US3468521A

US3468521A - Splash directing fill for cooling towers

Info

Publication number: US3468521A
Application number: US678709A
Authority: US
Inventors: Donn B Furlong; Glenn F Hallett; Warren F Kane
Original assignee: Fluor Prod Co
Current assignee: CUSTODIS-ECODYNE Inc; Fluor Prod Co; FLUOR PRODUCTS CO Inc
Priority date: 1967-10-27
Filing date: 1967-10-27
Publication date: 1969-09-23
Anticipated expiration: 1986-09-23
Also published as: DE1805438A1; DE1805438B2; ES359347A1; GB1193530A; JPS5336172B1

Description

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p 1969 o. B. FURLQNG ETAL SPLASH DIRECTING FILL FOR COOLING TOWERS Filed on, 27, 1967 United States Patent 3,468,521 SPLASH DIRECTING FILL FOR COOLING TOWERS Donn B. Furlong, Glenn F. Hallett, and Warren F.

Kane, Santa Rosa, Califi, assignors to Fluor Products Company, Inc., Santa Rosa, Calif., a corporation of California Filed Oct. 27, 1967, Ser. No. 678,709 Int. Cl. F28c 1/00 US. Cl. 261-111 11 Claims ABSTRACT OF THE DISCLOSURE The disclosed fill, which is easily installable in a cooling tower, includes a strip adapted to extend endwise with horizontal elongation in the tower in a transverse direction substantially normal to the lateral air fiow direction. The strip has an elongated edge that is convex in vertical lateral planes and that faces laterally toward the oncoming air fiow. The strip also has an upper surface the major extent of which slopes downwardly and laterally to terminate at the convex edge in such relation that the upper surface which receives dropping liquid directs splash travel of such liquid upwardly and laterally countercurrently into the oncoming lateral air fiow, and at the same time the bulk of the water filmed on the upper surface drains toward the convex edge.

Background of the invention This invention relates generally to fill assemblies for use primarily in mechanical draft water cooling towers, and more specifically concerns fill assemblies of novel construction and mode of operation such as will compensate for lateral defiection of falling water drops in crossflow and counterfiow cooling towers.

Crossfiow towers typically are constructed to have a basic shell or enclosure on two vertical end walls, with louvered openings located at the side walls to pass air laterally into the tower interior. At the top of the tower are one or more fans rotatin gin shrouds or housings for discharging air from the tower, as well as hot water distribution basins. Hot water from the latter is distributed by metering orifices to fall within the tower, wherein it is broken up into droplets by splashing on the fill strips, the water also filming On such strips. The air cooled water is ultimately collected in a cool water basin structure at the bottom of the tower, for recirculation.

Counterfiow towers typically are constructed to have a basic shell or enclosure on all sides with louvered openings located on the lower portion of from two to four side walls for air admission to the tower. The top of the tower is covered with decking on which are mounted one or more fans rotating in housings for discharging the vapor laden air from the tower. Hot water (to be cooled) is distributed over the filled portion of the tower by troughs or piping systems with outlet nozzles. Hot water from these nozzles falls within the tower, where it is broken up into droplets by splashing on the fill strips, the water also filming on such strips. The air cooled water is ultimately collected in a cold water basin at the bottom of the tower, for recirculation.

Cooling is accompl shed essentially by evaporation from the surface of droplets and films, and by sensible heat transfer from Water surfaces to the circulating air, (usually designated as mass transfer and heat transfer respectively). The air velocity through the filling, and the elapsed time of free fall of water through the filling, are of importance in effecting the heat transfer. The fill strip configuration and spacing relative to adjacent fill strips determines, to a degree, the time of fall. The more closely spaced the fill strips, the longer the water is exposed to 3,468,521 Patented Sept. 23, 1969 the air currents within the tower, with resultant greater evaporation and sensible heat transfer to the air. As a practical limit to the amount of fill utilized, the pressure drop of air through the fill increases with the amount of fill, requiring more fan horsepower to maintain such'air movement. Further, the fill strip configuration and spacing determines the rate and extent of water splash and resulting breakup into water particles. The greater the breakup, the greater the exposure of water droplets to circulating air; hence, the greater the heat transfer.

