JP2014000521A - Organic solvent recovery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic solvent recovery system for only discharging an exhaust gas from which the organic solvent is sufficiently adsorbed and eliminated.SOLUTION: There is provided an organic solvent recovery system for separating and recovering an organic solvent from an exhaust gas containing an organic solvent while circulating the exhaust gas, which comprises: a first organic solvent concentration device 200 and a second organic solvent concentration device 700 having adsorption elements capable of reversely adsorbing/desorbing an organic solvent; and a cooling and recovery system 300 for condensing and recovering an organic solvent by cooling an exhaust gas in which the organic solvent is concentrated by the organic solvent concentration devices, wherein the adsorption elements desorb the organic solvent adsorbed when an exhaust gas at a temperature higher than a predetermined temperature is passed, adsorbs the organic solvent in the exhaust gas when an exhaust gas at a temperature lower than a predetermined temperature is passed, and an exhaust gas in which the concentration of the organic solvent is lower than a predetermined concentration of an exhaust gas at a temperature lower than the predetermined temperature passed through an adsorption part of the first organic solvent concentration device is passed through an adsorption part of the second organic solvent concentration device to discharge the exhaust gas after the passing to the outside of the system.

Description

  The present invention relates to an organic solvent recovery system, and more particularly to an organic solvent recovery system that recovers an organic solvent from exhaust gas.

  There exists patent document 1 as a prior art document which disclosed the organic-solvent containing gas processing system which collect | recovers the organic solvent from waste gas. In the organic solvent-containing gas processing system described in Patent Document 1, the organic solvent in the organic solvent-containing gas is adsorbed and removed by the adsorbing element containing the adsorbent, while the adsorbed organic solvent is desorbed by heated air. .

JP 2007-44595 A

  In an organic solvent recovery system that recovers organic solvent from exhaust gas, when the organic solvent-containing gas generated from the process is processed by the organic solvent concentrator and cooling recovery device, a part of the gas processed by the organic solvent concentrator is used. When discharged to the outside, the concentration of the organic solvent may be high, which is a problem.

  The present invention has been made in view of the above problems, and can reduce the concentration of the organic solvent in the exhaust gas discharged out of the system, and exhaust only the exhaust gas from which the organic solvent has been sufficiently adsorbed and removed. An object of the present invention is to provide an organic solvent recovery system that can be used.

The organic solvent recovery system based on the present invention is an organic solvent recovery system that separates and recovers an organic solvent from exhaust gas while circulating the exhaust gas containing the organic solvent,
First and second organic solvent concentrators having adsorbing elements capable of reversibly adsorbing and desorbing organic solvents;
A cooling recovery device that cools the exhaust gas in which the organic solvent is concentrated by the organic solvent concentration device and condenses and recovers the organic solvent;
The adsorbing element desorbs the adsorbed organic solvent when exhaust gas of a predetermined temperature or higher is passed, and adsorbs the organic solvent in the exhaust gas when exhaust gas lower than the predetermined temperature is passed,
The first and second organic solvent concentrators include a desorption unit through which exhaust gas having a temperature equal to or higher than the predetermined temperature is passed, and an adsorption unit through which exhaust gas lower than the predetermined temperature is passed,
Of the exhaust gas lower than the predetermined temperature that has flowed through the adsorption part of the first organic solvent concentrator, the exhaust gas with the organic solvent having a predetermined concentration or less is passed through the adsorber of the second organic solvent concentrator. The exhaust gas after passing through is discharged out of the system.

  Preferably, only a part of the exhaust gas in which the organic solvent becomes a predetermined concentration or less is passed through the adsorption part of the second organic solvent concentrating device, and the remaining part of the exhaust gas is circulated in the system.

  Preferably, the exhaust gas having a temperature equal to or higher than the predetermined temperature that has flowed through the desorption portion of the second organic solvent concentrating device is returned to the inlet of the cooling recovery device.

