阅读说明：本技术 一种用于甲烷氧化偶联的工艺 (Process for oxidative coupling of methane ) 是由 王振维 聂毅强 盛在行 孙丽丽 刘罡 丁利伟 赵百仁 李少鹏 于 2019-03-27 设计创作，主要内容包括：本发明属于石油化工领域,涉及一种用于甲烷氧化偶联的工艺。富甲烷气体与富氧气体在烷氧混合器中进行混合,得到混合气,达到反应所需温度的混合气进入装有催化剂的恒温反应器,进行甲烷氧化偶联反应,恒温反应器内设置有间隔排布的多组反应单元和多组取热单元,以及隔热结构,所述催化剂装填于反应单元内,取热介质在取热单元内流动并吸收反应单元放出的热量；所述隔热结构设置于反应单元和取热单元之间,隔热结构与反应单元的接触面的温度高于甲烷氧化偶联反应起始温度,隔热结构与取热单元的接触面与取热单元内取热介质的温差为5～50℃。本发明的方法使每段催化剂床层基本恒定,使反应在最佳温度下反应。(The invention belongs to the field of petrochemical industry, and relates to a process for oxidative coupling of methane. Mixing methane-rich gas and oxygen-rich gas in an alkane-oxygen mixer to obtain mixed gas, feeding the mixed gas reaching the temperature required by the reaction into a constant-temperature reactor filled with a catalyst for methane oxidation coupling reaction, wherein the constant-temperature reactor is internally provided with a plurality of groups of reaction units and a plurality of groups of heat taking units which are arranged at intervals, and a heat insulation structure, the catalyst is filled in the reaction units, and a heat taking medium flows in the heat taking units and absorbs heat emitted by the reaction units; the heat insulation structure is arranged between the reaction unit and the heat taking unit, the temperature of the contact surface of the heat insulation structure and the reaction unit is higher than the initial temperature of the methane oxidative coupling reaction, and the temperature difference between the contact surface of the heat insulation structure and the heat taking unit and the temperature difference between the heat taking medium in the heat taking unit is 5-50 ℃. The method of the invention ensures that each section of catalyst bed layer is basically constant, and the reaction is carried out at the optimal temperature.)

1. A process for methane oxidative coupling is characterized in that methane-rich gas and oxygen-rich gas are mixed in an alkane-oxygen mixer to obtain mixed gas, the mixed gas reaching the temperature required by reaction enters a constant-temperature reactor filled with a catalyst to perform methane oxidative coupling reaction, a plurality of groups of reaction units and a plurality of groups of heat-taking units which are arranged at intervals are arranged in the constant-temperature reactor, and a heat-insulating structure is arranged in the constant-temperature reactor, the catalyst is filled in the reaction units, and a heat-taking medium flows in the heat-taking units and absorbs heat emitted by the reaction units; the heat insulation structure is arranged between the reaction unit and the heat taking unit, the temperature of the contact surface of the heat insulation structure and the reaction unit is higher than the initial temperature of the methane oxidative coupling reaction, and the temperature difference between the contact surface of the heat insulation structure and the heat taking unit and the temperature difference between the heat taking medium in the heat taking unit is 5-50 ℃.

2. The process for oxidative coupling of methane according to claim 1, wherein the reaction unit and the heat-extracting unit are arranged in such a way that the mixed gas is co-current, counter-current or cross-current, preferably counter-current, to the heat-extracting medium.

3. The process for oxidative coupling of methane according to claim 1, wherein the heat-withdrawing medium is selected from at least one of molten salts, water, steam, hot oils, and methane-rich gases.

4. The process for oxidative coupling of methane according to claim 1, wherein the heat-extracting medium after absorption of heat is recovered in a heat recovery unit.

5. The process for oxidative coupling of methane according to claim 1, wherein the temperature required for the reaction is 450 to 950 ℃; the temperature required by the reaction is achieved by heating the mixed gas, or by separately preheating the methane-rich gas and mixing the preheated methane-rich gas with the oxygen-rich gas.

6. The process for oxidative coupling of methane according to claim 1, wherein the product gas after the oxidative coupling of methane enters the cracking unit, heat is provided for the hydrocarbons fed into the cracking unit to carry out cracking reaction, and the product gas is further cooled; the hydrocarbons fed to the cracking unit include at least one of ethane, propane, LPG and naphtha.

7. The process for oxidative coupling of methane according to claim 1, wherein the reactor outlet material enters a quench system to be cooled.

8. The process for oxidative coupling of methane according to claim 7, wherein the quench medium used by the quench system is selected from the group consisting of water, steam, nitrogen and CO₂At least one of (1).

9. The process for oxidative coupling of methane according to claim 7, wherein the quench system employs a dividing wall heat exchange or direct contact quench.

10. The process for the oxidative coupling of methane according to claim 1, wherein the methane-rich gas has a content of methane of > 50% by volume, preferably > 90% by volume, the methane-rich gas preferably being natural gas and/or shale gas; the volume content of oxygen in the oxygen-enriched gas is 12-100%.

Technical Field

The invention belongs to the field of petrochemical industry, and particularly relates to a process for oxidative coupling of methane.

Background

Ethylene is one of the chemical products with the largest yield 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 occupies an important position 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 ethylene preparation by a 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 moving towards 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 the conversion of methane 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 reactor types used in the reaction process of preparing ethylene by oxidative coupling of methane include fluidized bed reactor, fixed bed reactor, membrane reactor, etc., but the industrial application of these reactors is yet to be further developed.

