JPS6133698A - Treatment of exhaust gas of dry cleaning - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for treating exhaust gas from dry cleaning equipment that uses organic solvents such as perchloroethylene, 1,1.1-)lychloroethane, and n1ia. be.

(Prior art) Conventionally, in this type of dry cleaning equipment, uncondensed exhaust solvent gas that could not be recovered by a condenser during the washing, deliquification, drying, and deodorizing processes is discharged to the outside of the dry cleaning equipment. After the solvent adhering to the drum is replaced with air to deodorize it, the drum door is opened to let in air in the same way as in the deodorizing process, and the items to be washed are taken out while deodorizing. In such conventional technology, a large amount of exhaust solvent gas flows out of the dry cleaning equipment during the deodorizing process and when the items to be washed are taken out, and the current situation is that activated carbon adsorption equipment or the like is used to recover this gas for treatment. However, the equipment costs and maintenance costs of such activated carbon adsorption equipment and related equipment (and also the outflow of solvents contained in the treated gas into the atmosphere) are expensive, and small-scale laundry companies are therefore reluctant to do so. There was a problem in that the exhaust solvent gas was not treated and was released into the atmosphere as it was, causing air pollution.

(Problems to be Solved by the Invention) In order to solve the problems of the prior art described above, the present invention was developed as a result of numerous studies and experiments. By recycling the solvent inside the dry cleaning equipment without processing it or emitting it to the outside, the amount of solvent used can be reduced, equipment and maintenance costs can be reduced, and air pollution caused by exhaust gas can be prevented. It is intended to be.

(Means for Solving the Problems) In order to achieve the above object, the present invention receives the exhaust gas generated in the cleaning drum into an exhaust gas tank, and uses a fan connected to the tank to move the inside of the cleaning drum and the condenser outlet. The parts are characterized in that they return exhaust solvent gas to these lower pressure parts when they are at a lower pressure than the other component parts.

In explaining the present invention in detail, first, the process of cleaning the object to be washed using a dry cleaning apparatus using conventional means will be explained based on FIG. 4: First, the object to be washed 3 is washed. Insert into drum 1. In this case, open the drum door 2, operate the fan 9, and operate the valve 1.
6 is opened to take in air and the inside of the cleaning drum 1 is replaced with air. Next, the drum door 2 is closed and the operation is started. The operation starts with a solvent injection step, in which the solvent 7 in the solvent storage tank 6 is sucked in by the pump 13 through the valve 20 and sent into the cleaning drum 1 through the filter 8. Next, the cleaning drum 1 is rotated at low speed to remove the solvent 7 from the button trap 5. Valve 20. A washing process is carried out in which the washing object 3 is washed by circulation through a circuit consisting of a pump 13 and a filter 8.

Next, the solvent inside the cleaning drum 1 is removed from the button trap 5.
．． After the solvent is drained into one tank 6 through the circuit of the valve 2o and the tank 6, the cleaning drum 1 is rotated at a high speed to perform a dewatering process in which the solvent adhering to the object 3 to be washed is centrifuged and deliquified. Further, after the above-mentioned washing and deliquoring steps are completed, the washing drum 1 is rotated at a low speed to perform a drying step. In this drying process, the cleaning drum 1. Fan 9. Capacitor 10. In the circuit of the heater 11, the fan 9 and the heater 11 evaporate and desorb the solvent attached to the object 3 to be washed, and the capacitor 1
The circulating solvent gas is liquefied by o, and the liquefied solvent is separated by a solvent/moisture separator 24 in a circuit 23 shown by a double dotted line and recovered in a tank 6. At the same time, the concentration of the circulating solvent gas gradually decreases with this liquefaction, and the internal temperature of the cleaning drum 1 increases due to the action of the heater 11, and when the inside of the cleaning drum 1 reaches a predetermined temperature, it dries. The process ends. - After the drying process, valve 16. Washing drum 1. Fan 9. In the deodorizing process circuit for the capacitor 10 and valve 19,
As described above, in the prior art, while air is taken in through the valve 16, the exhaust solvent gas that cannot be recovered by the condenser 10 is discharged to the outside through the activated carbon adsorption device 12 via the line 21.

After that, even when the object 3 to be washed is taken out and a new object 3 is put in, the floating solvent gas from the circuit such as the drying process flows into the inside of the washing drum 1, further contaminating the inside of the washing drum 1, and In order to impart a strong solvent odor to the items to be washed 3, the fan 9 is operated at the same time as the drum door 2 is opened, and while air is taken in from around the drum door 2, the washing drum 11 fan 9. The solvent odor inside the cleaning drum 1 is removed by the circuit of the capacitor io and the valve i9,
The discharged solvent gas is treated by an activated carbon adsorption device 12 and discharged to the outside. In such a conventional process, in addition to the deodorizing process, a large amount of exhaust solvent gas must be treated in the activated carbon treatment device 12 when the drum door 2 is opened to take out and put in the laundry 3.

