A numerical model for biomass and solid recovered fuel combustion on a reciprocating grate

摘要

The thermal conversion of biomass and solid recovered fuels has gained increasing interest in the recent efforts to reduce GHG emissions and to provide sustainable energy sources. Worldwide, experiments have been performed at laboratory and pilot plant scale to characterize the burning behaviour of these fuels and to collect data needed for industrial applications. At KIT, the fixed bed reactor KLEAA (10 1 volume) was used to measure characteristic numbers like ignition rates, reaction front velocities and mass conversion rates for several fuels. In addition, some fuels were burnt on a pilot scale pusher grate (TAMARA, 0.5 MW_(th)). The results from the fixed bed reactor were found to be compatible with results of the grate combustor. Also, a mathematical model (KLEAA - code) was developed which simulates the relevant physicochemical processes (drying, pyrolysis, gas and solid combustion) by a one dimensional porous bed approximation. The model results compare well with the fixed bed experiments and, the KLEAA-code was extended to cover the situation of forward acting grate combustors. In this paper, the recent updates of the KLEAA-code are described, a comparison of calculations with TAMARA experiments is presented and, first results of coupling the KLEAA-code with CFD calculations are shown.