New FPSO design produces LNG from offshore sources

The economics of liquefied natural gas (LNG) production and the design philosophy of an LNG floating production storage and offloading (FPSO) plant are considered. Merlin Production Inc., in cooperation with Costain Oil, Gas and Process Ltd and Moss Maritime AS has demonstrated that an economically viable floating LNG plant can be designed, built and operated. The vessel design and process design are described. The selection of the refrigeration cycle is discussed. Three refrigeration technologies were considered: cascade, mixed refrigerant and expander refrigeration. A double-nitrogen expander cycle was selected. The design of the FPSO LNG plant is discussed with reference to power generation, process cooling, ancillary utilities and effluent minimisation. Cargo transfer, relative motion between the floating structure and ship, manpower requirements, LNG containment systems and safety issues are considered.