Energy & Fuels, Vol.32, No.5, 6355-6362, 2018
NOx Emissions from Regenerator of Calcium Looping Process
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 NOx formation occurs during oxyfuel combustion. Because of the fact that NOx formation and destruction during combustion of solid fuels in a fluidized bed is a complex process, a predictive approach of NOx 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 NOx emissions from a CaL DFB experimental unit. Effects of fuel type, excess oxygen feed, and NO addition to primary or secondary feed gas on NOx 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.