US2190234A - Heat exchange apparatus - Google Patents

Description

Feb. 13, 1940- A. HAssELBAcl-l er Al. 2,190,234

HEAT EXCHANGE APPARATUS Filed May 2s, 1938 s sheets-sheet 1 Feb. 13, 1940. Al HASSELBACH ET AL 2,190,234

HEAT EXCHANGE APPARATUS Filed May 23, 1938 3 Sheets-Sheety 2 Feb. 13, 1940. l A. HAssELBAcH ET AL 2,190,234

HEAT EXCHANGE APPARATUS Filed May 25, 1958 3 Sheets-Sheet 5 UNITED STATES PATENT OFFICE HEAT EXCHANGE APPARATUS Alexander` Hasselbach, Fritz Luther, and Paul This invention relates heating and drying of or granular naturevwhile Hille, Dessau, Germany,

assignors to G. Polysins, Aktiengesellschaft, Dessau, Germany Application May 23, 1938, Serial No. 209,626 In Germany May 29, 1937 13 claims.

to apparatus for the materials of powdered in semi-liquid or pasty form, referred to for convenience as sludge, and is particularly applicable ment slurry. It is an object of the invention to provide apparatus of to the treatment of cethis character which is relatively simple and inexpensive to'construct.

which is largely automatic which will treat large in operation, and quantities of material rapidly'and effectively. In general the apparatus is similar to that illustrated in the granted June 4, 1935,-

to Hasselbach 2,003,649, and employs a number of prior patent the features illustrated in that patent together with other improvements and further novel features.

It is common practice to prepare raw materials 'such as cement in the form of a paste or slurry prior to their introduction into the kiln for calcining or other heat treatment, and it has been heretofore proposed cto introduction thereof into dry this slurry before the kiln, the material reaching the kiln in the form of small dry lumps,

grains, or powder in rea diness for the roasting or calcining process. When in the form of slurry, such raw material is not readily dried since it is essential that all portions of the material be adequately heated, usually by contact with hot gases, in order to effectively complete the drying. When large masses of raw material are to be dried rapidly, the pasty condition of the material retards the passage of heated gas therethrough and frequently results in the formation of large lumps which cannot be properly burned in the kiln.

It is therefore the pur pose of the present invention to provide an apparatus which will thoroughly agitate the r'aWf slurry or pasty mass `during the preliminary drying operation. It is a. feature of the invention that larger lumps of material formed during the drying operation are effectively broken up bef apparatus.

ore discharge from the rial on exposed' surfaces of the apparatus and for ensuring prompt discharge of the material therefrom.

In the preferred form of the invention, the

slurry or sludge is deposited upon a multiplieity of flexible elements suspended in a. drying chamber through .which hot gases arey passed,

the supporting means for thel flexible elements being intermittently mov ed in reverse directions to agitate the elements and thus ensure the breaking up and discharge of the material as it is dried. It is proposed as part of the instant invention to interrupt the movement of such supporting means for an appreciable period of 5 time on each reversal of movement, and to simultaneously.. interrupt the delivery of sludge to the flexible means for the purpose of materially improving the eiciency of the drying operation.

A further object of the invention is the provision of means for withdrawing dust from the hot gases vented from the drying apparatus and the return of such dust to the main body of the dried material.

A further object 'f the invention is the provision of means whereby drying apparatusof the type described, which is adapted to discharge the dried material into a kiln, may be readily rendered inoperative so that the sludge may be delivered directly to the kiln for burning without preliminary drying.

A further feature of the invention is the provision of means whereby the delivery of sludge to the apparatus may be eected in an efficient manner and the quantity of sludge thus delivered accurately controlled. l

Further objects and features of the invention will be apparent from the following description taken in connection with the accompanying drawings in which:

Figure 1 is a vertical sectional view illustrating one form of apparatus constructed in accord- Y ance-with the principles of the invention;

` Figure 2 is a diagrammatic view of mechanism 35 for automatically controlling the delivery of sludge to apparatus such as shown in Figure 1;

Figure 3 is an enlarged vertical sectional view of a portion of the apparatus shown in Figure 1;

Figure '4 illustrates a preferred form and ar- 40 rangement of the flexible elements shown in Fieures 1 and 3; A

Figure 5 is an enlarged view in elevation of a. detail of the slurry delivering device shown in Figures 1 and 3; 45

Figure 6 is an enlarged view, partly in section, of dust collecting apparatus shown in Figure 1;

Figure 'l is an enlarged detail view of one of the dust collecting elements shown in Figure 6:

and i Figure 8 is an enlarged sectional view of a portion of the structure shown in Figure 1.

.For convenience in describing lthe invention, reference is made herein to the several embodiments thereof illustrated in the drawings and specific language is employed. It will nevertheless be understood that no limitation of the invention is thereby intended, various alterations and modifications of the illustrated struccludes as itsvprincipal member a drying chamber `I`Il', within which are supported sludge-receiving yflexible elements II, the latter being carried on a support I2 which includes radiating arms and a hub portion secured to a shaft I4, the shaft being mounted in suitable bearings at the upper end of the chamber I0 for rotary or oscillatory movement in a manner hereinafter more particularly described. The sludge to be dried is received in a chamber Il and discharged from the lower end oi this chamber into a supply tank I8, such delivery being regulated by suitable control mechanism so as toV maintain ya constant level of. sludge in the tank.A From the tank I8 the sludge is introduced into the upper end of the chamber III by means including a supply pipe I9 disposed above the iiexible elements I I and arranged to eiect uniform delivery of the material thereto.

During the process of drying the material and as the result of agitation of the flexible elements II, the material moves downwardly along these elements and when completely dried and eilectively broken up, is discharged from the lower I of nthe kiln are directed upwardly through the chamber I0 into intimate contact with the material adhering to the iiexible elements I I, the gases being discharged from the upper end oi the chamber into a dust separating apparatus indicated generally at 23 and thence downwardly through a blower 24 into a settling chamber 25. 'I'he dust separated out in the chamber 23 is discharged downwardly through communicating conduits 26 and 21 and thus returned for admxture with the dried material discharged from the lower end of the chamber I0.

A suitable mechanism for regulating the depth of sludge in the supply tank I8 is shown in 'Figure 3, this mechanism including a pipe 29 having a valve 30 associated therewith, the valve being operable by a iloat 3| in such manner that a`l substantially constant. level of sludge is maintained within the tank I8. From the tank I8 the sludge ows into the supply pipe I9, the latter having a plurality of delivery nozzles 33 in the lower side thereof, the discharge of sludge through each nozzle being separately controllable by means of a threaded element 34, each of which is arranged to enter and throttle the orifice of the associated nozzle. The sludge discharged from each nozzle 33 passes through a pipe 35 disposed directly beneath the same, the lower ends of the several pipes 35 being so disposed that the sludge/is delivered with substantial uniformity on the flexible elements II and is thus distributed y'radially of the chamber I0.

It will be observed that the'exible elements II are disposed so ask to occupy and move within an annular portion of the chamber I0, the central portion of the chamber being occupied by a member 38 which is of generally cylindrical shape but preferably of somewhat larger diameter near pressed in another way, each chain secured to the aieoaa its lower end, the member 38 constituting a closed figure functioning as a baie to coniine the iiow of hot gases to the uter portion of the chamber I0. This arrangement promotes the eiciency of the drying operation by restricting the zone of contact between the hot gases and the sludge to that portion of the chamber in which adequate linear movement circumferentially of the Achamber may be imparted to the flexible elements by the rotation or oscillation of the support I2.

