Distillation of vacuum gas oil in a column with new packings

Abstract

Abstract A description of the technological scheme of the unit for separating the fraction of vacuum gas oil (FVG) is given, where the process of separation of heavy gas oil from FVG takes place in the column. The main focus of the work is on the design of a distillation column using the new structured roll packing. The fractional composition of the feedstock, by-product, light gas oil, and the target product, which is heavy gas oil, is presented. Requirements for the design of a structured packing in terms of pressure drop and separation efficiency are formulated. A structured roll packing with corrugations and rough surface having specific surface area of 300 m2/m3 is chosen. The diagram and photograph of the packing are presented. Comparative values of specific pressure drop for several structured packings are given. It is shown that the selected packing provides the lowest hydraulic resistance. For mathematical modeling and calculation of the multicomponent distillation process, a system of mass transfer equations with interfacial bulk sources of transfer components is used. In this case, for the conditional component, a fraction at the specified boiling points is used. As a result of solving the system of equations with boundary conditions, the profiles of the fractions along the height of the packed bed are found and the structural characteristics of the structured packing are selected that meet the requirements for the top and bottom of the column. Calculations of a vacuum distillation column with this packing are carried out and it is found that the bed height of 6 meters is sufficient to meet the requirements for the fractional composition of the upper and lower products, while meeting the pressure drop requirements. The developed scientific and technical solutions have been implemented at a refinery in Malaysia and correspond to the technical specifications for the design of the unit.