Reducing boiler maintenance costs and deferring capital expenditure through improved technology : final report 2016/020
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Boiler tube wear and corrosion costs the industry approximately $5 million a year in repairs, stops and inefficient operation. For example, the replacement cost of one convection bank due to wear is approximately $1 million with a tube life of approximately 10 to 15 years using current protection technology (tube shields). Given that most boilers in the industry are more than 30 years old and that the high capital cost of new boilers will result in very few replacements, nearly all existing boilers will operate into the foreseeable future. As these boilers age, the wear and corrosion costs are likely to increase. Tube coatings have been successfully applied in other industries and are expected to be equally beneficial to sugar mill boilers. The application of tube coatings is expected to become a viable alternative to tube shields and significantly reduce wear and corrosion of boiler tubes in convection banks, air heaters and economisers.An extensive investigation of options for reducing the maintenance costs of and deferring capital expenditure associated with sugar factory boilers has been carried out in this project. This investigation found that the most promising coating for erosion resistance is the WearPro 62 coating applied by laser process and the next most promising option is the SAE 420 coating applied by TWAS (twin wire arc spray). The promising options for extending the life of air heaters are the S-TEN 1 and SS304 stainless steel tube materials which have significantly greater resistance to dew point corrosion than carbon steel.