In addition to above mentioned, stratified flow happened at low liquid velocity (below0.15m/s). Under forced conditions the HTLB always operated in the bubble flow regimen at two liquid flow rates (0.35 and 0.47m/s) that were examined. Also ,the bubble regime was observe data low liquid flow rate, i.e.,0.24m/s when high gas flow rates (morethan0.03m/s)
were injected in to the HTLB. Determination of probable flow patterns in the horizontal reactor section was estimated based on high oxygen mass transfer coefficients results (L/D = 36.6 and S = 0.61) and are summarized in Table 2. As is obvious, the best mass transfer (0.016 S−1) was obtained in bubble flow regime. The flow pattern should be investigated complementary in further studies for design purposes to avoid conditions which can cause operational problems.