US2512271A - Water-cooling tower - Google Patents

Description

June 20, 1950 N. P. GREEN WATER-COOLING TOWER 2. Sheots-Shqet 1 Filed Dec. 26, 1947 June 20, 1950 I N. P. GREEN 2,512,271

I WATER-COOLING TOWER Filed Dec 26, 1947 2 Sheets-Sheet 2 7 FIGS.

Patented June 20, 1950 UNITED STATES PATENT OFFICE 2 Claims.

This invention relates to water-cooling towers, and more specifically to heat-exchange apparatus for receiving water from industrial equipment and atmospherically cooling the water for subsequent return to the equipment.

Among the several objects of the invention may be noted the provision of a water-cooling tower in which increased heat-exchangecapacity is obtained; the provision of apparatusof the class describedin which saidincre'ased heat-exchange capacity is obtained with a reduction in both water-pump and air-fan power; the provision of apparatus of this class which requires only a single water-pumping operation for "any eiiiciency; and. the provision of apparatus of this class which is simple in operation and flexible and economical to build. Other objects will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the elements. and combinations of elements, features of constructionand arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which one of various possible embodiments of theinvention is illustrated,

Fig. 11 is a cross section taken through a typical form of apparatus: embodying .theinvention, parts being broken away and, shown in section;

.Fig. 2 is a diagrammatic top plan view on a reduced scale, showing a typical assembly of units;

Fig. 3 is a horizontal. section taken: on line 3-3- of Fig. 1;

Fig. 4 is a horizontal section taken on line 4-4 of Fig. 1; and,

Fig. 5 is a vertical section taken on line 55 of Fig. 4.

Similar reference characters indicate corresponding parts throughout the several'views' of the drawings.

I have discovered that the efliciency and the heat-exchange capacity of a cooling tower can be increased for a givenexpenditure of energy'in auxiliaries such as water pumps, fansand the like by:

(1) Subjectinga gravity'fiow of water to serial passage through cooling compartments of cross sections which are comparatively small relative to the air-carrying crosssection of the tower;

(2) Causing thecurrent of cooling air to be completely divided so as simultaneously to have parts of it come into separate heat-exchange relations with the serially flowing; waterin the Itspe'ctivecompartments; and, V

(3) Enforcing an exclusive and complete coun terflow between'each divided mass of air andthe water in a given compartment.

The cross section of a tower is primarily determined by the air flow which must be accommodated. Heretofore the procedure has been generally to break up a desired mass of water throughout the cross section of a tower and to treat this broken mass with the entire flow of air either by cross flow, counterflow, or both. This has resulted in an excessive amount of interspacebetween the drops of water through which air passed without coming into sufliciently close proximity to the water for maximum heat exchange.

Counterflow action between the air and the Water is the best for obtaining maximum heat transfer during a given contact between air and water. By means of the present invention, I-'arrange a tower so that its cross section accommodates the entire air flow but the cross section over which the broken water is distributed is less than that of the entire tower, and in this smaller cross section I' obtain true counterfiow between all of the water and a definite part of air. This, with resulting increase in heat exchange, is ac complished with a simple construction requiring a minimum of pumping energy and mechanical operations.

Referring now more particularly to the drawings, numerals I (Fig. 1) indicate individual towers or stacks which maybe placed in various arrangements, one of which is shown in Fig. 2. In this arrangement the towers I are abutted back to back to form pairs which are then abutted' side to side to form a line, as indicated. Other multiple arrangements may be made and it is to be understood that'the essentials of the invention can be carried out in any one tower and that the particular multiple arrangement shown is only exemplary. However. in the case of the said abutted arrangement shown, the necessity for dividing walls between abutting towers is eliminated. For example, in Fig. I no walls are needed where the towers abut. but such could be employed if desired.

Each tower l comprises a bottom sump 3 above which is a suitable superstructure having an upper outlet 5 in which is a fan driven from a motor 9 through a transmission ll. Below each fan is a drift eliminator section 2, which is in the nature of bathing to reduce the escape of airentrained moisture.

At" an elevated position is located a water-sup ply container [3. One container may supply several towers. This. container [3 includes outlets;

l5 communicating withlateral channels II. Adjustable control plates are shown at 19, these being operable from control apparatus 21. Water is supplied to the box from the hot water supply through a riser pipe 23.

