Energy-efficient apparatus and method for distillation using process stream as continuous coolant

Abstract

The present invention relates to an apparatus and a method for distillation using a low-temperature raw material and a product as a coolant, and more specifically to an apparatus for distillation, in which heat exchangers are introduced so as to partially substitute for the role of a condenser, i.e., a process of liquefying gas discharged from the upper portion of a distillation column, through heat exchange between the high-temperature gas discharged from the upper portion of the distillation column and a low-temperature raw material and a product, thereby reducing the heat load of the condenser. In addition, the present invention relates to an apparatus for distillation, which also reduces the heat load of a reboiler by supplying heat to the distillation column by heating the raw material. The apparatus for distillation, according to the present invention, may effectively separate a raw material mixture, or a reaction mixture generated in a reaction unit, and particularly, it has been confirmed that as the temperature of the gas discharged from the upper portion of the distillation column increases, energy consumption and costs are greatly reduced.

Description

Energy-efficient distillation apparatus and method using continuous coolant in the process

[0001] The present invention relates to an energy-efficient distillation apparatus and method using a flow within a process as a coolant, and more particularly, to a distillation apparatus and method using the distillation apparatus, which partially replaces the role of a condenser by introducing a heat exchanger to liquefy a portion of the distillation tower top effluent gas through heat exchange with a low-temperature raw material and / or a low-boiling-point liquid product, and the heated raw material partially replaces the role of a reboiler by supplying heat to the distillation tower, thereby reducing the heat loads of the condenser and the reboiler.

[0002]

[0003] In a typical distillation column, a condenser is used at the top to separate substances with low boiling points, and a reboiler is used at the bottom to separate substances with high boiling points. In the case of the condenser, cooling water is used to condense the vapor from the top of the distillation column, and the low-boiling-point substances that have condensed into a liquid are separated. In the case of the reboiler, high-temperature steam is used to vaporize the liquid that comes out of the bottom of the distillation column, so that the low-boiling-point substances are sent back up and the high-boiling-point substances are separated from the bottom. Meanwhile, the series of processes that occur in the condenser and reboiler are all reactions that exchange heat and cause phase changes. Although they are essential processes for the separation of substances, they result in significant energy losses due to poor insulation in each device and heat loss (A. Araujo et al., Energy, 32 (2007) 1185-1193).

[0004] The energy required for the condenser is equivalent to the energy required to condense the vapor from the top of the distillation column. Meanwhile, a significant amount of cooling water must be continuously supplied to maintain a continuous distillation process (K. Singh et al., Chem. Eng. Res. Des., 123 (2017) 1-13). Since the operating and capital costs of the condenser include the energy cost associated with cooling water use, excessive cooling water use increases the annual cost of condenser use (K. Jeong et al., Int. J. Heat. Mass. Transf., 53 (2010) 2361-2368). Therefore, reducing the amount of energy required for the condenser not only reduces the energy consumption of the distillation process but also makes the cooling system operation more efficient.

[0005] Currently, various methods have been proposed to reduce the heat load of the condenser in a single distillation column, such as introducing an intermediate condenser or optimizing the cooling water circulation system. While an intermediate condenser reduces energy consumption compared to a conventional distillation column condenser, it requires the use of another condenser with a less expensive coolant, requiring additional coolant (R. Agrawal et al., AIChE Journal, 44 (1998) 1303-1315). Furthermore, circulation systems that utilize cooling water for heat exchange within the process require hot and cold flows to ensure continuous heat exchange, which necessitates continuous heat and cooling flows and maintenance, requiring improvements (W. He et al., Appl. Therm. Eng., 207 (2022) 118176). Therefore, there is a need to develop a distillation process that can reduce the heat load of the condenser, reduce energy consumption, and supply coolant energy-efficiently.

[0006] Accordingly, the inventors of the present invention have made great efforts to solve the above problems, and as a result, they have confirmed that by using a raw material or a low-boiling-point liquid product, which is a low-temperature flow within the process, as a coolant, the operating cost of the condenser is saved while supplying the coolant within the process, thereby reducing energy consumption, and the raw material heated through heat exchange can supply heat to the distillation column, thereby reducing the energy consumption of the reboiler, thereby improving the single distillation process in terms of energy and economy, and have completed the present invention.

[0007]

[0008] Summary of the invention

[0009] The purpose of the present invention is to provide an enhanced distillation apparatus with improved energy and economic efficiency by using a low-temperature stream within the process as a coolant and supplying heat to the distillation column through preheating of the raw material.

[0010] In addition, another object of the present invention is to provide a method for distilling a raw material mixture using the distillation apparatus.

[0011] In order to achieve the above object, a distillation apparatus including a distillation tower (1) for separating a raw material mixture or a reaction mixture; a raw material heat exchanger (5) for liquefying a portion of the distillation tower top discharge gas through heat exchange with a low-temperature raw material mixture; a condenser (3) for liquefying the distillation tower top discharge gas that is not completely condensed in the raw material heat exchanger; a reboiler (4) for heating and evaporating the distillation tower bottom discharge liquid and refluxing a portion of the generated vapor to the distillation tower; and a decanter (2) for separating a mixture in a liquid state condensed in the condenser, the distillation apparatus is characterized in that the distillation apparatus uses the raw material mixture as a coolant.

