Abstract:
A tray valve assembly for a process column of a type wherein a first, heavier fluid flows downwardly from a downcomer onto a tray and thereacross in a first direction through which a second, lighter fluid flows upwardly therethrough for interaction and mass transfer with the heavier fluid before passing therefrom. A plurality of valves disposed across a surface of the tray and mounted above a plurality of apertures on the surface of the tray, each valve of the plurality of valves comprising a top surface and at least one securement leg. A first securement leg of is adapted to intercept the heavier fluid flow in the first direction forming a diverting baffle for engaging the heavier fluid flow across the tray. Each valve includes at least one aperture to facilitate the lighter fluid flow therefrom and further comprising a first aperture in the first securement leg. The first aperture is adapted to allow the lighter fluid to flow in a second direction to interact with the heavier fluid flow in the first direction for lighter fluid aeration thereof. Each valve includes a plurality of open side regions for allowing ascending lighter fluid flow to pass outwardly therefrom in generally oppositely dispersed directions for contact with the heavier fluid flow in the first direction and each valve is adapted to allow the ascending lighter fluid flow to pass outwardly therefrom generally in the first direction of the heavier fluid flow passing over the top surface for facilitating a propulsion of the heavier fluid flow therefrom and across the tray.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application claims priority from, and incorporates by reference the entire disclosure of, U.S. Provisional Patent Application No. 60/926,707, filed Apr. 27, 2007. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to fluid-fluid contacting trays and, more particularly, but not by way of limitation, to an improved fluid impingement device and tray assembly incorporating fluid-deflector surfaces with multiple fluid-flow apertures for higher efficiency operation, which, in one embodiment, includes gas-liquid contacting trays incorporating fixed or floating valves with multiple vapor apertures. 
     2. History of Related Art 
     Distillation columns are utilized to separate selected components from a multicomponent stream. Generally, such contact columns utilize either trays, packing, or combinations thereof. In certain years the trend has been to replace so-called “bubble caps” by sieve and valve trays in most tray column designs. 
     Successful fractionation in the column is dependent upon intimate contact between heavier fluids and lighter fluids. Some contact devices, such as trays, are characterized by relatively high pressure drop and relatively high fluid hold-up. One type of contact apparatus utilizes fluid in the vapor phase to contact fluid in the liquid phase and has become popular for certain applications. Another type of contact apparatus is high-efficiency packing, which is energy efficient because it has low pressure drop and low fluid hold-up. However, these very properties at times make columns equipped with structured packing difficult to operate in a stable, consistent manner. Moreover, many applications simply require the use of trays. 
     Fractionation column trays come in two configurations: cross-flow and counter flow. The trays generally consist of a solid tray or deck having a plurality of apertures and are installed on support rings within the column. In cross-flow trays, lighter fluid ascends through the apertures and contacts heavier fluid moving across the tray, through the “active” area thereof. In this area, the heavier fluid and the lighter fluid mix and fractionation occurs. The heavier fluid is directed onto the tray by means of a vertical channel from the tray above. This channel is referred to as the Inlet Downcomer. The heavier fluid moves across the tray and exits through a similar channel referred to as the Exit Downcomer. The location of the downcomers determines the flow pattern of the heavier fluid. If there are two let Downcomers and the heavier fluid is split into two streams over each tray, it is called a two pass tray. If there is only one Inlet and one Outlet Downcomer on opposite sides of the tray, it is called a single pass tray. For two or more passes, the tray is often referred to as a Multipass Tray. The number of passes generally increases as the required (design) flow rate increases. It is the active area of the tray, however, which is of critical concern. 
     Addressing now select flow designs, a particularly effective tray in process columns is the sieve tray. This tray is constructed with a large number of apertures formed in the bottom surface. The apertures permit the ascending lighter fluid to flow into direct engagement with the heavier fluid that is flowing across the tray from the downcomer described above. When there is sufficient lighter-fluid flow upwardly through the tray, the heavier fluid is prevented from running downwardly through the apertures (referred to as “weeping”). A small degree of weeping is normal in trays while a larger degree of weeping is detrimental to the capacity and efficiency of a tray. 
     Tray efficiency is also known to be improved in sieve type trays by increasing the froth height of the heavier fluid and reducing the backflow of the heavier fluid flowing across the tray. Froth is created when lighter fluid “bubbles” percolate upwardly through the heavier fluid flowing across the tray. The suspension of the lighter fluid in the heavier fluid prolongs the fluid-fluid contact which enhances the efficiency of the process. The longer the froth is maintained and the higher the froth is established, the greater the fluid-fluid retention. Higher froth requires smaller “bubbles” formed at a sufficiently slow rate. Likewise, backflow occurs beneath the froth when circulating currents of heavier fluid are established during the heavier fluid flow across the plate. This generally forms along the lateral portions thereof. These currents carry the heavier fluid back across the tray in a manner that reduces the concentration-difference driving force for mass transfer. It is the concentration-difference between the lighter fluid and the heavier fluid which enhances the effectiveness of the fluid-fluid contact. 
