DUAL-MOTOR SOOTBLOWER

Abstract

A sootblower to project a blowing medium into a boiler is disclosed herein. The sootblower includes a hub, a first motor, a second motor, a gear train, and a drive shaft. The hub comprises a first end to receive a lance and a second end to receive the blowing medium. Further, the gear train is configured to convert rotation of the first motor into rotation of the lance, and the drive shaft is configured to convert bidirectional rotation of the second motor into translational motion of the lance.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit, under 35 U.S.C. §119, of U.S. Provisional Application Ser. No. 60/911,248, filed on Apr. 11, 2007 and entitled “Dual-Motor 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 hub, a first motor, a second motor, a gear train, and a drive shaft. The hub comprises a first end to receive a lance and a second end to receive the blowing medium. Further, the gear train is configured to convert rotation of the first motor into rotation of the lance, and the drive shaft is configured to convert bidirectional rotation of the second motor into translational motion of the lance.

In another aspect, embodiments disclosed herein relate to a sootblower to project a blowing medium. The sootblower includes a first motor, a second motor, a drive assembly, and a drive shaft. The gear train is configured to convert rotation of the first motor into rotation of the lance, and the drive shaft is configured to convert bidirectional rotation of the second motor into translational motion of the lance. Further, the drive assembly comprises a gear train having a first spur gear, a second spur gear, and a bevel gear. The first motor is configured to provide rotation to the first spur gear, the first spur gear is configured to provide rotation to the second spur gear, the second spur gear is configured to provide rotation to the bevel gear, and the bevel gear is configured to provide rotation to the lance.

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 prior art sootblowers.

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.

DETAILED DESCRIPTION

In one aspect, embodiments disclosed herein relate to an improved sootblower having two motors, one motor independently controlling a rotation of a lance attached to a hub of the sootblower, and the other motor independently controlling translational motion of the sootblower. In another aspect, embodiments disclosed herein relate to a sootblower having a first motor and a second motor, in which the first motor rotates a gear train of the sootblower and the second motor rotates a drive shaft of the sootblower. In yet another aspect, embodiments disclosed herein relate to a sootblower with a gear train, in which the gear train includes two spurs gears and a bevel gear to provide rotation to a hub within the sootblower.

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 two motors 318A, 318B configured to supply power and provide rotation to hub 310 and translational movement to housing 301. Specifically, motor 318A rotates hub 310 and lance 302 using a drive assembly (shown in FIG. 4) disposed within housing 301, and motor 318B moves housing 301 back-and-forth 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 for motors 318A, 318B 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, though, 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 rotation from the motors (e.g., 318A and 318B shown in FIG. 3) of the sootblower. Then, the rotation from one of the motors is converted by drive assembly 330 into rotation for hub 310, and the rotation from the other of the motors is converted by drive assembly 330 into translational motion for housing 301. The motors may provide unidirectional, or bidirectional, rotation to the drive assembly. Preferably, however, the motor to provide translational motion for the housing is bidirectional, while the motor to provide rotation for the hub may be unidirectional or bidirectional. Regardless, from using two motors to control the sootblower through the drive assembly, the housing of the sootblower may travel back-and-forth along the tracks to extend and retract the lance within the boiler, and the hub and lance attached thereto may independently rotate within the boiler because separate motors are controlling the rotation and the translational motion.

For example, as described above, a sootblower in accordance with embodiments disclosed herein may incorporate two motors. One of the motors may be used to control and provide bidirectional translational motion for the sootblower, and the other of the motors may be used to control and provide rotation for the hub and the lance attached thereto. As such, because of the use of two motors, the motors may act independently of one another. This independence of the motors may enable the nozzle to follow a limitless number of paths while traveling in-and-out of the boiler. This use of the two motors is discussed further below.

Referring still to FIG. 4, motor 318A (shown in FIG. 3) provides rotation to a gear train 360, and motor 318B (shown in FIG. 3) provides bidirectional rotation to drive shaft 340. Specifically, motor 318A may provide rotation (e.g., unidirectional or bidirectional) to a worm 326A, and motor 318B may provide bidirectional rotation to a worm 326B. Worms 326A, 326B, disposed within housing 301, are configured to rotate corresponding to the rotation of motors 318A, 318B, respectively. For example, as motor 318A rotates clockwise and then counter-clockwise, worm 326A may correspondingly rotate clockwise and then counter-clockwise.

Worms 326A, 326B are then configured to engage worm gears 342A, 342B, respectively. As shown, worm gear 342A is disposed about drive shaft 340 to be able to rotate independent of drive shaft 340, and worm gear 342B is attached to drive shaft 340. Thus, worm gear 342B is configured to bidirectionally rotate drive shaft 340 from engagement with worm 326B, while worm gear 342A is configured to rotate about drive shaft 340 from engagement with worm 326A. Further, the arrangement of worms 326A, 326B and worm gears 342A, 342B 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 318B using, for example, worm 326B and worm gear 342B, may be used to provide translational motion for housing 301. 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 318B, the translational direction of housing 301 may be controlled through drive shaft 340 within pinion gears 346 and the rack.

