Chemical‐looping combustion (CLC) is an innovative technology for power production with inherent carbon dioxide (CO2) capture. Even though CLC imposes no direct energy penalty for CO2 capture, previous works have shown significant energy penalties relative to natural gas (NG) combined cycle plants. This is due to the relatively low turbine inlet temperature (TIT), which is limited by the oxygen carrier used in the CLC process. Therefore, herein, an additional combustor (COMB) is included downstream of the CLC unit to raise the TIT (dependent on the CLC/COMB outlet temperature [COT] and the blade cooling). When NG is used in the additional COMB, the energy penalty is only 2.9% points with 72% CO2 capture. Achieving higher CO2 capture requires the use of H2 fuel in the COMB. The efficiency of the H2 production process plays an important role. For conventional H2 production with post‐combustion CO2 capture, the added COMB brings no improvement and the energy penalty is 8.8% points. For an advanced H2 production process (90% efficiency), the energy penalty reduces to 4.5% points with 100% CO2 capture. The results show the potential of CLC‐combined cycle power plants with an additional COMB to minimize the energy penalty of CO2 capture.
Chemical looping has great potential for reducing the energy penalty and associated costs of CO2 capture from fossil fuel-based power and chemical production while maintaining high efficiency. However, pressurized operation is a prerequisite for maximizing energy efficiency in most proposed chemical looping configurations, introducing significant complexities related to system design, operation and scale-up. Understanding the effects of pressurization on chemical looping systems is therefore important for realizing the expected cost reduction of CO2 capture and speed up the industrial deployment of this promising class of technologies.This paper reviews studies that investigated three key aspects associated with pressurized operation of chemical looping processes. First, the effect of pressure on the kinetics of the various reactions involved in these processes was discussed. Second, the different reactor configurations proposed for chemical looping were discussed in detail, focusing on their suitability for pressurized operation and highlighting potential technical challenges that may hinder successful operation and scale-up. Third, techno-economic assessment studies for these systems were reviewed, identifying the process configuration and integration options that maximize the energy efficiency and minimize the costs of CO2 avoidance.Prominent conclusions from the review include the following. First, the frequently reported negative effect of pressure on reaction kinetics appears to be overstated, implying that pressurization is an effective way to intensify chemical looping processes. Second, no clear winner could be identified from the six pressurized chemical looping reactor configurations
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