TABLE OF CONTENTS Natural gas continues to play a great role as a worldwide energy supply. In fact, major projects are being planned to move massive amounts of high-pressure sales gas from processing plants to distribution systems and large industrial users through large-diameter buried pipelines. These pipelines utilize a series of compressor stations along the pipeline to move the gas over long distances. In addition, gas coolers are used on the discharge side of the compressor stations to maintain a specified temperature of the compressed gas for pipeline downstream pressure drop reduction and to protect gas pipeline internal and external coating against deterioration due to high temperatures. This chapter covers all the important concepts of sales gas transmission from a fundamental perspective.
Optimum design of a gas transmission pipeline requires accurate methods for predicting pressure drop for a given flow rate or predicting flow rate for a specified pressure drop in conjunction with installed compression power and energy requirements, e.g., fuel gas, as part of a technical and economic evaluation. In other words, there is a need for practical methods to relate the flow of gas through a pipeline to the properties of both the pipeline and gas and to the operating conditions, such as pressure and temperature. Isothermal steady-state pressure drop or flow rate calculation methods for single-phase dry gas pipelines are the most widely used and the most basic relationships in the engineering of gas delivery systems (Beggs, 1984; Smith, 1990, Aziz and Ouyang, 1995).
