FIELD

The present disclosure relates to paper drying machines.

BACKGROUND

The background information herein below relates to the present disclosure but is not necessarily prior art.

Conventional drying machines utilize a rotary joint which provides a passage for fluid exchange, where steam is passed into the cylinder and condensate formed is evacuated from the cylinder simultaneously. However, this makes the construction of the rotary joint complex, as the passage for fluid interaction happens through the shaft of the cylinder. Hence, servicing and maintenance is difficult and requires trained personnel/time. Further, the rotary joint is subjected to complex loading conditions such as fluctuating bending andtwisting loads, which damages the rotary joint. Moreover, inappropriate sealing arrangement leaves the rotary joint prone to leaks, which causes inadvertent mixing of the fluids being handled. Thus, the efficiency of the paper drying process is compromised.

There is, therefore, felt a need, a rotary joint with siphon and sealing mechanism, which alleviates the above mentioned drawbacks.

OBJECTS

Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:

An object of the present disclosure is to provide a rotary joint with siphon and sealing mechanism that offers increased strength against complex fluctuating loads.

Another object of the present disclosure is to provide a rotary joint with siphon and sealing mechanism that offers ease of assembly.

Still another object of the present disclosure is to provide a rotary joint with siphon and sealing mechanism that provides efficient sealing.. Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.

SUMMARY

The present disclosure relates to a rotary joint with a siphon and sealing mechanism comprising a housing defining a cavity with a first end and a second end, the first end configured to be coupled with a head of the siphon pipe and the second end configured to be coupled with a siphon nut. The flat profiles are configured along the periphery of the first end and splines configured along the periphery of the second end at predetermined spaced apart locations. A seal made of composite material constrained between a seal flange and spring loaded primary assembly to keep it in closed condition. The rotary joint facilitates resistance against angular displacement of the siphon pipe and prevent inadvertent mixing of fluids thereby.

In a preferred embodiment, the head of the siphon pipe has flat profiles configured along the periphery of the head.

In a preferred embodiment, the siphon nut is configured with splines configured along the periphery of the siphon nut.

In a preferred embodiment, the first end is configured with a tapered profile.

In a preferred embodiment, the head of the siphon pipe is configured with a tapered profile.

In a preferred embodiment, the first layer and the second layer are made of distinct materials having distinct physical properties.

In a preferred embodiment, the first layer and the second layer are bonded together.

In a preferred embodiment, the first layer and the second layer have distinct dimensions.

In a preferred embodiment, a spider support is configured to support the siphon pipe to facilitate flexibility of the siphon pipe , the spider support comprises a bush having a spherical outer profile and a cylindrical inner profile.

In a preferred embodiment, guide rods are provided inside the rotary joint to facilitate ease of assembly. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING

A rotary joint with siphon and sealing mechanism, of the present disclosure will now be described with the help of the accompanying drawing, inwhich:

Figure 1 shows an isometric view of a drying machine;

Figure 2 shows a sectional view of the drying machine of the Figure 1 ;

Figure 3 shows an isometric view of a rotary joint of prior art;

Figure 4 shows a sectional view of the rotary joint of the Figure 3;

Figure 5 shows a sectional view of a rotary joint, in accordance with another embodiment of the prior art;

Figure 6 shows a sectional view of the rotary joint, in accordance with an embodiment of the present disclosure;

Figure 7-10 show views of the siphon engagement with the housing of the rotary joint, in accordance with an embodiment of the present disclosure;

Figure 11 shows a sectional view of the siphon engagement with the housing of the rotary joint of the Figure 10, in accordance with an embodiment of the present disclosure;

Figure 12a- 12f shows views of a siphon nut and housing which facilitates the engagement and locking of siphon nut to the housingof rotary joint, in accordance with an embodiment of the present disclosure;

Figure 13 shows a detail of the siphon engagement with the housing, in accordance with an embodiment of the present disclosure;

Figure 14 shows a detail of a sight glass provided in the rotary joint, in accordance with an embodiment of the present disclosure;

