Distillation apparatus

Abstract

To provide a distillation apparatus suitable for a bioethanol distillation process, which can improve energy saving effects and reduce CO2 emissions. [Solution] The system comprises a first distillation system for distilling a raw material liquid containing ethanol, water, low-boiling components having a boiling point lower than that of ethanol, and high-boiling components having a boiling point higher than that of ethanol, and a second distillation system for distilling a liquid taken as a side cut from the first distillation system. Both the first distillation system and the second distillation system have heat pumps that recover the thermal energy of the cooling water used to cool the overhead vapor and heat the bottom liquid. The middle distillate in the first distillation system is a condensate containing ethanol as the main component, and the overhead distillate is a liquid containing low-boiling components. The middle distillate in the second distillation system is a liquid containing high-boiling components, and the overhead distillate is a condensate containing ethanol as the main component.

Description

[Technical Field]

[0001] The present disclosure relates to a distillation apparatus using a heat pump, and more particularly to a distillation apparatus that distills a raw material liquid containing ethanol, water, a low-boiling component having a boiling point lower than that of ethanol, and a high-boiling component having a boiling point higher than that of ethanol, separates the low-boiling component and the high-boiling component from the raw material liquid, and recovers a distillate containing ethanol as a main component. [Background technology]

[0002] Amid the trend toward decarbonization both domestically and internationally, momentum is building in the aviation industry to introduce SAF. SAF stands for "Sustainable Aviation Fuel," a carbon-neutral, sustainable aviation fuel made from biomass and waste materials. The International Civil Aviation Organization (ICAO) and the International Air Transport Association (IATA) aim to halve carbon dioxide emissions by 2050 compared to 2005 levels. It is expected that the introduction of SAF by airlines around the world will lead to a significant reduction in CO2 emissions.

[0003] Current global production of SAF accounts for less than 0.03% of demand, and in order to achieve the 2050 environmental targets, it is necessary for related industries to cooperate across the board to advance the development of SAF manufacturing technology, production, and use, and to shift to 10% of fuel use by 2030. The Ministry of Land, Infrastructure, Transport and Tourism is also promoting the introduction and spread of SAF, and has set a target of "replacing 10% of fuel use by Japanese airlines with SAF" by 2030.

[0004] One method for producing SAF using bioethanol as a raw material is the saccharification and fermentation method, which produces alcohol via the ATJ (Alcohol to Jet) method. The ATJ method is also suitable for large-scale production and is expected to become a leading technology for SAF production.

[0005] However, the alcohol concentration of bioethanol immediately after fermentation is low, and a distillation process is required to concentrate it to a high concentration. Conventionally, boiler steam is used for this distillation process. However, the large amount of CO2 emitted by the boiler in the SAF production process, which aims to reduce CO2 emissions, has been an issue.

[0006] As such, the need for energy conservation in distillation apparatuses is ever-increasing, and various proposals have been made. One such energy-saving technology is a distillation apparatus that incorporates a heat pump 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 contained in the cooling water used to cool the overhead vapor in an overhead condenser that cools the overhead vapor of the distillation column. 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 column, thereby achieving energy conservation. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6612936 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the distillation apparatus of Patent Document 1 is not optimized for the distillation of bioethanol, and there is a need for a distillation process for producing SAF from bioethanol that can achieve energy savings and CO2 emissions reduction.

[0009] Specifically, ethanol produced from biomass contains trace amounts of by-products such as methanol, and multiple distillation processes are required to prevent these by-products from being included in the purified, high-concentration ethanol. Therefore, a large amount of energy is required to refine highly pure ethanol, and facilities that use more energy than the heat generated by the combustion of ethanol to produce ethanol for use as energy are not appropriate.

[0010] The present disclosure aims to provide a distillation apparatus suitable for a bioethanol distillation process that can improve energy saving effects and reduce CO2 emissions. [Means for solving the problem]

[0011] In order to achieve the above object, the distillation apparatus of the present disclosure is configured as follows.

