US 6,070,429 A · Nitrogen rejection system for liquified natural gas

Abstract

This invention concerns a method and an apparatus for removing nitrogen and other low boiling point inorganic components from pressurized LNG-bearing streams and streams produced therefrom. The removal of such components is accomplished via a novel pressure reduction/stripping methodology thereby producing at least one low BTU nitrogen-rich gas stream and at least one high BTU methane-rich stream which is suitable for recycle to an open methane cycle liquefaction process and/or employment as a high quality fuel gas.

Claims48

Dependent claims

A process for removing low boiling point inorganic components from a pressurized gas stream obtained from a pressurized LNG-bearing stream comprising the steps of:

(a) splitting said gas stream into a first stream and a second stream;
(b) cooling said first stream thereby producing a liquid-bearing stream;
(c) contacting said liquid-bearing stream and second stream in a countercurrent, multistage manner thereby producing a first gas stream and a liquid stream;
(d) splitting said first gas stream into a second gas stream and a third gas stream;
(e) cooling and reducing the pressure of said second gas stream thereby producing a second liquid-bearing stream;
(f) reducing the pressure of said third gas stream;
(g) contacting second liquid-bearing stream and reduced pressure third stream in a countercurrent, multistage manner thereby producing a fourth gas and a second liquid stream;
(h) cooling and reducing the pressure of said fourth gas stream thereby producing a third liquid-bearing stream;
(i) reducing the pressure of said second liquid stream;
(j) contacting said third liquid-bearing stream and reduced pressure third liquid stream in a countercurrent, multistage manner thereby producing a low BTU nitrogen-rich gas stream and a third liquid stream which upon sufficient warming becomes a high BTU methane-rich gas stream;
and
(k) warming said low BTU nitrogen-rich gas stream and third liquid stream by employing said streams as cooling agents for steps (e) and (h).

9 more elements

In a cascaded refrigeration process for liquefying natural gas employing a closed two- or three-stage propane refrigeration cycle, a closed two- or three-stage ethane or ethylene refrigeration cycle and an open methane refrigeration cycle employing three stages of compression, the improvement concerns a method of removing low boiling point inorganic compounds from the open methane cycle comprising the steps of:

(a) splitting said flash gas stream from the first pressure reduction stage in the open methane cycle into a recycle stream which is ultimately return to the methane compressor and a process stream;
(b) splitting said process stream into a first stream and a second stream;
(c) cooling said first stream thereby producing a liquid-bearing stream;
(d) contacting said liquid-bearing stream and second stream in a countercurrent, multistage manner thereby producing a first gas and a liquid stream;
(e) splitting said first gas stream into a second gas stream and a third gas stream;
(f) cooling and reducing the pressure of said second gas stream thereby producing a second liquid-bearing stream;
(g) reducing the pressure of said third gas stream;
(h) contacting said second liquid-bearing stream and reduced pressure third stream in a countercurrent, multistage manner thereby producing a fourth gas and a second liquid stream;
(i) cooling and reducing the pressure of said fourth gas stream thereby producing a third liquid-bearing stream;
(j) reducing the pressure of said second liquid stream;
(k) contacting said third liquid-bearing stream and reduced pressure third liquid stream in a countercurrent, multistage manner thereby producing a low BTU nitrogen-rich gas stream and a third liquid stream which upon sufficient warming becomes a high BTU methane-rich gas stream;
(l) warming said gas stream of (k) and third liquid stream by employing said streams as cooling agents for steps (f) and (i);
(m) combining said warmed third liquid stream of step (j) with a gas stream on the low pressure side of the first stage of methane compression;
(n) reducing the pressure of said liquid stream of (d);
(o) warming said stream of (n) by employing said stream as a cooling agent for step (c);
and
(p) combining said stream of step (o) with a gas stream on the low pressure side of the second stage of methane compression.

14 more elements

A process for removing low boiling point inorganic components from a pressurized LNG-bearing stream comprising the steps of:

(a) splitting said stream into at least a first stream and a second stream;
(b) cooling and reducing the pressure of said first stream;
(c) reducing the pressure of said second stream;
(d) contacting said cooled and reduced pressure first stream and reduced pressure second stream in a countercurrent, multistage manner thereby producing a first gas and a liquid stream;
(e) splitting said first gas stream into a second gas stream and a third gas stream;
(f) cooling and reducing the pressure of said second gas stream thereby producing a liquid-bearing stream;
(g) reducing the pressure of said third gas stream;
(h) contacting said liquid-bearing stream and reduced pressure third stream in a countercurrent, multistage manner thereby producing a fourth gas and a second liquid stream;
(i) cooling and reducing the pressure of said fourth gas stream thereby producing a second liquid-bearing stream;
(j) reducing the pressure of said second liquid stream;
(k) contacting said second liquid-bearing stream and reduced pressure third liquid stream in a countercurrent, multistage manner thereby producing a low BTU nitrogen-rich gas stream and a third liquid stream which upon sufficient warming becomes a high BTU methane-rich gas stream;
and
(l) warming said gas stream of (k) and third liquid stream by employing said streams as cooling agents for steps (f) and (i).

