JP2007111621A - Recovering apparatus and recovering method of solvent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently recover a washing solvent from drying wind obtained by drying the washing solvent adhering to a work piece at a drying process 2; and to prevent washing solvent-containing air from being discharged to atmospheric air. <P>SOLUTION: The drying wind is circulated in a drying wind circulation circuit 4 to form a closed circuit; a part of the drying wind is branched from a branching circuit 9 linked to the circulation circuit 4; the washing solvent is recovered from the branched drying wind by a recovering apparatus 8; the drying wind from which the washing solvent is recovered is again joined to the circulation circuit 4 via a joining circuit 10 and further the thus-recovered washing solvent is again used as the washing solvent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention belongs to the technical field of a solvent recovery apparatus and recovery method for efficiently recovering a solvent from dry air blown to forcefully dry the solvent adhering to a workpiece.

Today, workpieces manufactured in factories (processed products, such as electrical and electronic parts such as chips, printed boards, relays, and capacitors, and mechanical parts such as gears, bearings, and pressed parts are exemplified. The same shall apply hereinafter) may be washed using a solvent. Examples of such solvents include chlorine-containing solvents such as trichloroethane, trichloroethylene (tricylene), carbon tetrachloride, fluorine-containing solvents such as freon, and hydrocarbons such as cyclohexane. There are various types such as alcoholic solvents such as methanol solvents and methanol.
And since such a solvent generally vaporizes at normal temperature, the solvent which adheres to these workpieces is used on the spot where the workpiece is washed with these solvents or the adhesive or solid agent impregnated in the workpiece is solidified. It is required to forcibly dry, and the air thus forcibly dried contains a large amount of the vaporized solvent. And releasing such solvent-containing air as it is to the atmosphere is prohibited from the standpoint of environmental pollution, so that it can be discharged by performing solvent recovery processing and making the solvent concentration below a predetermined standard. It has become. As a technique for recovering such a solvent, there is known a technique for adsorbing and removing a solvent contained in the air using an adsorbent having a solvent adsorption ability such as activated carbon (for example, Patent Document 1).
By the way, recently, waiting for the solvent adhering to the work to dry by natural vaporization not only results in poor work efficiency, but if the solvent has been adhering to the work for a long time, the work surface may be stained or discolored. For this reason, it is required that the solvent be forcibly dried by blowing dry air onto the work using a blowing means such as a blower.
On the other hand, when workpieces are treated with adhesives, curing agents, coating agents, fluxes, processing oils, press oils, etc., or when these components are dissolved in solvents In such a case, the oil in which the oil is dissolved in the solvent is forcibly dried, but in the dry air in which the solvent in which the oil is dissolved is forcibly dried, not only the vaporized solvent but also the solvent is dissolved. It contains the oil that has been in the molecular level. And, if the solvent-containing air containing such oil is adsorbed as it is with the adsorbent, the adsorbent function of the adsorbent will be deteriorated at an early stage due to the oil adhering to the adsorbent surface and clogging. It will be. In addition, in the desorption process when recovering the solvent from the adsorbent that has adsorbed the solvent, the adsorbent is heated by using, for example, water vapor. At this time, the adsorbent is adsorbed on the oil adhering to the surface. There is a problem that the catalytic function acts to accelerate the reaction such as thermal decomposition or hydrolysis of the recovered solvent and deteriorate early.
Therefore, there is known one that recovers the solvent without using an adsorbent such as activated carbon (for example, Patent Document 2).
JP-A-6-304441 JP-A-9-117603

  By the way, in the case of recovering the vaporized solvent without using the adsorbent, the solvent-containing air is cooled to liquefy the solvent, and this is recovered. However, the liquefied solvent is recovered by the recovery means and recovered. Since the discharged air is exhausted to the atmosphere, it is necessary to recover it to a low concentration that satisfies the emission standards by increasing the recovery efficiency. As a result, the recovery efficiency is low only with one stage of cooling. There are problems such as the need to recover the solvent by cooling in two stages, three stages, and a plurality of stages, resulting in an increase in the size of the entire apparatus.

