On-line optimization of a crude unit heat exchanger network

This paper describes modeling and on-line optimization of a crude unit heat exchanger network at the Statoil Mongstad re nery. The objective is to minimize the energy input in the gas red heater by optimally distributing the cold crude oil in the heat exchanger network. The steady state mass and energy balance of the 20 heat exchangers in the network yields the process model. This model is tted to the measured values using data reconciliation and unmeasured values like heat exchanger duty and heat transfer coeÆcients are computed. The tted model is used to compute the optimal split fractions of crude in the network. This system has been implemented at the re nery and has resulted in a 2% reduction in energy consumption. In operational modes where the unit is constrained on energy input this gives a increased throughput and a signi cant contribution to the re nery pro t.