JP6677006B2 - Solvent recovery device - Google Patents

Description

  The present invention relates to a solvent recovery device.

As a conventional solvent recovery apparatus, a bottom portion having a circulation line for a can solution in which a heat exchange reboiler as an evaporator (for example, a heat exchange reboiler of a type in which a can solution is upflowed) is installed, BACKGROUND ART Distillation purification using a distillation column having a rectification unit in which a rectification member installed above a bottom is built in or internally is generally well known.
Further, as a conventional apparatus, for example, an apparatus described in Patent Document 1 is known.
Patent Literature 1 discloses a line (a1) for extracting a bottom liquid from a lower portion of a bottom of a tower to an inlet of a falling film reboiler, and a falling film reboiler for partially evaporating the bottom liquid. (A2) and a vapor supply line (a3) for supplying a vapor flow flowing out from the outlet of the falling-film reboiler and an unevaporated bottom liquid to the bottom of the column, in this order. Bottom (A) comprising a circulation line (a), and a cross section of the bottom of the tower above the bottom (A) for rectifying the vapor flow rising from the bottom (A). A rectifying section (B) composed of a rectifying tool provided in the whole, and a rectifying member provided therein or incorporated therein for distilling and purifying a steam flow further rising beyond the rectifying section (B). A distillation purification device including a distillation column consisting of a rectification section (C) It has been mounting.

As a conventional method, a method described in Patent Document 2 is known.
US Pat. No. 5,047,097 discloses a method for reducing entrainment of solids and liquids in a vapor flow exiting a separation vessel, wherein the separation is carried out in a separation vessel having an inner surface, at least one inlet and at least one vapor outlet. Introducing a stream, wherein the stream is introduced through at least one inlet and flows tangentially to an inner surface of the separation vessel, wherein the stream includes a non-vaporized material portion and a vaporized material portion; Here, introducing the stream into the separation vessel slows down the stream; separating the vapor flow from the stream in the separation vessel, wherein the vapor flow is a non-uniform vapor velocity within the separation vessel. Allowing the vapor flow to exit the separation vessel through at least one vapor outlet; and then reducing the speed of the stream. The method comprising maintaining the velocity, whereby the stream flows tangentially along the inner surface, and entrainment of the non-vaporized portion of the stream by the vaporized material flow is minimized. Have been.

JP 2001-9201A JP-T-2004-528179

  An object of the present invention is to provide a solvent recovery device in which particles are less mixed in the recovery solvent.

The above object of the present invention has been solved by means described in the following <1>. It is described below together with the preferred embodiment <2>.
<1> A heating tank having a stirring unit and a heating unit, an evaporative gas passage unit, an evaporative gas condensing unit, a condensed liquid recovery unit, and a depressurizing unit, wherein the evaporative gas passage unit has different angles It is composed of two or more pipes, wherein the pipes in the evaporative gas passage section are installed with a gradient in a direction in which the liquid flows into the heating tank, and the pipes directly connected to the heating tank, A dead end provided at the end of the pipe opposite to the side to which the heating tank is connected with respect to the traveling direction of the evaporating gas, and a dead end provided on the heating tank side of the pipe relative to the dead end. A solvent recovery device having a connection portion with another pipe,
<2> The solvent recovery device according to <1>, wherein the number of the pipes directly connected to the heating tank is two or more.

According to the invention described in the above <1>, there is provided a solvent recovery apparatus in which particles are less mixed in the recovery solvent obtained by condensing and recovering the vaporized gas as compared with the case where the present configuration is not provided.
According to the invention described in the above <2>, there is provided a solvent recovery apparatus in which particles in the recovery solvent are less mixed than when the number of the pipes directly connected to the heating tank is one. You.

