频繁碱洗对不锈钢及钛材设备的影响

Impact of Frequent Caustic Washing on Stainless Steel and Ti-Alloy Steel Equipment

Pd/C催化剂对PTA生产中加氢精制起了至关重要的作用。介绍了加氢反应器选材、催化剂失活及其再生碱洗的生产情况。并分析了高温碱洗对加氢反应器碱脆与后续不锈钢设备氯脆的影响。提出了防止应力腐蚀破裂的措施,包括提高催化剂质量、减少碱洗频次、改进碱洗工艺、同时优化加氢工艺、控制进料浆料质量分数,以提高催化剂使用寿命。采用优等品NaOH,消除设备残余应力,加强设备定期检测等也是有效的。对钛设备高温碱洗会发生氢脆也作了分析。

The Pd/C catalysts play a critical role in hydrotreating purification for PTA production. The material selection for hydrotreating reactor, deactivation of Pd/C catalysts and caustic washing for regeneration are introduced. The impact of caustic washing at high temperature on caustic stress corrosion cracking （ASCC） of hydrotreating reactor and subsequent chloride stress corrosion cracking （CSCC） of stainless steel equipment are analyzed. Measures for prevention of stress corrosion cracking （SCC） are presented, including enhancement of catalyst quality, reduction of caustic washing frequency, improvement of caustic washing process as well as optimization of hydrotreating process, control of feedg slurry percentage to extend the service life of catalysts. In addition, the application of high - quality NaOH to eliminate residue stress of equipment and scheduled testing of equipment are also effective means. The possibility of hydrogen embritflement of Ti - alloy equipment is also studied.