WO1998028056A1 - Soupape fixe - Google Patents

Soupape fixe Download PDF

Info

Publication number
WO1998028056A1
WO1998028056A1 PCT/US1997/021577 US9721577W WO9828056A1 WO 1998028056 A1 WO1998028056 A1 WO 1998028056A1 US 9721577 W US9721577 W US 9721577W WO 9828056 A1 WO9828056 A1 WO 9828056A1
Authority
WO
WIPO (PCT)
Prior art keywords
tray
arch
perforation
flow direction
liquid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US1997/021577
Other languages
English (en)
Inventor
John Harris
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Saint Gobain Norpro Corp
Original Assignee
Norton Chemical Process Products Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Norton Chemical Process Products Corp filed Critical Norton Chemical Process Products Corp
Publication of WO1998028056A1 publication Critical patent/WO1998028056A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • B01D3/16—Fractionating columns in which vapour bubbles through liquid
    • B01D3/163—Plates with valves
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • B01D3/16—Fractionating columns in which vapour bubbles through liquid
    • B01D3/22—Fractionating columns in which vapour bubbles through liquid with horizontal sieve plates or grids; Construction of sieve plates or grids

Definitions

  • This invention relates to chemical process equipment in which a liquid is contacted with a counterflow of gas. This may be for a variety of purposes such as stripping a component from the liquid stream or absorbing a component into a liquid stream. More generically this invention relates to equipment designed to facilitate mass and/or heat transfer between phases .
  • the type of equipment to which this invention specifically relates employs cross-flow fractionation trays connected by downcomers .
  • a tower is provided with a plurality of fractionation trays arranged generally horizontally within the tower.
  • Each tower has a perforated tray and at least one channel, called a downcomer, in which a liquid flowing over the tray may be collected and channeled to the tray below.
  • a gas or vapor is introduced at the base of the tower and passes upwards through the perforations in the trays of the fractionation trays. Meanwhile a liquid is introduced at the top of the tower and percolates downward passing across the fractionation trays and down the downcomers to the tray below.
  • the trays are conventionally made of metal and particularly a metal adapted to withstand the environment in which it is expected to operate.
  • the metal will be a stainless steel.
  • Such metals are relatively easy to engineer and trouble free while in use, though expensive in terms or materials.
  • the tray Upon reaching each tray, the liquid flows across the tray in what is described here as the "design flow direction", which indicates the direction the liquid is intended to flow when the tray is operating in optimum design conditions.
  • the tray is provided with a plurality of perforations through which gas bubbles continuously at a pressure that, under normal operating conditions, precludes the liquid from passing through the perforation. These perforations are referred to as “valves” and it is to an improved design for such valves that this invention particularly pertains.
  • the liquid should be prevented from passing through the valves in the trays by the pressure of gas passing through the perforations in the upward direction.
  • This is a finely balanced process since, if the pressure is too great, the gas will have a shorter transit time within the tower and less efficient contact with the down-flowing liquid.
  • the high gas velocity may also cause liquid droplets to be carried up to the tray above, thereby reducing the separation efficiency as a result of back-mixing.
  • the gas flow rate is too low the liquid will penetrate through the valves in the trays, (known as "weeping"), and short-circuit the flow patterns which are intended to maximize liquid/gas contacts.
  • valve designs actually allow the valve to close if the pressure drops too low. Such valves can however cause problems if they stick closed or only partially open. They are also expensive. Other valve designs merely place a cover over a perforation in the tray tray to prevent liquid falling on to the perforation with sufficient velocity to penetrate even when the pressure is at design levels.
  • the present invention provides a simple valve design that is obtained by a simple deformation of the material from which the tray is produced.
  • the tray can be produced, with the valves already in place, with no need for a further installation operation.
  • Such arrangements are already known in principle but are often only partially unsuccessful at minimizing weeping.
  • the present invention provides a highly effective means of contacting liquid flowing over and around the valve with gas flowing up through the valve with reduced weeping and all in the context of a fixed valve formed by deformation of the material of the tray itself.
  • the present invention provides a fractionation tray having a design flow direction and at least one perforation therein formed by deformation of the material of the tray out of the plane of the tray to form an arch member spanning the perforation and oriented in the design flow direction in the vicinity of the perforation, said arch being provided with a centrally-located depression and correspondingly, on the underside of the arch member, a rib extending substantially the length of the arch member in the design flow direction.
  • the bridge member forces the gas rising through the perforation to exit laterally so that the gas contacts the liquid flowing around the leg members essentially at right angles.
  • the gas flow does not have any significant imposed directional component since it merely contacts the undersurface of the arch member and scatters in directions limited only by the attachment of the arch to the tray.
  • the energy in the gas flow is somewhat dissipated by the impact on the arch undersurface.
  • the novel contribution of the present invention is the provision of a central depression in the arch member which provides a corresponding central rib on the underside.
  • the depression is so deep that the lowest point of the rib above the surface of the tray is from about 30 to about 60%, and preferably from about 40 to 55%, of the maximum height of the arch above the tray.
  • the length of the rib is preferably at least 60% and more preferably at least 75% of the length of the perforation in the design flow direction.
  • the arch is connected to the tray in effect by legs which are described as the "upstream” and “downstream” legs with the "stream” direction being the design flow direction.
  • Figure 1 is a plan view of a valve according to the invention.
  • Figure 2 is a cross-section at right angles to the design flow direction of the valve shown in Figure 1 at the midpoint of the arch member.
  • Figure 3 is a cross-section along the design flow direction at the center line of the valve shown in Figure 1.
  • the device illustrated in Figures 1, 2 and 3 comprises a arch member, 1, spanning a perforation, 2 in the tray, 3.
  • the arch is provided with a depression, 4, with a corresponding rib, 5, on the underside of the arch.
  • the arch is shown as a curved structure and indeed this is the preferred form as well the most simple to construct by deformation from the material of the tray. The depression and corresponding rib would then be located in the horizontal connecting portion of such a structure. It is therefore understood that the present invention embraces also such alternative forms of arch.
  • a tray In operation a tray has a large number of perforations which are usually circular, though other shapes such as elliptical and even polygonal are usable.
  • the preferred locations of the perforations on the tray is in lines across the design flow direction with adjacent lines staggered such that the perforations in one line are between pairs of perforations in the lines on either side along the design flow direction. This ensures that the flows are repeatedly split and combined to ensure that no flow of liquid develops that is not contacted by the up-rising gas.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