However, the concentration of the treated gas at the outlet of the activated carbon treatment device 12 cannot be reduced to zero, and usually contains around 11,000 pp. This means that expensive gaseous solvents are unnecessarily released into the atmosphere. This results in expensive equipment costs and maintenance costs.

In the present invention, in order to eliminate the drawbacks of the prior art described above due to the discharge of the exhaust gas to the outside, the exhaust solvent gas from the deodorizing process is passed through a line 21 to an exhaust gas tank 26 as shown in FIG. Temporarily stored in. Thereafter, during most of the solvent injection, washing, drying, and deodorizing steps, the pressure inside the drum 1 or the discharge path of the condenser 10 in the apparatus is lower than that in other components of the apparatus. For example, when the internal pressure of the washing drum 1 is 100 mmA9. When this occurs, the stored gas in the exhaust gas tank 26 is transferred to these low pressure parts via a line 28 to a point a of the discharge path of the condenser 10 and/or to a point a of the circuit leading to the cleaning drum 1, as shown in FIG. 25, the dry cleaning device is automatically pressurized and supplied until the internal pressure of the dry cleaning device reaches the upper limit set value, and then, during operation, when the pressure drops to, for example, 200 mmAfP, the stored gas is automatically supplied from the exhaust gas tank 26. The solvent gas should be processed in a completely closed circuit so that it can be restarted in a timely manner.

As a modification of the method of the invention described above, instead of receiving the exhaust solvent gas from the line 21 into the exhaust gas tank 26, a compressor 30 with a pressure tank capable of sucking a large amount of exhaust solvent gas is used, as shown in FIG. from which it can be supplied to the low pressure part of the apparatus described above.

Furthermore, as shown in FIG. 3, the circulating gas from the fan 9 can be branched before the condenser 10, and a portion of the circulating gas can be bypassed from the condenser 10 by adjusting the appropriate amount with the valve 34.

(Example) As described above, an apparatus for carrying out the method of the present invention in which the exhaust solvent gas passage is configured as a completely closed circuit is used to conduct R as a solvent.
The dry cleaning exhaust gas treatment of the present invention was carried out as follows using a washing drum 113 with a washing capacity of 20 kg/one time: 1. First, the washing drum 1 was opened, except that the valve 16 was opened based on the first example. Valve around 4. Valve 18. Valve 14° Valve 15 continues to close and the inside of the washing drum 1 is replaced with air. The drum door 2 is opened and the object to be washed 3 is put into the washing drum 1. The drum door 2 is closed and the valve 16 is closed. I closed it and started driving. This process produces no exhaust gas.

The start of operation is a solvent injection process, in which the solvent 7 in the solvent tank 6 is poured into the valve 20. Pump 13. A predetermined amount was injected into the cleaning drum 1 through the filter 8° valve 18 circuit.

Next, the cleaning drum l is rotated at low speed and the valve 74 button trap 5. Valve 20. Pump 13. Filter 8. A cleaning process was carried out in which a solvent at about 20° C. was circulated through the washing drum 1 whose internal temperature was about 30° C. to wash the laundry items 3 through the circuit of the valve 1B.

In the above solvent injection process and cleaning process, liquid solvent and solvent gas are mixed in the cleaning drum 1, and the solvent gas zone is gasified to a saturation pressure commensurate with the temperature and pressure, that is, close to the saturation concentration, and the liquid solvent is During the gasification process, the temperature of the solvent gas zone decreases due to the large latent heat of vaporization peculiar to the solvent, which is accompanied by a pressure drop.

However, just about 30 seconds after the start of the solvent injection process, the internal pressure of the cleaning drum became less than about 200 mmA7. Under such circumstances, the dry cleaning apparatus based on the present invention sets the lower limit setting value of the contact pressure gauge 32 to 200 mm.
If the upper limit set value is 600 mm AfP, the valve 17 is opened at the lower limit set value and the fan 25 is turned on.
was operated, and the gas stored in the exhaust gas tank 26 was turned on until it reached the above-mentioned upper limit setting value, and then the gas was supplied to the cleaning drum 1 or directly to the cleaning drum 1.

Furthermore, when the upper limit setting value was reached, the valve 17 was closed and the fan 25 was stopped.

Based on the above-described operation, the test data that can be supplied to the cleaning drum 1 by turning on the stored gas in the exhaust gas tank 26 is as follows: Next, the solvent inside the cleaning drum 1 is pumped through the valve 4. Button trap 5. Valve 20. After the liquid is drained into the tank 6 through the circuit of the solvent storage tank 6, the cleaning drum 1 is rotated at high speed to remove the solvent adhering to the object 3 by centrifugation 9. Ta. Next, after the above-mentioned washing and liquid removal steps were completed, the washing drum 1 was rotated at a low speed to perform a drying step. In this drying process, the cleaning drum 1. Valve 14. fan 9
．． Capacitor 10. Heater 11. 7 am in the circuit of valve 15 9. The solvent adhering to the object 3 to be washed is evaporated and desorbed by the heater 11, and the circulating gas is cooled and liquefied by the condenser 10, and then collected in the solvent storage tank 6. At the same time, the temperature inside the cleaning drum 1 rose due to the action of the heater 11, and when it reached a predetermined temperature, for example, 45° C., the drying process was completed. That is, when the above-mentioned condenser 10 artificial gas passed through the condenser 10, the amount of gas decreased by the amount of the solvent used to cool and liquefy the log gas output from the condenser 10, and further the gas decreased in proportion to the temperature at which it was cooled.

