A flash evaporation and post-cooling separation system for ethylene polymerization to produce alpha-olefins

Abstract

The present invention relates to a flash after-cooling separation system for preparing alpha-olefin reaction products by ethylene polymerization, comprising a flash tank, a flash after-cooler and an ethylene liquid separator. Wherein, the fourth inlet of the ethylene liquid separator is connected to the third outlet of the flash after-cooler; the fourth outlet of the ethylene liquid separator is connected to the recovery liquid inlet of the flash tank through a first pipeline; the first pipeline comprises a first branch pipe, a second branch pipe and an inverted U-shaped liquid seal pipe between the first branch pipe and the second branch pipe that are interconnected. The present invention also relates to a method for separating the reaction products of ethylene polymerization to prepare alpha-olefin using the flash after-cooling separation system as described above. The present invention sets a flash gas phase after-cooling separation system for the reaction product, which can increase the ethylene concentration of the flash gas phase in the reaction product, while effectively utilizing the gas-liquid separation effect, recovering ethylene for recycling, and the combined structure of the after-cooler and the liquid separator can reduce the floor space.

Description

Technical Field

[0001] The invention relates to a flash evaporation followed by cold separation technology for reaction products, and more specifically to a flash evaporation followed by cold separation system and a separation method for ethylene polymerization to prepare alpha-olefin reaction products. Background Art

[0002] In the production process of ethylene polymerization to prepare α-olefins, the reaction products of ethylene polymerization to prepare α-olefins contain unreacted ethylene. The reaction products with higher pressure are flashed out by reduced pressure in a flash tank to remove the unreacted ethylene, which is then sent to a compressor to increase the pressure and be recycled for reuse. The liquid phase reaction products at the bottom of the flash tank enter the rear system for separation to obtain α-olefin products.

[0003] During the process of ethylene polymerization product entering the ethylene flash tank under reduced pressure, the flash gas phase contains unreacted ethylene. Due to the high temperature of the flash gas phase, the saturated gas phase contains more heavy components, which reduces the concentration of recovered ethylene and affects the operation of the reaction system. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art, the object of the present invention is to provide a flash evaporation and post-cooling separation system and a separation method for the reaction products of ethylene polymerization to prepare α-olefins.

[0005] Based on the above purpose, the following technical solutions are adopted:

[0006] According to the present invention, there is provided a flash evaporation and post-cooling separation system for preparing alpha-olefin reaction products by ethylene polymerization, comprising:

[0007] A flash tank, the flash tank comprising a first outlet arranged at the top of the flash tank, a second outlet arranged at the bottom of the flash tank, and a recovery liquid inlet arranged at the side of the flash tank;

[0008] A flash aftercooler and an ethylene separator tank, wherein the ethylene separator tank comprises a fourth inlet disposed at the top of the ethylene separator tank and a fourth outlet disposed at the bottom of the ethylene separator tank; wherein the bottom of the flash aftercooler is connected to the fourth inlet of the ethylene separator tank;

[0009] The first outlet at the top of the flash tank is connected to the top or bottom of the flash aftercooler;

[0010] The fourth outlet of the ethylene liquid separator is connected to the recovery liquid inlet of the flash tank through the first pipeline; the first pipeline comprises a first branch pipe, a second branch pipe and an inverted U-shaped liquid seal pipe between the first branch pipe and the second branch pipe, the first branch pipe is connected to the fourth outlet, and the second branch pipe is connected to the recovery liquid inlet; wherein the fourth outlet of the ethylene liquid separator is located above the recovery liquid inlet of the flash tank in the height direction; the first branch pipe is provided with a first valve for controlling the connection and closing of the pipeline.

[0011] Furthermore, the ethylene liquid separation tank also includes an opening arranged on its side, and the opening is connected to the inverted U-shaped liquid sealing pipe through a siphon breaking valve to balance the pressure between the ethylene liquid separation tank and the inverted U-shaped liquid sealing pipe.

[0012] Furthermore, the first branch pipe and the second branch pipe are directly connected through a third branch pipe, and the third branch pipe is provided with a second valve for controlling the connection and closing of the pipeline.

[0013] Furthermore, the first branch pipe is connected to a second pipeline at a position closer to the fourth outlet at the bottom of the ethylene separator relative to the first valve. The second pipeline is provided with a third valve and connected to a flash liquid phase pipeline at the second outlet at the bottom of the flash tank.

