生化工程第四章1(搅拌器的型式及流型).pptVIP

第三章搅拌器轴功率计算 第三章 机械搅拌轴功率计算 搅拌目的 提高气液传递速率：打碎气泡，增大气液相的接触面积；使培养液产生涡流，延长气泡在液体中的停留时间，增大H0；减小气泡外滞流液膜的厚度，从而减小传递过程中的阻力。 混合物料，增强传质和传热效果 一、机械搅拌通风发酵罐（简介） H/D=2; d/D=1/3; B=0.1D ha=0.25D S=3d C=d 式中：H——罐高; D——罐的直径; d——搅拌器直径; B ——挡板宽度; ha——封头高度 ; S——两挡搅拌器之间距离；C——底挡搅拌器与下封头底之间距离 二、搅拌器的型式及流型 （一）型式 轴向推进：螺旋桨式 径向推进：涡轮式 1、型式 Lightnin Mixers Inc Axial Flow Impellers Recommended for applications requiring moderate pumping action and powder-wetting capabilities Superpitch design 1.5 pitch ratio for greater mixing capabilities Standard axial flow Optional ring guard prevents damage from dip tubes, temperature probes and other in-tank devices Recommended for low- to medium-viscosity, flow-controlled applications Classic 45° pitched blade design Produces a desirable balance of flow and shear The impeller of choice in many standard applications Recommended for axial-flow impeller for side-entry applications Designed for demanding pulp and paper applications Also used in other side-entry applications, such as oil storage Features minimal radial flow Recommended for gas-liquid dispersion and mass transfer-controlled applications Can improve mass transfer by 30% compared with Rushton turbines Decreases shear rates up to 75% Can reduce energy costs up to 45% Improves yields in shear-sensitive processes Recommended for higher-viscosity applications requiring high flow in the transitional flow regime Reduces blend time by half Shear rates are modest for both high- and low-viscosity conditions Fluid foil design delivers better axial motion and reduces power consumption Recommended for up-pumping applications Ideal for multi-phase applications, such as fermentation, polymerization and hydrogenation High gas induction from surface Controls foaming Recommended for low-viscosity flow-controlled applications Varying angle options optimize processes by changing the impeller diameter/tank ratio Maximizes flow with ability to add