JP2012081411A - Solvent dehydrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device which can achieve continuous dehydration of an organic solvent using an adsorbent principally without the need of exchange of the adsorbent, and can constantly remove water from a large amount of an organic solvent.SOLUTION: In a solvent dehydrator, the organic solvent is introduced into and made in contact with the absorbent, and then water contained in the organic solvent is adsorbed and removed. The solvent dehydrator includes an adsorption tank of a double pipe structure filled with the adsorbent, a depressurizer for reducing the pressure inside the adsorption tank, and a heater for heating the adsorption tank.

Description

  The present invention relates to an apparatus for removing water by removing moisture from an organic solvent, in particular, a used organic solvent generated from various factories or research facilities, or a solvent recovered from an organic solvent-containing gas using a solvent recovery apparatus. It is an apparatus used for dehydration treatment of the solvent for reuse.

  Conventionally, a distillation dehydration apparatus has been widely used as an apparatus for removing water from an organic solvent to dehydrate the solvent. That is, it is an apparatus that can obtain a high-purity organic solvent by evaporating the solvent by heating and fractionating the organic solvent and impurities using the difference in boiling point.

  However, since the distillation dehydration apparatus is a large apparatus, a large installation space is required, and both initial cost and running cost are high. In addition, an organic solvent having a boiling point close to that of water cannot be separated by distillation.

  In order to solve such a problem, there is known a method of removing impurities by passing an organic solvent through an adsorption tower packed with an adsorbent such as zeolite, ion exchange resin, molecular sieves, and activated alumina (for example, , See Patent Document 1), when a large amount of organic solvent is dehydrated, a large amount of adsorbent is required. In addition, since the adsorbent must be replaced when the adsorbent is in a breakthrough state, the labor for replacing the adsorbent and the running cost increase, which is an effective means at the laboratory level. It was not satisfactory to dehydrate a large amount of organic solvent recovered from

  Furthermore, a membrane separation apparatus can be cited as a technique that has attracted attention in recent years (see, for example, Patent Document 2). If this method is used, it can be separated by molecular sieving if the molecular size is different from that of water. However, this method is not applicable to all organic solvents, and depending on the organic solvent, membrane degradation may be significant and dehydration may be difficult. there were.

JP 2000-225316 A JP 7-39717 A

  The present invention has been made against the background of the problems of the prior art, and realizes continuous dehydration of an organic solvent using an adsorbent. Basically, it is not necessary to replace the adsorbent, and moisture is removed from a large amount of organic solvent. It is an object of the present invention to provide an apparatus that can be removed stably.

In order to solve the problems of the prior art, the present invention has finally been completed as a result of intensive studies. That is, the present invention is as follows.
1. A solvent dehydration device that adsorbs and removes water contained in an organic solvent by introducing an organic solvent into the adsorbent and bringing it into contact with the adsorbent, and depressurizes the adsorption tank filled with the adsorbent and the inside of the adsorption tank. A solvent dehydrator having a decompressor and a heating device for heating the adsorption tank.
2. 2. The solvent dewatering apparatus according to 1 above, wherein a cooling condenser is provided between the adsorption tank and the decompressor.
3. 3. The solvent dehydration apparatus according to 1 or 2 above, which has an inert gas introduction path for introducing an inert gas into the adsorption tank.
4). 4. The solvent dehydrator according to any one of 1 to 3 above, wherein the adsorbent contains at least one member selected from the group consisting of ion exchange resin, activated alumina, molecular sieves, and silica gel.
5. 5. The solvent dehydrating apparatus according to any one of 1 to 4 above, wherein the adsorbent is a cation exchange resin having at least one of a hydrogen ion form, a sodium form, and an alkanolamine form.
6). 6. The solvent dehydrating apparatus according to 5 above, wherein the cation exchange resin is granular or fibrous.
7). There are at least two adsorption tanks. One tank introduces an organic solvent containing water from the treated solvent introduction path, and adsorbs the moisture in the organic solvent to the adsorbent. The desorption process which desorbs the water | moisture content which carried out and discharge | emits it from an adsorption tank decompression path | route is implemented, Each adsorption tank transfers these processes sequentially, Dehydrating an organic solvent in any one of said 1-6 Solvent dehydrator.

