(555d) CO2 Separation From Coal-Fired Power Plants by Regenerable Mg(OH)2 Solutions

CO₂  Separation from Coal-Fired Power Plants by Regenerable Mg(OH)₂ Solutions   

 Hari K. Bharadwaj^†, Joo-Youp Lee^† *, Xiang Zhou^‡, Lei Cheng^‡, Tim C. Keener^‡

^†Chemical Engineering Program, ^‡ Environmental Engineering Program, School of Energy, Environmental, Biological, and Medical Engineering, University of Cincinnati, Cincinnati, OH 45221-0012

World energy demand is expected to increase by 57% from 2004 to 2030 which will undoubtedly produce a concurrent increase in atmospheric GHG levels unless something is done to mitigate the release of CO₂ to the atmosphere.  In response to this, a method is proposed of effectively, efficiently and reliably separating CO₂ from flue gases for potential sequestration purposes by means of the absorption of CO₂ in slurry containing magnesium compounds conducted at 52 °C, followed by a regeneration step conducted at 65 °C.  Mg(OH)₂ is readily available commercially, and/or may be easily and economically reclaimed from coal-fired power plants using lime-based flue gas desulphurization systems (FGD).  The CO₂ scrubbing system will be operated as a regenerable system where a concentrated CO₂ gas stream is created for further processing, and the magnesium reclaimed for further absorption of CO₂.  The process has many advantages including proven absorption technology, no modification of the existing boiler heat-transfer configuration, low temperature CO₂ regeneration, and the use of magnesium by-products for further SO₃ control.  This presentation will demonstrate our current research efforts in CO₂ absorption and regeneration including magnesium chemistry, lab-scale absorber operation, magnesium carbonate formation, and vapor-liquid-solid equilibrium for CO₂ stripper design and operation.

Keywords: CO₂ separation, Coal-fired power plants, magnesium hydroxide