Dynamic Flow Behavior Analysis of Wet Gas Pipelines

Abstract

Abstract Corroded wet gas pipelines could be a result of inadequate flow and cause stagnant water along the pipeline. Evaluation of flow behavior in a pipeline is necessary to ensure the integrity of the pipeline is well maintained. This paper presents an evaluation through dynamic flow simulation analysis of the optimum flow range for avoiding low velocity and stagnant fluid in a wet-gas pipeline network. The determining factors include pressure drop, liquid and water holdup, as well as gas and liquid velocities. To minimize the potential for corrosion due to stagnant water in contact with the pipe wall, the gas flow rate corresponding to a range of water holdup values along the pipeline, as well as the range of gas velocities, were evaluated. The variation in liquid velocity at these conditions was evaluated to confirm the stability of the flow. Additionally, the gas flow rates corresponding to the minimum holdup in the pipeline and overall pressure drop were obtained. Due to the dynamic nature of the flow, analysis required determination of maximum, minimum and average values associated with the gas flow rates. The impact of the elevation profile, various pipe sizes (4, 6, 8, and inches), and different gas properties were also considered for this analysis. Analysis indicated that operating at a minimum pressure drop in the pipeline could increase the potential for corrosion due to increase in water holdup. Additionally, the analysis suggested that the minimum flow rate for operation of the pipelines should be based on flow stability and water wetting the wall, and on acceptable pressure drop, but not by liquid or water holdup/accumulation. Dynamic flow behavior analysis in this paper shows flow stability corresponds to the gas flow rates for different pipeline sizes. Corrosion in pipelines may therefore be due to low flow or stagnant liquid along the pipeline, which is an important factor for assessing pipeline integrity.