Enzymatic hydrolysis of cellulose is one of the major technical obstacles which constraint the large-scale industrialization of cellulosic ethanol. It is necessary to carry out works on the details of reactor design for enzymatic hydrolysis of cellulose. In present study, a method combining experimental and computational fluid dynamics is applied to study the hydrodynamics character of reactors for enzymatic hydrolysis of cellulose.
Rheological equations for different stages of enzymolysis liquid were established through experimental study. The results showed that, the initial rheological equation of enzymolysis liquid is: τ=2.12012γ0.03267, the rheological equation of enzymolysis liquid after 10 hours is:τ=1.3403γ0.0228, the rheological equation of enzymolysis liquid after 20 hours is:τ=0.7540γ0.2051.
The characters of fluid flow for different impeller to reactor diameter ratios at different stirring speeds were studied. The results showed that the reactor using the combined impellers exhibited better fluid flow characteristics. Uniform velocity and viscosity distribution were obtained and low velocity region and high viscosity region almost disappeared. The mixing effects and liquidity were improved.
This paper proposed a Quasi Plug-flow Reactor which was especially suitable for the cellulose enzymolysis liquid with high viscosity for the first time. Clapboards were set in the reactor in order to construct multi series reactor which can significantly improve the liquid velocity distribution and viscosity distribution of enzymatic reactor. The optimal combination of clapboards is type B, with optimal angle of 5 °.
The residence time distribution can be greatly improved if proper clapboard parameters were selected. Quasi plug-flow can be obtained in enzymatic hydrolysis reactor via optimizing the clapboard parameters.
The setting of baffles effectively reduces the fluid viscosity between mixing zone and the wall, which is beneficial to optimize the flow field. The optimal width, number, and inclined angle of baffles are W/Di = 0.1, four and 0 °, respectively.
The simulation results of the effect of stirring speed and clapboard parameters on the fluid flow field distribution and power consumption provide a theoretical guidance for reactor design, geometry structure improvement and scale up.
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