A near-global optimization
approach is proposed to design blending
recipes for refinery products under uncertainties. In the refining
industry, the most valuable products, such as gasoline and diesel,
are produced by blending several intermediate feedstocks to maximize
profit and ensure that all qualities are on specification. Because
of the presence of property uncertainties, optimal blending recipes
under linear mixing laws should be designed by solving a linear program
with joint chance constraints. However, joint chance-constrained programming
is generally intractable even with Gaussian distributions, and thereby,
it is usually converted to an individual chance-constrained (ICC)
program to achieve a conservative approximation. To reduce this conservatism,
we find a global optimal solution for the ICC program. In case studies,
a multiproduct blending problem with 12 chance constraints and a crude
oil procurement example with 14 chance constraints are studied to
test and compare the proposed scheme with state-of-the-art optimization
software to demonstrate its superior performance in terms of computational
time.