CA1184028A - Sheet paper drying cylinder for a continuous papermaking machine - Google Patents
Sheet paper drying cylinder for a continuous papermaking machineInfo
- Publication number
- CA1184028A CA1184028A CA000409386A CA409386A CA1184028A CA 1184028 A CA1184028 A CA 1184028A CA 000409386 A CA000409386 A CA 000409386A CA 409386 A CA409386 A CA 409386A CA 1184028 A CA1184028 A CA 1184028A
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- drum
- shell
- tube
- collectors
- tubes
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Paper (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A steam heated cylindrical dryer drum for continuously drying a traveling paper web in a papermaking machine wherein steam is supplied to the inner cavity of the drum and the shell of the drum has a plurality of circumferential grooves with axially extending rectangular collectors and tubes projecting tangentially from the collectors of resiliently deflectable material biased outwardly toward the shell of the drum with positioning lugs on the free ends of the tubes resting on the ribs to fix their position in the base of the grooves.
A steam heated cylindrical dryer drum for continuously drying a traveling paper web in a papermaking machine wherein steam is supplied to the inner cavity of the drum and the shell of the drum has a plurality of circumferential grooves with axially extending rectangular collectors and tubes projecting tangentially from the collectors of resiliently deflectable material biased outwardly toward the shell of the drum with positioning lugs on the free ends of the tubes resting on the ribs to fix their position in the base of the grooves.
Description
BACKGROUND OF THE INVENTION
The present invention relates to improvements in dryer drum~ for continuousl.y dryirlg a web of paper in a papermaking machine, and more particulary to an improved condensate removal structure.
In a papermakin~ machine a plurality of dryer drums are arranged in sequence for carrying a continuous web of paper in a serpentine fashion ~hrough the dryer section~ The dryer drums are steam heated, and the drums are usually constructed of a cylindrical outer shell with a smooth outer sur~ace for carrying the paper web with heads at the ends of ~he drum shell which are provided with supporting bearings for rotatably mounting the drum. Means are provided at the bearings for directing steam into the dru~ and as heat is transferred to the web supported on the surface of the shell, condensate tends to form which must be removed so that it will not have an insulating effect and reduce the heat trans~er from the steam to the shell.
In a typical construction so that the heat transfer abilit~;r of the drum is increased, the shell is made as thin as possible, and for strength, a plurality of annular raised ribs are located on the inner surface of the shell with grooves therebetween. The condensate collects in these grooves, and it is imperative that it be effectively removed for increasing the eficiency of the dryer drum, and in high speed papermaking machines, it is imperative that heat transfer be maintained at maximum efficiency and that the insulating effect of condensate collected within the drum be maintained at a minimum and be immediatel~ and effectively and un.iormly removed.
In accordance with a provision of the present invention, there are provided a plurality of elongate tubes which suck the condensate from the base of the grooves and the tube~ are uniquely constructed and supported for removal of the `~
condensate.
In order to obtain good operation and a high coefficien~
of ~he transmission of heat ~o the paper web on the outer s~rface of the drum~ it is advi~able tha~ ~he thickness of the condensates which accumulates in the bottom of ~he drum be maintained at a minimum, and it is also imperative that this thickness remain the same in all o~ ~he grooves to maintain the same coefficient of heat transmission over the whole length of the surface of the drum.
Presently known drums can be generally categorized in two types. One type has condensate collectors which are fixed to the inner surface of the shell, and the other type has condensate collectors which are fixed and suppor~ed to the central shaft of the drum. The first type insures the maintenance of the distance between the collector tubes within the drum and the bottom of the grooves, but has the disadvantage that with rotation of the drum, centrifugal forces generated by the mas, of the collectors make the shell deform resiliently causing it to be polygonal because of the concentration of such forces at the location of the collectors.
Drums which have collectors that are supported on the central shaft have the disadvantage that there is no good control over the distance between the open ends of the collector tubes and the bottom of the grooves particularly because dimensions change with thermal deformation of ~he parts as temperatures change. There is thus a need for control over the depth or th~ckness of the condensate which rims at ~he bottom of the grooves. Another problem is encountered tha~ small tubes cannot be mounted with a very small spacing between their open ends and the inner surfaces of the shell because contact can occur between the tubes and the bottom of the grooves in operation generating wear and stresses on the shell.
An object of the pre~ent inventlon is to provide a steam dryer drum and condensate removal structure which will avoid the aforementioned disadvantages.
A further object of the invention is to provide a condensate removal sys~em utilizing individual tubes for the grooves wherein the tu~bes can be readily and accurately adjusted relative ~o the bottom of the groove for uniformity o spacing between the ends of ~he tubes and the groove.
