US2677898A

US2677898A - Steam heated drier

Info

Publication number: US2677898A
Application number: US138774A
Authority: US
Inventors: Paul E Ohlson; Edward A Hodge
Original assignee: Pusey & Jones Corp
Current assignee: Pusey & Jones Corp
Priority date: 1950-01-16
Filing date: 1950-01-16
Publication date: 1954-05-11
Anticipated expiration: 1971-05-11
Also published as: GB668025A; FR1020914A

Description

May I1, 1954 P. E. OHLSON ETAL STEAM HEATED DRIER 6 Sheets-Sheet 2 Filed Jan. 16, 1950 INVENTORS) PAUL E. OHLSON '9 EDWARD A. HODGES ATTOR NE Y5 May 11, 1954 P. E. oHLsoN ET AL ,STEAM HEATED DRIER s Sheets-Sheet s Filed Jan. 16, 1950 III/(IIIIIIIII/II;

INVENTORS Q49] GE HAUL EIOHLS EDWARD A H BY ,Qmf

ATTORNEY May 11, 1954 P. E. OHLSON ETAL STEAM HEATED DRIER 6 Sheets-Sheet 4 Filed Jan. 16, 1950 \\\\\\i my I PAUL E. OHLSON v EDWARD A. HODGE y 11, 1954 P. E. OHLSON ETAL 2,677,898

STEAM HEATED DRIER Filed Jan. 16, 1950 6 Sheets-Sheet 5 47 45 gwuwvtow 3 67 ,444 PAUL E. OHLSON w EDWARD A. HODGE W////////// wwm ww ATTO R N EYS STEAM HEATED DRIER 6 Sheets-Sheet 6 Filed Jan 16, 1950 mm M m M m m w O 2% m m Patented May 11 1954 STEAM HEATED DRIER Paul E. Ohlson and Edward A. Hodge, Wilmington, Del., asslgnors to The Pusey Wilmington, DeL, a corporation of notation, Delaware & Jones (Jor- Application January 16, 1950, Serial No. 138,774

18 Claims.

The present invention relates to improvements in steam heated driers, such as are used in paper mills, food processing plants, industrial chemical manufacturing plants and the like.

The primary object of the invention is to increase the efiiciency of such driers, without in creasing the steam pressures employed and without increasing the size or materially increasing the weight of the driers.

A further object of the invention is to provide a drier construction in which the heat transfer rates are materially increased between the heating medium and the surface of the drier, at the same or reduced pressures, as "compared to prior, conventional structures.

A further object is to provide a drier construction of the same or greater size in which the: power required to drive the drier is very materially reduced, as compared to prior constructions.

Another object the condensate removal from the interior surface of a drying roll or the like, to the end that the formation of a layer of condensate on said surface is eliminated and the heat transfer between the steam and said surface is improved.

Another object is to increase greatly the speed of the flow of steam in contact with the inner surface of the drying roll, further to improve the heat transfer rate and the removal and elimination of air and condensate particles.

Another object of the invention is to prevent the creation of a layer or layers of condensate, rotating with the drier and thereby to reduce the power factor involved in rotating the driers, as compared with prior driers in which such layers of condensate were rotated therewith.

Another object of the invention is to provide a drier in which the steam for heating the periphery of the roll is delivered directly adjacent the inner surface of the rim, for high speed travel therealong and in which the condensate is immediately removed from said inner surface, as rapidly as formed, by a combination of forces, including gravity actin on the condensate, centrifugal force, and an inward scooping action resulting from the inertia of the condensate.

Another object is to provide means for moving the condensate radially inwardly relative to t. e inner face of the rim, substantially immediat -y as it is formed, so that the condensate is not permitted to form an insulating layer between the inner surface of the rim and the incoming steam.

Another object is to provide improved means for isolating the inwardly thrown condensate,

of the invention is to improve for collecting the same within the drier, out of contact with the heat absorbing surface, and for discharging the condensate from the collecting means to the outside.

Another object of the invention is to provide means within the dried adjacent the heat absorbing surface, in which a pulsating steam presis effected, so as to flash minute particles of condensate adhering to the heat absorbing surface, further to enhance the heat transfer.

Another object is to provide an improved system of connecting a plurality of 'driers in a line, such as a paper making line, in a novel seriesparallel circuit, to improve the efficiency of the line.

Driers conventionally employed in industry are of two general types;

acts as an insulator between the steam and. the shell. In such case, the steam must heat the water which in turn heats the shell, an inefficient heat transfer system.

The condensation is conventionally removed bottom of the interior of the shell or mounted to rotate therewith.

In the mild steel, jacketed driers, steam jackets are associated with the inner surface of the shell and the steam is delivered directly thereto. However, the difiiculties resulting from the presence of air, noncondensable gases, and substantial amounts of liquid condensate in the jacket spaces are not eliminated. The condensate often collects in the form of puddles, and the jacket spaces sometimes become water-bound. Moreover, the rate of steam flow through the jacket spaces is not suificiently high to exert a scouring action, effective to remove air and non-condensable gases.

The present invention attains all of the advantages characteristic of both types of driers and eliminates the disadvantages thereof. Accordingly, the procedure previously followed in connection with cast iron driers is reversed. That is to say, the drier shell is heated directly with high velocity steam and the condensate and any particles of air are transferred inwardly into an inwardly spaced collecting the insulating effect of the water film and air cannot interfere with the transfer of the heat from the steam to the effective surface of the shell. The condensate so collected may be discharged from the drier before such a volume has accumulated as would increase the power required to rotate therein.

device, where the drier with the water In spite of the fact that the present invention provides for high velocity steam flow directly in contact with the head absorbing surface of the drier shell and for immediate removal of condensate to a zone where it cannot act as an insulating layer, inhibiting heat transfer to said surface, the internal elements in the drier need not be steam tight, as is the case with the so-called jacketed drier.

The fundamental combination of the present invention comprises a sheet metal cylindrical shell, spaced inwardly a short distance from the inner surface of the cast iron rim, having a plurality of longitudinally extending vanes or fins projecting outwardly into contact with the rim and dividing the space therebetween into a plurality of longitudinally extending compartments; means for delivering the steam to these compartments behind the vanes or fins, for high velocity flow therein, and means for removing the condensate from the surface of the rim and causing the same to flow through the shell out of contact with the inner surface of the rim. The condensate so removed may be collected in various ways and then removed to the outside of the drier. An important feature of the invention is the forward inclination and axial angular disposition of the fins or vanes so that, as a result of the scooping action, the condensate flows axially, in one direction or the other, and then radially inwardly for collection and removal from the drier.

In accordance with the present invention, the cross-sectional area of the space between the inner surface of the cast iron rim and the outer surface of the internal shell, which may be termed the heat transfer space, is accurately controlled. and proportioned with respect to the l total area of the openings in the shell, leading from said space to the interior of the shell. By this accurate control and proportioning, the steam is caused to give up substantially all of its latent heat in the steam quality in this space may be reduced from 100% at a predetermined pressure to substantially 10%, at the same pressure, as it is discharged from the heat transfer space to the interior of the shell. This reduction in steam quality is the result of the transfer of the latent heat of the steam directly to the cast iron rim. It results, of course, in a very material reduction in volume, the pressure remaining the same, with a consequent high velocity flow in the heat transfer space, as will be apparent from the specific examples given below.

In the accompanying drawings, a number of specific embodiments of the invention are shown for purposes of illustration, but it must be understood. that the drawings are illustrative only and are not restrictive of the invention, as many modifications and variations will occur to those skilled in the art from a consideration of the drawings and the following description.

In the drawings:

Figure 1 is a vertical, axial. section of a preferred form of drier.

Figure 2 is a radial section taken on line 2-2 of Figure 1;

heat transfer space. The

Figure 3 is a radial section, looking in the opposite direction, taken on line 33 of Figure 1;

Figure 4 is an enlarged fragmentary radial section, taken on line 4-4 of Figure 1;

Figure 5 is a fragmentary axial section on an enlarged scale, showing a prefered connection between the inner shell and the end of the drier;

Figure 6 is an enlarged fragmentary section with parts broken away, showing the condensate engaging fins or vanes, the section being taken substantially on line 6-6 of Figure 1;

Figures 7 and 8 are fragmentary sections and elevations taken on lines 1-! and 8-8 of Figure 6;

Figure 9 is a fragmentary radial section, taken on the mid-section of the condensate collecting well or trough, showing a condensate discharge nozzle;

Figure 10 is a similar view, showing a discharge aperture, instead of the nozzle;

Figure 11 is a fragmentary radial section of a preferred form of joint between adjacent sections of the shell;

Figure 12 (sheet 1) is a fragmentary section and elevation of a modified form of steam outlet connection;

Figure 13 is a diagrammatic view of a steam and condensate distributing system for a plurality of driers;

Figures 14 and 15 are sectional and plan views of a preferred form of condensate removing scoop;

Figure 16 is a section and elevation taken on line 16-46 of Figure 14;

Figure 17 is a perspective view of a modified form of condensate removing scoop;

Figure 18 is a fragmentary section on line l8l8 of Figure 17;

Figures 19 and 20 are axial and radial sections of a modified shell construction; and

Figure 21 is a sectional detail on an enlarged scale.

The drier shown in Figures 1-4 comprises a heavy cast iron rim 20, supported at its ends by

heads

21, 22, having hollow central bosses 23, in which hollow journals, not shown, are fitted, so that the drier as a whole is carried by the journals for rotation about a horizontal axis. The heads and the cylindrical rim are hermetically sealed and provide a steam tight interior 25.

Spaced from the inner surface 28- of the rim is a cylindrical, sheet metal shell 2'1, which may be of stainless steel, Monel, or any other suitable material. Projecting from the outer surface of the shell are a plurality of groups or sets of vanes or

fins

28, 29, 30, 3|, pitched forwardly and outwardly in the direction of drum rotation, having their outer edges in contact with the inner surface of the rim, and disposed in angular relation to axial sections of the drum. Preferably, the angular disposition of each vane is such that its leading end is nearer to the head of the drier and its trailing end is nearer to the mid-section thereof.

The forwardly pitched vanes are preferably made in a plurality of angularly disposed sections, as shown at 28-31. Although only four sections, in generally endwise alignment, from one end of the drum to the other, are illustrated in the accompanying drawings, it should be understood that each vane may be considerably shorter and the number in each longitudinally extending group correspondingly increased.

The shell is provided with a plurality of spaced apertures 33, in alignment with and facing toward the leading, 2343 l residual air and low explained.

The adjacent ends of the

vanes

28 and 29, and 36 and 3 1, respectively, are interconnected by circumferentially extending relatively short angle interposed between the outer surface of the shell 2? and the inner surface 26 of the rim. Each angle section is spot welded to the shell 27 at a plurality of spaced points 36, Figure '7. of the vanes 28, 29, etc. are held against the radial webs of the angle sections 35 by clamping plates El, having their back surfaces recessed to receive the inwardly turned end flanges 38 and having their ends 39 welded to said webs.

