PDF《提升管送风特性对充分发展段压降影响的实验及模型研究*》

第27 卷第

5 期电站系统工程Vol.

27 No.5

2011 年9月Power System Engineering

5 文章编号:1005-006X(2011)05-0005-03 提升管送风特性对充分发展段压降影响的实验及模型研究* 华北电力大学能源与动力工程学院 陈鸿伟 祁海波 梁占伟 杨新摘要:双循环流化床提升管床降随着固气质量比的增加而增加.搭建了双循环流化床实验台,系统地分析了提升管送风特性对充分 发展段压降的影响规律. 结果发现: 充分发展段压降随着提升管风速的增加逐渐增大;

径向送入二次风产生的压降比风口切向布置时大;

风口高度较低时产生的压降较大;

随着二次风口数目增加,压降有增加趋势,设置的

4 种情况下实测压降平均变化率分别为 12.28%、 2.76%、13.16%和6.96%.建立了提升管充分发展段压降模型,计算发现:实测压降与计算值存在偏差,风口数目影响下二者的偏差较 小,平均相对误差仅为 3.13%,最大相对误差 3.95%,风口高度影响下差距较大,平均相对误差为 4.27%,最大相对误差为 5.36%. 关键词:提升管;

送风特性;

充分发展段;

压降;

模型 中图分类号:TK229.6+

6 文献标识码:A Research on Effect of Air Characteristics to Riser of DCFB on Pressure Drop of Fully Developed Zone and Prediction Model CHEN Hong-wei, QI Hai-bo, LIANG Zhan-wei, YANG Xin Abstract:Pressure drop in a double circulating fluidized bed riser increased with the solid-gas mass ratio. A DCFB cold-state test bench and a pressure drop model were set up. This paper systematically tested the gas-solid flow pressure drop in fully developed zone affected by air characteristics. It shows that the pressure drop increased with the gas velocity of the riser and the same trend was found when the number of tuyeres increased. The drop was greater when the tuyeres were tangential arranged than it was radial arranged. The pressure gradient emerged a bigger drop when the tuyeres were lower from the distribution. The mean change rate was 12.28%, 2.76%, 13.16% and 6.96%, respectively in the four circumstances that the paper set. It shows that the tested value had a gap with the value calculated by model in fully developed zone, and the gap differ from affected factors. It showed a lower discrepancy affected by numbers of tuyeres, the mean relative error is 3.13% and the maximum relative error is 3.95%. But the mean relative error and the maximum relative error is comparatively larger affected by heights of tuyeres, which are 4.27% and 5.36%, respectively. Key words: riser;

characteristics of air supply model;

fully developed zone;

pressure gradient;

model 双循环流化床具有高效燃烧、 低污染及燃料适应性广等 优点,在煤燃烧、气化、生物质利用及垃圾处理领域得到了 广泛的应用[1] .双循环流化床最复杂的燃烧过程发生在快速 流化床(提升管)内,掌握提升管内颗粒浓度的分布特性, 对组织床内物料较好地掺混燃烧、 控制实现高效传热传质非 常重要[2] .压力梯度是提升管的重要参数之一,它能很好地 反映提升管内的物料流动状态及颗粒分布规律, 对改善管内 传热传质有一定的实际意义. 快速流化床按流动状态划分为加速段、 充分发展段和减 速段.加速段随着操作气速的不同约占据提升管高度的 1/3~2/3,该区域颗粒掺混剧烈,气流扰动强烈,实测压降 与计算值有较大偏差.充分发展段则流动相对稳定,气固滑 移速度接近零,两相加速效应可以忽略,实测压降与计算值 的偏差主要是气固两相与管壁间的摩擦产生的. 减速段在出 口速度变化较剧烈的提升管内是切实存在的, 本试验台提升 管出口导管采用圆弧状过渡,速度变化较为平缓,因此,减 速段忽略不计.已经有研究者[3~4] 发现,在提升管上部充分 发展段摩擦产生的压降占到总压降的 20%~50%, 且随着操 作气速的增加,所占比例有增大的趋势.由于充分发展段参 收稿日期:2011-05-02 陈鸿伟(1965-),男,教授,博士生导师.保定,071003 *国家自然科学基金(50876030);