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  本文選題：MVR + 耙式干燥　； 參考：《浙江工業(yè)大學》2017年碩士論文

【摘要】：干燥一般是指通過直接或間接的方式傳遞能量(通常是熱量)給濕物料,使其中的濕分(大多數(shù)情況下為水)產(chǎn)生相變與物料分離,從而獲得一定濕含量固體產(chǎn)品的過程。干燥過程的能耗與濕分的相變熱、傳熱傳質和能量回收方式等因素有關。由于濕分(尤其是水)的相變熱較大,導致脫濕需要消耗的能量較大。運用MVR(機械蒸汽再壓縮)技術,回收干燥過程脫除的濕分(二次蒸汽)的相變熱(冷凝熱),有顯著的節(jié)能效果。傳統(tǒng)的耙式干燥系統(tǒng)用蒸汽等為熱源間接加熱物料并在真空條件下脫濕,尾氣經(jīng)過濾、冷凝除濕后由真空泵排出。本文將MVR技術應用于耙式干燥系統(tǒng),提出用羅茨蒸汽壓縮機替換該系統(tǒng)中的真空泵,將干燥過程脫出的濕分(二次蒸汽)壓縮以提高壓力和溫度,再經(jīng)增濕(消除過熱)和補充少量生蒸汽后作為熱源使用。不僅節(jié)省了大量熱能,還節(jié)省了冷量,節(jié)能效果顯著。該系統(tǒng)特別適合熱敏性、易氧化和濕分須回收的物料的干燥。被干燥物料可以是粉粒狀、膏狀、漿狀,也可以是溶液(此時包含蒸發(fā)、結晶和干燥過程)。本文提出了MVR耙式干燥系統(tǒng)工藝流程;設計了實驗裝置的工藝流程,進行了物料熱量衡算和主要設備工藝計算,繪制了帶控制點工藝流程圖、耙式干燥機和絲網(wǎng)除沫器裝配圖和設備管道布置圖,搭建了MVR耙式干燥實驗裝置。分別以水和碳酸鈉溶液為對象,實驗研究了干燥壓力、壓縮比、耙軸轉速、過熱度、物料初始含水率、填充率等對過程COP和SMER的影響。結果表明:在實驗條件范圍內(nèi),選擇適當?shù)偷母稍飰毫Α⑦m當小的壓縮比、適中的轉軸速率、控制蒸汽過熱度均有利于提高系統(tǒng)的運行效率。以水為對象時,COP為4.4~8.8,SMER為2.0~3.4 kg/(kW·h);以碳酸鈉溶液為對象時,COP為3.1~7.3,SMER為1.2~2.8 kg/(kW·h)。節(jié)能效果明顯優(yōu)于傳統(tǒng)耙式干燥機。研究結果對MVR耙式干燥系統(tǒng)的應用有參考意義。
[Abstract]:Drying generally refers to the process of transferring energy (usually heat) directly or indirectly to the wet material, which makes the wet fraction (in most cases water) produce phase transition and material separation, thus obtaining a certain amount of wet solid product. The energy consumption of drying process is related to the heat of phase change, heat and mass transfer and energy recovery. Due to the large phase change heat of wet fraction (especially water), the dehumidification needs a large amount of energy. By using MVR( Mechanical Vapor recompression) technology, the phase change heat (condensation heat) of wet fraction (secondary steam) removed during drying process is recovered, which has remarkable energy saving effect. In the traditional rake drying system, steam is used as heat source to heat the material indirectly and dehumidify under vacuum condition. The tail gas is filtered, condensed and dehumidified, then discharged by vacuum pump. In this paper, the MVR technology is applied to the rake drying system. The vacuum pump in the system is replaced by a Roots steam compressor, and the wet fraction (secondary steam) released from the drying process is compressed to increase the pressure and temperature. After humidifying (eliminating overheating) and adding a small amount of steam, it can be used as heat source. Not only save a lot of heat energy, but also save the cooling capacity, energy saving effect is remarkable. The system is especially suitable for drying materials with heat sensitivity, easy oxidation and moisture separation to be recovered. Dried material can be powdered, paste, paste, or solution (this includes evaporation, crystallization, and drying processes). In this paper, the process flow of MVR rake drying system is put forward, the process flow of the experimental device is designed, the heat balance of material and the technological calculation of main equipment are carried out, and the process flow chart with control point is drawn. The assembly drawing of rake dryer and screen defoaming device and the layout drawing of equipment pipe were used to build MVR rake drying experimental device. The effects of drying pressure, compression ratio, speed of rake shaft, superheat, initial moisture content of material and filling ratio on COP and SMER were studied. The results show that, in the range of experimental conditions, choosing proper low drying pressure, proper compression ratio, moderate rotating shaft rate and controlling steam superheat are all beneficial to improve the operation efficiency of the system. The cop of water and sodium carbonate solution was 4. 4 and 2. 4 kg/(kW / h, respectively, and that of sodium carbonate solution was 3. 1 7. 3 and 1. 2. 8 kg/(kW / h respectively. The energy saving effect is obviously superior to the traditional rake dryer. The results are useful for the application of MVR rake drying system.
【學位授予單位】：浙江工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TQ051.892

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