[0012] The present invention also provides a method for fractionally distilling a raw material mixture or a reaction mixture using the above device.

[0013]

[0014] Figure 1 shows a general process diagram for separating a raw material mixture that can be separated using a decanter (2) using a distillation tower (1).

[0015] FIG. 2 is a first strengthening process drawing for FIG. 1, which includes heat exchange between the upper outlet gas of the distillation column and low-temperature raw materials by adding a raw material heat exchanger to FIG. 1, a distillation apparatus according to one embodiment of the present invention.

[0016] FIG. 3 is a second enrichment process diagram for FIG. 1, which further includes heat exchange between the upper effluent gas of the distillation column and the low-boiling-point liquid product separated through the decanter by adding a product heat exchanger to FIG. 2, according to one embodiment of the present invention.

[0017] Figure 4 shows a general process diagram for separating a reaction mixture produced through a reaction occurring in a reaction section (7) of a distillation tower (1).

[0018] FIG. 5 is a first strengthening process drawing for FIG. 4, which includes heat exchange between the upper outlet gas of the distillation column and low-temperature raw materials by adding a raw material heat exchanger to FIG. 4, a distillation apparatus according to one embodiment of the present invention.

[0019] FIG. 6 is a second enrichment process diagram for FIG. 4, which further includes heat exchange between the upper effluent gas of the distillation column and the low-boiling-point liquid product separated through the decanter by adding a product heat exchanger to FIG. 5, according to one embodiment of the present invention.

[0020]

[0021] Detailed description and specific implementation examples of the invention

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In general, the nomenclature used herein is well known and commonly used in the art.

[0023]

[0024] In the present invention, it was confirmed that when a low-temperature raw material or a low-boiling-point liquid product separated at a low temperature in a decanter is used as a coolant to cool the upper effluent gas of a distillation column, the heat load of the condenser is reduced, thereby reducing energy consumption and costs. In addition, the low-temperature raw material can be heated through heat exchange to supply heat to the distillation column, thereby further reducing the energy requirement of the reboiler. Various methods have been proposed to reduce the heat load of the condenser in a conventional single distillation column, such as introducing an intermediate condenser or optimizing the cooling water circulation system. However, it has been difficult to reduce the heat load of the condenser while reducing energy consumption and costs.

[0025]

[0026] Accordingly, the present invention provides a distillation apparatus comprising, from one aspect, a distillation tower (1) for separating a raw material mixture or a reaction mixture; a raw material heat exchanger (5) for liquefying a portion of the distillation tower top outlet gas through heat exchange with a low-temperature raw material mixture; a condenser (3) for liquefying the distillation tower top outlet gas that is not completely condensed in the raw material heat exchanger; a reboiler (4) for heating and evaporating the distillation tower bottom outlet liquid and refluxing a portion of the generated vapor to the distillation tower; and a decanter (2) for separating a mixture in a liquid state condensed in the condenser, wherein the distillation apparatus is characterized in that the distillation apparatus uses the raw material mixture as a coolant.

[0027] The present invention also proposes a distillation device that is connected to the raw material heat exchanger (5) and further condenses the upper outlet gas that is not completely condensed in the raw material heat exchanger through heat exchange with a low-temperature product, and discharges a portion of the heated product after passing through the product heat exchanger and recycles the remainder back to the decanter (2), thereby further saving energy through additional heat exchange in the above method.

[0028] In the present invention, it is preferable that the distillation tower (1) is a single distillation tower or a distillation tower including a reaction section (7).

[0029] In the present invention, it is preferable that the device separates the raw material mixture or the reaction mixture generated in the reaction unit (7). The raw material mixture refers to a liquid mixture that can be separated by a decanter, i.e., separated by a density difference, and may be, for example, two or more selected from the group consisting of water, alcohol, acetic acid, and acetate, but is not limited thereto. In addition, the reaction mixture generated in the reaction unit may be a liquid mixture that can be separated by a decanter, and more preferably, may be a liquid mixture composed of water and an organic substance heavier than water, but is not limited thereto.

[0030] In the present invention, the low-temperature raw material can also be heated through heat exchange to supply heat to the distillation column, thereby further reducing the energy requirement of the reboiler.

[0031] In the present invention, the distillation device performs heat exchange between a "high temperature" stream, which is a gas discharged from the top of the distillation tower, and a "low temperature" stream, which is a low-boiling-point liquid product separated from the raw material and / or decanter, wherein the term "low temperature" means 20 to 50°C, and the term "high temperature" means 100 to 300°C, but is not limited thereto.

[0032]

[0033] From another perspective, the present invention relates to a method for fractional distillation of a raw material mixture or a reaction mixture using the distillation apparatus.

