Separation apparatus, and method for separating ethylene and propylene

Abstract

The present invention aims to provide a separation apparatus that can relatively improve the purity of ethylene and propylene while relatively reducing the amount of coolant used, as well as a method for separating ethylene and propylene. [Solution] The separation apparatus according to the present invention is a separation apparatus for separating ethylene and propylene from a gas composition containing ethylene, propylene, water and an organic compound, and has a gas-liquid contact region in which the gas composition and a water-absorbing coolant are supplied from opposite directions and brought into countercurrent contact, and has a first separation unit that separates the gas composition into a gas component (A) containing ethylene and propylene and a liquid component (B) containing water, an organic compound and a water-absorbing coolant by countercurrent contact, and has a first return path that returns at least a portion of the liquid component (B) to an intermediate flow region between the upstream end and the downstream end in the flow direction of the water-absorbing coolant in the gas-liquid contact region, and a first cooling unit is interposed in the first return path to cool the returned liquid component (B).

Description

Technical Field

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[0001] The present invention relates to a separation device and a method for separating ethylene and propylene.

Background Art

[0002] Olefins such as ethylene and propylene are one of the main products in the petrochemical industry. Resins made from these olefins are widely used, and there is a need for technology that can produce these olefins efficiently.

[0003] In recent years, technology for producing olefins such as ethylene and propylene from alcohols such as ethanol has been studied. For example, Patent Document 1 discloses a technology for obtaining ethylene and propylene by contacting ethanol with a catalyst and subjecting the resulting product mixture to gas-liquid separation in a cooling tower.

[0004] In the above cooling tower, the mixture is cooled by spraying a coolant onto the mixture. As the mixture is cooled and the high-boiling components are liquefied, the high-boiling components are absorbed by the coolant, thereby separating ethylene and propylene from the mixture.

Prior Art Documents

Patent Documents

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in a separation device including a cooling tower as described above, a considerable amount of coolant needs to be used. Also, in this type of separation device, it is difficult to separate ethylene and propylene while efficiently removing organic compounds other than ethylene and propylene.

[0007] Therefore, the object of the present invention is to provide a separation apparatus that can relatively improve the purity of ethylene and propylene while relatively reducing the amount of coolant used, as well as a method for separating ethylene and propylene. [Means for solving the problem]

[0008] The separation apparatus according to the present invention is A separation apparatus for separating ethylene and propylene from a gas composition containing ethylene, propylene, water, and organic compounds other than ethylene and propylene, The apparatus has a gas-liquid contact region in which the gas composition and the water-absorbing coolant are supplied from opposite directions to bring them into countercurrent contact, and the apparatus includes a first separation unit which separates the gas composition into a gas component (A) containing ethylene and propylene, and a liquid component (B) containing water, the organic compound, and the water-absorbing coolant. The system has a first return path that returns at least a portion of the liquid component (B) to an intermediate flow region between the upstream and downstream ends in the flow direction of the water-absorbing coolant in the gas-liquid contact region, The first return route includes a first cooling unit for cooling the liquid component (B) being returned.

[0009] The method for separating ethylene and propylene according to the present invention is: The aforementioned separation device is used. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a separation apparatus that can relatively improve the purity of ethylene and propylene while relatively reducing the amount of coolant used, as well as a method for separating ethylene and propylene. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic diagram showing the separation device 1 according to this embodiment. [Figure 2] Figure 2 is a schematic diagram showing the separation apparatus 1 in Example 1. [Figure 3] Figure 3 is a schematic diagram showing the separation apparatus 1 in Example 2. [Figure 4] Figure 4 is a schematic diagram showing the separation apparatus 1 in Example 3. [Figure 5] Figure 5 is a schematic diagram showing the separation apparatus 1' in Comparative Example 1. [Figure 6] Figure 6 is a schematic diagram showing the separation apparatus 1' in Comparative Example 2. [Figure 7] Figure 7 is a schematic diagram showing the separation apparatus 1' in Comparative Example 3. [Modes for carrying out the invention]

[0012] [Separation device] The following description will refer to the drawings and explain the separation device 1 according to an embodiment of the present invention. The present invention is not limited to the following embodiments.

[0013] The separation apparatus 1 according to this embodiment separates ethylene and propylene from a gas composition containing ethylene, propylene, water, and organic compounds other than ethylene and propylene. As shown in Figure 1, the separation apparatus 1 according to this embodiment comprises a first separation unit 2 and a second separation unit 3. Also, as shown in Figure 1, the separation apparatus 1 according to this embodiment has a first return path 4 and a second return path 5.

