Statistics matter… 10,000,000,000 lbs. of cement raw materials and 99.75% uptime make the Precision PMCA-60 a Most Valuable Player. Installed at a large cement manufacturing facility in the central USA, the big feeder ran for two full processing seasons – bypassing rebuilding at the annual outage after one-year of operation. After more than 13,000 hours of operation, the feeder was removed from service and replaced with a back-up. The customer then shipped it to Precision Machine and Manufacturing for evaluation for rebuilding.
The plant originally had a triple-gate feeding its raw mill and then switched to a feeder from another manufacturer approximately ten years ago. That feeder was prone to building up sticky material and not feeding consistently. In 2017, the customer began considering a PMCA raw mill feeder from Precision.
The desired throughput at the plant was a minimum of 450 tons per hour of 92 lbs./ft3 raw material with a maximum size of 12” particles. Precision recommended a PMCA-60, which has a capacity of 80 cubic feet per revolution (CFR). The feeder was equipped with a 25-HP drive package, including an auto-resetting Tsubaki clutch. Custom-designed transitions facilitated the easy replacement of the existing feeder.
Plant personnel designed and installed a rail system to facilitate the installation of the PMCA-60, making it easy to move the feeder over to the edge of the platform. The rail system makes it possible to access the feeder with a crane for installation or replacement.
Installation was completed in March 2018 during the plant’s annual outage. The PMCA-60 was operated for 6,250 hours over the balance of 2018, with only 17.5 hours of unplanned downtime. 14.5 of the unplanned downtime hours were due to foreign objects jammed into the feeder, including rebar, refractory brick, a tree branch, and chute liners. The first year’s final results were 99.7% uptime.
In 2019, similarly, impressive uptime statistics were recorded with 6,300 hours of operation and only 15.5 hours of unplanned downtime. 10.7 of these hours were due to foreign objects lodged in the feeder.
Finally, in early 2020, the feeder operated for 760 hours before being removed from service in April. Less than 1 hour of unplanned downtime was recorded that wasn’t attributable to a foreign object.
In total, the PMCA-60 provided 99.75% uptime for the plant over more than 13,000 hours of planned operation.
The spare PMCA-60 was installed in April 2020, and the original feeder was returned to Precision in the summer of 2020 for evaluation for rebuilding. Once disassembled, the internal components of the feeder were found to be in excellent condition. The feeder is an ideal candidate for a factory-rebuild.
A Next-Generation Rotary Feeder
Precision began producing the PMCA raw mill feeder line in 2010. The design objectives were:
Durable construction for long, trouble-free operation
The aim was to design and build a new class of raw mill feeder that was truly Next-Generation with none of the issues that plagued older types of feeders. The goal was to make a step-change in performance and ROI.
In the decade since the introduction, the design and materials of the PMCA feeders have been refined based on customer feedback and the analysis of component wear and feeder performance.
Precision’s commitment to the Lean principles of continuous improvement has led to significant Up-Armoring in several wear points on the endbells and the feeder housing. The design for introducing and directing hot gas through the rotor has evolved as well.
Today’s PMCA raw mill feeder is truly Next-Generation. Maintenance is limited to a few minutes per day; uptime is an impressive 99%+, and every PMCA raw mill feeder that has been sold or rebuilt has run for a minimum of two years without a rebuild.
If your cement plant’s raw mill feeder –
Has to be rebuilt annually
Struggles to handle wet or sticky raw materials efficiently
Is overly well-acquainted with the plant’s maintenance department
It might be time to investigate a durable, reliable alternative that will allow operators and maintenance to focus elsewhere. To begin that investigation, consider these possibilities: