JP7629189B2 - Distillation apparatus equipped with a distillation column - Google Patents

Description

The present invention relates to a distillation apparatus equipped with a distillation column, and more specifically, to a distillation apparatus equipped with a distillation column and a reboiler that heats the liquid stored in the bottom of the distillation column.

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 fractional vapor within the distillation column (see Patent Document 1 below).

JP 2017-192868 A

In the distillation apparatus of the above-mentioned conventional example, as the solvent concentration of the concentrated liquid is increased in the reboiler (or the evaporator used as the reboiler), the boiling point rises, and when it rises above a certain level, the reboiler becomes a pressure vessel. In that case, a statutory inspection becomes necessary, and a licensed factory is 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 can be considered. However, with such a method, the specific volume of steam ( ^m3 /kg) increases, and the flow rate of steam in the distillation tower increases, so the diameter (body diameter) of the distillation tower becomes large, which causes a problem of an increase in initial cost.

The present invention was conceived in consideration of the above problems, and its purpose is to provide a distillation apparatus in which the reboiler does not correspond to a pressure vessel and the size of the distillation column is not increased.

In order to achieve the above object, a distillation apparatus equipped with a distillation tower according to the invention described in claim 1 comprises a distillation tower, a reboiler which heats and evaporates a stored liquid stored in the bottom of the distillation tower, and a first vapor compression device which compresses the vapor generated in the reboiler and sends it to the distillation tower, wherein the reboiler comprises at least a primary concentration section which evaporates and concentrates the stored liquid supplied thereto, and a secondary concentration section which further evaporates and concentrates the stored liquid concentrated in the primary concentration section, and the first vapor compression device is configured to compress the vapor generated in the secondary concentration section of the reboiler and send it to the distillation tower .

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 is advantageous in that the cost of the reboiler itself can be reduced .

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.

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 also possible to review the distillation tower size to be smaller. In addition, since the reflux water will evaporate 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)

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.

The distillation apparatus according to the invention having a distillation column according to claim 2 comprises a distillation column, a reboiler for heating and evaporating a liquid stored in the bottom of the distillation column, and a first vapor compression device for compressing the vapor generated in the reboiler and sending it to the distillation column, wherein the reboiler comprises a primary concentration section for evaporating and concentrating the stored liquid supplied thereto, a secondary concentration section for further evaporating and concentrating the stored liquid concentrated in the primary concentration section, and a tertiary concentration section for further evaporating and concentrating the stored liquid concentrated in the secondary concentration section, from the primary concentration section to the nth concentration section (n is an integer of 3 or more) at the rear, and the first vapor compression device is configured to compress the vapor generated in the nth concentration section at the rear of the reboiler and send it to the distillation column .

The 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 further comprises a retained liquid supply pipe for supplying the retained liquid to the reboiler.

The distillation apparatus equipped with the distillation column according to the invention described in claim 4 is a distillation apparatus equipped with the distillation column according to any one of the inventions described in claims 1 to 3, characterized in that it further comprises a second vapor compression unit which compresses and heats vapor supplied from the top of the distillation column and uses the vapor as a heating source for a reboiler .

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.

The distillation apparatus equipped with the distillation column according to the invention described in claim 5 is a distillation apparatus equipped with the distillation column according to the invention described in claim 1 or 2 , wherein the reboiler is a single horizontal tube type evaporator, and the horizontal tube type evaporator 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 equipped with a heat transfer tube group through which steam 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, and the first concentration section and the secondary concentration section are equipped with a heat transfer tube group through which steam 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, The present invention is characterized in that an inlet side common header, into which steam supplied from the top of the distillation column is introduced, 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, in which condensate produced by heat exchange between the steam introduced from the inlet side common header and a stored liquid sprayed on the outer surface of the heat transfer tube group as it 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.

The above configuration allows one evaporator to be divided into two, which makes it possible to reduce the size and cost of the device compared to a configuration using two evaporators.

The distillation apparatus equipped with the distillation column according to the invention described in claim 6 is a distillation apparatus equipped with the distillation column according to any one of the inventions described in claims 1 to 5 , characterized in that the condensed water produced by heat exchange of the steam supplied to the reboiler is returned to the top of the distillation column as reflux water.

