System and method for combined liquefaction and densification of oxygen

Abstract

A system and method for the production and supply of a densified, liquid oxidant to a space vehicle launch facility with one or more launch platforms is provided. A low pressure gaseous oxygen stream is piped from a nearby air separation unit and is then liquefied and densified in a two-stage, integrated liquefaction/densification system. The first refrigeration stage is a nitrogen based reverse Brayton cycle refrigeration cycle, that liquefies the gaseous oxygen and subcools the resulting liquid oxygen to a temperature of about 81 Kelvin. The second refrigeration stage is a mixed refrigerant loop containing some combination of helium and/or neon refrigerants that densifies the liquid oxygen to a temperature of about 57 Kelvin. The integrated liquefaction and densification system may also be configured to densify liquid methane or other propellants used in space vehicle launches.

1 . A system for production of a densified, liquid oxygen stream from a low pressure gaseous oxygen stream, the system comprises:
 a first refrigeration stage configured to receive a first refrigerant and flow the first refrigerant through at least one first heat exchanger to cool the low pressure gaseous oxygen stream and liquefy the cooled low pressure gaseous oxygen stream to yield a liquid oxygen stream; and   a second refrigeration stage configured to flow a helium or neon containing second refrigerant through at least one second heat exchanger to subcool the liquid oxygen stream and yield a densified, liquid oxygen stream; and   wherein the first refrigeration stage further comprises:   a first warm refrigeration circuit, a second cold refrigeration circuit, a residual refrigeration circuit, and one or more recycle circuits;   wherein the first refrigerant flowing through the first heat exchanger is split into a first warm portion of the first refrigerant stream in the first warm refrigeration circuit, a second cold portion of the first refrigerant stream in the second cold refrigeration circuit, and a residual portion of the first refrigerant stream in the residual refrigeration circuit;   a warm turbine configured to expand the first warm portion the first refrigerant stream to yield an intermediate pressure warm exhaust;   a cold turbine configured to expand the second cold portion the first refrigerant stream to yield an intermediate pressure cold exhaust;   an expansion valve for expanding the residual portion of the first refrigerant stream;   wherein the warm exhaust and the cold exhaust are recycled in the one or more recycle circuits via the first heat exchanger to cool the low pressure gaseous oxygen stream;   a first subcooler configured to receive all or a part of the expanded residual portion of the first refrigerant stream and liquefy the cooled low pressure gaseous oxygen stream and yield a first refrigerant return stream that is recycled via the one or more recycle circuits ; and   one or more first refrigerant recycle compressors configured to compress the recycled warm exhaust, the recycled cold exhaust, and the recycled first refrigerant return stream.   
     
     
         2 . The system for production of a densified, liquid oxygen stream of  claim 1  wherein the first refrigerant comprises nitrogen and the second refrigerant comprises a nitrogen and neon containing mixture. 
     
     
         3 . The system for production of a densified, liquid oxygen stream of  claim 2  wherein the second refrigeration stage is a closed loop refrigeration stage and further comprises:
 a second refrigerant recycle compressor disposed downstream of the second heat exchanger and configured to compress the second refrigerant; and 
 a second refrigerant turbine disposed upstream of the second heat exchanger and configured to expand the compressed second refrigerant. 
 
     
     
         4 . The system for production of a densified, liquid oxygen stream of  claim 1  wherein:
 the expanded residual portion of the first refrigerant stream is split into a first expanded residual portion and a second expanded residual portion; 
 the first expanded residual portion is received by the first subcooler and the second expanded residual portion is further expanded and recycled via the first heat exchanger as a low pressure return stream; and 
 the low pressure return stream is compressed in the one or more first refrigerant recycle compressors. 
 
     
     
         5 . The system for production of a densified, liquid oxygen stream of  claim 4  wherein the first refrigeration stage further comprises a first refrigerant subcooler configured to subcool the low pressure return stream via indirect heat exchange with the expanded residual portion of the first refrigerant stream. 
     
     
         6 . The system for production of a densified, liquid oxygen stream of  claim 1  wherein:
 the first refrigeration stage and the second refrigeration stage are disposed on moveable platforms; 
 the moveable platforms with the first refrigeration stage and the second refrigeration stage are disposed proximate a space vehicle launch platform at a launch facility; and 
 the low pressure gaseous oxygen is supplied to the launch facility or to a launch platform at the launch facility via a pipeline from a nearby air separation unit and the densified, liquid oxygen stream is stored in a storage tank for use as an oxidant for a space vehicle propulsion system. 
 
     
     
         7 . The system for production of a densified, liquid oxygen stream of  claim 1  wherein the low pressure gaseous oxygen stream is at a pressure greater than 1.5 bar(a). 
     
