基于物料品質調控的高溫熔渣余熱回收能質傳輸機理

朱恂 崔素萍 林林 王宏

摘要：本研究組利用高溫熔渣相變冷卻實驗裝置完成了一系列高爐渣顆粒相變冷卻與物性結構演變實驗，獲得了風冷高爐熔渣化學組成對物相結構及活性變化的影響；分析了風冷渣形成工藝參數對其結構及性能的影響；探討了風冷高爐渣的水化性能。結果表明：四元堿度是高爐渣玻璃體含量和7天活性指數的重要影響因素，SiO2/Al2O3比影響28天活性指數，出渣溫度影響玻璃體含量，保溫時間和冷卻風速影響活性指數。高爐渣降低水泥的水化放熱速率，適量結晶對其水硬活性有益。 建立了熔渣顆粒相變冷卻的傳熱模型，應用溫度法模型、VOF方法和凝固/熔化模型及輻射模型，研究了換熱條件、流體溫度、顆粒變物性和顆粒尺寸等對顆粒相變冷卻換熱的影響規律，獲得顆粒凝固的相變動態過程及不同組合工況下的顆粒凝固時間。提出了在空氣冷卻基礎上輔以噴霧冷卻的轉杯粒化干式余熱回收新方法，并對噴霧冷卻過程中單個液滴撞擊固壁機理進行了實驗研究和數值模擬。結果表明：熔渣顆粒內部的冷卻速率存在較大差異，粒徑是影響顆粒換熱的關鍵因素；換熱系數在橫向直徑處、迎風滯止處及背風面回流處獲得較大值。 搭建了液態物料離心粒化特性可視化實驗臺，前期以水為工質研究了轉杯粒化過程中液滴的形成機理，獲得了液滴形態及分布等信息，探討了轉杯轉速、工質流量、轉杯結構對粒化液滴的粒徑分布和平均粒徑的影響規律，結果表明：高轉速和小流量下液滴直徑小；淺和小內傾角轉杯粒化效果較好。 搭建了高爐渣離心粒化余熱回收系統，擬在此基礎上深入研究熔渣顆粒形成機理、顆粒運動及流化特性、氣固換熱特性以及顆粒最終物相品質等相關問題，揭示各相關因素對熔渣顆粒的影響規律以及獲得兼顧余熱回收和物料品質的系統運行最佳工況。

關鍵詞：高溫熔渣；干式粒化；相變換熱；余熱回收；品質調控

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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