Integrated short-term scheduling and production planning in an ethylene plant based on Lagrangian decomposition.

A cracking furnace, which is the major unit involved in ethylene production, produces various petrochemical products ranging from ethylene to pitch and determines the production yield of an ethylene plant. It is essential to consider the operational performances of the cracking furnaces and to incorporate them into the whole plant's planning problem. Facing this challenge, this paper developed an optimization model, which integrates the scheduling problem of upstream cracking furnaces and the operational planning of the downstream units under a synchronized global time scale. Moreover, a modified Lagrangian decomposition algorithm is proposed for solving the large-scale mixed integer nonlinear optimization problem. An industrial case study demonstrates the feasibility of the integrated model and the effectiveness of the solution algorithm. [ABSTRACT FROM AUTHOR]