Apparatus for the liquefaction of natural gas and methods relating to same

A liquefaction plant comprising:

• a first flow path configured for sequential delivery of a first stream of natural gas through a compressor, a first side of a first heat exchanger and a first side of a second heat exchanger;
• a second flow path configured for sequential delivery of a second stream of natural gas through an expander, a second side of the second heat exchanger and a second side of the first heat exchanger;
• at least two paths including a cooling path and a liquid production path formed from the first flow path at a location subsequent an intended flow of the first stream of natural gas through the first side of the second heat exchanger, the cooling path selectively configured to direct at least a first portion of the first stream of natural gas to the second side of the second heat exchanger and wherein the liquid production path is configured to selectively direct a second portion of the first stream of natural gas to a gas-liquid separator;
• and
• a surge protection loop comprising valving and piping located and configured to selectively direct at least a portion of the first stream of natural gas from a location between the compressor and the first side of the first heat exchanger back to an inlet of the compressor.

A liquefaction plant comprising:

• a first flow path configured for sequential delivery of a first stream of natural gas through a compressor, a first side of a first heat exchanger and a first side of a second heat exchanger;
• a second flow path configured for sequential delivery of a second stream of natural gas through an expander, a second side of the second heat exchanger and a second side of the first heat exchanger;
• at least two paths including a cooling path and a liquid production path formed from the first flow path at a location subsequent an intended flow of the first stream of natural gas through the first side of the second heat exchanger, the cooling path selectively configured to direct at least a first portion of the first stream of natural gas to the second side of the second heat exchanger and wherein the liquid production path is configured to selectively direct a second portion of the first stream of natural gas to a gas-liquid separator;
• and
• valving and piping configured to direct a portion of the first stream of natural gas to the gas-liquid separator such that the portion of the first stream of natural gas bubbles through any liquid contained therein.

A liquefaction plant comprising:

• a first flow path configured for sequential delivery of a first stream of natural gas through a compressor, a first side of a first heat exchanger and a first side of a second heat exchanger;
• a second flow path configured for sequential delivery of a second stream of natural gas through an expander, a second side of the second heat exchanger and a second side of the first heat exchanger;
• at least two paths including a cooling path and a liquid production path formed from the first flow path at a location subsequent an intended flow of the first stream of natural gas through the first side of the second heat exchanger, the cooling path selectively configured to direct at least a first portion of the first stream of natural gas to the second side of the second heat exchanger and the liquid production path is configured to selectively direct a second portion of the first stream of natural gas to a gas-liquid separator;
• and
• a source of methanol located and configured to introduce a volume of methanol into the first flow path at a location prior to an intended flow of natural gas through the compressor.

A liquefaction plant comprising:

• a first flow path configured for sequential delivery of a first stream of natural gas through a compressor, a first side of a first heat exchanger and a first side of a second heat exchanger;
• a second flow path configured for sequential delivery of a second stream of natural gas through an expander, a second side of the second heat exchanger and a second side of the first heat exchanger;
• at least two paths including a cooling path and a liquid production path formed from the first flow path at a location subsequent an intended flow of the first stream of natural gas through the first side of the second heat exchanger, the cooling path selectively configured to direct at least a first portion of the first stream of natural gas to the second side of the second heat exchanger and the liquid production path is configured to selectively direct a second portion of the first stream of natural gas to a gas-liquid separator;
• a liquid storage tank and another flow path defined between the gas-liquid separator and the liquid storage tank, and
• a first vent line coupled with the gas-liquid separator and a valve disposed within the first vent line providing selective communication between the gas-liquid separator and the liquid storage tank such that, when the valve is in an open position, a pressure in the gas-liquid separator is substantially the same as a pressure in the liquid storage tank.

A method of producing liquid natural gas, the method comprising:

• providing a source of unpurified natural gas and flowing a portion of the unpurified natural gas from the source;
• dividing the portion of unpurified natural gas into at least a process stream and a cooling stream;
• flowing the process stream sequentially through a compressor, a first side of a first heat exchanger and a first side of a second heat exchanger;
• flowing the cooling stream sequentially through an expander, through a second side of the second heat exchanger and into the source;
• sensing a temperature of the process stream after it exits the first side of the second heat exchanger;
• flowing substantially all of the process stream from the first side of the second heat exchanger to the second side of the first heat exchanger if the sensed temperature is warmer than a specified temperature;
• and
• flowing a first portion of the process stream from the first side of the second heat exchanger to the second side of the second heat exchanger and flowing a second portion of the process stream from the first side of the second heat exchanger to a gas-liquid separator if the sensed temperature is colder than the specified temperature.