Multi-technology integrated separation process for producing high-purity helium from liquefied tail gas of helium-rich natural gas

Abstract

The invention relates to a multi-technology integrated separation process for producing high-purity helium from helium-rich liquefied natural gas tail gas, which comprises the following steps: helium-containing tail gas from a natural gas liquefaction device enters a multi-stage circulating membrane separation unit for preliminary enrichment after being subjected to cold energy recovery and pressurization; crude helium obtained through membrane separation enters a catalytic oxidation dehydrogenation unit after being pressurized, then enters a compression condensation and temperature swing adsorption dehydration unit and finally enters a low-temperature pressure swing adsorption purification unit, and high-purity helium is obtained; and desorbed gas of the adsorption unit returns to a membrane separation unit. Through multi-technology gapless matching and synergistic interaction, it is guaranteed that each impurity is removed in a proper mode, high-purity helium with the purity being 99.99 vol% is obtained, the helium recovery rate is remarkably increased, and meanwhile purification energy consumption is reduced. The natural gas with a helium concentration of 4.60vol% liquefies tail gas , the simulation result shows that the recovery rate of the multi-technology integrated process can reach 84.0% or above, and the purification unit consumption (electricity) does not exceed 4.0 kWh / Nm <3> of helium.

Description

technical field [0001] The invention relates to a multi-technology integrated separation process for producing high-purity helium by using helium-enriched natural gas liquefaction tail gas as a raw material, belonging to the field of petrochemical industry. The helium-containing tail gas from the natural gas liquefaction unit enters the multi-stage circulation membrane separation unit for preliminary enrichment after cooling recovery and pressurization; the crude helium gas obtained by membrane separation enters the catalytic oxidation dehydrogenation unit after pressurization, and then enters the compression The condensation dehydration unit and the temperature swing adsorption dehydration unit finally enter the low-temperature pressure swing adsorption unit to obtain high-purity helium; the helium-containing desorbed gas produced by the adsorption unit returns to the multi-stage circulating membrane separation unit to increase the helium yield. Through the coupling and integ...

AI Technical Summary

Problems solved by technology

Due to the special composition of helium-rich natural gas liquefaction tail gas, it is difficult to achieve high purification of helium by a single separation technology

The operating temperature of the natural gas liquefaction process is about -150°C, and the methane content in the tail gas containing helium is still as high as 70vol%, while the boiling points of nitrogen and hydrogen are lower. It is a kind of gas separation technology through the selective dissolution of solvent, but the solubility of nitrogen and hydrogen in various absorbents is very low, which is difficult to meet the demand; membrane separation is a separation technology based on the difference in permeation rate, which does not depend on the phase balance of the separation system , but the condensability and molecular size of hydrogen and helium are very close, and it is difficult to achieve high purification of helium only by membrane separation; pressure swing adsorption is a separation technology based on selective adsorption on the surface of porous materials. It is very difficult to adsorb hydrogen and nitrogen with solvents, and it is difficult to achieve high purification of helium only by pressure swing adsorption.

[0007] Aiming at the problem that common gas separation technology is difficult to produce high-purity helium with helium-rich natural gas liquefaction tail gas as raw material, this invention proposes a high-purity helium gas that integrates gas membrane separation, catalytic oxidation, compression condensation, temperature swing adsorption and pressure swing adsorption Production Process

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