Chemical Engineering Use of Catalyzed Sulfite Oxidation Kinetics for the Determination of Mass Transfer Characteristics of Gas-Liquid Contactors

Trickle-bed reactors: state of art and perspectives

Catalyst wetting efficiency in trickle-bed reactors at high pressure

Pressure drop and liquid holdup in high pressure trickle-bed reactors

A two-fluid hydrodynamic model for the transition between trickle and pulse flow in a cocurrent gas–liquid packed-bed reactor

Liquid holdup and interfacial areas were measured in packed columns with cocurrent downward flow. An empirical equation of liquid holdup Φt is presented in terms of Reynolds numbers of gas Reg(=dsGg/μg) and liquid Rel, surface shape factor of packing φ, void fraction e and ratio of packing to column diameter dp/T, where the ratio is smaller than 0.13. This equation is different for the dispersed bubble flow and other flow regions. The empirical equation of interfacial area ap in the respective flow regions varies as follows: apdp/(1-Φl/e)=ωΦ-mRenlReqg(dp/T)-twhere ω=7.5×10-5, m=Q.2, n=Q.15, q=2/3, t=2.5 for spray flow; ω=2.2×10-4, m=0.3, n=2/3, q=0.2, t=2.5 for pulse flow; ω=3.9×10-3, m=0.1, n=0.4, q=p. t=2 for trickle flow; ω=2.8×10-7, m=0.9, n=1.8, q=0, t=3.3 for dispersed bubble flow. The equation of the boundary in the respective flow regions was found by equating the two of them. The predicted boundaries are in excellent agreement with the literature data given from the analysis of liquid pulse frequencies. The predictions for interfacial areas also agree well with the literature data.

Interfacial area and boundary of hydrodynamic flow region in packed column with cocurrent downward flow.

Liquid-phase volumetric coefficients and Peclet numbers in liquid mixing were measured in packed columns with cocurrent downwardflow. The empirical equations of liquid-phase volumetric coefficient are distinctly different in spray, pulse and dispersed bubble flow regions. The boundaries for the respective flow regions, obtained by combining two of these equations of volumetric coefficient, are in good agreement with the boundaries which have previously been given from the equations of interfacial area in the same fashion. The foam flow region, which gives the maximumvalue of liquid-phase mass-transfer coefficient, was found at higher gas Reynolds number in comparison with pulse and dispersed bubble flow regions. Taking the ratio of packing to column diameter dp/T and surface shape factor of packing  into consideration, the empirical equation of mass-transfer coefficient is presented in respective flow regions as

Liquid-phase volumetric and mass-transfer coefficient, and boundary of hydrodynamic flow region in packed column with cocurrent downward flow.

Liquid holdup and interfacial area were measured in columns packed with 1/2 and 1 in. ceramic spheres for upward cocurrent-flow mode, where the ratio of packing to column diameter, dp/dT, is 0.085, 0.128 and 0.169. The empirical equations of liquid holdup Φl for void fraction e are given as follows: Φl/e=κRehiRe-jgwhere κ=1.8, h=0.03, j=0.28 for Rel 695Reg-0.5. The empirical equations for interfacial area ap are also presented as follows: apdp/(1-Φl/e)=αRemlReno(dp/dT)-twhere the values of α, m, n and t are 16, 0.05, -0.4 and 0 for bubble (1), 2.2, 0.05, -0.2 and 0.5 for churn, 0.24. 0.27, 0 and 0.7 for pseudospray, 0.26, 2/3, -1/4 and 0.4 for bubble (11), 1.0×10-2, 2/3, 0 and 1.4 for pseudopulse and 2.9×10-4, 2/3, 0.2 and 2.5 for pulse flow, respectively. The equation for respective hydrodynamic flow boundary was found by combining two of these. The predicted mass-transfer coefficients for liquid phase given by the simple equation for downward flow mode agree with the literature data in a wide range of gas and liquid flow rates.

Gas-liquid mass transfer and hydrody-namic flow region in packed columns with cocurrent upward flow

Boundary of hydrodynamic flow region and gas-phase mass-transfer coefficient in packed column with cocurrent downward flow.

Interfacial areas and liquid-phase volumetric mass-transfer coefficients were measured from chemical absorption of oxygen into sulfite solution and from physical absorption of carbon dioxide into water, respectively, in the cases of one, two, three and seven strings of touching spheres, and in irrigated columns packed with spheres, Raschig rings and Berl saddles. The columns having seven strings of touching spheres used both open and closed configurations of spheres. When the number of spheres per string is larger than 10 and the number of strings m is 3 and 7, the empirical equation of interfacial area at for sphere diameter dp is given in terms of liquid Reynolds number Ret(=4ρQl/mπdpμl) and the number of contact points of spheres per sphere q as follows: atdp=4.8q-1.1Ret(0.27q0.25)tThe equation obtained by replacing at by ap/(1-e) and Ret by Rep in the above equation is applicable to illustrate the data in irrigated columns packed with spheres, (1-e) in solid fraction, with an accuracy of ±20%. Suppose q=4.2 for Raschig rings and q=2.8 for Berl saddles, the predicted values agree with the experimental data. The Sherwood numbers are presented by the same relation for the cases of one, two, three and seven strings, where the number of touching spheres is larger than 10, as follows: Sht=k*ltdp/DA=7.1Re1/3tSc1/2The equation obtained by substituting k*lt by k*lp, 7.1 by 27φ(1-e) and Ret by Rep represents the data for columns with a packing of surface shape factor φ.

Katsuhiko Kusaka

Papers

Interfacial area and boundary of hydrodynamic flow region in packed column with cocurrent downward flow.

Liquid-phase volumetric and mass-transfer coefficient, and boundary of hydrodynamic flow region in packed column with cocurrent downward flow.

Gas-liquid mass transfer and hydrody-namic flow region in packed columns with cocurrent upward flow

Boundary of hydrodynamic flow region and gas-phase mass-transfer coefficient in packed column with cocurrent downward flow.

Mass transfer on multi-strings of touching spheres.