The present invention has been created in view of the above-described circumstances and has been created for the purpose of solving these problems. The invention of claim 1 is directed to drying a solvent attached to a workpiece, The drying air is circulated through the drying air circulation circuit, and the drying air circulation circuit is provided with a diversion circuit for diverting a part of the drying air. The solvent recovery device is characterized in that the circuit is provided with a solvent recovery means for cooling and recovering the solvent from the diverted dry air.
A second aspect of the present invention is the solvent recovery apparatus according to the first aspect, further comprising a merging circuit for merging the dry air from which the solvent has been recovered by the solvent recovery means into the dry air circulation circuit.
A third aspect of the present invention is the solvent recovery apparatus according to the first or second aspect, wherein the drying air circulation circuit is provided with a heating means for heating the drying air blown to the workpiece.
According to a fourth aspect of the present invention, in any one of the first to third aspects, the shunt circuit is provided with precooling means for precooling the drying air before reaching the solvent recovery means. This is a solvent recovery device.
According to a fifth aspect of the present invention, in any one of the first to third aspects, the drying air circulation circuit is provided with pre-cooling means for pre-cooling the drying air that has dried the work before reaching the diversion circuit. This is a solvent recovery device.
In the invention of claim 6, in order to dry the solvent adhering to the workpiece, the drying air is blown to the workpiece and forced drying is performed. The solvent recovery method is characterized in that the solvent is recovered by cooling from a part of the dry air diverted from the wind circulation circuit.
A seventh aspect of the present invention is the solvent recovery method according to the sixth aspect, wherein the dry air from which the solvent has been recovered is merged with the dry air circulation circuit.
The invention of claim 8 is the solvent recovery method according to claim 6 or 7, wherein the heated dry air is blown onto the workpiece.
The invention of claim 9 is characterized in that, in any one of claims 6 to 8, a part of the divided dry air is pre-cooled before the solvent is recovered from the diverted dry air. This is a solvent recovery method.
A tenth aspect of the present invention is the method for recovering a solvent according to any one of the sixth to eighth aspects, wherein a part of the drying air is diverted after pre-cooling the drying air obtained by drying the workpiece. It is.

By using the invention of claim 1 or 6, it is only necessary to cool and recover the solvent from a part of the dry air that has been diverted, and no adsorbent such as activated carbon is used. However, while the solvent can be continuously recovered over a long period of time, the amount of solvent to be recovered is reduced. As a result, the solvent recovery means may be arranged in a single stage, and the apparatus can be made compact and compact.
According to the invention of claim 2 or 7, since the dry air from which the solvent has been recovered is used again after being joined to the dry air circulation circuit, the solvent recovery capability is not required to be discharged to the atmosphere. Although the recovery efficiency is high, the solvent recovery means itself does not require a high recovery efficiency and can be simplified.
According to the invention of claim 3 or 8, heated drying air is blown against the workpiece, so that the drying capacity can be increased.
According to the invention of claim 4 or 9, the recovery of the low boiling point solvent such as chlorofluorocarbon can be performed without cooling the drying air circulating in the drying air circulation circuit. The recovery efficiency of the solvent from can be improved while maintaining the solvent capacity.
According to the invention of claim 5 or 10, the recovery of the high boiling point solvent such as toluene can be performed by cooling the drying air circulation circuit, and the recovery efficiency of the high boiling point solvent can be improved.

  Next, an embodiment of the present invention will be described based on the first embodiment described in FIG. In the figure, reference numeral 1 denotes a workpiece cleaning process. In the cleaning process 1, for example, the workpiece is soaked in a cleaning solvent, or the cleaning solvent circulated and supplied is cleaned in a state where it is applied like a shower. It has become. Then, the work cleaned in the cleaning process 1 moves to the drying process 2, and the cleaning solvent adhering to the work in the drying process 2 is forcibly dried. Then, the work after the cleaning solvent is dried is supplied to the next step 3, and if the work is a final product, it is shipped by packing or the like, and if it is an intermediate product, further processing is added.