[0014] (1st separation section) The first separation unit 2 has a gas-liquid contact region 21 in which the gas composition and the water-absorbing coolant are supplied from opposite directions to bring them into countercurrent contact. For example, in the gas-liquid contact region 21, the gas composition may rise from vertically downward to vertically upward, and the water-absorbing coolant may descend from vertically upward to vertically downward, thereby bringing the gas composition and the water-absorbing coolant into countercurrent contact.

[0015] The first separation unit 2 separates the gas composition into a gas component (A) containing ethylene and propylene and a liquid component (B) containing water, the organic compound, and the water absorption cooling liquid by the countercurrent contact.

[0016] In the first separation unit 2, substances such as water contained in the gas composition are absorbed by the water absorption cooling liquid, and the gas composition and the water absorption cooling liquid come into contact with each other, causing the temperature of the gas composition to decrease, and high-boiling components contained in the gas composition to liquefy. As a result, in the first separation unit 2, the gas composition can be separated into the gas component (A) and the liquid component (B). The liquid component (B) separated in the first separation unit 2 is supplied to a second separation unit 3 described later.

[0017] The gas composition is a reaction product obtained by bringing a raw material containing alcohol into contact with a catalyst. The alcohol may be ethanol.

[0018] The gas composition contains water, ethylene, propylene, and the organic compound. The gas composition preferably further contains an oxygen-containing compound described later as the organic compound.

[0019] The water absorption cooling liquid is a liquid for cooling the gas composition. Examples of the water absorption cooling liquid include water such as normal-temperature water (for example, water at 23°C), cooling water below normal temperature, and component (D) described later. The water absorption cooling liquid may be water, cooling water, at least a part of component (D), or all of component (D). Further, the water absorption cooling liquid may be at least a part of component (D), or at least a part of component (D) and water, or at least a part of component (D), or at least a part of component (D) and cooling water.

[0020] In the first separation unit 2, since the water-absorbing coolant is water, it is possible to absorb the water contained in the gas composition without absorbing the ethylene and propylene contained in the gas composition, and to cool the gas composition and separate the substances contained in the gas composition into gas and liquid, thereby enabling efficient separation of ethylene and propylene from the gas composition. Furthermore, in the first separation unit 2, since the water-absorbing coolant is cooling water, gas and liquid separation is further promoted, and ethylene and propylene can be separated from the gas composition even more efficiently. In the first separation unit 2, since the water-absorbing coolant is component (D), the amount of coolant used can be further reduced.

[0021] The gas component (A) includes ethylene and propylene. The gas component (A) may further include paraffin, an olefin having 4 or more carbon atoms, carbon dioxide, carbon monoxide, or hydrogen. Examples of olefins having 4 or more carbon atoms include butene, pentene, and hexene.

[0022] The liquid component (B) comprises water, the organic compound, and the water-absorbing coolant. If the water-absorbing coolant is water, the liquid component (B) comprises water and the organic compound.

[0023] As stated above, the organic compound does not contain ethylene and propylene. The organic compound may also be an oxygen-containing compound. The oxygen-containing compound is an organic compound having an oxygen atom in its molecule. Examples of the oxygen-containing compound include acetone, 2-propanol, and ethanol. The oxygen-containing compound is preferably acetone.

[0024] As described above, the gas-liquid contact region 21 is a region in which the gas composition and the water-absorbing coolant are supplied from opposite directions to bring them into countercurrent contact.

[0025] The gas-liquid contact region 21 has an intermediate flow region between the upstream end and the downstream end in the flow direction of the water-absorbing coolant within the gas-liquid contact region 21. If the first separation unit 2 is composed of a plurality of separators for separating the gas composition into the gas component (A) and the liquid component (B), the plurality of separators constitute the gas-liquid contact region 21 as a whole. Therefore, the intermediate flow region is the flow region between the upstream end of the separator located on the upstream side in the flow direction and the downstream end of the separator located on the downstream side in the flow direction.

[0026] The aforementioned intermediate basin comprises a low-temperature basin, a medium-temperature basin, and a high-temperature basin. These basins are arranged in the order of low-temperature basin, medium-temperature basin, and high-temperature basin along the flow direction of the water-absorbing coolant.

[0027] The temperature in the low-temperature region may be between 20°C and 60°C, between 30°C and 50°C, or between 35°C and 45°C.

