Title:
VARYING HELICAL SOOTBLOWER
Kind Code:
A1


Abstract:
A sootblower to project a blowing medium into a boiler and a method of cleaning a boiler using a sootblower are disclosed. The sootblower includes a hub disposed within a housing, in which ends of the hub are configured to receive a lance and the blowing medium. A drive shaft of the sootblower is then configured to rotate the lance with respect to the boiler in a rotational direction at a first ratio relative to the drive shaft when the drive shaft is rotated in a first direction, and is configured to rotate the lance with respect to the boiler in the rotational direction at a second ratio relative to the drive shaft when the drive shaft is rotated in a second direction.



Inventors:
Holden, Wayne W. (Destin, FL, US)
Holden, Michael C. (Destin, FL, US)
Application Number:
11/773358
Publication Date:
09/11/2008
Filing Date:
07/03/2007
Assignee:
HOLDEN INDUSTRIES, LLC (DESTIN, FL, US)
Primary Class:
International Classes:
F28G3/16
View Patent Images:
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Primary Examiner:
DANIEL, JAMAL D
Attorney, Agent or Firm:
Pillsbury Winthrop Shaw Pittman, LLP (McLean, VA, US)
Claims:
What is claimed is:

1. A sootblower to project a blowing medium into a boiler, the sootblower comprising: a drive shaft configured to axially insert a lance into a boiler when rotated in a first direction and axially remove the lance from the boiler when rotated in a second direction; the drive shaft configured to engage a first rotational mechanism when rotated in the first direction, wherein the first rotational mechanism is configured to rotate the lance with respect to the boiler in a rotational direction at a first ratio relative to the drive shaft; and the drive shaft configured to engage a second rotational mechanism when rotated in the second direction, wherein the second rotational mechanism is configured to rotate the lance with respect to the boiler in the rotational direction at a second ratio relative to the drive shaft.

2. The sootblower of claim 1, further comprising a hub connecting the lance to a feed line supplying the blowing medium to the sootblower.

3. The sootblower of claim 2, further comprising a housing to contain the drive shaft, the hub, and the first and second rotational mechanisms.

4. The sootblower of claim 3, further comprising a lubricant disposed within the housing.

5. The sootblower of claim 2, wherein the hub comprises an inner wall and an outer wall with a gap disposed therebetween, wherein the outer wall comprises vents.

6. The sootblower of claim 1, further comprising pinion gears attached to the drive shaft and configured to engage a rack to provide translational motion for the sootblower.

7. The sootblower of claim 1, wherein the blowing medium is steam.

8. The sootblower of claim 1, wherein the lance comprises a venturi nozzle.

9. The sootblower of claim 1, further comprising a worm gear attached to the drive shaft, wherein a motor is configured to bidirectionally rotate a worm engaging the worm gear such that the worm rotates the drive shaft.

10. The sootblower of claim 1, wherein the first rotational mechanism and the second rotational mechanism comprise one-way rotational mechanisms.

11. A sootblower used to project a blowing medium, comprising a hub disposed within a housing, wherein a first end of the hub is configured to receive a lance and a second end of the hub is configured to receive the blowing medium; and a drive assembly configured to convert bidirectional rotational motion from a drive shaft into unidirectional rotational motion for a hub, wherein a ratio of a first direction of the bidirectional rotational motion to the unidirectional rotational motion varies from a ratio of a second direction of the bidirectional rotational motion to the unidirectional rotational motion.

12. The sootblower of claim 11, wherein the drive assembly comprises: a first one-way rotational mechanism and a second one-way rotational mechanism attached to the drive shaft; and a first gear train and a second gear train engaged with the first one-way rotational mechanism and the second one-way rotational mechanism, respectively; wherein the each of the first gear train and the second gear train is configured to engage the hub.

13. The sootblower of claim 12, wherein the drive shaft, the first and second one-way rotational mechanisms, and the first and second gear trains are disposed within the housing.

