Gasification kinetics of char from olive tree pruning in fluidized bed

摘要

The gasification rate of char from olive tree pruning was measured in a fluidized bed at temperatures between 760 and 900 ℃ Experiments were carried out using gas mixtures containing H_2O, CO_2, H_2, CO and N_2 in various proportions. Two kinetic equations were obtained, one for the char gasification rate with H_2O, taking into account the inhibition effect of H_2, and another for gasification with CO_2, including the inhibition effect of CO. The kinetic expressions account for the effect of temperature, gas composition, and the extent of carbon conversion. The influence of the gas composition and temperature was expressed by the Langmuir-Hinshelwood model, whereas an nth order kinetic model was used to account for the variation of the reaction rate with the extent of conversion. The reaction rate with H_2O was observed to be 3-4 times faster than that with CO_2. Inhibition effects caused by CO and H_2 were significant. It was found that the gasification rate in a mixture containing CO_2 and H_2O simultaneously can be estimated from addition of the individual rates with CO_2 and H_2O.