## 1 Introduction
### Modelling Approaches for the Packed Column Used for Absorption Processes  
Mathematical models contribute to a better understanding of the process and play an essential role in enhancing plant efficiency. A recent literature review tells that there are several studies concerning modelling the absorption process. These studies are based on two standard models: the equilibrium model and the rate-based model. The equilibrium-stage model is developed by [PERSON] et al. [21], whereas the rate-based model depends on the early work published by [PERSON] [22], who presented a model for rate-based CO\({}_{2}\) absorption. Recently the rate-based model and equilibrium model of CO\({}_{2}\) capture with Amin solvent in a packed column have been investigated by several authors. Many studies [23; 24; 25] applied the rate-based model for studying CO\({}_{2}\) absorption. [PERSON] et al. [26] compared the rate-based and equilibrium models for CO\({}_{2}\) capturing with AMP solution in a packed column. [PERSON] [19] employed equilibrium model to explain the experimental data for absorption tar by vegetable oil. The author tested two vegetable oils as absolvents namely soybean oil and canola oil.  
To the best of our knowledge, few studies have been published regarding the modelling of tar absorption with vegetable oil in a packed column. Most of these studies have concentrated on modelling absorption process for CO\({}_{2}\) capture, while the modelling of the tar absorption process is rarely presented. The objectives of this study are as follows:  
Assembling a property package for tar-soybean oil and build a rate-based model as well as equilibrium model by applied Aspen Plus software for simulation of tar absorption using soybean oil  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Absorbent** & **Water** & **Diesel Fuel** & **Biodiesel Fuel** & **Vegetable Oil** & **Engine Oil** \\ \hline Benzene & 24.1 & 77.0 & 86.1 & 77.6 & 61.7 \\ \hline Toluene & 22.5 & 63.2 & 94.7 & 91.1 & 82.3 \\ \hline Xylene & 22.1 & \(-\)730.1 & 97.8 & 96.4 & 90.7 \\ \hline Styrene & 23.5 & 57.7 & 98.1 & 97.1 & 91.1 \\ \hline Phenol & 92.8 & \(-\)111.1 & 99.9 & 99.7 & 97.7 \\ \hline Indene & 28.2 & 97.9 & 97.2 & 97.6 & 88.7 \\ \hline Naphthalene & 38.9 & 97.4 & 90.3 & 93.5 & 76.2 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Absorption efficiencies of tar components by different solvents (%) [16].  
as a solvent. Aspen Plus software is used because of its extensive property databanks and rigorous equation solvers.  
Validation of both the mathematical models (rate-based and equilibrium stage) against experimental data is carried out at different operation points. The experimental data reported by [PERSON] [19] is used for validation of the models.  
The accuracy of the results predicted by the two mathematical models (rate-based and equilibrium stage) is compared with the experimental data.  
Analysis of tar absorption process is essential to study the process parameters on tar removal efficiencies such as the solvent temperature, flow rate of solvent, and height packed bed.  
This study presents a methodology for selecting the optimum (most economical) operating conditions.  
This work is a contribution to the knowledge available for modelling studies for tar absorption using vegetable oil as a solvent in the wet packed column.