[0012] The distillation apparatus of the present disclosure includes a first distillation column, a second distillation column, a second condenser, a second heat pump, a third distillation column, a third condenser, a second reboiler, a second reflux line, a third reflux line, a first condenser, a first heat pump, a fourth distillation column, a fourth condenser, a first reboiler, a first reflux line, a fourth reflux line, and a pressure control mechanism. The first distillation column distills a raw material liquid containing ethanol, water, a low-boiling component having a boiling point lower than that of ethanol, and a high-boiling component having a boiling point higher than that of ethanol. The second distillation column distills a liquid taken as a side cut from the first distillation column. The second condenser cools and condenses the second overhead vapor extracted from the top of the second distillation column using circulating cooling water for the second condenser, separating it into a second condensate and a second vapor. The second heat pump recovers heat from the circulating cooling water for the second condenser, which has been used to cool the second overhead vapor in the second condenser and has been heated, and uses the recovered heat to raise the temperature level and heat hot water. The third distillation column distills the second vapor in the second condenser by bringing it into vapor-liquid contact with the third condensate. The third condenser cools and condenses the third overhead vapor extracted from the top of the third distillation column using circulating cooling water for the third condenser, recovering a third condensate mainly composed of ethanol. The second reboiler reheats the bottom liquid of the second distillation column using hot water heated by the second heat pump. The second reflux line refluxes a portion of the second condensate in the second condenser to the second distillation column. The third reflux line refluxes a portion of the third condensate in the third condenser to the third distillation column. The first condenser cools the first overhead vapor extracted from the top of the first distillation column using circulating cooling water for the first condenser, separating it into a first condensate mainly composed of ethanol and a first vapor containing a higher proportion of low-boiling-point components than the first condensate, and recovering the first condensate. The first 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 heat hot water by raising the temperature level. The fourth distillation column distills the first vapor in the first condenser by bringing it into vapor-liquid contact with the fourth condensate. The fourth condenser cools and condenses the fourth overhead vapor extracted from the top of the fourth distillation column using circulating cooling water for the fourth condenser, and discharges a trace amount of fourth condensate containing ethanol and low-boiling-point components. The first reboiler reheats the bottom liquid of the first distillation column using hot water heated by the first heat pump. The first reflux line refluxes a portion of the first condensate in the first condenser to the first distillation column, and the fourth reflux line refluxes a portion of the fourth condensate in the fourth condenser to the fourth distillation column. The pressure control mechanism controls the pressure within the system so that the temperatures of the bottom liquids in the first distillation column and the second distillation column are maintained at predetermined temperatures. [Effects of the Invention]

[0013] The distillation apparatus of the present disclosure can provide a distillation apparatus suitable for a bioethanol distillation process that can improve energy saving effects and reduce CO2 emissions. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a flow chart showing the configuration of a distillation apparatus according to one embodiment of the present disclosure. [Figure 2] A table showing the material balance at each point when distilling the raw material liquid in the distillation apparatus of Figure 1. DETAILED DESCRIPTION OF THE INVENTION

[0015] (Aspects of the Distillation Apparatus of the Present Disclosure) Before describing the embodiments of the present disclosure, an aspect of the distillation apparatus of the present disclosure will be described.

[0016] A distillation apparatus according to a first aspect of the present disclosure includes a first distillation column, a second distillation column, a second condenser, a second heat pump, a third distillation column, the third condenser, a second reboiler, a second reflux line, a third reflux line, a first condenser, a first heat pump, a fourth distillation column, the fourth condenser, the first reboiler, the first reflux line, a fourth reflux line, and a pressure control mechanism. The first distillation column distills a raw material liquid containing ethanol, water, a low-boiling component having a boiling point lower than that of ethanol, and a high-boiling component having a boiling point higher than that of ethanol. The second distillation column distills a liquid taken as a side cut from the first distillation column. The second condenser cools and condenses the second overhead vapor extracted from the top of the second distillation column using circulating cooling water for the second condenser, separating it into a second condensate and a second vapor. The second heat pump recovers heat from the circulating cooling water for the second condenser, which has been used to cool the second overhead vapor in the second condenser and has been heated, and uses the recovered heat to raise the temperature level and heat hot water. The third distillation column distills the second vapor in the second condenser by bringing it into vapor-liquid contact with the third condensate. The third condenser cools and condenses the third overhead vapor extracted from the top of the third distillation column using circulating cooling water for the third condenser, recovering a third condensate mainly composed of ethanol. The second reboiler reheats the bottom liquid of the second distillation column using hot water heated by the second heat pump. The second reflux line refluxes a portion of the second condensate in the second condenser to the second distillation column. The third reflux line refluxes a portion of the third condensate in the third condenser to the third distillation column. The first condenser cools the first overhead vapor extracted from the top of the first distillation column using circulating cooling water for the first condenser, separating it into a first condensate mainly composed of ethanol and a first vapor containing a higher proportion of low-boiling-point components than the first condensate, and recovering the first condensate. The first 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 heat hot water by raising the temperature level. The fourth distillation column distills the first vapor in the first condenser by bringing it into vapor-liquid contact with the fourth condensate. The fourth condenser cools and condenses the fourth overhead vapor extracted from the top of the fourth distillation column using circulating cooling water for the fourth condenser, and discharges a trace amount of fourth condensate containing ethanol and low-boiling-point components. The first reboiler reheats the bottom liquid of the first distillation column using hot water heated by the first heat pump. The first reflux line refluxes a portion of the first condensate in the first condenser to the first distillation column, and the fourth reflux line refluxes a portion of the fourth condensate in the fourth condenser to the fourth distillation column. The pressure control mechanism controls the pressure within the system so that the temperatures of the bottom liquids in the first distillation column and the second distillation column are maintained at predetermined temperatures.

