Method for the production of liquefied natural gas

1. A method for producing liquefied natural gas, comprising:

compressing a process stream containing natural gas from a natural gas source in a compression assembly fluidly coupled with the natural gas source to product a compressed process stream;

removing one or more non-hydrocarbons from the compressed process stream in a separator fluidly coupled with the compression assembly;

cooling the compressed process stream with a cooling assembly fluidly coupled with the compression assembly, thereby producing a cooled, compressed process stream containing the natural gas in a supercritical state;

expanding a first portion of the natural gas in the cooled, compressed process stream in a first expansion element to generate a first refrigeration stream;

expanding a second portion of the natural gas in the cooled, compressed process stream in a second expansion element to generate a second refrigeration stream;

cooling at least a portion of the natural gas in the cooled, compressed process stream to a subcritical state with the first refrigeration stream and the second stream, thereby producing the liquefied natural gas;

feeding the first refrigeration stream to the compression assembly as a first recycle stream; and

combining the compressed first recycle stream with the compressed process stream downstream from the separator;

feeding the second refrigeration stream to the compression assembly as a second recycle stream; and

combining the compressed second recycle stream with the process stream upstream of the separator.

2. The method of claim 1 , wherein the second expansion element is an expansion valve.

3. The method of claim 1 , wherein the first expansion element is a turbo-expander.

4. The method of claim 3 , further comprising:

expanding the first portion of the cooled, compressed process stream in the turbo-expander to generate mechanical energy; and

driving a compressor coupled with the turbo-expander with the mechanical energy to compress the first recycle stream.

5. The method of claim 1 , wherein cooling the at least a portion of the natural gas in the cooled, compressed process stream to the subcritical state with the first refrigeration stream and the second refrigeration stream comprises:

cooling the at least a portion of the natural gas in the cooled, compressed process stream in a first heat exchanger with the first refrigeration stream; and

cooling the at least a portion of the natural gas in the cooled, compressed process stream in a second heat exchanger with the second refrigeration stream.

6. The method of claim 1 , wherein the cooling assembly includes a mechanical chiller configured to receive and be driven by electrical energy.

7. The method of claim 1 , wherein compressing the process stream in the compression assembly comprises:

generating heat from the compression of the process stream; and

absorbing at least a portion of the heat generated from the compression of the process stream with a cooler of the compression assembly.

8. The method of claim 1 , wherein removing the one or more non-hydrocarbons from the compressed process stream in the separator comprises removing water and carbon dioxide from the natural gas in the separator at a pressure greater than about 1,000 kPa.

9. A method for producing liquefied natural gas, comprising:

compressing natural gas from a natural gas source in a compression assembly fluidly coupled with the natural gas source;

removing water and carbon dioxide from the natural gas in a separator fluidly coupled with the compression assembly;

cooling the natural gas to supercritical natural gas with a mechanical chiller configured to receive and be drive by electrical energy;

expanding a first portion of the supercritical natural gas in a first expansion element to generate a first refrigeration stream;

expanding a second portion of the supercritical natural gas in a second expansion element to generate a second refrigeration stream; and

cooling the remaining supercritical natural gas to subcritical natural gas with the first refrigeration stream and the second refrigeration stream, thereby producing the liquefied natural gas;

feeding the first refrigeration stream to the compression assembly as a first recycle stream;

combining the compressed first recycle stream with the natural gas downstream from the separator;

feeding the second refrigeration stream to the compression assembly as a second recycle stream; and

combining the compressed second recycle stream with the natural gas upstream of the separator.

10. The method of claim 9 , wherein the first expansion element is a turbo-expander, and the second expansion element is an expansion valve.

11. The method of claim 9 , further comprising removing water and carbon dioxide from the natural gas in the separator at a pressure greater than about 1,000 kPa.

12. The method of claim 9 , further comprising:

combusting a portion of the natural gas from the natural gas source in an internal combustion engine to produce mechanical energy;

generating the electrical energy in a generator operatively coupled with the internal combustion engine; and

directing at least a portion of the electrical energy to the mechanical chiller.

13. The method of claim 9 , wherein cooling the remaining supercritical natural gas to the subcritical natural gas with the first refrigeration stream and the second refrigeration stream comprises:

cooling the remaining supercritical natural gas with the first refrigeration stream in a first heat exchanger; and

cooling the remaining supercritical natural gas with the second refrigeration stream in a second heat exchanger.