     The concentration-difference between the lighter fluid and the heavier fluid can be effected in many ways; some reducing efficiency. For example, as operating pressure increases, the heavier fluid begins to absorb lighter fluid as it moves across a tray. This is above that normally dissolved in the heavier fluid and represents much larger amounts of lighter-fluid bubbles that are comingled or “entrained” with the heavier fluid. This lighter fluid is not firmly held and is released within the downcomer, and, in fact, the majority of said lighter fluid must be released otherwise the downcomer cannot accommodate the heavier fluid/lighter fluid mixture and will flood, thus preventing successful tower operation. This phenomena is generally deemed to occur when operating pressure is such as to produce a lighter fluid density above about 1.0 lbs/cu. ft. and typically amounts to about 10 to 20% of the lighter fluid by volume. For conventional trays, as shown below, the released lighter fluid must oppose the descending frothy lighter fluid/heavier fluid mixture flowing over the weir into the downcomer. In many cases, such opposition leads to poor tower operation and premature flooding. 
     When a vapor comprises the lighter fluid and a liquid comprises the heavier fluid, there are specific performance issues. Certain performance and design issues are seen in the publication “Distillation Tray Fundamentals”, M. J. Lockett, Cambridge University Press, 1986. Other examples are seen in several prior art patents, which include U.S. Pat. Nos. 3,959,419, 4,604,247 and 4,597,916, each assigned Glitsch, Inc., and U.S. Pat. No. 4,603,022 issued to Mitsubishi Jukogyo Kabushiki Kaisha of Tokyo, Japan. A particularly relevant reference is seen in U.S. Pat. No. 4,499,035 assigned to Union Carbide Corporation that teaches a gas-liquid contacting tray with improved inlet bubbling means. A cross-flow tray of the type described above is therein shown with improved means for initiating bubble activity at the tray inlet comprising spaced apart, imperforate wall members extending substantially vertically upwardly and transverse to the liquid flow path. The structural configuration is said to promote activity over a larger tray surface than that afforded by simple perforated tray assemblies. This is accomplished in part by providing a raised region adjacent the downcomer area for facilitating gas ascension therethrough. 
     U.S. Pat. No. 4,550,000 assigned to Shell Oil Company teaches an apparatus for contacting a liquid with a gas in a relationship between vertically stacked trays in a tower. The apertures in a given tray are provided for the passage of gas in a manner less hampered by liquid coming from a discharge means of the next upper tray. This is provided by perforated housings secured to the tray deck beneath the downcomers for breaking up the descending liquid flow. Such advances in tray designs improve efficiency within the confines of prior art structures. Likewise, U.S. Pat. No. 4,543,219 assigned to Nippon Kayaku Kabushiki Kaisha of Tokyo, Japan teaches a baffle-tray tower. The operational parameters of high gas-liquid contact efficiency and the need for low pressure loss are set forth. Such references are useful in illustrating the need for high efficiency lighter fluid/heavier fluid contact in tray process towers. U.S. Pat. No. 4,504,426 issued to Karl T. Chuang et. al. and assigned to Atomic Energy of Canada Limited is yet another example of gas-liquid contacting apparatus. 
     Several prior patents have specifically addressed the tray design and the apertures in the active tray deck area itself. For example, U.S. Pat. No. 3,146,280 is a 1964 patent teaching a directional float valve. The gas is induced to discharge from the inclined valve in a predefined direction depending on the orientation of the valve in the tray deck. Such valve configurations are often designed for particular applications and flow characteristics. Tray valves with weighted sides and various shapes have thus found widespread acceptance in the prior art. A circular valve structure is shown in U.S. Pat. No. 3,287,004 while a rectangular valve structure is shown in U.S. Pat. No. 2,951,691. Both of these patents issuing to I. E. Nutter, teach specific aspects of gas-liquid contact flow utilizing tray valve systems. Such specialized designs are necessary because lighter fluid/heavier fluid flow problems must be considered for each application in which a tray is fed by a downcomer. The type of flow valve, its orientation, and the lighter-fluid flow apertures for lighter fluid-heavier fluid flow interaction are some of the issues addressed by the present invention. 
