Fluidized Bed Apparatus for High-Temperature Sorption of Carbon Dioxide

Abstract

The study focuses on the measurement of carbon dioxide sorption via carbonate looping process realized in the home-made laboratory fluidized bed apparatus. The sorbents tested comprise fly ash containing high concentrations of Ca²⁺ present in a form allowing, under the given conditions, a heterogeneous reaction with CO₂. Of 35 samples of fly ash from various power plants, the sorption properties of which were verified outside the scope of this paper, two were selected for the description. The main aim of the study was to evaluate the effect of temperature on the achieved sorption capacity and on the sorption rate. Sorbed and desorbed carbon dioxide was detected by infrared spectrometry. Sorption was measured under isothermal conditions in the temperature range of 580–710 °C. The highest sorption capacity in combination with higher sorption rates maintained for a longer period of time was achieved at the temperature of 680 °C. Before and after the sorption tests, the samples were characterized by X-ray fluorescence spectrometry, X-ray diffractometry, and specific-surface-area and pore-volume measurements. It was confirmed that the proposed apparatus allows evaluating the sorption properties promptly and with a good reproducibility. The results show that fly ashes from combustors applying the dry desulphurization method can be used to capture CO₂ from flue gas without the need for chemical treatment before this application.