[0034]

[0035] In the present invention, the method comprises the steps of: a) injecting the raw material mixture into a distillation column (1) to separate the raw material mixture, and then discharging high-boiling-point substances in a liquid state to the bottom of the distillation column and discharging low-boiling-point substances in a gaseous state to the top of the distillation column; b) injecting the high-temperature gas discharged to the top of the distillation column into a raw material heat exchanger (5) and liquefying a portion of the high-temperature gas through heat exchange with a low-temperature raw material; c) injecting the gas that has not been completely liquefied in the raw material heat exchanger into a condenser (3) and injecting the completely condensed liquid mixture into a decanter (2); and d) separating the injected liquid mixture in the decanter to discharge a high-boiling-point liquid product and injecting the low-boiling-point liquid product back into the distillation column as a reflux flow.

[0036] In the present invention, for additional energy saving, the method comprises the steps of: a) injecting the raw material mixture into a distillation column (1) to separate the raw material mixture, and then discharging high-boiling-point substances in a liquid state to the bottom of the distillation column and discharging low-boiling-point substances in a gaseous state to the top of the distillation column; b) injecting the high-temperature gas discharged to the top of the distillation column into a raw material heat exchanger (5) and liquefying a portion of the high-temperature gas through heat exchange with a low-temperature raw material; c) injecting the gas partially liquefied in the raw material heat exchanger into a product heat exchanger (6) and further cooling the gas through heat exchange with a low-boiling-point liquid product discharged from a decanter; d) injecting the gas that is not completely liquefied in the product heat exchanger into a condenser (3) and injecting the completely condensed liquid mixture into the decanter (2); and e) discharging a portion of the heated product from the product heat exchanger and recycling the remainder back to the decanter.

[0037]

[0038] In addition, in the present invention, the method comprises the steps of: a) injecting a raw material mixture into a distillation column (1), and then discharging high-boiling-point substances among the reaction mixture generated in the reaction section (7) to the bottom of the distillation column and discharging high-temperature gas to the top of the distillation column; b) injecting the high-temperature gas discharged to the top of the distillation column into a raw material heat exchanger (5) and liquefying a portion of the high-temperature gas through heat exchange with a low-temperature raw material; c) injecting a gas that has not been completely liquefied in the raw material heat exchanger into a condenser (3) and injecting a completely condensed liquid mixture into a decanter (2); and d) separating the injected liquid mixture in the decanter to discharge a high-boiling-point liquid product and injecting a low-boiling-point liquid product back into the distillation column as a reflux flow.

[0039] In the present invention, for additional energy saving, the method comprises the steps of: a) injecting a raw material mixture into a distillation column (1), and then discharging high-boiling-point substances among the reaction mixture generated in the reaction section (7) to the bottom of the distillation column and discharging high-temperature gas to the top of the distillation column; b) injecting the high-temperature gas discharged to the top of the distillation column into a raw material heat exchanger (5) and liquefying a portion of the high-temperature gas through heat exchange with a low-temperature raw material; c) injecting a portion of the liquefied gas in the raw material heat exchanger (5) into a product heat exchanger (6) and further cooling the gas through heat exchange with a low-boiling-point liquid product discharged from a decanter; d) injecting a gas that is not completely liquefied in the product heat exchanger into a condenser (3) and injecting a completely condensed liquid mixture into a decanter (2); and e) discharging a portion of the heated product in the product heat exchanger and recycling the remainder back to the decanter.

[0040]

[0041] The present invention is described in detail below.

[0042]

[0043] Figure 1 shows a general process for separating a liquid mixture raw material that can be separated by a decanter using a fractional distillation column (1). A substance with a high boiling point passes through a reboiler (4) and is separated into the lower part of the distillation column, and a gas mixture of two substances passes through a condenser (3) to become liquid and is then separated through a decanter (2) at the upper part. After separating a substance with a low boiling point into a liquid state, the remaining mixture is refluxed into the distillation column to increase the efficiency of separation.

[0044] Figure 2 is a strengthening process for Figure 1, which includes heat exchange between the upper outlet gas of the distillation column and low-temperature raw material using a raw material heat exchanger (5). In addition, a condenser device (3) is included to completely condense the upper outlet gas that has not been completely condensed even after the heat exchange.

[0045] Fig. 3 is a strengthening process for Fig. 2, wherein additional heat exchange occurs in the product heat exchanger (6) between the upper outlet gas of the distillation column, which is partially liquefied through the raw material heat exchanger (5), and the low-temperature product discharged through the decanter (2). This additionally cools the upper outlet gas of the distillation column, thereby reducing the energy requirement of the condenser compared to Fig. 2. In addition, as in Fig. 2, a condenser device (3) is included for completely condensing the upper outlet gas that is not completely condensed even after heat exchange.

