KR20210045421A - Organic solvent recovery system - Google Patents

Abstract

The organic solvent recovery system of the present invention comprises a circulation path of a carrier gas, an adsorption and desorption treatment device that alternately performs adsorption of an organic solvent by introduction of a target gas and desorption of an organic solvent by introduction of a carrier gas, and adsorption and desorption. A condensation recovery device for condensing and recovering the organic solvent by cooling the carrier gas discharged from the treatment device, and a heating unit provided on the upstream side of the adsorption and desorption treatment device for heating the low-temperature carrier gas discharged from the condensation recovery device. In addition, the condensation recovery device has a melting portion that temporarily heats and melts the component frozen by cooling. Accordingly, while the running cost can be suppressed, the purification capability of the gas to be treated and the recovery efficiency of the organic solvent can be improved, and the system configuration can be further simplified and downsized.

Description

Organic solvent recovery system

The present invention relates to an organic solvent recovery system for separating an organic solvent from a gas to be treated containing an organic solvent, and recovering the separated organic solvent using a carrier gas.

Conventionally, an adsorption treatment and desorption treatment of an organic solvent is performed using an adsorbent on a target gas containing an organic solvent, and the organic solvent is transferred from the target gas to a carrier gas, thereby purifying the target gas and recovering the organic solvent. Gas treatment systems containing organic solvents that have made possible are known.

In general, this kind of organic solvent recovery system includes an adsorption and desorption treatment device in which a target gas containing an organic solvent and a carrier gas in a high temperature state come into contact with an adsorbent alternately with time, and the adsorption and desorption treatment device discharged from the adsorption and desorption treatment device A condensation recovery device is provided for condensing and recovering the organic solvent by cooling the carrier gas.

As one of such organic solvent recovery systems, Patent Document 1 discloses an organic solvent-containing gas treatment system using water vapor as a carrier gas.

In addition, in recent years, a low-drainage organic solvent recovery system for the purpose of improving the quality of the recovered organic solvent and simplifying the wastewater treatment process is desired, and Patent Document 2 discloses an organic solvent using an inert gas heated to a high temperature as a carrier gas. A recovery system is disclosed. Further, Patent Document 3 discloses an organic solvent recovery system in which an inert gas heated to a high temperature is used as a carrier gas, and an inert gas is circulated and used in the organic solvent recovery system, thereby reducing the amount of inert gas used.

Japanese Published Utility Model Gazette 「Practical Review 3-32924」 Japanese Unexamined Patent Application Publication No. Hei 7-68127 Japanese Patent Publication "Patent No. 5482776"

In such an organic solvent recovery system, in order to improve the purification ability for the gas to be treated and the recovery efficiency of the organic solvent, it is necessary to sufficiently perform desorption of the organic solvent in the desorption treatment, that is, regeneration of the adsorbent.

In addition, in order to suppress the running cost of the organic solvent recovery system, it is preferable to configure the used carrier gas to be recycled and reused in the organic solvent recovery system.

However, it is difficult to completely separate the organic solvent from the carrier gas in the condensation recovery device. Therefore, the uncondensed organic solvent is contained in the carrier gas discharged from the condensation recovery device. Therefore, in the case of a configuration in which the carrier gas is circulated and returned to the adsorption and desorption treatment apparatus, the regeneration of the adsorbent becomes insufficient, and there is a problem that the improvement of the purification ability for the target gas and the recovery efficiency of the organic solvent naturally occurs. there was.

By the way, in Patent Document 3, by providing a second adsorption and desorption element for adsorbing and removing the organic solvent from the carrier gas containing the uncondensed organic solvent discharged from the condensation recovery device, the purification ability for the gas to be treated and the recovery of the organic solvent It is improving efficiency. However, a second adsorption and desorption treatment device filled with the second adsorption and desorption element, or a means for bringing the carrier gas to a high temperature in order to desorb the organic solvent from the second adsorption and desorption element, etc., may be provided on the circulation path of the carrier gas. It is necessary, and there is a problem in that the configuration of the organic solvent recovery system is complicated and enlarged.

Thus, the present invention is made to solve the above-described problems, and while being able to suppress the running cost, it is possible to improve the purification ability of the target gas and the recovery efficiency of the organic solvent, and also simplify the system configuration and It is an object of the present invention to provide a system for recovering organic solvents that have been miniaturized.

As a result of intensive examination, the inventors of the present invention have found that the above problems can be solved by the means shown below, and have reached the present invention. That is, the present invention has the following configuration.

