Distillation apparatus equipped with a distillation column

Abstract

To provide a distillation device which prevents a reboiler from coming to be considered as a pressure container and prevents size increase of a distillation tower.SOLUTION: A distillation device 1 includes a distillation tower and comprises: a distillation tower 2; a reboiler 3 which heats and evaporates a storage liquid stored at a tower bottom part of the distillation tower 2; and a first steam compression device 4 which compresses steam generated by the reboiler 3 and sends the steam to the distillation tower 2. Preferably, the distillation device 1 includes a second steam compression device 42 which compresses and heats steam supplied from a tower top part of the distillation tower 2 to use the steam as a heating source of the reboiler 3.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a distillation apparatus equipped with a distillation column, and more particularly to a distillation apparatus equipped with a distillation column and a reboiler that heats a liquid stored in the bottom of the distillation column. [Background technology]

[0002] A commonly known distillation apparatus equipped with a distillation column is one in which the liquid stored at the bottom of the distillation column is removed and most of it is evaporated in a reboiler to produce fractionated vapor in the distillation column (see Patent Document 1 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-192868 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a distillation apparatus such as the above-mentioned conventional example, as the solvent concentration of the concentrated liquid is increased in the reboiler (or the evaporator used as a reboiler), the boiling point rises, and when it exceeds a certain level, the reboiler becomes a pressure vessel. This would require statutory inspection, and a licensed factory would be required to manufacture the pressure vessel. Therefore, a method of lowering the pressure in the system so that the reboiler does not become a pressure vessel could be considered. However, such a method would result in a high specific volume (m 3 This increases the vapor flow rate in the distillation tower as the total mass fraction (mass / kg) increases, which in turn increases the diameter (body diameter) of the distillation tower, resulting in a corresponding increase in initial costs.

[0005] The present invention has been devised in view of the above problems, and an object of the present invention is to provide a distillation apparatus in which a reboiler does not correspond to a pressure vessel and the size of the distillation column is not increased. [Means for solving the problem]

[0006] In order to achieve the above object, a distillation apparatus including a distillation column according to the invention described in claim 1 includes a distillation column, a reboiler that heats and evaporates a liquid stored in a bottom portion of the distillation column, and a first vapor compression device that compresses vapor generated in the reboiler and sends the vapor to the distillation column. The reboiler includes at least a primary condensation section that evaporates and condenses the stored liquid supplied thereto, and a secondary condensation section that further evaporates and condenses the stored liquid condensed in the primary condensation section, and the first vapor compression device is configured to compress the vapor generated in the secondary condensation section of the reboiler and send it to the distillation column. It is characterized by the fact that

[0007] According to the above configuration, by compressing the steam generated in the reboiler by the first vapor compression device, the pressure of the reboiler (and the temperature of the circulating liquid) can be lowered, and therefore the reboiler does not fall under the category of a pressure vessel. In addition, since the pressure of the reboiler can be lowered, the conditions for the pressure-resistant design of the reboiler can be lowered (for example, the plate thickness of the reboiler can be reduced), which provides the advantage of enabling the cost of the reboiler itself to be reduced. 。

[0008] In addition, by compressing the vapor in the first vapor compression device, an increase in the specific volume of the vapor can be suppressed, and an increase in the flow rate of the vapor in the distillation column can be suppressed. As a result, the diameter (body diameter) of the distillation column does not increase, and therefore an increase in costs can be suppressed.

[0009] In addition, in the above configuration, the stored liquid concentrated in the primary concentration section is low concentration (low boiling point), and the stored liquid concentrated in the secondary concentration section is high concentration (high boiling point). Therefore, compared to a configuration with only one reboiler (a configuration with an undivided reboiler), the primary concentration section can process the liquid at a low concentration, and the boiling point of the liquid to be processed is lowered, so the effective heat transfer temperature difference of the reboiler can be made large, and the heat transfer coefficient is also improved, so that the heat transfer area of ​​the reboiler can be suppressed from being enlarged. In addition, since low-concentration evaporated steam is supplied to the distillation tower, the solvent concentration in the steam to the distillation tower is reduced, and the reflux ratio can be reduced. In addition, it is possible to review the distillation tower size to be smaller. In addition, since the reflux water will be evaporated again in the distillation apparatus, it becomes an evaporation load. Therefore, compared to a configuration with only one reboiler, this configuration can reduce the evaporation load and the power consumption. (See JP 2017-192868 A)

[0010] Furthermore, in the case where the reboiler is configured to include a primary concentration section and a secondary concentration section, the stored liquid concentrated in the secondary concentration section becomes highly concentrated (has a high boiling point) as described above. Therefore, if the steam generated in the secondary concentration section is compressed by the first vapor compression device of the present invention, the effects of the present invention can be more effectively achieved than in the case where the reboiler is configured to include only one reboiler.

