Study On The Influence Of Radiation Model On The Numerical Simulation Of Pulverized Coal Combustion In Oxygen-enriched Atmosphere

Oxy-fuel combustion has become one of the most promising technologies for carbon capture and storage?CCS?in coal-fired plants.O₂/CO₂ combustion technology is a low risk of CO₂ capture and storage technology.O₂/CO₂ combustion technology has a high combustion efficiency and can effectively reduce emissions of pollutants.In oxy-fuel combustion with CO₂ recycle,the non-gray gas radiative heat transfer characteristics of gaseous participating media are different from those in air-fuel combustion.The ratio of the three atom gas is increased from 20% to 95% after using CO₂ instead of N2,which enhances the radiation ability of flue gas.A few modified weighted-sum-of-gray-gases?WSGG?models had been proposed to consider the wide H₂O to CO₂ ratio for oxy-fuel combustion in recent years.At present,domestic and foreign scholars mainly focus on the study of gas radiation model and few researchers have applied the gas radiation model to the Fluent software.The main contents of this paper are as follows.Firstly,Matalab software is used to calculate the gas emission rate of each WSGG model at different temperatures and paths.Using the statistical narrow-band?SNB?model as the benchmark,this paper provides a comprehensive assessment of the development of the weighted-sum-of-gray-gases?WSGG?model in recent years.As the path increases,the coincidence between the WSGG model and SNB model is getting better and the maximum absolute value of relative error of gas emission rate is 30%.With the increase of temperature,the gas emission rate decreases,and the maximum absolute value of relative error of gas emission rate is 20%.Johansson et al.'s WSGG model is applicable and the relative error of Yin et al.'s WSGG model is also acceptale.Secondly,a suit of mathematical and physical models have been verified by comparing to the experimental results.The numerical simulation of pulverized coal combustion process under different radiation models were carried out and the distributions of the temperature and NO are analyzed then.After using the radiation model,the furnace temperature is significantly reduced.The DO and DO+WSGG radiation models have great influence on the combustion temperature of pulverized coal in pulverized coal combustion area.Finally,Yin et al.'s and Johasson et al'.s WSGG models are applied to the Fluent software by UDF module.The effects of different WSGG?Smith et al.'s WSGG,Yin et al.'s WSGG,Johasson et al.'s,WSGG?models on the combustion temperature distribution and NO generation of pulverized coal are compared.Yin et al.'s and Smith et al.'s WSGG models have similar effects on pulverized coal combustion under different particle sizes,which are different from Johasson et al.'s WSGG model in the pulverized coal combustion zone.Yin et al.'s and Smith et al.'s WSGG models have similar effects on pulverized coal combustion at low oxygen concentrations.Yin et al.'s and Johasson et al'.s WSGG models have similar effects on pulverized coal combustion at high oxygen concentrations.