Gaseous emissions from advanced CLC and oxyfuel fluidized bed combustion of coal and biomass in a complex geometry facility:A comprehensive model

Abstract

Since the formation of gaseous pollutants during solid fuel combustion in circulating fluidized bed (CFB) units, especially under oxyfuel combustion and chemical looping combustion conditions, is an extremely complex process, the development of a simple predictive model of gas emissions is of practical significance. This paper introduces a novel approach based on fuzzy logic (FL), one of the main artificial intelligence (AI) methods, for the prediction of CO2, CO, NOx (i.e., NO + NO2), N2O, and SOx (i.e., SO2 + SO3) concentrations in flue gases from coal and biomass combustion in various operational sceneries. The simulations are carried out for different combustion environments, i.e., air-firing, oxyfuel, iG-CLC (in-situ gasification chemical looping combustion), and CLOU (chemical looping with oxygen uncoupling), under a wide range of operating parameters. A mixture of oxygen with CO2 was used for oxyfuel combustion. Three different oxygen carriers (OC) were examined in the study for iG-CLC and CLOU, i.e., ilmenite, copper oxide (60% wt.) with the support of carbonate waste from ore flotation, and copper oxide (60% wt.) with the support of ilmenite (20% wt.) and fly ash. The validation of the model was successfully performed on a complex geometry laboratory–scale 5 kWth Dual-Fluidized-Bed Chemical-Looping-Combustion of Solid-Fuels (DFB-CLC-SF) facility. The gaseous pollutant emissions predicted using the developed model were in good agreement with experimental results. The maximum relative error between measured and predicted by the model emissions was lower than 8%. The proposed method constitutes a quick and easy-to-run technique and a complementary tool compared to the experimental procedures and the programmed computing approach. The developed fuzzy logic-based model of gaseous emissions from advanced combustion (GasAdComb) of solid fuels can be easily applied by scientists and engineers to simulate and optimize coal and biomass combustion processes.