US2519105A - Drier roll for paper, paperboard, and like material - Google Patents

Description

Aug. l5, 1950 A, A, BLUE 2,519,105

DRIER ROLL FOR PAPER, PAPERBOARD AND LIKE MATERIAL Filed Aug. 14, 1947 01,. 0 @.Tgmwnw QM )7 fro a Mey;

Patented Aug. l5,` 1950 vDBIER ROLL FOR PAPER, PAPERBOARD. AND LIKE MATERIAL Anhui A. Blue, Fairfield, conn. Anuman August 14, 1947, serial No. 1118.582

l This invention pertains to dryer rolls of iinproved construction which permit the practice of an improved method of drying paper. Paper board or like materials :which are fed between and dried by the rolls. i

'I'he construction of a conventional dryer roll such as those now commonly and almost universally used comprises a cylindrical metallic barrel having end closures or heads each of which is providedwith an outwardly extending trunnion which is rotatable in suitable supporting bearings. One head is solid while the trunnion of the other head is hollow and provides an entry into the interior of the roll through which steam is admitted for heating the rroll. The introduction of the steam and the removal of the consequent condensed :water from the roll is accomplished in numerous ways and inasmuch as this forms no part `oi! the present invention no specific de-V scription of the introduction of the steam or the removal of the water is given. It might be mentioned however that the steam may be admitted directly into the interior of the roll 011 it may ybe carried into the roll by means of a pipe extending throughout the length oi' the interior of the roll and provided at spaced points along its length with steam outlet openings. It might also be mentioned that the water condensed from the cooling steam may be removed by pressure,=

by siphoning, by scooping, by steam injectors 011' by lany other suitable mechanical means.

, Dryer rolls as used in the industry are quite large often being as much as 42 inchesk in diameter and 120 inches long exclusive of the trunnions.

than those mentioned are to be found in many In 'fact rolls of greater dimensions mills. In a large paper board mill the number of rolls required to dry the product often in a single unit total more than 100. 'I'hese many rolls total in their entirety` an extremely large ,s cmm. (c1. 34-11o) area and the fuel necessary to heat this roll 'Y area and to drive this large train of rolls is very great. The fuel for heating the rolls is extremely great 4because it is now common practice to make the rolls throughout of common iron or steel the thermal conductivity/ of which, as compared to numerous other metals, is relatively low. In use or operation the paper, paper board or other material to be dried is passed around the rolls to pass between them all as is well'known to those familiar with and skilled in the art.

' The present invention has as its primary object the provision of an improved drying roll the nature and attributes of which are such that it can be more quickly, emciently andk cheaply tion in installation and operating heated than drying rolls as commonly known with the result that adequate drying of the material passing between the rolls can be accomplished by a lesser number of rolls with a consequent savings in fuel consumption because of the fewer number of rolls it is found necessary to drive and heat. l

Another object and advantage of the invention is that of reducing the cost of a drying installation which reduction is possible because of the reduced number of rolls by which the desired drying operation can be accomplished.

A further object of the invention is that of speeding up and increasing the out-put of a mill of a given number of rolls... By the use of my improved rolls having an increased heating power the drying operation is speeded up and the output increased by increasing the speed of rotation of the rolls which is possible because the rolls heat the paper or paperboard more rapidly. Consequently the material need not be in contact with the rolls as long thus permitting the roll speeds to be increased with a consequent increase in production ofver a mill having a like number ofrolls composed of the lesser eiiicient iron or steel construction.

A still further object oi the invention is the provision of a` new and improved method of manufacturing paper, paper board or like material by the utilization of a drying mill embodying my improved drying rolls.

A further object of the invention is the reducexpenses of a drying mill. i

Other objects, novel features of construction and improved results of the invention will appear from the following description when read in the .light of the accompanying drawing and will be understood and appreciated from this specification by those skilled in the art.

The drawing illustrates a drying roll embodying the present invention and describing the construction in detail it will be seen that the roll comprises a hollow open-ended drying drum I provided interiorly in each of its ends with a circumferential flange or shoulder 2 having on its outer face a circumferential V-shaped tongue 3.

tion between the heads and the flanges with the I 3 heads secured to the flanges by some suitable means" such as bolts 1.

