US1957779A - Heat exchange device - Google Patents

Description

May 8, 1934. J. J. HOPPES HEAT EXCHANGE DEVICE 2 Sheets-Sheet l Original Filed Feb. 14, 1951 III/1111111111111 INVENTOR ATTORNEYS May 8, 1934. .1. J. HoPPEs HEAT EXCHANGE DEVICE Original Filed Feb. 14 1931 2 Sheets-Sheet 2 INVENTOR ATTORNEYS Patented May 8, i934 @riginal application February l-i, 1931, Serial No.

Divided and this application January 25, 1933, Serial No. 653,51

7 Claims.

This invention relates to improvements in that class oi heat exchange devices in which a heated fluid is passed tfough a fluid-tight casing, the heat oi this fluid being transmitted. to a second fluid passing through tubes arranged in the path of the heated iiuid; this application being a division of my application Serial No. 515,808, led February 14th, 1931, upon which issued Letters Patent No. 1,898,727, dated February 21, 1933.

The improved heat exchanger is particularly adapted for use in such industries as laundries where large amounts oi heated water unfit for further use are available, the heat of which may be transferred to a supply oi clean water of lower temperatures with a consequent increase in operating economy. Since this hot waste water carries a large amount of foreign matter either in suspension or otherwise, the depositing thereof on the tubes lowers the eiiciency of the heat transmission, the deposit or sludge acting as an insulator.

An object of the invention is to provide a preliminary hopper-shaped settling chamber wherein a portion of the sludge may be precipitated, thereby preventing such portions from passing into the interior oi casing or" the device.

Another object is the provision oi an improved casing construction so designed that the fluid carrying tubes are at all times completely submerged, whereby drying and consequent hardening or" the sludge is prevented.

Another object is to provide a casing construction for a heat exchanger ior the purpose oi maintaining the temperature the duid receiving the heat at a more const it value. It is obvious that fluctuations in the temperature oi the heated iiuid is the ca1 or" any fluctuations in the temperature oi the fluid rec iving the heat. 1n the improved casing construction the heating fluid is pe itted to follow the natural tendency to establish upward currents within itself, the velocity and extent of the movement oi the currents being in direct proportion to the amount ci heat contained therein. Therefore, ii an occasional quantity oi colder waste water passes through the device, the currents will rise to a lesser altitude, as a consequence of which the temperature or the fluids in the upper portions oi the casing is not greatiy reduced.

In the accompanying drawings:

Fig. 1 is a iront elevation of a heat exchanger in which the principles of the invention are embodied, the view being broken away at points to show interior elevations.

Fig. 2 is an end elevation of the right hand end of the device, this view being broken away to show interior constructional details.

Fig. 3 is an enlarged fragmentary longitudinal section on the line 3-3 of Fig. 2.

Fig. e is an elevation of the left hand end of the device, the view also being broken away to show portions of the interior details.

Fig. 5 is an enlarged fragmentary vertical section on the line 5 5 of Fig. l, showing details of the tube and header construction.

Fig. 6 is an enlarged fragmentary longitudinal section on the iine 6--5 oi Fig. 1i.

Referring to the drawings, the casing of the improved heat-exchanger is essentially a uidtight sheet-metal box, admission and discharge openings for the fluid giving up its heat, which will hereafter be termed the hot or waste water, being in the nature oi long, rectangular openings in the lowerniost portions of the end Walls. 1 represents the upper sheet, 2 the bottom or oor member, 3 the rear, 4 the front wall and 5 and 23 the end walls. The waste water enters at 6 and ows into a preliminary, hopper-shaped settling chamber '7 adjacent the end wall 5 where a portion of the sludge is deposited. This chamber is formed by an outer wall 8 extending upwardly from the extension 2 of the door sheet 2 to a point above the level of the upper casing sheet 1.

The settling chamber 7 is closed at its upper end by a horizontal sheet 9 secured to the upper edges of the wall 8 and to a Wall member l0 which in turn is secured to the right-hand edge of the upper sheet 1. The chamber has a slop ing bottom l1 for the greater portion of its extent for the purpose oi facilitating the deposit of any sludge, the slope causing the sludge to gravitate to the bottom '7' of the chamber from where it may be drained oii at intervals through the drain pipe 12.