  In one aspect of the present invention, an organic solvent concentrating device includes a rotating shaft and a cylindrical adsorbent that has an adsorbing element positioned around the rotating shaft and allows exhaust gas to flow in the axial direction of the rotating shaft. Exhaust gas having a temperature equal to or higher than a predetermined temperature flows through a part of the cylindrical adsorbent from one end side in the axial direction of the cylindrical adsorbent. The exhaust gas having a temperature lower than the predetermined temperature is passed from the other end side in the axial direction of the cylindrical adsorbent to the other part of the cylindrical adsorbent. When the cylindrical adsorbent is rotated around the rotation axis, a part becomes a desorption part and the other part becomes an adsorption part.

  Preferably, the organic solvent concentrating device has a chamber that exhausts only exhaust gas in which the organic solvent has become a predetermined concentration or less by flowing through the adsorbing portion at one end of the cylindrical adsorbent.

  In one embodiment of the present invention, the chamber is movable with respect to the cylindrical adsorbent about the rotation axis.

  According to the present invention, it is possible to exhaust only the exhaust gas from which the organic solvent has been sufficiently adsorbed and removed.

It is a systematic diagram which shows the structure of the organic solvent collection | recovery system which concerns on Embodiment 1 of this invention. It is a perspective view shown with the waste gas which flows through the structure of the organic-solvent concentration apparatus which concerns on the same embodiment.

  Hereinafter, an organic solvent recovery system according to Embodiment 1 of the present invention will be described with reference to the drawings. In the following description of the embodiments, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a system diagram showing a configuration of an organic solvent recovery system according to Embodiment 1 of the present invention. As shown in FIG. 1, the organic solvent recovery system 1 according to Embodiment 1 of the present invention includes a production facility 1000 that is provided in various factories or research facilities and discharges exhaust gas containing an organic solvent. Yes.

  The organic solvent recovery system 1 according to the present embodiment is an organic solvent recovery system that separates and recovers an organic solvent from exhaust gas while circulating the exhaust gas containing the organic solvent discharged from the production facility 1000.

  In the organic solvent recovery system 1, a production facility 1000, a first organic solvent concentrator 200, a cooler 300, a cooling recovery device having a recovery tank 400, a heat exchanger 600, an air supply heater 100, and a second organic solvent concentrator 700. Is connected. Hereinafter, the function of each component will be described.

  The first organic solvent concentrator 200 has an adsorbing element capable of reversibly adsorbing and desorbing an organic solvent. The adsorbing element desorbs the adsorbed organic solvent when exhaust gas having a predetermined temperature or higher is passed, and adsorbs the organic solvent in the exhaust gas when exhaust gas lower than the predetermined temperature is passed.

  In this embodiment, an adsorption element containing activated carbon is used, but an adsorption element containing hydrophobic zeolite may be used. When an adsorbing element containing activated carbon and hydrophobic zeolite is used, the adsorbed organic solvent is desorbed when exhaust gas of about 50 ° C. or higher is passed, and exhaust gas lower than about 50 ° C. is passed. And adsorb organic solvent in exhaust gas. Further, the exhaust gas of the present embodiment is an exhaust gas containing an organic solvent such as n-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide and n-decane.

  The first organic solvent concentrating device 200 includes a desorption unit 21 through which exhaust gas having a predetermined temperature or higher flows, and an adsorption unit 22 through which exhaust gas lower than a predetermined temperature is passed. In the present embodiment, the first organic solvent concentrator 200 further includes a purge unit 23 between the desorption unit 21 and the adsorption unit 22 through which the exhaust gas having a temperature lower than a predetermined temperature through which the adsorption unit 22 flows. . However, the first organic solvent concentrating device 200 may not have the purge unit 23.

  As described above, the cooling and recovery device includes the cooler 300 and the recovery tank 400, cools the exhaust gas in which the organic solvent is concentrated by the first organic solvent concentrating device 200, and condenses and recovers the organic solvent. The cooler 300 cools and condenses the exhaust gas using cooling water or the like, thereby separating the recovered liquid containing the organic solvent at a high concentration and the exhaust gas containing the organic solvent at a low concentration. The recovered liquid containing the organic solvent at a high concentration is recovered in the recovery tank 400.