     Addressing specifically now the type of flow valve, its orientation, and the lighter-fluid flow apertures that currently are taught by the prior art. Attention is directed to two patents in which one of the co-inventors of the present application, Michael J. Binkley, is a co-inventor. U.S. Pat. Nos. 5,147,584 and 5,120,474, both teach certain valve-tray designs and contact tray assemblies and methods. In the contact tray assemblies and the valve designs, it may be seen that the individual valves whether fixed or floating, are illustrated in the drawings with solid surfaces. In other words, both the front and rear legs, as well as the top surface of the valves, whether floating or fixed, are shown to be of solid construction. Other contact-tray valve assemblies are set forth and shown in U.S. Pat. Nos. 6,145,816; 5,911,922; 5,762,834; and 6,089,550. Each of these patents further illustrate aspects of contact tray assemblies and methods as well as valve designs. Additional patents which should likewise be reviewed relative to contact trays include the following four patents in which the Applicant hereof, Michael J. Binkley, is a co-inventor and include: U.S. Pat. Nos. 5,453,222; 4,956,127; 5,106,556; 5,277,848; and 5,192,466. The above-referenced patents and statements with regard to the related art are set forth for purposes of understanding the intricacies of the design considerations in contact-tray assembly and method configurations. It would be an advantage to provide a method of and apparatus for enhanced fluid flow manifesting increased efficiency with a valve design having either a fixed or floating configuration relative to the tray and with multiple fluid-flow apertures formed therein for enhanced fluid interaction. The methods of and apparatus for valve tray assemblies and methods are herein set forth and shown. 
     SUMMARY OF THE INVENTION 
     A tray valve assembly for a process column of a type wherein a first, heavier fluid flows downwardly from a downcomer onto a tray and thereacross in a first direction through which a second, lighter fluid flows upwardly therethrough for interaction and mass transfer with the heavier fluid before passing therefrom. The assembly comprises a plurality of apertures formed on a surface of the tray for facilitating the lighter fluid flow upwardly therethrough, a plurality of valves disposed across the surface of the tray and mounted above the plurality of apertures formed on the surface of the tray, each valve of the plurality of valves comprising a top surface and at least one securement leg, and a first securement leg of the at least one securement leg is adapted to intercept the heavier fluid flow in the first direction forming a diverting baffle for engaging the heavier fluid flow across the tray. Each valve of the plurality of valves comprising at least one aperture to facilitate the lighter fluid flow therefrom and further comprising a first aperture in the first securement leg wherein the first aperture is adapted to allow the lighter fluid to flow in a second direction to interact with the heavier fluid flow in the first direction for lighter fluid aeration thereof. Each valve of the plurality valves comprising a plurality of open side regions for allowing ascending lighter fluid flow to pass outwardly therefrom in generally oppositely dispersed directions for contact with the heavier fluid flow in the first direction and each valve of the plurality of valves is adapted to allow the ascending lighter fluid flow to pass outwardly therefrom generally in the first direction of the heavier fluid flow passing over the top surface for facilitating a propulsion of the heavier fluid flow therefrom and across the tray. 
     A method of mixing a first, heavier fluid flowing downwardly from a downcomer onto a tray and thereacross in a first direction with a second, lighter fluid flowing upwardly therethrough for interaction and mass transfer with the heavier fluid before passing therefrom. The method includes forming, on a surface of the tray, a plurality of apertures for facilitating the lighter fluid flow upwardly therethrough, disposing, above the plurality of apertures formed on the surface of the tray, a plurality of valves, wherein each valve of the plurality of valves comprising a top surface and at least one securement leg, and intercepting, via a first securement leg of the at least one securement leg, the heavier fluid flow in the first direction to form a diverting baffle for engaging the heavier fluid flow across the tray. The method further includes forming, in each valve of the plurality of valves, a plurality of apertures to facilitate the lighter fluid flow therefrom, wherein a first aperture is formed in the first securement leg, allowing, via the first aperture, the lighter fluid to flow in a second direction to interact with the heavier liquid flow in the first direction for lighter fluid aeration thereof, allowing, via a plurality of open side regions, the ascending lighter fluid flow to pass outwardly therefrom in generally oppositely disposed directions for contact with the heavier fluid flow in the first direction, and allowing, via each valve of the plurality of valves, ascending lighter fluid flow to pass outwardly therefrom generally in the first direction of heavier fluid flow passing over the top surface for facilitating a propulsion of the heavier fluid flow therefrom and across the tray. 
