Optimization Analysis And Dynamic Simulation Of LNG Process

With the gradual change of world energy structure,the consumption of natural gas has increased dramatically and ranks second in the world energy structure.China's LNG technology is also in the rapid development stage,but it is not compatible with the development of China's liquefied natural gas(LNG).There is a gap between the technology level of LNG in our country and the developed countries,so it is urgent to develop the technology of LNG in China.Based on the steady simulation of liquefied natural gas(LNG)process,optimization analysis and dynamic simulation are carried out.Firstly,the development of natural gas liquefaction technology at home and abroad is discussed.The status quo of steady state and dynamic simulation of natural gas liquefaction process is introduced,and the necessity of flow optimization analysis and dynamic simulation of LNG is clarified.The main natural gas liquefaction processes are introduced,and each liquefaction processes are compared,and the principles of the selection of two functional natural gas liquefaction processes are clarified.Secondly,the thermophysical properties of natural gas and mixed refrigerants are described,including basic thermodynamic parameters,thermodynamic calculation methods,and phase equilibrium and entropy calculation models.In this paper,PR equation is used as the calculation model of the mixture phase equilibrium,and the LKP equation is used as the entropy calculation model.Finally,a steady-state thermodynamic model of the process equipment is established.Thirdly,based on the steady-state simulation of natural gas liquefaction process,optimization analysis is performed.Aspen Hysys software is used to minimize the power consumption of the system as the objective function,to optimize the distribution ratio of the mixed refrigerant set in the natural gas liquefaction process and the operating pressure of the system,and ultimately the consumption of the system is reduced by 14.18% and the liquefaction rate is increased by 7.936%.Combined with the main optimization parameters and the cold and hot fluid composite integration curve of the cold box,the theoretical analysis is carried out.Based on the optimized solution,under the non-design conditions,the impact of changes in natural gas temperature and pressure on the cold box pinch point is analyzed.Combined with the change of the water temperature in summer,the effect of the water temperature of the water cooler on the energy consumption and liquefaction rate of the mixed refrigerant system is analyzed.Finally,a dynamic simulation of the liquefaction process of natural gas is carried out,a dynamic model of the process equipment is established,and the dynamic response of changes in natural gas flow rate,composition,and temperature to the process is analyzed.