Retrofit design of a boil-off gas handling process in liquefied natural gas receiving terminals

Generation of Boil-off gas (BOG) in liquefied natural gas (LNG) receiving terminals considerably affects operating costs and the safety of the facility. For the above reasons, a proper BOG handling process is a major determinant in the design of a LNG receiving terminal. This study proposes the concept of a retrofit design for a BOG the handling process using a fundamental analysis. A base design was determined for a minimum send-out case in which the BOG handling becomes the most difficult. In the proposed design, the cryogenic energy of the LNG stream is used to cool other streams inside the process. It leads to a reduction in the operating costs of the compressors in the BOG handling process. Design variables of the retrofit design were optimized with non-linear programming to maximize profitability. Optimization results were compared with the base design to show the effect of the proposed design. The proposed design provides a 22.7% energy saving ratio and a 0.176 year payback period. -- Highlights: ► A retrofit design of the BOG handling process was proposed to maximize energy savings. ► The superstructure of the proposed design was developed based on a thermodynamic analysis. ► In the proposed design, the cryogenic energy of the LNG stream was utilized to directly cool down the BOG streams. ► The payback period of the proposed design is sufficiently short for investment in industry.