Thus, the four sets of vanes Kl-3i and their connecting angle strips 36 and 35 divide the space between the shell 2? and the rim 2t into a plurality of longitudinally extending compartments or steam spaces 4%].

Disposed inwardly of the shell 2?, behind the several apertures 33 are four pairs of inwardly projecting angle strip deflectors ll and 52, in endwise alignment, but in angular relation to axial sections of the drum and shell, with their leading ends adjacent the heads of the drum and their trailing ends adjacent the mid-section of the shell. As indicated in Figure 4, each angle member comprises a rearwardly extending flange '43 adapted to be secured by resistance spot welding or by rivets at fiange i5 dissubstantially concentric to the cumferentially extending welded or riveted at a plurality of spaced points to the inner surface of the shell 27?. At the points where the deflectors 4i and 52 abut the radial webs of the angle members it and ll, openings and M are provided in said webs, for the flow of condensate from the deflectors into the trough space or well 5!? therebetween, as explained below.

Referring to Figures 9 and 10, at the inner ends of the vanes 29 and 3E, openings (33' may be provided, leading directly to the trough or well 5 3, or, if desired, these openings may be provided with short nipples 5! having caps 52 on their inner ends, provided with orifices 53 of accurately predetermined size.

For simplicity of manufacture, the inner shell is preferably made up of a plurality of sections, to each other by lap joints, the details of which are illustrated in Figure 11. One section Zia is provided with an axially extended, outwardly offset marginal portion 21b, upon which the marginal portion 270 of the next section 2M is lapped. The lapped marginal portions are apertured and are secured together by nuts and bolts 55.

Secured to the hollow central bosses 23, 23 of the drier heads are axially extending shaft means for accurately positioning the shell and serving to deliver steam to and remove condensate from the drier. A shaft 50 has its right flanges cc and E8 hand end secured in a socket member 6i carried distributing head 63. The condensate return pipe 65 is connected to interior passages 65 in the head having two radial branches connected to curved pipes 57, leading to condensate scoops indicated generally at 68 and described below.

The outer, steam supply pipe 54 leads to an interior space within the head, separated from the space 86 and having two sets of four outlet nipples "it and H, to which two sets of radial steam delivery pipes 12 and 73 are connected. The latter are connected at steam headers i l and 15, extending axially of the drum, behind the sets of

vanes

23, 29 and 39, 3!, respectively.

The headers 74 and J5 deliver steam to the spaces 40 between the shell 27 and the inner surface of the cast iron drier by connections shown in Figures 2 and 4.

The plates overlie openings 78 in the shell, through which the nipples 36 extend and these plates may be secured to the shell, if desired, by nut and bolt connections. The outer ends of the nipples 76 are closed as indicated at E9 and their side walls are slotted as at 83 so that steam is discharged laterally and does not impinge directly against the inner surface of the drier.

The shaft cc and the outer steam pipe 64! are 8| having a plurality of to the steam turnbuckle assemblies are provided for each end can be forced outwardly, firmly into engagement with the shell and the shell and vanes maintained in proper position.

If desired, the radial steam delivery pipes 12 and 13 may be consituted by flexible hose sections of suitable heat resisting material, connected to the central distributing head 63' and to the headers by conventional couplings.

Each vane 28-3l is preferably shaped in crosssection substantially as shown in Figure 4 and is relatively thin sheet metal having good spring characteristics, such as thick stainless steel, so that the outer edge of the vane will bear against the inner surface of the drier with spring force and will conform to overall irregularities therein. A line of bend, as indicated at l forming action.

The shell ill may be secured to the inner faces of the end flanges of the The jacket may be bolted at spaced points to an end ring 9! which, in turn, is welded to a radial ring 9?. having a groove 93 in its axial, outer face, for the reception of packing material such as asbestos. The ring 93 may be secured to the end flange of the drier by screws 95 or the like.

Disposed in the central, inwardly facing channel or well Eli are a pair of suction nozzles or scoops 68, supported by radially extending rods '1 carried by the head 63. The rear ends of the scoops 68 are connected to the outer ends of the curved pipes 61, which are connected in turn at their inner ends by fittings 98 to the hollow interior 66 of the head 63. The details of certain preferred forms of scoops are shown in Figures 1 1-18 and will be described below.

In the operation of this form of the drier, steam delivered through the hollow journal and the hollow central shaft 64 fills the entire interior of the drier, since the shell does not have a steam tight fit, and, in any event, the steam is free to flow through the longitudinally extending compartments and apertures 33 to the interior. The steam fiows with high velocity from the openings 80 in the nipples 16 into the compartments between the shell 2! and the inner surface of the rim. Condensate forms on the surface 26 of the rim, but is substantially immediately removed by the vanes 28-31, during the rotation of the drier. During the ascending portion of the rotational cycle, the condensate flows along the leading, inner faces of the vanes, toward the midsection of the drier, because of the angular disposition of the vanes. As a result of a scooping action and the force of gravity, the condensate flows inwardly through the apertures St to the inner surface of the shell 2?, and along said surface until it strikes the deflector members 4i and 42. The flow along these members is in the same direction and the condensate is delivered through the openings to the central well or trough 50.

During the descending portion of the rotational cycle, any condensate not removed from the defiector members M and 42 drops down, to be caught by the deflectors ahead thereof, on their ascending movement. The condensate collected on the inner surface of the shell thus flows longitudinally toward the mid-section, and is deposited by gravity and centrifugal force into the circumferential channel or well where it is removed by the suction scoops 68.

