Effects of density and viscosity in vertical zero net liquid flow

An experimental study was conducted to investigate the effects of density a nd viscosity on zero net liquid flow (ZNLF) in vertical pipes. Predicting l iquid holdup under ZNLF conditions is necessary in several types of petrole um industry operations. These include predicting bottomhole pressures in pu mping oil wells and the design of compact gas-liquid cylindrical cyclone (G LCC(C))(1) separators. Models are proposed to predict flow pattern transiti ons under ZNLF conditions and comparisons are made with commonly used verti cal flow pattern transition criteria. Data was collected using a 3-in.-diam , 14-ft-section of transparent vertical pipe. Several different fluids, of differing density and viscosity, were utilized with air flowing at approxim ately 25 psig. Results are presented showing the liquid holdup and the flow distribution coefficient (C-o) as a function of density, viscosity, and su perficial gas velocity. [S0195-0738(00)00402-7].