To consolidate and modernize a paint manufacturing facility, it became obvious that the varied material handling characteristics of TiO2, Calcium Carbonate, Resin, Talc, and Clay would require a special focus on conveying. Each material had different conveying characteristics, and each affected differently when conveyed. Some of the bulk materials consisted of lumps ’the size of a basketball’ and each ingredient was delivered in a 2000lb (910 kg) bulk bag, requiring the bulk bag to be offloaded and transferred to one of ten mixers.
Processing Challenges
To accommodate many variable recipes for paint production, including the addition of minor colorants and additives, a site visit was arranged to discuss the best system design and equipment specification to automate the process. Issues at hand included the difficulty of breaking down the large lumps, as well as finding the best way to handle TiO2. A lump breaker system could be used as a particle size reducer but presented a problem for the difficult flow properties of TiO2. The applications required a total of four bulk bag unloading and transfer systems, with a required unloading time of just 5 minutes for each 2000-pound bag of TiO2. Additionally, the application required a very minimal delay in loading the mixer as multiple bulk bags were changed, furthering the requirement to avoid wasted time when changing bags. Since the entire system operated in an Explosion Hazard area, engineering challenges for the conveyor system were significant.
Application Solution
Aerocon Aero-mechanical conveyors are well-suited for the transfer of a variety of materials at the same transfer velocity. Unlike pneumatic conveying systems, Aero-mechanical conveyors can accommodate a wide variety of bulk densities without the need to change conveying parameters. Additionally, the conveyor does not pump air, and therefore does not require filtration. The application consists of an Aerocon bag dump station, a unique twin hopper screw feeder, purpose-built gravity diverter valve, a split-frame type bulk bag unloader, a lump breaker, and two Aero-mechanical conveyors. The bulk bag assembly was over 20 feet high to accommodate the diverter valve. Bulk material was unloaded from bulk bags, with minor ingredients hand dumped via integrated reverse jet filter type bag dump station, fed via a screw feeder and on to the first of two Aero-mechanical conveyors.
Low Headroom? No Problem.
The 450V Aero-mechanical conveyor elevates bulk materials 20’ before turning through 90 degrees and running horizontally for 12’ where bulk material discharges into a second Aero-Mechanical unit. Running at a lower linear velocity, this mechanical conveyor is equipped with three-outlet valves. The low profile Rotating Tube Section Valves are pneumatically operated and allow the selection of the appropriate destination mixer. The overall height of each valve is 15” including the operator, which in comparison to the height of a typical filter receiver, allows greater flexibility for low headroom environments.
For products such as TiO2 that smear inside conveyor tubes, the Aero-mechanical conveyor has a unique ability to keep the bore of the tube clean because of the method of conveying generated by the cable and disc assembly. Also essential to the success of this application was the design of the control panel. VAC-U-MAX is a UL approved panel manufacturer. Using a Micro Logic programmable controller housed within a ’Z’ Purged standard enclosure, one panel incorporated controls for the motors, reverse jet filter, lump breaker, and screw feeder. Additionally, the selection of the appropriate mixer and isolation valves were made. The ’Z’ purge enclosure uses positive pressure within the panel to protect against explosion risk.
Aero-Mechanical Conveying Explained
An Aerocon Aero-mechanical Conveyor is constructed of two parallel tubular housings (typically 3” or 4” tubes) containing a continuous loop of steel cable. Polymer discs smaller than the inside diameter of the tubes are mounted at equal intervals along the steel cable. One side of the housing is for conveying and the other is for return. Material inlets and outlets are suitably located for the application. Two sprocket assemblies, one providing drive and linked to a small motor (Typically 2 or 3 hp) and the other guiding the return, complete a basic system. Aerocon Conveyors have major advantages over competitive units by virtue of a superior bi-directional tensioning system that is independent of the drive assembly, offering easy clean self-draining housings, with geared motors as standard. Additionally, Aero-Conveyors are more economical to run, saving on overall energy costs.
Typical Applications
The Aerocon Aero-mechanical Conveyor is ideal for applications requiring the loading of powders, granules, beans, tea, and other friable bulk ingredients from paper sacks, bulk bags, blenders, and bag dump stations, including transferring bulk ingredients to packaging lines. Bulk ingredients are conveyed cleanly without segregation, and gently, to avoid product degradation. The application is dust-free and can accommodate floor level loading.