Disclosure of Invention

The invention aims to provide a process for oxidative coupling of methane. The technological process of the present invention makes the catalyst bed basically constant, so that the reaction is performed at optimal temperature and the stable bed temperature is favorable to the stability of the catalyst performance.

In order to achieve the purpose, the invention provides a process for methane oxidative coupling, wherein methane-rich gas and oxygen-rich gas are mixed in an alkane-oxygen mixer to obtain mixed gas, the mixed gas reaching the temperature required by reaction enters a constant-temperature reactor filled with a catalyst to perform methane oxidative coupling reaction, a plurality of groups of reaction units and a plurality of groups of heat-taking units which are arranged at intervals and a heat-insulating structure are arranged in the constant-temperature reactor, the catalyst is filled in the reaction units, and a heat-taking medium flows in the heat-taking units and absorbs heat emitted by the reaction units; the heat insulation structure is arranged between the reaction unit and the heat taking unit, the temperature of the contact surface of the heat insulation structure and the reaction unit is higher than the initial temperature of the methane oxidative coupling reaction, and the temperature difference between the contact surface of the heat insulation structure and the heat taking unit and the temperature difference between the heat taking medium in the heat taking unit is 5-50 ℃.

The material and arrangement of the heat insulation structure are not particularly limited in the present invention, as long as the above requirements are satisfied. Various insulation structures in the art may be employed, for example, the insulation structure may use refractory materials as the primary construction material, with the refractory materials being selected such as corundum firebrick and the like.

The arrangement of the reaction unit and the heat extraction unit is not particularly limited in the present invention, and the arrangement of the reaction unit and the heat extraction unit may be such that the mixed gas and the heat extraction medium flow in parallel, in countercurrent or in cross current, preferably in countercurrent.

According to the present invention, preferably, the heat-taking medium is selected from at least one of molten salt, water, steam, hot oil, and methane-rich gas.

Further, the heat-taking medium after absorbing the heat is recovered in the heat recovery device.

According to the invention, the temperature required by the reaction is preferably 450-950 ℃, and more preferably 600-950 ℃; the heat-taking medium is preferably water and steam; and secondly molten salt.

According to the invention, the temperature required by the reaction can be achieved by heating the mixed gas, or by preheating the methane-rich gas separately and mixing the preheated methane-rich gas with the oxygen-rich gas.

According to a preferred embodiment of the present invention, the product gas after the oxidative coupling reaction of methane enters the cracking unit, and provides heat for the hydrocarbons fed into the cracking unit to perform the cracking reaction, and simultaneously the product gas is further cooled. The cracking unit can be independently arranged and is arranged at the downstream of the constant temperature reactor; or can be arranged in the constant temperature reactor and arranged at the downstream of the reaction unit and the heat extraction unit.

Further, the hydrocarbons fed to the cracking unit include at least one of ethane, propane, LPG, and naphtha. The cracking unit is preferably provided with a gas distributor to uniformly distribute the hydrocarbons fed into the cracking unit.

According to the invention, the reactor outlet material is preferably passed into a quench system to be cooled. In particular, the quench medium used in the quench system is selected from the group consisting of water, steam, nitrogen and CO₂At least one of (1). The quenching system can adopt dividing wall heat exchange cooling or direct contact cooling.

According to the present invention, preferably the methane-rich gas has a methane content of > 50% by volume, preferably > 90% by volume, preferably the methane-rich gas is natural gas and/or shale gas; the volume content of oxygen in the oxygen-enriched gas is 12-100%.

The invention has the beneficial effects that: firstly, the reaction temperature of a bed layer is constant and can be controlled at the optimal reaction temperature; secondly, the performance of the catalyst is kept stable because the bed layer basically has no temperature rise; and thirdly, the reaction is carried out under a stable condition, so that the service life of the catalyst can be prolonged.

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 of an oxidative coupling reaction in combination with a cleavage process according to the present invention.

FIG. 2 shows a schematic of another oxidative coupling reaction in combination with a cleavage process of the present invention.

Description of the reference numerals

1-methane rich gas; 2-oxygen; 3-mixed gas; 4-discharging the reaction; 5-reaction discharging after quenching; 6. feeding water to the boiler; 7. steam; 8. cracking the feedstock hydrocarbons.

11-an alkyl oxygen mixer; 12-a heater; 13-a heat removal unit; 14-a reaction unit; 15-a cleavage unit; 16-quench heat exchanger; 17-distributor.

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.

As shown in figure 1, the methane-rich gas and the oxygen-rich gas enter an alkane-oxygen mixer 11, the methane-rich gas and the oxygen-rich gas are uniformly mixed in the alkane-oxygen mixer 11, the obtained mixed gas enters a heater 12, and the materials are heated to the temperature required by the reaction in the heater 12. The heated material enters a reaction unit 14 (a plurality of which are shown only one) containing a catalyst, and in the reaction unit 14, the methane and the oxygen undergo an oxidative coupling reaction. The heat released by the reaction is taken out by the heat-taking medium in the heat-taking unit 13 (there may be a plurality, only one of which is shown in the figure). The oxidation coupling reaction discharging material leaving the reaction unit 14 enters a cracking unit 15, and in the cracking unit 15, the cracking raw material is heated by the high-temperature oxidation coupling reaction discharging material and is heated, and cracking reaction occurs; the discharge of the oxidative coupling reaction is cooled by the cracking unit 15 and then enters a quenching system for further cooling.

The present invention is illustrated in more detail by the following examples.