14. The sootblower of claim 13, further comprising a lubricant disposed within the housing.

15. The sootblower of claim 14, wherein the lubricant comprises synthetic oil.

16. The sootblower of claim 11, further comprising a worm gear attached to the drive shaft, wherein a motor is configured to provide bidirectional rotational motion to a worm engaging the worm gear, thereby providing bidirectional rotational motion for the drive shaft.

17. The sootblower of claim 16, further comprising rollers rotatably attached to the housing and configured to travel along tracks.

18. The sootblower of claim 17, further comprising an intermediate support attached to one of the tracks to support the lance and electrical cords distributed outside and along the other of the tracks.

19. A method for cleaning a boiler using a sootblower in accordance with claim 1.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit, under 35 U.S.C. §119, of U.S. Provisional Application Ser. No. 60/893,738, filed on Mar. 8, 2007 and entitled “Varying Helical Sootblower” in the name of W. Wayne Holden and Michael C. Holden. The disclosure of this U.S. Provisional Application is incorporated herein by reference in its entirety.

BACKGROUND OF DISCLOSURE

1. Field of the Disclosure

Embodiments disclosed herein generally relate to sootblowers. More specifically, embodiments disclosed herein relate to an improved sootblower used to project a stream of a sootblower medium within a combustion device.

2. Background Art

Generally when combusting fuel in large boilers, as used in electric and steam generating plants, or in recovery boilers, as used in paper and pulp mills, large quantities of particulate matter from burned fuel may quickly accumulate within the interior surfaces and tubes of the boilers. Specifically, the particulate matter, such as soot and tar, may accumulate on the heat exchanger surfaces and tubes in these boilers to significantly reduce the boilers' efficiencies. To prevent such particulate matter buildup, sootblowers may be used to provide a substantially continuous cleaning of the interior surfaces of the boilers.

Typically, sootblowers are permanently installed between adjacent rows of heat exchanger tubes within a boiler so that the sootblowers may provide regular, if not substantially continuous, cleaning without the need for the boiler to be taken out of service during the cleaning. As such, it is common for each of the large boilers and the paper mill boilers to have up to fifty or more sootblowers attached for cleaning. To maintain operating efficiency, each sootblower may be operated on a regular cycle, such as about once an hour, depending on the size of the boiler and severity of the accumulation of particulate matter.

One commonly used sootblower is a long retracting sootblower. Examples of such sootblowers are shown and described in U.S. Pat. Nos. 5,675,863 and 5,745,950, which is incorporated by reference in its entirety. These sootblowers generally include a long pipe or lance having a nozzle at the end for directing a blowing medium, such as steam or another vapor, onto the surfaces of the heat exchanger tubes. An example of a lance 102 cleaning a boiler 190 is shown in FIG. 1. Lance 102, having nozzles 104 at an end for directing a blowing medium 106, is inserted through a hole 194 of a wall 192 of boiler 190. Lance 102 should be sufficient in length such that the entire length of heat exchanger tubes 196 of boiler 190 may be accessed by lance 102. Lance 102 is then usually attached to a moveable carriage or housing with a motor (not shown) to reciprocate and rotate (as indicated by arrows) lance 102 within boiler 190 for effective cleaning. Specifically, upon actuation, lance 102 will reciprocate into boiler 190 and rotate at a generally continuous speed. Blowing medium 106 is exerted through nozzles 104 as lance 102 is in motion, thereby blowing off accumulated particle matter 198 and cleaning heat exchanger tubes 196.

When actuated and reciprocated into and out-of the boiler, the lance generally will follow a standard helical path, as shown in FIG. 2A. Specifically, the nozzle of the lance may follow path 280 when extended into and retracted from the boiler. However, as the nozzle follows path 280, substantial portions of the boiler and the heat exchanger tubes may fail to be reached by blowing medium from the nozzle of the lance. Thus, particulate matter may still accumulate on the boiler's internal surfaces and heat exchanger tubes that do not fall within path 280 of the nozzle of the lance.

