The distillation unit is one of the main units in refning companies, and it serves as the mother unit in any refnery with any degree of complexity. The optimization of this unit can increase productivity. In this study, the vacuum distillation unit of a refnery was selected as the case study.
The shares of different expenses of this unit were clarifed using a novel material flow cost accounting (MFCA) method, the identifcation of the positive and negative products, and the identifcation of the actual values of the products. To this end, the vacuum distillation column was 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 showed that the difference between the quality of Ahvaz crude oil products and Maroon and their combination was 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 was also studied which revealed 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 varied 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 were introduced as the best alternatives to Ahvaz’s crude oil.