JPH0796075B2 - Method for operating solvent gas recovery device using activated carbon - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a solvent gas recovery device in the dry cleaning industry, or an organic solvent, and a solvent after metal cleaning using a degreasing tank for degreasing metal or the like. The present invention relates to a method of operating a gas recovery device or the like.

(Prior Art) The adsorption recovery technology using activated carbon is known in various ways. For example, a solvent recovery apparatus when combined with a dry cleaner will be described with reference to FIGS. 3 and 4.

A dry cleaner using an organic solvent such as perchlorethylene, 1.1.1-trichloroethane, Freon R113 or the like is generally operated in the following steps. (Not shown) (1) Washing step Put clothes in the rotary drum of the dry cleaner and put detergent in an organic solvent for washing.

(2) Drainage and drainage process The washed clothes are spun at high speed to spin-dry.

(3) Drying process Hot air is blown to the solvent on the clothing to dry it. At this time, the solvent gas evaporated from the clothing is collected by the condenser.

(4) Deodorizing step For the solvent content that remains in the clothing slightly even after drying, the outside air is introduced to contact with the clothing and evaporate. That is, deodorization (deaeration)
I do.

In the deodorizing step of the above item (4), the evaporating solvent is released into the air to cause a solvent loss as well as air pollution. Therefore, this is adsorbed and recovered by activated carbon. Further, when the dry cleaner is operated in addition to these, the solvent gas expands with the temperature change in the dry cleaner, and this is discharged to the outside of the dry cleaner through the ventilation pipe.

A method of recovering the solvent gas by deodorizing and expanding the internal pressure will be described with reference to FIG.

In the figure, 1 is activated carbon, 2 is a tank containing activated carbon (activated carbon tank), and 7 and 8 are dampers attached to the outlet and inlet of the tank. 3 is a condenser, which usually has a function of cooling through water. A water separator 4 separates the solvent and water due to the difference in specific gravity. The part composed of these 2, 3 and 4 is the main constituent part of the recovery device. 5 is the main body of the dry cleaner, 6
Indicates the tank in the dry cleaner.

The solvent gas discharged in the deodorizing step of the dry cleaner main body 5 is discharged to the atmosphere from the outlet damper 7 through the conduit 11, the inlet damper 8 and the activated carbon 1. At this time, most of the solvent component of the solvent gas that has passed through the activated carbon is adsorbed by the activated carbon, and when leaving the activated carbon, it is usually 50 ppm or less. The adsorption capacity of activated carbon is proportional to the amount of activated carbon. It is possible to predict the number of times (deodorization number) that adsorption cannot be performed for a certain load. When activated carbon cannot be adsorbed, the desorption process (also called regeneration)
Then, the inlet and outlet dampers 7 and 8 of the activated carbon tank 1 are closed, and the valve 9 is opened to add steam. Due to this heat, the solvent content in the activated carbon is evaporated and reaches the condenser 3 via the conduit 12. In the condenser 3, the solvent gas and water vapor are cooled and condensed and liquefied. The liquefied solvent and water are separated into a solvent and water by a water separator 4. For example, perchlorethylene has a specific gravity
1.62, the water is 1, so perchlorethylene collects near the bottom and the water floats at the top. The solvent returns to the tank 6 of the dry cleaner body through the recovery pipe 10. Water is discharged outside the system as waste water.

Fig. 4 shows that the activated carbon tank (activated carbon tank) called the twin-body type is composed of two, and its function is the same as that shown in Fig. 3, but one activated carbon tank can be adsorbed. , The other will do desorption. Therefore, one side is always open. That is, when the activated carbon tank 1a is in the adsorption state, the inlet / outlet dampers 7a and 8a are opened, and when the dry cleaner is deodorized, the solvent gas flows from the inlet damper 8a → the activated carbon 1a → the outlet damper 7a and is exhausted. In the other activated carbon tank, the inlet and outlet dampers 7b and 8b are closed, and steam is blown from the valve 9b for desorption. FIG. 5 is a chart showing the operation of the dry cleaner and these activated carbons.

In the case shown in FIG. 3, activated carbon is adsorbed, desorbed and dried in a single activated carbon tank during one step of the dry cleaner. In the case shown in FIG. 4, one of the activated carbons only adsorbs in all the steps of the dry cleaner, and the other activated carbon desorbs and dries the activated carbons to prepare for the next adsorption. That is, in the case shown in FIG. 4, when deodorizing the dry cleaner, the activated carbon side is in the adsorption state and the side is in the activated carbon dry state.

