US1844313A - Cooling tower - Google Patents

Description

Feb. 9, 1932. D. K. DEAN ET AL. 1,844,313

COOLING TOWER Filed March 19, 1928 INVENTOR Ila/v KIA-341v s Patented Feb. 9, 1932 UNITED STATES PATENT OFFICE DION KANOUSE DEAN, OF RAHWAY, AN'D ERNEST LINWOOD CAHOON, OF WESTFIELD, NEW JERSEY, ASSIGNORS T0 FOSTER WHEELER CORPORATION, OF NEW YORK, N. Y.,

A CORPORATION OF NEW YORK COOLING TOWER Application filed March 19, 1928. Serial No. 262,889.

Our present invention relates to cooling towers of the kind in which one or more fans are employedto cause air to flow through a tower structure in which the air comes into contact with water exposed in suitably divided form to such contact, in order that the water may thereby be cooled, and the general object of our invention is to provide improved fan means for moving air through such a cooling tower.

In the operation of a cooling tower, the volume of air to be handled is relatively large, and the pressure head developed by the fan or fans employed may be, and in practice is, relatively small. In consequence.

it is practically essential that the diameter of a cooling tower fan should be relatively large. Heretofore, it has been the usual practice to provide cooling towers with fans of the disc propeller type.

In the operation of a fan of the ordinary disc propeller type, there is created a socalled back-draft or reverse air flow across the central portion of the area swept by the fan blades or arms. Such back-draft is peculiarly objectionable in the case of cooling towers employed, as are most such towers, in latitudes in which temperatures low enough to freeze water are experienced from time to time, because the back-draft carries water drops or spray out of the tower, and in freezing weather this water collects in the form of ice on the fan blades. Such ice is a source of injury not only to the fan itself, but also to the tower structure, because of the .size of the ice pieces breaking loose from the fan blades from time to time, and the velocity with which such ice pieces are discharged.

An important specific object of the present invention is to provide a cooling tower fan we employ a fan resembling an ordinary.

aeroplane propeller, in that the pitch of the 'fanblades is relatively low, varying gradually throughout the blade length, the point of maximum pitch being at or adjacent to the fan hub, and in that the blade width tapers gradually from an intermediate point towards the blade ends, the point. of maximum width being substantially spaced from the outer end or tip of the blade. The individual blades are preferably from three to six feet in length and are capable of and adapted for rotation at relatively high speeds. Fans having blades constructed and arranged in this general manner are hereinafter generically referred to as fans of the aeroplane propeller type as distinguished fromthe' low speed fans formerly in use which had.

of the higher velocity air discharged from the portions of the fan blades nearer the tip. While in a fan of the disc type, the air is moved through a centrifugal path of flow from the blade tips, substantially all of the air in the hollow cone being moved by direct con-tact with the blades and only a relatively small portion of the flow being induced. This form of air stream tends to create a partial vacuum around the hub of the fan and the air movement created thereby causes a substantial back draft across the central part of the fan. For example, the pitch of each fan blade may progressively decrease from the hub of the'fan to the outer end or tip of the blade. With a fan so constructed, it is possible to maintain a velocity of air flow across the area swept by the fan blades, which is approximately uniform at all distances from the axis of the fan.

In an alternative construction, the fan blade pitch may increase with the distance from the fan axis to a maximum obtained at a distance from the fan axis equal to about two-thirds of the fan radius, after which the blade pitch diminishes from the point of maximum pitch as the distance from the fan axis increases. With the construction last described, the axial air velocity of anouter shell portion of the air moved across the area characterize our mvention arepomted out v..vantage over a propeller type,

swept by the blades, is greater than the axial air velocity of the inner portion of the movmg air stream, but the more rapidly'moving aeroplane propeller type is a relatively high speed fan. The difference between the characteristic speeds of the two types of fans is practically important, because a fan of the aeroplane propeller type may advantageously be connected directly to the shaft of an electric motor or other relatively high speed motor, whereas it is practically essential in driving a cooling tower fan of the disc propeller type by an electric motor or other relatively high speed motor, to employ some I form of speed reducing gear connection between the motor shaft and the fan shaft. Such connection is objectionable, because it materially increases the cost of the unit and involves some power wastage and requires attention from an operator.