[0046] Figure 4 is a general diagram of a process in which water and heavier organic substances are produced through a reaction occurring in a reaction distillation section (7) of a distillation column (1) and can be separated using a decanter. A gaseous mixture containing heavy organic substances is condensed through a condenser (3) at the bottom of the distillation column and water is condensed through a decanter (2) to separate water from the mixture. The remaining mixture is refluxed into the distillation column to increase the efficiency of separation.

[0047] Fig. 5 is a strengthening process for Fig. 4, which includes heat exchange between the upper outlet gas of the distillation column and low-temperature raw material using a raw material heat exchanger (5). In addition, a condenser device (3) is included to completely condense the upper outlet gas that has not been completely condensed even after the heat exchange.

[0048] Fig. 6 is a strengthening process for Fig. 5, wherein additional heat exchange occurs between the upper outlet gas of the distillation tower, which is partially liquefied through the raw material heat exchanger (5), and the low-temperature product discharged through the decanter (2) in the product heat exchanger (6). This additionally cools the upper outlet gas of the distillation tower, thereby reducing the energy requirement of the condenser compared to Fig. 5. In addition, as in Fig. 5, a condenser device (3) is included for completely condensing the upper outlet gas that is not completely condensed even after heat exchange.

[0049]

[0050] The present invention relates to an optimized process design of a single distillation column by introducing a heat exchanger, which is one of the methods of external heat integration, in order to reduce the energy consumption of a condenser and the use of cooling utilities in a single distillation column separation process including a decanter.

[0051] In the present invention, a decanter refers to a device used to separate pure substances through liquid-liquid split, and is operated at atmospheric pressure and a temperature close to room temperature.

[0052] The present invention also relates to a process design method capable of reducing energy usage of a reboiler by heating low-temperature raw materials as a result of the heat exchange and supplying heat to a distillation column.

[0053] In the present invention, the strengthening process for a single distillation tower refers to a form in which a heat exchanger is added to the distillation tower process for direct heat exchange between the high-temperature distillation tower top discharge gas and the raw materials and products, which are low-temperature flows within the process.

[0054] In the present invention, the product separated through the decanter is discharged at a low temperature, as shown in FIGS. 2 and 5, or is discharged in a heated state after contributing to additional heat exchange by circulating through a heat exchanger, as shown in FIGS. 3 and 6. The product discharged in a heated state can be used as a heat source for other processes.

[0055] In the present invention, the condenser included in the strengthening process is a device used to completely condense the partially liquefied fluid stream after the hot vapor passes through the heat exchanger described above. While it functions similarly to a conventional condenser, the introduction of the heat exchanger allows the gas to be partially liquefied, resulting in lower energy consumption than conventional condensers.

[0056] In the present invention, the strengthening process including all of the above-described elements relates to a method applied to (a) a separation process of a general liquid mixture; (b) a separation process of a liquid mixture containing water; and (c) a reactive distillation process in which water and heavier organic substances are separated through reactive distillation.

[0057] In the present invention, since the product is continuously used in the strengthening process that utilizes the separated product as a coolant by including reactive distillation, the chemical equilibrium is induced toward the forward reaction according to Le Chatelier's principle, and thus the reactive distillation technology is advantageous for application to the strengthening process.

[0058]

[0059] The present invention will now be described in more detail with reference to examples. These examples are intended merely to illustrate the present invention more specifically, and it will be apparent to those skilled in the art that the scope of the present invention is not limited to these examples.

[0060]

[0061] [Example]

[0062] Examples 1 to 5 below are written in Aspen PlusTM It was carried out by computer process simulation using .

[0063]

[0064] Example 1: Separation and enrichment process of a general liquid mixture (n-pentane, dimethyl formamide separation distillation process)

[0065] First, the existing process for separating n-pentane (C5H12, n-Pentane) and dimethyl formamide (C3H7NO, dimethyl formamide, hereinafter referred to as DMF) was designed. 100 kmol / h of n-pentane and 100 kmol / h of DMF were supplied to stage 15 of a 30-stage RadFrac separation distillation column. The condenser pressure was 1 bar to ensure complete liquefaction of the gas. DMF with a purity of 100 mol% was separated from the lower outlet. An n-pentane / DMF mixture with 76.6 mol% of n-pentane flowed out from the upper outlet and was separated through a decanter at 30°C. As a result, 98 mol% of n-pentane was separated as a product at 30°C. At this time, the energy required for the condenser was 1,510.32 kW, the energy required for the decanter was 57 kW, and the energy required for the reboiler was 2163.34 kW, for a total of 3,730.66 kW of energy.

[0066] Meanwhile, in the first strengthening process, heat was exchanged between the high-temperature distillation column top vapor and the low-temperature feedstock while maintaining the distillation column conditions described above. The distillation column top vapor was a gas at 105°C, but after heat exchange, it became a partially liquefied gas at 48°C (vapor fraction 0.75). To completely liquefy it, a condenser unit was required. On the other hand, the feedstock at 20°C rose in temperature after heat exchange, reaching 38°C and partially vaporizing (vapor fraction 0.4). The heated feedstock provided heat to the distillation column, thereby reducing the energy requirement of the reboiler. As a result, the energy required for the condenser unit was 805.1 kW, the decanter was 57 kW, and the reboiler was 1,458.11 kW, for a total energy of 2,320.21 kW.

