Dense-Phase Vacuum-Conveying System To Minimize Pellet Fracturing, Angel Hair And Equipment Wear

Dense-phase vacuum-conveying system to minimize pellet fracturing, angel hair and equipment wear

26-Oct-16

The patent-pending R-PRO™ dense-phase vacuum-conveying system developed by Conair to minimize pellet fracturing, "angel hair" and equipment wear caused by conventional dilute-phase conveying, will make its first appearance at K2016. Conair will present the results of R&D efforts aimed at taking advantage of the fact that the system can be “tuned” to match material speed to application requirements and the characteristics of the material being conveyed.

When the Conair R-PRO^® [Resin-PROtection] conveying system was first introduced a year ago, the focus was on slow-speed dense-phase conveying, which eliminates pellet fracturing, dust, "angel hair," equipment wear and other problems caused by conventional high-speed vacuum conveying. However, Doug Brewster, Conveying Product Manager, and the inventor of the system, says R-PRO is not only capable of running at low speeds. It can also operate in the more conventional dilute phase, with individual pellets fully suspended in the high-speed air… or at any speed in between. He reports that, as material speed increases, there is a gradual transition from dense phase to dilute phase, and “we have found we can control that transition very effectively and run right on the edge in a sort of mixed pulse phase. We think we can use this for higher-volume unloading where more airflow may be desirable but truly high-speed operation is not necessary or desirable.”

In slow-speed, dense-phase conveying, pellets move in compact slugs of material at speeds between 300 ft/min (91.5 m/min) up to 1200 ft/min (366 m/min). In conventional high-speed conveying, 4500 ft/min (1372 m/min) is a typical low speed and air speeds up to 6000 ft/minute (829 m/min) are not uncommon. Response to this innovation has been very positive, especially since conveying throughput and distances are comparable to high-speed systems. In addition, since R-PRO uses standard deep-vacuum pumps, conveying tubes and material receivers, the system costs only a little more than conventional systems and can be easily retrofitted to existing systems.
The variable-speed capabilities of R-PRO now give processors the flexibility to tune the system to their exact needs. For highly abrasive glass- and mineral-filled materials, Brewster says, the slowest material speeds are “absolutely the best.” However, he continues, “we are finding that we can run at higher speeds with some materials and still avoid a lot of the usual problems. This can be a big advantage for unloading bulk trucks and railcars where more airflow is helpful.” He suggests this mid-range speed would be good with materials like PET and acrylic, which are only mildly abrasive, or with light-bulk-density materials (e.g.: 15 lb/cu ft), like PE sheet flake. “It’s really easy to raise or lower material speed and airflow,” Brewster says, “and we can do it with great precision and control. The great news is the flexibility that the R-Pro system provides. The customer can set up and store programs (up to ten per receiver station) and convey different materials at different speeds.”

The new FLX-128 Plus system, which will be set up to control the R-PRO demonstration, is scalable and has all the same features that made the previous web-enabled FLX-128 Conair’s most popular conveying system control, but now is smarter, faster, and more powerful. It not only can control R-PRO systems, but also integrates Conair’s newest line-proofing systems including the Invisible Line Proofing (ILP) system mentioned below. The FLX-128 Plus flexible control system utilizes a combination of centralized I/O and expansion modules, interconnected via industrial Ethernet to provide control of up to 128 receivers, 40 pumps (plus 2 back-up pumps) and 256 source valves. A full color touch screen with descriptive icons ensures that even with little or no training, any user will be comfortable monitoring or making changes on up to 40 independently operating vacuum systems.

A mobile drying/conveying system (MDCW) with Conair’s newest DC-A touchscreen control interface. The MDCW combines an efficient Carousel^® Plus Dryer with a conveying blower, dust collector and direct-feed vacuum receiver to convey dried material to the throat of a processing machine – all assembled on a safe, convenient wheeled cart. Featuring intuitive graphical design, with minimal text and no function codes to decipher, the DC-A touchscreen control has descriptive help screens for operators and features auto-start capabilities, password protection and has Conair’s Drying Monitor capabilities built in. Trending capabilities simplify maintenance and troubleshooting, while providing users with information they can use to optimize drying parameters and save energy. The new DC-A control will also be offered on smaller Conair desiccant-wheel dryers.

The new MedLine^® family of clean-room-ready products was developed to help medical plastics processors select, install, commission and start up white rooms and cleanrooms faster and with less paperwork. It includes a complete range of auxiliaries – 40 different models and 170 different configurations in all – for molding and extrusion of medical products. The design of MedLine conveying, storage, drying, blending, heat-transfer and downstream extrusion products are all based on proven Conair designs, but they have been specially sized, configured, documented and supported for use in cleanrooms and other controlled environments.