  The solvent dehydrating apparatus according to the present invention can remove a large amount of water continuously with high efficiency, and basically does not require replacement of the adsorbent, so that the organic solvent can be stably manufactured at high cost with low cost. Water inside can be removed. Moreover, the desorption time is shortened by making the inside of the adsorption tank highly efficient desorption by decompression and heating, which is economical.

It is a solvent dehydrating apparatus of a two-tank vacuum desorption system, which is an example of a preferred embodiment of the present invention. This is a high-efficiency desorption-type solvent dehydration apparatus that further enhances the effect of the adsorption tank two-tank vacuum desorption system, which is an example of a preferred embodiment of the present invention. It is an example of the solvent collection | recovery processing apparatus using activated carbon fiber.

Hereinafter, a solvent dehydrating apparatus according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is an example of a preferred embodiment of the present invention. In the solvent dehydrating apparatus illustrated in FIG. 1, an organic solvent containing moisture is introduced from the solvent tank 12 to be treated into the adsorbent 11 through the solvent introduction path 13 by the solvent feed pump 17. A dehydration process facility that adsorbs and dehydrates the adsorbent 11, and the adsorbent 11 is heated by the heating device 16, and the adsorber 15 is depressurized by the decompressor 24, and is adsorbed by the adsorbent 11 from the adsorbent 11 through the adsorber depressurization path 22 It is equipped with a desorption process facility that drains the water that was stored.

  The solvent dehydrating apparatus of the present invention is preferably a solvent dehydrating apparatus that alternately performs such steps. It is because a dehydration process can be performed continuously by adopting such a structure.

  In the desorption step, the heating device 16 is not particularly limited as long as it can be heated from the outside of the adsorption tank, but is preferably a device that is heated as soon as possible. For example, a heating device using steam having a large latent heat capacity is preferable. Further, the desorption temperature is not particularly limited, but is preferably higher than the boiling point of water under reduced pressure at that time.

  In the desorption process, the decompressor is not particularly limited, but the decompression condition is preferably 1 to 80 kPa. If it exceeds 80 kPa, the depressurization pressure is high, so that the desorption efficiency is lowered. For this reason, for efficient desorption considering the size of the decompressor, the decompression condition is more preferably 10 to 50 kPa.

  FIG. 2 is an example of a more preferred embodiment of the present invention. The solvent dehydrator illustrated in FIG. 2 introduces the inert gas 20 into the adsorption tank 15 through the inert gas introduction path 21 in the desorption process, and further, the adsorption tank pressure reduction path 22 between the adsorption tank and the pressure reducer, and the downstream of the pressure reducer. The desorption efficiency can be further increased by providing the cooling and condensing device 25 in

  In the desorption process, it is preferable to introduce an inert gas 20. This is because the heat conduction efficiency to the adsorbent 11 is dramatically improved by introducing the inert gas 20. However, if the flow rate of the inert gas 20 is too large, the depressurization pressure is increased and the desorption efficiency may be lowered. Therefore, the flow rate of the inert gas 20 is determined by the space velocity SV of the adsorption tank 15 = 100 to 1000 / hr. preferable. An example of the inert gas is nitrogen.

  In the desorption step, it is preferable that the water vapor desorbed from the adsorbent 11 is condensed and recovered into water by the cooling condenser 25 provided between the adsorption tank and the decompressor. Since the organic solvent and water in the gas can be removed before the gas is introduced into the decompressor 24, the amount of gas discharged by the decompressor can be reduced, and the capacity of the decompressor can be reduced. This is because it can.

  In the desorption process, when the exhaust gas of the decompressor is discharged out of the system, a small amount of solvent is contained in the desorbed gas, so the cooling condenser 25 may be installed downstream of the decompressor. Further, the treatment may be performed by a commonly used gas processing device such as a direct combustion device, a catalytic combustion device, a regenerative combustion device or the like, a solvent recovery device using activated carbon fiber, or a scrubber.

  The adsorbent according to the present invention includes zeolite, activated alumina, silica gel, ion exchange resin and the like, and is not particularly limited, but is preferably a cation exchange resin from the viewpoint of performance. Cation exchange resin has an adsorption mechanism different from that of zeolite, silica gel and activated alumina, and absorbs moisture in the resin and swells in the gel. Therefore, it is an effective moisture adsorbent with a very large moisture adsorption capacity.