Advances have been made to sootblowers to improve upon the typical helical path. In one example, shown in FIG. 2B, the nozzle of the lance may incorporate a phase-shift into the standard helical path. Such a phase-shift may include temporarily stopping the rotation of the lance, thereby providing more coverage when cleaning the sootblowers. Thus, when first extended into the boiler, the nozzle may follow a first extension path 282. Upon full extension into the boiler though, the lance and nozzle may shift phase, for example, by about 30 degrees, so that as the lance is retracted, the nozzle on the lance may follow a first retraction path 284, distinct from first extension path 282. Upon the next trip into the boiler, the lance and nozzle may shift phase again, by about 15 degrees, so that the lance is extended into the boiler along a second extension path 286, distinct from first extension and retraction paths 282 and 284. Then, upon retraction from the boiler, the nozzle and lance may shift phase again, by about another 30 degrees, so that the lance may follow a second retraction path 288, distinct from previous paths 282, 284, and 286. Thus, with the phase-shifts, the path of the nozzle may be improved to cover more area than that of the standard helical path, as shown in FIG. 2A.

While this improvement upon the standard helical path may provide improved coverage and cleaning, the nozzle will generally follow a series of parallel paths, only differentiated by a phase-shift. This may still leave portions of the boiler and the heat exchanger tubes not covered by the blowing medium from the nozzle, thus still not completely cleaning the boiler. Accordingly, there exists a need for a sootblower that may improve the coverage of the nozzle to provide more coverage of cleaning of boilers, thereby increasing the efficiency of the boilers.

SUMMARY OF INVENTION

In one aspect, embodiments disclosed herein relate to a sootblower to project a blowing medium into a boiler. The sootblower includes a drive shaft configured to axially insert a lance into a boiler when rotated in a first direction and axially remove the lance from the boiler when rotated in a second direction. Further, the drive shaft is configured to engage a first rotational mechanism when rotated in the first direction, in which the first rotational mechanism is configured to rotate the lance with respect to the boiler in a rotational direction at a first ratio relative to the drive shaft. Furthermore, the drive shaft is configured to engage a second rotational mechanism when rotated in the second direction, in which the second rotational mechanism is configured to rotate the lance with respect to the boiler in the rotational direction at a second ratio relative to the drive shaft.

In another aspect, embodiments disclosed herein relate to a sootblower to project a blowing medium. The sootblower includes a hub disposed within a housing, in which a first end of the hub is configured to receive a lance and a second end of the hub is configured to receive the blowing medium. The sootblower further includes a drive assembly configured to convert bidirectional rotational motion from a drive shaft into unidirectional rotational motion for a hub, in which a ratio of a first direction of the bidirectional rotational motion to the unidirectional rotational motion varies from a ratio of a second direction of the bidirectional rotational motion to the unidirectional rotational motion.

Other aspects and advantages of the invention will be apparent from the following description and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a view of a prior art lance attached to a sootblower.

FIGS. 2A and 2B show a view of helical paths of a prior art sootblower.

FIG. 3 shows a top-down view of a sootblower in accordance with embodiments disclosed herein.

FIG. 4 shows a cross-sectional view taken along line A-A of the sootblower shown in FIG. 3 in accordance with embodiments disclosed herein.

FIG. 5 shows a cross-sectional view of a motor and a sootblower in accordance with embodiments disclosed herein.

FIG. 6 shows a cross-sectional view taken along line B-B of the sootblower shown in FIG. 4 in accordance with embodiments disclosed herein.

FIG. 7 shows a cross-sectional view taken along line B-B of the sootblower shown in FIG. 4 in accordance with embodiments disclosed herein.

FIG. 8 shows a view of helical paths of a sootblower in accordance with embodiments disclosed herein.