1. An organic solvent recovery system for separating and recovering an organic solvent from a gas to be treated containing an organic solvent, a circulation path through which a carrier gas circulates, and provided on the circulation path, having an adsorption and desorption element, and the treatment target An adsorption and desorption treatment device alternately performing adsorption of the organic solvent by introduction of gas and desorption of the organic solvent by introduction of the carrier gas, and is provided on the circulation path on a downstream side of the adsorption and desorption treatment device, A condensation recovery device having a cooling unit for cooling the carrier gas discharged from the adsorption and desorption treatment device, condensing the organic solvent in the carrier gas by the cooling and recovering it as a condensate, and the adsorption and desorption treatment device on the circulation path. It is provided on the upstream side and has a heating unit for heating the carrier gas in a low temperature state discharged from the condensation recovery device, and the condensation recovery device has a melting unit that temporarily heats and melts the component frozen by the cooling. Organic solvent recovery system, characterized in that. According to the above configuration, since the component frozen by cooling by the melting unit is temporarily heated and melted, the problem of gas flow due to adhesion of the frozen component can be solved. For this reason, the carrier gas can be cooled at a lower temperature than in the conventional system, so that the efficiency of condensation and recovery of the organic solvent can be improved. In addition, by this, the concentration of the organic solvent in the carrier gas discharged from the condensation recovery device can be reduced, and the desorption efficiency by the carrier gas in the adsorption treatment device is increased. There is no need to provide a desorption treatment device. As a result, while the running cost can be reduced, the purifying ability of the gas to be treated and the recovery efficiency of the organic solvent can be improved, and further simplification and miniaturization of the system configuration can be achieved.

2. The condensation recovery device has a refrigerant heat medium supply part for selectively supplying a refrigerant and a heat medium, and the cooling part and the fusion part are configured in the same manner as a cooling and fusion part, and the cooling and melting part receives a refrigerant from the refrigerant heat medium supply part. The organic solvent recovery system according to the above 1, characterized in that it receives supplied and functions as the cooling unit, and receives the fruit from the refrigerant fruit supply unit and functions as the melting unit. According to the above configuration, since the frozen component can be efficiently heated by temporarily supplying the fruit to the cooling and melting unit serving as a cooling source, the frozen component can be melted in a short time.

3. The condensation recovery device has a static pressure difference measuring unit for measuring a difference between the inlet side and the outlet side of the carrier gas of the static pressure, the refrigerant heat medium supply unit, wherein the difference in the static pressure measured by the static pressure measuring unit is a predetermined value. If exceeded, the organic solvent recovery system according to 2 above, characterized in that the supply of the fruit is selected. According to the above configuration, the problem of gas flow due to adhesion of the frozen component can be detected by the measurement result of the static pressure difference measuring unit, and the frozen component can be automatically heated and melted by switching to heat transfer.

4. A vapor pressure measuring unit for measuring the vapor pressure of the organic solvent contained in the carrier gas discharged from the condensation and recovery device is provided, and the temperature of the cooling unit is adjusted so that the vapor pressure of the organic solvent measured by the vapor pressure measuring unit is equal to or less than a predetermined value. The organic solvent recovery system according to any one of the above 1 to 3, characterized in that it has a temperature control unit. According to the above configuration, by adjusting the temperature of the cooling unit, the concentration of the organic solvent in the discharged carrier gas can be reduced to a certain level, and the organic solvent adsorbed on the adsorption and desorption element can be efficiently desorbed.

5. The organic solvent recovery system according to any one of 1 to 4 above, wherein a carrier gas is not supplied to the condensation recovery device during the melting by the melting unit. According to the above configuration, it is possible to prevent the concentration of the organic solvent in the carrier gas discharged from the condensation recovery device from becoming more than a certain level, and to efficiently desorb the organic solvent adsorbed on the adsorption and desorption element.

6. The adsorption and desorption treatment apparatus, after the adsorption and before the desorption, performs a purge treatment on the adsorption and desorption element, and the fusion unit performs the fusion during the purge treatment period. The organic solvent recovery system according to any one of 5. According to the above configuration, by performing the melting during the purge treatment period, the process of adsorption and desorption is not temporarily stopped and there is no melting, so that the system can be efficiently operated.

According to the present invention, since the component frozen by cooling is temporarily heated and melted by providing a melting portion in the organic solvent recovery system, the problem of gas flow due to adhesion of the frozen component can be solved. For this reason, it is possible to cool the carrier gas at a lower temperature than in the conventional system, and thus the efficiency of condensation and recovery of the organic solvent can be improved. In addition, by this, the concentration of the organic solvent in the carrier gas discharged from the condensation recovery device can be reduced, and the desorption efficiency by the carrier gas in the adsorption treatment device is increased. There is no need to provide a desorption treatment device. As a result, while the running cost can be reduced, the purification ability of the gas to be treated and the recovery efficiency of the organic solvent can be improved, and further simplification and miniaturization of the system configuration can be achieved.

1 is a diagram showing a structure of an organic solvent recovery system according to an embodiment.
[Fig. 2] Fig. 2 is a diagram showing a time chart showing a temporal conversion of an adsorption treatment and a desorption treatment using a pair of adsorption and desorption elements in the organic solvent recovery system according to the embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in the embodiment shown below, the same reference|symbol is attached|subjected to the same or common part in drawings, and the description is not repeated.

