换热设备的超声防垢机理

通过探讨成垢晶体的结晶动力学过程和超声波对形成的CaCO3晶体形状和大小的影响，揭示了超声波防除积垢的机理．研究表明，超声处理可以缩短溶液中晶体的成核诱导期，提高晶核的生成速度，在溶液中迅速生成大量的微晶悬浮于溶液主体，晶粒长大速度减慢，成垢晶体不易沉积在管壁上。从而减少了积垢的形成．同时，超声的空化与机械作用增大了积垢在溶液中的溶解度，破坏了已形成的积垢。使其松软脱落．超声波还能改变生成的CaCO3晶体的形状及大小，改变形成的积垢的堆积形状，从而起到防垢的目的．工厂试验也表明。超声波防除积垢装置不但可以防止积垢的形成，而且可以有效地除去已形成的积垢，提高了蒸发系统的传热系数与蒸发强度，平均防垢率迭76．4％．

Mechanism of Scale Controlling of Heat-Transfer Equipment by Ultrasonic

In this research, the mechanism of scale controlling by ultrasonic was revealed through the crystal dynamics and the investigation into the influence of ultrasonic on the shape and size of CaCO3. The results show that the nucleation induction period of CaCO3 crystals is shortened and the formed velocity of crystal nuclei is increased by ultrasonic, which causes a great number of minicrystals promptly to suspend in solution. And, the growth velocity of the crystal is decreased and the deposition of the scale on pipe wall is prevented, thus decreasing the amount of scale. Moreover, the cavitation and mechanical function of ultrasonic result in the increase of scale solubility, destroy the formed scale and make the scale soft fall off. In addition, ultrasonic radiation changes the shape, the size of CaCO3 crystal and the pileup form of the scale, thus preventing the pipeline from begriming. Experiments in a mill indicate that ultrasonic treatment can not only prevent the scale formation but also remove the formed scale, with an average efficiency of scale controlling up to 76.4%. Thus, the evaporation intensity and heat transfer coefficient of the evaporation system is improved.