锌冶炼冷却管失效分析与对策的研究

【作者】 袁望姣；

【导师】 何将三；

【作者基本信息】 中南大学 ， 机械电子工程， 2003， 硕士

【摘要】 锌液冷却工艺是火法炼锌的重要步骤之一。炼锌工业中广泛使用由20~#无缝钢管冷弯而成的冷却管来实现锌液的冷却。但冷却管的使用寿命非常短，消耗量相当大。本论文从如下几个方面分别探讨其对锌冶炼冷却管使用寿命的影响： 运用大型有限元分析软件ANSYS，得到了锌冶炼冷却管在工作过程中的热应力分布图及其分布规律，最大热应力为337MPa，达到冷却管抗拉强度86％，最大热应力位于冷却管弯直两部分的连接处且偏向弯曲部分。探讨了冷却水的水流速度、冷却管管壁厚度等因素对冷却管管壁温度场的影响，随着冷却水水流速度的增大，冷却管的冷面温度降低，温度梯度增大，热应力增大；管壁的厚度变化的影响是综合的。 从理论上分析了冷却管冷弯过程中残余应力产生的原因，是由于冷弯过程塑性变形的不均匀和塑性变形过程中弹性变形的存在；采取热处理等措施减少残余应力；并用切割法测量了冷却管残余应力的大小(最大残余应力181MPa)及其分布情况。 锌液的表面张力小，渗透性强，腐蚀性强，能与冷却管中的铁元素生成铁—锌合金，能溶解冷却管中碳、硅等元素；锌液与冷却管是不相容的。锌液与冷却管的相容性，是影响锌冶炼冷却管使用寿命的决定性因素。 锌冶炼冷却管的损坏是由于高温腐蚀和应力腐蚀。冷却管损坏位置，由热应力和残余应力共同决定，其中热应力起主导作用。 提高锌冶炼冷却管使用寿命的技术措施，主要靠提高冷却管抗锌液腐蚀的能力和降低热应力。通过采取改善冷却管的材质，如采用铁硼合金、铁铝合金；对冷却管进行表面处理，如采用抗锌液腐蚀涂层，对冷却管表面进行渗硼处理；都能有效地提高锌冶炼冷却管的使用寿命。更多还原

【Abstract】 Liquid Zinc cooling is one of very important steps in the course of melting Zinc by fire method. Cooling pipe made of 20 steel seamless tubing is widely used to cool liquid Zinc in Zinc smelting industry and its life is especially short that leads to consume of many cooling pipes. In this paper, the life of the cooling pipe of Zinc smelting is discussed in several parts as follows:The relevant thermal stress distribution graphs and regular patterns of the cooling pipe of Zinc smelting are obtained, with using the large-scale finite element analysis software ANSYS. The maximum thermal stress is 337MPa achieving 86% tensile strength of the cooling pipe and the site of the maximum thermal stress is the joint of bent section and linear section that it inclines to bent section. The effective factors such as current velocity and thickness and so on are discussed on the temperature field of the cooling pipe. The temperature of the cooling pipe on cold face is decreased and both the temperature gradient and the thermal stress are increased if the current velocity of the cooling water is increased, while the effect of thickness change of the cooling pipe is comprehensive.The reasons of producing residual stress lie in inhomogeneous plastic deformation and elastic deformation in plastic deformation process in theory. The residual stress is decreased using heat treatment. The data of residual stress are measured by using cut method and the peak value is 181MPa.There are the small surface tension and the strong osmosis and resistance of corrosion about liquid Zinc and it can form Fe-Zn alloy with steel of cooling pipe and can dissolve the C and the Si in cooling pipe. Liquid Zinc is not compatible with cooling pipe. Therefore, the compatibility is a decisive factor on the life of cooling pipe in liquid Zinc.The damage reason of the cooling pipe of Zinc smelting is high temperature corrosion and stress corrosion. Thermal stress plays an important role between the thermal stress and the residual stress to thedamaged site of the cooling pipe of Zinc smelting.The technique measures to improve life of the cooling pipe of Zinc smelting are to improve the corrosion resistance and to decrease thermal stress. The life of the cooling pipe of Zinc smelting is improved effectively by improving stuff such as using Fe-Al alloy and Fe-B alloy, surface treatment such as using surface coated material and surface boronisation treatment.更多还原