Process control considerations

Timothy C. Frank, Ph.D. Research Scientist and Sr. Technical Leader, The Dow Chemical Company Member, American Institute of Chemical Engineers (Section Editor, Introduction and Overview, Thermodynamic Basis for Liquid-Liquid Extraction, Solvent Screening Methods, Liquid-Liquid Diversion Fundamentals, Process Fundamentals and Basic Calculation Methods, Dual-Solvent Fractional Extraction, Extractor Selection, Packed Columns, Agitated Extraction Columns, Mixer-Settler Equipment, Centrifugal Extractors, Process Control Considerations, Liquid-Liquid Phase Separation Equipment, Emerging Developments)... 

Poor interface control allows the main liquid-liquid interface to leave the extractor. This may result from inadequate size of interface flow control valves, or operation with internals that provide inverse control responses such as those observed with sieve tray extractors. (See Process-Control Considerations. )... 

Because of the computational complexities associated with dynamic process simulation for rrmltiunit processes, there is still much to be done before simulators of this type become available for general application. Another problem complicating their development is that process nnodels for even individual separation units ate usually for steady-state cases this is the result of both incomplete understanding of the chemical and physical nciples involved and computational difficulties. This is one of the main reasons why process control considerations ate difficult to incorporate into chemical process simulation and thesis and why on-line plant optimization is still far away in most instances. 

Bandaruk, W., Process control considerations for adhesive bonding in production, Journal of Applied Polymer Science, 6(20) 217-220, March/April 1962. 

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