(Problems to be Solved by the Invention) The amount of activated carbon in the activated carbon tank is determined by the balance between the adsorption capacity of activated carbon and the solvent load. For example, the adsorption capacity of activated carbon is 20% of the weight of activated carbon in the case of perchlorethylene.
The degree is acceptable. On the other hand, the adsorption capacity of activated carbon is determined as a range in which the linear velocity of passage in the activated carbon tank does not move (a range in which floating does not occur) due to the activated carbon weight and wind speed, for example, about 0.4 m / sec. That is, if the air volume is constant, the cross-sectional area of the activated carbon tank is determined by the linear velocity. Further, the apparent contact time between the activated carbon and the solvent gas is about 1 second as a standard value. In this way, the cross-sectional area and height are determined by the air volume, and the amount of activated carbon is determined.

Emission of solvent gas from the dry cleaner varies depending on the capacity of the dry cleaner, but is generally 3.2% based on the weight of the clothing. Therefore, the amount of solvent gas discharged by the 10 kg / batch dry cleaner during deodorization is approximately 10 × 0.032 = 0.32 kg.
On the other hand, the air volume when deodorizing the dry cleaner is 0.5 m ³ / kg clothing /
Minutes are normal. Therefore, in the case of a dry cleaner of 10 kg / batch, it will be deodorized with an air volume of 5 m ³ / min.

When determining the amount of activated carbon for solvent load, 0.32 kg is discharged in the case of 10 kg / batch dry cleaner, and the adsorption capacity is 20% of the weight of activated carbon, so the amount of activated carbon is 1.6 kg.
Will be good. However, if the amount of activated carbon is determined from the limitation by the air volume, Q = Av (Q = air volume, A = cross-sectional area, v = linear velocity) Then, if the contact time is 1 second, the layer height becomes 0.4 m and the volume is 0.
It becomes 208 × 0.4 = 0.083m ³ . Apparent specific gravity of activated carbon is about 0.4 kg
Therefore, 0.083m ³ × 1000 / m ³ × 0.4kg / = 33.2k
g of activated carbon is required. From the above, it is the passing wind velocity of the activated carbon that determines the amount of activated carbon in the activated carbon adsorption method of the dry cleaner, and the device thus determined has too much adsorption load. The maximum air volume and load are required during deodorization of the dry cleaner, and the conventional recovery device has a single activated carbon tank as the activated carbon passage during deodorization. Therefore, the amount of activated carbon in one of the twin-body type shown in FIG. 4 is in sync with the amount of activated carbon in FIG. That is, the apparatus shown in FIG. 4 requires twice as much activated carbon as the apparatus shown in FIG.

Since the system shown in FIG. 3 has only one activated carbon tank, the activated carbon inlet and outlet and the damper are closed during desorption. For this reason, the dry cleaner and the atmosphere are closed, and the volume expansion due to the temperature change of the dry cleaner cannot pass through the activated carbon, so it is discharged to the outside of the device from the drain of the dry cleaner, etc. Alternatively, the internal pressure of the dry cleaner becomes high, which causes an abnormality in the device. On the other hand, in the system shown in FIG. 4, during desorption, one activated carbon is always open to the atmosphere, so that the volume expansion can be absorbed. The volume expansion amount is about 1/10 of the gas concentration and the air volume when deodorizing.

As shown above, the amount of activated carbon in the single-cylinder type is half that in the double-cylinder type, but it has the drawback that it cannot absorb the internal pressure expansion. On the other hand, the twin cylinder type requires twice as much activated carbon as the single cylinder type.

The present invention has been made for the purpose of solving these drawbacks at the same time, and the amount of activated carbon used is the same as that of the single-cylinder type, and at the same time, one of the activated carbon tanks is always open, and the advantage of the double-drum type is utilized. It is to provide a method of operating a solvent gas recovery device.

(Means and Actions for Solving the Problem) Therefore, the present invention divides the activated carbon into two tanks, and when the activated carbon in one tank is in an adsorbed state, desorption of the activated carbon in another tank and drying of the activated carbon are performed. In the recovery device, the method for operating the recovery device of the solvent gas by the activated carbon is adopted, in which the activated carbon in both tanks is placed in an adsorbed state with respect to the solvent gas sent from the device that generates the solvent gas. This is a means for solving the problem.

A case where this is adopted in a solvent gas recovery device in a dry cleaner will be described.

(1) The activated carbon tank is configured as a twin-body type, and in the deodorizing process in which the exhaust air volume of the dry cleaner is maximized, the two activated carbon tanks are simultaneously adsorbed.

(2) In steps other than the deodorizing step of the dry cleaner, one of the activated carbon tanks is similarly operated as an adsorption step, and the other activated carbon tank is operated as a deodorizing step of activated carbon and an activated carbon drying step.

(3) Therefore, since the maximum air volume is handled by two activated carbon tanks, the twin cylinder type requires the same amount of activated carbon as the single-cylinder type, which is half the conventional activated carbon volume. It becomes a device.