Among the problems associated with prior towers of the above type are the tendency of the splash from conventional fill strips to be moved inwardly and downwardly by the air currents, leaving outwardly located fill portions with a lower water concentration and with concomitant reduced cooling effectiveness; undesirable pressure drops caused by impingement of air currents on blunt, sharp edged slats; undesirable slat sagging with resultant channeling and uneven distribution of water; and absence of an easily installable fill configuration and mounting overcoming these and other problems associated with cooling tower construction and operation.

Further in counterfiow towers the inlet air velocity through the louvers is fairly high, which can cause the air fiow to be directed away from the side wall above the louver opening. The top of the louver opening is a sharp edged orifice having bad air fiow characteristics. Portions of the fill near the louver may not get proper splash or film surface development because of the drops being diverted inwardly by the high velocity inlet air stream.

Similarly other portions of the tower such as corners near the side wall may not get proper splash or film surface development, due to high velocity air outside these areas directing splash away from these areas.

Summary of the invention It is a major object of the invention to provide a cooling tower fill configuration and installation of unusually advantageous construction and mode of operation characterized as overcoming the problems discussed above. Basically, the fill is constructed for installation in a crossfiow cooling tower wherein air is displaced to fiow directionally generally laterally within the tower in cooling relation with dropping particulate liquid, as for example water. The fill strip extends, or is adapted to extend, endwisewithin the tower with generally horizontal elongation in a transverse direction substantially normal to the lateral air flow direction, the strip having elongated edge extent that is convex in vertical lateral planes and faces laterally toward the oncoming air flow, the strip also having an upper surface the major extent of which slopes downwardly and laterally to terminate at the edge in such relation that the upper surface receiving the dropping liquid directs splash travel thereof upwardly and laterally countercurrently into the oncoming lateral air fiow defiected upwardly by the convex edge. As a result, the

splash formed droplets are directed toward the air inlet wall of the tower, tending to keep the entirety of the fill'volume wetted. In this regard, the fill strip may contain multitudinous vertical through openings distributed over the area defined by the sloping upper surface, to achieve even greater water breakup and result splash, i.e.- in addition to drops forming at the lower edges of the fill strip and to drops formed by splashing from the top surface. Further, the fill causes air turbulence in areas of the -tower previously having lesser air flow in order to achieve greater air-water contact for heat and mass transfer. In counterfiow towers the fill causes the splash to be directed to areas previously having insufiicient splash or water film surface development.

More specifically, the invention further contemplates a fill strip having support legs including a forward leg defining the convex edge, typically of leading edge airfoil configuration, and rearward leg spaced laterally from the forward leg. The rearward leg characteristically has substantially greater vertical dimension than the vertical dimension of the forward leg, the strip also including webbing interconnecting the legs and defining the slanted upper surface overlying the space between the legs. Further, the construction is preferably such that the convex edge extent merges with an upper plane defined by the webbing and with a lower plane defined by the lowermost portions of the legs, whereby air impinging laterally n the convex edge extent is smoothly deflected above the upper plane and below the lower plane, with concomitant minimum pressure drop. The upper surface of the fill strip may also incorporate transversely elongated shoulders acting to retard direct downward and lateral flow, toward the convex edge, of liquid filmed on the upper surface, for additional cooling contact with air, and for diverting liquid toward the vertical through perforations to increase drop formation.

In addition, the improved fill slat or strip may be made structurally strong enough, though extended, to span a greater distance between supporting hangers or members, than is possible with conventional slats. This object is enhanced by forming the forward leg in the shape of a web loop or curl extending endwise of the strip. Also, the rearward leg may typically include a foot projecting laterally away from the loop for engagement with tower structure to resist endwise displacement of the strip, as will be described.

Finally, the fill strip is especially constructed to perform the above functions and at the same time to be easily installed in tower gridding extending in vertical lateral planes which are transversely spaced to define strip hangers, the gridding sized to receive the strips when inserted transversely endwise in partially rotated condition and to interfit the strips when the latter are rotated counterclockwise into supported positions.

