US1982010A - Heat transfer apparatus - Google Patents

Description

Nov. 27, 1934. D. R. M NEAL.

HEAT TRANSFER APPARATUS Filed April 16, 1932 2 Sheets-Sheet 1 lllllll llllllllll I VENTOR ATTORNEYS.

NOV. 27, 1934. R, MCNEAL HEAT TRANSFER APPARATUS Filed April 16, 1952 2 Sheets-Sheet 2 a INV%TOR f-Mwu ATTORN EYS.

Patented Nov. 27, 1934 iJNITED STATES lPAiTEN'i" FFICE Appiication April 16, 1932, Serial No. 605,618

3 Claims.

This invention relates to heat transfer apparatus and is especially concerned with aftercooler apparatus for cooling air or any other gas,

particularly under pressure.

The general objects of the invention have reference to improved efliciency, construction of the parts in such manner as to greatly increase their life' and provision of cooling apparatus which is not only simple and inexpensive in manufacture but which is, furthermore, readily inspected, re-- paired or the like.

To consider some of the more or less detailed objects and advantages, it should first be noted that at least certain features of the invention are especially useful for cooling air or other gas under pressure. An air or gas compressor ordinarily results in a substantial increase in the temperature of the air or gas. For many reasons which need not be considered in detail herein,

1 it is desirable, either before storage or before use,

or both, that the temperature of the gas or air be decreased or lowered. Such cooling is also, at least in many instances, preferably effected at a point relatively close to the compressor. However, the action of the compressor results, among other things, in irregularities in pressure or pulsations of the gas. Such pulsa ions, especially where they are substantially constant throughout the use of the apparatus, have heretofore produced vibrations in the cooling apparatus and as a consequence, parts of the cooler have become worn or shaken loose so that breakdown or leakage results.

It is an important object of this invention to construct an air or gas cooler of a type capable of withstanding vibrations or the like. The particular manner in which the foregoing is accomplished will appear more fully hereinafter, it being merely noted at this point that the invention has in View materially increasing the life of the cooler parts, especially with respect to wear and leakage encountered heretofore as a result of vibrations set up by the compressor.

Another problem in connection with the foregoing should also be considered at this point. In

' Fahrenheit or even higher, and this high temperature air, together with oil vapors in the receiver, has resulted in explosions of a very serious character.

However, in accordance with ,the arrangements of the prior art, it has not been practical'to locate the air cooler closely adjacent to the compressor (for example, between the compressor and the receiver) for the reason that the pulsations resulted in excessive vibration and resultant wear on various parts of the coolers employed. Thus, in accordance with this invention, I contemplate the interposition of an air cooler between the compressor and the receiver.

Ordinarily, moisture and vapor separators operate only very inefliciently under pulsating pressure conditions. However, since the cooler of this invention serves to minimize or very greatly reduce the force of the pulsations, I am enabled to employ a separator in the connection between the compressor and the receiver. This separator, as will be explained more fully hereinafter, is preferably associated directly with the cooler to constitute a unitary part thereof. The advantage of such an arrangement, of course, resides in the fact that a large quantity of the oil and water vapors are condensed during cooling of the air and thus never even enter the receiver tank. With the reduced quantity of oil and water vapor and condensate in the receiver tank, and with the very substantially lowered temperature of the air before its entry into the receiver, the possibility of explosion is practically eliminated.

How the foregoing and other objects and advantages are obtained will be apparent from a consideration of the following description making reference to the accompanying drawings, in which Figure 1 is a somewhat diagrammatic side View of an air compressor and reservoir with the cooler of the present invention associated therewith;

Figure 2 is a longitudinal sectional view taken through the inlet end of the cooling apparatus;

Figure 3 is a view similar to Figure 2 but taken through the outlet end of the apparatus;

Figure 4 is a transverse sectional View taken substantially as indicated by the section line 4-4 on Figure 3;

Figure 5 is a view showing a plurality of the cooling units of this invention associated in a particular manner to illustrate certain desirable features thereof; and

Figure 6 is an elevational view illustrating the heat exchanger of this invention mounted in a generally horizontal position.

Referring first to Figure 1, a compressor is indicated by the reference numeral 6, it being noted that the specific construction of this compressor need not be considered in detail herein since it forms no, part of the present invention per se. It might be noted, however, that such a compressor ordinarily produces pulsations in the air or gas being compressed. The air reservoir or receiver is illustrated in Figure 1 at 7 and is shown as being equipped with a discharge or supply pipe 8 and an inlet connection 9 between which and the discharge connection 10 of the compressor, the cooler, generally indicated at 11, is interposed. While the foregoing general arrangement of compressor, cooler and receiver is particularly advantageous for reasons above brought out, it should be understood that at least some advantages of the construction'of the cooler herein specifically disclosed may be obtained by the arrangement of the several parts in other ways.