[0014] Furthermore, the flash aftercooler includes a third opening arranged at the top of the flash aftercooler and a third outlet arranged at the bottom of the flash aftercooler; the first outlet at the top of the flash tank is connected to the third opening at the top of the flash aftercooler, and a gas phase outlet is arranged on the side of the ethylene separator tank to output ethylene gas.

[0015] Furthermore, a baffle is provided at the gas phase outlet in the ethylene separator tank to prevent liquid from being discharged from the gas phase outlet.

[0016] Furthermore, the flash aftercooler comprises a third opening arranged at the top of the flash aftercooler and a third outlet arranged at the bottom of the flash aftercooler; the first outlet at the top of the flash tank is connected to the third outlet at the bottom of the flash aftercooler, and the third opening at the top of the flash aftercooler allows ethylene gas to be output.

[0017] Furthermore, a mesh-shaped anti-mist entrainment component is provided at the third opening at the top of the flash aftercooler to prevent liquid from being discharged from the third opening.

[0018] Furthermore, a heating device is arranged outside the flash tank, and the heating device is selected from one of a tank external coil heating device, a tank external half-pipe heating device and a tank external jacket heating device.

[0019] Furthermore, the flash aftercooler and the ethylene separator are arranged separately.

[0020] According to the present invention, there is also provided a method for separating the reaction product of preparing α-olefins by polymerization of ethylene using the flash distillation and post-cooling separation system as described above, comprising the following steps:

[0021] 1) The reaction product is flashed at reduced pressure in a flash tank to obtain a flash gas phase component and a flash liquid phase component; the flash liquid phase component is discharged from the second outlet at the bottom of the flash tank to a flash liquid phase pipeline;

[0022] 2) The flash gas phase component containing the heavy component is discharged from the first outlet at the top of the flash tank and enters the flash aftercooler from the third opening at the top of the flash aftercooler for cooling and condensation;

[0023] 3) Subsequently, the gas-liquid mixed components obtained in step 2) enter the ethylene separator tank for gas-liquid separation, and the unreacted ethylene is sent to the compressor for recycling from the gas phase outlet of the ethylene separator tank, and the liquid phase heavy components flow back to the flash tank from the fourth outlet at the bottom of the ethylene separator tank by gravity or enter the flash liquid phase pipeline at the bottom of the flash tank.

[0024] According to the present invention, there is also provided a method for separating the reaction product of preparing α-olefins by polymerization of ethylene using the flash distillation and post-cooling separation system as described above, comprising the following steps:

[0025] 1) The reaction product is flashed at reduced pressure in a flash tank to obtain a flash gas phase component and a flash liquid phase component; the flash liquid phase component is discharged from the second outlet at the bottom of the flash tank to a flash liquid phase pipeline;

[0026] 2) The flash gas phase components containing the heavy components are discharged from the first outlet at the top of the flash tank and enter the flash aftercooler from the bottom of the flash aftercooler for cooling and condensation;

[0027] 3) Subsequently, the gas-liquid mixed components obtained in step 2) enter the ethylene separator tank for gas-liquid separation, and the unreacted ethylene is sent to the compressor for recycling from the third opening at the top of the flash aftercooler, and the liquid phase heavy components flow back to the flash tank from the fourth outlet at the bottom of the ethylene separator tank by gravity or enter the flash liquid phase pipeline at the bottom of the flash tank.

[0028] Beneficial effects of the present invention:

[0029] The flash aftercooling separation system and separation method of the ethylene polymerization reaction product for preparing alpha-olefins can solve the problem that the flash gas phase contains a lot of heavy components and affects the operation of the compressor. The aftercooler and the liquid separator are combined in the same device, the materials are fully separated, the equipment floor space is reduced, and the device construction investment is saved. If the site conditions do not allow the combination, horizontal or vertical equipment can be used for separate arrangement. The above system and method can be applied to the production of ethylene polymerization to prepare alpha-olefins. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the drawings required for use in the embodiment will be briefly introduced below. Obviously, the drawings described below are only some implementation cases of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 is a schematic diagram of a system according to Embodiment 1 of the present invention;

[0032] Figure 2 It is a schematic diagram of a system according to Embodiment 2 of the present invention.

[0033] Reference numerals list

[0034] 1-flash tank; 11-first outlet; 12-second outlet; 13-recovery liquid inlet; 14-tank external coil heating device; 2-flash aftercooler; 21-third opening; 22-third outlet; 23-anti-foam entrainment component; 3-ethylene liquid separator; 31-fourth inlet; 32-fourth outlet; 33-opening; 34-gas phase outlet; 35-baffle; 36-gas-liquid mixed inlet; 41-first branch pipe; 42-inverted U-shaped liquid seal pipe; 43-second branch pipe; 44-first valve; 45-siphon breaking valve; 46-third branch pipe; 47-second valve; 51-second pipeline; 52-third valve; 61-flash liquid phase pipeline; 62-fourth valve; 71-ethylene output pipeline; 72-fifth valve. DETAILED DESCRIPTION

[0035] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0036] Example 1

[0037] like Figure 1 FIG. 1 shows a flash aftercooling separation system for preparing α-olefin reaction products by ethylene polymerization. The system comprises a flash tank 1, a flash aftercooler 2 and an ethylene liquid separator 3. Figure 1 The flash gas phase shown enters the flash aftercooler 2 and the ethylene separator 3 of the combined structure, enters from the top of the aftercooler and the ethylene gas phase is discharged from the ethylene separator 3, so as to achieve the cooling and separation effect.

[0038] The equipment structure of the ethylene separator 3, the aftercooler and the separator can be combined in the same equipment (such as Figure 1 The aftercooler and the liquid separator are combined in the same device to reduce the floor space and facilitate the layout of the device. In another preferred embodiment, the aftercooler and the liquid separator are arranged separately, and the two devices can also be arranged separately vertically or horizontally (not shown). The use of the aftercooler and the liquid separator can effectively separate the unreacted ethylene in the reaction product.

[0039] The flash tank 1 comprises a first outlet 11 arranged at the top of the flash tank 1, a second outlet 12 arranged at the bottom of the flash tank 1 and a recovery liquid inlet 13 arranged at the side of the flash tank 1; a heating device is arranged outside the flash tank 1, and the heating device is an external tank coil heating device 14, such as Figure 1 shown.

[0040] The flash aftercooler 2 comprises a third opening 21 disposed at the top of the flash aftercooler 2 and a third outlet 22 disposed at the bottom of the flash aftercooler 2;

[0041] The ethylene separator tank 3 comprises a fourth inlet 31 arranged at the top of the ethylene separator tank 3 and a fourth outlet 32 ​​arranged at the bottom of the ethylene separator tank 3 ; a gas phase outlet 34 is arranged at the side of the ethylene separator tank 3 to output the ethylene gas to the ethylene output pipeline 71 .

[0042] A baffle 35 is provided at the gas phase outlet 34 in the ethylene liquid separator 3 to block the liquid from being discharged from the gas phase outlet 34 and prevent the gas phase from short-circuiting and entraining the liquid. Preferably, the baffle 35 can be a right-angle steel plate to block the gas phase outlet 34, and the gas-liquid mixed component entering from the top of the ethylene liquid separator 3 can condense and drip when encountering the baffle 35 without being discharged from the gas phase outlet 34.

[0043] The fourth inlet 31 of the ethylene separator 3 is connected to the third outlet 22 of the flash aftercooler 2; and the third outlet 22 of the flash aftercooler 2 is inserted into the fourth inlet 31 of the ethylene separator 3 so that the two are combined in the same device.

[0044] The first outlet 11 at the top of the flash tank 1 is connected to the third opening 21 at the top of the flash aftercooler 2, and the fourth outlet 32 ​​of the ethylene separator 3 is connected to the recovery liquid inlet 13 of the flash tank 1 through the first pipeline; the first pipeline includes a first branch pipe 41, a second branch pipe 43 and an inverted U-shaped liquid seal pipe 42 between the first branch pipe 41 and the second branch pipe 43, the first branch pipe 41 is connected to the fourth outlet 32, and the second branch pipe 43 is connected to the recovery liquid inlet 13; the liquid phase components separated from the ethylene separator 3 flow through the first branch pipe 41, the inverted U-shaped liquid seal pipe 42 and the second branch pipe 43 in sequence to enter the flash tank 1. The first branch pipe 41 is provided with a first valve 44 for controlling the connection and closing of the pipeline. The inverted U-shaped liquid seal pipe 42 forms a liquid seal to prevent gas phase crosstalk.

