JPH0490794A - Dry cleaning method - Google Patents

Abstract

PURPOSE:To contrive low boiling point substitute for CFC to be used for washing by conducting solvent gas previously to a special capacitor, when active carbon adsorbing types are combined with each other and solution gas is adsorbed with vapor phase, and by liquefying the dense solvent gas to be condensed, to reduce a load to the active carbon. CONSTITUTION:Low boiling point substitute for CFC cast in a new solution tank 2 is pumped up into a washing tank 1 with a pump 3, and liquid-like soap contained in a detergent tank 5 is cast to be used for washing several times. Besides, at least one or more distilling cans 10 are necessary to be indirectly heated. Evaporating solvent is led from a first upper capacitor 12a to a second capacitor 12b, and in the mean-time, filth is discharged as sludge 13. The capacitor is for liquefying the evaporating solvent with cooling water 14 and the second capacitor 12b is provided for further liquefying non-condensed gas, but in order to reduce the load of active carbon, a third capacitor 12c which is special for liquefying the dense solvent gas to be generated from the washing tank 1 previously to be condensed, is separately combined with, to be systematized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a dry cleaning method using a low-boiling CFC substitute called second generation CFC as a cleaning agent.
2) Do.

(Conventional technology) HCFC, which is currently considered to be a promising second class fluorocarbon
-123 has a boiling point of 27-5°C1 and HCFC-141
b has a boiling point of 32,0°C2 and KCD, which is a mixture of both.
-9450 has a boiling point of 29.2°C, which is lower than the boiling point of conventional Freon CFC-113, 47.6°C, and requires measures to prevent solvent loss in washing machines.

Therefore, when using these alternative CFCs,
A combination of an activated carbon adsorption method that recovers in the gas phase the solvent gas that cannot be sufficiently recovered by the freezing method is preferable, but since the capacity of activated carbon is also limited, it is necessary to reduce the load on the activated carbon.

On the other hand, regarding special low boiling point CFC substitutes,
Poor separation of water and solvent is also a problem.

(Problems to be Solved by the Invention) In view of the above-mentioned circumstances, the present invention provides a dry cleaning method when using a low boiling point substitute for chlorofluorocarbons for cleaning.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a dry cleaning method in which a low-boiling point alternative CFC is used for cleaning and recycled, by combining an activated carbon adsorption method to remove a solvent gas. When adsorbing in the gas phase, the solvent gas from the cleaning tank is passed through a special condenser in advance to liquefy and condense the concentrated solvent gas, thereby reducing the load on the activated carbon. It also constitutes a dry cleaning method in which a permeable membrane system is combined with a separator.

(Function) Even in the conventional dry cleaning method using Freon, two condensers have been used as described in Japanese Patent Publication No. 60-29519. but,
The second condenser in this case was for liquefying the non-condensable gas in the first condenser. Therefore, when a low boiling point solvent is used, a large amount of paper is generated, and a large amount of activated carbon is required to adsorb this paper.

Therefore, if the concentrated solvent gas generated from the cleaning tank is liquefied and condensed in advance in a dedicated third condenser, and only the diluted solvent gas is adsorbed by the activated carbon, the load on the activated carbon can be reduced.

On the other hand, in the case of Japanese Patent Publication No. 60-29519, there are two types of separators: a specific gravity separation method and a filtration separation method. It is desired to achieve effective oil-water separation. In this regard, if a permeable membrane system is combined with or in place of the filtration system, higher performance separation can be achieved in line with this objective. The permeable membrane method used in the present invention refers to a method in which liquid is subjected to pressure treatment as necessary through a thin membrane, and refers to membrane separation methods including reverse osmosis and superfiltration methods9 (implemented). Example) Hereinafter, embodiments of the present invention will be explained based on the drawings.
The figure is a flow sheet of a dry cleaning method showing one embodiment of the present invention.

The low boiling point CFC substitute used in the method of the present invention is a CFC substitute with a low ozone destruction coefficient and a substitute for the conventional 1.1.2-trichloro-1,2,2-trifluoroethane (CFC-113). Regarding 2nd generation Freon,)1
-225ca (boiling point 51.VC) and H-225cb
(boiling point 56.VC), but 2,2-dichloro-1,1,1-trifluoroethane (HCFC-
123), 1,1-dichloro-1-fluoroethane (HCFC-141b) with a boiling point of 32°C, and its mixture (KCD-9450> with a boiling point of 29.2°C). Limited to those with a boiling point lower than CFC-113 at 6°C.

(1) in Figure 1 is the cleaning tank, into which the items to be cleaned are placed for dry cleaning.9 However, the cleaning tank is (1).
The cleaning tank is not limited to the washer drum type, but may also be an immersion type, shower type, jet type, ultrasonic type, steam type, multi-tank type, etc., or a combination thereof9. Inject the low boiling point alternative CFC into the new liquid tank (2). In the case of this example, as a low-boiling CFC substitute, 1-dichloro-1-trifluoroethane (HC
FC-141b> was used. This HCFC-141b
is a substance whose chemical formula is CH3・CCl2F,
Unlike conventional fluorocarbons, it contains H atoms, so it decomposes easily in the atmosphere. In addition, the KB value is 3 of CFC-113.
Since it exhibits a value of 58 higher than 1, it has a good cleaning rate and has no problem with reverse contamination, so it is seen as a promising alternative to fluorocarbons.