A still further object of th invention is to provide a condensate removal system ~or a grooved or ribbed dryer drum wherein the radial spacing between the open receiving ends of condensate collectvr tubes and the bottom of the grooves remains constant independent of deformations of the shell during opération and independent of changes of dimensions due to thermal deformation.
In accordance with the principles of the invention, there is provided a rotary steam dryer drum for a continuous traveling web of paper wherein the drum is supplied with steam for drying the web and has a cylindrical shaped shell with a smooth outer surface and with heads at the end of the shell to support the drum in rotation~ Within the shell on the inner surface are a plurality of ribs with circumferential grooves therebetween, and a plurality of axially extending collectors is supportd and disposed within the interior of the drum to receive and take up the condensation resulting from the steam and to convey it out of the drum. The axially extending collectors are provided with a plurality of small elastically deflectable tubes which project in both circumferential directions from the collectors in such a way as to have~the base end securely mounted on the collector for the flow of cvndensate from the tube to the collector and having the free end biased toward the bottom of the groove but provided with a lugged tube positioning element which rests on the inner surface of the ribs adjacent the grooves in order ~o maintain the free end a predetermined accurate controlled distance from the bo~tom of the groove.
Other objects, advantages and features will become more apparent with the teaching of the principles of the invention in connection with the disclosure of the preferred embodiments thereof in the specification, claims and drawings in which:
DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a sectional view on a plane perpendicular to the axis of rotation of the dryer drum;
FIGURE 2 is a partial sectional view taken on a plane extending parallel to the drum axis;
FIGUÆ 3 is a sectional view taken substantially along line III-III of Figure 2;
FI~URE 4 is a partial sectional view taken substantially along line IV-XV of Figure 3;
FIGURE 5 is as fragmentary detailed sectional view taken substantially along line V-V of figure 4;
~ IGURE 6 is a fragmentary detailed sectional view taken substantially along line VI-VI of Figure 5;
FIGURE 7 is a fragmentary detailed sectional view taken substantially along line VII-VII o~ Figure 6 and showing a modified for~ of support; and FIGURE 8 is a detailed view, partly in section, taken ~ubstantially along line VIII-VIII of Figure 2.
DESCRIPTION
The dryer drum incorporating the features of the present invention includes a cylindrical shell la having a smooth outer surface which ~upports the continuously traveling web of paper to be dried. The drum has at its ends heads 1 which with the shell define an inner cavity which receives steam and in which the other components of the device are housed. Within the shell '~ f~
are axiallY extending collectors 2 which extend parallel to the central rotational axis of ~he drum and which are of a slightly less length than the drum. The heads at the ends of the drum are provided with suitable support bearings, not shown, so that the drum can rotate during drying operation.
Each of the collectsrs 2 is held by mean~ of four radial arms 3 which a e supported at their inner ends on an annular wall 4 which is part of the central shaft 5 or hub of the drum. The hub is provided in the form of a hollow annular casting formed in sections and providing two cavities 6 and 7 which are separated from one another by a wall 8. Each of the radial arms 3 is also circumferentially supported by four pairs of struts or tie rods 9 which struts are fixed both to the hub and to the radial outer ends of the arms 3. The tie rods circumferentia:Lly support the arms. but also provide radial support and absorb part of the circumferential tension force created by the mass of the collectors which is subjected to centri~ugal force during the rotation of the drum.
The central shaft, shown generally at 5, has an axial connection for the delivery of steam into the interior, and the hub 4 has a plurality of radial holes 13 which permit the steam to flow into the cavity 14 to come in contact with the shell.
Within the hub 4 is constructed a cylindrical wall 15 which de~ines a cavity 16 for the receipt and transmittal of condensate which flows axially outwardly through the end of the drum through an outlet hole 17~
Each collector 2 is in communication with ~he condensate cavity 16 by means of its o~n tube 18 in such a manner that under a given pressure differential or suction created by a pump or suitable suction device outside the drum, a flow of condensate will be caused from ~he collectors 2 into the cavity 16 and outwardly of the drum.
As is shown in Figures 1, 2 and 3, the outer surface of the shell 1 is smoot~ and cylindrical in shape for providing support for the paper web and for goQd heat transmission. The inner surface of the shell is circumferentially grooved to increase the area for heat exchange, to reduce the distance to the outer surface of the shell, to strengthen the shell, and to create a series of collection channels for condensate which forms during operation. The grooves are formed by integral ribs on the inner surface of the shell, and the grooves are shown at 19 separated by the ribs 20~
The axially extending collectors 3 are positioned closely adjacent the shell and supported by arms 3 with the connection between the collector and its supporting arms provided by means shown at 23 (Figure 3~. This includes a plate 24 provided with a lug 25 fixed to the collector, and a fork 26 fixed to the radially outermost end of the arm 2 and recei~ing the lug 25. A pair of pins 27 (Figure 4) pivotally fix the lub to the fork 26. Between the sides of the fork, there is a spacer washer 28 of a thickness so as to allow axial play of the collector 2 by allowing small displacements of the lug 25 as axial expansion and contraction of the collection occurs due to temperature variations In the arrangement illustrated in Figure 3, each arm 3 is hollow, and its radially innermost end is fixed and supported by means of a flange 29 ~o flange parts 30 of the central shaft 5.
