Heat integrated separation system

Abstract

A heat-integrated separation system is provided, comprising a first tower and a second tower, wherein an upper exhaust stream of the first tower is compressed by a compressor, and then the upper exhaust stream of the first tower is heat exchanged with a lower exhaust stream of the second tower in a second heat exchanger, and the upper exhaust stream of the second tower is heat exchanged with the lower exhaust stream of the first tower in the first heat exchanger, and equation 1 is satisfied (see the specification).

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Korean Patent Application No. 10-2021-0134244 filed in Korea on October 8, 2021, the entire contents of which are incorporated herein by reference for all purposes. Technical Field

[0004] The present invention relates to a heat-integrated separation system, and more particularly, to a system for separating a multi-component mixture containing three or more components, wherein the system for separating a multi-component mixture containing three or more components does not use additional cooling energy or heating energy when separating the multi-component mixture. Background Art

[0005] In chemical processing, multiple columns can be used to separate a desired product from other components in a multi-component mixture containing three or more components. For example, a mixture containing three or more components may contain a low-boiling component, a product, and a high-boiling component with different boiling points, and more than two columns may be required to separate the various components.

[0006] For example, a mixture comprising three or more components can be supplied to a front-stage tower, in which a high boiling point component can be separated downwards, and a low boiling point component and a medium boiling point component can be supplied to a rear-stage tower. In a rear-stage tower, a low boiling point component can be separated upwards and a medium boiling point component can be separated downwards. In addition, a mixture comprising three or more components can be supplied to a front-stage tower, in which a low boiling point component can be separated upwards, a medium boiling point component and a high boiling point component can be separated downwards, and the medium boiling point component and the high boiling point component can be supplied to a rear-stage tower, in which a medium boiling point component can be separated upwards and a high boiling point component can be separated downwards.

[0007] Therefore, when two or more columns are used to separate a multi-component mixture, cooling energy is used in the condenser above the column, and heating energy is used in the reboiler below the column. In addition, the use of heat energy produces carbon dioxide, which constantly raises sustainability issues. Summary of the Invention

[0008] Technical issues

[0009] An object of the present invention is to provide a heat-integrated separation system that operates using waste heat from a process to save energy and does not use external fossil fuels when separating a mixture containing more than three components using two towers.

[0010] Technical Solution

[0011] In one general aspect, a heat-integrated separation system includes a first tower and a second tower, wherein an upper exhaust stream of the first tower is compressed by a compressor and then heat-exchanged with a lower exhaust stream of the second tower in a second heat exchanger, and the upper exhaust stream of the second tower is heat-exchanged with the lower exhaust stream of the first tower in the first heat exchanger, and satisfies the following Formula 1.

[0012] [Formula 1]

[0013] T1<T2<T3<T4

[0014] In Formula 1, T1 is the temperature of the lower discharge stream of the first tower which is returned to the first tower after heat exchange in the first heat exchanger, T2 is the temperature of the upper discharge stream of the second tower which is returned to the second tower after heat exchange in the first heat exchanger, T3 is the temperature of the lower discharge stream of the second tower which is returned to the second tower after heat exchange in the second heat exchanger, and T4 is the temperature of the upper discharge stream of the first tower which is returned to the first tower after heat exchange in the second heat exchanger.

[0015] Beneficial effects

[0016] According to the heat-integrated separation system of the present invention, by adjusting the operating pressures of the first tower and the second tower, the waste heat of the upper exhaust stream of the second tower is used to heat the lower exhaust stream of the first tower. In addition, when it is difficult to perform heat exchange between the upper exhaust stream of the first tower and the lower exhaust stream of the second tower, a compressor is used to compress the upper exhaust stream of the first tower, so that the upper exhaust stream of the first tower and the lower exhaust stream of the second tower can perform heat exchange without using additional fossil fuels, thereby reducing the generation of carbon dioxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figures 1 to 4 They are process flow charts of a heat-integrated separation system according to an example of the present invention.

[0018] Figures 5 to 7 They are respectively process flow charts of the heat integrated separation system according to comparative examples. DETAILED DESCRIPTION

[0019] The terms and words used in this specification and claims should not be interpreted as general meanings or dictionary meanings, but should be interpreted as meanings and concepts that satisfy the technical concept of the present invention based on the principle that inventors can appropriately define the concepts of the terms in order to describe their own inventions in the best mode.

[0020] As used herein, the term "flow" may refer to the flow of a fluid in a process or the fluid itself flowing in a pipeline. Specifically, "flow" may refer to both the fluid itself flowing in a pipeline connecting various devices to each other and the flow of a fluid. In addition, a fluid may include any one or more components selected from the group consisting of gases, liquids, and solids.

[0021] In the following, reference will be made to Figures 1 to 4 The present invention is described in more detail to help understanding the present invention.

[0022] According to the present invention, a heat-integrated separation system is provided. The heat-integrated separation system may include a first tower 10 and a second tower 20, wherein an upper exhaust stream of the first tower 10 may be compressed by a compressor 30 and then heat-exchanged with a lower exhaust stream of the second tower 20 in a second heat exchanger, and the upper exhaust stream of the second tower 20 may heat-exchange with a lower exhaust stream of the first tower 10 in a first heat exchanger 11.

[0023] In chemical processing, multiple columns can be used to separate a desired product from other components in a multi-component mixture containing three or more components. For example, a mixture containing three or more components may contain a low-boiling component, a product, and a high-boiling component with different boiling points, and more than two columns may be required to separate the various components.

[0024] Therefore, when two or more columns are used to separate a multi-component mixture, cooling energy is used in the condenser above the column and heating energy is used in the reboiler below the column. In addition, the use of heat energy produces carbon dioxide, which raises sustainability issues.