Figure 15 shows a detail of a sealing arrangement provided in the rotary joint, in accordance with an embodiment of the present disclosure;

Figuree 16 shows a detail of a seal of the figure 15 provided in the rotary joint, in accordance with an embodiment of the present disclosure; Figure 17shows a spider support of the rotary joint, in accordance with another embodiment of the present disclosure;

Figure 18 shows a rotary joint, in accordance with another embodiment of the present disclosure; Figure 19 shows an exploded view of the rotary joint of the figure 18; and

Figure 20 depicts a plot of stresses observed at the interaction of the seal and the seal flange.

LIST OF REFERENCE NUMERALS USED IN DETAILED DESCRIPTION AND DRAWING

1 stationary steam inlet pipe

2 high speed rotary joint

3 stationary condensate outlet pipe

4 mounting bracket

5 dryer bearing housing

6 dryer cylinder

7,51 housing

8 rotary joint end cap

9 horizontal siphon pipe

10 vertical siphon pipe

11 dryer shaft

12 shoe assembly

13 condensate rim

16 4 bolt engagement

17 housing (prior art) 18 end cap (prior art)

19 radial o ring

20 first siphon (prior art)

21 sight glass 22 hollow bolt

23 second siphon (prior art)

24 primary plate

25 seal

26 seal flange 34 siphon

34.49 Siphon Head

35.50 Siphon Nut

37 Splines

38 first oring 39 Siphon Nut Pin

40 Pin Chain

41 second oring

42 Seal

43 Primary flange 44 first layer

45 second Layer 46 Spider Bracket

47 Spherical Profiled Bush

48 Spherical Seating for Bush

52 End Cap- Option 2

53 Spring Loaded Primary Assembly

54 Bolts

55 Guide Rods

56 flat profile

62 first end of annular passage

64 second end of annular passage

66 tapered profile

DETAILED DESCRIPTION

Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.

Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.

The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, elements, components, and/or groups thereof.

Referring to the figures 1-20, a rotary joint 2 with a siphon and a sealing mechanism will be explained in detail. As shown in the figures 1 and 2, a wet paper web is passed over a dryer cylinder 6, which is maintained at high temperature by passing steam therethrough. The rotary joint 2 interfaces components between a stationary inlet steam pipe 1 and the rotating dryer cylinder 6.The steam enters from the stationary steam inlet pipe 1 and passes into the dryer cylinder 6 through the annular area between the horizontal siphon pipe 9 and the dryer shaft 11 bore. When the dryer cylinder 6 rotates along its axis, the thermal energy in the steam gets passed through the inner surface of the dryer cylinder 6 to the paper web passed over the external surface of the cylinder 6.

The rotary joint 2 comprises a housing 7 that facilitates coupling of a horizontal siphon pipe 9. The horizontal siphon pipe 9 faciliates condensate removal formed inside the dryer cylinder 6 and is routed through the dryer cylinder 6. The housing 7 defines an annular passage having a first end 62 and a second end 64. The first end 62 is configured with a tapered profile 66. An identical tapered profile 66 is configured on the head 34 of the siphon pipe 9 to facilitate accurate alignment and leakproof arrangement of the horizontal siphon pipe 9 with the housing 7. The first end 62 is configured with flat profiles 56 on the circumferential periphery of the first end 62. Identical flat profiles 56 are configured on the head 34 of the siphon pipe 9. The flat profiles 56 facilitate engagement of the siphon head 34 with the housing 7 without any possibility of relative angular displacement when the rotary joint 2 is in operation. This is shown in the figures 7-10. The second end 64 of the annular passage is configured with splines 37 on the circumferential periphery of the second end 64. Identical splines 37 are configured on a siphon nut 35 to facilitate locking of the siphon nut 35 with the second end 64 of the housing 7. The assembly is shown in the figure 12-12 f. Thus, the siphon 34 gets aligned to the axis of the dryer cylinder 6 by engaging a single nut 35. This facilitates reduction in stresses induced in the siphon, when compared to conventional pin- key systems. After engaging the siphon nut35, a siphon nut pin 39 is inserted into the splines 37 on the siphon nut 35, which matches with the splines 37 on the second end 64 of the annular passage of the housing 7. The siphon nut pin 39 diameter is configured to resist the torque used to tighten the siphon nut 35, and hence prevents breakage by shock loads. The siphon nut pin 39 may also be reused. A pin chain 40 is attached from the siphon end to the siphon nut pin 39. The pin chain 40 protects the siphon nut pin 39 from getting lost during disassembly, and also provides a mechanism for removal of the siphon nut pin 39.