A third fan arrangement suitable for cooling tower use which we have devised to eliminate objectionable results of back-draft, comprises a main fan, which may be of the disc and a smaller auxiliary fan co-axial with the main fan and operating to create an air flow in the proper direction across the area swept by the inner portions of the arms or blades of the main fan.

The various features of novelty which with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, and the advantages possessed by it, reference should be had to the accompanying drawings and descriptive matter in which we have illustrated and described preferred embodiments of the invention.

Of the drawings Fig. 1 is an elevation with parts broken away and in section of a portion of a cooling tower equipped with a preferred form of air moving means;

7 Fig. 1;

Fig. 2 is an elevation of the fan shown in Fig. 3 includes fan blade sections taken along the lines 1, 2, 3, 4 and 5-, respectively, of Fig. 2;

Fig. mcludes fan blade sections taken construction shown in Figs. 1, 2 and 3, A represents a cooling tower of conventional design comprising a housing or tower structureopen to the atmosphere at its upper end, and provided with a lateral air inlet opening A adjacent its lower end. The inlet A opens directly into an air space A above which are arranged spaced apart bafiles B over which water, supplied to the upper portion of the tower to be cooled in the latter, flows downward in finely divided and broken streams or films. D represents a fan mounted on a shaft C and disposed in the inlet A and serving to force atmospheric air through the inlet A into the air space A Insofar as above described, the cooling tower and fan arrangement is of-well known type and embodies nothing now novel with us.

In the construction shown in Figs. 1, 2 and 3. the fan D, with which the present invention is concerned, resembles an ordinary aero-L plane propeller 1n that 1t comprises a relatively smaller number of blades, usually two 'or four, than an ordinary disc propeller fan.

'of course in the portion of the inlet occupied by the hub of the fan. With the fan construction shown in Figs. 2 and 3 this uniformity of air flow is obtained by shaping the fan blades so that the pitch of each blade decreases in a proper manner, from the fan hub to the blade tips. This is made clearly apparent in Fig. 3, wherein the different sections d, (1 (i d and d of'the blade D are taken along the lines 1, 2, 3, 4 and 5, respectively, of Fig. 2.

In Fig. 1, the shaft of the fan D is shown as an extension of the shaft of the driving motor F, the shaft C being journalled in bearings E and carried by a suitable support E and with the fan D overhanging its supporting bearings.

the blade approximately two-thirds of the total distance from the blade axis to the blade tip, and decreasing the blade pitch as the distances from the point of maximum pitch ininsofar as the distances from the fan axis at which the sections are taken is concerned,with the sections (Z, (Z d (1 and d of Fig. 3 In Fig. 4, the blade pitch of the sections at. and (Z is less than that of the section (1, and is greater than that of the sections (Z and cl, respectively.

In the construction illustrated in Fig. 5, a fan shaft C, which may be driven in any suitable manner as through speed reducing gear (not shown) from a high speed driving motor, carries a main fan DA and supports an auxiliary fan DE. The main fan DA may be of the propeller disc type heretofore invention now known to us,

commonly employed as a cooling tower fan. The back-draft tendency of the fan DA is neutralized in the construction shown in Fig. 5, by the auxiliary fan which need have a diameter but a comparatively small fraction of the diameter of the fan DA and is mounted sufficiently close to the latter so that the fan DB will drive air across the central portion of the area swept by the arms of the fan DA. In general, the speed of the fan DB should be greater than that of the fan DA,

but we have not thought it necessary to illustrate a driving connection to the quill DB carrying the fan DB.

With any of the arrangements described the cooling tower may be provided with a plurality of fans when necessary, and these fans may be arranged in pairs mounted on the same shaft and located in tower inlets at opposite sides of the tower structure. l/Ve have not thought it necessary to illustrate this as such double fan arrangements are well known and in common use. In general, however, it is desirable with the high speed aero plane type of fan illustrated in Fig. 1, to proide an individual driving motor for each Notwithstanding the specific difference in construction and operation noted above, all of the fan arrangements illustrated by Way of ezgample in the accompanying drawings are characterized by the fact that they are all effective to move air in the proper direction across approximately the entire area swept by the fan blades or arms, thereby avoiding the objectionable bac-k-draft characteristic of the operation of cooling tower fans heretofore'in general use, and contributing to a desirable elimination of noise.

