US3264751A

US3264751A - Heat-exchange method and apparatus

Info

Publication number: US3264751A
Application number: US495580A
Authority: US
Inventors: Frank J Mcentee Jr
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-07-11
Filing date: 1965-10-13
Publication date: 1966-08-09
Anticipated expiration: 1983-08-09
Also published as: GB934521A; GB934522A; US3253650A; CH381591A; CH401796A; BE605956A; DE1240373B; DE1401684A1

Description

Aug. 9, 1966 F. J. M ENTEE, JR

HEAT-EXCHANGE METHOD AND APPARATUS Original Filed July 11. 1960 5 Sheets-Sheet 1 .FIG.!

INVENTOR. FRANK J. McENTEE JR.

0 FZ M. 1.4;(6'1' arm/1 a A all) ATTORNEYS 9, 1966 F. J. M ENTEE, JR

HEAT-EXCHANGE METHOD AND APPARATUS 5 Sheets-Sheet 2 Original Filed July 11. 1960 FIG.6

FIG.2

.FIG. IO

ATTORNEYS F. J. M ENTEE, JR 3,264,751

HEAT-EXCHANGE METHOD AND APPARATUS Aug. 9, 1966 Original Filed July 11. 1960 5 Sheets-Sheet 3 INVENTOR. FRANK J. MCENTEE JR.

4 ATTORNEYS Aug. 9, 1966 F. J. M ENTEE, JR

HEAT-EXCHANGE METHOD AND APPARATUS Original Filed July 11. 1960 5 Sheets-Sheet 4 SEPARATOE FINISHED PRODUCT COOLER mum-1s COOLED mums Q,

MLL

FIG.9

' INVENTOR.

FRANK J. McENTEE JR.

ATTORNEYS 9, 1966 F. J. M ENTEE, JR 326,71

HEAT-EXCHANGE METHOD AND APPARATUS Original Filed July 11. 1960 5 Sheets-Sheet 5 INVENTOR. FRA NK J. McENTEE JR.

ATTORNEYS United States Patent 3,264,751 HEAT-EXCHANGE METHOD AND APPARATUS I Frank J. McEntee, IL, 1106 Hillcrest Road,

Beverly Hills, Calif.

Original application July 11, 1960, Ser. No. 41,967. Divided and this application Oct. 13, 1965, Ser. No. 495,580

Claims. (Cl. 34-57) This application is a division of my copending application Serial No. 41,967 filed July 11, 1960 which is a continuation-in-part of my application Serial No. 628,637, filed December 17, 1956, now Patent No. 2,953,365.

The present invention relates to heat exchange with pulverulent or granular materials, and is more particularly concerned with the cooling of such materials in fluidized beds.

The heating and cooling of pulverulent or granular materials in fluidized beds have been complicated by several problems including short-circuiting of hot material through the cooler to the outlet or discharge; uneven or erratic fluidization because of interference or obstruction of the fluidizing air flow by heat exchange surfaces or elements embedded in the fluidized bed; blockages caused by accumulations or oversize materials; and coating of the material on the heat-exchange surfaces.

Prior fluidized heat exchangers have employed arrangements and combinations of overflow and underflow weirs within horizontally elongated chambers, vertically elongated chambers, and various types of heat-exchange surfaces such as hollow tubes. However, none of the prior arrangements has been found entirely satisfactory.

The present invention provides a method and apparatus for heat exchange in a fluidized bed in which the heattransfer surfaces are maintained in a clean, uncoated condition by the motion of the material therealoug which may be regulated to compensate for variations in operating conditions.

In general, the preferred form of apparatus of the present invention comprises an elongated, preferably upright casing having a material inlet and a material outlet spaced from each other a substantial distance. The material with respect to which heat transfer is to be effected is maintained in a fluidized state in the casing. Between the inlet and the outlet, and in the space occupied by the fluidized material, the casing is provided with a plurality of heat-transfer members having extensive heat-transfer surfaces, such as fins. The heat-transfer members occupy a large portion of the volume and cross-sectional area of the casing, and extend substantially longitudinally between the inlet and outlet. Means are provided for maintaining a relatively high velocity of the material along the heat-transfer surfaces to prevent coating or build-up of material thereon.

