US1831679A - Heat transference - Google Patents

Description

Nov. 10, 1931 E. METCALFE-SHAW HEAT TRANSFERENCE Filed Dec. 5, 1928 4 Sheets-Sheet l E. METCALFZE- wwgu fl/Iys.

Nov. 10, 1931. E. METCALFE-SHAW 1,831,579

HEAT TRANSFERENCP Filed Deq. 5, 1928 4 Sheets-Sheet 2 IIII 1931a E. METCALFE-SHAW I 9 HEAT TRANSFERENCE I Filed Dec. 3. 1 928 4 Sheets-Shef. .3

/ uvu ra a ay/M 2 No v. 10, 1931. METCAHFE-SHAW 1,831,679

HEAT Tnmsr'snnncn Fild new; 3, 1928 4 Sheets-Sheet 4 z mmm fe- 97m,

lavmmq Patented Nov. 10, 1931 T OFFICE EDWARD METGALFE-SHAW, F IMPERIAL BEACH, CALIFORNIA HEAT TRANCE Application filed December 8, 1928. Serial No. 323,431. I

This invention relates to the transference of heat from solid surfaces to fluids, liquids or semi-liquids, includlng plast1c or viscous compositions or mixtures, (hereinafter re- 5 ferred to as liquids), and the invention has reference to heat transference for a variety of purposes, including heat-treating liquids, semi-liquids and the like,concentration of solutions, liquid mixtures and the like, .and

19 evaporation or distillationof liquids.

Heat transference is not only effected with increased thermal efficiency as compared with present-day methods, but reduces the time factor of heat-treatment and enables relative- 1y high temperatures to be'employed without damage to the liquid under treatment.

A further important advantage achieved by the invention lies in this that in the concentration of solutions or mixtures, deposits, crystalline or otherwise, are reduced if not quite prevented from forming'on or adhering to the surface, or if theyoccur are progressively removed. a

Numerous subsidiary or additional advan tages are derived from the invention and certain of these will be gathered from the description hereunder.

The invention comprises the constant me chanical removal and displacement of'a film upon a surface receiving heat, to expose a clean or clear portion for the reception of a fresh film which in turn is displaced, the removal and formation of the film being recurrent. v

The invention also consists in the heat treatment of a liquid by depositing a liquid progressively upon a heated surface in a thin layer and causing an organized movement of the layer over the surface to a discharge point. This is effected by mechanically removing portions ofthe layer at frequent intervals stage by stage in a manner adapted to expose a clear surface and laterally displace or relay it upon an exposed surface.

Another feature of the layer treatment according to the invention is that it lends itself to concentration or distillation (fra'c tional or otherwise) by reason of the fact that a large surface is presented for the escape of vapour or gas and that, due to the thin ness and movementof the'layer, the passing or conversion of the liquid or a part thereof into vapour or gaseous form takes place mainly by simple evaporation as distinct from ebullition or the formation of bubbles within the liquid layer. a i

It will be appreciated that by reason of the constant motion and turning of the layer very much highertemperatures for the heating surface with greaterrates of heat transfer can be employed than when the adhesionfilm of a layer remains more or less stagnant. According" to the invention; the means adapted to effect the mechanical removal and diversion of the adhesion film or liquid layer comprise a plurality of scrapers or vanes adapted intimately to contact with the heated surface between: which and the vanes relative movement is effected so that the vanes, so to speak, peel the film or layer from the surface, leaving in their track a clearor substantially clear area and displacing the portionof the film or layer acted upon transversely of the path. A multitude of vanes is employed according to certain embodiments of the invention which are arranged with their faces inclined to the path of relative movement, laterally to displace or direct the liquid removed there by, and further are arranged in spaced rela tionship or are pitched in two dimensions so that they lie in echelon, whereby there is a progressive feed from the path of one vane intothe path of another. Alternatively, the plurality of vanes are not adapted to give the removed or disturbed film a progressive displacement in one direc tion or a redirection. from one predetermined path to another, but are formed or adapted to remove or displace the film (it may be equally-Von either side) and the cleared path is'filled in by other portions of the layer i iowing under gravity actiondown the sur- 7 According. to another method of spread-' ing and displacinga layer of liquidfor heat treatment, the layer is acted upon in a plural-v ity of zones alternately to scrape it from the surface so that it is more or less piled up and subsequently again spread out in a layer over a cleared part of the heating surface. For this purpose the vanes may be reciprocated and given a travel partly in contact with the heating surface'to effect the clearing of the surface and partly in a slightly elevated plane Figure 1 is a front elevation of a" plant designed to carry out the inventionaccording to one embodiment in which an internal surfaceisprovided on whi'ch the liquid for treatment is heated by the aid of. steam.

