Distillation apparatus

Abstract

To provide a distillation apparatus that is improved in energy-saving efficiency, by effectively utilizing heat that cooling water for cooling overhead vapor has and suppressing scale from being generated in a distillation column.SOLUTION: A distillation apparatus is provided with: a distillation column 1; an evaporator that heats pure water to generate vapor to be blown to the distillation column; a capacitor 11 that cools and condenses overhead vapor to recover condensed water; a heat pump HP that is used in the capacitor, which recovers heat from heated circulating / cooling water for the capacitor and increases a level of the temperature of the recovered heat by electric power to heat the pure water; and a pressure control mechanism that controls pressure in a system so that the temperature of liquid at a column bottom of the distillation column can be kept at a predetermined temperature.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a distillation apparatus using a heat pump, and more particularly to a distillation apparatus used for distilling a raw material liquid containing water and a bottom boiling point component having a boiling point lower than that of water, and separating the low boiling point component from the raw material liquid. [Background technology]

[0002] In recent years, the need for energy saving in distillation apparatus has been increasing, and various proposals have been made.

[0003] As one such energy-saving technology, a distillation apparatus has been proposed in which a heat pump is incorporated in the distillation apparatus to improve thermal efficiency (see, for example, Patent Document 1). In the distillation apparatus of Patent Document 1, the heat pump is used to pump up the heat of the cooling water used to cool the overhead vapor in the overhead condenser that cools the overhead vapor of the distillation tower. The heat pumped up by the heat pump is used as a heat source for a reboiler that reheats the bottom liquid of the distillation tower, thereby saving energy. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6612936 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the case of the distillation apparatus of Patent Document 1, the heat pumped up by the heat pump is used to heat the bottom liquid of the distillation tower. For example, when the bottom liquid of the distillation tower contains substances that cause scale generation, such as calcium or silica, scale will be generated on the heat transfer surface (surface in contact with the bottom liquid) of the reboiler (heater) for reheating the bottom liquid of the distillation tower. That is, there is a problem that scale is generated on the heat transfer surface (surface in contact with the bottom liquid) of the heat exchanger (reboiler heater), which reduces the heat transfer efficiency and impairs the energy saving effect. Even though the heat pump is used to pump up and utilize the heat of the overhead condenser, it leads to a situation where the intended energy saving effect cannot be obtained.

[0006] An object of the present disclosure is to provide a distillation apparatus that can effectively utilize the heat contained in the cooling water used to cool the overhead vapor by using a heat pump as a heat source for performing a distillation operation, and that can suppress the formation of scale on the equipment even when the liquid to be treated contains substances that cause scale formation, without requiring a reboiler for reheating the bottom liquid of the distillation tower as in the distillation apparatus of Patent Document 1, thereby enabling stable, continuous operation with improved energy saving efficiency. [Means for solving the problem]

[0007] In order to achieve the above object, the distillation apparatus of the present disclosure is configured as follows.

[0008] A distillation apparatus according to one embodiment of the present disclosure includes a distillation column, a condenser, a heat pump, an evaporator, a reflux path, and a pressure control mechanism. The distillation column distills a raw material liquid containing water and a low-boiling point component having a boiling point lower than that of water. The condenser cools and condenses the overhead vapor taken out from the top of the distillation column by circulating cooling water for the condenser, and recovers a condensate mainly composed of the low-boiling point component. The heat pump recovers heat from the circulating cooling water for the condenser, which has been used to cool the overhead vapor in the condenser and has been heated, and uses the recovered heat to increase the temperature level by electric power to heat pure water. The evaporator directly flash evaporates the pure water heated by the heat pump, generating steam that is supplied to be blown into the bottom liquid of the distillation column. The reflux path refluxes a portion of the condenser condensate to the distillation column as a reflux liquid for the distillation column. The pressure control mechanism controls the pressure in the system so that the temperature of the bottom liquid of the distillation column is maintained at a predetermined temperature.

