JPH1133301A - Organic solvent recovery device and method for operating the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the high recovery rate of a solvent in a short recovery time by forming a closed recovery circulatory channel with the downstream side, of a vacuum pump and a secondary condenser connected in series, which is connected with the downstream side of an evaporator. SOLUTION: First, a first valve 11 is closed and a second valve 13 is opened to form an exhaust flow passage and further, a vacuum pump 10 is activated to create a negative pressure in the exhaust flow passage. Further, the first valve 11 is opened and the second valve 13 is closed resulting in the formation of a closed recovery flow path. Next, after immersing a nasflask 22 in a water bath 21, a solvent recovery operation is initiated. An organic solvent is cooled by a primary condenser 23 and is recovered by a flask 24. In addition, a solvent gas which is not yet recovered is cooled by a secondary condenser 30 to be liquefied and the liquefied solvent gas is recovered by a flask 31. After that, part of the solvent gas which is not captured by the secondary condenser 30 is again captured by the secondary condenser 30, whilst the remaining solvent gas circulates through the closed recovery flow path to be again captured by the secondary condenser 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an organic solvent recovery apparatus,
In particular, the present invention relates to an organic solvent recovery device having a closed recovery channel using a vacuum pump in a laboratory or the like.

[0002]

2. Description of the Related Art In recent years, according to an aspirator using tap water, there is a possibility that a solvent may be dissolved in tap water and a river may be polluted. Therefore, an organic solvent recovery device using a vacuum pump has been proposed. Conventionally, as an organic solvent recovery apparatus using a vacuum pump, for example, as shown in FIG. 7, a rotary evaporator 2 is arranged upstream of a vacuum pump 1 and a secondary condenser 3 is arranged downstream thereof. Something was done.

That is, the organic solvent placed in the eggplant flask 4 of the rotary evaporator 2 is kept in a water bath 5 having a relatively high vapor pressure and a boiling point of the solvent or lower. The cooling pipe 6a in the primary condenser 6 to which the eggplant flask 4 is attached is connected to a circulating cooler 7, and is cooled by cooling water or a refrigerant. For this reason, when the inside of the primary condenser 6 becomes negative pressure by the vacuum pump 1, the evaporation of the solvent is promoted, and the primary condenser 6
And liquefied, and collected and collected in the flask 8.
Then, the solvent gas that could not be captured by the primary condenser 6 is captured again by the secondary condenser 3 located on the downstream side of the vacuum pump 1 and collected in the flask 9.

[0004]

However, according to the organic solvent recovery apparatus described above, the exhaust port 3 of the secondary condenser 3
Since a was open to the atmosphere, solvent gas that could not be captured was discharged, causing indoor pollution. For this reason,
In order to increase the recovery rate of the solvent, the cooling temperature must be lowered, and the speed of passing the solvent gas through the condenser must be reduced, which increases the recovery time. As a result, if the recovery time is to be shortened, the recovery rate will be reduced, and if the recovery rate is to be increased, the recovery time will be prolonged.

[0005] In particular, it is impossible to trap a solvent having a saturated vapor pressure equal to the temperature of the condenser, and it is inevitable that the solvent diffuses into the air during the recovery operation and pollutes the room. For example, in the case of dichloromethane (methylene chloride), which is an organic solvent having a low boiling point, even if the temperature can be completely cooled to 0 ° C., a saturated vapor pressure of about 170 mbar remains, and the solvent corresponding to this vapor pressure is constantly recovered. There is a problem that it diffuses into the room and pollutes the room.

For example, a width of 5 m, a depth of 8 m, a height of 3 m,
500 g of dichloromethane in a laboratory at room temperature of 20 ° C.
If 3% of them leaked indoors, the weight of the leak would be 1
It becomes 5 g. Since dichloromethane has a molecular weight of 84.9, 4247 cc of dichloromethane diffuses into the room. For this reason, the concentration of dichloromethane in the laboratory becomes 35.4 ppm. Generally, many evaporators are installed in a laboratory. As a result, there is a possibility that the concentration may exceed the management concentration of the Industrial Safety and Health Law.

[0007] In view of the above problems, an object of the present invention is to provide an organic solvent recovery apparatus capable of realizing an extremely high recovery rate in a short recovery time and an operation method thereof at a low cost.

[0008]

In order to achieve the above object, an organic solvent recovery apparatus according to the present invention comprises a vacuum pump and a secondary condenser connected in series downstream of at least one evaporator. In the organic solvent recovery device described above, a downstream side of the vacuum pump and the secondary condenser connected in series is connected to a downstream side of the evaporator to form a closed recovery channel.

Further, a throttle valve may be arranged between the downstream side of the vacuum pump and the secondary condenser connected in series and the downstream side of the evaporator. Further, a vacuum gauge may be connected between the throttle valve and the evaporator.

