A major UK power plant urgently invited Vulcan for a site visit to investigate a leakage on a large Duechting® ROWA-MCC recirculation centrifugal pump.
After disassembly of the pump and careful examination, the cause of leakage was due to the springs being clogged by the media, and therefore the sealing faces were no longer able to achieve true alignment.The pump’s seals had been running for 5 years but due to the size of the pump and level of leakage, the original seal supplier was not willing to offer their help – which is when Vulcan was asked to step in.
The pump, one of 20 in the array, each with 580kW electric motors, was being used as part of the process to remove sulphur dioxide from coal using limestone slurry, at a temperature of approximately 80°C. Given the abrasive nature of the media, the reliability of the seals is a good indication of the robust nature of the pump and the suitability of the seal design. However, with such size and engineering comes cost. With the typically high costs of repair and replacement from the pump OEM, the plant’s chief engineer was motivated to seek alternative sources and Vulcan were the only seal supplier to provide the right answers and quotations.
Vulcan prepared production drawings from used parts provided by the chief engineer, along with drawings for various other bespoke seals that they had also approved for us to design. As part of the process, we took the opportunity to improve the design of the drive/anti-rotation pins compared to the OEM parts, while also ensuring no modifications would be required on the pump as a result.
Using our advanced manufacturing capabilities in Sintered Silicon Carbide, we produced the first seal for their evaluation. The seal is the largest manufactured by Vulcan to date, suiting a shaft sleeve size of 250mm, with a face operating diameter of 294mm.
The seal features Sintered Silicon Carbide faces on both the rotary and stationary seals, as well as a UHMWPE (ultra-high molecular weight polyethylene) stationary seal retainer with 36 springs.
The seal was installed in December 2016 and is running successfully with no report of leakage, and is expected to achieve far beyond the specified service lifetime of the original seals.
Vulcan are able to design and manufacture custom mechanical seals to meet your specific requirements. For more information on what services we can provide you, please contact your dedicated account manager or use the contact form on this page, detailing your requirements.
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