A comparative simulation study of power generation plants involving chemical looping combustion systems
Abstract This work presents a simulation study on both energy and economics of power generation plants with inherent CO 2 capture based on chemical looping combustion technologies. Combustion systems considered include a conventional chemical looping system and two extended three-reactor alternatives (exCLC and CLC3) for simultaneous hydrogen production. The power generation cycles include a combined cycle with steam injected gas turbines, a humid air turbine cycle and a simple steam cycle. Two oxygen carriers are considered in our study, iron and nickel. We further analyze the effect of the pressure reaction and the turbine inlet temperature on the plant efficiency. Results show that plant efficiencies as high as 54% are achieved by the chemical looping based systems with competitive costs. That value is well above the efficiency of 46% obtained by a conventional natural gas combined cycle system under the same conditions and simulation assumptions.
Techno-economic analysis of chemical looping combustion with humid air turbine power cycle
Abstract Power generation from fossil fuel-fired power plant is the largest single source of CO2 emission. CO2 emission contributes to climate change. On the other hand, renewable energy is hindered by complex constraints in dealing with large scale application and high price. Power generation from fossil fuels with CO2 capture is therefore necessary to meet the increasing energy demand, and reduce the emission of CO2. This paper presents a process simulation and economic analysis of the chemical looping combustion (CLC) integrated with humid air turbine (HAT) cycle for natural gas-fired power plant with CO2 capture. The study shows that the CLC–HAT including CO2 capture has a thermal efficiency of 57% at oxidizing temperature of 1200 °C and reducer inlet temperature of 530 °C. The economic evaluation shows that the 50 MWth plant with a projected lifetime of 30 years will have a payback period of 7 years and 6 years for conventional HAT and CLC–HAT cycles respectively. The analysis indicates that CLC–HAT process has a high potential to be commercialised.
Computational Fluid Dynamics in chemical reactor analysis and design: Application to the ZoneFlow™ reactor for methane steam reforming
The ZoneFlow reactor (Tribute Creations, LLC) is a tubular reactor with two types of internals: a core type and adjacent to the wall, a casing type, both covered with a thin layer of catalyst. It aims for higher energy efficiency and lower steam-to-carbon ratios in methane steam reforming by a judicious design of the relative position of the internals and their geometrical characteristics and a higher catalyst effectiveness. The performance of this novel structured catalytic reactor for synthesis gas production by methane steam reforming was simulated using a reactor model accounting in detail for the flow pattern by means of Computational Fluid Dynamics (CFD). A Reynolds Averaged Navier Stokes (RANS) approach was taken. Turbulence, heat transfer by convection and radiation, detailed reaction kinetics including coking, intraparticle diffusion limitations, and the compressibility of the gas phase were accounted for. Simulations were carried out to investigate the ZoneFlow reactor performance under typical commercial operating conditions and compare it with a conventional packed bed reactor using the same Ni catalyst.