Research On Helium Extraction Technology Of Helium-depleted Natural Gas By Cryogenic Condensation

Helium is a rare strategic resource.The concentration of helium in China’s natural gas reservoirs is low,and the extraction of helium from helium-depleted natural gas is difficult and the process is complex.Based on the analysis of the composition of raw natural gas and the cryogenic helium extraction process of helium-depleted natural gas,two cryogenic helium extraction processes of natural gas post-expansion + nitrogen expansion refrigeration cycle and MRC + nitrogen expansion refrigeration cycle,and two helium extraction processes and LNG co-production are proposed.The Aspen HYSYS software was used to simulate the four processes,and comprehensively analyzed from the three aspects of helium recovery rate,crude helium concentration and energy consumption.A better cryogenic helium extraction process from heliumdepleted natural gas was obtained,achieving the crude helium concentration of 43.5%and the helium recovery rate more than 98%.Through process simulation,the influence of key equipment process parameters on crude helium concentration,helium recovery rate and equipment energy consumption was analyzed,and the optimized combination of process parameters was obtained;the influence of nitrogen content in feed gas on helium extraction process was analyzed,and it was found that the lower the nitrogen content in the feed gas,the higher the concentration of crude helium.When the nitrogen content is less than 10%,the concentration of crude helium increases rapidly with the decrease of nitrogen content.And a denitrification scheme by adding a denitrification tower is proposed,and the concentration of crude helium can be increased by 12.04%;The influence of the hydrogen content in the feed gas on the helium extraction process was analyzed,and it was found that when the hydrogen content was reduced from0.04% to 0%,the crude helium concentration could be increased by 25%.