FIELD OF THE INVENTION
[001] The present invention in general relates to an expander device
for expanding ends of bank tubes in a drum of a steam generator. More particularly, but not exclusively, the present invention relates to an apparatus for withdrawing an expander device that is damaged or trapped in the bank tube of a drum of the steam generator.
BACKGROUND OF THE INVENTION
[002] Background description includes information that may be useful
in understanding the present subject matter. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed subject matter, or that any publication specifically or implicitly referenced is prior art.
[003] Boiler is a steam generator that is used to generate steam by
applying heat energy to water. Industrial boilers are designed to accommodate load fluctuations according to the needs. This is achieved by the use of multi-drums. The tubes connecting the upper and lower drums are called bank tubes. The bank tubes are expanded in both the drums.
[004] During installation, the bank tubes are required to be inserted
into the upper drum as well as the lower drum such that the ends of the bank tubes extend around 10 to 12 mm above the inner surface of the drums. After inserting, the ends of the bank tubes are expanded in both the drums. Tube expanding or tube rolling is a process of cold working in which the end of the tube comes into contact with the metal of the drum containing the tube holes or seats. When a tube is expanded, the outside diameter, inside diameter and length increases and wall thickness reduces. The increase in length, called extrusion, occurs in both directions. The residual radial pressure between the tube and tube seat resulting from a

properly expanded tube will provide a pressure tight joint of great strength and stability.
[005] A conventional roller expander contains rolls that are set at an
angle to the body of the expander, causing the tapered mandrel to feed inward when it is rotating. As the mandrel feeds inward, the rolls develop the internal force, which expands the tube. The expanded joint presents a simple and economical way of fastening tubes into low-pressure boilers. Under axial loading, the expanded joint is as strong as the tube itself.
[006] There are chances that the during the bank tube expansion work,
the mandrel may get broken. There may be several reasons for it such as higher interference, material weakness, among others.
[007] Conventionally, the broken mandrel is removed by welding a “T”
rod to the body of the broken mandrel. The “T” end is then uniformly hammered from either side to remove the broken mandrel. Hammering causes damage to the inside surface of the tubes. Also, the tool cannot be reused as the “T” rod is welded to the head of the roller guides.
[008] Additionally, this process is cumbersome and also consumes a lot
of time and man power. This further severely affects the steam generation as the boiler needs to be shut down for the entirety of the duration during which the mandrel is being removed. This also causes idling of manpower, thus affecting productivity.
[009] Further, if it is determined that the mandrel cannot be taken out
by hammering as the damage caused to the inside surface of the tube due to hammering will be beyond an acceptable limit, then the tool has to left there with no other option. This will result in the blanking of the tube.

OBJECTS OF THE INVENTION
[0010] In view of the foregoing limitations inherent in the state of the art, some of the objects of the present disclosure, which at least one embodiment herein satisfy, are listed herein below.
[0011] It is an object of the present disclosure to propose an apparatus for withdrawing a damaged tube expander device trapped in a bank tube of a drum of the steam generator.
[0012] It is another object of the present disclosure to propose an apparatus for withdrawing a damaged tube expander trapped in a bank tube without deforming the inside surface of the bank tube.
[0013] It is yet another object of the present disclosure to propose an apparatus to withdraw a damaged tube expander trapped in a bank tube, within a short period of time.
[0014] It is still yet another object of the present disclosure to propose an apparatus for reducing the downtime of a boiler while withdrawing a damaged tube expander trapped in a bank tube.
[0015] It is still another object of the present disclosure to propose an apparatus for withdrawing a broken tube expander trapped in a bank tube with optimum utilization of manpower and resources.
[0016] It is still yet another object of the present disclosure to propose an apparatus that can be reused for withdrawing a damaged tube expander trapped in a bank tube.
[0017] It is still yet another object of the present disclosure to propose an apparatus for eliminating the blanking of tubes.

[0018] It is still yet another object of the present disclosure to propose an apparatus that is safe for withdrawing a damaged tube expander trapped in a bank tube.
[0019] These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated.
SUMMARY OF THE INVENTION
[0020] This summary is provided to introduce concepts related to an apparatus and a method for with drawing a damaged tube expander trapped in a drum of a steam generator. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0021] The present disclosure relates to an apparatus that can be used for withdrawing a damaged tube expander trapped in a bank tube. The apparatus comprises a driving gear, at least one driven gear and a stub. The driving gear is configured to rotate a mandrel of a broken tube expander. The stub is connected to the driven gear, such that free end of the stub is configured to rest on a drum surface. Rotation of the stub is arrested when it is rested on the drum surface. The driven gear, when driven against the stationary stub, moves away from the drum surface in an upward direction and the driven gear moves the driving gear in the upward direction, thereby withdrawing the broken tube expander from a bank tube.

