| 摘要 |
997,802. Cold separation of gas mixtures. CONCH INTERNATIONAL METHANE Ltd. April 8, 1964, No. 14531/64. Heading F4P. A high pressure gas, mixture, e.g. natural gas, is freed of relatively high and low boiling point impurities, e.g. carbon dioxide and nitrogen by expansion of the feed mixture in a turbine N, liquefaction in an indirect heat exchanger A, separation in a column E from the base of which nitrogen - free liquid methane containing carbon dioxide is withdrawn through lines 8, 10 and a portion thereof discharged from the system through lines 19, 20, whilst the remainder is passed through a line 12, a flash vessel J, a carbon dioxide separator L and a further flash vessel product liquid methane is withdrawn through a line 17 and gaseous methane withdrawn through a line 21 is used as refrigerant in exchanger A; effluent nitrogen from the column being used to cool said refrigerant methane in a condenser F as is bottom product of the column in reboiler G. The refrigerant methane gas leaving vessel K through a line 21 is compressed at S, T, cooled in an exchanger D, liquefied in liquid product evaporator H and reboiler G arranged in parallel, further cooled in an exchanger C and expanded at a valve 32 into exchanger A. Methane evaporated in exchanger A is returned through a line 25 and exchangers C, D to the inlet of compressor T whilst liquid methane from said exchanger A is fed through a line 33, exchanger B and is flash evaporated at a valve 34 into the condenser F and the so-vaporized methane is returned through a line 22 to the inlet of compressor S. Methane gas from flash vessel J passing through a line 14 is warmed in exchangers B, C and D, compressed at R, Q and is discharged from the system through line 20 together with that portion of liquid bottom product not freed of carbon dioxide and vaporized in evaporator H. The compressors are driven by a motor M supplied with a small portion of feed mixture withdrawn at a point 40 through a valve 4 and a line 5. |