The steam flowing through the spaces 31 between the outer shell 21 and the inner surface of the rim with high velocity exerts a scouring action on the inner surface of the rim, thereby removing air and non-condensable gases and preventing condensation from accumulating in a layer of substantial thickness. Also, the vanes 28-3! exert a pronounced scooping action on any condensate tending to form on the inner surface of the rim and tending to lag behind the rotational movement of the rim. As a result, a more efficient heat transfer is effected than is possible with prior constructions.

As noted above, the cross-sectional area of the space between the shell and the inner surface of the cast iron rim is accurately predetermined, and the relationship between this area and the sum of the areas of the openings 33 etc. leading from the space to the interior of the shell is accurately proportioned, preferably at a ratio of 10 to l. The steam introduced at a predetermined pressure at 100% quality gives up its latent heat in the steam transfer space and quality and volume are reduced by condensation, to a quality of 10% when the steam and condensate are delivered to the interior of the shell through the openings 33. This reduction in quality and volume results in high velocity steam flow in the transfer space. As an example, assuming the steam pressure to be 35 pounds gauge and the quality to be 100%, then the steam volume will be 8.5 cubic feet per pound (1174 B. t. u.) upon its injection into the heat transfer space, as will be found from any standard entropy diagram. Steam at 35 pounds gauge with a quality of 10% upon release from the heat transfer space will have a volume of 0.35 of a cubic foot per pound (330 B. t. u.), as will be noted from the entropy diagram. The reduction in volume is compensated for by the high velocity flow of steam in the transfer space, between the inlet nipples 76 and the condensate discharge openings 33.

The steam velocity is controlled by predetermining the sectional area of the annular space between the shell and the interior of the drier rim. For instance, if the input steam flow is 600 pounds per hour, at 35 pounds per square inch and the inside diameter of the drier is 46 inches and the outside diameter of the shell is 45 inches, by simple calculations, the cross-sectional area of the transfer space is found to be 71.5 square inches or 0.496 square feet. The volume of the steam per pound at 35 pounds per square inch is 3.5 cubic feet, as may be noted on the entropy diagram. Thus, 600 pounds per hour times 8.5 equals 5106 cubic feet per hour, or 85.1 cubic feet per minute.

Thus, the velocity within the transfer space will be 85.1 divided by 0.496 or 172 feet per minute. Steam velocity in this range is highly effective to displace and remove from the inside surface of the drier rim, condensate, air films and non-condensable gases, as compared with an ordinary drier in which the velocity has been found to be between 2 and 4 feet per minute.

The steam flow, regardless of pressure or volume is controlled essentially by the work done by the drier, i. e. the amount of heat transfer to the paper being dried, which may be measured in B. t. u.s per hour. From consideration of a standard entropy diagram, it will be noted that saturated steam at 35 pounds per square inch has a volume of 8.51 cubic feet at quality and contains 1174 B. t. u. Steam at 35 pounds per square inch at 10% quality has a voiume of only 0.851 and contains only 350 B. t. u. Hence, in the above example, if the volume of the steam entering the heat transfer space is so controlled, before it is allowed to flow to the interior of the shell, that its quality drops from 100% to 10%, then the heat transfer is 824 B. t. u. at 35 pounds per square inch, the difference between 1174 and 350.

As noted above, the control of the steam quality and coincidentally of the volume is effected sim ply by making the area of the escapement open ings from the heat transfer space just large enough to allow the steam. to pass therethrough when it has reached 1.0 quality and not before.

In Figure 12 (sheet 1), there is shown a modincation of the right hand end of the drier, so that a plurality of such driers may be connected in the manner shown diagrammatically in Figure 13, with a number of flash tanks in the circuit. In this arrangement, steam flows in parallel through one pair of driers, and is delivered therefrom to flow in parallel to and through the next pair, while steam separated from the discharged condensate from the first pair joins the steam delivered therefrom and flows therewith through the next pair, and so on, as explained below.

The drier of Figure 12 may have substantially the same shell construction as described above, in connection with Figures 1-11.

Steam is delivered through the hollow journal to the distributing head and the radial pipes to the headers and the space between the inner surface of the rim and the shell as previously described. Condensate is collected in the circumferential channel and removed through suction scoops, connected by the curved pipes to the hollow interior of a central shaft I09. The shaft is in communication with a pipe IE6 (Figure 13), connected by another pipe I ill to a first flash tank it, where steam and condensate are separated.

At its right hand end (Figure 12), the central shaft M2 carries an expansion joint III? associated with a sleeve Iii having a plurality of apertures II 2 therein, for the steam, through the hollow journal lit to pipe lit (Figure 13). As shown in the latter figure, the first two driers I26 and I ZI are supplied with steam, as explained immediately above, in parallel by a common supply'pipe I15. The two con: densate removal pipes t lt join the pipe Ill? in parallel and deliver steam and condensate to the flash tar or trap Hi8. From this point, the condensate leaves by a pipe I I 6 and steam is delivered therefrom by a pipe Ill. The two steam discharge pipes IM from the first pair of driers are connected by a pipe M8 to the pipe ill, from which point, by a second pipe H9, steam is delivered to the next pair of rolls I 22 and 523, in parallel in the same manner as in connection with driers I29 and MI. Condensate is removed from driers E22 and iZS by pipe and pipe It'ia to the second flash tank Hits. Steam discharged from driers I22 and I23, through pipes I I 4a joins the steam from flash tank Etta and is delivered to the next pair of driers i22 and E25 in parallel by a pipe H917.

