Agitator Technical Quick Handbook For Sales Engineers – Prepared for Chee Horng 1. Introduction to Mixing & Agitator Basics Mixing is a vital operation in process industries, ensuring uniform composition, heat transfer, and reaction control. An agitator provides mechanical motion to achieve blending, suspension, or dispersion. Common Mixer Configurations: Top-Entry Most common; easy maintenance; suitable for general mixing. Side-Entry Used for large tanks or energy efficiency in blending. Bottom-Entry Used in hygienic or limited headroom applications (pharma, food). Basic Mixing Parameters: • Reynolds Number (Re): Determines flow regime (laminar, transitional, turbulent). • Power Number (Np): Relates power draw to impeller design and efficiency. • Flow Type: – Axial flow → top-to-bottom circulation (hydrofoil, propeller). – Radial flow → high shear, side circulation (Rushton turbine). 2. Impeller Types & Applications Impeller Type Flow Pattern Typical Application Propeller / Hydrofoil Axial Low-viscosity liquids, blending, heat transfer Pitched Blade Turbine Mixed General-purpose, solids suspension Rushton Turbine Radial Gas dispersion, high shear Anchor Tangential High viscosity, heat transfer near walls Helical Ribbon Axial (up/down) Very high viscosity (paste, polymer) Impeller Selection Tips: • Choose axial-flow impellers for blending or heat transfer (efficient pumping). • Select radial impellers for gas dispersion or high-shear mixing. • Larger impeller diameter → better flow at lower speed. • Multi-stage impellers for tall tanks or multi-phase mixing. 3. Tank Design, Baffles & Scale-up Tank geometry and baffles directly affect mixing performance. Baffles prevent swirling and improve top-to-bottom circulation. Tank Ratio Typical Range / Guideline Tank Diameter / Impeller Diameter (D/T) 0.3 – 0.5 Liquid Height / Tank Diameter (H/T) 0.8 – 1.2 Baffle Width / Tank Diameter (B/T) 1/10 – 1/12 Impeller Clearance / Tank Diameter (C/T) 0.3 – 0.5 Scale-up Principles: • Maintain constant tip speed or power per volume for similar performance. • Watch for heat transfer and gas dispersion limitations in larger tanks. • Geometric similarity helps predict flow and suspension behavior. 4. Troubleshooting & Performance Optimization Common Mixing Issues and Solutions: Issue Possible Cause Typical Solution Poor suspension Low impeller speed or wrong type Increase speed or use pitched blade turbine Vortex formation No baffles or too high speed Add baffles / reduce speed Dead zones Improper impeller position Adjust impeller height or add second impeller High power draw Oversized impeller or viscous fluid Optimize diameter or use hydrofoil Performance Optimization Tips: • Verify mixing goal before selecting impeller. • Balance energy efficiency and process requirement. • Ensure mechanical seal, bearing, and shaft are aligned. • Monitor vibration and temperature for predictive maintenance. Key Terminologies: Re = ρND²/µ (Reynolds number) → flow regime indicator Np = P / (ρN³Dâ– ) (Power number) → efficiency index Tip Speed = πDN → mixing intensity measure Prepared for Chee Horng Generic Logo Placeholder – Mixing Technology | Generated on 2025-10-10