[0017] A distillation apparatus according to a second aspect of the present disclosure is the distillation apparatus of the first aspect, wherein the first distillation column, the first condenser, the fourth distillation column, and the fourth condenser constitute a first distillation system for distilling the raw material liquid as a feed liquid, and the second distillation column, the second condenser, the third distillation column, and the third condenser constitute a second distillation system for distilling a liquid side-cut from the first distillation column. The middle distillate in the first distillation system is a first condensate containing ethanol as a main component, and the overhead distillate is a liquid containing low-boiling-point components. The middle distillate in the second distillation system is a liquid containing ethanol and high-boiling-point components, and the overhead distillate is a third condensate containing ethanol as a main component.

[0018] A distillation apparatus according to a third aspect of the present disclosure is the distillation apparatus of the second aspect, wherein distillation is performed in a second distillation column on a liquid taken as a side cut from the first distillation column, and the amount of the liquid taken as a side cut is set in the range of 50% to 98% of the amount of raw material liquid supplied to the first distillation column.

[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 COP of the second heat pump is set higher than the COP of the first heat pump.

[0020] (Embodiment) Hereinafter, embodiments of the present disclosure will be described in more detail, with the features of the present disclosure being explained.

[0021] In this embodiment, we will explain an example of a distillation apparatus that distills a raw material liquid (liquid to be treated: bioethanol) containing 5 wt% ethanol, water, low-boiling components with boiling points lower than those of ethanol, and high-boiling components with boiling points higher than those of ethanol, separates the low-boiling components and high-boiling components from the raw material liquid, and recovers a distillate containing ethanol as the main component.The distillation apparatus 100 according to this embodiment is a distillation apparatus that uses a heat pump to improve energy conservation.

[0022] As shown in FIG. 1, a distillation apparatus 100 according to this embodiment includes two distillation systems: a first distillation system 101 and a second distillation system 102.

[0023] The first distillation system 101 includes a first distillation column 1, a first condenser 2, a fourth distillation column 3, and a fourth condenser 4, and is a system that performs a distillation process using a raw material liquid as a feed liquid. The second distillation system 102 includes a second distillation column 21, a second condenser 22, a third distillation column 23, and a third condenser 24, and is a system that performs a distillation process on the liquid that is side-cut from the first distillation column 1 in the first distillation system 101.

[0024] The middle distillate in the first distillation system 101 is a liquid mainly composed of ethanol, and the overhead distillate is a liquid containing low boiling point components. The middle distillate in the second distillation system 102 is a liquid containing high boiling point components, and the overhead distillate is a liquid mainly composed of ethanol.

[0025] (First distillation system 101) The first distillation column 1 is a distillation column that distills a raw material liquid, for example, bioethanol (ethanol aqueous solution (water 95 wt%)) containing ethanol at a ratio of 5 wt%. In this embodiment, the first distillation column 1 uses a packed column for the concentration section and a plate column for the stripping section. The first distillation column 1 may be configured as either a packed column or a plate column, or both.

[0026] In the first distillation column 1, ethanol distillation is carried out by gas-liquid contact between a vapor containing components of the raw material liquid and a reflux liquid, which is a condensate condensed in the first condenser 2. The column bottom liquid (bottom liquid: containing a large amount of high-boiling-point components) from which ethanol and low-boiling-point components have been separated (removed) is discharged from the first distillation column 1 to the outside of the system by a first bottom liquid pump 11. Meanwhile, the first column overhead vapor, which contains ethanol and low-boiling-point components in a higher proportion than the raw material liquid, is supplied to the first condenser 2.

[0027] A side cut is performed in the first distillation column 1, and the side cut liquid is sent to the second distillation column 21 of the second distillation system 102 by the side cut pump 30.

