US3770255A

US3770255A - Valve tray having means for avoiding edge erosion

Info

Publication number: US3770255A
Application number: US00266907A
Authority: US
Inventors: D Nutter
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-06-28
Filing date: 1972-06-28
Publication date: 1973-11-06
Anticipated expiration: 1990-11-06

Abstract

Valve tray apparatus has an apertured tray deck for supporting a moving body of liquid and valves associated with the apertures in the tray deck, each valve being movable from a lower position where it substantially obstructs the associated aperture to an upper position where vapors pass upwardly through the aperture and into the body of liquid. Erosion-creating edge-to-edge contact between the valve assembly and the tray deck is avoided by providing the tray deck and or the valves with flanges which result in contacting surfaces.

Description

United States Patent [191 Nutter I [451 Nov. 6, 1973 VALVE TRAY HAVING MEANS FOR AVOIDING EDGE EROSION [76] Inventor:

Okla. 74105 22] Filed: June 28, 1972 [21] Appl. No.: 266,907

Related U.S. Application Data [63] Continuation-impart of Ser. No. 216,106, Jan. 7,

1972, abandoned.

[S2] U.S. Cl. 261/114 VT [51] Int. Cl ..-B0ld 3/18 [58] Field of Search 261/114 VT [56] I References Cited UNITED STATES PATENTS Schramm 261/114 VT Dale E. Nutter, 2498 E. 49th, Tulsa,

3,693,948 9/1972 Klossj: 261/114 VT Primary Examiner-Tim R. Miles Assistant Examiner-Steven H. Marko witz Attorney-Francis C. Browne et al.

57 ABSTRACT Valve tray apparatus has an apertured tray deck for supporting a moving'body of liquid and valves associated with the apertures in the tray deck, each valve being movable from a lower position where it substantially obstructs the associated aperture to an upper p0- sition where vapors pass upwardly through the aperture and into the body of liquid; Erosion-creating edge-toedge contact between the valve assembly and the tray deck is avoided by providing the tray deck and or the valves with flanges which result in contacting surfaces.

'10 Claims, 7 Drawing Figures sir/0.255

PATENTEDHUV 6 I973 2222222; 222225252: 222222 222; 222222; 52;; 225522;: 2:25: 5222:2222 DEEZZZZZZ HUI VALVE TRAY HAVING MEANS FOR AVOIDING EDGE EROSION This is a continuation-in-part of my copending application for valve trays having means for avoiding edge erosion Ser. No. 216,106 filed Jan. 7,, 1972, and now abandoned.

This invention relates to valve tray apparatus which will possess an increased useful life due to the provision of flanges which afford contacting surfaces on the relatively movable valve assembly andthetray deck.

In many types of existing'valve trays, a vertically movable valve body has depending legs which extend downwardly through a tray aperture to guide and limit the vertical movement of the valve. In instances where the tray aperture is perfectly circular, only one surface of each of the legs will contact the edge of the tray deck. In such apparatus, erosion problems are particularly aggravated by spinning of the valves in addition to their vertical movement. However, in apparatus of the type shown in U.S. Pat. Nos. 2,951,691, 3,210,056, 3,287,004, 3,333,836 and 3,530,879, the depending legs of the valve assembly have edges which are restricted and tend to ride directly against the apertureforming edges of the tray deck. Experience has shown that erosion tends to occur in areas where the edge of the valve leg rides directly on the aperture-forming edge of the tray deck.

The valves are usually made of a corrosion resistant alloy which is relatively light so that the vapor pressure drop across each tray will not be excessive. The tray deck containing the aperture in which the valve is applied may be of thicker material such as carbon steel, a low grade material which is subject to corrosion.

