LNG Transport Pipeline Pre-cooling Process Simulation And Analysis

Before large LNG terminal unloading,there will be two steps to pre-cooling the pipeline and tank. First step is BOG pre-cooling process,BOG will pre-cooled the pipeline to-120℃,and then LNG pre-cooled the pipeline to-150℃.At the same time 4” spraying pipeline will spary LNG to the tank and let the tank achieve precooling requirements.When the last two steps complete,LNG ship will pull the LNG to the tank and store LNG in the tank. My article’s target is rely on the two pre-cooling steps,establish mathematical model,use MATLAB software to simulate the process.And hope the changing trend from the simulate result can give some advises to the LNG terminal pre-cooling process.LNG terminal consist of 40’’ and 36’’ stainless steel pipe, use PIR parceling the pipeline as cold insulation materials, thickness of it is about 178 mm.40’’ and 36’’ length are 656.6 m and 104.6 m. Fluids from 40’’ pipe inlet began flow to drop section, horizontal section, elbow, climbing section, into the tank, and at the same time, fluids can also through 4’’ spray pipe of 36’’ pipe’s branch into the tank.BOG pre-cooling process: establish one-dimensional flow heat transfer model to simulate pre-cooling process. Through cooling process, changing trend of pipeline temperature, BOG gas temperature and inlet BOG gas mass-flow has been analysed. At the same time, different factor have different influence to the pre-cooling process. From the result we obtain, there has some advice to the operation of LNG terminal.LNG pre-cooling process: considering flow in the vertical tube and horizontal tube, we establish two fluids flow heat transfer model, choose stratified flow and LNG single phase to simulate pre-cooling process. Through cooling process, changing trend of pipeline temperature, LNG heigh in the tube and process of tube full of LNG has been analyses. At the same time, different factor have different influence to the pre-cooling process.Through the compare of actual pre-cooling data and simulate pre-cooling data, we analysis the difference of the data and the causes of producing the differences for simulation further research and lay the foundation of the optimization.From the result we obtain, we compete the there has some advice to the operation of LNG terminal.