     A valve for use in a tray valve assembly for a process column of a type wherein a first, heavier fluid flows downwardly from a downcomer onto a tray and thereacross in a first direction through which a second, lighter fluid flows upwardly therethrough for interaction and mass transfer with the heavier fluid before passing therefrom. The valve includes at least one securement leg having a first aperture formed therein, a top surface having a second aperture formed therein, a plurality of open side valve regions, and a first securement leg of the at least one securement leg being adapted to intercept the heavier fluid flow in the first direction forming a diverting baffle for engaging the heavier fluid flow across the tray. The first aperture being adapted to allow the lighter fluid to flow in a second direction to interact with the heavier fluid flow in the first direction for lighter fluid aeration thereof. The plurality of open side valve regions being adapted to allow ascending lighter fluid flow to pass outwardly therefrom in generally oppositely disposed directions for contact with the heavier fluid flow in the first direction. The valve is further adapted to allow the ascending lighter fluid flow to pass outwardly therefrom generally in the first direction of the heavier fluid flow passing over the top surface for facilitating a propulsion of the heavier fluid flow therefrom and across the tray. 
     A valve for use in a tray valve assembly for a process column of a type wherein a first, heavier fluid flows downwardly from a downcomer onto a tray and thereacross in a first direction through which a second, lighter fluid flows upwardly therethrough for interaction and mass transfer with the heavier fluid before passing therefrom. The valve includes a first securement leg having at least a first aperture formed therein, a second securement leg having at least a second aperture formed therein, a plurality of open side valve regions, the first securement leg being adapted to intercept the heavier fluid flow in the first direction forming a diverting baffle for engaging the heavier fluid flow across the tray. The first aperture being adapted to allow the lighter fluid to flow in a second direction to interact with the heavier fluid flow in the first direction for lighter fluid aeration thereof. The plurality of open side valve regions being adapted to allow the ascending lighter fluid flow to pass outwardly therefrom in generally oppositely disposed directions for contact with the heavier fluid flow in the first direction. The valve is further adapted to allow the ascending lighter fluid flow to pass outwardly therefrom generally in the first direction of the heavier fluid flow for facilitating a propulsion of the heavier fluid flow therefrom and across the tray. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the method and system of the present invention may be obtained by reference to the following Detailed Description when taken in conjunction with the accompanying Drawings wherein: 
         FIG. 1  is a perspective view of a prior art packed column with various sections cut away for illustrating, diagrammatically, a variety of tower; 
         FIG. 2  is a diagrammatic, side-elevational, cross-sectional view of a prior art downcomer-tray assembly secured within a process tower and illustrating the flow of heavier fluid thereacross and lighter fluid upwardly therethrough; 
         FIG. 3  is a top-plan, diagrammatic view of a prior art tray illustrating problems with fluid flow thereacross; 
         FIG. 4  is a perspective view of one embodiment of a downcomer-tray assembly constructed in accordance with the principles of the present invention and having portions thereof cut away for purposes of clarity; 
         FIG. 5  is an enlarged perspective view of one valve of the tray surface in accordance with an embodiment of the present invention; 
         FIG. 6  is a side-elevational cross-sectional view of the valve structure of  FIG. 5  in accordance with an embodiment of the present invention; 
         FIG. 7  is a side-elevational view of an alternative embodiment of the valve structure of  FIG. 5  in accordance with an embodiment of the present invention; 
         FIG. 8  is a perspective view of a valve structure comprising a fixed rectangular valve assembly in accordance with an embodiment of the present invention; 
         FIG. 9  is a perspective view of a valve structure comprising a fixed trapezoidal valve assembly in accordance with an embodiment of the present invention; and 
         FIG. 10  is a perspective view of a valve assembly comprising a fixed trapezoidal valve assembly in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Various embodiments of the present invention will now be described more fully with reference to the accompanying drawings. The invention may, however, be embodied in many different forms and should not be constructed as limited to the embodiments set forth herein; rather, the embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
     Referring first to  FIG. 1 , there is shown a fragmentary, perspective view of an illustrative prior art packed exchange tower or column  12  with various sections cut away for showing a variety of tower internals and the utilization of one embodiment of an improved high-capacity tray assembly. The exchange column  10  of  FIG. 1  comprises a cylindrical tower  12  having a plurality of packing bed layers  14  and trays disposed therein. A plurality of manways  16  are likewise constructed for facilitating access to the internal region of the tower  12 . Also provided are side stream draw-off line  20 , heavier-fluid side feed line  18 , and side stream lighter-fluid feed line or reboiler return line  32 . A reflux return line  34  is provided atop the column  10 . 
     In operation, heavier fluid  13  is fed into the column  10  through reflux return line  34  and side stream feed-input feed line  18 . The heavier fluid  13  flows downwardly through the tower  12  and ultimately leaves the tower  12  either at side stream draw-off line  20 , or at bottom-stream draw-off line  30 . In the case of a vapor-liquid tower, the heavier fluid  13 , during its downward flow, is depleted of some material which evaporate from it as it passes through the trays and packing beds, and is enriched or added to by material which condenses into it out of the lighter fluid stream. 
