US2884229A

US2884229A - Heat exchanger

Info

Publication number: US2884229A
Application number: US722562A
Authority: US
Inventors: Norman L Francis; Eugene P Berg
Original assignee: Link Belt Co
Current assignee: Link Belt Co
Priority date: 1958-03-19
Filing date: 1958-03-19
Publication date: 1959-04-28
Anticipated expiration: 1976-04-28

Description

N. 1 FRANCIS EAL 2,884,229

' HEAT EXCHANGER 2 Sheets-Sheet 1 April 28, 1959 Filed March 19. 1958 April 28, 1959 N. L.. FRANCIS ET AL VHEAT EXCHANGER 2 Sheets-Sheet 2 Filed March 19, 1958 United States Patent 2,884,229 r'IEAT EXCHANGER Norman Francis, La Grange, and Eugene` PI. Berg,

Wilmette, Ill`.,a`ssignors to Link-Belt Company, a corporation ofy Illinois Appiicafion Maren 19', 195s, serial No. 7'2"'2562- ldClaiins".l (Glt'ZST-t-S-l) 'this invention. relates tjo heen;` exchange devises and deatsjnioreparficiilarly with apparatus for heating or cooling fion/able solids which are' fed through the' apparatus' tiusly. y

A primary' object of ythe inventionY isy 'toy provide a 'cwvabl'ey solids heat erelijanger"l wherein a high percentage ofthe solids passing through the exchanger is exposed to` direct' contact with heat transfer surfaces. A n

vAnother object of the invention is to provide a owable solids heat" exchanger wherein the conyeying tnotio of the device is employed' to' continuously circulate heat' exchange iiuid' over the heat transfer surfaces at a selectively controlled rate. v

rAnother object of tliel invention is to provide a li'wable solids heat exchanger wherein a plurality ofl heat transferl elements are continuously r'novedl through the material andy heat exchange fluid is circulated through each element during. its passage through the material.

lAnother object' of the invention is to provide a iowablev solids heat exchanger wherein each heat transfer element is chargedI with heat exchange iiuid during the initial portion of its passage throughl the material and is drained ofy heat exchange huid between successive passagesl through the material. Still another object of the invention is to provide a iiow'able solids heat exchanger whereinthe heat exchange elements are ofv simple construction andare easily cleaned of deposits which may be left` by the heat exchange uid.

Other objectsvand advantages ofthe invention will become' apparent by reference to the following specification taken in conjunction with the accompanying drawings.

In the drawings l Figure 1 is a longitudinal, vertical sectional view of a beati exchanger embodying the invention;

Figure 2 isa transverse, vertical sectional view taken approximately along the line 2 2 of Fig. l', and;

Figure 3 is another transverse, vertical sectional view taken along the line 'S4-3 of Fig. l'.

The heat exchanger shown in the drawings includes a horizontal drum assembly designated' generally by the niir'neral 1'0 which includes a large diameter hollow cylindrical central section 12,. a reduced diameter hollow cylindrical" feedisection 14 and a" holloviicylindri'al discharge section 1'6; The feed section 14' and the discliar'ge section" 16 are' iixdly' secured t'o' the central sec# tion' 127 by annular end plates 18 and: 20, respectively, which may he secured to the respective sections by any suitable rneans such as' welding.

The drum.` `assembly is supported for' rotation about its longitudinal axisl with tlie drumI partially submerged in a body of heatexchange fluid 22 which: is contained within a tank' 24 of any suitable construction. The rotary suport for the drumv assemblyv 10 includes two concentric hardened steel tires 26 and 28 whichv are respectively mounted-upon the feed section 14 and the discharge section 16. Each drum. tire is rotatably supported. by a pair of rollers, one on each side of the verti- ICCv ment of the drum 10 in an axial direction, one off the tires, suchv 'as the tire 26, may be engagedbifaV 'of' axially spaced rollers 32. l

The drum assembly 10 is dli've'nI in rotation by't eou pling, a suitable source of power to a drivenge sproeket 34, which in the disclosed embodimentis mounted upon the discharge section 16. ,y

In some instances, it is desirable to provide activer member for the tank 24. Suchy a-cove't inem y nated- 36 in the drawings and isprefea "eoist'rl include a vent assemblyY 3s to perniit the escape of vaporiz'ed heat exchange fluid from the interior of the assembly. Where such a cover member i's' provided.. it is generally desirable to provide drip seals between the' stationary tank and` cover andthe fotatingdrnnr assembiy' as at 40 and 42.