[0045] Among them, the fourth outlet 32 ​​of the ethylene separator tank 3 is in the height direction (such as Figure 1 The arrow direction A) is located above the recovery liquid inlet 13 of the flash tank 1. The ethylene separator 3 and the flash tank 1 are set with an appropriate installation height difference to ensure that the liquid phase in the ethylene separator 3 can enter the flash tank 1 by gravity.

[0046] The first branch pipe 41 and the second branch pipe 43 are also directly connected through the third branch pipe 46, and the third branch pipe 46 is provided with a second valve 47 for controlling the connection and closing of the pipeline. Since part of the liquid phase remains in the ethylene liquid separator 3 and its bottom pipeline during shutdown, the second valve 47 is used to drain the liquid phase in the ethylene liquid separator 3 and its bottom pipeline to the flash tank 1 during shutdown. Under normal working conditions, the second valve 47 is in a closed state.

[0047] The first branch pipe 41 is connected to a second pipeline at a position closer to the fourth outlet 32 ​​at the bottom of the ethylene separator tank 3 relative to the first valve 44. The second pipeline 51 is provided with a third valve 52. The second pipeline 51 is connected to a flash liquid phase pipeline 61 at the second outlet 12 at the bottom of the flash tank 1.

[0048] The liquid phase heavy component precipitated from the ethylene separator 3 returns to the flash tank 1 through the first pipeline or directly enters the downstream system through the flash liquid phase pipeline 61 at the bottom of the flash tank 1 through the second pipeline 51. The first valve 44 and the third valve 52 are used to switch the flow direction of the heavy component, and these two flow directions are selected according to the production realization situation. Specifically, in actual production, the flash tank 1 or the flash liquid phase pipeline 61 can be selected according to which distance is closer, so as to save production costs.

[0049] The ethylene liquid separation tank 3 also includes an opening 33 arranged on its side, and the opening 33 is connected to the inverted U-shaped liquid sealing pipe 42 through a siphon breaking valve 45 to balance the pressure of the ethylene liquid separation tank 3 and the inverted U-shaped liquid sealing pipe 42, so that the pressure of the ethylene liquid separation tank 3 and the inverted U-shaped liquid sealing pipe 42 is the same.

[0050] A fourth valve 62 is provided on the flash liquid phase pipeline 61, and a fifth valve 72 is provided on the ethylene output pipeline 71. The pressure and temperature of the flash tank 1 and the liquid separator are controlled by the fourth valve 62 and the fifth valve 72. According to the equilibrium temperature of the medium, the operating pressure and temperature of the flash tank 1 and the ethylene liquid separator 3 are controlled by the fourth valve 62 and the fifth valve 72 to achieve full separation of unreacted ethylene. The fourth valve 62 and the fifth valve 72 are pressure control valves commonly used in the prior art, and the temperature in the tank is further controlled by pressure.

[0051] The method for separating the reaction product of preparing alpha-olefins by the flash distillation and cooling separation system as described above comprises the following steps:

[0052] 1) The reaction product is flashed at reduced pressure in a flash tank 1 to obtain a flash gas phase component and a flash liquid phase component; the flash liquid phase component is discharged from a second outlet 12 at the bottom of the flash tank 1 to a flash liquid phase pipeline 61; a gas phase baffle may or may not be provided in the flash tank 1.

[0053] 2) The flash gas phase components containing heavy components are discharged from the first outlet 11 at the top of the flash tank 1, and enter the flash aftercooler 2 from the third opening 21 at the top of the flash aftercooler 2 to be cooled to a lower temperature by the cooling medium, and most of the heavy components are condensed into a liquid phase;

[0054] 3) Subsequently, the gas-liquid mixed components obtained in step 2) enter the ethylene separator tank 3 for gas-liquid separation, and the unreacted ethylene is sent to the compressor for recycling from the gas phase outlet 34 of the ethylene separator tank 3, and the liquid phase heavy components flow back to the flash tank 1 from the fourth outlet 32 ​​at the bottom of the ethylene separator tank 3 by gravity or enter the flash liquid phase pipeline 61 at the bottom of the flash tank 1.

[0055] Preferably, the heating device may also be an external tank half-pipe heating device or an external tank jacket heating device.