The head I is solid and provided with a solid outwardly extending trunnion 8. The head 5 is provided with an outwardly extending trunnion 9 which is hollow to provide a. passageway l0 giving entry into the interior of the drum through which, by suitable means, steam or some other suitable heating medium is introduced for heating the drum so that it will provide its drying rfunction in the mill set-up. Although not so illustrated it will be understood that the trunnions are rotatably supported in suitable bearings and that an adequate number of drying rolls are provided to accomplish the desired degrec of drying of the product which is passed' around the drums constituting the drying unit or mill.

From the foregoing it will be understood that to make the most effective use of the heat supplied to a drying roll it is necessary that maximum heat be delivered through the cylindrical drying drum or barrel with which the paper or paper board is in contact and that a minimum amount of heat be delivered, that is lost, through the ends or heads of the drum. Heretofore therev has been great wastage of heat through the drum heads due to radiation and convection in air v currents. Additionally heat at the drum or barrel ends is highly undesirable as it makes for diiiiculties in maintaining lubrication at and in the trunnion bearings.

It is now common practice to make drying rolls of a single metal such as iron or steel and such rolls provide no differentiation between the rate of heat conductivity to the sides of the drum or roll where it will be useful and the ends or heads of the drums or rolls where it will be wasted. In my improved drying roll a difierential rate of conductivity between the barrel or drum sides and its ends or heads is provided.

Hereinafter in referring to and evaluating the -thermal conductivity of metals use is made of the c. g. s. unit of conductivity, namely, calories per second, per degree centigrade, per square centimeter, per centimeter, at temperatures from to 100 C. The values of conductivity used are those published 'by responsible manufacturers of metals and other standard sources but it is to be understood that such values are not exact as the values will vary from lot to lot of the same metal or material due to commercial variations in the manufacture of the metals.

The nominal thermal conductivity rate of common iron and steel is .120 c. g. s. units whic as heretofore mentioned is quite low.

Although it would appear that copper, due to its high nominal thermal conductivity, which is .930 c. g. s. units, would be suitable for use in dryer roll construction this is not the case due tothe soft characteristics of copper which make it unsuitable for use to build a dryer roll having adequate strength to withstand the stresses and strains to which dryer rolls are subjected.

Y It is essentialthat the metals used in both the barrel and its closure -heads have suicient physical strength to meet practical use requirements. The metals used by me have the necessary physical strength as they both have a. mini mum tensile strength of 45,000 ypounds per square inch even when continuously subjected to roll v operating temperatures of 350 F.

I have however determined that there are certain copper base alloys which have the usable combination of physical strength and high C. g. sfumts Aluminum brass, thermal conductivity rate 0.24

Chromium copper, thermal conductivity rate 034-084 Cadmium copper, thermal conductivity rate 0.75-082 The copper base alloys which can be used are not limited to the foregoing list. My invention in part is the use of a copper base alloy as the metal for the dryer roll drum or barrel l. such use greater heating power per square inch or square foot of the barrel is secured.

In drying rolls of the type here-discussed heat is wasted at three points on the drying rolls. First, at the ends or heads of the rolls; secondly. the steam feed means; and thirdly, the area of the drum which is not in contact with the paper sheet or other product passing through the rolls.

'Ihe invention further comprises reducing the wastage of heat at or through the ends or heads of the drying drum or barrel. There are certain alloy steels in which the alloy content causes the grain structure of the steel to be in the austenitic condition with the result that they have thermal conductivity rates much lower than common iron and steel. Examples of such alloy steels are:

C. g. s. Manganese steel, thermal conductivity rate 0.023 Nickel-chromium steels, known as austenitic Stainless Steels, thermal conductivity rate 0.03-0.04

The above referred to types of metal have a rate of thermal conductivity about one-third that of common iron and steel. One or the other of these listed alloy steel metals is used as the material for the dryer roll ends or heads.

