硝酸镁换热器的腐蚀防护与预警平台

Corrosion protection of magnesium nitrate heat exchanger and its early warning platform

某厂浓硝酸装置稀硝酸镁换热器经常发生腐蚀泄漏,该文结合换热器的操作参数、工艺介质、设计选材等角度对其腐蚀成因进行了分析,通过对可能存在的损伤机理包括氯应力腐蚀开裂、硝酸腐蚀、冲刷腐蚀及冷凝水腐蚀进行深入分析,找出各项影响损伤机理作用程度的因素,如氯离子含量、硝酸浓度、操作温度、设备材质等,并从工艺防腐、腐蚀监检测、选材、设备结构优化以及防腐蚀管理等角度提出该换热器的腐蚀控制建议。根据实施效果对采取的措施进行验证,防控效果良好,由此建立硝酸镁换热器的工艺指标控制窗口和预警平台,当指标异常,平台根据指标的风险等级给出相应的报警级别和响应措施,使得影响装置腐蚀风险的工艺指标回归到正常运行状态,保障装置的长周期安全运行;同时也体现了国家“双碳”背景下,对减少材料腐蚀带来的碳排放增加的巨大价值。

Corrosion leakage occurs frequently in the magnesium nitrate heat exchanger of nitric acid unit in a plant.Corrosion causes were studied in combination with operating parameters,process media,design material and other aspects of heat exchanger.In-depth analysis was conducted on the potential damage mechanisms,including chlorine stress corrosion cracking,nitrate acid corrosion,erosion corrosion and condensate corrosion.Main factors influencing the effect of damage mechanism were identified,such as chlorine ion content,nitric acid concentration,operating temperature,equipment material,etc.Anti-corrosion recommendations were proposed from the aspects of process anti-corrosion,corrosion monitoring and detection,material selection,equipment structure optimization and anti-corrosion management.The actions taken were verified according to the actual implementation effect.If the control effect is good,process window index and early warning platform of magnesium nitrate heat exchanger will be established.If the index is abnormal,corresponding alarm and response measures will be prompted according to index risk level,so as to make the process index return to normal,ensuring the long-term safe operation of the unit.It also reflects the great value of reducing carbon emissions caused by material corrosion under the national “double carbon” background.