[0009] A distillation apparatus according to another embodiment of the present disclosure includes a first distillation column, a first condenser, a heat pump, an evaporator, a second distillation column, a second condenser, a first reflux path, a second reflux path, and a pressure control mechanism. The first distillation column distills a raw material liquid containing water and a low-boiling point component having a boiling point lower than that of water. The first condenser cools a first overhead vapor taken out from the top of the first distillation column with circulating cooling water for the first condenser, and separates the first overhead vapor into a first condensate and a first vapor containing a higher proportion of low-boiling point components than the first condensate. The heat pump recovers heat from the circulating cooling water for the first condenser, which has been used to cool the first overhead vapor in the first condenser and has been heated, and uses the recovered heat to raise the temperature level by electric power to heat the pure water. The evaporator directly flash-evaporates the pure water heated by the heat pump, generating steam to be blown into the bottom liquid of the first distillation column. The second distillation column distills the first vapor, which is the vapor after partial condensation in the first condenser, by bringing it into gas-liquid contact with the second condensate. The second condenser cools and condenses the second overhead vapor taken out from the top of the second distillation column using circulating cooling water for the second condenser, and recovers a second condensate mainly composed of low boiling point components. The first reflux line refluxes the first condensate in the first condenser to the first distillation column as a reflux liquid for the first distillation column. The second reflux line refluxes a portion of the second condensate in the second condenser to the second distillation column as a reflux liquid for the second distillation column. The pressure control mechanism controls the pressure in the system so that the temperature of the bottom liquid of the first distillation column is maintained at a predetermined temperature. Effect of the Invention

[0010] According to the distillation apparatus of the present disclosure, the heat of the cooling water used to cool the overhead vapor can be pumped up by a heat pump and effectively utilized as a heat source for performing the distillation operation. Furthermore, unlike the distillation apparatus of Patent Document 1, a reboiler for reheating the bottom liquid of the distillation tower is not required. Therefore, even if the liquid to be treated contains a substance that causes scale generation, it is possible to provide a distillation apparatus that can suppress the generation of scale on the equipment and perform stable and continuous operation with improved energy saving efficiency. [Brief description of the drawings]

[0011] [Figure 1] A flow chart showing the configuration of a distillation apparatus according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Prior to describing the embodiments of the present disclosure, aspects of the distillation apparatus of the present disclosure will be described.

[0013] The distillation apparatus according to the first aspect of the present disclosure includes a distillation column, a condenser, a heat pump, an evaporator, a reflux path, and a pressure control mechanism. The distillation column distills a raw material liquid containing water and a low-boiling point component having a boiling point lower than that of water. The condenser cools and condenses the overhead vapor taken out from the top of the distillation column by circulating cooling water for the condenser, and recovers a condensate mainly composed of the low-boiling point component. The heat pump recovers heat from the circulating cooling water for the condenser, which has been used to cool the overhead vapor in the condenser and has been heated, and uses the recovered heat to increase the temperature level by electric power to heat the pure water. The evaporator directly flash evaporates the pure water heated by the heat pump, generating steam that is supplied to be blown into the bottom liquid of the distillation column. The reflux path refluxes a part of the condenser condensate to the distillation column as a reflux liquid for the distillation column. The pressure control mechanism controls the pressure in the system so that the temperature of the bottom liquid of the distillation column is maintained at a predetermined temperature.

[0014] A distillation apparatus according to a second aspect of the present disclosure includes a first distillation column, a first condenser, a heat pump, an evaporator, a second distillation column, a second condenser, a first reflux path, a second reflux path, and a pressure control mechanism. The first distillation column distills a raw material liquid containing water and a low-boiling point component having a boiling point lower than that of water. The first condenser cools a first overhead vapor taken out from the top of the first distillation column with circulating cooling water for the first condenser, and separates the first overhead vapor into a first condensate and a first vapor containing a higher proportion of low-boiling point components than the first condensate. The heat pump recovers heat from the circulating cooling water for the first condenser, which has been used to cool the first overhead vapor in the first condenser and has been heated, and uses the recovered heat to increase the temperature level by electric power to heat the pure water. The evaporator directly flash-evaporates the pure water heated by the heat pump, generating steam to be supplied to be blown into the bottom liquid of the first distillation column. The second distillation column distills the first vapor, which is the vapor after partial condensation in the first condenser, by bringing it into gas-liquid contact with the second condensate. The second condenser cools and condenses the second overhead vapor taken out from the top of the second distillation column using circulating cooling water for the second condenser, and recovers a second condensate mainly composed of low boiling point components. The first reflux line refluxes the first condensate in the first condenser to the first distillation column as a reflux liquid for the first distillation column. The second reflux line refluxes a portion of the second condensate in the second condenser to the second distillation column as a reflux liquid for the second distillation column. The pressure control mechanism controls the pressure in the system so that the temperature of the bottom liquid of the first distillation column is maintained at a predetermined temperature.