  The drying step 2 is incorporated in a circulation circuit (circulation air passage) 4 for circulating the drying air (drying gas). The circulation circuit 4 includes a blower 5 on the lower side of the drying process 2 and is set so that the circulating air is forced to flow (blow) through the circulation circuit 4. The circulation circuit 4 is provided with a pre-cooling condenser (pre-cooling agglomerator) 6 that is cooled by a cooler (chiller or refrigerator) 6 a on the lower side of the blower 5, and a heater on the lower side of the pre-cooling condenser 6. 7 is provided, and the drying air heated by the heater 7 is blown into the drying step 2 as hot air and blown to the work, thereby forcibly drying the work. Thus, a circulation circuit 4 for dry air is formed.

  8 is a recovery device for recovering the solvent by cooling the dry air containing the solvent. As the recovery device 8, for example, a general-purpose deep-cold pressure type recovery device is adopted. A diversion circuit (diversion air passage) 9 and a confluence circuit (merging air passage) 10 connected to the upper side and the lower side of 8 are an intermediate air passage between the precooling condenser 6 and the heater 7 of the circulation circuit 4. In 4a, it is provided so that it diverges from the circulation circuit 4 at each position on the upper side and the lower side and joins the circulation circuit 4. The recovery device 8 divides a part (for example, 10%) of the drying air pre-cooled by the pre-cooling condenser 6, recovers the cleaning solvent contained in the split drying gas, and the cleaning solvent The drying gas (gas containing a low-concentration cleaning solvent) collected is joined to the circulation circuit 4.

And in this Embodiment, about the washing | cleaning solvent collect | recovered with the precooling condenser 6, what was stored by the condensate tank 11 is supplied to the water separator 13 with the pump 12. FIG. Further, the cleaning solvent recovered by the recovery device 8 is supplied to the water separator 13 by pump means (not shown) provided in the recovery device 8, and the cleaning solution supplied to the water separator 13 is water here. Is separated, and the water-separated product is recovered and reused in the washing process as a washing solvent.
The circulation circuit 4 and the junction circuit 10 are provided with adjustment valves 13 and 14 for adjusting the circulation air volume.

  In the first embodiment of the present invention configured as described above, the workpiece cleaned with the cleaning solvent in the cleaning step 1 is subjected to forced drying of the cleaning solvent adhering (remaining) in the drying step 2. However, the drying air circulates in a closed circuit called the drying air circulation circuit 4, and what is heated on the upper side of the circuit in the drying process 2 is blown to the work and forcedly dried. , Drying efficiency is improved.

  And the drying air which dried the workpiece | work is pre-cooled and condensed by the pre-cooling condenser 6 arrange | positioned to the circuit lower side of the drying process 2, Thereby, a part of the cleaning solvent of the gasification state contained in the drying air is liquefied. A part of the pre-cooled and condensed drying air is sent to the recovery device 8 by the diversion circuit 9, where the cleaning solvent is cooled and recovered. Thus, in the embodiment of the present invention, the gasified cleaning solvent contained in the drying air is not recovered from all the drying air that has dried the cleaning solvent adhering to the work, Since the drying air is diverted and the divided drying air is cooled to recover the washing solvent, it is not necessary to increase the size of the collecting device 8 or arrange it in multiple stages, and the device can be made compact. . Moreover, since the recovery device 8 does not recover the solvent with an adsorbent such as activated carbon but recovers the solvent by cooling, when the oil is mixed in the dry air, the oil is also recovered by using the adsorbent. As in the case, the adsorbent can be made without clogging at an early stage.

Moreover, since the drying air from which the cleaning solvent has been collected merges with the circulation circuit 4 and is used again as the drying air, the cleaning solvent is recovered, but the whole becomes a closed circuit and is washed to the outside air. The air from which the solvent is recovered is not exhausted. As a result, the recovery capability of the cleaning solvent in the recovery device 8 can be reduced to a high performance having a low level up to the discharge standard to the atmosphere, or no need to provide multiple recovery devices.
In this case, the solvent recovery is carried out in the circulation circuit 4 which is a closed circuit, and the amount of water in the circulation circuit 4 is minimized because little or no fresh air is introduced. As a result, there is an advantage that the hydrolysis of the recovered solvent is prevented from being promoted and the water content in the recovered solvent can be reduced. Further, the solvent recovery is performed in the diversion circuit 9 branched from the circulation circuit 4, and the dried air collected from the solvent is again joined to the circulation circuit 4 to be circulated, so that the exhaust concentration can be made almost zero. Therefore, in order to exert such a function using an adsorbent such as activated carbon, there is no need for an existing high-performance adsorbent that has adsorption / desorption performance that makes exhaust concentration zero. If the solvent recovery performance in the high concentration range, which is easy to recover, is sufficient, the equipment can be simplified, and the equipment itself can be simplified. As a result, the overall equipment cost for solvent recovery is reduced. In addition, a significant reduction in running costs can be achieved.
In addition, the solvent recovery equipment capacity may be set to a solvent recovery capacity that is commensurate with the maximum amount of solvent generated in the work line. By doing so, in the circulation circuit 4, the solvent concentration extremely increases. Therefore, it becomes stable and can be circulated and dried efficiently. Incidentally, such an excellent effect is also exhibited in the second embodiment described later.