[0025] Unlike the prior art, the present invention provides a heat-integrated separation system that can reduce energy consumption when separating a multi-component mixture including products using two or more towers, and reduce carbon dioxide generation by not using additional fossil fuels as heat energy.

[0026] According to an embodiment of the present invention, the heat-integrated separation system may be applied to various fields of separating products contained in a feed stream containing three or more components using the first tower 10 and the second tower 20 .

[0027] The feed stream may be a multi-component mixture that may be produced during a chemical process. The multi-component mixture may contain three or more components, specifically, products, high-boiling components, and low-boiling components. For example, the feed stream may include a multi-component mixed stream from a naphtha cracking process and reaction product streams from various reactions. As a specific example, the feed stream may be a non-aromatic hydrocarbon stream produced in a naphtha cracking process, and n-hexane may be separated from the non-aromatic hydrocarbon stream using a heat-integrated separation system.

[0028] The content of the product in the feed stream may be 10 wt% to 40 wt%, the content of low boiling point components may be 30 wt% to 60 wt%, and the content of high boiling point components may be 30 wt% to 60 wt%.

[0029] According to an embodiment of the present invention, the first tower 10 and the second tower 20 may each be an apparatus for separation by distillation using a boiling point difference between components in a feed stream.

[0030] Each of the upper exhaust stream and the lower exhaust stream of the first tower 10 and the second tower 20 may be branched before or after heat exchange in the first heat exchanger 11 and the second heat exchanger 21. A portion of the branched stream may be refluxed and may be transferred to the next stage tower or the remaining portion of the separated stream.

[0031] According to an embodiment of the present invention, the operating pressures of the first tower 10 and the second tower 20 may be different. For example, the operating pressure of the first tower 10 may be lower than the operating pressure of the second tower 20. As a specific example, the operating pressure of the first tower 10 may be 0.5 kg / cm lower than the operating pressure of the second tower 20. 2 .g and above, 0.6kg / cm 2 .g or above or 0.75kg / cm 2 .g or more, and 1kg / cm 2 .g or less, 1.15kg / cm 2 .g or less or 1.5kg / cm 2 By controlling the operating pressures of the first tower 10 and the second tower 20 within the above range, the upper exhaust stream of the second tower 20 and the lower exhaust stream of the first tower can be heat exchanged in the first heat exchanger 11, thereby improving the separation efficiency of the first tower 10 and the second tower 20.

[0032] To achieve sufficient heat exchange between process streams, a temperature difference is necessary. To this end, the operating pressure of the energy-supplying column (e.g., second column 20) can be increased. Therefore, increasing the operating pressure of second column 20 increases the temperature of the upper exhaust stream, thereby promoting heat exchange with the lower exhaust stream of first column 10. However, this also increases the temperature of the lower exhaust stream of second column 20. In this case, the upper exhaust stream of first column 10, operating at a lower pressure than second column 20, has a lower temperature, while the lower exhaust stream of second column 20 has an increased temperature. Consequently, there may not be an adequate temperature difference between the upper exhaust stream of first column 10 and the lower exhaust stream of second column 20, making heat exchange between them difficult. Furthermore, even if heat exchange is performed in second heat exchanger 21, the upper exhaust stream of first column 10 requires a cooler and cooling energy for additional cooling, while the lower exhaust stream of second column 20 requires a heater and heating energy for additional heating.

[0033] According to an embodiment of the present invention, the upper exhaust stream of the first tower 10 may be compressed using the compressor 30 to increase the temperature based on gas characteristics, and the upper exhaust stream of the first tower 10 having the increased temperature may be heat-exchanged with the lower exhaust stream of the second tower 20. Specifically, the upper exhaust stream of the first tower 10 may be compressed by the compressor 30 and then heat-exchanged with the lower exhaust stream of the second tower 20 in the second heat exchanger 21.

[0034] The compression degree of the upper exhaust stream of the first tower 10 can be controlled according to the heat energy required by the compressor 30, and the pressure after passing through the compressor 30 can be higher by 1 kg / cm 2 .g to 30kg / cm 2 .g.

[0035] Generally, there is a limit in increasing the temperature and heat energy of the fluid by compressing the gas using the compressor 30. For example, the temperature and heat energy of the fluid can be increased by compressing up to 30 kg / cm 2 .g to increase the temperature and thus improve the heat transfer efficiency of the heat exchanger. However, even in this case, the thermal energy of the compressed fluid is insufficient, so without additional heating, temperature reversal may occur after heat exchange. Therefore, even if the upper exhaust stream of the first tower 10 is compressed only at the maximum power of the compressor 30, the temperature can be increased. However, due to insufficient thermal energy, when heat exchanging with the lower exhaust stream of the second tower 20, additional thermal energy may be required due to insufficient thermal energy of the compressed fluid. For this reason, in the present invention, the temperature after heat exchange is controlled to prevent temperature reversal by using sufficient thermal energy, so that the process can be carried out without using additional thermal energy.

[0036] According to an embodiment of the present invention, when separating products in a feed stream using the first tower 10 and the second tower 20 , the heat integrated separation system may operate and satisfy the following Formula 1, thereby operating the heat integrated separation system without using additional fossil fuel.

[0037] [Formula 1]

[0038] T1<T2<T3<T4

[0039] In Formula 1, T1 is the temperature of the lower discharge stream of the first tower 10 which is returned to the first tower 10 after heat exchange in the first heat exchanger 11, T2 is the temperature of the upper discharge stream of the second tower 20 which is returned to the second tower 20 after heat exchange in the first heat exchanger 11, T3 is the temperature of the lower discharge stream of the second tower 20 which is returned to the second tower 20 after heat exchange in the second heat exchanger 21, and T4 is the temperature of the upper discharge stream of the first tower 10 which is returned to the first tower 10 after heat exchange in the second heat exchanger 21.