[0028] The temperature in the intermediate-temperature region may be, for example, higher than the temperature in the low-temperature region and lower than the temperature in the high-temperature region described later. The temperature in the intermediate-temperature region may be between 20°C and 135°C, between 35°C and 110°C, or between 40°C and 80°C.

[0029] The temperature in the high-temperature region may be between 40°C and 150°C, between 80°C and 145°C, or between 90°C and 135°C.

[0030] The temperatures in the low-temperature, medium-temperature, and high-temperature watersheds are the temperatures of the gases present in each watershed. These temperatures are measured using thermocouples or thermometers installed in each watershed.

[0031] As shown in Figure 1, the gas-liquid contact region 21 according to this embodiment includes two contact mechanisms 22 that increase the opportunities for contact between the gas composition and the water-absorbing coolant.

[0032] Examples of the contact mechanism 22 include a filling mechanism that uses a packing material to disperse the flow paths of the gas composition and the water-absorbing coolant, and a shelf mechanism configured such that the gas composition passes through the water-absorbing coolant by bubbling. The contact mechanism 22 is preferably a filling mechanism or a shelf mechanism.

[0033] The gas-liquid contact region 21 is equipped with a contact mechanism 22, which makes it possible to further reduce the amount of coolant used. Furthermore, if the contact mechanism 22 is a filling mechanism or a shelf mechanism, it is possible to further reduce the amount of coolant used.

[0034] The gas composition may be supplied to the downstream side in the flow direction of the water-absorbing coolant in the gas-liquid contact region 21, or it may be supplied to the high-temperature flow region.

[0035] The location where the water-absorbing coolant is supplied is the low-temperature flow region.

[0036] The first separation section 2 may be a packed column or a tray column. The packed column is a separator having the packing mechanism. The tray column is a separator having the tray mechanism.

[0037] Since the first separation section 2 is a packed tower or a tray tower, the amount of coolant used can be further reduced.

[0038] In one embodiment, the separation apparatus 1 according to this embodiment has a gas-liquid contact region 21 in which the first separation unit 2 supplies the gas composition and the water-absorbing coolant from opposite directions to bring them into countercurrent contact, and by the countercurrent contact, separates the gas composition into a gas component (A) containing ethylene and propylene, and a liquid component (B) containing water, the organic compound and the water-absorbing coolant.

[0039] (First return route) The first return path 4 returns at least a portion of the liquid component (B) to an intermediate flow region between the upstream and downstream ends in the flow direction of the water-absorbing coolant in the gas-liquid contact region 21. Preferably, the first return path 4 returns at least a portion of the liquid component (B) to the medium-temperature flow region.

[0040] By returning at least a portion of the liquid component (B) to the intermediate flow region, the separation apparatus 1 according to this embodiment can reduce the amount of coolant used, and the gas component (A) in the intermediate flow region is cooled, causing the organic compound in the liquid component (B) to preferentially absorb substances other than ethylene and propylene, such as organic compounds and alcohols, which are abundant in the intermediate flow region, over ethylene and propylene, thus efficiently improving the purity of ethylene and propylene. Furthermore, by returning at least a portion of the liquid component (B) to the medium-temperature flow region, the separation apparatus 1 according to this embodiment can further reduce the amount of coolant used, and in the low-temperature flow region where the concentrations of ethylene and propylene are high, the coolant containing organic solvents can avoid absorbing ethylene and propylene, thus efficiently improving the purity of ethylene and propylene.

[0041] In the separation apparatus 1 according to this embodiment, a first cooling unit 6 is provided in the first return path 4 to cool the liquid component (B) that is being returned.

[0042] By interposing the first cooling unit 6 in the first return path 4, the separation device 1 according to this embodiment can further promote the gas-liquid separation of the gas composition and further reduce the amount of coolant used.

[0043] The first cooling unit 6 may have a refrigerant. Examples of the refrigerant include cooling water and an aqueous solution of ethylene glycol. The refrigerant is preferably cooling water.

[0044] The first cooling unit 6 may cool the liquid component (B) by heat exchange with other processes in the process.

[0045] (Second separation section) The second separation unit 3 separates the liquid component (B) into a component (C) containing the organic compound and a component (D) containing water.

[0046] The component (C) comprises the organic compound. The component (C) may further contain carbon dioxide, carbon monoxide, or hydrogen. The component (C) may contain water. If the component (C) contains water, the amount of water contained in the component (C) is less than the amount of water contained in the component (D).

[0047] The component (D) contains water. The component (D) may further contain the organic compound. If the component (D) contains the organic compound, the amount of the organic compound contained in the component (D) is less than the amount of the organic compound contained in the component (C).

[0048] The water content in component (D) is preferably 85% by mass or more, more preferably 95% by mass or more, and even more preferably 99% by mass or more. It is preferable that component (D) consists substantially of water alone.

[0049] (Second return route) The second return route 5 returns at least a portion of the component (D) to the first separation unit 2 as the water-absorbing coolant.

[0050] By returning at least a portion of component (D) to the first separation unit 2 as the water-absorbing coolant, the separation device 1 according to this embodiment can further reduce the amount of coolant used and sufficiently cool the gas composition, thereby efficiently separating the gas composition into gas component (A) and liquid component (B) to obtain high-purity ethylene and propylene.

[0051] In one embodiment, the separation device 1 includes a second separation unit that separates the liquid component (B) into a component (C) containing the organic compound and a component (D) containing water, wherein the water-absorbing coolant is at least a part of the component (D), and the device has a second return path that returns at least a part of the component (D) as the water-absorbing coolant to the first separation unit, and a second cooling unit is interposed in the second return path to cool the returned component (D).

[0052] Furthermore, if the water content in component (D) is 85% by mass or more, the separation device 1 according to this embodiment can avoid the absorption of ethylene and propylene by component (D) in the first separation unit 2, thereby further suppressing the reduction in the yield of ethylene and propylene.

[0053] In the separation device 1 according to this embodiment, a second cooling unit 7 is provided in the second return path 5 to cool the component (D) that is being returned.

[0054] Because the second cooling unit 7 is interposed in the second return path 5, the separation device 1 according to this embodiment can further promote the gas-liquid separation of the gas composition and further reduce the amount of coolant used.

[0055] The second cooling unit 7 may have a refrigerant. Examples of the refrigerant include cooling water and an aqueous solution of ethylene glycol. The refrigerant is preferably cooling water.

[0056] The second cooling unit 7 may cool the component (D) by heat exchange with other processes in the process.

[0057] In one embodiment of the separation device 1 according to this embodiment, the first cooling unit 6 and the second cooling unit 7 each have a refrigerant, and the refrigerant is cooling water.

[0058] The separation apparatus 1 according to this embodiment, when implemented in the manner described above, can relatively reduce the amount of coolant used while relatively improving the purity of ethylene and propylene.

[0059] [Method for separating ethylene and propylene] The following describes a method for separating ethylene and propylene according to embodiments of the present invention. The present invention is not limited to the following embodiments.

[0060] The separation method for ethylene and propylene according to this embodiment uses the separation apparatus 1 described above.

[0061] The method for separating ethylene and propylene according to this embodiment may include a first separation step in which a gas composition containing ethylene, propylene, water, and organic compounds other than ethylene and propylene is supplied to a water-absorbing coolant from opposite directions to cause countercurrent contact, and the gas composition is separated by the countercurrent contact into a gas component (A) containing ethylene and propylene, and a liquid component (B) containing water, the organic compounds, and the water-absorbing coolant.

[0062] The method for separating ethylene and propylene according to this embodiment may include a first return step of returning at least a portion of the liquid component (B) to the first separation step.

[0063] In the first return process, the liquid component (B) being returned may be cooled.

[0064] The method for separating ethylene and propylene according to this embodiment may include a second separation step of separating the liquid component (B) into a component (C) containing the organic compound and a component (D) containing water.

[0065] The method for separating ethylene and propylene according to this embodiment may include a second return step of returning at least a portion of the component (D) to the first separation step.

[0066] In the second return process, the component (D) being returned may be cooled.

[0067] The method for separating ethylene and propylene according to this embodiment, when implemented in the manner described above, can relatively reduce the amount of coolant used while relatively improving the purity of ethylene and propylene.

[0068] The present invention includes the following embodiments.

