Efficiency improvement of open-cycle cascaded refrigeration process
First Claim
Patent Images
1. A process for liquefying a pressurized gas stream comprising the steps of:
- (a) combining the pressurized gas stream and a first recycle gas stream as defined in step (j);
(b) cooling said stream of step (a) to near its liquefaction temperature;
(c) combining said stream of step (b) and a second recycle gas stream as defined in step (j);
(d) cooling and thereby condensing in major portion said stream of step (c);
(e) flowing said stream of step (d) through at least one pressure reduction means thereby producing a two-phase stream;
(f) separating the two-phase stream of step (e) into a return gas stream and a liquid stream;
(g) flowing said return gas stream of step (f) through an indirect heat exchange means thereby producing a warmed return gas stream;
(h) compressing said warmed return gas stream to a pressure greater than or equal to the pressure possessed by the pressurized gas stream of step (a) thereby producing a compressed return gas stream;
(i) cooling the compressed return gas stream of step (h) to a near ambient temperature, and(j) cooling further the compressed return gas stream of step (i) by flowing through an indirect heat exchange means which is in thermal contact with the indirect heat exchange means of step (g) wherein said cooling comprises cooling said compressed return gas stream in its entirety to a first temperature, splitting said stream into a first recycle gas stream and a second compressed return gas stream, and further cooling said second stream thereby producing a second recycle gas stream possessing a temperature lower than that of the first recycle gas stream and wherein the gas streams of step (g) and this step flow through their respective indirect heat exchange means in a generally countercurrent manner to one another.
2 Assignments
0 Petitions
Accused Products
Abstract
A process and apparatus for improving the efficiency of an open-cycle cascaded refrigeration process. Process efficiency is improved by the manner in which the compressed recycle stream is combined with the main process stream in the open refrigeration cycle.
94 Citations
29 Claims
-
1. A process for liquefying a pressurized gas stream comprising the steps of:
-
(a) combining the pressurized gas stream and a first recycle gas stream as defined in step (j); (b) cooling said stream of step (a) to near its liquefaction temperature; (c) combining said stream of step (b) and a second recycle gas stream as defined in step (j); (d) cooling and thereby condensing in major portion said stream of step (c); (e) flowing said stream of step (d) through at least one pressure reduction means thereby producing a two-phase stream; (f) separating the two-phase stream of step (e) into a return gas stream and a liquid stream; (g) flowing said return gas stream of step (f) through an indirect heat exchange means thereby producing a warmed return gas stream; (h) compressing said warmed return gas stream to a pressure greater than or equal to the pressure possessed by the pressurized gas stream of step (a) thereby producing a compressed return gas stream; (i) cooling the compressed return gas stream of step (h) to a near ambient temperature, and (j) cooling further the compressed return gas stream of step (i) by flowing through an indirect heat exchange means which is in thermal contact with the indirect heat exchange means of step (g) wherein said cooling comprises cooling said compressed return gas stream in its entirety to a first temperature, splitting said stream into a first recycle gas stream and a second compressed return gas stream, and further cooling said second stream thereby producing a second recycle gas stream possessing a temperature lower than that of the first recycle gas stream and wherein the gas streams of step (g) and this step flow through their respective indirect heat exchange means in a generally countercurrent manner to one another. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
-
-
15. A process for liquefying a pressurized natural gas stream possessing a pressure of greater than 500 psia and near ambient temperature comprising the steps of:
-
