Faculty of Mechanical Engineering, University of Maribor, Maribor, Slovenia.
Department of Energy Technology, Aalborg University, Aalborg East, Denmark.
J Environ Manage. 2018 Jul 15;218:200-208. doi: 10.1016/j.jenvman.2018.04.030. Epub 2018 Apr 19.
Grate-fired boilers are commonly used to burn biomass/wastes for heat and power production. In spite of the recent breakthrough in integration of advanced secondary air systems in grate boilers, grate-firing technology needs to be advanced for higher efficiency and lower emissions. In this paper, innovative staging of combustion air and recycled flue gas in a 13 MW waste wood-fired grate boiler is comprehensively studied based on a numerical model that has been previously validated. In particular, the effects of the jet momentum, position and orientation of the combustion air and recycled flue gas streams on in-furnace mixing, combustion and pollutant emissions from the boiler are examined. It is found that the optimized air and recycled flue gas jets remarkably enhance mixing and heat transfer, result in a more uniform temperature and velocity distribution, extend the residence time of the combustibles in the hot zone and improve burnout in the boiler. Optimizing the air and recycled flue gas jet configuration can reduce carbon monoxide emission from the boiler by up to 86%, from the current 41.0 ppm to 5.7 ppm. The findings of this study can serve as useful guidelines for novel design and optimization of the combustion air supply and flue gas recycling for grate boilers of this type.
炉排炉常用于燃烧生物质/废物以产生热能和电力。尽管在将先进的二次空气系统集成到炉排锅炉方面取得了最新突破，但为了提高效率和降低排放，炉排燃烧技术仍需要进一步改进。本文基于先前经过验证的数值模型，全面研究了在 13MW 废木屑燃烧炉排锅炉中对燃烧空气和再循环烟气进行创新分段的问题。特别研究了燃烧空气和再循环烟气射流的动量、位置和方向对锅炉内混合、燃烧和污染物排放的影响。结果表明，优化后的空气和再循环烟气射流可显著增强混合和传热效果，使温度和速度分布更加均匀，延长可燃物在高温区的停留时间，并提高锅炉的燃烧效率。优化空气和再循环烟气射流配置可以将锅炉的一氧化碳排放量从目前的 41.0ppm 降低到 5.7ppm，降幅高达 86%。本研究的结果可为这种类型的炉排锅炉的新型燃烧空气供应和烟气再循环设计与优化提供有用的指导。
