Energy optimization of integrated atmospheric and vacuum crude distillation units in oil refinery with light crude

The heat integration and retrofit analysis of Arabian light crude distillation units was carried out to identify opportunity for energy savings using different design options, to achieve optimum heat exchanger network. Data used were extracted from an existing and operating crude oil refining plant. The pinch analysis of existing plant using process integration software (Heat-Int) Process Integration Limited, Cheshire, United Kingdom revealed that the hot and cold utilities consumptions at the prevailing ΔT_min of 77°F in the plant were 680.23 and 521MMBtu/h, respectively. Economic evaluation of existing plant revealed total operating cost of 4829625/year. Retrofit of existing plant using different design options generated an optimal network comprised four additional heat exchangers with reduction in ΔT _min from 77°F to 57°F. The hot and cold utilities consumptions also reduced to 623.23 and 464.44MMBtu/h, respectively. Economic evaluation of the new design showed energy savings of 259860/year. The trade-off between energy and capital costs in terms of the costs procurement and installation new heat exchangers gives overall cost savings of 32800/year with payback period of 11months. The study concluded that retrofitting of existing heat exchanger network to correct those exchangers that are transferring heat across the pinch could result in enormous energy savings.