JPH0679244A - Closed type solvent cleaning and recovery method and device therefor - Google Patents

Abstract

PURPOSE:To reduce the quantity of noncondensing gas in a device and to elimi nate the solvent loss and boundary pollution by desorbing solvent gas from active carbon by the 1st condenser, treating distillation vapor gas by the 2nd condenser and previously resucing the load of the active carbon by the 3rd condenser to systematize the method. CONSTITUTION:In a closed type solvent cleaning and recovery method where low boiling point solvent is used for cleaning, three condensers for liquefying and condensing the low boiling solvent are provided. And when a series of regeneration treatment is performed by a closed system, the low boiling point solvent gas is desorbed from active carbon by the 1st condenser 26 of direct cooled type and the load of the active carbon is previously reduced by the 3rd condenser of direct cooled type 17 and further the 2nd condenser 9 of chiller water type for treating distillation vapor gas is combined to systematize the method so that it may be suitable particularly for the use of a substitute for fluorocarbon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hermetically sealed solvent cleaning and recovering method and apparatus, and more particularly to a hermetically sealed solvent cleaning and recovering apparatus which is adapted to a low boiling point alternative CFC which meets the regulation of CFC. TECHNICAL FIELD The present invention relates to a method for cleaning and recovering a solvent and an apparatus therefor.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 60-29519 is representative of a closed solvent cleaning and recovering method and apparatus. However, this was a system for trifluorotrifluoroethane (Freon 113) as a solvent under a certain cleaning cycle for an object to be cleaned such as cloth.
Therefore, it cannot be applied to other objects to be cleaned such as metals, and to future CFC alternatives having a low boiling point.

On the other hand, a closed type solvent cleaning and recovering method and apparatus applicable to various objects to be cleaned is disclosed in Japanese Patent Laid-Open No. 20780/1990.
No. 1 publication is known. This was a system in which various cleaning machines were combined with individual distillation cans, activated carbon tanks, condensers, etc., as a system, and recovery processing corresponding to the cleaning cycle could be performed. However, since the conventional CFC 113 is targeted, it is not applicable to a CFC alternative.

On the other hand, the present applicant has filed an application for a CFC alternative. This was to reduce the load of activated carbon by adsorbing the concentrated solvent gas in advance through a special third condenser before adsorbing the low boiling point solvent gas of the alternative CFC on the activated carbon. . But the second
There is no detailed description of the condenser, and it is not possible to completely deal with the alternative CFC having a low boiling point.

Apart from the above series of developments, a closed solvent cleaning and recovering method for alternative CFCs by a vacuum system has also been proposed. This is one in which the inside of the system is evacuated so that the solvent gas having a low boiling point is not emitted to the outside, but the greatest drawback of this vacuum system is that the cleaning cycle requires a long time.

[0006]

In view of the above-mentioned circumstances, the present invention is a systematic one that can cope with the layout of a factory for various kinds of cleaning including metal cleaning, etc. Among the alternative CFCs called second generation CFCs, it is possible to adapt to the particularly promising low-boiling-point CFCs, and it is a closed type that does not allow the emission of low-boiling-point solvent gas into the atmosphere. It is an object of the present invention to provide a closed solvent cleaning and recovering method and an apparatus therefor under the above conditions.

[0007]

In order to achieve the above object, the present invention provides a closed solvent cleaning and recovering method using a low boiling point solvent for cleaning, which comprises a condenser for liquefying and condensing a low boiling point solvent gas. A stand is provided, the direct condenser first condenser is used for desorption from the activated carbon, the chiller water second condenser is used to process the gas into the distillation vapor, and the direct cooling third condenser is used to preload the activated carbon. A closed solvent cleaning and collecting method and a washing machine that are systematically reduced, a distillation can, an activated carbon tank, a condenser,
In a closed solvent washing and recovering apparatus for low boiling point solvent, which systematizes a separator as necessary, the condenser is
Direct cooling first condenser for desorption of activated carbon, chiller water second condenser for distillation vapor gas treatment, and direct cooling third condenser for reducing load of activated carbon It constitutes a device.

[0008]

[Operation] Since the present invention is configured as described above, a washing machine, a distillation can for distilling the contaminated liquid after washing into a distillation gas, and a solvent gas are adsorbed so that various washing methods can be supported. When performing a series of regeneration treatment of the activated carbon tank, the condenser for liquefying and condensing the solvent gas, and the separator for separating the oil and water by the closed system, the direct cooling type of the activated carbon desorption In addition to 1 condenser, a direct cooling type table 3 condenser for reducing the load of activated carbon is installed, and on top of this, a second chiller water system for distilling vapor gas treatment is adopted so that it can be adapted to the use of CFC substitute especially in the low boiling point range. It consists of a closed-type solvent washing and recovery method and its system that are systematically combined with a condenser.

