Numerical and Experimental Assessment of a Novel Multinozzle Burner with CO₂ Diluent to Improve the Emissions from a Swirling Flame in a Combustion Chamber

Abstract

As turbulent combustion is commonly used in industrial applications, in this study, a new burner is designed in order to be applied in a test furnace. With the employment of Fourier transform infrared (FTIR) spectroscopy, the species in the flue gas at different ratios of direct secondary air flow and swirling secondary air flow are detected to choose the optimum ratio for the subsequent experiments. An experimental investigation is performed to study the effects on a CH 4 /air swirling turbulent flame while mixing CO 2 with CH 4 as the fuel. The OH-PLIF (hydroxyl-planar laser-induced fluorescence) and FTIR methods were employed to measure the OH distribution and NO in the flue gas separately with the added CO 2 . To study the reaction mechanism and predict the flow, temperature fields, and NO x emissions, numerical modeling works have been performed employing the COMMENT code. The standard k−ε and Reynolds stress model turbulence models are used to describe the turbulent flow. The "eddy dissipation" model (6 species and 2 reactions), the PDF (probability density function) model (β function) (9 species and 8 reactions) with a chemical equilibrium model, and the laminar flamelet model (17 species and 46 reactions) are used for modeling the turbulence−chemistry interaction. The NO x postprocessor is used to predict the NO emissions. The concentrations of the OH and O radicals are obtained by assuming the hypothesis of partial equilibrium and using a PDF in terms of temperature. Several factors influencing the combustion process are investigated. From the experiments, it was found that the OH and NO production both increased first, reached a peak value when the fraction of CO 2 was 25%, and then decreased. The numerical results obtained are compared with the experimental results and the results from previous works, and the experimental and numerical results are found to be in good agreement.

Experimental investigation on emission and combustion characteristics of an industrial burner using biogas co-fired with diesel and biodiesel

“…As the percentage of carbon dioxide in the biogas increases, the carbon monoxide emissions resulting from combustion increase the result of the high concentration of the inert dilution gas CO2, which lowers the flame temperature and impacts on the rate of the reaction that forms carbon monoxide and produces more carbon monoxide emissions. Zhang et al (2019). As shown in Figure 4, the low content of inert gas CO2 in the biogas compositions for B100biogas1 and D100biogas1 reduces carbon monoxide emissions and tends to bring the combustion closer to being complete.…”