  The cation exchange resin includes a hydrogen ion form, a sodium form, and an alkanolamine form, and is not particularly limited. However, a cation exchange resin in which a sulfonic acid group is coordinated is used. preferable. Since the cation exchange resin has an ion exchange group such as a sulfonic acid group on the resin surface, the cation exchange resin is an effective water adsorbent having the feature that only the water can be adsorbed without adsorbing the organic solvent.

  Examples of the structure of the adsorbent according to the present invention include granular, powdery, porous, honeycomb, and fibrous forms, and are not particularly limited, but are preferably granular or fibrous. When the organic solvent containing water passes through the adsorbent, the larger the surface area of the adsorbent, the higher the contact efficiency between the adsorbent and moisture and the higher the water adsorption capacity. , Granular or fibrous.

  In the solvent dehydrating apparatus of the present invention, it is preferable to have at least two adsorption tanks. When one adsorption tank is in a dehydration process in which an organic solvent containing moisture is introduced from the treated solvent introduction path and the adsorbent adsorbs moisture in the organic solvent to dehydrate, at least one of the remaining adsorption tanks is adsorbed. This is because the desorption process in which moisture adsorbed on the material is desorbed and discharged from the adsorption tank depressurization path, and each adsorption tank sequentially moves through these processes, so that the organic solvent can be dehydrated continuously. When there are three or more adsorption tanks, it is preferable from the viewpoint of dehydration efficiency that two or more adsorption tanks are used as the adsorption process and the remaining one adsorption tank is used as the desorption process.

  The organic solvent that can be dehydrated in the present invention is ethyl acetate, methyl acetate, propyl acetate, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, methylene chloride, chloroform, trichloroethane, propanol, butanol, acetic acid, propionic acid, or a mixture thereof. It is not limited and can be applied in various organic solvents.

  The organic solvent that can be dehydrated in the present invention includes a gas containing an organic solvent discharged from factories in various fields, such as a dry laminating process for laminating films, and an organic solvent that is recovered using a solvent recovery processing device. Is mentioned.

  For example, in the solvent recovery processing apparatus as shown in FIG. 3, the solvent-containing gas 31 is introduced into the adsorption tank 33 by the adsorption fan 32 and the organic solvent is adsorbed by the activated carbon fiber element 34 filled in the adsorption tank 33. The organic solvent is desorbed by introducing the steam 35 into the activated carbon fiber element 34 and the adsorption step that is exhausted to the outside air as the clean gas 36. The condenser 39 cools and condenses, and the separator 39 separates the solvent and water. There is a desorption process for recovering the recovered solvent 40, and the system can be continuously processed by alternately performing the adsorption process and the desorption process. Since this type of solvent recovery processing equipment uses steam for desorption and cools and condenses, moisture is mixed into the recovered solvent. Therefore, by applying the apparatus of the present invention, moisture is effectively removed from the recovered solvent. Can be removed.

  EXAMPLES Hereinafter, although the detail of this invention is further demonstrated from an Example, this invention is not limited to these Examples. The evaluation was performed by the following method.

(Evaluation method for removing water from organic solvents)
Various organic solvents containing water having a concentration of 3% by weight were flowed at a constant flow rate, and the moisture concentration in the sampled organic solvent after the dehydration treatment was measured.

(Water concentration evaluation method)
The moisture concentration at the inlet and outlet of the adsorbent was measured by the Karl Fischer moisture measurement method.

[Example 1]
In the solvent dehydrating apparatus of FIG. 1, a cation exchange resin (Na type, sulfonic acid group, Muromac DW2-1, manufactured by Muromachi Technos Co., Ltd.) having an average particle size of 1 mm as an adsorbent 11 is filled in a 22 kg adsorption tank 15 and moisture is contained. A mixed solution of 3% by weight, 94% by weight of ethyl acetate, and 3% of ethanol was introduced into the adsorption tank 15 through the solvent introduction path 13 at 200 L / hr. The adsorption temperature was 30 ° C. As a result of confirming the time-dependent change in the outlet moisture concentration at that time, the initial outlet moisture concentration was 0.03% by weight, and the time until the outlet moisture concentration reached 2% by weight was 120 minutes. The initial average moisture concentration was 0.5% by weight. Further, the moisture adsorption amount (q *) was 0.6 (g / g-resin), indicating a good moisture adsorption amount.

