Special Focus: Wear Protection
Fig. 3. Vertical Roller Mill grinding being wearface protected. Automated welding in situ.
VRMs repair In the 1970s, Vertical Roller Mills (VRMs) became increasingly dominant for grinding raw materials mainly in the power industry due to their high energy efficiency and excellent drying capacity. Te VRM components are subjected to severe wear and this wear can increase dramatically when high silica content is found in the raw materials. Consequently such wear problems can influence significantly the profitability of a plant. During the last decades, together with our partners we have proved that preventive maintenance on VRM can extend the critical component lifetime by
as much as 100 per cent. Tis is done with automated weld overlay of the rollers and the tables, plus use of CDP wearplates on house and rotation parts. Such maintenance operations have been performed on over 60 units, with 80 per cent being on-site repairs but also many repairs in our workshops. More than 30 different VRM models have been weld overlaid for more than 20 companies throughout the world. From small VRM (roller: 1.65m Ø and table: 2.75m Ø) to massive ones (roller: 3.2m Ø and table: 5.5m Ø), we have been successful working on equipment from Polysius, Loesche or FLS and Raymond. Together with the R&D department, the VRM team has developed special anti-wear products providing unbeatable resistance to abrasion, impact and erosion. Te new TeroMatec wire EO 8338 (open arc wire) which provides an extra smooth surface but an extremely resistant coatings. In one recent application in the Middle East this new EO 8338 wire was able to reduce wear on the rollers from 9 grams per ton crushed to 3 grams when build up 40 mm thickness on a four roller system.
Conclusions Castolin Eutectic’s thermal power plant repair service package includes: products to solve wear problems; on- site and in-workshop refurbishment; increased service life over conventional welding alloys; environmental ethic values; fast and effective return to service; alloy development and in-house manufacturing. ●
Enter 66 or ✔ at
www.engineerlive.com/ipe Dr Gary R Heath is Chief Technology Officer, Castolin Eutectic, Lausanne Switzerland.
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