| 摘要 |
Production of pure methane comprises rectifying liquefied methane from a natural gas storage tank. Production of pure methane from natural gas that has been purified to remove water vapor, carbon dioxide and higher-boiling (C2+) hydrocarbons comprises: (a) indirectly cooling the natural gas by evaporation of liquid nitrogen in a natural gas storage tank to liquefy the methane; (b) withdrawing a gas comprising components with a lower boiling point than methane from the natural gas storage tank; (c) rectifying the liquefied methane in a rectification column; (d) withdrawing pure methane from the rectification column as a liquid bottoms stream; and (e) recycling the overhead gas from the rectification column to the natural gas storage tank. An Independent claim is also included for apparatus for carrying out the process, comprising a natural gas storage tank with a gas space equipped with a condenser, a methane storage tank equipped with a heater, and a rectification column, where the methane storage tank and rectification column are integrated into a separating column, the top of which is connected via a gas line to the gas space in the natural gas storage tank and via a liquid line to the liquid space of the natural gas storage tank to form a separatory circuit. |
