JP2009208037A - Solvent recovering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently recover a solvent from solvent-containing gas. <P>SOLUTION: The solvent recovering apparatus recovering solvent from the solvent-containing gas has a gas flow passage 1 provided with a pre-cooler 2, a water cooler 3 and a condenser 4 for condensing the solvent-containing gas in this order. A coolant is supplied to the condenser 4 from a direct expanding type freezer system, so that the temperature of the condenser becomes 4 to 2°C. Thus, the solvent is efficiently recovered while preventing freezing of water contained in the gas. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the present invention, a solvent (solvent) such as a cleaning solvent or a reaction solvent, particularly a paraffinic hydrocarbon solvent having a boiling point of 180 to 250 ° C., or an alcoholic hydrocarbon solvent having a boiling point of 75 to 150 ° C. The present invention belongs to the technical field of a solvent recovery apparatus suitable for recovering a solvent from a solvent-containing gas containing a high-concentration solvent.

By the way, such organic solvents are widely used as solvents in various processes such as reaction, extraction, coating, degreasing and cleaning in various facilities such as chemical factories, painting factories, printing factories, chemical factories, semiconductor manufacturing factories, and precision machinery manufacturing factories. It has been adopted. Many of these solvents are recovered as they are because they have a high boiling point. However, some of them are vaporized and mixed with air. It becomes a cause of occurrence, and it is necessary to collect it in some form.
Therefore, as means for recovering the solvent mixed in the atmosphere, an adsorbent such as zeolite or activated carbon is used, and the solvent is adsorbed and desorbed to recover the solvent (for example, Patent Documents 1 and 2). However, since adsorbents such as zeolite are expensive, there is a problem that the burden on the economy is serious. In addition, zeolite and activated carbon are good adsorption / desorption media and at the same time have an excellent catalytic function. For this reason, there is a problem that they are altered by oxidation during adsorption / desorption of the solvent. In the case of a solvent having a high boiling point such as 200 ° C. or higher, treatment under a high-temperature atmosphere is required at the time of desorption, so that the oxidation proceeds more and the solvent changes in quality early. There is a problem that the deterioration is quick and the number of repeated use of the solvent and activated carbon is reduced.
Therefore, after the VOC gas is supplied to the first condenser (heat exchanger) on the side where the refrigerant is not supplied to the cooler, the second condenser (heat exchange) on the side where the refrigerant is supplied to the cooler. In the second condenser, moisture (steam) contained in the gas is frozen and attached in a state of taking in the solvent, while in the first condenser, It was proposed that the previously frozen water was heated and thawed with the supplied solvent-containing gas and recovered as a solvent-containing liquid, and the supplied solvent-containing gas was precooled (Patent Document 3). reference).
Japanese Patent Laid-Open No. 5-15724 Japanese Patent Laid-Open No. 5-15725 JP 2006-167543 A

  The above-mentioned proposal exhibited a high recovery capability and was effective as a means for solvent recovery. However, since this requires a two-column condenser, the entire apparatus becomes larger and the equipment cost increases. As a result, there is a problem that it is difficult to install in a place where it is difficult to secure a large installation space, such as SMEs and micro enterprises, and there is a problem that the present invention does not solve is there.

The present invention was created in view of the above-described circumstances to solve these problems, and the invention of claim 1 is a recovery device for recovering a solvent from a solvent-containing gas. The recovery device includes a condenser for condensing the solvent-containing gas, a refrigerant supply means for supplying a refrigerant to the condenser, and a pre-cooling leg means for pre-cooling the solvent-containing gas. The refrigerant supply means supplies the refrigerant so that the moisture in the solvent-containing gas does not freeze when the temperature of the condenser exceeds 0 ° C., and the precooling leg means receives the gas recovered from the solvent by the condenser. The solvent recovery device is connected to a condenser so as to be supplied as a refrigerant.
The invention according to claim 2 is the solvent recovery apparatus according to claim 1, wherein the solvent-containing gas contains 1000 to 10,000 ppm of a paraffinic hydrocarbon solvent having a boiling point of 180 to 250 ° C.
The invention according to claim 3 is the solvent recovery apparatus according to claim 1, wherein the solvent-containing gas contains 20000 to 30000 ppm of an alcohol-based hydrocarbon solvent having a boiling point of 75 to 150 ° C.
According to a fourth aspect of the present invention, the solvent-containing gas flow path for recovering the solvent is in the order of precooling means, water cooling means, and condenser. This is a recovery device.
According to a fifth aspect of the invention, the refrigerant supplied to the condenser is continuously supplied from a direct expansion type refrigerator system, and the solvent according to any one of the first to fourth aspects is provided. It is a recovery device.

According to the first aspect of the present invention, while the condenser is a single tower, the condenser can be operated for a long time without being closed by moisture freezing, and the gas recovered from the solvent in the condenser is preliminarily used. Since it can be effectively used as a refrigerant for the cooling means, the solvent recovery device can be reduced in size and price, and at the same time can be made highly energy efficient.
By making it invention of Claim 2, solvent recovery can be efficiently carried out from what contains 1000-10000 ppm of paraffinic hydrocarbon solvents whose boiling point is 180-250 degreeC.
By making it invention of Claim 3, solvent recovery can be efficiently carried out from what contains 20000-30000 ppm of the alcohol-type hydrocarbon solvent whose boiling point is 75-150 degreeC.
According to the invention of claim 4, the solvent-containing gas flow path becomes the pre-cooling means, the water cooling means, and the condenser in this order, so that more efficient solvent recovery can be performed.
According to the invention of the fifth aspect of the invention, the collection device can be made compact with a low manufacturing cost.

