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CN111747815B - Separation method of product gas of oxidative coupling reaction of methane - Google Patents

Separation method of product gas of oxidative coupling reaction of methane Download PDF

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Publication number
CN111747815B
CN111747815B CN201910239562.4A CN201910239562A CN111747815B CN 111747815 B CN111747815 B CN 111747815B CN 201910239562 A CN201910239562 A CN 201910239562A CN 111747815 B CN111747815 B CN 111747815B
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methane
product gas
separation
coupling reaction
oxidative coupling
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CN111747815A (en
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孙丽丽
刘罡
赵百仁
盛在行
王振维
聂毅强
李少鹏
丁利伟
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China Petroleum and Chemical Corp
Sinopec Engineering Inc
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China Petroleum and Chemical Corp
Sinopec Engineering Inc
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    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07CACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C7/00Purification; Separation; Use of additives
    • C07C7/005Processes comprising at least two steps in series
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P30/00Technologies relating to oil refining and petrochemical industry
    • Y02P30/40Ethylene production

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  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
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  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

The invention belongs to the field of petrochemical industry, and particularly relates to a separation method of a product gas of a methane oxidative coupling reaction. The product gas of the oxidative coupling reaction of methane contains hydrogen, methane, CO and CO 2 Ethylene, ethane, hydrocarbons of three and above carbons, and optionally acetylene, sulfur oxides, nitrogen oxides; the separation method comprises the steps of quenching and cooling the product gas, boosting pressure for the first time, washing with amine, washing with alkali, boosting pressure for the second time, cooling for the second time, rectifying to remove light components, refrigerating by an expander, exchanging heat with the product gas, separating methane and CO by pressure swing adsorption, separating carbon dioxide from carbon III and heavier components, and refining the carbon dioxide component. Compared with the prior art, the process flow of the invention is simple, especially the number of cold boxes is reduced, a complex heat exchange network is avoided, and the energy consumption and the equipment investment are reduced.

