阅读说明：本技术 一种降低乙烯装置高压脱丙烷塔釜温度的方法和装置 (Method and device for reducing temperature of high-pressure depropanizing tower kettle of ethylene device ) 是由 白宇辰 王振维 赵百仁 雷正香 于 2020-04-24 设计创作，主要内容包括：本发明属于石油化工中的乙烯生产装置技术领域,公开了一种降低乙烯装置高压脱丙烷塔釜温度的方法和装置,该方法包括；高压脱丙烷塔的塔顶物料经加热、压缩、碳二加氢、冷却后进入高压脱丙烷塔回流罐,高压脱丙烷塔回流罐中的气体进入脱甲烷塔深冷系统,经冷却后进入预脱甲烷塔,高压脱丙烷塔回流罐中的液体回流至高压脱丙烷塔,预脱甲烷塔的塔釜物料送至脱乙烷塔、塔顶气相送往脱甲烷塔,将脱乙烷塔的塔釜物料混合碳三部分引入高压脱丙烷塔,使高压脱丙烷塔的塔釜温度控制在80℃以下。本发明的方法和装置可控制高压脱丙烷塔的釜温,使高压脱丙烷塔的操作达到设计的温度,在保证产品纯度的同时,不会造成塔板、再沸器发生结焦堵塞的现象。(The invention belongs to the technical field of ethylene production devices in petrochemical industry, and discloses a method and a device for reducing the temperature of a high-pressure depropanizing tower kettle of an ethylene device, wherein the method comprises the following steps of; the tower top material of the high-pressure depropanizing tower is heated, compressed, hydrogenated by carbon and cooled, and then enters a reflux tank of the high-pressure depropanizing tower, the gas in the reflux tank of the high-pressure depropanizing tower enters a deep cooling system of the demethanizing tower, and then enters a pre-demethanizing tower after being cooled, the liquid in the reflux tank of the high-pressure depropanizing tower refluxes to the high-pressure depropanizing tower, the tower bottom material of the pre-demethanizing tower is sent to a deethanizing tower, the gas phase at the tower top is sent to the demethanizing tower, and the three parts of the tower bottom material mixed carbon of the deethanizing tower are introduced into the high-pressure depropanizing tower, so that the tower bottom temperature of the high-pressure depropanizing tower is controlled below 80 ℃. The method and the device can control the kettle temperature of the high-pressure depropanizing tower, ensure that the operation of the high-pressure depropanizing tower reaches the designed temperature, and can not cause the phenomena of coking and blockage of tower plates and a reboiler while ensuring the product purity.)

1. A method for reducing the temperature of a high pressure depropanizer kettle of an ethylene plant, the method comprising; the tower top material of the high-pressure depropanizing tower is heated, compressed, hydrogenated by carbon and cooled, and then enters a reflux tank of the high-pressure depropanizing tower, the gas in the reflux tank of the high-pressure depropanizing tower enters a deep cooling system of the demethanizing tower, and then enters a pre-demethanizing tower after being cooled, the liquid in the reflux tank of the high-pressure depropanizing tower refluxes to the high-pressure depropanizing tower, the tower bottom material of the pre-demethanizing tower is sent to a deethanizing tower, the gas phase at the tower top is sent to the demethanizing tower, and the three parts of the tower bottom material mixed carbon of the deethanizing tower are introduced into the high-pressure depropanizing tower, so that the tower bottom temperature of the high-pressure depropanizing tower is controlled below 80 ℃.

2. The method for reducing ethylene plant high pressure depropanizer column temperature according to claim 1, wherein said mixed carbon three is introduced at a location on the high pressure depropanizer column that is at least one of the column bottom, stripping section, rectification section, feed line and reflux line.

3. The method for reducing ethylene plant high pressure depropanizer drum temperature of claim 1, wherein said mixed carbon three comprises propylene and propane.

