Temperature drop mechanism for gas regulator of natural gas pipeline

Under the conditions of given components, generation of gas hydrate is decided by pressure and temperature. Accurate prediction of gas temperature after throttling can provide technical foundation for prevention and control of hydrates. In this regard, the finite-element model for fluids within RMG530 gas regulator was established with the finite-element analysis software FLUENT, in order to simulate distribution and throttling process of fluids within the gas regulator under different conditions. Specifically, the model was used to simulate the variation of internal fluid velocity, pressure and temperature, and analyze the effect of inlet pressure, pressure drop and ambient temperature on the temperature drop when gas flows through gas regulator. In addition, testing data for temperature drop obtained in gas offtake stations were used to verify the accuracy of simulation results. Research results show that the gas flow field in the regulator is complicated, with intense turbulent flow characteristics. In the gas throttling process, flow velocity increases sharply while pressure and temperature plunge, providing the suitable condition for precipitation of hydrates. Ambient temperature, inlet pressure and pressure drop are key factors for the temperature drop in throttling. The temperature drop increases as pressure drop increases, and decreases as inlet pressure and initial temperature increase.