A better understanding of the invention may be derived from the accompanying drawings and description in which:

FIG. 1 is a vertical sectional view of a fluidized cooler embodying the preferred form of the invention;

FIG. 2 is an enlarged horizontal sectional view of a portion of the cooler, taken along lines 22 of FIG. 1;

FIG. 3 is an enlarged horizontal cross-sectional view of a heat-exchange member;

FIG. 4 is a vertical sectional view of the lower portion of one of the heat-exchange members, taken on line 4-4 of FIG. 3;

FIG. 5 is a vertical sectional view of the discharge conduit of the fluidized cooler of FIG. 1;

FIG. 6 is a horizontal sectional view taken on line 6-6 of FIG. 5;

FIG. 7 is a schematic view of a preferred installation embodying the cooler;

m ce

FIG. 8 is a cross-sectional view of the lower end of a modified form of heat-transfer member;

FIG. 9 is a vertical sectional view taken on the lines 99 of FIG. 8;

FIG. 10 is a vertical sectional view of the upper end of the heat-transfer member of FIG. 8 and its associated parts;

FIG. 11 is a vertical sectional view of a modified form of a cooler embodying the invention;

FIG. 12 is a vertical sectional view of a further modified form of cooler embodying the invention;

FIG. 13 is a horizontal sectional view taken on lines 13-13 of FIG. 12;

FIG. 14 is a vertical sectional view of a modified form of cooler embodying the invention using a gaseous heattransfer fluid;

FIG. 15 is a horizontal sectional view taken along lines 1515 of FIG. 14; and

FIG. 16 is an enlarged view of a portion of one of the aerating pipes of FIG. 1.5.

As shown in FIGS. 1 to 7, the preferred form of the invention, as embodied in a fluidized cooler for hydraulic cement, comprises a cooler C in closed circuit with an air-swept finish mill M and an air-swept separator S. It is to be understood that any type mill or separator may be used in the circuit. The fluidized cooler comprises a vertically elongated vessel or casing 1 which may be of any suitable cross-sectional shape, and which is shown here in the preferred form of a cylinder. The casing 1 has a material inlet 2. at its upper end and a material outlet 3 in its lower region. Adjacent the material outlet 3 is a gas-permeable deck 4 which forms a floor in the casing and slopes downwardly towards the outlet. The gas-permeable deck preferably is formed of filter stones or similar heat-resistant material or, if temperature permits, may comprise a tightly woven fabric. The permeability of the deck is preferably as uniform as possible throughout its full area. The deck 4 is spaced from the bottom wall 5 of the casing to provide a plenum chamber 6 therebetween. An air or gas inlet 7 is provided in the bottom wall 5 for introducting fluidizing air or gas under pressure into the plenum chamber 6 to pass upwardly through the gas-permeable deck 4 to fiuidize overlying material. Air separating from the upper surface of the material is discharged through a vent 8 in the upper region of the casing.

A distributing cone 9 is arranged beneath the inlet 2 to spread and to form the incoming hot material into an annular, downwardly-flowing stream. Air rising beneath the distributor 9 passes outwardly through and agitates the annular stream of material as it falls off the outer edge of the distributor and onto the bed of material in the vessel. A disc 14) at the apex of the distributor 9 slightly chokes or retards the flow of material through the inlet 2 and aids in distributing the material.

A plurality of heat-transfer members extend downwardly from the top wall 12 of the casing lin a substantially symmetrical arrangement, preferably in concentric series arrangement, with respect to the cross-sectional area of the casing and in a number sufficient to provide a relatively small cross-sectional area open between the heattransfer members for flow of material through the casing. Each heat-transfer member 11 includes a pair of concentrically arranged inner and outer pipes 13 and 14 (FIGS. 3 and 4) respectively, both of which extend through the top wall 12. The outer pipe 14 is provided with a plurality of outwardly-extending, radial, heat-conducting fins 15. The fins 15 extend vertically of the pipe 14 from its lower end to a position slightly below the top wall 12 of the vessel 1. A closure member 16 in the form of a downwardly-pointing cone is provided for the lower end of each outer pipe 14. The cone 16 serves to distribute the air flow evenly around the surface of the members 11 to prevent short-circuiting of portions of the air. along.

one side of the members.

The inner pipes 13 of the heat-transfer members 11 terminate short of the lowerends of the outer pipes 14 and are provided ,with a pair of legs 17,'as best seen in FIG.'4, which maintain -a gap 18 between the lower end of the inner pipe 13 and the upper portion of the closure cone16. The legs 17 also function as spacers to maintain 1

pipes

13 and 14. At their upper ends, the inner pipes 13 the concentric relationship between the innerand outer.

extend through end walls or caps 19 of the outer pipes.

14 to provide means for the introduction of a heat- 1 exchange medium.

The lower ends of the heat-transfer members 11 may another, by suitable bracing, if desired.

'15 be secured in proper spaced position with respectto one The various heat-transfer members may be connected t in series or in parallel, as desired, for the flow of a heattransfer medium through them. As shown in FIG. 1, the heat-transfer members are connected together in groups to provide series flow of the heat-transfer medium through each group of the members. To this end, the outer pipes- 14 of adjacent pairs of heat-transfer members are con- 7 nected by pipes 21, and the inner pipes 13 of the adjacent members of adjacent pairs are connected to each other-by an inverted U-shaped section 13a. connected, heat-exchange medium supplied through the in- With the pipes: thus let pipes 13 will first pass downwardly through the inner,

pipes to the bottom of the heat-exchangers to which the: pipes are connectedand through the gap 18 into the outer.

pipes 14; The heat-exchange medium then flows upwardly through. the. outer pipes and is discharged through the connections 21 into the outer pipe 14 of a second heat exchanger. wardly through the outer pipe 14 and upwardly through the inner pipe to be discharged at the upper end there-. r

In the second heat exchanger, it fl-ows down of intoone of the inverted U-shaped sections 13 from which it passes to the inner pipe of a third .heat-.ex-. r

changer. change medium is discharged through the pipe 13b.

The material outlet 3 communicates with the lower. end of a discharge conduit 22. The dischargeconduit includes a lower leg 23 extending outwardly and upwardly from the outlet 3 to the lower end of a vertically-ex tending leg 24 which discharges at its upper end into I an overflow leg 25. The vertical leg 24 andthe overflow leg 25 may be separate conduits, or, as shown inFIGSi 5 This series flow continues until the. heat-exand 6, may becompa-rtmentsof a single discharge conoverflow edge 24a to correspondingly alter the levelof the material in the vessel 1. T-o this end, the common wall between the vertical leg 24 and the discharge leg 25 comprises. a series of replaceable or removable loose plates'24c. and a sliding plate or weir 24d having the over: flow edge 24a'which may be adjusted vertically by a handle 24a. The handle 2412, may be held in its adjusted position by any suitable means. The plates 24c and the plate or weir 24d are held in place by guides 24f securedtothe inside of opposite walls of the conduit. By. removing or adding plates 24c or by replacing larger plates with smaller plates or vice versa and by the use of the sliding plate or weir 24d, the overflow edge 24a may be positioned at any. desired level.

Instead of the means just described for adjusting the level, of the overflow edge 24a, any other means maybe provided for raising or lowering of such edge.

Adjacent the material outlet 3, the lower. leg '23 of the discharge conduit 22 is provided with a sump 26 which is opento the interior of the leg 23 and is closedyto the atmosphereby avalve 27:.; The@ valve 27 may be opened periodically to drain'ofli. accumulations of oversize material, lurnps, or foreign objects.

Adjacent the leg ;24, t'he :lower wall of the lower leg23is provided with an aerator; '28.which.underlies the vertical leg 24 to deliver; aerating airupwardly therethrough. The .air passing upwardly through. the conduit 22 escapes through asuitable vent 29 -in theupper. endv thereof.

