US3065552A - Paper machine dryer drum - Google Patents

Description

E. s. sKxNNER PAPER MACHINE DRYER DRUM Filed. March 5, 1960 Nov. 27, 1962 ll /f Y; 2 F q; 3

J NMI-1 INVENTOR ATTORNEYS dryer drum structure.

United States Patent O 3,065,552 PAPER MACHINE DRYER DRUM Eugene S. Skinner, Beloit, Wis., assigner to Beloit Iron Works, Beloit, Wis., a corporation of Wisconsin Filed Mar. 3, 1960, Ser. No. 12,551. 3 Claims. (Cl. 34--124) The instant invention relates to a dryer drum for a paper machine, and more particularly, to an improved 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 journaling the shell for rotation, and means for introducing steam into the interior of the shell and drawing condensate therefrom. The Yankee dryer drum has generally the same structural arrangement as now used in the art, except that the Yankee dryer drum is ordinarily of substantially greater size than the dryer drums in the conventional dryer section ofa paper machine. Nevertheless, in each case these dryer drums (whether the large Yankee dryer drum or the smaller conventional drum) have certain operating limitations.

In the prior art paper machine dryers, steam is admitted to the interior of the dryer and is in contact with the entire interior surface of the dryer, the inner cylinder wall being subject, therefore, to uniform temperature. Condensate forms on the inner surface of the cylinder and the condensate layer depth is substantially uniform at the minimum thickness or depth obtainable with Siphon equipment used. The outer wall of the dryer, however, is subject to variations in temperature. For example, the moist paper web may not extend the full length of the cylinder shell, so as to leave the ends thereof uncovered by the paper. Also, the paper web passing over the cylindrical shell may not be dried to the same extent in the central portion as it is at the edges thereof. In addition, the rate of water evaporation from the web may vary across the width thereof, because of prior irregularitiesV in the processing of the web, or different characteristics in the web, or different draft conditions in the dryer part. In particular, however, the dryer surface in the region of the heads is not cooled by the passing damp sheet and it is subjected to cooling only from the ambient air which, of course, mayvary greatly in relative humidity and/or temperature. In general, the cooling effect at the end reaches of the shell is less than that in the intermediate portion.

The instant invention provides a simple and economical means for overcoming this difliculty. It will be appreciated that the tendency for the ends of the shell to become overheated, or more greatly heated than the intermediate portion, results in a tendency to overdry the edges of the Webadjacent thereto, and causes an unnecessary heat loss. In the instant invention, however, insulating means are provided along the inner periphery of the end portions ofthe shell to reduce Vheat transfer from the steam to the shell body in these regions. It will be appreciated that the instant invention may be employed to reduce heat transfer from the steam to any particular portion of the shell desired, although the main problem here solved is that of reducing heat losses at the shell ends and reducing overheating of the shell ends.

In U.S. Patent No. 2,893,136, issued July 7, 1959, in the names of Edgar I. Justus and Robert A. Daane, one solution to this same problem is provided. In the patented arrangement a plurality of circumferential dams are mountedon the. inner periphery.of.the dryer shell at axially spaced locations therewithin. One dam is aligned approximatley with the extreme edge of the paper web trained about the shell outer periphery, and another cir- ICC cumferential dam or annular ridge may be located in closely spaced relation to the iirst dam or ridge so as to align a space therebetween with the edge portion of the paper web. The circumferential dams maintain levels of condensate against the inner periphery of the dryer drum shell, and the condensate levels are effectiveas insulators to reduce the rate of heat transfer from the live steam within the shell to the outer shell periphery, thereby readily, simply and economically reducing heat losses to the ambient atmosphere.

' The instant invention is even more economical to fabricate and install than the Justus et al. patented structure, and features insulating members or bands of asbestos, fiber glass or like tape materials carried upon the shell inner periphery at generally the locations of the condensate levels L and l in Justus et al. 2,893,136. The insulating bands may be provided by a layer of insulating medium lying generally flush against the shell inner periphery and secured by adhesive means or in any other suitable manner to a metallic band, the ends of which may mount clamping means or like devices. The insulating means are economical to fabricate, may be readily installed and removed, and since both the fibrous insulation and metal band are rather poor heat conductors, the rate of heat transfer from the live steam within the shell to the outer shell periphery is markedly reduced.

It is accordingly an important aim' of the instant invention to provide an improved dryer drum structure.

Another object of the instant invention lies in the provision of an improved dryer drum having insulating means therein to reduce the heat transfer rate from the heating iuid in the dryer drum to the dryer outer periphery.

A further object of the present invention is to provide a dryer drum comprised of a shell and insulating means carried along the shell inner periphery in close contact therewith, the insulating means including a fibrous band member and a metallic band support therefor, `whereby selected portions of the dryer drum shell are effectively insulated to reduce heat transfer losses during various operating speeds of the dryer drum.

Other objects and advantages of the invention will become more apparent during the course of the following description, particularly when taken in connection with the accompanying drawings.