As ~h~wn in Figure 4, each collector 2 has a sub~tantially rectangular section with flat walls 33a, 33b. The upper wall 33a is fixed to ~he pla~e 24 of connection means while the lower plate 34b is located a short distance inwardly from the ribs 20. As shown in Figure 4, the wall 34a and parts of the walls 33a and 33b are constructed from a shaped integral section of ~heet metal, and the other parts of the walls are provi~ed by bars 35 having a greater thickness than that of the wall as illustrated in the sectional view of Figure 4. These bars provide a rigid base for supporting tubes 36.
From the walls 33a and 33b of each collector 2, small tubes 36 extend in a ~ubs~antial tangential direction with respect to the shell 1. These tubes lead from each of the grooves to the interior of the collector 2. The base cr support end 38 of each of the tubes passes through one of the walls 33a and 33b of the associated collector and is inserted into a bushing 39, the threaded outer surface of w~ich is screwed into a corresponding threaded hole formed in the bar 35 of the a~sociated wall 33at 33b. A ring nu~ 40 locks this bushing and the associated small tube to the wall. The outer free end of each of the tubes 36 projects into a radial groove 19 as illustrated in Figure 4. The tube is shaped so that it diminishes in diameter from the base end 38 toward the free end. ~ne free end is cut at a bias so as to be parallel to the inner surface of the base of the groove, and therefore suction flow of the condensate into the tube is enhanced Each of the tubes 36 is made from an elastically deflectable material which is resistant to the temperature of the steam within the cylinder. Preferably, the tubes are formed of metal~ and the tubes in effect are a cantilever elastic beam ~upported on the associated collector with a natural bias or bend so as to cause the free end to spring toward the hase of the groove.
At the free end of each tube is secured a small guide plate 45 (Figures 4 and 5) preferably having a substantially T~
shaped form. This guide plate is a tube positioning element and has a central lug 46 with a hole therethrough into which projects the tubeO The lug is ~ufficiently narrow so that it fits within the groove. ~he lug has at least one, but preferably, a pair of laterally extending arms 47 which rest on the top of the adjacent ribs 20. In this way, the free open end 44 o each tube is held a predetermined very small distance from the bottom surface 19 of the groove as indicated at g in Figures 4 and 60 While other forms of bias may be used, it is preferred that the tube be con~tructed of a resilient material so that it can be mounted at its base to be biased alon~ its length to urge its free end toward the base of the groove. The bias is such that a preload or stress exists in the tube which is counteracted by the tube positioning e~ement 45.
The element rests on the top of the ridges and the ridges' top surface is parallel to the base of the grooves so that essentialLy with expansion or contraction due to temperature difference, the element 45 can slide on the rib without binding.
In the end regions of the headst there is a formed a radial groove :L9a (Figure 2~ of axial width greater than the grooves. In this groove l9a there is inserted a tube 36, the free end of which is rigidly positioned with respect to the bottom of this groove by a plate 45a (Figure 6) fixed to the rib 20 adjacent the groove, such as by qcrews 48. The plate 45a has a hole to receive the tube 43 and allow a limited amount of radial play.
Each discharge tube 18 (Figures 1 and 2) for the discharge of condensate from each collector 2 has a structure such as shown in Figure 8 and includes a first section 49a fitted into the collector itself bylmeans of a sealing assembly 50. This incl~des a pair of flanges 51 and a sealing element S2. Also included is a second section 4gb passing through the wall 15 and connected to the preceding part by means of a ball .J~r..~
joint 53 of a known ~ype. The discharge tube 18 is guided and maintained in position along the sha~t 5 by means of a bushing assembly 54 provided with a flange 55 connected to the wall 4 of the shaft.
Any configuration of tubes 36 projecting from each collector 2 can be employed. Preferably, the tubes are constructed to project alternately in opposite circumferential directions with respect to the supportin~ collector, but different arrangements can be adopted.
