CN-121971953-A - Hydrogen-rich tail gas recovery device and method

CN121971953ACN 121971953 ACN121971953 ACN 121971953ACN-121971953-A

Abstract

The application discloses a device and a method for recovering hydrogen-rich tail gas, wherein the device comprises a dehydrogenation tower, a plate-fin heat exchanger, a tail gas buffer tank, a compressor, a gas separation and purification unit, a hydrogen buffer tank, a desorption gas mixer, a reverse gas buffer tank and a reverse gas buffer tank, wherein the inlet of the plate-fin heat exchanger is connected with an outlet of the top of the dehydrogenation tower, the inlet of the tail gas buffer tank is connected with an outlet of the plate-fin heat exchanger, the inlet of the compressor is connected with an outlet of the top of the tail gas buffer tank, the inlet of the gas separation and purification unit is connected with an outlet of the compressor, the inlet of the hydrogen buffer tank is connected with the top of the gas separation and purification unit, the inlet of the desorption gas mixer is connected with the bottom of the gas separation and purification unit, and the desorption gas mixer is connected with the reverse gas buffer tank through a fuel gas pipe network. According to the application, the pressure swing adsorption technology is utilized, and according to the difference of adsorption capacities of components in the hydrogen-rich tail gas on the adsorbent, the purification of hydrogen and the regeneration of the adsorbent are realized under the periodically-changing pressure.

Inventors

WANG KAI
FU PENGFEI
Guo Xiyong
LI WEIHUA
YU WEIQI
MA FENG
Wang Juanqiang

Assignees

新疆准能化工有限公司

Dates

Publication Date: 20260505
Application Date: 20260212

Claims (10)

1. A hydrogen-rich tail gas recovery apparatus, comprising: A dehydrogenation tower, wherein the dehydrogenation tower comprises a dehydrogenation tower body, A plate-fin heat exchanger with an inlet connected with an outlet at the top of the dehydrogenation tower; a tail gas buffer tank with an inlet connected with the outlet of the plate-fin heat exchanger; the inlet is connected with the outlet at the top of the tail gas buffer tank; a gas separation and purification unit with an inlet connected with the outlet of the compressor; the inlet is connected with the top of the gas separation and purification unit; A desorption gas mixer with an inlet connected with the bottom of the gas separation and purification unit; the inlet is connected with the middle part of the gas separation and purification unit; the desorption gas mixer is connected with the reverse gas discharge buffer tank through a fuel gas removal pipe network.
2. The apparatus of claim 1, wherein the gas separation and purification unit comprises 4-12 adsorption columns arranged in parallel, a vacuum pump connected to the bottom of the first adsorption column, a sewage line connected to the bottom of the last adsorption column, and wherein the gas separation and purification unit comprises one or more of a pressure swing adsorption device, a membrane separation device, or a cryogenic separation device.
3. The apparatus of claim 2, wherein the inlet of the hydrogen buffer tank is connected to the top of the last adsorption column.
4. The apparatus according to claim 2, wherein the adsorption tower is connected with the vacuum pump and the desorption gas mixer in sequence through a hydrogen-rich tail gas pipeline.
5. The apparatus of claim 2, wherein the inlet of the reverse draft buffer tank is connected to the last adsorption column.
6. The apparatus of claim 2, wherein the last of the adsorption columns is connected to the hydrogen buffer tank through a hydrogen purification pipe, a product hydrogen control valve.
7. The apparatus of claim 1, wherein the plate-fin heat exchanger is provided with a refrigerant outlet line at the top and a refrigerant inlet line at the bottom.
8. A method for hydrogen-rich tail gas recovery, comprising: carrying out dehydrogenation, reheating, gas-liquid separation and compression on the hydrogen-rich tail gas to obtain pressurized hydrogen-rich tail gas; The pressurized hydrogen-rich tail gas enters the gas separation and purification unit; The gas separation and purification unit comprises 4-12 adsorption towers which are arranged in parallel, wherein each adsorption tower sequentially comprises adsorption, one uniform drop, two uniform drops, three uniform drops, four uniform drops, reverse discharge, vacuumizing, four uniform rises, three uniform rises, two uniform rises, one uniform rise and final rise in one cycle, so that high-purity hydrogen is obtained; the high purity hydrogen is output from the hydrogen buffer tank.
9. The method according to claim 8, wherein the impurity gas desorbed from the bottom of the adsorption tower is mixed with part of the hydrogen-rich tail gas of the tail gas buffer tank through the reverse gas buffer tank to obtain a mixed gas.
10. The method of claim 8, wherein an adsorbent is disposed within the adsorption column, the adsorbent comprising activated alumina and/or molecular sieves.

