JP3357447B2 - Compressed air dehumidifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressed air cleaning and dehumidifying apparatus which removes foreign matters such as solid particles contained in air and removes water vapor in the air to obtain clean dry air.

[0002]

2. Description of the Related Art In a pneumatic circuit having a pneumatic device, if the operating compressed air flowing through the circuit contains foreign matter such as solid particles and water droplets, the control valve may malfunction. Therefore, it is necessary to flow clean air through the pneumatic circuit. In addition, if steam is contained in the compressed air, corrosion of the pneumatic equipment and piping will occur, so it is necessary to remove the steam in the compressed air and dry the air.

As described above, when clean dry air having a predetermined cleanness and a predetermined dryness without containing foreign matter is required, there is a case where only a precision machine having an air pressure control device or an automatic control device is used. There are various fields such as fields of precision measuring instruments or analytical instruments and medical instruments.

[0004] As an air filter conventionally used for removing solid particles such as dust and scale contained in the air and water droplets such as free moisture, a filter element made of a sintered metal, a sintered resin or a wire mesh is used. However, in filter elements such as sintered metal, there is a limit in reducing the inner diameter of pores, and solid particles that can be removed are about 5 μm. It is difficult to remove it reliably. And
Since water droplets such as free water are subjected to centrifugal separation by centrifugal force using a louver or the like, the separation rate changes due to a change in flow rate, and stable water separation is difficult.

[0005] Air dryers for removing the humidity of compressed air are described, for example, in Hydraulic and Pneumatic Handbook (Ohm Co., Ltd., published February 25, 1989), pages 513 to 517. As described above, a refrigeration air dryer and an adsorption air dryer are known. A refrigeration air dryer cools compressed air using a refrigeration cycle to separate and condense moisture. Since chlorofluorocarbon is used as a refrigerant, not only may there be a risk of environmental destruction, but also compressors, fans, etc. , And there is a problem that power consumption increases.

On the other hand, the adsorption type air dryer is silica gel,
Drying is performed by adsorbing moisture to a solid adsorbent such as activated alumina or synthetic zeolite. If the adsorbent is pulverized, dust may be generated, and the work of replacing the adsorbent becomes necessary. There is a point.

[0007]

By the way, the present inventor studied an air dryer capable of obtaining clean and dry air with low power consumption, low running cost, and excellent operability. The following is a technique studied by the present inventors, and the outline is as follows.

That is, when a filter element is formed using a porous hollow fiber membrane, that is, a porous hollow fiber filtration membrane,
The average pore diameter of the pores communicating the outer surface of the porous hollow fiber filtration membrane and the hollow holes of this type of filter element is 0.1 μm.
Since it can be set to about m, solid particles smaller in diameter than a conventional air filter can be removed.

Further, the porous hollow fiber filtration membrane is formed of a material having hydrophobicity. When water droplets adhere to the outer surface of the hydrophobic porous hollow fiber filtration membrane, the contact angle with the water droplet increases. The water droplet becomes hemispherical or spherical due to surface tension. In other words, the hydrophobic porous hollow fiber filtration membrane has a material whose critical surface tension is smaller than the surface tension of water and is aggregated and rounded so that the surface area is minimized by the intermolecular attraction of water. Therefore, water droplets do not enter the pores of the hydrophobic porous hollow fiber filtration membrane, but only air, which is a fluid, flows into the pores, and almost 100% of the water droplets are separated. Note that the hydrophobic porous hollow fiber filtration membrane may be subjected to a hydrophobic treatment on the outer surface without using a hydrophobic material.

However, when an air filter of this type is used, the water vapor passes through the pores of the hydrophobic porous hollow fiber filtration membrane, and the water vapor cannot be removed. I can't lower it. Furthermore, when foreign matters such as water droplets, oil droplets, and solid particles adhere to the surface of the hydrophobic porous hollow fiber filtration membrane and stop, the pores become clogged, the pressure loss increases, and the flow rate decreases. Will be.

In recent years, a hollow fiber permeable membrane (gas separation membrane) for selectively transmitting water vapor in the air has been developed, and a membrane type air dryer using the same has a hollow fiber membrane inside a tubular hollow fiber membrane. By flowing air as a fluid from one end side to the other end side, while lowering the partial pressure of water vapor on the permeation side, the water vapor in the supplied air passes through the hollow fiber membrane when passing through the inside of the hollow fiber membrane. Dry air can be stably obtained because the water is transmitted through the membrane from the inside of the hollow fiber membrane and discharged to the outside of the hollow fiber membrane due to the difference in the partial pressure of water vapor present on the inner and outer surfaces of the membrane. However, this type of membrane air dryer has a structure in which foreign substances such as water droplets, solid particles, and oil pass through the inside of the hollow fiber membrane, that is, in the hollow holes, and cannot remove foreign substances only. However, it was found that the water vapor transmission performance of the hollow fiber membrane was deteriorated by the foreign matter.

