Reliability experiments in a cold box with nitrogen expansion liquefaction process running under sloshing conditions

A small-scale natural gas liquefaction equipment was built to study the liquefaction process of LNG-FPSO and the running reliability of liquefaction cold box under sloshing conditions at sea,which is the core equipment of the LNG-FPSO.The working performance of plate-fin heat exchanger,expander and separator and the operation effect of the whole process system under different working conditions were analyzed by the surge and roll experiments of the cold box.The main conclusions are summarized as follows: the cold box and the equipment run well under the experimental sloshing conditions and the pre-cooling nitrogen expansion liquefaction process is suited to the sea condition of the target gas field;the expander installed horizontally can reduce the effect of sloshing;the balance level of the gas-liquid two-phase separation process and the evaporation rate of liquid phase is increased by rolling;arranging the process equipment at the medial axis of the ship can reduce the amplitude of sloshing,as the roll is the most influential motion on the FPSO unit.