劣质原油常减压蒸馏工艺技术探讨与实践

Study on crude distillation process for low-quality crude oil and application

以渣油加氢处理和延迟焦化并存的重油加工路线为切入点,分析了常减压蒸馏一般流程的特点和不足,提出并论述了两段减压蒸馏技术的流程特点,介绍了流程对产品质量和收率的影响,实现了原油合理蒸馏.以采用了两段减压蒸馏技术的某在建工程项目12 Mt/a常减压蒸馏装置为例,通过流程模拟计算分别对常减压蒸馏的一般流程和两段减压蒸馏流程进行了分析,主要结论如下：外甩常压重油作渣油加氢处理原料,减少了减压蒸馏部分的加工负荷,同时也造成了直馏柴油的损失,采用两段减压蒸馏流程能够避免该部分柴油的损失.两段减压蒸馏技术,各段生产目标单一、明确,产品质量和收率可依据后续加工装置的需要灵活调节.两段减压蒸馏技术的第一段减压蒸馏操作条件缓和,采用常规干式减压蒸馏技术,可以有效降低装置的加工能耗.第二段减压蒸馏的减压塔内仅设有2～3段填料床层,内部结构简单,全塔压力降低,更有利于实现减压深拔技术,提高减压蒸馏的拔出深度;第二段减压蒸馏拔出的重质减压蜡油直接并入渣油加氢处理原料,简化了流程.采用两点抽真空技术,两段减压蒸馏共用一套抽真空系统,简化了流程,也降低了投资.两段减压蒸馏技术可以有效降低装置的加工能耗和建设投资,适用于新建项目,在以优化全厂装置配置为目的的改造项目中也值得尝试.

On the basis of residue oil hydrotreating process and delayed coking process, the characteristics and shortcomings of conventional atmospheric-vacuum distillation process are studied, the technical features of two-stage vacuum distillation process are presented, the impact of the process on product quality and yield are described and an optimized crude distillation process is realized. In a case study of a 1.2 MM TPY atmosphericvacuum distillation unit with two-stage vacuum distillation, the conventional atmospheric-vacuum distillation process and two-stage vacuum distillation process are analyzed by process flow simulation calculation. The conclusions are： the use of draw-out atmospheric residue as the feedstock of residue oil hydrotreating unit has re- duced the duty of vacuum distillation unit but the straight-run diesel is lost. Whereas, the application of two-stage vacuum distillation process can eliminate the loss of diesel. In two-stage vacuum distillation process, each stage produces definite product, and the product quality and yield can be flexibly adjusted accordingly to the requirements of down-stream units. The operating conditions of lst-stage of two-stage vacuum distillation process are mild, and the application of conventional dry vacuum distillation process can effectively reduce the energy consumption of the unit. The vacuum tower of 2nd-stage vacuum distillation only has 2 - 3 packed beds. The internal structure is simple and tower＇s pressure drop is low, which is favorable for the deep-cut vacuum distillation and increasing deep cut. The heavy vacuum gas oil from 2nd-stage vacuum distillation is directly sent to the residue oil hydrotreating unit as the feed, which simplifies the process flow and reduces the investment. The two-stage vacuum distillation process can effectively reduce the unit＇ s energy consumption and capital investment, which is applicable ibr the grass-roots units and refinery configuration optimization in revamping project.