Description

Separation method of product gas of oxidative coupling reaction of methane
Technical Field
The invention belongs to the field of petrochemical industry, and particularly relates to a separation method of a product gas of a methane oxidative coupling reaction.
Background
Ethylene is one of the chemical products with the largest output in the world, the ethylene industry is the core of the petrochemical industry, and the ethylene product accounts for more than 75 percent of petrochemical products and plays an important role in national economy. Ethylene production has been used worldwide as one of the important indicators for the development of petrochemical in one country.
With the large fluctuation of the international crude oil price and the technical progress, in order to change the condition that the raw materials for producing ethylene depend on petroleum resources excessively, the raw materials for producing ethylene are changed, and the technology for producing ethylene by taking methanol as the raw material is developed and becomes a technology with wide industrial application in the novel coal chemical industry technology.
The technology for preparing ethylene by Oxidative Coupling of Methane (OCM) is an important technology for producing ethylene, takes natural gas as a raw material, can prepare ethylene by only one-step reaction process, and has high theoretical value and economic value. After more than 30 years of research, the research on the ethylene preparation by the methane one-step method has made a breakthrough, and the industrial demonstration device for preparing ethylene by methane coupling is successfully put into production, which is the way to the beginning of industrialization. The method has great significance for breaking the bottleneck of raw material sources in the ethylene industry, reducing the production cost and enhancing the competitiveness of the ethylene industry and downstream industries.
Research and development at home and abroad are most typical of Siluria technology company in the United states, and the Siluria develops an industrially feasible methane direct ethylene catalyst by precisely synthesizing a nanowire catalyst by using a biological template. The catalyst can efficiently catalyze methane to be converted into ethylene under the condition of 200-300 ℃ lower than the operation temperature of the traditional steam cracking method and under the pressure of 5-10 atmospheric pressures. The technology prolongs the service life of the catalyst, greatly reduces the operation temperature, but has no substantial breakthrough on the conversion rate of methane and the yield of ethylene.
The separation method of the product gas of the methane oxidative coupling reaction is an important part in the OCM process, and the product gas is separated by adopting a multi-stage cold box in the prior art, so that the process method is complex and has high energy consumption. The industrialization of the OCM process is greatly limited by the economical efficiency of practical application, so that the development of a low-energy-consumption separation method for the product gas of the oxidative coupling reaction of methane is of great significance.
Disclosure of Invention
The invention aims to provide a method for separating a product gas of a methane oxidative coupling reaction. In particular to a technical scheme for separating components such as high value-added hydrocarbons, such as ethylene, and the like in methane coupling reaction product gas, which has the advantages of reliability, low energy consumption and simple process flow.
In order to achieve the above object, the present invention provides a method for separating a product gas of oxidative coupling of methane, which contains hydrogen, methane, CO, and CO 2 Ethylene, ethane, hydrocarbons of three and more carbons, and optionally acetylene, sulfur oxides, nitrogen oxides;
the separation method comprises the steps of quenching and cooling the product gas, boosting pressure for the first time, washing with amine, washing with alkali, boosting pressure for the second time, cooling for the second time, rectifying to remove light components, refrigerating by an expander, exchanging heat with the product gas, separating methane and CO by pressure swing adsorption, separating carbon dioxide from carbon III and heavier components, and refining the carbon dioxide component.
According to the present invention, preferably, the light components include hydrogen, methane and CO.
According to a particular embodiment of the invention, the separation method comprises the following steps:
(1) Quenching and cooling the product gas through a quenching unit, wherein the product gas generates steam and is cooled to a gas phase at the temperature of 30-50 ℃;
(2) The gas phase from the quenching unit is subjected to primary pressure increase to 1.0-2.5 MPaG through a compressor;
(3) Removing CO in the product gas from the gas phase after pressure boosting according to the sequence of amine washing and alkali washing 2 And sulfur oxides to obtain CO 2 A gas phase having a sulfur oxide concentration in the range of 1 to 20 ppm;
(4) The gas phase obtained in the step (3) is subjected to secondary pressure boosting by a compressor to 3.0-4.5 MPaG;
(5) The boosted gas phase enters a cold separation unit for secondary cooling, separation of hydrogen, methane, CO and carbon dioxide and heavier components is realized in the cold separation unit, the operation in the cold separation unit comprises the steps of gradually reducing the temperature of the gas phase by using a cold box or/and a heat exchanger, the cooled material is refrigerated by using an expander after hydrogen, methane and CO are removed from the top of the tower in a demethanizer, and the obtained cold energy is used for exchanging heat with the product gas to reduce the temperature of the product gas; then the separation of methane, hydrogen and CO is realized through pressure swing adsorption operation;
(6) The carbon dioxide, the carbon III and heavier components obtained in the cold separation unit are separated from the carbon III and heavier components through a deethanizer, and the carbon dioxide component is subjected to selective hydrogenation to remove acetylene hydrocarbon and then subjected to rectification operation to obtain polymer-grade ethylene.
According to the invention, preferably, the quenching and cooling process utilizes the heat of the product gas to generate 0.2-5.0 MPaG steam, and the steam generator is in one stage or multiple stages.
According to the invention, preferably, the methane obtained by pressure swing adsorption separation is recycled to the upstream oxidative coupling reaction system to participate in the reaction again.
According to the present invention, it is preferred that the operating pressure of the demethanizer is 3.0 to 4.5MPaG and the overhead temperature is-70 ℃ to-102 ℃.
According to the present invention, preferably, a benzene removal step is provided in the primary pressure increasing and/or secondary pressure increasing process of the product gas to control the benzene content entering the downstream process.
According to the present invention, preferably, the expander is a gas expander.
According to the present invention, it is preferred that the expander refrigerant outlet pressure is in the range of 0.05 to 1.0MPaG.
According to the present invention, it is preferred that ethane obtained during the purification of the carbon two component is fed back to the upstream oxidative coupling reaction system to participate in the reaction.
The invention has the beneficial effects that:
(1) The heat of the methane oxidative coupling product gas is fully utilized, and the utilization efficiency of the device on the heat is effectively improved.
(2) By adopting cryogenic separation and low-temperature expansion processes, the loss of ethylene is less, and the energy consumption is saved.
(3) The pressure swing adsorption is adopted to separate methane and CO, so that unreacted methane is fully recovered, the purity is high, and the material utilization efficiency is improved, which is difficult to realize through the separation of a multi-stage cold box in the prior art.
(4) The gas expander is adopted, so that a liquid-containing expander adopted in the prior art is avoided, the efficiency can be improved, and the cost is reduced.
(5) Compared with the prior art, the process flow of the invention is simple, especially the number of cold boxes is reduced, a complex heat exchange network is avoided, and the overall energy consumption and equipment investment are reduced.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings.
FIG. 1 shows a schematic flow diagram of a process for the separation of product gas from the oxidative coupling of methane reaction according to the present invention.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein.
Example 1
As shown in fig. 1, the separation system comprises, connected in series: the system comprises a quenching unit, a first compressor, a washing unit, a second compressor, a cold separation unit, a gas-phase expansion machine, a pressure swing adsorption separation unit, a deethanizer and an ethylene rectifying tower, wherein the quenching unit is a quenching water circulation established by a quenching water tower, the washing unit comprises an amine washing tower and an alkaline washing tower which are sequentially connected, the cold separation unit comprises a heat exchanger and a demethanizer which are sequentially connected, the top of the demethanizer is connected with the expansion machine, and the bottom of the tower is connected with the deethanizer.
The product gas of the oxidative coupling reaction of methane contains hydrogen, methane, CO and CO 2 Ethylene, ethane, hydrocarbons of three and above carbons, and optionally acetylene, sulfur oxides, nitrogen oxides.
The separation method comprises the following steps:
(1) Quenching and cooling the product gas through a quenching unit, wherein the product gas generates steam and is cooled to a gas phase at the temperature of 30-50 ℃; the heat of the product gas is utilized to generate 0.2-5.0 MPaG steam, and a steam generator can be in one stage or multiple stages;
(2) The gas phase from the quenching unit is subjected to primary pressure increase to 1.0-2.5 MPaG through a compressor;
(3) Removing CO in the product gas from the gas phase after pressure boosting according to the sequence of amine washing and alkali washing 2 And sulfur oxides to obtain CO 2 A gas phase having a sulfur oxide concentration in the range of 1 to 20 ppm;
(4) The gas phase obtained in the step (3) is subjected to secondary pressure boosting by a compressor to 3.0-4.5 MPaG; a benzene removal step is arranged in the secondary pressure boosting process, and the content of benzene entering a downstream process is controlled;
(5) The gas phase after secondary pressure rise enters a cold separation unit for secondary temperature reduction, separation of hydrogen, methane, CO and carbon dioxide and heavier components is realized in the cold separation unit, the cold separation unit comprises a heat exchanger and a demethanizer, the operation in the cold separation unit comprises that the temperature of the gas phase is reduced by using the heat exchanger, the cooled material is refrigerated by using an expander after hydrogen, methane and CO are removed from the top of the tower in the demethanizer, and the material refrigerated by the expander enters the heat exchanger to exchange heat with the product gas so as to reduce the temperature of the product gas; then the separation of methane, hydrogen and CO is realized through pressure swing adsorption operation, and the methane obtained by separation circulates back to the upstream oxidation coupling reaction system to participate in the reaction again; the separation of hydrogen, methane, CO and carbon dioxide and heavier components is realized by using a single rectifying tower (a demethanizer), the operating pressure of the demethanizer is 3.0-4.5 MPaG, and the temperature of the top of the tower is-70 ℃ to-102 ℃; the pressure of the refrigerating outlet of the expansion machine is 0.05-1.0 MPaG;
(6) The carbon dioxide and the carbon three and heavier components obtained in the cold separation unit are separated through a deethanizer, the carbon dioxide and the carbon three and heavier components are obtained from the carbon dioxide component obtained from the tower top, acetylene hydrocarbon is removed through selective hydrogenation, the carbon three and heavier components are obtained from the tower bottom, the ethylene rectifying tower is subjected to rectifying operation, polymerization-grade ethylene is obtained from the tower top, ethane is obtained from the tower bottom, and the ethane is sent back to an upstream oxidation coupling reaction system to participate in the reaction.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims (8)