[0040] Specifically, in Equation 1, T1, T2, T3, and T4, which are the temperatures of the streams undergoing heat exchange in first heat exchanger 11 or second heat exchanger 21, respectively, may be affected by the flow rate of the feed stream, the operating conditions of first tower 10 and second tower 20, and the temperature, composition, and flow rate of each stream undergoing heat exchange in first heat exchanger 11 or second heat exchanger 21. If Equation 1 is not satisfied, a temperature reversal may occur after heat exchange, making heat exchange impossible without the use of additional fuel, or heat exchange efficiency may decrease, causing fossil fuels to be used as heat energy, resulting in the generation of carbon dioxide. As a specific example, when a temperature reversal occurs after heat exchange between low temperature T1 and high temperature T2, T2 becomes lower than T1, indicating that heat exchange from T2 to T1 is not fully performed. Even when the temperatures are equal after heat exchange between low temperature T1 and high temperature T2, the heat exchange efficiency is low due to the equalization of T2 and T1, indicating that heat exchange is not fully performed. Therefore, in both cases, additional heat energy needs to be used to increase T2, and there is a problem of carbon dioxide generation due to the use of fuel in the process.

[0041] Each of the differences between T1 and T2 and T3 and T4 can be 0.1°C or more, 0.6°C or more, 1.2°C or more, 2°C or more, or 2.2°C or more, and 2°C or less, 2.5°C or less, 3°C or less, 4°C or less, 5°C or less, or 6°C or less. Specifically, if T1 is lower than T2 or T3 is lower than T4, heat exchange may not be performed due to temperature inversion, and if T1 and T2 are equal or T3 and T4 are equal, heat exchange efficiency may deteriorate. In addition, since T1 and T2 and T3 and T4 each have a temperature difference within the above range, the flow used as the heat medium for providing heat in the flow to be heat exchanged has sufficient thermal energy, so that heat exchange can be performed efficiently, and the use of additional thermal energy may not be necessary.

[0042] Furthermore, the difference between T1 and T2 may be 0.1° C. or greater, 0.3° C. or greater, 0.6° C. or greater, 1° C. or greater, 2° C. or greater, or 2.2° C. or greater, and 2.5° C. or less, 2.8° C. or less, or 3° C. or less. If the difference between T1 and T2 is greater than 3° C., even if the third heat exchanger 40 is fully utilized, a temperature inversion problem between T3 and T4 may occur.

[0043] According to an embodiment of the present invention, the feed stream may be heated before being supplied to the first tower 10 or the second tower 20. For example, a general heating method includes a heating method using thermal energy of a heater, but in the heat-integrated separation system of the present invention, waste heat in the process may be used to heat the feed stream without using additional thermal energy.

[0044] When the feed stream is supplied to the first tower 10 or the second tower 20, the product, the low-boiling point component, and the high-boiling point component contained in the feed stream may be separated from each other in the first tower 10 or the second tower 20. At this time, the low-boiling point component may be separated from the upper discharge stream of the first tower 10 or the second tower 20, and the high-boiling point component may be separated from the lower discharge stream of the first tower 10 or the second tower 20.

[0045] The stream containing the low-boiling-point component and the stream containing the high-boiling-point component can form a mixed stream and can be discharged from the system, and the mixed stream can be heat-exchanged with the feed stream in the third heat exchanger 40 before being discharged. Specifically, by utilizing the waste heat of the mixed stream of the stream containing the low-boiling-point component and the stream containing the high-boiling-point component to heat the feed stream, the feed stream can be heated without using additional heat energy, and by heating the feed stream, the flow rate of the upper discharge stream of the first tower 10 can be increased and satisfy Equation 1, and the heat exchange efficiency with the lower discharge stream of the second tower 20 can be improved without temperature inversion.

[0046] After heat exchange in the third heat exchanger 40, the temperature difference between the mixed stream of the stream containing the low-boiling point component and the stream containing the high-boiling point component and the feed stream may be 0.1° C. or more, 1° C. or more, 1.5° C. or more, 1.8° C. or more, 2° C. or more, or 2.5° C. or more, and 3° C. or less, 5.7° C. or less, 6° C. or less, 7° C. or less, 8° C. or less, 9° C. or less, or 10° C. or less. The temperature of the feed stream after heat exchange may be affected by the temperature, component, and flow rate of the feed stream and the mixed stream, and by adjusting the temperature difference between the mixed stream and the feed stream after heat exchange in the third heat exchanger 40 within the above range, Equation 1 may be satisfied, and operating conditions optimized for the heat-integrated separation system according to the present invention may be achieved.

[0047] According to an embodiment of the present invention, the first tower 10 and the second tower 20 may be used to separate products, low-boiling point components, and high-boiling point components in a feed stream through various operations.

[0048] For example, Figure 1 As shown, the feed stream may be supplied to the first tower 10, low-boiling-point components may be separated from the upper discharge stream of the first tower 10, products may be separated from the upper discharge stream of the second tower 20, and high-boiling-point components may be separated from the lower discharge stream of the second tower 20. Specifically, after the feed stream passes through the third heat exchanger 40, the feed stream may be supplied to the first tower 10, a portion of the lower discharge stream of the first tower 10 may be supplied to the first heat exchanger 11 to perform heat exchange with the upper discharge stream of the second tower 20, and then refluxed to the first tower 10, and the remaining stream may be supplied to the second tower 20. In addition, the upper discharge stream of the first tower 10 may be compressed in the compressor 30 and supplied to the second heat exchanger 21 to perform heat exchange with a portion of the lower discharge stream of the second tower 20, which may then refluxed to the first tower 10, low-boiling-point components may be separated from the remaining stream, and the remaining stream may be heat exchanged with the feed stream in the third heat exchanger 40 and then discharged. In addition, after the upper exhaust stream of the second tower 20 is heat-exchanged in the first heat exchanger 11, a portion of the stream may be refluxed to the second tower 20, and a product may be separated from the remaining stream. In addition, a portion of the lower exhaust stream of the second tower 20 may be passed through the second heat exchanger 21 and then refluxed to the second tower 20, high-boiling-point components may be separated from the remaining stream, and the remaining stream may be heat-exchanged with the feed stream in the third heat exchanger 40 before being discharged. At this time, the remaining stream of the upper exhaust stream of the first tower 10 that has passed through the second heat exchanger 21 may form a mixed stream with the remaining stream of the lower exhaust stream of the second tower 20, and the mixed stream may be heat-exchanged with the feed stream in the third heat exchanger 40 before being discharged.