Under these circumstances, when the lower limit set value of the contact pressure gauge 32 shown in FIG. 1 is reached, the valve 27 is opened and the fan 2
5 is operated, and the gas stored in the exhaust gas tank 26 is supplied from point a to the piping or the discharge path of the condenser 10 until it reaches the upper limit set value of the contact pressure gauge 32. When the upper limit set value was reached, the valve 27 was closed and the 7-ring 25 was stopped. Further, when the amount of gas stored in the exhaust gas tank 26 becomes zero, the indicated value of the contact pressure gauge 33 attached to the #P output tank 26 becomes Q mmA9. In the following, the fan 25. Valve 17° and valve 27 are interlocked.

The test data for supplying the gas stored in the exhaust gas tank 26 into the pipe from point a based on the above-described operation is as follows: Next, in the deodorizing process, the fan 9 is operated to take in air from the valve 16, and the cleaning drum 1 is ．． Valve 14° Fan 9. Capacitor 10. The solvent attached to the item 3 to be washed is replaced with air in the valve 19 circuit, and deodorized for about 1.5 minutes, and then the line 21
The deodorized gas in the cleaning drum 1 is temporarily stored in the exhaust gas tank 26 via the exhaust gas tank 26, and at the same time as the deodorization is completed, the valve 14° valve 19 is closed and the fan 9 is stopped. The laundry 3 was taken out and the drum door 2 was closed.

In the process from the deodorizing process to the removal of the object 3 to be washed and the introduction of a new object 3, exhaust gas to the line 21 is generated from deodorization to removal and insertion of the object 3, whereas in the conventional technology, gas is emitted from deodorization to removal of the object 3 and loading. In the present invention, after the deodorizing process, the cleaning drum 1
Valve near 4. Valve 14° Valve 15. Valve 17. Valve 18 By closing each valve, dry cleaning equipment piping,
Since the solvent remaining in the equipment is blocked from entering the cleaning drum 1 and the inside of the cleaning drum 1 is continuously maintained in a deodorized state, the exhaust gas in the line 21 is only generated during the deodorization process. Regarding the amount of exhaust gas, the amount of air required during the deodorizing process is as follows based on the operation described above in the prior art. However, regarding the degree of deodorization, the amount of solvent remaining in item 3 to be washed is
0.05 g per kg Therefore, the amount of stored gas that can be supplied from the line 28 during the above-mentioned solvent injection process, washing process, and drying process is more than 25 times the amount of air taken in from the valve 16 during the deodorizing process. We were able to achieve stable, completely closed-circuit processing of exhaust gas.

I was able to achieve this.

(Effects of the Invention) As described above, the present invention receives the exhaust gas generated in the cleaning drum into the exhaust gas tank, and uses a fan connected to this tank to separate the interior of the cleaning drum and the condenser outlet from other components. By configuring the exhaust solvent gas passage in a completely closed circuit so that the exhaust solvent gas is returned to these low pressure areas when the dry cleaning equipment is under low pressure, the exhaust gas is not discharged from the dry cleaning equipment to the outside, but can be stored inside the equipment. By recycling, we were able to reduce the amount of solvent used, reduce equipment costs and maintenance costs, and prevent air pollution caused by exhaust gas.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing each washing process circuit of a dry cleaning apparatus used to implement the dry cleaning exhaust gas treatment method of the present invention, and FIGS.
FIG. 4 is an explanatory diagram showing a partially modified process circuit in the figure, and FIG. 4 is an explanatory diagram showing each washing process circuit of a conventionally used dry cleaning apparatus. 1...Cleaning drum 2...
・Drum door 3... Items to be washed 4, 14.15.16.17.18.19.20.27
．． 34... Valve 5... Button trap
6... Solvent storage tank 7... Solvent 8... Filter 9.25...7 Anne 10... Capacitor 11...・
・Heater 12...Activated carbon adsorption device 13...Pump 21.28.
...Line 24...Solvent/moisture separator
26... Exhaust gas tank 30... Compression with pressure tank [32, 33... Pressure gauge with contact Figure 1

Claims (1)

[Claims] The exhaust solvent gas discharged from the washing drum for dry cleaning is received in an exhaust gas tank, and a fan connected to this tank is used to reduce the pressure inside the washing drum and the condenser outlet section when the pressure is lower than each component other than these parts. A dry cleaning exhaust gas treatment method characterized in that the exhaust solvent gas is returned to a dry cleaning exhaust gas.