[0056] Example 2

[0057] like Figure 2 FIG. 1 shows a flash aftercooling separation system for preparing α-olefin reaction products by ethylene polymerization. The system comprises a flash tank 1, a flash aftercooler 2 and an ethylene liquid separator 3. Figure 2 The flash gas phase shown enters the flash aftercooler 2 and the ethylene liquid separator 3 of the combined structure, enters from the bottom of the aftercooler and the ethylene gas phase is discharged from the third opening 21 at the top of the flash aftercooler 2, so as to achieve the cooling and separation effect.

[0058] The equipment structure of the ethylene separator 3, the aftercooler and the separator can be combined in the same equipment (such as Figure 2 The aftercooler and the liquid separator are combined in the same device to reduce the floor space and facilitate the layout of the device. In another preferred embodiment, the aftercooler and the liquid separator are arranged separately, and the two devices can also be arranged separately vertically or horizontally (not shown). The use of the aftercooler and the liquid separator can effectively separate the unreacted ethylene in the reaction product.

[0059] The flash tank 1 comprises a first outlet 11 arranged at the top of the flash tank 1, a second outlet 12 arranged at the bottom of the flash tank 1 and a recovery liquid inlet 13 arranged at the side of the flash tank 1; a heating device is arranged outside the flash tank 1, and the heating device is an external tank coil heating device 14, such as Figure 2 shown.

[0060] The flash aftercooler 2 comprises a third opening 21 disposed at the top of the flash aftercooler 2 and a third outlet 22 disposed at the bottom of the flash aftercooler 2;

[0061] The ethylene separator tank 3 includes a fourth inlet 31 arranged at the top of the ethylene separator tank 3 and a fourth outlet 32 ​​arranged at the bottom of the ethylene separator tank 3; the fourth inlet 31 of the ethylene separator tank 3 is connected to the third outlet 22 of the flash aftercooler 2; and the third outlet 22 of the flash aftercooler 2 is inserted into the fourth inlet 31 of the ethylene separator tank 3 so that the two are combined in the same device.

[0062] A gas-liquid mixing inlet 36 is provided on the side adjacent to the top of the ethylene separator tank 3, and the position of the gas-liquid mixing inlet 36 corresponds to the position of the third outlet 22 of the flash aftercooler 2 inserted into the ethylene separator tank 3. The first outlet 11 at the top of the flash tank 1 is connected to the gas-liquid mixing inlet 36, so that the flash gas phase component containing the heavy component enters the flash aftercooler 2 directly from the bottom of the flash aftercooler 2 after entering from the gas-liquid mixing inlet 36. The third opening 21 at the top of the flash aftercooler 2 allows the ethylene gas to be output.

[0063] A mesh anti-mist entrainment component 23 is provided at the third opening 21 at the top of the flash aftercooler 2 to prevent liquid from being discharged from the third opening 21. If the liquid condenses and drips on the mesh anti-mist entrainment component 23 after encountering the mesh anti-mist entrainment component 23, the gas can be discharged through the mesh of the mesh through the third opening 21. The mesh porosity of the mesh anti-mist entrainment component 23 is 0.95-0.99.

[0064] The fourth outlet 32 ​​of the ethylene liquid separator 3 is connected to the recovery liquid inlet 13 of the flash tank 1 through the first pipeline; the first pipeline comprises a first branch pipe 41, a second branch pipe 43 and an inverted U-shaped liquid seal pipe 42 between the first branch pipe 41 and the second branch pipe 43, the first branch pipe 41 is connected to the fourth outlet 32, and the second branch pipe 43 is connected to the recovery liquid inlet 13; the liquid phase components separated from the ethylene liquid separator 3 flow through the first branch pipe 41, the inverted U-shaped liquid seal pipe 42 and the second branch pipe 43 in sequence to enter the flash tank 1. The first branch pipe 41 is provided with a first valve 44 for controlling the connection and closing of the pipeline. The inverted U-shaped liquid seal pipe 42 forms a liquid seal to prevent gas phase crosstalk.

[0065] The fourth outlet 32 ​​of the ethylene separator tank 3 is located above the recovery liquid inlet 13 of the flash tank 1 in the height direction. An appropriate installation height difference is set between the ethylene separator tank 3 and the flash tank 1 to ensure that the liquid phase in the ethylene separator tank 3 can enter the flash tank 1 by gravity.