[0010] The organic solvent recovery device gasifies and recovers the organic solvent in a primary condenser of at least one evaporator, and then uses a vacuum pump to remove the unrecovered solvent gas in a secondary condenser. After the recovery, the remaining unrecovered solvent gas can be circulated using the closed recovery channel, and the operation can be performed so as to be recovered again by the secondary condenser.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of an organic solvent recovery apparatus according to the present invention will be described with reference to the accompanying drawings of FIGS. Note that, for convenience of explanation, the flow path of the refrigerant is omitted. In the first embodiment, as shown in FIG. 1, a rotary evaporator 20 is connected to an upstream side of a vacuum pump 10, while a secondary condenser 30 is connected to a downstream side thereof. The downstream side of the condenser 30 is connected to the downstream side of the rotary evaporator 20 to form a closed recovery passage.

The rotary evaporator 20 is the same as the conventional example, and an eggplant flask 22 heated by a water bath 21 is attached to a primary condenser 23. The primary condenser 23 is provided with a flask 24 for collecting a liquefied solvent.

A first valve 11 is disposed between the vacuum pump 10 and the secondary condenser 30. A second valve 13 connected to the exhaust trap 12 is connected between the first valve 11 and the vacuum pump 10. The downstream side of the secondary condenser 30 is also connected to the exhaust trap 12 via a relief valve 14. Further, a vacuum path is provided between the exhaust side of the secondary condenser 30 and the downstream side of the rotary evaporator 20.
A pressure kneader 15, a throttle valve 16, and a vacuum gauge 17 are sequentially mounted.

Next, an operation method of the above-mentioned organic solvent recovery apparatus will be described. First, rotary evaporator 2
The eggplant flask 22 of 0 is not immersed in the water bath 21. In order to remove the air in the closed recovery passage and the saturated vapor pressure gas of the solvent at room temperature, the first
The valve 11 is closed, the second valve 13 is opened to form an exhaust passage, and the vacuum pump 10 is operated to make the inside of the passage negative pressure. The vacuum value in this case is determined in consideration of various conditions such as the boiling point of the solvent.

Then, the first valve 11 is opened and the second valve 13 is closed to form a closed system recovery flow path. Next, after immersing the eggplant flask 22 in the water bath 21, the outlet of the evaporator 20 is set to an appropriate vacuum value by the throttle valve 16, and the solvent recovery operation is started. The organic solvent warmed appropriately in the water bath 21 is gasified by the vacuum pump 10, cooled and liquefied in the primary condenser 23, and collected in the flask 24.

Further, the solvent gas not recovered in the primary condenser 23 is sent to the secondary condenser 30 by the vacuum pump 10, cooled and liquefied, and recovered in the flask 31. Then, the vapor pressure of the gas not captured by the secondary condenser increases with time, and a part of the gas is captured again by the secondary condenser 30, while the remaining gas is collected by the throttle valve 1.
6, circulates through the closed recovery passage of the vacuum pump 10 and is captured again by the secondary condenser 30.

The completion of the recovery operation is confirmed by visually checking the presence or absence of the organic solvent in the eggplant flask 22 or by checking the increase in the vacuum value of the vacuum gauge 17.

After the completion of the recovery operation, the first valve 11 is closed and the second valve 13 is opened to form an exhaust passage. After the solvent gas remaining in the flow path is removed by the exhaust trap 12, a leak valve (not shown) of the rotary evaporator 20 is opened to bring the pressure in the flow path to atmospheric pressure, and the vacuum pump 10
To stop.

As shown in FIG. 2, the second embodiment differs from the first embodiment in that the first and second valves 11, 13 are arranged downstream of the secondary condenser 30. Is the same as According to the present embodiment, there is an advantage that when evacuation is performed via the secondary condenser at the initial stage of the operation, the amount of the solvent gas flowing out to the exhaust trap 12 is reduced, and the recovery rate of the organic solvent is improved.

In the third embodiment, as shown in FIG. 3, two rotary evaporators 20 are connected to a vacuum pump 1.
Except for the point that it is connected to the upstream side of 0, the rest is the same as the above-described second embodiment. According to the present embodiment, when recovering a heterogeneous solvent, the bath temperature can be set according to the boiling point of the solvent. For this reason, there is an advantage that adjustment of the time balance in the recovery of the heterogeneous solvent is facilitated.

The fourth embodiment is the same as the above-described second embodiment except that a secondary condenser 30 is disposed upstream of the vacuum pump 10 as shown in FIG. According to the present embodiment, for example, even if the evaporator 20 leaks and air enters the recovery flow path, the throttle valve 16 is appropriately adjusted to make the pressure downstream of the vacuum pump 10 substantially equal to the atmospheric pressure. By doing so, gas can be vented through the relief valve 14. Therefore, there is an advantage that the degree of vacuum at the outlet of the evaporator 20 can be kept constant, and stable recovery can be maintained.