The cooler 11 (see Figures 1, 2 and 3) includes an elongated cylinder orshell 12 having, at one end thereof, a header or connection device 13. This header constitutes the inlet means for the cooler and is provided with a pipe connection or nipple 14 extended transversely of the shell 12.

Airor gas tubes 15 are extended lengthwise through the shell 12 and terminate, toward the inlet end, in a tube sheet 16 which may conveniently be secured in position between shoulder 17 formed on the header 13 and shoulder 18 arranged at the end of, the casing or shell 12. Suitable packings or packing rings 19 may be interposed between the tube sheet and the shoulders 17 and 18 and these several parts are rigidly secured to'each other as by means of bolts 20.

At their other ends, the tubes 15 terminate in a sheet 21 which is arranged for sliding movement inside the shell 12 in order to compensate for relative expansion and contraction of the tubes and shell. At the outlet end an additional header or connection device 22, having a transversely extended discharge nipple 23, is arranged for connection (in accordance with the layout of Figure 1) through pipe 24 with the inlet 9 of the reservoir 7. The inlet and outlet headers may thus be similarly formed and they may conveniently be provided with closure or cover plates 25 and 26 arranged at opposite ends of the cooling unit.

In accordance with this invention, the several tubes 15 which constitute the cooling elements are each belled outwardly at their ends as indicated at 15a in Figures 2 and 3, beyond the two tube sheets 16 and 21. Thus the tubes together with their belled ends constitute generally Venturi shaped passages, the advantages of which will be touched on more fully hereinafter.

While I may arrange the outlet or discharge header 22 immediately adjacent to one end of the shell 12, I prefer to interpose a gas or air drying device, generally indicated at 27, between the end of the cooler proper and the discharge header 22.

As shown in Figure 3 the separator or drying device includes spiral vanes or baiiies 28 arranged to separate moisture and provide for accumulation thereof in the chamber 29 to be withdrawn this invention it is conveniently associated with the cooling unit to constitute a part thereof. It

- is further observedthat in accordance with this arrangement the separating chamber, in effect, constitutes a portion of the outlet or discharge header.

The present invention further provides for the attachment of the discharge header means (with or without the separator) directly to the tube sheet 21, bolts 31 or the like being provided for this purpose. A packing ring or gasket 32 is interposed between the outer face of the tube sheet and the header part associated therewith. A packing device including a gland 33 and packing 34 is arranged between the shell or casing 12 and the circumference of the tube sheet 21. Adjusting and tightening bolts 35 serve to maintain the proper joint between these parts.

From the foregoing it will be seen that, in contradistinction to the more usual practice, this in- 12 and an outlet 37 1s provided adjacent the other end. Thus the arrangement provides for counterflow of the cooling medium. The counterficw,

however, is not direct, since the invention further makes provision for the use of a novel type of baffle means in the shell to cause the cooling medium to follow a substantially transverse path across portions of the tubes. As will be seen in Figures 2, 3 and 4, the bafile means include a series of parallel and spaced baffle elements 38 each of which extends transversely or across sectionally of the casing 12. As clearly seen in Figure 4, each baffle 38 is provided with a rounded edge at one side thereof to conform to the inner surface of the shell 12. At the other side (the division line lying approximately along a diameter of the shell) each element 38 is cutaway, as indicated at 39, to provide a semi-annular passage 40 through which the cooling medium .may pass in its flow beyond each successive bafile. By reference to Figure 4 it will also be seen that the tubes 15 are arranged in a cylindrical nest or bundle of such diameter as to leave a substantially unrestricted annular passage or cavity just inside the casing 12. The several baffles 38 may be spaced from each other as by means of the thimbles or sleeves 41 threaded on one or a few of the tubes in the manner clearly shown in Figures 2, 3 and 4. In order to ensure passage of the cooling medium between the tubes themselves rather than around the edges of the bundle, additional baffle elements 42 are extended lengthwise between the plates 38, these additional bafiies also preferably being arranged at diametrically opposite sides of the tube nest (see Figure 4) With bafiies of the fore going type alternately disposed as shown in Fig ures 2 and 3, the water or other cooling medium entering through the inlet 36 first passes transversely across the tube nest and then upwardly (as viewed in Figure 3) beyond the cutaway-portion of the first baiiie 38. From this point the medium is again deflected in the opposite transverse direction for passage through the tubes and, as a result, the flow, in general, is from one end of the casing 12 to the other, although the medium moves in a zigzag path during this gen-.

