Medupi Power Station is one of South Africa’s most strategic power generation assets and is crucial for the sustained reliability of the country’s grid. EnFloTech not only values this asset but has also made a strategic commitment to help address the power crisis in South Africa. Consequently, undertaking ambitious projects to assist Eskom in enhancing Medupi’s reliability is of paramount importance to EnFloTech. One such project is the development of the split loading frame.
Background
Medupi Power Station is equipped with MPS 265 vertical spindle coal mills, the largest in the Eskom fleet, each capable of producing 110 TPH. Consequently, the components of these mills are large and heavy, making their availability and reliability crucial for the overall availability of the mill plant. This, in turn, has a significant impact on Medupi Power Station’s energy availability factor (EAF).
Some of these components, including the loading frame, were designed for the plant’s entire lifespan, making them non-routine replacement items. Consequently, the ergonomic design of the mill makes it difficult to remove these components easily. Removing the loading frame from the mill requires significant deconstruction of part of the boiler plant, which is costly and time-consuming. This not only strains taxpayer funds but also risks reducing the EAF.
Problem at Medupi
The loading frame is subjected to high-velocity pulverised coal, which is extremely abrasive and causes premature wear, risking its useful life and mechanical integrity. Combined with the limited ergonomic design, this presents a significant problem given the cost, lead time, and threat to the plant’s reliability.
Our Solution for Medupi
EnFloTech embarked on a design initiative to reconfigure the solid one-piece (A-frame) loading frame by dividing it into three segments. Each segment weighs approximately 4 tonnes. Given that this loading frame is the central structure transferring the hydraulic grinding force to the mill, the design team faces a mass constraint, with the total frame allowed to exceed 12 tonnes.
Designing a split joint capable of withstanding the significant fluctuating forces inside a mill, supporting its own mass, and being small enough to fit through the mill’s service door was quite challenging. Extensive first-principle design calculations, combined with Finite Element Analysis (FEA), resulted in a final design that meets weight limitations and offers a loading frame with a 47% increase in the safety factor against fatigue failure under the worst-case operating scenario.
The loading frame is currently being manufactured and is estimated to save Medupi Power Station at least three months of mill unavailability, along with significant primary and secondary costs. This is yet another example of EnFloTech’s commitment to helping Eskom eliminate load shedding threats.
