Application of a Circulating Fluidized Bed Process for the Chemical Looping Combustion of Solid Fuels

75109-The sequestration of carbon dioxide (CO2) ¿ in used oil and gas fields, in coal beds for oil or methane recovery, in aquifers, in deep seas and sea bottoms ¿ requires that the CO2 be of relatively high purity. This presents a problem with the sequestration of CO2 from flue gas. In conventional combustion systems, fuel and air are directly mixed and burned, giving rise to low partial pressures of CO2 in the presence of contaminants. Among the available or proposed technologies for CO2 purification, Chemical Looping Combustion offers the most promise. The process uses a solid oxygen carrier to transfer oxygen from the air to the fuel. In this project, the oxygen carrier will be recycled as a fuel reactor (reducer), where it will be reduced by the fuel, and as an air reactor (oxidizer), where it will be oxidized by the air. Thus, air is never mixed with the fuel, the CO2 does not become diluted by the nitrogen in the flue gas, and CO2 sequestration can easily follow. Phase I will investigate possible processes and establish a novel concept for a circulating fluidized bed Chemical Looping Combustor for solid fuels. Commercial Applications and Other Benefits as described by the awardee: A Chemical Looping Combustion process for solid fuel should efficiently produce pure CO2 that is ready for sequestration. As a second benefit, reducing CO2 emissions would prolong the use of coal in advanced combustion technologies. Third, other pollutants emitted during coal combustion, such as sulfur oxides and trace metals, can be efficiently controlled because of the very low volume of nitrogen-free flue gas generated in the reducer. Finally, NOx formation can be nearly eliminated.