  In the heat exchanger 600, heat exchange is performed between exhaust gases flowing through different pipes. The supply air heater 100 heats the exhaust gas supplied to the production facility 1000 to a predetermined temperature.

In the second organic solvent concentrator 700, the exhaust G10a outside the system is adsorbed by the adsorption unit, and further the organic solvent concentration is reduced, while the organic solvent adsorbed by the adsorption unit with the high-temperature heating fluid is desorbed in the desorption unit. And the adsorption process is performed again. The degassed gas concentrated in the desorption part is processed by returning it to the inlet of the cooler 300.
In addition, it is also a preferred embodiment to further reduce the concentration of the organic solvent in the exhaust gas discharged out of the system by installing an organic solvent concentrating device after the second organic solvent concentrating device.

Hereinafter, the connection relationship of each component will be described.
The production facility 1000 and the first organic solvent concentrator 200 are connected by a pipe L1, and a valve V111 is provided in the pipe L1. The pipe L1 is connected to the desorption part 21 of the first organic solvent concentrator 200.

  The first organic solvent concentrator 200 and the heat exchanger 600 are connected by a pipe L5. The pipe L5 is connected to the desorption part 21 of the first organic solvent concentrator 200. A pipe L9 connected to the pipe L5 is connected to a position between the production facility 1000 of the pipe L1 and the valve V111. A valve V112 is provided in the pipe L9.

  The heat exchanger 600 and the cooler 300 are connected by a pipe L7. The cooler 300 and the recovery tank 400 are connected by a pipe L6. The cooler 300 and the first organic solvent concentrator 200 are connected by a pipe L2. The pipe L2 is connected to the adsorption unit 22 of the first organic solvent concentrator 200.

  The first organic solvent concentrator 200 and the heat exchanger 600 are connected by a pipe L3. A valve V113 is provided in the pipe L3. A pipe L10 connected to the purge part 23 of the first organic solvent concentrator 200 is connected to a position between the adsorption part 22 of the first organic solvent concentrator 200 and the valve V113 in the pipe L3. A valve V114 is provided in the pipe L10. A pipe L11 connected to the purge unit 23 of the first organic solvent concentrator 200 is connected to the pipe L2.

  The heat exchanger 600 and the air supply heater 100 are connected by a pipe L8. The supply heater 100 and the production facility 1000 are connected by a pipe L4. A pipe L <b> 12 for exhausting exhaust gas out of the system is connected to the adsorption unit 22 of the first organic solvent concentrator 200. A pipe L13 connected to the pipe L8 is connected to the pipe L12. A valve V117 is provided in the pipe L13.

  Although two heat exchangers 600 are illustrated in FIG. 1 for simplicity, only one heat exchanger may be provided. The heat exchanger 600 can exchange heat energy between the pipes L3 and L8 and heat energy between the pipes L5 and L7.

Hereinafter, the flow path of the exhaust gas circulating through the organic solvent recovery system 1 will be described.
As shown in FIG. 1, at least a part of the exhaust gas G1 discharged from the production facility 1000 becomes exhaust gas G1a that passes through the pipe L1 and flows to the desorption part 21 of the first organic solvent concentrator 200. The remaining part of the exhaust gas G1 becomes the exhaust gas G1b that passes through the pipe L9 and reaches the pipe L5 without flowing through the desorption part 21.

  For example, the exhaust gas G1 has an air volume of 380 NCMN, an organic solvent concentration of 1830 ppm, and a temperature of 110 ° C. The flow rate ratio between the exhaust gas G1a and the exhaust gas G1b is adjusted by opening and closing the valve V111 and the valve V112.

  The exhaust gas G1a becomes exhaust gas G2 by flowing through the desorption part 21 of the first organic solvent concentrator 200. Since the exhaust gas G1a has a temperature of 50 ° C. or higher, the organic solvent adsorbed by the adsorption element of the desorption part 21 is desorbed. When the temperature of the exhaust gas G1a is lower than 50 ° C., a regeneration heater for raising the temperature of the exhaust gas G1a may be provided in the section of the pipe L1.