Flowable solids are fed in'to the interior of the dri' 10 by means of a chute or tube 44 which proi'ects' i'to the interior of the feed section 14 through an open 'g46 formed in an end wall 48. Anl internal conveying screw 50 is mounted in the interior of the feed section 4" feed the material through the feedl sectiony and itl interior of the centrall section 12 through the opfe rig'llit hand end of the feedv section 14 which" is ifregifstry' with an enlarged central opening 52 the annular end? plate 18.

The discharge section 16Y isv likewise provided ir'itiiv an" internal conveying screw 54 for conveying. material' fron! the right-hand or discharge end of the central sectionl 12 through the open discharge end ofY the discharge: seciton 16. y K Y Heating or cooling of the materials' passing through the drum assembly 10 is accomplishedA during theV passage' of the material through the central section 12 of the drum assembly. The heat transfer elements erriployedI to heat or cool the material within the centraly section 1,2" take the form of a plurality of longitudinally extending hollow tubes 56, the opposite ends of which espectiiely project through the annular end walls 18`Indf2'0r; Each of the

end walls

18 and 20 is formed withya plurality of openings for receiving the ends of the tubes, the operi* ings being located symmetrically about the vaxis ofthe drum assembly 10 and preferably lying at' a.v common radial distance from the axis ofthe drum.V The respeetive ends of the tubes are sealingly secured to asso ciated end walls to prevent the entry of cooling Yuid froni the tank 24 into the interior ofthe central sectionl 12.

In the disclosed embodiment, the openings fori'ned the

end walls

18 and 20 are in axial alignment lwith' each other, as may besty be appreciated by reference to Fig. 2 of the drawings. However, the tubes 56 do not' extend between axially aligned openings but are instead extended between an opening in ,the plate 20" to an openn ingA in the plate 18 which is angularly displaced alic'fiut'y axis of the drum assembly 10. p

This may best be appreciated by identifying thexv efnd's of the tubes 56 which project throughl the annular-'end plate 20 at the discharge end of the centralv section Ii as,- inlet ends 58 and by identifying the ends of the tubes 56 which project through the anular end plate 18n asoutletl ends 60. Two adjacent tubes have been'identifiedA in Fig. 2 as 56a and 56b. The circumferential location. oi the inlet end 58a of the tube 56a is shown as being angularlydisplaced by some from the `circumferential ocation of the outlet end 60a of the tube 56a. Theamoun of angular displacement about the axis of the drum. as# sembly 10 of the respective inlet ends 58- and outlet ends 60 is equal both in amount and direction for allN of the assenza tubes 56, and hence the tubes 56 may be said to be disposed symmetrically about the axis of the drum assembly 10.

As indicated by the arrow A of Fig. 2, the direction of rotation of the drum assembly is clockwise when the drum is viewed from its feed end. The purpose served by the angular inclination of the tubes 56 to the axis of the drum may be best appreciated by following the movement of one of the tubes. Since twelve tubes are disclosed in Fig. 2, it will be convenient to refer to the successive locations of the inlet and outlet ends of the tubes by referring to these positions as though they were represented by numerals on a clock face. For example in Fig. 2, the 'position of the tube 56a places its inlet end 58a at the 3.oclock position with its outlet end 60a disposed at the 12 oclock position.

