流化—移动组合床的流体力学与传热特性研究

发布时间：2018-02-27 07:48

  本文关键词： 组合床 传热 关联式　出处：《大连理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：流化—移动组合床是将流化床和移动床相结合,充分利用流化床的高效传热和移动床的连续操作特性。本文通过实验研究和分析组合床的流体力学和传热特性。本研究首先以玻璃珠为物料进行流体力学和传热特性实验研究,从流化状态和传热系数来考察流化床的分级和传热效果。实验从颗粒粒径、分级效率、床层高度、临界流化气速等因素方面来研究组合床中玻璃珠的流体力学特性。颗粒粒径增大,临界流化速度随着增大,压降随床层高度增高而变大。随操作气速的增大,床层的分级效率先上升,达到一个最大值后下降。气速在一定范围内,随气速增高,床层的扬析量成指数增长,但分级效率降低。在传热实验中,从气速、空气温度、粒径和床层高度等角度来考察气固传热系数的变化。通过对流化-移动组合床的传热过程正交分析得到气-固传热的经验关联式：流化部分：移动部分：在玻璃珠的流体力学实验基础上进行煤的干燥实验。从操作气速、空气温度和床层移动速率等方面研究煤的干燥过程。煤的干燥过程分为恒速干燥阶段和降速干燥阶段,床层的温度在恒速干燥阶段变化较小。随操作气速和空气入口温度的增加,组合床的干燥速率加快。并且在不同的温度和气速下,煤的平衡含水量发生改变。当空气温度为120℃、流量为32m3/h时,煤的临界含水量在2%左右。
[Abstract]:Fluidized moving combined bed is a combination of fluidized bed and moving bed. Taking full advantage of the high efficiency heat transfer of fluidized bed and the continuous operation characteristics of moving bed, the hydrodynamics and heat transfer characteristics of the combined bed are studied and analyzed experimentally in this paper. Firstly, the hydrodynamics and heat transfer characteristics of the composite bed are studied experimentally with glass beads as the material. The classification and heat transfer effect of fluidized bed are investigated from fluidized bed state and heat transfer coefficient. The experimental results are as follows: particle size, fractionation efficiency, bed height, The hydrodynamic properties of glass beads in the combined bed are studied in terms of critical fluidization gas velocity and other factors. The particle size increases, the critical fluidization velocity increases, the pressure drop increases with the increase of bed height, and with the increase of operating gas velocity, The fractionation efficiency of the bed increased first, reached a maximum and then decreased. The gas velocity increased exponentially with the increase of the gas velocity, but the fractionation efficiency decreased. In the heat transfer experiment, the gas velocity, the air temperature, The change of gas-solid heat transfer coefficient was investigated from the angles of particle size and bed height. The empirical correlation of gas-solid heat transfer was obtained by orthogonal analysis of fluid-moving combined bed heat transfer process: fluidized part: moving part: in glass. On the basis of the hydrodynamic experiment of bead, the drying experiment of coal was carried out. The drying process of coal is studied in the aspects of air temperature and bed moving rate. The drying process of coal is divided into constant drying stage and decreasing drying stage. The drying rate of the combined bed increased with the increase of operating gas velocity and air inlet temperature, and the drying rate of the combined bed increased at different temperatures and gas velocities. When the air temperature is 120 鈩，

本文编号：1541777