[0067] The second intensification process involved adding a product heat exchanger to the first intensification process to further cool the overhead gas. The overhead gas (partially liquefied gas at 48°C (vapor fraction 0.75)) that had previously undergone a heat exchange was further cooled to 42°C (vapor fraction 0.74) through heat exchange with the product discharged through the decanter at 30°C. This reduced the condenser energy requirement to 740.7 kW. On the other hand, the energy requirement for the decanter increased to 80 kW. This is because the flow rate that the decanter must handle increases as the product is recycled to the decanter, as shown in Figure 3. In this process simulation, while the flow rate that the decanter had to handle was 141 kmol, the flow rate that the decanter had to handle increased to 428 kmol in the second intensification process. However, it was confirmed that the total energy consumption was further reduced in the second strengthening process because the energy consumption of the condenser decreased more than the energy demand of the decanter increased.

[0068]

[0069] Through the intensification process, condenser energy consumption was reduced by approximately 47-51%, and reboiler energy consumption was reduced by approximately 32.6%. Utilizing a heat exchanger, the overall process energy consumption was reduced by approximately 36-37% compared to the conventional single distillation process.

[0070]

[0071] Example 2: Separation process and strengthening process of a liquid mixture containing water (water, dodecanol separation distillation process)

[0072] In the same manner as in Example 1, a conventional process for separating water (H2O) and dodecanol (C12H26O, Dodecanol) was first designed. 100 kmol / h of water and 100 kmol / h of dodecanol were supplied to stage 30 of a 60-stage RadFrac separation distillation column. The condenser pressure was 1 bar to ensure complete liquefaction of the gas. Dodecanol with a purity of 100 mol% was separated from the lower outlet. A water / dodecanol mixture with a water content of 74.4 mol% flowed out from the upper outlet and was separated through a decanter at 35°C. As a result, 99 mol% of water was separated as a product at 35°C. At this time, the energy required for the condenser was 2,762.51 kW, the energy required for the decanter was 437.08 kW, and the energy required for the reboiler was 6,971.99 kW, for a total of 10,171.58 kW of energy.

[0073] Meanwhile, in the first strengthening process, heat was exchanged between the distillation column top vapor and the low-temperature feedstock while maintaining the distillation column conditions described above. The distillation column top vapor was a gas at 211.92°C, but after heat exchange, it became a partially liquefied gas at 101°C (vapor fraction 0.67). To completely liquefy it, a condenser unit was required. On the other hand, the feedstock at 20°C rose in temperature after heat exchange, reaching 91°C and partially vaporizing (vapor fraction 0.19). The heated feedstock provided heat to the distillation column, thereby reducing the energy requirement of the reboiler. As a result, the energy required for the condenser unit was 1,207.68 kW, the decanter was 437.08 kW, and the reboiler was 5,417.32 kW, for a total of 8,742.64 kW.

[0074] The second intensification process involved adding a product heat exchanger to the first intensification process to further cool the overhead gas. The overhead gas (partially liquefied gas at 101°C (vapor fraction 0.67)) that had previously undergone a heat exchange was further cooled to 88°C (vapor fraction 0.51) through heat exchange with the product discharged through the decanter at 35°C. This further reduced the condenser energy requirement to 850.61 kW. On the other hand, the energy requirement for the decanter increased to 704.23 kW. This is because, as in Example 1, the flow rate that the decanter must handle increases as the product is recycled to the decanter. In this process simulation, while the flow rate that the decanter had to handle was 150 kmol, the flow rate that the decanter must handle increased to 397 kmol in the second intensification process. However, it was confirmed that the total energy consumption was further reduced in the second strengthening process because the energy consumption of the condenser was reduced more than the energy demand of the decanter increased.

[0075]

[0076] By utilizing a heat exchanger, condenser energy consumption was reduced by approximately 56-69%, and reboiler energy consumption was reduced by approximately 20.6%. Compared to the conventional single distillation process, the overall process energy consumption was reduced by approximately 29-30%.

[0077]

[0078] Meanwhile, the greater the amount of heat exchanged in the heat exchanger, the greater the cooling effect the cold liquid can provide to the hot vapor stream. Furthermore, the greater the amount of pre-condensed liquid, the more the energy required by the condenser decreases. Therefore, in Examples 3-5 below, we sought to determine how much the condenser energy reduction varies with varying head gas temperatures. Accordingly, we introduced reactive distillation, which can generate different head gas temperatures.

