Simulation and Economic Benefit Analysis of Carburetor Combined Transport in Winter at a Liquefied Natural Gas Receiving Station

In the winter, a certain LNG receiving terminal operates exclusively with the submerged combustion vaporizer (SCV). However, due to the high operational costs associated with the SCV, a new combined operation scheme utilizing both the SCV and the open rack vaporizer (ORV) has been proposed. First, models for the SCV and ORV gasification units were developed in Aspen HYSYS and validated using actual operational parameters. Next, the relationship between the seawater inlet–outlet temperature difference and the minimum seawater flow rate for the ORV was determined, and an optimized seawater pump operation strategy, considering LNG export volumes, was formulated. Additionally, the relationship between the SCV fuel gas flow rate and LNG export volume was analyzed, and a comparison was made between the operating costs of SCV running independently and the combined SCV-ORV operation under winter conditions. The results of the combined operation experiments indicated that at a seawater inlet–outlet temperature difference of 3 °C, the joint operation mode could save costs by 70–77%; at 2.5 °C difference, it saves 60–67%; at 2 °C difference, it saves 45–50%; at 1.5 °C difference, it saves 35–38%; and at 1 °C difference, it saves 20–23%. This approach achieves optimized economic performance for LNG terminal operations.