Publications

The goal of this study is to enhance energy efficiency and reduce emissions in LNG plants by introducing an innovative defrosting method. This research focuses on the application of Boil-Off Gas (BOG) as a defrost gas at PT Donggi-Senoro LNG (DSLNG), a significant departure from the conventional practice of using feed gas.

In standard LNG operations, defrosting is achieved by using feed gas heated to 60°C. However, this method often leads to energy inefficiency, especially during periods of low demand, such as plant maintenance shutdowns, when the excess BOG is typically flared. Addressing this inefficiency, the DSLNG approach repurposes BOG for defrosting. The process entails compressing and heating the BOG to the necessary temperature for effective moisture removal from equipment post-overhaul, thereby preventing hydrate formation during the LNG conversion process. This DSLNG BOG utilization for defrosting is a pioneering method in Indonesia’s LNG plant.

This innovative method was thoroughly tested and implemented during maintenance shutdowns at DSLNG. The results: the use of BOG as defrost gas consistently reduced the moisture content in equipment to below 10 ppm, surpassing the safety requirements for plant restarts. Importantly, this approach not only conserved energy but also significantly reduced gas flaring, contributing to a decrease in emissions. In conventional practice, feed gas from the trunkline is used for defrost gas, which is subsequently flared after the defrosting process is completed. Meanwhile, DSLNG also has excess BOG during shutdowns, which eventually flared. By utilizing BOG as defrost gas, not only the plant start-up process is more efficient, but furthermore, the number of flaring was effectively reduced.

This case study represents a change in basic assumptions in LNG plant operations. The successful implementation of BOG as a defrost gas at DSLNG demonstrates a practical, efficient, and environmentally responsible approach to a common challenge in the industry. The findings from this study set a new benchmark in LNG operations, displaying a method that optimizes resource use, enhances operational efficiency, and supports environmental sustainability. The insights gained have the potential to influence future practices and inspire similar innovations across the energy industry. By repurposing BOG that would otherwise be flared, this method not only conserves energy and reduces environmental impact but also sets a precedent for future practices and inspires innovations in the LNG industry. A Similar LNG plant could take this opportunity to enhance its operation efficiency and carbon emission reduction. This also inspires innovations that show plant production or efficiency improvement opportunities could go hand-in-hand with decarbonization efforts.