[0079]

[0080] Example 3: Reactive distillation process in which water and heavier organics are separated through reactive distillation - low temperature overhead vapor case (esterification reactive distillation process to produce butyl acetate)

[0081] A reactive distillation was considered in which butyl alcohol (C4H9OH) and acetic acid (C2H4O2) react to produce butyl acetate (C6H12O2) and water. The reaction occurred in stages 5 to 40 of a total of 60 Radfrac distillation stages, with the reactants entering stage 5. The condenser pressure was 1 atm, ensuring complete liquefaction of the gas. Butyl acetate with a purity of 99.75 mol% was separated from the lower outlet. A water / butyl alcohol / butyl acetate mixture with 62 mol% water, 14.5 mol% butyl alcohol, and 23.5 mol% butyl acetate flowed out from the upper outlet, and was separated through a decanter at atmospheric pressure and 35°C. As a result, 99 mol% of water was separated as a product at 35°C, and the remaining butyl alcohol / butyl acetate mixture was refluxed into the distillation tower. At this time, the energy required for the condenser was 1,123.59 kW, the energy required for the decanter was 246.19 kW, and the energy required for the reboiler was 1,744.23 kW, for a total of 3,114.008 kW of energy.

[0082] As the first strengthening process, a heat exchanger was introduced to exchange heat between the distillation tower top vapor and the low-temperature feedstock. The distillation tower top vapor was a gas at 95.76°C, but after heat exchange, it became a partially liquefied gas at 91°C (vapor fraction 0.76). To completely liquefy it, a unit corresponding to a condenser was required. On the other hand, the feedstock at 20°C rose in temperature after heat exchange, reaching 81°C. The heated feedstock provided heat to the distillation tower, thereby reducing the energy requirement of the reboiler. As a result, the energy required for the condenser unit was 846.163 kW, the energy required for the decanter was 245.876 kW, and the energy required for the reboiler was 1465.98 kW, for a total of 2,558.019 kW.

[0083] The second intensification process involved adding a product heat exchanger to the first intensification process to further cool the overhead gas. The overhead gas (partially liquefied gas at 101°C (vapor fraction 0.67)) that had previously undergone a heat exchange was further cooled to 88°C (vapor fraction 0.51) through heat exchange with the product discharged through the decanter at 35°C. This further reduced the condenser energy requirement to 721.12 kW. Conversely, the energy requirement for the decanter increased to 293.01 kW. This is because, as in Example 1, the product was recycled to the decanter, increasing the flow rate that the decanter had to process. However, since the energy consumption of the condenser decreased more than the increased energy demand of the decanter, the overall energy consumption was further reduced in the second intensification process. This represents a 20.30% reduction compared to the conventional process.

[0084]

[0085] Example 4: Reactive distillation process for separating water and heavier organics through reactive distillation - intermediate temperature overhead vapor case (esterification reactive distillation process for producing amyl acetate)

[0086] A reactive distillation was considered in which amyl alcohol (C5H11OH) reacts with acetic acid to produce amyl acetate (C7H14O2) and water. The reaction occurred from stage 4 to 44 of a total of 60 Radfrac distillation stages, with the reactants entering stage 4. The condenser pressure was 1 atm to ensure complete liquefaction of the gas. Amyl acetate with a purity of 100 mol% was separated from the lower outlet. A water / amyl alcohol / amyl acetate mixture with 65.6 mol% water, 23.1 mol% amyl alcohol, and 11.1 mol% amyl acetate was distilled from the upper outlet and separated through a decanter at atmospheric pressure and 35°C. As a result, 99.9 mol% water was separated as a product at 35°C, and the remaining amyl alcohol / amyl acetate mixture was refluxed into the distillation tower. At this time, the energy required for the condenser was 1191.15 kW, the energy required for the decanter was 273.29 kW, and the energy required for the reboiler was 1995.49 kW, for a total of 3009.91 kW of energy.

[0087] As the first strengthening process, a heat exchanger was introduced to exchange heat between the distillation tower top vapor and the low-temperature feedstock. The distillation tower top vapor was a gas at 120.7℃, but after heat exchange, it became a partially liquefied gas at 102.4℃ (vapor fraction 0.69). To completely liquefy it, a unit corresponding to a condenser was required. On the other hand, the temperature of the 20℃ feedstock increased after heat exchange, and thus its temperature rose to 92.4℃. As a result, the energy required for the condenser unit was 745.794 kW, the energy required for the decanter was 273.59 kW, and the energy required for the reboiler was 1593.56 kW, for a total of 2533.795 kW.

[0088] The second intensification process involved adding a product heat exchanger to the first intensification process to further cool the overhead gas. The overhead gas (partially liquefied gas at 102.4°C (vapor fraction 0.69)) that had previously undergone a heat exchange was further cooled to 97.6°C (vapor fraction 0.64) through heat exchange with the product discharged through the decanter at 35°C. This further reduced the condenser energy requirement to 718.79 kW. Conversely, the energy requirement for the decanter increased to 289.32 kW. This is because, as in Examples 1 and 3, the product was recycled to the decanter, increasing the flow rate that the decanter had to process. However, since the energy consumption of the condenser decreased more than the increased energy demand of the decanter, the overall energy consumption was further reduced in the second intensification process. This represents a 24.8% reduction compared to the conventional process.

