Piróliose dos finos do xisto em reator de leito fluidisado-deslizante

Abstract

It was designed, built and set up a solid-fluid reactor to operate at high temperatures. The aim was to study the oil-shale pyrolisis and the combustion of the pyrolised oil-shale. First, the reactor’s thermal characteristic was studied by establishing the longitudinal temperature profile for different gas and heat flow rates. The loading of oil-shale was kept constant. It was observed an isothermal profile in the reaction zone, but, an highly non iso-thermnal profile in the collecting zone. Furthermore, the hydrodynarnic behaviour was studied at high temperatures for different gas flow rates. It was found that for space velocities s > 4, the spouted material out of the reactor is pronounced by increasing the space velocity. It was performed a set of experiments, by doing the oil-shale pyrolisis for temperatures between 450ºC and 550ºC and gas flow rates between 450 cm³/s and 1800 cm³/s. The material loading was 200g for all the experiments and its sieve size -8+14#. For each experiment the weight loss of the pyrolised oil-shale in the reactor and the spouted material out of the reactor collected in the cyclones were determined. Using a method of analysis, the volatile material of the oil shale was determined. Comparing these preliminary experimental results with the amount of volatile material observed by experiments at 650ºC from the kinetic studies of the oil-shale pyrolisis in a thermobalance, it was determined the efficiency of the reactor. Its efficiency is between 77% and 87%. It was also developed a theoretical model assurning the existence of a spherical penetration front which varies with time, assuming a zero order reaction at the penetration front and the mass transfer in the gas phase. It is assumed a reactor with batch characteristics for the particulated phase. It was observed that the concentration profile in the gas phase increases to a maximum with time. The mass transfer resistance in the gas phase and the penetration front velocity depend on the reaction rate constant and on the space veloci-ty. From the experimental results of the oil-shale pyrolisis we come to the conclusion that the mass transfer resistance in the gas phase is negligible because of the high contact between thegas and the solid phase.