[0028] The first condenser 2 is connected to the top of the first distillation column 1 through a pipe. The first condenser 2 cools the first overhead vapor withdrawn from the top of the first distillation column 1 using first condenser circulating cooling water to separate the first overhead vapor into a first condensate containing ethanol as a main component and a first vapor containing a higher proportion of lower boiling point components than the first condensate. The first condenser 2 is provided with a first pump 12 that sends out the separated first condensate to be recovered as a product. The first pump 12 sends out the first condensate as a product and also returns a portion of the first condensate to the first distillation column 1 as a reflux liquid via a first reflux line 15.

[0029] The fourth distillation column 3 is connected to the first condenser 2, and performs distillation by bringing the first vapor separated in the first condenser 2 into gas-liquid contact with a fourth condensate (the condensate of the fourth condenser 4). The condensed liquid is returned to the first condenser 2, and a fourth overhead vapor is extracted from the top of the fourth distillation column 3. Note that the first condenser 2 and the fourth distillation column 3 may be separated from each other as long as the first vapor, which is the vapor after partial condensation in the first condenser 2, is supplied to the bottom of the fourth distillation column 3.

[0030] The fourth condenser 4 is connected to the top of the fourth distillation column 3 through a pipe. The fourth condenser 4 cools and condenses the fourth overhead vapor withdrawn from the top of the fourth distillation column 3 using circulating cooling water for the fourth condenser, and discharges a fourth condensate containing ethanol and low-boiling-point components. A second pump 13 is provided to discharge the discharged fourth condensate as a waste liquid. The second pump 13 discharges the fourth condensate as a waste liquid and also refluxes a portion of the fourth condensate to the fourth distillation column 3 as a reflux liquid through a fourth reflux line 16.

[0031] The first distillation system 101 further includes a first heat pump HP1 and a first reboiler 5.

[0032] The first heat pump HP1 recovers heat from the circulating cooling water for the first condenser, which has been used to cool the first tower overhead vapor in the first condenser 2 and has been heated, and uses the recovered heat to raise the temperature level and heat hot water using electricity.

[0033] The circulating cooling water for the first condenser is circulated between the first condenser 2 and the first heat pump HP1 by a pump (not shown). The first heat pump HP1 recovers heat from the circulating cooling water for the first condenser used in the first condenser 2, and uses electric power to increase the temperature level of the recovered heat to heat hot water, thereby circulating and utilizing thermal energy.

[0034] Specifically, the circulating cooling water for the first condenser at 9.6°C is supplied to the first condenser 2 and used to cool the first tower overhead vapor, raising its temperature to 14.6°C. The circulating cooling water for the first condenser at 14.6°C undergoes heat recovery in the first heat pump HP1, and the circulating cooling water for the first condenser, whose temperature has been reduced to 9.6°C, is circulated and supplied to the first condenser 2.

[0035] Meanwhile, in the first heat pump HP1, the hot water whose temperature has been raised to 57.4°C by the heat and electricity recovered from the circulating cooling water for the first condenser is supplied to the first reboiler 5. The hot water whose temperature has been reduced to 52.4°C in the first reboiler 5 is returned to the first heat pump HP1, where it is raised to 57.4°C and then supplied to the first reboiler 5 again.

[0036] The first reboiler 5 is connected to the bottom of the first distillation column 1, and a portion of the bottom liquid (bottom liquid) is supplied to the first reboiler 5 by the first bottoms pump 11. The bottoms liquid is heated in the first reboiler 5 using hot water, and the heated bottoms liquid is supplied to the first distillation column 1.

[0037] (Second distillation system 102) The second distillation column 21 is a distillation column that distills the liquid that is side-cut from the first distillation column 1. This side-cut liquid contains ethanol at a lower ratio than the raw material liquid. In this embodiment, a plate column is used as the second distillation column 21. Note that the second distillation column 21 may be a column with various configurations other than a plate column, such as a packed column.

[0038] In the second distillation column 21, ethanol distillation is carried out by gas-liquid contact between a vapor containing components of the side-cut liquid and a reflux liquid, which is a condensate condensed in the second condenser 22. The bottom liquid from which ethanol and some of the high-boiling components have been separated (removed) is discharged from the second distillation column 21 to the outside of the system by the second bottoms pump 31. Meanwhile, the second overhead vapor, which contains ethanol and high-boiling components in a higher proportion than the side-cut liquid, is supplied to the second condenser 22.