Figure '2' is a transverse section on the line 2-2 of Figure 1 (certain view lines being omitted) and illustrates a mode of mounting scrapers or vanes.

Figure 3 is a view of adetail.

I Figure 4 is a plan view of plant inwhich the heating surface is of rotary disc form.

Figure 5is1a section on lines 5-5' of Figure4. 7 7

Figures 6 and 7' are, respectively, side and end elevationsfof a plant. having; a heating surface in the formof arectangular plane or table and in which the vanes have a relative reciprocatory or oscillatory motion.

Figure 8 is. a; detail view of.- a cam for operating in conjunction with: the plant shown in Figures 6 and 7. e

Figure 9 is an enlarged detail view illustrating one convenient form of vane or scraper element according 'tothe invention.

Figure 10 is a diagram illustrating the action of the scrapers on. a. ribbon layer of liquid showing the diversion of the ribbon layer from one path to another.

Figures 11. and 12 are diagrams illustrating byway of example, two relative arrangements of the vanes with respect to one another giving a different movement of a liquid layer over the surface oftheheating element.

In carrying the inventioneinto effect according to one convenient mode (see Figures 1 and 2) as applied, by way of example, for sugar boiling or like processes by the aid of steam heat, a base 1, preferably supporting the storage tank 1a,. hasmounted: uponv it a column and driving gear fora rotary shaft 2a mounted ina footstep bearing 3 and fur- 1 ther supported in a bearing 4- of the driving gear casting. A cylindrical element 6 concentric with the shaft 2a is supported ina sta. tionary position by bracket members or annular supports 38 from a. stanchion or other support 39 whichalso serves as atop bearing at 40 for the shaft 2a. The cylindrical element is: provided with a" jacket 6d through which steam is circulated by the pipes 22 and 23.

Vane elements or scrapers 21 are mounted upon the shaft 211 in any convenient manner; for example, the shaft is provided with a series of rings 41 abutting one against the other and clamped between an upper collar 41a and a lower collar 41b. The opposing surfaces of the rings 41 are grooved to accommodate the vanes 21 which according to one convenient mode are formed of U-shape integrally in pairs as shown at 21a, Figure 2. The rings 41 are formed on their opposing faces with corresponding U shape slots to accommodate the ends of the vanes.

A chute 31b is mounted on the stanchion 39 below the end of the cylinder 6 and is provided with a flanged orifice 310 to accommodate the shaft 2a. This chute is adapted to. receive the liquid, as it drips from the lower marginof the cylinder 6' and deliver the same to the plant.

The liquid is-f'ed to the cylinder 6 from a tank 26 through a pipe line 25 and mouthpiece (see Figure 3) WdlCll is contoured: tocon-form to the circumference of the upper collar member 41a. The collar 41a is provided with a conical extension or skirt 410 which .is of only slightly less Idianieterthan the interior diameter of the cylinder 6 so that the liquid spread upon the collar 41m from the feed. mouthpiece fiows down upon andisspread from the periphery of the .skirt'41c in: a layer onto the interior surface of the cylinder where it is treated and given a progressively downward displacement. by the vanes 21 in the manner more particularly described. hereinafter. The tank 10. may act as a reservoir for the liquid to be treated and is provided with a centrifugal pump 1?) (operated by the driving'gear for the shaft 2a) adapted to deliver the liquid up the pipe 16 to the tank 26 at a rate predetermined .to maintain a constant level or head of liquid in the feed tank 26. An overflow pipe 28 iszfitted to the tank 26 to return any surplus discharged by the pump to the tank 1. I