[0089]

[0090] Example 5: Reactive distillation process in which water and heavier organics are separated through reactive distillation - high temperature overhead vapor case (esterification reactive distillation process to produce methyl laurate)

[0091] A reactive distillation was considered in which methanol (CH3OH) and lauric acid (C12H24O2) react to produce methyl laurate (C13H26O2) and water. The reaction occurred in stages 6 to 15 of a total of 18 Radfrac stages, with lauric acid entering stage 1 and methanol entering stage 17. The reason the feedstock was divided into two stages is that the difference in boiling points between lauric acid and methanol is large, so that if they entered the same stage, the reaction would not occur well in the reaction section of the distillation column. Therefore, lauric acid with a higher boiling point was introduced at the top, and methanol with a lower boiling point was introduced at the bottom so that they could mix well. The condenser pressure was 1 atm to ensure complete liquefaction of the gas. Methyl laurate with a purity of 99.9 mol% was separated from the lower outlet. A mixture of water / methyl laurate / lauric acid (59.6 mol% water, 32 mol% methyl laurate, and 8.5 mol% lauric acid) was discharged through the upper outlet and separated through a decanter at atmospheric pressure and 35°C. As a result, 99.99 mol% water was separated as a product at 35°C, and the remaining mixture of methyl laurate / lauric acid was refluxed into the distillation column. At this time, the energy required for the condenser was 1828.89 kW, the energy required for the decanter was 432.55 kW, and the energy required for the reboiler was 4059.64 kW, for a total of 6321.08 kW of energy.

[0092] As the first strengthening process, heat exchangers were introduced to exchange heat between the distillation tower top vapor and the low-temperature feedstock. Meanwhile, since the low-temperature feedstock was divided into two (methanol and lauric acid), two heat exchangers were used. The distillation tower top vapor was a gas at 235.9°C, but after two heat exchanges, it became a partially liquefied gas at 87°C (vapor fraction 0.5). To completely liquefy it, a unit equivalent to a condenser was required. On the other hand, the low-temperature feedstock was a liquid at 20°C, but as the temperature increased, lauric acid entered the distillation tower as a liquid at 158°C and methanol as a gas at 77°C. As a result, the energy required for the unit corresponding to the condenser was 660.9 kW, the energy required for the decanter was 432.66 kW, and the energy required for the reboiler was 2595.82 kW, for a total of 3689.42 kW of energy.

[0093] The second strengthening process involved adding a product heat exchanger to the first strengthening process to further cool the overhead gas. The overhead gas (partially liquefied gas at 87°C (vapor fraction 0.5)) that had undergone two heat exchanges was further cooled to 83.6°C (vapor fraction 0.47) through heat exchange with the product discharged through the decanter at 35°C. This further reduced the condenser energy requirement to 387.81 kW. By cooling the overhead gas three times, the condenser energy consumption was reduced by 78.8% compared to the previous process. Meanwhile, unlike the previous Example 1-4, the energy requirement for the decanter was slightly reduced to 368.99 kW. This is because although the product was recycled to the decanter, the amount was small, and the temperature of the overhead vapor was significantly reduced through the three heat exchanges, which reduced the energy requirement for the decanter. Compared to the existing process, the reinforcement process showed an energy reduction rate of 46.96%.

[0094]

[0095] Table 3 compares the energy usage of Example 3-5.

[0096]

[0097] The results of Example 3-5 show that the higher the temperature of the distillation column top outlet gas, the greater the energy consumption of the condenser and the overall process. This is because the higher the vapor temperature, the greater the cooling effect that the low-temperature stream within the process can provide to the high-temperature top outlet vapor stream, thereby increasing the amount of vapor condensed, thereby further reducing the amount of energy required for the condenser. Therefore, the intensification process proposed in the present invention can maximize the application effect by reducing the overall energy consumption by up to approximately 47% as the temperature of the distillation column top outlet gas increases.

[0098]

[0099] While specific aspects of the present invention have been described in detail above, it will be apparent to those skilled in the art that these specific descriptions merely represent preferred embodiments and are not intended to limit the scope of the present invention. Therefore, the substantial scope of the present invention is defined by the appended claims and their equivalents.

[0100]

[0101] The present invention partially replaces the role of a condenser, i.e., the process of liquefying the upper outlet gas of a distillation column, by introducing a heat exchanger, thereby reducing the cost of cooling water used in existing condensers and the energy requirement of the condenser, thereby reducing energy and costs. In addition, by using the raw material and low-boiling-point liquid product, which are the flow within the process, as coolants, continuous supply of coolants within the process is possible. In addition, the low-temperature raw material can be heated through heat exchange to supply heat to the distillation column, thereby further reducing the energy requirement of the reboiler. The distillation apparatus according to the present invention can effectively separate the raw material mixture or the reaction mixture generated in the reaction section, and it was confirmed that, in particular, the higher the temperature of the upper outlet gas of the distillation column, the greater the reduction in energy consumption and costs.

