System and method for combined liquefaction and densification of oxygen

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.