     Still referring to  FIG. 1 , the exchange column  10  is diagrammatically cut in half for purposes of clarity. In this illustration, the column  10  includes a lighter-fluid outlet in overhead line  26  disposed atop the tower  12  and a lower skirt  28  disposed in the lower region of the tower  12  around bottom stream takeoff line  30  coupled to a reboiler (not explicitly shown). Reboiler return conduit  32  is shown disposed above the lower skirt  28  for recycling lighter fluid therein upwardly through the trays and/or packing layers  14 . Reflux from condensers is provided in the upper tower region  23  through entry conduit  34  wherein reflux is distributed throughout a distributor  36  across upper packing bed  38 . According to exemplary embodiments, the upper packing bed  38  is of the structured packing variety. The regions of the exchange column  10  beneath the upper packing bed  38  are shown for the purpose of illustration and include a heavier fluid collector  40  disposed beneath a support grid  41  in support of the upper structured packing  38 . The column  10  is presented with cut-line  43  for illustrating the fact that the tower internals arrangement is diagrammatical only and is provided for referencing various component arrays therein. 
     Referring still to  FIG. 1 , an assembly of a pair of trays is also shown for purposes of illustration. In many instances, process columns contain only packing, only trays, or combinations of packing and trays. The present illustration is, however, a combination for purposes of discussion of the overall tower and its operation. A trayed column usually contains a plurality of trays  48  of the type shown herein. In many instances, the trays  48  are valve or sieve trays. According to an exemplary embodiment, the trays  48  are valve trays. The trays  48  comprise plates which may be, for example, punched or slotted in construction. Within the scope of the invention and for the purposes of the description of various embodiments herein, the configuration referred to as a “valve” includes anything at the intersection of and facilitating the contact between a lighter fluid and a heavier fluid. The lighter fluid and the heavier fluid engage at or along the tray  48  and, in some assemblies, are permitted to flow through the same openings in a counter-current flow arrangement. Optimally, the lighter-fluid and heavier-fluid flows reach a level of stability. With the utilization of appropriate downcomers, to be described in more detail below, this stability may be achieved with a relatively low flow rate permitting the ascending lighter fluid to mix with the descending heavier fluid. In some embodiments, no downcomers are used and the lighter fluid and the heavier fluid use the same openings, alternating as the respective pressures change. 
     According to an exemplary embodiment, cross-flow valve trays  48  and  49  and downcomers  53  and  69  are illustrated. Tray  48  is constructed with a plurality of floating valves. Tray  49  also illustrates a raised inlet section  51  beneath downcomer  53 , which is substantially planar, formed with a plurality of apertures, and which may include a series of momentum deflector barriers, as will be described below. The raised inlet area is described in more detail in U.S. Pat. No. 4,956,127 (the &#39;127 patent). Corrosion is another consideration in designing packed towers and for the selection of the material, design, and the fabrication of the tower internals. 
     Referring now to  FIG. 2 , there is shown a is a diagrammatic, side-elevational, cross-sectional view of a prior art downcomer-tray assembly secured within a process tower and illustrating the flow of heavier fluid thereacross and lighter fluid upwardly therethrough. An upper tray  48  comprises a first valved panel. The lower tray  49  is also of generally planar construction across its central active area  52 , having a plurality of valves  100  mounted thereon, disposed therein, or formed therefrom as diagrammatically shown. Heavier fluid  13  travels down a downcomer  53  having a tapered or mitered bottom section  54 , from tray  48  disposed thereabove. The tapered section  54  of the downcomer provides a clearance angle for lighter fluid flow from the active inlet area, which clearance angle affords a horizontal flow vector to the lighter fluid vented through raised panel  51 . The heavier fluid  13  engages lighter fluid  15  discharged from the raised active panel area  51  beneath the downcomer  53 . 
     Still referring to  FIG. 2 , the froth  61  extends with a relatively uniform height, shown in phantom by line  63  across the width of the tray  49  to the opposite end  65  where a weir  67  is established for maintaining the froth height  63 . The accumulated froth at this point flows over the top of the weir  67  into associated downcomer  69  that carries the froth downwardly into a mitered region  70  where the heavier fluid accumulates and disperses upon active inlet region  71  therebeneath. Again active inlet region  71  is shown herein diagrammatically for purposes of illustration only. As stated herein, the area of holes and perforations for a single cross-flow plate establish the active length of the plate and the zone in which the froth  61  is established. It should be noted that the present invention would also be applicable to multiple downcomer configurations, wherein the downcomers and raised, active inlet areas (if incorporated) may be positioned in intermediate areas of the trays as also described below. By increasing the total active area of active inlet areas  51  and  71 , greater capacity and efficiency is achieved. It is also the manner of flow of the heavier fluid  13  across the tray  49  which is critical to tray efficiency. 
