A simultaneous optimization strategy for overall integration in refinery planning

The refining industry is under immense pressure to produce cleaner products but faces low economic margins because of stricter environmental regulatio ns and depressed market demand. In this situation, refinery planning become s very important as it can exploit all potential opportunities to push the economic margin to the maximum limit. This paper presents a method for over all refinery optimization through integration of the hydrogen network and t he utility system with the material processing system. The problem of optim izing each of these three systems is very complex in its own right. To make the problem of overall optimization solvable, the current practice adopts a decomposition approach, in which material processing is optimized first u sing linear programming (LP) techniques to maximize the overall profit. The n, supporting systems, including the hydrogen network and the utility syste m, are optimized to reduce operating costs for the fixed process conditions determined from the LP optimization. Essentially these three systems are d ealt with separately, which usually leads to nonoptimal solutions for refin ery operations. A new optimization method is proposed that is developed on the basis of a sound understanding of interactions between the three system s and the proper use of mathematical modeling. This method considers the op timization of refinery liquid flows, hydrogen flows, and steam and power fl ows simultaneously. As a result, this method furnishes new insights into th e problem of refinery optimization and can provide significant benefits to the refining industry in exploiting the true potential of the processes and obtaining truly optimal operation.