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

Functionalized ceramics for biomedical, biotechnological and environmental applications

Bioethanol production from renewable sources to be used in transportation is now an increasing demand worldwide due to continuous depletion of fossil fuels, economic and political crises, and growing concern on environmental safety. Mainly, three types of raw materials, that is, sugar juice, starchy crops, and lignocellulosic materials, are being used for this purpose. This paper will investigate ethanol production from free sugar containing juices obtained from some energy crops such as sugarcane, sugar beet, and sweet sorghum that are the most attractive choice because of their cost-effectiveness and feasibility to use. Three types of fermentation process (batch, fed-batch, and continuous) are employed in ethanol production from these sugar juices. The most common microorganism used in fermentation from its history is the yeast, especially, Saccharomyces cerevisiae, though the bacterial species Zymomonas mobilis is also potentially used nowadays for this purpose. A number of factors related to the fermentation greatly influences the process and their optimization is the key point for efficient ethanol production from these feedstocks.

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Bioethanol Production from Fermentable Sugar Juice

Immobilized cells : a review of recent literature

Trickle-bed reactors: state of art and perspectives

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.

Susumu Fukushima

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.

Continuous alcohol production from starchy materials with a novel immobilized cell/enzyme bioreactor