During normal operation, a valve of the type shown in US. Pat. No. 2,951,691 opens in two phases. During the first phase, the valve is inclined with one side edge resting on the tray deck and the other side edge of the valve elevated from the tray deck to permit the discharge of vapor into fluid which passes over the tray deck. The degree of inclination of the valve is limited by the outturned flanges on the depending valve legs. An increase in vapor flow will cause the valve to move to its fully opened position where the outturned leg flanges will lie in contact with the underside of the tray deck. During this movement, the vertically moving side edge of the depending leg will be frictionally contacting the aperture wall. The valve and the tray then define a pair of oppositely directed slot openings for introducing vapor to the area above the tray.

In some services where severe corrosion of the deck material prevails and where design requires frequent movement of the valves, accelerated wear has been experienced at the points of frictional contact of the edges of the valve legs and the tray deck. Usually most of the wear is in the carbonsteel tray deck metal, but.

sometimes, where extremely severe corrosion exists, both the edges of the valve legs and the tray deck material wear at these points of contact and-movement.

Whenever this described wear prevails, rectangular valves of the type shown in U.S. Pat. No. 2,951,691 can shift laterally so that one side edge of the valve no longer overlies the marginal area of the tray'adjacent the aperture. This permits the valve to fall through the aperture. When this failure occurs, the complete tray assembly is beyond repair and expensive total replacement is required. 1

This invention is concerned with the avoidance of unnecessary erosion and corrosion in valve trays of the type which heretofore have relied upon the edge of the tray deck or the valve for guiding the other one of these relatively movable members.

One aspect of the invention is concerned with a valve I construction whereby the depending valve leg is bent to form a plurality of surfaces so that the surfaces, rather than the edge of the leg, will ride against the aperture-forming surface or edge in the tray deck.

Another aspect of the invention involves such apparatus provided with a downturned flange in the tray deckto confront the valve leg and provide a surface which will assist in guiding the valve legs for vertical movement. The use of such a surface, rather than the previously employed aperture-defining edge, further contributes to the advancement of this particular art. In an opimum system, both of the previously-discussed aspects of the invention will be combined to provide a valve tray which has a substantially increased resistance to apparatus-damaging erosion and corrosion.

An understanding of the invention may be had by referring to the following specification and the accompanying drawings wherein FIG. 1 is a plan view of one tray deck installed in fluid contacting apparatus;

FIG. 2 is an exploded view of a portion of the tray deck and a valve constructed according to this invenvalve units and its associated tray aperture;

FIG. 5 is a planview of one of the valve units and its associated tray aperture; and

FIGS. 6 and 7 are sectional views taken along the lines 66 and 7-7 in FIG. 3.

Valve trays according to the invention will normally be used as a vertically staged series of horizontaltrays in a vertically-orientated cylindrical tower. Arrangements of this general type are shown in the previously mentioned US. Pat. Nos. 2,951,691 and 3,530,879 which areincorporated herein by reference. Each tray in the tower will have the general appearance shown in FIG. 1 where it will be seen that the tower 2 contains a vertical plate 4 at each tray which forms the downcomer passage 6 for introducing liquid to the upstream end of the next lower tray 8. The liquid flows across the tray in a left-to-right direction as shown in FIG. 1 until it passes over the upper edge of the next downcomer plate which constitutes the overflow weir 10 and onto the upstream end of the tray therebeneath. Vapors' ascend through the housing 2 and pass upwardly through the liquid which flows across the trays 8.

Conforming to conventional practice, the tray has a pluralityof apertures, each of which has an associated valve. In the preferred embodiment, the apertures and their associated valves are elongated and have their major dimensions lying parallel to the flow path across the tray. The sides of the valve are tapered inwardly in a downstream direction which has been found to reduce the volume of liquid which weeps downwardly through the tray apertures when the valves are open, and it also tends to weight the valves so that their lighter and downstream ends will lift first when the vapors beneath the tray exert a sufficient pressure to move the valves toward their open position.

FIGS. 2-7 show the general arrangement of the valve with its associated aperture. It will be noted that the aperture 12 has its sides formed by depending flanges 14 which are turned slightly outwardly as shown in FIGS. 6 and 7, which has been found to improve the operating characteristics of the tray. The flanges 14 extendfor the entire length of the aperture.

