The distillation unit is one of the main units in refining companies, and it serves as the mother unit in any refinery with any degree of complexity. The optimization of this unit can increase productivity. In this study, the vacuum distillation unit of a refinery is selected as the case study. The shares of different expenses of this unit are clarified using a novel material flow cost accounting (MFCA) method, the identification of the positive and negative products, and the identification of the actual values of the products. To this end, the vacuum distillation column is simulated by replacing Ahvaz’s crude oil with different types of crude oils such as Mansouri, and Maroon and also by combining these crude oils types. The results indicate the difference between the quality of Ahvaz crude oil products and Maroon and their combination is less than 2%, so it can be an appropriate alternative to the main crude oil, without changing the column operating conditions. The influence of changing the column conditions is studied, revealing the zero effect of the variations of the quality of Mansouri’s crude oil products and its blend with Ahvaz crude oil. The feed temperature was changed 20 °C while the input and bottom column pressure increased 7 and 5 mmHg respectively. But API varies from approximately 3 to 7 in the products. Finally, two types of Mansouri’s crude oil and a blend of Maroon and Ahvaz crude oil are introduced as the best alternatives to Ahvaz’s crude oil.