[0039] The second condenser 22 is connected to the top of the second distillation column 21 via a pipe. The second condenser 22 cools the second overhead vapor withdrawn from the top of the second distillation column 21 with second condenser circulating cooling water to separate the second overhead vapor into a second condensate containing high-boiling point components and the second vapor. A third pump 32 is provided to send out the separated second condensate to be discharged as effluent. The third pump 32 sends out the second condensate as effluent and refluxes a portion of the second condensate to the second distillation column 21 as reflux via a second reflux line 35.

[0040] The third distillation column 23 is connected to the second condenser 22, and distills the second vapor separated in the second condenser 22 by bringing the second vapor into gas-liquid contact with a third condensate (the condensate of the third condenser 24). The condensed liquid is returned to the second condenser 22, and a third overhead vapor is extracted from the top of the third distillation column 23. Note that the second vapor, which is the vapor after partial condensation in the second condenser 22, may be supplied to the bottom of the third distillation column 23, and the second condenser 22 and the third distillation column 23 may be separated from each other.

[0041] The third condenser 24 is connected to the top of the third distillation column 23 via a pipe. The third condenser 24 cools and condenses the third overhead vapor withdrawn from the top of the third distillation column 23 using circulating cooling water for the third condenser, and recovers a third condensate containing ethanol as a main component. A fourth pump 33 is provided to discharge the recovered third condensate as a product. The fourth pump 33 not only discharges the third condensate as a product, but also refluxes a portion of the third condensate to the third distillation column 23 via a third reflux line 36 as a reflux liquid.

[0042] The second distillation system 102 further includes a second heat pump HP2 and a second reboiler 25.

[0043] The second heat pump HP2 recovers heat from the circulating cooling water for the second condenser, which has been used to cool the second tower overhead vapor in the second condenser 22 and has been heated, and uses the recovered heat to raise the temperature level and heat hot water using electricity.

[0044] The circulating cooling water for the second condenser is circulated between the second condenser 22 and the second heat pump HP2 by a pump (not shown). The second heat pump HP2, for example, recovers heat from the circulating cooling water for the second condenser used in the second condenser 22, and uses electric power to increase the temperature level of the recovered heat to heat hot water, thereby circulating and utilizing thermal energy.

[0045] Specifically, the circulating cooling water for the second condenser at 21.8°C is supplied to the second condenser 22 and used to cool the second tower overhead vapor, raising its temperature to 26.8°C. The circulating cooling water for the second condenser at 26.8°C undergoes heat recovery in the second heat pump HP2, and the circulating cooling water for the second condenser, whose temperature has been lowered to 21.8°C, is circulated and supplied to the second condenser 22.

[0046] Meanwhile, in the second heat pump HP2, the hot water whose temperature has been raised to 57.1°C by the heat and electricity recovered from the circulating cooling water for the second condenser is supplied to the second reboiler 25. The hot water whose temperature has been reduced to 52.1°C in the second reboiler 25 is returned to the second heat pump HP2, where it is raised to 57.1°C and then supplied to the second reboiler 25 again.

[0047] The second reboiler 25 is connected to the bottom of the second distillation column 21, and a portion of the bottom liquid (bottom liquid) is supplied to the second reboiler 25 by the second bottoms pump 31. The bottom liquid is heated using hot water in the second reboiler 25, and the heated bottom liquid is supplied to the second distillation column 21.

[0048] The distillation apparatus 100 is provided with a chiller unit 19 that circulates and supplies circulating cooling water for the fourth condenser and the third condenser. The chiller unit 19 supplies, for example, 12°C cooling water as 5°C cooling water.

[0049] The distillation apparatus 100 is equipped with a pressure control mechanism that controls the pressure within the first distillation system 101 and the second distillation system 102 so that the temperature of the bottom liquid of the first distillation column 1 and the second distillation column 21 is maintained at a predetermined temperature.

[0050] The pressure control mechanism includes a vacuum pump 17 that performs vacuum suction within the system via the fourth condenser 4, and a vacuum pump 37 that performs vacuum suction within the system via the third condenser 24, so that the system reaches a predetermined vacuum level. The pressure control mechanism also includes a pressure sensor that detects the pressure within the system, and a control system that controls the vacuum suction of the vacuum pumps 17 and 37 based on pressure information from the pressure sensor.

[0051] In the distillation apparatus 100, the pressure in the system is controlled by a pressure control mechanism to maintain the temperatures of the bottom liquids of the first distillation column 1 and the second distillation column 21 at a predetermined temperature. Such a predetermined temperature is, for example, maintained at 50°C or below, and in this embodiment, is maintained at about 49°C.

