换热面上碳酸钙的结垢行为及垢形

CALCIUM CARBONATE FOULING BEHAVIOR AND MORPHOLOGY

研究了循环冷却水及池式沸腾系统中换热面上碳酸钙的结垢行为 ,对垢形进行了分析 .考察了分子自组装膜 (SAM)低能表面循环冷却水系统中碳酸钙结垢诱导期及过诱导期特性 ,研究了污垢的脱除现象 .结果表明 ,在诱导期内进行脱除可减少污垢的发生 ,在诱导期后进行脱除会增加污垢的发生 .扫描电镜 (SEM )表明 ,在阻垢剂存在下 ,循环冷却水系统中形成的碳酸钙垢形发生了变化 .利用扫描电镜与原子力显微镜 (AFM)对池式沸腾系统中生成的碳酸钙形貌进行了研究 ,发现在阻垢剂存在下以方解石为主的垢形变成了以文石和球霰石为主的垢型 ,同时碳酸钙表面的台阶发生了聚并现象 .垢形分维分析表明 ,在阻垢剂存在下两种系统中生成的碳酸钙垢形的分维值都增大了 .

The CaCO3 fouling behavior in both re - circulated cooling water and pool boiling systems have been studied. Fouling morphology was also analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The fouling characteristics, as well as removal of fouling, for both induction period and post - induction period, were investigated in cooling water system. The results show that the removal performed in induction period will reduce fouling, while fouling will increase for the removal performed in post-induction period. Fouling morphology changed in the presence of inhibitor of 5 mg &middotL-1 PAA in cooling water system. For the CaCO3 fouling formed in pool boiling system, it was found that main crystal forms changed from calcite in the absence of PAA to aragonite and vaterite in the presence of PAA. Step bunching was found by AFM on the crystal surface of CaCO3. Fractal dimension analysis shows that in the presence of inhibitor of PAA, fractal dimension increased for CaCO3 fouling morphologies formed in both heat transfer systems.