Automated process for cooldown of main cryogenic heat exchanger

F. CHEN, M. OKASINSKI and T. SABRAM, Air Products and Chemicals Inc.,  Allentown, Pennsylvania No matter how reliable an LNG plant is, situations will arise that require restart from a shutdown condition. These situations include initial plant startup after completion of construction, and restart after scheduled compressor or driver maintenance. LNG plant startup and restart involve several sequential steps. The feed gas receiving, compression (if applicable) and pretreatment systems are the first units to be commissioned. This commissioning order ensures that dry, clean feed gas is available for liquefaction and for refrigerant makeup. Depending on the specific liquefaction process used,