The valves preferably are made from a piece of sheet material, cut and bent to form a main body 16 which is similar in shape to the tray aperture 12. Dimples 18 are provided toward the upstream end of the valve where they will rest on the tray deck immediately adjacent to the aperture 12. The presence of the dimples 18 provides a small preset opening 20 which may be seen in FIG. 3 to permit a slight escape of the ascending vapors and prevent locking of the valves in their closed positions.

At the opposite ends of the valves, there are depending leg portions 22 which extend downwardly through the aperture 12 to guide and limit the vertical movement of the main body 16 of the valve. At a lower portion of the leg portions 22 are laterally extending outturned feet 24 which serve as a stop means to limit the extent of upward movement of the main body 16. Those skilled in the art are familiar with this type of construction wherein the vapors tending to ascend through the aperture 12 exert a force on theundersurface of the main body 16 of the valve to lift the valve from a lower position where it substantially obstructs the aperture to an upper position where the main body 16 is spaced above the tray deck. When the main body 16 is in its upper position, the vapors are permitted to pass upwardly through the aperture 12 and through the body of liquid supported on the tray deck.

Prior to this invention, the depending valve legs had edges of sheet material which directly confronted the adjacent edge of the tray deck. Repeated useage of such apparatus, particularly in corrosive environments, caused a significant degree of erosion of the deck adjacent to the edges of the leg portions 22, occasionally requiring the equipment to be shut down for maintenance. This previous shortcoming of such apparatus has now been avoided by adding to the structure the leg flanges 26 which provide a planar face for confronting and riding against the sides of the tray deck aperture. The flanges 26 preferably extend downwardly below the feet 24 so that the valve cannot shift laterally and bind when in its uppermost position, but will maintain a consistent lateral position. Although these leg flanges 26 are useful even when the tray deck does not have the downturned flanges 14, it is preferred to use both the leg flanges 26 and the deck flanges 14 in order to provide a surface-to-surface structure for guiding the vertical movement of the valve.

The horizontal cross section of the legs is U-shaped with the base of the U being formed by the vertical base of the leg 22 and the sides of the U being formed by the leg flange 26. The use of the leg flanges is superior to the prior art construction, in part because there is no contact between the relatively movable portions of the tray deck and an edge of the sheet material used to form the valve. In structures where the tray deck does not have the depending flanges 14, the leg flanges 26 extend upwardly in close proximity to the bottom surface of the valve body 16, to prevent possible valve immobilization created by lateral shifting of the valve when in its lower position.

This invention is not limited to the specific shape of valves shown herein,but is also applicable to any type of prior valve associated with a tray deck in a fashion which causes an edge of the sheet material valve leg to move and be contacted by the tray deck. Many modifications may be made to the sole disclosed embodiment without departing from the spirit of the invention defined by the claims which follow.

I claim:

1. A fluid contact tray for supporting a body of liquid moving thereacross from an upstream location to a downstream location, comprising a liquid supporting tray deck having a plurality of apertures extending therethrough,

valve means associated with said apertures, each of said valve means having a main body portion movable under the influence of vapors ascending through the aperture from a lower position where it substantially obstructs the associated said aperture to an upper position where it is spaced above the tray deck and permits vapors to pass upwardly through the associated said aperture and through the body of liquid, each of said valve means having a plurality of leg portions extending downwardly from the main body portion and through the aperture to guide the vertical movement of the main body portion, said leg portions being movable with their associated main body portion with respect to the tray deck, and laterally extending stop means on the leg means to limit the extent of upward movement of the main body portion,

each of said leg means being formed of sheet material and having a plurality of vertical faces and a plurality of vertical edges, said faces confronting the tray deck, said edges being out of contact with the tray deck in order to avoid the vulnerability of the apparatus to edge erosion and corrosion.

