(408a) Chemical Looping Combustion for Carbon Capture Efficiency

Authors: 
Ocone, R., Heriot-Watt University
Porrazzo, R., Heriot-Watt University
White, G., Heriot-Watt University
Cordiner, J., GB Biosciences, (Syngenta)
Among the well-known state-of-the-art technologies for CO2 capture, Chemical Looping Combustion (CLC) stands out for its potential to capture with high efficiency the CO2 from a fuel power plant for electricity generation. CLC involves combustion of carbonaceous fuel such as coal-derived syngas or natural gas via a red-ox chemical reaction with a solid oxygen carrier circulating between two fluidised beds, air and fuel reactor, working at different hydrodynamic regimes. Avoided NOx emissions, high CO2 capture efficiency, low CO2 capture energy penalties and high plant thermal efficiency are the key concepts making worthy the investigation of the CLC technology. One of the main issues about the CLC technology might concern the cost of the solid metal oxides and therefore the impact of the total solid inventory, solid make-up and lifetime of the solid particles on the cost of the electricity generated. In this work, macro scale models of fluidised beds (i.e. derived applying macroscopic equations) are developed and implemented in Aspen Plus software. Kinetic and hydrodynamic phenomena, as well as different operating conditions, are taken into account to evaluate their effect on the total solid inventory required to get full fuel conversion. Additionally, a 2D â??microâ? scale model of the fuel reactor (i.e. derived applying partial differential equations), making use of a CFD code, is also developed. The results, in terms of the effect of the different kinetic and hydrodynamic conditions on the outlet gas conversion, drive the improvement of the macro scale model to capture the main physics influencing the performance of the fuel reactor. The latter macro scale model is embedded into a natural gas fired power plant configuration where mass and energy balances are solved simultaneously. Two CFD platforms (namely MFIX and OpenFOAM) are implemented to devise the influence that the reactorâ??s internals have on the hydrodynamics and then on the conversion. Finally, a thermal efficiency evaluation of the CLC power plant is carried out together with a detailed economic analysis. The effect of the fuel price and lifetime of the solid particles on the Levelised Cost Of Electricity (LCOE) is investigated and the resulting outcomes are critically discussed in comparison with post-combustion technology employing amines.