[0066] The first branch pipe 41 and the second branch pipe 43 are also directly connected through the third branch pipe 46, and the third branch pipe 46 is provided with a second valve 47 for controlling the connection and closing of the pipeline. Since part of the liquid phase remains in the ethylene liquid separator 3 and its bottom pipeline during shutdown, the second valve 47 is used to drain the liquid phase in the ethylene liquid separator 3 and its bottom pipeline to the flash tank 1 during shutdown. Under normal working conditions, the second valve 47 is in a closed state.

[0067] The first branch pipe 41 is connected to a second pipeline at a position closer to the fourth outlet 32 ​​at the bottom of the ethylene separator tank 3 relative to the first valve 44. The second pipeline 51 is provided with a third valve 52. The second pipeline 51 is connected to a flash liquid phase pipeline 61 at the second outlet 12 at the bottom of the flash tank 1.

[0068] The liquid phase heavy component precipitated from the ethylene separator 3 returns to the flash tank 1 through the first pipeline or directly enters the downstream system through the flash liquid phase pipeline 61 at the bottom of the flash tank 1 through the second pipeline 51. The first valve 44 and the third valve 52 are used to switch the flow direction of the heavy component, and these two flow directions are selected according to the production realization situation. Specifically, in actual production, the flash tank 1 or the flash liquid phase pipeline 61 can be selected according to which distance is closer, so as to save production costs.

[0069] The ethylene liquid separation tank 3 also includes an opening 33 arranged on its side, and the opening 33 is connected to the inverted U-shaped liquid sealing pipe 42 through a siphon breaking valve 45 to balance the pressure of the ethylene liquid separation tank 3 and the inverted U-shaped liquid sealing pipe 42, so that the pressure of the ethylene liquid separation tank 3 and the inverted U-shaped liquid sealing pipe 42 is the same.

[0070] The gas-liquid mixing inlet 36 is closer to the top of the ethylene liquid separation tank 3 than the opening 33 communicating with the siphon breaking valve 45 .

[0071] A fourth valve 62 is provided on the flash liquid phase pipeline 61, and a fifth valve 72 is provided on the ethylene output pipeline 71. The pressure and temperature of the flash tank 1 and the liquid separator are controlled by the fourth valve 62 and the fifth valve 72. According to the equilibrium temperature of the medium, the operating pressure and temperature of the flash tank 1 and the ethylene liquid separator 3 are controlled by the fourth valve 62 and the fifth valve 72 to achieve full separation of unreacted ethylene. The fourth valve 62 and the fifth valve 72 are pressure control valves commonly used in the prior art, and the temperature in the tank is further controlled by pressure.

[0072] The method for separating the reaction product of preparing alpha-olefins by the flash distillation and cooling separation system as described above comprises the following steps:

[0073] 1) The reaction product is flashed at reduced pressure in a flash tank 1 to obtain a flash gas phase component and a flash liquid phase component; the flash liquid phase component is discharged from a second outlet 12 at the bottom of the flash tank 1 to a flash liquid phase pipeline 61; a gas phase baffle may or may not be provided in the flash tank 1.

[0074] 2) The flash gas phase component containing the heavy component is discharged from the first outlet 11 at the top of the flash tank 1, and enters from the gas-liquid mixed inlet 36 of the ethylene separator 3 to enter the flash aftercooler 2 from the bottom of the flash aftercooler 2 and is cooled to a lower temperature by the cooling medium, and most of the heavy components are condensed into a liquid phase;

[0075] 3) Subsequently, the gas-liquid mixed components obtained in step 2) enter the ethylene separator tank 3 for gas-liquid separation, and the unreacted ethylene is sent to the compressor for recycling from the gas phase outlet 34 of the ethylene separator tank 3, and the liquid phase heavy components flow back to the flash tank 1 from the fourth outlet 32 ​​at the bottom of the ethylene separator tank 3 by gravity or enter the flash liquid phase pipeline 61 at the bottom of the flash tank 1.

[0076] Preferably, the heating device may also be an external tank half-pipe heating device or an external tank jacket heating device.

[0077] The above is an exemplary embodiment disclosed by the present invention, but it should be noted that, without departing from the scope disclosed by the embodiments of the present invention as defined in the claims, various changes and modifications may be made. In addition, although the elements disclosed by the embodiments of the present invention may be described or required in individual form, they may also be understood as multiple unless explicitly limited to the singular.