[0069] [1] A separation apparatus for separating ethylene and propylene from a gas composition containing ethylene, propylene, water, and organic compounds other than ethylene and propylene, The apparatus has a gas-liquid contact region in which the gas composition and the water-absorbing coolant are supplied from opposite directions to bring them into countercurrent contact, and the apparatus includes a first separation unit which separates the gas composition into a gas component (A) containing ethylene and propylene, and a liquid component (B) containing water, the organic compound, and the water-absorbing coolant. The system has a first return path that returns at least a portion of the liquid component (B) to an intermediate flow region between the upstream and downstream ends in the flow direction of the water-absorbing coolant in the gas-liquid contact region, The first return path 4 is provided with a first cooling unit for cooling the liquid component (B) being returned. Separation device. [2] The system includes a second separation unit that separates the liquid component (B) into a component (C) containing the organic compound and a component (D) containing water. The water-absorbing coolant is at least a part of the component (D), The system has a second return path that returns at least a portion of the aforementioned component (D) to the first separation unit as the water-absorbing coolant, The second return path is provided with a second cooling unit for cooling the component (D) being returned. [1] The separation apparatus described above. [3] The gas composition is supplied to the downstream side in the flow direction of the water-absorbing coolant in the gas-liquid contact region. The separation apparatus described in [1] or [2]. [4] The first separation section is a packed tower or a tray tower. A separation device as described in any one of [1] to [3]. [5] The aforementioned organic compound is an oxygen-containing compound. A separation device as described in any one of [1] to [4]. [6] The oxygen-containing compound is acetone. [5] The separation apparatus described above. [7] The first cooling unit and the second cooling unit have a refrigerant, The refrigerant is cooling water. [2] The separation apparatus described above. [8] The water content in component (D) is 85% by mass or more. [2] The separation apparatus described above. [9] Use the separation device described in any one of [1] to [8]. A method for separating ethylene and propylene.

[0070] It should be noted that the separation apparatus and the method for separating ethylene and propylene according to the present invention are not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the present invention. Furthermore, configurations, methods, etc., of embodiments other than those described above may be arbitrarily adopted and combined.

[0071] The separation device 1 according to the above embodiment comprises a first separation unit 2 and a second separation unit 3. However, the separation device according to the present invention is not limited thereto, and may not include the second separation unit.

[0072] The separation device 1 according to the above embodiment has a first return path 4 and a second return path 5. However, the separation device according to the present invention is not limited thereto and may not have a second return path.

[0073] In the above embodiment, the separation device 1 has two contact mechanisms 22 in the gas-liquid contact area 21. However, the separation device according to the present invention is not limited thereto, and the number of contact mechanisms may be one, three or more, and the gas-liquid contact area may not have any contact mechanisms. [Examples]

[0074] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0075] In Examples 1-3 and Comparative Examples 1-3, the distribution of compounds in the separation column corresponding to the first separation section was calculated using the process simulator ASPEN to determine the acetone loss rate and the amount of heat removed in addition to that removed by process heat exchange.

[0076] The acetone loss rate was calculated using equation (1).

[0077] Acetone loss rate (%) = (Amount of acetone contained in the gas discharged from the top of the separation column (unit: t / hour)) / (Amount of acetone contained in the gas composition (unit: t / hour)) × 100 ... (1)

[0078] (Example 1) In Example 1, a simulation was performed using the apparatus 1 shown in Figure 2. A gas composition containing ethylene, propylene, water, and acetone is supplied at 135°C to the separation tower 2, which serves as the first separation section 2. Water, as the water absorption coolant, is supplied to the upper part of the separation tower 2, i.e., upstream of the contact mechanism 22 located at the uppermost point in the flow direction of the water absorption coolant. Liquid component (B) is returned to the middle part of the separation tower 2, i.e., between the two contact mechanisms 22. By bringing the water, as the water absorption coolant, into contact with liquid component (B), gas component (A) and acetone are separated from the gas composition.

[0079] The water supplied to the upper section of separation tower 2 is cooled to 40°C by cooling water at a flow rate of 120 t / h. The liquid component (B) returned to the middle section of separation tower 2 is cooled to 60°C in the first cooling section 6' by heat exchange with other processes in the process (hereinafter referred to as process heat exchange), and then cooled to 40°C by cooling water in the first cooling section 6. A portion of the liquid component (B) is supplied to the acetone recovery tower 3, which corresponds to the second separation section 3, and is separated into a component containing acetone (C) and a component containing water (D).

[0080] (Example 2) In Example 2, the simulation was performed under the same conditions as in Example 1, except that the apparatus 1 shown in Figure 3 was used, water was used as the water absorption coolant supplied to the upper stage of the separation tower 2 as component (D), the flow rate of component (D) was set to 120 t / h, and component (D) was cooled to 40°C by cooling water in the second cooling section 7.