DETAILED DESCRIPTION

In one aspect, embodiments disclosed herein relate to an improved sootblower with a drive assembly configured to supply different ratios of translational motion to rotational motion as a lance of the sootblower is extended into and retracted from a boiler. In another aspect, embodiments disclosed herein relate to a sootblower having a hub and a lance positioned substantially on a vertical centerline of the sootblower. In yet another aspect, embodiments disclosed herein relate to a drive shaft having two one-way rotational mechanisms attached thereto in opposing directions such that as the drive shaft is rotated, one of the one-way rotational mechanisms is activated and imparts motion to the hub while the other of the one-way rotational mechanisms is deactivated.

Referring to FIG. 3, a sootblower 300 in accordance with embodiments disclosed herein is shown. Sootblower 300 includes a housing 301 configured to receive a lance 302. Lance 302 may have a long, tubular construction and include one or more nozzles 304. As shown, nozzle 304, preferably a venturi nozzle, is disposed at the end of lance 302. However, those having ordinary skill in the art will appreciate that the invention is not so limited, and the nozzle may be disposed at any location on or about the lance. Nevertheless, lance 302 is configured to connect with a hub 310, such as connecting a flange 308 of lance 302 with a flange 312 of hub 310. Hub 310 may be rotationally disposed within housing 301 such that hub 310 is able to rotate with respect to housing 301. As such, when hub 310 rotates, lance 302 will accordingly rotate therewith. Further, hub 310 is configured to receive a blowing medium, such as through a feed tube 317. As shown, a valve 316 may supply the blowing medium to feed tube 317, in which the blowing medium may then be transported through hub 310 to lance 302 to exert the blowing medium through nozzle 304. Preferably, the blowing medium used is steam, such as superheated steam of about 750° F. (400° C.); however, any high-pressure and/or high-temperature vapor or gas known in the art may be used.

Sootblower 300 further includes a motor 318 configured to supply power and provide rotational movement to hub 310 and translational movement to housing 301. Specifically, using a drive assembly disposed within housing 301, motor 318 rotates hub 310 and lance 302, in addition to moving housing 301 along tracks 322. In one embodiment, rollers 320 may be rotatably attached to housing 301 through, for example, legs 324 attached to housing 301. Rollers 320 may then travel along tracks 322 to support the weight and enable translational movement for sootblower 300. Thus, when used in a boiler cleaning application, the lance of the sootblower may be reciprocated into and out-of the boiler while rotating. Further, sootblower 300 may include intermediate supports (not shown) disposed underneath lance 302 and/or feed tube 317 to prevent excessive bending or deflection thereof. As such, the intermediate supports may attach to one of tracks 322 to support lance 302 and feed tube 317. This arrangement of the intermediate supports attached to only one of tracks 322 may allow necessary electrical cords and power to be distributed to motor 318 and housing 301 outside and along the other of tracks 322. An example of motor 318 that may be used within sootblower 300 is a 1,750 revolutions per minute, 2 horsepower electric motor. Those having ordinary skill in the art will appreciate that any suitable motor may be used.

Referring now to FIG. 4, a cross-section taken along line A-A of sootblower 300 of FIG. 3 in accordance with embodiments disclosed herein is shown. Sootblower 300 includes a drive assembly 330 disposed within housing 301. Generally, drive assembly 300 is configured to receive bidirectional rotation from the motor (e.g., 318 shown in FIG. 3) of the sootblower. This bidirectional rotation is then converted by drive assembly 330 into unidirectional rotation for hub 310. Thus, as the housing of the sootblower travels back-and-forth along the tracks to extend and retract the lance within the boiler, the lance remains rotating in the same direction.

For example, when the sootblower is translationally moving along the track towards the boiler with the lance being extended into the boiler, the motor and the hub/lance may rotate in the clockwise direction. However, when the sootblower is translationally moving along the track away from the boiler with the lance being retracted from the boiler, the motor may reverse directions to rotate in the counter-clockwise direction, while the hub/lance remains to rotate in the clockwise direction. Thus, bidirectional rotation from the motor is converted into unidirectional rotation for the hub and the lance attached thereto. This conversion of bidirectional rotation to unidirectional rotation is described further below.

