Optimum air exchangers fans control selection in distillation columns

Air exchangers are commonly used in distillation columns to remove heat generated by the columns’ reboilers, and use the lower temperature product as reflux. The target temperature in the air exchanger outlets can be controlled by several methods, such as louvers, pitch controls (on the fan blades) or variable-speed motors. Failure to control the target temperature from the air exchangers can lead to energy losses, additional heat requirements and lost product specifications. Most air exchangers consist of several parallel units, covering a large area that makes it difficult to control the target temperature by solely depending on using air exchanger fans on-off (as a step-control). Variou