COOLING TOWER WATER DISTRIBUTION SYSTEM

Abstract

A cooling tower is provided having a heat exchange section. A water collection basin located above the heat exchange section. The water collection basin has a plurality of openings that allow water to be distributed downwardly onto the heat exchange section. The water collection basin openings each have a diameter of from 0.2 inch to 0.6 inch.

Claims

1. A cooling tower comprising: an indirect heat exchange section, a water collection basin located above the indirect heat exchange section, the water collection basin having a plurality of openings that allow water to be distributed downwardly onto the indirect heat exchange section, the water collection basin openings being arranged in lateral rows, the water collection basin openings each having a diameter of from 0.2 inch to 0.6 inch, and the spacing between adjacent water collection basin openings is from 2.0 to 6.0 inches.

2. The cooling tower of claim 1 wherein adjacent water collection basin openings in each lateral row are longitudinally offset from each other.

3. The cooling tower of claim 1 wherein the indirect heat exchange section is comprised of a plurality of plate type heat exchanger, with the plate type heat exchangers arranged in lateral rows, and wherein each lateral row of water collection basin openings is aligned with a lateral row of plate type heat exchangers.

4. The cooling tower of claim 3 wherein each plate type heat exchanger has a front face side and a rear face side, and the water from the collection basin openings covers both the front face side and the rear face side of each plate type heat exchanger.

5. The cooling tower of claim 1 wherein the indirect heat exchange section is comprised of a plurality of plate type heat exchangers, with the plate type heat exchangers arranged in lateral rows, and wherein each lateral row of water collection basin openings is biased slightly from a direct alignment with a lateral row of plate type heat exchangers and each lateral row of water collection openings are in an alternating pattern relative to each lateral row.

6. The cooling tower of claim 1 wherein the indirect heat exchange section includes a plurality of plate type heat exchangers, each plate type heat exchanger having a centerline, a front side, and a rear side, the front and rear sides being on opposite sides of the centerline, each lateral row of water collection basin openings being directly above a corresponding one of the plate type heat exchangers to allow water to be distributed downwardly onto the corresponding plate type heat exchanger, wherein each lateral row of water collection basin openings includes a first plurality of openings overlapping the centerline of the corresponding plate type heat exchanger and longitudinally biased toward the front side of the corresponding plate type heat exchanger, wherein each lateral row of water collection basin openings includes a second plurality of openings overlapping the centerline of the corresponding plate type heat exchanger and longitudinally biased toward the rear side of the corresponding plate type heat exchanger, and wherein each lateral row includes an alternating arrangement of the first plurality of openings and the second plurality of openings to evenly distribute the water across the front side and the rear side of the corresponding plate type heat exchanger.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In the drawings,

[0015] FIG. 1 is a perspective view of a direct heat exchange apparatus in accordance with the present invention;

[0016] FIG. 1A is a perspective view of an indirect heat exchange apparatus in accordance with the present invention;

[0017] FIG. 2 is a side view of a direct heat exchange apparatus in accordance with the present invention;

[0018] FIG. 2A is a side view of a indirect heat exchange apparatus in accordance with the present invention;

[0019] FIG. 3 is a top view of a part of upper gravity drain water collection basin in accordance with the present invention;

