Design of a Solar Thermochemical Reactor for Calcium Oxide Based Carbon Dioxide Capture

An engineering design for a 1-kW dual-cavity solar-driven reactor to capture carbon dioxide via the calcium oxide based two-step carbonation-calcination cycle is presented. In the low temperature carbonation step, gas containing up to 15% carbon dioxide flows through a gas manifold and plenum into an annular reaction zone filled with calcium oxide particles. The carbon dioxide reacts with the calcium oxide, forming calcium carbonate. Carbon dioxide-depleted gas flows out of the reactor through a second gas manifold. In the high temperature calcination step, concentrated solar radiation enters the beam-up oriented, windowless reactor and is absorbed by the diathermal cavity wall, which transfers heat via conduction to the calcium carbonate particles formed in the previous step. The calcium carbonate dissociates into calcium oxide and carbon dioxide. Additional carbon dioxide is used as a sweep gas to ensure high purity carbon dioxide at the outlet. Mechanical and thermal analyses are conducted to refine an initial reactor design and identify potential design shortcomings. Numerically predicted temperature profiles in the reactor are presented and the final reactor design is established.