A plurality of O-rings 38, 42 are provided to ensure sealing between steam and condensate lines as shown in the figure 11. The first O-ring 38 prevents any possibility of leakage between the housing 7 and the siphon nut 35. A second O-ring 42 prevents leakage through the threads. This arrangement facilitates inadvertent mixing between the exchanged fluids viz. the incoming steam and the outgoing condensate.

The angle of the tapered profile 66 on the siphon head 34 is optimized such that the holding force will increase with increase in the inlet steam pressure. The holding force gets automatically and indirectly adjusted to the condensate load by virtue of the tapered profile 66. Optimizing the holding force is facilitated by adjusting the length from the tapered profile 66 to the siphon nut Z and the taper radius Y within a certain ratio as shown in the figure 13. The differential thermal expansion of the stainless steel siphon 9 and the cast iron housing 7 materials allow the holding forces to be increased with increase in temperature of the incoming saturated steam. The length to diameter ratio allows sufficient slipping within the tapered profile 66 such that the thermal expansion will not result in exceeding the allowable stresses, and thus avoiding the rupture of the siphon 9 or the housing 7. Thus, the ratio criterion brings balance between thermal expansion, contact forces and stresses induced. A Finite Element Analysis model simulation facilitates optimization of the tapered profile parameters.

In a preferred embodiment, the siphon 9 is extended upto the edge of a sight glass 21 to ensure that any water coming out of the siphon 9 flows through the line of vision of the sight glass 21 as shown in the figure 14. Thus, a visual inspection of the condensate is made facilitated.

The diameter of primary flange 43 is optimized such that sealing is facilitated by the pressure force exerted due to a piston action. A seal 42 made of a composite material with a first layer 44 of soft material like solid Lubricant filled Polymer like Carbon Filled PTFE and a second layer 45 of a relatively harder material, like Antimony impregnated Graphite AIG. The first layer 44 has a convex spherical profile and the second layer 45 has a flat profile as shown in the figure 15. In an embodiment, the rotation between these layers 44, 45 may be locked using pin or profile arrangement. In another embodiment, the two layers 44, 45 may be bonded together using high temperature adhesive, or they may even have a conical Solid to Solid Contact for facilitating sealing. The profile shape of the first layer 44complies with the profile shape of seal flange 26 through self lapping during running, in a short time. This is required because whenever the steam temperature changes, the seal flange 26 profile also changes due to thermal expansion. This lapping stops whenever the spherical profiles start matching. Then the seal 25 starts rotating with the seal flange 26 and the second layer 45 of antimony graphite starts rubbing with the flat primary flange 43 surfaces. As in constant running conditions, the second layer 45 AIG surface is rubbing; the effective seal life is increased.Atleast six low stiffness springs 53 are provided to accommodate any wobbling during operation. Moreover, the springs 53 advance the primary flange 43 as the seal starts to wear off.

A spider support 46 is installed inside the dryer cylinder 6 such that a support is provided to the siphon 9 from the inner wall of the dryer cylinder 6. A concave spherical seating 48 is inserted into the spider support as shown in the figure 17. A PTFE carbon or AIG bush 47 which has a spherical outer profile and a cylindrical ID is placed inside the seating. The outer profile of the bush 47 matches with the profile that is machined to the SS seating. The siphon pipe 9 has the freedom to axially expand inside the cylindrical surface. The spherical surface accommodates the wobble of the dryer wall and the cylindrical inner surface allows the expansion of the siphon 9. The slipping of the seating may be restricted using a flange.