[0052] By applying the distillation apparatus 100 of this embodiment, it is possible to perform efficient distillation using the first distillation system 101 and the second distillation system 102 to recover heat and thereby save energy, while separating low-boiling components having a boiling point lower than that of ethanol and high-boiling components having a boiling point higher than that of ethanol from the raw material liquid, thereby reliably separating and recovering ethanol as a highly concentrated aqueous ethanol solution.

[0053] The features of the distillation apparatus 100 of this embodiment will be described below.

[0054] The first distillation column 1, to which the feed liquid (raw material liquid) is sent, withdraws liquid from the recovery section of the first distillation column 1 (performing a side cut) to prevent the accumulation of high-boiling components and to prevent a decrease in the purity of the high-concentration ethanol extracted from the first condenser 2. While side cuts are commonly performed to stabilize the composition of the distillate and bottoms during distillation operations, discarding the extracted liquid results in a decrease in the yield of the distillate and bottoms. Therefore, a typical side cut is typically targeted at the stage with the highest concentration of by-products accumulated in the distillation column, and the amount discarded is typically small. In the distillation apparatus 100 of this embodiment, the liquid extracted by the side cut from the first distillation column 1 in the first distillation system 101 is distilled in the second distillation system 102. Therefore, even if a large amount of liquid is withdrawn, the yield does not decrease or even improves.

[0055] The distillation apparatus 100, which uses bioethanol as the raw material liquid, is provided with four outlets for extracting water and by-product liquid, and the main extracted substances are as follows. Bottoms of first distillation column 1: water, acetic acid (contains traces of ethanol) Bottoms of second distillation column 21: water, acetic acid (containing a trace amount of ethanol) Distillate of second condenser 22: water, acetic acid, isobutanol (including low concentrations of ethanol and traces of methanol) Distillate from 4th condenser 4: methanol, acetaldehyde, (including high concentration ethanol)

[0056] In addition, trace amounts of by-products with boiling points close to these are also entrained. In other words, by-products other than ethanol are extracted from these four outlets, which increases the ethanol yield.

[0057] The middle distillate in the first distillation system 101 of the distillation apparatus 100 is a first condensate mainly composed of ethanol, and the overhead distillate is a liquid containing low boiling point components. The middle distillate in the second distillation system 102 is a liquid containing high boiling point components, and the overhead distillate is a third condensate mainly composed of ethanol.

[0058] In the first distillation system 101, the distillate is high-concentration ethanol and the bottoms are water, so the difference in boiling points and pressure loss between them results in a large temperature difference between the top and bottom.On the other hand, in the second distillation system 102, the distillate is mainly low-concentration ethanol and by-products, and the bottoms are acetic acid and water, so the boiling point difference is small and there are fewer stages, so the pressure loss and temperature difference are also small.

[0059] Here, the characteristics of a heat pump will be explained. The heat pump recovers heat from the cooling water in the condenser and supplies hot water to the reboiler as a heat source. The smaller the temperature difference between the cooling water and the hot water, the higher the COP. That is, the COP of the second heat pump HP2 in the second distillation system 102 is higher than the COP of the first heat pump HP1 in the first distillation system 101. Since the COP is the amount of power per unit of heat, the higher the COP, the greater the energy savings. That is, in the distillation apparatus 100 of this embodiment, the first heat pump HP1 and the second heat pump HP2 are arranged to maximize energy savings.

[0060] Furthermore, in order to reduce the load on the first heat pump HP1, which has a lower COP than the second heat pump HP2, as much as possible, the amount of side cut from the first distillation column 1 is set to be as large as possible. By setting it in this manner, the energy saving performance of the distillation apparatus 100 as a whole can be improved. For example, it is preferable to supply a liquid amount to the second distillation column 21 as a side cut of 50% or more of the amount of raw material liquid supplied to the first distillation column 1. The amount of liquid cut from the side cut may be set in the range of 50% to 98% of the amount of raw material liquid supplied to the first distillation column 1.

[0061] The fourth distillation column 3 uses the surplus heat of the first distillation column 1 as a heating source. Heat recovered from the cooling water of the first condenser 2 is used as a heating source for the first reboiler 5 by the first heat pump HP1. The power of the first heat pump HP1 is converted into heating energy and supplied to the first reboiler 5, resulting in overheating, causing the first condenser 2 to enter partial condensation operation, and the surplus heat causes vapor to be supplied to the fourth distillation column 3.