It is a schematic cross section which shows a suitable example of the solvent collection | recovery apparatus of this embodiment. It is a schematic cross section which shows another suitable example of the solvent collection | recovery apparatus of this embodiment. It is a schematic cross section which shows another suitable example of the solvent collection | recovery apparatus of this embodiment. It is a schematic cross section which shows another suitable example of the solvent collection | recovery apparatus of this embodiment. It is a schematic cross section which shows an example of the conventional solvent collection | recovery apparatus. It is a schematic cross section which shows another example of the conventional solvent collection | recovery apparatus. It is a schematic cross section which shows another example of the conventional solvent collection | recovery apparatus. It is a schematic cross section which shows another example of the conventional solvent collection | recovery apparatus. It is a schematic cross section which shows another example of the conventional solvent collection | recovery apparatus. It is a schematic cross section which shows another example of the conventional solvent collection | recovery apparatus.

Hereinafter, the present embodiment will be described.
In the present embodiment, the description “A to B” indicates not only a range between A and B but also a range including both ends A and B. For example, if “A to B” is a numerical range, it indicates “A or more and B or less” or “B or more and A or less”.
Further, “% by mass” and “parts by mass” have the same meanings as “% by weight” and “parts by weight”, respectively.

(Solvent recovery device)
The solvent recovery apparatus according to the present embodiment includes a heating tank having a stirring unit and a heating unit, an evaporative gas passage unit, an evaporative gas condensing unit, a condensed liquid recovery unit, and a decompression unit. Is composed of two or more pipes having different angles, and the pipes in the evaporative gas passage are installed with a gradient in a direction in which the liquid flows in the heating tank, and are directly connected to the heating tank. The pipe provided is a dead end provided at an end of the pipe opposite to the side to which the heating tank is connected with respect to the traveling direction of the evaporative gas, and the pipe is heated more than the dead end. It is characterized by having a connection portion with another pipe provided on the tank side.
Further, the solvent recovery device of the present embodiment is preferably a solvent recovery device that recovers a solvent from a mixture containing particles and a solvent, and is a solvent recovery device that recovers a solvent from a mixture containing particles, water and a solvent. Is more preferred.
The solvent used in combination with water preferably has a boiling point of 90 ° C. or lower, more preferably a boiling point of 30 ° C. to 90 ° C.
The particles are preferably particles having a volume average particle size of 10 nm to 200 μm, and more preferably particles having a volume average particle size of 10 nm to 50 μm.
Further, the particles may be solid particles or liquid particles, but are preferably solid particles after the solvent is recovered.

When removing the solvent, which is a low-boiling component, from the mixture containing the powder and the solvent by vacuum distillation, particles, particularly fine particles, are scattered at the same time as the bubbles are broken, and the vaporized gas is entrained by the stream of the solvent vapor. The present inventors have found that there is a problem of being mixed in the recovery section. Conventionally, process conditions such as temperature and decompression conditions have been controlled within a range in which the particles are not entrained in the gas flow of the evaporative gas, but this was not sufficient to suppress the particles from being mixed into the recovery solvent.
The present inventors have conducted a detailed study, by using a specific structure of the pipe in the evaporative gas passage section, a solvent recovery apparatus with less mixing of particles in the recovery solvent condensed and recovered the vaporized gas. I found what I could get.
Further, in the solvent recovery device of the present embodiment, there is no need to install a filter between the heating tank and the condensate recovery unit, and the evaporating gas passage unit and the evaporation gas passage unit as in the invention described in Patent Document 2. There is no need to install a liquid cyclone between the gas condensing section and the simple apparatus as described above is used.
Further, the solvent recovery device of the present embodiment has a large solvent recovery amount and a residue recovery amount from the heating tank, and the total amount is close to the total amount of the mixture charged into the solvent recovery device.

<Heating tank>
The solvent recovery device of the present embodiment has a heating tank having a stirring means and a heating means, and the heating tank is connected to an evaporative gas passage.
As the stirring means of the heating tank, a mechanical stirring means such as a mechanical stirrer is preferably exemplified.
Examples of the mechanical stirring means include a driving unit such as a motor, a stirring shaft connected to the driving unit, and a stirring blade provided on the stirring shaft.
As the stirring blade, an inclined paddle may be used, or a scraping blade having a half-pipe liquid-feeding stirring member may be used.
The material of the stirring blade is not particularly limited, and examples thereof include metal and polytetrafluoroethylene.