4. A method for reducing the high pressure depropanizer column temperature of an ethylene plant according to any one of claims 1 to 3, it is characterized in that the device comprises a high-pressure depropanizing tower and a deethanizing tower, a first reflux pipeline is arranged at the top of the high-pressure depropanizing tower, according to the material flow direction, a heater, a cracking gas compressor, a carbon dioxide hydrogenation system, a cooler and a high-pressure depropanizing tower reflux tank are sequentially arranged on the first reflux pipeline, the gas outlet of the reflux tank of the high-pressure depropanizing tower is connected with the feed inlet of the pre-demethanizing tower through a demethanizing tower cryogenic system, the tower kettle discharge pipeline of the pre-demethanizer is connected with the feed inlet of the deethanizer, the tower top discharge pipeline of the pre-demethanizer is connected with the feed inlet of the demethanizer, and a mixed carbon three-introducing pipeline connected with the high-pressure depropanizing tower is arranged on a tower kettle discharging pipeline of the deethanizing tower.

5. The apparatus of claim 4, wherein the discharge end of the mixed carbon three introduction line is connected to at least one of the still, stripping section, rectification section, feed line, and reflux line of the high pressure depropanizer.

6. The apparatus of claim 4, wherein the mixed carbon three inlet line is provided with a flow meter and a regulating valve.

7. The apparatus of claim 4, wherein the mixed carbon three inlet line is sized to be 2 ".

8. The apparatus of claim 4, wherein the high pressure depropanizer has a feed line in the middle, a high pressure depropanizer reboiler in the kettle, and a kettle discharge line.

9. The apparatus of claim 4, wherein the deethanizer has a feed inlet at the middle part, a deethanizer reboiler at the bottom of the deethanizer, and a second reflux line at the top of the deethanizer, and the second reflux line sequentially comprises a deethanizer overhead cooler, a deethanizer reflux drum, and a deethanizer reflux pump along the material flow direction.

Technical Field

The invention belongs to the technical field of ethylene production devices in petrochemical industry, and particularly relates to a method and a device for reducing the temperature of a high-pressure depropanizing tower kettle of an ethylene device.

Background

A certain ethylene production device adopts a separation flow of front depropanization, and the specific separation flow is shown in figures 1 and 2, a cracking raw material 1 is cracked by a cracking furnace 2 and then enters a quenching oil tower 3, the tower kettle of the quenching oil tower 3 obtains cracking fuel oil 10, the middle part obtains cracking diesel oil 9, tower top materials are sent into the quenching water tower 4, the tower kettle of the quenching water tower 4 obtains cracking gasoline 8, the tower top materials enter a cracking gas compressor (sections 1, 2, 3 and 4) 5 to be compressed and then sent to an alkali washing tower 6, the gas at the top of the alkali washing tower 6 enters a high-pressure depropanization tower 11 after being dried by a cracking gas drier 7, the tower top materials of the high-pressure depropanization tower 11 are heated by a heater 28, the cracking gas compressor (section 5) 12 is compressed, a carbon dioxide hydrogenation system 13 is hydrogenated, a cooler 29 is cooled, liquid flows back to the high-pressure depropanization tower 11, and gas enters a pre-demethanization tower 16 through a demethanization cryogenic system 14, the fuel gas 15 is discharged from the demethanizer cryogenic system 14, the tower bottom material of the predehanizer 16 is sent to the deethanizer 17, the tower top material of the predehanizer 16 is sent to the demethanizer 39, the tower bottom material of the deethanizer 17 is hydrogenated by the carbon three hydrogenation system 18 and then enters the propylene rectifying tower 20 to obtain the propylene 22, the tower bottom material of the demethanizer 39 and the tower top material of the deethanizer 17 enter the ethylene rectifying tower 19 to obtain the ethylene 21, the tower top material of the demethanizer 39 enters the demethanizer cryogenic system 14, the tower bottom material of the high-pressure depropanizer 11 is sent to the low-pressure depropanizer 23 through the low-pressure depropanizer feed cooler 31, the tower bottom material of the low-pressure depropanizer 23 is sent to the debutanizer 24, the tower top of the debutanizer 24 obtains the mixed carbon four 25, and the tower bottom obtains the pyrolysis gasoline 26. The specific process flow of the high pressure depropanizer 11 and deethanizer 17 themselves are not described in detail.

