Grinding and combustion characteristics of woody biomass for co-firing with coal in pulverised coal boilers

Abstract

This paper presents results of grinding experiments and development of woody biomass mill for co-firing in pulverised coal fired boilers. Woody biomass co-firing with coal is already realised since it can be easily handled as a carbon–neutral fuel. Three steps have been carried out to understand the grinding and combustion characteristics of woody biomass. A suitable mill type for woody biomass grinding has been sought in laboratory-scale experiments. The selected industrial-scale mill has been modified to increase the capacity.The objective of this experimental study is to establish and demonstrate the woody biomass firing system including mill and burner for pulverised coal fired boilers. Both, laboratory- and industrial-scale measurements, provide good understanding of woody biomass grinding and firing performance. The proper burner arrangement is found by use of Computational Fluid Dynamics (CFD) to maintain high burnout efficiency in the boiler. The study proves that the proposed mill and burner positioning is promising to utilise woody biomass with high co-firing ratio. The combination of furnace experiments and CFD modelling results in a satisfying specification of a co-firing system for woody biomass with pulverised coal in sufficient ratio whilst reducing CO2 emissions.