The heating means included in the heating tank is not particularly limited, and a known heating means is used, and for example, a jacket-type heating means such as a jacket-type heater is preferably used.
Further, it is preferable that the heating tank has not only a heating unit but also a cooling unit and a temperature adjusting unit.
As the cooling unit and the temperature adjusting unit, known units are used, and examples thereof include a jacket-type water cooling unit.
Among them, the heating tank preferably has a heating unit and a cooling unit, and more preferably has a jacket-type heating and cooling unit.
The heating temperature of the heating tank may be appropriately determined according to the reduced pressure conditions, the solvent used, and other components. For example, when the solvent to be recovered is an organic solvent, and water is included as another component in the mixture from which the solvent is recovered, a method of heating to a temperature equal to or higher than the boiling point of the organic solvent under a reduced pressure to be set is exemplified.

The material of the heating tank is not particularly limited as long as it has durability against reduced pressure, heat and solvent, but is preferably a metal from the viewpoint of cost, processability and heat conductivity. And more preferably stainless steel.
In addition, the surface of the heating tank may be subjected to a known surface treatment. For example, plating treatment, oxide film treatment, polytetrafluoroethylene treatment and the like can be mentioned.
The shape of the heating tank is not particularly limited, and may be any desired shape. For example, a hollow cylindrical shape, a hollow polygonal column shape, and the like can be given.
There is no particular limitation on the volume of the heating tank, and any volume may be used as long as it is a desired volume.
The connection position of the heating tank and the pipe of the evaporative gas passage is not particularly limited, but is preferably the upper part of the heating tank with the gravity direction being the lower part from the viewpoint of the efficiency of solvent recovery.
Further, it is preferable that an inner diameter of a pipe of the evaporative gas passage connected to the heating tank is smaller than an inner diameter of an upper part of the heating tank.
Furthermore, the connection position of the pipe with the heating tank is not particularly limited, and may be a central part or an end part of the upper part of the heating tank.
The number of the pipes directly connected to the heating tank may be one or more, but is preferably two or more, more preferably 2 to 8, and still more preferably 2 to 4, Particularly preferred is 2. When the content is in the above range, the amount of particles mixed in the recovered solvent is smaller.

<Evaporation gas passage section>
The solvent recovery device of the present embodiment has an evaporative gas passage, the evaporative gas passage is composed of two or more pipes having different angles, and the pipe in the evaporative gas passage is the heating tank It is installed with a gradient in the direction in which the liquid flows, and the pipe directly connected to the heating tank is on the opposite side to the side where the heating tank is connected to the traveling direction of the evaporating gas. It has a dead end provided at the end of the pipe, and a connection with another pipe provided on the heating tank side of the pipe with respect to the dead end.
The evaporative gas passage is composed of two or more pipes having different angles.
The number of pipes in the evaporative gas passage section is preferably 2 to 16, more preferably 2 to 8, further preferably 2 to 6, and particularly preferably 2 to 4. The larger the number of pipes, the smaller the mixing of particles in the recovery solvent, and the smaller the number of pipes, the better the cost.
The pipe in the evaporative gas passage may be a straight pipe or a bent pipe, but is preferably a straight pipe.
Further, the pipe in the evaporative gas passage section may be a cylindrical pipe or a polygonal cylindrical pipe.
The inner and outer diameters of the pipe in the evaporative gas passage section are not particularly limited, and may be appropriately selected according to the size of the heating tank and the connection portion of the evaporative gas condensing section.

