Co-firing Biomass with Coal in a Tangentially-fired Pulverized Coal Boiler

摘要

This project consists of co-firing biomass with pulverized coal in a 90 MW tiltingtangentially-fired pulverized coal boiler (#1) by utilizing separate injection of thebiomass at a maximum rate of approximately 20,000lb/hr (up to 20% on a heatbasis) for an extended period of time. The biomass will consist of residue from alocal wood manufacturing and dedicated willow bush grown in the Dunkirk area.Currently, the Niagara Mohawk has initiated the planting of over 500 acres ofwillow near the Dunkirk Steam Station. Willow bush can be grown and harvestedon three-year cycles. The SUNY College of Environmental Science and Forestryin Syracuse, NY is currently developing the growth and harvesting strategies forthe willow bush.The objectives of the Dunkirk test program are to: quantify the impacts of cofiringwood waste with pulverized coal by separate injection with respect to boilerefficiency, flame stability, operability and the formation of airborne emissionsincluding SO_2, CO_2, Nox and opacity; demonstrate that the cofiring technologycan be applied to corner fired pulverized coal boilers at moderate percentage;evaluate the economics of cofiring wood as compared to coal and provide abasis for evaluating the infrastructure needed to deliver biomass fuel to DunkirkSteam Station.Tests to evaluate biomass cofiring up to 20 percent by heat of woodmanufacturing waste and willow bush with various moisture and ash contentsand with varying fuel volatility are currently scheduled for late September/October2000. Since the co-firing testing has yet to be performed no results are available.Based on the limited field testing we should be able to conclude that impacts onSO_2, No_x and CO_2 emissions will be favorable. The wood waste is essentiallyfree of sulfur so the substitution of wood for coal should reduce SO_2 emissions.The cofiring tests at Dunkirk Steam Station are expected to be sufficientlyfavorable to support pursuit of a long-term demonstration of this cofiringtechnology.