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The current development of chemical looping combustion (CLC) technology is presented in this paper. This technique of energy conversion enables burning of hydrocarbon fuels with dramatically reduced CO2 emission into the atmosphere, since the inherent separation of carbon dioxide takes place directly in a combustion unit. In the beginning, the general idea of the CLC process is described, which takes advantage of solids (so-called oxygen carriers) being able to transport oxygen between combustion air and burning fuel. The main groups of oxygen carriers (OC) are characterized and compared, which are Fe-, Mn-, Cu-, Ni-, and Co-based materials. Moreover, different constructions of reactors tailored to perform the CLC process are described, including fluidized-bed reactors, swing reactors, and rotary reactors. The whole systems are based on the chemical looping concept, such as syngas CLC (SG-CLC), in situ Gasification CLC (iG-CLC), chemical looping with oxygen uncoupling (CLOU), and chemical looping reforming (CLR), are discussed as well. Finally, a comparison with other pro-CCS (carbon capture and storage) technologies is provided.

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The calcium looping (CaL) process usually employs a dual-fluidized bed (DFB) solid circulating unit. In the regenerator (calcinator or calciner), decomposition of CaCO3 proceeds. To supply the heat of decomposition, oxyfuel combustion of coal is conducted. However, since coal contains nitrogen, the NO x formation occurs during oxyfuel combustion. Because of the fact that NO x formation and destruction during combustion of solid fuels in a fluidized bed is a complex process, a predictive approach of NO x emissions has not yet been sufficiently recognized, especially during oxyfuel combustion conditions in the CaL systems. The paper introduces a regression-based method for the prediction of NO x emissions from a CaL DFB experimental unit. Effects of fuel type, excess oxygen feed, and NO addition to primary or secondary feed gas on NO x emissions in the regenerator were evaluated. The presented way constitutes a straightforward method to run a complementary technique in relation to other methods of data handling, including the programmed computing approach and measurements. The developed model can be simply employed by scientists as well as engineers for optimization purposes.

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