Integration of heat recovery unit in coal fired power plants to reduce energy cost of carbon dioxide capture

Abstract

This work presents the feasibility of utilizing a novel heat recovery unit (HRU) technology, to directly recover thermal energy contained in flue gas utilizing an inert non-aqueous heat transfer fluid (HTF), which can then be utilized to lower CO2 capture costs and increase overall power plant efficiency. Silicone oil was identified as the HTF for use in this direct heat recovery process, as the fluid is thermally stable and resistant to oxidation. Interactions between the HTF and flue gas were investigated with the HTF found to be chemically resistant to SO2 and CO2. The viability of using an HTF as an energy vector between flue gas and CO2 rich-amine solvent was studied via bench-scale experimentation showing distinct phase separation devoid of reactions between the HTF and CO2 rich-amine solvent. Energy savings in reboiler heat duty with HRU integration were estimated using Aspen Plus simulations. Simulation results suggest HRU integration schemes could lower reboiler heat duty between 15.1% and 31.2%.