Dynamic simulation and optimization of the operation of boil-off gas compressors in a liquefied natural gas gasification plant

We propose an algorithm for the optimal operation schedule of the BOG compression process based on simulation of the dynamic behavior of an LNG tank. The algorithm uses an empirical boil-off rate model to predict the amount of BOG generation, and an MILP formulation to distribute the BOG compressors loads. Finally, a safety analysis is done using a dynamic simulator. To improve the accuracy, Aspen Dynamics with the Peng-Robinson equation of state is used in place of a simplified dynamic model used before. The dynamic simulation of the LNG tank pressure showed the results of oscillation within a safe pressure range while the BOG compressors were operated normally. The performance of the proposed algorithm was found to be superior to the algorithm used in routine processes as well as those from previous works in terms of safety and energy savings.