     Referring now to  FIG. 3 , there is shown a top-plan, diagrammatic view of a prior art tray illustrating problems with fluid flow thereacrossthere. The prior art tray  72  is illustrated herein as a round unit having a first conventional downcomer for feeding heavier fluid upon a solid, underlying panel  73  and then to the tray  74 . A second downcomer  74 A carries heavier fluid away from the tray. A plurality of arrows  75  illustrate the non-uniform flow of heavier fluid  13  typically observed across a conventional prior art tray which does not address the circulation issue. Circular flow is shown to be formed on both sides of the plate lateral to the direction of primary flow. The formation of these retrograde flow areas, or recirculation cells  76 , decreases the efficiency of the tray. Recirculation cells  76  are the result of retrograde flow near the walls of the process column and this backflow problem becomes more pronounced as the diameter of the column increases. With the increase in retrograde flow and the resultant stagnation effect from the recirculation cells, concentration-difference driving force for mass transfer between the counter-flowing streams is reduced. The reduction in concentration-difference driving force will result in more contact or height requirement for a given separation in the column. Although back mixing is but a single aspect of plate efficiency, the reduction thereof is provided concurrently with the other advantages hereof. Reference is again made to the plate efficiency discussion set forth in above referenced &#39;127 patent. 
     Referring now to  FIG. 4 , there is shown a perspective view of a downcomer-tray assembly  99  constructed in accordance with principles of the present invention and having portions thereof cut away for purposes of clarity and illustrated with a downcomer and raised inlet region. Conventional materials such as, for example, stainless steel or other corrosion resistant material may be utilized, as is well known in the art. The tray  49 , as shown herein, is also constructed for placement in the tower  12  by conventional means. In the tower, a feeding downcomer  102 , having an inclined face  103 , is disposed over a raised inlet region  104  for discharging heavier fluid  13  to tray  49 . A weir  82  is disposed on the opposite side of tray  49  whereby a second downcomer is disposed for carrying heavier fluid  13  away from the tray  49 . Heavier fluid  13  spills down upon the inlet region  104  and over upstanding edge  112  onto the tray  49 . It should be noted that neither the downcomer nor the raised inlet region  104  is a part of the present invention. 
     Still referring to  FIG. 4 , there is shown a plurality of valves  100  uniformly spread across tray  49 . The plurality of valves  100  are diagrammatically shown, but, as will be more fully described below, the plurality of valves  100  can be formed in both “fixed” and “floating” configurations. In one embodiment, the plurality of valves  100  are uniformly disposed across the entire surface of tray  49 . However, various other embodiments are contemplated where the pattern of the plurality of valves  100  is staggered or varied across a single tray  49 . As will be described in more detail below, the heavier fluid  13 , flowing across the tray  49 , encounters a lighter fluid  15  flowing up through the plurality of valves  100  for interaction therewith. The design of the plurality of valves  100  is configured to increase the efficiency of that interaction. 
     In one embodiment, the plurality of valves  100  are diagrammatically shown as rectangles, but, as will be more fully described below, the plurality of valves  100  can be formed of a plurality of shapes. In one embodiment, the valves  100  are uniformly disposed across the entire surface of tray  49 . For example,  FIG. 4  shows a portion of two different exemplary uniform patterns  1100 . 
     Referring now to  FIG. 5 , there is shown an enlarged perspective view of a floating valve  100  in accordance with an embodiment of the present invention. The floating valve  100  is a separate structure inserted into tray  49 . The floating valve  100  comprises a front securement leg  132  and a rear securement leg  134  depending from a generally circular top surface  130 . According to an exemplary embodiment, the top surface  130  comprises a circular disc. The floating valve  100  is mounted within the surface of tray  49  and disposed above an aperture  136  formed therein. The aperture  136  includes a pair of slotted regions  138  and  139  adapted for receiving the securement legs  132  and  134 , respectively. There are multiple advantages in utilizing this type of floating valve  100 . The orientation of the floating valve  100  relative to the heavier fluid flow is determined by the alignment and spacing of the slotted regions  138  and  139  which allows for not only the upward flotation of the circular disc  130  for the passage of lighter fluid therebeneath, but also the secured orientation thereof. It is important that the valves  100  maintain the orientation shown in  FIG. 4 . According to exemplary embodiments, the floating valve  100  acts as a deflecting plate that deflects impinging fluid-flow across the tray  49  in order to disperse rising fluid  15  coming through the tray  49  into heavier fluid  140  stream thereacross. 