A preferred arrangement of the flexible elements is shown more particularly in Figures 3 and 4. 'Ihe flexible elements are here illustrated as metallic chains, a series of single chains being suspended at points spaced radially on each arm of the support I2. Each single chain is securedat its lower end to two further chains which depend therefrom, and each of these further chains supports two additional chains. Ex-

increases the efficiency of the apparatus, the more thoroughly dried and more iirmly adhering material near the lower end of the chamber being properly dislodged as the result of collision between a greater number ofiiexible elements. It

will be observed that the increased agitation at the lower end of the kiln is further promoted by the shape of the member 38, the flexible elements being confined within a smaller annular zone at the lower end of the chamber, so that collision therebetween is more frequent.

Various types ofjfmotion may be imparted to the support I2 forgthe purpose of agitating the chains. 'I'hus thef'support may be moved vertically, rotated or |osclllated about the vertical axis of the chamber I0, or subjected 'to a combination of these various types of movement. I prefer, however, to impart to the support an oscillatory movement, rotating the same iirst in one direction and then in the other, and interrupting the movement altogether on each reversal. Thus in one form of the apparatus which has proven quite satisfactory from a practical standpoint, the support is rotated in reverse directions at a speed oi 4 R..l P. M. through an angle of approximately 360, such rotary movement requiring about 15 seconds. Movement is then interrupted for a further period of 10 seconds, resulting in violent collision between the flexible elements, and the support is then rotated in the opposite direction for a period of 15 seconds, 50 seconds being required for the completion of one cycle of operation. 'It will be understood that these figures are given merely by way of example; the nature of the material, the moisture content and other 'conditions may require decided variation of this motor at 43 in Figure 2, is there shown as associated with suitable mechanism for correlating the operation of the motor and the control of the supply'of sludge to the drying chamber. Thus a reversing switch 45 may be associated with the field winding of the motor to reverse the direction of motor rotation, this switch being actuated by a lever 46 which isin turn operated by a cam track 48 formed in one face of a worm gear 49, a small constant speed motor 50 and associated worm 5l being employed to rotate the Worm gear. It will be observed that the cam track is provided with four distinct but connected portions, each portionV being concentric with the axis of rotation of the worm gear49. 'I'hus there is provided a portion of least radius, a portion of greatest radius, and connecting portions of equal and intermediate radius. When the lever 46 is engaged by either of the cam track portions of intermediate radius, the reversing switch occupies a neutral position and the motor 43 is not energized. When the lever 46 engages the portions of the cam trackof least and greatest radius the motor 43 will` be supplied with current and rotated in one direction or the other. This mechanism therefore provides for the reversal of rotation of the motor 43 and for the interruption of rotation of the motor intermediate the periods of reversed movement, and it is apparent that by varying the contour of the cam groove 48 the timing of the motor may be altered as desired.

A solenoid of which the winding is indicated at 53 is in series with the motor 43. quently when the motor is rotated, the solenoid' is energized and the armature 54 thereof is drawn upwardly. Secured to this armature is a member 55 which `is positioned to extend above a series of valve elements 56 which extend through suitably packed apertures in the upper side` of the supply pipe I9', each valve element 56 being arranged to cooperate with an aperture 5 1 in the lower side of this pipe in such manner as to interrupt the'supply of sludge through the aperture vwhen the valve is fully depressed. A coil s'pring 59 surrounds each valve to normally maintain the same free of the associated opening 51. It will thus be apparent that on cessation of operation of the motor 43, the solenoid 53 will be de-energized and the armature 54 and member 55 will fall, depressing the valves 56 and thereby interrupting the supply of sludge to the drying chamber. When motor operation is resumed, the member 55 will be raised and the valves will be displaced upwardly so that the sludge may be supplied to the drying chamber as hereinbefore described.

This interruption of the supply of sludge when the rotation of the chains is interrupted preliminary to reversal has been found quite important. Suspension -of introduction of sludge into the drying chamber during this period ensures that the sludge will not be sprayed downwardly between, rather than on, the chains; retention of the material in the chamber for a sumcient length of time for complete drying is thus assured and the introduction into the kiln of moist or incompletely dried material, tending to form large lumps or balls which cannot b'e uniformly calcined or burned, is avoided.