An object of the present invention is to provide a compressed air cleaning and dehumidifying apparatus capable of removing foreign substances in air and removing water vapor for a long period of time with small power consumption.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0014]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

That is, in the compressed air cleaning and dehumidifying apparatus of the present invention, a raw material air supply path connecting an air pressure supply source to each of the inlets of two air filters, and an outlet of each of the air filters is connected to an inlet of an air dryer. A clean air supply path connected to the air filter for guiding the air cleaned by the air filter; and a regenerated air supply for connecting the outlet of the air dryer to the outlet of the respective air filters and returning the air dried by the air dryer. A passage, an exhaust passage for discharging regeneration air flowing backward from the regeneration air supply passage to the respective air filters, and first switching means for guiding air from the air pressure supply source to one of the two air filters. Guiding the clean air from one of the two air filters to the air dryer and passing the dry air from the air dryer to the other. Second switching means for guiding to the air filter, wherein each of the air filters is formed with a large number of pores communicating an outer surface and an inner surface of the hollow hole, and an opening of the hollow hole is formed in the air filter. The air dryer is constituted by a hollow fiber permeable membrane that has a hollow hole for guiding clean air from the inlet to the outlet and has a side wall that allows water vapor to pass therethrough. It is characterized by comprising.

Further, the compressed air cleaning and dehumidifying apparatus of the present invention comprises:
The first switching means is formed by a shuttle valve that guides air from the air pressure supply source to one of the two air filters, and an opening / closing valve that opens and closes the exhaust passage, or A position for guiding the raw air to one of the two air filters and for guiding the regeneration air from the other air filter to the exhaust passage; and a position for guiding the raw air to the other of the air filters and regeneration from the one air filter. The first switching means is formed by a switching valve that switches to a position for guiding air to the exhaust passage.

Further, either a shuttle valve for guiding the clean air from one of the respective air filters to the air dryer or an open / close valve for opening / closing the respective clean air supply passages, and from the air dryer to the respective air filters. The second switching means is formed by either a check valve for allowing a flow toward the front and preventing a flow in the reverse direction or an opening / closing valve for opening / closing the respective regeneration air supply passages.

Then, the supply of air from the air pressure supply source to one of the two air filters is switched and controlled at predetermined intervals, or according to the pressure difference between the inlet and the outlet of each air filter. Switching is controlled.

[0019]

In the above-mentioned compressed air cleaning and dehumidifying apparatus, the raw material air is guided to one of the two air filters, and foreign matters such as water droplets and solid particles are removed by the porous hollow fiber filtration membrane to be cleaned. The purified air is then guided to an air dryer, where the water vapor is removed by the hollow fiber permeable membrane and dried. The cleaned and dried air is 2
Part of the air filter flows back to the other air filter on which the cleaning operation has not been performed, and is used for regeneration of the air filter. As described above, since the air filter is regenerated while cleaning and drying the raw material air, the device can be operated for a long period without frequent maintenance. Moreover, the porous hollow fiber filtration membrane and the hollow fiber permeable membrane are used to remove foreign substances from the raw material air and water vapor in the air, respectively, so that large power is not used for drying or the like. So
Running costs can be reduced.

Since the operation of either of the two air filters can be automatically performed, maintenance of the apparatus is facilitated.

[0021]

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

(Embodiment 1) FIG. 1 is a pneumatic circuit diagram showing a basic structure of a compressed air cleaning and dehumidifying apparatus according to one embodiment of the present invention.

The illustrated compressed air cleaning and dehumidifying apparatus includes an inflow portion 10 connected to an air pressure supply source constituted by a compressor and the like, and first and second two air filters 11 and 2.
12 has a material air supply passage 21 connecting the respective inlets 11a, 12a, and the air in the atmosphere is used as the material air, and the material air is supplied to the respective air filters 1.
1 and 12.

The outlets 11b, 12b of the air filters 11, 12 are connected to the inlet 13a of the air dryer 13 by a clean air supply passage 22, and the clean air purified by the air filters 11, 12 is supplied to the air dryer. 13.

The outlet 13b of the air dryer 13 is
The drying air is connected to the outflow portion 14 by a drying air supply passage 23, and the dried air that has passed through the air dryer 13 and has been dried is discharged from the outflow portion 14 to the outside. The air flowing out of this is supplied to a portion requiring clean and dried air, such as various control devices having a pneumatic device, a coating device, a medical device such as a respiratory device, and the like.

On the other hand, a purge passage 24 is connected to a purge gas discharge port 13c of the air dryer 13 for discharging the water vapor removed by the air dryer 13 to the outside. A muffler 15 is provided.

A regeneration air supply passage 25 is formed between the dry air supply passage 23 and the outlets 11b, 12b of the two air filters 11, 12, and each regeneration air supply passage 25 has Throttle valves 16a and 16b for restricting the flow path of the regeneration air supply passage 25 are provided, and check valves 17a and 17b for permitting the flow toward the respective air filters 11 and 12 and preventing the flow in the reverse direction are provided. ing.

Inflow port 1 of two air filters 11 and 12
1a and 12a are exhaust filters 18 with built-in silencers.
Are connected to the exhaust filters 26a and 26b, respectively, and the regenerated air returned to the respective air filters 11 and 12 from the regenerated air supply path 25 is supplied to the exhaust filter 18.
From the outside.