As best shown in FIG. 7, the cooler, C receives materialthrough. its inlet 2- from the coarsetailings outlet 31 of the air-swept separator S, anddischarges thetailings after being cooled throughits outlet 3 and discharge con: duit 22 tothe inlet. of the .air-swept mill M,'such as a cement finish mill.

The material discharged from'the mill is passed to the.

inlet 32 of the separators. Under thezeinfluenceof an air impeller (not: shown), which may be an integral part of the separator, the separator classifies, the material into coarse and fine fractions and discharges the air through an air. outlet 33; the coarse tailings through the outlet31, and the desired fine fraction of finished product through a productoutlet 34. Where desired, the finished .cemeent productsdischarged through the outlet:34;.rnay..be passed. to a second cooler prior to use or storage.

Inoperation of the apparatus of FIGS.- 1 to 8 for the cooling .of hydraulic cement, the mill M, separator S and the fluidizing'ainflow tothe cooler C are started and a feed of cement clinker is 'delivered to the mill-from stor-- age or from a primary clinkercrusher (not shown). for grinding. The grinding. of the cement clinker develops considerable heat which subsequently must be removed Itis generally accepted theory that the greater portion of the horsepower suppliedto a milliof the type commonly used .for finished grinding ofxcementtisilost inthe form of heat developed by abrasion and impact.

The hot cement passes from the discharge end of the mill M to the: separator; S and from the separator to the cooler C. This operation is continued until the temperature of thematerial inthe cooler is above the dew. point of the .flu'idiz'ing air. in order to avoid condensation of moisture on the surface of the heat-transfer members 11. When this condition is reached, the flow of thecooling medium, preferably water, through the heat-transfer members 11 is started.

The hot tailings which leave the separator at a temperature. of the order of F. to 300 F., for example,pass

through the inlet 2 of the cooler'and onto the'disc 10. The

free flow of the hot tailings in the. cooler is checked by the disc 10, :which prevents any uneven flow, or excessive .fiow along one side of the inlet; pipe from continuingwithin thevcoole'r; The material feeds off the edge of the disc 10 and'beneath the circular lower edge of the inlet 2 as anxannulanstream onto the distributing cone 9; and

from the lower edge of the distributing cone downward.

ly onto the main body of fluidized cement-in the cooler.

The cement which exhibits pseudo-hydrostatic properties similar to those of a liquid tendsto seek an equilibrium pointpor in" other words, a constantlevel. Therefore, a portion of the fluidized bed will flow through the outlet 3 and upwardly into the vertical leg 24 of the discharge conduit. The air supply to the aerator 28 is regulated to cause .fluidization of the material, thereabove in =the'leg.

24 to. an extent to produce a lower:density of the fluidized mass therein such that the-*head-orhydrostatic pressure of the fluidized mass inthe vesselwill cause the less dense fluidized material at the leg 24 to rise and to overflow into the leg 25 from which it is discharged.

In .normal operatiomas long :as the supply of air to the aerator is continued, cement is discharged from the'bed." Therefore, the new cement distributed ,by the cone. onto the upper surface of .the ,fluidized bedyis fluidized andmixed with the 'bed and passes downwardly in-the vessel 1 as a part of the fluidized bed. As the cement passes downwardly through the cooler, the constant agitation of the cement resulting from the fluidization of the bed causes an eflicient heat transfer between the cement and the heat-transfer members 11, since the individual particles of the cement are caused to contact different areas of the heat-transfer members. Preferably the rate of cement fed to the casing 1 is so correlated with the rate at which the cement is discharged through the outlet 3 that the flow of the fluidize-d cement through the cooler is maintained at a velocity of about three feet per minute. For materials which are moisture-sensitive and which tend to coat on the heat-transfer surfaces, velocities down to about one foot per minute may be satisfactory. However, in some instances even higher or lower velocities may be satisfactory.