[0049] As another example, Figure 2As shown, the feed stream may be supplied to the first tower 10, high-boiling-point components may be separated from the lower discharge stream of the first tower 10, low-boiling-point components may be separated from the upper discharge stream of the second tower 20, and products may be separated from the lower discharge stream of the second tower 20. Specifically, after the feed stream passes through the third heat exchanger 40, the feed stream may be supplied to the first tower 10, a portion of the lower discharge stream of the first tower 10 may be supplied to the first heat exchanger 11 to undergo heat exchange with the upper discharge stream of the second tower 20, and then refluxed to the first tower 10, high-boiling-point components may be separated from the remaining stream, and the remaining stream may undergo heat exchange with the feed stream in the third heat exchanger 40 and then be discharged. In addition, the upper discharge stream of the first tower 10 may be compressed in the compressor 30 and supplied to the second heat exchanger 21 to undergo heat exchange with a portion of the lower discharge stream of the second tower 20, and then the portion of the stream may be refluxed to the first tower 10, and the remaining stream may be supplied to the second tower 20. In addition, after the upper exhaust stream of the second tower 20 is heat-exchanged in the first heat exchanger 11, a portion of the stream may be refluxed to the second tower 20, low-boiling-point components may be separated from the remaining stream, and the remaining stream may be heat-exchanged with the feed stream in the third heat exchanger 40 before being discharged. In addition, a portion of the lower exhaust stream of the second tower 20 may be passed through the second heat exchanger 21, then refluxed to the second tower 20, and a product may be separated from the remaining stream. At this time, the remaining stream of the upper exhaust stream of the second tower 20 that has passed through the first heat exchanger 11 may form a mixed stream with the remaining stream of the lower exhaust stream of the first tower 10, and the mixed stream may be heat-exchanged with the feed stream in the third heat exchanger 40 before being discharged.

[0050] As another example, Figure 3As shown, the feed stream may be supplied to the second tower 20, high-boiling-point components may be separated from the lower discharge stream of the second tower 20, low-boiling-point components may be separated from the upper discharge stream of the first tower 10, and products may be separated from the lower discharge stream of the first tower 10. Specifically, after the feed stream passes through the third heat exchanger 40, the feed stream may be supplied to the second tower 20, a portion of the lower discharge stream of the second tower 20 may be supplied to the second heat exchanger 21 to perform heat exchange with the upper discharge stream of the first tower 10 compressed by the compressor 30, and then refluxed to the second tower 20, high-boiling-point components may be separated from the remaining stream, and the remaining stream may be heat exchanged with the feed stream in the third heat exchanger 40 and then discharged. In addition, the upper discharge stream of the second tower 20 may be supplied to the first heat exchanger 11 to perform heat exchange with a portion of the lower discharge stream of the first tower 10, and then the portion may be refluxed to the second tower 20, and the remaining stream may be supplied to the first tower 10. In addition, the upper exhaust stream of the first tower 10 may be compressed in the compressor 30 and supplied to the second heat exchanger 21, heat exchanged in the second heat exchanger 21, and then a portion of the stream may be refluxed to the first tower 10, low-boiling point components may be separated from the remaining stream, and the remaining stream may be heat exchanged with the feed stream in the third heat exchanger 40 before being discharged. In addition, a portion of the lower exhaust stream of the first tower 10 may pass through the first heat exchanger 11, then may be refluxed to the first tower 10, and a product may be separated from the remaining stream. At this time, the remaining stream of the upper exhaust stream of the first tower 10 that has passed through the second heat exchanger 21 may form a mixed stream with the remaining stream of the lower exhaust stream of the second tower 20, and the mixed stream may be heat exchanged with the feed stream in the third heat exchanger 40 before being discharged.

[0051] As another example, Figure 4As shown, the feed stream may be supplied to the second tower 20, low-boiling-point components may be separated from the upper discharge stream of the second tower 20, products may be separated from the upper discharge stream of the first tower 10, and high-boiling-point components may be separated from the lower discharge stream of the first tower 10. Specifically, after the feed stream passes through the third heat exchanger 40, the feed stream may be supplied to the second tower 20, a portion of the lower discharge stream of the second tower 20 may be supplied to the second heat exchanger 21 to perform heat exchange with the upper discharge stream of the first tower 10, which is compressed by the compressor 30 and then refluxed to the second tower 20, and the remaining stream may be supplied to the first tower 10. In addition, the upper discharge stream of the second tower 20 may be supplied to the first heat exchanger 11 to perform heat exchange with a portion of the lower discharge stream of the first tower 10, and the portion may then be refluxed to the second tower 20, low-boiling-point components may be separated from the remaining stream, and the remaining stream may be heat exchanged with the feed stream in the third heat exchanger 40 and then discharged. In addition, the upper exhaust stream of the first tower 10 may be compressed in the compressor 30 and supplied to the second heat exchanger 21, undergo heat exchange in the second heat exchanger 21, and then a portion of the stream may be refluxed to the first tower 10, and a product may be separated from the remaining stream. In addition, a portion of the lower exhaust stream of the first tower 10 may pass through the first heat exchanger 11, then may be refluxed to the first tower 10, high-boiling-point components may be separated from the remaining stream, and the remaining stream may be heat exchanged with the feed stream in the third heat exchanger 40 before being discharged. At this time, the remaining stream of the upper exhaust stream of the second tower 20 that has passed through the first heat exchanger 11 may form a mixed stream with the remaining stream of the lower exhaust stream of the first tower 10, and the mixed stream may be heat exchanged with the feed stream in the third heat exchanger 40 before being discharged.