Clockwise rotation of the drum assembly 10 will move the inlet end 58a of the tube 56a downwardly from the indicated position in Fig. 2. The first location of interest assumed by the inlet end 58a of the tube 56a is its arrival at the 5 ocloek position. At this time, the open inlet end S821 begins to be submerged below the surface of the body of heat exchange uid 22 contained in the tank 24 and uid commences to flow into the tube and rising within the tube to the level of the body of tiuid within the tank. The outlet end 60a of the tube 56a, of course, follows the movement of the inlet end of the tube, and, at the time the inlet end 58a has arrived at the 6 oclock position, the outlet end 60a has moved downwardly to the 3l oclock position. Since the outlet end 60a is disposed well above the surface of the body of fluid 22 at the time of the greatest submergence of the inlet end of the tube, 'any steam or vapors trapped within the tube upon the submergence of its inlet end may easily escape through the outlet end of the tube and hence offer no resistance to the free ow of liuid into the tube body.

' As the inlet end of the tube is rotated to the 7 oclock position, the outlet end is lowered to the 4 oclock position, thus permitting the fluid to flow further into the tube. As the tube is rotated further to move its inlet end to the 8 oclock position, the outlet end moves to a level below that of the inlet end of the tube, thus trapping whatever fluid remains within the interior of the tube as the Vtube is rotated upwardly through the body of material M disposed within the drum assembly 10.

I t will be noted that the outlet end of each tube is provvided with a relatively restricted opening 62, within which vis disposed an orifice plug 64. The opening within the orifice plug may be so chosen as to control the rate of flow of iiuid from the interior of the tube as the inlet end is elevated above the outlet end. By selecting a suitably sized' oriijce, the bulk of the uid may be retained within theftube kuntilfthe latter has been rotated upwardly to a position clear' of the body of material within the drum, such as thatv assumed by a tube when its inlet end reaches the 12 oclockpostion and its outlet end reaches the 9 oclock'positio'n. Conveniently, the orifice plugs 64 are threadedly engaged within the discharge end wall 66 of each'tube and by providing sets of orifice plugs having varying diametered openings, the rate of flow of fluid from the tubes may be adjusted, as desired. It should be noted further that as the drum is rotated to return the tube 56a to the position illustrated in Fig. 2, the inlet end is again lowered below the outlet end and hence any fluid which has not drained from the tube is free to ow back to the tank through the open inlet end of the tube.

In cases where the longitudinal length of the central section 12 is not too great, the flow of material through this section may be satisfactorily accomplished merely by the hydraulic slope assumed by the material. This is due to the fact that the material piles up to a higher level at the inlet end. Where the length of the central section 12 is somewhat greater, it is often preferable to provide at least one full pitch of an internal screw conveying ight 68'` at a desired location in the central section 12. The

4l. radial width of the iiight 68 is preferably made such that the tubes 56 may be passed through the iiight and thus supported at a location intermediate their ends.

In cases where the unit is to be self-emptying, a narrow conveying spiral 70 may be located throughout the length of the central section 12, terminating adjacent to one of the discharge scoops 72, see Fig. 1.

On the external surface of the annular end plate 20, a plurality of scoops 74 are mounted, one adjacent the inlet end of each tube. The scoops 74 increase the amount of heat exchange tluid lfed into the tubes 56. The scoops 74 further provide some additional stiffening to the coupling between the end plate 20 and the discharge section 16.

The operation of the structure described below will be set forth in terms of a cooling operation wherein water is employed as the heat exchange liuid. It is believed apparent, however, that heat exchange fiuids other than water may be employed and that the structure described above is also adapted to perform a heating operation.

Water, or any suitable heat exchange uid, may be fed' into the tank 24 by means of a valved conduit 76 which is preferably located at the discharge end of the drum assembly.v Where a continuous ow of water through the tank 24 is desired, an overow or outlet opening may be provided at the end of the tank 24 adjacent the feed end of the drum assembly. In cases where the temperatures of the material being handled by the drum are such as to generate steam, the vent for the latter is preferably located. adjacent the feed end of the assembly, as indicated at 38.