Although it is to be understood that the cooler of the present invention is equipped for use in different circuits, such as a direct cooling of the finished cement product, closed circuit cooling of the mill discharge enroute to the separator or of the tailings from the separator while they are enroute back to the mill is preferred in many cases. When the cooler is located in either of these positions, within a closed circuit, it receives a substantial material flow, commonly called the circulating load, which may be, in terms of weight per hour, from one to eight times the output of finished product from the mill circuit. This substantial load of material makes possible a relatively high velocity of material flow along the heat-transfer surfaces, particularly since the number and size of the heat-transfer members restrict the area within the casing through which the materials may flow. Nevertheless, a large bulk of cooled material is maintained in the circuit, within which bulk the heat developed in the mill may be distributed and dissipated.

When operating in a closed circuit and it is desired to change the particle size of the feed to the mill, say from one-fourth inch to three-eighth inch or one-half inch,

- there will be a higher proportion of rejects from the separator to be passed to the cooler. Under such conditions, if the level of the overflow edge 24a remains the same, there will be a gradual building up of the amount of the material in the cooler, which, if not corrected, may result in a condition in which the entire system will become plugged. To avoid this, the overflow edge 24a will be lowered to the extent necessary to maintain the desired level of the fluidized material in the vessel 1.

In the production of hydraulic cement, the desired cooling result is expressed in terms of the temperature of the finished cement. Since the amount of heat produced by a mill is relatively constant for a given rate of output of finished cement, the high circulating load of partiallycooled material being returned to the mill inlet causes the total heat input of the mill to :be distributed over a large mass of material, thereby causing a lower actual rise in temperature of that material than would occur with a lesser mass of returned or recycled material. Therefore, when the cooler of the present invention is employed in either of the preferred locations in the circuit, it is not necessary to cool the large circulating load to a very low temperature, since only the extraction of total heat therefrom, in terms of B.t.u.s, is required to provide for absorption of the mill heat by the large mass. Thus a lower temperature differential may be maintained between the material and the cooling medium while still producing the required result. At the same time, reduction of the temperature of the material in the mill prevents coating of the balls or other grinding media by the mate-rial and, in the case of hydraulic cement, prevents the false setting found in overheated material.

The modified form of heat-transfer member shown in FIGS. 8 to 10 comprises only a single pipe 14' having longitudinal and radially-extending heat-conducting fins 15 on its outer surface. A transverse partition 36 divides the interior of the pipe 14 into a pair of

channels

37 and 38 and extends from the top endwall or cap 19' of the pipe (FIG. 10) to a point spaced from the lower endwall 39 (FIG. 9) to form a gap 18 therebetween for the flow of the heat-transfer medium. At its upper end above the top wall 12 of the casing, the pipe 14 is connected to an inlet pipe 41 communicating with the channel 37 and an outlet pipe 42 communicating with the channel 38. The heat-transfer members 14' may be operated in parallel, or may be connected to operate in series arrangement.

In operation, cooling fluid is delivered through the inlet pipe 41 into the channel 37 and passes downwardly therethrough to its lower end. The cooling fluid then passes through the gap 18 beneath the partition 36 and upwardly through the channel 38 to the outlet pipe 42.

The modified form of cooler shown in FIG. 11 comprises a casing 1a having a material inlet 2a in its top wall 12a and a material outlet 3a located at opposite sides. A gas-permeable deck 4:: extends across the lower region of the casing, and, together with the bottom wall 5a of the casing, forms a plenum chamber 6a. Air or gas is supplied to the plenum chamber via a gas inlet 7a to pass upwardly through the gas-permeable deck 4a to fluidize pulverulent material in the casing. A suitable vent 8a extending from the top wall 12a discharges the gas escaping from the fluidized material from the casing. A plurality of heat-transfer members 11a are arranged within the casing in an arrangement similar to those of FIG. 1.

A material-inlet pipe or tube 45 extends downwardly from the material inlet, and at its lower end terminates at a point spaced from the gas-permeable deck 4a to form an annular distributing orifice 46 through which the material is discharged into the casing. The lower end of the tube 45 is constricted by an inverted frusto-conical section 47 which chokes or restricts material within the pipe to facilitate uniform feeding thereof outwardly through the annular orifice 46 from the casing.