Generally motor 318 provides bidirectional rotational movement to a drive shaft 340 of drive assembly 330. Specifically, referring now to FIGS. 4 and 5 together, motor 318 may provide bidirectional rotation to a worm 326. Worm 326, disposed within housing 301, is also configured to bidirectionally rotate, corresponding to the bidirectional rotation of motor 318. For example, as motor 318 rotates clockwise and then counter-clockwise, worm 326 may correspondingly rotate clockwise and then counter-clockwise. Worm 326 is then configured to engage a worm gear 342 attached to drive shaft 340. Thus, worm gear 342 is configured to bidirectionally rotate drive shaft 340 from engagement with worm 326. Further, the arrangement of worm 326 and worm gear 342 may take advantage of ratios of revolutions therebetween, in which the ratio of revolutions of the worm to the worm gear may be of the magnitude of about 1:36. Those having ordinary skill in the art, though, will appreciate that the invention is not so limited, and any arrangement and ratio between the worm and the worm gear may be used.

Drive shaft 340, powered by motor 318 using, for example, worm 326 and worm gear 342, is used to provide translational motion for housing 301, and also provide rotational motion to hub 310. As such, to provide translational motion for housing 301, pinion gears 346 may be attached to the ends of drive shaft 340. Pinion gears 346 may be configured to engage a rack (not shown) attached or formed to tracks 322 (shown in FIG. 3). Specifically, for example, teeth of pinion gears 346 may be configured to engage teeth of the rack to transfer the rotational motion of pinion gears 346 and drive shaft 340 into translational motion for housing 301 of sootblower 300. Thus, by switching rotational directions of motor 318, the translational direction of housing 301 may be controlled through drive shaft 340 within pinion gears 346 and the rack.

Further, to provide rotational motion for hub 310, rotational mechanisms 350A and 350B are attached to drive shaft 340. One-way rotational mechanisms 350A and 350B are configured to transmit rotation from drive shaft 340 to a first gear train 360A and a second gear train 360B, respectively. As such, when one of one-way rotational mechanisms 350A and 350B is engaged and transmitting rotation from drive shaft 340 to gear trains 360A and 360B, the other of one-way rotational mechanisms 350A and 350B is not engaged, thereby not transmitting rotation from drive shaft 340 to gear trains 360A and 360B. For example, one-way rotational mechanisms 350A and 350B are configured to engage and transmit rotation from drive shaft 340 to gear trains 360A and 360B only when drive shaft 340 is rotating in one direction. When drive shaft 340 is rotating in the opposite direction, one-way rotational mechanisms are then configured to not engage such that no rotation is transmitted from drive shaft 340 to gear trains 360A and 360B. More discussion of one-way rotational mechanisms is provided below.

Referring now to FIG. 6, a cross-section taken along line B-B of one-way rotational mechanism 350A of FIG. 4 in accordance with embodiments disclosed herein is shown. One-way rotational mechanism 350A is disposed about drive shaft 340 and includes a pin 352A and a biasing mechanism 354A. As shown, drive shaft 340 may include a plurality of teeth 344A formed therein, in which each tooth 343A is formed with a stop face 344A. Using biasing mechanism 354A, such as a spring (as shown), pin 352A may be biased towards drive shaft 340 to contact teeth 343A formed on drive shaft 340.

Thus, when drive shaft 340 is rotated in direction D1 (e.g., clockwise) with respect to one-way rotational mechanism 350A, one-way rotational mechanism 350A engages and rotates with drive shaft 340. Specifically, pin 352A is biased into contact and engagement with stop face 344A of teeth 343A, thereby engaging one-way rotational mechanism 350A to prevent relative rotation between drive shaft 340 and one-way rotational mechanism 350A when drive shaft is rotated in direction D1.

