阅读说明：本技术 一种丙烷脱氢装置与乙烯装置联产的工艺方法及系统 (Process method and system for co-production of propane dehydrogenation device and ethylene device ) 是由 姜浩 张锦红 张军 马利峰 于 2020-05-25 设计创作，主要内容包括：本发明涉及一种丙烷脱氢装置与乙烯装置联产的工艺方法及系统,包括油气水洗塔、富气压缩机、富气压缩机出口冷却器、汽水分离器、富气干燥器、冷箱、气液分离罐、凝液输送泵、粗脱乙烷塔、粗脱乙烷塔顶冷凝器、粗脱乙烷塔顶回流罐、粗脱乙烷塔顶回流泵、粗脱乙烷塔底输送泵及丙烯精馏塔。本技术方案利用乙烯装置的精馏系统分离乙烯装置裂解气和丙烷脱氢装置的脱乙烷塔顶不凝汽,增加了产品附加值,提高了收益,并且共用公用工程系统和制冷系统,减少了设备投资和占地。(The invention relates to a process method and a system for co-production of a propane dehydrogenation device and an ethylene device, which comprise an oil-gas water washing tower, a rich gas compressor outlet cooler, a steam-water separator, a rich gas dryer, a cold box, a gas-liquid separation tank, a condensate delivery pump, a crude deethanizer top condenser, a crude deethanizer top reflux tank, a crude deethanizer top reflux pump, a crude deethanizer bottom delivery pump and a propylene rectifying tower. The technical scheme utilizes the rectification system of the ethylene device to separate the cracked gas of the ethylene device and the top of the deethanizer of the propane dehydrogenation device without condensing steam, thereby increasing the added value of products, improving the income, and reducing the equipment investment and the occupied area by sharing a public engineering system and a refrigeration system.)

1. A process method for co-production of a propane dehydrogenation device and an ethylene device is characterized by comprising the following steps:

s1, sending a PDH product rich gas from the propane dehydrogenation reaction unit to an oil-gas water washing tower, and discharging the PDH product rich gas from the top of the oil-gas water washing tower after the PDH product rich gas is washed by the oil-gas water washing tower;

s2, introducing a PDH product rich gas discharged from the top of the oil-gas water scrubber into a rich gas compressor, pressurizing by the rich gas compressor, and sending to an outlet cooler of the rich gas compressor;

s3, sending the PDH product rich gas cooled by the outlet cooler of the rich gas compressor to a steam-water separation tank to separate the oil-contaminated water, discharging the PDH product rich gas subjected to steam-water separation from the top of the steam-water separation tank, and sending the PDH product rich gas to a rich gas dryer;

s4, in the rich gas dryer, removing residual moisture from the rich gas of the PDH product, sending the rich gas to a cold box, further cooling, and sending the rich gas to a gas-liquid separation tank;

s5, in the gas-liquid separation tank, sending light hydrocarbon gas contained in the rich gas of the PDH product to the upper part of the crude deethanizer from the top of the gas-liquid separation tank, and pumping the first light hydrocarbon condensate at the bottom of the gas-liquid separation tank to the lower part of the crude deethanizer through a condensate pump;

s6, sending light hydrocarbon gas from the top of the crude deethanizer to a condenser at the top of the crude deethanizer, condensing the light hydrocarbon gas by the condenser at the top of the crude deethanizer, and then sending the condensed light hydrocarbon gas into a crude deethanizer reflux tank, wherein the light hydrocarbon condensate is used as the reflux liquid at the top of the crude deethanizer and is sent back to the top of the crude deethanizer by a crude deethanizer reflux pump, and the dry gas is sent to the inlet of a fourth-stage cracking gas compressor of an ethylene device after being extracted from the reflux tank of the crude deethanizer;

s7, sending light hydrocarbon extracted from the bottom of the crude deethanizer to a propylene rectifying tower through a crude deethanizer bottom conveying pump, extracting a polymerization-grade propylene product from the top of the propylene rectifying tower, and returning propane extracted from the bottom of the propylene rectifying tower to a propane dehydrogenation reaction unit as circulating propane.

2. The process for propane dehydrogenation unit co-production with an ethylene unit of claim 1, further comprising: the dry gas of propane dehydrogenation and ethylene cracking gas are sent to a rectifying system of the ethylene device together for separation by utilizing a rectifying tower system of the ethylene device.

3. The process for co-production of propane dehydrogenation unit and ethylene unit as claimed in claim 1, wherein the theoretical plate number of the oil gas water washing tower is layer, the operation pressure is normal pressure, the temperature extracted from the top of the tower is 42 ℃, and the temperature extracted from the bottom of the tower is 55 ℃; the outlet pressure of the rich gas compressor is 1.15 MPaG; and the outlet temperature of the hot end of the cooler of the rich gas compressor is 40 ℃.

4. The process for the co-production of a propane dehydrogenation unit and an ethylene unit according to claim 1, wherein the steam-water separation tank is operated at an operating pressure of 1.1MPaG and an operating temperature of 40 ℃; the operating pressure of the rich gas dryer is 1.05MPaG, and the operating temperature is 40 ℃; the inlet temperature of the rich gas end of the cooling box is 40 ℃, the outlet temperature is-33 ℃, the operating pressure of the gas-liquid separation tank is 0.9MPaG, and the operating temperature is-33 ℃.

5. The process for the co-production of a propane dehydrogenation unit and an ethylene unit of claim 1, wherein the number of theoretical plates of the crude deethanizer is 48, the operating pressure is 0.75MPaG, the temperature at the top of the tower is-23 ℃, and the temperature at the bottom of the tower is 18 ℃; the number of theoretical plates of the propylene rectifying tower is 200, the operating pressure is 0.8MPaG, the temperature at the top of the tower is 15 ℃, and the temperature at the bottom of the tower is 27 ℃.

6. The process for propane dehydrogenation unit and ethylene unit co-production according to claim 1, wherein the PDH product rich gas consists of: 1.57 wt% of hydrogen, 0.86 wt% of methane, 0.49 wt% of ethylene, 0.84 wt% of ethane, 0.01 wt% of propyne, 32.11 wt% of propylene, 62.65 wt% of propane and 0.95 wt% of heavy component impurities.

7. The process for propane dehydrogenation unit and ethylene unit co-production according to claim 1, wherein the composition of the dry gas withdrawn from the top of the reflux drum of the crude deethanizer is: 24.04 wt% of hydrogen, 27.34 wt% of methane, 7.5 wt% of ethylene, 12.76 wt% of ethane, 22.59 wt% of propylene and 5.77 wt% of propane.

8. The process for the co-production of a propane dehydrogenation unit and an ethylene unit as claimed in claim 1, wherein the propylene product extracted from the top of the propylene rectification column contains 99.6 wt% of propylene and 0.4 wt% of propane.

9. A system for co-production of a propane dehydrogenation unit and an ethylene unit, for use in a process for co-production of a propane dehydrogenation unit and an ethylene unit according to any one of claims 1 to 8, comprising:

the system comprises an oil gas water washing tower, a rich gas compressor outlet cooler, a steam-water separator, a rich gas dryer, a cold box, a gas-liquid separation tank, a condensate delivery pump, a crude deethanizer top condenser, a crude deethanizer top reflux tank, a crude deethanizer top reflux pump, a crude deethanizer bottom delivery pump and a propylene rectifying tower;

a PDH product rich gas of the propane dehydrogenation reaction unit is connected with a gas inlet at the side lower part of the oil gas water washing tower from a rich gas outlet of the waste heat recovery device through a pipeline, and washing water is connected with a water inlet at the side upper part of the oil gas water washing tower through a pipeline; the top gas outlet of the oil-gas water washing tower is connected with the inlet of a rich gas compressor through a pipeline, and the outlet of the rich gas compressor is connected with the inlet of the hot end of an outlet cooler of the rich gas compressor through a pipeline;

