Kinetic Rate Laws of Cd, Pb, and Zn Vaporization during Municipal Solid Waste Incineration

The kinetic rate laws of heavy metal (HM) vaporization from municipal solid waste during its incineration were studied. Realistic artificial waste (RAW) samples spiked with Pb, Zn, and Cd were injected into a fluidized bed reactor. Metal vaporization wastracked by continuous measure of the above metals in exhaust gases. An inverse model of the reactor was used to calculate the metal vaporization rates from the concentrabon vs time profiles in the outlet gas. For each metal, experiments were carried out at several temperatures in order to determine the kinetic parameters and to obtain specific rate laws as functions of temperature. Temperature has a strong influence on the HM vaporization dynamics, especially on the vaporization kinetics profile. This phenomenon was attributed to internal diffusion control of the HM release. Two types of kinetic rate laws were established based on temperature: a fourth- or fifth-order polynomial rate law (r(x) = k(0)e(-EA/RT) p(x)) for temperatures lower than 740 degrees C and a first-order polynomial (r(x) = k(0)e(-EAI/) (RT(q-qf))) for temperatures higher than 740 degrees C.