[0062] Although the distillation apparatus 100 of this embodiment employs a configuration using a reboiler as described above, other configurations may also be employed. For example, the distillation apparatus may be configured to include an evaporator in which soft water is supplied to a heat pump, the soft water heated by the heat pump is directly flashed, and the flashed vapor is blown into the bottom liquid of the distillation column.

[0063] In the second distillation system 102, the same principle as in the first distillation system 101 is applied, and the electric power of the second heat pump HP2 becomes surplus heat, and this surplus heat is used to supply vapor to the third distillation column 24.

[0064] Heat pumps can simultaneously perform cooling and heating, but by selecting a heat pump that can operate at the required temperature and changing the operating vacuum, distillation can be performed over a wide temperature range. For example, if the feed liquid (raw material liquid) contains an enzyme and is added for recovery purposes, distillation at a lower temperature is desirable. On the other hand, to reduce the column diameter and reduce equipment costs, it is desirable to reduce the vacuum and distillation at near atmospheric pressure.

[0065] (Example) Next, an example of the operational results when distillation was carried out using bioethanol as a raw material liquid using the distillation apparatus 100 according to the present embodiment will be shown as an example.

[0066] In this embodiment, the bottoms of the first distillation column 1 and the second distillation column 21 are returned to the reaction process in the upstream stage of the distillation apparatus 100, so the system is designed so that the liquid temperature at the bottom of the first distillation column 1 and the second distillation column 21 is 50°C or less.

[0067] The specifications of the raw material liquid supplied to the distillation apparatus 100 are as follows: Supply liquid amount: 5,000 kg / hr Feed liquid temperature 35℃ Supply ethanol concentration 5wt% Feed by-product concentration Methanol 10 ppm Acetaldehyde 20 ppm Isobutanol 100 ppm Acetic acid 1000 ppm

[0068] The specifications of the product liquid extracted as a product from the distillation apparatus 100 are as follows: Concentrated ethanol concentration: 92.6 wt% (below the azeotropic point with water) Ethanol recovery rate: 98.15%

[0069] The specifications of the distillation apparatus 100 are as follows: Heat pump specifications First heat pump HP1 Heating capacity 363.9kW Electricity 92.6kW COP3.93 Second heat pump HP2 Heating capacity 549.5kW Electricity 99.9kW COP5.5 Total heating amount: 913.4kW Electricity amount: 192.5kW Chiller unit 19 Cooling capacity 157.3kW Power consumption 28.5kW COP5.52 Pumps: Total power consumption: 44.0kW

[0070] Here, the material balance at each point when distillation of the raw material liquid is performed in the distillation apparatus 100 according to this embodiment is shown in the table of Figure 2. Points 1 to 15 in the table of Figure 2 are shown on the lines of the flow sheet in Figure 1 (numbers surrounded by square marks).

[0071] The calorific value of 92.6 wt% ethanol obtained by distillation using the distillation apparatus 100 is approximately 2.00 kW, while the total energy required for the distillation is 265 kW. Even when compared in terms of primary energy, it can be seen that the energy required for distillation is significantly lower than the calorific value of the ethanol obtained by distillation. Therefore, it can be seen that the distillation apparatus 100 is a distillation apparatus with excellent energy saving properties. Ethanol amount equivalent to 100% of the feed liquid: 250 kg / hr Product recovery rate: 98.15% Ethanol combustion heat: 8.256 kWh / kg (※250×0.9815×8.256=2,025.8kW)

[0072] Therefore, the distillation apparatus 100 of this embodiment can provide a distillation apparatus suitable for a bioethanol distillation process that can improve energy saving effects and reduce CO2 emissions.

[0073] Note that the values ​​of various quantities, temperatures, concentrations, energy consumption (kW), pressures, etc., relating to the feed liquid, bottom liquid, condensate, vapor, etc., explained in the above-mentioned embodiment or shown in Figures 1 and 2 are merely examples. The present disclosure does not exclude cases where these values ​​are different from those in the above-mentioned embodiment.

[0074] Furthermore, the low-boiling point components having a boiling point lower than that of ethanol contained in the raw material liquid and the high-boiling point components having a boiling point higher than that of ethanol are shown as examples in the above-described embodiment, and the raw material liquid may contain other components.

