Integrated and Cost-effective Design Utilizes LNG Cryogenic Energy for Power Generation

Recycling valuable LNG cold energy released in the gasification process for power generation is the main cold energy utilization mode in present LNG receiving terminals, it can reduce the cost of LNG regasification, relieve CO₂ emission, and provide electric power demand for receiving terminals. Aiming at the current low exergetic efficiency of the Rankin and direct-expansion system in LNG receiving terminals, based on the existing technology and demand of receiving terminals, a new integrated and cost-effective design is carried out to recycle the LNG cold energy to power generation in this paper. In the improved processes, LNG cold energy is employed to cool chilling water to meet the cooling demand from air-conditioning, air compressor and intake gas for gas turbine of LNG receiving terminals. On the one hand, it saves 1124 kW power consumed by refrigerator to produce chilling water; on the other hand, low temperature overplus heat cooled by circulating cooling water in gas-fired power plant is used to heat natural gas and propane working fluid, which result in the total expansion work power of natural gas and propane turbine increased by 2558 kW, and the natural gas and propane thermal efficiencies are increased by 55.2% and 22.5%, respectively. Compared with the original processes, about 61.5 kW power is recycled per LNG ton in the new Rankin and Direct-expansion power generation technique, the energetic and exergetic efficiencies are increased by 38%, meanwhile it gains annual economic benefits of 30.92 million Yuan for the LNG receiving terminals.