Control Structure Design and Dynamic Simulation of Mixed Fluid Cascade Natural Gas Liquefaction Process

Mixed fluid cascade natural gas liquefaction process control system is designed and analyzed in this study. The specific energy consumption (SEC) of this process is 0.2647 kWh/kg LNG. After steady state simulation and sizing the process components, a control structure is designed to control the whole process. In addition, dynamic simulation is carried out and performance of the controllers is investigated. By dynamic simulation, specific energy consumption is reduced to 0.2574 kWh/kg LNG, which means the designed control structure can stably and accurately control the process. To validate the performance and stability of the control structure, changes in the flow rate and temperature of the feed gas are inflicted as a disturbance to the process.