Abstract

L'invention concerne un plateau de fractionnement comportant des perforations enjambées par des éléments arqués (1) formés par déformation d'un matériau identique au matériau dont est constitué le plateau (3). L'élément arqué (1) présente une face inférieure nervurée façonnée pour dévier en douceur le gaz montant à travers les perforations de manière qu'il rencontre l'écoulement de liquide sensiblement perpendiculairement.
PCT/US1997/021577 1996-12-20 1997-11-25 Soupape fixe Ceased WO1998028056A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US77178096A 1996-12-20 1996-12-20
US08/771,780 1996-12-20

Publications (1)

Publication Number Publication Date
WO1998028056A1 true WO1998028056A1 (fr) 1998-07-02

Family

ID=25092950

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1997/021577 Ceased WO1998028056A1 (fr) 1996-12-20 1997-11-25 Soupape fixe

Country Status (1)

Country Link
WO (1) WO1998028056A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6460833B2 (en) 2000-02-16 2002-10-08 Shell Oil Company Gas-liquid contacting column
US6494440B2 (en) * 2000-02-16 2002-12-17 Shell Oil Company Gas-liquid contacting tray
US6588735B2 (en) 2000-02-16 2003-07-08 Shell Oil Company Gas-liquid tray
WO2004071636A2 (fr) 2003-02-06 2004-08-26 Sulzer Chemtech Ag Appareil a plateaux, colonne munie de cet appareil et procede d'assemblage et d'utilisation correspondant
US6863267B2 (en) 2000-02-16 2005-03-08 Shell Oil Company Gas-liquid contacting tray
US6866254B2 (en) 2000-02-16 2005-03-15 Shell Oil Company Gas-liquid contact tray

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1595892A (fr) * 1968-12-02 1970-06-15
US3759494A (en) * 1971-07-21 1973-09-18 L Axelrod Valve plate of column still
DE2223654A1 (de) * 1972-05-15 1973-11-29 Stage Hermann Ventilboden fuer stoffaustauschkolonnen
DE2708683A1 (de) * 1977-02-28 1978-08-31 Inst Nawozow Sztucznych Zjedno Reaktor zur synthese von harnstoff

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1595892A (fr) * 1968-12-02 1970-06-15
US3759494A (en) * 1971-07-21 1973-09-18 L Axelrod Valve plate of column still
DE2223654A1 (de) * 1972-05-15 1973-11-29 Stage Hermann Ventilboden fuer stoffaustauschkolonnen
DE2708683A1 (de) * 1977-02-28 1978-08-31 Inst Nawozow Sztucznych Zjedno Reaktor zur synthese von harnstoff

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6460833B2 (en) 2000-02-16 2002-10-08 Shell Oil Company Gas-liquid contacting column
US6494440B2 (en) * 2000-02-16 2002-12-17 Shell Oil Company Gas-liquid contacting tray
US6588735B2 (en) 2000-02-16 2003-07-08 Shell Oil Company Gas-liquid tray
US6863267B2 (en) 2000-02-16 2005-03-08 Shell Oil Company Gas-liquid contacting tray
US6866254B2 (en) 2000-02-16 2005-03-15 Shell Oil Company Gas-liquid contact tray
US6902154B2 (en) 2000-02-16 2005-06-07 Shell Oil Company Gas-liquid contact tray having multiple downcomers
WO2004071636A2 (fr) 2003-02-06 2004-08-26 Sulzer Chemtech Ag Appareil a plateaux, colonne munie de cet appareil et procede d'assemblage et d'utilisation correspondant
US7770873B2 (en) 2003-02-06 2010-08-10 Sulzer Chemtech Ag Tray apparatus, column with same and method of assembling and using

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