[0011] Claim 2 A distillation apparatus equipped with the distillation column according to the invention described above is The present invention comprises a distillation tower, a reboiler which heats and evaporates a liquid stored in a bottom portion of the distillation tower, and a first vapor compression device which compresses the vapor generated in the reboiler and sends the vapor to the distillation tower, the reboiler including a primary concentration section which evaporates and condenses the stored liquid supplied thereto, a secondary concentration section which further evaporates and condenses the stored liquid concentrated in the primary concentration section, and a tertiary concentration section which further evaporates and condenses the stored liquid concentrated in the secondary concentration section, from the primary concentration section to the nth concentration section at the rear end (n is an integer of 3 or more), and the first vapor compression device is configured to compress the vapor generated in the nth concentration section at the rear end of the reboiler and send the vapor to the distillation tower. It is characterized by the fact that

[0012] A distillation apparatus equipped with the distillation column according to the invention recited in claim 3 is a distillation apparatus equipped with the distillation column according to the invention recited in claim 1 or 2, characterized in that it is equipped with a retained liquid supply pipe for supplying the retained liquid to the reboiler.

[0013] Claim 4 A distillation apparatus equipped with the distillation column according to the invention described above is Any one of claims 1 to 3 A distillation apparatus comprising the distillation column according to the invention described in A second vapor compression device is provided to compress and heat the vapor supplied from the top of the distillation column and use it as a heating source for the reboiler.It is characterized by the fact that

[0014] According to the above configuration, the steam supplied from the top of the distillation column can be reused as a heat source for the reboiler, thereby achieving energy saving in the distillation apparatus.

[0015] Claim 5 The distillation apparatus equipped with the distillation column according to the invention described above is 1 or 2 a reboiler for reboiler that is a horizontal tube type evaporator that is divided into two parts by a partition plate, and each divided part of the divided evaporator is configured as the primary concentration section and the secondary concentration section, and the primary concentration section and the secondary concentration section are provided with a heat transfer tube group through which steam supplied from a top of the distillation column passes, and a sprayer that sprays the stored liquid toward an outer surface of the heat transfer tube group, and an inlet side common header through which steam supplied from the top of the distillation column passes is provided on one side of the primary concentration section and the secondary concentration section so as to surround one end of each of the heat transfer tube groups, and an outlet side common header for storing condensed liquid generated by heat exchange between the steam introduced from the inlet side common header and the stored liquid sprayed on the outer surface of the heat transfer tube group as the steam introduced from the inlet side common header passes through the heat transfer tube group is provided on the other side of the primary concentration section and the secondary concentration section so as to surround the other end of each of the heat transfer tube groups.

[0016] According to the above configuration, a configuration in which one evaporator can be divided into two can be used, and the size and cost of the device can be reduced compared to a configuration in which two evaporators are used.

[0017] Claim 6 The distillation apparatus equipped with the distillation column according to the invention described above comprises the following: 5 The present invention relates to a distillation apparatus having a distillation column according to any one of claims 1 to 5, characterized in that the apparatus is configured to return condensed water produced by heat exchange of steam supplied to the reboiler to the top of the distillation column as reflux water. Effect of the Invention

[0018] According to the present invention, the reboiler does not fall under the category of a pressure vessel, and the size of the distillation column does not increase, so that an increase in cost can be suppressed. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is an overall configuration diagram of a distillation apparatus according to a first embodiment. [Diagram 2] FIG. 1 is an overall configuration diagram of a distillation apparatus according to a second embodiment. [Diagram 3] FIG. 11 is an overall configuration diagram of a distillation apparatus according to a third embodiment. [Figure 4] FIG. 11 is a perspective view of a distillation apparatus according to a third embodiment. [Diagram 5] FIG. 11 is a front view of a distillation apparatus according to a third embodiment. [Figure 6] FIG. 13 is an overall configuration diagram of a distillation apparatus according to yet another example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The present invention will be described in detail below based on the embodiments, however, the present invention is not limited to the following embodiments.

[0021] (Embodiment 1) Fig. 1 is an overall configuration diagram of a distillation apparatus 1 according to embodiment 1. In this embodiment 1, the distillation apparatus 1 is described by taking as an example a distillation apparatus used for distilling wastewater containing a high-boiling point organic solvent having a boiling point higher than that of water and separating the wastewater into a recovered liquid and treated water. Examples of high-boiling point organic solvents having a boiling point higher than that of water include NMP (N-methyl-2-pyrrolidone), DMSO (dimethyl sulfoxide), ethylene glycol or diethylene glycol, and high-boiling point alcohol-based cleaning agents (including surfactants).

[0022] The distillation apparatus 1 includes a distillation column 2, a reboiler 3 that heats and evaporates the liquid stored in the bottom of the distillation column 2, and a first vapor compression device 4 that compresses the vapor generated in the reboiler 3 and sends it to the distillation column 2. In the present embodiment 1, the first vapor compression device 4 is configured with one vapor compressor. The distillation column 2 may be a multi-stage one, or may not be a multi-stage one. That is, the distillation column 2 may be a plate tower or a packed tower.

[0023] The reboiler (evaporator) 3 is composed of a horizontal tube type evaporator 10, and is equipped with a diffuser 11 and an indirect heater 12. The evaporator 10 is not limited to the horizontal tube type, and may be, for example, a thin film flow (vertical tube) type evaporator.