2. The apparatus of claim 1 wherein the tray deck has depending flange portions confronting said faces of the leg means to provide surface-to-surface contact between the contacting relatively movable portions of the tray deck and the valve means; whereby the vulnerability to edge erosion and corrosion of the tray deck is reduced.

3. The apparatus of claim 1 wherein the legs have a horizontal cross section which-includes a base and leg flange portions.

4. The apparatus of claim 3 wherein the leg flange portions extend downwardly beyond said laterally extending stop means.

5. The apparatus of claim 1 wherein the apertures and the associated main body portions of the valves are elongated, and the legs have a horizontal cross-section which includes a base and leg flange portions.

6. The apparatus of claim 5 wherein an integral piece of sheet materials forms the main body, legs and stop means of each valve means.

7. A fluid contact tray for supporting a body of liquid moving thereacross from an upstream location to a downstream location, comprising a liquid supporting tray deck, having a plurality of apertures extending therethrough,

valve means associated with said apertures, each of said valve means having amain body portion movable under the influence of vapors ascending through the aperture from a lower position where it substantially obstructs the associated said aperture to an upper position where it is spaced above the tray deck and permits vapors to pass upwardly through the associated said aperture and through the body of liquid, each of said valve means having a plurality of leg portions extending downwardly from the main body portion and through the aperture to guide the vertical movement of the main body portion, said leg portions being movable with respect to the tray deck, each of said leg portions having a horizontal cross-section which includes a vertical base and vertical leg flange portions, and laterally extending stop means on the leg means to limit the extent of upward movement of the main body portion, said tray deck having depending flange portions confronting the opposite sides of of sheet material forms the main body, legs and stop means of each valve means.

10. The apparatus of claim 9 wherein said leg flange portions extend downwardly beyond said laterally extending stop means.

Claims

1. A fluid contact tray for supporting a body of liquid moving thereacross from an upstream location to a downstream location, comprising a liquid supporting tray deck having a plurality of apertures extending tHerethrough, valve means associated with said apertures, each of said valve means having a main body portion movable under the influence of vapors ascending through the aperture from a lower position where it substantially obstructs the associated said aperture to an upper position where it is spaced above the tray deck and permits vapors to pass upwardly through the associated said aperture and through the body of liquid, each of said valve means having a plurality of leg portions extending downwardly from the main body portion and through the aperture to guide the vertical movement of the main body portion, said leg portions being movable with their associated main body portion with respect to the tray deck, and laterally extending stop means on the leg means to limit the extent of upward movement of the main body portion, each of said leg means being formed of sheet material and having a plurality of vertical faces and a plurality of vertical edges, said faces confronting the tray deck, said edges being out of contact with the tray deck in order to avoid the vulnerability of the apparatus to edge erosion and corrosion.

3. The apparatus of claim 1 wherein the legs have a horizontal cross section which includes a base and leg flange portions.

7. A fluid contact tray for supporting a body of liquid moving thereacross from an upstream location to a downstream location, comprising a liquid supporting tray deck, having a plurality of apertures extending therethrough, valve means associated with said apertures, each of said valve means having a main body portion movable under the influence of vapors ascending through the aperture from a lower position where it substantially obstructs the associated said aperture to an upper position where it is spaced above the tray deck and permits vapors to pass upwardly through the associated said aperture and through the body of liquid, each of said valve means having a plurality of leg portions extending downwardly from the main body portion and through the aperture to guide the vertical movement of the main body portion, said leg portions being movable with respect to the tray deck, each of said leg portions having a horizontal cross-section which includes a vertical base and vertical leg flange portions, and laterally extending stop means on the leg means to limit the extent of upward movement of the main body portion, said tray deck having depending flange portions confronting the opposite sides of said leg means to provide surfaces for contact by the relatively movable portions of the valve means; whereby the vulnerability to edge erosion and corrosion of the tray deck is reduced.

8. The apparatus of claim 7 wherein the apertures and the associated main body portions of the valves are elongated.

9. The apparatus of claim 8 wherein an integral piece of sheet material forms the main body, legs and stop means of each valve means.