[0022] The present disclosure further relates to a method for withdrawing a damaged tube expander trapped in a bank tube. The method comprises screwing a driving gear to a mandrel of a broken tube expander. Driving, using the driving gear, at least one driven gear and connecting a stub to the driven gear until a free end of the stub rests on a drum surface. Rotation of the stub is arrested when rested on the drum surface. The driven gear, when driven against the stationary stub, moves away from the drum surface in an upward direction and the driven gear moves the driving gear in the upward direction, thereby withdrawing the broken tube expander from a bank tube.
[0023] Other objects, features and advantages of the present disclosure will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating specific embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0024] While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter that is regarded as forming the present subject matter, it is believed that the present disclosure will be better understood from the following description taken in conjunction with the accompanying drawings, where like reference numerals designate like structural and other elements, in which:
[0025] FIG. 1A is an isometric view of an apparatus 100 for withdrawing a broken tube expander 214 trapped in a bank tube 202, (As shown in FIG. 2) in accordance with an embodiment;

[0026] FIG. 1B is a front view of the apparatus 100, in accordance with an embodiment;
[0027] FIG. 2 is a front view of the apparatus 100 being connected to a mandrel 212 of the broken tube expander 214, in accordance with an embodiment;
[0028] FIG. 3 is an isometric view of the apparatus 100 connected to the mandrel 212 before the withdrawal of the broken tube expander 214 from the bank tube 202, in accordance with an embodiment; and
[0029] FIG. 4 is an isometric view of the apparatus 100 withdrawing the broken tube expander 214 from the bank tube 202, in accordance with an embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0030] The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0031] It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “includes”, “consisting” and/or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
[0033] It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
[0034] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[0035] Referring to FIGs. 1A and 1B, disclosed is an apparatus 100 for withdrawing a broken tube expander 214 (shown in FIG. 2) trapped in a bank tube 202 (shown in FIG. 2), in accordance with an embodiment. The apparatus 100 may comprise a driving gear 102, at least one driven gear 104 and a stub 106.

[0036] In an embodiment, the driving gear 102 may be in contact with a drive shaft 112, such that the drive shaft 112 may be configured to rotate the driving gear 102.
[0037] In an embodiment, the drive shaft 112 may be welded to the driving gear 102.
[0038] In an embodiment, the driving gear 102 may comprise a driving bearing collar 110, wherein the driving bearing collar 110 may be connected to the driving gear 102. Rotation of the driving gear 102 may rotate the driving bearing collar 110.
[0039] In an embodiment, the driving bearing collar 110 may define internal threads (not shown) that may be configured to engage with external threads of a mandrel 212 (shown in FIG. 2) of the broken tube expander 214.
[0040] In an embodiment, the driving bearing collar 110 may be welded to the driving gear 102.
[0041] In an embodiment, the driving bearing collar 110 may be enclosed within a driving bearing housing 116.
[0042] In an embodiment, the driving gear 102 may engage with the external threads of the mandrel 212, through the internal threads of driving bearing collar 110.
[0043] In an embodiment, the driving gear 102 may be configured to drive the driven gear 104 such that the rotation of the driving gear 102 may rotate the driven gear 104 in a direction that may be opposite to the direction of rotation of the driving gear 102.

[0044] In an embodiment, a pair of driven gears 104 connected to the driving gear 102 such that each driven gear 104 of the pair may be arranged on either side of the driving gear 102. Thus, the driving gear 102may drive two driven gears 104.
[0045] In an embodiment, the driven gear 104 may comprise a driven bearing collar 108, wherein the driven bearing collar 108 may be connected to the driven gear 104. Rotation of the driven gear 104 may rotate the driven bearing collar 108.
[0046] In an embodiment, the driven bearing collar 108 may define internal threads (not shown) configured to screw the stub 106 to the driven bearing collar 108.
[0047] In an embodiment, the driven bearing collar 108 may be welded to the driven gear 104.
[0048] In an embodiment, the driven bearing collar 108 may be enclosed within a driven bearing housing 118.
[0049] In an embodiment, the driven gear 104 may be configured to screw the stub 106 to the driven gear 104, through the internal threads of driven bearing collar 108.
[0050] In an embodiment, the driving bearing housing 116 and the driven bearing housing 118 may be connected to each other using a connecting plate 120.
[0051] In an embodiment, two sets of driving gears 102 and driven gears 104 may be used, wherein one set of gears 102, 104 may be stacked above the other set of gears 102, 104.

