Hydrocarbon gas separation process

A process for separating components of a feed gas containing methane and heavier hydrocarbons, the process comprising the steps of:

• feeding an inlet gas stream to a demethanizer column to produce therefrom an overhead vapor stream containing predominantly methane and a bottom fraction containing predominately C.sub.2 and C.sub.2.sup.+ components;
• compressing the overhead vapor stream to form a compressed recycle stream;
• cooling the compressed recycle stream sufficiently to substantially condense it to a reflux stream by reboiling the demethanizer column while simultaneously satisfying heat requirements of the column;
• supplying the condensed reflux stream to the demethanizer column as a top feed to thereby control product recovery from the process.

A process for separating components of a feed gas containing methane and heavier hydrocarbons, the process comprising the steps of:

• feeding an inlet gas stream to a separator, without first splitting the inlet gas stream, the separator producing a first vapor portion and a first liquid portion therefrom;
• supplying the first vapor portion, after expansion, to a demethanizer column at an intermediate feed position;
• expanding the first liquid portion to form an expanded stream and supplying the expanded stream to the demethanizer column at a relatively lower feed position;
• removing an overhead vapor stream from the demethanizer column;
• compressing the overhead vapor stream to a higher pressure and thereafter dividing the stream into a volatile residue gas fraction and a compressed recycle stream;
• cooling the compressed recycle stream sufficiently to substantially condense it while reboiling the demethanizer and supplying the condensed stream as reflux to the demethanizer column at a top feed position.

A process for separating components of a feed gas containing methane and heavier hydrocarbons, the process comprising the steps of:

• feeding an inlet gas stream to a separator, without first splitting the inlet gas stream, the separator producing a first vapor portion and a first liquid portion therefrom;
• supplying the first vapor portion, after expansion, to a demethanizer column at an intermediate feed position;
• expanding the first liquid portion to form an expanded stream and supplying the expanded stream to the demethanizer column at a relatively lower feed position;
• removing an overhead vapor stream from the demethanizer column;
• compressing the overhead vapor stream to a higher pressure and thereafter dividing the stream into a volatile residue gas fraction and a compressed recycle stream;
• cooling the compressed recycle stream sufficiently to substantially condense it while simultaneously providing heat to reboil the demethanizer column;
• expanding the cooled compressed recycle stream to a lower pressure and supplying it to the demethanizer at a top feed position.

A process for separation of a gas stream containing methane, C.sub.2 components, C.sub.3 components and heavier components, the process comprising the steps of:

• cooling an inlet gas stream under pressure, prior to splitting the inlet gas stream, to provide a partially condensed, cooled stream;
• separating the partially condensed, cooled stream in a high pressure separator into a first vapor portion and a first liquid portion;
• expanding the first vapor portion in a turboexpander to further cool the stream and introducing the expanded stream to a demethanizer column at an intermediate feed position;
• expanding the first liquid portion from the separator and directing the expanded liquid portion to the demethanizer column at a relatively lower feed position;
• removing an overhead vapor stream from the demethanizer column;
• passing the overhead vapor stream in countercurrent flow to the inlet gas stream in a heat exchanger to warm the overhead vapor stream and cool the inlet gas stream;
• compressing the overhead vapor stream to a higher pressure and thereafter dividing the stream into a volatile residue gas fraction and a compressed recycle stream;
• cooling the compressed recycle stream sufficiently to substantially condense it by contacting it with side reboilers provided as a part of the demethanizer column;
• further cooling the compressed recycle stream;
• expanding the cooled compressed recycle stream to a lower pressure and supplying it to the demethanizer at a top feed position.