Both VBD models incorporate the same operator-friendly software and controller perfected for the LPD dryer, and the same five-year warranty. Additional VBD models will be introduced in the first half of 2014.
VBD 150 Dryer Provides Cost Benefits of Vacuum over Desiccant SystemsThe cost savings achieved with vacuum drying result from a reduction in energy consumption of up to 60% in comparison with desiccant dryers; elimination of the need to regenerate desiccant; and reduction in startup time as a result of a drying cycle that is only one-sixth as long. In addition, resin is exposed to elevated temperature for as much as 83% less time than with the desiccant dryer, which means lower risk of material degradation.
In addition to the efficiency of vacuum drying, another reason why drying is six times faster than with desiccant dryers is Maguire's use of dry air to purge the vacuum chamber of the moisture that the vacuum has released from the resin pellets, thus preventing reabsorption.
As an example of the energy efficiency of the VBD system, the first model in the series, the VBD 1000, draws power at the rate of 53 W/kg/hr, as compared with 75 W/kg/hr for the most efficient wheel dryer, according to Mr. Smith.
The three vessels in the VBD dryer systems are, from top to bottom: a heating hopper that brings resin to a target temperature; a vacuum vessel in which vacuum reduces the boiling point of water, causing moisture within the pellets to volatilize and be forced out of the pellet into the low-pressure environment surrounding it; and a pressurized retention / take-away hopper that is continually purged by a membrane air dryer to maintain the target level of dryness until the material is discharged. The heating circuit of the VBD system includes a blower whose variable-frequency drive optimizes blower speed and saves energy.
Vacuum drying is a proven concept, with several thousand Maguire LPD dryers now in service around the world. Maguire will continue to produce and support the LPD system.