Sludge Burning in a Circulating Fluidized Bed Boiler, 1994 Environmental Conference Proceedings

James Peterson, Glenn Poulin, Steven Hudson

Boise Cascade’s Rumford, Maine mill is an integrated pulp and paper mill making over 1600 tons/day of coated and uncoated printing and magazine papers. The mill generates approximately 100 tons/day of primary and secondary sludge from the mill’s waste-water treatment plant. Following startup in 1990 of two new 415,000 lbs./hr. circulating fluidized bed boilers, the mill began evaluating the possibility of burning sludge in these boilers to reduce landfill disposal costs, landfill space requirements, and to recover any heat value in the sludge. New screw presses were required to accomplish improved sludge dewatering, and those were installed in 1992. Following the startup of the first screw press in November 1992, a sludge burning trial was initiated.

This paper presents Boise Cascade’s experience with sludge burning in the fluidized bed boilers, evaluates emissions of criteria air pollutants with and without sludge burning, and reviews some of the problems encountered during this project. Graphs are presented illustrating the drastic reduction in the volume of material landfilled following the screw press startup, and conversion to sludge burning. The program to date indicates that the sludge burning project fits well with the mill’s plans regarding waste minimization, pollution prevention, and improved raw material utilization.