[0075] Furthermore, the present disclosure is not limited to the above-described embodiments in other respects either, and applications and modifications can be made within the scope of the disclosure. [Industrial Applicability]

[0076] The distillation apparatus of the present disclosure relates to a distillation apparatus using a heat pump, and more specifically, is useful for distilling a raw material liquid containing ethanol, water, a low-boiling component having a boiling point lower than that of ethanol, and a high-boiling component having a boiling point higher than that of ethanol, separating the low-boiling component and the high-boiling component from the raw material liquid, and recovering a distillate containing ethanol as a main component. [Explanation of symbols]

[0077] 1. First distillation tower 2. First capacitor 3. Fourth distillation tower 4 Fourth Capacitor 5. No. 1 reboiler 11 No. 1 bottoms pump 12 First Pump 13 Second pump 15 First return channel 16 Fourth Circulation Channel 17 Vacuum Pump 19 Chiller unit 21 Second distillation tower 22 Second capacitor 23 Third Distillation Tower 24 Third capacitor 25 Second reboiler 30 Side cut pump 31 Second bottoms pump 32 Third Pump 33 4th Pump 35 Second return channel 36 Third return channel 37 Vacuum Pump 100 Distillation apparatus 101 First distillation line 102 Second distillation line HP1 Primary Heat Pump HP2 Secondary Heat Pump

Claims

1. a first distillation column for distilling a raw material liquid containing ethanol, water, a low-boiling component having a boiling point lower than that of ethanol, and a high-boiling component having a boiling point higher than that of ethanol; a second distillation column for distilling a liquid taken as a side cut from the first distillation column; a second condenser that cools and condenses a second overhead vapor taken out from the top of the second distillation column using circulating cooling water for a second condenser, and separates the second overhead vapor into a second condensate and a second vapor; a second heat pump that recovers heat from the second condenser circulating cooling water, the temperature of which has been increased by being used to cool the second column overhead vapor in the second condenser, and uses the recovered heat to raise the temperature level of hot water by electric power; a third distillation column for distilling the second vapor in the second condenser by vapor-liquid contact with a third condensate; a third condenser that cools and condenses a third overhead vapor taken out from the top of the third distillation column using circulating cooling water for a third condenser, and recovers the third condensate containing ethanol as a main component; a second reboiler that reheats the bottom liquid of the second distillation column with the hot water heated by the second heat pump; a second reflux line for refluxing a portion of the second condensate in the second condenser to the second distillation column; a third reflux line for refluxing a portion of the third condensate in the third condenser to the third distillation column; a first condenser that cools a first overhead vapor taken out from the top of the first distillation column with circulating cooling water for a first condenser to separate the first overhead vapor into a first condensate containing ethanol as a main component and a first vapor containing the low-boiling point component at a higher ratio than the first condensate, and recovers the first condensate; a first heat pump that recovers heat from the first condenser circulating cooling water that has been used to cool the first column overhead vapor in the first condenser and has been heated, and that uses electric power to raise the temperature level of the recovered heat and heat hot water; a fourth distillation column for distilling the first vapor in the first condenser by vapor-liquid contact with a fourth condensate; a fourth condenser that cools and condenses a fourth overhead vapor taken out from the top of the fourth distillation column using circulating cooling water for a fourth condenser, and discharges the fourth condensate containing ethanol and the low-boiling point components; a first reboiler that reheats the bottom liquid of the first distillation column with the hot water heated by the first heat pump; a first reflux line for refluxing a portion of the first condensate in the first condenser to the first distillation column; a fourth reflux line for refluxing a portion of the fourth condensate in the fourth condenser to the fourth distillation column; a pressure control mechanism that controls the pressure in the system so that the temperatures of the bottom liquids of the first distillation column and the second distillation column are maintained at predetermined temperatures; A distillation apparatus comprising:

2. the first distillation column, the first condenser, the fourth distillation column, and the fourth condenser constitute a first distillation system for distilling the raw material liquid as a feed liquid, the second distillation column, the second condenser, the third distillation column, and the third condenser constitute a second distillation system for distilling a liquid side-cut from the first distillation column; the middle distillate in the first distillation system is the first condensate containing ethanol as a main component, and the overhead distillate is a liquid containing the low boiling point component, 2. The distillation apparatus according to claim 1, wherein the middle distillate in the second distillation system is a liquid containing the high-boiling point component, and the overhead distillate is the third condensate containing ethanol as a main component.

3. 3. The distillation apparatus according to claim 2, wherein the second distillation column is distilled on a liquid taken as a side cut from the first distillation column, and the amount of the liquid taken as a side cut is set in the range of 50% to 98% of the amount of the raw material liquid supplied to the first distillation column.

4. The distillation apparatus according to claim 1 , wherein the COP of the second heat pump is higher than the COP of the first heat pump.

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