Mixed Refrigerant Liquefaction System and Method

A system for liquefying a gas comprising:

• a. a liquefaction heat exchanger having a warm end and a cold end and a liquefying passage having an inlet at the warm end and an outlet at the cold end;
• b. a mixed refrigerant compression system in communication with the liquefaction heat exchanger and adapted to cool the liquefying passage;
• c. a liquefied gas outlet line connected to the outlet of the liquefying passage;
• d. a feed gas line having an inlet configured to communicate with a source of feed gas and an outlet;
• e. a heavy hydrocarbon removal heat exchanger having a feed gas cooling passage with an inlet in communication with the outlet of the feed gas line, a return vapor passage and a reflux cooling passage;
• f. a scrub device having:
• i) a feed gas inlet in communication with an outlet of the feed gas cooling passage of the removal heat exchanger;
• ii) a return vapor outlet in communication with an inlet of the return vapor passage of the removal heat exchanger;
• iii) a reflux vapor outlet in communication with an inlet of the reflux cooling passage of the removal heat exchanger;
• iv) a reflux mixed phase inlet in communication with an outlet of the reflux cooling passage of the removal heat exchanger;
• g. a reflux liquid component passage having an inlet and an outlet in communication with the scrub device;
• h. said scrub device configured to vaporize a reflux liquid component stream from the outlet of the reflux liquid component passage so as to cool a feed gas stream entering the scrub device through the feed gas inlet of the scrub device so that the freezing components are condensed and removed from the scrub device through a freezing components outlet;
• and
• i. a processed feed gas line in communication with an outlet of the vapor return passage of the heat exchanger and an inlet of the liquefying passage of the liquefaction heat exchanger.

A system for removing freezing components from a feed gas comprising:

• a. a heavy hydrocarbon removal heat exchanger having a feed gas cooling passage with an inlet adapted to communicate with a source of the feed gas, a return vapor passage and a reflux cooling passage;
• b. a scrub device having:
• i) a feed gas inlet in communication with an outlet of the feed gas cooling passage of the heat exchanger;
• ii) a return vapor outlet in communication with an inlet of the return vapor passage of the heat exchanger;
• iii) a reflux vapor outlet in communication with an inlet of the reflux cooling passage of the heat exchanger;
• iv) a reflux mixed phase inlet in communication with an outlet of the reflux cooling passage of the heat exchanger;
• c. a reflux liquid component passage having an inlet and an outlet in communication with the scrub device;
• d. said scrub device configured to vaporize a reflux liquid component stream from the outlet of the reflux liquid component passage so as to cool a feed gas stream entering the scrub device through the feed gas inlet of the scrub device so that the freezing components are condensed and removed from the scrub device through a freezing components outlet;
• and
• e. a processed feed gas line in communication with an outlet of the vapor return passage of the heat exchanger.

A method for removing freezing components from a feed gas comprising the steps of:

• a. providing a heavy hydrocarbon removal heat exchanger and a scrub device;
• b. cooling the feed gas using the heat exchanger to create a cooled feed gas stream;
• c. directing the cooled feed gas stream to the scrub device;
• d. directing vapor from the scrub device to the heat exchanger and cooling the vapor to create a mixed phase reflux stream;
• e. directing the mixed phase reflux stream to the scrub device so that a liquid component reflux stream is provided for the scrub device;
• f. vaporizing the liquid component reflux stream in the scrub device so that the freezing components are condensed and removed from the cooled feed gas stream in the scrub device to create a processed feed gas vapor stream;
• g. directing the processed feed gas vapor stream to the heat exchanger;
• and
• h. warming the processed feed gas vapor stream in the heat exchanger to produce a warmed processed feed gas vapor stream suitable for liquefaction.