The pipe in the evaporative gas passage is provided with a gradient in a direction in which the liquid flows into the heating tank.
In addition, the pipe in the evaporative gas passage directly connected to the heating tank has a dead end provided at an end of the pipe opposite to the side to which the heating tank is connected with respect to the traveling direction of the evaporative gas. And a connection part with another pipe provided on the heating tank side of the pipe with respect to the dead end part.
The pipe directly connected to the heating tank has the dead end portion and the connection portion, so that particles that blow up due to foam breakage in the heating tank collide with the dead end portion, and / or around the dead end portion. The particles are pushed back by the return of the solvent, and the mixing of the particles into the vaporized gas condensing section is suppressed.
Further, even if particles enter the next pipe beyond the connection part, since the pipe in the evaporative gas passage is provided with a gradient in a direction in which the liquid flows in the heating tank. Then, the particles are pushed back by the return of the solvent to the heating tank, and the mixing of the particles into the vaporized gas condensing section is further suppressed.
The shape of the dead end is not particularly limited, and may be any shape as long as the end of the pipe is sealed.
The length of the dead end portion, that is, the length from the sealed portion of the pipe in the dead end portion to the connection portion depends on the thickness of the pipe and the like, but is 1/4 or more of the inner diameter of the pipe. It is preferably a length, more preferably １ ／ or more of the inner diameter of the pipe, further preferably not less than the inner diameter of the pipe, particularly preferably not less than the inner diameter of the pipe and not more than 5 times the inner diameter of the pipe. preferable. When the content is in the above range, the amount of particles mixed in the recovered solvent is smaller.
Further, the number of the pipes directly connected to the heating tank is preferably 2 or more, more preferably 2 to 8, and further preferably 2 to 4. When the content is within the above range, the amount of particles mixed in the recovered solvent is smaller, and the recovery rate of the solvent is excellent.

The gradient in the direction in which the liquid flows in the heating tank of the pipe is not particularly limited, but is preferably 1 to 90 °, more preferably 10 to 90 °, with respect to the horizontal direction.
Further, the gradient of the pipe connected at the connection portion to the pipe directly connected to the heating tank is preferably 1 to 45 °, more preferably 5 to 40 ° with respect to the horizontal direction, It is particularly preferable that the angle is 8 to 30 °. In the case of the above aspect, the mixing of particles in the recovery solvent is further reduced.
The pipe in the evaporative gas passage section may have a dead end section and a connection section not only for the pipe directly connected to the heating tank, but also for other pipes.
The number of dead ends and the number of connection portions in the entire evaporative gas passage section is preferably 1 to 8, more preferably 1 to 5, still more preferably 2 or 3, and preferably 3. Is particularly preferred.
Further, among the pipes in the evaporative gas passage section, all of the pipes other than the pipes directly connected to the evaporative gas condensing section preferably have a dead end section and a connection section.
The pipe in the evaporative gas passage directly connected to the heating tank has an axial direction of the pipe (the direction in which the evaporative gas advances in the pipe and the opposite direction) from the viewpoint of mixing of particles in the recovered solvent. It is preferably substantially parallel to the direction of gravity (within ± 5 ° to the direction of gravity), and more preferably, the axial direction of the pipe is parallel to the direction of gravity.

<Evaporated gas condensing unit, condensed liquid collecting unit and decompression means>
The solvent recovery device of the present embodiment has an evaporative gas condensing unit, a condensed liquid recovery unit, and a pressure reducing unit. Further, the evaporative gas passage is connected to the evaporative gas condenser.
Known condensing means is used for the evaporative gas condensing unit, and examples thereof include a cooler such as a condenser and a heat exchanger.
The size of the evaporative gas condensing section is not particularly limited, and may be appropriately selected according to the size of the entire solvent recovery device of the present embodiment and the type and amount of the solvent to be condensed.
The refrigerant temperature and the main body temperature in the evaporative gas condensing section are not particularly limited as long as they can be condensed, and may be appropriately selected according to the type and amount of the solvent to be condensed.

The condensed liquid recovery unit is not particularly limited as long as the condensed liquid obtained by condensing the evaporative gas in the evaporative gas condensing unit is not particularly limited. It may be a transport pipe that performs the transport.
Further, the evaporative gas condenser section and the condensate recovery section may be directly connected to each other, or may be connected via a condensate recovery pipe.

The decompression means in the solvent recovery device of the present embodiment may be connected to any one of the heating tank, the evaporative gas passage section, the evaporative gas condensing section, and the condensate recovery section. From the viewpoint of the simplicity of the apparatus and the apparatus, it is preferable that the evacuation gas condensing unit and / or the condensed liquid collecting unit be connected to the decompression unit.
The pressure reducing means is not particularly limited, and a known pressure reducing means can be used.
As the pressure reducing means, for example, a vacuum pump such as a rotary pump is suitably used.
Further, only one pressure reducing means may be used, or two or more pressure reducing means may be used.
The degree of decompression in the solvent recovery apparatus of the present embodiment is not particularly limited, and may be appropriately set according to the boiling point of the compound to be recovered, the boiling point of the compound not desired to be recovered, the evaporation amount thereof, and the like.