[0052] According to an embodiment of the present invention, the content of the product in the stream from which the product is separated (e.g., the upper or lower effluent stream of the first tower 10 or the second tower 20) may be 50 wt% to 85 wt%. In addition, the recovery rate of the product may be 60% to 95%. In this case, the recovery rate of the product may refer to the ratio of the content of the product in the stream from which the product is separated to the content of the product contained in the feed stream.

[0053] According to an embodiment of the present invention, in the heat-integrated separation system, if necessary, equipment such as a column, a condenser, a reboiler, a valve, a pump, a separator, and a mixer may be additionally installed.

[0054] As described above, although the heat-integrated separation system according to the present invention has been described and shown in the accompanying drawings, in the above description and drawings, only the main components for understanding the present invention are described and illustrated, and processes and equipment that are not separately described and not shown can be appropriately applied and used to realize the heat-integrated separation system according to the present invention.

[0055] Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are intended to illustrate the present invention, and it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention, and the scope of the present invention is not limited thereto.

[0056] Examples

[0057] Example 1

[0058] like Figure 1 A commercial simulation tool (Aspen Plus manufactured by Aspen Corporation) was used to validate the heat-integrated separation system as shown in the process flow diagram shown.

[0059] Specifically, a feed stream containing 20 wt% of n-hexane, 40 wt% of low-boiling point components, and 40 wt% of high-boiling point components passes through the third heat exchanger 40 and is then supplied to the first tower 10, and a portion of the lower discharge stream of the first tower 10 is supplied to the first heat exchanger 11, heat-exchanged with the upper discharge stream of the second tower 20, and then refluxed to the first tower 10, and the remaining stream is supplied to the second tower 20. In addition, the upper discharge stream of the first tower 10 is compressed in the compressor 30 and supplied to the second heat exchanger 21 to heat-exchange with a portion of the lower discharge stream of the second tower 20, which is then refluxed to the first tower 10, and the remaining stream containing the low-boiling point components is separated, heat-exchanged with the feed stream in the third heat exchanger 40, and then discharged. At this time, the operating pressure of the first tower 10 is adjusted to 0.5 kg / cm 2 .g.

[0060] After the upper discharge stream of the second tower 20 is heat-exchanged in the first heat exchanger 11, a portion of the stream is refluxed to the second tower 20, and the product is separated from the remaining stream. In addition, a portion of the lower discharge stream of the second tower 20 passes through the second heat exchanger 21 and then refluxed to the second tower 20, and the remaining stream containing high-boiling-point components is separated, heat-exchanged with the feed stream in the third heat exchanger 40, and then discharged. At this time, the remaining stream of the upper discharge stream of the first tower 10 that has passed through the second heat exchanger 21 and the remaining stream of the lower discharge stream of the second tower 20 form a mixed stream, and the mixed stream is heat-exchanged with the feed stream in the third heat exchanger 40 and then discharged. In addition, the operating pressure of the second tower 20 is adjusted to 1.4 kg / cm 2 .g.

[0061] In the Examples and Comparative Examples, operations were performed so that the content of the product in the stream from which the product was separated and the recovery rate of the product were the same.

[0062] The temperature T of the feed stream supplied to the first column 10 after heat exchange in the third heat exchanger 40 isin , the temperature T1 of the lower discharge stream of the first tower 10 which is refluxed to the first tower 10 after heat exchange in the first heat exchanger 11, the temperature T2 of the upper discharge stream of the second tower 20 which is refluxed to the second tower 20 after heat exchange in the first heat exchanger 11, the temperature T3 of the lower discharge stream of the second tower 20 which is refluxed to the second tower 20 after heat exchange in the second heat exchanger 21, the temperature T4 of the upper discharge stream of the first tower 10 which is refluxed to the first tower 10 after heat exchange in the second heat exchanger 21, and the temperature T5 of the mixed stream discharged after heat exchange in the third heat exchanger 40. out As shown in Table 1 below.

[0063] In addition, the amount of energy used in this process is shown in Table 2 below.

[0064] Example 2

[0065] like Figure 2 A commercial simulation tool (Aspen Plus manufactured by Aspen Corporation) was used to validate the heat-integrated separation system as shown in the process flow diagram shown.

[0066] Specifically, a feed stream containing 20 wt% of n-hexane, 40 wt% of low-boiling-point components, and 40 wt% of high-boiling-point components passes through the third heat exchanger 40 and is then supplied to the first tower 10, and a portion of the lower discharge stream of the first tower 10 is supplied to the first heat exchanger 11, heat-exchanged with the upper discharge stream of the second tower 20, and then refluxed to the first tower 10, and the remaining stream containing the high-boiling-point components is separated and heat-exchanged with the feed stream in the third heat exchanger 40, and then discharged. In addition, the upper discharge stream of the first tower 10 is compressed in the compressor 30 and supplied to the second heat exchanger 21 to heat-exchange with a portion of the lower discharge stream of the second tower 20, and then the portion is refluxed to the first tower 10, and the remaining stream is supplied to the second tower 20. At this time, the operating pressure of the first tower 10 is adjusted to 0.5 kg / cm 2 .g.