[0052] Referring to FIG. disclosed is a front view of the apparatus 100 being connected to the mandrel 212 of the broken tube expander 214, in accordance with an embodiment. The broken tube expander 214 may be inserted into the bank tube 202 of a drum 204 for tube expanding. During the tube expanding, the mandrel 212 of the tube expander 214 may break and may get trapped in the bank tube 202.
[0053] The external thread of the broken mandrel 212 may be fit into the driving bearing collar 110 by rotating the driving bearing collar 110 with respect to the mandrel 212. After the mandrel 212 has been inserted to a sufficient height into the driving bearing collar 110, a grub screw 122 (shown in FIG. 1B) may be used to lock the relative rotation of the driving bearing collar 110 and the mandrel 212. The driving bearing collar 110 may define a threaded through-hole to accommodate the grub screw 122. The grub screw 122 may be screwed into the through-hole defined by the driving bearing collar 110 and may be tightened to rest on the mandrel 212. This tightening of the grub screw 122 may rotate the mandrel 212 as and when the driving bearing collar 110 is rotated (that is, there is no relative rotation between the two).
[0054] The driving bearing collar 110 is rotated using the driving gear 102, which in turn is rotated using the drive shaft 112. Free end 126 (shown in FIG. 1B) of the drive shaft 112 may define a notch 114 (shown in FIG. 1A) to receive a ratchet 218, wherein the ratchet 218 may be used to operably rotate the drive shaft 112.
[0055] In an embodiment, the free end 126 of the drive shaft 112 may be connected to a hydraulic unit (not shown) that may be configured to operably rotate the drive shaft 112.

[0056] Once the mandrel 212 is locked inside the driving bearing collar 110, the stub 106 may be screwed out from the driven bearing collar 108 until free end 124 (shown in FIGs. 1A and 1B) of the stub 106 may rest on drum surface 206. The rotation of the stub 106 may be locked when the free end 124 of the stub 106 is rested upon the drum surface 206. The stub 106 may define a slot 210. A locking element 208 may be used to lock the rotation of the stub 106.
[0057] In an embodiment, the locking element 208 may be a long rigid shaft 208 whose one end may be affixed to the drum surface 206 and the other end may be received by the slot 210.
[0058] FIGs. 3 and 4 disclose the working of the apparatus 100, in accordance with an embodiment. As discussed previously, the apparatus 100 may be arranged to withdraw the broken tube expander 214 trapped in the bank tube 202. The driving bearing collar 110 may be engaged to the mandrel 212 and its relative rotation may be locked with the help of the grub screw 122. The stub 106 may be screwed out from the driven bearing collar 108 and may be rested on the drum surface 206. The rotation of the stub 106 with respect to the drum surface 206 may be locked with the help of the locking element 208.
[0059] The drive shaft 112 may be rotated using the ratchet 218. The drive shaft 112 may rotate the driving gear 102. The rotation of the driving gear 102 causes the driven gear 104 to rotate in the direction that is opposite to the direction of rotation of the driving gear 102. Also, the rotation of the driving gear 102 results in the rotation of the driving bearing collar 110, which along with it rotates the mandrel 212.

[0060] The rotating driven gear 104 rotates the driven bearing collar 108. Since the rotation of the stub 106, which is screwed to the driven bearing collar 108, is locked, the driven bearing collar 108 moves in an upward direction 402. This motion of the driven bearing collar 108 in the upward direction 402 causes the driving bearing collar 110 also to move in the upward direction 402. This results in the driving bearing collar 110withdrawing the rotating mandrel 212 in the upward direction and along with it the trapped broken tube expander 214 out of the bank tube 202.
TECHNICAL ADVANTAGE
[0061] The present disclosure proposes an apparatus for withdrawing a damaged tube expander trapped in a bank tube without deforming the inside surface of the bank tube.
[0062] The present disclosure proposes an apparatus for reducing the time taken to withdraw a damaged tube expander trapped in a bank tube.
[0063] The present disclosure proposes an apparatus for reducing the downtime of a boiler while withdrawing a damaged tube expander trapped in a bank tube.
[0064] The present disclosure proposes an apparatus for optimum utilization of manpower and resources.
[0065] The present disclosure proposes an apparatus that can be reused for withdrawing a damaged tube expander trapped in a bank tube.
[0066] The present disclosure proposes an apparatus for eliminating the blanking of tubes.
[0067] The present disclosure proposes an apparatus that is safe for withdrawing a broken tube expander trapped in a bank tube.

[0068] Furthermore, each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the “invention” may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the “invention” will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0069] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.
[0070] Furthermore, those skilled in the art can appreciate that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.

