Modeling and Simulation of Reaction and Fractionation Systems for the Industrial Residue Hydrotreating Process

Residue oil

Built-in residue oil

Asphaltene

Paraffins

Naphthenes

Aromatics

Sulfur Components

Nitrogen 

Components

Asphaltene

Solid residue

H

2

S

NH

3

1

C

2

C

3

C

4

C

Naphtha

Diesel

Tail oil

HCR model

 PFR model 

Gas

 

Figure 2. The reaction mechanism of the two-reactors model for residue reactions process. (HCR: 

hydrocracker reactor; PFR: plug flow reactor). 

3.1. Kinetic Model of the Built-In Residue Oil Hydrotreating Process 

In the HCR model, the reaction network is extremely complicated with 177 reactions. According 

to reference [24], the reactions can be grouped into six types: (1) paraffin hydrocracking; (2) ring-

opening; (3) dealkylation of aromatics, naphthenes, nitrogen lumps, and sulfur lumps; (4) saturation 

of aromatics, non-basic nitrogen lumps, and hindered sulfur lumps; (5) hydrodesulfurization (HDS) 

of unhindered sulfur lumps; and (6) hydrodenitrogenation (HDN) of nitrogen lumps. Each reaction 

rate equation is based on the classical theory of Langmuir–Hinshelwood–Hougen–Watson (LHHW) 

[25], which demonstrates that the heterogeneous catalytic reactions undergo three basic stages: 

adsorption, surface reaction, and desorption. Figure 3 illustrates the part of the reaction network 

employed in the HCR model of Aspen HYSYS for the reaction of nitrogen lumps.