[0015] In the distillation apparatus of the present disclosure, pure water (e.g., soft water or RO water) from which components that cause scale formation, such as calcium and silica, have been removed in advance is supplied to an evaporator, the pure water is heated by a heat pump, the pure water is flash evaporated in the evaporator, and the generated steam is directly blown into the bottom liquid of the first distillation column. Therefore, even if the bottom liquid contains components that cause scale formation, such as calcium and silica, there is no risk of scale formation on the heat transfer surface of the reboiler, which would otherwise cause a decrease in heat transfer efficiency, as occurs when a reboiler is used to heat the bottom liquid of the distillation column.

[0016] Therefore, the heat of the cooling water used to cool the overhead vapor can be pumped up by a heat pump and effectively utilized as a heat source for the distillation operation. Furthermore, a distillation apparatus can be provided that can stably and continuously perform a distillation operation with improved energy saving efficiency without causing problems such as the formation of scale on the heat transfer surface.

[0017] Furthermore, since the evaporator only comes into contact with pure water, there is no risk of scaling or corrosion, and there is a high degree of freedom in selecting the type and constituent materials of the evaporator, making it possible to reduce costs.

[0018] A distillation apparatus according to a third aspect of the present disclosure is the distillation apparatus according to the first or second aspect, in which the pressure control mechanism includes a vacuum suction means for suctioning a vacuum via a condenser or a second condenser so that the inside of the system is at a predetermined vacuum level. This makes it possible to control the temperature in the system to a temperature at which the heat recovered by the heat pump can be efficiently utilized without requiring equipment with a complex structure, thereby making it possible to more effectively utilize the distillation apparatus of the present disclosure.

[0019] A distillation apparatus according to a fourth aspect of the present disclosure is the distillation apparatus of any one of the first to third aspects, wherein the pressure control mechanism controls the pressure within the system so that the temperature of the bottom liquid of the distillation column or the first distillation column is 98°C or lower.

[0020] According to this configuration, the heat pump can be operated under high COP conditions, thereby realizing higher energy saving efficiency. By adjusting the operating pressure in the system including the inside of the distillation column so that the temperature of the bottom liquid of the distillation column or the first distillation column is 98°C or lower, the steam generated from the evaporator can be stably blown into the bottom liquid of the distillation column or the first distillation column, thereby enabling efficient and stable distillation operation.

[0021] A distillation apparatus according to a fifth aspect of the present disclosure is the distillation apparatus according to any one of the first to fourth aspects, in which the raw material liquid contains a lower proportion of low boiling point components than water. In the distillation apparatus of the present disclosure, steam generated in an evaporator is blown into the bottom liquid of the first distillation column. This makes it possible to perform efficient stripping to separate the low boiling point components when the raw material liquid contains a lower proportion of low boiling point components than high boiling point components, and allows the distillation apparatus of the present disclosure to be used more effectively.

[0022] In this disclosure, "pure water" that is heated to generate steam in an evaporator refers to water from which components that cause scale formation, such as calcium and silicon, have been previously removed using, for example, a water softener that uses ion exchange resin (so-called soft water), or water from which components that cause scale formation, such as calcium and silicon, have been previously removed by purification using a reverse osmosis membrane filter (so-called RO water).

[0023] Hereinafter, embodiments of the present disclosure will be described in more detail, with reference to the accompanying drawings.

[0024] In this embodiment, a distillation apparatus is used as an example to distill a raw material liquid (liquid to be treated) containing 1.0 wt% acetone, a low boiling point component, and the remainder (99.0 wt%) being water, a high boiling point component, to separate and recover acetone from the raw material liquid.

[0025] The distillation apparatus 100 according to this embodiment is a distillation apparatus that uses a heat pump to improve energy saving performance.

