Publication: Research - peer-review › Conference abstract for conference – Annual report year: 2011
Energy requirements of distillation processes account for a large percentage of the total energy consumption of the chemical industry. Hence, strategies for heat recovery have been extensively implemented in industrial processes during the last decades. However, operation (including start-up and shut-down strategies) and control of, heat-integrated systems becomes a formidable challenge if not a problem since higher-order systems dynamics occur where different time-scale phenomena interact. Furthermore, if the operation state of the process does not lie close to the designed state, the amount of energy wasted increases, questioning the economics of implementation of heat integration. Modelling is the foremost tool in assessment of chemical process dynamics. In the case of distillation, an extensive literature deals with classic distillation columns whereas much less has been investigated on dynamics of heat integrated distillation systems and the significance of developing a proper plantwide control strategy to ensure optimal and stable operation. This contribution has two aims; firstly to create a systematic framework for the modeler for developing dynamic models of distillation processes with heat-integration. To this end a computer-aided methodology was developed. Secondly, the methodology was tested in an actual industrial case, where a dynamic model for heat-integrated distillation systems is developed and used to analyse and solve operation and control problem. The system studied in the industrial case is composed of two distillation columns in series (operated at 3.5 and 1.5 bar) for recovery of ethanol from a pseudo-binary mixture (heavy key water). Heat recovery is carried out both backward (from the two bottoms flow to the feed) and forward (from the first condensate to the second reboiler). Based on a numerical model of the system, two solutions are presented for improving its control: i) a fine tuning of the existing control strategy, therefore suitable for immediate implementation; and ii) a new control structure, including sensors and actuators for long term modification of the system. The suitability of the proposed control strategies were ultimately evaluated using as input actual data of one month of operation.
|Conference||8th European Congress of Chemical Engineering|
|Period||25/09/11 → 29/09/11|
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