The characterizations of various flow regimes were investigated in the HTLB by changing the gas and liquid flow rates.The observed flow patterns are depicted in Fig. 9. As is obvious ,the bubbly (homogeneous) flow regime was characterized by almost uniform sized bubbles with equal radial distribution at liquid flow rates more than0.2m/s. The heterogeneous flow (slugandwavy) were determined by large bubbles moving at high gas velocities (morethan0.03m/s)
in thepresenceofsmallbubbles.Moreover,theplugflowoccurred when gas flow rate did not exceed 0.03m /sand the value of liquid velocity was between 0.1 and 0.4m/s.