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Scheduling of Refinary Overhaul Activities Under Uncertainty, Case Study: Glycol Regeneration Unit of Farashband Refinary

Moradi, Hadi | 2020

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 53008 (01)
  4. University: Sharif University of Technology
  5. Department: Industrial Engineering
  6. Advisor(s): Shadrokh, Shahram
  7. Abstract:
  8. In order to maintain system reliability and high production rate, at oil, gas and petrochemical industries and other manufacturing plants, the plant is shut down and the planned maintenance activities are done on machines and equipment. In this research, a robust reliability-based scheduling for the maintenance activities are considered, in which the duration of maintenance activities and also project deadline are uncertain, start date and finish date of the shutdown are predefined and maintenance activities can be done in the multi-mode. The proposed problem is a multi-mode time-constrained project scheduling problem (MTCPSP). The glycol regeneration unit in a gas refinery is studied as the case study and at first, based on the effect of equipment or sub-equipment on the system reliability, the importance value (IV) of equipment and sub-equipment within the system is determined, and these importance values are used in a new priority rule for choosing activities in the schedule. A heuristic algorithm is employed for this problem, in which to maintain the robustness of the baseline schedule, the concept of critical chain project management (CCPM) is applied and a new definition to resource buffer is considered. A simulation methodology is applied to determine the size and location of resource buffers in the schedule in which three different buffer sizes and three different uncertainty levels are considered. Outcomes demonstrate the performance of the proposed algorithm in early or on-time delivery of the planned shutdown and reveal that if during the execution of the maintenance activities, it is forced to shorten the shutdown period, at each time before the predefined shutdown deadline, the plant can be started up with the maximum possible improvement of the system reliability
  9. Keywords:
  10. Maintenance Scheduling ; Uncertainty ; Robust Scheduling ; Heuristic Algorithm ; Critical Chain Method ; System Stability ; Multi-Mode Project Scheduling

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