However, when drive shaft 340 is rotated in direction D2 (e.g., counter-clockwise) with respect to one-way rotational mechanism 350A, one-way rotational mechanism 350A does not engage with drive shaft 340. Instead, pin 352A will preferably slide over teeth 344A to not rotate with drive shaft 340, thereby having one-way rotational mechanism 350A freewheeling about drive shaft 340. Thus, the one-way rotational mechanism is configured to engage when the drive shaft is rotated in one direction, but is configured to not engage when drive shaft is rotated in the other direction.

One-way rotational mechanism 350B may be of similar construction or arrangement as one-way rotational mechanism 350A; however, those having ordinary skill in the art will appreciate that the invention is not so limited. Further, those having ordinary will appreciate that other one-way rotational mechanisms known in the art may be used with the present invention, such as a one-way clutch or one-way bearings, without departing from the scope of the present invention.

Referring back to FIG. 4, one-way rotational mechanisms 350A and 350B are attached to drive shaft 340 and oriented in different directions from one another. As such and described above, when drive shaft 340 is rotated in one direction, one of one-way rotational mechanisms 350A and 350B is engaged while the other of one-way rotational mechanisms 350A and 350B does not engage. Further, when drive shaft 340 is rotated in the other direction, one-way rotational mechanisms 350A and 350B reverse roles of engaging and not engaging. These one-way mechanisms 350A and 350B may then be attached or configured to engage gear trains 360A and 360B. As shown, in this embodiment, one-way mechanisms 350A and 350B are attached to spur gears 362A and 362B of gear trains 360A and 360B, respectively. Thus, as one-way rotational mechanisms 350A and 350B engage drive shaft 340 and rotate, this rotation is transferred from one-way rotating mechanisms 350A and 350B to spur gears 362A and 362B. In this embodiment, spur gears 362A and 362B may then be rotatably disposed about drive shaft 340, but not attached to drive shaft 340. Further, as shown, one-way rotating mechanisms 350A and 350B and spur gears 362A and 362B may include bearings 344, such as ball bearings (as shown), roller bearings, or any other similar devices known in the art. Bearings 344 may be used to facilitate the rotation of one-way rotating mechanisms 350A and 350B and spur gears 362A and 362B when not engaged with drive shaft 340.

Referring still to FIG. 4, in addition to spur gears 362A and 362B, gear trains 360A and 360B further include additional spur gears 364A and 364B and bevel gears 366A and 366B. Spur gears 362A and 362B are configured to engage additional spur gears 364A and 364B through, for example, the engagement of teeth (not shown) formed thereon. Further, additional spur gears 364A and 364B include bevel gears 366A and 366B attached thereto. Thus, as spur gears 362A and 362B rotate, this rotational motion is translated through additional spur gears 364A and 364B to rotate bevel gears 366A and 366B. Accordingly, as one-way rotational mechanisms 350A and 350B are engaged to rotate with drive shaft 340, corresponding gear train 360A and 360B will also rotate with drive shaft 340.

Further, bevel gears 366A and 366B of gear train 360A and 360B are configured to engage and rotate hub 310. Specifically, bevel gears 366A and 366B may engage a bevel gear 311 attached to and/or formed upon hub 310. As such, through the engagement of teeth (not shown), for example, bevel gears 366A and 366B may rotate bevel gear 311 of hub 310. Thus, when one-way rotational mechanism 350A is engaged, thereby rotating gear train 360A, bevel gear 366A of gear train 360A will engage bevel gear 311 and rotate hub 310. Bevel gear 366B and gear train 360B may still be engaged with bevel gear 311 of hub 310 during this rotating motion provided by gear train 360A, but because one-way rotational mechanism 350A is engaged and providing rotational motion to hub 310, one-way rotational mechanism 350B is not engaged, thus not providing any rotational motion to hub 310. Specifically, because one-way rotational mechanisms 350A and 350B are oriented in opposing directions when attached to drive shaft 340, only one of one-way rotational mechanisms 350A and 350B may be engaged to translate the rotational motion from drive shaft 340 along to hub 310, while the other of one-way rotational mechanisms 350A and 350B may then be not engaged, and thereby freewheeling about the drive shaft 340.