These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following detailed description of the drawings, in which:

Brief description of the drawings FIG. 1 is a vertical elevation taken through a crossflow cooling tower showing the fill strip of the invention in installed position;

FIG. 2 is a perspective view showing typical details of fill strip installation on grid hangers and supports for the latter;

FIG. 3 is a plan view of one form of fill strip incorporating the invention;

FIG. 4 is a vertical elevation taken on line 4-4 of FIG. 3;

FIGS. 5a and 5b are vertical sections showing the manner of installing the fill strip in hanger gridding;

FIG. 50 is a fragmentary plan view of the FIG. 5b installed strip;

FIG. 6 is a plan view of modified fill strip;

FIG. 7 is a vertical elevation showing still another form of the fill strip;

FIG. 8 is a plan view of the FIG. 7 strip;

FIG. 9 is a vertical section taken through a representative crossflow cooling tower; and

FIG. 10 is a view like FIG. 9, but taken through a counterfiow cooling tower.

Description of preferred embodiments Referring first to FIGS. 1 and 9, a crossflow cooling tower 10 is shown as having a housing 11 incorporating a top 12 defining a water distributing pan 13. Liquid such as water to be cooled is pumped at 14 into the pan, from which the liquid drains via suitable outlets 15. After descending through the fill or packing 16, the liquid is collected in basin 17 for removal at 18.

A fan 19 rotated in stack 20 by drive 21 draws air laterally through the tower for upward discharge via the stack. The air passes successively through openings betweeen housing side wall inlet louvers 23, the fill 16 and through drift eliminator louvers 24 as indicated by arrows 125. In FIG. 1 the eliminator louvers appear in three groups, 24a, 24b and 240.

Extending the description to FIG. 2, fill strips 25 of the invention are seen as carried by gridding 26, as for example wire mesh hangers, extending in vertical planes which are transversely spaced in directions parallel to the length extents of louvers 23. Such hangers may be suitably supported, as by lateral supports 27 carried by ties 28 on vertical posts 29. For example, the supports 27 may be notched at 30 to receive vertical Wires 31 of the hangers, the notches then being covered by battens 32 to retain the hangers in position. The top horizontal lateral wire 33 of a hanger is typically carried on the support 27.

It will be noted in FIGS. 1 and 9 that the outer side 16a of the fill tapers downwardly and inwardly, to conform generally to the path of dropping liquid, which is carried inwardly toward the bafiles 24 by the air flow; however, it is found that in conventional towers the outer fill strips at that lower portion of the tower tend to operate with undesirably reduced efficiency due to insufllcient wetting by the dropping liquid. This problem is overcome by provision of the fill now to be described.

As better seen in FIGS. 2-5, the fill strips 25 extend lengthwise within the tower with generally horizontal elongation in a transverse direction substantially normal to the lateral, oncoming air flow direction designated by arrows 125. Generally speaking, each strip has elongated edge extent at 40 that is convex in vertical lateral planes and faces laterally toward the oncoming air flow. The strip also has an upper surface 41 the major extent of which slopes downwardly and laterally to terminate at the convex edge in such relation that the surface 41 direacts splash travel of dropping liquid upwardly and laterally at 42 countercurrently into the oncoming lateral air flow, which typically is deflected upwardly by edge 40. Further, the great bulk of the water filmed on surface 41 drains toward edge 40. As a result, Whether water splashes on the strip or is filmed on the strip, it is advanced to- Ward the oncoming air flow, whereby the lower packing strips in the tower remain desirably wetted even though they are proximate the tower side.

More specifically, the strip 25 has support legs including a forward leg 43 defining the convex surface 40 and a rearward leg 44 spaced laterally from leg 43. Leg 44 has overall vertical dimension substantially greater than the overall vertical dimension of leg 43, and the strip includes webbing 45 interconnecting the legs and defining the upper surface 41 which overlies the space between the legs and slopes, preferably at an angle of between 5 and 20 degrees. Convex edge 40 typically merges with an upper plane defined by the surface 41 of sheet or webbing 45, and with a lower plane 46 defined by the lowermost portions of

legs

43 and 44, whereby air which impinges on or approaches laterally toward the convex edge extent 40 is smoothly deflected above the upper plane and below the lower plane 146, with minimum pressure drop.