As shown in Fig. 1, the organic solvent recovery system 100A according to the present embodiment includes a circulation path L1 through which a carrier gas circulates, and an adsorption and desorption treatment device 10 provided on the circulation path L1. And a condensation recovery device 20. Further, on the circulation path L1, a circulation blower 40 and a gas blower 50 to be processed are provided. As the carrier gas, it is possible to use various types of gases such as steam, heated air, and an inert gas heated to a high temperature. In particular, when an inert gas, which is a gas containing no moisture, is used, the organic solvent recovery system 100A can be configured to be more simple.

The circulation path L1 is provided with piping lines L4 to L7 shown in the drawing. The circulation blower 40 is a blowing means for passing the carrier gas through the circulation path L1 so that the carrier gas circulates, and the target gas blower 50 transfers the target gas from the piping line L2 to the adsorption and desorption treatment device 10. It is a means of supplying air.

The adsorption/desorption treatment apparatus 10 is provided with an adsorption/desorption tank A11 and an adsorption/desorption tank B12. The adsorption and desorption tank A (11) is filled with an adsorption and desorption element A (13) for adsorbing and desorbing organic solvents, and the adsorption and desorption tank B (12) contains an adsorption and desorption element B (14) that adsorbs and desorbs organic solvents It is charged. Although two adsorption and desorption tanks are provided in this embodiment, one or three or more may be sufficient. In addition, the adsorption and desorption treatment apparatus 10 is provided with a heater (heating part) 30.

The heater 30 heats the carrier gas supplied to the adsorption and desorption tank A (11) or the adsorption and desorption tank B (12). More specifically, the heater 30 is the adsorption and desorption tank A (11) or the adsorption and desorption tank B (12) with the carrier gas discharged from the condensation recovery device 20 and passed through the circulation blower 40 at a high temperature. To supply. Here, the heater 30 is a carrier introduced into the adsorption and desorption tank A (11) and the adsorption and desorption tank B (12) so that the adsorption and desorption element A (13) and the adsorption and desorption element B (14) are maintained at a predetermined desorption temperature. Adjust the temperature of the gas. In addition, the heater 30 may be provided outside the adsorption/desorption treatment device 10.

The adsorption/desorption element A13 and the adsorption/desorption element B14 adsorb the organic solvent contained in the gas to be treated by contacting the gas to be treated introduced from the piping line L2. Some gas to be processed contains moisture, and this moisture is also adsorbed. Therefore, in the desorption treatment apparatus 10, when the gas to be processed is supplied to the adsorption and desorption tank A (11) or the adsorption and desorption tank B (12), the organic solvent and moisture are transferred to the adsorption and desorption element A (13) or the adsorption and desorption element. The organic solvent is removed from the gas to be treated by being adsorbed on the B 14, and the gas to be treated is purified and discharged from the adsorption and desorption tank A (11) or the adsorption and desorption tank B (12) as a clean gas.

Further, the adsorption and desorption element A13 and the adsorption and desorption element B14 desorb the adsorbed organic solvent and moisture by contacting the carrier gas in a high-temperature state. Therefore, in the adsorption and desorption treatment apparatus 10, when a carrier gas in a high-temperature state is supplied to the adsorption and desorption tank A (11) or the adsorption and desorption tank B (12), the organic solvent and moisture are absorbed and desorbed by the adsorption and desorption element A13 ) Or a carrier gas that is desorbed from the adsorption and desorption element B (14), and contains an organic solvent and moisture, is discharged from the adsorption/desorption tank A (11) or the adsorption/desorption tank B (12).

The adsorption and desorption element A (13) and the adsorption and desorption element B (14) are composed of an adsorbent containing any of granular activated carbon, activated carbon fiber, zeolite, silica gel, a porous polymer, and a metal organic structure. Preferably, activated carbon or zeolite such as granular, powder, and honeycomb is used, but more preferably, activated carbon fiber is used. Since the activated carbon fiber has a fibrous structure having micropores on its surface, the contact efficiency with gas is high, and the adsorption efficiency is higher than that of other adsorbents.

In addition, since activated carbon fibers have higher adsorption selectivity to organic solvents than activated carbon such as granular, powdery, honeycomb, etc., they hardly adsorb moisture contained in the gas to be treated. Therefore, the moisture contained in the carrier gas discharged from the adsorption and desorption tank A (11) or the adsorption and desorption tank B (12) of the adsorption and desorption treatment apparatus 10 becomes a very small amount, and the organic solvent recovery system is configured to be more simple. And the organic solvent recovery system can be downsized. When an adsorption and desorption element having low adsorption selectivity to an organic solvent is used, a large amount of moisture contained in the gas to be treated is adsorbed. Therefore, the moisture contained in the carrier gas discharged from the adsorption and desorption tank A 11 and the adsorption and desorption tank B 12 of the adsorption and desorption treatment apparatus 10 also becomes large, and the organic solvent recovery system 100A Since wastewater containing the solvent is discharged, separate wastewater treatment is required.

