Fractional distillation column control
AssigneePhillips Petroleum Company
InventorDanny L. Furr
Life of this patent
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Abstract
In a fractional distillation column, a desired ratio between the flow rate of a side draw product stream and the internal reflux flow rate at the particular tray from which a side draw stream is withdrawn from the fractional distillation column is maintained by manipulating the flow rate of the center reflux stream so as to maintain the desired ratio between the internal reflux flow rate and a side draw product stream flow rate at the particular tray from which the side draw stream is withdrawn from the fractional distillation column. Control of the ratio between the flow rate of a side draw product stream and the internal reflux flow rate results in an improved side draw product stream purity.
Claims7
A method for maintaining a desired ratio between the flow rate of the internal reflux at a first intermediate portion of a fractional distillation column and the flow rate of a side draw product stream, wherein a side draw stream is withdrawn from said first intermediate portion of said fractional distillation column, a portion of said side draw stream being returned as an intermediate external reflux to a second intermediate portion of said fractional distillation column which is above said first intermediate portion of said fractional distillation column, a portion of said side draw stream providing said side draw product stream, said method comprising the steps of:
- using computing means to establish a first signal representative of the flow rate of said intermediate external reflux required to maintain said desired ratio between the flow rate of the internal reflux at said first intermediate portion of said fractional distillation column from which said side draw stream is withdrawn and the flow rate of said side draw product stream;
- establishing a second signal representative of the actual flow rate of said intermediate external reflux;
- using computing means to compare said first signal and said second signal and to establish a third signal responsive to the difference between said first signal and said second signal;
- and
- manipulating the flow rate of said intermediate external reflux in response to said third signal.
Dependencies are inferred from the claim text.