MODEL RESEARCH OF COAL AND BIOMASS CO-COMBUSTION IN A LARGE SCALE CIRCULATING FLUIDIZED BED BOILER

摘要

The paper presents a model of the lignite and biomass co-combustion in an environmentally friendly way. Forest biomass, sunflower husk, willow and lignite were used in co-combustion tests, run in a large-scale circulating fluidized bed (CFB) boiler with a capacity of 261 MWe. Experimental studies, calculations and model validation were performed for the CFB boiler. The study was conducted for the four test-run involving different shares and types of both biomass and coal. The percentage of biomass added in the fuel was: 7%, 10% and 15% (as chemical energy) whereas constant heat flux within the fuel fed to the boiler was maintained at 100% load. The coal combustion model previously developed for coal was used. For the purpose of this study, some modifications have been made including new geometry of the system, biomass devolatilization sub-model and new approach to the chemical kinetics description of the co-combustion process. The comparison between measured and predicted by model CO_2, CO, SO_2 and NO_x emissions show, that data obtained by calculation are located in borders of± 20%.