  Next, when the heating device 16 in the desorption process is set to 100 ° C. and the reduced pressure is adjusted to 10 kPa, the 100% desorption time for desorbing q * to 0 g / g-resin is 300 minutes, and q * is Since the 60% desorption time for desorption up to 0.24 g / g-resin was 120 minutes, the cycle was alternated between the tanks by switching between the dehydration process 120 minutes and the desorption process 120 minutes.

  The mixed solvent dehydrated by the solvent dehydrating apparatus of the present example has an average water concentration of 1.0% by weight or less at the outlet in the mixed solvent even if it is repeated from 10 cycles to 30 cycles of the dehydration / desorption cycle of the dehydration step → desorption step It was possible to maintain Since the dehydration and desorption were continuously performed, the performance was not deteriorated, and the solvent dehydration process could be stably performed with high efficiency.

[Example 2]
In the solvent dehydrating apparatus of FIG. 2, a cation exchange resin (Na type, sulfonic acid group, Muromac DW2-1, manufactured by Muromachi Technos Co., Ltd.) having an average particle size of 1 mm as an adsorbent 11 is filled in a 22 kg adsorption tank 15 and moisture is contained. A mixed solution of 3% by weight, 94% by weight of ethyl acetate, and 3% of ethanol was introduced into the adsorption tank 15 through the solvent introduction path 13 at 200 L / hr. The adsorption temperature was 30 ° C. As a result of confirming the time-dependent change in the outlet moisture concentration at that time, the initial outlet moisture concentration was 0.03% by weight, and the time until the outlet moisture concentration reached 2% by weight was 120 minutes. The initial average moisture concentration was 0.5% by weight. Further, the moisture adsorption amount (q *) was 0.6 (g / g-resin), indicating a good moisture adsorption amount.

  Next, the heating device 16 in the desorption process was set to 100 ° C., the cooling condenser 25 was adjusted to an outlet temperature of 37 ° C. using cooling water, and the reduced pressure was adjusted to 10 kPa. Further, when nitrogen was introduced into the inert gas introduction path 21 at SV = 1000 / hr as the inert gas 21, the 100% desorption time for q * to be desorbed to 0 g / g-resin was 160 minutes, and q * Since the 70% desorption time for desorbing up to 0.18 g / g-resin was 120 minutes, the cycle was alternated between the tanks by switching between the dehydration process 120 minutes and the desorption process 120 minutes.

  The mixed solvent dehydrated by the solvent dehydrating apparatus of this example has an outlet average water concentration of 0.9% by weight or less even if it is repeated from 10 cycles of the dehydration step to the desorption cycle of the desorption step up to 30 cycles. It was possible to maintain Since the dehydration and desorption were continuously performed, the performance was not deteriorated, and the solvent dehydration process could be stably performed with high efficiency.

[Example 3]
In the solvent dehydrating apparatus of FIG. 1, a cation exchange resin (Na type, sulfonic acid group, Muromac DW2-1, manufactured by Muromachi Technos Co., Ltd.) having an average particle size of 1 mm as an adsorbent 11 is filled in a 22 kg adsorption tank 15 and moisture is contained. A mixed solution of 0.2% by weight, 97% by weight of methylene chloride and 2.8% by weight of methanol was introduced into the adsorption tank 15 through the solvent introduction path 13 at 50 L / hr. The adsorption temperature was 30 ° C. As a result of confirming the change with time in the outlet moisture concentration at that time, the initial outlet moisture concentration was 0.001% by weight, and the time until the outlet moisture concentration reached 0.05% by weight was 120 minutes. The initial average water concentration of the solvent was 0.01% by weight. Further, the moisture adsorption amount (q *) was 0.08 (g / g-resin), indicating a good moisture adsorption amount.

  Next, when the heating device 16 in the desorption process is set to 100 ° C. and the reduced pressure is adjusted to 10 kPa, the 100% desorption time for q * to be desorbed to 0 g / g-resin is 130 minutes, and q * is Since the 90% desorption time for 0.008 g / g-resin was 120 minutes, the cycle was alternated between the tanks by switching between the dehydration process 120 minutes and the desorption process 120 minutes.

  In the mixed solvent dehydrated by the solvent dehydrating apparatus of this example, the average moisture concentration at the outlet in the mixed solvent is 0.02% by weight or less even if the dehydration / desorption cycle of the dehydration process → desorption process is repeated from 10 cycles to 30 cycles. It was possible to maintain Since the dehydration and desorption were continuously performed, the performance was not deteriorated, and the solvent dehydration process could be stably performed with high efficiency.

