Numerical simulation of combustion characteristics of municipal solid waste pyrolysis gas in a rotary hearth furnace

Metallurgical dust and sludge are important secondary resources, and the rotary hearth furnace (RHF) is currently one of the most widely used technologies for its treatment. This study proposes a novel approach of utilizing pyrolysis gas derived from municipal solid waste as a substitute for conventional mixed gas as the fuel in RHFs. This strategy not only facilitates the disposal of urban waste but also contributes to carbon emission reduction in RHF operations. This work employs CFD model to study the combustion characteristics and CO 2 reduction potential of pyrolysis gas in the RHF. The model was validated by comparing the simulated temperature distribution during mixed gas combustion with actual plant data. Subsequent simulations were conducted under two fuel configurations: equal fuel flow rate and equal air flow rate. The results show that under the equal fuel flow rate condition, a 20% pyrolysis gas ratio yields a temperature profile is close to that of mixed gas combustion, while achieving a 53% reduction in CO 2 emissions. However, this solution also causes an 18% increase in the total flue gas volume. Conversely, under the equal air flow rate condition, an 80% pyrolysis gas ratio maintains a comparable temperature to that of mixed gas, while reducing total flue gas volume by 22% and CO 2 emissions by 63%. Moreover, partial replacement of mixed gas with pyrolysis gas in the reduction zones I to III demonstrates favorable temperature distributions and significant CO 2 emission reductions under both fuel structures.