The light key components of the process fluid of the high-pressure depropanizing tower are all carbon dioxide and partial carbon, and the heavy key components are carbon four and components heavier than carbon. The content of the carbon four components is strictly controlled at the tower top, because the excessive carbon four components can seriously affect the subsequent carbon two hydrogenation system, so that the tower top is generally controlled to contain no carbon four or more components, and the tower bottom is controlled to contain no carbon two or less components. During normal operation, the components in the tower bottom are three carbon components and components heavier than three carbon components.

In an industrial application example, the overhead pressure of the high pressure depropanizer is about 1.459MpaG, the overhead temperature is-31 ℃, the pressure of the bottom of the tower is about 1.486MPaG, and the temperature of the bottom of the tower is about 79.6 ℃. If the operation is improper during the production operation, the temperature of the tower bottom can exceed 80 ℃. At the moment, because the composition of the tower kettle is basically the components with more than three carbons, when the temperature of the tower kettle exceeds 80 ℃, the carbon-tetraunsaturated hydrocarbon components in the tower kettle can generate serious polymerization, the tower plate and the reboiler of the tower kettle can generate coking and blockage phenomena, the pressure difference of the tower is increased, the reboiler can not provide enough heating, and the device can be stopped in serious cases.

In many ethylene plant production operations, it is common practice to inject the appropriate concentration of polymerization inhibitor at the feed to the high pressure depropanizer and at the reboiler inlet. The addition of inhibitors can mitigate coking of the trays and reboiler, but this approach tends to respond with lag or sometimes ineffective. This can affect the normal production operation of the ethylene plant.

Disclosure of Invention

In view of the above situation, the present invention aims to provide a method and an apparatus for reducing the temperature of a high-pressure depropanizing tower kettle of an ethylene plant, wherein a part of mixed carbon three material flow of a deethanizing tower kettle far away from the high-pressure depropanizing tower in a process flow is circularly injected into the high-pressure depropanizing tower, so that the temperature of the tower kettle of the high-pressure depropanizing tower can be controlled below 80 ℃, and the separation effect of the high-pressure depropanizing tower is ensured.

In a first aspect of the invention, there is provided a method for reducing the temperature of a high pressure depropanizer drum of an ethylene plant, the method comprising; the tower top material of the high-pressure depropanizing tower is heated, compressed, hydrogenated by carbon and cooled, and then enters a reflux tank of the high-pressure depropanizing tower, the gas in the reflux tank of the high-pressure depropanizing tower enters a deep cooling system of the demethanizing tower, and then enters a pre-demethanizing tower after being cooled, the liquid in the reflux tank of the high-pressure depropanizing tower refluxes to the high-pressure depropanizing tower, the tower bottom material of the pre-demethanizing tower is sent to a deethanizing tower, the gas phase at the tower top is sent to the demethanizing tower, and the three parts of the tower bottom material mixed carbon of the deethanizing tower are introduced into the high-pressure depropanizing tower, so that the tower bottom temperature of the high-pressure depropanizing tower is controlled below 80 ℃.

The second aspect of the invention provides a device adopted by the method for reducing the temperature of the high-pressure depropanizing tower kettle of the ethylene device, which comprises the high-pressure depropanizing tower and the deethanizing tower, wherein a first reflux pipeline is arranged at the top of the high-pressure depropanizing tower, a heater, a cracking gas compressor, a carbon dioxide hydrogenation system, a cooler and a high-pressure depropanizing tower reflux tank are sequentially arranged on the first reflux pipeline according to the material flow direction, a gas outlet of the high-pressure depropanizing tower reflux tank is connected with a feed inlet of the pre-demethanizing tower through a demethanizing tower cryogenic system, a tower kettle discharge pipeline of the pre-demethanizing tower is connected with a feed inlet of the deethanizing tower, a tower top discharge pipeline of the pre-demethanizing tower is connected with a feed inlet of the demethanizing tower, and a mixed carbon three-introduction pipeline connected with the high-pressure depropanizing tower is arranged on the tower kettle discharge pipeline of the deethanizing tower.

