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US 6,269,656 B1Granted
Method and apparatus for producing liquified natural gas
OwnerRichard P. Johnstoninventor
Life of this patent
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OwnerRichard P. Johnstoninventor
Estimating the term…
Both a method and apparatus for producing liquified natural gas (LNG) at a well head or other source where cool high pressure natural gas is provided. The natural gas flow from the source is cleaned, if required, and is split into two portions. The first flow portion goes to a primary heat exchanger, then to a second heat exchanger or super cooler, and is thereafter throttled into a LNG tank wherein a part thereof flashes to liquid natural gas and a part thereof becomes a very cold saturated vapor to be vented from the LNG tank. This vent remainder of the first flow portion enters the super cooler as a coolant therefor. The second flow portion enters an expander where work is extracted and the temperature and pressure of the second flow portion are lowered. The cold lower pressure second portion combines with the partially warmed vent remainder of the first portion from the super cooler and passes into the primary heat exchanger as the initial coolant for the first portion. The combined warmed second portion and first portion vent remainder then pass out of the system into a low pressure receiver such as a pipeline. The combined portions are at a pressure equal to or greater than that in the receiver. In a second embodiment the supercooler is eliminated, somewhat reducing the liquid natural gas produced.
A method for converting a fraction of natural gas from a source to liquid natural gas comprising the steps of providing a source of pressurized, cool, clean natural gas, splitting said natural gas into first and second portions, causing said first portion to pass through at least a first heat exchanger to cool said first gas portion, causing said first gas portion to pass through a restriction into a liquid natural gas collector wherein a part of said first gas portion flashes to liquid natural gas, the remainder comprising a very cold saturated natural gas, venting said remainder through said at least first heat exchanger to serve as a cooling medium therefor, directing said second portion of said cleansed natural gas to an expander, expanding said second portion by extracting expander work, combining said cooled and expanded second portion with said vent remainder prior to passage thereof through said at least first heat exchanger, thereafter conducting said combined vent remainder of said first gas portion and said second gas portion to a receiver, and assuring that said combined vent remainder of said first gas portion and said second gas portion are at a pressure equal or greater than the pressure in said receiver.
An apparatus for converting a fraction of the natural gas from a source thereof to liquid natural gas, said apparatus comprising a source of pressurized, cool, clean natural gas, said source being connected to a point where said natural gas from said source is split into first and second portions, at least one heat exchanger, said first gas portion being connected to said at least one heat exchanger, a restriction, said at least one heat exchanger being operatively connected to said restriction, a liquid natural gas collector, said collector being connected to said restriction whereby said first portion of said natural gas passes through said at least one heat exchanger and is throttled into said collector wherein it is partially converted to liquid natural gas, the remainder comprising a very cold saturated natural gas vapor, said collector being connected by a conduit to said at least one heat exchanger whereby to vent said vapor through said at least one heat exchanger as a cooling medium therefor, an expander, a conduit for directing said second gas portion to said expander for expansion and cooling, a conduit from said expander being connected to said conduit from said collector to said at least one heat exchanger whereby to combine said cooled and expanded second gas portion with said vented remainder of said first gas portion before entry into said at least one heat exchanger, a receiver, a conduit from said at least one heat exchanger to said receiver to convey said combination of said cooled and expanded second gas portion and said vented remainder of said first gas portion from said at least one heat exchanger to said receiver.
A method for converting a fraction of natural gas from a source to liquid natural gas, comprising the steps of:
Dependencies are inferred from the claim text.