洁净煤技术

2019, (04) 72-79

[打印本页] [关闭]
本期目录(Current Issue) | 过刊浏览(Past Issue) | 高级检索(Advanced Search)

两类锅炉中兰炭粉和生物质混燃特性数值模拟
Numerical simulation of co-firing characteristics of pulverized semi-coke and biomass in the two different boilers

李美军;程晓磊;杨石;张鑫;王永英;崔豫泓;
LI Meijun,CHENG Xiaolei,YANG Shi,ZHANG Xin,WANG Yongying,CUI Yuhong

摘要(Abstract):

清洁能源兰炭粉价格低且污染物排放量小,但其着火和燃尽困难。可再生能源生物质清洁低碳、易于获取且利于着火,但其能量密度低。二者混燃可有效改善兰炭粉的着火和燃烧特性,解决生物质能量密度低的问题,有利于提高燃料适用性。针对煤科院自主研发的水冷式和风冷式锅炉,研究了不同掺混比例对兰炭粉和生物质混燃特性的影响,分析了不同型式的锅炉中不同混燃特性产生的原因。采用数值模拟方法建立了三维等比例模型,综合考虑了湍流、传热、挥发分析出和燃烧、固定碳燃烧、颗粒流动等实际燃烧过程。模型计算结果与文献试验结果的相对误差不超过5%,从而验证了模型的准确性。分析对比了不同掺混比例下,两类锅炉燃烧器出口温度分布、燃烧区域温度分布、炉膛出口温度分布及氧含量分布等。结果表明:水冷式锅炉中,掺混比例为2/8时燃烧器出口平均温度和最高温度、燃烧区域平均温度以及炉膛出口平均温度均最高,炉膛出口平均氧含量为最低值6%,燃烧性能最好,4/6和10/0时最差。风冷式锅炉中,掺混比例为4/6时燃烧器出口平均温度和最高温度达到最高,氧含量最低,为4. 8%,因此燃烧性能最好,8/2和10/0时最差。随掺混比例增大,两类锅炉燃烧器内的着火位置逐渐向前锥推移并在前锥最前端出现最高温度;水冷式锅炉着火位置偏向前锥时对炉膛内燃烧性能下降的影响较大。两类锅炉相比,风冷式锅炉的各温度参数明显较高,氧含量较低;水冷式锅炉在最佳工况2/8时,除燃烧区域最高温度外,各温度参数均低于风冷式,氧含量高1%,燃烧性能低于风冷式锅炉;风冷式锅炉处于最差工况8/2时,温度比水冷式锅炉高300~700K,氧含量是其1/2,故燃烧性能高于水冷式锅炉;在相同掺混比例下,风冷式锅炉燃烧性能明显优于水冷式锅炉。
Compared with coal,the pulverized semi-coke has a lower price and a lower pollution emissions,but has more difficulty in ignition and burn-out.Renewable energy biomass is clean,low carbon,easy to access and prone to fire,but it has a lower energy density.Therefore,the co-combustion of pulverized semi-coke and biomass can improve the ignition and combustion characteristics of pulverized semi-coke,solve the problem of low biomass energy density,and improve fuel applicability.It plays a significant role in energy-saving and improvement of the fuel application.In order to derive the optimal mixing ratios in water-cooled and air-cooled boilers which were independently developed by the Coal Science Institute,the effects of different mixing ratios on the mixed combustion characteristics of semi-coke and biomass were studied,and the causes of different mixed combustion characteristics in different types of boilers were analyzed.A three-dimensional proportional model was established by numerical simulation method,which comprehensively considered the turbulent flow,radiation heat transfer,volatile precipitation,gas phase reaction,particle motion and fixed carbon combustion.The relative error between the calculated results of the model and the experimental results in the literature was less than 5%,which verified the accuracy of the model.The temperature profiles of burner outlet,combustion region and furnace outlet,the oxygen content of furnace outlet of two distinct boilers were analyzed under different mixing ratios.The results show that in the water-cooled boiler,the optimal combustion performance appears at 2/8 mixing ratio(semi-coke/biomass),and the worst appears at 4/6 and 10/0.With a 2/8 mixing ratio,the average and highest temperature of burner outlet,combustion region and furnace outlet are the highest,and the oxygen content of furnace outlet is the lowest value of 6%.Whereas in the air-cooled boiler,the optimal mixing ratio is 4/6,and the worst is 8/2 and 10/0.With a 4/6 mixing ratio,the average and highest temperature of burner outlet are highest,and the oxygen content is the lowest value of 4.8%.With the increasing mixing ratio,the ignition position in the burner moved forward gradually and the highest temperature appeared at the front end of the front cone in the two types of boilers.When the ignition position of the water-cooled boilers shifts to the front cone,the combustion performance in the furnace decreases greatly.With the comparison of two boilers,all the temperatures of the air-cooled boiler are obviously higher and the oxygen content is lower.When the optimum working condition is 2/8 in the water-cooled boiler,all the temperature parameters except the highest temperature in the combustion region are lower than those of the air-cooled boiler,and the oxygen content is 1% higher and the combustion performance is lower than that of air-cooled boiler.When the air-cooled boilers is in the worst working condition of 8/2,all the temperatures of the air-cooled boiler are 300-700 K higher and the oxygen content is the half of that in the water-cooled boiler.So the combustion characteristics of air-cooled boiler is better than that of the water-cooled boiler.Under the same mixing ratio,the combustion performance of air-cooled boiler was significantly better than that of the water-cooled boiler.

关键词(KeyWords): 兰炭粉;生物质;混燃特性;工业锅炉
pulverized semi-coke;biomass;co-firing characteristics;industrial boiler

Abstract:

Keywords:

基金项目(Foundation):

作者(Author): 李美军;程晓磊;杨石;张鑫;王永英;崔豫泓;
LI Meijun,CHENG Xiaolei,YANG Shi,ZHANG Xin,WANG Yongying,CUI Yuhong

Email:

参考文献(References):

文章评论(Comment):

序号(No.) 时间(Time) 反馈人(User) 邮箱(Email) 标题(Title) 内容(Content)
反馈人(User) 邮箱地址(Email)
反馈标题(Title)
反馈内容(Content)
扩展功能
本文信息
服务与反馈
本文关键词相关文章
本文作者相关文章
中国知网
分享