In operation steam is supplied to the interior of the drum through the cavity 14 through the hole 12, the cavity ~ and the radial holes 13 for heating the shell. As heat is extracted from the steam for evaporating water from the paper sheet, this causes condensation within the drum which collects at the bottom of the grooves 19 (Figure 3). Through the holes 17 and the cavity 16 a suction is applied which rreates a lowered pressure within the interior of the collectors 2. The condensate, or a mixture of condensate and steam is drawn through the small tubes 36 through the free open ends ~3 having their collection surfa~es 44 in close proximity to the base of the grooves. It is, therefore, apparent that a spacing g between the surfaces 44 and the base is very small, and the condensate can almost completely be sucked up with the intended advantaye of increasing the coef~icient of heat transfer between the steam and the metal of the shell~
During operation of the devicer the shell o one of the cylinders is subjectd to deformations produced by thermal expansion due to the heat within the drum and the removal of heat by the water evapora~ing from the w~b on the ou~er surface of the drum and these circumstances~:will vary during operation. As a consequence of this deformation of the shell, the substantially cylindrical form of the shell and its J~
associated grooves 19 varies~ Such a variation in form does not have any nega~ive effect on the sucking action exerted on the condensate in the bottom of the grooves 19 by the tubes. In fact, whatever the dimensional and form variations of the groove, the clearance space g between ~he surface 44 of a given tube in the bottom surface of the associated groove is maintained constant. This favorable resul~ i5 obtained because the free end of the tube is positioned in a fixed manner with respect to the bottom of the groove both by the action of the plate 45 and by the resilient preloading of ~he tube. Whatever the displacement of the bottom surface of the groove which is located beneath the end surface 44 of the tube, the same displacement occurs on the ribs on either side of the groove.
Because of the abutment on the plate 45 on these ribs, this causes a corresponding displacement of the end of the tube.
The con~densate drawn up into the various collectors is conveyed through the discharge tubes 18, the cavity 16 and the hole 17 out of the drum7 Because of the form of the section of each collector which is rectangular, it can be arranged in a radial position very close to the inner surfaces of the shell with the advantage of improving effectiveness of the suction.
Each tube 36 can be accurately positioned with respect to the associated collector by means of the bushing and ring 39 and ring nut 40 for the purpose of positioning in a correct manner the end 44 of the tube with respect to the bottom surface of the associated groove 19.
While the pre~erred form is illustrated, it will be apparent fro~ the foregoing teaching of the description that various parts of the embodiment of the present invention can be varied without departing from the spirit and scope of the invention.
, .~ , ;
The present invention relates to improvements in dryer drum~ for continuousl.y dryirlg a web of paper in a papermaking machine, and more particulary to an improved condensate removal structure.
In a papermakin~ machine a plurality of dryer drums are arranged in sequence for carrying a continuous web of paper in a serpentine fashion ~hrough the dryer section~ The dryer drums are steam heated, and the drums are usually constructed of a cylindrical outer shell with a smooth outer sur~ace for carrying the paper web with heads at the ends of ~he drum shell which are provided with supporting bearings for rotatably mounting the drum. Means are provided at the bearings for directing steam into the dru~ and as heat is transferred to the web supported on the surface of the shell, condensate tends to form which must be removed so that it will not have an insulating effect and reduce the heat trans~er from the steam to the shell.
In a typical construction so that the heat transfer abilit~;r of the drum is increased, the shell is made as thin as possible, and for strength, a plurality of annular raised ribs are located on the inner surface of the shell with grooves therebetween. The condensate collects in these grooves, and it is imperative that it be effectively removed for increasing the eficiency of the dryer drum, and in high speed papermaking machines, it is imperative that heat transfer be maintained at maximum efficiency and that the insulating effect of condensate collected within the drum be maintained at a minimum and be immediatel~ and effectively and un.iormly removed.
In accordance with a provision of the present invention, there are provided a plurality of elongate tubes which suck the condensate from the base of the grooves and the tube~ are uniquely constructed and supported for removal of the `~
condensate.
In order to obtain good operation and a high coefficien~
of ~he transmission of heat ~o the paper web on the outer s~rface of the drum~ it is advi~able tha~ ~he thickness of the condensates which accumulates in the bottom of ~he drum be maintained at a minimum, and it is also imperative that this thickness remain the same in all o~ ~he grooves to maintain the same coefficient of heat transmission over the whole length of the surface of the drum.
Presently known drums can be generally categorized in two types. One type has condensate collectors which are fixed to the inner surface of the shell, and the other type has condensate collectors which are fixed and suppor~ed to the central shaft of the drum. The first type insures the maintenance of the distance between the collector tubes within the drum and the bottom of the grooves, but has the disadvantage that with rotation of the drum, centrifugal forces generated by the mas, of the collectors make the shell deform resiliently causing it to be polygonal because of the concentration of such forces at the location of the collectors.
Drums which have collectors that are supported on the central shaft have the disadvantage that there is no good control over the distance between the open ends of the collector tubes and the bottom of the grooves particularly because dimensions change with thermal deformation of ~he parts as temperatures change. There is thus a need for control over the depth or th~ckness of the condensate which rims at ~he bottom of the grooves. Another problem is encountered tha~ small tubes cannot be mounted with a very small spacing between their open ends and the inner surfaces of the shell because contact can occur between the tubes and the bottom of the grooves in operation generating wear and stresses on the shell.
An object of the pre~ent inventlon is to provide a steam dryer drum and condensate removal structure which will avoid the aforementioned disadvantages.
A further object of the invention is to provide a condensate removal sys~em utilizing individual tubes for the grooves wherein the tu~bes can be readily and accurately adjusted relative ~o the bottom of the groove for uniformity o spacing between the ends of ~he tubes and the groove.
A still further object of th invention is to provide a condensate removal system ~or a grooved or ribbed dryer drum wherein the radial spacing between the open receiving ends of condensate collectvr tubes and the bottom of the grooves remains constant independent of deformations of the shell during opération and independent of changes of dimensions due to thermal deformation.
In accordance with the principles of the invention, there is provided a rotary steam dryer drum for a continuous traveling web of paper wherein the drum is supplied with steam for drying the web and has a cylindrical shaped shell with a smooth outer surface and with heads at the end of the shell to support the drum in rotation~ Within the shell on the inner surface are a plurality of ribs with circumferential grooves therebetween, and a plurality of axially extending collectors is supportd and disposed within the interior of the drum to receive and take up the condensation resulting from the steam and to convey it out of the drum. The axially extending collectors are provided with a plurality of small elastically deflectable tubes which project in both circumferential directions from the collectors in such a way as to have~the base end securely mounted on the collector for the flow of cvndensate from the tube to the collector and having the free end biased toward the bottom of the groove but provided with a lugged tube positioning element which rests on the inner surface of the ribs adjacent the grooves in order ~o maintain the free end a predetermined accurate controlled distance from the bo~tom of the groove.
Other objects, advantages and features will become more apparent with the teaching of the principles of the invention in connection with the disclosure of the preferred embodiments thereof in the specification, claims and drawings in which:
DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a sectional view on a plane perpendicular to the axis of rotation of the dryer drum;
FIGURE 2 is a partial sectional view taken on a plane extending parallel to the drum axis;
FIGUÆ 3 is a sectional view taken substantially along line III-III of Figure 2;
FI~URE 4 is a partial sectional view taken substantially along line IV-XV of Figure 3;
FIGURE 5 is as fragmentary detailed sectional view taken substantially along line V-V of figure 4;
~ IGURE 6 is a fragmentary detailed sectional view taken substantially along line VI-VI of Figure 5;
FIGURE 7 is a fragmentary detailed sectional view taken substantially along line VII-VII o~ Figure 6 and showing a modified for~ of support; and FIGURE 8 is a detailed view, partly in section, taken ~ubstantially along line VIII-VIII of Figure 2.
DESCRIPTION
The dryer drum incorporating the features of the present invention includes a cylindrical shell la having a smooth outer surface which ~upports the continuously traveling web of paper to be dried. The drum has at its ends heads 1 which with the shell define an inner cavity which receives steam and in which the other components of the device are housed. Within the shell '~ f~
are axiallY extending collectors 2 which extend parallel to the central rotational axis of ~he drum and which are of a slightly less length than the drum. The heads at the ends of the drum are provided with suitable support bearings, not shown, so that the drum can rotate during drying operation.
Each of the collectsrs 2 is held by mean~ of four radial arms 3 which a e supported at their inner ends on an annular wall 4 which is part of the central shaft 5 or hub of the drum. The hub is provided in the form of a hollow annular casting formed in sections and providing two cavities 6 and 7 which are separated from one another by a wall 8. Each of the radial arms 3 is also circumferentially supported by four pairs of struts or tie rods 9 which struts are fixed both to the hub and to the radial outer ends of the arms 3. The tie rods circumferentia:Lly support the arms. but also provide radial support and absorb part of the circumferential tension force created by the mass of the collectors which is subjected to centri~ugal force during the rotation of the drum.
The central shaft, shown generally at 5, has an axial connection for the delivery of steam into the interior, and the hub 4 has a plurality of radial holes 13 which permit the steam to flow into the cavity 14 to come in contact with the shell.
Within the hub 4 is constructed a cylindrical wall 15 which de~ines a cavity 16 for the receipt and transmittal of condensate which flows axially outwardly through the end of the drum through an outlet hole 17~
Each collector 2 is in communication with ~he condensate cavity 16 by means of its o~n tube 18 in such a manner that under a given pressure differential or suction created by a pump or suitable suction device outside the drum, a flow of condensate will be caused from ~he collectors 2 into the cavity 16 and outwardly of the drum.
