延迟焦化加工劣质渣油的技术探讨

Discussion on processing low-quality residue in delayed coking unit

分析了劣质渣油特别是减压深拔后渣油的性质及其对延迟焦化装置的影响。原料密度大、沥青质和残炭比值大的原料易产生弹丸焦。原料的残炭值越高、芳烃/沥青值的比值越小、金属含量越高,则导致加热炉炉管越易结焦、生焦率提高、分馏塔下部和焦炭塔顶油气管线易结焦、分馏塔上部易结盐。硫含量的增加加剧了设备的腐蚀,安全及环保压力增大。通过进一步优化和完善延迟焦化工艺设计,如考虑生产弹丸焦的设计、优化加热炉的设计和操作、增设防焦设施、增设在线洗盐措施、采用全蜡油下回流脱过热工艺和定量控制循环比、提高设备及阀门的可靠性并增加安全联锁、增设环保措施等,充分发挥现有延迟焦化装置加工劣质渣油的作用。

The properties of low-quality residue oil especially the vacuum residue from deep-cut vacuum distillation process and their impact on delayed coking unit are analyzed. The feedstock with higher density, higher asphahenes and greater CCR is more easily to produce shot coke. The higher the CCR is, the greater is the aromatic to asphaltene ratio. The higher the metal content is in the feed, the furnace tubes are more easily subject to coking, the coke make is high, and salt is more easily deposited at the bottom and overhead of fractionator and overhead oil vapor line of coker drum. Furthermore, the increase of sulfur in the feed will aggra- vate the corrosion of equipment and lead to the safety problems and environmental pollution. To solve these problems, the following measures should be taken, such as design for shot coke production, optimization of design and operation of coker furnaces, addition of anti-coking facilities and on-line salt washing equipment, application of total HCGO and fixed recycle ratio control, improvement of operation reliability of equipment and valves, addition of safety interlock system and provision of environmentally friendly measures.