Large Volume Inorganic Chemicals - Ammonia ... - ammk-rks.net

Chapter 22.4.7 Advanced process controlDescriptionAn advanced process control (APC) system has been successfully implemented on the ammoniaplant in 2004. The APC is model-based or model predictive and the implementation did nothave a significant negative effect on operation nor was a plant shutdown caused or required.With the APC on-line in the example plant, the production is stable at record-high levels.The APC provides weighted and hierarchical optimisation. Hierarchical means that there aredifferent classes of optimisation problems. Only when one class has been solved and furtherdegrees of freedom are available, the next lower priority class will be solved. Thanks to thisfeature, the APC is able to support control strategies adapted to specific scenarios, e.g. whereplant safety takes priority over quality or where quality takes priority over energy saving.Weighted means, that within an optimisation problem, one of the variables is more importantthan another (e.g. because it costs more).Achieved environmental benefitsIn the referenced example plant, the benefits on production capacity and/or energy consumptionare significant.Cross-media effectsNone believed to be likely.Operational dataNo information provided.ApplicabilityGenerally applicable. The implementation of the same APC was expected to start for thecompany’s ammonia unit D in 2005 and was in planning for more units.EconomicsSignificant cost benefits. In the example plant, the payback actually started already during theinitial phase of project where the complete control and operating strategy of the plant wasrevised and reconsidered.Driving force for implementationCost benefits in the example plant.References to literature and example plants[19, IPCOS, 2004], Yara ammonia unit E, Sluiskil70 Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilisers