US2993282A - Dryer drainage control - Google Patents

Description

July 25, 1961 R. A. DAANE ET AL 2,993,282

DRYER DRAINAGE CONTROL Filed Sept. 19, 1957 llb ld l8 2 i; FE WE Haber! A. Dame Edgar cl Jusfus of Wisconsin Filed Sept. 19, 1957, Ser. No. 684,873 5 Claims. (Cl. 34-125) The present invention relates to a dryer drum, and more particularly to a dryer drum having an improved drainage system.

As conventionally employed in the art, dryer drums for paper machine drying sections generally consist of a cylindrical shell, spaced heads extending radially across the shell to close the open ends thereof and carrying means for journalling the shell for rotation, and means for introducing a heat exchange fluid into the interior of the shell. Since steam is the heat exchange fluid normally employed, means are also provided for removing the aqueous condensate from the interior of the drum during use.

In general the condensate removal assembly comprises a drainage outlet mounted in one of the heads and a dipper connected to such drainage outlet within the drum and extending radially therefrom to closely spaced relation to the inner periphery of the drum. A thin layer of film of condensate tends to build up rather uniformly on the inner periphery of the rotating drum, and the dipper is mounted with its mouth in closely spaced relation to the inner periphery. The pressure differential between the drum interior and the exit of the drainage line drives the condensate up to the dipper and out the drainage line. This pressure differential must, of course, overcome centrifugal forces acting upon the water in the dipper tending to flow the water or condensate back out of the dipper and into the drum. At very high speeds this creates a problem, particularly when a drum tends to load up or fill up with condensate.

The instant invention provides a novel dipper structure having a small aperture or orifice therein near to but spaced from the condensate-receiving mouth in closely spaced relation to the inner periphery of the shell. Live steam from within the drum or shell enters this orifice and mixes with condensate within the dipper conduit, so as to materially reduce the density of the material within the dipper conduit and thereby reduce the effect of centrifugal force upon the steam condensate mixture being forced up the dipper and into the drainage outlet.

The instant arrangement not only aifords advantages by reduction in the density of the liquid-vapor mixture passing through the dip-per, but it also permits the positioning of the dipper mouth much closer to the inner periphery of the shell (so that the condensate level along the inner periphery of the shell can be maintained at a minimum). The difficulties resulting from flooding of the shell with condensate so as to completely submerge the dipper mouth are, of course, overcome by the use of the instant steam orifice. Therefore, much less pressure diiterential, between the pressure within the dryer and the pressure on the drainage system, is required to effect the removal of water.

Other and further objects, features and advantages of the present invention will become apparent to those skilled in the art from the following detailed disclosure thereof and the drawings attached hereto and made a part hereof.

On the drawings:

FIGURE 1 is a fragmentary sectional view with parts shown in elevation taken along the longitudinal axis of rotation of adryer drum of the present invention, showing one end only of such dryer drum; and

FIGURE 2 is an enlarged detail view of the dipper Patented July 25, 1961 month and associated steam orifices taken substantially along the line IIII of FIGURE 1.

As shown on the drawings:

In FIGURE 1, the reference numeral 10 indicates generally a dryer drum of the present invention, showing essentially one end thereof, comprising a cylindrical shell 11 having open ends (only one of which is shown) closed by heads 12 (only one of which is shown) atfixed thereto by suitable means such as bolts (not shown) and extending radially thereacross. The heads 12 mount concentric journals 13 (only one of which is shown) for rotatably mounting the shell 11. The journal 13 is a hollow journal through which steam from a source S may be fed into the interior of the drum 10. As here shown, the steam enters through a non-rotating head element sealingly engaging the journal 13 and then through the hollow journal 13 into the drum 11. The steam inlet head 14 concentrically mounts a drainage outlet 15 which, in turn, mounts a syphon 16 by means of a pipe joint 17 at the interior end of the drainage outlet 15. The syphon or syphon pipe 16 extends generally radially outwardly from the drainage conduit 15 to closely spaced relation to the inner periphery 11a of the shell 11. In general, the arrangement just described is old and well known in the art, in that dryer drums are known wherein steam is fed through a steam inlet 14- in one of the heads 12 and condensate is removed through a drainage conduit 15 also in one of the heads 12. It is also well known to employ a syphon assembly connected to the drainage conduit 15, such as the syphon assembly 16 which extends to close running relation to the inner periphery 11a of the shell 11.

