基于物料品质调控的高温熔渣余热回收能质传输机理

朱恂 崔素萍 林林 王宏

摘要：本研究组利用高温熔渣相变冷却实验装置完成了一系列高炉渣颗粒相变冷却与物性结构演变实验，获得了风冷高炉熔渣化学组成对物相结构及活性变化的影响；分析了风冷渣形成工艺参数对其结构及性能的影响；探讨了风冷高炉渣的水化性能。结果表明：四元碱度是高炉渣玻璃体含量和7天活性指数的重要影响因素，SiO2/Al2O3比影响28天活性指数，出渣温度影响玻璃体含量，保温时间和冷却风速影响活性指数。高炉渣降低水泥的水化放热速率，适量结晶对其水硬活性有益。 建立了熔渣颗粒相变冷却的传热模型，应用温度法模型、VOF方法和凝固/熔化模型及辐射模型，研究了换热条件、流体温度、颗粒变物性和颗粒尺寸等对颗粒相变冷却换热的影响规律，获得颗粒凝固的相变动态过程及不同组合工况下的颗粒凝固时间。提出了在空气冷却基础上辅以喷雾冷却的转杯粒化干式余热回收新方法，并对喷雾冷却过程中单个液滴撞击固壁机理进行了实验研究和数值模拟。结果表明：熔渣颗粒内部的冷却速率存在较大差异，粒径是影响颗粒换热的关键因素；换热系数在横向直径处、迎风滞止处及背风面回流处获得较大值。 搭建了液态物料离心粒化特性可视化实验台，前期以水为工质研究了转杯粒化过程中液滴的形成机理，获得了液滴形态及分布等信息，探讨了转杯转速、工质流量、转杯结构对粒化液滴的粒径分布和平均粒径的影响规律，结果表明：高转速和小流量下液滴直径小；浅和小内倾角转杯粒化效果较好。 搭建了高炉渣离心粒化余热回收系统，拟在此基础上深入研究熔渣颗粒形成机理、颗粒运动及流化特性、气固换热特性以及颗粒最终物相品质等相关问题，揭示各相关因素对熔渣颗粒的影响规律以及获得兼顾余热回收和物料品质的系统运行最佳工况。

关键词：高温熔渣；干式粒化；相变换热；余热回收；品质调控

Energy and mass transfer mechanism of waste heat recovery from high temperature molten slag coupled material quality regulation

Abstract：Molten slag， as a kind of by-product during the steelmaking process， is exhausted in extremely high temperature and thus， it carries a great deal of high-grade heat. Dry granulation refers to recover the waste heat of slag by air， it can achieved the purpose of energy conservation and emissions reduction and overcome the disadvantages of the water quenching method. Compared with other dry granulating methods， rotating cup atomizer method attracts more attention， because of its compact and simple structure and the high utilization value of the cold slag. But this technique is in the research and development stage. In order to make it use in industrial application， the key scientific problems of the rotating cup atomizer method were studied systematically. A series of experiments towards phase change coolingand physical structure evolution of blast furnace slag particles have been completed. The influence rule of air-cooled blast furnace slag chemical compositionon the structure and activity of slag has been obtained. The studies on effect of air-cooled slag formation process parameters on the structure and properties have basically been completed， and the studies on hydration propertiesof air-cooled blast furnace slag have made some progress. In order to explore the affect rulesof internal cooling rate on phase change heat transfer and phase structural evolutionof the slag， a phase change coolingvisualexperiment system of high-temperatureslag has been built， and the mathematical model of phase changeheat transfer cooling process of slag particles has also been established. By application of temperature method model， VOF method and freeze/thaw model， the influencing mechanism of heat transfer conditions， fluid temperature， radiation heat transfer， variable propertiesand particle size on the phase change heat transfer of slag particle is studied. In addition， a new air coolingtechnique combined spray cooling is proposed， and the mechanism of a single droplet impact solid wall in the spray cooling process was investigated experimentally. A visual experimental system to investigate characteristics of centrifugal granulation using liquid material has been built. The formation mechanism of the liquid droplets in rotor granulation process was investigated， and how the rotate speed， mass flow rate and rotor structure effect the average size and distribution of granulated droplets have also been discussed.

Keywords：High temperature molten slag， Dry granulation， Phase-change heat transfer， Waste heat recovery， Quality regulation

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