an outlet of the hot end of an outlet cooler of the rich gas compressor is connected with an inlet of a steam-water separation tank through a pipeline, a gas-phase outlet at the top of the steam-water separation tank is connected with an inlet of a rich gas dryer through a pipeline, an outlet of the rich gas dryer is connected with a rich gas end inlet of a cold box through a pipeline, and a rich gas end outlet of the cold box is connected with an inlet of a gas-liquid separator through a pipeline;

a gas phase outlet at the top of the gas-liquid separation tank is connected with a gas inlet at the upper part of the crude deethanizer through a pipeline, a liquid phase outlet at the bottom of the gas-liquid separation tank is connected with an inlet of a condensate delivery pump through a pipeline, and an outlet of the condensate delivery pump is connected with a middle liquid inlet of the crude deethanizer through a pipeline;

a gas phase outlet at the top of the crude deethanizer is connected with a hot end inlet of a condenser at the top of the crude deethanizer through a pipeline, and a hot outlet of the condenser at the top of the crude deethanizer is connected with an inlet of a reflux tank at the top of the crude deethanizer;

a gas phase outlet at the top of the reflux tank at the top of the crude deethanizer is connected to an inlet of a fourth-stage compressor of the ethylene plant through a pipeline; a liquid phase outlet at the bottom of the reflux tank at the top of the crude deethanizer is connected with an inlet of a reflux pump at the top of the crude deethanizer, and an outlet of the reflux pump at the top of the crude deethanizer is connected with a reflux port at the top of the crude deethanizer;

the liquid phase outlet at the bottom of the crude deethanizer is connected with the inlet of a crude deethanizer bottom delivery pump, and the outlet of the crude deethanizer bottom delivery pump is connected with the inlet of a propylene rectifying tower;

the propane product outlet at the top of the propylene rectifying tower is connected with the inlet of the cryogenic unit through a pipeline, and the propane outlet at the bottom of the propylene rectifying tower is connected with the inlet of the propane dehydrogenation reaction unit.

Technical Field

The invention belongs to the technical field of propane dehydrogenation and ethylene, and particularly relates to a process method and a system for co-production of an ethylene device of a propane dehydrogenation device.

Background

Ethylene and propylene are important petrochemical monomers that can be used to produce a variety of polymers and intermediates. As the market demand for these products increases, so does the demand for ethylene and propylene. Ethylene plants and propane dehydrogenation plants are currently the predominant production processes.

The dry gas at the top of the depropanizing tower of the propane dehydrogenation device contains a part of ethylene, ethane is generally sent to the propane dehydrogenation device along with the dry gas as fuel gas to be burnt, the part of ethylene and ethane are wasted, the additional value is low, and if the ethane in the dry gas is separated in the propane dehydrogenation device independently, the ethylene increases the equipment investment but the obtained benefit is limited.

In view of the above problems, how to realize co-production of an ethylene plant and a propane dehydrogenation plant by changing a technical scheme and recover the propylene and propane in the propane dehydrogenation dry gas is a problem to be solved urgently.

Disclosure of Invention

The invention aims to provide a process method and a system for co-production of a propane dehydrogenation device and an ethylene device, and aims to solve the problem of dry gas separation of the conventional propane dehydrogenation device.

The invention is realized by the following technical scheme:

a process method for co-production of a propane dehydrogenation unit and an ethylene unit comprises the following steps:

s1, sending a PDH product rich gas from the propane dehydrogenation reaction unit to an oil-gas water washing tower, and discharging the PDH product rich gas from the top of the oil-gas water washing tower after the PDH product rich gas is washed by the oil-gas water washing tower;

s2, introducing a PDH product rich gas discharged from the top of the oil-gas water scrubber into a rich gas compressor, pressurizing by the rich gas compressor, and sending to an outlet cooler of the rich gas compressor;