The exhaust passage 26a is provided with the exhaust passage 26a.
An opening / closing valve 31 which can be opened and closed by a solenoid is provided at a position where the valve is closed and a position where the valve is opened.
Is provided with an on-off valve 32. Further, a shuttle valve 33 is provided in the raw air supply passage 21 for guiding the raw air flowing from the inflow portion 10 to one of the two air filters 11 and 12. 33a is communicated with the inflow portion 10 and has one of the outlets 33.
b is connected to one air filter 11, and the other outlet 33 c is connected to the other air filter 12.

Two on-off valves 31, 32 and a shuttle valve 33
These constitute first switching means for guiding the raw material air from an air pressure supply source (not shown) to one of the two air filters 11 and 12 via the inflow portion 10.

The clean air supply passage 22 is provided with a shuttle valve 34 for guiding the clean air flowing out of one of the two air filters 11 and 12 to the air dryer 13. The inlet 34a is connected to the outlet 11b of the air filter 11, and the other inlet 3
4b is connected to the outlet 12b of the air filter 12, and the outlet 34c is connected to the air dryer 13. Therefore, the shuttle valve 34 and the two check valves 17a, 1
7b constitutes second switching means for guiding the clean air from one of the two air filters 11 and 12 to the air dryer 13 and guiding the dry air from the air dryer 13 to the other air filter.

FIG. 2 is a diagram showing a detailed structure of the air filter 11, and the other air filters 12 have the same structure. As shown in FIG. 2, the air filter 11 has an air filter main body 43 formed by a cylindrical resin case 41 and a connecting portion 42 attached to an upper end of the case 41. . A metal cover 44 is provided outside the case portion 41, and the resin case portion 4 is provided.
1 is covered by a cover 44 to protect the case 41.

In order to attach the case portion 41 to the connecting portion 42, an uneven portion 45 is provided annularly in the fitting hole 42a of the connecting portion 42, and the uneven portion 45 is formed in the case portion 41 and the cover 44.
A concave / convex portion 46 whose concave / convex relationship is reversed is provided corresponding to the above. As a result, after the case 41 and the cover 44 are integrated and the upper ends thereof are inserted into the fitting holes 42a of the connecting part 42, the case 41 and the cover 44 are rotated, so that the connecting part 42 The case 41 and the cover 44 are attached. Further, the connecting portion 42 is fastened to the case portion 41 by a stopper 47 such as a screw or a spring roll pin.

An inlet (primary port) 11 a to which the raw material air supply passage 21 shown in FIG. 1 is connected is formed in the connecting portion 42, and the inlet 11 a is formed in the element accommodation chamber formed in the air filter main body 43. 48 and a guide channel 50
The air that has flowed into the inflow port 11a is guided into the element housing chamber 48 by the guide flow path 50. An outlet 11b connected to the clean air supply passage 22 and the regeneration air supply passage 25 is formed on the opposite side of the inlet 11a in the connecting portion 42, and the outlet (secondary port) 11b is connected to the case portion 41. Is communicated with the center of the element housing chamber 48 through a screw hole 49 formed in the hole.

In the element accommodating chamber 48, a cylindrical sintered porous body 51 constituting one of the filter elements is provided.
Is installed. The sintered porous body 51 having a large number of pores is, for example, a sintered metal filter made of a sintered metal or a sintered resin filter made of a sintered resin, and has an average pore diameter of about 5 μm. Then, the male screw portion 52a of the mounting portion 52 integrally formed at the upper end is connected to the connecting portion 42.
Is screwed to the connecting portion 42 by screwing to the screw hole 49. At the top of the sintered porous body 51, a connecting portion 4 is provided.
A port opened to the second secondary port 11b is formed. An attachment portion 53 having a bottom is integrally attached to the lower end of the sintered porous body 51.

As described above, a large number of holes are formed in the sintered porous body 51, and the sintered porous body 51 is formed through these holes.
Communicates with the inside of the element accommodating chamber 48.

A drain 54 is formed at the bottom of the mounting portion 53, and a drain pipe 40 having a drain 40 a communicating with the drain 54 is screwed to the bottom of the case 41. Into the drain pipe 40, a joint 55 to which a drain hose is fixed is fitted.

The porous medium-filtration membrane disposed in the sintered porous body 51 and constituting the other of the filter elements comprises a hydrophobic porous hollow fiber filtration membrane 56 and a hydrophilic porous hollow fiber filtration membrane 57. It is configured.

Hydrophobic and hydrophilic porous hollow fiber filtration membrane 5
6 and 57 have hollow holes 56a and 57a, respectively.
As shown in FIG. 7, the sheet is folded in a folded state, bundled at the opening, and joined by an adhesive at the opening. And. The hydrophobic porous hollow fiber filtration membrane 56 is arranged with its opening facing the secondary side port 11b, and the hydrophilic porous hollow fiber filtration membrane 57 is arranged with its opening facing the drain 54. I have. further,
The hydrophobic and hydrophilic porous hollow fiber filtration membranes 56 and 57
Are formed with a large number of pores 56b, 57b that connect the inner surface and the outer surface of the hollow holes 56a, 57a.

