加氢换热器失效分析及防控工程优化研究

发布时间：2018-06-16 10:22

  本文选题：换热器 + 失效分析　； 参考：《浙江理工大学》2017年硕士论文

【摘要】：随着原油对外依存度逐年攀升,我国大量进口国外“高硫、高氮、含氯”的劣质原油,导致加氢装置中换热器频繁发生因NH_4Cl结晶而引发的流动腐蚀失效事故。鉴于NH_4Cl结晶沉积机理复杂,原油中的Cl、N含量波动幅度大,难以进行准确预测,严重影响炼油装置的安稳运行,因此亟需开展NH_4Cl结晶温度预测方法及防控优化方案研究。本文以JX石化加氢改质装置的换热器失效为研究对象,进行工艺关联过程分析,明确加氢换热器失效原因,开展NH_4Cl溶液垢下腐蚀实验,揭示反应流出物换热器的铵盐结晶机理,构建NH_4Cl结晶温度的预测模型。本文的主要结论如下:(1)基于加氢装置运行工况,构建工艺计算模型,分析换热器E1103A/B中NH_4HS结晶和NH_4Cl结晶的失效风险。通过工艺过程计算,确定NH_4Cl结晶温度188℃,反应流出物系统中不存在NH_4HS结晶,明确换热器E1103A/B的主要失效原因为NH_4Cl的结晶沉积。同时分析四个影响因素对NH_4Cl结晶温度的影响规律,明确影响NH_4Cl结晶温度的主要因素为系统压力、氯含量和氮含量。(2)针对加氢换热器NH_4Cl结晶失效问题,采用恒温恒湿试验箱,开展四种典型石化材料的NH_4Cl溶液垢下腐蚀试验研究,获得不同环境温度、溶液浓度对石化材料腐蚀速率的影响规律。通过扫描电镜和能谱分析,获得试件表面的腐蚀形貌和腐蚀产物的组成,揭示反应流出物多相流体系中NH_4Cl结晶沉积的机理。(3)基于多相流体系工艺计算模型,采用最小二乘法,获得独立变量影响下NH_4Cl的结晶温度变化函数;根据NH_4Cl结晶温度的变化规律数据,采用偏最小二乘法,构建包含氯含量、氮含量、压力三个变量共同影响下的NH_4Cl结晶温度预测模型。根据NH_4Cl结晶温度的准确预测,开展工艺注水位置及注水量的方案优化。本文的创新之处在于:针对NH_4Cl形成机理复杂、结晶温度预测困难的问题,通过对实际失效案例的分析,采用多相流工艺计算与偏最小二乘法相结合的方法,构建了包含氯含量、氮含量、压力三个关键影响因素下的NH_4Cl结晶温度预测模型,实现了NH_4Cl结晶温度的定量预测,提出了NH_4Cl结晶沉积的防控方法。研究成果可用于加氢换热器NH_4Cl结晶沉积的风险评估及防控优化,确保加氢换热器的长周期安全运行。
[Abstract]:With the increasing degree of external dependence of crude oil, China imports a large number of "high sulfur, high nitrogen, chlorine" crude oil, resulting in frequent heat exchangers in the hydrogenation unit caused by NH4Cl crystallization flow corrosion failure accident. In view of the complex mechanism of NH4Cl crystallization and deposition and the large fluctuation of ClN content in crude oil, it is difficult to predict accurately and seriously affect the stable operation of refining units. Therefore, it is urgent to study the prediction method of NH4Cl crystallization temperature and the optimization scheme of prevention and control. In this paper, the failure of heat exchanger in JX petrochemical hydrogenation upgrading plant is studied, the process correlation process is analyzed, the cause of failure of hydrogenation heat exchanger is determined, the scale corrosion experiment of NH4Cl solution is carried out, and the crystallization mechanism of ammonium salt in heat exchanger of reaction effluent is revealed. The prediction model of NH4Cl crystallization temperature was established. The main conclusions of this paper are as follows: (1) based on the operating conditions of the hydrogenation unit, the process calculation model is constructed, and the failure risk of NH4HS crystallization and NH4Cl crystallization in heat exchanger E1103A / B is analyzed. The crystallization temperature of NH _ 4Cl was determined at 188 鈩，

本文编号：2026333