In order to reveal the mass transfer process characteristics of stripping section of the vacuum distillation column (VDC) in crude unit and to improve the stripping operation, an improved simulation method and mass transfer correlations for VDC were applied to investigate the mass transfer behaviours of steam stripping process. Based on the understanding of stream stripping process, the necessity of using packed stripping column and stripping section was demonstrated, and the design and analysis methods for stream stripping process were proposed. The calculation results show that the packing separation performance of side stripping tower keeps constant, and the separation efficiency of side stripping tower is close to that of the corresponding separation section of VDC, thus more attention should be devoted to design and operation of steam stripper and stripping section to improve separation performance. The process and hydraulics characteristics of bottom stripping section of VDC are the same with that of side stripping tower. High steam mass flow rate ( more than 1 % of feedstock) of bottom stripping section may cause negative impact on the overall separation efficiency of VDC.%为了揭示减压塔汽提工艺的传质过程特性,进而改进汽提操作,采用改进的减压精馏过程模拟方法和传质计算方法,分析了炼油常减压装置的汽提工艺的传质特点.在深化对于汽提工艺的理解基础上论证了采用填料汽提塔(段)的必要性以及设计、分析的基本方法.计算分析结果表明侧线汽提塔内填料分离性能保持恒定,汽提塔的分离效率与减压塔对应分离段接近,所以在设计和操作中应给予汽提塔(段)充分重视.减压塔底汽提段的工艺和水力学特点与侧线汽提塔相同.塔底汽提蒸汽质量流率应小于减压塔进料质量流率1％,否则将导致减压塔整体分离效率降低.
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