Piping lines L2 and L3 are connected to the adsorption/desorption processing apparatus 10, respectively. The piping line L2 is a piping line for supplying a target gas containing an organic solvent and moisture to the adsorption/desorption tank A11 or the adsorption/desorption tank B12 via the target gas blower 50. In the piping line L2, the connected/disconnected state to the adsorption and desorption tank A11 is switched by the valve V1, and the connected/disconnected state to the adsorption and desorption tank B12 is switched by the valve V3. The piping line L3 is a piping line for discharging the clean gas from the adsorption and desorption tank A (11) or the adsorption and desorption tank B (12). In the piping line L3, the connected/disconnected state to the adsorption and desorption tank A11 is switched by the valve V2, and the connected/disconnected state to the adsorption and desorption tank B12 is switched by the valve V4.

In addition, piping lines L5 and L6 are connected to the adsorption/desorption processing apparatus 10, respectively. The piping line L5 is a piping line for supplying the carrier gas to the adsorption/desorption tank A11 or the adsorption/desorption tank B12 via the heater 30. In the piping line L5, the connected/disconnected state to the adsorption and desorption tank A11 is switched by the valve V5, and the connected/disconnected state to the adsorption and desorption tank B12 is switched by the valve V7. The piping line L6 is a piping line for discharging the carrier gas from the adsorption and desorption tank A (11) or the adsorption and desorption tank B (12). In the piping line L6, the connected/disconnected state to the adsorption and desorption tank A11 is switched by the valve V6, and the connected/disconnected state to the adsorption and desorption tank B12 is switched by V8.

To each of the adsorption/desorption tank A11 and the adsorption/desorption tank B12, by operating the opening/closing of the valves V1 to V8 described above, the gas to be treated and the carrier gas in a high temperature state are alternately supplied in time. Thereby, the adsorption and desorption tank A (11) and the adsorption and desorption tank B (12) alternately function as an adsorption tank and a desorption tank in time, and as a result, the organic solvent and moisture are transferred from the target gas to a high temperature state. Move to the carrier gas. In addition, specifically, during the period in which the adsorption and desorption tank A 11 functions as an adsorption tank, the adsorption and desorption tank B 12 functions as a desorption tank, and the adsorption and desorption tank A 11 functions as a desorption tank. During the period, the adsorption and desorption tank B 12 functions as an adsorption tank.

The condensation recovery device 20 includes a condenser (condenser) 21, a recovery tank 22, and a refrigerant/fruit supply unit 23. The condenser 21 controls the temperature of the carrier gas in a high-temperature state discharged from the adsorption and desorption tank A 11 or the adsorption and desorption tank B 12 to a low-temperature state, so that the organic solvent and trace moisture contained in the carrier gas Is to condense. The condenser 21 specifically liquefies the organic solvent and moisture by indirectly cooling the carrier gas using a refrigerant. The recovery tank 22 stores the organic solvent and moisture liquefied in the condenser 21 as a condensate. Further, the recovery tank 22 and the refrigerant/fruit supply unit 23 may be provided outside the condensation recovery device 20.

The refrigerant/fruit supply unit 23 alternately supplies the refrigerant or the heat medium to the condenser 21 in time. The condensation recovery device 20 supplies a refrigerant from the refrigerant/fruit supply unit 23, and indirectly cools the carrier gas including the organic solvent and moisture discharged from the adsorption and desorption device 10 with a condenser 21, and Condensation treatment (refrigerant supply) is performed to condense the organic solvent and moisture by controlling the temperature in the state of. In addition, the condensation recovery device 20 supplies heat from the refrigerant/fruit supply unit 23, and indirectly heats and melts the condenser 21 and water and organic solvents (freezing components) frozen in the vicinity thereof ( Fruit supply). By the melting treatment, the frozen component can be efficiently heated by temporarily supplying the heat medium to the condenser serving as the cooling source, so that the frozen component can be melted in a short time.

Here, water, ethanol, ethylene glycol, propylene glycol, chlorofluorocarbons, hydrochlorofluorocarbons, hydrofluorocarbons, or mixtures thereof may be used as the refrigerant and heat medium, but is not particularly limited. In addition, the fruit refers to a medium that is in a state of higher temperature than the refrigerant.

Piping lines L6 and L7 are connected to the condensation recovery device 20, respectively. The piping line L6 is a piping line for supplying the carrier gas discharged from the adsorption/desorption processing apparatus 10 to the condenser 21. The piping line L7 is a piping line for discharging the carrier gas from the condenser 21.

Further, a pipe line L9 is connected to the capacitor 21. The piping line L9 is a piping line for introducing the organic solvent and trace moisture condensed by the condenser 21 into the recovery tank 22.

In addition, piping lines L10 and L11 are connected to the capacitor 21, respectively. The piping line L10 is a piping line for supplying the refrigerant or the heat medium to the condenser 21 from the refrigerant/fruit supply unit 23. The piping line L11 is a piping line for discharging a refrigerant or a heat medium from the condenser 21 to the outside. In the present embodiment, the piping line L11 is connected to the refrigerant/heat medium supply unit 23, and is used by circulating the refrigerant or heat medium. By circulating and using the refrigerant or the heat medium, the amount of heat can be recovered, and the condensation recovery device 20 can be operated with energy saving.

