TH42974A - The re-liquefaction of the boiling gaseous portion is further compressed from liquefied natural gas. - Google Patents

Abstract

DC60 (03/10/42) The process is revealed for the re-liquefaction of a boiling gas that is produced by compressing liquefied natural gas. In this process, a cooling quantity is supplied to the heat exchanger via a refrigeration cycle. The compressed natural gas is cooled by the heat exchanger and subsequently expanded to a lower pressure to produce a liquid stream which passes into a first-stage separator. The boiling vapor passes through the heat exchanger and is compressed and cooled before being recycled back through the heat exchanger. The cooled boiling gas is compressed, subsequently expanded and passes into a second-stage separator, separated from the process. The liquid stream produced by the second-stage separator passes into the first-stage separator to produce a compressed liquid at a temperature of approximately -112 °C and sufficient pressure for the liquid to be at or below the liquid bubbling point. The process is revealed for the re-liquefaction of a boiling gas that is produced by compressing liquefied natural gas. In this process, a cooling quantity is supplied to the heat exchanger via a refrigeration cycle. Natural gas is compressed, cooled by a heat exchanger, and further expanded to a lower pressure to produce a liquid stream, which passes into a first-stage separator. Boiling vapor emerges, passes through another heat exchanger, is compressed and cooled before being recycled back through the heat exchanger. The cooled boiling gas is compressed, expands, and passes into a second-stage separator, separating it from the process. The liquid stream produced by the second-stage separator passes into a first-stage separator to create a compressed liquid at a temperature of approximately -112°C, pressurized sufficiently to keep the liquid at or below its bubbling point.

Claims (5)

1. The process for compressing a boiling gas into a liquid, which is produced from compressed liquefied natural gas, consists of the following steps: (a) supplying a cooling volume to a heat exchanger via a refrigeration cycle; (b) passing the compressed natural gas through a heat exchanger to cool it; (c) the expansion of the cooled natural gas to a reduced pressure, thus liquefying it. (d) Separation in a first-order phase separator of any gas phase, if any vapor phase is present, after phase expansion (c), from the liquefied gas; (e) Re-liquefaction of the boiling gas is re-liquefied and reheated in a heat exchanger, by subsequent supply of a cooling volume to the heat exchanger; (f) Re-compression and cooling of the boiling gas; (g) Re-return of the re-compressed boiling gas to a heat exchanger to re-cool the re-compressed boiling gas; (h) Expansion of the re-compressed boiling gas to a lower pressure to induce (i) phase separation in the second-order separator of the gas and liquid phases of step (h); (j) passage of the liquid phase of step (I) to the first-order separator; (k) vapor recovery from the second-order separator; and (l) extraction of the liquid from the first-order separator in the form of compressed liquefied natural gas, which is heated to a temperature of approximately -112 °C (170 °F) and pressured sufficiently for the liquid to be at or below its bubbling point. 2. The process of claim 1 is subsequently incorporated with the step of the vapor recovery of step (k) through a heat exchanger. 3. The process of claim 1 is subsequently incorporated with a quantification step of the vapor recovered in step (k) by controlling the amount of cooling of the boiling gases out in the pathway through a heat exchanger. 4. The process of claim 1 involves the boiling gas being introduced into a process with a temperature above -112 °C (-170 °F) and a pressure above 1,379 kPa. 5. The process of claim number 4 involves the boiling of gas to a pressure exceeding 2,413 kPa.