Oxy-Combustion in ITM Reactors: System's Analysis, Combustion, Electrothermochemistry and Materials

Fossil fuels -- and their conversion through combustion -- are and will remain to be the major primary energy source for centralized electricity and heat generation while longer term solutions such as renewable primary energy sources are further developed for large scale applications. However, in light of the impact of greenhouse gases such as CO2 , even short term solutions will require a significant CO2 emission reduction. One of the most attractive methods of CO2 reduction is CO2 Capture and Storage (CCS). A promising CCS technology for lighter hydrocarbons and gaseous fuels is oxy-combustion, where fuel is combusted in pure (or almost pure) oxygen, thereby simplifying the subsequent CO2 separation. Oxy-combustion plants require an air separation unit (ASU) to provide the required pure oxygen, a combustor designed to accommodate the unique combustion aspects of burning in pure oxygen, and possibly novel turbo-machinery that operate with CO2 rich working fluids, as opposed current designs for exhaust streams with high N2 concentrations.

Current ASUs represent a significant component of the capital investment in an oxy-combustion CCS power plant and a 15-20% reduction in thermodynamic efficiency compared to a non-CCS powerplant. As an alternative to conventional ASUs, thin (<1mm) ceramic Ion Transport Membranes (ITM) can be used at high temperatures (700-900°C) for high-purity air separation. The air separation rate of ITM can be improved by a factor of 3-5, and hence the required capital investment reduced, when they are coupled with the combustion process in a so-called ITM reactor. The separation penalty associated with the oxygen production process is expected to be significantly lower than current ASUs, thus making ITM oxy-combustion more thermodynamically viable for CCS. It is the focus of this multi-faceted project to consider the implications of using such membranes for power generation through the following research activities:

(*) Investigation of suitable ceramic membrane materials and how they might be modified for maximum performance, while still maintaining suitable chemical, mechanical, and thermal stabilities for ITM reactors (Professors Yang Shao-Horn and Mezghani).
(*) Application of experimental investigations of various degrees of complexity in unison with detailed numerical simulations to understand the combustion processes within the ITM reactor, as well as the specific considerations demanded by oxy-fuel combustion. A major challenge of this sub-task is identifying the operating regimes and potential control strategies for ITM reactors (Professors Ghoniem, Habib, Ben-Mansour, Badr, and Ahmed)
(*) Development of system-level models and analyses of ITM power plants to optimize the integration of the ITM reactor into a suitable power cycle in the most efficient and feasible manner (Professor Mitsos).

It is through this comprehensive project structure, considering the membrane development, its performance when coupled with combustion, and its integration into a suitable power cycle, that the most applicable solutions can bring this attractive and promising technology one step closer to realization.