The hydrophobic porous hollow fiber filtration membrane 56 is formed of a material having hydrophobicity. Therefore, when water droplets adhere to the outer surface of the hydrophobic porous hollow fiber filtration membrane 56, the water droplets have a large contact angle and become hemispherical. The outer diameter of the hydrophobic porous hollow fiber filtration membrane 56 is 0.38 mm
And the average inner diameter of the pores 56b, that is, the fractionation characteristics is 0.
It is 1 μm. The outer surface of the hydrophobic porous hollow fiber filtration membrane 56 itself may be subjected to hydrophobic treatment without using a hydrophobic material.

On the other hand, the hydrophilic porous hollow fiber filtration membrane 57 is
Unlike the hydrophobic porous hollow fiber filtration membrane 56, it is formed of a hydrophilic material. Therefore, when a water droplet adheres to the surface of the hydrophilic porous hollow fiber filtration membrane 57, the contact angle of the water droplet becomes extremely small. The outer diameter of the hydrophilic porous hollow fiber filtration membrane 57 is the same as that of the hydrophobic porous hollow fiber filtration membrane 56, but the average inner diameter of the pores 57b, that is, the fractionation characteristics is 0.1.
Those having a size of 5 μm are used. The hydrophilic porous hollow fiber filtration membrane 57 may also be subjected to a hydrophilic treatment on the outer surface without using a hydrophilic material.

As shown in FIG. 3, the hydrophobic and hydrophilic porous hollow fiber filtration membranes 56 and 57 are arranged so as to be in contact with each other and to be mixed.

When the air filter having the above-described structure is provided in the fluid pressure circuit, the compressed fluid from the pneumatic line connected to the primary port 11a flows into the element housing chamber 48 via the guide passage. . And, the element accommodating chamber 48
The fluid flowing into the filter element first passes through the sintered porous body 51 constituting one of the filter elements, and then passes through the hydrophobic porous hollow fiber filtration membrane 56 constituting the other of the filter elements.
From the port to the secondary port 11b.

When the fluid that has flowed in contains solid particles having a relatively large diameter, such as large-diameter foreign matter or metal chips, these are the sintered porous bodies that are the filter elements that pass first. Captured by 51. This is because the pore diameter of the sintered porous body 51 is about 5 μm on average as described above, whereby the sintered porous body 51 passes through the porous hollow fiber filtration membrane 56, Large fluid solid particles are removed from the fluid reaching 57, and the fluid contains small foreign matter and water droplets.

When water drops are contained in the fluid, even when the water drops contact the hydrophobic porous hollow fiber filtration membrane 56 when the fluid passes through the porous hollow fiber filtration membranes 56 and 57. Since the hydrophobic porous hollow fiber filtration membrane 56 is formed of a hydrophobic material, the contact angle with a water droplet increases, and the water droplet becomes hemispherical or spherical due to surface tension. In other words, the hydrophobic porous hollow fiber filtration membrane 56 is agglomerated and rounded so that the critical surface tension of the material is smaller than the surface tension of water and the surface area is minimized by the attraction between molecules of water. Become. Therefore, water droplets do not enter the pores 56b of the hydrophobic porous hollow fiber filtration membrane 56, and only air, which is a fluid, flows into the pores 56b.
It will be 0% separated. Then, water droplets are repelled by the hydrophobic porous hollow fiber filtration membrane 56,
Water droplets move so as to be attracted to the hydrophilic porous hollow fiber filtration membrane 57 formed of a hydrophilic material. The critical surface tension of the hydrophilic porous hollow fiber filtration membrane 57 is close to the surface tension of water, the contact angle with water is extremely small, and the water passes through the drain port 54 from inside the element housing chamber 48. Since a slight flow of fluid is formed, the water droplets enter the inside of the hydrophilic porous hollow fiber filtration membrane 57 through the pores 57b and are discharged to the outside through the drain port 54.

As shown in the figure, since the hydrophobic porous hollow fiber filtration membrane 56 and the hydrophilic porous hollow fiber filtration membrane 57 are mixed, the outer surface of the hydrophobic porous hollow fiber filtration membrane 56 is solidified. Since the water droplets repelled together with the object are drawn to the outer surface of the hydrophilic porous hollow fiber filtration membrane 57, the mounting posture of the air filter is not limited to the one shown in the drawing, and the air filter is installed in any posture such as a horizontal direction. Can be attached.

Further, even if foreign matter having a small diameter adheres to the outer surface of the hydrophobic porous hollow fiber filtration membrane 56, water droplets that collide with the outer surface are repelled from the surface of the hydrophobic porous hollow fiber filtration membrane 56. As a result, solids are removed from the surface of the hydrophobic porous hollow fiber filtration membrane 56 together with the repelled water droplets. This prevents the pores 56b of the hydrophobic porous hollow fiber filtration membrane 56 from being clogged. Solid matter such as repelled dust is 0.15
If it is less than μm, the water is discharged from the drain port 54 through the pores 57 b of the hydrophilic porous hollow fiber filtration membrane 57.