FIG. 2 is a time chart showing the temporal conversion of adsorption treatment and desorption treatment using the adsorption and desorption element A 13 and the adsorption element B 14 in the organic solvent recovery system 100A shown in FIG. 1. . Next, referring to FIG. 2, details of the processing of the gas to be processed using the organic solvent recovery system 100A in the present embodiment will be described as an example in which an inert gas is used as a carrier gas.

The organic solvent recovery system 100A can continuously process the gas to be treated by repeating the cycle with one cycle shown in FIG. 2 as a unit period.

In the first half of the first cycle (between time t0 to t2 shown in Fig. 2), in the adsorption and desorption tank A (11) of the adsorption and desorption treatment device 10 filled with the adsorption and desorption element A (13), the adsorption treatment Is carried out. In parallel with this, in the adsorption and desorption tank B 12 of the adsorption and desorption treatment device 10 filled with the adsorption and desorption element B 14, a purge treatment in which the inside of the adsorption and desorption tank B 12 is replaced with an inert gas (Fig. 2 A desorption process (between a time t1 to t2 shown in FIG. 2) is performed after that (between the time t0 to t1 shown in FIG. 2). The inert gas and carrier gas used in the purge treatment are the same. The downstream of the adsorption and desorption tank B (12) during the purge treatment is connected to the upstream side of the target gas blower (50), and is replaced with an inert gas to be discharged (gas remaining in the adsorption and desorption tank B (12). ) Is preferably piped so as to be supplied together with the gas to be treated to the adsorption and desorption tank A11 in which the adsorption treatment is performed. This is because it is possible to increase the recovery concentration of the organic solvent by allowing it to be subjected to the adsorption treatment again. In this embodiment, as described above, the downstream of the adsorption and desorption tank during the purging process is in a connected state with the upstream side of the gas blower 40 to be processed, and is configured so that the condenser 21 side is in a non-connected state. Do (not shown). Switching to this connected/disconnected state is also performed with the valve.

In addition, in the second half of the cycle (between time t2 to t4 shown in Fig. 2), adsorption in the adsorption and desorption tank B 12 of the adsorption and desorption treatment device 10 filled with the adsorption and desorption element B 14 In the adsorption and desorption tank A (11) of the adsorption and desorption treatment apparatus 10 in which the adsorption and desorption element A (13) is filled in parallel with this treatment, the inside of the adsorption and desorption tank A (11) is replaced with an inert gas. After the purging process (between the times t2 to t3 shown in Fig. 2) is performed, the desorption process (between the times t3 to t4 shown in Fig. 2) is performed.

In the condensation recovery device 20, a refrigerant is supplied from the refrigerant/fruit supply unit 23 to indirectly cool the carrier gas containing the organic solvent and trace moisture discharged from the adsorption and desorption device 10 with a condenser 21, Then, a condensation treatment (between the time t0 to t2 shown in Fig. 2) of condensing the organic solvent by controlling the temperature in a low-temperature state is performed, and the organic solvent and trace moisture are recovered.

The condensation recovery device 20 includes a vapor pressure measuring unit (not shown) for measuring the vapor pressure of the organic solvent contained in the carrier gas discharged from the condenser 21, and the vapor pressure of the organic solvent measured by the vapor pressure measuring unit is predetermined. A temperature controller (not shown) for controlling the temperature of the condenser 21 may be provided so as to be less than or equal to the value. By controlling the temperature of the condenser, the concentration of the organic solvent in the discharged carrier gas can be made below a certain level, and the organic solvent adsorbed on the adsorption and desorption element can be efficiently desorbed.

For example, as in the examples to be described later, when the organic solvent is ethyl acetate, in the condensation treatment, the carrier gas is supplied so that the vapor pressure of the organic solvent contained in the carrier gas discharged from the condenser 21 is 11.4 mmHg or less. It is preferable to adjust the temperature, and it is more preferable to adjust the temperature of the carrier gas so as to be 6.1 mmHg or less. When the vapor pressure of the organic solvent contained in the carrier gas discharged from the condenser 21 is 11.4 mmHg or less, the organic solvent contained in the carrier gas that circulates and contacts the adsorption and desorption element A (13) and the adsorption and desorption element B (14) Since the vapor pressure is also sufficiently lowered, the regeneration of the adsorption and desorption element A 13 and the adsorption and desorption element B 14 is effectively promoted. On the other hand, when the vapor pressure of the organic solvent contained in the carrier gas discharged from the condenser 21 exceeds 11.4 mmHg, it is contained in the carrier gas that circulates and contacts the adsorption and desorption element A (13) and the adsorption and desorption element B (14). Since the vapor pressure of the organic solvent to be used is also expensive, it is difficult to sufficiently regenerate the adsorption and desorption element A 13 and the adsorption and desorption element B 14, and performance degradation occurs as a system. These values of 11.4 mmHg and 6.1 mmHg are values derived from experimental results in Examples described later.

