废酸回收装置首次开车难点分析及应对措施

Analysis of difficulties and countermeasures for first start-up of waste acid recovery unit

2023年1月某石化企业丙烯腈联合装置中的SAR(废酸再生)装置投料开车一次成功。提高裂解废酸转化率的关键是降低再生炉内的氧含量。通过降低预热系统负荷和提高再生炉燃烧器负荷,有效降低了再生炉内氧含量,提高了再生炉内三氧化硫向二氧化硫的转化率,减少净化单元弱酸中硫酸含量,最终缓解了稀酸腐蚀问题。通过增加备用废酸喷枪的数量和降低单支废酸喷枪的负荷,既解决了废酸喷枪的雾化效果不佳问题,又缓解了废酸水原料对再生炉的腐蚀。开工阶段,在余热锅炉火管和烟箱处容易出现冷凝酸腐蚀和泄漏。由于衬氟设备发生的腐蚀泄漏主要与内衬的密封形式和材料的使用温度相关,因此为了提高密封性,耐酸腐蚀金属软管通常选用内衬PTFE而且与法兰面整体成型的结构。

In January 2023,the SAR(sulfuric acid regeneration)unit in the acrylonitrile complex of a petrochemical plant was successfully started up for the first time.The key to improving the conversion rate of waste acid was to reduce the oxygen content in the regeneration furnace.By decreasing the load of the preheating system,the burner load of the regeneration furnace was elevated,which effectively diluted the oxygen content in the regeneration furnace,increased the conversion rate of sulfur trioxide to sulfur dioxide,lowered the sulfuric acid content in the weak acid of the purification unit,and ultimately lessened the problem of acid corrosion.By adding the number of backup waste acid spray guns and diminishing the load on a single spray gun,the poor atomization effect of waste acid spray gun and the corrosion of acid water on the regeneration furnace were alleviated.During the start-up phase,condensed acid corrosion and leakage were prone to occur at the fire tubes and smoke boxes of the waste heat boiler.The corrosion and leakage of fluorine lined equipment was mainly related to sealing form of the lining and temperature of the material used.Acid resistant metal hoses need to be lined with PTFE and integrally formed with the flange surface to enhance sealing performance.