Abstract: In a fractional distillation process in which a pump around stream is utilized to control heat removal from an upper portion of the fractional distillation column and in which the pump around stream is utilized to preheat the feed stream flowing to the fractional distillation column, control signals derived from an analysis of the overhead product stream from the fractional distillation column are utilized to substantially maximize the flow rate of the pump around stream. This results in a maximum preheating of the feed stream flowing to the fractional distillation column which improves the energy efficiency of the fractional distillation process. Also, a desired overhead product specification is maintained.

Abstract: A measurement of the amount of infrared radiation coming from the flame associated with a flare stack is utilized to manipulate the flow of steam to the flare stack so as to reduce the emission of smoke from the flare stack when a combustible waste gas containing hydrocarbons is being burned in the flare stack.

Abstract: In a fractional distillation column in which at least a first component and a second component are at least partially separated with the first component being removed principally as an overhead product and the second component being removed principally as a bottoms product and in which the heat supplied to the fractional distillation column is used as the primary control for the overhead product composition with the flow rate of external reflux to the fractional distillation column being used to control the bottoms product composition, a comparison of the actual concentration of the second component in the overhead product to the desired concentration is utilized to bias the control signal which is utilized to manipulate the flow rate of the external reflux to the fractional distillation column.

Abstract: In a selective hydrogenation process wherein at least two catalyst beds in series are utilized, the temperature of the feed stream flowing to the first catalyst bed and the temperature of the feed stream flowing from the first catalyst bed to the second catalyst bed are controlled using a combination of feed forward and feed back control. The feed forward control is based on the change in a process variable during a specified period of time. The feed back control is based on a comparison to the actual concentration of acetylene in the product stream flowing from the second catalyst bed to the desired concentration of acetylene in the product stream flowing from the second catalyst bed.