Introduction
The topping unit, or atmospheric distillation unit (CDU), is the first and most critical unit in any refinery. Its primary function is to physically separate crude oil into various fractions based on the boiling points of its components.
Overall Process in a Topping Unit
- Crude Oil Preheating: Crude oil is transferred from storage tanks to the topping unit and preheated in heat exchangers. This reduces fuel consumption in the furnace.
- Furnace Heating: The preheated crude oil enters the furnace and is heated to the vaporization temperature of lighter components.
- Entry into the Distillation Column: The vapors from the furnace enter the bottom of the distillation column.
- Distillation: In the distillation column, vapors move upward. Heavier components liquefy on different trays and flow downward, while lighter components continue upward as vapor and exit from the top.
- Condenser: Vapors exiting from the top of the column enter the condenser and are converted to liquid. This liquid is known as light naphtha.
- Separator: The liquid from the condenser enters a separator to remove non-condensable gases like hydrogen and methane.
Products of the Topping Unit
- Light naphtha: Obtained from the top of the column and used as feedstock for aromatic or reforming units.
- Gasoline: Obtained from the condensation of vapors on middle trays and, after refining, used as motor gasoline.
- Kerosene: Obtained from the condensation of vapors on lower trays and used as jet fuel or feedstock for lubricant production units.
- Diesel: Obtained from the bottom of the column and, after refining, used as diesel fuel.
- Atmospheric residue: The heaviest component, exiting from the bottom of the column, and used as feedstock for vacuum distillation units.
Importance of the Topping Unit
- First stage of refining: The topping unit is the initial stage of crude oil refining, producing primary products that are further processed in subsequent units.
- High-volume product production: This unit produces a significant volume of petrochemical products such as gasoline, diesel, and kerosene.
- Foundation of the refining process: All subsequent units in a refinery are designed and built based on the products produced in the topping unit.
This study aims to design and simulate a topping unit using Aspen HYSYS, utilizing industrial data from the Khangiran Refinery. By modeling this unit, it becomes possible to analyze the process behavior under various operating conditions, leading to improved performance and increased production efficiency. Additionally, the simulation can help identify the impact of various parameters such as temperature, pressure, and feedstock composition on the quality and quantity of produced products. This activity can serve as a decision-making tool for refinery managers to improve processes and enhance product quality.
This study aims to design and simulate the Topping unit with Aspen Hysys software using the industrial data of Khangiran Refinery. By modeling this unit, it is possible to analyze the behavior of the process under different operational conditions, which can lead to improved performance and increased production efficiency. In addition, simulation can help to identify the effect of various parameters such as temperature, pressure and feed composition on the quality and quantity of manufactured products.
This activity can be used as a decision-making tool for refinery managers in order to improve processes and improve product quality.
Simulation of Topping Unit Khangiran Refinery With Industrial Data
Distillation unit of Khangiran Gas Refinery was built in 1993 with the cooperation of I.M.S and National Iranian Gas Company N.I.G.C. The goal is the distillation of gas condensates in gas extracted from natural gas pools in the region. The ultimate goal of building this unit was to convert oil condensate into products with more added value such as naphtha, solvent, kerosene and diesel.
In this project, due to the very important role of simulating industrial processes in their behavior analysis, investigation and feasibility in unit design. And predicting the impact of changing various operating variables on the unit’s performance, and considering the low cost of simulation, the simulation of the mentioned unit has been done. Aspen Hysys software is used for simulation.