The temperature adjustment of the carrier gas can be controlled by the amount of the refrigerant from the refrigerant/heat supply unit 23 or the temperature of the refrigerant. Specifically, the relationship between the temperature and the vapor pressure is taken as data, and the temperature of the carrier gas is adjusted by the refrigerant so that the desired vapor pressure is achieved. In addition, although the relationship between temperature and vapor pressure varies depending on the type of organic solvent, it can be confirmed in literature and the like. The vapor pressure of the organic solvent can be measured by a VOC concentration meter or gas chromatography.

In addition, when the temperature of the carrier gas is adjusted so that the vapor pressure of the organic solvent contained in the carrier gas discharged from the condenser 21 is equal to or less than a predetermined value, for example, the condenser 21 and the adsorption/desorption treatment device (10) There is no need to provide an adsorption/desorption element for adsorbing and removing the organic solvent in the carrier gas, etc., and the organic solvent recovery system 100A can have a simple configuration, thereby reducing the size.

In addition, when the condensation recovery device 20 adjusts the temperature of the carrier gas so that the vapor pressure of the organic solvent contained in the carrier gas discharged from the condenser 21 is equal to or less than a predetermined value, the carrier gas is zero according to the type of the organic solvent. It is necessary to control the temperature below ℃. For this reason, the organic solvent and moisture contained in the carrier gas are frozen in the condenser 21, the flow path of the carrier gas is blocked, the air permeation resistance of the condenser 21 increases, and the carrier gas cannot flow. Therefore, in the refrigerant/nutrient supply unit 23, by switching from the supply of the refrigerant to the supply of the heat medium, the frozen organic solvent and trace moisture are indirectly heated so that the flow path in the condenser 21 is not blocked and melted (Fig. 2). (Between the time t2 to t3 shown in the figure) is carried out. The molten organic solvent and trace moisture are discharged to the recovery tank 22 through the piping line L9.

In addition, it is better not to supply the carrier gas to the condenser 21 during the melting process. If a carrier gas is supplied to the condenser 21 during the melting treatment, the molten organic solvent and moisture are vaporized and contained in the carrier gas, and are discharged on the circulation path L1 through the piping line L7, thereby enabling efficient liquefied recovery. There will be no. For this reason, between the purge processing in which the adsorption and desorption element A13 or the adsorption and desorption element B14 does not perform the desorption treatment, the fusing treatment may be performed without supplying the carrier gas to the capacitor 21. In this embodiment, as described above, since the adsorption and desorption tank 12 being purged is in a state of being disconnected from the condenser 21, and instead, it is in a state of being connected to the upstream of the target gas blower 50, The gas to be treated (gas remaining in the adsorption and desorption tank B 12) that is discharged after being replaced with an inert gas in the purge process is not supplied to the condenser 21.

In addition, in the condensation recovery device 20, the organic solvent and trace moisture in the condenser 21 continue until almost melted, and when the melting of the organic solvent and trace moisture is completed, the refrigerant/nutrient supply unit 23 is Switch from supply to supply of refrigerant. Thereby, the condenser 21 performs a condensation treatment (between time t3 to t4 shown in Fig. 2) of condensing the organic solvent and trace moisture by indirectly cooling the carrier gas and adjusting the temperature to a low temperature state.

Here, in Fig. 2, as an example, the melting process is performed between the times t2 and t3, but the melting process of the capacitor 21 need not be performed every cycle. It may be performed regularly or may be performed irregularly. In addition, as shown in FIG. 2, it is not necessary to perform only between the purge processing of the adsorption and desorption element A13, and may be performed between the purge processing of the adsorption and desorption element B14.

In addition, if the melting treatment cannot be completed between the purge treatment of the adsorption and desorption element A (13) or the adsorption and desorption element B (14), several capacitors are installed, and while the melting treatment is continued in one capacitor, the other A condensation treatment may be performed in a condenser. In this case, the condenser for performing the melting treatment and the condenser for performing the condensation treatment may be configured to be switched by valve operation, but are not particularly limited.

Here, a positive pressure difference measuring unit (not shown) that measures the difference between the positive pressure at the inlet of the condenser 21 of the carrier gas and the positive pressure at the outlet of the condenser 21 is provided, and the difference between the positive pressure is equal to or greater than a predetermined value. By switching from the condensation treatment to the melting treatment at the point at which the condensation treatment is reached, an increase in the air permeation resistance of the capacitor 21 can be prevented at all times. From the measurement result of the static pressure difference measuring unit, the problem of gas flow due to adhesion of the frozen component can be detected, and the frozen component can be automatically heated and melted by switching to a melting treatment (fruit supply). Here, the "predetermined value" determines the pressure loss (differential pressure) of the condenser 21 such that the discharge pressure of the circulation blower 40 does not decrease as a limit value. The discharge pressure of the circulation blower 40 is determined according to the motor capability of the circulation blower 40. As the static pressure difference measuring part, if a pressure gauge is used to connect the positive pressure measuring port of the pressure gauge and the inlet (L6 side) of the condenser 21, and the negative pressure measuring port and the outlet (L7 side) of the condenser 21 are connected, the positive pressure You can measure the car.

