Numerical simulation on gas-solid flow characteristics and NO(x)formation of a full-scale dual circulating fluidized bed boiler
Numerical simulation on gas-solid flow characteristics and NO(x)formation of a full-scale dual circulating fluidized bed boiler
复制标题
全尺寸双循环流化床锅炉气固流动特性及NO(x)生成数值模拟
DOI：
10.1080/15567036.2020.1811807
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Lu Xiaofeng
中科院分区：
文献类型：
--
作者：
Nie Hua;Li Jianbo;Zhang Yi;Liu Qingcai;Wang Quanhai;Lu Xiaofeng
对新型全尺寸双循环流化床（DCFB）中的气固流动特性和燃料NOx形成机制进行了数值研究。 DCFB 由一个在降低温度下释放燃料-N 的鼓泡流化床 (BFB) 和一个用于燃烧残炭的循环流化床 (CFB) 组成。采用稠密离散相模型与颗粒流动力学理论耦合（DDPM-KTGF）模型来确定DCFB的气固流动特性，并使用具有详细化学反应机制的一维化学反应网络（1D-CRN）来了解其NOx形成机制。结果表明，DCFB的CFB密相中床层颗粒混合良好，稀相中床层颗粒呈现典型的“环芯”结构，床层物料流化质量良好。同时，BFB中尺寸大于0.1毫米的循环灰会通过设计的溢流口，使BFB质量流至CFB。对NOx形成的研究表明，与O/O2和挥发性N缔合的R398、R1-N-1、R569和R17等反应会促进DCFB中NOx的形成，而与NH2、烟灰和炭缔合的反应主要是R411、R570、R571、R5和R6抑制NOx的形成。经计算，DCFB炉膛出口NOx排放总量为97.29 mg/Nm3，比同配置的传统CFB降低了56.66%。因此，新颖的 DCFB 设计将燃料 N 释放和焦炭燃烧分开，为控制 CFB 燃烧期间的 NOx 排放提供了另一种方法。
The gas-solid flow characteristics and fuel NOxformation mechanisms in a novel full-scale Dual Circulating Fluidized Bed (DCFB) was numerically studied. The DCFB was comprised of a bubbling fluidized bed (BFB) at reducing temperature for the release of fuel-N and a circulating fluidized bed (CFB) for combustion of the residue char. A dense discrete phase model coupled with kinetic theory of granular flow (DDPM-KTGF) model was used to determine the gas-solid flow characteristics of the DCFB, and a one-dimensional chemical reaction network (1D-CRN) with detailed chemical reaction mechanisms was used for understanding its NOxformation mechanisms. Results showed that bed particles in the CFB dense phase of DCFB were well-mixed and showed a typical “ring-core” structure in the dilute phase, proving good fluidization quality of bed materials. Meanwhile, circulation ash in BFB with sizes lager than 0.1 mm would pass through the designed overflow port, allowing mass flow from BFB to CFB. Investigation into NOxformation revealed that reactions such as R398, R1-N-1, R569, and R17 associating with O/O2and volatile N would promote NOxformation in DCFB, whereas reactions mainly R411, R570, R571, R5, and R6 associating with NH2, soot, and char inhibited NOxformation. The overall NOxemission at the furnace outlet of DCFB was calculated to be 97.29 mg/Nm3, which was 56.66% lower than that in traditional CFB with the same configuration. Consequently, the novel DCFB design that separating fuel-N release and char combustion provides an alternative means for manipulating NOxemission during CFB combustion.