A Review of the Theory and Practice of Two-Phase Flow in Gas-Liquid Transmission Systems

Abstract

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Abstract The development of frictional pressure drop correlations for two phase flow is reviewed covering the contributions of Lockhart and Martinelli, Baker and Duckler. A new equation is presented for prediction of the multiplying factor () for frictional pressure drop in two phase flow which gives pressure drop in two phase flow which gives results very similar to those predicted by Duckler's case 2 method. 1.82 V (1-Rl) 1 x2= {1 + l} x +g --- ------- ----- ----Vg Rl (1-Rl)2.4 Rl 1.8 The effect of vertical rises and undulations on the overall pipeline pressure drop is discussed. A hypothesis is presented for the mechanism of massive liquid and gas surges which have sometimes been observed at reception terminals for two phase pipelines. pipelines Introduction Although there are now many two-phase gas-liquid transmission pipelines in use, some of which have been in operation for many years, and although a number of research projects have been initiated on the subject projects have been initiated on the subject over the last three decades, there still remains much to be learned about the various phenomena occurring in two phase flow. The phenomena occurring in two phase flow. The present paper reviews some of the criteria present paper reviews some of the criteria which are used in designing two phase transmission systems and contributes some new thoughts on the subject. THE DEVELOPMENT OF TWO-PHASE FRICTIONAL PRESSURE DROP CORRELATIONS PRESSURE DROP CORRELATIONS For many years since its development in. the late 1940's the Lockhart - Martinelli correlation represented the most accurate and most widely used method for the calculation of frictional pressure drop in two phase flow. This correlation was based on experiments using air and various liquids in pipes of 1" diameter and less. It expresses a multiplying factor (2) as a function of the ratio of the pressure drops for the liquid phase flowing on its own and the gas phase flowing on its own (X2). The product of this multiplying factor and the product of this multiplying factor and the pressure drop for one of the phases flowing pressure drop for one of the phases flowing on its own is then the friction pressure drop for two phase flow. Lockhart and Martinelli identified four types of flow which depend on whether the flow is viscous or turbulent for each of the phases. phases.