Modelling of a plasma reactor for the synthesis of calcium carbide

Plasma synthesis of calcium carbide was investigated using calcium oxide and graphite powders. A semi-batch spout-fluid bed reactor with a DC plasma torch was used for the study. Argon was used to initiate the plasma and hydrogen gas was then added to increase power and raise the plasma jet enthalpy. Experimental results showed that the reactor consisted of two different zones : a high temperature reaction zone and a well mixed isothermal bed zone. The size of the reaction zone and the particle flow rate into the jet depended on the net plasma power. The reaction rate was correlated by a shrinking core, reaction control model and showed excellent fit for conditions where hydrogen was present in the plasma gas and heat transfer limitations were negligible. The apparent activation energy of the reaction was determined to be 377 kJ/mol (90 kcal/mol). Extrapolation of the reaction model and the experimental results indicated that a plasma fluid bed process could be a technically viable and a more efficient alternative for the production of calcium carbide.