The mouth-piece 18 (see Fig. 3) is arcuate and adapted snugly to fit the contour of the collar; 41a; In order tovarythe width of the ribbon layer spread upon the collar by the mouthpiece, it may be provided with a sliding. shutter 19 which may be adjusted by the rod 29a and for the-purpose of very ing the thicknessofthe layer the slot 20 in the side of. the mouthpiece through which the liquid escapes may be adjusted by the slide 20a manipulated by the, rod .205.

t will lie-appreciated that the vanes or scrapers 21 are revolved by the driving gear while the cylinder 6 remains stationary.

The revolution of the: collar 41a'under the V mouthpiece 18 enables the latter to feed a ribbon layer of liquid to the face of the collar which flows down and is distributed by the skirt. 41c onto the cylinder. The vanes, as they revolve act upon the continuinncr surface of the ously discharged ribbon layer and cause the liquid to be displaced progressively stage by stage down the heated surface 6, so that the liquid receives uniform heat treatment which 18 complete when the liquid reaches the lower end of the cylinder.

The. invention has been described abov with reference to the distribution of the liquid for treatment upon a surface of cylindrical form. The invention may, however, be carried into effect by the distribution thereof upon a rotating disc or flat table. One form of this arrangement is illustrated in Figures 4 and 5. A standard or column 42 is provided with a hollowed part 4200 and has a stufling box 42?) and a footstepbearing 420 for the spindle 43 of a hollow table element 44. The table element is flanged and has a heating surface disc 45 mounted thereon and sealed at its periphery so as to make the space 46 under it steamtight. In order to avoid fieXure or buckling of the disc supplementary supporting .bolts or members 44a may be provided. i

For supplying steam to the space 46, the spindle 43 is provided with inlet and outlet ducts 46a and 47 a communicating with suit able inlet and outlet ducts. The table 44 on its lower surface is provided with an annular rack 44?) with which a bevel pinion 48 of a driving gear is adapted to mesh for the purpose of giving the table and surface 45 rota- I is tional movement.

. Liquid to be treated may be fed towards the centre of the table from a tank 49 which maybe kept supplied with liquid from any suitable source. The liquid is fedon to the table by means of a pipe 50 terminating in a mouthpiece of the character already de scribed in connection with the earlier figures. Coaxial withthe table 44 is a vertical stationary pipe 51'and cover 510. to collect and carry away the evaporated steam. The cover 51a may be supported in any convenient man ner as by spaced arms 51?) (only one of which is shown) mounted on posts 510 carried by brackets 51d from the column 42. The cover 51a also carries a plurality (for example, twelve four only of which are shown) of radial arms52 on which a series of vanes 53 is secured. The. liquid is fed onto the disc near the centre and comes under the action of the vanes as the table revolves beneath such. Thevanes cause the liquid progressively to move outward towards the circumference and the treatment is such thatwhen the liquid arrives at the periphery it is ready for discharge and m -y be delivered by means of a scraper 54.

While for general purposes itis convenient to employ rotary motion; for causing the progressive travel of the liquid over the heating surface, the same effect may be gained by providing relative reciprocation or oscillatory movement between the vanes and the heated surface bearing the liquid: For example, in Figures 6 and 7 a stationary rectangular 'hollowtable 55 is carried by a suitable frame 56' and receives a heating medium through pipes or conduits (not shown) which are located in any suitablesituation. The liquid is fed or supplied in a layerto one end of the table and is discharged. from the'other end. A supply tank 57 may be discharged through a control cock 58-into a funnel59 which terminates in a mouth-piece el'ement (not shown) which extends across the width of the table. Above the table a hood 60 may be provided for carrying away vapour and air.

