Closed loop single mixed refrigerant process

In a closed loop single mixed refrigerant process for cooling a fluid material through a temperature range exceeding 200.degree. F. by heat exchange with a single mixed refrigerant in a closed loop refrigeration cycle comprising:

• compressing gaseous mixed refrigerant in a compressor to produce a compressed mixed refrigerant;
• Cooling the compressed mixed refrigerant to produce a mixture of a condensed portion of the mixed refrigerant and a gaseous refrigerant;
• separating the condensed portion of the mixed refrigerant;
• combining the condensed portion of the mixed refrigerant and the gaseous refrigerant to reconstitute the mixed refrigerant;
• charging the mixed refrigerant to a refrigeration zone wherein the mixed refrigerant is passed in countercurrent heat exchange with a low temperature coolant to produce a substantially liquid mixed refrigerant;
• passing the substantially liquid mixed refrigerant through an expansion valve to produce the low temperature coolant;
• charging the fluid material to the refrigeration zone wherein the fluid material is passed in countercurrent heat exchange with the low temperature coolant;
• recovering the fluid material in a substantially liquid phase;
• recovering the mixed refrigerant after the countercurrent heat exchange in a substantially gaseous phase;
• and
• recycling the gaseous mixed refrigerant to the compressor, the improvement comprising;
• compressing the gaseous mixed refrigerant in a first stage compressor;
• cooling the compressed mixed refrigerant from the first stage compressor to produce a first stage mixture of a first stage condensed liquid refrigerant rich in higher boiling point components of the mixed refrigerant and a first stage gaseous refrigerant;
• separating the first stage condensed liquid refrigerant from the first stage gaseous refrigerant;
• compressing the first stage gaseous refrigerant in a second stage compressor;
• cooling the compressed first stage gaseous refrigerant to produce a second stage mixture of a second stage ;condensed liquid refrigerant and a second stage gaseous refrigerant;
• separating the second stage condensed liquid and the second stage gaseous refrigerant;
• combining the first stage condensed liquid refrigerate, the second stage condensed liquid refrigerant and the second stage gaseous refrigerant to reconstitute the compressed mixed refrigerant;
• and
• charging the compressed, reconstituted, mixed refrigerant to the refrigeration zone.

A closed loop single mixed refrigerant system comprising:

• a) a mixed refrigerant suction drum;
• b) a first compressor having an inlet in fluid communication with a gaseous mixed refrigerant outlet from the mixed refrigerant storage drum;
• c) a first condenser having an inlet in fluid communication with an outlet from the first compressor;
• d) a first refrigerant separator having an inlet in fluid communication with an outlet from the first condenser;
• e) a second compressor having an inlet in fluid communication with a gaseous refrigerant outlet from the first refrigerant separator;
• f) a second condenser having an inlet in fluid communication with an outlet from the second compressor;
• g) a second refrigerant separator having an inlet in fluid communication with an outlet from the second condenser and a liquid refrigerant outlet from the first refrigerant separator;
• h) a refrigeration vessel including a first heat exchange passageway in fluid communication with a gaseous refrigerant outlet from the second refrigerant separator and a liquid refrigerant outlet from the second refrigerant separator, a second heat exchange passageway in fluid communication with a source of a fluid material which is to be cooled, a third heat exchange passageway countercurrently positioned in the refrigeration vessel with respect to the first heat exchange passageway and the second heat exchange passageway, and an expansion valve in fluid communication with an outlet from the first heat exchange passageway and an inlet to the third heat exchange passageway;
• i) a recycled refrigerant line in fluid communication with an outlet from the third heat exchange passageway and an inlet to the mixed refrigerant suction drum;
• and,
• j) a product line in fluid communication with an outlet from the second heat exchange passageway.