Achieving Adequate Circulation in Chemical Looping Combustion─Design Proposal for a 200 MW_th Chemical Looping Combustion Circulating Fluidized Bed Boiler

Abstract

Chemical looping combustion (CLC) has unique potential for avoiding the large costs and energy penalties of existing CO 2 capture technologies. Oxygen is transferred to the fuel using an oxygen carrier, thus avoiding contact between air and fuel. Consequently, the combustion products, CO 2 and H 2 O, come in a separate stream, and more or less pure CO 2 is obtained after condensation of H 2 O. CLC is normally conceived as a dual fluidized bed process, with high gas velocities in an air reactor driving the circulation, similar to circulating fluidized beds (CFBs), except that the material is led to a fuel reactor before being returned to the air reactor. Crucial for the process is the properties of the oxygen carrier and that circulation is sufficient to transfer needed oxygen and heat to the fuel reactor. Comprehensive literature shows successful use of many oxygen carriers in sustained pilot operation. In contrast, the need for reaching adequate circulation in an industrial-scale system has been given little consideration. Normally, a system similar to CFB boilers is assumed to give sufficient circulation. However, literature data indicate that circulation in CFB boilers is 5−50% of what is needed. Measures to provide sufficient circulation may cause difficulties, such as erosion or bed material loss in the cyclone. Here, a circulation system based on collection of the downflow of particles along the walls is proposed, and a design of a 200 MW th combined CLC−CFB boiler based on this principle is presented. Further, operational strategies and the need for flexibility are discussed. The design is focused on making an industrial-scale demonstration boiler, which can be used in CLC operation with different oxygen carriers and different fuels and that can explore different operational strategies to find optimal conditions. It is recommended that the upscaling of the technology aims directly at the industrial scale.

Fate of NO and Ammonia in Chemical Looping Combustion─Investigation in a 300 W Chemical Looping Combustion Reactor System

“…Thus, the effect of the temperature, circulation, and fuel flow could not be assessed. (2) This also means that, in contrast to LD slag, there was no oxidation to NO for the cases when CO was zero.…”

Hydrotalcite-Derived Copper-Based Oxygen Carrier Materials for Efficient Chemical-Looping Combustion of Solid Fuels with CO2 Capture

“… 7 , 12 , 13 These investigations have shown that CLC provides an efficient and cost-effective method for the combustion of gaseous fuels with inherent capture of CO 2 . 14 …”

“…The CLC process implicitly reduces the energy penalties of separating CO 2 and other products associated with a traditional air-based combustion. This technology for the combustion of gaseous fuels, particularly natural gas, has been an active research area for the last two decades. ,, These investigations have shown that CLC provides an efficient and cost-effective method for the combustion of gaseous fuels with inherent capture of CO 2 …”

“…7,12,13 These investigations have shown that CLC provides an efficient and cost-effective method for the combustion of gaseous fuels with inherent capture of CO 2 . 14 Given the vast abundance of solid fuels (coal, petroleum coke, biomass, etc.) and their importance in the generation of electrical power, it is highly attractive to apply CLC to the combustion of solid fuels for CO 2 capture.…”

Precursor engineering of hydrotalcite-derived redox sorbents for reversible and stable thermochemical oxygen storage

“…This technology uses gasphase O 2 , generated by metal oxides such as those of copper, to react with the solid fuel directly, through comparatively fast solid-gas reactions. In the past two decades, pilot megawatt-scale CLC reactors have been developed [22][23][24][25] , showing great promise for industrial scale decarbonization.…”