(122c) Heat Exchanger Network (HEN) Retrofit for a Sustainable Energy Efficient Design in Aramco’s Lube Refinery

Industrial sector is accountable for approximately one-third of world-wide energy usage that relies on fossil fuels as the primary source of energy. A significant percentage of energy consumed is spent to supply utilities for oil & gas facilities so that energy could be engendered for other sectors. The adverse impact of fossil-fuel combustion has instigated efforts to minimize carbon emissions, whilst environmental regulations have a substantial effect on the energy’s production cost. Furthermore, it is a competitive world with ever-increasing energy prices, industrial communities are convened to brainstorm over conservation of energy resources and profitability. Energy efficiency should be a foundational strategy to support plans to meet the climate policy goals as well as for being lucrative. Energy efficiency with its integral role in energy intensive refining processes is critically essential to achieve desired energy-saving potential and reduction in CO₂ emissions. Pinch technology imparts a systematic technique for saving energy in processes and on entire sites. This technique helps optimize thermal heat recovery, and immediately became popular as a theoretically elegant yet feasible approach to design Heat Exchanger Networks (HENs). The paper illustrates, through a case study, the ‘plant lifetime retrofitability’ concept in a standard oil refinery’s VDU plant. The study demonstrates the impact of energy demand reduction by identifying retrofit projects for a Vacuum distillation unit (VDU), utilizing retrofit with retrofit in mind approach. The case study’s objective is to look for the most inexpensive retrofit projects via arranging each initiative in phases for implementation using the existing topology and available capital investments. Each energy saving’ initiative is implemented in a way that does not hinder the future identified initiatives. The analysis was conducted with a commercially available Heat-Int software, with an initial minimum temperature difference (ΔT_min) of 34°C with corresponding hot and cold utility requirements of 21.53 Gcal/hr and 17.13 Gcal/hr, respectively. The analytical outcomes disclosed a 2.02 Gcal/hr energy reduction in the vacuum distillation unit (VDU) with simultaneous generation of MP and LP steams of 4.4 and 3.8 tonnes/hr, respectively. The proposed modification can be implemented in three phases, execution of each phase retrofit won’t hinder the future retrofits and beyond.