In this paper, a novel integrated optimization approach which couples the up-stream refinery and the down-stream ethylene plant is proposed. When the material balances of the intermediate products between the two complex processes are considered, the potential of increasing the overall margin can be explored. A multi-period enterprise-wide mixed-integer nonlinear programming (MINLP) model is formulated to optimize the production planning of the processing units in the refinery and the ethylene plant simultaneously. Due to the model complexity, the Lagrangian algorithm is applied to decompose the integrated mathematical model into an MILP problem for the refinery and a small-scale MINLP problem for the ethylene plant. The performance of the proposed model was investigated on industrial examples to illustrate the economic potential and trade-offs involved in the enterprise-wide network. Results show that the integrated approach gains improvement in overall profit compared with the traditional sequential approach.
['Hao Zhao', 'Marianthi G. Ierapetritou', 'Nikisha K. Shah', 'G. Rong']
Integrated model of refining and petrochemical plant for enterprise-wide optimization