(54e) Improve Column Control by Modifications to Temperature Control Strategies

As rates are increased on existing towers, quality and stability issues may surface even though the column internals can theoretically handle the increased production. Sometimes these issues can be solved by implementing a modification to a simple temperature control strategy. Temperature averaging is a very stable control method that uses two or more measured temperatures to compute an average, which is then used as the control point. This method is especially useful for towers that have a large temperature difference between top and bottom. Several examples of improved stability with regard to rate changes and process upsets will be given. Pressure compensated temperature control is another variation of the standard temperature controller that can be used to alleviate quality and capacity issues. Two examples of improved control will be presented, along with a guide on how to implement these strategies.