US 3426839 A
Description (OCR text may contain errors)
Feb. 11, 1969 e. OVERTON 3,426,839
DRYING CYLINDER Filed Dec. 5, 1966 IN VENTOR. 64 0 1/5270 A TTORNE YS United States Patent 3,426,839 DRYING CYLINDER Glen Overton, Allegan, Mich. 49010 Continuation-impart of application Ser. No. 559,693,
June 22, 1966, which is a continuation of application Ser. No. 375,035, June 15. 1964, now abandoned. This application Dec. 5, 1966, Ser. No. 599,060 The portion of the term of the patent subsequent to Mar. 14, 1984, has been disclaimed U.S. Cl.165--89 7 Claims Int. Cl. F28f 02; F26b 11/02; F28d 7/00 ABSTRACT OF THE DISCLOSURE A dryer drum or drying cylinder heated eificiently and uniformly with internal steam jets closely adjacent the inside surface of the cylinder wall and fed with more steam than can be completely condensed in the cylinder to provide jet streams which mechanically scour the inner surface of the cylinder Wall to break up and remove condensate filnr thereby increasing the heat transfer through the cylinder wall and lessening the amount of condensate to be removed. Uncondensed steam i discharged from the cylinder for use elsewhere. The steam jets are provided by longitudinally extending pipes inside the cylinder closely adjacent the cylinder wall and carried by spoke pipes radiating from a central pipe or axle of the cylinder to revolve with the cylinder. The live steam is fed into this central axle or pipe through one end of the cylinder and exited at the other end of the cylinder. Pressure regulators maintain a desired differential steam pressure drop between the inlet and outlet ends of the cylinder.
RELATED APPLICATIONS This application is a continuation-in-part of my copending application Ser. No. 559,693 entitled, Drying Cylinder, filed June 22, 1966, now Patent No. 3,308,554 granted Mar. 14, 1967 which application in turn is a full continuation of my application Ser. No. 375,035 filed June 15, 1964 and now abandoned.
BACKGROUND OF THE INVENTION Field of the invention This invention pertains to the art of heating rotating drying cylinders or dryer drums with condensable fluids such as live steam and particularly to the art of using steam jets to scour the surface being heated for breaking up any condensate film on the surface to increase the heat transfer through the surface.
Description of the prior art In my aforesaid applications Ser. Nos. 559,693 and 375,035 the illustrated drying cylinders are equipped With stationary internal steam jet heating apparatus and steam is preferably fed into both ends of the cylinder with one end supplying the jets and the other end supplying the central interior of the drum with live steam. In some installations, however, the drying cylinder has a central pipe or axle extending therethrough in fixed relation to the end heads of the cylinder and of course this pipe or axle revolves with the cylinder. The present invention solves the problem of steam jet heating of such cylinders by using the central pipe or axle as a steam conduit, allowing the jet apparatus to rotate with the cylinder and lessening the condensate removal problem by exiting uncondensed steam from the cylinder for further use elsewhere.
3,426,839 Patented Feb. 11, 1969 SUMMARY The gist of the invention is to pass more steam through a drying cylinder than can :be condensed in the cylinder and to use this surplus steam as a mechanical scouring media to break up moisture films which might build up on the cylinder wall. The steam is released into the cylinder closely adjacent the cylinder wall in the form of a myriad of high pressure steam jets directed non-radially against the cylinder wall to scour the surface thereof free from condensate and to prevent formation of localized hot spots on the cylinder. The steam jets release the steam at angles of about 45 from the radius of the cylinder so that the jet streams will impinge against the cylinder wall at high velocity having both radial and circumferential force components thus providing a good scrubbing action on the cylinder wall. Each jet pipe may have two rows of jet openings so that the jet sprays will extend in nonradial directions on both sides of the pipe and have downward circumferential components to direct any condensate or moisture film to the bottom of the cylinder.
The jet pipes also have jet outlets at the ends thereof to direct jet streams against the very end edges of the cylinder for insuring complete heating of the entire length of the cylinder.
The central axle or pipe in the cylinder is preferably plugged near one end thereof to divide the interior of the axle into an elongated steam manifold for feeding the jet pipes and into a short exiting manifold for releasing the surplus steam from the cylinder. This short manifold can also receive the condensate pipe therethrough for removing the condensed steam from the bottom of the cylinder.
It is then an object of this invention to provide a dryer with steam jets closely adjacent the drying wall for inrpinging live steam non-radially against the wall to scour condensate films off of the wall and to lessen condensate rem-oval requirements by maintaining a steam pressure differential in the drum and exiting surplus steam for use elsewhere.
