Modeling of Mercury Desorption from Activated Carbon at Elevated Temperatures Under Fluidized/Fixed Bed Operations

摘要

The most effective method for trace mercury emission control is to employ activated carbon (AC) to adsorb mercury from the combustion flue gas. An environmental concern regarding the activated carbon mercury control process is the low sorption capacity. The mercury control practice, therefore, will need a large quantity of fresh AC and generate an equally large quantity of spent AC contaminated with various forms of mercury. A practical solution to this problem is to regenerate the AC for reuse. In this study, an activated carbon mercury sorption/desorption model was developed for simulating the mercury desorption process at elevated temperatures under both the fixed and fluidized bed conditions. The developed model, which involved the coupling of a kinetic model based on mass transfer and surface equilibrium mechanisms and a tank-in-series approach for material balance consideration, had only one parameter to fit. For desorption simulations, the experimentally observed mercury adsorption data were first involved to best-fit the model parameter and the parameter-fitted model was then used to simulate the mercury desorption profiles under various conditions. The simulation results have indicated that both the desorption temperature and the fluidization condition affect significantly the mercury desorption rates.