IMPACT OF BIOMASS CO-FIRING ON UNREACTIVE COALS IN PULVERISED FUEL COMBUSTION

摘要

Utilization of coal in the power generation market has been predicted to increase substantially over the coming decades, with higher efficiency production and clean technologies providing a low carbon energy market. An increase in coal combustion will lead to the necessity for burning more low rank and unreactive coals that produce high quantities of waste ash consisting of high levels of trapped carbon. The potential to release this trapped carbon by co-firing with biomass is an attractive option that would lead to lower emissions and higher energy outputs. The aim of this research is to determine to what extent additions of biomass can increase volatile yields, thus reducing ignition temperature, and improving char burn-out for a selection of unreactive bituminous coals. To achieve; a range of industrially relevant biomass fuels have been co-fired with coal in both fast and slow heating rate experiments at a blend ratio of 50:50 weight%. Slow heating rates were experienced by fuel blends undergoing Thermogravimetric Analysis (TGA), whilst fast heating rates, comparable to power generation conditions, were achieved using a Drop Tube Furnace (DTF) rig. This paper focuses on the volatile matter yields produced from both process and whether a synergistic effect was observed. The outcomes from the slow heating rate experiments show an additive relationship with no synergistic effects occurring, whilst fast heating rates generally gave an increase in volatile matter yield. The greatest increase in volatile matter yields occurred during co-firing of high moisture woody biomass thought to derive from steam gasification induced by the moisture released, wood pellet increases of 12%-21% and raw bagasse increases of 7%-12%.