Modeling of hydrogen blending natural gas combustion characteristics and emission analyses in industrial burners

Clean energy-based heat demands have increased interest in environmentally friendly fuels such as hydrogen for industrial decarbonization applications. In the present study, the combustion characteristics of a 150 kW natural gas process burner, which is widely used in different industrial processes such as direct firing, heat treatment, melting, drying, etc., were investigated under different hydrogen mixture ratios (0 %, 5 %, 10 %, 15 %, and 20 %) and air excess coefficients (1.2, 1.3 and 1.4). Experimental studies were carried out with a PLC-controlled test oven system. Numerical simulations were carried out with Fluent codes using methane (CH4) representing natural gas. Three different combustion models (Eddy Dissipation Model-EDM, Non-Premixed Combustion-NPC, and Partially Premixed Combustion-PPC) results were compared to each other. As a result of the comparison of different combustion models, the PPC model for 150 kW heat input, natural gas fueled, and air excess coefficient of 1.2 calculated the most compatible result with the experimental data. Methane gas was used instead of natural gas in numerical studies. Experimental studies were carried out at different air excess coefficients between 1.2 and 1.4 with 150 kW heat input and blended fuel ranging from 0 % H2/100 % NG to 20 % H2/80 % NG. Numerical simulations were made with the PPC combustion model using the same boundary conditions. These studies examined the effects on temperature, velocity, density, pressure, emissions, pollutants, flue gas temperature, flame formation, and stability. Blending 20 % hydrogen into natural gas reduced CO2 emissions by approximately 5.8 %. While O2 emissions remained constant, NO emissions and flue gas temperatures increased. While O2 emissions remained constant, NO emissions and flue gas temperatures increased. In addition, the hydrogen and natural gas fuel mixture improved flame stability, and increased flame temperature, velocity, and pressure; however, the intensity of flame has decreased. As the hydrogen mixing ratio in the fuel mixture increased, the concentration of OH and the formation of NO also increased. In the use of hydrogen-blended fuels, higher air excess coefficients were required to release low NO emissions. As a result of the study, it was determined that process gas burners with diffusion flame characteristics can be safely operated with a blending of natural gas and up to 20 % hydrogen in accordance with safety guidelines in the operation of lowpressure applications and that this technology offers significant potential for industrial decarbonization.