Substantial stiffness is imparted to the plastic strip by extruding the forward leg 43 in the form of a web loop extending endwise of the strip, as shown, and also by extruding the rear leg 44 with a foot 46 projecting laterally. As a result, fewer hangers are needed to support the strip along its length. As regards the strip material, extruded plastics such as polypropylene or polyvinylchloride are satisfactory from the standpoints of resistance to chemicals found in cooling or process water streams, durability and long life, and resistance to algae and fungus organisms occurring in cooling towers. A typical strip may be about 72 inches in overall length, about 4 inches in overall width, about 1.4 inches in overall height as seen in FIG. 4, and have a web thickness of about 0.3 to 0.45 inch.

FIG. 3 shows the strip as containing vertical through openings 48 distributed rather uniformly over the area defined by the upper surface 41. Such openings provide for even greater water breakup and resultant splash, and for multiple sized water droplets formed upon water drainage through the openings after filming on the upper surface. The openings also restrict channeling of water falling through the fill in the tower.

As shown in FIGS. 7 and 8, the strips may be extruded with longitudinal grooves or serrations defining shoulders 50 for restraining drainage of filmed water or liquid toward convex edge 40a, thereby to divert water or liquid toward the opening 48a.

FIGS. 5a and 5b show the manner of installation of the fill strip 25 in hanger rectangular opening 26a defined by wires 51-54. The fill strip is partly rotated about a longitudinal axis and in the direction of arrow 55 in FIG. 5a to provide gaps 56 and 57 between the strip and

wires

53 and 54, thereby to allow free endwise insertion of the strip into the opening. Thereafter, the strip is reversely rotated to position seen in FIG. 5b, corresponding to FIG. 4 position. Note that the fill strip then interfits the grid wires as by seating on wire 52, with nose interfit against wire 53 and leg interfit of wire 54. Foot 46 is notched at 58 to receive wire 54 of the hanger, which is part of the tower structure. As a result, the fill strip is locked against endwise displacement, and its interfit between

wires

53 and 54 locks the fill against lateral displacement. Strut 59 of leg 44 may flex to accommodate fitting of wire 54 in notch 58.

FIG. 2 shows the fill strips 25 inserted in staggered relation within the hangers, this being one possible strip arrangement in the tower. Of course, other modes of assembly are also possible, depending upon the desired duration of water residence in the path of cooling air.

FIG. 6 illustrates a fill strip 60 of construction the same as described above in FIG. 4, excepting for elongated notches 61 in the foot 46a. Such notches are adapted to interfit tower vertical post structure, where encountered.

FIG. illustrates application of the invention to a counterfiow cooling tower 70. The latter incorporates a housing 71 wherein hot water is distributed via nozzles in horizontally extending ducts 72 to fall as droplets within the tower interior and film on packing or fill layers 73. The top of the tower is covered with decking 64 on which is mounted a fan 75 driven at 76 to displace vapor laden air from the tower via stack 77. Drift eliminator baffies extend at 78, and air inlet louvers 79 extend at the tower side as shown to pass air into the tower laterally, as indicated by arrows 80.

The fill strips 81, of construction as described above, extend in the paths of the oncoming air streams at the level of louvers 79 and are suitably supported as by hangers 82. Arrows 83 indicate the laterally directed splash travel of Water droplets falling on the inclined upper surfaces of the fill strips to counteract the effect of high velocity in tending to urge the droplets away from the louvers. If desired, such fill strips may be reversely oriented near the center of the tower to direct falling droplets toward the tower center.

