TECHNO-ECONOMIC MODEL OF A NOVEL BIODRING PROCESS FOR THE DRYING OF PULP AND PAPER INDUSTRY MIXED SLUDGE AND ITS EFFECT ON THE EFFICIENCY OF A FLUIDIZED BED BODLER

摘要

The Pulp and Paper (P&P) industry of North America has examined a range of sludge disposal techniques, including combustion using a fluidized bed boiler. The novel biodrying process considered in this study uses forced aeration and biological heat to dry the sludge in order to improve its heating value. This paper explores the economic viability of this biodrying process. To this end, a techno-economic model is presented that systematically considers costs and revenues in the context of a model of a fluidized bed boiler efficiency, in regards to the moisture content of the feed. The model is applied to three case studies of eastern Canadian mills and compared to rotary dryers. Results show that a payback period of less than two years is possible. Biodrying is an interesting step prior to combustion to add value to the mixed sludge. This process is particularly interesting for mills that have problems with combustion stability and that wish to reduce their fossil fuel consumption.