It is always suggestable to go for much in-depth of pilot plant studies before arriving at the big risk time.įurthermore, in case of any doubt, checks and cross checks from different agencies are likely to be obtained and it is available at reasonable cost. Pilot plants do come and go but the commercial plant determines the profit percentage. The agitator price is somewhat very little in comparison to what a process would gain and deserves from a reasonably good design. In fact for thumb rule at low speed, wattage equals the weight of total mass in grams transferred except in thixotropic conditions.įor both turbulent and viscous motion flow rate is determined by power of impeller diameter for viscous impellers. We shamefully take motor margins as 50% minimum. Power calculation in viscous fluid is cumbersome and then also is unreliable. TERMED AS THE IMPELLER NUMBER.Ĭonsidering gear efficiency and motor margin, motor power is determined. K= A CONSTANT VARIES GREATLY FROM 0.3 UPTO 8 AND IS DEPENDENT MAINLY ON BLADE GEOMETRY, TANK DIMENSIONS, BAFFLES, PHYSICAL FLUID CHARACTERISTICS, ETC. Basic power calculation for turbulent flow is :. Now the international trend is that if the process permits (unless molecular chains break up or organic growth is hampered in biological processes) lower speeds are only negotiated with motor power reduction without affecting the application parameters. Again lower speed was thought to be superior in terms of application. Till date we very often encounter motor power selection much on higher side with no necessity. I am very sorry for my weakness even in rough schematic drawing that could have helped in better understanding. With its diameter close to tank diameter, is used for viscosity above 80 poise.Īnother very effective design for handling viscous fluid is to use pitched blade turbine placed at bottom of draft tube (equaling 70% of tank dia.) at medium speed. Helical Ribbon looking like screwed ladder or double helix model of our gene.Anchor (with its namely look) is used for heat transfer from bottom or scraping viscous liquids.Suggested for oil-water emulsion, lubricants, paints, etc.
Bad design for blending simple solutions as well as handling semi solids (grease, honey etc.). Saw Tooth Cutter is reasonably good for handling medium to high viscous liquids.Stator rotor– Old outdated design supposed to bring highest shearing action and usually specified for oil-water emulsion.Curved vane impeller looks like straight Pelton wheel designed to hold moving particles for some time e.g.Of interest for mining people for mineral washing and beneficiation for energy efficiency. Aerofoil is having a classic stand fan blade type look and its properties are almost like hydrofoil impellers.Its flow efficiency is better than marine propeller, replacing the later in most applications and is most desired for mixing purposes but unsuitable for high shear application. Hydrofoil is supposed to be a foil in water and looks like pitched blade turbine with an angled cut on the lower periphery.Mainly used for medium viscous liquids and solid suspension. 45 degree vertically inclined flat blades (like ceiling fans), has reasonable flow and shear compromising both.