加氢裂化装置加工高硫原料油问题分析

Analysis on problems of processing high-sulfur feedstock in hydrocracking unit

关键词:  硫  循环氢  H₂S  K_p  腐蚀

Key words:  sulfur  circulating gas  H₂S  corrosion factor(K_p)  corrosion

摘要:

目的 为管控加氢裂化装置加工高硫原料油带来的风险,对加工高硫原料油导致的生产问题进行全面总结,对REAC系统腐蚀原因进行重点分析。方法 逐项计算影响REAC系统腐蚀的主要参数,与设计规范或有关研究成果对比。结果 通过分析可知,循环氢H₂S体积分数上升,造成REAC系统腐蚀因子K_p、H₂S分压上升,导致REAC空冷管束和出口弯头腐蚀加剧。结论 加工高硫原料油对加氢裂化装置的长周期平稳运行造成严重的不利影响,建议在成品柴油需求下降时,将硫质量分数较低的直馏柴油掺入加氢裂化原料,一方面增产航煤和尾油,降低柴汽比,另一方面降低原料硫质量分数。建议在生产操作过程中严格控制循环氢H₂S体积分数,确保腐蚀因子K_p＜0.2。 

Abstract:

Objective Aiming at controlling the risks of processing high-sulfur feedstock in hydrocracking unit, production problems are comprehensively summarized and the corrosion causes of REAC system are emphatically analyzed. Methods The main parameters affecting the corrosion of REAC system were calculated item by item which was subsequently compared with the design specifications or related studies. Results It can be seen from the analysis that the increase in the volume fraction of H₂S in circulating gas would result in the increase of the corrosion factor K_p and H₂S partial pressure of REAC system, which ultimately enhance the corrosion of REAC air cooling tube bundle and the outlet elbow. Conclusion sThe processing of high-sulfur feedstock has serious adverse effects on the smooth operation of hydrocracking unit in long term. Several suggestions were given as follows:(1) Straight-run diesel with low sulfur content should be added into hydrocracking feedstock when the product diesel demand drops,so as to increase jet fuel and tail oil, reduce diesel-gasoline ratio, and meanwhile reduce sulfur contents of feedstock; (2) The volume fraction of H₂S in circulating gas should be strictly controlled during production operation to ensure the corrosion factor K_p<0.2.