In addition, the solvent recovery device of the present embodiment may include known means and members other than those described above.
The solvent recovery device of the present embodiment has a particle collecting means such as a filter or a demister between the heating tank, the evaporative gas passage section, the evaporative gas condensing section, and the condensed liquid collecting section. However, from the viewpoint of pressure loss and clogging with the passage of time, it is preferable not to have these particle collecting means. In the solvent recovery apparatus of the present embodiment, the amount of particles mixed in the recovery solvent is small, and it is not necessary to use such a particle collection unit.

Hereinafter, a preferred solvent recovery apparatus of the present embodiment will be described with reference to the drawings.
FIG. 1 is a schematic sectional view showing a preferred example of the solvent recovery device of the present embodiment.
The solvent recovery apparatus 10 shown in FIG. 1 has a heating tank 12 for heating a mixture (not shown) containing particles and a solvent to evaporate the solvent. The heating tank 12 includes a driving unit (motor) 14 as a stirring means. , A stirring shaft 16 connected to the driving unit 14, and a stirring blade 18 provided at an end of the stirring shaft 16. Further, the heating tank 12 has a jacket-type heating means (not shown). Is provided.
A pipe 20a is directly connected to the heating tank 12 as a part of the evaporative gas passage portion, and the pipe 20a is on the opposite side of the direction in which the evaporating gas travels from the side to which the heating tank 12 is connected. A dead end portion 22 provided at the end of the pipe 20a, and a connection portion 24 with another pipe 20b provided on the heating tank 12 side of the pipe 20a with respect to the dead end portion 22.
Further, a pipe 20b, which is a part of the evaporative gas passage section, is installed with a gradient in a direction in which the liquid flows in the heating tank 12, and the pipe 20a has an axial direction of the pipe parallel to the direction of gravity. .
The pipe 20b is connected to the evaporative gas condensing unit 26, where the evaporative gas is condensed into the condensed liquid (solvent) in the evaporative gas condensing unit 26, and serves as a condensed liquid collecting unit via the collecting pipe 28 to the collecting container 30. Condensate is collected.
Further, a pressure reducing means (not shown) is connected to the evaporative gas condensing section 26. Further, a decompression unit may be connected to the condensate recovery unit.
It is preferable that the heating tank 12, the pipes 20a and 20b, and the evaporative gas condensing section 26 are at least in a reduced pressure state by the pressure reducing means.
Further, the pressure may be reduced to the collection container 30, but in this case, it is preferable that the collection container 30 includes a cooling unit (not shown) in order to suppress evaporation of the solvent.

FIG. 2 is a schematic sectional view showing another preferred example of the solvent recovery device of the present embodiment.
The solvent recovery device 10 shown in FIG. 2 is the same as the solvent recovery device of FIG. 1 except that the connection angle between the pipe 20a and the pipe 20b is different.
The solvent recovery apparatus shown in FIG. 1 with a gentle gradient in the pipe 20b reduces the mixing of particles in the recovery solvent.
Further, the solvent recovery apparatus shown in FIG. 2 having a steep gradient of the pipe 20b is more excellent in the recovery rate of the recovered solvent and the residue as a whole.

