Hinging Hyperplanes Crude Oil Mixing Model for Production Planning Optimization

Refinery feed, usually a mixture of several crude oils, is separated via a crude distillation unit (CDU). Crude true boiling point (TBP) distillation curve determines the amount of products which can be obtained via CDU separation. The TBP curve of the mixed crude feed is calculated by blending pseudocomponents from each individual crude; the blending calculation introduces a lot of nonlinear terms and makes it difficult to optimize the crude selection and the downstream refinery operation. This work proposes a continuous piecewise linear (CPWL) model to approximate the crude blending, thereby eliminating the nonlinear blending terms. A hinging hyperplanes (HH) model is employed to formulate the CPWL model. In addition, its parameters are computed by a two-layer perceptron, which is built to simulate the HH model. This leads to a mixed-integer linear model suitable for crude oil selection and cut point optimization. The proposed model enables accurate computation of the mixed crude feed TBP curve while eliminating nonlinear blending terms. Hence, it is suitable for inclusion in refinery planning models dealing with optimal crude selection.