%0 Journal Article
%T 煤粉空气分级燃烧中还原性气氛的模拟预测及分析
%A 李振山
%A 蔡宁生
%A 陈登高
%J 洁净煤技术
%D 2019
%X 空气分级燃烧是广泛采用的煤粉低氮燃烧技术,使用数值模拟方法对其进行模拟预测,有助于燃烧设备的改进并优化燃烧,实现在燃烧中进一步降低污染物排放。空气分级燃烧数值模拟中对还原区的准确模拟是预测氮氧化物排放、硫化氢高温腐蚀等的基础。笔者旨在提出一种合理预测煤粉空气分级燃烧还原性气氛的数值模拟方案,并将其应用于实际锅炉的模拟,并探讨了还原性气氛预测准确性对氮氧化物排放、焦炭燃烧等的影响。主要内容包括:①对煤粉空气分级燃烧过程进行原理分析,提出数值模型开发及其应用的研究思路,即是通过小型电加热沉降炉模拟实际锅炉分级燃烧温度和组分浓度场,测量组分、焦炭转化等参数用于模型开发和验证,最后将开发的模型嵌入商用数值模拟平台,实现分级燃烧全过程模拟。基于此,搭建了能够反映实际锅炉空气分级燃烧温度场和组分浓度场特性的电加热沉降炉试验平台,并通过在线称重给煤速率、气体浓度组分测量,对试验系统的稳定性进行了验证。②设计不同工况的空气分级燃烧试验,并获取沿程CO、H_2、焦炭转化率等关键数据,基于数值模拟的动力学优化方法获取空气分级燃烧状态下还原区焦炭的气化反应动力学参数。通过开发用户自定义函数的方式在Fluent平台上实现了焦炭气化以及还原性气氛的模拟预测,并将其应用于600 MWe超临界墙式对冲炉分级燃烧的数值模拟。③分析比较了在模拟中不考虑气化和考虑气化时对炉内温度、还原区气氛、氮氧化物的分布和焦炭转化的影响。结果表明,文中提出的空气分级燃烧数值模拟方案能实现对实际锅炉空气分级燃烧特别是还原区的合理预测;在模拟中不考虑焦炭气化将导致还原性气体浓度明显偏低,导致颗粒燃尽推迟,炉膛出口氮氧化物浓度偏高。 Air staged pulverized coal combustion is a widely used low NOx combustion technology.Numerical simulation method has been used to help improving the combustion inside the furnace in order to further reduce the pollutants during combustion process.The prediction of reductive atmosphere is the foundation for accurate prediction of NOx emission,H2S erosion,and so on.The main purpose of the paper is to propose a route for reasonable numerical simulation of air staged combustion.And apply the proposed methods on the simulation of actual boilers and analysis the effect of the prediction accuracy of the reductive atmosphere.The main content includes:① The characteristics of pulverized coal air staged combustion was discussed.A research routine for the development of numerical simulation models and its application was developed.This includes the model development and validation based on air staged combustion drop tube furnace experiments,and application of the developed model on commercial CFD simulation platform for numerical simulation of air staged combustion.② A drop tube furnace experiment platform was built to form a temperature and species field that is similar to actual boiler.The combustion stability of the system was quantified by online measured coal feeding rate and gas species concentrations.Experiments under different conditions were designed and conducted to obtain key results,for example the concentration of CO,H2 and coal conversion.Thirdly,a coal reaction model that can simulate both oxidation and gasification reaction was developed and coupled into commercial CFD platform.The developed models were applied on the simulation of a 600 MWe super critical wall fired furnace.③ The simulated results with consideration of char gasification and without that were compared in terms of the distribution of reductive gases,NOx distribution and emission,and coal
%K 煤粉空气分级燃烧
%K 还原性气氛
%K 数值模拟
%K 焦炭气化
%K 墙式对冲炉 coal air staged combustion
%K reductive atmosphere
%K numerical simulation
%K char gasification
%K wall fired furnace
%U http://www.jjmjs.com.cn/WKD/WebPublication/paperDigest.aspx?paperID=643d29f8-8344-4148-bef7-85b0ec81c3e8