100kW_(th)加压循环流化床富氧燃烧试验研究

Experimental research on oxygen-enriched combustion at 100kW_(th) pressurized circulating fluidized bed

加压循环流化床富氧燃烧技术(PCFB-OFC)是一种新型清洁高效的燃烧技术,其高碳捕获率和低能耗的特点受到广泛关注,具有很好的发展潜力和工业应用前景。受限于燃烧压力升高后带来的问题,现有关于加压循环流化床富氧燃烧的研究多着重于理论建模或基于小型试验台的试验及机理研究。东南大学自主研发了热输入功率为100 kW的加压循环流化床富氧燃烧热态试验装置,实现了加压循环流化床富氧燃烧技术的规模化示范,并获得了热态试验数据和设计及运行经验。试验结果表明,该装置能够实现空气燃烧和富氧燃烧模式的平稳切换,在0.6 MPa压力下循环流化床能够稳定运行,炉内温度变化平稳,并且加压富氧燃烧模式下干烟气中CO_(2)体积分数能够稳定维持在90%以上,达到预期设计目标。燃烧压力的提升加快了化学反应速率并且延长了气体停留时间,再结合2级配风模式,使燃料氮更多的转化为氮气,最终表现出压力升高显著降低尾气中NO和N_(2)O的排放。此外,压力升高提升了燃烧效率,烟气中CO和CH_(4)的体积分数显著降低,并分别在0.4 MPa和0.2 MPa时达到较低体积分数。

The pressurized circulating fluidized bed oxygen-enriched combustion technology(PCFB-OFC)is a new type of clean and efficient combustion technology.Its high carbon capture rate and low energy consumption make it attract wide attention and have a good development potential and industrial application prospects.However,due to problems caused by the increase in combustion pressure,the existing research on pressurized circulating fluidized bed oxygen-enriched combustion focuses more on theoretical modeling,or experiments and mechanisms based on small experimental benches.Southeast University has developed a hot-state experimental device for pressurized circulating fluidized bed oxy-fuel combustion with a heat input power of 100 kW,realized the large-scale demonstration of pressurized circulating fluidized bed oxy-fuel combustion,and obtained some thermal experimental data and design and operation experience.The experimental results show that the device can realize the smooth switching of the two combustion modes,the PCFB can operate stably at a pressure of 0.6 MPa,the temperature in the furnace changes smoothly,and dry flue gas CO_(2)concentration stabilizes above 90%in the POFC mode,achieving the expected design goal.The increase in combustion pressure accelerates the chemical reaction rate and prolongs the gas residence time,causes more fuel-N to be converted into nitrogen combined with the two-stage air distribution mode,and finally shows that the increase in pressure significantly reduces the emission concentration of NO and N_(2)O in the exhaust gas.In addition,the increase in pressure improves the combustion efficiency,significantly reduces the concentration of CO and CH_(4) in the flue gas,and reaches lower concentrations at 0.4 MPa and 0.2 MPa,respectively.