In operation of the apparatus of FIG. 11,, the flow of fluidizing gas upwardly through the gas-permeable deck 4a is started. The flow of cooling fluid through the heattransfer members 11a is started either before or after starting the flow of material through the casing, as desired.

The material passing downwardly through the inlet tube 45 is partially retarded by the restricting frusto-conical section 47, thereby stabilizing the material flow and preventing any short-circuiting along a side of the tube. The material is thereby metered through the annular orifice 46 into the free space within the casing. The material in the casing is fluidized and, as additional material is fed to the casing, it is displaced upwardly along the heat-transfer members 11a until it ultimately overflows through the material outlets 3a and is discharged from the casing.

The modified form of cooler shown in FIGS. 12 and 13 comprises a casing 112 having a material inlet 2b and a material outlet 3b and a plurality of heat-transfer members 11b similar to those of FIGS. 1 and 11. A material inlet chamber 50 mounted on the top wall 12b communicates with the inlet 217, through a collar or neck element 50. Material to be introduced to the casing is fed to the inlet chamber through a pipe 5011. A gas-permeable deck 4b extends across the lower portion of the casing and is spaced from the bottom wall 5b thereof to form a series of plenum chambers, as hereinafter described.

The gas-permeable deck slopes downwardly from adjacent the periphery of the casing to a lower level 51 adjacent the center of the casing. A circular wall 52 closes the space between the bottom wall 5b and the underside of the lower level 51 of the deck to form a central plenum chamber 53. Four radially-extending

walls

54, 55, 56 and 57 divide the space between the gas-permeable deck 4b and the bottom wall of the casing and surrounding the central plenum chamber 53 into four quadrants or

outer plenum chambers

58, 59, 60 and 61 of sector shape. The

50 and into a separating chamber 68 having an air vent,

At the point at which it passes through the material inlet 2b, the gas-lift pipe-67 and the collar or neck 50" form an-annular space 72 through which material islfed from the inlet chamber 50 onto the distributing cone 9b.

In operation of the apparatus of FIGS. 12 and 135a flow of fluidizing gas upwardly through the gas-permeable deck is started and maintained as describedmore fully hereinafter. The flow of cooling fluid through the heat-transfer member 111) is started either before or after starting the flow of material through the casing, as desired.

The=flowof material into the inlet chamber 50 :is-par-- tially retarded by the size of the annular aperture 72 and by the cone 9b',thereby stabilizingthe material flow and,

preventing short-circuiting of the material along one side of-either the aperture 72 :or thecasing. The material@ passes as an annular stream through the annular. aperture 72, and is thereafter evenly distributed by the cone 9b. over the upper surface of the bed of fluidizedmaterial in the casing.

Air 'or gas is delivered through'the central plenum chamber 53 and the lower deck area 51 and through the nozzle. pipe 71. The material abovethe lower deck area 51 is fluidized by the air passing upwardly there-: through and rises in the gas-lift pipe 67 where it tends to seek an equilibriumv point or stable level. The air entering the lift pipe 67 from the nozzle 71 further aerates,- expands and reduces the density of this materialinthe lift pipe; The head of the material bed in the casing around the gas-lift pipe forces additional materialinto the lower end of the lift pipe and causes the less dense material therein to move upward into the separating chamber 68. In the separating chamber 68 theair separates from the, pulverulent material .and escapes through the vent 69, whilethe material is discharged by'gravi-ty or by other means through the discharge pipe 68'.

Assuming a substantially constant feed of material into the upper end of the vessel 1b, the level of the. material within the vessel can be controlled by the amount of gas introduced through. the nozzle pipe 71". Increasing the amount of gas introduced through the nozzle pipe 71 into the lift pipe lowers the density of the fluidized material in the lift pipe and increases the density differential bet-ween the fluidized material inthe gas-lift pipe and in the main vessel surrounding the lift pipe.-

This results in a greater flow of material upwardly through.

the lift pipe and a corresponding lowering of'the. level of the material in the vessel. reduction of the amount of air introduced through the nozzle pipe 71 will result'in an increased density of the fluidized material in thelift pipe and a decrease in thedensity differential between the fluidized materialin the= gas-liftz=pipe and in the vessel surrounding it. This will result in a lesser flow of the fluidized material upwardly through the gas-lift pipe and a corresponding raising of the level of the fluidizedmaterial in the vessel.

