【摘要】 本文对Krupp型正银缩口的水泥生料预热器的工作原理,包括喷射气体的流型、物料在立筒内运动过程、落料的分散、气固两相在立筒内的传热方式与速率、气固分离以及物料在立筒内停留时间的概率分布等实质性问题,在理论分析和模型试验的基础上进行了比较深入的探讨,修正了过去将立筒预热器归入逆流换热类型的传统看法。明确指出立筒是以同流为主的多级换热设备,并归纳出若干基本认识和概念。基于这些新概念,作者还对立筒预热器的操作和结构改进提出了一些看法。更多还原

【Abstract】 On the basis of the theoretical analysis and model test, a through study was made on the working principle of Krupp suspension preheater for cement raw meal with nozzle type construction, including jet stream pattern, process of raw meal motion, dispersion of falling lumps, mode and rate of heat transfer, gas-solid separation and probable distribution of residence time of raw meal in the shaft etc. Practical measu.rements show that the velocity pattern of jet stream in a much limited space remains the characteristics of Gausses distribution and can be divided into four regions of core, spout, vortex and back flow, and each region plays a different role in particlar motion. The process of raw meal motion in a compartment may be depicted as a clear physical model of "dispersion-separation-piling-slipping" through practical observation and measurements by the aid of high speed photography. Theoretical derivation and experiments turn out that the rate of transient convective heat transfer is more effective and heat exchange mainly takes place in the core region. Therefore gas-solid heat exchange in Krupp preheater is carried out in co-current mode, which corrects the traditional view point that shaft was considered a counter-current heat exchanger. Meanwhile, comparison between stream line illustration and distribution diagram of powder concentration indicates that separation function of gas-solid in a compartment is due to the existence of the circular vortex. Practical measurements show that the radical vetosity in the shaft is one order of magnitude smaller than tangential velosity in cyclone.Based on above research results, a new and fairly complete working principle of Krupp preheater is created. The authors also put forward some views to improve the operation and construction of Krupp preheater, which may be of value in production, design and development.更多还原