Analysis of the possibility of landfill gas use as additional fuel for combustion of solid municipal waste with different moisture content

Abstract

The paper suggested the calculation method of combustion for solid and gaseous fuel cofiring. The calculation is suggested to carry out for per unit of generated during combustion total capacity instead of per unit of weight or volume of fuel. This method was tested during combustion parameters examination at cofiring of solid municipal waste, which is the main fuel, and landfill gas (biogas) which is the additional fuel for thermal mode stabilization. The calculation has been conducted for waste with the moisture content of 50%, 30% и 10%, which are solid fuel, methane, as a reference fuel, common biogas with a methane content of 60%, and biogas with a low methane content of 35%. It was established that additional input of biogas is effective for the combustion of unprepared waste with high moisture content, moreover, it is possible to use common biogas as well as biogas with low methane content. The required combustion product temperature (900-1000°C) for unprepared waste can be achieved at the excess air coefficient of 116 or more. In summary, solid fuel and biogas cofiring allows operative control of the combustion process and sustain combustion product temperature and heat output of units at a constant level. The combustion process regulation should be based on the given temperature of combustion products by changing two parameters: landfill gas flow rate and flow rate of air supplied for combustion.