A pair of longitudinal frame elements 61 engaged by cam elements 67 keyed upon shaft 68 which is driven by any suitable means. The rotation of the cams causes the the table to be reciprocated. In addition to the rectilinear reciprocation, the vanes are provided with a motion transverse to the direction of reciprocation at each end of the reciprocating stroke so that they arealternately raised from and lowered onto the table. To accommodate this movement the arms 6'4 engage the frame element 61 by a pinand-slot connection 64a. At each end of the table a cross shaft 69 is mounted and has secured to it a pair ofstepped cam elements 69a. by chain and chain wheel gear 70 from the driving shaft 68 or by any other convenient driving connection. The vane-carrying frames 61 are floated upon the cams and rise and fall as they rotate and according to their contour. latch members 71 are provided the .upper surface of whichis flat and adapted to constitute a sliding track for bars or studs 72 secured to the under-side of the frame element 61. This arrangement permits the free reciprocation of the vanes while at the same time providing a means to cause their elevat1on at the end of their reclprocating stroke and their depression into contact with the table for the commenc'ement of a stroke, or with an intermediate rise of the vanes during a portion of the reciprocatory travel according to the desiredaction of the vanes. For example, the earns 70 may be designed to have three steps 70a, 7 0b and'700. The lowest step 70a and the next succeeding step 70?) each occupy aquarter of a revolution while the higheststep extends over the remaining half revolution. The latch members 71 in proceeding from the step 70a to step .706 are raised 1/16th and similarly in-proceeding from step 706 to step 700 they; are raised Atthe ends of the tables pivoted 180 have cross bars 62 each of which carries a cranked arms 64 to be oscillated and causes F The shaft 69 may be rotated I another 1/16th. The timing of thecams is such that during the first half of the reciprocatory movement of the vanes, they move the liquid lying on the table forward so that the liquid is more or less piled in front of the vanes. The length of the stroke may have any suitable predetermined value and where the stroke is l" the vanes clear the liquid layer in front of them and push it) forward for The cams then lift the vanes 1/l6th in passing from the step a to the step 70?) and during the remainder of the travel the vanes spread out the piled liquid again to a depth of 1/16th, leaving the whole table surface covered. The spreading movement continues for the remainder of the reciprocatory stroke, that is to say, for a movement of At the end of the stroke the step 700 raises the latches 71 a further 1/16th lifting the vanes clear of the table and out of contact with the liquid layer. At this point the return reciprocatory stroke commences and the vanes are carried back out of contact with the liquid to their initial position. V

The vanes between the longitudinal frames are arranged the full width of the table and may be formed as elongated rectangular plates.

The vanes are preferably formed on or constituted by the ends of piecesof wire adapted to afford a certain amount of resilience. They may be made from wire of circular cross section or they may be formed by members of other sections. The portion or body of the vanes in rear of their contact or active faces are preferably inclined in two directions, one towards theirheating surface so as to prevent the liquid from creeping or running down the wires, and another to facilitate or accommodate the relative movement and to aid in resilient action. The vanes are adapted to contact with the surface or have a working clearance therewith. In order to avoid loss of heat, means may be provided for heating the vanes and their supports or the vanes may be heat insulated from their support.

Figure 9 is an enlarged view showing the active end of a vane wire which has been found suitable for use in conjunction with a cylindrical surface. The end of the wire is formed with a slightly convex surface 21a of a curvature corresponding with the curvature of the cylindrical surface. This face may be ground or run in on the cylindrical surface. There the vane is intended to engage an external cylindrical surface the face 21 would be formed correspondingly concave. The wire is formed to provide a face or edge 21?) and is set so that it lies at an angle of 45 or'other appropriate angle to the path due to the relative motion between the vane and the heated surface. This face 21b is the active face adapted to scrape or peel the liquid from the cylindrical surface and divert 1t laterally, or in a direction transverse to the path above mentioned. At 210 the vane may be cut away in order that the adjacent edge of the surface 21?) may be sharply defined.

A vane of the characterv illustrated in Figure 9 is adapted to promote a unidirectional displacement or diversion of a ribbon layer of liquid in an organized and predetermined progressive manner as hereinafter described.