s3, sending the PDH product rich gas cooled by the outlet cooler of the rich gas compressor to a steam-water separation tank to separate the oil-contaminated water, discharging the PDH product rich gas subjected to steam-water separation from the top of the steam-water separation tank, and sending the PDH product rich gas to a rich gas dryer;

s4, in the rich gas dryer, removing residual moisture from the rich gas of the PDH product, sending the rich gas to a cold box, further cooling, and sending the rich gas to a gas-liquid separation tank;

s5, in the gas-liquid separation tank, sending light hydrocarbon gas contained in the rich gas of the PDH product to the upper part of the crude deethanizer from the top of the gas-liquid separation tank, and pumping the first light hydrocarbon condensate at the bottom of the gas-liquid separation tank to the lower part of the crude deethanizer through a condensate pump;

s6, sending light hydrocarbon gas from the top of the crude deethanizer to a condenser at the top of the crude deethanizer, condensing the light hydrocarbon gas by the condenser at the top of the crude deethanizer, and then sending the light hydrocarbon gas into a crude deethanizer reflux tank, wherein the light hydrocarbon condensate is used as the reflux liquid at the top of the crude deethanizer and is sent back to the top of the crude deethanizer by a crude deethanizer reflux pump, and the dry gas is sent to the inlet of a fourth-stage cracking gas compressor of an ethylene device after being extracted from the crude deethanizer reflux tank;

s7, sending light hydrocarbon extracted from the bottom of the crude deethanizer to a propylene rectifying tower through a crude deethanizer bottom conveying pump, extracting a polymerization-grade propylene product from the top of the propylene rectifying tower, and returning propane extracted from the bottom of the propylene rectifying tower to a propane dehydrogenation reaction unit as circulating propane.

Further, the process method further comprises the following steps: the dry gas of propane dehydrogenation and ethylene cracking gas are sent to a rectifying system of the ethylene device together for separation by utilizing a rectifying tower system of the ethylene device.

Further, the theoretical plate number of the oil-gas water washing tower is 4 layers, the operation pressure is normal pressure, the temperature extracted from the top of the tower is 42 ℃, and the temperature extracted from the bottom of the tower is 55 ℃; the outlet pressure of the rich gas compressor is 1.15 MPaG; and the outlet temperature of the hot end of the cooler of the rich gas compressor is 40 ℃.

Further, the operating pressure of the steam-water separation tank is 1.1MPaG, and the operating temperature is 40 ℃; the operating pressure of the rich gas dryer is 1.05MPaG, and the operating temperature is 40 ℃; the inlet temperature of the rich gas end of the cooling box is 40 ℃, the outlet temperature is-33 ℃, the operating pressure of the gas-liquid separation tank is 0.9MPaG, and the operating temperature is-33 ℃.

Further, the number of theoretical plates of the crude deethanizer is 48, the operating pressure is 0.75MPaG, the temperature at the top of the tower is-23 ℃, and the temperature at the bottom of the tower is 18 ℃; the number of theoretical plates of the propylene rectifying tower is 200, the operating pressure is 0.8MPaG, the temperature at the top of the tower is 15 ℃, and the temperature at the bottom of the tower is 27 ℃.

Further, the rich gas composition of the PDH product is as follows: 1.57 wt% of hydrogen, 0.86 wt% of methane, 0.49 wt% of ethylene, 0.84 wt% of ethane, 0.01 wt% of propyne, 32.11 wt% of propylene, 62.65 wt% of propane and 0.95 wt% of heavy component impurities.

Furthermore, the composition of dry gas extracted from the top of the reflux tank at the top of the crude deethanizer is as follows: 24.04 wt% of hydrogen, 27.34 wt% of methane, 7.5 wt% of ethylene, 12.76 wt% of ethane, 22.59 wt% of propylene and 5.77 wt% of propane.

Furthermore, the propylene product extracted from the top of the propylene rectifying tower contains 99.6 wt% of propylene and 0.4 wt% of propane.

