space of the membrane surface of the hollow fiber membrane and is output from the outlet to the downstream passage, while the regeneration liquid that has passed through the hollow fiber membrane is output from the regeneration port. A hollow fiber membrane module,
A liquid feed pump that supplies the cleaning liquid passing through the upstream passage in a predetermined pressurized state to the inlet and returns to the concentration tank via the downstream passage; and from the regeneration port The regenerated liquid that is output is configured to be reused in the cleaning tank,
The flow rate ratio between the cleaning liquid and the regenerating liquid is controlled, and the flushing process of the hollow fiber membrane module is executed under predetermined conditions. In the flushing process, warm water and neutral cleaning liquid are respectively supplied to the cleaning liquid circulation path. A cleaning system that is distributed over time.   The cleaning system according to claim 1, wherein the cleaning liquid for the concentration tank is maintained in a temperature range of 40C to 70C.   The cleaning system according to claim 1, wherein an ultrasonic vibrator is disposed in the cleaning tank.   The said hollow fiber membrane is a washing | cleaning system in any one of Claims 1-3 comprised by the ultrafiltration membrane whose average hole diameter is 0.005 micrometer-0.05 micrometer. The washing system according to any one of claims 1 to 4, wherein in the flushing process, a warm water circulation operation, a neutral cleaning liquid circulation operation, and a warm water circulation operation are executed in this order . The flow rate ratio between the cleaning liquid and the regenerated liquid is controlled to a predetermined control value,
6. The flushing process according to claim 1 , wherein the flushing process is executed when a flow rate ratio between the cleaning liquid and the regenerated liquid is lower than a control value in a state where oil contamination of the cleaning liquid in the concentration tank does not exceed a limit level . Cleaning system.   The purification apparatus used with the washing | cleaning system in any one of Claims 1-6.

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