Where however the invention is applied in connection with a vertically placed surface or where its position has a vertical component and it is intended that gravity shall take an active part in the movement of the layer of liquid, the vanes may be formed with a square, curved ordouble inclined active face or edges, such as may be presented by a round, oval, square or wedge-shaped sectionwire or rod. Similarly, vanes of the above character may be employed in connection with surface disposed such that gravity has no influence for movement on the layer but where move ment is promoted or modified by centrifugal force. a

In these cases the reforming of the layer or the filling in thereof behind or in the path of. a vane may be aided by gravity or centrif ugal action on the'adjacent portions of the layer. g

The action of the vanes upon a liquid film or ribbon is illustrated in Figure 10. The upper or leading edge of the'face 21b lies upon the same horizontal line as the lower or trailing edge of the vane in front but it will be obvious that these faces 21?) may overlap one another, if desired. The vanes 21 present the surface 216 towards the direction from which the surface carrying the film or ribbon 21d is moving, as shown by the arrow. It will be seen that each surface 21?) in turn obstructs the path of the liquid so that the surface of the cylinder is cleared behind the vanes in the respective paths and at the same time diverts, bya wedge-like action upon the liquid, the ribbonor stream thereof, as at 210, from its path in front of one surface 21?) to a path a stage nearer the discharge and in front of the next surface 21?).

The vanes are arranged in a plurality of vertical series, each series comprising'equally spaced vanes having active surfaces of predetermined dimension X, Figure 10. Every series is vertically displaced or pitched with reference to its adjacent vertical series on the following side (having referenceto the relative movement) equal to the dimension X with the active face. The vertical spacing of the vanes in a vertical row is some predetermined multiple of the dimension X.

In the diagram, Figure 10, the pitch of the series of vanes is at a minimum, that is tosay, the ribbon is deflected by the vanes of each vertical row or series of vanes.

Two examples ofthe pitching of the vertical rows of vanes are illustrated in Figures 11 and 12. In Figure 12 the vanes are pitched so that the paths of the liquid, as at 21d, are diverted, as at 21c, from the vanes of one vertical row to the vanes in a third vertical row (corresponding with the direction of rotational movement) from it, whereas in F igure 12 the paths 21d are diverted at 2-16 to va'nes in the sixth vertical row from the vanes in the vertical row at which diversion takes place.

The pitch arrangements are given by way of example and it will be appreciated that any pitching relationship may be adopted. It will also be appreciated that the greater the pitch the longer the liquid remains in contact with the heating surface before it is turned over or disturbed.

The arrangement of the vanes in Figures 4 and 5 is such that active surfaces give the liquid layer a displacement radially outwards and the vanes of one arm 52 (see Figure 4) are pitched in the manner already described with respect to the vanes of adjacent arms. In the forms (see Figures 6 and 7) where there is a relative reciprocatory movement between the vanes and the heating surfaces, and where the liquid is alternately heaped up and spread out, a similar pitch arrangement may be employed in order that the whole surface of the table may be acted upon by the vanes.

The arrangement of vanes, the area and dimensions of the heating surface, the rate of feed of the liquid to the heating surface and the rate of relative movement will be predetermined and varied according to the particular treatment in view. The process of heat treatment will be devised and directed to the end in view, whether it be for theboiling of sugar or for other processes involving the extraction of the liquid or volatile content of a solution or body, or for evaporation or distillation. The invention is applicable for distillation processes in which it is desired to distil or extract a more volatile liquid from a body of less volatile liquid as it enables heat to be supplied in such a manner that the temperature of the mixed liquid is kept below that at which the less volatile constituent vaporizes and yet above the temperature at which the more volatile liquid can evaporate.

I claim:

1. A plant for heat transference between the surface of a solid body and a liquid comprising a surface, means for heating the surface, means for applying the liquid to the surface in a thin layer, a multiplicity of vanes acting adjacent the heated surface and means for effecting relative movement between the vanes and the surface, whereby the van-es remove portions of the layer, (to expose a substantially clear surface) simultaneously in a multiplicity of zones and displace the re- 'movedportionstowards the zones of other vanes.