A system for co-production of a propane dehydrogenation unit and an ethylene unit, which is used for the process method for co-production of the propane dehydrogenation unit and the ethylene unit, and comprises the following steps:

the system comprises an oil gas water washing tower, a rich gas compressor outlet cooler, a steam-water separator, a rich gas dryer, a cold box, a gas-liquid separation tank, a condensate delivery pump, a crude deethanizer top condenser, a crude deethanizer top reflux tank, a crude deethanizer top reflux pump, a crude deethanizer bottom delivery pump and a propylene rectifying tower;

a PDH product rich gas of the propane dehydrogenation reaction unit is connected with a gas inlet at the side lower part of the oil gas water washing tower from a rich gas outlet of the waste heat recovery device through a pipeline, and washing water is connected with a water inlet at the side upper part of the oil gas water washing tower through a pipeline; the top gas outlet of the oil-gas water washing tower is connected with the inlet of a rich gas compressor through a pipeline, and the outlet of the rich gas compressor is connected with the inlet of the hot end of an outlet cooler of the rich gas compressor through a pipeline;

an outlet of the hot end of an outlet cooler of the rich gas compressor is connected with an inlet of a steam-water separation tank through a pipeline, a gas-phase outlet at the top of the steam-water separation tank is connected with an inlet of a rich gas dryer through a pipeline, an outlet of the rich gas dryer is connected with a rich gas end inlet of a cold box through a pipeline, and a rich gas end outlet of the cold box is connected with an inlet of a gas-liquid separator through a pipeline;

a gas phase outlet at the top of the gas-liquid separation tank is connected with a gas inlet at the upper part of the crude deethanizer through a pipeline, a liquid phase outlet at the bottom of the gas-liquid separation tank is connected with an inlet of a condensate delivery pump through a pipeline, and an outlet of the condensate delivery pump is connected with a middle liquid inlet of the crude deethanizer through a pipeline;

a gas phase outlet at the top of the crude deethanizer is connected with a hot end inlet of a condenser at the top of the crude deethanizer through a pipeline, and a hot outlet of the condenser at the top of the crude deethanizer is connected with an inlet of a reflux tank at the top of the crude deethanizer;

a gas phase outlet at the top of the reflux tank at the top of the crude deethanizer is connected to an inlet of a fourth-stage compressor of the ethylene plant through a pipeline; a liquid phase outlet at the bottom of the reflux tank at the top of the crude deethanizer is connected with an inlet of a reflux pump at the top of the crude deethanizer, and an outlet of the reflux pump at the top of the crude deethanizer is connected with a reflux port at the top of the crude deethanizer;

the liquid phase outlet at the bottom of the crude deethanizer is connected with the inlet of a crude deethanizer bottom delivery pump, and the outlet of the crude deethanizer bottom delivery pump is connected with the inlet of a propylene rectifying tower;

the propane product outlet at the top of the propylene rectifying tower is connected with the inlet of the cryogenic unit through a pipeline, and the propane outlet at the bottom of the propylene rectifying tower is connected with the inlet of the propane dehydrogenation reaction unit.

The invention has the beneficial effects that:

1. according to the co-production process method of the propane dehydrogenation device and the ethylene device, the separation system of the ethylene device is used for separating ethylene and ethane in the dry gas of the propane dehydrogenation device, so that the added value of products is increased, and the benefit is improved.

2. The co-production process of the propane dehydrogenation device and the ethylene device shares a common engineering system and a refrigeration system, and reduces equipment investment and occupied land.

Drawings

FIG. 1 is a process flow diagram of the co-production of a propane dehydrogenation plant and an ethylene plant of the present invention.

Description of the reference numerals

1-oil gas water washing tower; 2-a rich gas compressor; 3-a rich gas compressor outlet cooler; 4-a steam-water separation tank; 5-rich gas dryer; 6-a cold box; 7-a gas-liquid separation tank; 8-a condensate delivery pump; 9-a crude deethanizer; 10-crude deethanizer overhead condenser; 11-crude deethanizer overhead reflux drum; 12-crude deethanizer overhead reflux pump; 13-crude deethanizer bottoms transfer pump; 14-propylene rectifying tower.