Another object of the invention is to provide a steam jet heater for drying cylinders equipped with central axles wherein the steam jet means are supported from the axles and rotate with the cylinders.
Another object of this invention is to provide a steam jet heating apparatus for drying drums which maintain a differential steam pressure in the drum to lessen condensate removal requirements.
A further and specific object of this invention is to provide a drying cylinder especially siutable for drying foodstuff such as milk, slurries and the like at high speeds and without local overheating wherein the heat is sup plied from live steam jets and the heating surface is scoured free from condensate films by the jets and the condensate is kept to a minimum by existing surplus steam.
Other and further objects will be apparent to those skilled in this art from the disclosures in the aforesaid applications and the hereinafter specific disclosures of preferred embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 is a somewhat diagrammatic longitudinal cross-sectional view, with parts in elevation, of a drying cylinder equipped with jet heating apparatus according to this invention;
FIGURE 2 is a transverse cross-sectional view taken along the line 11-11 of FIGURE 1;
FIGURE 3 is a transverse cross-sectional view similar to FIGURE 2 but showing added jet pipes; and
FIGURE 4 is an enlarged fragmentary cross-sectional view taken along the line IV 1V of FIGURE 1.
3 DESCRIPTION OF THE PREFERRED EMBODIMENTS The drying cylinder of FIGURES 1 and 2 has a cylindrical metal shell 11 with inturned end flanges 12, 12 and end heads 13, 13 secured to the flanges and provided with hollow journals 14 to rotatably support the cylinder. The end heads are connected by a central axle or reinforcing tubular pipe 15 extending through the central interior of the shell 11 and cooperating with the hollow interiors of the journals 14 to provide a central passageway 16 through the cylinder. A plug 17 is secured in this passageway 16 near one end head 13 and the axle or tube 15 is provided with ports 18 between the plug and this adjacent end head for joining the interior of the tube or axle with the interior of the cylinder.
The plug 17 divides the passageway 16 into an elongated steam inlet manifold 19 on one side of the plug 17 and a steam outlet manifold 20 on the opposite side of the plug 19.
The axle or tube 15 has central radial spoke pipes 21 extending from the midway thereof. Additional spoke pipes 22 extend radially from the axle or tube 15 adjacent the ends of the axle or tube. All of these spoke pipes communicate with the passage 19 provided by the axle or tube. These spoke pipes carry T fittings 23 at their outer ends which are positioned closely adjacent the inner surface of the cylinder 11. These T fittings support longitudinal jet pipes 24 which extend closely adjacent the cylinder wall from one end flange 12 to the other. The jet pipes may be sectioned to have screw thread connection with the Ts 23 but for descriptive purposes may be considered as single units extending longitudinally along the entire length of the drying cylinder.
In the form of the invention illustrated in FIGURES 1 and 2 four jet pipes 24 are provided in equally spaced relation in the drying cylinder and each of these four spray pipes is supported by the sets of central spoke pipes 21 and end spoke pipes 22. It will be understood however that any number of spoke pipes may be used depending on the length of the drying cylinder. For stability and equal steam distribution along the entire length of the jet pipe, it is preferred that at least two spoke pipes be used for each jet pipe and that they be located at or near the ends of the spoke pipe.
Each jet pipe 24 has two rows of jet openings or apertures 25 at closely spaced relation along the length thereof. These jet openings 25 as best shown in FIG- URE 4 are positioned to direct jet sprays 26 on each side of the radius R for the cylinder 11. As illustrated the jet streams 26 on one side of the radius R are at an angle A while the jet streams on the other side are at an angle B. These angles may be the same or different and are about 45 so that the jet streams 26 will impinge on the shell wall in non-radial directions but will have force components impacting the wall both radially and circumferentially to provide a good scrubbing action for breaking up the film of moisture on the wall.
The ends of the spray pipes 24 also have jet outlets 27 to eject jet sprays 28 toward the very ends of the shell 11. The end flanges 12 of the shell may be peripherally grooved at 29 to receive these sprays 28 for heating the shell up to the very ends thereof.