  As a result, the organic solvent concentration of the exhaust gas G2 is higher than the organic solvent concentration of the exhaust gas G1a. For example, the exhaust gas G2 has an air volume of 380 NCMN, an organic solvent concentration of 2763 ppm, and a temperature of 94 ° C. In this case, the valve V112 is completely closed.

  The exhaust gas G2 is mixed with the exhaust gas G1b and passed through the heat exchanger 600, thereby releasing heat and becoming the exhaust gas G3. For example, the exhaust gas G3 has an air volume of 380 NCMN, an organic solvent concentration of 2763 ppm, and a temperature of 71 ° C.

  The exhaust gas G3 is cooled by being passed through the cooler 300, whereby a part of the contained organic solvent is condensed and separated. In the present embodiment, the concentration of NMP (n-methyl-2-pyrrolidone) separated by the cooler 300 and recovered in the recovery tank 400 is 97 wt%.

  The exhaust gas G4 flowing through the cooler 300 is cooled so that the temperature becomes 50 ° C. or less. For example, the exhaust gas G4 has an air volume of 380 NCMN, an organic solvent concentration of 1000 ppm, and a temperature of 37 ° C. The exhaust gas G4 is mixed with the exhaust gas G6b passed through the purge unit 23 to become the exhaust gas G5, and is passed to the adsorption unit 22 of the first organic solvent concentrator 200. The mixing amount of the exhaust gas G6b to the exhaust gas G4 is adjusted so that the exhaust gas G5 has a temperature of 50 ° C. or less.

  For example, the exhaust gas G6b has an air volume of 30 NCMN, an organic solvent concentration of 500 ppm, and a temperature of 100 ° C. For example, the exhaust gas G5 has an air volume of 410 NCMN, an organic solvent concentration of 963 ppm, and a temperature of 42 ° C.

  The exhaust gas G5 is adsorbed with the organic solvent contained by flowing through the adsorption part 22 of the first organic solvent concentrator 200. A part of the exhaust gas flowing through the adsorption unit 22 becomes exhaust gas G6a that flows through the purge unit 23. Of the exhaust gas that has flowed through the adsorption unit 22, the exhaust gas in which the organic solvent contained becomes a predetermined concentration or less is sent into the pipe L12 that leads to the outside. The remainder of the exhaust gas that has flowed through the adsorption unit 22 becomes the exhaust gas G7 that is passed through the heat exchanger 600. For example, the exhaust gas G7 has an air volume of 342NCMN, an organic solvent concentration of 30 ppm, and a temperature of 48 ° C.

  The exhaust gas G7 is passed through the heat exchanger 600, thereby absorbing heat and becoming exhaust gas G8. For example, the exhaust gas G8 has an air volume of 342NCMN, an organic solvent concentration of 30 ppm, and a temperature of 71 ° C.

  The exhaust gas G8 is heated by passing through the air supply heater 100 and becomes exhaust gas G9. For example, the exhaust gas G9 has an air volume of 342NCMN, an organic solvent concentration of 30 ppm, and a temperature of 120 ° C. The exhaust gas G9 is mixed with the exhaust gas newly exhausted from the production facility 1000 to become exhaust gas G1 and circulates in the system.

  Part of the exhaust gas sent into the pipe L12 from the adsorption part 22 of the first organic solvent concentrator 200 passes through the pipe L13 and reaches the pipe L8 without passing through the heat exchanger 600. Become. The remainder of the exhaust gas sent from the adsorption part 22 of the first organic solvent concentrator 200 into the pipe L12 becomes the exhaust gas G10a exhausted to the outside. For example, the exhaust gas G10a has an air volume of 38NCMN, an organic solvent concentration of 5 ppm, and a temperature of 43 ° C. In this case, the valve V117 is completely closed. Further, the waste gas G10a is sent to the second organic solvent concentrator 700. The organic solvent is adsorbed and removed by the adsorption part of the second organic solvent concentrating device, and the organic solvent concentration can be further reduced. For example, the air volume is 38 NCMN, the organic solvent concentration is 0.5 ppm, and the temperature is 43 ° C. Further, the organic solvent adsorbed in the desorption part of the second organic solvent concentrator 700 is desorbed. For example, the air volume is 2NCMN, the organic solvent concentration is 85.5 ppm, and the temperature of 80 ° C. is returned to the inlet of the cooler.