As is shown in Figures 1, 2 and 3, the outer surface of the shell 1 is smoot~ and cylindrical in shape for providing support for the paper web and for goQd heat transmission. The inner surface of the shell is circumferentially grooved to increase the area for heat exchange, to reduce the distance to the outer surface of the shell, to strengthen the shell, and to create a series of collection channels for condensate which forms during operation. The grooves are formed by integral ribs on the inner surface of the shell, and the grooves are shown at 19 separated by the ribs 20~
The axially extending collectors 3 are positioned closely adjacent the shell and supported by arms 3 with the connection between the collector and its supporting arms provided by means shown at 23 (Figure 3~. This includes a plate 24 provided with a lug 25 fixed to the collector, and a fork 26 fixed to the radially outermost end of the arm 2 and recei~ing the lug 25. A pair of pins 27 (Figure 4) pivotally fix the lub to the fork 26. Between the sides of the fork, there is a spacer washer 28 of a thickness so as to allow axial play of the collector 2 by allowing small displacements of the lug 25 as axial expansion and contraction of the collection occurs due to temperature variations In the arrangement illustrated in Figure 3, each arm 3 is hollow, and its radially innermost end is fixed and supported by means of a flange 29 ~o flange parts 30 of the central shaft 5.
As ~h~wn in Figure 4, each collector 2 has a sub~tantially rectangular section with flat walls 33a, 33b. The upper wall 33a is fixed to ~he pla~e 24 of connection means while the lower plate 34b is located a short distance inwardly from the ribs 20. As shown in Figure 4, the wall 34a and parts of the walls 33a and 33b are constructed from a shaped integral section of ~heet metal, and the other parts of the walls are provi~ed by bars 35 having a greater thickness than that of the wall as illustrated in the sectional view of Figure 4. These bars provide a rigid base for supporting tubes 36.
From the walls 33a and 33b of each collector 2, small tubes 36 extend in a ~ubs~antial tangential direction with respect to the shell 1. These tubes lead from each of the grooves to the interior of the collector 2. The base cr support end 38 of each of the tubes passes through one of the walls 33a and 33b of the associated collector and is inserted into a bushing 39, the threaded outer surface of w~ich is screwed into a corresponding threaded hole formed in the bar 35 of the a~sociated wall 33at 33b. A ring nu~ 40 locks this bushing and the associated small tube to the wall. The outer free end of each of the tubes 36 projects into a radial groove 19 as illustrated in Figure 4. The tube is shaped so that it diminishes in diameter from the base end 38 toward the free end. ~ne free end is cut at a bias so as to be parallel to the inner surface of the base of the groove, and therefore suction flow of the condensate into the tube is enhanced Each of the tubes 36 is made from an elastically deflectable material which is resistant to the temperature of the steam within the cylinder. Preferably, the tubes are formed of metal~ and the tubes in effect are a cantilever elastic beam ~upported on the associated collector with a natural bias or bend so as to cause the free end to spring toward the hase of the groove.
At the free end of each tube is secured a small guide plate 45 (Figures 4 and 5) preferably having a substantially T~
shaped form. This guide plate is a tube positioning element and has a central lug 46 with a hole therethrough into which projects the tubeO The lug is ~ufficiently narrow so that it fits within the groove. ~he lug has at least one, but preferably, a pair of laterally extending arms 47 which rest on the top of the adjacent ribs 20. In this way, the free open end 44 o each tube is held a predetermined very small distance from the bottom surface 19 of the groove as indicated at g in Figures 4 and 60 While other forms of bias may be used, it is preferred that the tube be con~tructed of a resilient material so that it can be mounted at its base to be biased alon~ its length to urge its free end toward the base of the groove. The bias is such that a preload or stress exists in the tube which is counteracted by the tube positioning e~ement 45.
The element rests on the top of the ridges and the ridges' top surface is parallel to the base of the grooves so that essentialLy with expansion or contraction due to temperature difference, the element 45 can slide on the rib without binding.
In the end regions of the headst there is a formed a radial groove :L9a (Figure 2~ of axial width greater than the grooves. In this groove l9a there is inserted a tube 36, the free end of which is rigidly positioned with respect to the bottom of this groove by a plate 45a (Figure 6) fixed to the rib 20 adjacent the groove, such as by qcrews 48. The plate 45a has a hole to receive the tube 43 and allow a limited amount of radial play.
Each discharge tube 18 (Figures 1 and 2) for the discharge of condensate from each collector 2 has a structure such as shown in Figure 8 and includes a first section 49a fitted into the collector itself bylmeans of a sealing assembly 50. This incl~des a pair of flanges 51 and a sealing element S2. Also included is a second section 4gb passing through the wall 15 and connected to the preceding part by means of a ball .J~r..~
joint 53 of a known ~ype. The discharge tube 18 is guided and maintained in position along the sha~t 5 by means of a bushing assembly 54 provided with a flange 55 connected to the wall 4 of the shaft.
