Horizontal annular‐mist flow of natural gas‐water mixtures

Abstract

AbstractA survey of the literature having possible application to the annular‐mist flow problem is presented.The horizontal annular‐mist flow of natural gaswater mixtures in one‐ and two‐in. diameter, schedule 40 aluminum pipes was investigated. The input gasliquid volume ratios were varied between 10 and 100,000 for superficial gas velocities between 25 and 300 ft./sec. The mid‐point pressure was held constant at 120 p.s.i.g. Some data for variable mid‐point pressure and constant liquid and gas rates are also presented to show the effect of gas density.The pressure drop data for constant mid‐point density are presented as a function of the superficial velocities of the two phases. The same data are also presented in terms of the ratio of the two‐phase pressure gradient to the single‐phase gas pressure gradient. Possible mechanisms of the flow in the annular‐mist region are discussed and the possibility of microscopic changes in flow pattern is indicated. A large effect of a small quantity of water was observed over the gas rates investigated. Higher water rates had much greater effect at low gas rates than at high gas rates. It is proposed that the high pressure drop is caused by the formation of a liquid film on the inside wall of the pipe. The thickness of this film decreases as the gas rate is increased until it reaches some minimum value. The breakup of this film was not indicated over the range of gas rates investigated.The data are also interpreted in terms of a friction factor and Reynolds number based on the mixture properties.The data are compared with the correlations of Lockhart and Martinelli, and Chenoweth and Martin.