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Abu Bakar Salleh - One of the best experts on this subject based on the ideXlab platform.
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Scale-up synthesis of lipase-catalyzed palm esters in stirred-tank reactor.
Bioresource Technology, 2008Co-Authors: P.s. Keng, Arbakariya B Ariff, Mahiran Basri, M. B. Abdul Rahman, R. Abdul Rahman, Abu Bakar SallehAbstract:Abstract Lipase-catalyzed production of palm esters by alcoholysis of palm oil with oleyl alcohol in n-hexane was performed in 2 L stirred-tank reactor (STR). Investigation on the performance of reactor operation was carried out in batch mode STR with Single Impeller mounted on the centrally located shaft. Rushton turbine (RT) Impellers provide the highest reaction yield (95.8%) at lower agitation speed as compared to AL-hydrofoil (AL-H) and 2-bladed elephant ear (EE) Impellers. Homogenous enzyme particles suspension was obtained at 250 rpm by using RT Impeller. At higher Impeller speed, the shear effect on the enzyme particles caused by agitation has decreased the reaction performance. Palm esters reaction mixture in STR follows Newtons’ law due to the linear relation between the shear stress (τ) and shear rate (dυ/dy). High stability of Lipozyme RM IM was observed as shown by its ability to be repeatedly used to give high percentage yield (79%) of palm esters even after 15 cycles of reaction. The process was successfully scale-up to 75 L STR (50 L working volume) based on a constant Impeller tip speed approach, which gave the yield of 97.2% after 5 h reaction time.
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Process improvement in the production of oleyl oleate, a liquid wax ester in stirred tank reactor
Journal of Biotechnology, 2008Co-Authors: Mahiran Basri, Arbakariya B Ariff, Abu Bakar Salleh, M. B. Abdul Rahman, Salina Mat Radzi, Rosfarizan Mohamad, Raja Noor Zaliha Raja Abdul RahmanAbstract:Lipase-catalyzed production of oleyl oleate, a liquid wax ester by esterification of oleic acid with oleyl alcohol was performed in 2 L stirred tank reactor (STR). Process improvement study in reactor operation was carried out in batch mode STR with Single Impeller mounted on the centrally located shaft. Rushton turbine Impeller showed better performance in degree of mixing, as compared to AL Hydrofoil Impeller, whereby a high Reynolds number of >104 was achieved at 400 rpm, which exhibit a turbulent flow pattern [1]. Homogenous enzyme particles suspension was obtained at lower Impeller speed (≤200 rpm) by using AL Hydrofoil Impeller. However, there was significant effect to the mixing improvement on the enzyme particles distribution by using 2 Impellers system with spacing of 30 mm even at lower agitation speed (≤200 rpm). High stability of Novozym 435 was observed even in the presence of shear forces on the enzyme particles due to the mechanical agitation speed. Wax ester reaction mixture in STR follows Newtons’ law due to the linear relation between the shear stress (τ) and shear rate (dυ/dy) [2]. The process was successfully carried out to the highest amount of wax ester that can be produced in 2 L STR whereby, the production and productivity of oleyl oleate were improved from 295.39 g/L/h to 705.76 g/L/h and 310.16 g/h to 952.78 g/h, respectively.
A. Lübbert - One of the best experts on this subject based on the ideXlab platform.
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Catchment area of the cavities behind a rushton turbine in gassed-stirred-tank reactors
Chemical Engineering Science, 1997Co-Authors: G.c. Ezimora, A. LübbertAbstract:The aim of this investigation is to determine the extent of the region around a Single Impeller from which, with a significant probability, gas bubbles are sucked into the cavities.
Evanthia Babalona - One of the best experts on this subject based on the ideXlab platform.
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Dispersion Characteristics of Gas‐Liquid Contactors Agitated by Single and Double‐Stage Rushton Turbines
Chemical Engineering & Technology, 2002Co-Authors: Joannis Markopoulos, Spiros V. Paras, Evanthia BabalonaAbstract:The study of the loading/complete dispersion transition is of great importance especially in processes with enhanced mixing requirements. In the present work, new data and correlations concerning the dispersion characteristics in gas-liquid contactors agitated by Single and dual Rushton turbine systems are reported. The maximum amount of gas which can be completely dispersed, in the presence of gross, well defined recirculation patterns of gas at a given stirrer speed is predicted. Under these conditions, an increase of flow number with increasing Froude number could always be estimated. With decreasing Impeller diameter, d, the same gas amount could be dispersed at higher stirrer speeds. At Impeller spacing ΔH=2 d, for d equal to 0.06 and 0.08 m, and ΔH=1.54 d, for d=0.10 m, the complete dispersion conditions of the dual Impeller systems were slightly better than the corresponding conditions of the Single Impeller systems.
