Experimental and Numerical Analysis of Carbon Black Formation in Hydrocarbon/Air Diffusion Flames

Carbon black has been widely used in industry, especially in rubber and plastic production. The present study is concerned with measuring and simulating the carbon black formation process in Propane-air and Acetylene-Air diffusion flames. The carbon black concentrations in the furnace have been measured by means of a soot pump and gravimetric method. The flue gas analysis is also done by means of Testo XL-350 Gas Analyzer. The numerical predictions are carried out with the CFD code, Fluent. The chemical reaction formulation relates the production of the carbon black to the incomplete combustion and pyrolysis of propane and Acetylene as both the main gas and the feedstock. The effects of feedstock mass flow rate, the position of feedstock injection, the feedstock material and the shape of the furnace on carbon black are studied. The results show the effect of temperature on soot and carbon black formation in which as the temperature increases the soot and carbon black mass fraction is also increased. The results also show that as the feedstock mass flow rate increases the formation of the carbon black is increased up to point where the mass flow rate of feed stock is three times greater than the mass flow rate of the main gas and after that the carbon black production rate starts decreasing because of the decreasing of temperature due to cold fuel injection to the furnace. The position of feedstock injection affects the mixing process of air and fuel, and complete mixing causes the temperature to be increased. The injection of feedstock in the pre-combustion zone influences the maximum of the flame temperature. As the hydrocarbon initially pyrolyzes to acetylene and afterwards acetylene breaks into soot and carbon black in the present study acetylene is used as feedstock, the results show huge increasing of soot and carbon black mass fraction in the products. The results also show that predictions and the experimental measurements are in good agreement.