DESIGN MODIFICATIONS FOR THE NEW ECONOMISER INSTALLATION AT INVICTA MILL

INVICTA SUGAR MILL boiler No. 3 was upgraded in 1997 to improve thermal efficiency and allow optimum operation of the 39MW turbo alternator. Part of the upgrade included the installation of an economiser. Since then the economiser has been replaced twice due to dew point corrosion, localised corrosion and high velocity erosion. The lifespan of each economiser was about 8 years, which included at least one crushing season with the bottom bank being bypassed. This paper covers seven main design changes that were implemented at Invicta to address the previous issues with economisers. The changes are expected to significantly increase the life of the economiser, improve gas flow distribution through the air heater and economiser and provide more options and simpler solutions when the economiser is approaching the end of useful life. Inspection following the completion of the 2014 crushing season shows promising results.