If the treatment of the outer surface of the hydrophobic porous hollow fiber filtration membrane 56 is increased not only to water droplets but also to a degree of hydrophobicity or water repellency to repel oil, not only water but also oil can be reduced. Can also be separated. In conjunction with such a configuration, the average inner diameter of the pores 57b of the hydrophilic porous hollow fiber filtration membrane 57 is adjusted to the hydrophobic porous hollow fiber filtration membrane 56.
If it is set to be larger than the average inner diameter of the pores 56b, it is possible to cause water, oil, and solids to flow out from the drain port 54 to the outside.

The porous hollow fiber filtration membrane 56 includes
Instead of being bent into a U-shape, a straight member may be used to close one end and open the other end so that the opening faces the outlet 11b. Instead of using the sintered porous body 51, a metal or resin cylindrical body may be used, and a hole for air communication may be formed in a part of the cylindrical body.

FIG. 4 is a view showing a modification of the air filter 11, and the air filter 11 is integrally attached to a float type auto drain, that is, an automatic drainage device.
As the filter element, only the hydrophobic porous hollow fiber filtration membrane 56 shown in FIG. 5 is used, and the average pore diameter of the pores of the filtration membrane is 0.1 μm and the filtration membrane has hydrophobicity. Because of this, water droplets, solid particles, and oil are separated. The hydrophobic porous hollow fiber filtration membrane 56 shown in FIG. 5 is the same as the hydrophobic porous hollow fiber filtration membrane 56 shown in FIG.

The hydrophobic porous hollow fiber filtration membrane 56 is
2, the holder 61 may be formed of a sintered porous body, as in the case shown in FIG.

As shown in FIG. 4, a valve seat member 62 is attached to the bottom of the case 41, and a retainer 64 is attached to the valve seat member 62 via a screen 63. A hollow piston 66 having a bleed hole 65 is slidably mounted in the retainer 64 in the axial direction. A filter 67 made of a sintered porous body provided in the hollow piston 66 and an upper end of the retainer 64 A spring 68 for urging a spring force in a direction to advance the hollow piston 66 downward is provided between the first and second portions.

A float 69 is arranged outside the retainer 64, and the float 69 is supported by the retainer 64 by the receiving member 71. The receiving member 71 is provided with a vane valve 73 for opening and closing a communication hole 72 formed at the upper end of the retainer 64.

In the air filter 11 having the automatic drainage device having such a structure, when moisture is accumulated in the case portion 41, the float 69 rises and the vane valve 73 is opened. As a result, the air that has entered the storage chamber 48 pushes the hollow piston 66 down from the communication hole 72, whereby the contact between the hollow piston 66 and the O-ring 74 is released, and the liquid is discharged to the outside through the screen 63. become.
As the liquid is discharged to the outside, the float 69 is lowered, and when the vane valve 73 is closed, an upward pressure acts on the hollow piston 66 through the communication hole 75 in the case portion 41 by air pressure. Thereby, the hollow piston 6
6 contacts the O-ring 74 with the lower end of the drainage port 40a.
Is closed.

When the supply of air into the case portion 41 is stopped, upward pressure is no longer applied to the hollow piston 66, so that the hollow piston 66 is pushed down by the elastic force of the spring 68 to exhaust air. The port 40a is opened, and all the liquid is discharged to the outside.

FIG. 7 is a view showing the basic structure of the hollow fiber permeable membrane type air dryer 13. A joint part 81 having an inlet 13 a and a purge gas outlet 24 a is connected to one end of a casing body 80, and the other end thereof. Outlet 13b
And a joint portion 83 having a throttle valve 82 for supplying a reduced pressure of a part of the outflow dry air into the casing body 80 as a purge gas, thereby forming a casing of the hollow fiber permeable membrane type air dryer 13. .
Inside the casing main body 80, hollow fiber permeable membranes 84 formed of a large number of fluoropolymers are provided at both ends of the casing main body 80 by bonding with an adhesive. Has an inlet 1
A hollow hole 85 having an opening communicating with 3a and an opening communicating with the outlet 13b at both ends is formed. Therefore, the moist air flowing from the inflow port 13a is
5, and is discharged as dry air from the outlet 13b. At this time, a part of the dried out air is depressurized by the throttle valve 82, flows into the casing body 80 provided with the hollow fiber permeable membrane 84 as a purge gas, comes into contact with the hollow fiber permeable membrane 84, and It will be discharged outside through the discharge port 13c.

