Issue link: http://www.e-digitaleditions.com/i/370117
7 PBE August 2014 Words worth noting from PBE articles in 2014 January — Mixing and Blending "There are several factors to consider when choosing the right shaft seal for a mixer. For the seal itself, you must consider the shaft's circumferential speed, the operating temperature and pressure, and the ingredients' physical and chemical properties." — from "Suppliers' tips" "When choosing shaft seals for a horizontally agitated mixer, you must understand that often shaft seals are only as good as the agitator shaft going through the seal." — from "Suppliers' tips" February — Screening and Classifying "While the sieve's vibratory motion is essential for processing your material, this motion can wreak havoc if the clamps holding the screen decks in place are improperly tightened." — from "Quick tips for solving screen-clamping problems with your circular vibratory sieve," Rob O'Connell "Proper installation requires that the sieve be mounted on a solid floor or structure that doesn't allow any secondary vibration. Also, adjusting the weight settings during machine setup can give you a precise vibration level to meet your application needs without causing excessive wear, which will reduce future maintenance needs." — from "Suppliers' tips" March — Pneumatic Conveying "Using a closed-loop pneumatic conveying system that recycles the expensive inert or conditioned conveying gas is a good way to handle these challenging materials while reducing operating costs." — from "Pneumatic points to ponder…," Jack D. Hilbert and Paul E. Solt "Providing a steady powder discharge from the filter- receiver to downstream processing or packaging equipment is just as important as achieving a constant flowrate at the system's pickup point." — from "Vacuum pneumatic conveying: Choosing the right system components for your non-free-flowing powder," Doan Pendleton "The total pressure drop in a system is the sum of the pressure drop incurred from the solids and the air (or other gas) moving through the conveying line and filter." — from "Suppliers' tips" April — Drying "To prevent airflow short circuits, first make sure that your raw feed material is uniformly loaded across the conveyor bedplate at the depth your drying operation requires. This will help the process air flow evenly through the bed without being able to escape around it." — from "Eight tips for improving your conveyor dryer's operating efficiency," Brian Roh "Conduction drying is particularly useful when evaporating solvent from the material in a closed-cycle drying circuit. The lower dryer outlet gas flow will result in smaller solvent recovery equipment and lower chilled water requirements for the condensing operation." — from "Suppliers' tips" May — Bagging and Packaging "When bagging efficiency goes down, it's common to blame the equipment, yet experience shows that the equipment often isn't the culprit. It's just as likely that the material characteristics or the bag quality have changed, disrupting the process." — from "Balancing the bagging triangle to maximize your packaging efficiency," Markus Lackmann "To prevent flow blockage during bag discharge, the automated bulk bag discharger is equipped with bag activators — steel plates that raise and lower the bag's bottom edges at timed intervals. This helps prevent material from bridging across the bag outlet and lodging in the bag corners." — from "Case history: Upgrade to automated bulk bag discharger with gravimetric controls improves winemaking process" "In general, the major emission sources from bagging operations are open transfer points, spillage from feed nozzles, feeder shaft seals, and equipment flange and gasket joints. Leakage could result from an improper or weak bag that splits or from a badly sealed bag." — from "Suppliers' tips" June — Size Reduction "In most applications, the clearance between the hammer tip and screen has only minor influence on grinding performance. Generally, a larger tip-to-screen clearance provides the greatest grinding capacity and efficiency." — from "Hammermill maintenance for top grinding performance at a lower operating cost," Mark Heimann "In a fluidized-bed jet mill, size reduction is achieved by particle-to-particle collisions within the fluidized bed. High-velocity gas streams (compressed air, inert gas, or superheated steam) accelerate the particles in the material bed; there's no impact against the mill's surface or its rotating grinding elements such as occurs in mechanical impact mills." — from "Suppliers' tips" July — Mechanical Conveying "The standard belt conveyor has a lower capital cost than vibrating-trough conveyors but costs more to operate and maintain over the long term, especially in sanitary handling applications." — from "Belt and vibrating- trough conveyors: Some guidelines for selection," Paul Cichanowski "For many hot materials, a static screw elevator is a good choice. A static screw elevator is used to convey bulk material at temperatures up to 1,500°F. If the material temperature needs to be maintained during elevation, the elevator's rotating lift tube can be insulated." — from "Suppliers' tips"