AN EVALUATION OF LIMITATIONS OF CO-FIRING BIOMASS IN PULVERIZED FUEL FACILITIES

摘要

In the frame of the European co-funded project DEBCO, advanced co-firing applications of variousfeedstocks have been demonstrated in lab-scale upto industrial scale. This paper reports on the co-firing of higherthermal shares of biomass beyond industrial practices in a 0.5 MWth pilot facility and smaller laboratory facilities.Findings from a large scale demonstration run are also highlighted. Results show that co-firing of biomass up toabout 50% thermal share is manageable. The combustion may be unstable with a thermal share beyond 50%. This isbelieved to be due to the combustion of the biomass volatiles that may delay the oxygen penetration necessary to startthe residual char combustion. The O_2 profile concentrations increased with the increase of biomass co-firing in pilotscale tests, since volatile combustion likely creates a cloud around the char particle. This probably prolonged thecombustion of both the larger biomass particles, as well as the coal char particles. As is shown in the results, thispromotes undesired deposits, likely due to reduced zones that facilitate eutectic compound formations. The 100%thermal share of biomass combustion showed a stable combustion and no problematic deposit formations. However,other occurrences are shown such as alkali salt formations, giving rise to a more possible enhanced fouling problem.