Estimation of reaction vessel volume for a fixation furnace in the pyrolysis and dry-fixation system of SF6 gas

To develop a dry recovery process for fluorides including the decomposed gases of SF6 gas, which has a global warming potential (GWP) of 23,900 times that of CO2, the gas-solid reaction properties of HF gas and calcium carbonate in a fixed-bed reaction furnace were investigated. The experimentally determined reaction zone volume including unreacted calcium carbonate in the fixed-bed reaction furnace was in good agreement with the estimated value from the HF breakthrough curve using the fixed-bed reaction model. Further the HF reaction rate with calcium carbonate could be estimated from an approximate rate formula using the unreacted core model with the mass transfer factors of the solid product layer and the boundary layer at the external surface, and each factor was obtained. By estimating roughly the passage time through the reaction zone in the furnace from the obtained reaction rate formula and these factors, the reaction zone volume, which is needed to design the reaction vessel in the fixed-bed reaction furnace, can be estimated safely.