Claims

1. Distillation tower (1) for separating a raw material mixture or reaction mixture; A raw material heat exchanger (5) that liquefies a portion of the gas emanating from the upper portion of the distillation tower through heat exchange with a low-temperature raw material mixture; A condenser (3) that liquefies the distillation tower top discharge gas that is not completely condensed in the above raw material heat exchanger; A reboiler (4) that heats and evaporates the liquid effluent from the bottom of the distillation tower and refluxes some of the vapor generated to the distillation tower; and A distillation apparatus including a decanter (2) for separating a liquid mixture condensed in the above condenser, A distillation device characterized in that the distillation device uses a raw material mixture as a coolant.

2. In the first paragraph, a product heat exchanger (6) is additionally included to further condense a portion of the upper outlet gas through heat exchange between a portion of the liquefied gas through the raw material heat exchanger (5) and a low-temperature, low-boiling-point liquid product separated from the decanter (2). A distillation device characterized in that the distillation device uses the raw material mixture and the low-boiling-point liquid product as a coolant.

3. A distillation apparatus characterized in that in paragraph 1, the distillation tower (1) is a single distillation tower or a reaction distillation tower including a reaction section (7).

4. A method for fractionally distilling a raw material mixture or a reaction mixture using a distillation device according to any one of claims 1 to 3.

5. A method according to claim 4, characterized in that it comprises the following steps: a) In order to separate the raw material mixture, a step of injecting the raw material mixture into a distillation tower (1), then discharging high-boiling-point substances in a liquid state to the bottom of the distillation tower, and discharging low-boiling-point substances in a gaseous state to the top of the distillation tower; b) A step of injecting the high-temperature gas discharged from the top of the distillation tower into a raw material heat exchanger (5) and liquefying a portion of the high-temperature gas through heat exchange with a low-temperature raw material; c) a step of injecting a gas that is not completely liquefied in the raw material heat exchanger into a condenser (3) and injecting a completely condensed liquid mixture into a decanter (2); and d) A step of separating the injected liquid mixture in a decanter to discharge high-boiling-point liquid products and injecting low-boiling-point liquid products back into the distillation column as a reflux flow.

6. A method according to claim 4, characterized in that it further comprises the following steps: a) In order to separate the raw material mixture, a step of injecting the raw material mixture into a distillation tower (1), then discharging high-boiling-point substances in a liquid state to the bottom of the distillation tower, and discharging low-boiling-point substances in a gaseous state to the top of the distillation tower; b) A step of injecting the high-temperature gas discharged from the top of the distillation tower into a raw material heat exchanger (5) and liquefying a portion of the high-temperature gas through heat exchange with a low-temperature raw material; c) A step of injecting some of the liquefied gas from the raw material heat exchanger into the product heat exchanger (6) to further cool the gas through heat exchange with the low-boiling-point liquid product discharged from the decanter; d) a step of injecting a gas that is not completely liquefied in the above product heat exchanger into a condenser (3) and injecting a completely condensed liquid mixture into a decanter (2); and e) A step of discharging a portion of the heated product from the above product heat exchanger and recycling the remainder back to the decanter.

7. A method according to claim 4, characterized in that it comprises the following steps: a) A step of injecting a raw material mixture into a distillation tower (1), then discharging high-boiling-point substances from the reaction mixture generated in the reaction section (7) to the bottom of the distillation tower, and discharging high-temperature gases to the top of the distillation tower; b) A step of injecting the high-temperature gas discharged from the top of the distillation tower into a raw material heat exchanger (5) and liquefying a portion of the high-temperature gas through heat exchange with a low-temperature raw material; c) a step of injecting a gas that is not completely liquefied in the raw material heat exchanger into a condenser (3) and injecting a completely condensed liquid mixture into a decanter (2); and d) A step of separating the injected liquid mixture in a decanter to discharge high-boiling-point liquid products and injecting low-boiling-point liquid products back into the distillation column as a reflux flow.

8. A method according to claim 4, characterized in that it further comprises the following steps: a) A step of injecting a raw material mixture into a distillation tower (1), then discharging high-boiling-point substances from the reaction mixture generated in the reaction section (7) to the bottom of the distillation tower, and discharging high-temperature gases to the top of the distillation tower; b) A step of injecting the high-temperature gas discharged from the top of the distillation tower into a raw material heat exchanger (5) and liquefying a portion of the high-temperature gas through heat exchange with a low-temperature raw material; c) A step of injecting some of the liquefied gas from the raw material heat exchanger (5) into the product heat exchanger (6) to further cool the gas through heat exchange with the low-boiling-point liquid product discharged from the decanter; d) a step of injecting a gas that is not completely liquefied in the above product heat exchanger into a condenser (3) and injecting a completely condensed liquid mixture into a decanter (2); and e) A step of discharging a portion of the heated product from the above product heat exchanger and recycling the remainder back to the decanter.

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