Hereinafter, the structures of the first and second organic solvent concentrators according to this embodiment will be described.
FIG. 2 is a perspective view showing together with the exhaust gas flowing through the structure of the organic solvent concentrator according to the present embodiment. In FIG. 2, a chamber to be described later is not shown.

  As shown in FIG. 2, the first and second organic solvent concentrators of this embodiment are of a rotor type, and an adsorbing element is positioned around the rotating shaft 211 and the rotating shaft 211, and exhaust gas is exhausted in the axial direction of the rotating shaft 211. It includes a cylindrical adsorbent 210 that is passed through. The rotating shaft 211 is rotated by an actuator (not shown).

  Specifically, in the cylindrical adsorbent 210, honeycomb-structured adsorbing elements are concentrically stacked over a plurality of layers. In FIG. 2, an end portion of the cylindrical adsorbent body 210 positioned on the front side of the paper surface is defined as one end 214 in the axial direction of the rotation shaft 211 of the cylindrical adsorbent body 210. On the other hand, the end portion of the cylindrical adsorbent body 210 located on the back side of the paper surface is defined as the other end 215 in the axial direction of the rotating shaft 211 of the cylindrical adsorbent body 210.

  The exhaust gas G1a having a predetermined temperature of 50 ° C. or higher is passed from the one end 214 side of the cylindrical adsorbent body 210 to the desorption part 21 which is a part of the cylindrical adsorbent body 210 to become exhaust gas G2.

  Exhaust gas G5 lower than a predetermined temperature of 50 ° C. is passed from the other end 215 side of the cylindrical adsorbent body 210 to the adsorbing portion 22 which is another part of the cylindrical adsorbent body 210. Exhaust gas G10a, which is part of the exhaust gas that has been passed through the adsorbing portion 22 and has an organic solvent having a predetermined concentration of 20 ppm or less, is exhausted outside the system. The remaining exhaust gases G7, G6a, and G10b are circulated through the system again without being exhausted.

  By rotating the cylindrical adsorbent body 210 around the rotation shaft 211, a part of the cylindrical adsorbent body 210 becomes the detachable portion 21, and another part of the cylindrical adsorbent body 210 becomes the adsorbed portion 22. . In addition, a part of the cylindrical adsorbent 210 serves as a purge unit 23 between the end of the desorption unit 21 and the start of the adsorption unit 22. In the present embodiment, the upper half of the cylindrical adsorbent body 210 is the adsorbing part 22, a part of the lower half is the desorbing part 21, and a part of the diagonally lower part between the desorbing part 21 and the adsorbing part 22 is It becomes the purge unit 23.

  The cylindrical adsorbent 210 rotates at a predetermined speed in a direction indicated by an arrow 201 in the drawing with the rotation shaft 211 as a rotation center. As a result, the adsorption element of the cylindrical adsorbent 210 moves from the adsorption unit 22 to the desorption unit 21 and then moves from the desorption unit 21 to the adsorption unit 22 via the purge unit 23 again. By treating the exhaust gas while rotating the cylindrical adsorbent body 210 in this manner, it is possible to continuously recover the organic solvent while simultaneously performing the adsorption process, the desorption process, and the purge process.

  The purge unit 23 is provided to cool the adsorption element of the purge unit 23 when exhaust gas having a temperature lower than a predetermined temperature is passed through the purge unit 23. The ratio of the purge unit 23 to the adsorption unit 22 is preferably 5% or more and 50% or less. When this ratio is smaller than 5%, the adsorption element cannot be cooled to a desired temperature. When this ratio is larger than 50%, the ratio of the portion of the cylindrical adsorbent where the organic solvent is adsorbed is too small, and the organic solvent recovery efficiency is lowered.