10 more elements

In a cascaded refrigeration process for liquefying natural gas employing a closed two- or three-stage propane refrigeration cycle, a closed two- or three-stage ethane or ethylene refrigeration cycle and an open methane refrigeration cycle employing three stages of compression, the improvement concerns a method of removing low boiling point inorganic components from the methane cycle comprising the steps of;

(a) splitting the pressurized LNG-bearing stream from the final stage of ethylene cooling into at least a first stream, a second stream, and one or more other streams to be conventionally flashed to near-atmospheric pressure;
(b) cooling and reducing the pressure of said first stream thereby producing a liquid-bearing stream;
(c) reducing the pressure of said second stream;
(d) contacting said liquid-bearing stream and reduced pressure second stream in a countercurrent, multistage manner thereby producing a first gas and a liquid stream;
(e) splitting said first gas stream into a second gas stream and a third gas stream;
(f) cooling and reducing the pressure of said second gas stream thereby producing a second liquid-bearing stream;
(g) reducing the pressure of said third gas stream;
(h) contacting said second liquid-bearing stream and reduced pressure third stream in a countercurrent, multistage manner thereby producing a fourth gas and a second liquid stream;
(i) cooling and reducing the pressure of said fourth gas stream thereby producing a third liquid-bearing stream;
(j) reducing the pressure of said second liquid stream;
(k) contacting said third liquid-bearing stream and reduced pressure third liquid stream in a countercurrent, multistage manner thereby producing a low BTU nitrogen-rich gas, and a third liquid stream which upon sufficient warming becomes a high BTU methane-rich gas stream;
(l) warming said fifth gas stream and third liquid stream by employing said streams as cooling agents for steps (f) and (i);
and
(m) combining said warmed third liquid stream of step (l) with a gas stream on the low pressure side of the first stage of methane compression.

11 more elements

An apparatus for removing low boiling point inorganic compounds from a pressurized hydrocarbon-rich gas stream comprising:

(a) first and second splitting means;
(b) first, second, third, fourth, fifth and sixth indirect heat exchange means;
(c) first, second and third stripper columns;
(d) first, second and third pressure reduction means;
(e) a first conduit connected to the first splitting means;
(f) a second conduit connected between the first splitting means and the inlet to the first indirect heat exchange means;
(g) a third conduit connected to the outlet of the first indirect heat exchange means and the upper section of the first stripper column;
(h) a fourth conduit connected to the first splitting means and the lower section of the first stripper column;
(i) a fifth conduit connected to the bottom of the first stripper column and the first pressure reduction means;
(j) a sixth conduit connected to the first pressure reduction means and the inlet to the second indirect heat exchange means wherein the first heat exchange means is situated in close proximity to the first indirect heat exchange means so as to provide for heat exchange between the two means;
(k) a seventh conduit connected to the outlet of the second indirect heat exchange means;
(l) an eighth conduit connected to the top of the first stripper column and the second splitting means;
(m) a ninth conduit connected between the second splitting means and the inlet to the third indirect heat exchange means;
(n) a tenth conduit connected to the outlet of the third indirect heat exchange means and the upper section of the second stripper column;
(o) an eleventh conduit connected to the second splitting means and the upper section of the second stripper column;
(p) a twelfth conduit connected to the top of the second stripper column and the inlet to the fourth indirect heat exchange means;
(q) a thirteenth conduit connected to the outlet of the fourth indirect heat exchange means and the third pressure reduction means;
(r) a fourteenth conduit connected to the third pressure reduction means and the upper section of the third stripper column;
(s) a fifteenth conduit connected to the bottom of the second stripper column and the second pressure reduction means;
(t) a sixteenth conduit connected to the second pressure reduction means and the lower section of the third stripper column;
(u) a seventeenth conduit connected to the top of the third stripper column and the inlet to the fifth indirect heat exchange means;
(v) an eighteenth conduit connected to the bottom of the third stripper column and the inlet to the sixth indirect heat exchange means;
(w) a nineteenth conduit connected to the outlet of the fifth indirect heat exchange means;
and
(x) a twentieth conduit connected to the outlet of the sixth indirect heat exchange means;
wherein said third and fourth indirect heat exchange means are situated in sufficiently close proximity to the fifth and sixth indirect heat exchange means so as to provide for heat exchange.