2. A'plant for heat transference between the surface of a solid body and a liquid comprisingfa-surface, means for heating the surface, means for applying the liquid to the surfacelin afthin layer, 'a multiplicity of vanes acting adjacent the heated surface and ar ranged ina plurality of-rows, the vanes in each row being laterallydisplaced with reference to the corresponding vanes in adjacent rows not more than the width of the vanes and-means for effecting relative movement between the vanes and the surface, whereby the vanes remove portions of the layer, (to expose a substantially clear surface) simultaneously in a multiplicity of zones and displace thelremove'd portions towards the zones of other vanes.

3; A plant as claimed in claim 2 wherein the pitch of the vanes in each row is a multiple of a unit, said unit being not greater than the width of a vane. Y

r 4. Aplant .for'heat transference between the surface of a solid body and a liquid comprising a surface,=means for heatingthe surface, means for applying the liquid to the surface in a thin layer, a multiplicity of vanes acting adjacent the heated surface, said vanes being inclined to and resiliently engaging the surface, and means foreffectingrelative movement between the vanes and the surface, whereby the vanes removei portions of the layer, (to exposea substantially clear surface) simultaneously in a multiplicity of zones and displace the removed portionstowards-the zones of other vanes.

I 5. A plant for heat transmission between the surface of a solid body and a liquid comprising an externally heated cylinder, means for'fiowing the liquid onto the interior surface of the cylinder in a thin layer,. a multiplicity of vanes positioned to engage and act upon the interior surface of the cylinder, and means foreffecting relative rotation between the vanes and the cylinder, whereby the vanes remove portions of the layer, (to expose a substantially clear surface) simultaneously in a multiplicity of zones and displace the removed portions towards the zones of other vanes.

6. A plant for heat transmission between the surface of a solid body and a liquid comprising an externally heated cylinder arranged with its axis vertical, an inner rotatable shaft carrying a multiplicity of vanes positioned to engage and act upon the interior surface of the cylinder, said vanes being inclined to the surface downwardly and in the direction of rotation, and means for flowing liquid onto the interior surface of the cylinder in a thin layer, wherebythe vanes remove portions of the layer, (to expose a substantially clear surface) simultaneously in a multiplicity of zones and displace the removed- :portions towards the zones of :other vanes.

. 7 A plant as claimed in claim 6,Wherein the means for flowingcthe liquid onto the cylinder comprises a rotatable element adapted todeliver theliquid onto the inner surface of the cylinder in a thin layer and an arcuate mouthpiece for delivering-the liquid to said rotatable element,vmeans being provided for adjustingwthe: flow of the liquidflfrom the mouth-piece-to said rotatable element 8. Avheat transference apparatus comprising an externally heated. cylinder, meansfor applyingiliquidto theinterior surface of the cylinder in a thin layer, and an innerrotae table shaft carryinga multiplicity of vanes positioned to engage and act upon saidinterior surface, said vanes beingarranged in rows, the vanes in each row beinglaterally displaced with reference to the corresponding vanes inaadjacent rows not ;more than the Width. ofthe vanes.

9. A heat transference apparatus as claimed in=claim 8,: wherein the pitch ofthe vanes in'each row is amultiple of a unit, said unit being not .greater than thewidth. ofa

vane- 10. A- plant for .heat transference between the surface ofa .solid body and aliquid, com.- prising. a surface, means for heating the-sur-x face, means for applying; vthe liquid 1110 the surface inra thin layer, a multiplicity of vanes acting adj acent the heatedsunface andemeans for effecting relative movement between the vanes and=the surface, the arrangement being such that theva-nes remove portionsaaof the layer, (to expose: a substantially clear.sur-' face) simultaneously in a1; multiplicity of paths anddisplace the removed portions of the layer transversely ofsaidmpathS into paths clearedsby the 2 removal. of other pore tions ofthe layer. 7

In testimony whereof I have signed :my name to; this specification.

EDWARD METGALEE-SHAW;

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