Here, the KB value is the number of liters of solvent added to a solution of potassium rubber in butyl alcohol until it becomes cloudy, and the larger the value, the greater the dissolving power, so it is used as a guideline for cleaning. However, HCFC-141
Since the boiling point of b is as low as 31.5°C, the drawback is that the solvent gas tends to scatter into the atmosphere and needs to be recovered in a closed system.

The low boiling point alternative CFC put into the new liquid tank (2) is pumped by the pump (3) to the cleaning tank (1) via the new liquid line (4), and connected to the upper part of the cleaning tank 1). The liquid soap filled in the detergent tank (5) is poured into the detergent tank (5) and used for washing several times. In the case of this example, 2 minutes 4
Two washes were performed: a first wash for 5 seconds and a second wash for 2 minutes and 10 seconds. After cleaning, it is dropped into a storage tank (7) via a button trap (6), and transferred to a distillation can (10) via a cartridge filter (9) by a pump (8). In the case of this embodiment, an example of washing with a fresh solution is shown, but a circulation method such as that disclosed in Japanese Patent Publication No. 60-29519, in which washing is first performed with a low concentration live dyeing solution, may be used.

At least one distillation can (10) is required, and the solvent in the distillation can (10) is evaporated by indirect heating with steam (11). This evaporated solvent is
From the capacitor (12a) to the second capacitor (12b
), while waste is discharged as sludge (13). This condenser is for liquefying the evaporated solvent by cooling water (14), and the second condenser (12b) is for further liquefying non-condensable gas, but in the method of the present invention, separately. In order to reduce the load on the activated carbon, a dedicated third condenser (L2c) is installed in advance to liquefy and condense the thick solvent gas generated from the cleaning tank (1), and this point will be described in detail later. .

Next, the liquefied solvent liquefied in the second condenser (12c) is led to the first separator (15a) of the specific gravity separation type, where oil and water are separated9. A separator (1, 5b) is installed, and a third separator (15c) is installed on the oil side. This second separator (
15b) and the third separator (15c) used a permeation membrane method, and in the case of this example, a fiber membrane filter made of Neetik (trademark) manufactured by Asahi Kasei Corporation was used, and the reverse filtration method was used.

(PA) (PB) are the high pressure pumps at that time. However, it is also possible to use a fiber membrane filter that does not apply high pressure.9 And for the third separator (15c) on the oil side,
Furthermore, a fourth separator (15d) of a flow separator type is connected to improve separation accuracy.

The dry cleaning method of the present invention combines an activated carbon adsorption method for recovering in the gas phase the solvent gas that cannot be sufficiently recovered by the freezing method alone. (1,6a)
<1.6b) are two activated carbon tanks for this purpose.
5a) (15b) (15c) and air tank (1
7), etc., to adsorb solvent gas up to a low concentration.

There are two activated carbon tanks (16a) and (16b).

This is for alternately adsorbing and desorbing two units.
If necessary, use both activated carbon (16a) (16b) during the day.
) can also be used to adsorb and desorb both at night. In addition, please use steam (18) when attaching and detaching.
is blown into the activated carbon, and drying is performed by sending in hot air heated by outside air (19) with a steam heater (20), but since both are closed systems to the first condenser (12A), dilute solvent gas is 9 The following Figure 2 shows the third condenser (
12c) is a flow sheet for explaining the action of step 12c).

(1) shows the cleaning cycle of the cleaning tank, in which first cleaning is performed for 2 minutes and 45 seconds, and then drainage is performed as well as being shaken off at high speed.

The next cleaning takes 2 minutes and 10 seconds, then pauses after draining and shaking off at high speed, followed by 4 minutes and 20 seconds of drying, resulting in a total cleaning cycle of about 13 minutes. It is shown that.

During this cycle of about 13 minutes, the conventional first activated carbon (1
6a) was cooled for 8 to 9 minutes as in (2), and the remaining time was devoted to adsorption of solvent gas. On the other hand, the conventional activated carbon (16b) desorbs for 7 to 8 minutes as shown in (3) and then goes to drying, so it does not adsorb the solvent gas generated from the cleaning tank and is in a dormant state. It was there.