(a) cooling said gas stream to a first temperature significantly about the liquefaction temperature of said stream via a closed refrigeration cycle which employs a refrigerant comprised in a major portion of propane; (b) combining the pressurized gas stream and a first recycle gas stream as defined in step (k); (c) cooling said stream of step (a) to near its liquefaction temperature via a closed refrigeration cycle which employs a refrigerant comprised in major portion of ethylene, ethane or mixtures thereof; (d) combining said stream of step (c) and a second recycle gas stream as defined in step (k); (e) cooling and thereby condensing in major portion said stream of step (c) via the refrigeration system of step (d); (f) flowing said stream of step (e) through at least one pressure reduction means thereby producing a two-phase stream; (g) separating the two-phase stream of step (f) into a return gas stream and a second stream; (h) flowing said return gas stream of step (g) through an indirect heat exchange means thereby producing a warmed return gas stream; (i) compressing said warmed return gas stream to a pressure greater than or equal to the pressure possessed by the pressurized gas stream of step (b) thereby producing a compressed return gas stream; (j ) cooling the compressed return gas stream of step (i) to a near ambient temperature via the closed refrigeration cycle of step (a); (k) cooling further the compressed return gas stream of step (j) by flowing through an indirect heat exchange means which is in thermal contact with the indirect heat exchange means of step (h) wherein said cooling comprises cooling the compressed return gas stream in its entirety to a first temperature which is about equal to the temperature of the pressurized gas stream from step (a), splitting said stream into a first recycle gas stream and a second compressed return gas stream, and further cooling said second stream thereby producing a second recycle gas stream possessing a temperature lower than that of the first gas recycle stream and wherein the gas streams of step (g) and this step flows through their respective indirect heat exchange means in a manner countercurrent to one another. - View Dependent Claims (16, 17, 18)
-
-
19. In a process for liquefying a pressurized gas stream via an open-cycle, cascaded refrigeration process comprising a closed propane cycle with two or three stages of cooling, a closed ethylene, ethane or mixture thereof cycle with two or three stages of cooling, and an open methane cycle with at least two stages of pressure reduction and wherein the flash vapors from the pressure reduction stages are employed to cool the open methane cycle stream following pressurization and cooling to near ambient temperature, the improvement comprises
(a) cooling the open methane cycle stream via countercurrent heat transfer with one or more flash vapor streams to a first temperature; -
(b) splitting said cooled open methane cycle stream into a first cooled recycle stream and a second stream; (c) combining the first cooled recycle stream with the pressurized gas stream immediately upstream of the first stage of cooling in an ethane, ethylene or mixture thereof cycle; (d) further cooling the second stream via countercurrent heat transfer with one or more flash vapor streams to a second temperature thereby producing a second cooled recycle stream; (e) combining said second cooled recycle stream with the pressurized gas stream undergoing processing downstream of the first stage of cooling in the ethylene or ethane cycle but upstream of the stage wherein the stream is liquefied in major portion. - View Dependent Claims (20, 21, 22, 23)
-
-
24. An apparatus for liquefying a pressurized gas comprising:
-
(a) a conduit for a first recycle stream; (b) a conduit for a pressurized gas stream; (c) a conduit connected to said conduits of(a) and (b); (d) a chiller connected at the inlet end to conduit (c); (e) a conduit connected to the outlet end of the chiller of (d); (f) a conduit for a second recycle stream; (g) a conduit connected to said conduits of (e) and (f); (h) a condenser connected at the inlet end to said conduit of (g); (i) a conduit connected to said condenser of (h); (j) a pressure reduction means connected to said conduit of (i); (k) a conduit connected to said pressure reduction means; (l) a separator connected to the conduit of (k); (m) a conduit connected to the upper section of the separator for removal of a gas stream; (n) a conduit connected to the lower section of the separator for the removal of a liquid stream; (o) an indirect heat exchange means connected to said conduit of (m); (p) a conduit connected to said indirect heat exchange means; (q) a compressor which is connected at an inlet port location to said conduit of (p); (r) a conduit connected at an outlet port of said compressor; (s) an indirect heat exchange means connected to said conduit of (r) and situated in close proximity to the indirect heat exchange means of element (o) so as to provide for heat exchange between the two means, situated such that fluids flowing through such means flow generally countercurrent to one another, and to which is connected at some point along such means between the entrance and exit is the conduit of (a) and to which is connected at the exit end is the conduit of (f). - View Dependent Claims (25, 26, 27, 28, 29)
-
Specification