The novelty in the instant arrangement, however, resides in the particular construction of the syphon 16, and more specifically, the particular construction of the syphon mouthpiece 16a carried at the end of the syphon pipe 16b, as shown in detail in FIGURE 2 herein. It will be appreciated that the syphon 16 rotates with the shell 11, so that a rotating joint is employed at the pipe joint 19 or at a connection between the drainage conduit 15 and the drainage disposal system indicated diagrammatically at D in FIGURE 1. Again, the particular method of mounting the syphon 16 for rotation is not important, or is at least well known in the art so it need not be described in greater detail herein. The syphon 16 may extend in direct radial alignment as here shown, or it may extend in general radial alignment along an arcuate path, for example, as is shown in Lloyd Hornbostel US. Patent No. 2,651,114. In any event, it extends to closely spaced relation to the shell periphery 11a, such space being indicated by s in FIGURE 2. The syphon pipe 16b mounts a syphon mouthpiece or dipper element 16a at its outer end and the dipper element 16a has a generally frusto-conical skirt at its outer extremity, the skirt 16c opening to form the open extremity of the mouth 16d for the syphon 16. Liquid condensate collects at a substantially uniform level L around the entire inner peripheral 11a of the shell 11 because of centrifugal force during movement of the shell 11 in the rotation thereof. As here shown, the mouth 16d of the skirt portion 160 is mounted at approximately this level L. One advantage of the instant invention is that the mouth 16d may be positioned such a short space s from the shell periphery 11a, that it is beneath the normal level L of the condensate. Under ideal operating conditions, the condensate level will be maintained at the thickness s, because the syphon 16 will be removing water from the shell 11 as rapidly as it passes beneath the skirt 16c. Actually, the operating level L can be just slightly less than the space s. In this way, it may be advantageous to have a small amount of steam pass beneath the skirt 160 with the water and pass up the syphon 16 also with the condensate. However, if the level L even momentarily rises above the space s, then only water enters into the mouth 16d and the syphon 16 would tend to become filled with water. Removal of this water from the syphon 16 into the drainage conduit 15 and into drainage dis 'posal D would require a distinct large pressure differential between the steam pressure within the shell 11 and the pressure at the drainage disposal D.

In addition, the full leg of water within the syphon 16 would be subject to centrifugal force and there would be a substantial amount of force urging the water in the syphon 16 back out through the mouth 16a. This is overcome in the practice of the instant invention by the use of a plurality of steam orifices 162, 16 closely spaced from the mouth 16d radially inwardly in the syphon 16 (or actually in the syphon mouthpiece 16a). As will be appreciated, the instant device employs a plurality of steam orifices 162, etc. spacedl80 apart, although only a single orifice may be employed in the practice of the instant invention. The arrangement here shown has been found to be most advantageous. The orifices 162, 16 etc. are positioned so as to be disposed at an angle to the axis of the mouthpiece 16a, or to be disposed at an upward incline. The incline is radially inwardly in the direction of liquid fiow or radially inwardly with respect to the syphon 16. This is advantageous in that the steam entering the orifices 162, 16 etc. mixes most advantageously with the condensate therein and thus materially reduces the density of the mixture of condensate and steam within the syphon 16. This, in turn, reduces the effect of centrifugal force tending to throw condensate the mouth 16d and the inner shell periphery 11a, because flooding (or increasing of the level L above the space s) 'does not result in operational difiiculties. The steam still enters through the orifices 162, 16 and the advantages of the use of a mixture of steam and condensate in the syphon 16 are obtained. The additional advantage here is that a very small space s may be used so that under relatively slow operating conditions an extremely low level L of condensate is obtained. As will be appreciated, the less condensate the better within the shell 11, because condensate interferes with heat transfer from the live steam to the outer periphery 11b of the shell 11.

Although the manner in which the orifices are mounted may be vanied in the practice of the instant invention, the instant orifices 162, 16 have been found to be most advantageous. In the instant arrangement, a scoop 17 secured to the shell by bolts (not shown) is also secured to the syphon mouthpiece 16a to mount the same in the desired position. The scoop 17 is mounted with an open mouth in the direction of travel of the roll (FIGURE 2). Also, a partition wall 18 is mounted within the skirt 160, so as to engage the inner shell periphery 11a and fix the position of the skirt 16c. The syphon pipe 16b afiords conduit communication between the mouthpiece 16a and the pipe joint or elbow 19, by the use of a slip joint with one or the other, to accommodate relative expansion and contraction of the shell 11 during heating and cooling.

It will be understood that modifications and variations may be effected without departing from the spirit and scope of the novel concepts of the present invention.

