Condition monitoring predictive strategies

Dynamic simulation may be used for off-line or on-line applications. An offline dynamic model runs independent of the plant. This is a predictive mode in which a column or an entire process is simulated to predict transient behavior with no input from the plant. Such a model is typically used for the design of equipment and control strategies and as a training simulator. An on-line dynamic model may be used to monitor the column performance and to provide vital information for the control system. It reads current plant conditions and, in real time, computes properties that are not measured on-line, such as product compositions. This makes it possible to control such properties directly. The on-line dynamic simulator can also predict future column trends, thereby allowing the control system to take corrective action in advance. 

As is well-known in practice, the protein folding properties and, hence the product quality is dependent on the cultivation conditions of the host organism. Thus, in order to guarantee products within narrow specification limits, the production process must be kept under tight control (4). An essential prerequisite is accurate monitoring of the process state and an optimization of the trajectories of the key process variables. Advanced control strategies require to predict the process behaviour at least over time horizons which are needed to influence the process so that the state variables will not escape from the acceptable intervals. Prediction, however, means that the process has to be modelled. 

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