June, 2005
Vol 1 Chapter 34: Development of Oxygen Carriers for Chemical-looping Combustion
Juan Ada´nez, Francisco Garcı´a-Labiano, Luis F. de Diego, Pilar Gaya´n, Alberto Abad and Javier Celaya
Abstract: The objective of this work was to develop oxygen carriers with enough reduction and oxidation rates, resistant to the attrition and with high durability, maintaining the chemical, structural and mechanical properties in a high number of reduction–oxidation cycles, to be used in a chemical-looping combustion (CLC) system. A significant number of oxygen carriers, composed up to 80% of Cu, Fe, Mn or Ni oxides on Al2O3, sepiolite, SiO2, TiO2 or ZrO2, were prepared by different methods, and tested in a thermogravimetric analyser (TGA) and in a fluidized bed. Based on data of rushing strength, reactivity, attrition, and agglomeration of the carriers and its variation during successive reduction–oxidation cycles, the three most promising oxygen carriers based on Cu, Fe, and Ni were selected and prepared to be tested in a pilot plant. The effect of the main operating variables, such as temperature, gas composition, gas concentration, etc. on the reduction and oxidation reaction rates were analysed in a TGA to determine the kinetic parameters of the selected carriers. A heat balance in the particle showed that the particles can be considered isothermal when using small particle sizes, as it would be normal in a CLC process. The reduction reaction rate of the oxygen carriers with CH4 was controlled by the chemical reaction, meanwhile the oxidation reaction rate was controlled by the chemical reaction and the diffusion in the product layer. Finally, the kinetic parameters obtained for the selected oxygen carriers were included into a mathematical model to describe the behaviour of these particles in the fuel reactor of a CLC system.
Carbon Dioxide Capture for Storage in Deep Geologic Formations – Results from the CO2 Capture Project Capture and Separation of Carbon Dioxide from Combustion Sources - Volume 1
Edited by: David C. Thomas, Senior Technical Advisor, Advanced Resources International Inc, USA
(451 Kb) Download