1. The method for separating the product gas of the oxidative coupling reaction of methane is characterized in that the product gas of the oxidative coupling reaction of methane contains hydrogen, methane, CO and CO 2 Ethylene, ethane, hydrocarbons of three and more carbons, and optionally acetylene, sulfur oxides, nitrogen oxides;
the separation method comprises the following steps:
(1) Quenching and cooling the product gas through a quenching unit, wherein the product gas generates steam and is cooled to a gas phase at the temperature of 30-50 ℃;
(2) The gas phase from the quenching unit is subjected to primary pressure increase to 1.0-2.5 MPaG through a compressor;
(3) Removing CO in the product gas from the pressurized gas phase according to the sequence of amine washing and alkali washing 2 And sulfur oxides to obtain CO 2 A gas phase having a sulfur oxide concentration in the range of 1 to 20 ppm;
(4) The gas phase obtained in the step (3) is subjected to secondary pressure boosting through a compressor to 3.0-4.5 MPaG;
(5) The boosted gas phase enters a cold separation unit for secondary cooling, the separation of hydrogen, methane, CO and carbon dioxide and heavier components is realized in the cold separation unit, the operation in the cold separation unit comprises the steps of gradually reducing the temperature of the gas phase by using a cold box or/and a heat exchanger, the cooled material is refrigerated by using an expander after hydrogen, methane and CO are removed from the top of the tower in a demethanizer, and the obtained cold energy is used for exchanging heat with the product gas to reduce the temperature of the product gas; then the separation of methane, hydrogen and CO is realized through pressure swing adsorption operation;
(6) The carbon dioxide, the carbon III and heavier components obtained in the cold separation unit are separated from the carbon III and heavier components through a deethanizer, and the carbon dioxide component is subjected to selective hydrogenation to remove acetylene hydrocarbon and then subjected to rectification operation to obtain polymer-grade ethylene.
2. The separation method according to claim 1, wherein the quenching and cooling process utilizes the heat of the product gas to generate 0.2-5.0 MPaG steam, and the steam generator is one or more stages.
3. The separation method according to claim 1, wherein the methane obtained by pressure swing adsorption separation is recycled to the upstream oxidative coupling reaction system to participate in the reaction again.
4. The separation process of claim 1, wherein the demethanizer is operated at a pressure of 3.0 to 4.5MPaG and an overhead temperature of-70 ℃ to-102 ℃.
5. The separation process of claim 1, wherein a benzene removal step is provided during the primary and/or secondary pressure increase of the product gas to control the benzene content entering the downstream process.
6. The separation process of claim 1, wherein the expander is a gas expander.
7. The separation process of claim 1, wherein the expander refrigerant outlet pressure is in the range of 0.05 to 1.0MPaG.
8. The separation method according to claim 1, wherein ethane obtained in the refining of the carbon two component is fed back to the upstream oxidative coupling reaction system to participate in the reaction.
CN201910239562.4A 2019-03-27 2019-03-27 Separation method of product gas of oxidative coupling reaction of methane Active CN111747815B (en)