  In addition, the said embodiment disclosed this time is an illustration in all the points, Comprising: It does not become a basis of limited interpretation. Therefore, the technical scope of the present invention is not interpreted only by the above-described embodiments, but is defined based on the description of the scope of claims. Further, all modifications within the meaning and scope equivalent to the scope of the claims are included.

  DESCRIPTION OF SYMBOLS 1 Organic solvent recovery system, 21 Desorption part, 22 Adsorption part, 23 Purge part, 100 Air supply heater, 200 1st organic solvent concentrator, 210 Cylindrical adsorption body, 211 Rotating shaft, 212 Chamber, 213 Exhaust pipe, 214 End, 215 other end, 300 cooler, 400 recovery tank, 600 heat exchanger, 700 second organic solvent concentrator, 1000 production equipment, G1, G1a, G1b, G2, G3, G4, G5, G6a, G6b, G7 , G8, G9, G10a, G10b exhaust gas, L1, L2, L3, L4, L5, L6, L7, L8, L9, L10, L11, L12, L13 piping, V111, V112, V113, V114, V115 valves.

Claims (6)

An organic solvent recovery system for separating and recovering an organic solvent from exhaust gas while circulating the exhaust gas containing the organic solvent,
First and second organic solvent concentrators having adsorbing elements capable of reversibly adsorbing and desorbing organic solvents;
A cooling recovery device that cools the exhaust gas in which the organic solvent is concentrated by the organic solvent concentration device and condenses and recovers the organic solvent;
The adsorbing element desorbs the adsorbed organic solvent when exhaust gas of a predetermined temperature or higher is passed, and adsorbs the organic solvent in the exhaust gas when exhaust gas lower than the predetermined temperature is passed,
The first and second organic solvent concentrators include a desorption unit through which exhaust gas having a temperature equal to or higher than the predetermined temperature is passed, and an adsorption unit through which exhaust gas lower than the predetermined temperature is passed,
Of the exhaust gas lower than the predetermined temperature that has flowed through the adsorption part of the first organic solvent concentrator, the exhaust gas with the organic solvent having a predetermined concentration or less is passed through the adsorber of the second organic solvent concentrator. , Organic solvent recovery system that discharges exhaust gas after passing through the system.   2. The organic solvent according to claim 1, wherein only a part of the exhaust gas in which the organic solvent becomes a predetermined concentration or less is passed through the adsorption part of the second organic solvent concentrating device, and the remaining part of the exhaust gas is circulated in the system. Collection system.   3. The organic solvent recovery system according to claim 1, wherein the exhaust gas having a temperature equal to or higher than the predetermined temperature that has flowed through the desorption portion of the second organic solvent concentrating device is returned to the inlet of the cooling recovery device. The organic solvent concentrator includes a rotating shaft and a cylindrical adsorbing body in which the adsorbing element is positioned around the rotating shaft and exhaust gas flows in the axial direction of the rotating shaft,
The exhaust gas having a temperature equal to or higher than the predetermined temperature is passed from one end side in the axial direction of the cylindrical adsorbent to a part of the cylindrical adsorbent,
Exhaust gas lower than the predetermined temperature is passed from the other end side in the axial direction of the cylindrical adsorbent to another part of the cylindrical adsorbent,
The cylindrical adsorbent is rotated about the rotation axis, whereby the part becomes the desorption part and the other part becomes the adsorption part. The organic solvent recovery system described.   The organic solvent concentrating device has a chamber that exhausts only the exhaust gas in which the organic solvent has become a predetermined concentration or less by passing the adsorbing portion at an end portion on the one end side of the cylindrical adsorbent. Item 5. The organic solvent recovery system according to Item 4.   The organic solvent recovery system according to claim 5, wherein the chamber is movable with respect to the cylindrical adsorbent about the rotation axis.