We claim:

1. In a cooling tower wherein air is displaced to fiow directionally generally laterally within the tower in cooling relation with dropping particulate liquid, a fill strip extending endwise within the tower with generally horizontal elongation in a transverse direction substantially normal to the lateral air flow direction, the strip having elongated edge extent that is convex in vertical lateral planes and faces laterally toward the oncoming air flow, the strip also having an upper surface the major extent of which slopes downwardly and laterally to terminate at said edge in such relation that said surface receiving the dropping liquid directs splash travel thereof upwardly and laterally countercurrently into said oncoming lateral air flow, and the bulk of the water filmed on said surface drains toward said edge, the strip having support legs including a forward leg and a rearward leg spaced laterally from said forward leg, said rearward leg having overall vertical dimension greater than the overall vertical dimension of said forward leg, the strip including an inclined sheet interconnecting said legs and defining said sloping upper surface overlying the space between the legs.

2. The combination as defined in claim 1 wherein the strip contains vertical through openings distributed over the area defined by said upper surface.

3. In a cooling tower wherein air is displaced to flow directionally generally laterally within the tower in cooling relation with dropping particulate liquid, a fill strip extending endwise within the tower with generally horizontal elongation in a transverse direction substantially normal to the lateral air flow direction, the strip having elongated edge extent that is convex in vertical lateral planes and faces laterally toward the oncoming air flow, the strip also having an upper surface the major extent of which slopes downwardly and laterally to terminate at said edge in such relation that said surface receiving the dropping liquid directs splash travel thereof upwardly and laterally countercurrently into said oncoming lateral air flow, and the bulk of the water filmed on said surface drains toward said edge, the strip having support legs including a forward leg and a rearward leg spaced laterally from said forward leg, said rearward leg having overall vertical dimension greater than the overall vertical dimension of said forward leg, the strip including a sheet interconnecting said legs and defining said sloping upper surface overlying the space between the legs, said rearward leg including a foot projecting laterally for engagement with tower structure to resist endwise displacement of the strip.

4. In a cooling tower wherein air is displaced to flow directionally generally laterally within the tower in cooling relation with dropping particulate liquid, a fill strip extending endwise within the tower with generally horizontal elongation in a transverse direction substantially normal to the lateral air flow direction, the strip having elongated edge extent that is convex in vertical lateral planes and faces laterally toward the oncoming air flow, the strip also having an upper surface the major extent of which slopes downwardly and laterally to terminate at said edge in such relation that said surface receiving the dropping liquid directs splash travel thereof upwardly and laterally countercurrently into said oncoming lateral air flow, and the bulk of the water filmed on said surface drains toward said edge, the strip having support legs including a forward leg and a rearward leg spaced laterally from said forward leg, said rearward leg having overall vertical dimension greater than the overall vertical dimension of said forward leg, the strip including a sheet interconnecting said legs and definiu said sloping upper sur face overlying the space between the legs, said strip con sisting of a plastic extrusion.

5. In a cooling tower wherein air is displaced to flow directionally generally laterally within the tower in cooling relation with dropping particulate liquid, a fill strip extending endwise within the tower with generally horizontal elongation in a transverse direction substantially normal to the lateral air flow direction, the strip having elongated edge extent that is convex in vertical lateral planes and faces laterally toward the oncoming air flow, the strip also having an upper surface the major extent of which slopes downwardly and laterally to terminate at said edge in such relation that said surface receiving the dropping liquid directs splash travel thereof upwardly and laterally countercurrently into said oncoming lateral air flow, and the bulk of the water filmed on said surface drains toward said edge, the strip having support legs including a forward leg and a rearward leg spaced laterally from said forward leg, said rearward leg having overall vertical dimension greater than the overall vertical dimension of said forward leg, the strip including a sheet interconnecting said legs and defining said sloping upper surface overlying the space between the legs, and tower gridding extending in vertical lateral planes which are transversely spaced to define strip hangers, the gridding sized to receive the strip when inserted transversely endwise into the grid openings in partially rotated condition and to interfit the strip when the strip is reversely rotated to seat said legs on the gridding.