The humid air containing water vapor is supplied to the inlet 13a.
And flows into the hollow hole 85 of the hollow fiber permeable membrane 84,
It flows toward the outlet 13b. On the other hand, in order to lower the partial pressure of water vapor on the outer surface (water vapor transmission side) of the hollow fiber permeable membrane 84 in the casing body 80, a part of the dry air flowing out is reduced in pressure by the throttle valve 82 of the outlet side joint portion 83, and is used as purge gas. It is supplied into the casing body 80. The supplied purge gas comes into contact with the hollow fiber permeable membrane 84 and is discharged outside through the purge gas discharge port 13c. The water vapor in the humid air is
When passing through the hollow hole 85 (inside) of the hollow fiber permeable membrane 84, the difference in the partial pressure of water vapor existing on the inner and outer surfaces of the hollow fiber permeable membrane 84 is used as a driving force to drive the hollow fiber permeable membrane 84 having a high water vapor partial pressure
Permeation of water vapor occurs to the outside of the hollow fiber permeable membrane 84 having a lower water vapor partial pressure than the inside of the hollow fiber, and the amount of water vapor in the air flowing inside the hollow fiber permeable membrane 84 decreases, so that dry air can be obtained.

As a result, dry air having an atmospheric pressure dew point of about -35 ° C. or less continuously flows out of the outlet 13b. Adjusting the throttle valve 82 to adjust the casing body 80
By changing the flow rate of the purge gas to be brought into contact with the hollow fiber permeable membrane 84 in the inside, it is possible to change the dew point of the obtained dry air. If the flow rate of the purge gas is increased, the atmospheric pressure dew point becomes about −60 ° C. It is possible to lower it.

Next, the operation of the compressed air purifying / dehumidifying apparatus having the above structure will be described. In the state where the raw material air is supplied from the inflow section 10 to the shuttle valve 33 by operating the compressor (not shown), When the solenoid is energized and the exhaust passage 26a is opened, the compressed air as the raw material air flowing from the inflow portion 10 passes through the shuttle valve 33 into the air filter 12 having the porous hollow fiber filtration membranes 56 and 57. Inflow. Due to the inside of the air filter 12, the water droplets A, the oil components B, and the solid particles C contained in the raw material air do not enter the pores 56b.
Separated as shown in (A).

The air thus purified flows through the shuttle valve 34 into the air dryer 13 having the hollow fiber permeable membrane 84. Even when the purified air contains water vapor, the water vapor selectively exists as shown by the arrow D in FIG. 7 due to the difference in the partial pressure of the water vapor present on the inner and outer surfaces of the hollow fiber permeable membrane 84. The air passes through the side wall and is discharged from the purge flow path 24 to the outside. As a result, the dried air is discharged from the outlet 14 through the dry air supply path 23.

A part of the air reaching the outflow portion 14 is reduced by the throttle valve 16a through the regeneration air supply passage 25 and reduced in pressure.
Into the outflow port 11b. At this time, shuttle valve 3
4 and the check valve 17b are operating, so that dry air does not flow into the air filter 12.

The dry air flowing into the outlet 11b of the air filter 11 flows backward through the hollow holes 56a of the porous hollow fiber filtration membrane 56 in the air filter 11, and when the filtration operation is performed, the porous hollow fiber filtration is performed. Water droplets A, oil droplets B, and solid particles C adhered to the surface of the film 56 as shown in FIG.
The air spouted from the pores 56b is separated from the surface of the filtration membrane 56, and the porous hollow fiber filtration membrane 56 in the air filter 11 is regenerated.

By this regenerating action, the separated water droplets A and the like are discharged to the outside from the exhaust filter 18 through the exhaust passage 26a. As described above, when foreign matter such as water droplets is removed by the air filter 12, the other air filters 11 are simultaneously regenerated by dry air.

Next, when the power to the on-off valve 31 is released and the exhaust passage 26a is closed, the inflow port 11a of the air filter 11 and the
Is filled with regeneration air, and the pressure in this portion increases.

In this state, when the solenoid of the on-off valve 32 is energized to open the exhaust passage 26b, the throttle valve 1
6b, the air in the pipe between the on-off valve 32 is instantaneously released, the pressure between the shuttle valve 33 and the on-off valve 32 decreases, the shuttle valve 33 is switched, and the raw material from the inflow portion 10 The air is supplied to the air filter 11. As a result, foreign matters such as water droplets A are removed by the air filter 11 after the regeneration is completed, and at the same time, the air filter 1 is removed.
2 is performed.

Material air is alternately supplied to the two air filters 11 and 12 to filter foreign matter by one air filter and regenerate the other air filter.
The operation of cleaning and dehumidifying compressed air can be performed for a long period of time without frequent maintenance.

In the case shown in FIG. 1, two on-off valves 31,
After one of the valves 32 and 32 is operated for a predetermined time to open one of the exhaust passages, the two on-off valves 31 and 32 are kept closed for a short time, so that the filtering by one air filter and the filtering of the other air filter can be performed. Reproduction can be performed repeatedly. Each time is controlled by a known timer. Thereby, stable dry air is always supplied continuously.

(Embodiment 2) FIG. 8 is a pneumatic circuit diagram of a compressed air cleaning and dehumidifying apparatus according to another embodiment of the present invention.
The same reference numerals are given to parts common to the above-described embodiments. In this case, each of the two air filters 11, 12 is provided with a differential pressure detector 91, 92 for detecting a pressure difference between the air flowing from the inlet 11a, 12a to the outlet 11b, 12b. I have. Each of the differential pressure detectors 91 and 92 is provided with a signal output unit. When the clogging of each of the air filters 11 and 12 becomes a predetermined state or more, the pressure difference causes the one air filter to switch to the other air filter. The state is automatically switched to the filtration state.

