The Validation of a Calculation Model for Biomass Combustion Using CO₂ Measurement

Abstract

This paper presents a calculation model for obtaining specific volumes of flue gas and air from biomass combustion. The main goal of the presented work is the evaluation of the accuracy of the model in relation to the actual combustion process. Since the model allows calculation of concentrations of flue gas components, the validity of the model was evaluated by measuring the actual CO₂ concentration. In total 10 various kinds of biomass fuels were used for combustion experiments, including wood, waste, and agricultural biomass. The tests were performed in a commercially available small-scale boiler which provided CO₂ concentrations in precisely defined conditions. Generally, the measured and calculated concentrations differed approximately from −9% to +2% relatively. The performed correlation analysis shows that the calculated values correlate with the measured values with a 95% reliability. The analysis also shows a 65% correlation of the relative deviation of the calculated and measured concentrations with the carbon monoxide concentration as a measure of incompleteness of the combustion process. On the other hand, no correlation was found between the relative deviation between the CO₂ concentrations and the operation mode of the boiler, represented by the percentage of the nominal capacity of the boiler. The last evaluation was focused on the influence of the excess air ratio on the relative deviation, in order to find a possible influence of flue gas dilution on model reliability. Also in this case no correlation was found.

Keywords:

• Biomass
• Combustion
• Calculation model
• Flue gas

Additional information

Funding

This work was supported by project MSM6840770035 “Development of environmentally friendly decentralized energy systems,” which is gratefully acknowledged.