The rate of air flow, or the amount of air or gas per rninute'per square foot of the gas-permeable deck ineach of the

sectors

58, 59, 60 and 61 may be regulated- In a similar manner, a

by suitable valving ,(not shown) .to control the rate .of flow through the

gas inlets

62, 63,, 64. and 65,respectively. The! rate of flow through'each of the sectors may be equal, or may be consistently non-uniform, with the higher air: flowbeing cycled .or periodically shifted to different sectors as more fully described in Patent No. 2,844,361, issued July 22, i1958,5to Dilcher et al.

This control iover the aeration of different ,zones of the material bed permits regulation of material density and material velocity in-the various zones. Therefore, when problems such as a local zoneof'idense or agglomerated material occur, the air flow may be temporarily set to createa high state of material turbulence, or a high material velocity in the desired zone. Although the tern-j porary turbulence or-high velocity may not be the most. efficient; in terms of heat transfer, it maybe used for perodic clearing of. the heat-transfer members or breakdown of dense material areas. After: the. heat-transfer members of one section have, been :cleared by high'aeration,rthat. section may be returned to the rate of air fiow desired for effective heat transfer, and another. sector may receive the higher air flow.

As shown in FIGS; 14 t0/16, a modified embodiment of the invention, which; is? particularly advantageous for use with a gaseous heat-transfer medium, comprises a'casing; 10 having a material inlet 2c. in its lower region anda material outlet 3c in its upper, region. A screw feeder Y75 :and a startfeeders. 76 control the .flow of ma-. terial through :the inlet 2c and;out1etx3c,- respectively. When the unit is to be used for zcoolingextremely hot pulverulent materialsyor where desired.for any reason, a layer of insulation 74 is provided about :the casing A plurality of heat-transfer members 11:0 extend through the. casing longitudinally thereof, and are commonly connected at their opposite ends to an upper; supply chamber 77' and a lower collecting chamber 78. The heat transfer members-11c comprise open pipes having a plurality. of longitudinally-extending fins 15c extending radially terconnecting, pipes 82. The aeration .pipes are uniformly perforated with apertures 89 on their; lower sides or :in any suitable? manner to deliver :air or.;gas into the .surrounding material. Preferably, the=fins are notched or ,intem'upted as at1'83 to ,permit positioning of the aeration pipes; close. to the heat-transfer pipes 140E i The groups of

aeration pipes

79, 80 and 81 Lreceive air or gas individually throughpiping andvalves 84, 85 t and 86, respectively, from a.sourcei (not shown). The spent air or-gas is ventedfrom the casing by'a cyclone vent87 which removes stray dust fromythe gasesand.

returns it to the material-bed through a dip leg88.

In operation of theapparatus ofFIGS. 14 to 1 6, mate-v rial is delivered into the casing by I the screw feeder:

75', and is ultimately removed at thev top of the bed by.

tionzat the different vertical zones, mayberegulatedby the

valves

84, 85 and 86. I t

A gaseous heat: transfer mediurn'such as coldair is passed into the supply chamber 77 and through .the heattransfermembers-llc and ,is withdrawn from the collect- Alternatively, if desired, the gaseous: medium may follow an opposite path upwardly through ing chamber :78.

the heat-transfer members; Also, liquid. heat-exchange 9 media may be used in the apparatus of FIGS. 14 to 16, if desired.

Various changes may be made in the details of construction of the several forms of heat-exchangers herein described without departing from the invention as define-d in the subjoined claims or sacrificing any of the advantages thereof.