Assuming that the driers I24 and I25 are the last pair in the line, condensate and, possibly, some steam is discharged through pipes IllIib and iil'ih to the final flash tank "38b.

Marked economy in steam consumption is eifected by this system of steam distribution and conden ate separation. It has been found particularly advantageous to have the steam space, between the shell and the inner surface of the cast iron rim, of progressively decreasing radial di. from the first pair of driers in the line, to the last. For instance, the steam space in the pair or" driers may be 2 i ches; in the sound pair, 1% inches, and in the third pair,

nch. lctual tests have shown that, when steam at s. i. pressure is delivered to pipe M5, the t .air of driers effect a heat transfer of 89,654

the next pair .3 s. l

of driers, the pressure is of 900,669 13. t. u..s final pair, the pres- 2.5 p. s. i., with a heat transfer of 908,735

The heat loss in such a system is small, as compared with conventional systems, in most of which the steam flows from -ouree, in parallel, through all of the driers l' line. By making the steam space progresely smaller and by effecting a high velocity ow of steam, the heating medium may be conucted in series to successive pairs of driers and normally lost in the steam traps or units returned to the line.

it is highly desirable in most instances, to prevent the escape of steam with the discharge of or to limit the amount of steam so discharged. Hence, the water rimming the bottom of the circumferential channel 53 should substantially seal the open end of the suction per hour; the pressure drop is such nozzles or scoops disposed therein. Since the rate of accumulation of condensate in the channel varies in accordance with a number of factors, it is advantageous to make the mouth of each scoop or nozzle adjustable, to restrict the flow of liquid thereinto and to vary the height of the upper lip from the bottom of the channel.

A preferred embodiment of such an adjustable nozzle or scoop is shown in Figures I l-16. Referring to Figure 14, the nozzle is in the form of a flattened casting 53G, terminating at its inner end in a hollow centrally tapped boss I3I, into which one of the pipes, as pipe 67, is threaded. The casting formed with a socket I32 in its upper or radially inner surface, in which the positioning rod a? is seated. The lower or radially outer lip fill may be secured in place by a pin I3 3 extending through the outer shell 21 and bearing against the inner surface of rim 20.

Interiorly secured to the lower surface of the upper lip I35 is a flexible stainless steel, spring lip I35, having an upwardly curved end I37. A screw I38, threaded in the forwardly projecting portion I35 of the nozzle Isl], carries at its upper end a worm follower I39, in mesh with a worm Hill journalled in a bracket Isl, positioned between spaced washers pinned to the screw I 38. The worm is fast on a shaft M2, extending axially of the drier and, if desired, projected through one of the heads thereof, in steam tight relation, for ready manipulation from the outside. By rotating the shaft I 52, the screw I 38 may be projected into contact with the spring lip I 35, to depress the same, more or less, toward the lower lip I 33, thereby to vary the size of the effective opening between the upper and lower lips.

It should be noted that the side walls M3 and i iof the nozzle project forwardly beyond the upper and lower lips and engage the side edges of the adjustable lip I38 with a fairly close, sliding fit.

It will be understood that the amount of condensate formed in each drier will depend upon the amount of heat transferred from the drier to the material being dried, such as the web of paper, in a paper making machine. This rate of transfer, in turn, is controlled by a number of variable factors, such as the steam pressure employed, the speed of rotation of the driers, the moisture content of the paper web, and the like. By manipulating the several worm carrying shafts I42, the movable lips associated with the suction scoops or nozzles may be adjusted so that a water seal in the or well is provided, of

condensate as rapidly as formed, and preventing the building up of excess amounts of condensate in the channels or wells.

The inclined vanes or fins 2t-3l in the spaces between the outer shell and the inner surface of the cast iron drier are inclined forwardly and outwardly in the direction of rotation of the drier so that their leading edges are adjacent the surface of the drier and their trailing edges adjacent the outer surface of the shell. The vanes are also to end, with their leading ends nearer to the heads of the drier and their trailing ends nearer to the mid-section. The apertures 33 in the shell are positioned in alignment with the inner, leading surfaces of the vanes adjacent the trailing edges thereof. The deflector members 4| and 42, projecting inwardly from the shell, are positioned behind the apertures 33. The scooping action of the vanes, the influence of gravity, and the tendency of the condensate to lag behind the movement of the rim causes the condensate to flow in the V-shaped space between the outer surface of the shell and the leading face of each vane, lengthwise of the vane until one of the apertures 33 is encountered, whereupon the condensate is discharged into the interior of the shell. The condensate flowing along the inner surface of the shell encounters the inclined deflector strips M and 42 and is caused to flow along the leading faces thereof, toward and into the central well 56. The condensate is removed from the well 56 by the suction scoops previoush described.

The periodic removal of condensate from the steam chambers or spaces between the shell and the rim, during each upward movement of the vanes and steam spaces, and the periodic covering and uncovering of the holes in the inner shell leading to the interior, results in a pulsating action and a periodic drop in pressure in the steam spaces, with consequent flashing of minute particles of condensate on the inner surface of the drier rim, which enhances the scouring action and eliminates the fllm of condensate normally present in other constructions, and which always has a high heat insulating effect. Hence, transfer of heat from the steam to the drier surface is improved.