According to the present invention, the reboiler does not fall under the category of a pressure vessel. In addition, the size of the distillation column does not increase, and therefore costs can be suppressed.

FIG. 1 is an overall configuration diagram of a distillation apparatus according to a first embodiment. FIG. 1 is an overall configuration diagram of a distillation apparatus according to a second embodiment. FIG. 11 is an overall configuration diagram of a distillation apparatus according to a third embodiment. FIG. 11 is a perspective view of a distillation apparatus according to a third embodiment. FIG. 11 is a front view of a distillation apparatus according to a third embodiment. FIG. 13 is an overall configuration diagram of a distillation apparatus according to yet another example.

The present invention will be described in detail below based on the embodiments. Note that the present invention is not limited to the following embodiments.

(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 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 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 alcohol-based cleaning agents (including surfactants).

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 this embodiment 1, the first vapor compression device 4 is composed of a single 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.

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. Note that the evaporator 10 is not limited to the horizontal tube type, and may be, for example, a thin film flow (vertical tube) type evaporator.

The indirect heater 12 is equipped with 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 treatment liquid is stored. The raw liquid is supplied to the bottom of the evaporator 10 through a raw liquid supply pipe 22.

The evaporator 10 has a circulation flow path h1 (composed of tubes 70 and 71) for the raw liquid or concentrated liquid. A circulation pump P1 and a sprayer 11 are arranged in the circulation flow path h1. The circulation pump P1 is connected to the bottom of the distillation tower 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 tower 2 to the sprayer 11 through the tube 70. In other words, the tube 70 is a stored liquid supply pipe that supplies the stored liquid stored in the bottom of the distillation tower 2 to the reboiler 3. The tube 70 has a branch pipe 83 that branches off in the middle, so that a part of the concentrated liquid obtained by concentrating the raw liquid can be recovered and discharged outside the system as a recovered liquid through the branch pipe 83. The sprayer 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.

The bottom of the header 14 in the heater 12 is connected to a sprayer 20 provided at the top of the distillation column 2 via a pipe 74. A pump P2 is provided in the pipe 74, and the condensed water stored in the header 14 is sprayed from the sprayer 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.

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.

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 that has evaporated in a thin film outside the heat transfer tube group 13 is compressed by 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 a turbo type vapor compressor, a Roots type vapor compressor, or any other vapor compressor.

Next, the processing operation of the distillation apparatus 1 configured as above 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 tower is supplied to the sprayer 11 through the tube 70, and is sprayed from the sprayer 11 toward the heat transfer tube group 13. The circulating liquid sprayed by the sprayer 11 evaporates into 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 and supplied to the bottom of the distillation tower 2, and rises inside the distillation tower 2.

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 comes into gas-liquid contact with the treated water (condensed water) flowing down inside the distillation tower 2, separating components with different boiling points, and a concentrated liquid of 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.

The steam that enters the header 15 is guided inside the heat transfer tube group 13 and evaporates the circulating liquid sprayed on the outside of the heat transfer tube group 13 into 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 tower 2, where it rises inside the distillation tower 2 and comes into gas-liquid contact with the treated water (condensed water) that descends inside the distillation tower 2 from the top of the tower. 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 into a thin film is supplied from the bottom of the evaporator 10 to the bottom of the distillation tower 2 through the tube 71 and is stored in the storage chamber 44 at the bottom of the tower. This series of processes is then repeated, whereby the circulating liquid is concentrated.

According to the first embodiment, the steam generated in the reboiler 3 is compressed by the first steam compression device 4, so the pressure in the reboiler 3 can be reduced. Therefore, the reboiler 3 is configured so as not to be a pressure vessel. In addition, because the pressure in 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 has the advantage of enabling the cost of the reboiler 3 itself to be reduced.

In addition, by compressing the vapor using the first vapor compression device 4, the specific volume of the vapor can be reduced, which prevents the vapor flow rate in the distillation column 2 from increasing. This prevents the diameter (body diameter) of the distillation column 2 from becoming large, and therefore prevents increases in costs.

The specific configuration of another embodiment of the present invention will be described below. Note that in the following description and drawings, parts and members similar to those described in the first embodiment above will be given the same reference numerals, and their description will basically be omitted unless necessary.

