阅读说明：本技术 一种乙烯多聚制备α-烯烃反应产物的闪蒸后冷分离系统 (Cold piece-rate system after flash distillation of α -alkene reaction product is prepared to ethylene polymerization ) 是由 吴南屏 黄祥谦 娄海生 张文超 李月新 徐永伟 于 2019-12-18 设计创作，主要内容包括：本发明涉及一种乙烯多聚制备α-烯烃反应产物的闪蒸后冷分离系统,包括闪蒸罐、闪蒸后冷器和乙烯分液罐。其中,所述乙烯分液罐的第四进口与所述闪蒸后冷器的第三出口连通；所述乙烯分液罐的第四出口通过第一管线连通至所述闪蒸罐的回收液进口；所述第一管线包含相互连通的第一分支管、第二分支管和在第一分支管和第二分支管之间的倒U型液封管。本发明还涉及一种使用如上所述的闪蒸后冷分离系统对乙烯多聚制备α-烯烃反应产物的分离方法。本发明设置反应产物闪蒸气相后冷分离系统,可以提高反应产物中闪蒸气相的乙烯浓度,同时有效利用气液分离效果,回收乙烯循环利用,后冷器与分液罐组合结构能够减少占地面积。(The invention relates to a cold separation system after flash evaporation for preparing α -olefin reaction products from ethylene multimer, which comprises a flash evaporation tank, a cold device after flash evaporation and an ethylene liquid separation tank, wherein a fourth inlet of the ethylene liquid separation tank is communicated with a third outlet of the cold device after flash evaporation, a fourth outlet of the ethylene liquid separation tank is communicated with a recovery liquid inlet of the flash evaporation tank through a first pipeline, and 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 which are communicated with each other.)

1. A cold separation system after flash distillation of α -olefin reaction product from the polymerization of ethylene, comprising:

the flash tank comprises a first outlet arranged at the top of the flash tank, a second outlet arranged at the bottom of the flash tank and a recovered liquid inlet arranged at the side part of the flash tank;

the ethylene separating tank comprises a fourth inlet arranged at the top of the ethylene separating tank and a fourth outlet arranged at the bottom of the ethylene separating tank; the bottom of the flash evaporation aftercooler is communicated to a fourth inlet of the ethylene liquid separation tank;

a first outlet at the top of the flash tank is communicated to the top or the bottom of the flash after-cooler;

a fourth outlet of the ethylene liquid separating tank is communicated to a recycling 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, the first branch pipe and the second branch pipe are communicated with each other, the inverted U-shaped liquid seal pipe is arranged between the first branch pipe and the second branch pipe, the first branch pipe is communicated with the fourth outlet, and the second branch pipe is communicated with the recovery liquid inlet; wherein, the fourth outlet of the ethylene liquid separating tank is positioned above the recycled liquid inlet of the flash tank in the height direction; and a first valve for controlling the communication and the closing of the pipeline is arranged on the first branch pipe.

2. The system for cold separation after flash distillation of the reaction product of ethylene multimerization α -olefin according to claim 1, wherein the ethylene partial tank further comprises an opening disposed on a side thereof, the opening communicating to the inverted U-shaped liquid seal pipe through a siphon-breaking valve to equalize the pressure of the ethylene partial tank and the inverted U-shaped liquid seal pipe.

3. The system for cold separation after flashing of the reaction product of ethylene multimerization α -olefin according to claim 1, wherein the first branch line and the second branch line are further in direct communication via a third branch line, the third branch line being provided with a second valve that controls line communication and closing.

4. The system for cold separation after flashing of the reaction product of ethylene multimerization α -olefin according to claim 1, wherein the first branch line is connected to a second line provided with a third valve at a location closer to a fourth outlet at the bottom of the ethylene separation tank than the first valve, the second line being connected to a flash liquid line at the second outlet at the bottom of the flash tank.

5. The system of claim 1, wherein the flash post-cold separation system comprises a third opening at the top of the flash post-cooler and a third outlet at the bottom of the flash post-cooler, the first outlet at the top of the flash tank is connected to the third opening at the top of the flash post-cooler, and the side of the ethylene separation tank is provided with a gas phase outlet for outputting ethylene gas.

6. The cold separation system after flash distillation of the reaction product of ethylene multimerization α -olefin according to claim 5, wherein a baffle is disposed at the vapor outlet of the ethylene splitter tank to block liquid from exiting the vapor outlet.

7. The system of claim 1, wherein the flash aftercooler comprises a third opening at a top of the flash aftercooler and a third outlet at a bottom of the flash aftercooler, the first outlet at the top of the flash drum is connected to the third outlet at the bottom of the flash aftercooler, and the third opening at the top of the flash aftercooler outputs ethylene gas.

8. The flash cold separation system for poly production of ethylene α -olefin reaction product according to claim 7, wherein a net-like anti-entrainment member is provided at the third opening at the top of the flash aftercooler to block liquid from exiting the third opening.