[0026] As shown in FIG. 1, the distillation apparatus 100 of this embodiment includes a first distillation column 1, an evaporator 3, and a first condenser 11 that cools the overhead vapor (first overhead vapor) extracted from the top of the first distillation column 1.

[0027] The distillation apparatus 100 also includes a heat pump HP that recovers heat from the circulating cooling water for the first condenser, a second distillation column 2 that distills the vapor (first vapor) after partial condensation in the first condenser 11, and a second condenser 22 that cools the overhead vapor (second overhead vapor) extracted from the top of the second distillation column 2.

[0028] In this embodiment, the first condenser 11 for cooling the first overhead vapor and the second distillation column 2 for distilling the vapor (first vapor) after partial condensation in the first condenser 11 are integrally configured. That is, the second distillation column 2 is installed so as to be directly connected to the upper side of the first condenser 11, and the first condenser 11 and the second distillation column 2 are configured so that the first vapor, which is the vapor after partial condensation in the first condenser 11, is directly supplied to the bottom of the second distillation column 2. It is only necessary that the first vapor, which is the vapor after partial condensation in the first condenser 11, is supplied to the bottom of the second distillation column 2, and the first condenser 11 and the second distillation column 2 may be configured separately.

[0029] The distillation apparatus 100 is equipped with a pressure control mechanism 40 that controls the pressure within the system so that the temperature of the bottom liquid of the first distillation column 1 is maintained at a predetermined temperature.

[0030] The pressure control mechanism 40 includes a vacuum suction means 34 that performs vacuum suction via the second condenser 22 so that the inside of the system reaches a predetermined vacuum level. For example, a vacuum pump may be used as the vacuum suction means 34. The pressure control mechanism 40 also includes a pressure sensor that detects the pressure inside the system, and a control system that controls the vacuum suction of the vacuum suction means 34 based on pressure information from the pressure sensor.

[0031] In the distillation apparatus 100, as described below, the pressure within the system is controlled by a pressure control mechanism 40 to keep the temperature of the bottom liquid of the first distillation column 1 at 88° C. or lower.

[0032] The distillation apparatus 100 is equipped with a first reflux line 31 for refluxing the condensate from the first condenser 11 to the first distillation column 1, and a second reflux line 32 for refluxing the condensate from the second condenser 22 to the second distillation column 2.

[0033] The configuration of the distillation apparatus 100 of this embodiment will be described in detail.

[0034] The first distillation column 1 is a distillation column that distills, for example, an aqueous acetone solution (99.0 wt% water) containing 1.0 wt% acetone as a raw material liquid. In this embodiment, a packed column is used as the first distillation column 1. Note that, as the first distillation column 1, a column having various configurations such as a plate column may be used in addition to a packed column.

[0035] The evaporator 3 is used to directly flash evaporate the pure water heated by the heat pump HP and generate steam for directly heating the bottom liquid of the first distillation column 1. Specifically, an evaporator 3 made of stainless steel (SUS304) is used as the evaporator 3. A pure water pump 51 is provided to supply pure water to the evaporator 3 via the heat pump HP and to supply pure water remaining in the evaporator 3 that has not been supplied as steam to the heat pump HP.

[0036] In this embodiment, the pure water supplied to the heat pump HP is RO water, which has been purified using a reverse osmosis membrane filter to remove components such as calcium and silicon that cause scale formation.

[0037] The distillation apparatus 100 includes a feed liquid preheater 41, a pure water preheater 42, and a bottoms pump 52. The feed liquid preheater 41 heats the raw material liquid (feed liquid) supplied to the first distillation column 1, and the pure water preheater 42 heats the pure water supplied to the heat pump HP. The bottoms pump 52 supplies the bottoms liquid (bottoms) extracted from the bottom of the first distillation column 1 to each of the feed liquid preheater 41 and the pure water preheater 42. The feed liquid is heated by heat exchange with the bottoms in the feed liquid preheater 41, and the pure water is heated by heat exchange with the bottoms in the pure water preheater 42, thereby recovering energy.

