Activity of the Main Reaction

Starting from process temperature (Tp), the reaction is accelerated by the temperature increase to MTT following Arrhenius Law. But, at the same time reactants are converted, which results in a depletion of the reactant concentration and consequently in reduction of the reaction rate. Thus, two antagonistic factors play at the same time acceleration with temperature and slowing down by the reactant depletion. Both effects may be summarized in an acceleration factor (facc) that multiplies the heat release rate. Thus  

In this equation, the conversion term for a first-order reaction (1-X) is expressed as a function of the characteristic temperature levels of the scenario. First-order is a conservative approximation, since for higher reaction orders the reactant depletion is even higher. Zero-order would even be more conservative, but is generally unrealistic. 

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