减压蒸馏装置过汽化油设计方案比较

Comparison of Design Schemes for Over Flash Oil in Vacuum Distillation Unit

减压蒸馏装置过汽化油设计存在三种方案,即过汽化油引至减压塔底、减压炉前循环和作为侧线产品抽出。以3.0Mt/a燃料型减压蒸馏为例,利用Aspen Plus流程模拟软件,考察上述三种设计方案对于加热炉负荷、炉出口温度、减三线蜡油(HVGO)质量和减压拔出率的影响。对于小规模减压蒸馏装置,在加工轻质原油、不进行减压深拔的条件下,过汽化油引至减压塔底和减压炉前循环两者差别较小;对于大型减压蒸馏装置或加工重质原油的减压深拔技术,减压炉前循环方案更具优势,加热炉出口温度降低,炉负荷减少,能耗降低。过汽化油作为侧线产品抽出时,能显著改善减三线蜡油的产品质量,该方案提高了减压拔出率,但是导致减压炉负荷相应增加,炉出口温度相应提高,同时使减底泵的电耗增加。在实际工程设计中,应根据减压蒸馏装置所加工的原油性质、产品要求和设备投资进行综合比较后,确定适宜的方案。

There are three design schemes for the over flash oil in vacuum distillation unit including leading the over flash oil to the bottom of vacuum tower,circulating the over flash oil to the front of VDU furnace and pumping the over flash oil out as side-draw product.In this paper,a 3.0Mt/a fuel-type vacuum distilla- tion unit is taken as an example and ASPEN PLUS simulation software is used to investigate the effects of the three design schemes mentioned above on the load of VDU furnace,the outlet temperature of furnace ,the quality of HVGO and the pull-out rate of vacuum distillation.For small-scale vacuum distillation units,there is little difference between leading the over flash oil to the bottom of vacuum tower and circulating the over flash oil to the front of VDU furnace while light crude For large-scale vacuum distillation units or deep-cut oil is processed without deep-cut vacuum distillation. vacuum distillation technology for processing heavy crude oil, circulating the over flash oil to the front of VDU furnace has more advantages such as lower out- let temperature of VDU furnace,reduced furnace load and lower energy consumption.Pumping the over flash oil out as side-draw product can significantly improve the quality of HVGO.This scheme improves the pull- out rate of vacuum distillation,but leads to corresponding increases in the furnace load,the outlet temperature of VDU furnace and the power consumption of vacuum residue oil pump.In actual engineering design,a com- prehensive comparison should be made on the properties of crude oil processed in VDU ,the product require- ments and the equipment investment,so as to determine the appropriate scheme.