[0038] In the first distillation column 1, acetone is distilled by gas-liquid contact between the steam generated in the evaporator 3, the raw material liquid heated in the feed liquid preheater 41, and the reflux liquid which is the condensed liquid condensed in the first condenser 11. The column bottom liquid (bottoms) from which acetone has been separated (removed) is discharged from the first distillation column 1 to the outside of the system by the bottoms pump 52. On the other hand, the column overhead vapor (first column overhead vapor) which contains acetone at a higher ratio than the raw material liquid is supplied to the first condenser 11.

[0039] The first condenser 11 cools the overhead vapor (first overhead vapor) taken out from the top of the first distillation column 1 by the circulating cooling water for the first condenser, and separates it into a first condensate and a first vapor containing a higher proportion of acetone than the first condensate. Then, this first condensate is returned as a reflux liquid to the top of the first distillation column 1. That is, in the first condenser 11, mainly the high boiling point component (water) is condensed, and the condensate (aqueous acetone solution) containing 20 wt % acetone is returned to the top of the first distillation column 1 as a reflux liquid.

[0040] The heat pump HP is used to cool the first tower overhead vapor in the first condenser 11, recovering heat from the heated circulating cooling water for the first condenser (54.5°C in this embodiment) and using the recovered heat by electricity to raise the temperature level and heat pure water.

[0041] The circulating cooling water for the first condenser is circulated between the first condenser 11 and the heat pump HP by a cooling water pump 53. The heat pump HP, for example, recovers heat from the circulating cooling water for the first condenser used in the first condenser 11, and uses the thermal energy in a circulating manner by increasing the temperature level of the recovered heat using electric power to heat pure water.

[0042] Specifically, the circulating cooling water for the first condenser at 49.5° C. is supplied to the first condenser 11 and used to cool the first tower overhead vapor, raising the temperature to 54.5° C. The circulating cooling water for the first condenser at 54.5° C. undergoes heat recovery in the heat pump HP, and the circulating cooling water for the first condenser whose temperature has been reduced to 49.5° C. is circulated and supplied to the first condenser 11.

[0043] Meanwhile, in the heat pump HP, the pure water whose temperature has been raised to 93°C by electric power is supplied to the evaporator 3, where a portion of it is flash evaporated and the steam is supplied to the first distillation column 1. The temperature of the remaining pure water (including pure water formed from condensed steam) is reduced to 88°C in the evaporator 3 and the pure water is returned to the heat pump HP by the pure water pump 51, where the temperature is raised to 93°C and then supplied to the evaporator 3 again.

[0044] The second distillation column 2 is a distillation column that distills the first vapor, which is the vapor after partial condensation in the first condenser 11, by bringing the first vapor into gas-liquid contact with the second condensate condensed in the second condenser 22, and extracts an overhead vapor (second overhead vapor) having a higher acetone concentration from the top of the column. In this embodiment, a packed column is used as the second distillation column 2. However, the second distillation column 2 may be a column having various configurations other than a packed column, such as a plate column.

[0045] In the second distillation column 2, the vapor after partial condensation in the first condenser 11, which has a high acetone concentration, is distilled, and acetone is selectively extracted into the second condenser 22.

[0046] The second condenser 22 cools the second overhead vapor, which is the overhead vapor of the second distillation column 2, with second condenser circulating cooling water, and condenses the acetone and water contained in the second overhead vapor as a second condensate.

[0047] A second condensate pump 54 that extracts the second condensate is connected to the second condenser 22. A part of the second condensate is recovered as a recovered solvent (distillate) by the second condensate pump 54, and the remaining condensate is refluxed to the top of the second distillation column 2 as a reflux liquid.

[0048] The distillation apparatus 100 includes a first reflux line 31 for refluxing the first condensate in the first condenser 11 to the first distillation column 1 as a reflux liquid for the first distillation column 1.

[0049] The distillation apparatus 100 also includes a second reflux line 32 that refluxes the second condensate in the second condenser 22 to the second distillation column 2 as a reflux liquid for the second distillation column 2.

[0050] In the distillation apparatus 100, the gas in the system is discharged via the second condenser 22 by the vacuum suction means 34, so that the distillation apparatus 100 is operated at an operating pressure (for example, 25 kPaA or more and atmospheric pressure or less) such that the temperature of the bottom liquid (bottom liquid) discharged from the bottom of the first distillation column 1 becomes 88°C. In addition, the temperature level is increased by the heat pump HP so that the temperature of the pure water supplied to the evaporator 3 becomes 93°C.