6. For combination in a cooling tower wherein air is displaced to fiow generally laterally within the tower in cooling relation with particulate liquid dropping therein, a fill strip adapted to extend endwise within the tower with generally horizontal elongation in a transverse directon substantially normal to the lateral air flow direction, the strip having elongated edge extent that is convex in vertical lateral planes and faces laterally toward the oncoming air flow, the strip also having an upper surface the major extent of which slopes downwardly and laterally to terminate at said edge in such relation that said surface receiving the dropping liquid directs splash travel thereof upwardly and laterally countercurrently into said oncoming lateral air flow, and the bulk of the water filmed on said surface draining toward said edge, the strip having support legs including a forward leg and a rearward leg spaced laterally from said forward leg, said rearward leg having overall vertical dimension greater than the overall vetrical dimension of said forward leg, the strip including an inclined sheet interconnecting said legs and defining said sloping upper surface overlying the space between the legs.

7. The strip as defined in claim 6 wherein said convex extent merges with an upper plane defined by said sheet and with a lower plane defined by the lowermost portions of said legs whereby air impinging laterally on said convex extent is smoothly defiected above said upper plane and below said lower plane, the strip containing vertical through openings distributed over an area defined by said upper surface.

8. For combination in a cooling tower wherein air is displaced to flow generally laterally within the tower in cooling relation with particulate liquid dropping therein, a fill strip adapted to extend endwise within the tower with generally horizontal elongation in a transverse direction substantially normal to the lateral air flow direction, the strip having elongated edge extent that is convex in vertical lateral planes and faces laterally toward the oncoming air fiow, the strip also having an upper surface the major extent of which slopes downwardly and laterally to terminate at said edge in such relation that said surface receiving the dropping liquid directs splash travel thereof upwardly and laterally countercurrently into said oncoming lateral air flow, and the bulk of the water filmed on said surface draining toward said edge, the strip including laterally spaced forward and rearward legs, and said rearward leg including a foot projecting laterally for engagement with tower structure to resist endwise displacement of the strip.

9. The strip as defined in claim 8 wherein said foot defines a notch to receive said tower structure.

10. In a cooling tower wherein air is displaced to flow directionally generally laterally within the tower in cooling relation with dropping particulate liquid, multiple fill strips each extending endwise within the tower with generally horizontal elongation in a transverse direction substantially normal to the lateral air flow direction, each strip having elongated edge extent that is convex in vertical lateral planes and faces laterally toward the oncoming air flow, each strip also having an upper surface the major extent of which slopes downwardly and laterally to terminate at said edge in such relation that said surface receiving the dropping liquid directs splash travel thereof upwardly and laterally countercurrently into said oncoming lateral air flow, and the bulk of the water filmed on said surface drains toward said edge, each strip having support legs including a forward leg and a rearward leg spaced laterally from said forward leg, said rearward leg having overall vertical dimension greater than the overall vertical dimension of said forward leg, each strip including a sheet interconnecting said legs and defining said sloping upper surface overlying the space between the legs, the tower including gridding extending in vertical lateral planes which are transversely spaced to define strip hangers, the gridding sized to receive the strips when inserted transversely endwise into the grid openings in partially rotated condition and to interfit the strip when the strips are reversely rotated to seat said legs on the gridding, the tower having a side toward which said strip convex extents are presented, said side tapering downwardly and laterally in the direction of said air flow.

11. For combination in a cooling tower wherein air is displaced to flow generally laterally within the tower in cooling relation with particulate liquid dropping therein, a fill strip adapted to extend endwise within the tower with generally horizontal elongation in a transverse direction substantially normal to the lateral air flow direction, the strip having elongated edge extent that is convex in vertical lateral planes and faces laterally toward the oncoming air flow, the strip also having an upper surface the major extent of which slopes downwardly and laterally to terminate at said edge in such relation that said surface receiving the dropping liquid directs splash travel thereof upwardly and laterally countercurrently into said oncoming lateral air flow, and the bulk of the water filmed on said surface draining toward said edge, the strip containing vertical through openings distributed over the area defined by said upper surface, and the strip including shoulders extending longitudinally at said upper surface to restrain drainage of liquid toward said convex edge.

References Cited UNITED STATES PATENTS 4/ 1933 Rasmussen. 6/1968 De Flon.

U.S. Cl. X.R. 26ll l3