The form of condensate removal scoop shown in Figures 17 and 18 is preferred in some cases, for the sake of cheapness and simplicity of fabrication. It may be made of sheet metal parts, out and bent to the desired shape and welded together. Disposed between the side walls and lla of the trough or well are a pair of parallel, radially disposed attaching plates I53, iEl, hav ing apertures I52 and I53 therein, by which they may be secured to the well. Welded to the rear ends of the plates E56 and ISI are a pair of inwardly converging side plates IN and I55, connected at their rear ends to an apertured end plate I56. The outer edges of the plates ms, 555, and I56 lie against the bottom of the trough, in contact with the shell 2?. The scoop structure is completed by an inner, top plate I68, welded to the side plates I55 and 55 and to the rear plate I56, and inclined outwardly and downwardly toward the bottom of the circumferential trough to a line I56, the outer or undersurface of which is spaced an accurately predetermined distance from the bottom of the trough. From this line forwardly, the plate 58 diverges from the trough bottom and inclines upwardly or in wardly to its forward edge I56, which is aligned with the edges of the side walls file and dim. The side edges of the forwardly and inwardly inclined portion of the top plate E58 are preferably welded to the attaching plates Hill and I5I.

The leading portion of the scoop acts as a mouth to receive condensate, while the restricted, slot-like opening below the transverse line I58 acts as a seal to prevent the escape of undue amounts of low quality steam. The condensate removal pipe 61a, may have its end welded to the margins of the aperture in the plate I56.

In Figures 19, 20, and 21, a modified form of drier shell is shown. The steam delivery headers and pipes, the central shaft, the condensate removal scoops and pipes, and many other parts have been omitted, to simplify the showing, but it should be understood that the arrangements shown in the other figures of the drawings, or any above. Openings I6'I are 12 other appropriate construction may be employed with this form of shell.

The purpose of this modification is to effect a substantially uniform velocity steam flow within each of the heat transfer spaces or compartments, between each shell section and the drier rim, from the leading end to the trailing end thereof or, in other words, from the points where steam is delivered to the compartments to the points where the condensate flows inwardly to the interior of the shell. This substantially constant rate of steam flow is effected by decreasing or tapering the radial depth of each compartment, from the leading to the trailing end thereof.

It will be remembered that the pressure on both sides of the shell is equal. The removal of the latent heat from the steam in its passage through the spaces between the shell and the rim results in a reduction in the volume of the steam. If the compartments are of constant transverse cross-sectional area from end to end, the velocity of steam flow is decreased as the volume decreases. By the expedient of constantly decreasing the cross-sectional area of each compart- I ment, in the direction of steam flow the reduction in volume is compensated for, and a substantially uniform velocity of steam flow may be effected.

Within the cast iron rim I66 is a substantially cylindrical shell I6I, made up of a plurality of individual sections I62, each having its axial ends secured to circular flange members I63 and I64. The leading trailing ends of each section I62 are angularly disposed with respect to axial planes of the rim. The leading end of each section I62 is inwardly disposed in lapping relation to the trailing end of the next section, as clearly shown in Figure 21 and a filler strip I65 is preferably interposed therebetween, to space each leading edge a substantial distance, radially inwardly from the trailing edge of the adjacent section.

Projecting outwardly from the trailing edge of each shell section is a vane I66, which may be identical to the corresponding elements described formed along the trailing edge of each shell section, adjacent the leading face of each vane I66.

Disposed inwardly of the shell are a plurality of angle strip deflectors I68, each secured to the leading edge of one of the shell sections I62, so that the deflectors are arranged angularly with respect to axial planes of the drier. The inner flanges I69 of each strip project forwardly, in the direction of rotation of the drier.

A condensate collecting well of the type described above may be provided within the shell, or a well may be formed adjacent one end of the drier, constituted by an inwardly projecting, circumferentially extending strip I76, adjacent the trailing ends of the deflectors I68. The strip is provided with a plurality of apertures HI, registering with the spaces adjacent the leading faces of the deflectors, at the trailing ends thereof, for the flow of condensate through the strip into the well.

Steam delivery nipples I12 extend through the shell sections at the leading ends thereof, as previously described and these nipples may be connected to steam supply pipes in the same manner.

By reference to Figures 19 and 20, it will be seen that the heat transfer spaces or compartments I15 are of tapering radial depth from their leading ends, adjacent the steam delivery nipples I72, to their trailing ends, where the holes I61 are located. This construction is particularly adpressure steam.

The operation by the nipples F2. The steam flows through the spaces I 7'5 toward the trailing ends and gives up resulting in a reduction of its quallty and volume. Condensate is scooped inwardiy by the vanes [66 and flows by gravity through the openings I61. The deflectors I58, which are inclined with respect to the axis of the drier impart longitudinal movement to the condensate, from their leading, right hand ends to their trailing left hand ends (Figure 19). The condensate flows through the wall I10 into the well at the left end of the drum, where it is removed by scoops, similar to tions shown and described from Figures 19 and 20.

It must be understood that the invention is not iimite coming within the scope of the appended claims and their equivalents.

We claim:

1. A drier comprising a pair of rotatable heads and a cylindrical rim carried thereby and defining an enclosed interior, a cylindrical shell spaced from the inner surface of the rim, a plurality of longitudinally extending vanes projecting outwardly from the shell substantially into contact surface of the rim and dividing plurality of longitudinally excompartments, means for delivering each of said compartments, and means for conducting condensate radially inwardly through said shell from each compartment adjacent the leading face of the trailing vane thereof.