[0051] If the temperature level of the pure water obtained from the general-purpose heat pump HP is about 93°C, and the return temperature of the pure water returning from the evaporator 3 to the heat pump HP is 88°C, the temperature of the steam generated in the evaporator 3 will be about 88°C. Therefore, the pressure (operating pressure) in the equipment such as the first distillation column 1 and the second distillation column 2 is adjusted so that the temperature of the bottom liquid of the first distillation column 1 is 88°C or less. This allows the steam generated from the evaporator 3 to be stably blown into the bottom liquid of the first distillation column 1 in the distillation apparatus 100, thereby enabling efficient and stable distillation operation. Note that by selecting the specifications of the heat pump, the pressure (operating pressure) in the equipment such as the first distillation column 1 and the second distillation column 2 may be adjusted so that the temperature of the bottom liquid of the first distillation column 1 is 98°C or less.

[0052] A device may be provided to prevent flash evaporation of the pure water in the heat pump HP. For example, the evaporator 3 may be provided at a position higher than the heat pump HP to prevent flash evaporation due to the liquid depth (liquid pressure) of the pure water. For example, a valve (back pressure valve) may be provided between the heat pump HP and the evaporator 3 to prevent flash evaporation.

[0053] In the distillation apparatus 100, the raw material liquid supplied to the first distillation column 1 is an aqueous acetone solution having an acetone concentration of 1.0 wt%, and the acetone concentration of the discharged liquid discharged from the bottom of the first distillation column 1 is set to be 0.001 wt% or less (10 ppm or less).

[0054] In such a situation, by applying the distillation apparatus 100 of the present embodiment, it is possible to perform efficient distillation to save energy, while reliably separating and recovering acetone, which is a low boiling point component, from the raw material liquid.

[0055] Furthermore, in the distillation apparatus 100, the power of the heat pump HP is added as a heat quantity to the evaporator 3 of the first distillation column 1, and the amount of cooling heat in the first condenser 11 is insufficient for the amount of heat added by the evaporator 3. This makes it possible to utilize the surplus heat in the second distillation column 2, and reduces the heat load on the second distillation column 2. As a result, it becomes possible to make the column diameter of the second distillation column 2 smaller than the column diameter of the first distillation column 1, and it is possible to reduce the equipment cost.

[0056] (Example) Next, an example of the operational result when a raw material liquid (liquid to be treated) containing acetone and water is distilled using the distillation apparatus 100 according to the present embodiment will be described as an example.

[0057] When distilling the raw material liquid using the distillation apparatus 100, an aqueous acetone solution having a temperature of 20° C. and an acetone concentration of 1.0 wt % was supplied as the raw material liquid to the first distillation column 1 at a rate of 3000 kg / hr via the supply liquid preheater 41. Here, the amount of acetone in the raw material liquid supplied to the first distillation column 1 was 30 kg per hour.

[0058] Pure water was preheated in the pure water preheater 42 and then flash evaporated in the evaporator 3. The generated steam was supplied to the bottom liquid of the first distillation column 1 by directly blowing it therein at a rate of 158 kg / hr.

[0059] As the bottom liquid (bottom water) of the first distillation column 1, water having a temperature of 25° C. and an acetone concentration of 10 ppm or less (treated liquid from which most of the acetone had been separated) was discharged to the outside of the system at a rate of 3127 kg / hr.

[0060] Here, the amount of acetone discharged to the outside of the system as the column bottom liquid is approximately 0.03 kg / hr (3127 kg / hr x 0.001 / 100 = 0.03 kg / hr).

[0061] In the second distillation column 2, a vapor having a temperature of 43° C. and an acetone concentration of 98.0 wt % is taken out as a column overhead vapor (second column overhead vapor) from the column top at a rate of 63.4 kg / hr.

[0062] In the second condenser 22, the overhead vapor of the second distillation column 2 (second overhead vapor) is cooled and condensed as a second condensate. This second condensate has a temperature of 43° C., an acetone concentration of 98.0 wt %, and is produced at a rate of 63.4 kg / hr.

