| 摘要 |
<p>A stream 2 of gas mixture typically comprising methane and up to 12% by volume of carbon dioxide is subjected to rectification in a first column 8 to form a carbon dioxide depleted fraction that is withdrawn as product from the top of the column 8 and a carbon-dioxide-enriched fraction which is withdrawn from the bottom of the column 8, warmed in heat exchanger 22, and introduced into a second rectification column 20 operating at a higher pressure than the first column 8. A stream 30 in which carbon dioxide predominates is withdrawn from the bottom of the column 20 while a stream 34 containing a lower proportion of carbon dioxide than said enriched fraction is withdrawn from the top of the column 20, is throttled through valve 36 and is united with the stream 2 upstream of the column 8. Methane product is able to be obtained at high yield. </p> |