I claim:

1. A heat-exchange apparatus for treating pulverulent material comprising a vessel to receive the pulverulent material, the portion of the vessel which receives the material and in which the material is treated having an inlet opening located at the top of the vessel for the introduction of the material to be treated and an outlet conduit extending upwardly through the vessel from a portion adjacent but spaced from the bottom of the vessel, the lower end of said conduit being open and forming the discharge from the portion of the vessel in which the material is to be treated, said conduit having an opening adjacent its upper end for the discharge of material, a nozzle pipe having an opening positioned to direct gas passing therethrough upwardly through said conduit to facilitate upward flow of material through said conduit, means adjacent the botom of the vessel for introducing a fluidized gas to pass upwardly throughthe material in the vessel to fluidize it, a plurality of heat exchangers within said vessel, said heat exchangers being spaced from the walls of the vessel and from one another to provide spaces for the material being treated, and means for causing a flow of heat-exchange medium through said heat exchangers.

2. Heat-exchange apparatus as set forth in claim -1,

10 which includes a material-inlet chamber above the vessel and surrounding the upper portion of said conduit below the inlet opening for the discharge of material, means for supplying material to said material-inlet chamber and a collar surrounding and spaced from said conduit, the upper end of the collar communicating with said materialinlet chamber and the lower end communicating with the vessel and forming the inlet for the material to the vessel.

3. Heat-exchange apparatus as set forth in claim 1 wherein a separation chamber is positioned above said vessel and communicates with said discharge opening, the separation chamber having a vent in the upper portion thereof for the escape of gas separating from material in the chamber and a material discharge communicating with and leading away from the separation chamber.

4. Heat-exchange apparatus as set forth in claim 1 wherein each heat exchanger carries a plurality of elongated, outward-ly extending, radial, heat-conducting fins.

5. Heatexchange apparatus as set forth in claim 1 having a distributing member positioned below the inlet opening of the vessel to cause incoming material to be spread out over a larger area within said vessel.

References Cited by the Examiner UNITED STATES PATENTS FREDERICK L. MA'ITESON, JR., Primary Examiner.

D. A. TAMBURRO, Assistant Examiner.

Claims

1. A HEAT-EXCHANGE APPARATUS FOR TREATING PULVERULENT MATERIAL COMPRISING A VESSEL TO RECEIVE THE PULVERULENT MATERIAL, THE PORTION OF THE VESSEL WHICH RECEIVES THE MATERIAL AND IN WHICH THE MATERIAL IS TREATED HAVING AN INLET OPENING LOCATED AT THE TOP OF THE VESSEL FOR THE INTRODUCTION OF THE MATERIAL TO BE TREATED AND AN OUTLET CONDUIT EXTENDING UPWARDLY THROUGH THE VESSEL FROM A PORTION ADJACENT BUT SPACED FROM THE BOTTOM OF THE VESSEL, THE LOWER END OF SAID CONDUIT BEING OPEN AND FORMING THE DISCHARGE FROM THE PORTION OF THE VESSEL IN WHICH THE MATERIAL IS TO BE TREATED, SAID CONDUIT HAVING AN OPENING ADJACENT ITS UPPER END FOR THE DISCHARGE OF MATERIAL, A NOZZLE PIPE HAVING AN OPENING POSITIONED TO DIRECT GAS PASSING THERETHROUGH UPWARDLY THROUGH SAID CONDUIT TO FACILITATE UPWARD FLOW OF MATERIAL THROUGH SAID CONDUIT, MEANS ADJACENT THE BOTTOM OF THE VESSEL FOR INTRODUCING A FLUIDIZED GAS TO PASS UPWARDLY THROUGH THE MATERIAL IN THE VESSEL TO FLUIDIZE IT, A PLURALITY OF HEAT EXCHANGERS WITHIN SAID VESSEL, SAID HEAT EXCHANGERS BEING SPACED FROM THE WALLS OF THE VESSEL AND FROM ONE ANOTHER TO PROVIDE SPACES FOR THE MATERIAL BEING TREATED, AND MEANS FOR CAUSING A FLOW OF HEAT-EXCHANGE MEDIUM THROUGH SAID HEAT EXCHANGERS.