[0063] Of the 63.4 kg / hr of the second condensate, 33.0 kg / hr (acetone concentration: 98.0 wt%) is refluxed to the second distillation column 2, and the recovered solvent having an acetone concentration of 98.0 wt% is recovered at a rate of 30.4 kg / hr.

[0064] Here, the amount of acetone recovered as the recovered solvent is approximately 29.8 kg (30.4 kg / hr x 0.98 = approximately 29.8 kg).

[0065] In the case of a conventional distillation apparatus using steam as a heat source, the amount of heat generated by the steam is 133.5 kW, and therefore the primary energy is 133.5 kW. On the other hand, in the case of the distillation apparatus 100 using the heat pump HP of this embodiment, the power of the heat pump HP is 27 kW, and when the primary energy conversion coefficient is 2.57, the primary energy is 69.4 kW, which is the product of the power of the heat pump HP and the primary energy conversion coefficient. Since the heat pump HP has a rated capacity of 116 kW and a rated power consumption of 27 kW, the COP of the heat pump HP is 4.3.

[0066] Therefore, by using the distillation apparatus 100 according to this embodiment, the primary energy reduction rate is 48% compared to the above-mentioned conventional steam-type distillation apparatus, making it possible to obtain a significant energy-saving effect.

[0067] In the distillation apparatus 100 according to the present embodiment, steam generated in the evaporator 3 is blown into the bottom liquid of the first distillation column 1. As described above, when the raw material liquid contains low boiling point components in a proportion less than that of water (1.0 wt% of acetone as a low boiling point component and 99.0 wt% of water as a high boiling point component), efficient stripping can be performed to separate the low boiling point components.

[0068] The amounts of the raw material liquid, bottom liquid, first and second condensates, first and second vapors, and the like, as well as the values ​​of temperature, acetone concentration, energy consumption (kW), pressure, and the like, described in the above embodiment or shown in Fig. 1 are merely examples. The present disclosure does not exclude cases where these values ​​are different from those in the above embodiment.

[0069] In the above embodiment, the case where acetone is recovered by distilling a raw material liquid containing acetone as a low boiling point component and water as a high boiling point component has been described as an example, but in the present disclosure, the type of the low boiling point component is not limited to the above embodiment. The low boiling point component may be ammonia, methanol, ethanol, propanol, butanol, isopropyl alcohol, ethyl acetate, methyl acetate, ethyl formate, methyl propionate, ethyl propionate, methyl ethyl ketone, acetaldehyde, acetonitrile, allyl alcohol, chloroform, cyclohexane, carbon tetrachloride, dichloroethane, dichloromethane, carbon disulfide, diethyl ether, tetrahydrofuran, trichloroethylene, benzene, heptane, hexane, etc.

[0070] The present disclosure is not limited to the above-described embodiments in any other respects either, and applications and modifications can be made within the scope of the disclosure.

[0071] For example, in the case of a distillation apparatus operated under conditions in which the top vapor of the distillation column is heated to a high temperature, heat can be recovered from the cooling water of a condenser used to cool the top vapor of the distillation column and used as a heating source. In this case, pure water can be used as the cooling water for the condenser, and this cooling water is evaporated by heat exchange with the top vapor of the distillation column in the condenser. The generated steam is compressed in a steam compressor, and the resulting pressurized steam is blown into the distillation column.

[0072] In the present disclosure, the distillation apparatus has been described as having a two-column configuration (having two distillation columns) with high energy saving efficiency, but the distillation apparatus of the present disclosure is not limited to such a configuration. For example, the distillation apparatus may have a one-column configuration that has a first distillation column but no second distillation column. Specifically, a distillation apparatus according to one embodiment of the present disclosure may include a distillation column for distilling a raw material liquid containing water and a component having a boiling point lower than that of water; a condenser for cooling and condensing an overhead vapor taken out from a top of the distillation column by circulating cooling water for a condenser and recovering a condensate mainly composed of a low boiling point component; a heat pump configured to recover heat from the circulating cooling water for the condenser that has been used to cool the overhead vapor in the condenser and has a raised temperature, and to use the recovered heat to raise the temperature level by electric power to heat pure water; an evaporator for directly flash evaporating the pure water heated by the heat pump to generate steam to be supplied to be blown into the bottom liquid of the distillation column; a reflux path for refluxing a portion of the condenser condenser to the distillation column as a reflux liquid for the distillation column; and a pressure control mechanism for controlling the pressure in the system so that the temperature of the bottom liquid of the distillation column is maintained at a predetermined temperature.

