An apparatus for separating a feed gas into a volatile residue gas fraction and a less volatile fraction, said feed gas containing hydrocarbons, methane and C2 components together comprising said feed gas, said apparatus including
- a. a first heat exchange means comprising a first heat exchanger to receive said feed gas under pressure and cool said feed gas to partially condense it to form a partially condensed stream;
- b. a separation means comprising a separation column connected to said first heat exchange means to receive said partially condensed stream under pressure and separate said partially condensed stream into a liquid stream and a vapor stream;
- c. a first dividing means comprising a piping tee connected to said separation means to receive said vapor stream and divide said vapor stream into a first stream and a second stream;
- d. a first expansion means comprising an expansion machine connected to said first dividing means to receive said first stream and expand said first stream to a lower pressure to form an expanded first stream;
- e. a distillation column. connected to receive said expanded first stream at a mid-column feed position;
- f. a second heat exchange means comprising a second heat exchanger connected to said first dividing means to receive said second stream and cool said second stream to condensation to form a cooled second stream;
- g. a second expansion means comprising an expansion valve connected to said second heat exchange means to receive said cooled second stream and expand said cooled second stream to said lower pressure to form an expanded cooled second stream;
- h. a third heat exchange means comprising a third heat exchanger connected to said separation means to receive said liquid stream and cool said liquid stream to form a subcooled liquid stream;
- i. a second dividing meanssomprising a piping tee connected to said third heat exchange means to receive said subcooled liquid stream and divide said subcooled liquid stream into a first portion and a second portion;
- j. a third expansion means comprising an expansion valve connected to said second dividing means to receive said first portion and expand said first portion to said lower pressure to form an expanded first portion;
- k. said third heat exchange means further connected to said third expansion means to receive said expanded first portion and heat said expanded first portion to form a heated expanded first portion, thereby to supply at least a portion of said cooling of element h, said third heat exchange means further being connected to said distillation column connected to supply said heated expanded first portion to said distillation column at a lower mid-column feed position;
- l. a fourth expansion means.commis* an expansion valve connected to said second dividing means to receive said second portion and expand said second portion to said lower pressure to form an expanded second portion,
- m. a combining means comprising a piping tee connected to said second expansion means and said fourth expansion means to receive said expanded cooled second stream and said expanded second portion and combine said expanded cooled second stream and said expanded second portion to form a combined stream, said combining means being further connected to said distillation column to supply said combined stream to said distillation column at a top feed position,
- n. said distillation. column being adapted to fractionate said combined stream;said expanded first stream, and said heated expanded first portion at said lower pressure to form a distillation vapor stream and said less volatile fraction;
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- o. said distillation colimm being further connected to said second heat exchange means and said second heat exchange means being further connected to said first heat exchange means to receive said distillation vapor stream and heat said distillation vapor stream to form said volatile residue gas fraction, thereby to supply at least a portion of said cooling of elements a and f.