'Ihe material is discharged downwardly from the chamber Il! through a generally conical spout 60 which is supported for rotation about the axis of the chamber, the spout being ro- Consescraping devices 52 engage the inner face of the spout 60 -to remove material therefrom and prevent caking. From the lower end of the spout 60 the material is conducted downwardly p herence thereto of particles and lumps of dis--K` charging materials.

Associated with the housing 65 is a gate valve 13, disposed in a generally horizontal plane. When this gate valve is closed, the downward movement of material and the upward iiow of hot exhaust gases is of course interrupted, and l a by-pass conduit 15, controlled by a valve 16, conveys the gases from the 4housing 65 to the settling chamber 25. When the drier is thus rendered inoperative, the material may be introduced directly into the kiln, for example, through conduit 18 for discharge into the housing 65 and thence to the kiln.

The hot gases moving upward through the ilexible elements /ll are discharged from the upper end of the chamber I0 into the dust separating apparatus 23. This apparatus may comprise a chamber in which are suspended a plurality of flexible elements, for example chains 19, the latter being yieldably suspended from the upper portion of the chamber in the manner shown in Figure 7.A Thus in the arrangement shown in this figure, a group of chains are supported on a spindle -Which is normally urged upwardly by a coil spring 8|, the degree of compression of the coil spring being regulated by means of a nut 82 threaded on the spindle. By means of this construction the chains may be readily depressed and agitated, the operation being carried out either manually or automatically, for the purpose of shaking collected dust from the same. The dust thus collected and discharged falls downwardly through the conduits 26 and 21 into the housing 65 and mixed with the dried material falling from the chamber l0. Dampers 85 are located beneath the chains 19 to control the downward m'ovement of the gases, and discharge of the gases from the dust removing chamber is controlled by means of dampers 86 disposed intermediate the chamber and ,the blower 24.

Having thus described theinvention, what is claimed as new and desired to be secured by Letters Patent is:

' 1. I n apparatus for drying sludge, the combination with a chamber, ilexible carrier elements suspended in said chamber, means for depositing sludge on said elements, mechanism intermittently agitating said elements to dislodge the sludge therefrom, and means automatically operable in timed relation with said mechanism for periodically interrupting the operation of said first named means to suspend the depositing of sludge on said elements during cessation of agitation of the latter. Y

2. In apparatus for drying sludge, the combination with a chamber, means for causing hot gases to flow through said chamber, flexible means suspended in saidchamber, means for depositing sludge on said exible means, and mechanism for imparting to said ilexible means intermittent rotationin reverse directions circumferentially of said chamber with a dwell between successive movements.

3. In apparatus for sludge, the combination with a chamber, means for causing hot gases to ow through said chamber, flexible means suspended in said chamber, means for depositing sludge on said exible means, and mechanism for imparting to said exible means intermittent rotation in reverse directions circumferentially of said chamber with a dwell between successive movements, said flexible means including a plurality of chains supported at points spaced radially and circumferentially of said chamber.

4. In apparatus for drying sludge, the combination with a chamber; means for causing hot gases toV ilow through said chamber, flexible means suspended in said chamber, means for depositing sludge on said exible means, mechanism for imparting to said ilexible means intermittent rotation in reverse directions circumferentially of said chamber, and means automatically operable to interrupt the delivery of sludge to said exible means during periods intermediate the rotation of the latter.

5. In apparatus for drying sludge, the combination with a chamber, means for causing hot gases to flow through said chamber, exible means suspended in said chamber, means for depositing sludge on said ilexible means, and mechanism for imparting to said ilexible means -intermittent rotation in reverse directions circumferentially of said chamber with a dwell between successive movements, lsaid last named means being operative to d -lli/er sludge to said ilexible means only when th y ,are being rotated.