However, as shown in (4), a considerable amount of solvent gas was generated from the cleaning tank even when the first activated carbon was cooling before 8 to 9 minutes, and reached a peak at 9 to 10 minutes. Therefore, in the case of using a CFC substitute with a low boiling point as in the method of the present invention, it is necessary to prepare a large-capacity activated carbon tank if such a concentrated solvent gas is sent in at once at the beginning of the first activated carbon adsorption process. If this is not done, the adsorption and recovery will become impossible.9Therefore, in the activated carbon load reduction method (5) of the present invention, for the first 8 to 9 minutes, the solvent gas generated from the cleaning tank (1-) is transferred to the activated carbon tank. Instead of sending the solvent gas, it is circulated through a dedicated third condenser (12c) to liquefy and condense the solvent gas. Then, for the next drying and the mentioned 2 minutes, it is circulated to the third dedicated condenser (12c), but at this time, the cleaning tank (1) is dried through a heater, and the thick solvent that is generated in the early 10 minutes is circulated. The force is dealt with in advance. When the final activated carbon reaches the late 10 minute mark, when the solvent gas is in a thin state, outside air is taken in and sent to the activated carbon to reduce the load on the activated carbon.9 This can be seen in Figure 1. To explain in an example, first, the circulation by the dedicated third condenser starts from the cleaning tank (1
) The solvent gas generated from the gentle blower (21
) is sent to the third condenser (12c), where it is liquefied and condensed by the cooling water (22), and first, the changeover switch (23) bypasses the activated carbon tank (from the line 24, passes through the switch (25), Use the changeover switch (26) to pass through the line (27) that does not go through the heater, pass through the changeover switch (28), and then connect the line (29).
) is returned to the cleaning tank (1) and circulated.

For the next 2 minutes of drying, turn the selector switch (26) 1.14 turns to the left in Figure 1, and connect the line (30) to the heater (3).
1) and turn the selector switch (28) to 17 on the right in the figure.
Rotate 4 times to open and chain line (27), and line (29)
It is circulated to the cleaning tank (1), and the cleaning tank (1) is agitated with hot air to dry it.

For the final 2 minutes and 20 seconds of introduction into the activated carbon, outside air (32) is put into the heater (31), the changeover switch (28) is rotated 174 times to the right, the air is passed through the line (29), and then the air is fed into the cleaning tank. (1) Dry the inside further and use the blower (2
1) via the third capacitor (12c),
Turn the selector switch (23) 174 turns to the left in the figure, and connect the line (33) to the activated carbon tank (16a) (16b).
, turn the selector switch (25) from the line (34) 174 turns to the left in the figure, turn the selector switch (26) 174 turns to the left in the figure, and return to the heater (31).In this embodiment, For explanation purposes, the heater (31) is shown separately. However, in reality, it is the steam heater (20).
One unit can be used for both purposes.

The dry cleaning method of the present invention combines an activated carbon adsorption method for adsorbing solvent gas in the gas phase. (1, 6a) and (16b) are two activated carbon tanks filled with activated carbon for this purpose. This activated carbon<16a)
(1, 6b) includes both tanks (2) (7), separators (15a) (15b) (15c), and air tank (
17) etc., up to low concentration of solvent gas.
It is designed to adsorb and desorb by using two units alternately, or by using both activated carbons (16a and 16b) to adsorb during the day and desorb at night. Use steam (18) for attaching and detaching, and use outside air (19) for drying using a steam heater (
The hot air heated in step 20) is used in a closed system to ensure that the dilute solvent gas is not released outside the system.

However, since the solvent used in the method of the present invention is a low boiling point substitute for chlorofluorocarbon, it places a heavy burden on activated carbon. Therefore, a low-air blower (21) is sent to the activated carbon tanks (16a) (16b), and a third condenser (12c) dedicated to activated carbon is systemized to this system through a shutter (22) to constantly circulate gently. Activated carbon<1
6a) <L6b) The solvent gas adsorbed in <L6b) is sequentially desorbed and liquefied, thereby reducing the load on the activated carbon. Of course, the third condenser dedicated to activated carbon <12c) is designed to constantly circulate and liquefy the gas components in the activated carbon tank (16a) (16b) using the blower (21), so pressure relief is also required for this purpose. .

In this way, the low-boiling-point alternative fluorocarbon is recovered without loss and reused.

(Effects of the Invention) The systemization of a condenser exclusively for activated carbon by the method of the present invention can eliminate the solvent loss that occurs in refrigeration systems when using low-boiling point substitutes, and can completely adsorb even low-concentration solvent gases. Although an activated carbon adsorption method was used, the load on the activated carbon could be reduced by providing a third condenser exclusively for liquefying and condensing the thick solvent gas generated from the cleaning tank.

As a result, there is no need to install large amounts of activated carbon. Moreover, by making the entire system closed, dispersion into the atmosphere can be prevented, and the expensive recovered liquid can be reused.

On the other hand, combining a permeable membrane separator according to the method of the present invention can speed up the separation of water and solvent, making it possible to perform higher-performance separation and provide cleaner drainage. became.

[Brief explanation of drawings]

(12c)...Third condenser dedicated to activated carbon <15a) <15b)...Second permeable membrane type
・3 separators (L6a) (16b)...Activated carbon tank °Patent applicant Takeshi 1) Year: Male representative
Patent attorney Hiroshi Kusano

Claims (2)

[Claims] (1) In a dry cleaning method that uses a low-boiling CFC substitute for cleaning and recycles it, when combining an activated carbon adsorption method to adsorb solvent gas in the gas phase, the solvent gas from the cleaning tank is A dry cleaning method characterized by passing the concentrated solvent gas through a condenser to liquefy and condense it to reduce the load on activated carbon. (2) A dry cleaning method that uses a low-boiling-point alternative CFC for cleaning, characterized in that a permeable membrane system is combined with a separator.