延迟焦化装置高压水泵节能及防腐蚀升级改造

Energy Saving and Anticorrosion Upgrading of Hydro Pump in Delayed Coking Unit

高压水泵是延迟焦化装置水力除焦设施的关键设备,由于某石化企业延迟焦化装置受掺炼污泥和回炼轻污油等影响,导致除焦水中含有较高的氯离子、硫离子及游离氧,其中氯离子质量分数能够超过1 200μg/g。高压水泵叶轮材质为不锈钢,氯离子易引发不锈钢材质点蚀及应力腐蚀开裂,后果非常严重。两台高压水泵在2009—2014年,多次发生盖板断裂、穿孔、裂纹以及叶轮开裂等故障。试验结果表明:在适当降低高压水泵出口压头条件下,仍然满足除焦要求,并且对除焦时间无影响。因此,将高压水泵原叶轮直径由Ф383 mm切割至Ф359 mm,泵扬程由3 587 m降至3 300 m,进而降低高压水泵出口压力,节能降耗显著。此外,将叶轮材质升级为双相不锈钢可以有效抑制氯离子的腐蚀,提高设备运行稳定性。

Hydro pump is the key equipment of hydraulic coke removal in delayed coking unit. The delayed coking unit in a petrochemical enterprise was affected by mixing sludge and light slop oil,which resulted in high content of chloride ion,sulfur ion and free oxygen in coke removal water,and content of chloride ion run up to 1 200 μg/g. Therefore,pitting and cracking occurred through the reaction between chloride ion and stainless steel impeller of hydro pump. Two hydro pumps have suffered many accidents such as cover plate fracture,cover plate perforation,cover plate cracking and impeller cracking from 2009 to 2014. Experiments showed that decoking would not be affected under the condition of lowering outlet pressure head of pump properly. Thus,improvements were made by cutting original impeller from Ф383 mm to Ф359 mm and lowering pump head from 3 587 m to 3 300 m. In addition,impeller material was upgraded to duplex stainless steel which could inhibit corrosion effectively and improve operation stability of the equipment.