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CN-121988151-A - System and method for recycling hydrogen and nitrogen in flare pipe network

CN121988151ACN 121988151 ACN121988151 ACN 121988151ACN-121988151-A

Abstract

The invention discloses a system and a method for recycling hydrogen and nitrogen in a flare pipe network, which relate to the technical field of comprehensive utilization of chemical tail gas, and comprise a pretreatment module, a gas-liquid separation module, a gas separation module and a residual liquid treatment module, wherein the pretreatment module comprises a gas holder, a first driving device and an alkaline washing tower which are connected in sequence; the separation module comprises an expander and a separation tank which are sequentially connected, the expander is connected with the alkaline washing tower, the gas separation module comprises a pressure swing adsorption unit, the residual liquid treatment module comprises a vaporizer, a second driving device and a fuel gas pipe network, the vaporizer is connected with the residual liquid output end of the separation tank, and the second driving device is used for driving a medium in the residual liquid treatment module to enter the fuel gas pipe network for combustion. The technical scheme provided by the invention can solve the problems of resource waste and environmental pollution caused by discharging a large amount of hydrogen, sulfide with a certain concentration and hydrocarbon gas to a flare gas pipe network by an oil refining device and a chemical device.

Inventors

  • ZHANG FAWANG
  • CAI SHAOYONG
  • LIAN CHUANMIN
  • ZHANG YUANLI
  • CHEN YUNQING
  • DONG XIN
  • Gan Yonghao
  • RUAN JIA

Assignees

  • 中国石油天然气股份有限公司
  • 广东石化有限责任公司

Dates

Publication Date
20260508
Application Date
20241227

Claims (10)

  1. 1. A system for recovering hydrogen and nitrogen from a flare stack for recovering hydrogen and nitrogen from a feed gas comprising: the pretreatment module (1), wherein the pretreatment module (1) comprises a gas holder (11), a first driving device (12) and an alkaline washing tower (13) which are connected in sequence; The gas-liquid separation module (2) comprises an expander (21) and a separation tank (22) which are sequentially connected, and the expander (21) is connected with the alkaline washing tower (13); A gas separation module (3), the gas separation module (3) comprising a pressure swing adsorption unit (31), the pressure swing adsorption unit (31) being connected to the gas output of the separation tank (22), and The residual liquid treatment module (4), the residual liquid treatment module (4) comprises a vaporizer (41) and a second driving device (42) and a fuel gas pipe network, the vaporizer (41) is connected with the residual liquid output end of the separation tank (22), and the second driving device (42) is used for driving a medium in the residual liquid treatment module (4) to enter the fuel gas pipe network.
  2. 2. The system for recovering hydrogen and nitrogen in a flare stack of claim 1, wherein said gas separation module (3) further comprises an air separation device (32), said air separation device (32) being connected to said pressure swing adsorption unit (31).
  3. 3. The system for recovering hydrogen and nitrogen in a flare network of claim 2, wherein said gas-liquid separation module (2) further comprises a condenser (23), said condenser (23) connecting said expander (21) with said separator tank (22).
  4. 4. A system for recovering hydrogen and nitrogen from a flare stack as claimed in claim 3, wherein said first drive means (12) is a first compressor.
  5. 5. The system for recovering hydrogen and nitrogen from a flare stack of claim 4, wherein said caustic scrubber (13) is filled with an amine solution or sodium hydroxide solution.
  6. 6. The system for recovering hydrogen and nitrogen in a flare network of any one of claims 1 to 5 wherein said raffinate treatment module (4) comprises a pressure control valve (43), said pressure control valve (43) connecting said vaporizer (41) with a fuel gas network.
  7. 7. The system for recovering hydrogen and nitrogen from a flare stack of claim 6, wherein said second driving means (42) is a condensate pump (421), said condensate pump (421) being located between said separator tank (22) and said vaporizer (41).
  8. 8. The system for recovering hydrogen and nitrogen from a flare stack of claim 7, wherein said raffinate treatment module (4) further comprises a liquid level controller (44), said liquid level controller (44) being located between said condensate pump (421) and said vaporizer (41).
  9. 9. The system for recovering hydrogen and nitrogen from a flare stack of claim 6, wherein said second drive means (42) is a second compressor (422), said second compressor (422) being located between said pressure control valve (43) and said vaporizer (41).
  10. 10. A method for recovering hydrogen and nitrogen in a flare network, implemented by the system for recovering hydrogen and nitrogen in a flare network according to any one of claims 1 to 9, comprising the steps of: passing flare gas from refinery and chemical units to the pretreatment module (1); after being stored and buffered by the gas holder (11), the flare gas is pressurized by the first driving device (12) and enters the alkaline washing tower (13); after desulfurization is carried out on the flare gas in the alkaline washing tower (13), the flare gas enters the gas-liquid separation module (2) and is subjected to depressurization and temperature reduction through the expander (21), gas is condensed, and then the flare gas flows into a gas output end only containing hydrogen and nitrogen and a residual liquid output end containing a complex hydrocarbon solution through the separation tank (22) respectively; the flare gas at the gas output end is separated into high-purity hydrogen and mixed gas of hydrogen and nitrogen after passing through the pressure swing adsorption unit (31); the complex hydrocarbon solution at the output end of the residual liquid passes through the second driving device (42) and the vaporizer (41) and then enters the fuel gas pipe network.