Furthermore, using the arrangement shown of gear trains 360A and 360B coupled with the orientation of one-way rotational mechanisms 350A and 350B, hub 310 may always be rotated in the same direction, regardless of the direction of rotation of drive shaft 340, worm 326, or motor 318. Specifically, the bidirectional rotational motion of drive shaft 340, worm 326, and/or motor 318 may be converted to unidirectional rotational motion of hub 310. For example, when worm 326 is rotated by motor 318 in a clockwise direction or in a counter-clockwise direction (i.e., bidirectional rotation), the arrangement of drive shaft 340 with one-way rotational mechanisms 350A and 350B and gear trains 360A and 360B may be such that hub 310 will still always be rotated in only the clockwise direction (i.e., unidirectional rotation). Thus, as the motor changes directions in rotation when the sootblower is moving back-and-forth along the tracks to extend and retract the lance from a boiler, the hub may always continue to rotate in the same direction, independent of the rotational direction of the motor.

Referring now to FIG. 7, a cross-section taken along line C-C of hub 310 and gear trains 360A and 360B shown in FIG. 4 in accordance with embodiments disclosed herein is shown. As discussed above, hub 310 is configured to receive lance 302 and a blowing medium, such as through feed tube 317. Thus, as shown in FIG. 7, feed tube 317 may pass through hub 310 and into lance 302, lance 302 threadedly connected to hub 310, thereby depositing the blowing medium into lance 302. The blowing medium from feed tube 317 may then flow out nozzles 304 (shown in FIG. 3) disposed at the other end of lance 302. To prevent any leakage of the blowing medium, sootblower 300 may include a packing set 367 disposed about feed tube 317. Specifically, packing set 367 may include bushings 368 with packing seals 369 disposed therebetween, in which bushings 368 may be pushed together to provide scaling engagement of packing seals 369 about feed tube 317.

As shown, hub 310 may further include an inner wall 370A and an outer wall 370B with a gap 371 disposed therebetween. Gap 371, coupled with vents 372 disposed about hub 310, may be used to provide air cooling of hub 310. Alternatively, gap 371 may include any other medium known in the art for cooling of hub 310. Regardless, this arrangement for hub 310 may then be used to more efficiently dissipate heat from hub 310 and/or permit air flow through hub 310, thereby minimizing heat transfer from feed tube 317 to hub 310 and limiting expansion of any parts. Further, as described above, hub 310 is rotatably disposed within housing 301. As such, sootblower 300 may include a plurality of roller bearings 373 with protective seals 374 disposed between hub 310 and housing 301. These roller bearings 373 may then enable hub 310 to rotate with respect to housing 301 while still securing hub 310 within housing 301.

Preferably, the gear trains that provide the rotational motion from the drive shaft to the hub are provided with varying or different ratios. If the gear trains are provided with ratios to vary or differ from one another, the helical path of the lance being extended into a boiler may then differ from the helical path of the lance being retracted from the boiler. For example, by using multiple gear trains as described above, one gear train may be used to rotate the hub as the lance is being extended into the boiler, and the other gear train may be used to rotate the hub as the lance is being retracted from the boiler. In such an embodiment, the gear trains may be configured such that the lance may rotate at one rotational speed or ratio (e.g., 20 revolutions per minute or 20 revolutions per foot) when extended into the boiler, and may then rotate at a different rotational speed or ratio when retracted from the boiler (e.g., 15 revolutions per minute or 15 revolutions per foot).