[0071] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
[0072] While the foregoing describes various embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof. The scope of the present disclosure is determined by the claims that follow. The present disclosure is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

WE CLAIM:
1. An apparatus (100) for withdrawing a damaged tube expander (214)
trapped in a bank tube (202), the apparatus (100) comprising:
a driving gear (102) configured to rotate a mandrel (212) of a
damaged tube expander (214);
at least one driven gear (104) configured to be driven by the driving
gear (102); and
a stub (106) connected to the driven gear (104), wherein,
free end (124) of the stub (106) is configured to rest on a drum surface (206);
the driven gear (104), when driven against the stationary stub (106), moves away from the drum surface (206) in an upward direction (402); and
the driven gear (104) moves the driving gear (102) in the upward direction (402), thereby withdrawing the damaged tube expander (214) from a bank tube (202).
2. The apparatus (100) as claimed in claim 1, comprising a driving bearing collar (110) connected to the driving gear (102), wherein rotation of the driving gear (102) rotates the driving bearing collar (110).
3. The apparatus (100) as claimed in claim 2, wherein the driving bearing collar (110) defines internal threads configured to engage with external threads defined on the mandrel (212), such that the driving bearing collar (110) and the mandrel (212) rotate relative to each other.

4. The apparatus (100) as claimed in claim 3, comprising a grub screw (122) configured to arrest the relative rotation of the driving bearing collar (110) and the mandrel (212).
5. The apparatus (100) as claimed in claim 1, comprising a driven bearing collar (108) connected to the driven gear (104), wherein rotation of the driven gear (104) rotates the driven bearing collar (108).
6. The apparatus (100) as claimed in claim 5, wherein the driven bearing collar (108) defines internal threads configured to screw the stub (106) to the driven bearing collar (108).
7. The apparatus (100) as claimed in claim 1, comprising a drive shaft (112) connected to the driving gear (102), wherein the drive shaft (112) is configured to rotate the driving gear (102).
8. The apparatus (100) as claimed in claim 7, wherein free end (126) of the drive shaft (112) is in contact with a hydraulic unit configured to operably rotate the drive shaft (112).
9. The apparatus (100) as claimed in claim 7, wherein free end (126) of the drive shaft (112) defines a notch (114) to receive a ratchet (218), wherein the ratchet (218) is configured to operably rotate the drive shaft (112).
10. The apparatus (100) as claimed in claim 1, comprising a locking element (208) configured to arrest the rotation of the stub (106).
11. The apparatus (100) as claimed in claim 11, wherein the stub (106) defines a slot (210) to receive the locking element (208).

12. A method for withdrawing a damaged tube expander (214) trapped in
a bank tube (202), of a drum of the steam generator, the method
comprising:
engaging a driving gear (102) to a mandrel (212) of a damaged tube
expander (214);
driving, using the driving gear (102), at least one driven gear (104);
and
connecting a stub (106) to the driven gear (104), such that a free end
(124) of the stub (106) rests on a drum surface (206), wherein,
rotation of the stub (106) is arrested when rested on the drum surface (206);
the driven gear (104), when driven against the stationary stub (106), moves away from the drum surface (206) in an upward direction (402); and
the driven gear (104) moves the driving gear (102) in the upward direction (402), thereby withdrawing the broken tube expander (214) from a bank tube (202).
13. The method as claimed in claim 12, comprising connecting a driving bearing collar (110) to the driving gear (102), wherein rotation of the driving gear (102) rotates the driving bearing collar (110).
14. The method as claimed in claim 13, wherein the driving bearing collar (110) defines internal threads configured to engage with external threads defined on the mandrel (212), such that the driving bearing collar (110) and the mandrel (212) rotate relative to each other.

15. The method as claimed in claim 14, comprising arresting, using a grub screw (122), the relative rotation of the driving bearing collar (110) and the mandrel (212).
16. The method as claimed in claim 12, comprising connecting a driven bearing collar (108) to the driven gear (104), wherein rotation of the driven gear (104) rotates the driven bearing collar (108).
17. The method as claimed in claim 16, wherein the driven bearing collar (108) defines internal threads configured to screw the stub (106) to the driven bearing collar (108).
18. The method as claimed in claim 12, comprising connecting a drive shaft (112) to the driving gear (102), wherein the drive shaft (112) is configured to rotate the driving gear (102).
19. The method as claimed in claim 18, comprising rotating the drive shaft (112) using a hydraulic unit, wherein free end (126) of the drive shaft (112) is in contact with the hydraulic unit.
20. The method as claimed in claim 18, comprising rotating the drive shaft (112) using a ratchet (218), wherein free end (126) of the drive shaft (112) defines a notch (114) to receive the ratchet (218).
21. The method as claimed in claim 12, wherein the damaged tube expander (214) is trapped within the bank tube (202) of a drum (204).
22. The method as claimed in claim 12, comprising arresting the rotation of the stub (106) using a locking element (208).

23. The method as claimed in claim 22, wherein the stub (106) defines a slot (210) to receive the locking element (208).