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CN114736095B (en) * 2022-05-12 2024-06-25 中海石油气电集团有限责任公司 A method for producing hydrogen and olefins by catalytic oxidation of natural gas

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WO2016205411A2 (en) * 2015-06-16 2016-12-22 Siluria Technologies, Inc. Ethylene-to-liquids systems and methods
CN106831291A (en) * 2017-01-05 2017-06-13 中石化上海工程有限公司 The method of Catalyst for Oxidative Coupling of Methane
CN106831292A (en) * 2017-01-05 2017-06-13 中石化上海工程有限公司 The separating technology of Catalyst for Oxidative Coupling of Methane product
CN108017499A (en) * 2016-11-01 2018-05-11 中国石油化工股份有限公司 A kind of utilization system and method for comprehensive utilization of methanol to olefins reaction product

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US9701597B2 (en) * 2014-01-09 2017-07-11 Siluria Technologies, Inc. Oxidative coupling of methane implementations for olefin production

Patent Citations (5)

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Publication number Priority date Publication date Assignee Title
CN106068323A (en) * 2014-01-08 2016-11-02 希路瑞亚技术公司 Ethylene to liquid system and method
WO2016205411A2 (en) * 2015-06-16 2016-12-22 Siluria Technologies, Inc. Ethylene-to-liquids systems and methods
CN108017499A (en) * 2016-11-01 2018-05-11 中国石油化工股份有限公司 A kind of utilization system and method for comprehensive utilization of methanol to olefins reaction product
CN106831291A (en) * 2017-01-05 2017-06-13 中石化上海工程有限公司 The method of Catalyst for Oxidative Coupling of Methane
CN106831292A (en) * 2017-01-05 2017-06-13 中石化上海工程有限公司 The separating technology of Catalyst for Oxidative Coupling of Methane product

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