  Next, embodiments of the present invention will be described with reference to the drawings. In the figure, reference numeral 1 denotes a flow path of a solvent-containing gas in which a vaporized solvent is mixed and the solvent needs to be recovered. The flow path 1 includes a precooler (precooled condenser) 2 and a coolant at 2 ° C. cold water. The main condenser (heat exchanger) 4 is reached via a water cooler (water-cooled condenser) 3. A blower 5 is provided in the outlet-side flow path 1a of the condenser 4. By the intake / exhaust operation of the blower 5, the solvent-containing gas is sucked into the condenser 4, and as described later, The treated gas from which the solvent has been recovered is supplied as a refrigerant for the precooler 2 and then exhausted.

6 is a refrigerant tank, and the refrigerant stored in the refrigerant tank 6 is continuously supplied to the cooler 8 cooled by the direct expansion type refrigerator 7 by driving the pump 9 and cooled. Things are supplied as refrigerant of the condenser 4.
Reference numeral 10 denotes a condensate tank recovered by the condenser 4, and the condensate recovered in the condensate tank 10 is supplied to a moisture removing device (not shown) by driving the pump 11 to remove the moisture. Solvent is recovered.

  Next, the means for recovering the solvent will be described in detail. As the solvent-containing gas, a paraffinic hydrocarbon solvent having a boiling point of about 196 ° C. is contained at a concentration of 5000 ppm, and is supplied to the flow path 1 at 60 ° C. The The supplied solvent-containing gas is condensed by the condenser 4 to recover the solvent. When the condenser 4 starts operating at 18 ° C., a refrigerant cooled to 2 ° C. is supplied here. The temperature of the condenser 4 became about 2 ° C. in about 2 hours. When this state was maintained and the solvent recovery rate was measured, the recovery rate was 91.1%. In this case, in the condenser 4, the freezing phenomenon of the water contained in the solvent-containing gas did not appear even after 6 hours from the start of operation, and further operation was possible.

  On the other hand, when the recovery of the solvent-containing gas was attempted by supplying a refrigerant of −5 ° C. to the condenser 4 having an operation start temperature of 9 ° C., the condenser 4 became frozen in about 2 hours and was blocked. did.

As described above, in the case where the present invention is implemented, although the condenser 4 is one tower, the temperature in the condenser 4 is maintained at about 2 ° C. There is no blockage due to freezing, and a recovery operation can be performed at a high recovery rate for a long time. Moreover, the solvent recovered by the condenser 4 is effectively used as a refrigerant for cooling the precooler 2.
As a result, it is possible to recover the solvent with high efficiency by using one tower of the condenser 4, thereby achieving downsizing and cost reduction of the equipment and improving energy efficiency.

  Next, the recovery apparatus is used to recover isopropanol containing isopropanol gas having a boiling point of 82 ° C. at a concentration of 25000 ppm, and is supplied to the flow path 1 at 50 ° C. The supplied solvent-containing gas is condensed by the condenser 4 to recover the solvent. When the condenser 4 starts operating at 18 ° C., a refrigerant cooled to 2 ° C. is supplied here. The temperature of the condenser 4 became about 2 ° C. in about 2 hours. When this state was maintained and the solvent recovery rate was measured, the recovery rate was 71.0%. In this case, in the condenser 4, the freezing phenomenon of the water contained in the solvent-containing gas did not appear even after 6 hours from the start of operation, and further operation was possible.

  Furthermore, the recovery device is arranged in the order of the precooler 2 and the water cooler 3 in the solvent recovery gas flow path, but this is arranged opposite to the water cooler 3 and the precooler 2. And whether there was a difference in the solvent recovery rate. As the contained solvent, the paraffinic carbonized solvent except that the boiling point is 200 to 206 ° C. paraffinic hydrocarbon solvent is contained at a concentration of 1000 ppm and the precooler 2 and the water cooler 3 are arranged differently. The recovery rate was compared in the same manner as the hydrogen solvent recovery method. According to this, what was arranged in the order of the precooler 2 and the water cooler 3 had a recovery rate of 86%, whereas conversely, what was arranged in the order of the water cooler 3 and the precooler 2 was the recovery rate. Was 88.8%, which was confirmed to be slightly low, and the former was confirmed to have higher recovery efficiency.

It is a circuit diagram of a solvent collection | recovery apparatus.

Explanation of symbols

1 Channel 2 Precooler 3 Water Cooler 4 Condenser 5 Refrigerant Tank

Claims (5)

  A recovery device for recovering a solvent from a solvent-containing gas, the recovery device comprising: a condenser for condensing the solvent-containing gas; a refrigerant supply means for supplying a refrigerant to the condenser; Precooling leg means for precooling the gas is provided, and the refrigerant supply means supplies the refrigerant so that the temperature of the condenser exceeds 0 ° C. and the water in the solvent-containing gas does not freeze. The pre-cooling leg means is connected to the condenser so that the gas recovered from the solvent in the condenser is supplied as a refrigerant.   2. The solvent recovery apparatus according to claim 1, wherein the solvent-containing gas contains 1000 to 10,000 ppm of a paraffinic hydrocarbon solvent having a boiling point of 180 to 250 ° C.   2. The solvent recovery apparatus according to claim 1, wherein the solvent-containing gas contains 20000 to 30000 ppm of an alcohol-based hydrocarbon solvent having a boiling point of 75 to 150 ° C.   The solvent recovery apparatus according to any one of claims 1 to 3, wherein the flow path of the solvent-containing gas for solvent recovery is in the order of pre-cooling means, water cooling means, and condenser.   5. The solvent recovery apparatus according to claim 1, wherein the refrigerant supplied to the condenser is continuously supplied from a direct expansion type refrigerator system.

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