[0078] It should be understood that, as used herein, the singular forms "a", "an" are intended to include the plural forms as well, unless the context clearly supports an exception. It should also be understood that, as used herein, "and / or" refers to any and all possible combinations including one or more of the associated listed items.

[0079] The serial numbers of the embodiments disclosed in the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0080] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A flash evaporation and post-cooling separation system for the reaction product of ethylene polymerization to prepare α-olefins, characterized in that: include: A flash tank, the flash tank comprising a first outlet disposed at the top of the flash tank, a second outlet disposed at the bottom of the flash tank, and a recovery liquid inlet disposed at the side of the flash tank; A flash aftercooler and an ethylene separator tank, wherein the ethylene separator tank comprises a fourth inlet arranged at the top of the ethylene separator tank and a fourth outlet arranged at the bottom of the ethylene separator tank; wherein the bottom of the flash aftercooler is connected to the fourth inlet of the ethylene separator tank; the flash aftercooler comprises a third opening arranged at the top of the flash aftercooler and a third outlet arranged at the bottom of the flash aftercooler; the first outlet at the top of the flash tank is connected to the third outlet at the bottom of the flash aftercooler, and the third opening at the top of the flash aftercooler allows ethylene gas to be output; a mesh anti-mist entrainment component is provided at the third opening at the top of the flash aftercooler to prevent liquid from being discharged from the third opening; the mesh porosity of the mesh anti-mist entrainment component is 0.95-0.99; The first outlet at the top of the flash tank is connected to the top or bottom of the flash aftercooler; The fourth outlet of the ethylene liquid separator is connected to the recovery liquid inlet of the flash tank through a first pipeline; the first pipeline comprises a first branch pipe, a second branch pipe and an inverted U-shaped liquid seal pipe between the first branch pipe and the second branch pipe, the first branch pipe is connected to the fourth outlet, and the second branch pipe is connected to the recovery liquid inlet; wherein the fourth outlet of the ethylene liquid separator is located above the recovery liquid inlet of the flash tank in the height direction; the first branch pipe is provided with a first valve for controlling pipeline connection and closing.

2. The flash evaporation and cooling separation system for preparing alpha-olefin reaction products by ethylene polymerization according to claim 1, characterized in that: The ethylene liquid separation tank further comprises an opening arranged on its side, and the opening is connected to the inverted U-shaped liquid sealing pipe through a siphon breaking valve to balance the pressure of the ethylene liquid separation tank and the inverted U-shaped liquid sealing pipe.

3. The flash evaporation and cooling separation system for preparing alpha-olefins by polymerization of ethylene as claimed in claim 1, characterized in that: The first branch pipe and the second branch pipe are also directly connected through a third branch pipe, and the third branch pipe is provided with a second valve for controlling the connection and closing of the pipeline.

4. The flash evaporation and cooling separation system for preparing alpha-olefin reaction products by ethylene polymerization according to claim 1, characterized in that: The first branch pipe is connected to a second pipeline at a position closer to the fourth outlet of the bottom of the ethylene separator relative to the first valve. The second pipeline is provided with a third valve and connected to a flash liquid phase pipeline at the second outlet of the bottom of the flash tank.

5. A method for separating the reaction product of preparing α-olefins by the flash distillation and post-cooling separation system according to any one of claims 1 to 4, characterized in that: The following steps are involved: 1) The reaction product is flashed by reducing pressure in a flash tank to obtain a flash gas phase component and a flash liquid phase component; the flash liquid phase component is discharged from the second outlet at the bottom of the flash tank to the flash liquid phase pipeline; 2) The flash gas phase components containing heavy components are discharged from the first outlet at the top of the flash tank and enter the flash aftercooler from the bottom of the flash aftercooler for cooling and condensation; 3) Then, the gas-liquid mixed components obtained in step 2) enter the ethylene separator tank for gas-liquid separation, and the unreacted ethylene is sent to the compressor for recycling from the third opening at the top of the flash aftercooler, and the liquid phase heavy components flow back to the flash tank from the fourth outlet at the bottom of the ethylene separator tank by gravity or enter the flash liquid phase pipeline at the bottom of the flash tank.

Images