止水机械密封的热特性研究

发布时间：2017-12-28 13:25

本文关键词：止水机械密封的热特性研究　出处：《昆明理工大学》2013年硕士论文　论文类型：学位论文

【摘要】：止水机械密封是一种新型的机械密封应用方式,常用于湿法冶金流程泵中,它的密封水不进行外部循环,称之为“止水”。不过,在该机械密封运行过程中,不对外循环的密封腔里的“止水”会随着轴的转动在密封腔内流动,甚至于内循环流动。密封摩擦副产生的热量和密封旋转件搅拌液体产生的热量会传递给密封腔里的密封水,使其温度升高。温度升高的密封水对防止液体的结晶有重要作用。但密封腔内的密封水的温度也不能太高。合理控制密封腔液体的温度是正确应用该类机械密封的关键。充分了解和把握该类机械密封的传热特性是合理控制该类机械密封的理论基础和关键技术。本文采用解析法对止水机械密封的传热特性进行了理论研究,研究了止水机械密封的稳态热性能和暂态热性能,获得了密封环和密封水的温度分布规律。本文在对等截面直翅片传热过程分析的基础上,考虑由两段截面不等的直翅片组成的复合翅片,根据热量平衡原理,经推导,获得了由两段不等截面直翅片组合的复合翅片的温度分布和总传热量的计算表达式。将该计算式取等截面条件与经典的计算式进行了对比,计算结果相同。利用获得的不等截面直翅片温度分布和总传热量的计算表达式,分别成功地计算了翅片根部段截面小和翅片根部段截面大的两种翅片的导热状况,结果表明翅片根部段截面大的情况更利于热量传递,对于相同的散热量,其根部温度更低。不等截面直翅片模型可以用来计算双边传热机械密封的热特性。对于双端面机械密封,靠近介质端的机械密封即为双边传热机械密封,一侧与被密封介质接触,另一侧与密封水接触。止水机械密封一般采用普通双端面机械密封,只是密封水不对外循环。对于单边传热机械密封,根据Buck翅片模型计算得到了其稳态下的温度分布。结果表明,密封环温度随着与密封端面轴向距离的增大而逐渐减小。同时分析了摩擦系数f、端面比压pc、转速N等因素对温度分布的影响。暂态传热特性可由密封环温度分布随时间变化规律反映。采用分离变量法计算得到了单边传热机械密封环的暂态温度分布,其稳定后的温度分布与稳态下的温度分布吻合。分析了转速N、摩擦系数f、端面比压pc等因素对密封环暂态温度场分布的影响。止水机械密封腔密封水的温升受多种因素的影响。本文将密封水与密封环组件看成一个多热容系统,利用系统热平衡方程和双热容系统理论分析得到了密封环和密封水温度随时间的变化规律,分析了其影响因素。对于双边传热机械密封,根据本文获得的不等截面复合翅片模型的温度分布和总发热量的计算式,计算得到了密封环的温度分布规律。分析了转轴速度N、密封端面比压pc和摩擦系数f对双边传热机械密封温度分布的影响规律,结果表明,随着转轴转速N、密封端面比压pc和摩擦系数f的增大,密封端面温度均上升,其中密封端面比压pc和摩擦系数f对端面温度的影响尤为突出。
[Abstract]:Water seal mechanical seal is a new application way of mechanical seal. It is often used in process pump of hydrometallurgy. Its sealing water does not carry out external circulation, it is called "water stop". However, during the operation of the mechanical seal, the "stop water" which does not circulate in the sealed chamber will flow with the axis rotation in the sealing cavity, or even the internal circulation. The heat generated by the sealed friction pair and the heat produced by the sealed rotating part of the mixing liquid are transferred to the sealed water in the sealing cavity to increase the temperature. The high temperature sealed water plays an important role in preventing the crystallization of the liquid. But the temperature of the sealed water in the sealed chamber is not too high. The proper control of the temperature of the liquid in the sealing cavity is the key to the correct application of this kind of mechanical seal. To fully understand and grasp the heat transfer characteristics of this kind of mechanical seal is the theoretical basis and key technology for the rational control of this kind of mechanical seal. In this paper, the heat transfer characteristics of the sealing mechanical seal are theoretically studied by analytical method. The steady thermal and transient thermal properties of the sealing mechanical seal are studied, and the temperature distribution law of the sealing ring and the sealing water is obtained.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TH136

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