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] Referring now to FIG. 1 of the drawings, an embodiment of the present invention is shown in a cooling tower direct heat exchange apparatus 10. Direct heat exchange apparatus is comprised of casing 11, direct heat exchange fill pack 12, upper gravity drain water basin 13, lower water sump 14, water pre-distribution box 15, fan assembly 16, upper gravity drain basin covers 17, pre-distribution box pipe inlet 18, air inlet 19 and air outlet 20. It should be noted that the direct heat exchange fill pack may also be an indirect heat exchanger and is not a limitation of the invention. Cooling tower direct fill heat exchange apparatus 10 is generally enclosed in casing 11, which can be made of thin sheet of metal or fiber reinforced plastic. Casing 11 provides a housing for fill pack 12, upper gravity drain basin 13, fan assembly 16, and lower basin 14. Upper gravity drain basin 13 is located generally directly above fill pack 12 and fill pack 12 is located above lower sump 14. Upper gravity drain basin 13 is generally rectangular in shape having a width, length, and height. The width and length of upper gravity drain basin 13 is generally the same size as width and length of fill pack 12 and the height is usually four to 12 inches. Upper gravity drain water collection basin 13 may be covered with a plurality of upper gravity drain water collection basin covers 17 to prevent debris from entering. Inside upper gravity drain water collection basin 13 is pre-distribution box 15, which sits generally in the middle of upper basin 13, but pre-distribution box 15 could be placed anywhere of upper basin 13. Water enters upper gravity drain water collection basin 13 through pre-distribution box 15 which helps to spread water more evenly throughout upper gravity drain water collection basin 13. Fan assembly 16 draws in air through air inlet 19 and generally in crossflow through fill pack 12 and ejects air out of direct heat exchange apparatus 10 through air outlet 20. The direction of airflow may be generally upwards, generally downwards, generally across or generally concurrent with the water flow through the direct heat exchanger. Cooling tower direct heat exchange apparatus 10 may have one or more water inlets 18, one or more fill packs 12, one or more fan assembly 16 and one or more air outlets 20.

[0021] Referring now to FIG. 1A of the drawings, an embodiment of the present invention is shown in an indirect heat exchange apparatus 21. Indirect heat exchange apparatus 22 is comprised of casing 11, indirect heat exchange section 22, upper gravity drain water collection basin 13, lower water sump 14, water pre-distribution box 15, fan assembly 16, upper gravity drain water collection basin covers 17, pre-distribution box pipe inlet 18, air inlet 19 and air outlet 20. It should be noted that the indirect heat exchange section may be of any type including tubes, plates, finned and is not a limitation of the invention. It could also be a combination direct/indirect heat exchange section. Indirect heat exchange apparatus 21 is generally enclosed in casing 11, which can be made of thin sheet of metal or fiber reinforced plastic. Casing 11 provides a housing for indirect heat exchange section 22, upper gravity drain basin 13, fan assembly 16, and lower basin 14. Upper gravity drain water collection basin 13 is located generally directly above indirect heat exchange section 22 which is located above lower sump 14. Upper gravity drain water collection basin 13 is generally rectangular in shape having a width, length, and height. The width and length of upper gravity drain water collection basin 13 is generally the same size as width and length of indirect heat exchange section 22 and the height is usually four to 12 inches. Upper gravity drain water collection basin 13 may be covered with a plurality of upper gravity drain water collection basin covers 17 to prevent debris from entering. Inside upper gravity drain water collection basin 13 is pre-distribution box 15, which sits generally in the middle of upper water collection basin 13, but pre-distribution box 15 could be placed anywhere of upper water collection basin 13. Water enters upper gravity drain water collection basin 13 through pre-distribution box 15 and spreads throughout upper gravity drain water collection basin 13. Fan assembly 16 draws in air through air inlet 19 and generally in crossflow through indirect heat exchange section 22 and ejects air out of indirect heat exchange apparatus 21 through air outlet 20. The direction of airflow may be generally upwards, generally downwards, generally across or generally concurrent with the water flow through the indirect heat-exchanger. Indirect heat exchange section 22 has internal process fluid inlet pipe 23 and outlet pipe 24. The connections can be reversed if desired. The interior process fluid is cooled indirectly from the evaporative water that flows by gravity generally downward across from the upper gravity drain water collection basin 13. Indirect heat exchange apparatus 21 may have one or more water inlets 18, one or more indirect heat exchange sections 22, one or more fan assembly 16 and one or more air outlets 20.