[0024] The indirect heater 12 includes a heat transfer tube group 13 consisting of one or more horizontal heat transfer tubes, and a pair of left and right headers 14, 15. The bottom of the evaporator 10 serves as a storage section in which the liquid to be treated is stored. The raw liquid is supplied to the bottom of the evaporator 10 through a raw liquid supply pipe 22.

[0025] The evaporator 10 has a circulation flow path h1 (composed of a tube 70 and a tube 71) for the raw liquid or the concentrated liquid. A circulation pump P1 and a sparger 11 are arranged in the circulation flow path h1. The circulation pump P1 is connected to the bottom of the distillation column 2. The circulation pump P1 is configured to transfer the raw liquid (including the concentrated liquid obtained by concentrating the raw liquid) stored in the bottom of the distillation column 2 to the sparger 11 through the tube 70. In other words, the tube 70 serves as a stored liquid supply pipe that supplies the stored liquid stored in the bottom of the distillation column 2 to the reboiler 3. The tube 70 has a branch pipe 83 that branches off midway, and a part of the concentrated liquid obtained by concentrating the raw liquid is recovered and discharged to the outside of the system as a recovered liquid through the branch pipe 83. The sparger 11 is configured to spray the raw liquid (including the concentrated liquid obtained by concentrating the raw liquid) from above the heat transfer tube group 13 toward the heat transfer tube group 13. In addition, the bottom of the evaporator 10 is connected to the bottom of the distillation column 2 via a pipe 71, and the stored liquid is returned to the bottom of the distillation column 2 via the bottom of the evaporator 10 and stored in the storage chamber 44.

[0026] The bottom of the header 14 in the heater 12 is connected to a spreader 20 provided at the top of the distillation column 2 via a pipe 74. A pump P2 is disposed in the pipe 74, and the condensed water stored in the header 14 is spread from the spreader 20 as reflux water by driving the pump P2. The pipe 74 has a branch pipe 75 that branches off midway, and a portion of the condensed water stored in the header 14 is discharged to the outside via the branch pipe 75.

[0027] The top of the distillation column 2 is connected to the header 15 of the heater 12 via a pipe 79 so that steam supplied from the top of the distillation column 2 is introduced into the header 15.

[0028] The upper part (downstream side) of the evaporator 10 is connected to the inlet side of the first vapor compression device 4 via a pipe 72, and the outlet side of the first vapor compression device 4 is connected to the bottom of the distillation column 2 via a pipe 84, so that the vapor evaporated in a thin film outside the heat transfer tube group 13 is compressed in the first vapor compression device 4 and supplied to the bottom of the distillation column 2. Here, the first vapor compression device 4 may be any of a turbo type vapor compressor, a Roots type vapor compressor, and other vapor compressors.

[0029] Next, the processing operation of the distillation apparatus 1 having the above-mentioned configuration will be described. By driving the circulation pump P1, the circulating liquid (including the raw liquid and concentrated water) stored in the storage chamber 44 at the bottom of the column is supplied to the sprayer 11 through the pipe 70, and is sprayed from the sprayer 11 toward the heat transfer tube group 13. The circulating liquid sprayed by the sprayer 11 evaporates in a thin film on the surface of the heat transfer tube group 13, generating steam. This steam is compressed by the first vapor compression device 4, supplied to the bottom of the distillation column 2, and rises inside the distillation column 2.

[0030] Meanwhile, the condensed water stored in the header 14 is sprayed from the sprayer 20 as reflux water by driving the pump P2, and flows down inside the distillation tower 2. Then, at each stage inside the distillation tower 2, the steam rising inside the distillation tower 2 and the treated water (condensed water) flowing down inside the distillation tower 2 come into gas-liquid contact, whereby components with different boiling points are separated, and a concentrated liquid of the high boiling point components flows down to the bottom of the tower and is stored in the storage chamber 44, while steam consisting mostly of low boiling point components is extracted from the top of the tower. The steam extracted from the top of the tower is sent to the header 15.

[0031] The steam that enters the header 15 is guided to the inside of the heat transfer tube group 13, and evaporates the circulating liquid sprayed on the outside of the heat transfer tube group 13 in a thin film. The steam generated by the thin film evaporation is compressed by the first vapor compression device 4 and then supplied again to the bottom of the distillation column 2, where it rises inside the distillation column 2 and comes into gas-liquid contact with the treated water (condensed water) descending inside the distillation column 2 from the top of the column. As a result, the concentration of high boiling point components in the descending liquid increases, and the concentration of high boiling point components in the ascending vapor decreases. Meanwhile, the remaining circulating liquid that has not evaporated in a thin film is supplied from the bottom of the evaporator 10 to the bottom of the distillation column 2 through the pipe 71, and is stored in the storage chamber 44 at the bottom of the column. This series of processes is then repeated, whereby the circulating liquid is concentrated.