[0073] Any of the various embodiments described above can be appropriately combined to achieve the effects of each embodiment. [Industrial Applicability]

[0074] The distillation apparatus of the present disclosure can effectively utilize the heat of the cooling water used to cool the overhead vapor by pumping it up with a heat pump as a heat source for performing the distillation operation, and can stably and continuously perform highly energy-efficient operation. Therefore, the distillation apparatus of the present disclosure is useful for application to a distillation apparatus used for distilling a raw material liquid containing water and a low-boiling point component having a boiling point lower than that of water to separate the low-boiling point component. [Explanation of symbols]

[0075] 1. First distillation tower 2. Second distillation tower 3 Evaporation tank 11 First capacitor 22 Second Capacitor 31 A first reflux line for refluxing the condensate of the first condenser to the first distillation column 32 A second reflux line for refluxing the condensate of the second condenser to the second distillation column 34 Vacuum suction means (vacuum pump) 40 Pressure Control Mechanism 41 Feed liquid preheater 42 Pure water preheater 51 Pure water pump 52 Bottoms Pump 53 Cooling water pump 54 No. 2 Condensate Pump 100 Distillation Apparatus HP Heat Pump

Claims

1. a distillation column for distilling a raw material liquid containing water and a low-boiling point component having a boiling point lower than that of water; a condenser for cooling and condensing the overhead vapor taken out from the top of the distillation column using circulating cooling water for a condenser, and recovering a condensate mainly composed of the low boiling point component; a heat pump configured to recover heat from the condenser circulating cooling water, the temperature of which has been increased by being used to cool the top vapor in the condenser, and to use the recovered heat to raise the temperature level of pure water by electric power; an evaporator that directly flash evaporates the pure water heated by the heat pump to generate steam that is supplied to be blown into the bottom liquid of the distillation column; a reflux path for refluxing a portion of the condensate in the condenser to the distillation column as a reflux liquid for the distillation column; The pressure in the system is controlled so that the temperature of the bottom liquid of the distillation column is maintained at a predetermined temperature. Pressure control mechanism A distillation apparatus comprising:

2. 2. The distillation apparatus according to claim 1, wherein the pressure control mechanism comprises a vacuum suction means for performing vacuum suction so that a predetermined degree of vacuum is achieved within the system.

3. 2. The distillation apparatus according to claim 1, wherein the pressure control mechanism controls the pressure in the system so that the temperature of the bottom liquid of the distillation column is 98° C. or lower.

4. a first distillation column for distilling a raw material liquid containing water and a low-boiling point component having a boiling point lower than that of water; a first condenser for cooling a first overhead vapor taken out from a top of the first distillation column with circulating cooling water for a first condenser to separate the first overhead vapor into a first condensate and a first vapor containing a higher proportion of the low boiling point component than the first condensate; a heat pump configured to recover heat from the first condenser circulating cooling water, the temperature of which has been increased by being used to cool the first column overhead vapor in the first condenser, and to use the recovered heat to raise the temperature level of pure water by electric power; an evaporator that directly flash evaporates the pure water heated by the heat pump to generate steam that is supplied to be blown into the bottom liquid of the first distillation column; a second distillation column for distilling the first vapor, which is the vapor after partial condensation in the first condenser, by vapor-liquid contact with a second condensate; a second condenser for cooling and condensing a second overhead vapor taken out from the top of the second distillation column by circulating cooling water for a second condenser, and recovering the second condensate mainly composed of a low boiling point component; a first reflux line for refluxing the first condensate in the first condenser to the first distillation column as a reflux liquid for the first distillation column; a second reflux line for refluxing a portion of the second condensate in the second condenser to the second distillation column as a reflux liquid for the second distillation column; a pressure control mechanism for controlling the pressure in the system so that the temperature of the bottom liquid of the first distillation column is maintained at a predetermined temperature; A distillation apparatus comprising:

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