[0067] After the upper discharge stream of the second tower 20 is heat-exchanged in the first heat exchanger 11, a portion of the stream is refluxed to the second tower 20, and the remaining stream containing low-boiling components is separated, heat-exchanged with the feed stream in the third heat exchanger 40, and then discharged. In addition, a portion of the lower discharge stream of the second tower 20 passes through the second heat exchanger 21, then refluxed to the second tower 20, and the product is separated from the remaining stream. At this time, the remaining stream of the upper discharge stream of the second tower 20 that has passed through the first heat exchanger 11 and the remaining stream of the lower discharge stream of the first tower 10 form a mixed stream, and the mixed stream is heat-exchanged with the feed stream in the third heat exchanger 40 and then discharged. In addition, the operating pressure of the second tower 20 is adjusted to 1.65 kg / cm 2 .g.

[0068] The temperature T of the feed stream supplied to the first column 10 after heat exchange in the third heat exchanger 40 is in , the temperature T1 of the lower discharge stream of the first tower 10 which is refluxed to the first tower 10 after heat exchange in the first heat exchanger 11, the temperature T2 of the upper discharge stream of the second tower 20 which is refluxed to the second tower 20 after heat exchange in the first heat exchanger 11, the temperature T3 of the lower discharge stream of the second tower 20 which is refluxed to the second tower 20 after heat exchange in the second heat exchanger 21, the temperature T4 of the upper discharge stream of the first tower 10 which is refluxed to the first tower 10 after heat exchange in the second heat exchanger 21, and the temperature T5 of the mixed stream discharged after heat exchange in the third heat exchanger 40. out As shown in Table 1 below.

[0069] In addition, the amount of energy used in this process is shown in Table 2 below.

[0070] Example 3

[0071] like Figure 3 A commercial simulation tool (Aspen Plus manufactured by Aspen Corporation) was used to validate the heat-integrated separation system as shown in the process flow diagram shown.

[0072] Specifically, a feed stream containing 20 wt% of n-hexane, 40 wt% of low-boiling-point components, and 40 wt% of high-boiling-point components passes through the third heat exchanger 40 and is then supplied to the second tower 20. A portion of the lower discharge stream of the second tower 20 is supplied to the second heat exchanger 21, heat-exchanged with the upper discharge stream of the first tower 10 compressed by the compressor 30, and then refluxed to the second tower 20. The remaining stream containing the high-boiling-point components is separated and heat-exchanged with the feed stream in the third heat exchanger 40 before being discharged. In addition, the upper discharge stream of the second tower 20 is supplied to the first heat exchanger 11 to heat-exchange with a portion of the lower discharge stream of the first tower 10, and then the portion is refluxed to the second tower 20, and the remaining stream is supplied to the first tower 10. At this time, the operating pressure of the second tower 20 is adjusted to 1.25 kg / cm 2 .g.

[0073] After the upper exhaust stream of the first tower 10 is compressed in the compressor 30, supplied to the second heat exchanger 21, and heat exchanged in the second heat exchanger 21, a partial stream is refluxed to the first tower 10, and the remaining stream containing low-boiling-point components is separated, heat-exchanged with the feed stream in the third heat exchanger 40, and then discharged. In addition, a partial stream of the lower exhaust stream of the first tower 10 passes through the first heat exchanger 11, then refluxed to the first tower 10, and the product is separated from the remaining stream. At this time, the remaining stream of the upper exhaust stream of the first tower 10 that has passed through the second heat exchanger 21 and the remaining stream of the lower exhaust stream of the second tower 20 form a mixed stream, and the mixed stream is heat-exchanged with the feed stream in the third heat exchanger 40 and then discharged. In addition, the operating pressure of the first tower 10 is adjusted to 0.5 kg / cm 2 .g.

[0074] The temperature T of the feed stream supplied to the second column 20 after heat exchange in the third heat exchanger 40 is in , the temperature T1 of the lower discharge stream of the first tower 10 which is refluxed to the first tower 10 after heat exchange in the first heat exchanger 11, the temperature T2 of the upper discharge stream of the second tower 20 which is refluxed to the second tower 20 after heat exchange in the first heat exchanger 11, the temperature T3 of the lower discharge stream of the second tower 20 which is refluxed to the second tower 20 after heat exchange in the second heat exchanger 21, the temperature T4 of the upper discharge stream of the first tower 10 which is refluxed to the first tower 10 after heat exchange in the second heat exchanger 21, and the temperature T5 of the mixed stream discharged after heat exchange in the third heat exchanger 40. out As shown in Table 1 below.

[0075] In addition, the amount of energy used in this process is shown in Table 2 below.

[0076] Example 4

[0077] like Figure 4 A commercial simulation tool (Aspen Plus manufactured by Aspen Corporation) was used to validate the heat-integrated separation system as shown in the process flow diagram shown.

[0078] Specifically, a feed stream containing 20 wt% of n-hexane, 40 wt% of low-boiling-point components, and 40 wt% of high-boiling-point components passes through the third heat exchanger 40 and is then supplied to the second tower 20. A portion of the lower discharge stream of the second tower 20 is supplied to the second heat exchanger 21, heat-exchanged with the upper discharge stream of the first tower 10 compressed by the compressor 30, and then refluxed to the second tower 20, and the remaining stream is supplied to the first tower 10. In addition, the upper discharge stream of the second tower 20 is supplied to the first heat exchanger 11 to heat-exchange with a portion of the lower discharge stream of the first tower 10, and then the portion is refluxed to the second tower 20, and the remaining stream containing the low-boiling-point components is separated, heat-exchanged with the feed stream in the third heat exchanger 40, and then discharged. At this time, the operating pressure of the second tower 20 is adjusted to 1.65 kg / cm 2 .g.