[0032] According to the first embodiment, since the steam generated in the reboiler 3 is compressed by the first steam compression device 4, the pressure of the reboiler 3 can be reduced. Therefore, the reboiler 3 is configured not to be a pressure vessel. In addition, since the pressure of the reboiler 3 can be reduced, the conditions for the pressure-resistant design of the reboiler 3 can be lowered (for example, the plate thickness of the reboiler 3 can be reduced), which is advantageous in that the cost of the reboiler 3 itself can be reduced.

[0033] In addition, by compressing the vapor using the first vapor compression device 4, the specific volume of the vapor can be reduced, and an increase in the vapor flow rate in the distillation column 2 can be prevented. This prevents the diameter (body diameter) of the distillation column 2 from increasing, thereby preventing an increase in costs.

[0034] Specific configurations of other embodiments of the present invention will be described below. In the following description and drawings, the same parts and members as those described in the first embodiment will be given the same reference numerals, and their description will basically be omitted unless necessary.

[0035] (Embodiment 2) FIG. 2 is an overall configuration diagram of a distillation apparatus 1L according to the second embodiment. In the first embodiment, the reboiler 3 is composed of one evaporator 10. In the second embodiment, the reboiler 3L is divided into two, and includes a first evaporator (corresponding to a primary concentration section) 10A and a second evaporator (corresponding to a secondary concentration section) 10B. The second evaporator 10B is configured to evaporate and concentrate the stored liquid to a concentration higher than that of the stored liquid to be evaporated and concentrated in the first evaporator 10A. That is, the evaporative concentration section is divided according to the concentration difference of the stored liquid to be evaporated and concentrated, and the first evaporator 10A processes the liquid with a low concentration, and the second evaporator 10B processes the liquid with a high concentration. Specifically, the raw liquid is fed into the first evaporator (corresponding to a primary concentration section) 10A. Meanwhile, the liquid concentrated in the first evaporator 10A is fed into the second evaporator (corresponding to a secondary concentration section) 10B.

[0036] By dividing the reboiler 3L in this manner, the effective heat transfer temperature difference can be made larger by the amount that the boiling point is lowered compared to the case of a single reboiler (when not divided), and the heat transfer efficiency is also improved, so that the heat transfer area of ​​the reboiler (evaporator) can be made smaller and the heat transfer area can be made more compact.

[0037] The first evaporator 10A and the second evaporator 10B are both horizontal tube-type evaporators having the same configuration, and the first evaporator 10A has the same configuration as the evaporator 10 according to the above-mentioned embodiment 1. Therefore, in the following explanation, the second evaporator 10B will be mainly described. In addition, in the first evaporator 10A and the second evaporator 10B, corresponding parts or members are designated by the same numerals with A and B added thereto.

[0038] The first evaporator 10A and the second evaporator 10B are provided with diffusers 11A and 11B and indirect heaters 12A and 12B. The first evaporator 10A and the second evaporator 10B are not limited to the horizontal tube type, and may be, for example, a thin film flow (vertical tube) type evaporator.

[0039] The indirect heaters 12A and 12B are provided with a heat transfer tube group 13A and 13B consisting of one or more horizontal heat transfer tubes, and a pair of left and right headers 14A, 15A; 14B, 15B. The bottoms of the evaporators 10A and 10B serve as storage sections for storing the liquid to be treated. The raw liquid is supplied to the bottom of the first evaporator 10A through a raw liquid supply pipe 22.

[0040] The second evaporator 10B has a circulation flow path h2 for the raw liquid or the concentrated liquid. A circulation pump P3 and a sprayer 11B are arranged in the circulation flow path h2. The circulation pump P3 is connected to the bottom of the second evaporator 10B. The circulation pump P3 is configured to transfer the stored liquid (concentrated liquid obtained by concentrating the raw liquid) stored at the bottom of the second evaporator 10B to the sprayer 11B through the circulation flow path h2. The sprayer 11B is configured to spray the stored liquid (concentrated liquid obtained by concentrating the raw liquid) from above the heat transfer tube group 13B toward the heat transfer tube group 13B.

[0041] The pipe 70 in the circulation flow path h1 of the first evaporator 10A has a branch pipe 73 branched off midway, so that the concentrated liquid obtained by concentrating the raw liquid from the bottom of the distillation column 2 can be supplied to the bottom of the second evaporator 10B through the branch pipe 73. In other words, like the pipe 70, the branch pipe 73 also serves as a liquid supply pipe for supplying the liquid stored in the bottom of the distillation column 2 to the reboiler 3L.

[0042] The upper part of the second evaporator 10B is connected to the inlet side of the first vapor compression device 41 via a pipe 76, and the outlet side of the first vapor compression device 41 is connected to the bottom of the distillation column 2 via a pipe 85, so that the vapor evaporated in a thin film outside the heat transfer tube group 13B is compressed by the first vapor compression device 41 and supplied to the bottom of the distillation column 2. Here, the first vapor compression device 41 may be any of a turbo type vapor compressor, a Roots type vapor compressor, and other vapor compressors.