.Another feature of the invention involves the use of removable or detachable supporting feetor brackets 43 (see Figures 1,.31and 6) arranged to cooperate alternatively with any one :of a :num-

er of attachment means 44 with which the easing l2'is provided. AssshownainFigures 1,?Brandi6 these attachment means 44 are provided :at ion-- git-udinally as well .as radially ofiset :points and the brackets 43 are so constructed that they may readily be securedto the casing atone endithere of only (for example, as shown in Figure :1 to sup port the cooler in a vertical position) or one at each end thereof (for purposes ofrsupport .a substantially horizontal position, as Shown in Figure 6) Before considering the operationof the apparatus thus far described, .referenceshould :bermade to Figure 5 in which I have illustrated a parallel arrangement or" a pair of cool ng units of the type shown in Figures 11 to '4 inclusive. 'Withithls arrangement, the air supply line 1011 may .iconveniently be coupled. with the header 1311 at one end of one unit and the discharge connection Zea may similarly be associated with the header 13b of the other unit, .the two headers 13a and 13b just mentioned being located adjacent to each other. Similarly, at their other ends, the outlet headers 22a) and 22b may be interconnected by the pipe l5. Thecooling medium .or water connections are similarly arranged and, as shown, include connection of the supply line 46 with the inlet 37?), connectionof the discharge pipe 47 with the outlet 37a and an interconnecting pipe 28 extended between the connection means 36b and'36a.

In considering the operation, first of the arrangement illustrated in Figure 1, assume first that the compressor 6 is being employed to deliver air under pressure to the receiver 7. As noted above, this action results in irregular or pulsating pressure conditions in the air line. Heretofore, such pulsations have resulted in vibration or the like of various portions of the cooling apparatus employed and the vibrations, in turn, have not infrequently producedbreakdowns or at least difficulties with respect to leakage. Before proceeding further with the operation of the particular cooler disclosed herein, "it should be noted that heretofore the air has ordinarily been circulated around a plurality of tubes through which the cooling medium is passed. With such arrangements the vibrations resulted in loosening of the tube joints in the tube sheets I and further, where baffles were employed, the vibraiions resulted in cutting or wearing of the tubes at points where they passed through the baffles.

In the arrangement herein disclosed, which provides for the passage of the air or gas to be cooled through the tubes, rather than around them, and further with belled openings at each end of each tube, any tendency to produce vibrations is practically eliminated. The cause of this may possibly be involved in the Venturi action of the belled tubes or it may possibly be because the water or other cooling medium surrounding tubes aids in damping out or absorbing the vibrations, or both. However, whatever may be the cause of the wear heretofore encountered, I have found that by passing the air through the tubes and the cooling liquid around the tubes by the means above described, wear of the tubes by the bafiles and loosening of the tubes in their supporting sheets is very materially reduced, so that, as a practical matter, these vibrations are no longer a'factor'in determining the life :of the cooler.

The reduction in vibration and wear also per-' mits the use of tubes which are not individually packed in the tubesheets. In the practice of the priorart, where the vibrations were likely to loosen the tubes in their sheets, individual packings for the tubes have sometimes been employed. Individual packings, of course, necessitate a wider spacing of the tubes and also produce other obvious disadvantages.

As :an additional advantage which flows from the damping out of the vibrations or pulsations in the .air being cooled, it is observed that the condition of the air after it is discharged from the cooler proper is such that a separator of the character above referred to may readily and efliciently beemployed to remove condensed oil and water vapor .prior to entry of .the air into the receiver.

.Inaddition to the foregoing, in accordance with prior practice (that is, where the air or gas to be cooled was circulated around the outside or anest of tubes) it was necessary to employ various packing devices which were subject to air or gas pressure. .Such packing devices were necessarily employed between a'tube sheet and the casing of the cooler in order to permit relative movement thereof and thus compensate for expansion and contraction. With the apparatus of this invention, the means arranged to compensate for expansion and contraction requires a packing which is only subjected to the pressure of the cooling medium, this quite frequently being relatively low as compared to the high pressure of the gas or air often employed. An additional point to be considered is the fact that the cool ing medium isvusually a liquid and a packing device, of course, may be arranged for much more eflicient operation to prevent leakage of a liquid than to prevent leakage of air orany othergas.

A further feature of importance resides in the use of an inlet header having a connection extended thereto generally transversely of the ex tension of the cooling tubes. This will be apparent from inspection of Figure 2 in which it will be seen that the incoming air, in making-the turn from the inlet nipple to the entrance ends of the tubes, will be very uniformly distributed between the several tubes. The inlet arrangement just referred to also cooperates with the belled ends of the tubes in reducing vibrations and the like.

The arrangement of the inlet and outlet headers for cooperation with transversely extended connections is also of advantage in compensating for-expansion and contraction, because, during relative movement of the two headers (by expansion or contraction), the associated pipe connections need only flex slightly transversely thereof and, as a result, there will be no tendency to -cause buckling of the connections extended to the cooler.

