LANNING MODEL
A typical oil refinery generates several streams that are blended in order to specify a commercial product. Furthermore, there are products with different grades that must satisfy market demands. The model described here assumes the existence of several processing units, producing a variety of intermediate streams, with different properties, that can be blended to constitute the desired kinds of products. The topology of the refinery is defined by sets that specify the connections among units as well as among streams and units. Figure 1 presents an overview of these concepts as applied to a typical unit.