Any configuration of tubes 36 projecting from each collector 2 can be employed. Preferably, the tubes are constructed to project alternately in opposite circumferential directions with respect to the supportin~ collector, but different arrangements can be adopted.
In operation steam is supplied to the interior of the drum through the cavity 14 through the hole 12, the cavity ~ and the radial holes 13 for heating the shell. As heat is extracted from the steam for evaporating water from the paper sheet, this causes condensation within the drum which collects at the bottom of the grooves 19 (Figure 3). Through the holes 17 and the cavity 16 a suction is applied which rreates a lowered pressure within the interior of the collectors 2. The condensate, or a mixture of condensate and steam is drawn through the small tubes 36 through the free open ends ~3 having their collection surfa~es 44 in close proximity to the base of the grooves. It is, therefore, apparent that a spacing g between the surfaces 44 and the base is very small, and the condensate can almost completely be sucked up with the intended advantaye of increasing the coef~icient of heat transfer between the steam and the metal of the shell~
During operation of the devicer the shell o one of the cylinders is subjectd to deformations produced by thermal expansion due to the heat within the drum and the removal of heat by the water evapora~ing from the w~b on the ou~er surface of the drum and these circumstances~:will vary during operation. As a consequence of this deformation of the shell, the substantially cylindrical form of the shell and its J~
associated grooves 19 varies~ Such a variation in form does not have any nega~ive effect on the sucking action exerted on the condensate in the bottom of the grooves 19 by the tubes. In fact, whatever the dimensional and form variations of the groove, the clearance space g between ~he surface 44 of a given tube in the bottom surface of the associated groove is maintained constant. This favorable resul~ i5 obtained because the free end of the tube is positioned in a fixed manner with respect to the bottom of the groove both by the action of the plate 45 and by the resilient preloading of ~he tube. Whatever the displacement of the bottom surface of the groove which is located beneath the end surface 44 of the tube, the same displacement occurs on the ribs on either side of the groove.
Because of the abutment on the plate 45 on these ribs, this causes a corresponding displacement of the end of the tube.
The con~densate drawn up into the various collectors is conveyed through the discharge tubes 18, the cavity 16 and the hole 17 out of the drum7 Because of the form of the section of each collector which is rectangular, it can be arranged in a radial position very close to the inner surfaces of the shell with the advantage of improving effectiveness of the suction.
Each tube 36 can be accurately positioned with respect to the associated collector by means of the bushing and ring 39 and ring nut 40 for the purpose of positioning in a correct manner the end 44 of the tube with respect to the bottom surface of the associated groove 19.
While the pre~erred form is illustrated, it will be apparent fro~ the foregoing teaching of the description that various parts of the embodiment of the present invention can be varied without departing from the spirit and scope of the invention.
, .~ , ;
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A steam heated cylindrical dryer drum for continuously drying a traveling paper web in a papermaking machine comprising in combination:
a rotary mounted cylindrical dryer drum having an outer shell with a smooth outer surface with heads at the ends defining a steam containing cavity within;
annular ribs on the inner surface of the shell defining axially spaced grooves in which condensate collects during drying operation as heat is transferred to a web on the drum surface;
a plurality of elongate collector tubes within the drum each having a supporting base end and having a condensate collection free end projecting into a groove and extending in a generally tangential direction being formed of an elastically deflectable material;
a condensate collector rigidly supporting the base end of the tubes with the tubes biased toward the shell so that said free ends tend to move toward the shell;
and a tube positioning element secured to the tube at the free and in supporting engagement with the inner surface of the shell adjacent the grooves fixedly positioning the free end a predetermined distance from the bottom of the groove.
a rotary mounted cylindrical dryer drum having an outer shell with a smooth outer surface with heads at the ends defining a steam containing cavity within;
annular ribs on the inner surface of the shell defining axially spaced grooves in which condensate collects during drying operation as heat is transferred to a web on the drum surface;
a plurality of elongate collector tubes within the drum each having a supporting base end and having a condensate collection free end projecting into a groove and extending in a generally tangential direction being formed of an elastically deflectable material;
a condensate collector rigidly supporting the base end of the tubes with the tubes biased toward the shell so that said free ends tend to move toward the shell;
and a tube positioning element secured to the tube at the free and in supporting engagement with the inner surface of the shell adjacent the grooves fixedly positioning the free end a predetermined distance from the bottom of the groove.
2. A steam heated cylindrical dryer drum for continuously drying a traveling paper web in a papermaking machine constructed in accordance with claim 1:
wherein said tube is secured to the collector with a preload bias in such a manner that the free end of the tube exerts a predetermined force toward the shell.
wherein said tube is secured to the collector with a preload bias in such a manner that the free end of the tube exerts a predetermined force toward the shell.