2. A drier comprising a rotatable, cylindrical rim, a cylindrical shell spaced from the inner surface of the rim, a plurality of longitudinally extending, forwardly pitched the space into a tending a plurality of longitudinally extending compartments, a plurality of apertures in the shell adjacent the leading faces of said vanes for the inward flow of condensate from the associated compartment under the influence of gravity and scooping action and means for delivering steam to each compartment.

3. A drier comprising a rotatable, cylindrical rim, a cylindrical shell spaced from the inner surface of the rim, a plurality of longitudinally extending, forwardly pitched vanes projecting the shell in contact with said surface and dividing the space therebetween into a plurality of longitudinally extending compartments, a plurality of apertures in the shell adthe leading faces of said vanes for the inscooping action and a plurality of conduits ex tending through the shell adjacent the trailing rim, a cylindrical shell spaced from the interior surface of the rim, a plurality of longitudinally extending vanes projecting outwardly from the shell into engagement with said surface of the said shell having a plurality of apertures therein adjacent the leading faces of the vanes, for the inward gravity flow of condensate engaged by the vanes, and means for delivering steam to the space between the rim and shell adjacent the trailing faces of said vanes.

5. A drier comprising a rotatable, cylindrical rim, a cylindrical shell spaced from the interior surface of the rim, a plurality of longitudinally extending vanes projecting outwardly from the shell into engagement with said surface of the rim and disposed in angular relation to axial sections of the rim and shell, whereby longitudinal flow is imparted to condensate engaging the same, said shell having a plurality of apertures therein adjacent the leading faces of the vane for the inward gravity flow of condensate engaged by the vanes, means disposed inwardly of the shell for collecting condensate flowing through said apertures, means for conducting the same from the collecting means to the exterior of the drier and means for delivering steam to the space between the rim and shell behind the trailing faces of said vanes.

6. A drier comprising a rotatable, cylindrical rim, a cylindrical shell spaced from the interior surface of the rim, a plurality of longitudinally extending vanes projecting outwardly from the shell into engagement with said surface of the rim and disposed in angular relation to axial sections of the rim and shell, whereby longitudinal flow is imparted to condensate engaging the same, said shell having a plurality of apertures therein adjacent the leading faces of the vanes, for the inward gravity flow of condensate engaged by the vanes, and means for delivering steam to said space behind each of said vanes.

7. A drier in accordance with claim 5, in which said condensate collecting means comprises an inwardly facing, circumferential channel.

8. A drier comprising a rotatable cylindrical rim, a cylindrical shell spaced from the interior ing steam compartments, each vane of each group being disposed in angular relation to axial se tion of the rim and shell, said shell having apertures therein adjacent the leading faces of the vanes for the inward flow of condensate engaged cumferentially on the inner surface of the rim, to impart longitudinal movement thereto, means defining a clrcumferentially extending Well for receiving the longitudinally flowing condensate, and suction means in the well for removing the condensate therefrom.

9. A drier comprising a rotatable cylindrical 15 of the rim, said vanes being arranged in a plurality of longitudinally extending, interconnected groups, dividing the space between the shell and the rim into a plurality of longitudinally ex ending steam compartments, each vane of each group being disposed in angular relation to axial sections of the rim and shell, said shell having apertures therein positioned at the trailing end of the leading faces of the vanes for the inward flow of condensate engaged by the vanes, means to engage the condensate flowing inwardly through the apertures and circumferentially on the inner surface of the rim, to impart longitudinal move ment thereto, means defining a circumferentially extending well for receiving the longitudinally flowing condensate, and suction means in the well for removing the condensate therefrom.

10. A drier comprising a rotatable cylindrical rim, a cylindrical shell Spaced from the interior surface of the rim, a plurality of forwardly and outwardly pitched vanes projecting from the surface of the shell in contact with the inner surface of the rim, said vanes being arranged in a plurality of longitudinally extending, interconnected groups, dividing the space between the shell and the rim into a plurality of longitudinal" ly extending steam compartments, each vane of each group being disposed in angular relation to axial sections of the rim and shell, said shell having apertures therein for the inward flow of condensate engaged by the vanes, a plurality of angularly disposed deflector bafile strips projecting inwardly from the shell behind the apertures to receive and engage the condensate flowing inwardly through the apertures and circumferentially on the inner surface of the rim, to impart longitudinal movement thereto, means defining a circumferentially extending well for receiving the longitudinally flowing condensate, and suction means in the well for removing the condensate therefrom.

11. A drier comprising a rotatable cylindrical rim, a cylindrical shell spaced from the interior surface of the rim, a plurality of forwardly and outwardly pitched vanes projecting from the surface of the shell in contact with the inner surface of the rim, said vanes being arranged in a plurality of longitudinally extending, interconnected groups, dividing the space between the shell and the rim into a plurality of longitudinally extending steam compartments, each vane of each group being disposed in angular relation to axial sections of the rim and shell, said shell having apertures therein adjacent the leading faces of the vanes for the inward flow of condensate engaged by the vanes, means to engage the condensate flowing inwardly through the apertures and circumferentially on the inner surface of the rim, to impart longitudinal movement thereto, inwardly projecting flange means at the ends of said baiile strips defining a circumferential well, said flange means being apertured to receive the longitudinally flowing condensate, and suction means in the well for removing the condensate therefrom.