I recognize that by the use of these differential metals in the dryer drum barrel and its heads there may be in some cases a difference in heat expansion between the barrel and the heads. Where this occurs it is compensated for by the V-shaped tongue and groove joint between the barrel and its heads.

From the foregoing it will be seen in respect to dryer rolls as heretofore known and used the present roll is much more elcient. The barrel of each roll is much more eiiicient in the transmission of heat while the heads of each roll reduce the loss of heat through the roll ends or heads. Due to this greater efliciency the total number Aof rolls necessary to dry a product is materially reduced and therefore the loss of heat, heretofore mentioned, is reduced. This is so because to the amount that the area of the rolls which is wasting heat is reduced there is consequent saving in fuel. It will be obvious that if it is possible to reduce the number of rolls in a mill by one-half the area of the rolls which is wasting heat is reduced in a like amount. By the use of the copper base alloy mentioned for the roll barrel the number of rolls necessary to the accomplishment of a drying operation is materially reduced. 'Ihis reduction in the number of necessary rolls is increased by the use of the specified alloy steels as the material for the ends or heads of the rolls because the saving in heat loss at the roll ends makes it possible to further reduce the number of rolls necessary in the mill.

asians less heat is conducted into the bearings which increases the, life of the bearings. Additionally the reduction of-heat in the bearings reduces lubricant expenses.

What I claim is: 1. A drying roll for drying paper, paper board or like material comprising, a hollow open-ended Ametallic cylindrical barrel, a metallic `head closing each end of saidjbarrel, themetals composing said barrel and its ends having diilerent rates of thermal conductivity, said barrel being constructed of a chromium copper alloy having a thermal conductivity rate from .74 to .84 c. g. s. units, and said heads being composed of an austenitic alloy steel having a thermal conductivity rate of .023 to .040 c. g. s. units.

2. A drying roll for drying paper, paper board or like material comprising, a hollow open-ended metallic cylindrical barrel, a metallic head closing each end of said barrel, the metals composing said barrel and its ends having different rates yof thermal conductivity, said barrel being constructed of a chromium copper alloy having a thermal rate of conductivity of .74 to .84 c. g. s. units, and said barrel heads being constructed of ferrous metal having a lower rate of thermal conductivity than the metal composing the barrel.v

3. A drying roll as deiined in claim l wherein, the, metals used in both the barrel and the head closures thereof have a minimum tensile strength af 45,000 pounds per square inch even when sub- Jected to temperatures up to 350 F.

4.,A drying roll as dened in claim 2 wherein, thel metals used in both the barrel and the head closures thereof have a minimum tensile strength of 45,000 pounds per square inch even when subjected to temperatures up to 350 F.

4 5. A drying roll for drying paper, paper board or like material comprising, a hollow open ended -f cylindrical barrel, a metallic` head closing each strength of 4500 pounds per square inch even when subjected to temperatures up to 350 F., and the thermal conductivity of the barrel being `not less than six or more than thirty-six times that of the heads.

6. A drying roll for drying paper, paper board or like material comprising, a hollow openv ended metal cylindrical barrel, a metallic head closing each end of the barrel, the metals composing said barrel and its ends having different rates of thermal conductivity and each havingv a minimum tensile strength of 4500 pounds per square inch even when subjected to temperatures up to 350 F., the thermal conductivity of the metal composing the barrel being from .24 to .84 c. g. s.

units, and the thermal conductivity of the metal composing'the heads being from .023 to .040 c. g. s. units.-

7. A construction as defined in claim 6 wherein, the metal composing the barrel is a copper base alloy and the metal composing the heads is an austenitic alloy steel.

8. A drying roll for drying paper, paper board or like material comprising, a hollow open-ended cylindrical barrel composed of a copper base alloy, a head closing each end of said barrel and each head being composed of an austenitic alloy steel, the metals composing said barrel at its ends having dilcrent rates of thermal conductivity, the thermal conductivity of the metal composing the barrel being from .24 to .84 c .g. s. units, and the thermal conductivity of the metal com' posing the barrel heads being from .023 to .040 c. g. s. units.

ARTHUR A. BLUE.

REFERENCES @FEED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Hornbostel -;1--- Dec.,23, 1947

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