HYDROCARBON GAS PROCESSING

摘要

The processing of gas streams containing hydrocarbons and other gases of similar volatility to recover components such as ethane, propane and heavier hydrocarbons from a residue gas containing methane is disclosed. In prior art processes, it has been customary to cool incoming raw feed gas and to separate the desired products by distillation. A part of the needed cooling is obtained by expanding the raw feed gas from a high feed pressure to a lower pressure at which distillation occurs. In the present invention, the raw feed gas is divided into two gaseous streams before expansion. The first stream is expanded in the usual fashion and supplied to the demethanizer as a mid-column feed. The remaining part is cooled to substantial condensation. The condensed stream is expanded and supplied to the demethanizer column above the feed point of the first stream. The split vapor feed provides unexpected advantages in reducing the risk of carbon dioxide icing in the demethanizer column, thus either eliminating or reducing the need for prior CO2 removal. Alternately, without increasing the risk of carbon dioxide icing, ethane recovery can be increased.