Transient Modeling and Simulation of Coal Bed Methane Transmission Pipeline

Abstract

The coal bed methane is methane mainly and it has less heavier than conventional natural gas, thus coal bed methane has a slightly higher value than natural gas. Developing and utilization of coal bed methane is an important way to release contraction between supply and demand of natural gas in China. The pipeline is principle way of transporting the coal bed methane from sources to end-users. In view of the characteristics of coal bed methane, equation of state BW RS is used to calculate the thermodynamic parameters. Then based on continuity equation, momentum equation, characteristic equations of non-pipe elements and flow quantity balance equation, the transient simulation mathematic model of coal bed methane transmission pipeline is built. Considering the slow transient characteristic of gas flowing, the implicit central difference method is used to transform partial differential equations of the model into finite difference equations. Aiming at non- linear characteristics of differential equations, Newton iteration format is constructed and the model's solution method is discussed. Finally, MS Visual C++ is utilized to develop a simulation software name coal bed methane pipeline emulation system, and the practical applications are carried out. The results show the mathematic model built in the paper and its solving method are both feasible. They provide technical supports for reasonable design and operation of the coal bed methane pipelines.