[0043] The bottom of the header 14B is connected to the bottom of the header 15A via a pipe 77, and the condensed water stored in the header 14B is supplied to and stored in the header 14A through the header 15A and the heat transfer tube group 13A. In addition, the circulation flow path h2 has a branch pipe 78 that branches off midway, and the circulation pump P3 is capable of recovering a portion of the concentrated liquid obtained by concentrating the raw liquid and discharging it outside the system through the branch pipe 78 as a recovered liquid.

[0044] The top of the distillation column 2 is connected to the inlet side of the second vapor compression device 42 via a pipe 79, and the outlet side of the second vapor compression device 42 is connected to the header 15A of the heater 12A via a pipe 80. The pipe 80 is provided with a branch pipe 81 that branches off midway, and the outlet side of the second vapor compression device 42 is also connected to the header 15B of the heater 12B via the branch pipe 81. Here, the second vapor compression device 42 may be any of a turbo type vapor compressor, a Roots type vapor compressor, and other vapor compressors.

[0045] Next, a description will be given of the processing operation of the distillation apparatus 1L according to the embodiment 2. The processing operation of the first evaporator 10A is similar to the processing operation of the evaporator 10 according to the above-mentioned embodiment 1, and therefore the description will be omitted.

[0046] The steam taken out from the top of the distillation column 2 is guided to the second vapor compression device 42. In the second vapor compression device 42, the supplied steam is compressed and heated, and used as a heat source for the reboiler 3L. That is, the steam guided to the second vapor compression device 42 is adiabatically compressed in the second vapor compression device 42 to increase its temperature and pressure, and then sent to the headers 15A and 15B.

[0047] The steam that has entered the header 15A is guided to the inside of the heat transfer tube group 13A, and evaporates the circulating liquid sprayed on the outside of the heat transfer tube group 13A in a thin film. The steam generated by the thin film evaporation is again supplied to the bottom of the distillation column 2, rises in the distillation column 2, and comes into gas-liquid contact with the treated water (condensed water) descending from the top of the distillation column 2. As a result, the concentration of high boiling point components in the descending liquid increases, and the concentration of high boiling point components in the ascending steam decreases. Meanwhile, the remaining circulating liquid that has not evaporated in a thin film is supplied from the bottom of the evaporator 10A to the bottom of the distillation column 2 through the pipe 71, and is stored in the storage chamber 44 at the bottom of the column. This series of processes is repeated, and the circulating liquid is concentrated, and the concentrated liquid is supplied to the bottom of the second evaporator 10B through the branch pipe 73.

[0048] In the second evaporator 10B, the circulation liquid (concentrated liquid obtained by concentrating the raw liquid) stored at the bottom of the second evaporator 10B is supplied to the diffuser 11B through the circulation flow path h2 by driving the circulation pump P3, and is diffused from the diffuser 11B toward the heat transfer tube group 13B. Meanwhile, the steam compressed by the second vapor compression device 42 enters the header 15B and is guided to the inside of the heat transfer tube group 13B. As a result, the circulation liquid diffused by the diffuser 11B is evaporated in a thin film on the surface of the heat transfer tube group 13B, and steam is generated. This steam is compressed by the first vapor compression device 41 and then supplied to the bottom of the distillation column 2, and rises inside the distillation column 2. Meanwhile, the remaining circulation liquid that has not evaporated in a thin film is diffused from the diffuser 11B through the circulation flow path h2 again, and generates steam by thin film evaporation. By repeating such a series of processes, the circulation liquid is concentrated and discharged from the pipe 78 to the outside of the system as a recovered liquid (concentrated liquid).

[0049] Meanwhile, the condensed water stored in the header 14B is guided to the header 14A through the pipe 77 and the header 15A, and is sprayed from the sprayer 20 as reflux water by driving the pump P2, and flows down within the distillation column 2.

[0050] In this manner, in the present embodiment 2, the stored liquid concentrated in the first evaporator 10A has a low concentration (low boiling point), and the stored liquid concentrated in the second evaporator 10B has a high concentration (high boiling point). Therefore, in the present embodiment 2, compared to a configuration with only one reboiler (a configuration in which the reboiler is not divided), the first evaporator (corresponding to the primary concentration section) 10A can process the liquid at a low concentration, and since the boiling point of the liquid to be processed is lowered, the effective heat transfer temperature difference of the reboiler can be made large, and the heat transfer coefficient is also improved, so that it is possible to suppress an increase in the heat transfer area of ​​the reboiler.

[0051] In addition, since low-concentration evaporated steam is supplied to the distillation column 2, the reflux ratio can be reduced. Note that the reflux water is evaporated again in the distillation apparatus, which creates an evaporation load. Therefore, the evaporation load can be reduced, and power consumption can be reduced.

[0052] In addition, the distillation apparatus 1L according to the second embodiment is equipped with a second vapor compression device 42 that compresses and heats the steam supplied from the top of the distillation column 2 and uses it as a heat source for the reboiler 3L. Therefore, the steam can be reused as a heat source for the reboiler 3L, thereby making the distillation apparatus 1L more energy efficient.

