大氮肥装置中的腐蚀事故原因及其防止方法的研究

【作者】 姚灿龙；

【导师】 李国希； 朱泽华；

【作者基本信息】 湖南大学 ， 材料工程， 2003， 硕士

【摘要】 中石化股份公司巴陵分公司在1970年代引进了一套大氮肥生产装置，经过近三十年的生产运行，该装置中一些设备由于基本接近设计寿命，或者由于生产原料改变而引起设备的运行工况发生了较大变化，一些设备出现了较多的腐蚀破坏事故，造成严重的经济损失。本文针对巴陵分公司出现的设备破坏事故，通过调查和分析材质、环境等确定了设备腐蚀的原因，提出了解决措施。实践证明，在采取我们提出的措施后，设备的事故率大大降低，获得了显著的经济效益。 1．合成氨装置中的第一废热锅炉(101-C)换热管自1992年以来先后8次发生换热管爆裂事故。其中，1994年6月20日更换后，运行仅59天就发生了爆裂。换热管爆裂事故造成停工停产，严重影响生产。通过对101-C所用换热管的化学成分、力学性能、金相组织进行试验测定，分析锅炉给水的水质，导致换热管爆裂的主要原因是锅炉水和给水水质不符合规定。解决措施是加强管理，优化工艺操作、严格控制锅炉水质的各项指标；在脱盐水出水总管及尿素回收冷凝液出口总管处加树脂捕捉器，防止回收冷凝液中含有树脂等杂质。在采用这些措施后，该设备从未发生爆管事故，已平稳运行5年，每年因此而减少损失1000万元以上。 2．锅炉及热交换器的结灰、结焦使锅炉排烟温度上升，导致换热效率下降，工艺介质温度达不到要求，并引起受热面发生高温腐蚀。特别是合成氨装置中原来以石脑油为燃料的转化炉(101B)改用重油后，由于重油灰分较多，转化炉的换热管结灰更加严重。通过分析蒸汽吹灰、声波吹灰及燃气高能脉冲吹灰的原理，比较它们的效果和费用，最后确定采用干冰清洗结合燃气高能脉冲吹灰方法，较好地解决了锅炉换热管积灰和结焦的问题。这一工作为巴陵分公司和中石化湖北分公司处理这个问题提供了理论依据，这两个单位在2002年和2003年相继采用本方案后，较好地解决了锅炉换热管集灰和结焦的问题，每年节约费用800多万元。 3．19g3年以来，巴陵分公司长一洞输油管道茶港段发生多次穿孔漏油事故，引起输油中断、污染环境，造成很大的经济损失。通过现场调查、土壤分析，弄清了油管穿孔漏油的主要原因是茶港化工厂内操作不规范而造成工业废液渗入到地下管道外表面，从而引起油管的腐蚀破坏。当地政府采纳了上述分析结果，责令该厂停产整顿，基本上解决了输油管道腐蚀破坏的隐患。更多还原

【Abstract】 In the 1970s. SiNOPEC Baling Petrochemical Company introduced a set of large production device of nitrogenous fertilizer. After operation for twenty years, some equipment of the device has nearly reached the design life. In addition, the variation of raw material of production has greatly changed the circumstances of operation. Because of these two factors, many accidents of corrosion destroy have happened, which have also brought about serious economic losses. To effectively solve this problem, we conducted a thorough investigation into the causes of the accidents and made a careful analysis of the material quality and operation circumstances. Then, we put forward our measures. The practice have proved that our measures have greatly lowered the accident rate of the device and gained notable economic benefit.1. Since 1992, blast accidents of heat exchange pipes of the first waste heat boiler of synthetic ammonia have taken place eight times. Among these accidents, a blast accident happened only 59 days after it was changed on 20th June, 1994, which led to stop production. Through test determination for chemical composition, mechanical performance and metallurgical tissue of the heat exchange pipe of 101-C and analysis of quality of supply water from the boiler, the main reason why the accident happened was that the quality of the water from the boiler and the supply water did not accord with the stipulations. Management enhancement, technological operation optimization and serious control of all indexes of water quality were measures to solve this problem. Resin applicators were installed on both the outlet of the main pipe for desalting water and that for urea reclaimed condensate to guarantee no impurity in the reclaimed condensate, such as resin. After these measures were taken, the device has been in smooth operation without blast accidents for 5 years, which has reduced losses of morn than RMB ten million annually.2. Ash and coke on the boiler and heat exchanger raised the temperature of theflue gas in the boiler, which led to the results that the heat exchange rate was decreased and the temperature of process medium did not meet the requirements.. Therefore, high temperature corrosion took place on heat surface. In particular, after substituting heavy oil for naphtha as lite! for the converter in the synthetic ammonia device, ashing in the heat exchange pipes of the converter was more serious because of the large quantity of ash content of heavy oil. Through analysis of the principles of vapor blow, sound wave blow and gas-fired blow of high energy pulse, and through comparing their effects and expenses, we finally decided to combine the last method and dry ice cleaning, which provided theoretical basis to solve the problem for Baling petrochemical company and Hubei petrochemical company. In 2002 and 2003, the two companies solved the problem of ashing and coking on the heat exchange pipe of the boiler better than before after they adopted the method in succession. In the meantime, they saved RMB eight million annually.3. Since 1993, puncture leakages have happened many times in the pipe duct on the cha-gang section, which resulted in delivery suspension, environment pollution and large economic losses. Through spot investigation and soil analysis, the main reason why puncture leakages happened was that the abnormal operation caused the industrial waste water to permeate into the external surface of underground pipe and thus led to corrosion destroy of the oil pipe. The local government adopted the above-mentioned analysis results and ordered the factory to stop operation and carry on rectification. So hidden danger of corrosion destroy of the oil pipe was basically resolved.更多还原