Commercial ROSE units have demonstrated overall savings of up to 50 percent compared to conventional solvent-extraction processes that use evaporation, compression and condensation. By eliminating the need to evaporate a major portion of the extraction solvent, the size and complexity of the ROSE unit is reduced. This, in turn, leads to reduced investment costs and further energy savings. The relative simplicity of the ROSE process facilitates smooth start-up and operation and minimizes operator requirements. A ROSE unit can be designed to yield deasphalted oils ranging from lube-oil blending stocks to fluid catalytic cracker feedstock, depending on the solvent selected for the extraction.
Further flexibility is possible by designing the unit to generate two, three or more products.
A two-stage ROSE unit makes deasphalted oil and a heavy product. The three-stage unit produces a deasphalted oil and separates the heavy product into resins and asphaltenes, further improving the refiner's ability to meet market demands for asphalts and other specialty products. Deasphalted oil is a relatively clean product, substantially lower in metals and carbon-residue contaminants than the resin and asphaltene fractions. Deasphalted oil is readily processed in a downstream fluid catalytic cracker or hydrocracker. Resins, an intermediate fraction, act as a peptizing agent to maintain a homogenous solution of asphaltenes, resins and oils to produce a stable asphalt with desired properties.