[0053] In particular, as described above, the stored liquid concentrated in the second evaporator 10B, which corresponds to the secondary concentration section, becomes highly concentrated (has a high boiling point), and since the first vapor compression device 41 is connected to the upper part of this second evaporator 10B, the effect of compressing the vapor generated in the reboiler by the first vapor compression device 41 is further enhanced.

[0054] That is, in the configuration of the distillation apparatus 1L according to the second embodiment, assuming that the first vapor compression device 41 is not provided as an example for comparison (comparative example), and assuming that the pressure (vacuum degree) in the distillation column 2 is V2, the pressure in the first evaporator 10A is V10A, the pressure in the second evaporator 10B is V10B, the circulating liquid temperature in the first evaporator 10A is T10A, and the circulating liquid temperature in the second evaporator 10B is T10B as shown in Fig. 2, the following results are obtained. When the circulating liquid (concentrated liquid) is concentrated and the solvent concentration is increased by repeating a series of processes in the distillation apparatus according to this comparative example, the circulating liquid temperature in the first evaporator 10A remains low (for example, T10A = 87.0 ° C.), but in contrast, the boiling point in the second evaporator 10B increases, and when it increases to a certain level (for example, T10B = 100 ° C.), the second evaporator 10B corresponds to a pressure vessel. Therefore, a method of lowering the pressure (degree of vacuum) in the system so that the second evaporator 10B does not correspond to a pressure vessel can be considered. In the case of this comparative example, the pressure (degree of vacuum) in the system measured as V2, V10A, V10B, etc. can be lowered from (V2=V10A=V10B=) 57.8 kPa to 47.4 kPa, for example, to prevent the second evaporator 10B from corresponding to a pressure vessel. However, such a method results in a large increase in the specific volume (m 3 In the case of this comparative example, if the amount of steam passing through the distillation column 2 is 1 kg / h, 57.8 kPa is converted to a specific volume of 2.83 m 3 / kg, but if this is reduced to 47.4kPa, which does not qualify as a pressure vessel, the specific volume becomes 2.83m 3 / kg to 3.41m 3 / kg. As a result, the flow rate of the steam in the distillation column 2 increases, so the diameter (body diameter) of the distillation column 2 becomes larger, and the initial cost increases accordingly.

[0055] In contrast, in the distillation apparatus 1L of this embodiment 2, a first vapor compression device 41 is connected to the top of the second evaporator 10B, and the vapor generated in the second evaporator 10B is compressed by the first vapor compression device 41. Therefore, only the pressure V10B (and the circulating liquid temperature T10B) of the second evaporator 10B can be lowered to, for example, 47.4 kPa (95.0°C), thereby making the second evaporator 10B not a pressure vessel. On the other hand, the pressure V41 at the outlet side of the first vapor compression device 41 can be raised to, for example, 57.8 kPa, which is equal to the pressure in the original system (V2 = V10A =). Therefore, the specific volume of vapor is not increased, and therefore the diameter (body diameter) of the distillation column 2 is not increased.

[0056] (Embodiment 3) FIG. 3 is an overall configuration diagram of the distillation apparatus 1M according to the third embodiment, FIG. 4 is a perspective view of the distillation apparatus 1M according to the third embodiment, and FIG. 5 is a front view of the distillation apparatus 1M according to the third embodiment. FIG. 3 is a schematic diagram of the evaporator as viewed from the direction of the arrow A in FIG. 4. Meanwhile, FIG. 5 is a schematic diagram of the evaporator as viewed from the direction of the arrow B in FIG. 4. That is, although the evaporator (evaporator can) is depicted in both FIG. 3 and FIG. 5 in a schematic manner, the evaporator is depicted from a different viewing direction in each drawing in order to facilitate illustration. Also, in FIG. 5, piping related to the evaporator is omitted. Below, an outline will be described with reference to FIG. 3 to FIG. 5.

[0057] In the above-mentioned second embodiment, the evaporators 10A and 10B are provided with a pair of left and right headers 14A and 15A; 14B and 15B, but they may be configured with common headers 14C and 15C as in the distillation apparatus 1M shown in Figs. 3 to 5. The evaporator (evaporator) 100 is divided into two parts, a low-concentration evaporation section 102A (a primary concentration section, corresponding to the first evaporator 10A) and a high-concentration evaporation section 102B (a secondary concentration section, corresponding to the second evaporator 10B), by a partition plate 101. A common header 14C is provided on one side of the low-concentration evaporation section 102A and the high-concentration evaporation section 102B, and a common header 15C is provided on the other side of the low-concentration evaporation section 102A and the high-concentration evaporation section 102B. The common header 14C is an inlet side common header to which heating steam is supplied, and the common header 15C is an outlet side common header in which condensate generated by heat exchange with the circulating liquid sprayed on the outside of the heat transfer tube group when the heating steam passes through the heat transfer tube group is stored. In addition, in Figures 3 and 4, 80A is a pipe that guides the heating steam from the second vapor compression device 42 to the common header 14C, and is used in place of the pipes 80, 81 in Figure 2.