The flow of hot water is turned downwardly on entering the settling chamber as shown by the arrows in Fig. 2, then upwardly, there being a vertical baiie member 13 longitudinally disposed in the chamber I7; there being a horizontal wall 1B which closes the space in the settling cham` ber above the inlet on the outer side of the baflie so that all water must pass beneath the baiiie in proximity to the inclined bottom 11. The end wall 5 of the casing forms one side of the charnber and extends upwardly to a point not less in height than the level of the upper casing member 1, and provides an opening 14 between the upper edge 5' of the wall member 5 and the chamber top member 9. This opening 14 communicates with a vertical channel 15 formed between the end wall 5 and a partition member 16 placed in parallel relation therewith and preferably extending the full width of the casing from front to rear, the front and rear walls oi the channel being extensions of the wall members 4 and 3, respectively. The hot water then flows downwardly through this narrow vertical channel l5 and into the casing through an opening 17 below the baffle member 16, the bailie 16 extending to within a short distance of the iioor 2 of the casing.

The accompanying drawings show a casing whose interior is divided into two compartments by a single vertical, transversely disposed partition member 18 in parallel relation with the end walls and joined at its upper front and rear edges preferably by duid-tight joints to the upper member and front and rear walls 4 and 3. This partition also extends to within a short distance of the iieor 2, providing a horizontal opening 19 similar to the opening 17. The two compartments mentioned are designated C and C', and are termed heat-exchanging chambers, since in each chamber are inserted interconnected. unitary structures comprising tubes, headers and other associated details through which the fluid to be heated is passed. In the present specication the fluid being heated is termed simply the clean water, while the description of the conduits carrying the same will appear at a later point.

The path of the ilow of hot water through the chamber C is undulatory, the water arising irnmediately on entering the chamber through the opening 17 by virtue of its heat. As it ascends, heat is lost and the velocity of this upward current is reduced, and on impinging on the under surface of the upper sheet 1 the water is diverted to the left, flowing downwardly through the left side of the chamber C along the partition 18 towards the opening 19. The opening 19 is, of course, the inlet opening to the chamber C', wherein a repetition of the iiow just described occurs. The outlet for the chamber C is also ad jacent the iioor member 2 in the same manner as the openings 17 and 19 are arranged and is designated as at 20, Fig. 1. The iiow after passing through this opening 20 is upwardly through a narrow vertical passage 21 formed by the parallel position of a battle sheet 22 and the end wall 23 at the left extension of the casing. The passage 21 discharges into an enclosure comprising the walls 24, 25 and 26, Fig. 7, in connection with suitable front and rear wall extensions forming a fluid-tight passage-way leading to the discharge connection 27, it being noted that the ilow through the enclosure reaches an altitude greater than the level of the upper portions of the casing, as the edge 23 of the end wall 23 extends above the upper sheet 1, in the same manner as described in connection with the upper edge 5. The advantage gained in causing the incoming and outgoing flows of hot water to be at greater elevations than the upper portions of the casing is that the casing at all times remains completely lled with water Whether in operation or not, therefore any sludge that may be deposited within the casing or passages leading to and from the same, or upon the clean water conduit arrangements, remains in a more plastic condition, being prevented from drying and consequent hardening which would result in an expensive cleaning operation. This construction also permits the drainage of the settling chamber 7 without lowering the level of the water in the interior of the casing.

By causing the waste water to enter and leave at the lowerrnost portions of the casing the previously mentioned advantage is gained of allowing a short-circuiting of any occasional quantities of colder waste water, the path of such being comparatively direct from the casing inlet 17 to the outlet 20, the water, by its greater density remaining near the iloor. A further minor advantage is that, by the provision of hand-hole openings normally covered by cover-plates such as are indicated at 28, Fig. 2, and at 29, Fig. 4, access may be had to the iicor area of the casing for inspection or such cleaning thereof as may be desired. The casing may be drained by opening a valve (not shown) connected with a drainpipe preferably located near the casing outlet 20.

