Experiment of sulfur carrying particles in gas-liquid two-phase flow and prediction method of critical velocity of sulfur carrying gas

Accurately revealing the patterns of sulfur deposition and the conditions for sulfur transportation is crucial for optimizing production allocation, tubing size, and determining the timing for sulfur management in sour gas wells. Therefore, a visuable inclined pipe with an inner diameter of 40 mm, and a length of 6 m was set up, with which inclined angle could be adjusted from 0° to 90°. Based on the similarity principles of Froude number and Reynolds number, experimental parameters were designed. Multiphase flow experiments of air-water-sulfur particles were conducted using sulfur particles collected from the field, simulating the process in which sulfur precipitates, forms particles, and was carried by the air-water two-phase mixture. The experiments revealed the critical gas velocity for the transportation of sulfur particles by the gas-liquid two-phase flow and the forms in which sulfur is carried. The effects of pipeline inclination angle, sulfur particle size, and sulfur deposition layer on the critical gas velocity for sulfur particles transportation were tested. The results show that the mechanism of sulfur transportation by the gas-liquid two-phase flow involves the gas flow carrying the liquid film, and the liquid film carrying the sulfur particles. The sulfur particles primarily move forward in a suspended or rolling manner. The critical gas velocity for sulfur transportation first increases and then decreases as the pipeline inclination angle increases, reaching a peak at an inclination angle of around 60°. The difference in critical gas flow velocity for sulfur particles transportation of large, medium, and small sizes is 5% to 10%. The developed prediction model for the critical gas velocity of sulfur particle transportation in gas-liquid two-phase flow demonstrates high prediction accuracy. This study provides theoretical reference and technical support for the efficient production and development of high-sulfur gas wells.