Dynamics and Control During Start-up of Energy Integrated Distillation Column

To advocate the usage of process integration in industrial practice, it is important to be able to guarantee not only robust control during near steady state operation, but also to provide procedures for generating fast and reliable start-up sequences. This contribution concentrates on describing a systematic procedure for development of plant start-up sequences. The basis for the start-up procedure development is available qualitative process knowledge. Application of the start-up sequence generation procedure is demonstrated upon an energy integrated distillation plant. This plant illustrates some of the inherent effects of process integration upon a start-up procedure. In particular the effect of energy recycle upon the possible start-up sequence, and the effect of using an actuator f or control purposes, i.e. the heat pump, which in itself requires significant start-up time. The experimental application of a generated start-up sequence illustrates that safe and reliable start- ups are ensured. The main conclusions of the paper are that it is indeed possible to generate safe and reliable start-up sequences using qualitative process knowledge. However the selection of an optimal start-up sequence is not possible based upon qualitative process knowledge alone.