Description

Hydrogen-rich tail gas recovery device and method Technical Field The application relates to the technical field of chemical industry, in particular to a device and a method for recycling hydrogen-rich tail gas. Background In the natural gas liquefaction industry, the raw gas is purified and then subjected to cryogenic liquefaction in a cold box through a plate-fin heat exchanger. In this process, in addition to the main component methane being liquefied, components which are difficult to liquefy, such as hydrogen (H 2) and a small amount of nitrogen (N 2), contained in the raw material gas are separated from liquefied natural gas (Liquefied Natural Gas, LNG) in a dehydrogenation tower (or gas-liquid separation tank) at the end, so that a hydrogen-rich tail gas is formed. The tail gas has the characteristics of high hydrogen concentration, certain methane content and relatively low pressure and temperature. For a long time, many devices choose to either directly empty or burn as fuel the hydrogen rich tail gas produced by the cryogenic liquefaction process. The treatment mode mainly has the following problems that the resource value is not fully known, part of enterprises consider that the recovery economy is not high, and meanwhile, if the traditional large-scale recovery technologies such as pressure swing adsorption (Pressure Swing Adsorption, PSA) or membrane separation are adopted for tail gas with small gas quantity, the equipment utilization rate is low, the investment benefit is poor and the technical bottleneck is formed due to the 'large Mara trolley'. In fact, hydrogen in hydrogen-rich tail gas is a valuable industrial feedstock and clean energy source. Only using it as a common fuel is a downgraded utilization and waste of resources. Along with the rising energy price, the economic benefit brought by recycling and high-value utilization of hydrogen in the fuel is far beyond the fuel value. In the existing process flow, hydrogen-rich tail gas discharged from the top of the dehydrogenation tower usually enters a plate-fin heat exchanger to recover cold energy, and after rewarming, the hydrogen-rich tail gas is sent to a factory fuel gas pipe network with lower pressure by virtue of self pressure (usually more than or equal to 0.5 MPa) to be used as supplementary fuel. The conventional utilization mode has low resource utilization rate and limited economic benefit, and carbon dioxide emission is still generated after combustion, so that environmental protection pressure is faced. In summary, in the methane cryogenic liquefaction process, the generated hydrogen-rich tail gas (especially for a small-gas working condition) is directly discharged, flared or only used as fuel, so that the problems of resource waste, poor economy and environmental protection exist. Therefore, how to provide an economical, efficient and easy-to-implement hydrogen-rich tail gas recovery device based on the existing mature liquefaction process is a problem to be solved by the person skilled in the art. Disclosure of Invention In view of this, the present application provides a device for recovering hydrogen-rich tail gas, so as to achieve the purpose of effectively utilizing the hydrogen-rich tail gas and reducing the overall fuel consumption and emission of the device. The application provides a device for recovering hydrogen-rich tail gas, which comprises: A dehydrogenation tower, wherein the dehydrogenation tower comprises a dehydrogenation tower body, A plate-fin heat exchanger with an inlet connected with an outlet at the top of the dehydrogenation tower; A tail gas buffer tank with an inlet connected with an outlet of the plate-fin heat exchanger; the inlet is connected with the top outlet of the tail gas buffer tank; a gas separation and purification unit with an inlet connected with an outlet of the compressor; The inlet is connected with the top of the gas separation and purification unit; the inlet is connected with the desorption gas mixer at the bottom of the gas separation and purification unit; The inlet is connected with the middle part of the gas separation and purification unit; the stripping and air-sucking mixer is connected with the reverse air-discharging buffer tank through a fuel-removing air pipe network. In some specific implementations, the gas separation and purification unit includes 4-12 adsorption columns arranged in parallel, a vacuum pump connected to the bottom of the first adsorption column, and a sewer line connected to the bottom of the last adsorption column. The gas separation and purification unit includes one or more of a pressure swing adsorption device (Pressure Swing Adsorption, PSA), a membrane separation device, or a cryogenic separation device. In some specific implementations, the inlet of the hydrogen buffer tank is connected to the top of the last adsorption column. In some specific implementations, the adsorption tower is connected with a vacuum pump and a desorption gas mix