23 more elements

An apparatus for removing low boiling point inorganic components from a pressurized LNG-bearing stream comprising:

(a) first and second splitting means;
(b) first, second, third, fourth, and fifth indirect heat exchange means;
(c) a fuel column;
(d) first and second stripper columns;
(e) first, second third, fourth, fifth and sixth pressure reduction means;
(f) a first conduit connected to the first splitting means;
(g) a second conduit connected between the first splitting means and the inlet to the first indirect heat exchange means;
(h) a third conduit connected to the outlet of the first indirect heat exchange means and the first pressure reduction means;
(i) a fourth conduit connected to the first pressure reduction means and the fuel column;
(j) a fifth conduit connected to the first splitting means and the second pressure reduction means;
(k) a sixth conduit connected to the second pressure reduction means and the lower section of the fuel column;
(l) a seventh conduit connected to the bottom of the fuel column;
(m) an eighth conduit connected to the top of the fuel column and to the second splitting means;
(n) a ninth conduit connected to the second splitting means and the third pressure reduction means;
(o) a tenth conduit connected to the second splitting means and inlet to the second indirect heat exchange means;
(p) an eleventh conduit connected to the outlet to the second indirect heat exchange means and the upper section of the first stripper column;
(q) a twelfth conduit connected between the second splitting means and the lower section of the first stripper column;
(r) a thirteenth conduit connected to the top of the first stripper column and the inlet to the third indirect heat exchange means;
(s) a fourteenth conduit connected to the outlet to the third indirect heat exchange means and the fifth pressure reduction means;
(t) a fifteenth conduit connected to the fifth pressure reduction means and the upper section of the second stripper column;
(u) a sixteenth connected to the bottom of the first stripper column and the fourth pressure reduction means;
(v) a seventeenth conduit connected to the fourth pressure reduction means and the lower section of the second stripper column;
(w) an eighteenth conduit connected to the top of the second stripper column and the inlet to the fourth indirect heat exchange means;
(x) a nineteenth conduit connected to the bottom of the second stripper column and the inlet to the fifth indirect heat exchange means;
(y) a twentieth conduit connected to the outlet of the fourth indirect heat exchange means;
and
(z) a twenty-first conduit connected to the outlet of the fifth indirect heat exchange means;
wherein said second and third indirect heat exchange means are situated in sufficiently close proximity to the fourth and fifth indirect heat exchange means so as to provide for heat exchange.

25 more elements

Dependencies are inferred from the claim text.

Abstract

Claims48

Dependent claims

A process for removing low boiling point inorganic components from a pressurized gas stream obtained from a pressurized LNG-bearing stream comprising the steps of:

(a) splitting said gas stream into a first stream and a second stream;
(b) cooling said first stream thereby producing a liquid-bearing stream;
(c) contacting said liquid-bearing stream and second stream in a countercurrent, multistage manner thereby producing a first gas stream and a liquid stream;
(d) splitting said first gas stream into a second gas stream and a third gas stream;
(e) cooling and reducing the pressure of said second gas stream thereby producing a second liquid-bearing stream;
(f) reducing the pressure of said third gas stream;
(g) contacting second liquid-bearing stream and reduced pressure third stream in a countercurrent, multistage manner thereby producing a fourth gas and a second liquid stream;
(h) cooling and reducing the pressure of said fourth gas stream thereby producing a third liquid-bearing stream;
(i) reducing the pressure of said second liquid stream;
(j) contacting said third liquid-bearing stream and reduced pressure third liquid stream in a countercurrent, multistage manner thereby producing a low BTU nitrogen-rich gas stream and a third liquid stream which upon sufficient warming becomes a high BTU methane-rich gas stream;
and
(k) warming said low BTU nitrogen-rich gas stream and third liquid stream by employing said streams as cooling agents for steps (e) and (h).

