CN-116496820-B - Recovery method and recovery system for refinery dry gas

CN116496820BCN 116496820 BCN116496820 BCN 116496820BCN-116496820-B

Abstract

The application provides a recovery method and a recovery system for refinery dry gas, comprising the following steps of carrying out primary rectification separation on the refinery dry gas to obtain first liquid and first gas; the method comprises the steps of rectifying and separating the first gas for the second time to obtain ethane and second gas, washing the second gas at low temperature to obtain second liquid and hydrogen-rich gas, and purifying the hydrogen-rich gas to obtain a pure hydrogen product. According to the application, by utilizing the difference of the boiling points of the gases in the refinery dry gas, the refinery dry gas is subjected to repeated rectification separation, low-temperature washing and purification treatment, so that other components except hydrogen in the refinery dry gas are gradually removed, and the recovery rate and recovery purity of the hydrogen are improved. In addition, the refinery dry gas is subjected to multiple rectification separation, low-temperature washing and purification treatment, so that the effective components in the refinery dry gas can be purified and utilized in a quality-dividing way, and the effective components are used as chemical raw materials or products and fully utilized, thereby increasing the economic benefit of the refinery dry gas.

Inventors

SONG XIPING
LIU YING
WEI LONG
GUO XIA

Assignees

深圳华盈工业科技有限公司

Dates

Publication Date: 20260505
Application Date: 20230309

Claims (7)

1. A method for recovery of refinery dry gas comprising: pressurizing the refinery dry gas, and performing impurity removal treatment on the pressurized refinery dry gas to remove acidic impurities in the refinery dry gas; carrying out dehydration treatment on the refinery dry gas after removing the acidic impurities to obtain purified dry gas; performing primary heat exchange on the purified dry gas to reduce the temperature of the purified dry gas, wherein the purified dry gas is kept in a gas state; Carrying out first rectification separation on the purified dry gas to obtain first liquid and first gas; conveying a first heat exchange medium subjected to first heat exchange with the purified dry gas into an ethane tower, and conveying the first gas into the ethane tower, so that the first heat exchange medium exchanges heat with the first gas in the ethane tower, and the first gas is subjected to second rectification separation to obtain ethane and second gas; washing the second gas at a low temperature to obtain a second liquid and hydrogen-rich gas; and purifying the hydrogen-rich gas to obtain a pure hydrogen product.
2. The method for recovering dry gas from a refinery according to claim 1, further comprising, after the step of subjecting the dry gas from the refinery to the first rectifying separation to obtain the first liquid and the first gas: And carrying out third rectification separation on the first liquid to obtain light oil and liquefied petroleum gas.
3. The method for recovering dry gas from a refinery according to claim 1, further comprising, before said step of subjecting said first gas to a second rectifying separation to obtain ethane and a second gas: and performing second heat exchange and first gas-liquid separation on the first gas to remove the first liquid in the first gas.
4. The method for recovering dry gas from a refinery according to claim 1, further comprising, before the step of subjecting said second gas to a low temperature washing to obtain a second liquid and a hydrogen-rich gas: and performing third heat exchange and second gas-liquid separation on the second gas to remove ethane in the second gas.
5. The method for recovering dry gas from a refinery according to claim 4, further comprising, after the step of performing the third heat exchange and the second gas-liquid separation on the second gas to remove ethane in the second gas: performing fourth heat exchange on the second gas to reduce the temperature of the second gas, wherein the second gas can be kept in a gas state; And/or carrying out fifth heat exchange on the second gas and the nitrogen circulation refrigerating device so as to reduce the temperature of the second gas, wherein the second gas can be kept in a gas state.
6. The method for recovering dry gas from a refinery according to any one of claims 1 to 5, further comprising, after the step of subjecting the second gas to low temperature washing to obtain a second liquid and a hydrogen-rich gas: And carrying out fourth rectification separation on the second liquid to obtain methane and fuel gas.
7. The recovery system for the refinery dry gas is characterized by comprising a deethanizer, an ethane tower, a low-temperature washing tower and a pressure swing adsorption device, wherein the deethanizer, the ethane tower, the low-temperature washing tower and the pressure swing adsorption device are correspondingly communicated in sequence, the deethanizer is used for carrying out first rectification separation on the refinery dry gas to obtain first liquid and first gas, the ethane tower is used for carrying out second rectification separation on the first gas to obtain ethane and second gas, the low-temperature washing tower is used for carrying out low-temperature washing on the second gas to obtain second liquid and hydrogen-rich gas, and the pressure swing adsorption device is used for carrying out purification treatment on the hydrogen-rich gas to obtain a pure hydrogen product.

