Scheduling gasoline blending operations from recipe determination to shipping using unit slots

Abstract

Gasoline can yield 60%-70% of the total profit of a refinery. Integrated scheduling of gasoline blending and order delivery operations can increase profit by avoiding ship demurrage, improving customer satisfaction, minimizing quality giveaways, avoiding costly transitions and slop generation, and reducing inventory costs. In this paper, we develop a novel continuous-time formulation using unit slots for an integrated scheduling of gasoline blending operations incorporating features such as multipurpose tanks, parallel nonidentical blenders, minimum run lengths, blender setups, tank changeovers, piecewise-constant profiles for blend component qualities and feed rates, simultaneous receipt/delivery by tanks, etc. We employ and revise the schedule adjustment procedure of Li et al. [AIChE J.2010, 56, 441-465] to avoid solving mixed-integer nonlinear programming (MINLP) problems and illustrate the effectiveness of our new formulation on 14 industry-scale examples. © 2011 American Chemical Society.