The Dynamic Simulation And Optimization Study On Qingdao LNG Receiving Terminal

LNG receiving terminal is the terminal part of the industrial chain, one of whose important function is peak shaving. The natural gas is rich in the world. But its distribution is not balance. With the increasing consumption of natural gas, and the constant breakthroughs of low temperature materials and technology issues, the LNG receiving terminal is developing vigorously. The technology about LNG receiving terminal is immature in Chia. Using simulation technology to research is the development direction of our country.In this paper, the specific LNG vapor-liquid equilibrium and enthalpy was calculated in different equations by using simulation software, whose results were compared with experimental results. The concultion is that when LNG termianls were simulated, PR equation is the best one to calculate gas-liquid equilibrium and L-K-P equation is the best one to calculate enthalpy. This reach is based on Qingdao LNG terminal. Established the steady-state model of Qingdao LNG terminal by simulation software, then analyzed the impact of important parameters on the energy consumption of the whole station. After that the optimal operating parameters of each device were made out.In the actual production, the process parameters are constantly changing. The whole operation in different conditions can be described accurately using dynamic simulation. While using the steady-state simulation only can describe the station at one time. Therefore the dynamic simulation has more practical significance. By adding the boundary conditions, the size of the device and controllers, the dynamic model of Qingdao LNG terminal was created. Then simulate some special conditions and different accident conditions which included day peak shaving condition, unloading condition, tank overpressure condition, tank leaking conditions, pump starting and stopping condition, the minimum output and zero output condition. Steady the dynamic response of the process system duing these conditions. Through that, the reasonableness of the design parameters and control system were verified, and the reasonable suggestions for preventing accidents were put forward.Finally, the mixed process which mixed direct compression process and re-condensation process was proposed to hand BOG for Qingdao LNG terminal. The total power consumption increased by 6.8% using mixed process than using re-condensation process. However, in the minimum external output condition, using mixed process could avoid entering BOG to flare system, which would result in energy waste. What’s more, the entrance flow of recondenser would have small fluctuation. The LNG receving terminal process could run more stable and secure.