(Example) Hereinafter, a typical example when the present invention is applied to a dry cleaner will be described with reference to the drawings. FIG. 1 shows a schematic structure of a solvent recovery device incorporated in a dry cleaner for carrying out the method of the present invention. The components in FIG. 1 are basically the same as those of the conventional twin barrel type solvent recovery device shown in FIG. Is the same. Therefore, the present invention can be implemented even with the device shown in FIG. The difference between FIG. 1 and FIG. 4 is that the former is an example in which two activated carbon tanks are integrated, and the latter is an example in which the activated carbon tank is divided into two tanks. May have any configuration. However, in the case of the present invention, two activated carbon tanks 2a, 2 are used in the deodorizing process of the dry cleaner.
All of the entrance / exit dampers 7a, 7b, 8a, 8b leading to b are controlled to open. Therefore, in the deodorizing step of the dry cleaner, the solvent gas flows to the activated carbon tank through the conduit 11a,
Since the inlet / outlet dampers 7a, 7b, 8a, 8b of the two activated carbon tanks 2a, 2b are all open, almost the same amount of solvent is adsorbed by both activated carbons and low concentration The generated solvent gas is discharged to the outside via the exhaust pipe 13.

When all the steps of the dry cleaner are completed and the next cleaning step is started, one activated carbon tank 2a enters the desorption step. Therefore, the inlet / outlet dampers 7a, 8a of the activated carbon tank 2a are closed, steam is introduced from the valve 9a, and the solvent adsorbed on the activated carbon 1a by heat evaporates and passes through the check valve 15a (which may be an automatic valve). , Conduit 12a
Sent to the condenser via. 15b is also a check valve (it may be an automatic valve) so that the desorbed vapor on the side of the activated carbon container 2a does not flow into the other activated carbon container 2b side. At this time, since the inlet / outlet dampers 7b, 8b of the other activated carbon tank 2b remain open, even if the internal pressure rises due to the volume expansion of the internal gas due to the temperature change on the dry cleaner side, it passes through the conduit 11a. Then, it is exhausted to the outside through the exhaust pipe 13 through the inlet damper 8b → the activated carbon 1b → the outlet damper 7b. Therefore, the open state to the atmosphere is always present in either one of the sides, so that an abnormality in the device can be prevented.

The above operation is shown in the flow chart of FIG.

In the present embodiment, switching between the two activated carbon tanks 2a and 2b is described for each step of the dry cleaner. However, the switching timing is changed depending on the amount of activated carbon and the load (capacity on the dry cleaner side). It is possible to
It is also effective in running cost. Although the description of the activated carbon drying step is omitted in the description of the present embodiment, the same step is an operation of recovering the adsorption capacity of the activated carbon by exhausting and drying the moisture in the activated carbon by the outside air after desorption of the activated carbon. Further, in the present description, it is sufficient to adopt a known technique for the specific structure and method, and therefore the description thereof is omitted. In addition, in the device shown in Fig. 1, it is expected that the activated carbons that are separated by partitions will have a thermal effect on the adjacent activated carbons due to heat conduction during desorption of one activated carbon. It is well known that it is difficult to put on and take off, so there is no practical problem.

(Effects of the Invention) As described in detail above, according to the present invention, the following excellent effects are obtained.

(1) The initial cost can be reduced because the amount of activated carbon can be configured to be half that of the conventional twin-body type device.

(2) The device can be compactly integrated.

(3) Since one activated carbon tank is always open, it can handle deodorizing loads of multiple dry cleaners.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a solvent gas recovery apparatus for carrying out the present invention, FIG. 2 is a process diagram when the present invention is applied to a dry cleaner, and FIG. 3 is a conventional single-body type solvent gas. FIG. 4 is a schematic configuration diagram of a recovery device, FIG. 4 is a schematic configuration diagram of a conventional twin-body type solvent gas recovery device, and FIG. 5 is a process diagram of a conventional dry cleaner and a single-body type and double-body type solvent gas recovery device. Is. Explanation of the main parts of the figure 1a, 1b ...... Activated carbon 2a, 2b ...... Activated carbon tank 7a, 7b ...... Outlet damper 8a, 8b …… Inlet damper 9a, 9b …… Desorption steam inlet valve 15a, 15b …… Check valve

Claims (1)

[Claims] 1. A solvent gas recovery device for dividing activated carbon into two tanks and desorbing activated carbon from another tank and drying activated carbon when the activated carbon in one tank is in an adsorbed state. A method for operating a solvent gas recovery device using activated carbon, characterized in that both activated carbon in both tanks are placed in an adsorbed state with respect to the incoming solvent gas.