Institute for Combustion Science
Application of a Circulating Fluidized Bed Process for the Chemical Looping Combustion of Solid Fuels has been funded by the Department of Energy: It has been recently proposed that pure CO 2 sequestered from flue gas can be stored in used oil and gas fields, in coal beds for oil or methane recovery, in aquifers, in deep seas and sea bottoms. In a conventional combustion system, fuel and air directly mixed and burned, give rise to the low partial pressure of CO 2 in the presence of contaminants. This is the main limitation to controlling CO 2 emission and will create a significant energy penalty. Among the available or proposed technologies involving CO 2 purification, chemical looping combustion is the most promising technology to combine fuel combustion and pure CO 2 in-situ, which is easily followed by CO 2 sequestration. The process uses a solid oxygen carrier to transfer the oxygen from the air to fuel. The oxygen carrier is recycled as a fuel reactor (reducer), where it is reduced by the fuel, and as an air reactor (oxidizer), where it is oxidized by the air. The air is never mixed with the fuel, so the CO 2 does not become diluted by the nitrogen of the flue gas.
The objectives of the proposed project will be to develop and evaluate a novel concept of the application of a CFB system and a moving bed to the CLC for solid fuel. The project goals are as follows:
- To understand the mechanisms of the chemical looping combustion of solid fuel.
- To establish a theoretical frame of reaction enthalpy, chemical equilibrium and chemical reaction kinetics for three reaction units including an air reactor, fuel reactor and solid separation reactor.
- To establish and evaluate the concept of a CFB chemical looping combustor for solid fuel.
- To establish guidelines for the selection and evaluation of suitable oxygen carriers based on the technical concept of the chemical looping combustion of solid fuel.
- To obtain the basic parameters and information for calculation of mass and energy balances and system pressure balance.
To find technical approaches for solving technical problems involved in the chemical looping combustion of solid fuel, the compatibility of three units combined in the process, and the prevention of possible interactions between the ash and oxygen carriers.