In addition, if the concentration of the organic solvent and the amount of moisture contained in the gas to be treated can be grasped in advance, it is taken as data, and the refrigerant/fruit supply unit 23 switches the condensation treatment and the melting treatment at regular time intervals. do.

Here, when activated carbon fibers are used for the adsorption and desorption elements A (13) and the adsorption and desorption elements B (14), since they hardly adsorb moisture contained in the gas to be treated, they are contained in the carrier gas supplied to the condenser 21. The resulting moisture becomes a very small amount. Therefore, the amount of water frozen in the condenser 21 may be very small, the frequency of the condenser 21 performing the melting treatment is significantly reduced, energy required for the melting treatment can be reduced, and further organic solvent recovery The system 100A can be made a simpler configuration.

The organic solvent recovery system 100A of the present embodiment is also excellent in economical efficiency because the carrier gas can be repeatedly used by the construction of the circulation path L1. Therefore, when an inert gas typified by nitrogen gas or the like is used as a carrier gas, an effect of particularly suppressing running cost is obtained.

In the organic solvent recovery system 100A of the present embodiment described above, since the frozen component is temporarily heated and melted by supplying the heating medium to the condenser 21, there is a problem of gas flow due to adhesion of the frozen component. Can be solved. For this reason, the carrier gas can be cooled at a lower temperature than in the conventional system, so that the efficiency of condensation and recovery of the organic solvent can be improved. In addition, by this, the concentration of the organic solvent in the carrier gas discharged from the condensation and recovery device 20 can be reduced, and the desorption efficiency by the carrier gas in the adsorption treatment device 10 is increased. There is no need to separately provide a second adsorption/desorption treatment device on the downstream side of ). Since the concentration of the organic solvent in the carrier gas can be reduced, it is a result of promoting the regeneration of the adsorption and desorption element A (13) and the adsorption and desorption element B (14) in the desorption treatment. , It is possible to more efficiently adsorb and remove the organic solvent from the gas to be treated. Therefore, by using the organic solvent recovery system 100A, the running cost can be reduced, the purification ability of the gas to be treated and the recovery efficiency of the organic solvent are improved, and further simplification and miniaturization of the system configuration can be achieved. I can. As described above, according to the present embodiment, it is possible to provide an organic solvent recovery system having a high performance and simple configuration compared to the conventional one.

(Example)

In the following examples, the processing target gas was performed using the organic solvent recovery system 100A according to the embodiment of the present invention described above.

In Examples, a gas having a relative humidity of 60% RH and 40°C containing ethyl acetate as an organic solvent at a concentration of 3000 ppm was used as the gas to be treated. Nitrogen gas at 120°C was used as the carrier gas. In addition, as the adsorption and desorption element A (13) and the adsorption and desorption element B (14), activated carbon fibers having a BET specific surface area of 1500 mg/m 2 were used, and an aqueous solution of 70% by mass of ethylene glycol was used as a coolant and a heat medium.

First, by using the gas blower 50 to be treated, blowing into the adsorption and desorption tank of the adsorption and desorption tank A (11) and the adsorption/desorption tank B (12) of the adsorption ^{/desorption treatment device 10 at an air volume of 10 Nm 3} /min for 10 minutes By doing so, the adsorption and desorption tank functioned as an adsorption tank, and adsorption treatment was performed.

After the completion of the adsorption treatment, the valve was switched to operate, the one adsorption and desorption tank was switched to the desorption tank, and the other adsorption and desorption tank was used as the adsorption tank. In the desorption tank, after purging the inside of the desorption tank with nitrogen gas, nitrogen gas heated at 120°C with a heater 30 ^{was introduced at an air volume of 1.5 Nm 3} /min to perform desorption treatment of the adsorption and desorption element. In the adsorption tank, adsorption treatment similar to the conditions described above was performed. In the condensation recovery device 20, a refrigerant is supplied from the refrigerant/fruit supply unit 23 to the condenser 21, and a condensation treatment is performed in which nitrogen gas containing ethyl acetate discharged from the desorption tank is cooled to -30°C. .

When one cycle described above was continuously repeated, it was confirmed that the concentration of ethyl acetate contained in the clean gas discharged from the adsorption and desorption treatment apparatus 10 was reduced to about 20 ppm. That is, in Examples, it was confirmed that ethyl acetate can be removed with a high removal rate of about 99%.

In addition, in the desorption treatment described above, it was confirmed that the vapor pressure of ethyl acetate contained in the nitrogen gas flowing through the piping line L6 through which the gas is introduced into the condensation recovery device 20 rises to an average of 15.2 mmHg, and the condensation recovery device It was confirmed that the vapor pressure of ethyl acetate contained in the nitrogen gas flowing through the piping line L7 for discharging the gas from (20) was always lowering to 2.7 mmHg or less. In this example, the temperature of the refrigerant was changed, and the temperature of the nitrogen gas was adjusted so that the vapor pressure of ethyl acetate was always 2.7 mmHg or less.