The improved heat-exchanger is designed to provide that a modiiication of the effective' counter-iow scheme is employed, the path of the flow of clean water receiving heat starting at the lower left extremity of the device and terminating at the lower right portion in proximity to the waste water inlet. It is clear from the description so far that the path followed by the waste water is a series of undulations moving from right to left, and that a chamber such as C encloses a single undulation consisting of a descending and ascending column of water of substantially rectangular cross-sectional area.

The simplest counter-flow arrangement would be to cause the path ci the clean water to closely conform to the undulatory path of the waste water in all respects, but I prefer the modied' arrangement such as is shown and described in the present case, wherein the path of the clean water zig-zags to and fro in a generally upward movement through a descending column, and conversely to and fro in a generally downward movement through an ascending column, of waste water. The exact relation of the paths one to another may be stated in other words by explaining that a cross-section taken on a horizontal plane through either an ascending or descending column of waste water is substantially rectangular in form, the long dimension extending from front to rear, and that the path of the clean water within the casing is always parallel to the long dimension.

Such an arrangement has an advantage in that an extended clean water path is provided in a relatively small space. There is also an.v advantage that it is possible that a desired number of tubes and associated parts may be combined into a unitary structure of which a plurality are employed, each of which may be inserted or withdrawn into or from the casing independently of the others, all connecting mediums conveying uids from one to another of the structures be ing made on the outside of the casing.

The clean water is conveyed throughout the casing interior in tubes 31 of which a preferably equal number is associated in each unitary structure or bank, in the present case there being two banks for each single heat exchanging compartment such as C or C". The tubes are arranged in vertical and horizontal rows, as seen best in Figs. 1 and 5, although it is clear that a staggered arrangement could be employed. Referring to the initial bank, employed in the left portion of the chamber C', the tubes are secured at their forward ends in a flat plate 32 and at their farther ends in the raised portion 33' of a hollow header 33 preferably by a rolling and calking process, this operation at their connecn. uu

tion with the header 33 being performed through openings in alignment with each tube, the openings being closed by the plugs 33C.

The front wall Al of the casing is provided with rectangular openings a through which the unit is inserted into the casing. Rollers 33d are fitted to the bottom portions of the headers 33 whereby greater ease oi assembly may be secured. The plate 32 is sufficiently large to act as a cover for an opening l and through the overlying portions or the plate 32 screws are inserted which thread into openings in the front wall 4, and also passing through the overlying flange 34 of a dish-shaped cover casting 34. The dished interior of the cover casting is divided into compartments by horizontal baies 35 and 36 into the compartments 343, 31th and 34C, these baffles being of such height as to bear against the plate 32 and eectually prevent the passage of fluid from any compartment to another. In the rear header 33 an integral baille 37 is employed, which divides the interior of this header into two compartments 33a and 33h. The alignment of the bafiies 35 and 36 in the cover 34 in relation to the baille 37 in the header 33 is such that the compartment 34a communicates with a plurality of tubes which discharge into the lowermost portion of the compartment 33a, while tubes leading from the upermost portion of the compartment 33a discharge into the lowermost part of the compartment 34h. The tubes in communication with the upper portion of the compartment 34h lead to the lower portion of the compartment 33b in the rear header, and from the upper part of this latter compartment the tubes discharge into the compartment 34C at the upper end portion of the cover 34.

Openings 33 and 39 are provided in the raised portion of the cover casting 34, the opening 38 being an inlet opening where the clean water makes its initial entrance into the conduit arrangement, communicating directly with the compartment 34a, while the opening 39 communicates with the compartment 34. It will then be seen that the clean water flowing into the compartment 34a travels rearwardly through the lower tubes into the compartment 33a and is then returned forwardly to the compartment 34D, then again in a rearwardly direction into the lower part of the compartment 33h, then forwardly into the compartment 34.0 and outwardly through the opening 39. Alternate movements are thus made in a direction generally upward, and since the bank as just described occupies the left hand portion of the chamber C' in which portion a descending column of waste water is flowing, a heat transfer in accordance with the preferred modied form of counterflow takes place.

