The other day I was talking to an operation manager about his fixed-bed reactors. These reactors are large tanks filled with different layers of material. The main component of the bed consisted of catalyst pellets which were placed in a centralized layer in the middle of the tank. Above and below the catalyst pellets, they used different sizes of ceramic balls to create a gradient buffer. This was important to disperse the gas to utilize the entire catalyst bed and reduce the possibility of channeling. The tanks were designed with a dump flange mounted at the bottom; so, when the catalyst material was used up, they could dump all the material from the tank and replenish. In recycling the reactors, they could reuse the ceramic balls after they have been reconditioned.
As we discussed the details further about the reconditioning process, the material from the reactor was dumped into drums and separated manually. The catalyst material was discarded; leaving the ceramic balls. The ceramic balls came in three different diameters, 6mm, 13mm, and 25mm. To separate these, they would slide three empty wire-meshed trays into the oven, and placed a specific diameter into a corresponding tray. Once the oven was filled with the ceramic balls, they would heat the oven to 400 deg. C. This would burn off any dangerous material that was collected on the surface from the process within the reactors. After the heat cycle, they would have to wait approximately one hour until the ceramic balls were cool enough to handle. After the cooling period, they would use a shovel to remove the ceramic balls from the trays.
The reconditioned ceramic balls were placed in storage drums and kept until they had to recycle another reactor. The removal of the ceramic balls from the oven would take an additional half hour to complete. The entire reconditioning process was labor intensive, time consuming, and ergonomically a safety issue. For each oven, they were only getting two cycles per day to recondition the ceramic balls. With the number of reactors that they had, they needed to either decrease the downtime for the oven, or purchase another batch oven.
After discovering the EXAIR website, they were intrigued with the Air Operated Conveyors (Line Vacs). If they could remove the ceramic balls at a much higher temperature, then this would allow them to reduce the cycle time. The EXAIR Air Operated Conveyor is a great product for moving bulk items over a short distance without manually having to shovel it, transfer it, or lift it. With the customer’s goal to minimize the downtime with the batch oven, I recommended the EXAIR model HT6064 2” Stainless Steel High Temperature Line Vac. With some standard PPE (Personal Protection Equipment), they could remove the ceramic balls from the oven without waiting for it to cool. The model HT6064 has a maximum temperature rating of 482 deg. C and a throat diameter of 45mm; large enough to move all three sizes of the ceramic balls.
The Line Vac, or Air Operated Conveyor, operates by using compressed air to generate a vacuum. It does not have any motors or moving parts to wear, and the inline design makes it easy to attach a transfer hose to the vacuum and exhaust ports. Personnel could now stand near the oven; stick the high temperature duct into the tray, remove all the ceramic balls, and transfer them to a nearby drum. By using the High Temperature Line Vac, they were able to reduce the oven down-time to only 15 minutes. This was plenty enough to reach the goal of increasing the cycles per day. As an added benefit, the back-breaking work of shoveling was removed; thus, increasing the health and safety of the workers.
If your company manually moves dry bulk products from point A to point B, you can contact an EXAIR Application Engineer to see if an Air Operated Conveyor could improve your process. For my customer, the HT6064 Line Vac improved the speed of their reconditioning process, and it took away the pain of shoveling which made this process undesirable for the personnel.