Exergy cost accounting thermoeconomic analysis of an oil refinery operating at off-design conditions

ABSTRACT

Reducing crude oil quality affects the refinery capacity, quality for downstream units, and overall economics. The thermoeconomic model of a refinery can show that the effects of faults generally propagate through the whole process and affect the behavior of several components, resulting in induced malfunction in typical components. This study aims to estimate the primary source of inefficiency and, therefore, the main reason for the increase in irreversibility and entering feed into the refinery due to changes in some operating conditions. Operating conditions in 2013 and 2023 are defined as base mode and operating mode, respectively. The results of exergy cost analysis show that Liquefied Petroleum Gases (LPG) unit and H₂S removal unit have the greatest impact on reducing the overall performance of the refinery in 2023, while this unit is one of the units with the least exergy destruction in the base year. The share of the environment and fuel oil unit, LPG unit, H₂S removal unit, and kerosene treating unit in increasing the irreversibility of the utility unit is 4,898.18, 1200.67, 935.15, 642.73, and 624.45 GJ/day, respectively. The share of the Crude Distillation Unit (CDU) in the reduction of the irreversibility of the utility unit is 7,316.67. The results show that the total resource consumption has increased by 168 MJ/day. Therefore, in order to reduce resource consumption in 2030 (operational mode), the impact of LPG and H₂S removal units on utility irreversibility should be controlled.

KEYWORDS:

• Exergy cost accounting
• Oil refinery
• Exergy analysis
• Malfunction diagnosis
• Resource consumption

Nomenclature

DFDysfunction	=
$\dot{E}$Exergy flow [kW]	=
FFuel flow rate [kW]	=
$⟨FP⟩$Matrix of exergy distribution ratios (n×n)	=
hEnthalpy flow [kW/kg]	=
IIrreversibility rate [kW]	=
kunit exergy consumption	=
MFMalfunction	=
$⟨\mathbf{K}\mathbf{P}⟩$unit exergy consumption matrix	=
nNumber of components of the system	=
PProduct rate [kW]	=
$⟨\mathbf{P}\mathbf{F}⟩$Matrix of exergy junction ratios (n×n)	=
$<\left.{\mathbf{P}}^{\ast }\right|$Cost matrix operator (n×n)	=
sEntropy flow [kW/kg]	=
TTemperature [K]	=
rJunction Ratios: elements of matrix $⟨PF⟩$	=
${\mathbf{U}}_{\mathbf{D}}$Identity matrix (n×n)	=
xmass fraction	=
Greek letters	=
$\epsilon$exergy efficiency	=
$\gamma$activity coefficient	=
$\kappa$marginal exergy consumption	=
$\mathrm{\Delta }$difference	=
Subscripts	=
0Environment	=
i, jGeneral index	=
PProduct	=
Superscripts	=
0reference mode (design mode)	=

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. Aviation Turbine Kerosene.

Additional information

Notes on contributors

Morteza Khosravirad

Morteza Khosravirad: He is a PhD candidate of chemical engineering in Islamic Azad University, Science and Research Branch, Tehran. He is very high industrial experience in the field of oil and gas, process engineering and factory managnment.

Amir Heydarinasab

Amir heydarinasab: He is an associate professor at the Faculty of Chemical and Petroleum Engineering, Islamic Azad University, Science and Research Branch, Tehran. He received his PhD degree in chemical engineering from Amirkabir University of Technology. He is presently working in the field of separation, nanotechnology, dynamic modeling of oil reservoirs, carbon dioxide capture and stabilization, and air pollution modeling, and he has published many research papers highly reputed journals.

Fatemeh Joda

Fatemeh Joda: She is assistance professor at the faculty of mechanical and Energy Engineering, Shahid Beheshti University, Tehran. She has received PhD degree in chemical engineering. She has published many research papers highly reputed journal.

Seyed Abolhassan Alavi

Seyed Abolhassan Alavi: He is an associate professor at the Faculty of Chemical and Petroleum Engineering, Islamic Azad University, Science and Research Branch, Tehran. He received his PhD degree in chemical engineering from The University of Manchester(UMIST). He is working in the field of Biofuels, Biomass Conversion, Renewable Energy Technologies and Hydrolysis.