(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, but 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 concentration of the stored liquid evaporated and concentrated in the second evaporator 10B is configured to be higher than the concentration of the stored liquid 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.

By dividing the reboiler 3L in this way, the boiling point is lowered compared to a single unit (when not divided), making the effective heat transfer temperature difference larger and improving the heat transfer efficiency, so the heat transfer area of the reboiler (evaporator) can be reduced and the heat transfer area can be made more compact.

The first evaporator 10A and the second evaporator 10B are both horizontal tube type evaporators and have the same configuration, with the first evaporator 10A having the same configuration as the evaporator 10 according to the first embodiment. For this reason, the following explanation will mainly focus on the second evaporator 10B. 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.

The first evaporator 10A and the second evaporator 10B are equipped with diffusers 11A, 11B and indirect heaters 12A, 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.

The indirect heaters 12A and 12B are equipped 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 and 15A; 14B and 15B. The bottoms of the evaporators 10A and 10B serve as storage areas in which the treatment liquid is stored. The raw liquid is supplied to the bottom of the first evaporator 10A through a raw liquid supply pipe 22.

The second evaporator 10B has a circulation flow path h2 for the raw liquid or 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.

The pipe 70 in the circulation flow path h1 of the first evaporator 10A has a branch pipe 73 that branches 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 line that supplies the liquid stored in the bottom of the distillation column 2 to the reboiler 3L.

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 that has 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 a turbo type vapor compressor, a Roots type vapor compressor, or any other vapor compressor.

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

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 has 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 a turbo type vapor compressor, a Roots type vapor compressor, or any other vapor compressor.

Next, the processing operation of the distillation apparatus 1L according to the second embodiment will be described. The processing operation of the first evaporator 10A is the same as the processing operation of the evaporator 10 according to the first embodiment, and therefore the description will be omitted.

The steam extracted 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 the temperature and pressure, and then sent to the headers 15A and 15B.

The steam that enters 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 tower 2 and rises inside the distillation tower 2, where it comes into gas-liquid contact with the treated water (condensed water) descending from the top of the distillation tower 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 tower 2 through the pipe 71 and is stored in the storage chamber 44 at the bottom of the tower. This series of processes is repeated, and the circulating liquid is concentrated, and this concentrated concentrated liquid is supplied to the bottom of the second evaporator 10B through the branch pipe 73.

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 sprayer 11B through the circulation flow path h2 by driving the circulation pump P3, and is sprayed from the sprayer 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 sprayed by the sprayer 11B evaporates in a thin film on the surface of the heat transfer tube group 13B, generating steam. 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 sprayed from the sprayer 11B again through the circulation flow path h2, generating steam by thin film evaporation. By repeating this 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).

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

In this way, in this second embodiment, the stored liquid concentrated in the first evaporator 10A is low concentration (low boiling point), and the stored liquid concentrated in the second evaporator 10B is high concentration (high boiling point). Therefore, in this second embodiment, compared to a configuration with only one reboiler (a configuration with an undivided reboiler), 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 being processed is lowered, the effective heat transfer temperature difference of the reboiler can be made larger, and the heat transfer coefficient is also improved, so that the heat transfer area of the reboiler can be prevented from becoming large.

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. As a result, the evaporation load can be reduced, and power consumption can be reduced.

The distillation apparatus 1L according to the second embodiment is equipped with a second steam 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. This steam can be reused as a heat source for the reboiler 3L, thereby saving energy in the distillation apparatus 1L.

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 the first vapor compression device 41 is connected to the top of this second evaporator 10B, so that the effect of the feature of the present invention in compressing the vapor generated in the reboiler by the first vapor compression device 41 is further enhanced.

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 (degree of vacuum) 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 series of processes are repeated in the distillation apparatus according to this comparative example to concentrate the circulating liquid (concentrated liquid) and increase the solvent concentration, the circulating liquid temperature in the first evaporator 10A remains low (e.g., T10A = 87.0°C), but in contrast, the boiling point in the second evaporator 10B increases, and when it increases to a certain level (e.g., 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 57.8 kPa to 47.4 kPa (V2 = V10A = V10B =), for example, so that the second evaporator 10B does not correspond to a pressure vessel. However, such a method increases the specific volume (m ³ /kg) of steam. 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 lowered to 47.4 kPa, which does not correspond to a pressure vessel, the specific volume increases from 2.83 m ³ /kg to 3.41 m ³ /kg. As a result, the flow rate of the vapor in the distillation column 2 increases, so that the diameter (body diameter) of the distillation column 2 becomes larger, and the initial cost increases accordingly.

