Refrigerated semipressurised LPG gas tanker

摘要

The liquefaction plant of this gas tanker is connected, via a suction line, to the vapour space of the cargo tank and, via a return line, is connected to the liquid space of the cargo tank, and has at least one seawater-cooled condenser and at least two compressors, of which at least one draws in and compresses vaporous cargo gas via the suction line. The compressed cargo gas is returned, after cooldown and condensation, into the tank via the return line. In the case of transporting cargo gases such as LNG, cooling and at least partial condensation of the compressed cargo gas takes place in a heat exchanger cooled by evaporating refrigerant. The second compressor is connected to this heat exchanger and the seawater-cooled condenser to form a closed circuit, in which a refrigerant is operating. The liquefaction plant can be switched over between an open plant having only one circuit, and a cascade arrangement of two circuits.