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Complete Dispersion Characteristics in Gas‐Liquid Contactors Agitated by Single‐ and Double‐Stage Rushton Turbines
Chemical Engineering & Technology, 2002Co-Authors: Evanthia Babalona, Spiros V. Paras, Joannis MarkopoulosAbstract:The study of the loading/complete dispersion transition is of great importance especially in processes with enhanced mixing requirements. In the present work, new data and correlations concerning the dispersion characteristics in gas-liquid contactors agitated by Single and dual Rushton turbine systems are reported. The maximum amount of gas which can be completely dispersed, in the presence of gross, well defined recirculation patterns of gas at a given stirrer speed is predicted. Under these conditions, an increase of flow number with increasing Froude number could always be estimated. With decreasing Impeller diameter, d, the same gas amount could be dispersed at higher stirrer speeds. At Impeller spacing ΔH=2 d, for d equal to 0.06 and 0.08 m, and ΔH=1.54 d, for d=0.10 m, the complete dispersion conditions of the dual Impeller systems were slightly better than the corresponding conditions of the Single Impeller systems.
Joannis Markopoulos - One of the best experts on this subject based on the ideXlab platform.
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Dispersion Characteristics of Gas‐Liquid Contactors Agitated by Single and Double‐Stage Rushton Turbines
Chemical Engineering & Technology, 2002Co-Authors: Joannis Markopoulos, Spiros V. Paras, Evanthia BabalonaAbstract:The study of the loading/complete dispersion transition is of great importance especially in processes with enhanced mixing requirements. In the present work, new data and correlations concerning the dispersion characteristics in gas-liquid contactors agitated by Single and dual Rushton turbine systems are reported. The maximum amount of gas which can be completely dispersed, in the presence of gross, well defined recirculation patterns of gas at a given stirrer speed is predicted. Under these conditions, an increase of flow number with increasing Froude number could always be estimated. With decreasing Impeller diameter, d, the same gas amount could be dispersed at higher stirrer speeds. At Impeller spacing ΔH=2 d, for d equal to 0.06 and 0.08 m, and ΔH=1.54 d, for d=0.10 m, the complete dispersion conditions of the dual Impeller systems were slightly better than the corresponding conditions of the Single Impeller systems.
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Complete Dispersion Characteristics in Gas‐Liquid Contactors Agitated by Single‐ and Double‐Stage Rushton Turbines
Chemical Engineering & Technology, 2002Co-Authors: Evanthia Babalona, Spiros V. Paras, Joannis MarkopoulosAbstract:The study of the loading/complete dispersion transition is of great importance especially in processes with enhanced mixing requirements. In the present work, new data and correlations concerning the dispersion characteristics in gas-liquid contactors agitated by Single and dual Rushton turbine systems are reported. The maximum amount of gas which can be completely dispersed, in the presence of gross, well defined recirculation patterns of gas at a given stirrer speed is predicted. Under these conditions, an increase of flow number with increasing Froude number could always be estimated. With decreasing Impeller diameter, d, the same gas amount could be dispersed at higher stirrer speeds. At Impeller spacing ΔH=2 d, for d equal to 0.06 and 0.08 m, and ΔH=1.54 d, for d=0.10 m, the complete dispersion conditions of the dual Impeller systems were slightly better than the corresponding conditions of the Single Impeller systems.
Mingying Ju - One of the best experts on this subject based on the ideXlab platform.
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effects of baffle design on the liquid mixing in an aerated stirred tank with standard rushton turbine Impellers
Chemical Engineering Science, 1997Co-Authors: Weiming Lu, Hongzhang Wu, Mingying JuAbstract:Abstract The effects of width and number of baffles in mechanically agitated vessels with standard Rushton turbine Impellers are examined for systems with and without aeration. The insertion of the appropriate number of baffles clearly improves the extent of liquid mixing. However, excessive baffling (i.e. n b > 8or B/T> 0.2 ) and sparging gas through the Impeller would interrupt liquid mixing and lengthen the mixing time. This study found that sparging gas through the Impeller leads to an increase in the mixing time of more than 20% because it reduces the liquid pumping capacity of the Impeller. A numerical technique was applied to examine the same effect on several extreme baffle conditions and the cases of higher gas flow rates and rotational speeds. To generalize our results obtained, the numerical technique was applied to simulate for a system with triple Impellers. The trends of the mixing time were found to be very similar to the Single Impeller system. By correlating the mixing time with n b , B/T, Q g and N , the following correlation is obtained for the system with Single Rushton turbine Impeller under non-gassed and aerated systems.Nt M = 55.7(n b ) −0.30 ( B/T ) −0.1535 ( Q g /ND 3 ) 0.0296 and the similar correlation for the triple Impeller system can be given asNt M = 46.5(n b ) −0.295 ( B/T ) −0.327 ( Q g /ND 3 ) 0.010
