Conventional and optimized testing facilities of calcium looping process for CO2 capture: A systematic review

CO2 generated by the combustion of fossil fuels is the main source of global warming. Carbon capture and storage (CCS) is considered to play a crucial role in reducing greenhouse gas emissions. Calcium looping (CaL) process is a promising carbon capture technology to minimize efficiency penalty and related augment in electricity cost. This review first provides an overview of the available conventional bench-scale, pilot-scale and demonstrationscale testing facilities (1 kWth-20 WMth) worldwide, with a focus on summarizing the characteristics and operational status of the testing facilities, and extracting critical experimental results. There were two kinds of optimized systems that can alleviate the problems faced by conventional systems. To solve the problem of adverse effects of impurity elements from fuel combustions on CO2 capture, indirectly heated calciners had been constructed and tested. To solve the problem of the rapid decay of sorbents with increasing number of cycles, three methods had been used to optimize the systems, including introducing steam during the carbonation and/ or the calcination process, intermediate hydration after calcination and re-carbonation by partial CO2 from calciner.