Pilot-Scale Investigation of the Influence of Coal−Biomass Cofiring on Ash Deposition

Abstract

Cofiring biomass with coal is a promising short-term option for reducing the net CO2 emissions from existing coal-fired power plants. This paper examines the effects of cofiring biomass and coal on ash deposition under conditions representative of those found in the superheater region of pulverized-coal boilers. Experiments were conducted with blends of eight different fuelsthree types of bituminous coal, sub-bituminous coal, two types of straw, switchgrass, and wood. For each fuel, reference tests of unblended fuel establish a baseline against which to compare the results from the cofiring tests. The deposition rates for the cofire blends are between the measured deposition rates of the unblended fuels. Therefore, blending straw with coal reduces the high deposition rates observed while firing unblended straw, and cofiring coal with wood results in slightly lower deposition rates than those that occur while firing unblended coal. The primary interaction between the biomass and coal during cofiring is the...