  In addition, since the drying air blown to the work in the drying process 2 is heated in the heating process 7, it is possible to prevent the drying time from becoming too early and causing the work surface to be stained or discolored.

In the embodiment, the precooling condenser 6 is provided in the circulation circuit 4, and the washing solvent is advantageous for recovering a high boiling point solvent such as toluene. The high-boiling cleaning solvent is easier to condense than the low-boiling cleaning solvent. Therefore, by providing the pre-cooling condenser 6 in the circulation circuit 4 and performing the condensation, the burden on the recovery device 8 can be reduced. On the other hand, in the case of a washing solvent having a low boiling point such as Freon, even if the pre-cooling condenser 6 is provided in the circulation circuit 4, the effect of condensation cannot be expected so much as in the second embodiment shown in FIG. There is an advantage that the pre-cooling condenser 6 can be reduced in size because the amount of dry air condensed is reduced by being provided in the diversion circuit 9.
Furthermore, it goes without saying that the present invention is not limited to the recovery of the cleaning solvent as in the above-described embodiment, and can be applied in the fields of adhesion, welding, printing, chemistry, storage, and other solvent use. Yes.

It is a collection circuit diagram of the work washing solvent of a first embodiment. It is a collection circuit diagram of the work washing solvent of a second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Washing process 2 Drying process 4 Drying air circulation circuit 6 Pre-cooling condenser 7 Heating process 8 Collection | recovery apparatus 9 Shunt circuit 10 Merge circuit

Claims (10)

  In order to dry the solvent adhering to the workpiece, the drying air is forced to dry by blowing the drying air on the workpiece, and the drying air circulates in the drying air circulation circuit. A solvent collecting apparatus comprising: a diversion circuit for diverting a part of the solvent; and a solvent collecting means for cooling and collecting the solvent from the diverted dry air.   2. The solvent recovery apparatus according to claim 1, further comprising a merging circuit for merging the dry air from which the solvent has been recovered by the solvent recovery means with the drying air circulation circuit.   3. The solvent recovery apparatus according to claim 1, wherein the drying air circulation circuit is provided with heating means for heating the drying air blown to the workpiece.   4. The solvent recovery apparatus according to claim 1, wherein the shunt circuit is provided with pre-cooling means for pre-cooling the drying air before reaching the solvent recovery means.   4. The solvent according to claim 1, wherein the drying air circulation circuit is provided with pre-cooling means for pre-cooling the drying air that has dried the work before reaching the diversion circuit. Recovery device.   In order to dry the solvent adhering to the work, the dry air is circulated through the dry air circulation circuit and is divided from the dry air circulation circuit in the configuration of forced drying by blowing the dry air onto the work. A method for recovering a solvent, wherein the solvent is recovered by cooling from a part of the drying air.   7. The method for recovering a solvent according to claim 6, wherein the drying air from which the solvent has been recovered is joined to the drying air circulation circuit.   8. The method for recovering a solvent according to claim 6 or 7, wherein heated dry air is blown onto the workpiece.   9. The method for recovering a solvent according to claim 6, wherein a part of the diverted dry air is pre-cooled before the solvent is recovered from the diverted dry air.   9. The method for recovering a solvent according to claim 6, wherein a part of the drying air is diverted after pre-cooling the drying air obtained by drying the workpiece.

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