Detailed Product Description
Sealing Retrofit for 903 Bowl Mills of 210 Mw thermal power station
Bowl mills used for pulverising raw coal, use a combination of rotating Dust Guard and stationary Air seal Housing, to provide sealing to the gear box and anti friction bearings of the 903 Bowl mill. This combination gives satisfactory service, as long as the dust guard assembly is held integral with the main vertical shaft of the Mill. For various reasons, the dust guard falls apart, with out rotation, giving opportunity for dust ingress to enter the Mill gear box.In later design, a combination of Mechanical seal is provided to ensure leak-proof sealing to the mill gear box, and this feature has been adapted for these mills. However, there are many more mills in operation, with dust guard and seal air housing combination, requiring attention, and better sealing from ash and coal dust. The sealing arrangement was studied and a new sealing design was evolved with Mechanical sealing features, using the available space constraints of dust guard cover and Air seal housing. In addition the seal flow was well distributed through equally- spaced, radial sealair entry ducts, flushing seal air uniformly around the annular space, between rotating dust guard cover and the stationary Air seal housing.This Sealing Retrofit with Mechanical sealing features, was tested in the laboratory for its performance. Excellent results were obtained, and the Sealing retrofit can be used in such mills under operation, requiring additional mechanical sealing features.
Axial section of the 903 Bowl mill is shown, where the existing sealing arrangement, and the modified sealing with mechanical sealing features are brought together for comparison. Photographs of the Sealing Retrofit undergoing test in the laboratory is shown. The Air seal Housing with radial air pipes and Air header assembly is shown. The instrumentation for air-pressure measurement, showed no leakage of Air Seal Housing inside pressure, during test. This proved the Retrofits performance as a Mechanical seal,with the existing dust guard cover and Air seal Housing combinations in 903 Bowl mills.