Detailed Description

It should be noted that the embodiments and features of the embodiments of the present invention may be combined with each other without conflict.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "top", "bottom", and the like, indicate orientations or positional relationships based on those shown in the drawings, are only used for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the invention, the meaning of "a plurality" is two or more unless otherwise specified.

In the description of the invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted", "connected" and "connected" are to be construed broadly, e.g. as being fixed or detachable or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the creation of the present invention can be understood by those of ordinary skill in the art through specific situations.

The invention will be described in detail with reference to the following embodiments with reference to the attached drawings.

As shown in figure 1, the present application provides a process for coproduction of a propane dehydrogenation unit and an ethylene unit, and firstly, PDH product rich gas generated in a propane dehydrogenation reaction unit is sent to the side lower part of a hydrocarbon water washing tower 1.

In this example, the composition of the rich gas of the PDH product produced in the reaction unit was 1.57 wt% hydrogen, 0.86 wt% methane, 0.49 wt% ethylene, 0.84 wt% ethane, 0.01 wt% propyne, 32.11 wt% propylene, 62.65 wt% propane, and 0.95 wt% heavies impurities.

In this embodiment, the operating parameters of the oil-gas water scrubber are selected to be 42 ℃ at the top of the tower, atmospheric pressure at the operating pressure and 55 ℃ at the bottom of the tower. And (3) discharging rich gas of a PDH product from the top of the oil gas washing tower after the rich gas is washed by the oil gas washing tower, and introducing oily sewage at the bottom of the oil gas washing tower into a recovery or treatment system.

The rich gas of the PDH product from the oil gas water scrubber is sent to a rich gas compressor 2, the rich gas of the PDH product is pressurized to 1.15MPaG and then sent to a rich gas compressor outlet cooler 3, the rich gas of the PDH product is cooled to about 40 ℃ by the rich gas compressor outlet cooler and sent to a steam-water separation tank 4 to separate oil-containing sewage, and in the embodiment, the working parameters of the steam-water separation tank are that the operating pressure is 1.1MPaG, and the operating temperature is 40 ℃.

The rich gas of the PDH product is discharged from the top of the steam-water separation tank and sent to a rich gas dryer 5, the working parameters of the rich gas dryer are that the operating pressure is 1.05MPaG, the operating temperature is 40 ℃, the rich gas of the PDH product is subjected to residual moisture removal by the rich gas dryer and then enters a cold box 6, and is sent to a gas-liquid separation tank 7 after being further cooled to-33 ℃, and in the embodiment, the working parameters of the gas-liquid separation tank are that the operating pressure is 0.9MpaG, and the operating temperature is-33 ℃.

The light hydrocarbon gas separated from the gas-liquid separation tank is discharged from the top of the gas-liquid separation tank and then sent to the upper part of a crude deethanizer 9, and the first light hydrocarbon condensate at the bottom of the gas-liquid separation tank is sent to the lower part of the crude deethanizer through a condensate pump 8, wherein in the embodiment, the working parameters of the crude deethanizer are 0.75MpaG, the temperature at the top of the tower is-23 ℃, and the temperature at the bottom of the tower is 18 ℃.

Light hydrocarbon gas is sent to thick deethanizer overhead condenser 10 through thick deethanizer overhead and is condensed and then gets into thick deethanizer reflux jar 11, the second light hydrocarbon condensate in the thick deethanizer reflux jar is carried back to the top of thick deethanizer overhead reflux pump 12 through thick deethanizer overhead reflux as thick deethanizer overhead reflux liquid, dry gas in the thick deethanizer reflux jar is extracted from the tank deck and is sent to the fourth section pyrolysis gas compressor entry of ethylene unit, in this embodiment, the dry gas composition that thick deethanizer overhead reflux jar top was extracted becomes: 24.04 wt% of hydrogen, 27.34 wt% of methane, 7.5 wt% of ethylene, 12.76 wt% of ethane, 22.59 wt% of propylene and 5.77 wt% of propane.