FIG. 3 is a schematic sectional view showing another preferred example of the solvent recovery device of the present embodiment.
The solvent recovery apparatus 10 shown in FIG. 3 has a heating unit 12 having a driving unit 14, a stirring shaft 16 and a stirring blade 18 as stirring means, as in FIG. (Not shown) is provided.
A pipe 20a is directly connected to the heating tank 12 as a part of the evaporative gas passage portion, and the pipe 20a is on the opposite side of the direction in which the evaporating gas travels from the side to which the heating tank 12 is connected. A dead end portion 22a provided at the end of the pipe 20a, and a connection portion 24a with another pipe 20b provided on the heating tank 12 side of the pipe 20a with respect to the dead end portion 22a.
The pipe 20b has a dead end 22b provided at an end of the pipe 20b opposite to the connection part 24a with respect to the traveling direction of the evaporative gas, and a heating tank 12 for the pipe 20b more than the dead end 22b. It has a connection portion 24b with another pipe 20c provided on the side.
The pipe 20c has a dead end portion 22c provided at an end of the pipe 20c opposite to the connection portion 24b with respect to the traveling direction of the evaporative gas, and a heating tank 12 for the pipe 20c more than the dead end portion 22c. It has a connection portion 24c with another pipe 20d provided on the side.
The pipes 20b and 20d, which are part of the evaporative gas passage section, are installed with a gradient in the direction in which the liquid flows in the heating tank 12, and the pipes 20a and 20c are arranged such that the axial direction of the pipes is the direction of gravity. Is parallel to
The pipe 20d is connected to the evaporative gas condensing unit 26, and the evaporative gas is condensed in the evaporative gas condensing unit 26 to become a condensed liquid (solvent). Condensate is collected.
Further, a pressure reducing means (not shown) is connected to the evaporative gas condensing section 26. Further, a decompression unit may be connected to the condensate recovery unit.
It is preferable that the heating tank 12, the pipes 20a to 20d, and the evaporative gas condensing unit 26 are at least in a reduced pressure state by the pressure reducing means.
Further, the pressure may be reduced to the collection container 30, but in this case, it is preferable that the collection container 30 includes a cooling unit (not shown) in order to suppress evaporation of the solvent.

FIG. 4 is a schematic cross-sectional view showing still another preferred example of the solvent recovery device of the present embodiment.
The solvent recovery apparatus 10 shown in FIG. 4 has a heating unit 12 having a drive unit 14, a stirring shaft 16 and a stirring blade 18 as stirring means, as in FIG. (Not shown) is provided.
Pipes 20 a and 20 b are directly connected to the heating tank 12 as a part of the evaporative gas passage section.
The pipe 20a has a dead end portion 22a provided at an end of the pipe 20a on the opposite side to the side to which the heating tank 12 is connected with respect to the traveling direction of the evaporating gas, and the pipe is more than the dead end portion 22a. It has a connecting portion 24a with another pipe 20d provided on the heating tank 12 side of 20a.
The pipe 20b has a dead end portion 22b provided at an end of the pipe 20b on the opposite side to the side to which the heating tank 12 is connected with respect to the traveling direction of the evaporating gas, and the pipe is more than the dead end portion 22b. It has a connection 24b with another pipe 20c provided on the heating tank 12 side of 20b.
One of the pipes 20c is connected to the pipe 20b at the connection portion 24b, and the other is connected to the pipe 20a at the connection portion 24c.
The pipes 20c and 20d, which are part of the evaporative gas passage section, are installed so as to have a gradient in the direction in which the liquid flows in the heating tank 12, and the pipes 20a and 20b are arranged such that the axial directions of the pipes are in the direction of gravity. Is parallel to
The position of the connection part 24a and the position of the connection part 24c may be the same height or different heights, but from the viewpoint of the flow of steam, the position of the connection part 24a and the position of the connection part 24c Are preferably the same height, or the position of the connection portion 24c is closer to the heating tank 12 than the position of the connection portion 24a.
The pipe 20d is connected to the evaporative gas condensing unit 26, and the evaporative gas is condensed in the evaporative gas condensing unit 26 to become a condensed liquid (solvent). Condensate is collected.
Further, a pressure reducing means (not shown) is connected to the evaporative gas condensing section 26. Further, a decompression unit may be connected to the condensate recovery unit.
It is preferable that the heating tank 12, the pipes 20a to 20d, and the evaporative gas condensing unit 26 are at least in a reduced pressure state by the pressure reducing means.
Further, the pressure may be reduced to the collection container 30, but in this case, it is preferable that the collection container 30 includes a cooling unit (not shown) in order to suppress evaporation of the solvent.