According to the invention, the mixed carbon three introduction pipeline is newly added on the high-pressure depropanizing tower, so that the purpose of reducing the temperature of the high-pressure depropanizing tower kettle is achieved, the high-pressure depropanizing tower is stable in operation, the separation effect of the high-pressure depropanizing tower is ensured, the risk of coking and blockage of the tower plate and the reboiler is reduced on the premise of meeting the qualification requirements of tower kettle products and tower top products, and the device is safe and stable to operate in a long period.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without limiting the invention.

FIG. 1 is a schematic of a front-end depropanization flow scheme of a prior art ethylene plant.

FIG. 2 is a schematic process flow diagram of the high pressure depropanizer and deethanizer column of FIG. 1.

Figure 3 is a schematic process flow diagram for reducing the high pressure depropanizer drum temperature of an ethylene plant in accordance with an embodiment of the present invention.

Description of the reference numerals

1-cracking the feedstock; 2-a cracking furnace; 3-a quench oil tower; 4-a quench water tower; 5-cracked gas compressor (1, 2, 3, 4 stages); 6-alkaline washing tower; 7-cracked gas dryer; 8. 26-pyrolysis gasoline; 9-pyrolysis diesel; 10-pyrolysis fuel oil; 11-a high pressure depropanizer; 12-cracked gas compressor (section 5); a 13-carbon dioxide hydrogenation system; 14-demethanizer cryogenic system; 15-fuel gas; 16-a pre-demethanizer; 17-a deethanizer; an 18-carbon three hydrogenation system; 19-an ethylene rectification column; a 20-propylene rectification column; 21-ethylene; 22-propene; 23-a low pressure depropanizer; a 24-debutanizer column; 25-mixed carbon four; 27-a feed line; 28-a heater; 29-a cooler; 30-high pressure depropanizer reflux drum; 31-low pressure depropanizer feed cooler; 32-high pressure depropanizer reboiler; 33-deethanizer reboiler; 34-a deethanizer overhead cooler; 35-deethanizer reflux drum; 36-deethanizer reflux pump; 37-a first mixed carbon three introduction line; 38-a second mixed carbon three introduction line; 39-demethanizer.

Detailed Description

In order that the present invention may be more readily understood, the following detailed description of the invention is given with reference to the accompanying drawings and embodiments, which are given by way of illustration only and are not intended to limit the invention.

According to a first aspect of the invention, there is provided a method of reducing the temperature of a high pressure depropanizer drum of an ethylene plant, the method comprising; the tower top material of the high-pressure depropanizing tower is heated, compressed, hydrogenated by carbon and cooled, and then enters a reflux tank of the high-pressure depropanizing tower, the gas in the reflux tank of the high-pressure depropanizing tower enters a deep cooling system of the demethanizing tower, and then enters a pre-demethanizing tower after being cooled, the liquid in the reflux tank of the high-pressure depropanizing tower refluxes to the high-pressure depropanizing tower, the tower bottom material of the pre-demethanizing tower is sent to a deethanizing tower, the gas phase at the tower top is sent to the demethanizing tower, and the three parts of the tower bottom material mixed carbon of the deethanizing tower are introduced into the high-pressure depropanizing tower, so that the tower bottom temperature of the high-pressure depropanizing tower is controlled below 80 ℃.

In the present invention, the introduction position of the mixed carbon three on the high-pressure depropanizer can be one or more, for example, at least one of a tower still, a stripping section, a rectifying section, a feed line and a reflux line.

According to the invention, the operation pressure of the deethanizer can be 2.36MPaG, the temperature at the top of the tower can be-15.9 ℃, the temperature at the bottom of the tower can be 59.5 ℃, the material component at the top of the tower is carbon two, the material component at the bottom of the tower is mixed carbon three, and the material at the bottom of the tower is cooled to 43 ℃ by cooling water and then is sent to a carbon three hydrogenation reaction system. The mixed carbon three contains propylene and propane, specifically, propylene 91.94 mol%, and propane 6.81 mol%.