6. In apparatus for dryingsludge, the combination with a chamber, exible carrier elements suspended in said chamber, means for depositing sludge on said elements, mechanism intermittently agitating said elements to Adislodge the sludge therefrom, and means associated with said chamber and affording a discharge passage for the dislodged sludge, said means including a movable wall in said passage, and means for agitating said wall to prevent adherence of sludge thereto.

7. In apparatus for drying sludge, the combination with a chamber, iiexible carrier elements suspended in said chamber, means for 'depositing sludge on said elements, mechanism intermittently agitating said elementsto dislodge the sludge therefrom, means associated with the lower end of said chamber and aording a downwardly tapered passage for discharge of dried material, and scraping means associated with said passage for preventing deposit and adherence of material therein.

8. In apparatus for drying sludge, the combination with a'vertical chamber, of means for causing hot gases to ow through said chamber, means for introducing sludge into the upper portion of said chamber, a plurality of exible elements suspended in said chamber in spaced relation, and means for agitating said elements to cause the latter to collide for discharging the dried material therefrom, the number of ilexible elements in the lower portion of the chamber being greater than the number in the upper portion thereof.

9. In apparatus for drying sludge, the combination with 'a vertical chamber, of means for .causing hot gases to flow through said chamberfmeans for introducing sludge into the upper portion of said chamber, a plurality of iiexible elements suspended in said chamber in spaced relation', and means for agitating said elements to cause the latter to collide for discharging the dried material therefrom, said exible elements comprising chains having additional chains secured thereto at points intermediate the ends thereof.

10. In apparatus for drying sludge, the combination with a chamber, means for causing hot gases to ow through said chamber, exible means suspended in said chamber. means for l depositing sludge on said exible means, mechanism for imparting to said flexible means intermittent rotation in reverse directions circumferentially of said chamber with a. dwell between successive movements, means for iiltering dust from the gases vented from said chamber, and

' means for effecting admixture of dust thus ltered with dried material discharged from said chamber.

11. In apparatus for drying and burning cement slurry, the combination with a kiln, of means associated with said kiln for drying the slurry and delivering the dried material to the kiln, said. means including a drying chamber, means causing hot gases from the kiln to ow through said chamber, means for delivering slurry to said chamber and retarding the iiow of slurry therethrough, dried material cut-01T means operable to isolate said chamber from said kiln, and separate means for supplying ma terial to said kiln and venting hot gases therefrom when said chamber is thus isolated.

12. In apparatus for drying cement slurry prior to the introduction thereof into a kiln, the combination with a vertical chamber through which hot gases are caused to ilow, of elongated flexible elements depending within said chamber adjacent the chamber walls and supported at Ythe upper ends thereof only, the number of such elements being greater in the lower portion than in the upper portion of said chamber, means for depositing slurry uponsaid elements, means for agitating said elements to dislodge the slurry therefrom when dried, said last named means comprising a rotating support for said elements, and means for directing and confining the hot gases in an upward path in the direction of the chains through the whole cross-sectional area of the chamber, said last named means comprising a baille within said chamber for deilecting the gases toward the chamber walls.

13. In apparatus for drying cement slurry prior to the introduction thereof into a kiln, the combination with a vertical chamber through which hot gases are caused to flow, of elongated ilexible elements depending Within said chamber adjacent the chamber walls and supported at the upper ends thereof only, means for depositing slurry upon said elements, means for agitating said elements to dislodge the slurry therefrom when dried, said last named means comprising a rotating support for said elements and means for intermittently rotating said support in opposite directions with a period of dwell between successive movements, and means for dlrecting and confining the hot gases in an upward path in the direction of the chains through the whole cross-sectional area of the chamber, said last named means comprising a baille within said chamber for deflecting the gases toward the chamber walls, said baille being carried by said rotating support.

ALEXANDER HASSELBACH. FRITZ LUTHER. PAUL HILLE.

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