A steam inlet supply pipe 30 at the left-hand end of the cylinder in FIGURE 1 supplies live steam to the through passage 16 where the plug 17 confines it to the passageway portion 19. This inlet 30 has a shut-off valve 31, a pressure regulator valve 32 downstream from the shut-off valve, a control 33 for the regulator 32, an indicator gauge 34 for the pressure regulator and blow-off valves 35 and 36 on the upstream and downstream sides respectively of the pressure regulator. A rotary steam joint 37 connects the steam inlet with the hollow journal 14 of the adjacent 9 1d head 13 and steam at the desired pressure under the control of the regulator 32 as set by the control 33 is thus fed into the passageway portion 19 for flow through the spoke pipes 21 and 22 to the four jet pipes 24 and thence through the orifices 25 thereof to form the jet streams 26 and 28.
A condensate removal siphon tube 38 is carried by the central axle or pipe 15 beyond the plug 17 and extends through the passage 20. The siphon tube 38 is closely adjacent the end head and has an inlet end 39 closely adjacent the shell 11 positioned to scoop up condenate water on the ascending side of the shell 11 as best shown in FIGURE 2. The siphon tube 38 extends through the journal 14 and into a rotary steam joint 40.
Surplus steam and water removal apparatus is provided at the right-hand end of the cylinder 10 and includes a fitting 41 on the journal 40 receiving condensate from the outlet end 42 of the siphon tube 38 and also receiving surplus steam from the passageway 20. The condensate water is drained through a pipe 43 to a trap. The surplus steam is received by a steam outlet pipe 44 with a back pressure regulating valve 45 the pressure of which is controlled by a regulator 46 as indicated by an indicator -47. Shut-off valves 48 and 49 are provided respectively on the upstream and downstream sides of the regulator valve 45. A relief valve 50 is provided in the steam outlet line 44 on the upstream side of the regulator 45.
The end heads 13 for the shell 11 have access holes 51 therein caused by covers 52 when the apparatus is in operation.
-In the embodiment shown in FIGURE 3 the drying cylinder 10 is equipped with twice the number of jet pipes as is shown in FIGURE 2. In this arrangement the eight jet pipes 24 are spaced equally around the interior of the shell 11 and are each supported by the central spoke pipes 21 and the end spoke pipes 22. From this it will be understood that any desired number of jet pipes can be used to meet conditions.
OPERATION OF THE DEVICE The drying cylinder 10 may be used alone or in combination with identical cylinders to provide single or twin drum drying apparatus. The material to be dried is fed to the periphery of the shell 11 and the dried film is scraped from this periphery as is conventional. The capacity of the dryer of course depends on the speed of removal of the liquid content of the material being dried without damaging the end product. The device of this invention by efiiciently and uniformly heating the shell 11 .has materially speeded up the drying operation of drum dryers and dryers equipped with the heating apparatus of this invention have increased production as much as onethird without increasing the cylinder sizes.
In operating the device of this invention steam at a selected predetermined pressure, preferably in the range of to lbs. per square inch is fed from the inlet 30 into the passageway portion .19 where it is distributed by the spoke pipes 21 and 22 to the jet pipes 24. These spoke pipes are positioned so that each jet stream 26 emerging from the jet pipes 24 will have the same velocity and will impinge on the dryer shell as shown in FIGURE 4 with force components both radially and circumferentially to efliciently scour the shell and remove moisture film therefrom. The dryer 10 and the heating apparatus in the dryer all rotate together in a clockwise direction as indicated in FIGURE 2 and While the jet streams 26 thus are in fixed relation to the shell 12 they nevertheless span a sufficient area of the shell so as to coact with the streams from the next adjacent spray pipes in a manner to equally heat the entire circumference of the shell.
The steam outlet apparatus is regulated so that a deseired steam pressure is maintained in the drum. The jets supply suificient steam to maintain the set back pressure. Outlet pressures of from 60 to 100 lbs. per square inch are preferred when the inlet pressure is from 100 to 140 lbs. per square inch. Thus differential steam pressures of about 45 lbs. per square inch are maintained, although it should be understood that the regulating valves 32 and 45 can be controlled to maintain any desired steam pressure in the drum.
The surplus steam in the drum flows through the ports 18 into the passageway 20 and thence to the steam outlet 44,
Some condensate is desired to obtain the latent heat of the condensation of steam for transfer through the shell 11 and this condensate is removed by the siphon tube 38.
It will therefore be understood that the heating of the shell 11 is obtained by differential steam pressure which is maintained in the drum and also by the latent heat released in the condensation of some of the steam. It will also be understood that the steam jets scour the walls of the shell 11 to at least partly remove the condensate film thereon and thereby greatly enhance the heat transfer through the shell to the material being dried on the shell. It will also be understood that the heating apparatus of this invention revolves with the drum and is carried by the axle or central pipe of the drum.
