A new plasma fluid bed process to replace the present electric arc furnace for the production of calcium carbide has been studied. A thermodynamic analysis predicted that the solid phase reaction would be complete at 2150 K and that the plasma process could lower the energy consumption by up to 40%. A semi-batch fluid bed reactor with a DC plasma torch was used for the study. Calcium oxide powder with a mean particle size of 170 $ mu$m was reacted with two types of graphite, coke and methane. Argon was used to initiate the plasma and hydrogen gas was then added to increase the power and raise the plasma jet enthalpy. The hydrogen concentration in the plasma gas ranged From 33 to 67 (vol%). The experimental results showed that the reaction took place in the plasma jet zone and that the conversion to calcium carbide increased linearly with reaction time. The rate of conversion increased exponentially with plasma jet temperature, indicating that chemical reaction was the controlling mechanism. The reaction rate was correlated to the shrinking core, reaction control model $ rm 1-(1-X) sp{1/3}$ = Kt and showed excellent fit for conditions where hydrogen was present in the plasma gas. The apparent activation energy of the reaction was determined to be 377 kJ/mol (90 kcal/mol). Microscopic analysis of the solid product showed that calcium carbide was formed around both reactants. The surface area of the carbon was found to be an essential factor in determining the rate of formation of calcium carbide. Extrapolation of the reaction model and the experimental results indicated that complete conversion can be achieved within a reasonable time in a plasma fluid bed process. Thus, the new process is technically viable and also a more efficient alternative for the production of calcium carbide.

Munz, R. T. (Supervisor)