The process parameters which are not limited in the invention can be set conventionally according to the prior art, for example, the operation parameters of the high-pressure depropanizer belong to the conventional technical means.

According to a second aspect of the present invention, there is provided an apparatus for reducing the temperature of a high pressure depropanizer drum of an ethylene plant as described above, the device comprises a high-pressure depropanizing tower and a deethanizing tower, wherein the top of the high-pressure depropanizing tower is provided with a first reflux pipeline, according to the material flow direction, a heater, a cracking gas compressor, a carbon dioxide hydrogenation system, a cooler and a high-pressure depropanizing tower reflux tank are sequentially arranged on the first reflux pipeline, the gas outlet of the reflux tank of the high-pressure depropanizing tower is connected with the feed inlet of the pre-demethanizing tower through a demethanizing tower cryogenic system, the tower kettle discharge pipeline of the pre-demethanizer is connected with the feed inlet of the deethanizer, the tower top discharge pipeline of the pre-demethanizer is connected with the feed inlet of the demethanizer, and a mixed carbon three-introducing pipeline connected with the high-pressure depropanizing tower is arranged on a tower kettle discharging pipeline of the deethanizing tower.

In the invention, the discharge end of the mixed carbon three introduction pipeline is connected with at least one of a tower kettle, a stripping section, a rectifying section, a feeding pipeline and a reflux pipeline of the high-pressure depropanizing tower.

Preferably, a flow meter and a regulating valve are arranged on the mixed carbon three introducing pipeline. And specifically adjusting the flow of the mixed carbon III according to the temperature of the high-pressure depropanizing tower.

In the invention, the mixed carbon three introducing pipeline is required to have a proper size, and the mixed carbon three introducing pipeline cannot meet the requirement of long-period safe and stable operation due to too large or too small size. The size of the mixed carbon III introducing pipeline is not suitable to be too large so as to prevent excessive injection of the mixed carbon III, which causes that the temperature of the high-pressure depropanizing tower is lower, the content of light components in the tower exceeds the standard, the separation effect of the tower is deteriorated, and the operation and the product quality are influenced. Similarly, the size of the mixed carbon three introducing pipeline is not suitable to be too small so as to prevent the mixed carbon three from injecting insufficient flow and unobvious effect, which causes the phenomena of high temperature of the high-pressure depropanizing tower kettle, coking and blockage of the tower plate and the tower kettle reboiler and influences the operation of the tower. Preferably, the mixed carbon three introduction line has a size of 2 ".

According to the invention, the middle part of the high-pressure depropanizing tower is provided with a feeding pipeline, and the tower kettle is provided with a high-pressure depropanizing tower reboiler and a tower kettle discharging pipeline.

In the invention, a feed inlet is arranged in the middle of the deethanizer, a deethanizer reboiler is arranged at the tower bottom, a second return pipeline is arranged at the tower top, and a deethanizer top cooler, a deethanizer return tank and a deethanizer return pump are sequentially arranged on the second return pipeline along the material flow direction.

Components of the system which are not limited in the invention can be selected conventionally according to the prior art, and belong to the conventional technical means.

The invention provides a flexible adjustment means, which controls the kettle temperature of the high-pressure depropanizing tower by additionally arranging a mixed carbon three introduction pipeline, so that the operation of the high-pressure depropanizing tower reaches the designed temperature, and simultaneously, the separation effect of the high-pressure depropanizing tower is ensured. If the kettle temperature of the high-pressure depropanizing tower is higher in the production operation process, the operation of adjusting the opening degree of the valve on the added mixed carbon three introducing pipeline is implemented to increase the flow of the carbon three material flow and further reduce the tower kettle temperature of the high-pressure depropanizing tower. Even if the heating quantity of the reboiler is slightly increased in the production operation process, the tower kettle is not over-heated, so that the tower plate and the reboiler are not coked and blocked while the product purity of the tower kettle is ensured.

The present invention will be described in detail by way of examples.

Examples

This example illustrates the process and apparatus of the present invention for reducing the temperature in the high pressure depropanizer drum of an ethylene plant.