     The floating valve  100  includes one or more apertures on each surface thereof. In one embodiment, the valve  100  has one aperture on three surfaces forming three distinct apertures therein. Aperture  137 C is formed in the top surface  130  thereof while upstream aperture  137 D is formed in the front securement leg  132  thereof and downstream aperture  137 E is formed in the rear securement leg  134  thereof. These apertures  137 C,  137 D,  137 E in conjunction with the open valve areas  137 A and  137 B, permit an improved lighter fluid/heavier fluid interaction due to the multiplicity of lighter-fluid flow areas constructed with the valve  100 . According to an exemplary embodiment, the size of the valve  100  has been shown to be effective in the assembly of a tray having an active area with approximately 25-50 valves per square foot. Other sizes are, of course, contemplated by the present invention. This valve density per square foot is substantially higher than possible with valves of the conventional size of 11/2″ to 17/8″ in diameter. Prior art valve density on the order of 12-14 valves per square foot has been common. The increased density is a result of the smaller size of valve  100  and its directional thrust design as herein described, which permits it to be spaced close to adjacent valves as shown. The various embodiments of the present invention are a marked advance over prior art designs utilizing larger valves and broader spacing. The efficiency of the tray is thought to be enhanced therefrom. 
     Still referring to  FIG. 5 , heavier-fluid flow is illustrated with arrow  140  flowing in a direction of the circular disc  130 . As the heavier-fluid flow  140  engages the frontal leg  132  of the floating valve  100 , it is seen to split into bi-directional flow  141  traveling around the circumference of the circular aperture  136 . Lighter fluid  15  venting beneath circular disc  130  is represented by arrows  142 A,  142 B,  142 C,  142 D, and  142 E, which arrows illustrate the biased direction that the lighter fluid  15  has in discharge from beneath the circular disc  130 . More particularly, it is shown in  FIG. 5  how the heavier-fluid flow  140  interacts with the lighter-fluid flow  15  due to the multiplicity of apertures formed in the valve  100 . As shown herein and as described above, the floating valve  100  is constructed with the multiplicity of areas for lighter-fluid flow, including open side regions  137 A and  137 B, top aperture  137 C, upstream aperture  137 D, and downstream aperture  137 E. It may be seen that the lighter fluid flow  142 A,  142 B,  142 C,  142 D and  142 E each extend through their respective valve openings  137 A and  137 B as well as apertures  137 C,  137 D and  137 E. These lighter-fluid flow areas allow interaction between the lighter fluid  15  and the heavier fluid  140  in such a way that maximum interaction is afforded. 
     Referring still to  FIG. 5 , it may be seen that the orientation of the floating valve  100  both induces the lighter fluid flow  142 C to be in a direction substantially along the path of the heavier fluid flow  140  to further promote the directional flow of heavier fluid as well as the lighter fluid flow  142 E occurring against the path of the heavier fluid flow  140  to further enhance interaction. It should be noted that the “directional thrust” aspect of the valve is provided in conjunction with the multiple-aperture interaction therein afforded by the multiple apertures across the legs and top surface thereof to further enhance the heavier fluid/lighter fluid interaction. 
     Referring now to  FIG. 6  there is shown, according to an exemplary embodiment, the floating valve  100  including top surface  130  containing aperture  137 C of  FIG. 5  in a side elevational, cross-section view. Front securement leg  132  is seen to include upstream aperture  137 D for affording lighter fluid/heavier fluid interaction with heavier-fluid flow  140  coming across the tray  49 . Lighter fluid  15  ascending through the tray  49  is exhausted as represented by arrows  142 A,  142 B,  142 C,  142 D and  142 E. The escaping lighter fluid flow represented by arrows  142 A,  142 B,  142 C,  142 D, and  142 E interacts immediately with heavier fluid flow  140  and continues downstream of the rear securement leg  134  having downstream aperture  137 E formed therein. In one embodiment, the aperture on the top surface or leg surface is punched to leave a tab that also functions as a deflection surface. 
     Referring now to  FIG. 7  there is shown a side-elevational view of an alternative embodiment of a valve structure in accordance with an embodiment of the present invention. Tray  49  includes a valve  200  which is constructed with a downstream aperture  201 , a top aperture  202 , and an upstream aperture  203  which further facilitate lighter-fluid dispersion therefrom in conjunction with the dispersion of lighter fluid through the openings at the sides of the valve as described above. In this particular embodiment, a floating valve  200  is seen with an angulated top surface  220  relative the flow of flow  140  of heavier fluid thereacross. In this embodiment the angulated top surface  220  of the floating valve  200  faces the incoming flow  140  to enhance the fluid-fluid interaction and reduce resistance to heavy fluid flow, however, the angulated top surface  220  may be angulated in the opposite direction or any other direction depending on the design requirements. It should further be noted that valves of both floating and fixed configuration are contemplated by the spirit and scope of the present invention. 