     
         8 . The system for production of a densified, liquid oxygen stream of  claim 1  wherein the one or more first refrigerant recycle compressors are configured to compress the recycled warm exhaust, the recycled cold exhaust, and the recycled first refrigerant return stream to a pressure greater than about 50 bar(a). 
     
     
         9 . The system for production of a densified, liquid oxygen stream of  claim 1  wherein the intermediate pressure warm exhaust and the intermediate pressure cold exhaust are at a pressure between about 5 bar(a) and 10 bar(a). 
     
     
         10 . The system for production of a densified, liquid oxygen stream of  claim 4  wherein the low pressure return stream is at a pressure of between 1.5 bar(a) and 3.0 bar(a). 
     
     
         11 . A system for production of a densified, liquid oxygen stream from a gaseous oxygen stream, the system comprises:
 a first refrigeration stage configured to receive a first refrigerant and flow the first refrigerant through a first primary heat exchanger to cool the gaseous oxygen stream and liquefy the cooled gaseous oxygen stream to yield a liquid oxygen stream;   a second refrigeration stage configured to flow a second refrigerant through a second heat exchanger to subcool the liquid oxygen stream and yield a densified, liquid oxygen stream;   wherein the first refrigeration stage further comprises:   a first warm refrigeration circuit, a second cold refrigeration circuit, a residual refrigeration circuit, and a recycle circuit;   wherein the first refrigerant flowing through the first heat exchanger is split into a first warm portion of the first refrigerant stream in the first warm refrigeration circuit, a second cold portion of the first refrigerant stream in the second cold refrigeration circuit, and a residual portion of the first refrigerant stream in the residual refrigeration circuit;   a warm turbine configured to expand the first warm portion the first refrigerant stream to yield an intermediate pressure warm exhaust;   a cold turbine configured to expand the second cold portion the first refrigerant stream to yield an intermediate pressure cold exhaust;   an expansion valve for expanding the residual portion of the first refrigerant stream;   wherein the warm exhaust, the cold exhaust, and a first refrigerant return stream are recycled in the one or more recycle circuits via the first heat exchanger to cool the low pressure gaseous oxygen stream;   a first subcooler configured to receive all or a part of the expanded residual portion of the first refrigerant stream and liquefy the cooled low pressure gaseous oxygen stream and yield a first refrigerant return stream that is recycled via the one or more recycle circuits; and   one or more first refrigerant recycle compressors configured to compress the recycled warm exhaust, the recycled cold exhaust, and the recycled first refrigerant return stream; and   wherein the second refrigeration stage further comprises an auxiliary heat exchanger configured to cool the second refrigerant via indirect heat exchange with a diverted portion of the cold exhaust and wherein the diverted portion of the cold exhaust is then recycled to the one or more first refrigerant recycle compressors.   
     
     
         12 . The system for production of a densified, liquid oxygen stream of  claim 11  wherein the first refrigerant comprises nitrogen and the second refrigerant comprises a nitrogen and neon containing mixture. 
     
     
         13 . The system for production of a densified, liquid oxygen stream of  claim 11  wherein the second refrigeration stage further comprises:
 a second refrigerant recycle compressor configured to compress the second refrigerant; and 
 a second refrigerant turbine disposed upstream of the second heat exchanger and configured to expand the compressed second refrigerant 
 
     
     
         14 . The system for production of a densified, liquid oxygen stream of  claim 12  wherein:
 the expanded residual portion of the first refrigerant stream is split into a first expanded residual portion and a second expanded residual portion; 
 the first expanded residual portion is received by the first subcooler and the second expanded residual portion is further expanded and recycled via the first heat exchanger as a low pressure return stream; and 
 the low pressure return stream is compressed in the one or more first refrigerant recycle compressors. 
 
     
     
         15 . The system for production of a densified, liquid oxygen stream of  claim 14  wherein the first refrigeration stage further comprises a nitrogen subcooler configured to subcool the low pressure return stream via indirect heat exchange with the expanded residual portion of the first refrigerant stream. 
     
     
         16 . The system for production of a densified, liquid oxygen stream of  claim 11  wherein:
 the first refrigeration stage and the second refrigeration stage are disposed on moveable platforms; 
 the moveable platforms with the first refrigeration stage and the second refrigeration stage are disposed proximate a space vehicle launch platform at a launch facility; and 
 the low pressure gaseous oxygen is supplied to the launch facility via a pipeline from a nearby air separation unit and the densified, liquid oxygen stream is stored in a storage tank for use as an oxidant for a space vehicle propulsion system.