[0009]

EXAMPLE The solvent used in the present invention is, of course, 1.1.2-trichloro-1.2-trifluoroethane (CFC-113) having a boiling point of 47.6 ° C. and H having a high boiling point.
Alternative chlorofluorocarbons such as -225ca (boiling point 51.1 ° C) and H-225cb (boiling point 56.1 ° C) are also possible, but 1.1 dichloro-1-fluoro with a boiling point of 32 ° C, which is particularly promising in the future, is preferable. Ethane (HCFC-141b), 2.2-dichloro-1.1.1-trifluoroethane (HCFC-123) with a boiling point of 27.5 ° C., and 35% with 1.1-dichloro-1-fluoroethane and 2. 2-dichloro-
It is suitable for low boiling point solvents such as (KCD-9450) with a boiling point of 29.2 ° C. which is a mixture with 1.1.1-trifluoroethane 65%.

The washing machine used in the present invention may be of various types such as a shower type and a washer drum type, but vapor washing can also be performed by directly connecting a chiller water type condenser to the washing machine. .

The distilling can used in the present invention is a pipe for connecting a steam pipe, indirectly heating the contaminated cleaning liquid to extract a clean solvent gas component, and separating and discharging the contaminated sludge.

The activated carbon tank referred to in the present invention is a tank filled with activated carbon for adsorbing a solvent gas, and is a series of tanks usually composed of two or more for adsorption and for desorption during or during the adsorption. That is.

The condenser is used for liquefying a solvent gas. In the present invention, the first condenser for desorption from activated carbon is a direct cooling type with cooling water, which is used for distilling vapor gas treatment. The second condenser is a chiller water type, and the third condenser for reducing the load of activated carbon is a direct cooling type with frozen water.

The term "separator" as used in the present invention means an oil-water separator comprising a specific gravity difference separation system or a filtration separation system, and is not required if steam is not added to the activated carbon and no water enters. Usually used.

In the system of the present invention, a connecting pipe between the washing machine and the second condenser for performing vapor washing, an air tank for keeping an air balance in the system, and a lid of the washing tank are provided. If necessary, auxiliary equipment such as an adsorption blower for keeping the inside of the system at a negative pressure to prevent the solvent gas from being released to the outside is provided.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a flow sheet of a closed-type solvent cleaning / collecting apparatus showing an embodiment of the present invention.

(1) is a shower type washing machine, but the washing machine is not limited to this, and is a jet type, washer drum type, immersion type, ultrasonic type, steam type or multi-type multi-tank A washing machine may be used.

The lid (1a) of the washing machine is opened to put the article (2) to be washed, the lid (1a) is closed and the shower (1b),
The solvent is jetted from (1b) for cleaning. There is a limit switch (1c) on the top of this washer (1),
When the lid (1a) is opened, the adsorption switch (1c) starts to operate the adsorption blower (3) and keeps the system negative pressure, so that the low boiling point solvent gas is not released to the outside. The device is incorporated.

After cleaning, the contaminated liquid is a button trap (4).
It is dropped into the solvent tank (5) via the. (5a)
Is a float switch in the solvent tank (5), and when it reaches a certain amount, it is transferred to the distillation can (7) by the pump (6).

In the present embodiment, the contaminated cleaning liquid used for the shower was a low boiling point CFC alternative consisting of 1.1-dichloro-1-trifluoroethane (HCFC-141b). This HCFC-141b is a substance whose chemical formula is represented by CH ₃ · CCl ₂ F, and contains H atoms unlike conventional CFCs, so it decomposes well in the atmosphere and has a low ozone depletion coefficient. ing.
Moreover, the KB value is higher than 31 of the conventional CFC-113.
Since it shows 8, the cleaning rate is good, and there is no problem with reverse contamination, so it is considered as a promising alternative to CFCs. The KB value is the mol number of a solvent added to a solution in which potassium rubber is dissolved in butyl alcohol until clouding occurs. The larger this value is, the larger the dissolving power is.
However, HCFC-141b has a low boiling point of 31.5 ° C. For this reason, special consideration is required for sealing to prevent the low-boiling-point solvent gas from being scattered into the atmosphere and for recovering a large amount of solvent gas.

