Turbo Expander Design Considerations for Cryogenic Natural Gas Plants Without Molecular Sieve Application for Dehydration

摘要

Turbo expander utilization in natural gas cryogenic plants dates back to late 1950’s. The first gas plant with turbo expander design was installed in Corpus Christi Texas in 1958. Dehydration of natural gas is normally carried out upstream of turbo expanders. Hydrate formation inside turbo expander with variable inlet guide vanes, high speed and tight clearances causes serious operational problems. Dehydration of natural gas is achieved by molecular sieves and regeneration system in most cryogenic plants. Several gas plants have also designed with injection of hydrate inhibitors upstream of turbo expander instead of molecular sieves in the last two decades. This paper discusses design features of turbo expander for the latter applications where hydrate inhibitor injection is utilized to replace molecular sieves. The authors present their experiences and lesson learned from several gas plants.