颗粒内部和固定床反应耦合过程的生物质燃烧数值模拟

Simulation of Biomass Combustion by Coupling Particles Interior and Fixed Bed Reaction

为研究成型颗粒在固定床内燃烧过程,提出了一种单颗粒与固定床结合的模型,将固定床视作由颗粒堆积的反应器,考虑了床层以及颗粒内部气体扩散,考虑生物质颗粒干燥、热解和固定碳燃烧过程。结果表明:模型准确地预测了生物质颗粒燃尽时间和热解过程的温度变化,在1223K条件下颗粒完全燃烧约需要150s,最高温度可达1720K;模型能准确预测固定床的燃烧过程,发现固定床内高温区温度远低于单颗粒燃烧可达到的最高温度,床内生物质颗粒燃尽时间比热空气中单颗粒燃尽时间长34.9%。该模型为深入研究固定床提供了有力工具。

In order to study the combustion process of formed particles in fixed bed,a model combining single particles and fixed bed is proposed in this paper.The fixed bed is regarded as a reactor formed by particles accumulation.The gas diffusion inside the particles and the bed are considered,as well as the drying,pyrolysis and fixed carbon combustion process of biomass particles.The results show that:the model accurately predicts the temperature change of particle pyrolysis and burnout time of combustion process.Under the temperature condition of 1223K,the complete combustion of particles needs about 150s,and the maximum temperature reaches 1720K.The model also accurately predicts the combustion process of a fixed bed.It is found that the temperature in the fixed bed is far lower than the maximum temperature that can be reached by single particle combustion,and the burnout time of particles in the bed is 34.9%longer than that of single particles in hot air.This model provides a powerful tool for further study of fixed bed.