The arrangement of the connections, furthermore, including :those for the cooling medium, is also advantageous in facilitating mounting of the cooler in any desired position (usually vertica-lly or horizontally). As will also be apparent from inspection of Figure 5 the connection arrangements, particularly the extension thereof u with respect to the longitudinal axis of the cooler, are further such as to facilitate mounting of two or more of the coolers, it being noted that this facility is maintained even though the coolare are horizontally or vertically disposed. When a plurality of the units are arranged as in Fig.- ure 5, the air and water line connections are not subject to any bending or buckling strains whatever during expansion and contraction, since'all of the necessary connections are associated with parts which are relatively fixed. Thus, referring to Figure 5, the supporting elements 43 are arranged to support the casings of the cooler units, as well as all the connections extended to and from the units, in a fixed position, and when expansion and contraction takes place, the lower and interconnected headers move up anddown with the lower tube sheets 21.

As an additional advantage, the cooler elements themselves, i. e., the nest of tubes with its associated tube sheets, may be removed from the casing as a unit. In this way, the original construction, maintenance, inspection and repair are all materially facilitated, it being noted that in order to remove the internal-elements, it is necessary only to remove nuts 31, remove the upper header (as viewed in Figures 2 and 3) and then pull out the nest of tubes with its associated tube sheets. Access to the interior of the tubes themselves may also be had by mere removal of the end cover plates for the inlet and outlet headers.

The apparatus of this invention has further been found, by actual test, to effect a certain washing or cleansing of the air being cooled. While the exact reasons for this are not all definitely known, at the same time, experiments show that by the passage of the air to be cooled through a plurality of relatively small diameter tubes of the character above described, the tendency for dirt particles, dust and the like to carbonize in the tubes is very materially reduced as compared to the marked tendency to carbonize where the air to be cooled is circulated around the exterior of a nest of tubes. ther shown that, with the various parts of the cooler arranged, for example, as shown in Figures 1, 2 and 3, a very large percentage of the dust and dirt is removed with the oil and water condensate in the separator.

ly in excess of that effected by other separator arrangements. In fact, the percentage of dirt removed is much greater than that effected by the use of a separator, even substantially identical to the one shown, when the separator is located with other types of cooling apparatus or in some other relation with respect thereto.

Finally, it should be observed that while certain features of the invention are particularly useful in the cooling of air under pressure, for reasons fully brought out above, at the same time, at least certain features of the invention are equally applicable to heat exchange apparatus for other purposes.

1. Gas or air heat transfer apparatus including anelongated cylindrical casing adapted for the passage of a heat transfer medium therethrough generally from one end to the other end thereof, tubes extended lengthwise through,

Experiment has fur- Indeed, the percentagev of dirt and the like removed in this way is greatthe casing for the gas or air between which and said medium the heat transfer is to be effected,

deflecting said medium in a transverse direction across portions of said tubes, said bafiie means including plate-like elements of generally circular shape having approximately one-half thereof dimensioned to fit the interior curvature of the casing and having a semi-annular cutaway-portion at the other side thereof to provide for passage of the medium generally axially of the casing in the annular space between the nest of tubes and the internal casing wall, there being a plurality of such plate-like elements arranged in spaced relation along the length of the casing with their cutaway-portions alternately oppositely disposed at different sides of the casing, together with additional baffles extended between said plate-like elements and lying in planes disposed generally radially of the casing in the annular space between the inner casing wall and the nest of tubes, there being baffies of the type last mentioned positioned at opposite sides of the casing adjacent the points of termination of said cutaway-portions of the plate-like elements.

2. In heat transfer apparatus an elongated tubular casing, heat transfer elements in the casing extended generally lengthwise thereof, connection means arranged toward opposite ends of the casing at oneside thereof, and means for supporting the. casing in either substantiab H ly upright or substantially horizontal position,

the last means including a plurality of attachment means adapted to cooperate with supporting elements, the attachment means being car-' ried by the casing and spaced from each other thereon toward opposite ends of the casing and radially offset from said connection means, whereby said attachment means may alternatively be associated with different supporting elements to provide for support of the casing in substantially horizontal or substantially vertical position and at the same time to maintain convenient access to the connection means for the purpose of making connections to and from the heat transfer elements.

3. In heat transfer apparatus, an elongated l'.

tubular casing, heat transfer elements in the casing, and a mechanism for supporting the casing in either one of at least two different positions, such mechanism including a plurality of supporting means carried on the casing, the supporting means being positioned at points which are radially and axially offset from each other, whereby various of the supporting means may alternatively be employed to cooperate with fixed supports spaced axially or circumferentially of I- the casing and thus provide for support of the casing in a generally horizontal position or in a generally vertical position.

DANIEL RAYMOND MCNEAL.

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