Material to be cooled is fed into the feed section 14 through the chute or tube 44. Rotation of the drum assembly 10 by the application of a driving force to the driven sprocket or gear 34 rotates the drum in a direction to cause the internal conveying flights 50 to move material from left to right through the feed end section and into the central section 12. In most applications, the hydraulic slope assumed by the material within the drum assembly 10 is relied upon to convey the material through the central section 12 of the drum, although if necessary, this conveying action may be assisted by the internal conveying flights 68 and 70. Discharge of material from the drum is accomplished through the discharge section 16 by the internal conveying ght 54.

Rotation of the drum assembly 10 sequentially submerges the inlet ends 58 of the respective tubes 56 into the body of water contained within the tank 24. As explained above, each of the tubes 56 receives a charge of water during the passage of its inlet end through the body of uid and, as the inlet end of the tube is elevated, by the rotation of the drum, above the surface of the uid, a charge of uid is retained within the tube. Discharge of the fluid from the respective tubes 56 is controlled by the diameter of the opening within the orice vplug 64 located at the outlet end of the tube. The rate of .discharge of the fluid through the orifice opening is selected so that a substantial percentage of the uid chargedinto the tube during its passage through the tank is retained within the tube until after the tube has been rotated clear of the bed of material within the drum.

Rotation of the series of tubes through the material within the central section 12 of the drum assembly imparts a mixing action to the material to thereby expose a large percentage of the material within the central section 12 to direct contact with the heat transfer surfaces represented by the outer surfaces of the tubes 56. It will be noted that due to the orientation of the tubes S6, the fiow of cooling fluid through the tubes is in a direction countercurrent to the direction of movement of material through the drum. Further, since the outlet ends 60 of the various tubes are always located above the surface of the body of liuid while the inlet end of the tube is submerged in the body of uid, steam or vapor can freely ow from the interior of the tube through the orifice plug 64 as the tube is being charged with'a freshv Supply of heat exchange fluid.

While we have described but one embodiment of 'our invention, it will be apparent to those skilled in the art that the disclosed embodiment is capable of modilication. Therefore, the foregoingspecilication is to be considered exemplary rather than limiting and the true scope of our invention is that described in the following claims.

Having thus described the invention, we claim:

1. A heat exchanger for handling flowable solids comprising a horizontal drum having a feed end and a discharge end, an annular plate iiatly mounted on each end of said drum, feeding means communicating with the central opening of the annular end plate at said feed end, discharge means communicating with the central opening of the annular end plate at said discharge end, each of said end plates having an equal number of smaller openings therethrough disposed symmetrically about its central opening, a plurality of tubes mounted on said end plates, each of said tubes extending through a said smaller openings in one of said end plates and through a said smaller opening in the other of said end plates, said last two mentioned openings being angularly displaced relative to each other about the axis of said drum, a tank having a body of heat exchange uid therein, means supporting said drum for rotation about its axis with said drum partially submerged in said body of fluid to a depth at which said smaller openings are sequentially submerged in said fluid upon rotation of said drum, and means for rotating said drum.

2. A heat exchanger for tlowable solids as defined in claim l wherein the ends of said tubes at said one of said end plates are angularly displaced by equal amounts in a leading direction with respect to the direction of rotation of said drum from the respective ends of said tubes at the other of said end plates.

3. A heat exchanger for flowable solids as defined in claim 2 including regulating means for controlling the ilow of heat exchange fluid from the ends of said tubes at said other of said end plates.

4. A heat exchanger for flowable solids as delined in claim 2 including scoop means mounted on the outer Ysurface of said one of said end plates adjacent each of the smaller openings therein for transferring heat exchange uid from said tank to said tubes.

5. A heat exchanger for tiowable solids as dened in claim 4 including regulating means for controlling the ow of heat exchange uid from the ends of said tubes at said other of said end plates.

6. A heat exchanger for handling flowable solids comprising a horizontal drum having a feed end and a discharge end, an annular plate having its peripheral edge portion secured to each end of said drum, feeding means communicating with the central opening of the annular end plate at said feed end, discharge means communicating with the central opening of the annular end plate at said discharge end, each of said end plates having an equal number of smaller openings therethrough disposed symmetrically about its central opening at a common radial distance from the axis of said drum, a plurality of tubes mounted on said end plates, each of said tubes extending through a said smaller opening in one of said end plates and through a said smaller opening in the other of said end plates, said last two mentioned smaller openings being angularly displaced relative to each other about the yaxis of said drum, a tank having a body of heat exchange fluid therein, means supporting said drum for rotation about its raxis with said drum partially submerged in said body of iluid to a depth at which said smaller openings are sequentially submerged in said fluid upon rotation of said drum, and means for rotating said drum.