(Solvent recovery method)
The solvent recovery method of the present embodiment is a method of recovering a solvent from a mixture containing particles and a solvent using the solvent recovery device of the present embodiment.
The solvent recovery device in the solvent recovery method of the present embodiment is the above-described solvent recovery device of the present embodiment, and the preferred embodiments are also the same.
Further, the solvent recovery method of the present embodiment is preferably a method of recovering a solvent from a mixture containing particles, water and a solvent.
The solvent used in combination with water preferably has a boiling point of 90 ° C. or lower, more preferably a boiling point of 30 ° C. to 90 ° C.
The particles are preferably particles having a volume average particle size of 10 nm to 200 μm, and more preferably particles having a volume average particle size of 10 nm to 50 μm.
Further, the particles may be solid particles or liquid particles, but are preferably solid particles after the solvent is recovered.
Further, the particles are preferably resin particles, and the mixture is preferably a resin dispersion containing a resin, water and a solvent.
Further, the solvent recovery method of the present embodiment uses the solvent recovery apparatus of the present embodiment, a step of evaporating the solvent from a mixture containing the particles and the solvent by heating and depressurizing in a heating tank, wherein the vapor of the solvent is evaporated. Passing through the evaporative gas passage section, condensing the evaporative gas passing through the evaporative gas passage section in the evaporative gas condenser section, and recovering the solvent condensed in the evaporative gas condenser section in the condensate recovery section Preferably, the method includes:
Further, as another preferable mode in the solvent recovery method of the present embodiment, the preferable mode in the above-described solvent recovery apparatus of the present embodiment is exemplified.

  Hereinafter, the present embodiment will be described in more detail with reference to examples and comparative examples, but the present embodiment is not limited to the following examples. Unless otherwise specified, “%” represents “% by mass” and “parts” represents “parts by mass”.

<Synthesis of polyester resin>
In a jacketed stainless steel container, 80 molar equivalents of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 10 molar equivalents of ethylene glycol, 10 molar equivalents of cyclohexanediol, and 80 molar equivalents of terephthalic acid Starting from the equivalents, 10 molar equivalents of isophthalic acid and 10 molar equivalents of n-dodecenylsuccinic acid, dibutyltin oxide was added as a catalyst, nitrogen gas was introduced into the apparatus, and the temperature was raised while maintaining an inert atmosphere at 150 ° C. To 230 ° C. for about 12 hours, and then the pressure was gradually reduced from 210 ° C. to 250 ° C. to synthesize a polyester resin (1).
The weight average molecular weight (Mw) of the obtained polyester resin (1) was 17,100. The acid value of the polyester resin (1) was 12.5 mgKOH / g.
Further, the glass transition temperature of the polyester resin (1) was measured by using a differential scanning calorimeter (DSC), and the glass transition temperature was obtained by analyzing according to JIS standards (see JIS K-7121). As a result, a stepwise endothermic change was observed without showing a clear peak. The glass transition temperature (Tg) at the midpoint of the stepwise endothermic change was 58 ° C.

<Preparation of polyester resin dispersion liquid 1 containing an organic solvent>
-Polyester resin (1): 100 parts by mass-Ethyl acetate: 70 parts by mass-Isopropyl alcohol: 15 parts by mass The mixed solvent of the above ethyl acetate and the above isopropyl alcohol is charged into a jacketed stainless steel container, and the above resin is gradually added thereto. And the mixture was completely dissolved while stirring to obtain an oil phase.
A 10% by mass aqueous ammonia solution was gradually dropped into the stirred oil phase by a tube pump so that the total amount became 3 parts by mass, and 230 parts by mass of ion exchanged water was gradually dropped at a rate of 10 L / min. Phase inversion was emulsified.

<Method for measuring solid content concentration in recovered organic solvent>
The turbidity of the polyester resin dispersion liquid previously diluted to a predetermined solid content was measured, and a calibration curve between the turbidity and the solid content was prepared. The turbidity of the collected organic solvent was measured, and the solid content concentration was calculated.

<Calculation method of recovery rate of polyester resin dispersion>
With respect to the total mass of the resin particle dispersion containing the organic solvent put into the jacketed stirring tank, the sum of the mass of the recovered organic solvent and the mass of the resin particle dispersion finally obtained from the jacketed stirring tank is used. The recovery was calculated by dividing.