[0081] (Example 3) In Example 3, the apparatus 1 shown in Figure 4 was used, and the simulation was performed under the same conditions as in Example 2, except that the liquid component (B) returned to the middle section of the separation tower 2 was not cooled by process heat exchange in the first cooling section 6', but was cooled to 40°C with cooling water in the first cooling section 6.

[0082] (Comparative Example 1) In Comparative Example 1, the simulation was performed under the same conditions as in Example 1, except that the apparatus 1' shown in Figure 5 was used, and the liquid component (B) was returned to the upper stage of separation tower 2, i.e., the position where the water absorption coolant is supplied.

[0083] (Comparative Example 2) In Comparative Example 2, the simulation was performed under the same conditions as in Comparative Example 1, except that the apparatus 1' shown in Figure 6 was used, water was used as the water absorption coolant supplied to the separation tower 2 as component (D), the flow rate of component (D) was set to 120 t / h, and component (D) was supplied to a position downstream of the first cooling section 6' and upstream of the first cooling section 6 in the path for returning the liquid component (B) to the separation tower 2.

[0084] (Comparative Example 3) In Comparative Example 3, the simulation was performed under the same conditions as in Comparative Example 1, except that the apparatus 1' shown in Figure 7 was used, and the liquid component (B) returned to the upper stage of the separation column 2 was not cooled by process heat exchange in the first cooling section 6', but was cooled to 40°C with cooling water in the first cooling section 6.

[0085] Table 1 shows the acetone loss rate for each example and comparative example, and the amount of heat removal required other than by process heat exchange.

[0086] [Table 1]

[0087] As can be seen from Table 1, each embodiment that satisfies the constituent elements of the present invention yields better results in terms of acetone loss rate than each comparative example. In other words, each embodiment contains almost no acetone in gas component (A) and the purity of ethylene and propylene in gas component (A) is better than that of each comparative example.

[0088] Table 1 shows that in Examples 1 and 2, which are cooled by process heat recovery, the required heat removal amount is lower compared to Example 3, which does not include process heat recovery. Furthermore, Examples 1-3 and Figures 2-3 show that the amount of water used is reduced by an amount corresponding to the amount of component (D) used as the water-absorbing coolant, indicating that the amount of coolant can be reduced by using component (D) as the water-absorbing coolant.

[0089] From the above, it can be seen that the present invention provides a method for producing propylene that can relatively reduce the amount of coolant used while relatively improving the purity of ethylene and propylene. [Explanation of Symbols]

[0090] 1 Separation device 2 1st separation section 21 Gas-liquid contact area 22 Contact mechanism 3 Second separation section 4. First return route 5. Second return route 6 1st cooling section 7 Second cooling section

Claims

1. A separation apparatus for separating ethylene and propylene from a gas composition containing ethylene, propylene, water, and organic compounds other than ethylene and propylene, The apparatus has a gas-liquid contact region in which the gas composition and the water-absorbing coolant are supplied from opposite directions to bring them into countercurrent contact, and a first separation unit that separates the gas composition into a gas component (A) containing ethylene and propylene, and a liquid component (B) containing water, the organic compound and the water-absorbing coolant, The system has a first return path that returns at least a portion of the liquid component (B) to an intermediate flow region between the upstream and downstream ends in the flow direction of the water-absorbing coolant in the gas-liquid contact region. The first return path is provided with a first cooling unit for cooling the liquid component (B) being returned. Separation device.

2. The system includes a second separation unit that separates the liquid component (B) into a component (C) containing the organic compound and a component (D) containing water. The water-absorbing coolant is at least a part of the component (D), The system has a second return path that returns at least a portion of the aforementioned component (D) to the first separation unit as the water-absorbing coolant, The second return path is provided with a second cooling unit for cooling the component (D) being returned. The separation apparatus according to claim 1.

3. The gas composition is supplied to the downstream side in the flow direction of the water-absorbing coolant in the gas-liquid contact region. The separation apparatus according to claim 1 or 2.

4. The first separation section is a packed tower or a tray tower. The separation apparatus according to claim 1 or 2.

5. The aforementioned organic compound is an oxygen-containing compound. The separation apparatus according to claim 1 or 2.

6. The oxygen-containing compound is acetone. The separation apparatus according to claim 5.

7. The first cooling unit and the second cooling unit have a refrigerant, The refrigerant is cooling water. The separation apparatus according to claim 2.

8. The water content in component (D) is 85% by mass or more. The separation apparatus according to claim 2.

9. Using the separation apparatus described in claim 1 or 2, A method for separating ethylene and propylene.

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