In contrast, in the distillation apparatus 1L according to the second embodiment, the 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), so that the second evaporator 10B does not correspond to 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 =), so that the specific volume of the vapor is not increased, and therefore the diameter (body diameter) of the distillation column 2 does not become large.

(Embodiment 3)
FIG. 3 is a diagram showing the overall configuration 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 drawing of the evaporator as viewed from the direction of the arrow A in FIG. 4. On the other hand, FIG. 5 is a schematic drawing 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 direction in each drawing in order to facilitate the illustration. Also, in FIG. 5, the piping related to the evaporator is omitted. Below, an outline will be described with reference to FIG. 3 to FIG. 5.

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

As shown in FIG. 3, in the distillation apparatus 1M according to the third embodiment, as in the case of the distillation apparatus 1L according to the second embodiment, 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.

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

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.

(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, for example, as mentioned in the above-mentioned embodiment 3, 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 the same as 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 way, by further compressing and heating only the steam supplied to the second evaporator 10B by the secondary compressor, the evaporation and concentration of the stored liquid can be performed 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.

(2) In the above embodiment 1, one evaporator was provided, and in the above embodiment 2, two evaporators were provided, but it may be configured with three or more evaporators.

Furthermore, for example, when the reboiler is divided into three parts and includes a first evaporator, a second evaporator, and a third evaporator, the distillation column 2 may be configured to include a primary compressor that compresses the 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 to introduce the steam compressed by the tertiary compressor into the third evaporator via a pipe, while branching the steam compressed by the secondary compressor into the second evaporator via a pipe, and branching the steam compressed by the primary compressor into the first evaporator via a pipe.

In the above configuration, the first vapor compression device may be provided in any of the first, second, and third evaporators, but it is particularly preferable to provide it in the third evaporator.

(3) In the above embodiments 1 to 3, 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 the same for the second vapor compression device.

(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.

(5) In the above-mentioned second and third embodiments, a first vapor compression device 41 is provided at the top of the second evaporator 10B and the high concentration evaporation section 102B, which correspond to the secondary concentration section. In addition, a first vapor compression device may be provided at the top of the primary concentration section.

(6) In the above-mentioned second embodiment, the vapor evaporated in a thin film outside the heat transfer tube group 13B in the second evaporator 10B is supplied to the bottom of the distillation column 2. However, for example, as in the distillation apparatus 1N shown in FIG. 6, it may be configured to be supplied to the bottom of the first evaporator 10A. With this configuration, in the first evaporator 10A, the high-concentration generated vapor supplied to the bottom and the low-concentration circulating liquid sprayed from the sprayer 11A come into gas-liquid contact, the low-concentration circulating liquid evaporates, the low-concentration generated vapor is generated, and evaporation and concentration are performed. From the tube 72, the low-concentration generated vapor and the high-concentration generated vapor after gas-liquid contact flow out and are supplied to the bottom of the distillation column 2. In this way, by bringing the high-concentration generated vapor generated in the second evaporator 10B into gas-liquid contact with the low-concentration circulating liquid in the first evaporator 10A, the solvent concentration in the high-concentration generated vapor can be reduced, and the solvent concentration in the vapor to the distillation column can be reduced.

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 upper part 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.

(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, but the raw liquid may be fed to any of the bottom, middle, and top of the distillation tower.

The present invention can be applied to a distillation apparatus equipped with a distillation column and a reboiler that heats the liquid stored in the bottom of the distillation column.

1: Distillation apparatus 2: Distillation column 3: Reboiler (horizontal tube heat exchanger)
4, 41: First vapor compression device 42: Second vapor compression device

Claims (6)

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 . 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 nth concentration section at the rear end of the reboiler and send it to the distillation column . 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 . 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 . 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. 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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