Optimization of the design of the initial transportation station in LNG receiving terminal project

In China's LNG terminal project, there are many differences in the process flow, design pressure, material selection, etc. for initial transportation station. The closing condition of shut-off valve in downstream transportation pipeline of LNG receiving terminal was simulated by SPS, and compared to the overpressure protection design of pipeline with low design pressure, the effectiveness and limitation of the built initial station were pointed out. The results show that: (1) when the design pressure demarcation point is at the outgoing ESD valve of the receiving terminal, i.e. the design pressure of the initial station is consistent with that of the transportation pipeline, the closing of the outgoing ESD valve by transportation PAHH interlocking of the receiving terminal may not be able to insure the intrinsic safety of the initial station, so the design pressure of the initial station should be greater than the maximum pressure under the closing condition, or equal to the design pressure of the transportation system of the receiving terminal, (2) when the shut-off valve is closed, the downstream pipeline of the initial station is able to get rid of the overpressure in operation by reasonably setting the interval between the receiving terminal and the valve chamber, as well as the receiving terminal's transportation PAHH interlock, and(3) in the optimized process flow of the initial station, the pig launcher should be provided with nitrogen charging port, and the safety valve and sewage outlet should be cancelled. The manual venting in the station shall rely on the flare system of the receiving terminal, instead of being used for the venting of the downstream pipeline. For a LNG receiving terminal project, the research results may be used to guide the design of overpressure protection of the transportation pipeline and the process design of the initial station.