水泥熟料篦冷机料层阻力及冷却换热的实验研究

发布时间：2018-02-17 06:13

  本文关键词： 篦冷机 料层阻力 流态化 冷却 换热　出处：《西南科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：篦冷机是水泥熟料生产线的核心设备,回收热量的多少和热风品位的好坏,直接影响着整条窑系统的稳定性和能耗的高低。目前,大部分研究都集中于通过计算机模拟熟料的冷却换热,对生产具有一定的指导作用。但由于实际工况的复杂性和不确定性,并不能反映出目前篦冷机存在的问题,具有一定的局限性。本文采用缩小篦冷机进行小型工程实验的方法,对不同篦下风速、不同熟料粒径、不同料层厚度下的料层阻力和冷却换热情况,分别进行冷态实验和热态实验,并对目前生产过程中篦冷机出现的篦缝过宽、粗细料离析、飞砂等不良现象进行实验验证、分析。主要研究结论如下:(1)对不同粒径熟料的测试中发现,随着熟料粒径的变小,料层阻力逐渐增加。空隙率是料层阻力的最大影响因数,采用欧根公式对篦冷机实际料层阻力进行计算的方法,并不能准确的估算出料层的阻力。通过对不同粒径的熟料进行反复实验,归纳出了能够比较准确估算料层阻力的经验公式。(2)在料层高度方向上,料层阻力分布并不相同,底部料层的阻力大于上部相同厚度的料层,并找到了相关的两方面原因。实际生产中,设计篦板和匹配风机时都应考虑。(3)飞砂料的流态化特征完全符合气固系统的非均一流态化,实验得出飞砂料流态化速度为0.38m/s,较理论计算值偏小,并绘制出了ΔP~u曲线;采用阿基米德准数计算的流态化速度和流态化极限速度,与实际测试值比较接近。(4)在一定范围内,增加篦下风速有利于空气与熟料的换热。熟料Φ20-31.5mm、温度850℃的条件下,风速1.17m/s增加至1.29m/s,有利于熟料的换热,超过1.29m/s后,作用不再明显;熟料颗粒的粒径是影响综合换热系数的重要因数,粒径越小,换热越快。但冷却初始阶段,熟料表层温度高,与冷却空气的温差较大,冷却速率基本相同。(5)在篦板通风面积2.48%、熟料Φ20-31.5mm、料层200mm的条件下,3mm篦缝造成熟料冷却速度明显降低,空气温度下降31℃;对粗、细料离析的测试中发现Φ10-16mm+Φ20-31.5mm实验组冷却换热后的空气温度比Φ5-10mm+Φ20-31.5mm实验组温度高出71℃。篦板缝隙和颗粒离析是造成冷却空气严重分布不均,二、三次风温度偏低的最主要原因。
[Abstract]:Grate cooler is the core equipment of cement clinker production line. The quantity of heat recovered and the grade of hot air directly affect the stability and energy consumption of the whole kiln system. Most of the research is focused on simulating the cooling and heat transfer of clinker by computer, which can guide the production to some extent. However, because of the complexity and uncertainty of the actual working conditions, it can not reflect the problems existing in the grate cooler at present. There are some limitations. In this paper, the resistance and cooling heat transfer of the material layer under different grate wind speed, different clinker particle size and different layer thickness are studied by using the method of small-scale engineering experiment with a reduced grate cooler. The cold and hot experiments were carried out respectively, and the bad phenomena such as too wide grate gap, coarse and fine material segregation, flying sand and so on, which appeared in the grate cooler in the current production process, were verified. The main conclusions are as follows: (1) in the test of clinker with different particle size, it is found that the resistance increases with the decrease of clinker particle size, and the porosity is the biggest influence factor of feed layer resistance. The method of calculating the actual layer resistance of grate cooler by using the Eucan formula can not accurately estimate the resistance of the material layer. Through repeated experiments on the clinker with different particle sizes, The empirical formula for estimating the resistance of the material layer accurately is concluded. (2) in the direction of the height of the material layer, the resistance distribution of the layer is different, and the resistance of the bottom layer is greater than that of the upper layer of the same thickness. Two related reasons have been found. In practical production, the fluidization characteristics of fly sand materials should be considered when designing grate plate and matching fan. The fluidization characteristics of fly sand completely accord with the heterogeneous fluidization of gas-solid system. The experimental results show that the fluidization rate of fly sand is 0.38 m / s, which is smaller than that of the theoretical calculation, and the 螖 Pu curve is drawn, and the fluidization velocity and fluidization limit velocity calculated by Archimedes number are close to the actual measured values in a certain range. Under the condition of 桅 20-31.5 mm, temperature 850 鈩，

本文编号：1517411