摘要
以某台220t/h煤粉锅炉为研究对象,对选择性非催化还原过程中尿素溶液还原剂与烟气的混合问题进行数值研究.计算表明,还原剂液滴喷入炉内1 100℃左右的高温区后,迅速经历加热、沸腾和蒸发过程,液滴的停留时间很短,因此增加还原剂射流穿透深度可有效提高混合程度.以还原剂质量分数的相对标准偏差为混合程度的衡量指标,分析了还原剂喷射速度、流量、液滴粒径以及锅炉等因素的影响,发现降低锅炉负荷、提高还原剂喷射速度和流量均可有效提高混合程度,而液滴粒径对混合具有双重影响,一般存在最佳粒径范围.
The mixing characteristics of urea reducing agents and flue gas in the SNCR process of a 220 t/h coal-fired boiler were numerically studied.The calculation showed that the urea solution experienced heating,boiling and evaporation quickly after being injected into a high temperature zone of 1,100 ℃.The residence times of reducing agent droplets were short,so increasing the penetration depth could enhance the mixing degree.The influences of the reducing agent injection velocity,the flow rate of reducing agents,the droplet size and the boiler load were investigated.The relative standard deviation of urea concentration was used to evaluate the mixing degree.The results show that the mixing degree is enhanced by increasing the injection velocity and the flow rate of reducing agents and by decreasing the boiler load.The droplet size has a double influence on the mixing degree.Usually,an optimum range of droplet size exists for effective mixing.
出处
《中国计量学院学报》
2012年第2期198-202,共5页
Journal of China Jiliang University