It will be understood that variations and modifications may be effected without departing from the spirit and scope of the novel concepts of this invention.
-1. A drying apparatus which comprises a cylindrical shell, end heads closing the ends of the shell, journals on the end heads for rotatably supporting the shell, a central pipe extending axially through said shell and attached to said end heads, a plug in said pipe adjacent one end head dividing the interior of the pipe into an elongated steam inlet passage and a short steam outlet passage, ports in said pipe joining the interior of said shell with said outlet passage, a siphon tube extending through said steam outlet passage and having an inlet end for removing condensate from the shell, spoke pipes radiating from said central pipe communicating with the steam inlet passage, jet pipes carried by the outer ends of the spoke pipes closely adjacent the shell and extending along the full length of the shell, said jet pipes having outlet apertures positioned to direct steam jets in non-radial directions for scrubbing and heating the shell wall, means for introducing steam under controlled pressure into the steam inlet passage for discharge through the spoke pipes and jet pipes, means for removing steam from the steam outlet passage, means for maintaining the steam outlet pressure at a predetermined differential relative to the steam inlet pressure, and means for separating the condensate from the exiting steam.
2. A drying apparatus which comprises a rotatable horizontal dryer drum having a cylindrical shell, end heads closing the ends of the shell and hollow journals projecting from the end heads for rotatably supporting the drum, a central pipe fixed to the end heads and extending through the drum in full communication with the hollow journals, a steam inlet connected to one of said hollow journals, a steam outlet connected to the other of said hollow journals, means dividing said pipe into an elongated passage communicating with the steam inlet and a short passageway communicating with the steam outlet, spoke pipes radiating from the central pipe communicating with the inlet passage, longitudinal jet pipes carried by the outer ends of the spoke pipes closely adjacent the cylinder wall, said jet pipes having jet outlets along the lengths thereof positioned to direct steam jets in non-radial directions against the cylinder wall, a condensate siphon tube depending from the central pipe and extending through the outlet passage portion thereof, said steam inlet supplying live steam to the inlet passage at a predetermined pressure, said steam outlet maintaining a desired back pressure in the steam outlet portion of the pipe and means for separating condensate from surplus steam in the steam outlet.
3. A dryer drum which comprises a cylindrical shell, end heads closing the ends of the shell, hollow journals projecting from the end heads, a hollow axle for said drum secured at its ends to said end heads and cooperating with said hollow journals to provide a through passage in the center of the drum, a plug in said axle dividing said through passage into a steam inlet portion and a steam outlet portion, said steam outlet portion having ports communicating with the interior of the drum, means for feeding live steam into the steam inlet portion of the axle, spoke pipes carried by the axle and radiating therefrom for receiving steam from the steam inlet portion thereof, longitudinal jet pipes carried by the outer ends of the spoke pipes for ejecting the steam in nonradial directions against the interior of the shell, steam outlet control means communicating with the steam outlet portion of said axle to maintain a desired steam back pressure in the drum, and a condensate removal tube extending through one of said journals for removing condensate from the interior of the drum whereby the shell is heated with live steam, surplus steam is removed from the drum, and condensate water is removed from the drum.
4. Heating apparatus for a drum dryer having a hollow central axle extending therethrough which comprises spoke pipes radiating from said axle for receiving live steam therefrom, jet pipes carried by the outer ends of the spoke pipes closely adjacent the drum, means for feeding live steam into one end of the axle, means for removing excess steam from the other end of the axle, and steam control means for maintaining a live steam pressure differential between the steam inlet portion of the axle and the steam outlet portion of the axle.
5. The drying apparatus of claim 1 wherein from four to eight jet pipes are provided in the shell.
6. The drying apparatus of claim 1 wherein each jet pipe has a central spoke pipe and two end spoke pipes.
7. The drying apparatus of claim 1 wherein each jet pipe has two spaced rows of outlet apertures along the length thereof positioned for discharging jet sprays at angles of about 45 relative to the radius of the shell.
References Cited UNITED STATES PATENTS 1,189,761 7/1916 White 34-124 1,768,777 7/1930 Muller 34-124 2,599,346 6/1952 Oflen -89 2,885,790 5/1959 Cram 165-89 X 2,772,075 11/ 1956 Mayer 165-89 3,308,554 3/1967 Overton 34-124 ROBERT A. OLEARY, Primary Examiner. THEOPHIL W. STREULE, Assistant Examiner.
US. Cl. X.R. 34-124