The water issuing from the upper compartment 34C passes through the opening 39 and through a hollow duct 40 into the upper compartment 34C of the cover 34 or" the succeeding bank of tubes, which bank is placed in the right side of the chamber C. By admitting the fluid to this compartment, which is in fact the compartment 34C of the second bank, the water1 flows towards the rearward header and thereafter in a generally downward direction to the opening 38 in this bank, and is then conveyed by the duct 41 to the succeeding banks. The generally downward movement of the clean water in this bank is also in a direction counterwise to that of the waste water, which in this half of the chamber is up wardly. The flow of clean water continues as described through all of the plurality of banks of tubes, nally issuing at the outlet opening 33 in the bank nearest the waste water inlet 1'7.

A plurality of banks such as have just been desc 1ibed are employed in the heat exchanger. The present drawings show four only, these being placed two each in a single compartment such as C or C', therefore there are two forward and two rearward movements of the clean water for each ascending or descending columns of waste water, or sixteen to and iro movements for two undulations in the heat exchanger illustrated in the drawings. This provides perhaps the shortest path practical for either of the fluids for an exchange of heat of any appreciable economy; certain circumstances may indicate that a more complete abstraction of the available heat units in the waste water may be made by providing a longer path for the fluids. The design of the present exchanger lends itself to such extensions as it is only necessary to employ additional chambers and banks of clean water conduits, using the casing and constructions as described, it being understood that a partition 18 is employed between adjacent chambers.

Having thus described my invention, I claim:

l. In a heat exchange device, a main casing having tubes therein, a settling chamber at one end of said casing having an inclined bottom, said settling chamber being in communication with said casing by a passageway that leads from a point above the bottom of said chamber to a point at the bottom of said casing, a iiuid inlet leading to said chamber and a fluid outlet leading from said casing.

2. In a heat exchange device, a main casing, a bank of tubes therein, a settling chamber at one end of said casing having an inclined bottom, a fluid inlet in the upper portion of said chamber, a vertically-arranged barile adjacent said inlet and extending below the same but terminating above said inclined bottom, a communicating passageway between the upper portion of said settling chamber and the lower portion of said casing, and a iiuid outlet leading from said casing.

3. In a heat exchange device, a main casing, a plurality oi tubes therein, a settling chamber at one end of said casing, a pair of separated walls forn a passage between the upper end of said settling chamber and the lower end of said casing for the full width of the casing and chamber, said settling chamber having an inclined bottom, a fluid inlet leading into the upper portion of said settling chamber, a baille wall adjacent said inlet extending the full length of said settling chamber and terminating below said fluid inlet, and a wall enclosing the space above said inlet on the outer side or" said baiiie member.

4. In a heat exchange device, a casing, a plurality of tubes therein, means for supplying liquid to said casing including a vertically-extending passage, the entrance to said passage being above the desired liquid level to be maintained in said casing and the discharge end of said passage leading to the extreme lower portion of said casing, and means for discharging liquid from said casing including a vertical passage-way, the lower end of which communicates with the extreme lower portion of said casing and the upper end of which is above the desired uid level to be maintained in said casing.

5. In a heat exchange device, an enclosure, a plurality of tubes in said enclosure arranged from a point adjacent the bottom to a point adjacent the top thereof, means for admitting and discharging fluid to said enclosure at the bottom thereof so arranged as to maintain a constant level of fluid in said enclosure about said tubes and permit short-circuiting of the fluid through said enclosure below said tubes.

6. In a heat exchange device, an enclosure, a plurality of tubes therein, with a space in said enclosure beneath said tubes, a fluid supply passage leading to the bottom of said enclosure one point at least of which is above the desired liquid level to be maintained in said enclosure, and a fluid discharge passage leading from the bottom of said enclosure one point at least of which is above said liquid level, the space in said enclosure beneath said tubes permitting a llow of cold fluid directly therethrough from the supply passage to the discharge passage.

7. In a heat exchange device, an enclosure, a plurality of tubes therein with a space in said enclosure beneath said tubes, a fluid supply passage leading to the bottom of said enclosure, a lluid discharge passage leading from the bottom of said enclosure, one point at least of each of Said passages being above the desired liquid level to be maintained in said enclosure, means in said enclosure to direct the water upwardly and downwardly about said tubes, the space in the bottom of said enclosure permitting ilow of cold fluid directly therethrough from the supply passage to the discharge passage.

JOHN J. HOPPES.

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