9. A separation process for the polymerization of ethylene to α -olefin reaction product using a cold separation system after flash distillation as claimed in any one of claims 1-8, comprising the steps of:

1) carrying out pressure reduction and flash evaporation on the reaction product through a flash tank to obtain a flash vapor component and a flash liquid component; discharging the flash liquid phase component from a second outlet at the bottom of the flash tank to a flash liquid phase line;

2) the flash gas phase component containing the heavy component is discharged from a first outlet at the top of the flash tank and enters a flash after-cooler from a third opening at the top of the flash after-cooler for cooling and condensation;

3) and then the gas-liquid mixed component obtained in the step 2) enters an ethylene liquid separation tank for gas-liquid separation, unreacted ethylene is sent to a compressor from a gas phase outlet of the ethylene liquid separation tank for cyclic utilization, and a liquid phase heavy component flows back to a flash tank or enters a flash liquid phase pipeline at the bottom of the flash tank from a fourth outlet at the bottom of the ethylene liquid separation tank under the action of gravity.

10. A separation process for the polymerization of ethylene to α -olefin reaction product using a cold separation system after flash distillation as claimed in any one of claims 1-8, comprising the steps of:

1) carrying out pressure reduction and flash evaporation on the reaction product through a flash tank to obtain a flash vapor component and a flash liquid component;

discharging the flash liquid phase component from a second outlet at the bottom of the flash tank to a flash liquid phase line;

2) discharging the flash vapor phase component containing the heavy component from a first outlet at the top of the flash tank, and entering a flash post-cooler from the bottom of the flash post-cooler for cooling and condensation;

3) and then the gas-liquid mixed component obtained in the step 2) enters an ethylene liquid separation tank for gas-liquid separation, unreacted ethylene is sent to a compressor for recycling from a third opening at the top of a flash evaporator, and a liquid phase heavy component flows back to a flash tank or enters a flash liquid phase pipeline at the bottom of the flash tank from a fourth outlet at the bottom of the ethylene liquid separation tank under the action of gravity.

Technical Field

The invention relates to a technology for cold separation of reaction products after flash evaporation, in particular to a cold separation system and a cold separation method after flash evaporation for preparing α -olefin reaction products by polymerizing ethylene.

Background

In the production process of α -olefin by ethylene polymerization, the reaction product of α -olefin by ethylene polymerization contains unreacted ethylene, the unreacted ethylene is obtained by pressure reduction and flash evaporation of the reaction product with higher pressure through a flash tank, the unreacted ethylene is sent to a compressor for pressure increase and recycling, and the liquid phase reaction product at the bottom of the flash tank enters a post-system for separation to obtain a α -olefin product.

In the process that the ethylene polymerization reaction product enters an ethylene flash tank under reduced pressure, the flash vapor phase contains unreacted ethylene, and because the flash vapor phase has higher temperature and the saturated vapor phase contains more heavy components, the concentration of recovered ethylene is reduced, and the operation of a reaction system is influenced.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a cold separation system and a separation method after flash evaporation for preparing α -olefin reaction products by polymerizing ethylene.

Based on the purpose, the following technical scheme is adopted:

according to the present invention, there is provided a cold separation system after flash distillation for the production of α -olefin reaction product from ethylene polymerization, comprising:

the flash tank comprises a first outlet arranged at the top of the flash tank, a second outlet arranged at the bottom of the flash tank and a recovered liquid inlet arranged at the side part of the flash tank;

the ethylene separating tank comprises a fourth inlet arranged at the top of the ethylene separating tank and a fourth outlet arranged at the bottom of the ethylene separating tank; wherein, the bottom of the flash evaporation aftercooler is communicated to a fourth inlet of the ethylene liquid separation tank;

a first outlet at the top of the flash evaporation tank is communicated to the top or the bottom of the flash evaporation aftercooler;

a fourth outlet of the ethylene liquid separating tank is communicated to a recycled 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, the first branch pipe and the second branch pipe are communicated with each other, the inverted U-shaped liquid seal pipe is arranged between the first branch pipe and the second branch pipe, the first branch pipe is communicated with the fourth outlet, and the second branch pipe is communicated with the recycling liquid inlet; wherein, the fourth outlet of the ethylene liquid separating tank is positioned above the recycled liquid inlet of the flash tank in the height direction; the first branch pipe is provided with a first valve for controlling the communication and closing of the pipeline.

Furthermore, the ethylene liquid separation tank also comprises an opening arranged on the side part of the ethylene liquid separation tank, and the opening is communicated to the inverted U-shaped liquid seal pipe through a siphon breaking valve so as to balance the pressure of the ethylene liquid separation tank and the inverted U-shaped liquid seal pipe.

Furthermore, the first branch pipe and the second branch pipe are also directly communicated through a third branch pipe, and a second valve for controlling the communication and closing of the pipelines is arranged on the third branch pipe.

Further, the first branch pipe is communicated with a second pipeline at a position, close to a fourth outlet at the bottom of the ethylene liquid separation tank relative to the first valve, the second pipeline is provided with a third valve, and the second pipeline is communicated with a flash liquid phase pipeline of a second outlet at the bottom of the flash tank.

Further, the flash after-cooler comprises a third opening arranged at the top of the flash after-cooler and a third outlet arranged at the bottom of the flash after-cooler; the first outlet at the top of the flash tank is communicated to the third opening at the top of the flash after-cooler, and a gas-phase outlet is arranged at the side part of the ethylene separating tank so as to output ethylene gas.

Further, a gas phase outlet in the ethylene liquid separation tank is provided with a baffle plate to block the liquid from being discharged from the gas phase outlet.

Further, the flash after-cooler comprises a third opening arranged at the top of the flash after-cooler and a third outlet arranged at the bottom of the flash after-cooler; the first outlet at the top of the flash tank is communicated to the third outlet at the bottom of the flash after-cooler, and the third outlet at the top of the flash after-cooler enables the ethylene gas to be output.

Further, a third opening on the top of the flash evaporator is provided with a reticular anti-foam entrainment part to prevent the liquid from being discharged from the third opening.

Further, a heat tracing device is arranged outside the flash tank, and is selected from one of an external coil pipe heat tracing device, an external half pipe heat tracing device and an external jacket heat tracing device.

Further, the flash evaporation aftercooler and the ethylene separating tank are separately arranged.

According to the present invention there is also provided a separation process for the polymerization of ethylene to α -olefin reaction product using a cold separation system after flashing as described above, comprising the steps of:

1) carrying out pressure reduction and flash evaporation on the reaction product through a flash tank to obtain a flash vapor component and a flash liquid component; discharging the flash liquid phase component from a second outlet at the bottom of the flash tank to a flash liquid phase line;

2) the flash gas phase component containing the heavy component is discharged from a first outlet at the top of the flash tank and enters a flash after-cooler from a third opening at the top of the flash after-cooler for cooling and condensation;

3) and then the gas-liquid mixed component obtained in the step 2) enters an ethylene liquid separation tank for gas-liquid separation, unreacted ethylene is sent to a compressor from a gas phase outlet of the ethylene liquid separation tank for cyclic utilization, and a liquid phase heavy component flows back to a flash tank or enters a flash liquid phase pipeline at the bottom of the flash tank from a fourth outlet at the bottom of the ethylene liquid separation tank under the action of gravity.

According to the present invention there is also provided a separation process for the polymerization of ethylene to α -olefin reaction product using a cold separation system after flashing as described above, comprising the steps of:

1) carrying out pressure reduction and flash evaporation on the reaction product through a flash tank to obtain a flash vapor component and a flash liquid component; discharging the flash liquid phase component from a second outlet at the bottom of the flash tank to a flash liquid phase line;

2) discharging the flash vapor phase component containing the heavy component from a first outlet at the top of the flash tank, and entering a flash post-cooler from the bottom of the flash post-cooler for cooling and condensation;

3) and then the gas-liquid mixed component obtained in the step 2) enters an ethylene liquid separation tank for gas-liquid separation, unreacted ethylene is sent to a compressor for recycling from a third opening at the top of a flash evaporator, and a liquid phase heavy component flows back to a flash tank or enters a flash liquid phase pipeline at the bottom of the flash tank from a fourth outlet at the bottom of the ethylene liquid separation tank under the action of gravity.

The invention has the beneficial effects that:

the flash evaporation after-cooling separation system and the separation method for the reaction product of ethylene polymerization preparation α -olefin can solve the problem that the operation of a compressor is influenced because the flash evaporation gas phase contains more heavy components, adopt the after-cooling device and the liquid separation tank to be combined in the same equipment, fully separate materials, reduce the occupied area of the equipment, save the construction investment of the device, and adopt horizontal or vertical equipment to be separately arranged if the field condition does not allow the combination.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some implementation examples of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.

FIG. 1 is a schematic diagram of a system of embodiment 1 of the present invention;

fig. 2 is a schematic diagram of a system of embodiment 2 of the present invention.

List of reference numerals

1-a flash tank; 11-a first outlet; 12-a second outlet; 13-inlet of recovery liquid; 14-tank external coil pipe heat tracing device; 2-flash evaporation aftercooler; 21-a third opening; 22-a third outlet; 23-an anti-mist entrainment member; 3-ethylene liquid separating tank; 31-a fourth inlet; 32-a fourth outlet; 33-opening; 34-a gas phase outlet; 35-a baffle; 36-gas-liquid mixing inlet; 41-a first branch pipe; 42-inverted U-shaped liquid seal pipe; 43-a second branch pipe; 44-a first valve; 45-breaking siphon valve; 46-a third branch pipe; 47-a second valve; 51-a second line; 52-a third valve; 61-a flash liquid phase line; 62-a fourth valve; 71-ethylene output line; 72-fifth valve.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the following embodiments of the present invention are described in further detail with reference to the accompanying drawings.