Abstract:

An offshore FPSO project carries out separation, purification and liquefaction processes for natural gas extracted from offshore sources, so as to produce, store and transport liquefied petroleum gas (LPG) outward. The FPSO uses ship loading pumps for loading operations. After the loading is completed, the outgoing pipelines are purged using the overhead gas from LPG storage tanks. Once the purging is finished, the gaseous and liquid phase LPG in the system is promptly recovered. This paper examines the purging and recovery operation of an LPG vapor recovery compressor in the project, introduces the purging and recovery processes for the outgoing pipelines, and proposes some measures for ensuring the safe operation of the compressor. HYSYS simulations are performed to model the outlet temperature of the vaporizer and calculate the leakage rates under heat exchanger tube rupture scenarios, providing theoretical guidance for similar LPG loading operations.

Key words: LPG loading；safety valve calculation；heat exchanger tube rupture；pressure compensation for vaporizer ,