导　　师： 徐志明

学科专业： 0807

授予学位： 硕士

作　　者： ;

机构地区： 东北电力大学

摘　　要： 在工业生产中，换热设备大多具有污垢问题。换热器结垢不仅增加运行成本、降低换热效率，而且腐蚀换热面带来安全隐患。为研究换热管污垢问题，本文对不锈钢圆管硫酸钙析晶污垢特性进行实验研究，分析了溶液中离子浓度对其污垢特性的影响。 首先，研究了水质工况对硫酸钙污垢特性的影响，在相同的实验条件下，分别研究氯离子和硝酸根离子对硫酸钙结垢特性的影响。实验结果表明，阴离子对硫酸钙污垢的形成有一定的促进作用，但这种促进作用受实验管段流速的影响，与管段入口温度和工质浓度没有明显关系。电镜观察结果显示，含有大量硝酸根离子的硫酸钙溶液在圆管内结垢致密且厚重，硫酸钙晶体紧密的聚集。含有大量氯离子的硫酸钙溶液在圆管内结垢疏松且均匀，没有明显的聚集现象。 其次，实验研究了过饱和与不饱和硫酸钙溶液的污垢特性，考察了溶液浓度、水浴温度、管内流速对过饱和与不饱和硫酸钙溶液污垢特性的影响。结果表明，过饱和工质溶液的污垢热阻明显大于不饱和工质溶液；过饱和溶液污垢热阻比不饱和溶液污垢热阻更易受温度的影响；实验中管内流速越高，污垢生长速率越慢，污垢热阻渐近值越低，但流速对不饱和溶液的影响更为明显。 Fouling affects on the most of heat transfer in industry production. Heatexchanger fouling not only increases operating costs and reduces the heat transferefficiency, but also corrode heat transfer surface and causes security risk. This thesisstudies the fouling characteristics of calcium sulfate and analyzes the influence of ionconcentration on the fouling characteristics. Firstly, under the same experimental conditions, the experiment research theinfluence of water conditions to CaSO4fouling characteristics. We have respectivelyresearched the influence of NO3-and Cl-to the CaSO4fouling characteristics. Theexperiment shows that anion promotes the formation of CaSO4fouling to some extent,but this kind of promoting is affected by flow velocity, which has no obviousrelationship with inlet temperature and working medium concentration. The results ofscanning electron microscopy show that CaSO4solution contains large amounts ofNO3-fouling dense and thick and CaSO4crystals closely together. However, in thecircular tube, CaSO4solution with large amounts of Cl-fouling loose and uniform,and there is no obvious aggregation phenomenon. Secondly, the experiment research fouling characteristics of over-saturated andunsaturated calcium sulfate solution. The effect of concentration, the temperature ofthe water tank, tube flow rate on the fouling characteristics of over-saturated andunsaturated calcium sulfate solution are investigated. The results show that foulingresistance of over-saturated calcium sulfate solution is significantly greater than thefouling resistance of saturated solution; the fouling resistance of over-saturatedcalcium sulfate solution is more susceptible to temperature than the fouling resistanceof unsaturated calcium sulfate solution. In fouling characteristics experiment, thehigher the flow rate is, the slower the growth rate of fouling is, the lower theasymptotic value of fouling resistance is, but the flow rate has a more obvious effect on the unsaturated solution.

关 键 词： 污垢特性 阴离子 晶体形态 不饱和工质

分 类 号： [TK172]

领　　域： [动力工程及工程热物理]