3. A steam heated cylindrical dryer drum for continuously drying a traveling paper web in a papermaking machine constructed in accordance with claim 1:
wherein said tube positioning element comprises a small plate provided with an opening into which the free end of the tube is inserted and includes a lug engaging the inner surface of the shell.
wherein said tube positioning element comprises a small plate provided with an opening into which the free end of the tube is inserted and includes a lug engaging the inner surface of the shell.
4. A steam heated cylindrical dryer drum for continuously drying a traveling paper web in a papermaking machine constructed in accordance with claim 1:
wherein the shell has a surface which is engaged by the tube positioning element which surface is substantially parallel to the bottom surface of the groove.
wherein the shell has a surface which is engaged by the tube positioning element which surface is substantially parallel to the bottom surface of the groove.
5. A steam heated cylindrical dryer drum for continuously drying a traveling paper web in a papermaking machine constructed in accordance with claim 1:
wherein said condensate collector extends axially and is rectangular in shape with tubes projecting circumferentially from opposite walls of said collector.
wherein said condensate collector extends axially and is rectangular in shape with tubes projecting circumferentially from opposite walls of said collector.
6. A steam heated cylindrical dryer drum for continuously drying a traveling paper web in a papermaking machine constructed in accordance with claim 5:
wherein each of the tubes includes an adjustment means for adjusting the axial position of the tube relative to the collector.
wherein each of the tubes includes an adjustment means for adjusting the axial position of the tube relative to the collector.
7. A steam heated cylindrical dryer drum for continuously drying a traveling paper web in a paper making machine comprising in combination:
a rotary mounted cylindrical dryer drum having an outer shell with a smooth outer surface with heads at the ends defining a steam containing cavity within;
a plurality of radial ribs within the drum defining grooves therebetween;
a plurality of collectors having open condensate receiving ends adjacent the inner surface of the drum;
the collectors being in the form of elongate tubes having fee ends projecting into the grooves and extending in a generally tangential direction;
means biasing the collectors radially toward the drum;
means resisting said bias and limiting the movement of the collectors to limit the position of the free ends of the collectors to be a predetermined distance from the inner surface of the drum;
said means limiting the movement of the collectors to limit the position of the free ends thereof being in the form of a lug secured to the tube and resting on the radial inner surface of the rib.
a rotary mounted cylindrical dryer drum having an outer shell with a smooth outer surface with heads at the ends defining a steam containing cavity within;
a plurality of radial ribs within the drum defining grooves therebetween;
a plurality of collectors having open condensate receiving ends adjacent the inner surface of the drum;
the collectors being in the form of elongate tubes having fee ends projecting into the grooves and extending in a generally tangential direction;
means biasing the collectors radially toward the drum;
means resisting said bias and limiting the movement of the collectors to limit the position of the free ends of the collectors to be a predetermined distance from the inner surface of the drum;
said means limiting the movement of the collectors to limit the position of the free ends thereof being in the form of a lug secured to the tube and resting on the radial inner surface of the rib.
8. A steam heated cylindrical dryer drum for continuously drying a traveling paper web in a paper making machine constructed in accordance with claim 7:
wherein said lug has an adjustment device forcing it radially inwardly to position the free end of the tube.
wherein said lug has an adjustment device forcing it radially inwardly to position the free end of the tube.
9. A steam heated cylindrical dryer drum for continuously drying a traveling paper web in a paper making machine constructed in accordance with claim 8:
wherein said lug is T-shaped with ends resting on adjacent ribs.
wherein said lug is T-shaped with ends resting on adjacent ribs.
10. A steam heated cylindrical dryer drum for continuously drying a traveling paper web in a paper making machine constructed in accordance with claim 7:
wherein the tubes are mounted on their base ends to axially extending collectors;
radially extending arms mounted on a hub within the drum supporting the collectors at the ends;
and angular struts connected between said hub and the outer ends of said arms providing radial and circumferential support for the arms.
wherein the tubes are mounted on their base ends to axially extending collectors;
radially extending arms mounted on a hub within the drum supporting the collectors at the ends;
and angular struts connected between said hub and the outer ends of said arms providing radial and circumferential support for the arms.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000409386A CA1184028A (en) | 1982-08-13 | 1982-08-13 | Sheet paper drying cylinder for a continuous papermaking machine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000409386A CA1184028A (en) | 1982-08-13 | 1982-08-13 | Sheet paper drying cylinder for a continuous papermaking machine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1184028A true CA1184028A (en) | 1985-03-19 |
Family
ID=4123398
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000409386A Expired CA1184028A (en) | 1982-08-13 | 1982-08-13 | Sheet paper drying cylinder for a continuous papermaking machine |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1184028A (en) |
-
1982
- 1982-08-13 CA CA000409386A patent/CA1184028A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEC | Expiry (correction) | ||
| MKEX | Expiry |