旋流式分解炉燃烧与分解耦合及NO<sub><em>x</em></sub>生成的数值模拟

摘要针对一新型的旋流式分解炉建立模型,对煤粉燃烧与生料分解耦合及NO_x生成过程进行了数值模拟。其中对连续相采用Euler坐标系下的Realizable k-ε双方程湍流模型,对于颗粒相采用离散相(Discrete phase model)模型以及随机轨道模型,对煤粉燃烧和碳酸钙分解过程采用组分输运模型(Species transport model)并结合有限速率/涡耗散模型(Finite-rate/eddy-dissipation)模拟,采用P-1辐射模型计算颗粒与气体间的辐射换热,对NO_x的生成使用污染物模型,考虑热力型NO_x,燃料型NO_x的生成。研究结果表明:在分解炉内,三次风主要沿壁面螺旋向上运动,而烟气主要沿中轴线螺旋向上运动;当煤粉进入分解炉后挥发分快速释放并燃烧,而后残余焦炭持续燃烧,其主要的燃烧区域在蜗壳附近,燃烬时间约为5.9 s;生料入炉后便快速分解,当运动至分解炉50 m高度处,碳酸钙分解率达到了90%,此时下端生料与上端生料的分解时间约为6.5 s与4.7 s,出口碳酸钙分解率为92.32%。由于在蜗壳处煤粉燃烧与生料分解的耦合关系较差,在壁面处形成了局部高温,使NO_x生成速率较大,出口处NO_x达到了1.251×10^-3,需对此进行改进。

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	李全亮
	何峰
	梅书霞
	谢峻林
	张超
	邓玉华

关键词：分解炉煤燃烧碳酸钙分解 NO_x 数值模拟计算流体力学

Abstract： Aiming at a new type of swirl precalciner, numerical simulations were carried out for the pulverized coal combustion, raw meal decomposition coupling, and NO_x generation processes. In Euler coordinate system gas phase was expressed with the Realizable k-ε two-equation model, in Lagrange coordinate system solid phase was expressed with the discrete phase model(DPM),pulverized coal combustion and raw meal decomposition was expressed with the species transport model,radiation was expressed with the P-1 model, NO_x generation was expressed with the pollutant model. Thermal NO_x and fuel NO_x generation are considered. The results show that the tertiary air mainly moves upward along the wall spiral, while the flue gas mainly moves the central axis spiral in the precalciner. When the pulverized coal enters the precalciner, the volatiles are rapidly released and burned, and then the char continues to burn, and its main combustion area is near the shell. When the pulverized coal enters the precalciner, the volatiles are rapidly released and burned, and then the char continues to burn, and its main combustion area is near the shell, and the combustion residence time is approximately 5.9 s. The raw meal decomposes rapidly after entering the precalciner. When reaching a height of 50 m in the precalciner, the decomposition rate of CaCO₃ reaches 90%. At this point, the decomposition times for the lower and upper raw meal are approximately 6.5 s and 4.7 s, respectively. 92.32% decomposition of calcium carbonate at the outlet. Due to the poor coupling between pulverized coal combustion and raw meal decomposition at the shell, local high temperatures are formed at the wall, which makes the NO_x generation rate larger, and the NO_x at the outlet reaches 1.251×10^-3, which needs to be improved.

Keywords： precalciner coal combustion calcium carbonate decomposition NO_x numerical simulation computational fluid dynamics

Received 2023-03-01;

Fund:全氧燃烧技术研发(CBMI-KJCX-2021-04)。

Corresponding Authors: 梅书霞,教授级高级实验师,msx0303@163.com;谢峻林,教授,xjl09532@bjut.edu.cn。 Email: msx0303@163.com;xjl09532@bjut.edu.cn

About author: 李全亮(1997—),男,博士研究生,现从事燃烧及污染物减排数值模拟方面的研究。

引用本文:

李全亮, 何峰, 梅书霞, 谢峻林, 张超, 邓玉华.旋流式分解炉燃烧与分解耦合及NO_x生成的数值模拟[J]. 化学工业与工程, 2025,42(2): 177-186

LI Quanliang, HE Feng, MEI Shuxia, XIE Junlin, ZHANG Chao, DENG Yuhua.Numerical simulation of pulverized coal combustion and calcium carbonate decomposition coupling and NO_x generation in swirl precalciner[J]. Chemcial Industry and Engineering, 2025,42(2): 177-186

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