Referring now to FIG. 8, a helical path 880 of a sootblower in accordance with embodiments disclosed herein is shown. In this embodiment, the sootblower includes gear trains that provide rotational motion of different ratios to the hub to produce helical path 880. Described in another way, the ratio of the rotational motion of the hub when extended into the boiler varies from the ratio of the rotational motion of the hub when retracted from the boiler. Further, described more generally, the ratio of a first direction of the bidirectional rotational motion of the drive shaft to the unidirectional rotational motion of the hub varies from the ratio of a second direction of the bidirectional rotational motion of the drive shaft to the unidirectional rotational motion of the hub. As shown, when first extended into the boiler, the nozzle of a lance attached to the hub may follow a first extension path 882. Upon full extension into the boiler then, the nozzle on the lance may then follow a first retraction path 884. Because taking advantage of the conversion of the bidirectional rotation of the drive shaft to unidirectional rotation of the hub, the orientation of first extension path 882 will oppose the orientation of first retraction path 884. Specifically, as shown, the orientation of first extension path 882 may be positive with respect to horizontal axis 881, while the orientation of first retraction path 884 may be negative with respect to horizontal axis 881.

Further, still referring to FIG. 8, because the ratios of the gear trains for rotating the hub may vary and differ, the slope of first extension path 882 may differ from the slope of first retraction path 884. Specifically, as shown, the slope of first extension path 882 may be about sixty degrees with respect to horizontal axis 881, whereas the slope of first retraction path 884 may be about forty-five degrees with respect to horizontal axis 881. In this embodiment, the ratio of the gear train rotating the hub as the lance is extended into the boiler is higher than the ratio of the gear train rotating the hub as the lance is retracted from the boiler. As such, the slope of extension paths 882 and 886 is higher than that of retraction paths 884 and 888. Furthermore, the sootblower may incorporate phase-shifts so that upon the next cleaning or trip into the boiler, the nozzle of the sootblower may follow a second extension path 886 and a second retraction path 888 differing from that of first extension path 882 and first retraction path 884.

Those having ordinary skill in the art will appreciate that the present disclosure is not limited to the specific ratios used for the gear trains of the sootblower. For example, the ratio of gear train 360A may be higher or lower than the ratio of gear train 360B. Further, those having ordinary skill in the art will appreciate that the present disclosure is not limited to a specific arrangement of gears within the gear trains of the sootblower. For example, the gear trains may incorporate more gears or fewer gears into the gear assembly, or different sizes of gears, and the numbers and sizes of gears between the gear trains may vary and differ.

Further, as shown in FIG. 4, the hub may be positioned substantially on the vertical centerline of the housing of the sootblower, as hub 310 is positioned substantially on vertical centerline 331 of housing 301. In such an embodiment, this enables the majority of the weight from the hub, with the lance and feed tube attached thereto, to be evenly distributed along the drive shaft and amongst the rollers of the sootblower to give the sootblower a balanced design.

Furthermore, the hub, the drive shaft, the one-way rotational mechanisms, and the gear trains may be disposed within the housing of the sootblower and submerged in a lubricant. For example, a lubricant of synthetic oil, or any other lubricant known in the art, may be disposed and sealed within the housing of the sootblower. This may be used to preserve and maintain the moving parts disposed within the housing of the sootblower.

Embodiments of the present disclosure may provide for one or more of the following advantages. First, embodiments disclosed herein may provide a more efficient cleaning of boilers because of the different and varying paths used by the nozzles. Specifically, the nozzle may have an increased amount of paths to follow when cleaning boilers, thereby improving coverage when cleaning. Next, embodiments disclosed herein may provide a more economical sootblower for cleaning of boilers. For example, as shown, the sootblower described herein may only include one motor, thereby preventing cost of an additional motor. Further, embodiments disclosed herein may provide for a sootblower with an increased working life. For example, because the sootblower described herein may incorporate a balanced design, in addition to lubricant disposed therein, the working life of the sootblower may be extended by preventing unnecessary wear of parts.

While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.