Process for liquefying a natural gas stream containing at least one freezable component

A process for separating a multi-component feed stream comprising at least methane and at least one freezable component having a relative volatility less than that of methane to produce a liquid product enriched in methane, comprising:

• (a) introducing the multi-component feed stream into a separation system, said separation system operating under solids forming conditions for said freezable component;
• (b) withdrawing a vapor stream from an upper region of said separation system;
• (c) compressing said vapor stream to a higher pressure stream;
• (d) cooling at least a portion of said compressed stream using the cooling available in vapor stream of step (b);
• (e) expanding said cooled compressed stream to further cool said compressed stream, said expanded stream being predominantly liquid;
• (f) feeding at least a portion of said expanded stream to an upper region of the separation system to provide refrigeration to said separation system;
• and
• (g) recovering from the expanded stream a liquid product stream enriched in methane.

A process for producing liquefied natural gas at a pressure above about 1,380 kPa (200 psia) from a multi-component feed stream containing methane and a freezable component having a relative volatility less than that of methane, comprising:

• (a) introducing the multi-component feed stream into a separation system, said separation system operating under solids forming conditions for said freezable component;
• (b) withdrawing a vapor stream from an upper region of said separation system;
• (c) compressing said vapor stream to a higher pressure stream;
• (d) cooling at least a portion of said compressed stream using the cooling available in vapor stream of step (b);
• (e) expanding said cooled compressed stream to further cool said compressed stream, said expanded stream being predominantly liquid at a pressure above about 1,380 kPa (200 psia);
• (f) feeding at least a portion of said expanded stream to an upper portion of the separation system to provide refrigeration to said separation system;
• and
• (g) recovering from the expanded stream a liquid product stream enriched in methane at a pressure above about 1,380 kPa (200 psia).

A process for liquefying a multi-component stream comprising methane and at least one freezable component to produce a methane-rich liquid having a temperature above about -112.degree. C. and a pressure sufficient for the liquid to be at or below its bubble point, comprising the steps of:

• (a) introducing the multi-component feed stream having a pressure above about 1,380 kPa (200 psia) into a separation system operating under solids forming conditions for said freezable component to provide a methane-rich vapor stream and a liquid stream rich in said component that solidified in the separation system;
• (b) liquefying the vapor stream by a closed loop refrigeration system to produce a methane-rich liquid having a temperature above about -112.degree. C. and a pressure sufficient for the liquid to be at or below its bubble point;
• and
• (c) introducing said methane-rich liquid to a storage vessel for storage at a temperature above -112.degree. C.