New Way® Air Bearings is always committed to advancing motion solutions for new industries. Our partnership with Dedert is no exception. Since 1968, Dedert Corporation has been a leading manufacturer of process engineering technology across a wide array of industries. We brought the unique benefits of Porous Media Technology™ to bear on their problem, producing a patent pending high-speed rotary atomizer. This new innovation has the potential for wide-ranging disruption of existing atomizer technologies.
For the food and pharmaceutical markets, spray drying offers a method of producing dry powder from a liquid by drying the incoming medium with a hot gas. These rotary atomizers often use oil-lubricated spindle bearings or high-speed roller bearings, and as such come with numerous limitations. Among these drawbacks include oil contamination of the final product, short bearing lifespan, and high maintenance costs. New Way is well acquainted with the shortfalls contact bearing solutions, and was happy to assist with Dedert in developing a superior product.
Prior to contacting New Way, Dedert developed a magnetic bearing system to remove contact friction, and extend the lifespan of their atomizers. While magnetic bearings are non-contact, they are also highly delicate, as magnetic bearings require an active feedback controller as well as speed and position sensors along multiple axes. These controllers adjust the magnetic field through proprietary black-box software, and require a separate configuration file for each individual speed range.
The bearings themselves also require their own dedicated computer for the microcontroller, as well as a dedicated GUI for diagnostics and frequency domain analysis of bearing performance. Furthermore, magnetic bearings require backup contact bearings in case of a power loss. Dedert found these systems difficult to maintain. Similarly difficult was getting buy-in from the end use operators, who disliked the idea of a black-box system they can’t maintain in house.
We set to work designing a new atomizer in tandem with Dedert. The New Way team worked closely with Vishal Wadhvani, the lead engineer for the Porous Media atomizer project. “Once we moved beyond magnetic bearings, air bearings were the only option”, recalls Vishal, after evaluating New Way’s products at the 2016 Turbo Symposium.
New Way recommended radial air bearings at the top and bottom of the shaft for radial support, with a thrust bearing for support along the axis of rotation. The bearings are mounted on O-rings surrounding the shaft, providing a degree of compliance to reduce stiffness and damp out any whirl frequencies which may arise in the system. Rotordynamic analysis would later demonstrate only a single backwards whirl mode. Given that backwards modes are typically unexcitable, can be disregarded from a system safety perspective.
For further technical information, the full description of the porous media system and its performance characterization will be presented during the Proceedings of the ASME Turbo Expo 2023.
Dedert’s requirements for a successful bearing system included temperature stabilized operation under operating conditions, 48 hours of continuous runtime without incident and a test for imbalanced operation, which the porous media system met with flying colors at the end of a two year testing campaign.
As with every new technology, this innovation took time. There were a few early crashes of the prototype system. Once the compensation layer was fine tuned, they had a system which was highly resistant to being imbalanced and exceptionally temperature stable. Unlike the active feedback systems required for magnetic bearings, air bearings operate on the principles of the squeeze film effect, meaning Porous Media air bearings are naturally self-stabilizing and highly damped.
The equations required for fine tuning an air bearing system are simply algebraic in nature, so the final customer is fully capable of adjusting their own system for new operating conditions. Even the early crashes were a valuable exercise in the resiliency of Porous Media. Crashing a contact or magnetic bearing system is catastrophic. Meanwhile, crashing a New Way system results in the soft graphite bearing pads absorbing the impact, and only requires replacement of the bearing faces should such an event occur.
While the final atomizer is still under test with its intended client, Vishal had only positive impressions on the final product and the process of working with New Way. “New Way was quick to turnaround replacement bearings and helped pay for the initial crash”, he said, impressed with New Way’s commitment to working with Dedert on bringing this system to market. Vishal continued, “You have to come into this with an open mindset, and understand that you’re working through the innovation in real time. There will be hiccups along the way, but the long term benefits outweigh them”