Thermal Efficiency of Combined Cycle Power Plants Involving

Chemical Looping Based Systems

Vicente Rico-Ramirez, Moises A. Petriz-Prieto and Guillermo Gonzalez-Alatorre Instituto Tecnologico de Celaya, Departamento de Ingenieria Quimica, Av. Tecnologico y Garcia Cubas S/N, Celaya, Guanajuato, Mexico 38010

Abstract

This work presents a study on both energy performances and total annual cost of combined cycle power generation plants with CO2 capture based on chemical looping combustion systems. The combustion systems considered include the conventional chemical looping (CLC) and its extended version (exCLC). In the conventional version of a CLC, combustion takes place into two separate reactors (oxidation and reduction reactors), using a metal that acts as an oxygen carrier; then, separate streams of exhaust air and CO2 are obtained. In the exCLC configuration, the oxygen carrier circulates along with a carbon carrier through three reactors. In the first reactor, the oxygen carrier is oxidized with air; in the second reactor, fuel is consumed along with the oxygen transported through the carrier and hydrogen is produced. Finally, in the third reactor the carbon carrier is regenerated.
The power generation cycles used for the analysis include novel modifications to the combined cycle with steam injected gas turbines (STIG) and the Humid Air Turbine cycle (HAT). Three different carriers are also considered in our study. The thermal efficiencies and cost of the various combinations of combined cycles and combustion systems (including carrier selection) are compared to the performance of a base combined cycle with amine adsorption (CC-AA).
Further, we analyze the effect of the pressure in the system reaction, the material flows that control the turbine inlet temperature (TIT) and, for the case of the exCLC, the effect of the conditions that favor production of H2 and those that improve power generation. Results indicate that thermal efficiencies as high as 54% for the chemical looping based systems are achieved with competitive TAC. That value is well above the efficiency of 46% obtained by the system of CO2 capture with amine adsorption (46%).

Keywords: Chemical Looping, CO2 Capture, Combined Cycle Power Plants.