Study on Two-phase Flow in Tray Downcomer - Backmixing and Choking Tests

摘要

To decide the upper limit of tray downcomer, characteristics of V-L two-phase flow in theindustrial scale downcomer are studied in the paper. The liquid backmixing and circular flow indowncomer are tested with the fluoro-tracer agent and the hot water tracer technique in a 1900mm and a1200mm diameter simulator ,respectively. The critical chocking liquid-loading intensity of downcomer isdetermined in a rectangle simulator, of which the length is 800mm and the width is 600mm. The resultsshows severe liquid backmixing in the downcomer with backmixing number are higher than 0.1 and thedimensionless variance are about 0.5. The liquid circular flow is observed in the middle of downcomer. Itis also shown that the value of critical chocking liquid-loading intensity of downcomer is less than thevalue predicted by previous empirical correlation. The results obtained in the large-scale experimentalapparatus should be more reliable than that in small-scale equipment. It can provide basic data forengineering design.