MVR热泵干燥系统建立和恒速段的实验研究

发布时间：2018-03-09 00:25

  本文选题：MVR　切入点：空心桨叶干燥机　出处：《浙江工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：干燥是固液分离过程常用的单元操作,但普遍存在热效率低、能耗高的问题。随着世界能源危机日益加重,提高能源利用率,设计开发新型低能耗的干燥系统迫在眉睫。MVR技术利用压缩机向蒸发产生的二次蒸汽输入一定量的功,将二次蒸汽压缩到加热蒸汽的热力状态再循环利用。系统仅需消耗少量电能,且工艺简单、操作成本低、维护方便,在海水淡化、蒸发浓缩等工业领域已经成熟运用,节能效果显著。但MVR技术在干燥领域的应用和研究较少。本文将MVR技术应用于传导型干燥机,做了以下工作:提出了基于空心桨叶干燥机的MVR热泵干燥系统。对系统进行了能量平衡和质量平衡过程分析,并对MVR系统热力过程进行了初步理论分析和计算。模拟计算了干燥压力为80 kPa,压缩比为2的状况,结果表明:系统压缩单位工质的耗功仅为311 k J/kg,但可回收利用的冷凝潜热达到2346 kJ/kg,二次蒸汽温度提高了19.9℃,回收利用的热量与输入功的热功比达7.54,能源利用效率大幅提升;模拟计算了同一干燥压力不同压缩比,以及相同压缩比不同干燥压力下热泵系统性能的变化规律,结果表明:同一干燥压力下,随着压缩比的增加,MVR热泵干燥系统的COP和SMER均随着压缩比的增加而减小,且随着压缩比的增加,下降趋势变缓;在相同的压缩比下,随着干燥压力的增加,热泵的性能系数增加不明显。设计并建立了处理量为50 kg污泥/h的MVR热泵空心桨叶干燥系统。计算选用了JY-003型空心桨叶干燥机和罗茨压缩机,设计了进料机和丝网除沫器,对辅助装置进行了选型。并对MVR热泵干燥系统进行了安装和调试。采用该实验系统对污泥间歇干燥的恒速阶段进行了实验研究。结果表明:在污泥初始湿含量75%,质量为120 kg,热轴转速11.3 r/min的工况下,干燥压力80 k Pa,压缩比从1.5增加到1.9,COP从5.3降到3.9,SMER从6.9降到5.2 kg/(kW·h),参照目前的蒸汽电价比,在干燥的恒速段,使用MVR热泵系统进行干燥,具有很高的实际价值。在干燥污泥的恒速段,降低干燥压力、适当减小压缩比、选择合适的热轴转速均有利于提高系统的运行效率;提出了优化MVR热泵干燥系统主要有两个方向:一是提高压缩机的效率,二是增强干燥机的传热性能。研究结果对促进MVR技术在干燥中的应用有一定的理论意义和工程应用价值。
[Abstract]:Drying is a common unit operation in solid-liquid separation process, but there are many problems such as low thermal efficiency and high energy consumption. It is urgent to design and develop a new low energy consumption drying system. MVR technology uses the compressor to input a certain amount of work into the secondary steam generated by evaporation. The secondary steam is compressed to the thermal state of heating steam for recirculation and utilization. The system only needs a small amount of electric energy, and the process is simple, the operation cost is low, the maintenance is convenient, and the system has been mature and applied in the industrial fields such as seawater desalination, evaporation and concentration, etc. The energy saving effect is remarkable, but the application and research of MVR technology in drying field are few. In this paper, MVR technology is applied to conductive dryer, The following works are done: a MVR heat pump drying system based on hollow blade dryer is proposed. The energy balance and mass balance process of the system are analyzed. A preliminary theoretical analysis and calculation of the thermodynamic process of the MVR system are carried out. The drying pressure is 80 KPA and the compression ratio is 2. The results show that the energy consumption per unit of the system is only 311 KJ / kg, but the recoverable latent condensate heat is 2346 KJ / kg, the secondary steam temperature is increased by 19.9 鈩，

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