Issue link: https://www.e-digitaleditions.com/i/1277345
12 © Copyright Powder & Bulk Engineering 2020 © Copyright Powder & Bulk Engineering 2020 The bulk bag fi ller The supplier delivered one model C2-2R bag-fi lling sys- tem to the Oregon wastewater treatment facility, and Os- tara engineers installed it under a large structural steel frame that holds the four fl exible-fabric storage silos. A three-position slide-gate valve installed at each silo's out- let controls pellet discharge, and a common feed chute below the slidegate valves directs the pellets into a bulk bag. The bulk bag fi ller is 60 inches wide by 74 inches deep by 110 inches tall, its fi lling zone where the pallet sits is about 15 inches above the fl oor, and the fi ller's framework sits on load cells for accurate gain-inweight bag weigh- ing. The fi ller requires an 80-psi compressed-air source (at 7.5 cubic feet per cycle) to operate its pneumatically ac- tuated quick-release bag-loop hooks, infl atable neck seal, bag-liner infl ator, and air springs. To fi ll a bulk bag, an operator places an empty pallet on a powered roller conveyor in the fi lling zone and hangs the bulk bag's support loops in the loop hooks located on the bag-hanging frame. Next, the operator pulls the bag's neck over the infl atable neck seal, which is attached to the end of the fi lling nozzle and creates a dust tight seal with the bag when infl ated. The fi lling nozzle is a dual concentric fi lling spout with an integral bag-liner in- fl ator that allows the pellets to enter the bag by gravity through the center annulus and the displaced air to exit through the outer annulus. The bagliner infl ator's venturi combines compressed air with free air to create a posi- tive pressure that infl ates the bag in about 15 seconds. The operator accesses the fi ller's custom-programmed controller to close the loop hooks and infl ate the neck seal, bag liner, and air springs, which are installed under a vibration table in the fi lling zone. When infl ated, the air springs raise the vibration table and pallet above the roller conveyor to provide a secure fi lling platform. The operator then selects the silo to be discharged and ac- tivates the system, and the controller opens the appro- priate slide-gate valve to begin the bag-fi lling process. As the pellets fi ll into the bulk bag, the load cells contin- uously send weight readings to the controller, and the vibration table's two variable-frequency 1-horsepower motors activate as programmed to vibrate the pallet and bag to consolidate the pellets. When the bag is about 95 percent full, the controller partially closes the slide-gate valve to slow the fi lling rate to a trickle for the remaining 5 percent. Once the bag hits the target weight, the controller closes the slidegate valve, opens the loop hooks, and defl ates the neck seal and air springs to lower the pallet onto the powered roller conveyor. The controller also prints out a label detailing the bag weight, pellet size, date bagged, bag sequence number, and other pertinent informa- tion to ensure quality control. The operator then puts the label on the bag, removes the fi lling spout from the neck seal, and activates the powered roller conveyor to move the palleted bag out of the fi lling zone to an in- clined gravity roller conveyor for indexing. Reliable, effi cient bag fi lling Since installing the supplier's bagfi lling system in the Oregon facility, Ostara has purchased seven more systems for wastewater treatment facilities in the US, Canada, and the UK, and has plans to purchase more. "The whole bag-fi lling process only takes a couple of minutes; it's very fast," says Dharas. "And the bag-fi ll- ing system has a low air consumption and energy draw and is very reliable, which keeps maintenance and en- ergy costs low and minimizes downtime." The bag-fi lling system is easy to install and easy for the operators to use. "We gave the supplier some feed- back from our operators, and they were able to modify some things for us based on our input," says Dharas. "They've continued to improve the bag-fi lling system and have come up with some newer models that are even easier to use and require less maneuvering from the operators than the earlier model. Since we've been involved with the supplier, we've worked together to make a better bag fi ller." According to Dharas, the supplier has been responsive when the company has had technical or operational issues with the equipment or needs additional equip- ment. "A couple of times we've been caught behind the eight ball and needed a system in a hurry, and they've been very understanding and able to deliver when we've needed the equipment within a tight timeline. They've always come through for us." PBE