克拉玛依重质原油焦化技术评析

A DISCUSSION OF THE KARAMAY HEAVY OIL COKING TECHNOLOGY

依据克拉玛依石化公司新建的重油焦化装置几年来运行情况和操作数据,对重油焦化与蒸馏-渣油焦化组合工艺进行对比分析。结果表明,重油焦化工艺能多裂解蜡油组分,投资省,柴汽比高,但焦炭、干气产率偏高;重油焦化工艺由于没有设置常压蒸馏塔,造成装置能耗高、后续加工费用高的问题。提出利用环烷酸经焦炭塔高温分解的现象、通过灵活运用渣油焦化的间接换热和增设常压蒸馏塔工艺、在焦化分馏塔系统采用普通钢材代替316L钢材的新方案。焦化装置采用增设蜡油汽提塔等改造措施后显著改善柴油与蜡油的分割,节约后续加工费用。

Based on the operation data of the heavy oil coking unit in Karamay Petrochemical Company,a comparison of heavy oil direct coking process and distillation-coking combine process was carried out. It can be seen that as compared with the combine process, heavy oil direct coking technology exhibited less investment,more cracking of VGO fractions and higher diesel to gasoline ratio,yet higher yields of coke and gas were observed. Because atmospheric tower was omitted in the heavy oil coking unit, energy consumption of the unit and the operation cost in subsequent processes became higher. Since naphthenic acid could be decomposed at high temperature in coke tower,a new idea about anti-corrosion of naphthenic acid was presented and discussed in this paper as well. For reducing energy consumption and saving downstream processing fee, a suggestion of adding an atmospheric distillation tower in the coking unit,adopting indirect heat exchange for residue coking and using carbon steel instead of 316L steel in the distillation system was proposed based on the above analysis. Furthermore, adding a coker gatch stripper could significantly improve the separation of coker gas oil from coker gatch, resulting in less downstream processing fee,and this was realized in this existed unit.