[0022]

【Example】

(Example 1) A performance test of chloroform and dichloromethane recovery was performed by the closed organic solvent recovery apparatus shown in the first embodiment. The test results are shown in FIG. As is clear from FIG. 5, according to the present example, it was found that the organic solvent could be almost completely recovered.

(Example 2) A performance test was conducted by collecting 409 g of dichloromethane at a vacuum value of 426 mbar, a bath temperature of 35 ° C, and a refrigerant temperature of + 1 ° C using the closed organic solvent recovery apparatus described in the second embodiment. The test results are shown in FIG.

(Comparative Example 1) 409 g of dichloromethane was evacuated to a vacuum value of 3 by the open system organic solvent recovery apparatus shown in the conventional example.
A performance test was carried out by recovering at 40 mbar, a bath temperature of 35 ° C. and a refrigerant temperature of + 1 ° C. The test results are shown in FIG.

As is clear from the test results of Example 2 and Comparative Example 1 shown in FIGS. 6A and 6B, according to Example 2, it is clear that the organic solvent can be almost completely recovered. Was.

(Example 3) A performance test was conducted by recovering 404 g of chloroform at a vacuum value of 280 mbar, a bath temperature of 55 ° C, and a refrigerant temperature of 0 ° C using the closed organic solvent recovery apparatus described in the second embodiment. The test results are shown in FIG.

(Comparative Example 2) 408 g of chloroform was applied with a vacuum value of 19 using the open system organic solvent recovery apparatus shown in the conventional example.
A performance test was conducted by collecting at 0 mbar, a bath temperature of 50 ° C (first time), 45 ° C (second time), and a refrigerant temperature of -1 ° C. The test results are shown in FIG.

As is apparent from the test results of Example 3 and Comparative Example 2 shown in FIGS. 6C and 6D, it was found that the organic solvent could be almost completely recovered according to Example 3.

[0029]

As is apparent from the above description, according to the organic solvent recovery apparatus of the present invention, the flow path of the solvent gas is a closed recovery flow path. For this reason, almost complete recovery becomes possible, and the indoor contamination of the solvent gas can be completely prevented. Further, the recovery rate becomes constant regardless of the speed at which the organic solvent gas passes through the condenser. For this reason, the solvent can be recovered at a high degree of vacuum within a range that does not cause bumping of the solvent, and the recovery time can be significantly reduced.

According to the second aspect, the degree of vacuum at the outlet of the evaporator is adjusted by the throttle valve, so that the amount of solvent discharged during recovery can be suppressed. Therefore, the recovery time can be adjusted by adjusting the degree of vacuum, which is convenient. According to the third aspect, when the collection is completed, the meter of the vacuum gauge is displaced to the high vacuum side, so that the completion of the collection can be easily and reliably confirmed.

According to the fourth aspect, the organic solvent is circulated and collected by reducing the pressure in the closed recovery channel with a vacuum pump to a negative pressure.
Therefore, not only is the recovery rate of the organic solvent improved, but even if a leak occurs during the recovery, the pressure in the recovery channel is negative,
There is an effect that the solvent gas does not leak into the atmosphere and the room is not polluted.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a first embodiment of an organic solvent recovery device according to the present invention.

FIG. 2 is a schematic view showing a second embodiment of the organic solvent recovery device according to the present invention.

FIG. 3 is a schematic view showing a third embodiment of the organic solvent recovery device according to the present invention.

FIG. 4 is a schematic view showing a fourth embodiment of the organic solvent recovery device according to the present invention.

FIG. 5 is a table showing performance test results of the organic solvent recovery device according to the present invention.

FIG. 6 is a table showing performance test results of the organic solvent recovery device according to the present invention.

FIG. 7 is a schematic diagram showing an organic solvent recovery device according to a conventional example.

[Explanation of symbols]

10 vacuum pump, 16 throttle valve, 17 vacuum gauge, 20
... Rotary evaporator, 21 ... Water bath, 2
2: eggplant flask, 23: primary condenser, 24: flask, 30: secondary condenser, 31: flask.

Claims (4)

[Claims] 1. An organic solvent recovery device having a vacuum pump and a secondary condenser connected in series on a downstream side of at least one evaporator, wherein the vacuum pump and the secondary condenser are connected in series. An organic solvent recovery device, wherein a closed system recovery flow path is formed by connecting a side of the organic solvent recovery device to a downstream side of the evaporator. 2. The organic solvent recovery according to claim 1, wherein a throttle valve is arranged between a downstream side of the vacuum pump and the secondary condenser connected in series and a downstream side of the evaporator. apparatus. 3. A vacuum gauge is connected between the throttle valve and the evaporator.
Organic solvent recovery device according to 1. 4. The first of at least one evaporator
The organic solvent is gasified and recovered in the secondary condenser, and the unrecovered solvent gas is recovered in the secondary condenser using a vacuum pump. The method for operating an organic solvent recovery apparatus, wherein the organic solvent is recovered using the secondary condenser and circulated again using the secondary condenser.