[0022] Referring now to FIG. 2 of the drawings, an embodiment of the present invention is shown in a side view generally as direct heat exchange apparatus 30. Heat exchange apparatus 30 is comprised of casing 31, direct heat exchange fill pack 32, upper gravity drain water collection basin 33, lower sump 34, pre-distribution box 35, fan assembly 36, pre-distribution box pipe 37, air inlet 38 and plenum air outlet 39.

[0023] During operation, water to be heated or cooled enters direct heat exchange apparatus 30 through pre-distribution pipe 37, spreads across upper gravity feed water collection basin 33 and accumulates a head of water 40 inside upper gravity drain water collection basin 33. Upper gravity drain water collection basin 33 is generally an open top rectangular box comprised of sides 45 and upper gravity drain basin bottom plate 44, which has plurality of spray holes that are generally spaced throughout. Accumulated water head 40 inside upper gravity feed water collection basin 33 travels downward through the plurality of spray holes in basin bottom plate 44 and forms a well distributed flow 41 and falls on the top of direct heat exchange fill pack 32.

[0024] Direct heat exchange fill pack 32 is made of plurality of thin plastic fill sheet 43 that are either hung using a hanger system or bundled together in a block form and stacked underneath upper gravity drain water basin 33 and above lower sump 34. Direct heat exchange fill pack 32 has a plurality of air gaps so that both spray water and air can easily flow through. When spray water flows through direct heat exchange fill pack 32 and reaches lower sump 34, water accumulates in sump 34 to form a shallow pool 42 before exiting heat exchange apparatus 30. Air enters cooling tower direct heat exchange apparatus 30 through air inlet 38, travels through the plurality of gaps within fill pack 32, makes generally an upward turn inside plenum outlet 39 and exits cooling tower direct heat exchange apparatus 30 through fan assembly 36. As air travels though fill pack 32, heat exchange takes place between air and spray water on fill sheets 43.

[0025] Referring now to FIG. 2A of the drawings, another embodiment of the present invention is shown in a side view generally as indirect heat exchange apparatus 30A. Indirect heat exchange apparatus 30A is comprised of casing 31, indirect heat exchange section 32A, indirect heat exchange inlet and outlet connections 46 and 47 respectively, upper gravity drain water collection basin 33, lower sump 34, pre-distribution box 35, fan assembly 36, pre-distribution box pipe 37, air inlet 38 and plenum air outlet 39.

[0026] During operation, process fluid to be heated, cooled, evaporated or condensed enters indirect heat exchange apparatus 30A through inlet connection 46 and exits from outlet connection 47. Evaporative fluid, usually water, enters pre-distribution pipe 37, spreads across upper gravity water collection basin 33 and accumulates a head of water 40 inside upper gravity drain water collection basin 33. Upper gravity drain water collection basin 33 is generally an open top rectangular box comprised of sides 45 and upper gravity drain basin bottom plate 44, which has plurality of spray holes that are generally spaced throughout. Accumulated water head 40 inside upper gravity water collection basin 33 travels downward through the plurality of spray holes in basin bottom plate 44 and forms a well distributed flow 41 and falls on the top of indirect heat exchange section 32A.

[0027] Indirect heat exchange section 32A may be made of plurality of plates 43A, tubes, or finned type heat exchangers and is not a limitation of the invention. Indirect heat exchanger plates 43A may be either hung using a hanger system or bundled together in a block form and stacked underneath upper gravity drain water basin 33 and above lower sump 34. Indirect heat exchange section 32A has a plurality of air gaps so that both spray water 41 and air can easily flow through. When spray water flows through indirect heat exchange section 32A and reaches lower sump 34, water accumulates in sump 34 to form a shallow pool 42 before exiting indirect heat exchange apparatus 30A.

[0028] Air enters indirect heat exchange apparatus 30A through air inlet 38, travels through the plurality of gaps within indirect heat exchange sections 43A, makes generally an upward turn inside plenum outlet 39 and exits indirect heat exchange apparatus 30A through fan assembly 36. As air travels through indirect heat exchanger 32A, indirect heat exchange takes place between the spray water and the interior process fluid while direct heat transfer takes place between the spray evaporative spray water and the air flowing.

