垃圾渗滤液浓缩用MVR蒸发管内CaCO3结垢过程数值分析
收稿日期: 2016-05-13
修回日期: 2016-06-12
网络出版日期: 2016-08-30
基金资助
广东省科技计划项目（2014B050505014）；
佛山市院市合作项目（2014HK100061）
Numerical Analysis on the Process of CaCO3 Fouling of MVR Evaporation Tube for Landfill Leachate Concentration
Received date: 2016-05-13
Revised date: 2016-06-12
Online published: 2016-08-30
基于圆管立式降膜蒸发传热传质的相关理论，建立了其管内CaCO3结垢过程的数学模型，并应用于垃圾渗滤液浓缩用机械蒸汽再压缩（MVR）立式降膜蒸发管内CaCO3结垢过程研究，得到了各结垢参数在不同结垢阶段的变化规律。结果表明：结垢初期，蒸发管内CaCO3的沉积速率远大于剥蚀速率，净存速率较大，污垢层厚度、污垢热阻快速增加，使得蒸发管总传热系数快速减小，进而引起蒸发器的蒸发量、浓缩比快速减小；结垢中期，CaCO3的净存速率变小，污垢增加变缓，各结垢参数变化趋势由急变缓；结垢末期，CaCO3的净存速率趋近于零，污垢不再增加，各结垢参数趋于稳定；相比蒸发管入口，出口液膜溶液的流量小、CaCO3浓度高，结垢更严重，且受整个蒸发管结垢的影响，液膜溶液流量、CaCO3浓度变化较大，各结垢参数变化更迅速，更早趋于稳定。
关键词： 垃圾渗滤液; 浓缩; 机械蒸汽再压缩（MVR）; 蒸发管; CaCO3污垢
杨承志 , 黄 冲 , 冯自平 , 李帅旗 , 何世辉 . 垃圾渗滤液浓缩用MVR蒸发管内CaCO3结垢过程数值分析[J]. 新能源进展, 2016 , 4(4) : 320 -327 . DOI: 10.3969/j.issn.2095-560X.2016.04.009
Based on the related theories of heat and mass transfer in vertical falling film evaporation, the mathematical model of the process of CaCO3 fouling in the tube was established. It was applied to the research on the process of CaCO3 fouling in the vertical drop film evaporation tube of mechanical vapour recompression (MVR) for landfill leachate concentration, and the fouling parameters’ change rules of different stages were obtained. The results showed: In the initial stage of fouling, the deposition rate of CaCO3 was much larger than the removal rate in the evaporation tube, the total rate was larger, and the fouling layer thickness and fouling resistance increased rapidly, which caused that the total heat transfer coefficient of the evaporator reduced quickly, and that the evaporation capacity and concentration ratio of the evaporator decreased rapidly; in the middle stage of fouling, the total rate of CaCO3 became smaller, the accumulation rate of fouling became slow, and the change trend of all the fouling parameters was from fast to slow; in the end stage of fouling, the total rate of CaCO3 reached zero, the fouling no longer increased, and all the fouling parameters gradually stabilized; compared to the evaporation tube inlet, liquid film flow in outlet was smaller and the concentration of CaCO3 was higher, so the fouling in outlet was more serious. And affected by the whole evaporation tube fouling, liquid film flow and CaCO3 concentration in outlet greatly changed, which caused all the fouling parameters to change more quickly and tend to be stable relatively earlier.
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