Recovery Boiler Retrofit With Fluidized Bed Technology, 1998 Engineering Conference Proceedings

Retrofit of existing boilers to a fluidized bed configuration is a lower cost option to provide continuing service in plants that must change their process to fit environmental or market constraints. Boilers are designed for long term operation tiring specific fuels. While process changes may eliminate the fuels, inactivating the boilers, mechanically they may be in perfect condition and suitable for years of additional life. If plant steam requirements still exist, retrofit of the boilers to fire available fuels is an option that should be explored.

This paper deals with the retrofit issues of a black liquor recovery boiler at a paper mill in the throes of eliminating its pulping process and switching to 100 percent recycled fiber. The objective was to analyze the existing equipment for long term serviceability and establish the economics of fluidized bed retrofit allowing combustion of paper sludge as an option to landfill. Challenges to be met included access to the existing equipment for reconfiguration and addition of new environmental equipment to meet new source standards utilizing available space. Project cost was weighed against landtill and auxihary fuel costs for steam generation to develop a retrofit configuration and fuel firing scenario that would save the company money.