The hydrodynamics of trickling flow in packed beds. Part II: Experimental observations

AICHE Journal - Tập 32 Số 3 - Trang 369-380 - 1986
Janez Levec1, A. Eduardo Sáez2, Ruben G. Carbonell2
1Department of Chemistry and Chemical Technology, Edvard Kardelj University, 61000 Ljubljana Yugoslavia
2Department of Chemical Engineering , North Carolina State University , Raleigh , NC , 27695-7905

Tóm tắt

AbstractThe liquid holdup and the pressure drop for two‐phase trickling flow in a packed bed were measured experimentally. Different values of those parameters were obtained as the liquid flow rate was increased and then decreased, indicating a multiplicity in hydrodynamic states. This behavior was observed even when the gas flow rate was zero in the bed. It was determined that the hysteresis exhibited by the process is due to imperfect wetting of the packing and to the difference between advancing and receding contact angles at the gas‐liquid‐solid contact lines. The reduced wetting conditions are also the cause of the increase in liquid holdup observed when the surface tension of the liquid is decreased. In this case, the amount of liquid retained in the bed is controlled by the extension of the wetted regions due to the more favorable contact angles as the surface tension decreases. The transition from the trickling to the pulsing flow regime was also dependent on the history of the process.A new correlation for predicting liquid holdups and pressure drops for trickling flow in packed beds is proposed for the decreasing liquid flow rate operating mode. This correlation is based on the experimental determination of the liquid phase relative permeability as a function of the the liquid phase reduced saturation and the determination of the gas phase relative permeability as a function of the gas phase saturation and the gas phase Reynolds number. The new data are analyzed in the light of the theory developed in the first part of this paper.

Từ khóa


Tài liệu tham khảo

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AICHE Journal

Tập 32 Số 3

369-380

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