In the distillation can (7), the contaminated solvent is vaporized and gasified by indirect heating by the steam (8), and the solvent gas evaporated here is guided to the second condenser (9) at the upper part, while the waste is It is discharged as sludge (10).

The second condenser (9) strongly liquefies and condenses the distilled vapor gas with the chiller water (11), and the liquefied solvent is then transferred to the first separator (12). The enhancement effect of the second capacitor (8) of the present invention is clear when compared with the flow sheet of FIG. 3 showing a conventional example. The conventional second condenser (a) is a direct cooling type that uses ordinary cooling water (b) instead of using strong chiller water. Further, it was not directly connected to the distillation can (c), and played a supplementary role of liquefying the solvent gas desorbed from the activated carbon via the first condenser (d). On the other hand, the second condenser (9) of the present invention uses chiller water (11) to enhance the cooling effect, and is directly connected to the distillation can (7) so as to play a central role in the liquefaction recovery in the distillation step, It is dedicated to the treatment of distilled vapor gas, and is intended to strongly reduce the amount of solvent gas vapor in the system.

In the case of the present embodiment, the first separator (12) is of a specific gravity difference separation system, and the second separator (13) which is subsequently arranged in parallel with a step is A filtration separation method or a permeable membrane method can be used, oil water is separated by these separators, and the regenerated fresh liquid from which water is removed is stored in the storage tank (14).

The first washing and the like are controlled by a timer (not shown), but the solvent tank (5) has already been emptied by transferring the contaminated liquid after washing to the distillation can (7). Therefore, the new liquid in the storage tank (14) is transferred to the solvent tank (5), the new liquid (regenerated) is pumped to the washing machine (1), and at least the second washing is performed. In this way, washing and recovery are circulated and repeated.

When the washing is completed, the adsorption blower (3) is activated, the steam heater (15) and the electric heater (16) are turned on, and the thick solvent gas generated in the washing machine (1) is heated by hot air. Is sent to the third condenser (17) by means of an air tank (18) provided in the system, and the check valve (18a) blows out at a constant pressure and the check valve (18b) sucks at a negative pressure. ) And are provided so that the air in the system can be kept in balance.

The third condenser (17) is a direct-cooling condenser for feeding frozen water from the refrigerator, and is provided in advance to reduce the load of activated carbon. That is, as shown in the treatment cycle of the solvent gas generated from the washing machine in FIG. 2, the valve (20) in FIG. 1 is opened to circulate in the third condenser (17) before the washing cycle begins to dry. The liquefaction condensation process was carried out, and the introduction into the activated carbon was carried out after the washing cycle became dry and the solvent gas became diluted.
The valve (20) shown in the figure is closed and the valve (21) is opened to take in the air and send it to the first activated carbon tank (22) or the second activated carbon tank (23) for adsorption. I try to reduce the load.

The solvent recovery of the present invention employs an activated carbon adsorption system for completely adsorbing a low concentration solvent gas in the gas phase. The first activated carbon tank (22) and the second activated carbon tank (23) are for that purpose, but two of them are alternately adsorbed and desorbed, or both are used for adsorption in the daytime and desorbed at night. It is intended to be used, for example.

Desorption from activated carbon is carried out by activating steam (8), and the solvent gas desorbed from activated carbon is introduced into a first condenser (26) of direct cooling type with cooling water (25) for liquefaction condensation. Then, it is sent to the first separator (12).

The pipe (27) in the system is the second
The condenser (9) and the washing machine (1) are connected to each other. By doing so, vapor washing can be performed. The vapor cleaning has a rinse effect with few stains and has an advantage that the drying efficiency is fast because the solvent gas is warm.

[0030]

The method and apparatus of the present invention is an optimum system for the low boiling point solvent of the second generation Freon. Among alternative CFCs called second generation CFCs, H-22
5ca has a boiling point of 51.1 ° C, H-225cb has a boiling point of 5
Since it has a high boiling point at 6.1 ° C, a conventional apparatus may be used. However, HCF with a boiling point of 32 ° C, which holds promise in the future,
Second-generation CFCs such as C-141b, HCFC-123 with a boiling point of 27.5 ° C., and KCD-9450 with a boiling point of 29.2 ° C. have low boiling points, so that the amount of babers generated increases, and countermeasures against this are required. .

In the present invention, a third condenser is additionally installed,
During washing and drying, the third condenser and the washing machine circulate and condense to collect and then collect the activated carbon to reduce the load on the activated carbon, and purposely install a large capacity activated carbon tank. I didn't need it.

