Modeling, Simulation, and Control of a Modular Refinery

Modeling, Simulation, and Control of the Diesel Chimney Tray in a Crude Distillation Column of a Modular Refinery

Abstract

Modular refineries are refineries whose hardware are built in fragments with the intent of easy transportation, installation, and decommission. A modular refinery can produce a range of specific petroleum products, commonly naphtha, diesel, kerosene, and residue, at a time thereby meeting the immediate fuel needs of Nigeria. The establishment of modular refineries at strategic locations would reduce the importation of refined petroleum products, curb pipeline vandalism, impact the nation's GDP, and provide employment opportunities for both skilled and unskilled workforce. The daily consumption of diesel in Nigeria according to NMDPRA in 2021 was about 13 million litres per day, hence it is necessary to control the liquid level in the diesel chimney tray of the crude distillation column.

This work develops an input-output transfer function model used for designing the diesel chimney tray liquid level in the crude distillation column. Four tuning methods were used: Ziegler Nicholas; Cohen-Coon; Integral Time Weighted Absolute Error (ITAE); and Internal Model Control (IMC) tuning methods. The ITAE tuning method with controller parameters KC, τi , and τD of 2.48154, 2.14899, and 0.31699 respectively gave the best dynamic response with 4% overshoot, 2.5s rise time, 7s settling time, and minimal oscillation.

Tuning the programmable logic controller in the distributed control system of Walter-Smith modular refinery using the ITAE process parameters gotten above would minimize weeping and flooding in the column thereby ensuring maximum draw of product and maintaining temperature and pressure distribution across the tray, thus ensuring premium product quality.