9 more elements

(a) splitting said flash gas stream from the first pressure reduction stage in the open methane cycle into a recycle stream which is ultimately return to the methane compressor and a process stream;
(b) splitting said process stream into a first stream and a second stream;
(c) cooling said first stream thereby producing a liquid-bearing stream;
(d) contacting said liquid-bearing stream and second stream in a countercurrent, multistage manner thereby producing a first gas and a liquid stream;
(e) splitting said first gas stream into a second gas stream and a third gas stream;
(f) cooling and reducing the pressure of said second gas stream thereby producing a second liquid-bearing stream;
(g) reducing the pressure of said third gas stream;
(h) contacting said second liquid-bearing stream and reduced pressure third stream in a countercurrent, multistage manner thereby producing a fourth gas and a second liquid stream;
(i) cooling and reducing the pressure of said fourth gas stream thereby producing a third liquid-bearing stream;
(j) reducing the pressure of said second liquid stream;
(k) contacting said third liquid-bearing stream and reduced pressure third liquid stream in a countercurrent, multistage manner thereby producing a low BTU nitrogen-rich gas stream and a third liquid stream which upon sufficient warming becomes a high BTU methane-rich gas stream;
(l) warming said gas stream of (k) and third liquid stream by employing said streams as cooling agents for steps (f) and (i);
(m) combining said warmed third liquid stream of step (j) with a gas stream on the low pressure side of the first stage of methane compression;
(n) reducing the pressure of said liquid stream of (d);
(o) warming said stream of (n) by employing said stream as a cooling agent for step (c);
and
(p) combining said stream of step (o) with a gas stream on the low pressure side of the second stage of methane compression.

14 more elements

A process for removing low boiling point inorganic components from a pressurized LNG-bearing stream comprising the steps of:

(a) splitting said stream into at least a first stream and a second stream;
(b) cooling and reducing the pressure of said first stream;
(c) reducing the pressure of said second stream;
(d) contacting said cooled and reduced pressure first stream and reduced pressure second stream in a countercurrent, multistage manner thereby producing a first gas and a liquid stream;
(e) splitting said first gas stream into a second gas stream and a third gas stream;
(f) cooling and reducing the pressure of said second gas stream thereby producing a liquid-bearing stream;
(g) reducing the pressure of said third gas stream;
(h) contacting said liquid-bearing stream and reduced pressure third stream in a countercurrent, multistage manner thereby producing a fourth gas and a second liquid stream;
(i) cooling and reducing the pressure of said fourth gas stream thereby producing a second liquid-bearing stream;
(j) reducing the pressure of said second liquid stream;
(k) contacting said second liquid-bearing stream and reduced pressure third liquid stream in a countercurrent, multistage manner thereby producing a low BTU nitrogen-rich gas stream and a third liquid stream which upon sufficient warming becomes a high BTU methane-rich gas stream;
and
(l) warming said gas stream of (k) and third liquid stream by employing said streams as cooling agents for steps (f) and (i).

10 more elements

In a cascaded refrigeration process for liquefying natural gas employing a closed two- or three-stage propane refrigeration cycle, a closed two- or three-stage ethane or ethylene refrigeration cycle and an open methane refrigeration cycle employing three stages of compression, the improvement concerns a method of removing low boiling point inorganic components from the methane cycle comprising the steps of;

(a) splitting the pressurized LNG-bearing stream from the final stage of ethylene cooling into at least a first stream, a second stream, and one or more other streams to be conventionally flashed to near-atmospheric pressure;
(b) cooling and reducing the pressure of said first stream thereby producing a liquid-bearing stream;
(c) reducing the pressure of said second stream;
(d) contacting said liquid-bearing stream and reduced pressure second stream in a countercurrent, multistage manner thereby producing a first gas and a liquid stream;
(e) splitting said first gas stream into a second gas stream and a third gas stream;
(f) cooling and reducing the pressure of said second gas stream thereby producing a second liquid-bearing stream;
(g) reducing the pressure of said third gas stream;
(h) contacting said second liquid-bearing stream and reduced pressure third stream in a countercurrent, multistage manner thereby producing a fourth gas and a second liquid stream;
(i) cooling and reducing the pressure of said fourth gas stream thereby producing a third liquid-bearing stream;
(j) reducing the pressure of said second liquid stream;
(k) contacting said third liquid-bearing stream and reduced pressure third liquid stream in a countercurrent, multistage manner thereby producing a low BTU nitrogen-rich gas, and a third liquid stream which upon sufficient warming becomes a high BTU methane-rich gas stream;
(l) warming said fifth gas stream and third liquid stream by employing said streams as cooling agents for steps (f) and (i);
and
(m) combining said warmed third liquid stream of step (l) with a gas stream on the low pressure side of the first stage of methane compression.