Further, 5 hours after the start of blowing of the gas to be treated, trace moisture was frozen (solidified) in the condenser 21 of the condensation recovery device 20, so that the differential pressure between the inlet and the outlet of the nitrogen gas was 150 mmH. _{Since it was confirmed that it is rising to 2} O to 300 mmH ₂ O, while one of the adsorption and desorption element A (13) or the adsorption and desorption element B (14) is performing a purge treatment, the refrigerant/fruit supply unit 23 Was switched from the supply of the refrigerant to the supply of the heat medium, and the condenser 21 was switched from the condensation treatment to the melting treatment. The temperature of the heating medium supplied from the refrigerant/fruit supply unit 23 was set to 30°C.

Since the frozen trace moisture was rapidly melted by the melting treatment of the condenser 21, the refrigerant/nutrient supply unit 23 is switched from the supply of the heat medium to the supply of the coolant again, and the condenser 21 is condensed from the melting treatment. Switched to processing.

The melting treatment of the condenser 21 described above is performed when the differential pressure between the positive pressure at the inlet of the condenser 21 of nitrogen gas and the positive pressure at the outlet of the condenser 21 rises _{to 150 mmH 2} O to 300 mmH _{2 O.} did. More specifically, about every 5 hours, while one of the adsorption/desorption element A13 or the adsorption/desorption element B14 is performing a purge treatment, the condenser 21 was melted.

Even immediately after performing the melting treatment of the condenser 21 described above, it was confirmed that the concentration of ethyl acetate contained in the clean gas discharged from the adsorption and desorption treatment apparatus 10 was reduced to about 20 ppm. That is, in this example, it was confirmed that the condenser can be melted without affecting the removal efficiency of ethyl acetate from the gas to be treated.

The embodiments and examples disclosed above are illustrative in all respects, and are not restrictive. The technical scope of the present invention is defined by the claims, and includes the meanings equivalent to the description of the claims and all changes within the scope.

The present invention can be effectively used, for example, in a system for treating a target gas containing an organic solvent discharged from a factory or a building.

10: adsorption and desorption treatment device
11: adsorption and desorption tank A
12: adsorption and desorption tank B
13: adsorption and desorption element A
14: adsorption and desorption element B
20: condensation recovery device
21: Condenser (melting part, cooling part, cooling and melting part)
22: recovery tank
23: refrigerant/fruit supply unit (refrigerant fruit supply unit)
30: heater (heating part)
40: circulation blower
50: target gas blower
100A: organic solvent recovery system
L1: circulation path
L2 to L11: piping line
V1 to V8: valve

Claims (6)

It is an organic solvent recovery system that separates and recovers an organic solvent from a gas to be treated containing an organic solvent,
A circulation path through which the carrier gas circulates,
An adsorption and desorption treatment device provided on the circulation path and having an adsorption and desorption element, which alternately performs adsorption of the organic solvent by introduction of the target gas and desorption of the organic solvent by introduction of the carrier gas;
It has a cooling part provided on the downstream side of the adsorption and desorption treatment device on the circulation path to cool the carrier gas discharged from the adsorption and desorption treatment device, and to condense the organic solvent in the carrier gas by the cooling and recover it as a condensate. A condensation recovery device,
A heating unit provided on the circulation path on the upstream side of the adsorption and desorption treatment device to heat the carrier gas in a low temperature state discharged from the condensation and recovery device,
The condensation and recovery device has a melting unit that temporarily heats and melts the component frozen by the cooling. The method of claim 1, wherein the condensation recovery device has a refrigerant heat medium supply unit that selects and supplies a refrigerant and a heat medium,
The cooling unit and the melting unit are configured identically as a cooling and melting unit, and the cooling and melting unit functions as the cooling unit by receiving a coolant from the coolant fruit supply unit, and receiving a fruit from the coolant fruit supply unit to serve as the melting unit. Organic solvent recovery system, characterized in that the function. The method according to claim 2, further comprising a static pressure difference measuring unit that measures a difference between a static pressure on an inlet side and an outlet side of the carrier gas in the condensation recovery device,
The refrigerant heat medium supply unit selects the supply of the heat medium when a difference between the static pressure measured by the static pressure measurement unit exceeds a predetermined value. The method according to any one of claims 1 to 3, comprising a vapor pressure measuring unit for measuring the vapor pressure of the organic solvent contained in the carrier gas discharged from the condensation recovery device,
The organic solvent recovery system, characterized in that it has a temperature control unit that adjusts the temperature of the cooling unit so that the vapor pressure of the organic solvent measured by the vapor pressure measuring unit is equal to or less than a predetermined value. The organic solvent recovery system according to any one of claims 1 to 4, wherein a carrier gas is not supplied to the condensation recovery device during the melting by the melting unit. The adsorption and desorption treatment device according to any one of claims 1 to 5, wherein the adsorption and desorption treatment device performs a purge treatment on the adsorption and desorption element after the adsorption and before the desorption,
The fusion unit performs the fusion during the purge treatment period.

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