Description

System and method for recycling hydrogen and nitrogen in flare pipe network Technical Field The invention relates to the technical field of comprehensive utilization of chemical tail gas, in particular to a system and a method for recycling hydrogen and nitrogen in a flare pipe network. Background In recent years, a large number of refinery-integrated plants are built, and various industrial equipment such as oil refining devices, ethylene cracking devices, aromatic hydrocarbon devices, polypropylene production devices and polyethylene production devices are covered in the plant area, and a large amount of waste gas is released in the production process of the equipment. Most of the waste gas can be recycled by utilizing the adsorption devices in the devices, and the residual non-condensable gas enters a flare gas pipe network and is then combusted and discharged. Because nearly half of the components in the flare gas are nitrogen, the heat value is low, and the high heat value fuel gas needs to be supplemented to the flare pipe network so as to ensure the normal combustion of the flare. The catalytic and cracking processes in the oil refining device discharge a great amount of hydrogen and sulfide (mainly H 2 S) with a certain concentration, and certain hydrocarbon gas components are discharged in the chemical device. The emptying combustion of the mixed gas not only causes energy waste, but also causes environmental pollution. Disclosure of Invention The invention mainly aims to provide a system and a method for recycling hydrogen and nitrogen in a flare gas network, and aims to solve the problems of energy waste and environmental pollution caused by discharging a large amount of hydrogen, sulfide with a certain concentration and hydrocarbon gas to the flare gas network by an oil refining device and a chemical device. The system for recycling the hydrogen and the nitrogen in the flare network comprises a pretreatment module, a gas-liquid separation module, a gas separation module and a residual liquid treatment module, wherein the pretreatment module comprises a gas holder, a first driving device and an alkaline washing tower which are sequentially connected, the separation module comprises an expander and a separation tank which are sequentially connected, the expander is connected with the alkaline washing tower, the gas separation module comprises a pressure swing adsorption unit, the pressure swing adsorption unit is connected with the gas output end of the separation tank, the residual liquid treatment module comprises a vaporizer, a second driving device and a fuel gas pipeline network, the vaporizer is connected with the residual liquid output end of the separation tank, and the second driving device is used for driving a medium in the residual liquid treatment module to enter the fuel gas pipeline network. In one embodiment, the gas separation module further comprises an air separation device coupled to the pressure swing adsorption unit. In one embodiment, the gas-liquid separation module further comprises a condenser connecting the expander and the separator tank. In one embodiment, the first driving device is a first compressor. In one embodiment, the caustic tower inner packing is amine solution or sodium hydroxide solution. In one embodiment, the raffinate treatment module comprises a pressure control valve connecting the vaporizer with a fuel gas piping network. In one embodiment, the second driving device is a condensate pump, and the condensate pump is located between the separation tank and the vaporizer. In one embodiment, the raffinate treatment module further comprises a liquid level controller located between the condensate pump and the vaporizer. In one embodiment, the second driving device is a second compressor, and the second compressor is located between the pressure control valve and the carburetor. The invention also provides a method for recycling hydrogen and nitrogen in the flare pipe network, which is realized by adopting a system for recycling hydrogen and nitrogen in the flare pipe network and comprises the following steps: Introducing flare gas from oil refining devices and chemical devices into the pretreatment module; after being stored and buffered in the gas holder in sequence, the flare gas is pressurized by the first driving device and enters the alkaline washing tower; after desulfurization is carried out on the flare gas in the alkaline washing tower, the flare gas enters the gas-liquid separation module, is subjected to depressurization and cooling by the expander to realize condensation, and respectively flows into a gas output end only containing hydrogen and nitrogen and a residual liquid output end containing complex hydrocarbon solution after passing through the separation tank; the flare gas at the gas output end is divided into high-purity hydrogen and mixed gas of hydrogen and nitrogen after passing through the pressure swing adsorption unit; and the com