[0079] After the upper discharge stream of the first tower 10 is compressed in the compressor 30, supplied to the second heat exchanger 21, and heat-exchanged in the second heat exchanger 21, a partial stream is refluxed to the first tower 10, and a product is separated from the remaining stream. In addition, a partial stream of the lower discharge stream of the first tower 10 passes through the first heat exchanger 11, then refluxed to the first tower 10, and the remaining stream containing high-boiling-point components is separated, heat-exchanged with the feed stream in the third heat exchanger 40, and then discharged. At this time, the remaining stream of the upper discharge stream of the second tower 20 that has passed through the first heat exchanger 11 and the remaining stream of the lower discharge stream of the first tower 10 form a mixed stream, and the mixed stream is heat-exchanged with the feed stream in the third heat exchanger 40 and then discharged. In addition, the operating pressure of the first tower 10 is adjusted to 0.5 kg / cm 2 .g.

[0080] The temperature T of the feed stream supplied to the second column 20 after heat exchange in the third heat exchanger 40 is in , the temperature T1 of the lower discharge stream of the first tower 10 which is refluxed to the first tower 10 after heat exchange in the first heat exchanger 11, the temperature T2 of the upper discharge stream of the second tower 20 which is refluxed to the second tower 20 after heat exchange in the first heat exchanger 11, the temperature T3 of the lower discharge stream of the second tower 20 which is refluxed to the second tower 20 after heat exchange in the second heat exchanger 21, the temperature T4 of the upper discharge stream of the first tower 10 which is refluxed to the first tower 10 after heat exchange in the second heat exchanger 21, and the temperature T5 of the mixed stream discharged after heat exchange in the third heat exchanger.out As shown in Table 1 below.

[0081] In addition, the amount of energy used in this process is shown in Table 2 below.

[0082] Comparative Example

[0083] Comparative Example 1

[0084] like Figure 5 A commercial simulation tool (Aspen Plus manufactured by Aspen Corporation) was used to validate the heat-integrated separation system as shown in the process flow diagram shown.

[0085] Specifically, a feed stream containing 20 wt% of n-hexane, 40 wt% of low-boiling-point components, and 40 wt% of high-boiling-point components is supplied to the first tower 10, a portion of the lower exhaust stream of the first tower 10 is passed through the reboiler 12 to be refluxed to the first tower 10, and the high-boiling-point components are separated from the remaining stream. In addition, after the upper exhaust stream of the first tower 10 passes through the condenser 13, a portion of the stream is refluxed to the first tower 10, and the remaining stream is supplied to the second tower 20.

[0086] The upper exhaust stream of the second column 20 passes through the condenser 23, a portion of the stream is refluxed to the second column 20, and low-boiling point components are separated from the remaining stream. In addition, a portion of the lower exhaust stream of the second column 20 passes through the reboiler 22, refluxed to the second column 20, and the product is separated from the remaining stream.

[0087] At this time, the working conditions of the first tower 10 and the second tower 20 are respectively controlled to be 0.5 kg / cm 2 .g.

[0088] In addition, the amount of energy used in this process is shown in Table 2 below.

[0089] Comparative Example 2

[0090] like Figure 6 A commercial simulation tool (Aspen Plus manufactured by Aspen Corporation) was used to validate the heat-integrated separation system as shown in the process flow diagram shown.

[0091] Specifically, a feed stream containing 20 wt% of n-hexane, 40 wt% of low-boiling-point components, and 40 wt% of high-boiling-point components is supplied to the first tower 10, and the upper exhaust stream of the first tower 10 passes through the condenser 13, and then a portion of the stream is refluxed to the first tower 10, and the low-boiling-point components are separated from the remaining stream. In addition, a portion of the lower exhaust stream of the first tower 10 passes through the reboiler 12 to reflux to the first tower 10, and the remaining stream is supplied to the second tower 20.

[0092] After the upper exhaust stream of the second column 20 passes through the condenser 23, a portion of the stream is refluxed to the second column 20, and the product is separated from the remaining stream. In addition, a portion of the lower exhaust stream of the second column 20 passes through the reboiler 22, refluxed to the second column 20, and the high boiling point component is separated from the remaining stream.

[0093] At this time, the working conditions of the first tower 10 and the second tower 20 are respectively controlled to be 0.5 kg / cm 2 .g.

[0094] In addition, the amount of energy used in this process is shown in Table 2 below.

[0095] Comparative Example 3

[0096] like Figure 7 A commercial simulation tool (Aspen Plus manufactured by Aspen Corporation) was used to validate the heat-integrated separation system as shown in the process flow diagram shown.

[0097] Specifically, Comparative Example 3 was performed in the same manner as Comparative Example 2, except that the lower exhaust stream of the first tower 10 and the upper exhaust stream of the second tower 20 were heat-exchanged in the first heat exchanger 11 in Comparative Example 2.

[0098] In addition, the amount of energy used in this process is shown in Table 2 below.

[0099] Comparative Examples 4 and 5

[0100] As a method of adjusting the flow rate of the mixed stream passing through the third heat exchanger 40 in Example 2, Comparative Examples 4 and 5 were performed in the same manner as Example 1, except that the temperature of the feed stream supplied to the first tower 10 through the third heat exchanger 40 was different.

[0101] The temperature T of the feed stream supplied to the first column 10 after heat exchange in the third heat exchanger in , the temperature T1 of the lower discharge stream of the first tower 10 which is refluxed to the first tower 10 after heat exchange in the first heat exchanger 11, the temperature T2 of the upper discharge stream of the second tower 20 which is refluxed to the second tower 20 after heat exchange in the first heat exchanger 11, the temperature T3 of the lower discharge stream of the second tower 20 which is refluxed to the second tower 20 after heat exchange in the second heat exchanger 21, the temperature T4 of the upper discharge stream of the first tower 10 which is refluxed to the first tower 10 after heat exchange in the second heat exchanger 21, and the temperature T5 of the mixed stream discharged after heat exchange in the third heat exchanger. out As shown in Table 1 below.

