Title: Numerical modelling of vacuum unit wash section efficiency

Authors: Bin Jiang; Xinglei Feng; Luhong Zhang

Addresses: National Engineering Research Center for Distillation Technology, Tianjin University, 92 Weijin Road, Nankai District, Tianjin, 300072, China ' School of Chemical Engineering and Technology, Tianjin University, 92 Weijin Road, Nankai District, Tianjin, 300072, China ' School of Chemical Engineering and Technology, Tianjin University, 92 Weijin Road, Nankai District, Tianjin, 300072, China

Abstract: Wash-zone and stripping section design are critical aspects to guarantee long-term vacuum unit performance. De-entrainment efficiency of wash zone and wash oil flow rate determines the heavy vacuum gas oil (HVGO) quality and coking trend of packing. Stripping section in deep-cut vacuum unit is designed to maximise VGOs yields and improve the HVGO quality. A model representing the true vacuum unit operation condition is established to predict the HVGO quality and minimum wash oil flowrate. The simulation results show good correspondence with industrial data. Wash-zone de-entrainment efficiency and non-equilibrium of transfer line are taken into account. Concentrations of vanadium, nickel and Conradson carbon in HVGO are obtained within different wash section efficiency and different amount of stripping steam in this paper. The model and simulation method must be useful for providing insights into the HVGO quality control and coke avoiding with respect to complex varying operating conditions. [Received: January 29, 2013; Accepted: October 15, 2013].

Keywords: vacuum towers; wash zone; stripping section; entrainment; slop wax; over-flash; deep-cut; numerical modelling; vacuum unit wash section; de-entrainment efficiency; wash oil flow rate; heavy vacuum gas oil; HVGO quality; coking trend; wash section packing; oil refineries; vanadium; nickel; Conradson carbon; simulation; quality control; coke avoidance.

DOI: 10.1504/IJOGCT.2015.072035

International Journal of Oil, Gas and Coal Technology, 2015 Vol.10 No.4, pp.369 - 383

Received: 01 Feb 2013
Accepted: 25 Nov 2013
Published online: 30 Sep 2015 *

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