The channels I! lead outward from the container 13 to points above groups of cross channels 25, located near the top and sides of the towers (Fig. 3). Holes [8 in channels I! allow water to gravitate to the cross channels 25 from which the water subsequently flows over serrated edges 20. Under the channels 25 are built angle-shaped heat-exchange boxes 21. Each box includes an enclosing vertical inner imperforate wall 29 and an enclosing horizontal bottom-rimmed imperforate wall forming a collecting basin 3L In the bottom of the basin 3| is a trough 33 which extends inward and over another set of channels 25 associated with a second and lower box 31. Openings [8 in trough 33 allow water'to escape down into the cross channels 25 from which it escapes over serrated edges 20. This box 31 also has an inner wall 29 and a collecting basin 3| with a trough 33 leading out to holes i8 over a third group of channels 25 having serrated overflow edges 20 and which are above what would be a third box if a back wall were used for this tower. This will be considered to be a third box 41 for reasons which will appear. It will be understood that the above described descending stepped construction may be carried out in as many steps as may be desired, the three-stepped arrangement being merely typical.

Under each set of cross channels 25 is a socalled filling section 39. As known in this art, a

filling section is one constituted by bafiles over which the water flows and drips and through which flow of cooling air is admitted. Such baifies may be constructed of wood, metal or the like, and are often composed of a cries-cross arrangement of strips of rectangular cross section, preferably with the planes of the sections vertically arranged so as to present a large area of wetted surface With minimum obstruction to air flow. Any water flowing through such filling or baflling is broken up and in addition to running over the baflles, drips or rains down between them. The filling sections are diagrammed b crosses over the areas occupied thereby and will not further be detailed in view of common knowledge regarding their make-up. The filling sections extend only partially downward in the respective boxes 21, 31 and 41, leaving open areas 35 into which air may be introduced through openings 4|, provided at the lower left of each space 35. In the case of the lowermost equivalent box 41, the opening M of course extends down to the level W of the liquid carried in the sump 3. The depth of each stack l perpendicular to the plane of the paper in Fig. 1 is optional and as suggested in Figs. 3, 4 and 5, for increased depths the unit construction shown may be repeated.

The front of each tower is covered by louver boards 43 which admit a stream of air constituting all of the air flow employed in each tower. This stream is separated into three paths A, B and C, which respectively supply the boxes 21, 3'! and 51. lower streams C ofiset one another centrally and act as mutual guides in a vertical plane such that no central box wall corresponding to walls 29 of boxes 2'! and 31 is needed for the equivalent box 41. Such a wall could be employed if desired for box 41. In the case of abutted towers one back wall for box 41 would serve both bottom boxes 41.

Since the towers are abutted, the

It should :be understood that the use of the fans I is optional and that under certain circumstances natural convection may be relied upon for enforcing air flow through the tower. The fans, however, substantially increase capacity.

Operation is as follows, assuming that the fans I are operating and that a suitable standard pump (not shown) in the line 23 pumps hot water to the container I3. Water flows from the container I 3 through the troughs 11, through openings l8 to the upper channels 25, where it is distributed laterally and overflows into the filling 39 of each upper box 21. The filling baffles break the water up so that it drips or rains downward from the filling. Considering for the moment one tower only, water is collected in the basin 3| and enters the trough 33 below box 21. It then flows through openings I8 into the channels 25 of the next box 31 and overfiowsinto its filling 39 and rains down onto the basin 3| of this box 31 from whence it enters its troughs 33, to be delivered through another set of openings Hi to channels 25 of the lowermost box 41. It overflows these channels into the filling 39 of this lowermost box and then rains down into the supply at the sump 3.

All of the atmospheric air used is drawn in through the louvers 43 and passes out of the outlet 5. This air is divided into the three distinct streams A, B and C, as determined by the forms of the boxes 21, 3! and 41. These streams enter the spaces 35 and are deflected upward into complete and isolated counterflow movement relative to the downwardly progressing water. Air stream A contacts the hottest water; air stream B contacts cooler water; and air stream C contacts the coolest water. It is clear from the above that the number of steps in the heat-transfer operation could be increased by increasing the number of boxes and consequent air streams. Since the temperature drop between the water and the air stream A is th highest, the most efficient heat transfer is obtained in box 21. This efiiciency decreases in successive boxes in descending order, but the average efiiciency of all boxes in a series is higher than if all the water were placed in heat-exchange relation with all of the air operating in a single stream. That is to say, the enthalpy (or total heat) of the air is by this means more efliciently increased than heretofore. It will be noted that all of the water which flows through the successive boxes '21, 31 and 41 is caused to rain through a cross section which is roughly times the total cross section of the tower where N is the number of boxes employed. In this case the fraction will be approximately one-third. Thus the air which travels through this reduced cross section is thrown into more intimate relation to the water droplets without so much air getting through a given process in a box at low heat-exchange efficiency. This eificiency is enhanced by the enforcement of true counterfiow conditions between the water and the air in each separate heattransfer process in each box. It is true that the temperature difierence between the water and air goes down with each passage of the water through a successive box and thi tends to reduce theamp-ii enthalpy increase of the air passing through each successive box, but the losses in this respect are more than made up for by the advantages stated, so that the total enthalpy increase of the total air flowing from each outlet 5 is higher than heretofore. The construction above described can b carried out in various forms, but the essential features are that:

(a) The hot water flows serially and by gravity through the respective filler sections of the boxes 21, 31 and 41, the successive cooling functions 'being serial in time, the cross sections of the respective filler sections being smaller than that of a given stack by the ratio of (b) The air masses in the streams A, B, C function simultaneously but separately upon the stream of water flowing serially through the boxes 21, 31 and 41; and,

(0) Each isolated mass or stream of air in its respective compartment constituted by boxes 21, 31 and 41, flows upward against the descending broken stream of water in true counterfiow relationship.

In the above expressions, where the factor N is used, it will be understood that it is assumed that all boxes are of the same sizes and if they are not, then the expression for each box needs to be modified in a manner which is obvious.

It should be noted that the boxes 21, 31 and 41 form distinctly enclosed compartments carrying filling means to which liquid is introduced from above the compartment and below which the air is guided for upward counterfiow in respect to the descending water, and that the respective stream of air flowing through the compartment is definitely separated from other air streams and guided by the walls of the compartment, the lower wall of the compartment forming a catch basin from which water progresses to the next compartment without letting air through the compartment from any other air stream. It will also be noted that each filling means is completely surrounded by a wall which Will enforce vertical counterfiow in the respective compartment so that the heat-exchange functions in the respective compartment take place in an isolated region. Since the flow cross section of each compartment is less than the flow cross section of the entire tower or stack, said isolated heat-exchange process in the respective compartment takes place under optimum mechanical conditions for optimum heat-exchange functions. 7 By means of the structure described, the entire cross section of the stack is available to all of the air flowing into the louvers 43, but only a fraction of the cross section of the stack is available to counterfiow between water and air in any given compartment.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. A cooling tower comprising a vertical stack having a common vertical side air inlet and a common horizontal upper air outlet, a series of heat-exchange boxes each consisting of imperforate L-shaped baffle elements arranged in diagonal stepped relation from an upper part of the stack adjacent the air inlet and air outlet to a lower part of the stack distant from the air inlet and air outlet, peripherally enclosed filling baiiles respectively horizontally arranged crosswise in the upper portion of each box, the bottom of each box forming a water-collecting basin spaced from the respective filling bafile so as to provide an individual box inlet directed toward said vertical air inlet, each successive downward box inlet being farther from the common air inlet, means for introducing all the water to be cooled into the filling bailles of the uppermost box for progress to its basin, means for transferring all of the water from said basin to the filling bafiies of successively lower boxes, whereby all the water passes serially through the filling baflles and basins of all stepped boxes and the air entering said vertical inlet is divided between said respective box inlets, each divided portion of air being deflected by a respective L-shaped baffle element into respective upward counterfiow relationship with all of the water which passes through the respective box.

2. A cooling tower comprising a vertical stack having air inlet means and a common horizontal upper air outlet, a group of heat-exchange boxes arranged in diagonal stepped non-overlapping relation from an upper part of the stack adjacent the air outlet to a lower part of the stack more distant from said air outlet, peripherally enclosed filling baffles respectively arranged crosswise in the upper portion of each box, the bottom of any box which is higher than another forming a water-cooling basin below its respective filling, means for introducing substantially all the water to be cooled into the filling baffles of the uppermost box, means for transferring all of the water from any higher basin to the filling baifies of a successively lower box, whereby all the water passes serially through the stepped boxes, and baflle means constituted by parts of the boxes adapted to divide the air flow from the air inlet means into exclusive individual counterfiow relationships with all the Water passing serially through the respective boxes.

NATHANIEL P. GREEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,054,809 Fleisher Sept. 22, 1936 FOREIGN PATENTS Number Country Date 10,448 Great Britain Oct. 22, 1907 550,268 France Dec, 8, 1922 718,790 France Nov. 5, 1931

Images