[Comparative Example 1]
In the solvent dehydrating apparatus of FIG. 2, a cation exchange resin (Na type, sulfonic acid group, Muromac DW2-1, manufactured by Muromachi Technos Co., Ltd.) having an average particle size of 1 mm as an adsorbent 11 is filled in a 22 kg adsorption tank 15; A mixed solution of 3% by weight of water, 94% by weight of ethyl acetate, and 3% of ethanol was introduced into the adsorption tank 15 through the solvent introduction path 13 at 200 L / hr. The adsorption temperature was 30 ° C. As a result of confirming the time-dependent change in the outlet moisture concentration at that time, the initial outlet moisture concentration was 0.03% by weight, and the time until the outlet moisture concentration reached 2% by weight was 120 minutes. The initial average moisture concentration was 0.5% by weight. Further, the moisture adsorption amount (q *) was 0.6 (g / g-resin), indicating a good moisture adsorption amount.

  Next, the heating device 16 in the desorption process was eliminated, the cooling condenser 25 was adjusted to an outlet temperature of 37 ° C. using cooling water, and the reduced pressure was adjusted to 20 kPa. Moreover, when nitrogen was introduced into the inert gas introduction path 21 at SV = 1000 / hr as the inert gas 21, it was not possible to desorb and the adsorbent was frozen. This is because heat is absorbed as heat of vaporization at the time of desorption. The same result is expected when the temperature is set lower than the boiling point of water under the reduced pressure.

  The solvent dehydrating apparatus of the present invention realizes continuous dehydration of the solvent, basically does not require replacement of the adsorbent, and is a dehydrating apparatus that can remove a large amount of water with high efficiency and stability. Material replacement work can be omitted, costs can be reduced, and moisture can be removed stably. Furthermore, by devising the desorption process, the running cost can be greatly reduced, which is economical. For this reason, it can be used for dehydration of the solvent recovered from exhaust gas generated from a wide range of fields such as laboratories and factories using a solvent recovery processing apparatus, and contributes greatly to the industry.

DESCRIPTION OF SYMBOLS 11 Adsorbent 12 Solvent solvent tank 13 Solvent solvent introduction path 14 Process solvent tank 15 Adsorption tank 16 Heating device 17 Solvent feed pump 20 Inert gas 21 Inert gas introduction path 22 Adsorption tank decompression path 23 Return solvent path 24 Decompression Machine 25 Cooling condenser 26 Condensate tank 31 Solvent-containing gas 32 Adsorption fan 33 Adsorption tank 34 Activated carbon fiber element 35 Steam 36 Clean gas 37 Damper 38 Condenser 39 Separator 40 Recovery solvent

Claims (7)

  A solvent dehydration device that adsorbs and removes water contained in an organic solvent by introducing an organic solvent into the adsorbent and bringing it into contact with the adsorbent, and depressurizes the adsorption tank filled with the adsorbent and the inside of the adsorption tank. A solvent dehydrator having a decompressor and a heating device for heating the adsorption tank.   The solvent dehydrating apparatus according to claim 1, further comprising a cooling condenser between the adsorption tank and the decompressor.   The solvent dehydration apparatus according to claim 1, further comprising an inert gas introduction path for introducing the inert gas into the adsorption tank.   The solvent dehydrating apparatus according to any one of claims 1 to 3, wherein the adsorbent includes at least one member selected from the group consisting of an ion exchange resin, activated alumina, molecular sieves, and silica gel.   The solvent dehydrating apparatus according to any one of claims 1 to 4, wherein the adsorbent is a cation exchange resin having at least one of a hydrogen ion form, a sodium form, and an alkanolamine form.   The solvent dehydrating apparatus according to claim 5, wherein the form of the cation exchange resin is granular or fibrous.   There are at least two adsorption tanks. One tank introduces an organic solvent containing water from the treated solvent introduction path, and adsorbs the moisture in the organic solvent to the adsorbent. The desorption process which desorbs the water | moisture content which carried out and discharge | emits it from an adsorption tank decompression path | route is implemented, and each adsorption tank dehydrates an organic solvent continuously, shifting these processes sequentially. Solvent dehydration equipment.