As described above, by using the differential pressure detectors 91 and 92, the air filters 11 and 12 can be switched in an optimum state, and unnecessary switching can be prevented to extend the life of the clean filtration device and reduce consumption. The power can be reduced. Further, performance management and failure prediction of the air filter can be performed, and optimal maintenance can be performed.

Further, in the case shown in FIG. 8, a known coaling type air filter 93 is provided in the raw material air supply passage 21 between the inflow portion 10 and the shuttle valve 33. The high-viscosity liquid, such as tar, in the raw air flowing into the air filters 11 and 12 can be removed by the air filter 93, and the life of the air filters 11, 12 and the air dryer 13 is shortened due to clogging or sticking. , Malfunction and the like can be prevented.
Whether or not to use the air filter 93 is selected according to the nature of the raw material air to be used.

In the case shown in FIG. 8, a known micro mist air filter 94 is provided in the clean air supply passage 22 between the shuttle valve 34 and the air dryer 13. This micro mist air filter 94
Has a filtration accuracy of about 0.01 μm. By removing such fine foreign substances, the dry air after passing through the air dryer 13 is further purified, and the dry air flows back to the air filters 11 and 12. When the air filter is regenerated, the clogging inside the porous hollow fiber filtration membrane 56 in the air filters 11 and 12 can be prevented.

Whether or not to use the micromist air filter 94 is selected according to the type and properties of the raw material air to be used.

(Embodiment 3) FIG. 9 is a view showing still another embodiment of the present invention. In the compressed air cleaning and dehumidifying apparatus of this embodiment, the first switching means is replaced by a shuttle valve in the above embodiment. While the switch 33 and the two on-off valves 31 and 32 are formed, the first switching means is formed by the three-port switching valves 95 and 96.

As shown in the figure, the material air supply passage 21 is positioned between the inflow portion 10 and the air filter 11 so that the
A port switching valve 95 is provided, and a 3-port switching valve 96 is provided between the inflow portion 10 and the air filter 12. Each of the switching valves 95 and 96 is connected to the inflow portion 10 and the air filter 1 in a state where the power to the solenoid is released.
The communication between the air filters 11 and 1 is stopped by energizing the solenoid and the position where the air filters 11 and 1 communicate with each other.
The second inlets 11a and 12a are moved to positions where they communicate with the exhaust passages 26a and 26b.

Therefore, these switching valves 95, 96
Is a position for guiding the raw air to one of the two air filters 11 and 12 and for guiding the regeneration air from the other air filter to the exhaust passage, a position for guiding the raw air to the other air filter and one air filter. Has a function of switching to a position for guiding regeneration air from the exhaust passage to the exhaust passage.

(Embodiment 4) FIG. 10 is a view showing still another embodiment of the present invention. In this case, the first switching means is formed by a 5-port switching valve 97. This switching valve 9
Reference numeral 7 denotes a position for guiding the raw air to one of the two air filters 11 and 12, and a position for guiding the regenerated air from the other air filter to the exhaust passage, a position for guiding the raw air to the other air filter, and one air filter. To the position for guiding the regeneration air from the exhaust passage to the exhaust passage. In this case, the exhaust passages 26a and 26b can be opened and closed by an on-off valve, that is, a two-port switching valve 98.

(Embodiment 5) FIG. 11 is a view showing another embodiment of the present invention. In this case, a 4-port switching valve 99 is used instead of the 5-port switching valve 97 in FIG. . Other structures are the same as those in FIG.

(Embodiment 6) FIG. 12 shows another embodiment of the present invention. In this case, a 3-port switching valve 101 is provided in place of the shuttle valve 33 shown in FIGS. ing. Therefore, in this case, the three-port switching valve 1
01 and two on-off valves 31 and 32 form a first switching means.

Further, in the case shown in FIG. 12, the second switching means is formed by the check valves 17a and 17b and the shuttle valve 34 in each of the aforementioned embodiments, whereas the check valve 17a , 17b in place of each
2a and 102b are provided.
The regeneration air supply passage 25 is opened and closed by energizing the solenoids 02a and 102b. And
Air filters 11 and 12 and air dryer 13
The on-off valves 103 and 104 are provided in place of the shuttle valve 34 in the clean air supply path 22 connecting the two.

However, instead of the switching valve 101, the on-off valve 1
The on-off valves having the same structure as that of the inflow parts 10 and 2
Air supply path 2 connecting the two air filters 11 and 12
1 may be provided respectively. Further, between the two air filters 11 and 12 and the air dryer 13,
Instead of the three on-off valves 103 and 104, a three-port switching valve similar to the switching valve 101 may be provided.

As described above, the invention made by the inventor has been specifically described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and can be variously modified without departing from the gist thereof. Needless to say.

For example, the compressed air cleaning / dehumidifying device is used in accordance with the site where the device is used and the nature of the raw material air used.
The components of the various types of apparatuses described above may be arbitrarily combined.