[0102] [Table 1]

[0103] <![CDATA[T in ]]> T1 T2 T3 T4 <![CDATA[T out ]]> Example 1 62.0 94.9 97.4 107.5 109.7 64.5 Example 2 65.0 96.0 97.2 109.9 112.1 66.8 Example 3 62.0 92.3 92.9 107.9 109.9 64.7 Example 4 63.0 94.6 97.4 112.2 117.6 68.7 Comparative Example 4 40.0 96.0 97.2 109.9 108.2 91.6 Comparative Example 5 50.0 96.0 97.2 109.9 109.8 85.3

[0104] [Table 2]

[0105]

[0106] Table 2 shows the energy consumption of each of cooling energy, heating energy, and electric energy. Specifically, in Examples 1 to 4, the amount of electric energy used in the compressor 30 was measured, and the amount of electric energy used in Example 1 was converted into a percentage and displayed. Furthermore, in Comparative Examples 1 to 3, the cooling energy and heating energy were calculated considering an electric energy conversion efficiency of approximately 30%, and the electric energy consumption in Example 1 was converted into a percentage and displayed.

[0107] Referring to Tables 1 and 2, in Examples 1 to 4, using the heat-integrated separation system according to the present invention to separate products from a feed stream reduces energy consumption and, because additional cooling and heating energy are not required, reduces carbon dioxide production. Specifically, in Example 1, it can be seen that the maximum operating temperature in this process is low and the waste heat recovery rate is high, resulting in the greatest energy savings.

[0108] In contrast, in Comparative Examples 1 and 2, waste heat was not reused through heat exchange in the process. It can be seen that energy consumption was significantly increased compared to Examples 1 to 4, and in Comparative Example 3, energy consumption was reduced by heat exchange between streams in the process compared to Comparative Examples 1 and 2, however, it was confirmed that energy consumption was still high compared to Examples 1 to 4.

[0109] Furthermore, it can be seen that in Comparative Examples 4 and 5, the heat-integrated separation system operates similarly to Examples 1 to 4, but does not satisfy the temperature condition of Formula 1, and thus cannot achieve sufficient heat exchange, requiring additional heating and cooling energy. Specifically, in Comparative Examples 4 and 5, a temperature inversion occurs between T3 and T4, resulting in insufficient thermal energy in the upper exhaust stream of the first tower 10, which is refluxed to the first tower 10 after heat exchange in the second heat exchanger 21, making heat exchange difficult.

Claims

1. A heat integration separation system comprising: First Tower; as well as The second tower, wherein the upper exhaust stream of the first tower is compressed by a compressor, and then the upper exhaust stream of the first tower is heat exchanged with the lower exhaust stream of the second tower in a second heat exchanger, The upper exhaust stream of the second tower is heat-exchanged with the lower exhaust stream of the first tower in a first heat exchanger, and Satisfies the following formula 1: [Formula 1] T1<T2<T3<T4 Wherein, T1 is the temperature of the lower discharge stream of the first tower that is returned to the first tower after heat exchange in the first heat exchanger, T2 is the temperature of the upper discharge stream of the second tower that is returned to the second tower after heat exchange in the first heat exchanger, T3 is the temperature of the lower discharge stream of the second tower that is returned to the second tower after heat exchange in the second heat exchanger, and T4 is the temperature of the upper discharge stream of the first tower that is returned to the first tower after heat exchange in the second heat exchanger.

2. The heat integration separation system according to claim 1, wherein: The first column or the second column is supplied with a feed stream comprising product, high boiling point components and low boiling point components.

3. The heat integration separation system according to claim 2, wherein: separating the low-boiling-point component from the upper effluent stream of the first column or the second column, separating the high-boiling-point component from the lower effluent stream of the first column or the second column, The stream containing the separated low-boiling point component and the stream containing the separated high-boiling point component form a mixed stream, and The mixed stream is heat exchanged with the feed stream in a third heat exchanger.

4. The heat integrated separation system according to claim 3, wherein: After heat exchange in the third heat exchanger, the temperature difference between the mixed stream and the feed stream is 0.1°C to 10°C.

5. The heat integrated separation system according to claim 2, wherein: The feed stream is supplied to the first column, separating the high boiling point component from the lower effluent stream of the first column, separating the low-boiling-point components from the upper effluent stream of the second column, and The product is separated from the lower effluent stream of the second column.

6. The heat integrated separation system according to claim 2, wherein: The feed stream is supplied to the first column, separating the low-boiling-point component from the upper effluent stream of the first column, separating the product from the upper effluent stream of the second column, and The high boiling point components are separated from the lower effluent stream of the second column.

7. The heat integrated separation system according to claim 2, wherein: The feed stream is supplied to the second column, separating the high boiling point component from the lower effluent stream of the second column, separating the low-boiling-point components from the upper effluent stream of the first column, and The product is separated from the lower effluent stream of the first column.

8. The heat integrated separation system according to claim 2, wherein: The feed stream is supplied to the second column, separating the low-boiling-point component from the upper effluent stream of the second column, separating the product from the upper effluent stream of the first column, and The high boiling point components are separated from the lower effluent stream of the first column.

9. The heat-integrated separation system according to claim 1, wherein: The working pressure of the first tower is 0.5 kg / cm lower than that of the second tower. 2 .g to 1.5kg / cm 2 .g.

10. The heat integrated separation system according to claim 1, wherein: The differences between T1 and T2 and between T3 and T4 are 0.1°C to 6°C, respectively.

11. The heat-integrated separation system according to claim 1, wherein: The difference between T1 and T2 is 0.1℃ to 3℃.

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