Managing Operation of LNG Plant with Tube-Leaked Cryogenic Heat Exchanger

Abstract This paper describes how Tangguh LNG successfully managed tube-leaked on main cryogenic heat exchangers (MCHE) without compromising safety or production. It shows systematic methods to maintain production with adequate mitigation measures without increasing risk on safety and business. The scope covers daily monitoring to identify and diagnose anomalies, risk evaluation for continued operation, tactical plans for safe operation, including difficult startup after unexpected trip, and internal inspection to verify the tube leakage. The leakage of MCHE tubes was detected as anomalies in daily surveillance, as shown by the continuous rise of methane composition and compressor suction pressure. Investigation was carried out to locate the leakage source. Risk assessment was conducted to evaluate the feasibility of continued operation, agree on the control measures, and rectification plans. Tactical strategies were established, including periodic liquid draining and venting, management of refrigerant composition and scrub column pressure. Tangguh also managed to handle a challenging situation with an unplanned trip during this condition. Special instructions for startup, including exchanger cooldown were prepared to safely restart the plant. Tangguh managed to keep operating safely with a tube leaked MCHE until the scheduled shutdown period, saving the business from losing around $50M. The key to this success was the tactical strategies during both start-up and normal operation. Investigation revealed that the leak was triggered by rapid cooldown in the previous startup, which caused thermal shock. To prevent the leaks, the cooldown should be controlled within the maximum rate. Internal inspection verified leaks in the feed gas circuit at various locations, and repairs were done. The paper summarizes that proper cooldown during startup is vital for preserving the integrity of the cryogenic heat exchanger. If leakage happens, systematic methods, including comprehensive surveillance analysis, solid risk assessment, and tactical strategies, should be applied to evaluate if continuing operation is reasonable. The paper uses Tangguh LNG's distinctive experience in managing tube-leaked cryogenic heat exchanger safely to develop systematic methods to prevent unexpected shutdown, which can be useful for other LNG operators. The paper also highlights the importance of proper cooldown during startup to preserve the cryogenic heat exchanger integrity.