Transient Response Analysis of High-Pressure Steam Distribution Systems

The mathematical models for unsteady pipeline networks play an important role in the design of petrochemical plants, hydraulic power machines, long distance pipelines, etc., and have become popular in these industry due to the development of high-speed computers. An iterative implicit method is proposed in this research to solve the continuity, momentum and energy equations in an unsteady, non-isothermal and compressible steam pipeline. The Newton-Raphson method is used as an algorithm to solve the finite-difference equations of a steam pipeline. The modified Hardy-Cross method is applied to the calculation of network system. A set of nonlinear equations have to be solved simultaneously in traditional fully implicit methods, which are inappropriate to be used in a complex network system. Hence, a sequentially iterative fully implicit method has been propounded to deal with the nonlinear equations. Several cases are completed by the presented iterative fully implicit method and the simulation results are compared with existing characteristics methods. For network systems, the present work proposes a method which combines the iterative fully implicit method that has been used in a single pipeline with the modified Hardy-Cross method and several examples are completed. The transient analysis of a network system is more practical than a single pipeline in a large refinery, therefore, the present study gives a simple method which can quickly have a deep look into the steam transient response.