Description

Recovery method and recovery system for refinery dry gas Technical Field The invention relates to the technical field of low-temperature separation of refinery dry gas, in particular to a recovery method and a recovery system for the refinery dry gas. Background The refinery dry gas refers to non-condensed gas (also called distilled gas) generated and recovered in the refinery process, and the main components of the non-condensed gas are hydrogen, ethylene, propylene, methane, ethane, propane, butane and the like, and the refinery dry gas mainly comes from the secondary processing process of crude oil, such as heavy oil catalytic cracking, thermal cracking, delayed coking and the like. Although the light hydrocarbon and the hydrogen in the refinery dry gas have higher utilization value, the light hydrocarbon and the hydrogen are usually sent into a gas pipe network to be used as fuel gas, and some of the fuel gas is even put into a torch to be burnt, so that the great waste of resources is caused. Along with continuous production of a refinery hydrogenation device, the demand of the refinery for hydrogen is increased increasingly, and if high-added-value hydrogen in refinery dry gas is recovered, the hydrogen product can fill the defects and shortage of refinery oil upgrading and structure optimizing processes. In addition, other effective components in the hydrogen-rich tail gas are utilized in quality division, so that considerable economic benefits can be brought to enterprises. The hydrogen energy source is used as a novel energy source and has the advantages of high heat value, green, no pollution and the like. The traditional recovery method mainly adopts a pressure swing adsorption technology and a membrane separation technology. However, the recovery rate and purity of hydrogen in the traditional recovery method are low. Disclosure of Invention Based on this, it is necessary to provide a recovery method and recovery system for refinery dry gas, aiming at the problem of low recovery rate and purity of hydrogen in the conventional recovery method. The technical scheme is as follows: in one aspect, a method for recovery of refinery dry gas is provided, comprising: carrying out primary rectification separation on refinery dry gas to obtain first liquid and first gas; Carrying out secondary rectification separation on the first gas to obtain ethane and second gas; washing the second gas at a low temperature to obtain a second liquid and hydrogen-rich gas; and purifying the hydrogen-rich gas to obtain a pure hydrogen product. The technical scheme is further described as follows: in one embodiment, in the step of performing a first rectification separation on refinery dry gas to obtain a first liquid and a first gas, the method comprises: pressurizing the refinery dry gas, and performing impurity removal treatment on the pressurized refinery dry gas to remove acidic impurities in the refinery dry gas; carrying out dehydration treatment on the refinery dry gas after removing the acidic impurities to obtain purified dry gas; and carrying out first rectification separation on the purified dry gas to obtain first liquid and first gas. In one embodiment, before the step of subjecting the purified dry gas to first rectification separation to obtain the first liquid and the first gas, the method further comprises: and carrying out first heat exchange on the purified dry gas to reduce the temperature of the purified dry gas, wherein the purified dry gas is kept in a gas state. In one embodiment, in the step of performing a second rectification separation on the first gas to obtain ethane and a second gas, the method comprises: And conveying a first heat exchange medium after the first heat exchange with the purified dry gas to an ethane tower, and conveying the first gas to the ethane tower, so that the first heat exchange medium exchanges heat with the first gas in the ethane tower, and the first gas is subjected to second rectification separation to obtain the ethane and the second gas. In one embodiment, after the step of performing the first rectifying separation on the refinery dry gas to obtain the first liquid and the first gas, the method further comprises: And carrying out third rectification separation on the first liquid to obtain light oil and liquefied petroleum gas. In one embodiment, before the step of subjecting the first gas to a second rectification separation to obtain ethane and a second gas, the method further comprises: and performing second heat exchange and first gas-liquid separation on the first gas to remove the first liquid in the first gas. In one embodiment, before the step of subjecting the second gas to low temperature scrubbing to obtain a second liquid and a hydrogen-rich gas, the method further comprises: and performing third heat exchange and second gas-liquid separation on the second gas to remove ethane in the second gas. In one embodiment, after the step of performing the thi