Refining plant energy optimization

Abstract

A refining plant in the Middle East began official production in 2020 to produce strategic products. After production stabilization, the plant operators decided to implement energy optimization. While the refining plant utilizes a large number of units, only four units were selected for optimization. In addition, two scenarios were studied for optimization. Scenario 1 involves stopping the use of the sour water stripper units (SWS) to save 18.85 ton/h of steam used for stripping. The SWSs strip hydrogen sulfide (H2S) and ammonia from the sour water of the refinery units. Meanwhile, scenario 2 considered optimizing the steam used in the SWSs and amine regeneration units (ARUs). The ARUs regenerate rich amine using H2S from all the refining units to provide the lean amine required for gas sweetening. The overhead acid gas from the SWSs and ARUs feed the sulfur recovery unit (SRU) to prevent emissions from exceeding environmental regulations. The feed to steam ratio of the SWS reboilers was optimized from 0.17 to 0.16 kg steam/kg feed) and from 0.14 to 0.10 kg steam/kg feed for the ARU reboilers. Overall, scenario 2 saved 23.09 ton/h of stripped steam. After a feasibility analysis, scenario 2 was selected for implementation. Considering the average steam cost of 7.6$/ton, scenario 2 saved 1,537,206.38 $/year. In total, five different simulations were conducted in this study, four of which were performed using Aspen HYSYS V.11. Conversely, the other simulation, which simulated the entire SRU plant, used a special sulfur package. In addition, a combined heat and power model was used to evaluate the thermodynamic properties, material, and energy balance equations for the live steam balances.

Keywords

• Amine regeneration unit
• Energy optimization
• Refining plant optimization
• Sour water stripping
• Sulfur recovery unit