西安建筑科技大学学报(自然科学版)

通过研究内外风量比对回转窑内火焰形状、烟气流场及其温度分布的影响,为优化燃烧器的操作参数提供依据.以一四风道煤粉燃烧器及Φ4 m×60 m的回转窑为对象,应用Fluent软件,建立了k-ε湍流模型,煤粉燃烧模型和辐射换热模型.研究了以煤粉为燃料,内外风量比分别为0.37、0.47、0.6和0.8时,回转窑内火焰形状、烟气流场及温度分布情况.结果表明,内外风量比为0.47时,回转窑内火焰形状成良好的棒槌状,火焰高温区达到2 000 K,火焰温度分布符合水泥熟料煅烧的要求.计算给出了最佳条件下,沿窑长方向上的O2、CO、CO2的摩尔浓度分数分布,计算分析了喷煤管出口附近的内回流区和窑壁附近的外回流区,表明了在最佳操作参数条件下窑内流场分布和气体浓度场分布的合理性.

Pulverized coal combustion in rotary kiln provides heat for cement clinker calcination. The effects of internal air volume ratio on the flame shape, gas flow field and temperature distribution were investigated, which provides the basis of optimization operation and structure parameter for the burner. Accordingly, a rotary kiln with the length of 60 m and the diameter of 4 m using pulverized coal burner is examined. With the Fluent software, the turbulence model, the pulverized coal combustion model and radiation heat transfer model were established. When the internal air volume ratios were 0.37, 0.47, 0.6 and 0.8, respectively, the flame performance, gas flow and temperature distribution in rotary kiln with a pulverized coal as fuel were analyzed. The results show that when the internal air volume ratio is 0.47, it will get the good flame shape and the flame temperature can reach 2 000 K within the rotary kiln, and flame temperature distribution meets the requirements of cement clinker calcination. Under the given best conditions, mole fraction profiles of O2, CO, and CO2 is obtained along the length direction of the kiln. Analyzing the inner recirculation zone near the outlet of the burner and outer recirculation zone near the kiln wall shows that the flow field and the gas concentration are reasonable under the best operating parameters.

引言
1 数学模型的建立
2 计算结果与分析
3 结论

图1 四通道煤粉燃烧器的结构示意图<br/>Fig.1 Sketch of four channel pulverizedcoal burner

图1 四通道煤粉燃烧器的结构示意图
Fig.1 Sketch of four channel pulverizedcoal burner

图2 回转窑计算域示意图<br/>Fig.2 Schematic diagram of the calculation domain

图2 回转窑计算域示意图
Fig.2 Schematic diagram of the calculation domain

图3 计算区域网格划分示意图<br/>Fig.3 Diagram ofmesh generation of the calculation domain

图3 计算区域网格划分示意图
Fig.3 Diagram ofmesh generation of the calculation domain

表1 各风道的入口速度与质量流率<br/>Tab.1 The inlet velocity and mass flow rate of the ducts

表1 各风道的入口速度与质量流率
Tab.1 The inlet velocity and mass flow rate of the ducts

表2 煤的元素分析<br/>Tab.2 Elemental analysis of the coal

表2 煤的元素分析
Tab.2 Elemental analysis of the coal

图4 不同内外风量比时窑内温度分布图<br/>Fig.4 The temperature distribution in the kiln with different internal air volume ratio

图4 不同内外风量比时窑内温度分布图
Fig.4 The temperature distribution in the kiln with different internal air volume ratio

图5 不同横截面上的温度云图(单位:K)<br/>Fig.5 Temperature distribution of the different cross section

图5 不同横截面上的温度云图(单位:K)
Fig.5 Temperature distribution of the different cross section

图6 中心纵切面z=0上的窑头速度矢量图<br/>Fig.6 The velocity vector diagram of the kiln head at z=0 in the center

图6 中心纵切面z=0上的窑头速度矢量图
Fig.6 The velocity vector diagram of the kiln head at z=0 in the center

图7 x=1截面速度矢量图<br/>Fig.7 Thevelocity vector diagram at x=1 cross section

图7 x=1截面速度矢量图
Fig.7 Thevelocity vector diagram at x=1 cross section

图8 窑内O2、CO、CO2的摩尔浓度分布<br/>Fig.8 Concentration distribution of O2, CO and CO2in the rotary kiln

图8 窑内O2、CO、CO2的摩尔浓度分布
Fig.8 Concentration distribution of O2, CO and CO2in the rotary kiln

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备注

引言

1 数学模型的建立

2 计算结果与分析

3 结论

期刊信息