11 more elements

An apparatus for removing low boiling point inorganic compounds from a pressurized hydrocarbon-rich gas stream comprising:

(a) first and second splitting means;
(b) first, second, third, fourth, fifth and sixth indirect heat exchange means;
(c) first, second and third stripper columns;
(d) first, second and third pressure reduction means;
(e) a first conduit connected to the first splitting means;
(f) a second conduit connected between the first splitting means and the inlet to the first indirect heat exchange means;
(g) a third conduit connected to the outlet of the first indirect heat exchange means and the upper section of the first stripper column;
(h) a fourth conduit connected to the first splitting means and the lower section of the first stripper column;
(i) a fifth conduit connected to the bottom of the first stripper column and the first pressure reduction means;
(j) a sixth conduit connected to the first pressure reduction means and the inlet to the second indirect heat exchange means wherein the first heat exchange means is situated in close proximity to the first indirect heat exchange means so as to provide for heat exchange between the two means;
(k) a seventh conduit connected to the outlet of the second indirect heat exchange means;
(l) an eighth conduit connected to the top of the first stripper column and the second splitting means;
(m) a ninth conduit connected between the second splitting means and the inlet to the third indirect heat exchange means;
(n) a tenth conduit connected to the outlet of the third indirect heat exchange means and the upper section of the second stripper column;
(o) an eleventh conduit connected to the second splitting means and the upper section of the second stripper column;
(p) a twelfth conduit connected to the top of the second stripper column and the inlet to the fourth indirect heat exchange means;
(q) a thirteenth conduit connected to the outlet of the fourth indirect heat exchange means and the third pressure reduction means;
(r) a fourteenth conduit connected to the third pressure reduction means and the upper section of the third stripper column;
(s) a fifteenth conduit connected to the bottom of the second stripper column and the second pressure reduction means;
(t) a sixteenth conduit connected to the second pressure reduction means and the lower section of the third stripper column;
(u) a seventeenth conduit connected to the top of the third stripper column and the inlet to the fifth indirect heat exchange means;
(v) an eighteenth conduit connected to the bottom of the third stripper column and the inlet to the sixth indirect heat exchange means;
(w) a nineteenth conduit connected to the outlet of the fifth indirect heat exchange means;
and
(x) a twentieth conduit connected to the outlet of the sixth indirect heat exchange means;
wherein said third and fourth indirect heat exchange means are situated in sufficiently close proximity to the fifth and sixth indirect heat exchange means so as to provide for heat exchange.

23 more elements

An apparatus for removing low boiling point inorganic components from a pressurized LNG-bearing stream comprising:

(a) first and second splitting means;
(b) first, second, third, fourth, and fifth indirect heat exchange means;
(c) a fuel column;
(d) first and second stripper columns;
(e) first, second third, fourth, fifth and sixth pressure reduction means;
(f) a first conduit connected to the first splitting means;
(g) a second conduit connected between the first splitting means and the inlet to the first indirect heat exchange means;
(h) a third conduit connected to the outlet of the first indirect heat exchange means and the first pressure reduction means;
(i) a fourth conduit connected to the first pressure reduction means and the fuel column;
(j) a fifth conduit connected to the first splitting means and the second pressure reduction means;
(k) a sixth conduit connected to the second pressure reduction means and the lower section of the fuel column;
(l) a seventh conduit connected to the bottom of the fuel column;
(m) an eighth conduit connected to the top of the fuel column and to the second splitting means;
(n) a ninth conduit connected to the second splitting means and the third pressure reduction means;
(o) a tenth conduit connected to the second splitting means and inlet to the second indirect heat exchange means;
(p) an eleventh conduit connected to the outlet to the second indirect heat exchange means and the upper section of the first stripper column;
(q) a twelfth conduit connected between the second splitting means and the lower section of the first stripper column;
(r) a thirteenth conduit connected to the top of the first stripper column and the inlet to the third indirect heat exchange means;
(s) a fourteenth conduit connected to the outlet to the third indirect heat exchange means and the fifth pressure reduction means;
(t) a fifteenth conduit connected to the fifth pressure reduction means and the upper section of the second stripper column;
(u) a sixteenth connected to the bottom of the first stripper column and the fourth pressure reduction means;
(v) a seventeenth conduit connected to the fourth pressure reduction means and the lower section of the second stripper column;
(w) an eighteenth conduit connected to the top of the second stripper column and the inlet to the fourth indirect heat exchange means;
(x) a nineteenth conduit connected to the bottom of the second stripper column and the inlet to the fifth indirect heat exchange means;
(y) a twentieth conduit connected to the outlet of the fourth indirect heat exchange means;
and
(z) a twenty-first conduit connected to the outlet of the fifth indirect heat exchange means;
wherein said second and third indirect heat exchange means are situated in sufficiently close proximity to the fourth and fifth indirect heat exchange means so as to provide for heat exchange.

25 more elements

Dependencies are inferred from the claim text.

Nitrogen rejection system for liquified natural gas

Life of this patent

Abstract

Claims48

Nitrogen rejection system for liquified natural gas

Life of this patent

Abstract

Claims48