While in accordance with the provisions of the statutes, we have illustrated and described the best form of embodiment of our it will be apparent to those skilled in the art that changes may be made in the form of the" apparatus disclosed without departing from the spirit of our invention as set forth in the appended claims and that in some cases certain features of our invention may be used to advantage without a corresponding use of other features.

Having now described our invention, what.

we desire to secure by Letters Patent, is:

1. Water cooling apparatus comprising in I I combination, a vertically arranged cooling tower structure open to atmosphere at its upper end and having means for supplying water to be cooled in large quantities to the upper portion of said tower structure, 'bafile means arranged in said upper portion receiving the water suppliedto said tower structure and directing it downwardly therethrough in finely divided streams, a substantially unobstructed air chamber of substantial volume arranged in the lower portion of said tower structure and receiving the downflowing water substantially throughout the horizontal are-a ofsaid chamber, a cooling air inlet of substantial size arranged in one side of said air chamber, and fan means passing a substantially unbroken solid stream of cooling air at a relatively high linear velocity horizontally across said air chamber in intimate contact with the descending water in all'portions thereof, whereby a substantial water cooling ell'ect is attained in said air chamber.

2. Water cooling apparatus comprising in combination a vertically arranged cooling tower structure open to atmosphere at its upper end and having means for supplying Water to be cooled in large quantities to the upper portion of said tower structure, baffle means arranged in said upper portion receiving the water supplied to said tower structure and directing it downwardly therethrough in finely divided streams, an air chamberof substantial volume arranged in the lower portion of said tower structure and receiving the downflowing Water substantially throughout the horizontal area of said chamber, air inlet of substantial size arranged in one side of said air chamber, and means passing a substantially unbroken solid stream of cooling air at a relatively high linear velocity horizontally across said air chamber in intimate contact with the descending water in all,

portions thereof including an aeroplane propeller type fan extending substantially across and arranged to discharge horizontally through said air'inlet opening into said air chamber, whereby a substaiitial water cooling efl'ect is attained in said air chamber.

3. Water cooling apparatus comprising in combination a vertically arranged cooling tower structure open to atmosphere at its upper end and having means for supplying water to be cooled in large quantities to the upper portion of said tower structure, baflle means arranged in said upper portiontreceiving the. water supplied to said tower structure and directing it downwardly therethrough in a. cooling finely divided streams, a substantially unobstructed airchamber of substantial volume arranged in the lower portion of said tower structure and receiving the downflowing 5 water substantially throughout the horizontal area of said chamber, a cooling air inlet of substantial size arranged in one side of said air chamber, and forced draft fan means positioned adjacentsaid air inlet opening and arranged to efiectra forward flow of air at a relatively high linear velocity through substantially the entire area of said inlet opening and substantially horizontally across said chamber in intimate contact throughout its passage with the descending water therein, whereby a substantial water cooling efl'ect is attained in said air chamber.

4. Water cooling apparatus comprising in combination a vertically arranged cooling tower structure open to atmosphere at its upper end and having means for supplying water to be cooled in large q uantities to the upper portion of said tower structure, baffle means arranged in said upper portion receiving the water supplied to said tower structure and directing it downwardly therethrough in finely divided streams, an air chamber of substantial volume arranged in the lower portion of said tower structure and receiving the downflowing water substantially throughout the horizontal area of said chamber, a cooling air inlet of substantial size arranged in one side of said air chamber, a high speed electric motor mounted adjacent said inlet opening and having a drive shaft extending towards said opening, bearing means for said shaft, and a fan of the aeroplane propeller type mounted on a portion of said shaft overhanging said bearing means and arranged to eflect a forward flow of air at a relatively high linear velocity through substantially the entire area of said inlet opening and substantially horizontally across said chamber in intimate contact throughout its passage with the descending water therein, whereby a substantial water cooling effect is attained in said air chamber.

Signed at New York city, in the county of New York and State of New York, this 16th day of March, A. D. 1928.

DION KANOUSE DEAN. ERNEST LINWOOD CAHOON.

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