Mathematical modeling and simulation of a diolefin saturation reactor used in a naphtha hydrotreating process

Abstract

This paper describes a dynamic mathematical model developed to simulate a diolefin reactor currently used in an existing naphtha hydrotreating process. Diolefins polymerize at temperatures above 200 °C, which is reached in a reactor of hydrotreatment of naphtha. Therefore, the diolefins must be removed before they reach the hydrotreating reactors. This hydrotreating unit has an essential role in modern refineries as it specifies the naphtha of different units, such as distillation and delayed coker. A mathematical model of a three-phase reactor was developed. It was used to obtain the kinetics of the diolefin and olefin saturation reaction in a temperature range of 180 ºC to 200 °C, and pressure of 3.5 MPa to 4 MPa. The kinetic model was developed from the experimental data from a Brazilian refinery. The reactor model includes correlations for determining mass-transfer coefficients, kinetics reaction rates, and properties of the compounds under process conditions. The kinetic model predicted the temperature profile along the reactor length with a minor absolute error. The developed model offers reliable simulated results when compared to experimental data.

Keywords

• kinetics of diolefin saturation
• mathematical modeling
• naphtha hydrotreating