7. A heat exchanger for owable solids as dened in claim 6 including regulating means for controlling the flow of heat exchange-Huid lfrom the ends ofsaid tubes at'said other of saidend plates.

8. A heat exchanger for flowable solids as dened in claim 6 including scoop means mounted on the outer surface of said one vof said end plates adjacent each of the smaller openings therein for transferring heat exchange uid from said tank to said tubes.

9. A heat 'exchanger for flowable solids as defined in claim 8 including regulating means for controlling the rate of ow of uid from the ends of said tubes at said other of said end plates.

10. A heat exchanger for handling flowable solids comprising a horizontal drum having a feed end and a discharge end, a plate flatly mounted on each end of said drum, each of said end plates having a centrally located materials handling opening therethrough and an equal number of smaller openings disposed symmetrically about the central opening at a common radial distance from the drum, means for feeding flowable solids into said drum through the central opening in said end plate at the feed end of the drum, means for discharging said material through the central opening in said end plate at the discharge end of the drum, a plurality of tubes mounted within said drum and extending between said end plates, each of said tubes extending through a said smaller opening in one of said end plates and through a said smaller opening in the other of said end plates, said last two mentioned smaller openings being angularly displaced relative to each other about the axis of said drum, a tank having a body of heat exchange liuid therein, means supporting said drum for rotation about its axis with said drum submerged in said body of fluid to a depth at which said central openings are disposed above the surface of said body of iluid and said tube openings are sequentially submerged in said body of fluid upon rotation of said drum, and means for rotating said drum.

11. A heat exchanger for tiowable solids as defined in claim 10 including an internal conveying screw flight of at least one pitch mounted within said drum in supporting engagement with said tubes intermediate the ends thereof.

12. A heat exchanger for handling owable solids comprising a horizontal drum having an enlarged diameter central section, a hollow cylindrical materials feed section of reduced diameter at one end of said central section, a hollow cylindrical materials discharge section of reduced diameter at the opposite end of said drum, annular plates at each end of said central section ixedly securing said feed and said discharge sections to said central section in concentric relationship therewith, a plurality of tubes extending through said central section in symmetric relationship to the axis of said drum, each of said tubes having an inlet end projecting through the end plate at the discharge end of said drum and an outlet end projecting through the end plate at the feed end of said drumvat a location angularly displaced about the axis of said drum from its inlet end, a tank having a body of heat exchange iluid therein, means supporting said drum for rotation about its axis with said feed and said discharge sections located above the surface of said body of fluid and said central section partially submerged in said body of fluid to a depth at which the inlet ends of said tubes are sequentially submerged in said body of fluid upon rotation of said drum, and means for rotating said drum about its axis.

13. A heat exchanger for owable solids as defined in claim l2 including means for regulating the rate of ow of heat exchange duid from the outlet ends of said tubes.

14. A heat exchanger for :tlowable solids as detined in claim l2 including scoop means mounted on the outer surface of the plate at the discharge end of said drum adjacent each of the inlet ends of said tubes for transferring heat exchange fluid from said tank to said tubes.

l5. A heat exchanger for owable solids as defined in 7 claim 14 including regulating means for controlling the larly displaced by equal amounts in a leading direction rate of ow of fluid from the discharge ends of said with respect to the direction of rotation of said drum tubes. from the respective outlet ends of said tubes.

16. A heat exchanger for owable solids as defined in claim l5 wherein the respective ends of said tubes 5 References Cmd m the me of this patent are located at a common radial distance from the axis of FOREIGN PATENTS said drum, and said inlet ends of said tubes are angu- 151,461 Switzerland Mar. 1, 1932 lune,