12. A drier comprising a rotatable, cylindrical rim, a cylindrical shell spaced from the interior surface of the rim, a plurality of forwardly and outwardly pitched vanes projecting from the shell into contact with the inner surface of the rim,

said vanes being arranged in longitudinally extending, interconnected groups extending in opposite directions substantially from the mid-section of the drier toward the ends and dividing the space between the shell and the rim into a plurality of longitudinally extending compartments, each vane in each group being disposed in angular relation to axial sections of the rim with its leading end nearer to the adjacent drier head and its trailing nd nearer to the mid-section, said shell having apertures therein adjacent the leading faces of the trailing ends of the vanes for the inward flow of condensate engaged by the vanes, and means within the shell for collecting and removing the condensate.

13. In combination with a cylindrical, rotatable drier having a closed interior, means spaced from the inner cylindrical surface thereof defining a circumferential space of relatively small radial dimension, means for delivering steam to said space at a plurality of spaced points, means for conducting condensate from said space and for causing the same to flow inwardly therefrom through the first mentioned means, deflector means for receiving the inwardly flowing condensate and for causing the same to flow longitudinally of the drier, means for collecting the longitudinally flowing condensate, and means for discharging the collected condensate from the drier.

14. A drier comprising a rotatable cylindrical rim, a substantially cylindrical shell spaced from the inner surface of the rim, a plurality of longitudinally extending, forwardly pitched vanes projecting outwardly from the shell in contact with said surface and dividing the space therebetween into a plurality of longitudinally extending compartments, a plurality of apertures in the shell adjacent the leading faces of said vanes for the inward flow of condensate, said shell having its outer surface disposed to give each of said compartments a tapering radial depth from its leadlllg end, circumferentially towards its trailing ends.

15. A drier comprising a rotatable, cylindrical rim, a substantially cylindrical shell spaced from the interior surface of the rim, a plurality of longitudinally extending vanes projecting outwardly from the shell into engagement with said surface of the rim and disposed in angular relation to axial sections of the rim and dividing the space therebetween into a plurality of longitudinally and angularly extending compartments, and means for delivering steam to said compartments at the leading ends thereof, behind the trailing faces of said vanes, said shell having a plurality of apertures therein at the trailing ends of said compartments adjacent the leading faces of the vanes for the inward flow of condensate engaged by the vanes, said compartments being of tapering radial depth, from their leading ends in a circumferential direction toward their trailing ends.

16. A drier comprising a rotatable, cylindrical rim, a substantially cylindrical shell spaced from the interior surface of the rim, a plurality of longitudinally extending vanes projecting outwardly from te shell into engagement with said surface of the rim and disposed in angular relation to axial sections of the rim and dividing the space therebetween into a plurality of longitudinally and angularly extending compartments, means for delivering steam to said compartments at the leading ends thereof, behind the trailing faces of said vanes, said shell having a plurality of apertures therein at the trailing ends of said compartments adjacent the leading faces of the vanes for the inward flow of condensate engaged by the vanes, means to engage the condensate flowing inwardly through the apertures and to impart longitudinal movement thereto, means defining a circumferentially extending well for re- 17 ceiving the condensate from the last mentioned means and suction means in the well for removing the condensate therefrom, said compartments being of tapering radial depth, from their leading ends in a circumferential direction toward their trailing ends.

17. A drier comprising a rotatable, cylindrical rim, a substantially cylindrical shell spaced from the interior surface of the rim, said shell comprising a plurality of longitudinally and angularly disposed sections with the leading edge of each section disposed inwardly in lapping relation to the trailing edge of the adjacent section, to provide a space between each shell section and the rim of tapering radial depth from the leading edge to the trailing edge, a plurality of longitudinally and angularly extending vanes connected to the trailing edges of the shell sections and projecting outwardly therefrom into engagement with the inner surface of the rim, dividing said space into a plurality of compartments, means for delivering steam to each compartment adjacent the leading end thereof, and openings in the shell sections adjacent the trailing ends of the compartments for the inward flow of condensate engaged by the vanes.

18. A drier comprising a rotatable, cylindrical rim, a. shell spaced from the inner surface of the rim and comprising a, plurality of curved sections disposed in eccentric relation to the said surface and each having its leading and trailing edges on longitudinally extending angularly disposed lines, the leading edge of each section extending in inwardly spaced overlapping relation to the trailing edge of the adjacent section, and a filler strip between each of said overlapping edges, thereby providing a space between each section and the inner surface of the rim of tapering radial depth from the leading to the trailing edge, a vane secured to the trailing edge of each shell section projecting outwardly into engagement with said rim surface and dividing said space into a plurality of compartments, means for delivering steam to each compartment adjacent the leading end thereof, and openings in the shell sections adjacent the trailing ends of the compartments for the inward flow of condensate engaged by the vanes.

References Cited in the file Of this patent UNITED STATES PATENTS Number Name Date 693,233 Chadwick Feb.11, 1902 700,776 Hunting May 27, 1902 1,084,677 Vedder Jan. 20, 1914 1,114,215 Woodsome Oct. 20, 1914 1,264,254 Aitken Apr. 30, 1918 1,413,480 Kingsley Apr. 18, 1922 1,575,615 Broughton Mar. 9, 1926 1,750,837 Farnsworth Mar. 18, 1930 2,150,132 Sandwell Mar. 7, 1939 2,433,121 Hornbostel Dec. 23, 1947 2,486,719 Messinger Nov. 1, 1949 2,498,662 Eaby Feb. 28, 1950 2,521,371 Hornbostel et a1. Sept. 5, 1950 FOREIGN PATENTS Number Country Date 17,564 Great Britain of 1908 18,155 Great Britain of 1913 189,725 Great Britain Dec. 7, 1922 OTHER REFERENCES Paper Trade Journal, Industrial Development Section, January 20, 1949,

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16 and 17.