Further, the switching valve, the opening / closing valve and the like are not limited to the solenoid valve, but can be all controlled by pneumatic pressure and can be provided with explosion-proof properties by a combination of an air timer and an air-operated valve. .

[0084]

Advantageous effects obtained by typical ones of the inventions disclosed in the present application will be briefly described.
It is as follows.

(1) It is possible to remove foreign substances in the air and water vapor for a long period of time with small power consumption.

(2) When the air is being purified by one of the two air filters, the other air filter can be regenerated, so that the reliability and durability can be greatly improved. A compressed air cleaning and dehumidifying device is obtained.

[Brief description of the drawings]

FIG. 1 is a pneumatic circuit diagram showing a basic structure of a compressed air cleaning and dehumidifying apparatus according to one embodiment of the present invention.

FIG. 2 is a sectional view showing a detailed structure of the air filter shown in FIG.

FIG. 3 is a side view showing a part of the hydrophobic porous hollow fiber filtration membrane and the hydrophilic porous hollow fiber filtration membrane shown in FIG. 2;

FIG. 4 is a sectional view showing a detailed structure of an air filter integrated with an automatic drain device.

FIG. 5 is a side view showing a part of a hydrophobic porous hollow fiber filtration membrane incorporated in the air filter of FIG. 4;

6A is a cross-sectional view showing a part of the porous hollow fiber filtration membrane in a filtration state, and FIG. 6B is a cross-sectional view showing a part of the porous hollow fiber filtration membrane in a regeneration state.

FIG. 7 is a sectional view showing a detailed structure of an air dryer having a hollow fiber permeable membrane.

FIG. 8 is a pneumatic circuit diagram showing another embodiment of the present invention.

FIG. 9 is a pneumatic circuit diagram showing still another embodiment of the present invention.

FIG. 10 is a pneumatic circuit diagram showing another embodiment of the present invention.

FIG. 11 is a pneumatic circuit diagram showing still another embodiment of the present invention.

FIG. 12 is a pneumatic circuit diagram showing still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Inflow part 11, 12 Air filter 13 Air dryer 14 Outflow part 15 Muffler 16a, 16b Throttle valve 17a, 17b Check valve 21 Raw material air supply path 22 Clean air supply path 23 Dry air supply path 24 Purge flow path 25 Regeneration air supply path 26a, 26b Exhaust passage 31, 32 On-off valve 33, 34 Shuttle valve 56 Hydrophobic porous hollow fiber filtration membrane 57 Hydrophilic porous hollow fiber filtration membrane 84 Hollow fiber permeable membrane 91, 92 Differential pressure detector 95, 96 Switching valve 97, 98 Switching valve

Claims (4)

(57) [Claims] 1. A raw material air supply path connecting an air pressure supply source to respective inlets of two air filters, and an outlet of the respective air filters connected to an inlet of an air dryer and cleaned by the air filters. A regeneration air supply path that guides the air that has passed through, a regeneration air supply path that connects the outlet of the air dryer to the exit of the respective air filters, and returns the air that has been dried by the air dryer. An exhaust passage for discharging the regenerated air flowing back to each air filter to the outside; a first switching means for guiding the air from the air pressure supply source to one of the two air filters; Second switching means for guiding clean air to the air dryer and guiding dry air from the air dryer to the other air filter; A porous hollow fiber, in which each of the air filters has a large number of pores formed so that an outer surface thereof communicates with an inner surface of the hollow hole, and an opening of the hollow hole faces an outlet of the air filter. Compressed air cleaning and dehumidification, wherein the air dryer is constituted by a hollow fiber permeable membrane having a hollow hole for guiding clean air from an inflow port to an outflow port and allowing water vapor to permeate from a side wall portion. apparatus. 2. The first switching means is formed by a shuttle valve for guiding air from the air pressure supply source to one of the two air filters and an on / off valve for opening and closing the exhaust passage. A position for guiding the raw air from the air pressure supply source to one of the two air filters and for guiding the regenerated air from the other air filter to the exhaust passage; and a position for guiding the raw air to the other of the air filters. The first valve is switched by a switching valve that switches to a position where the regeneration air from the air filter is guided to the exhaust passage.
2. The compressed air cleaning and dehumidifying apparatus according to claim 1, wherein a switching means is formed. 3. A shuttle valve that guides clean air from one of the air filters to the air dryer or an open / close valve that opens and closes each of the clean air supply paths, from the air dryer to the respective air filters. The said 2nd switching means is formed with either the non-return valve which permits the heading flow and blocks the flow of the reverse direction, or the on-off valve which opens and closes each regenerative air supply path, The said 2nd switching means is characterized by the above-mentioned. Compressed air purifier dehumidifier. 4. An air supply from the air pressure supply source to one of the two air filters is switched and controlled at predetermined time intervals, or a pressure difference between an inlet and an outlet of each of the air filters is controlled. The compressed air cleaning and dehumidifying apparatus according to any one of claims 1 to 3, wherein switching control is performed according to the switching.