(209c) Simulation of Large Scale Natural Gas Transmission Networks with Heat Transfer Considerations

A fast and efficient algorithm was proposed for the simulation of large natural gas transmission networks. The model considered the thermal effects and variations of physical properties of gas upon pressure drop in the pipelines or pressure rise in the compressors. The initial model was well defined for gas networks including gas sources and sinks. Gas pipelines and compressors were considered as the links between the nodes at which the gas pressure might drop or rise. Using mass balance for each node a set of nonlinear equations was formulated. The system of equations was further solved by local linearization of the nonlinear system. The algorithm was tested for a benchmark problem. Since the pressure changes in the compressors and pipelines were typically of near quadratic order, even with a tight cumulative absolute error of 1e-3, the algorithm could converge within 15-40 iterations, for the base case problem. Sensitivity of the algorithm to the initial guess was tested for the benchmark problem with and without heat transfer consideration. With having heat transfer through the pipelines still the algorithm could converge within 15 iterations.