Clean Coal Technology

2022, v.28;No.142(06) 143-149

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兰炭循环流化床锅炉燃烧性能模型
Combustion performance of a semi-coke fired circulating fluidized bed boiler based on CFB model

李静渊;柯希玮;蒋苓;黄中;张缦;
LI Jingyuan;KE Xiwei;JIANG Ling;HUANG Zhong;ZHANG Man;Department of Energy and Power Engineering,Tsinghua University;

摘要(Abstract):

兰炭具有挥发分含量低、固定碳含量高的特点,与煤粉炉相比,循环流化床(CFB)锅炉更适合用于兰炭燃烧。为了解兰炭循环流化床(CFB)锅炉的燃烧性能,利用一维循环流化床锅炉模型对兰炭CFB锅炉进行了模拟。通过对比循环灰和底渣的粒径分布模型预测与现场取样测量结果,发现二者吻合良好,验证了锅炉整体模型的合理性和准确性。通过模型分析了分离器效率、给煤粒径对兰炭CFB锅炉的影响。模拟结果表明,提高分离器效率使兰炭燃烧更加充分,建议将飞灰中位粒径控制在10μm左右。给煤粒径对兰炭CFB锅炉有重要影响,给煤粒径减小导致燃烧效率略下降,同时NO_x排放量明显减少。针对兰炭成灰特性合理设计给煤粒径分布,建议将给煤粒径控制在0.5~6.0 mm为宜。通过与燃烧褐煤的循环流化床进行对比,发现燃烧兰炭时炉内温度高于燃烧褐煤,燃烧效率低于褐煤,SO_2和NO_x排放量均较低,但仍需通过烟气脱硝来满足污染物排放需求。利用模型的定量研究为兰炭CFB锅炉的运行优化提供了方向。
Semi-coke has the characteristics of low volatile matter and high fixed carbon. Compared with pulverized coal boiler, circulating fluidized bed(CFB) boiler is more suitable for semi-coke combustion. In order to understand the combustion performance of the circulating fluidized bed boiler for semi-coke, the one-dimensional circulating fluidized bed boiler model was used to simulate a CFB boiler for semi-coke. By comparing the model prediction of particle size distribution of circulating ash and bottom slag with the measurement results of field sampling, the two match well and verify the reasonableness and accuracy of the overall boiler model. Through simulation, the effects of cyclone efficiency and semi-coke particle size on semi-coke CFB boiler were analyzed. The simulation results show that the cyclone efficiency has a very significant impact on the performance of semi-coke fired circulating fluidized bed. Improving the cyclone efficiency can increase combustion efficiency of semi-coke, and median particle size of fly ash is recommended to be controlled around 10 μm.Feed coal particle size has an important effect on the CFB boiler of semi-coke. The combustion efficiency is decreased by reducing the semi-coke particle size, and NO_x emission can be reduced significantly.According to the ash formation characteristics of semi-coke, the inject particle size should be in the range of 0.5-6.0 mm.Comparing with the circulating fluidized bed boiler burning lignite, the temperature in the furnace is higher when burns semi-coke, and the combustion efficiency is lower. Both SO_2 emission and NO_x emissions in the combustion process of semi-coke are low, but it still needs flue gas denitrification systems to meet the pollutant emissions. All above results provide a direction for the operation optimization of CFB boiler that fires semi-coke.

关键词(KeyWords): 兰炭;循环流化床;一维模型;燃烧性能;运行优化;烟气脱硝
semi-coke;circulating fluidized bed;one-dimensional model;combustion performance;operation optimization;flue gas denitrification

Abstract:

Keywords:

基金项目(Foundation): 山西省科技重大专项资助项目(20181102001)

作者(Authors): 李静渊;柯希玮;蒋苓;黄中;张缦;
LI Jingyuan;KE Xiwei;JIANG Ling;HUANG Zhong;ZHANG Man;Department of Energy and Power Engineering,Tsinghua University;

DOI: 10.13226/j.issn.1006-6772.21050702

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