As shown in fig. 3, the present invention provides a method for reducing the temperature of a high pressure depropanizer drum of an ethylene plant, the method comprising; the tower top material of the high-pressure depropanizing tower is heated, compressed, hydrogenated by carbon and cooled, and then enters a reflux tank of the high-pressure depropanizing tower, the gas in the reflux tank of the high-pressure depropanizing tower enters a deep cooling system of the demethanizing tower, and then enters a pre-demethanizing tower after being cooled, the liquid in the reflux tank of the high-pressure depropanizing tower refluxes to the high-pressure depropanizing tower, the tower bottom material of the pre-demethanizing tower is sent to a deethanizing tower, the gas phase at the tower top is sent to the demethanizing tower, and the three parts of the tower bottom material mixed carbon of the deethanizing tower are introduced into the high-pressure depropanizing tower, so that the tower bottom temperature of the high-pressure depropanizing tower is controlled below 80 ℃. The introducing position of the mixed carbon III on the high-pressure depropanizing tower is a feeding pipeline and a return pipeline. The operation pressure of the deethanizer is 2.36MPaG, the temperature at the top of the tower is-15.9 ℃, the temperature at the bottom of the tower is 59.5 ℃, and the material mixed carbon III at the bottom of the tower is partially introduced into a feed pipeline and/or a reflux pipeline after being cooled to 43 ℃ by cooling water. Mixed carbon three contained 91.94 mol% propylene and 6.81 mol% propane.

The device adopted by the method for reducing the temperature of the high-pressure depropanizing tower of the ethylene device comprises a high-pressure depropanizing tower 11 and a depropanizing tower 17, wherein the top of the high-pressure depropanizing tower 11 is provided with a first reflux pipeline, a heater 28, a cracked gas compressor (5 sections) 12, a carbon dioxide hydrogenation system 13, a cooler 29 and a high-pressure depropanizing tower reflux tank 30 are sequentially arranged on the first reflux pipeline according to the material flow direction, a gas outlet of the high-pressure depropanizing tower reflux tank 30 is connected with a feed inlet of a pre-demethanizing tower 16 through a demethanizing tower cryogenic system 14, a tower bottom discharge pipeline of the pre-demethanizing tower 16 is connected with a feed inlet of the deethanizing tower 17, a tower top discharge pipeline of the pre-demethanizing tower 16 is connected with a feed inlet of a demethanizing tower 39, a mixed carbon three-introduction pipeline connected with the high-pressure depropanizing tower 11 is arranged on the tower bottom discharge pipeline of the deethanizing tower 17, the mixed carbon three introduction line includes a first mixed carbon three introduction line 37 and a second mixed carbon three introduction line 38. The discharge end of the first mixed carbon three introduction line 37 is connected to the feed line of the high-pressure depropanizer 11, and the discharge end of the second mixed carbon three introduction line 38 is connected to the reflux line of the high-pressure depropanizer 11.

The first mixed carbon three introducing pipeline 37 and the second mixed carbon three introducing pipeline 38 are both provided with a flowmeter and a regulating valve (not shown), the normal total flow of the two introducing pipelines is 6000kg/h, and the maximum total flow is 8100 kg/h. The first mixed carbon three introduction line 37 and the second mixed carbon three introduction line 38 have a size of 2 ".

The middle part of the high-pressure depropanizing tower 11 is provided with a feeding pipeline 27, and the tower kettle is provided with a high-pressure depropanizing tower reboiler 32 and a tower kettle discharging pipeline.

A feed inlet (not shown) is formed in the middle of the deethanizer 17, a deethanizer reboiler 33 is arranged at the tower bottom, a second return pipeline is arranged at the tower top, and a deethanizer top cooler 34, a deethanizer return tank 35 and a deethanizer return pump 36 are sequentially arranged on the second return pipeline along the material flow direction.

The embodiment is only exemplified by the introduction of mixed carbon three through the feed line 27 and the first reflux line, and the other locations of introduction into the high pressure depropanizer 1 are similar and not enumerated.

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the illustrated embodiments.