Improving energy saving of crude oil distillation units with optimal operations

As the most energy intensive sector in refinery industry, crude oil distillation unit can affect the overall energy consumption of a plant by up to 20%. Improving energy saving is an important factor of cleaner production and environmental impacts for crude oil distillation units. Many technologies regarding retrofit of heat exchanger network and optimal operations have been proposed to increase the energy and economic efficiencies of crude oil distillation units in the last decades. However, it is still a challenge of implementing traditional methods in practice, for instance, retrofitting are commonly restricted by process topology, safety and maintenance constraints and may lead to high capital costs because of considerable civil works; while operation models usually suffers from the computational difficulty caused by complex unit performances. To deal with the above problems, this paper presents an optimal operation strategy for improving energy efficiency of crude oil distillation units without any structural modifications. First, detailed process operations are formulated and expressed as a complex nonlinear programming model, which is then solved with a double-loop algorithm. The objective of the proposed method is to minimize process energy utilization while retain its economic benefit. This work provides an efficient tool to help engineers handily adjust process key parameters to achieve higher energy saving than the traditional approaches, especially up to 1.06 MW of energy reduction without additional retrofit investment in an industrial case. This is also equivalent to 2800 tons of CO2 emission reduction per year, and thus intensifying the overall sustainability profile of the crude oil distillation processes.