[0058] In the distillation apparatus 1M of this embodiment 3, as shown in Figure 3, similarly to the case of the distillation apparatus 1L of the above-mentioned embodiment 2, the upper part of the secondary concentration section (high concentration evaporation section 102B) is connected to the inlet side of the first vapor compression device 41 via pipe 76, the outlet side of the first vapor compression device 41 is connected to the bottom of the distillation column 2 via pipe 85, and the top of the distillation column 2 is connected to the inlet side of the second vapor compression device 42 via pipe 79, and the outlet side of the second vapor compression device 42 is connected to the common header 14C via pipe 80A.

[0059] In this way, in the distillation apparatus 1M shown in Figures 3 to 5, a configuration in which one evaporator is divided into two can be used, making it possible to reduce the size and cost of the apparatus compared to embodiment 2 which uses two evaporators.

[0060] Furthermore, if one evaporator is divided into two and the header is also divided into two, it can be applied to a distillation apparatus configured to use a primary compressor and a secondary compressor as a second vapor compression device, as exemplified later, and supply compressed vapor from the primary compressor to evaporator 10A and compressed vapor from the secondary compressor (vapor obtained by further compressing the compressed vapor from the primary compressor) to evaporator 10B.

[0061] (Other matters) (1) In the above-mentioned embodiment 2, the second vapor compression device 42 is composed of one compressor, and the vapor compressed by the second vapor compression device 42 is configured to be introduced into the first evaporator 10A and the second evaporator 10B, respectively. However, as mentioned in the above-mentioned embodiment 3, for example, the second vapor compression device may be configured to include a primary compressor that compresses the vapor supplied from the top of the distillation column, and a secondary compressor that further compresses the vapor compressed by the primary compressor, and to branch the vapor compressed by the secondary compressor and introduce it into the second evaporator 10B through a pipe, and to branch the vapor compressed by the primary compressor and introduce it into the first evaporator 10A through a pipe. In this configuration, the operation of the distillation apparatus is similar to that of the distillation apparatus 1L according to the above-mentioned embodiment 2, except that the vapor compressed by the primary compressor is further compressed by the secondary compressor and the compressed vapor is introduced into the second evaporator 10B. In this manner, by further compressing and heating only the steam supplied to the second evaporator 10B by the secondary compressor, the stored liquid can be evaporated and concentrated with the minimum amount of heat required according to the respective stored liquid concentrations in the first evaporator 10A and the second evaporator 10B, thereby reducing power consumption and achieving energy savings.

[0062] (2) In the above-mentioned first embodiment, one evaporator is provided, and in the above-mentioned second embodiment, two evaporators are provided, but they may be configured with three or more evaporators.

[0063] Furthermore, for example, when the reboiler is divided into three parts and provided with a first evaporator, a second evaporator and a third evaporator, the distillation column 2 may be provided with a primary compressor that compresses steam supplied from the top of the column, a secondary compressor that further compresses the steam compressed by the primary compressor, and a tertiary compressor that further compresses the steam compressed by the secondary compressor, and may be configured so that the steam compressed by the tertiary compressor is introduced into the third evaporator via a pipe, the steam compressed by the secondary compressor is branched and introduced into the second evaporator via a pipe, and the steam compressed by the primary compressor is branched and introduced into the first evaporator via a pipe.

[0064] In the above-mentioned configuration, the first vapor compression device may be provided in any one of the first evaporator, the second evaporator, and the third evaporator, but it is particularly preferable to provide it in the third evaporator.

[0065] (3) In the above-mentioned first to third embodiments, the first vapor compression device 4, 41 is configured with one vapor compressor, but it may be configured with two or more vapor compressors, and in this case, these multiple vapor compressors may be connected in series or in parallel. This configuration is also applicable to the second vapor compression device.

[0066] (4) In the above-mentioned embodiment 1, a first vapor compression device 4 is provided but a second vapor compression device is not provided, whereas in the above-mentioned embodiments 2 and 3, both a first vapor compression device 41 and a second vapor compression device 42 are provided. However, for example, a second vapor compression device may be provided in the above-mentioned embodiment 1.

[0067] (5) In the above-mentioned embodiments 2 and 3, a first vapor compression device 41 was provided at the top of the second evaporator 10B and the high concentration evaporation section 102B, which correspond to the secondary concentration section, respectively. In addition to this, a first vapor compression device may be provided at the top of the primary concentration section.

[0068] (6) In the above-mentioned second embodiment, the steam evaporated in a thin film on the outside of the heat transfer tube group 13B in the second evaporator 10B is supplied to the bottom of the distillation column 2. However, as in the distillation apparatus 1N shown in FIG. 6, the steam may be supplied to the bottom of the first evaporator 10A. With this configuration, in the first evaporator 10A, the high-concentration generated steam supplied to the bottom is brought into gas-liquid contact with the low-concentration circulating liquid sprayed from the sprayer 11A, and the low-concentration circulating liquid is evaporated to generate the low-concentration generated steam, which is then evaporated and concentrated. From the pipe 72, the low-concentration generated steam and the high-concentration generated steam after the gas-liquid contact flow out and are supplied to the bottom of the distillation column 2. In this way, the high-concentration generated steam generated in the second evaporator 10B is brought into gas-liquid contact with the low-concentration circulating liquid in the first evaporator 10A, thereby reducing the solvent concentration in the high-concentration generated steam and reducing the solvent concentration in the steam to the distillation column.

