Research on steady state system of closed loop natural gas flow facility

Flowmeters are key instruments for natural gas measurement, and the measurement accuracy directly affects the fairness and impartiality of trade. Closed loop technique does not rely on upstream and downstream pipeline conditions, whose calibration pressure can be switched flexibly, has become the trend of development in flow measurement field. So, Jinan branch of the National Petroleum and Natural Gas Flow Measurement Station plan to build the closed loop facility. The equipment lectotype and design specifications of steady-state system of natural gas closed loop based on the construction scale and configuration of Jinan branch station are discussed, the target uncertainty is studied, and the steady-state system simulation model is built. According to the pressure and temperature simulation of steady-state system, when the calibration pressure is 5.5 MPa, during increasing of the calibration flow rate from 13 m 3 /h to 8000 m 3 /h, the maximum pressure deviation is 0.4 %, and the maximum pressure deviation is 0.1 % at the pressure of 5.5 MPa and flow rate of 1600m 3 /h during the calibration. When the calibration pressure is 5.5 MPa, during the process of reaching a flow rate of 1600 m 3 /h in the closed loop, the temperature tended to stabilize within 16 minutes, and the maximum temperature difference is 0.1 °C within 15 minutes in the measurement stage.