Abstract: The preheating combustion technology based on circulating fluidized bed proposed is one of the new clean coal combustion technologies.The O_2/CO_2 ratio in the gas after fluidized preheating process has a great influence on the subsequent combustion and emissions.Exploring the coke combustion model that can correctly reflect the O_2/CO_2 ratio will help to further understand the fluidized preheating process.Based on the pulverized coal fluidized preheating conversion process,the typical preheated air-rich atmosphere( O_2/N2),oxygenrich atmosphere( O_2/CO_2),and fuel type change were used to study the conversion characteristics of the gaseous component CO/CO_2 after preheating.Moreover,the degree of matching between the existing coke combustion model and the fluidized preheating process was analyzed.The experimental data and model predictions show that in the air-rich oxygen atmosphere,as the oxygen concentration increases from 21% to 28.2%,the proportion of CO_2 in the preheated gas produced by Shenmu semi-coke fluidized preheating process decreases,the proportion of CO increases,and the CO/CO_2 ratio increases from 0.81 to 1.45.When Shenmu bituminous coal is preheated in the same atmosphere,the above-mentioned parameters show the same tendency as Shenmu semi-coke,and the CO/CO_2 ratio increases from 0.51 to0.76 as the oxygen concentration increases from 21.0% to 24.4%.In the oxygen-rich atmosphere,the CO produced by Shenmu semi-coke preheating is higher than that of Shenmu bituminous coal. The CO/CO_2 ratio also increases with the increase of oxygen concentration,but compared with the air-enriched atmosphere,the increasing degree is smaller. The experimental data of the preheated gas component CO/CO_2 of Shenmu bituminous coal is the most consistent with the prediction of the coke combustion model proposed by Tognotti,and the error of experiment and prediction results is within 9% under oxygen-rich atmosphere