Issue link: http://www.e-digitaleditions.com/i/713316
7 PBE August 2016 Words worth noting from PBE articles in 2016 January — Mixing and Blending "The mixing paddles create a fluid bed, and the continuous rotation throughout the entire blending cycle assures that all material remains in motion, preventing segregation in batches of varying ingredient bulk densities. Internal flights then lift and direct the blended product to the discharge gate, evacuating the rotating mixing drum, which is free of dead spots." — from "Case history: Perfecting the art of tea" "If your ingredients have different particle sizes that can be screened into fractions, then you can perform a statistical analysis of multiple samples. In this method, each sample is separated into fractions, often by sieve testing, and then each fraction is weighed to determine whether the amount of each ingredient in the sample is in correct proportion." — from "Suppliers' tips" February — Screening and Classifying "A correctly tensioned screen is completely taut. This stretches out the mesh to the designated mesh opening size. An incorrectly tensioned screen will sag on the insert frame, causing the mesh openings to distort and restrict your material's flow through the screen." — from "Tips for optimizing screener performance" "We all enjoy light reading, so the first step to understanding and preventing screening problems is to read the manual in its entirety. The screener's manual will outline important details pertaining to your specific screening machine. From setup and installation to proper greasing schedules for your motor, the manual will cover all the information you need to properly operate and maintain your screener." — from "Suppliers' tips" March — Pneumatic Conveying "In a vacuum or pressure pneumatic conveying system, the air pressure changes as the air flows through the system. As the air pressure changes, so does the air's volume and capacity to hold moisture." — from "Pneumatic points to ponder…," Jack D. Hilbert "With a mechanical conveying system, the surrounding air isn't moving, so dust can hang in the air and reach dangerous concentrations. A pneumatic conveying system encloses the material and dust and keeps them moving, allowing you to control the air-to-material ratio and ensure that a dangerous dust concentration doesn't develop." — from "Using pneumatic conveying to reduce your combustible dust explosion risk," Mitch Lund April — Drying "Since a cascade exhaust system uses the exhaust air from one zone as the makeup air for another zone, the system can reduce a dryer's overall exhaust-air volume by around 5 percent compared to an independent exhaust system. A lower exhaust-air volume means that the system can use smaller, less expensive exhaust components, such as exhaust fans, fan motors, and ductwork." — from "Using cascade exhaust airflow in conveyor dryers," Shannon Stanforth "The first step in reducing a slurry material's moisture content is to reduce the evaporative load. Mechanical dewatering is always more efficient than thermal drying, and increasing the solids concentration will allow you to minimize the dryer size." — from "Suppliers' tips" May — Bagging and Packaging "The ability to condition all sides of your bulk bag at multiple heights is an important factor in many applications. If your material is heavily solidified throughout the bag but your conditioner's arms only apply pressure to a small area on two sides, you won't be able to fully break up agglomerates and may still experience flow problems." — from "Selecting a bulk bag conditioning system" Robert Meirick and Chad Gleesing "In my experience, companies that most successfully implement packaging automation do considerable research and investigation prior to switching to an automated system. This includes understanding all the implications related to automating that can impact a production process both during the changeover period and after." — from "Suppliers' tips" June — Size Reduction "In general, fluidized-bed jet mills scale up proportional to gas flow. For example, if the tests reveal that 2 pounds of compressed air grinds 1 pound of material to the desired particle size, you can use that 2-to-1 air-to- material ratio to determine the mill size for your required production rate." — from "How to select and start up a fluidized-bed jet mill system," Gary Liu "Ensure that the grinding equipment is fed material at an even, metered rate across the entire material inlet if your process uses flood and surge feeding. This will make use of the equipment's entire grinding surface area." — from "Suppliers' tips" July — Mechanical Conveying "If your process is generating static electricity, install grounding straps from the conveyor to rigid electrical or pneumatic piping to dissipate the electrostatic charge. Also, when welding in the area, be sure to place the ground clamp so that the current doesn't flow through the gear drive and arc between the gear teeth." — from "Diagnosing common gear-drive problems," David Kennedy "In an explosive environment, use only intrinsically safe electrical devices and explosion-proof components. In some situations, the conveyor controls can be located in a designated safe area while the mechanical conveying equipment is in the hazard area." — from "Suppliers' tips"