(Example 1)
<Preparation of polyester resin particle dispersion liquid 1>
The polyester resin dispersion liquid 1 containing the organic solvent was transferred to a 500 L jacketed stainless steel container having a stirring blade and capable of being decompressed while heating at 60 ° C. while stirring and decompressing the entire container to 3 kPa. The organic solvent evaporated by the reduced pressure passed through a vapor gas passage pipe from the upper portion of the stainless steel container, was then condensed by the condenser, and was recovered in the recovery container below the condenser. The vapor gas passage pipe is a stainless steel pipe with an inner diameter of 55 mm, which is vertically extended from the upper part of the stainless steel container, then turned 60 degrees 55 mm before the pipe is attached and connected to the condenser. (Fig. 1). After removing the solvent, the dispersion in the stainless steel container was recovered to obtain a polyester resin dispersion 1. The volume average particle size of the resin particles dispersed in this dispersion was 180 nm. When the solid content concentration of the collected organic solvent was measured, it was 0.40%. Further, the recovery rate was 99.60%.

(Example 2)
The procedure was performed in the same manner as in Example 1 except that the structure was such that it was connected to the condenser at 50 degrees (FIG. 2). When the solid content concentration of the recovered organic solvent was measured, it was 0.50%, and the recovery was 99.70%.

(Example 3)
Except having carried out with the apparatus shown in FIG. 3, it carried out similarly to Example 1. When the solid content concentration of the collected organic solvent was measured, it was 0.08%, and the recovery rate was 99.40%.

(Example 4)
As in Example 1, except that two evaporative gas passage pipes connected to the heating tank were used, and devices (devices shown in FIG. 4) respectively connected to two places on the upper portion of the stainless steel container were used. went. When the solid content concentration of the collected organic solvent was measured, it was 0.03%, and the recovery rate was 99.60%.

(Comparative Examples 1 to 6)
Except having performed each using the apparatus shown in FIGS. 5-10, it carried out similarly to Example 1.
Table 1 summarizes the evaluation results.

-Evaluation criteria-
The solid content concentration of the recovered organic solvent was determined based on the following criteria, and Δ or more was regarded as an allowable range.
◎: less than 0.1% ：: 0.1% or more and less than 0.5% Δ: 0.5% or more and less than 1.0% ×: 1.0% or more

The recovery rate was determined based on the following criteria, and Δ or more was regarded as an allowable range.
◎: 99% or more ○: 97% or more and less than 99% Δ: 95% or more and less than 97% ×: less than 95%

  10: solvent recovery device, 12: heating tank, 14: drive unit (motor), 16: stirring shaft, 18: stirring blade, 20, 20a to 20d: piping, 22, 22a to 22c: dead end portion, 24, 24a to 24c: connection part, 26: evaporative gas condensing part, 28: collection pipe, 30: collection container

Claims (4)

Has a heating bath have a stirring means and a heating means, and houses a mixture comprising particles and solvent, and evaporating gas passage, an evaporation gas condensing section, and the condensate recovery unit, and a pressure reducing means,
The evaporative gas passage section is configured by two or more pipes having different angles,
The pipe in the evaporative gas passage section is installed with a gradient in a direction in which the liquid flows in the heating tank,
The pipe directly connected to the heating tank, the particles contained in the heating tank provided at the end of the pipe opposite to the side to which the heating tank is connected, with respect to the traveling direction of the vaporized gas. A solvent recovery device, comprising: a dead end that collides; and a connection to another pipe provided on the heating tank side of the pipe with respect to the dead end.   The solvent recovery device according to claim 1, wherein the number of the pipes directly connected to the heating tank is two or more.   The other pipe is a pipe B,
  The pipe B has a dead end B provided at an end of the pipe B opposite to the connection part with respect to a traveling direction of the evaporative gas, and a heating tank side of the pipe B with respect to the dead end B. 3. The solvent recovery device according to claim 1, further comprising a connection portion B for connecting to a pipe C provided in the device.   The pipe C has a dead end portion C provided at an end of the pipe C opposite to the connection portion B with respect to the traveling direction of the evaporative gas, and a heating tank of the pipe C more than the dead end portion C. The solvent recovery device according to claim 3, further comprising a connection portion C with a pipe D provided on the side.

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