[0069] In the distillation apparatus 1N according to this example, as in the distillation apparatus 1L according to the second embodiment, the top of the distillation column 2 is connected to the inlet side of the second vapor compression device 42 via a pipe 79, and the outlet side of the second vapor compression device 42 is connected to the header 15A of the heater 12A via a pipe 80, while the top of the second evaporator 10B is connected to the inlet side of the first vapor compression device 401 via a pipe 82, and the outlet side of the first vapor compression device 401 is connected to the bottom of the first evaporator 10A via a pipe 86. The high-concentration generated steam supplied to the bottom of the first evaporator 10A is supplied to the bottom of the distillation column 2 via the pipe 72 after being brought into gas-liquid contact with the low-concentration circulating liquid as described above. That is, the steam evaporated in a thin film outside the heat transfer tube group 13B in the second evaporator 10B is compressed by the first vapor compression device 401 and supplied to the bottom of the distillation column 2 via the pipe 86, the first evaporator 10A, and the pipe 72. This configuration can also be applied to a distillation apparatus having three or more evaporators in which the reboiler is divided into three or more sections.

[0070] (7) In the above embodiment 1, the raw liquid is fed to the reboiler, and in the above embodiment 2, the raw liquid is fed to the low-concentration reboiler. However, the raw liquid may be fed to any one of the bottom of the distillation column, the middle part of the distillation column, or the top of the distillation column. [Industrial Applicability]

[0071] The present invention can be applied to a distillation apparatus including a distillation column and a reboiler that heats the liquid stored in the bottom of the distillation column. [Explanation of symbols]

[0072] 1: Distillation apparatus 2: Distillation tower 3: Reboiler (horizontal tube heat exchanger) 4, 41: First vapor compression unit 42: Second vapor compression unit

Claims

1. A distillation column; A reboiler that heats and evaporates the liquid stored in the bottom of the distillation column; a first vapor compression device that compresses the vapor generated in the reboiler and sends the vapor to the distillation column; Equipped with The reboiler includes at least a primary concentrating section that evaporates and concentrates the stored liquid supplied thereto, and a secondary concentrating section that further evaporates and concentrates the stored liquid concentrated in the primary concentrating section, A distillation apparatus equipped with a distillation column, wherein the first vapor compression device is configured to compress vapor generated in a secondary concentration section of the reboiler and send the vapor to the distillation column.

2. A distillation column; A reboiler that heats and evaporates the liquid stored in the bottom of the distillation column; a first vapor compression device that compresses the vapor generated in the reboiler and sends the vapor to the distillation column; Equipped with The reboiler includes a primary concentrating section for evaporating and concentrating the stored liquid supplied thereto, a secondary concentrating section for further evaporating and concentrating the stored liquid concentrated in the primary concentrating section, and a tertiary concentrating section for further evaporating and concentrating the stored liquid concentrated in the secondary concentrating section, from the primary concentrating section to the nth concentrating section (n is an integer of 3 or more) at the rear end, The distillation apparatus is characterized in that the first vapor compression device is configured to compress the vapor generated in the rearmost n-th concentration section in the reboiler and send it to the distillation column.

3. 3. A distillation apparatus comprising the distillation column according to claim 1 or 2, further comprising a reservoir liquid supply line for supplying the reservoir liquid to the reboiler.

4. A distillation apparatus comprising the distillation column according to any one of claims 1 to 3, further comprising a second vapor compression device for compressing and heating the vapor supplied from the top of the distillation column to serve as a heat source for a reboiler.

5. The reboiler is a horizontal tube type evaporator, which is divided into two parts by a partition plate, and each divided part of the horizontal tube type evaporator is configured as the primary concentration section and the secondary concentration section, The primary concentration section and the secondary concentration section each include a heat transfer tube group through which vapor supplied from the top of the distillation column passes, and a sprayer that sprays the stored liquid toward an outer surface of the heat transfer tube group, 3. The distillation apparatus equipped with a distillation column according to claim 1 or 2, wherein an inlet side common header into which steam supplied from a top of the distillation column is introduced is provided on one side surface of the primary concentrating section and the secondary concentrating section so as to surround one end of each of the heat transfer tube groups, and an outlet side common header in which condensate produced by heat exchange between the steam introduced from the inlet side common header and a stored liquid sprayed on an outer surface of the heat transfer tube group as the steam passes through the heat transfer tube group is stored is provided on the other side surface of the primary concentrating section and the secondary concentrating section so as to surround the other end of each of the heat transfer tube groups.

6. 6. A distillation apparatus comprising the distillation column according to claim 1, wherein condensed water produced by heat exchange with the steam supplied to the reboiler is returned to the top of the distillation column as reflux water.

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