Development of a predictive kinetic model for homogeneous Hg oxidation data

Several researchers have developed kinetic models to predict the effects of various flue gas components on homogeneous mercury (Hg) oxidation. Most of these models make use of over 50 reversible reactions that involve radicals in a combustion or post-combustion system, where temperatures are similar to that of a power plant boiler, in excess of 1700 ∘C. Reaction rate constants are expressed in the form of k=A∗Tn∗exp(−E/R/T)k=A∗Tn∗exp(−E/R/T) where the unknown variables are AA (pre-exponential factor), nn (the exponent of temperature) and EE (activation energy). The focus of this paper is the development of a simple kinetic model to predict experimental data in a laboratory scale apparatus. The results obtained show that only five reactions are required to predict the data obtained in the experimental work. Two of these reactions are reversible and three are irreversible. None of the reactions involve radicals, and only the pre-exponential factor and activation energy values in the rate constant term for the reactions are determined — the value of ‘nn’ is set at 0. It is found that the predicted values correspond very well with the observed experimental data.