[0029] Referring now to FIG. 3 of the drawings, an embodiment of the present invention 48 is shown in a plan view. Upper gravity drain water collection basin bottom plate 50 has a plurality of spray water holes 51 that are strategically aligned over top of a plurality of direct heat exchange fill sheets 52. Each fill sheet 52 has a front face side 55 and a rear face side 56. Each fill sheet 52 is separated by a nominal distance determined by fill spacer 61 so that there is a gap between fill sheets 52. Fill sheet 52 has plurality of surface pattern humps and valleys that may weave in and out of fill sheet nominal plane 53 and that may not be vertically aligned when viewed downward from gravity drain water basin bottom plate 50. The geometry and positioning of these humps and valleys gives fill sheet 52 a body thickness when viewed downward from gravity drain water basin bottom plate 50. Each fill sheet 52 is typically made of thin sheets of plastic or PVC but can be made of any material desired.

[0030] Spray holes 51 are strategically aligned above the plurality of fill sheets 52 so that when spray water drops down through plurality of holes 51, the water falls onto fill sheets 52. The spray water streams purposely land on both face side 55 and obverse face side 56 of fill sheet 52. Spray holes 51 are separated by gap 70 and 72 in the width and separated by gap 71 between the face and obverse face sides. Generally gap 72 and 70 are equal such that the number of holes are reduced. Gaps 70 and 72 are at a distance apart such that when spray water hits fill sheet 52, the spray water spreads out such that fill sheet 52 is uniformly and evenly wetted. The combination of patterns, humps and valleys in fill sheets 52 spreads the single stream of water over a surface area as a thin film of water so that more efficient air to water heat exchange could take place. Air travels in the direction from air inlet edge 59 toward air outlet edge 60, and fill sheet 52 is aligned so that it doesn't block the air travel.

[0031] Spacing 70 and 72 must be optimized to allow for uniform spreading on the face 55 and obverse face sides of fill sheet 52 while simultaneously reducing the number of holes required such that the diameter of the holes are maximized. The hole 51 diameter and the hole spacing 70 and 72 can be found by iteratively solving the following equation:

Flow rate=number of fill sheets.Math.hole spacing.Math.hole coefficient, where

hole spacing=fill sheet air travel lengthnumber of holes per fill sheet

hole coefficient=Cd.Math.A.Math.(2gh).sup.2, where

[0032] Cd is drag coefficient of hole in a plate,

[0033] A is area of hole

[0034] g is gravity constant, and

[0035] h is water column height in the gravity drain water basin.

[0036] The preferred hole 51 diameter is 0.4 inches0.2 inches while the preferred gap 70 and 72 is 4 inches2 inches. The balance between the selected hole diameter and selected spacing 70 and 72 vary depending on the required overall flow rate. Once the overall target design flow rate is known, holes gaps 70 and 72 and hole 51 diameter are iterated to arrive at a solution which guarantees even and uniform water coverage while minimizing the number of spray holes so that the spray performance can be maximized. This balance of finding optimum gaps 70 and 72 with hole 51 diameter guarantees maximum thermal heat transfer while reducing the possibility for hole clogging. Hole gap 71 is selectively set to insure both the face 55 and 245 obverse face side of fill sheet 52 are properly covered. This gap is dependent on the gap between the fill sheets.

[0037] A set of face spray hole 57 and obverse face spray hole 58 that belongs to a same fill sheet 52 may not necessarily be in a straight line in the air travel direction. Face spray holes 57 are slightly biased toward face 55 direction from fill sheet nominal plane 53 and obverse face spray holes 58 are slightly biased toward obverse face 56 from fill sheet nominal plane 53 of corresponding fill sheet 52. The biasing of the holes exists so that when there is slight variation of location of fill sheet 52 in a parallel direction of air inlet edge 59, both face 55 and obverse face 56 are properly wetted by spray holes 51.