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AssigneeConocoPhillips Company
InventorsNed P. Baudat, Bobby D. Martinez, Paul R. Hahn, Hans P. Weyermann, Wesley R. Qualls
Estimating the term…
Natural gas liquefaction system employing electric motors as compressor drivers. A combination of motors and steam turbines can be powered by a cogeneration plant and employed as drivers.
A process for liquefying natural gas, said process comprising the steps of:
A process for liquefying natural gas, said process comprising the steps of:
An apparatus for liquefying natural gas by cooling the natural gas via a plurality of sequential refrigeration cycles employing different refrigerants, said apparatus comprising:
An apparatus for liquefying natural gas by cooling the natural gas via a plurality of sequential refrigeration cycles employing different refrigerants, said apparatus comprising:
An apparatus for liquefying natural gas by cooling the natural gas via a plurality of sequential refrigeration cycles employing different refrigerants, said apparatus comprising:
An apparatus for liquefying natural gas by cooling the natural gas via a plurality of sequential refrigeration cycles employing different refrigerants, said apparatus comprising:
An apparatus for liquefying natural gas by cooling the natural gas via a plurality of sequential refrigeration cycles employing different refrigerants, said apparatus comprising:
An apparatus for liquefying natural gas by cooling the natural gas via a plurality of sequential refrigeration cycles employing different refrigerants, said apparatus comprising:
Dependencies are inferred from the claim text.
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Using an "external" refrigerant stream in a closed vapor compression cycle: by vaporising a liquid refrigerant stream
Characterised by the fluid to be liquefied: hydrocarbons, e.g. natural gas
Using the feed stream itself or separated fractions from it, i.e. "internal refrigeration": by flash gas recovery
Hydrocarbons: ethane; Ethylene
Term ended 1 Nov 2022 (estimated)
1. Field of the Invention
This invention concerns a method and an apparatus for liquefying natural gas. In another aspect, the invention concerns an improved driver, compressor, and power source configurations for a cascade-type natural gas liquefaction plant.
2. Description of the Prior Art
A preferred embodiment of the present invention is described in detail below with reference to the attached drawing figures, wherein:
FIG. 1 is a simplified flow diagram of a cascaded refrigeration process for LNG production which employs a novel driver and compressor system. The numbering scheme in FIG. 1 can be summarized as follows:
100-199: Conduits for primarily methane streams
As used herein, the term open-cycle cascaded refrigeration process refers to a cascaded refrigeration process comprising at least one closed refrigeration cycle and one open refrigeration cycle where the boiling point of the refrigerant/cooling agent employed in the open cycle is less than the boiling point of the refrigerating agent or agents employed in the closed cycle(s) and a portion of the cooling duty to condense the compressed open-cycle refrigerant/cooling agent is provided by one or more of the closed cycles. In the current invention, methane or a predominately methane stream is employed as the refrigerant/cooling agent in the open cycle. This stream is comprised of the processed natural gas feed stream and the compressed open methane cycle gas streams.
The design of a cascaded refrigeration process involves a balancing of thermodynamic efficiencies and capital costs. In heat transfer processes, thermodynamic irreversibilities are reduced as the temperature gradients between heating and cooling fluids become smaller, but obtaining such small temperature gradients generally requires significant increases in the amount of heat transfer area, major modifications to various process equipment and the proper selection of flow rates through such equipment so as to ensure that both flowrates and approach and outlet temperatures are compatible with the required heating/cooling duty.
One of the most efficient and effective means of liquefying natural gas is via an optimized cascade-type operation in combination with expansion-type cooling. Such a liquefaction process is comprised of the sequential cooling of a natural gas stream at an elevated pressure, for example about 625 psia, by sequentially cooling the gas stream by passage through a multistage propane cycle, a multistage ethane or ethylene cycle, and an open-end methane cycle which utilizes a portion of the feed gas as a source of methane and which includes therein a multistage expansion cycle to further cool the same and reduce the pressure to near-atmospheric pressure. In the sequence of cooling cycles, the refrigerant having the highest boiling point is utilized first followed by a refrigerant having an intermediate boiling point and finally by a refrigerant having the lowest boiling point. As used herein, the term “propane chiller” shall denote a cooling system that employs a refrigerant having a boiling point the same as, or similar to, that of propane or propylene. As used herein, the term “ethylene chiller” shall denote a cooling system that employs a refrigerant having a boiling point the same as, or similar to, that of ethane or ethylene. As used herein, the terms “upstream” and “downstream” shall be used to describe the relative positions of various components of a natural gas liquefaction plant along the flow path of natural gas through the plant.