In the drawings, wherein like numerals designate like parts throughout the same:

FIGURE l is a partial sectional elevational View of a dryer drum constructed in accordance with the principles of this invention;

FIGURE 2 is a fragmentary plan view of insulating means embodying the concepts of this invention; and

FIGURE 3 is a fragmentary detail sectional view taken substantially along the line III-III of FIGURE 2, with the clamping means thereof shown in elevation.

Referring now to the drawings, a dryer drum of the instant invention is designated generally by the numeral 10, although in FIGURE 1 only the lower half of the drum is shown in sectional elevation for simplification of the description of this invention. The dryer drum 10 comprises a cylindrical shell 11 having open ends closed by annular heads 12 and 12a which are secured to the ends of the shell by bolts 13 and extend radially across the ends of the shell 1l. Journals 14 and 14a are shown as integrally formed with the heads 12 and 12a, the journals extending axially outwardly therefrom to be received by suitable bearings (not shown) for rotatably mounting the drurn lil. An axial bore 15 and 15a extends through each journal I4 and 14a, Vwhile in the particular structure i1- lustrated, the axial bore i501 is closed off by a plate 16a. At the opposite end of the drum ltlthe axial bore 15 mounts a plate 16 which receives a steam inlet header 17 26 and 27, as for example, three or four piece bands 26 and 27. As Well, as was noted, the number of insulating means 22,-25 may be less than or greater than that illustrated in FIGURE l.

It will also be appreciated that the instant invention is of important application in the control of heat input to the web throughout an entire dryer section, which may include as many as fifty dryer drums. ln such an arrangement, the insulative means Within the dryer drums are positioned at different locations throughout the dryer section, so that the amount of heat input to the central portion of the web may `be correlated with that input to the web edges Wa and Wb. Stated otherwise, the insulative means of the character indicated at 22-25 in FIGURE are positioned so as to produce a contoured curve of total heat input to the web. Illustratively, in a paper machine having a dryer section of fifty dryers, the insulative means can be successively moved toward the center of the machine in such a manner that the edges of the web would receive a heat input of 60% of the input at the center of the machine or dryer, and `by properly arranging the insulative means, the total heat input at intermediate points would be precisely adjusted to the desired moisture protile, and/ or to the particular characteristics of drying due to ventilation and other factors.

In such a paper machine dryer section, the circumferential insulative bands within the dryer drums are moved progressively inward toward the center of the drums in the direction of web travel, from the oncoming to the off-running side of the `dryer section, and with such insulative bands mounted in the drums in this manner, a substantially uniform ratio between the heat input to the central portion of the web and that to the edges may be maintained throughout the length of the dryer section.

It will be understood that modiiications and variations may be effected Without departing from the spirit and scope of the novel concepts of the present invention,

I claim as my invention:

l. A dryer drum comprising ya cylindrical shell, -a head closing each end of 'the shell, a steam inlet line leading into the shell through one of said heads, axially spaced and axially adjustable insulative means including a fibrous insulative band in ush fitting contact with the shell inner periphery and stationarily carried thereby, said insulative means being positioned on the shell inner periphery so that an inner face thereof will contact the steam brought into the shell by said steam inlet, a condensate drainage line communicating with the inner surface of the shell only, and said insulative means being positioned between the condensate drainage line and the shell heads reducing heat transfer through the drum shell.

2. A dryer drum comprising a cylindrical shell having a smooth and uninterrupted inner periphery between opposite ends thereof, a head closing each end of the shell, a steam inlet line leading into the shell through one of said heads, a condensate drainage line leading from the shell through one of said heads receiving steam and condensate from the shell, an axially spaced circumferential insulative means on the shell inner periphery near the shell ends and having an inner face that is in contact with steam brought into the inner `shell by said steam inlet for reducing heat transfer through said shell, each of said insulative means comprising a Water absorptive Woven fibrous strip stationarily carried by and in close fitting contact with the shell periphery and a metal backing band secured to said fibrous layer.

3. A dryer drum comprising a cylindrical shell having a smooth `and uninterrupted inner periphery between opposite ends thereof, a head closing each end of the shell, a steam inlet line leading into the shell through one of said heads, a condensate drainage line leading from the shell through one of said heads receiving steam and condensate from the shell, an axially spaced circumferential insulative means on the shell inner periphery near the shell ends having an inner face in contact relationship with steam that is brought into the shell by said steam inlet for reducing heat transfer through said shell, each of said means comprising a librous band in close iitting contact with the shell inner periphery and rigidly carried thereby, a transversely split metal backing adhesively secured to `said fibrous band, and means clampingly engaging the metal backing at opposite sides of the transverse split.

References Cited in the file of this patent UNITED STATES PATENTS 1,640,855 Shlick Aug. 30, 1927 1,899,256 Brannen Feb. 28, 1933 2,412,733 Hornbostel Dec. 17, 1946 2,783,550 Breakell Mar. 5, 1957 2,870,546 Nelson I an. 27, 1959 2,893,136 lJustus et al. n July 7, 1,952

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