Dividing wall fractionation column control system and apparatus
AssigneeUop LLC
InventorPaul C. Steacy
Life of this patent
Estimating the term…
Abstract
A control method and apparatus for regulating the rate of vapor flow in the two adjacent sections of a dividing wall fractional distillation column are presented. The liquid level on a tray at the top of each section is used to control the rate of vapor flow through the tray. The liquid level is controlled by measuring the pressure differential across the tray in each section and varying the flow of liquid to this tray in response to the differential.
Claims11
An apparatus for controlling the relative rate of upward vapor flow in each of two parallel, partial-column contacting sections located in a middle portion of a divided wall column, the column being divided into at least said two contacting sections by a vertical dividing wall, said apparatus comprising:
- a.) a first differential pressure measuring device measuring the pressure differential between vapor-filled volumes located immediately above and below a first dedicated perforated tray located in an upper portion of a first partial-column contacting section of said column;
- b.) a second differential pressure measuring device measuring the pressure differential between vapor-filled volumes located immediately above and below a second dedicated perforated tray located in an upper portion of a second partial-column contacting section of said column;
- c.) a liquid collection tray located in the column above the first and second partial-column contacting sections of the column, the liquid collection tray having a liquid collection well and also having openings allowing the upward flow of vapor through the liquid collection tray;
- d.) a liquid withdrawal and distribution conduit system communicating with the liquid collection well of the liquid collection tray and comprising conduits for the passage of liquid from the liquid collection well to other points in the fractionation column including a first conduit having an outlet discharging onto the first dedicated tray and a second conduit having an outlet discharging onto the second dedicated tray;
- e.) a first flow control valve located in the first conduit and controlling the rate of liquid flow through the first conduit in response to a signal generated by the first pressure differential measuring device;
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- f.) a second flow control valve located in the second conduit and controlling the rate of liquid flow through the second conduit in response to a signal generated by the second pressure differential measuring device.
A method of controlling the vapor flow rate upward through two parallel partial-column contacting sections of a dividing wall section of a fractionation column which is being operated at fractionation conditions to perform a separation by fractional distillation, said method comprising the steps of:
- a.) restricting the upward escape of vapor from the two partial-column contacting sections of the column by means of a dedicated tray extending across the cross-section of each of the two partial-column contacting sections of the column, with vapor rising through each partial-column section passing through the respective dedicated trays and producing a pressure differential between the upper and lower surfaces of the respective trays;
- b.) measuring the pressure differential between the pressure above and the pressure below at least one of the dedicated trays of the two partial-column sections of the column;
- c.) collecting essentially all of the liquid flowing downward in the column at the top of the dividing wall section of the column at a trap-out tray;
- d.) adjusting the rate at which a stream of said collected liquid is delivered to at least one of the two dedicated trays in response to the pressure differential measured in step b.) to adjust the level of liquid retained on at least one of the dedicated trays, and thus adjusting the relative rate of vapor flow upward through each of the two dedicated trays;
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- e.) delivering the remainder of said collected liquid to trays within the dividing wall section which are located below the dedicated trays.
A method of controlling the vapor flow rate upward through two parallel partial-column contacting sections of a dividing wall section of a fractionation column which is being operated at fractionation conditions to perform a separation by fractional distillation, said method comprising the steps of:
- a.) restricting the upward escape of vapor from the two partial-column contacting sections of the column by means of a dedicated tray extending across the cross-section of each of the two partial-column contacting sections of the column, with vapor rising through each partial-column section passing through the respective dedicated trays and producing a pressure differential between the upper and lower surfaces of the respective trays;
- b.) measuring the pressure differential between the pressure above and the pressure below the dedicated trays of the two partial-column sections of the column;
- c.) collecting essentially all of the liquid flowing downward in the column at the top of the dividing wall section of the column at a trap-out tray;
- d.) adjusting the rates at which separate streams of said collected liquid are delivered to the two dedicated trays in response to the pressure differential measured in step b.) to adjust the level of liquid retained on each dedicated tray;
- and
- e.) delivering the remainder of said collected liquid to trays within the dividing wall section which are located below the dedicated trays.
Dependencies are inferred from the claim text.