In another embodiment, the general configuration of the rotary joint 2 is modified as shown in the figure 18. It can be observed that the siphon 49 length is reduced while the length of the siphon nut 50 is increased. In the embodiment shown in the figure 18, the steam and the condensate paths are completely isolated in the housing. This facilitates elimination of requirement of any O-rings. The following sequence of seal replacement may be employed as shown in the figure 19 which reduces the seal change time by 25 percent. i Removing the bolts 54, the end cap 52 is removed from the housing 7. ii Two studs 39 that fasten the housing 7 to the mounting bracket 4 is dismantled and replaced with two guide rods 55. After this, the nuts on the rest of the studs are removed from the housing. iii The Siphon nut pin 39 is removed and the siphon nut 50 is disengaged from the siphon 49. iv The Housing 51 and the sealing cartridge 53 is ‘slid’ backwards over the guide rods just enough to have the siphon end to be visible between the sealing cartridge and the sealing flange. v The used seal 25 is slid over the siphon disengaged from the siphon end, removed through the space between the sealing cartridge and the sealing flange. A new seal is inserted by the reversing the sequence mentioned to remove the seal. vi Now the seal is held in place, and the sealing cartridge with the housing is slid forwards such that the sealing cartridge gets engaged with the seal. The nuts are tightened. The guide rods are removed and replaced with studs and nuts. vii Siphon nut is engaged, and the pin is inserted. The end cap is assembled.

As manual lifting of the components is not necessitated, the effort is highly reduced. No issue of misalignment occurs because the housing and sealing cartridge are slid over the guide rods without losing alignment. The gap between the sealing cartridge and the seal flange is obtained by sliding a very small distance because the siphon end length is reduced to 120mm. In the above mentioned embodiment, the seal 25, the seal flange 26 and the primary plate 24 have the following features to facilitate a shorter period of initial in-process lapping and durability of sealing in the long run. The flat surface of the primary plate 24 is ground and lapped during manufacturing to a surface finish value of 0.4 micron Ra value. The seal flange 26 undergoes spherical lapping by a special hardened spherical lapping tool until the required sphericity is attained and the same surface roughness of 0.4 micron Ra is maintained. The roughness of this value is observed to help in the deposition of a carbon transfer layer on to the seal 25 and the seal flange 26 as the carbon from the seal erodes initially and fills within the undulations of the mating surfaces, giving the surface a smooth texture. The transfer layer is optimal in terms of providing sufficient lubrication to the rubbing surface, hence controlling the aggressive wear and overheating of the seal 25. Still another feature for the embodiment is that the Carbon filled PTFE curved face has a lower radius than the seal flange 26 initially. This causes a higher contact force between the seal 25 and the seal flange 26 initially resulting in aggressive wear during initial lapping phase. I.e. the conforming surface between the seal 25 and the seal flange 26 is formed faster, and in effect it is observed that the sealing action starts within 10 minutes of initial run. The Finite Element Simulation results depicts the instant at which a lower radius seal 25 comes in contact with a higher radius seal flange 26 as shown in the figure 20. Due to the hyper elastic nature of Carbon filled PTFE material; the sealing action is possible at a lower closing force from the primary plate 24. The closing force is contributed by the spring 53 forces, as well as the steam pressure force given by the fluid pressure times the primary plate 24 piston area. By optimizing the piston area, sealing at minimal closing forces and hence minimal overall heating is facilitated.

The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.

TECHNICAL ADVANCES AND ECONOMICAL SIGNIFICANCE

The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a rotary joint with siphon and sealing mechanism that:

• offers efficient sealing between components;

• augments strength of the siphon assembly against fluctuating loads; and

• facilitates ease of assembly and dismantling.

The foregoing description of the specific embodiments so fully reveals the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, step, or group of elements, steps, but not the exclusion of any other element, step, or group of elements, or steps. While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.