CFD Simulation And Reactor Design For High Solid Content Lignocelluloses Enzyme Hydrolysis

Enzyme hydrolysis is a vital part in lignocelluloses bio-refining process. The efficiency of enzyme hydrolysis can have great influence on the growth of bacteria in fermentation, product yield and energy consumption of the downstream process. In order to reduce the cost of bioethanol refining, high solid content of raw material is needed. But high solid loading can cause great influence on mass and heat transfer in the reactor, thus leading to increased reaction process power consumption and low conversion rate. In this paper, the enzyme hydrolysis of high solid content (30%) corn stover in5L helical ribbon impeller bioreactor was studied. Insoluble solid content, sugar concentration, particle size distribution and rheology property change of the material during enzyme hydrolysis were investigated. The results show that, during the digestion process, sugar concentration increased gradually, while insoluble solid content and particle size decreased. Materials all shows a shear-thinning non Newton behavior and the viscosity reducing gradually during the hydrolysis. Computational fluid dynamics (CFD) was used in this paper, a CFD simulation of enzyme hydrolysis process was established successfully and the rheology property change during the hydrolysis was introduced as an equation for dynamic simulation. The investigation of structure and operating parameters were conducted by using the CFD model. The results show that, d/D is the most important effecter in the power consumption and mixing of the reactor. The increase of d/D can lead to increased power consumption and decreased mixing time. The effect of rotation speed is influenced by the structure of the reactor and the properties of material. In general, with the increase of rotation speed, the power consumption increases and mixing time decreases. Moreover, with the increase of rotation speed, its effect on mixing performance also decreased. Finally, in the magnification of the reactor, using equal power per unit volume rule can get better performance. This paper laid a foundation for the CFD simulation of lignocelluloses biorefining process, and provide basic research for the design, optimization and industrialization of bioreactors.