We claim as our invention:

1. A syphon for the removal of condensate from a steam fed hollow rotatable heating device which comprises a conduit, generally radially extending imperforate conducting means connected to the conduit and mounted in the heating device for rotation therewith and having a continuous bore terminating in an open end proximate to the inner periphery of said device to receive condensate from within said device and convey said condensate to said conduit, and means defining a duct opening directly into said bore of said radially extending imperforate means spaced inwardly from the open end thereof at the region of the inner periphery of the device only sufli ciently far to avoid submergence in condensate in the hollow heating device, so as to transmit steam from the hollow rotatable heating device into said imperforate means thereby reducing the density of condensate. received through said imperforate means to reduce the efi'fect of centrifugal force upon the steam-condensate mixture.

2. A paper machine dryer drum which comprises a cylindrical shell, a head closing each end of the shell, a steam inlet conduit and a condensate drainage conduit each mounted in one of said heads, and a generally radially extending imperforate conducting means connected to the drainage conduit and mounted in the drum for rotation therewith and having a continuous bore terminating in an open end proximate to the inner periphery of said drum to receive condensate from within said drum and convey said condensate to said drainage conduit, and means defining a duct opening directly into said bore of said radially extending imperforate means spaced inwardly from the open end thereof at the region of the inner periphery of the drum only sufiiciently far to avoid submergence in condensate in the drum, so as to transmit steam from the interior of the drum into said imperforate means thereby reducing the density of the condensate received through said imperforate means to reduce the eflfect of centrifugal force upon the steam-condensate mixture.

3. A syphon for the removal of condensate from a steam fed hollow rotatable heating device which comprises a conduit, generally radially extending imperforate conducting means connected to the conduit and mounted in the heating device for rotation therewith and having a continuous bore terminating in an open end proximate to the inner periphery of said device to receive condensate from within said device and convey said condensate to said conduit, and means defining a duct opening directly into said bore of said radially extending imperforate means spaced inwardly from the open end thereof at the region of the inner periphery of the device only sufiiciently far to avoid submergence in condensate in the hollow heating device, so as to transmit steam from the hollow rotatable heating device into said imperforate means thereby reducing the density of condensate received through said imperforate means to reduce the effect of centrifugal force upon the steam-condensate mixture, said conducting means defining at its open end a frusto-conical skirt as a continuation of the bore to define a condensatereceiving mouth closely spaced from the inner periphery of said hollow heating device and said duct being positioned inwardly from said skirt.

4. A syphon for the removal of condensate from a steam fed hollow rotatable heating device which comprises a conduit, generally radially extending imperiorate conducting means connected to the conduit and mounted in the heating device for rotation therewith and having an open end terminating proximate to the inner periphery of said device to receive condensate from within said device and convey said condensate to said conduit, and means defining an orifice opening in said radially extending imperforate means spaced inwardly from the open end thereof at the region of the inner periphery of the device only sufficiently far to avoid submergence in condensate in the hollow heating device, so as to transmit steam from the hollow rotatable heating device into said imperforate means thereby reducing the density of condensate received through said imperiorate means to reduce the effect of centrifugal force upon the steam-condensate mixture, said orifice being aligned at an incline to the radially extending conducting means with said orifice extending in such incline outwardly from the interior of the radially extending means toward the inner periphery of the device.

5. A syphon for the removal of condensate from a steam fed hollow rotatable heating device which comprises a conduit, generally radially extending imperiorate conducting means connected to the conduit and mounted in the heating device for rotation therewith and having an open end terminating proximate to the inner periphery of said device to receive condensate from Within said device and convey said condensate to said conduit, and means defining an orifice opening in said radially extending imperforate means spaced inwardly from the open end thereof at the region of the inner periphery of the device only sufliciently far to avoid submergence in condensate in the hollow heating device, so as to transmit steam from the hollow rotatable heating device into said imperforate means thereby reducing the density of condensate received through said imperforate means to reduce the effect of centrifugal force upon the steam-condensate mixture, said conducting means mounting its open end a frusto-conical skirt to define a condensate-receiving mount closely spaced from the inner periphery of said hollow heating device, said orifice being aligned at an incline to the radially extending conducting means with said orifice extending in such incline out- Wardly from the interior of the radially extending means toward the inner periphery of the device.

References Cited in the file of this patent UNITED STATES PATENTS 1,095,757 Wentz May 5, 1914 2,017,762 Lord Oct. 15, 1935 2,299,530 Cram Oct. 20, 1942 2,869,248 Justus Jan. 20, 1959 FOREIGN PATENTS 301,213 Great Britain Nov. 29, 1928

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