materials preparation | Drying
airflow and 40% of the energy.” Performance of the Eureka system is further
enhanced by the company’s Flowmatik airflow regula- tion technology, which uses motorised calibration valves and automated control software to ensure the system delivers precisely the airflow required at any point in the drying process. Moretto founder and CEO Renato Moretto says the
Eureka technology is suitable for both small and large drying installations. He says the company has around 60 systems currently in operation, with the smallest sized for a throughput of 1,200kg/hr and the largest handling more than 6,000 kg/hr (the technology is designed to be applied for throughputs of up to 12,000 kg/hr). Most Eureka installations to date have been in the
energy-intensive PET processing sector and, as the scale of any savings escalates with the throughput, interest is greater at the larger end of the market. Interest is also greatest in what Moretto describes as “the more mature markets” such as the US, where control of operating cost is seen as a key competitive factor. “When talking about additional costs, the return on
Below: Conair’s compact MicroWheel dryer is designed for mounting on the machine feed throat
investment can be realised in about three months and you can have an amortisation in 12 to 24 months,” Moretto says. He estimates the typical savings from implementing the Eureka drying system in a PET application to amount to around €50,000 a year. With an approximate 10,000 PET processing plants in operation around the world, he says the company has “extremely high” expectations for the technology. Meanwhile, the VBD dryer from US-based Maguire
takes a very different approach to resin dehumidifica- tion, replacing conventional desiccants with a vacuum to create the moisture gradient that draws water from the polymer. The latest upgrade to the system incorpo- rates load cells to provide continuous monitoring of the levels of polymer in the vacuum chamber and retention hopper, increasing accuracy and providing improved documentation of resin throughputs. The load cells operate on a loss-in-weight basis, providing real-time data on material throughput that is unaffected by variation in bulk density and provides a measurement accuracy of ±0.5%, according to Mike Gera, senior dryer product manager. “The use of load cells in the vacuum and retention vessels provides 100% reliability and is superior to alternatives
such as capacitive proximity sensors and paddle wheel sensors. Because of their accuracy, they provide moulders and extrusion processors with new
54 INJECTION WORLD | March 2015
tools for increasing the efficiency and versatility of their operations,” he says. Benefits for users include more detailed throughput
tracking and the option to run the dryer in batch mode, where the system can be set to dry a particular weight of material before conveniently shutting down with a completely empty vacuum chamber and retention hopper. Improved throughput control also pays benefits in terms of energy efficiency as there is a reduced likelihood of drying material that is not subsequently used for production. Maguire claims its VBD vacuum drying technology
cuts energy use by 60% compared to standard desiccant dryers. Start-up times are also claimed to be reduced – down to one sixth that of conventional systems - while resin exposure to the elevated drying temperatures is cut by up to 80%. The system works by feeding the material by gravity through three vertically-arranged processing stages: the resin is heated to the drying temperature in the first stage; placed in a vacuum chamber to draw out the moisture in the second stage; then stored under a blanket of dry air in the final retention hopper up to the point of discharge to the processing machine. Last year, Germany’s Motan-Colortronic added its
ATTN automatic temperature and dew point control system to the standard specification across the full Luxor A dryer product line from 80 to 2,400 litres capacity. ATTN is claimed to maintain a constant dew-point for the process air and is said to be a particularly useful addition when handling plastics that must be dried to a predefined moisture content or that are susceptible to over-drying. The ATTN system continuously regulates and documents the dew point, holding it to within ±1˚C of the set point (the device is generally installed in the drying
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Moretto claims its modular Eureka system can cut drying energy use by more than 50%
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