Radiation Characteristics of Coal Fired Boiler Changing with Burnout Rate
To address the issues of low accuracy in particle radiation characteristics in combustion simulation and complex calculation of radiation characteristics in coal-fired boilers,a new single particle pulverized coal burnout model is established.This model fits the density ratio and diameter ratio of multiple coal types varying with burnout rate.Taking Jiaozuo coal as an example,the Mie theory is used to calculate the absorption and scattering efficiency of coal particles.With further consideration of pulverized coal particle swarm,the absorption and scattering coeffi-cients are calculated.Based on this,the particle emissivity and scattering factor in the simulation are modified into polynomial and linear models using user-defined functions(UDF),which is compared and verified with on-site detection results.The radiation characteristics of coal-fired boilers varying with burnout rate are studied.The results show that there is a significant change in density during the combustion process of each coal type,and the particle size decreases to 50%—70%when fully burned.The particle emissivity slightly increases from 0.897 in the early and mid-term of combustion,and sharply decreases in the late stage.The error between the above correction and the on-site section temperature detection decreases from 6.07%to 2.96%,which is more consistent with the actual situation.
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