Further, in the present invention, chiller water is added to the second condenser as cooling so as to play a central role in the liquefaction and recovery of the distilled vapor gas, thereby reducing the amount of non-condensed gas in the apparatus. .

In the present invention, by utilizing the characteristics of the second-generation CFC, the dissolving power of the solvent is increased, the cleaning ability is improved, the cleaning and drying can be performed at a low temperature, and the process time can be shortened. It was possible to shorten the cleaning cycle and the tact treatment time compared with the vacuum and vacuum type.

The present invention makes the system closed,
When the lid of the cleaning tank is opened, it is of a closed type so that it can be automatically kept at a negative pressure. Since the generated vapor is adsorbed by activated carbon and recovered and reused, there is almost no solvent loss, and since the solvent gas does not leak into the room or the atmosphere, there is no fear of environmental pollution. A check valve is attached to the air tank in the system to adjust the internal pressure in the system.

Since the apparatus and cycle of the present invention are not built-in fixed ones, any cleaning method can be adopted, the cleaning machine can be downsized, and the cleaning can be carried out with a desired new distillation liquid. Yes, it is possible to systematize the changing and changing of the collection device according to the layout of the factory as appropriate, and the device is inexpensive in combination with the adoption of the centralized management system. If the distillation vapor is connected to a washing machine, it is possible to perform the vapor washing with the regenerated fresh liquid, prevent the generation of stains and accelerate the drying.

The method and apparatus of the present invention are used for cleaning electric equipment such as printed circuit boards, which are planned to be cleaned by the second-generation CFCs in the future, cleaning metal of automobile machinery, and precision optical equipment. It is a useful and widely used for cleaning

[Brief description of drawings]

FIG. 1 is a flow sheet of a closed-type solvent cleaning / collecting device according to an embodiment of the present invention.

FIG. 2 is a flow sheet showing the action of the third condenser of the present invention.

FIG. 3 is a flow sheet of a solvent cleaning and recovering device showing a conventional example.

[Explanation of symbols]

 1 Cleaning machine 1a Cleaning machine lid 3 Adsorption blower 7 Distillation can 9 Second condenser 11 Chiller water 12 First separator 13 Second separator 17 Third condenser 18 Air tank 22 First activated carbon tank 23 Second activated carbon tank 26 26th 1 condenser 27 Connection pipe for second condenser and washing machine

Claims (7)

[Claims] 1. In a closed solvent cleaning and recovery method using a low boiling solvent for cleaning, three condensers for liquefying and condensing a low boiling solvent gas are provided, and a direct cooling type first condenser is used to remove the activated carbon from the activated carbon. Desorption and treatment of distilled vapor gas with a chiller water type second condenser,
A closed solvent cleaning and collecting method, characterized in that a direct cooling type third condenser is systemized in advance to reduce the load of activated carbon. 2. The low boiling point solvent is 1.1-dichloro-1-
Fluoroethane, 2.2-dichloro-1.1.1-trifluoroethane, 1.1-dichloro-1-fluoroethane 35% and 2.2-dichloro-1.1.1-trifluoroethane 65% The method for solvent cleaning and recovery according to claim (1), characterized in that a low boiling point CFC alternative comprising a mixture of 3. The closed-type solvent cleaning and recovering method according to claim 1, wherein the activated carbon is configured so that the adsorption / desorption cycle can be varied in accordance with the cleaning cycle and the amount of the low boiling point solvent gas. 4. The closed-type solvent cleaning and recovery method according to claim 1, wherein the second condenser is connected to a cleaning machine so that vapor cleaning can be performed. 5. The closed solvent cleaning and recovering method according to claim 1, wherein an air tank is provided in the system so that the air in the system can be kept in balance. 6. The system is provided with an adsorption blower, which keeps a negative pressure in the system when the lid of the cleaning tank is opened so that the low boiling point solvent gas is not released to the outside. 1) The method for cleaning and recovering a closed solvent described in 1). 7. A purifier, a distillation can, an activated carbon tank,
In a closed solvent cleaning and recovering apparatus for low boiling point solvents, in which a condenser and, if necessary, a separator are systematized, the condenser comprises a direct cooling first condenser for desorption of activated carbon and a chiller for treating a distillation vapor gas. A closed solvent cleaning and recovering device comprising three water type second condensers and a direct cooling type third condenser for reducing the load of activated carbon.