CN111747806A

CN111747806A - Method for preventing oxidation coupling process from generating tempering

Info

Publication number: CN111747806A
Application number: CN201910239558.8A
Authority: CN
Inventors: 李少鹏; 聂毅强; 丁利伟; 王振维; 盛在行; 刘罡; 孙丽丽; 赵百仁
Original assignee: China Petroleum and Chemical Corp; Sinopec Engineering Inc
Current assignee: China Petroleum and Chemical Corp; Sinopec Engineering Inc
Priority date: 2019-03-27
Filing date: 2019-03-27
Publication date: 2020-10-09
Anticipated expiration: 2039-03-27
Also published as: CN111747806B

Abstract

The invention belongs to the field of petrochemical industry, and relates to a method for preventing an oxidative coupling process from generating tempering. Mixing the methane-rich gas and the oxygen-rich gas to obtain mixed gas, and allowing the mixed gas to enter a reactor for oxidation coupling reaction to generate ethylene-containing product gas; the time for the mixed gas to pass through the reactor bed layer is longer than the induction time of the mixed gas. The invention can reduce the oxygen concentration of the system to be below the maximum allowable oxygen concentration under the abnormal working condition, thereby avoiding the occurrence of fire and explosion.

Description

Method for preventing oxidation coupling process from generating tempering

Technical Field

The invention belongs to the field of petrochemical industry, and particularly relates to a method for preventing an oxidative coupling process from generating tempering.

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.

Disclosure of Invention

The invention aims to provide a method for preventing the oxidation coupling process from generating tempering. The method can avoid backfire, and the supplemented inert gas can also reduce the oxygen concentration of the system and reduce the risk of fire and explosion.

In order to achieve the aim, the invention provides a method for preventing an oxidative coupling process from generating tempering, which comprises the steps of mixing methane-rich gas and oxygen-rich gas to obtain mixed gas, and enabling the mixed gas to enter a reactor for an oxidative coupling reaction to generate a product gas containing ethylene; the time for the mixed gas to pass through the reactor bed layer is longer than the induction time of the mixed gas.

In the present invention, the term induction time means: the explosive mixture explodes after a certain time after reaching a certain temperature, and the delay period is called induction time, induction period and explosion delay period. For the oxidative coupling reaction, the induction time of the mixed gas is 20-2 s, preferably 20-40 ms.

In the present invention, the time for the mixed gas to pass through the reactor bed is not particularly limited as long as it is longer than the above-mentioned induction time.

According to the invention, the methane-rich gas feed line is preferably provided with one of the following flashback-preventing structures in series or in parallel: fire arrestor, emergency cut-off valve, governing valve.

According to the invention, the sensors in the quick action emergency valve are preferably pressure and/or temperature sensors, the scanning time of which is 20ms to 200 ms.

According to the invention, preferably, the flame arrester is arranged close to the reactor.

According to the present invention, it is preferred that the inert gas is injected into the methane-rich gas feed line or the oxygen-rich gas feed line so that the oxygen concentration in the system is reduced below the maximum allowable oxygen concentration. The "maximum allowable oxygen concentration" varies depending on the reaction conditions, and the calculation method thereof is well known to those skilled in the art. Typically, the maximum allowable oxygen concentration in an OCM process is 3% to 50%.

Further, the inert gas is selected from at least one of nitrogen, carbon dioxide, water vapor and argon.

Preferably, according to the invention, the point of injection of the inert gas is located upstream of the flame arrester, or immediately downstream of the flame arrester.

According to the present invention, preferably, the ethylene-containing product gas comprises hydrogen, a carbon two-component, a carbon three-component and unreacted methane.

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

The invention has the beneficial effects that: the oxygen concentration of the system can be reduced to be lower than the maximum allowable oxygen concentration under the abnormal working condition, and the occurrence of fire and explosion is avoided.

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

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

A method for preventing the oxidation coupling process from generating backfire comprises the steps of mixing natural gas (wherein the content of methane is 98%) with oxygen to obtain mixed gas, enabling the mixed gas to enter a reactor to carry out oxidation coupling reaction to generate ethylene-containing product gas, wherein the ethylene-containing product gas comprises hydrogen, a carbon two component, a carbon three component and unreacted methane; the induction time of the mixed gas is 30 ms; the time for the mixed gas to pass through the reactor bed layer is more than 30 ms.

Wherein the natural gas is injected into the reactor using an emergency shut-off valve disposed proximate the reactor; the sensor in the emergency cut-off valve is a pressure sensor, and the scanning time of the sensor is 20ms to 200 ms.

Example 2

A method for preventing the oxidation coupling process from generating backfire comprises the steps of mixing natural gas (wherein the content of methane is 98%) with oxygen to obtain mixed gas, enabling the mixed gas to enter a reactor to carry out oxidation coupling reaction to generate ethylene-containing product gas, wherein the ethylene-containing product gas comprises hydrogen, a carbon two component, a carbon three component and unreacted methane; the induction time of the mixed gas is 40 ms; the time for the mixed gas to pass through the reactor bed layer is more than 40 ms.

Wherein the natural gas is injected into the reactor using a flame arrestor disposed proximate to the reactor; carbon dioxide is injected on the natural gas line at a point upstream of the flame arrestor such that the oxygen concentration in the system is reduced below the maximum allowable oxygen concentration.

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

1. A method for preventing an oxidative coupling process from generating tempering is characterized in that methane-rich gas and oxygen-rich gas are mixed to obtain mixed gas, and the mixed gas enters a reactor to perform an oxidative coupling reaction to generate a product gas containing ethylene; the time for the mixed gas to pass through the reactor bed layer is longer than the induction time of the mixed gas.

2. The method according to claim 1, wherein the induction time of the mixed gas is 20 to 2s, preferably 20 to 40 ms.

3. The method according to claim 1, characterized in that the methane-rich gas feed line is provided with one of the following flashback-preventing structures in series or in parallel: fire arrestor, emergency cut-off valve, governing valve.

4. A method according to claim 3, characterised in that the sensors in the slam shut valve are pressure and/or temperature sensors, the scanning time of which is 20 to 200 ms.

5. A method as claimed in claim 3, wherein the flame arrestor is provided adjacent to the reactor.

6. A process according to claim 3, wherein the oxygen concentration in the system is reduced to below the maximum allowable oxygen concentration by injecting an inert gas into the methane-rich gas feed line or the oxygen-rich gas feed line.

7. The method of claim 6, wherein the inert gas is selected from at least one of nitrogen, carbon dioxide, water vapor, and argon.

8. A method as claimed in claim 6, wherein the point of injection of the inert gas is located immediately upstream of, or downstream of, the flame arrestor.

9. The method of claim 1, wherein the ethylene-containing product gas comprises hydrogen, a carbon two component, a carbon three component, and unreacted methane.

10. The method according to claim 1, wherein the methane-rich gas has a methane content > 50% by volume, preferably > 90% by volume, further 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%.