The Simulation Of Gas Flow Dynamics In Pipeline Networks

Abstract: "A network formulation is introduced for the modeling and numerical simulation of complex gas transmission systems like a multi- cylinder internal combustion engine. Several simulation levels are discussed which result in different network representations of a specific system. Basic elements of a network are chambers of finite volume, straight pipes and connections like valves or nozzles. The pipe flow is modeled by the unsteady, one-dimensional Euler equations of gas dynamics. Semi-empirical approaches for the chambers and the connections yield differential-algebraic equations (DAEs) in time. The numerical solution is based on a TVD scheme for the pipe equations and a predictor-corrector method for the DAE-system. Simulation results for an internal combustion engine demonstrate the practical interest of the new approach."

Computer simulation is the key to comprehending and controlling the full-scale industrial plant used in the chemical, oil, gas and electrical power industries. Simulation of Industrial Processes for Control Engineers shows how to use the laws of physics and chemistry to produce the equations to simulate dynamically all the most important unit operations found in process and power plant.The book explains how to model chemical reactors, nuclear reactors, distillation columns, boilers, deaerators, refrigeration vessels, storage vessels for liquids and gases, liquid and gas flow through pipes and pipe networks, liquid and gas flow through installed control valves, control valve dynamics (including nonlinear effects such as static friction), oil and gas pipelines, heat exchangers, steam and gas turbines, compressors and pumps, as well as process controllers (including three methods of integral desaturation). The phenomenon of markedly different time responses ("stiffness") is considered and various ways are presented to get around the potential problem of slow execution time. The book demonstrates how linearization may be used to give a diverse check on the correctness of the as-programmed model and explains how formal techniques of model validation may be used to produce a quantitative check on the simulation model's overall validity.The material is based on many years' experience of modelling and simulation in the chemical and power industries, supplemented in recent years by university teaching at the undergraduate and postgraduate level. Several important new results are presented. The depth is sufficient to allow real industrial problems to be solved, thus making the book attractive to engineers working in industry. But the book's step-by-step approach makes the text appropriate also for post-graduate students of control engineering and for undergraduate students in electrical, mechanical and chemical engineering who are studying process control in their second year or later.

This book is concerned with the steady state hydraulics of natural gas and other compressible fluids being transported through pipelines. Our main approach is to determine the flow rate possible and compressor station horsepower required within the limitations of pipe strength, based on the pipe materials and grade. It addresses the scenarios where one or more compressors may be required depending on the gas flow rate and if discharge cooling is needed to limit the gas temperatures. The book is the result of over 38 years of the authors' experience on pipelines in North and South America while working for major energy companies such as ARCO, El Paso Energy, etc.

When pipelines are used to transport gas through long distances, compression stations are coupled to the system in order to regain energy that is lost during fluid flow. In order for the compression stations to work, they consume part of the fluid being transported, making of it a source of fuel. An elegant optimization problem arises from the determination of network characteristics that will minimize fuel consumption at the compression stations. This minimization problem is given by highly non-linear objective function and constraints. Furthermore, an important part of the determination of compression performance is based on the calculation of efficiency in compressors. While some authors have assumed this efficiency to be constant, others have expanded the efficiency calculations by using polynomial curves. This study introduces three methods that allow for the simulation and optimization of natural gas transportation networks: first, it is demonstrated how fuel consumption can be accounted for in a system; second, it is introduced a method for the calculation of compressor efficiency; third, a domain-constrained search procedure is implemented in order to determine how compression stations should be adjusted in order to achieve minimum fuel consumption in a given transportation network. In order to account for possible convergence difficulties, all the procedures implemented in the three methods rely on the use of the Linear-Pressure Analog model, a technique that allows for the linearization of the gas flow equations. This is concluded to be one of the main reasons why system efficiency and minimum fuel consumption can be estimated, given the fact that the Linear Analog procedure facilitates convergence and effectiveness of the methods implemented in a reliable and effective manner.