     Referring now to  FIG. 8 , there is illustrated a perspective view of a valve structure  200  comprising a fixed rectangular valve assembly in accordance with an embodiment of the present invention. The fixed valve  200  comprises a front securement leg  204  and a rear securement leg  205  depending from a generally rectangular top surface  201 . The fixed valve  200  is mounted within the surface of tray  49  and disposed above an aperture  212  formed therein. The fixed valve  200  includes one or more apertures on each surface thereof. In one embodiment, the fixed valve  200  includes one aperture on three surfaces forming three distinct apertures therein. Aperture  202  is formed in the top surface  201  thereof while aperture  208  is formed in the front securement leg  204  thereof and aperture  203  is formed in the rear securement leg  205  thereof. In these embodiments, the front and rear securement legs  204 ,  205  extend from the top surface  201  of the fixed valve  200  down to tray  49  and are secured thereagainst. According to an exemplary embodiment, aperture  202  is shown as a slot whose length runs transverse to the length of the top surface  201  of the floating valve  200 . However, it is contemplated that the aperture  202  can be of any size and shape and in any direction depending on the design requirements. According to an exemplary embodiment, only fixed rectangular valves  200  are illustrated; however, the valves  200  can be formed in both “fixed” and “floating” configurations. 
     Similarly,  FIG. 9 , there is illustrated a perspective view of a valve structure  200  comprising a fixed trapezoidal valve assembly in accordance with an embodiment of the present invention. The fixed valve  200  comprises a front securement leg  204  and a rear securement leg  205  depending from a generally trapezoidal top surface  201 . The fixed valve  200  is mounted within the surface of tray  49  and disposed above an aperture formed therein. The fixed trapezoidal valve  200  includes one or more apertures on each surface thereof. In one embodiment, the fixed valve  200  has one aperture on three surfaces forming three distinct apertures therein. Aperture  202  is formed in the top surface  201  thereof while aperture  208  is formed in the front securement leg  204  thereof and aperture  203  is formed in the rear securement leg  205  thereof. Apertures  202 ,  203 ,  208  operate to allow the discharge of lighter fluid therefrom. In these embodiments, the front and rear securement legs  204 ,  205  extend from the top surface  201  of the fixed valve  200  down to tray  49  and are secured thereagainst. According to an exemplary embodiment, the aperture  202  is shown as a slot whose length runs transverse to the length of the top surface  201  of the valve  200 . However, it is contemplated that the aperture  202  can be of any size and shape and in any direction depending on the design requirements. According to an exemplary embodiment, only fixed trapezoidal valves  200  are illustrated; however, the valves  200  can be formed in both “fixed” and “floating” configurations. 
     Referring now to  FIG. 10 , there is illustrated a perspective view of a valve assembly  300  comprising a fixed trapezoidal valve assembly in accordance with an embodiment of the present invention. The fixed trapezoidal valve  300  is shown made from a protrusion of tray  49 . In this embodiment, the fixed trapezoidal valve  300  acts as a deflecting plate that deflects impinging fluid-flow across the tray  49  in order to disperse rising lighter fluid coming through the tray  49  into the heavier fluid stream thereacross. According to an exemplary embodiment, the fixed trapezoidal valve  300  can be an integral unit formed out of the tray  49  or can be a separate structure fastened to the tray  49  at one end. In one embodiment, the fixed trapezoidal valve  300  is formed by punching a hole into the tray  49  of less than 360 degrees so that a tab  349  is formed. The tab  349  includes a top aperture  302 A and front aperture  302 B. According to an exemplary embodiment, the aperture  302 A is shown as a slot whose length runs transverse to the length of the top surface of the tab  349  while aperture  302 B is “T” shaped. However, it is contemplated that the apertures  302 A and  302  B can be of any size and shape and in any direction depending on the design requirements. 
     In summary, this patent application is provided to further teach the utilization of both fixed and floating valves in a contact tray assembly that is designed to enhance lighter fluid/heavier fluid interaction utilizing a multiplicity of valve configurations. The contact trays may have a plurality of valves of a multitude of shapes. The plurality of valves may have one or more apertures in the top and one or more apertures on one or more legs depending from the top surface. 
     Although various embodiments of the method and apparatus of the present invention have been illustrated in the accompanying Drawings and described in the foregoing Detailed Description, it will be understood that the invention is not limited to the embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the spirit of the invention as set forth herein.