Light hydrocarbon extracted from the bottom of the crude deethanizer is sent to a propylene rectifying tower 14 through a crude deethanizer bottom delivery pump 13, the operating pressure is 0.8MpaG, the tower top temperature is 15 ℃, the tower bottom temperature is 27 ℃, a polymerization-grade propylene product is extracted from the top of the propylene rectifying tower, and propane extracted from the tower bottom is returned to the reaction unit as circulating propane.

The system comprises an oil-gas washing tower, a rich gas compressor outlet cooler, a steam-water separator, a rich gas dryer, a cold box, a gas-liquid separation tank, a condensate delivery pump, a crude deethanizer top condenser, a crude deethanizer top reflux tank, a crude deethanizer top reflux pump, a crude deethanizer bottom delivery pump and a propylene rectifying tower.

A PDH product rich gas of the propane dehydrogenation reaction unit is connected with a gas inlet at the side lower part of the oil gas water washing tower from a rich gas outlet of the waste heat recovery device through a pipeline, and washing water is connected with a water inlet at the side upper part of the oil gas water washing tower through a pipeline; and a gas outlet at the top of the oil-gas water washing tower is connected with an inlet of a rich gas compressor through a pipeline, and an outlet of the rich gas compressor is connected with an inlet of a hot end of an outlet cooler of the rich gas compressor through a pipeline.

The outlet of the hot end of the outlet cooler of the gas-enriched compressor is connected with the inlet of the steam-water separation tank through a pipeline, the gas-phase outlet at the top of the steam-water separation tank is connected with the inlet of the gas-enriched dryer through a pipeline, the outlet of the gas-enriched dryer is connected with the gas-enriched end inlet of the cold box through a pipeline, and the gas-enriched end outlet of the cold box is connected with the inlet of the gas-liquid separator through a pipeline.

The gas phase outlet at the top of the gas-liquid separation tank is connected with the gas inlet at the upper part of the crude deethanizer through a pipeline, the liquid phase outlet at the bottom of the gas-liquid separation tank is connected with the inlet of a condensate delivery pump through a pipeline, and the outlet of the condensate delivery pump is connected with the middle liquid inlet of the crude deethanizer through a pipeline.

The gas phase outlet at the top of the crude deethanizer is connected with the hot end inlet of the condenser at the top of the crude deethanizer through a pipeline, and the hot outlet of the condenser at the top of the crude deethanizer is connected with the inlet of the reflux tank at the top of the crude deethanizer.

A gas phase outlet at the top of the reflux tank at the top of the crude deethanizer is connected to an inlet of a fourth-stage compressor of the ethylene plant through a pipeline; and a liquid phase outlet at the bottom of the reflux tank at the top of the crude deethanizer is connected with an inlet of a reflux pump at the top of the crude deethanizer, and an outlet of the reflux pump at the top of the crude deethanizer is connected with a reflux port at the top of the crude deethanizer.

The liquid phase outlet at the bottom of the crude deethanizer is connected with the inlet of a crude deethanizer bottom delivery pump, and the outlet of the crude deethanizer bottom delivery pump is connected with the inlet of a propylene rectifying tower.

The propane product outlet at the top of the propylene rectifying tower is connected with the inlet of the cryogenic unit through a pipeline, and the propane outlet at the bottom of the propylene rectifying tower is connected with the inlet of the propane dehydrogenation reaction unit.

While the present invention has been described with reference to specific embodiments, it will be apparent to those skilled in the art that the present invention may be practiced by modifying, or by making appropriate changes and combinations of, the products and methods of manufacture described herein without departing from the spirit, scope, and spirit of the invention. It is expressly intended that all such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and content of the invention.