Further, powered by motor 318A to provide rotation for hub 310, worm gear 342A is disposed about and configured to rotate about drive shaft 340. Worm gear 342A is configured to transmit rotation from worm 326A and motor 318A to gear train 360. Thus, by switching rotational directions of motor 318A, the rotational direction provided to gear train 360 may be controlled through worm gear 342A.

Referring still to FIG. 4, gear train 360 may include spur gears 362, 364 and a bevel gear 366. Spur gear 362, attached to worm gear 342A, is disposed about and configured to rotate about drive shaft 340. Thus, as worm gear 342A rotates, spur gear 362 will correspondingly rotate. Spur gear 362 is then configured to provide rotation to spur gear 364. Specifically, spur gear 362 may engage spur gear 364 through, for example, the engagement of teeth (not shown), to translate the rotation from one gear to the other.

Further, as shown, spur gear 364 may be attached to bevel gear 366. As such, when spur gear 362 rotates, this rotation is translated through spur gear 364 to rotate bevel gear 366. Bevel gear 366 is then configured to provide rotation to hub 310. Specifically, bevel gear 366 may engage a bevel gear 311 attached to and/or formed upon hub 310 through, for example, the engagement of teeth (not shown). Thus, using the interaction of spur gears 362, 364 and bevel gear 366 of gear train 360, motor 318A may provide rotation to hub 310.

With the inclusion of two motors, one to provide unidirectional or bidirectional rotation to the hub and the other to provide bidirectional rotation to the drive shaft corresponding to translational motion, the nozzle may follow any desired path when extending into and retracting from the boiler. For example, in one embodiment, while providing a constant translational speed to the sootblower, the hub may be provided an accelerating and decelerating rotational speed. As such, the nozzle path may be dense in areas of high rotational speed and sparse in areas of low rotational speed.

Further, in another embodiment, the hub may bidirectionally rotate such that every 180 degrees, the hub will switch directions and rotate in the opposing direction. As such, the nozzle path may only cover about 180 degrees when extended and retracted from the boiler. Furthermore, in yet another embodiment, rather than continuously rotating the hub, the hub may discontinue rotating as the sootblower changes directions from extending into the boiler to retracting from the boiler. As such, the nozzle path may incorporate a phase-shift, such as shown in FIG. 2B. Regardless, those having ordinary skill in the art will appreciate that the nozzle path is not so limited, and any desired nozzle path may be used by incorporating the two motors.

Next, those having ordinary skill in the art will appreciate that the present disclosure is not limited to the specific arrangement of gears for the gear trains of the sootblower. For example, the gear trains may incorporate more gears or fewer gears into the gear train without departing from the scope of the present invention.

Further, the hub may be positioned substantially on the vertical centerline of the housing of the sootblower, and the motors may be positioned substantially opposite one another with respect to the centerline. For example, as shown in FIG. 4, hub 310 may be positioned substantially on vertical centerline 331 of housing 301. In such embodiments, the majority of the weight from the hub, with the lance and feed tube attached thereto, and the motors may 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, and the gear train 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 boilers. For example, as shown, the sootblower described herein may include only one gear train for rotating the hub and lance, rather than including several chains and sprockets. 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.

Claims

1. A sootblower used to project a blowing medium, the sootblower comprising:

a hub comprising a first end to receive a lance and a second end to receive the blowing medium;

a first motor;

a second motor;

a gear train configured to convert rotation of the first motor into rotation of the lance; and

a drive shaft configured to convert bidirectional rotation of the second motor into translational motion of the lance.

2. The sootblower of claim 1:

wherein the gear train comprises a first spur gear, a second spur gear, and a bevel gear;

wherein the first motor is configured to provide rotation to a first spur gear;

wherein the first spur gear is configured to provide rotation to the second spur gear;

wherein the second spur gear is configured to provide rotation to a bevel gear; and

wherein the bevel gear is configured to provide rotation to the lance.

3. The sootblower of claim 2, wherein the second spur gear is attached to the bevel gear to provide rotation from the second spur gear to the bevel gear.

4. The sootblower of claim 1, further comprising:

a first worm gear disposed about the drive shaft and a second worm gear attached to the drive shaft;

wherein the first motor is configured to provide rotation to a first worm engaging the first worm gear, thereby providing rotation to the gear train; and

wherein the second motor is configured to provide bidirectional rotation to a second worm engaging the second worm gear, thereby providing bidirectional rotation to the drive shaft.

5. The sootblower of claim 1, wherein the hub connects the lance to a feed line supplying the blowing medium to the sootblower.

6. The sootblower of claim 1, further comprising a housing to contain the hub, the gear train, and the drive shaft.

7. The sootblower of claim 6, further comprising a lubricant disposed within the housing.

8. The sootblower of claim 7, wherein the lubricant comprises synthetic oil.

9. The sootblower of claim 1, wherein the lance is positioned substantially on a vertical centerline of the housing.

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

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

12. The sootblower of claim 1, wherein the lance comprises a venturi nozzle to emit the blowing medium.

13. A sootblower to project a blowing medium into a boiler, the sootblower comprising:

a first motor and a second motor;

a drive assembly configured to convert rotation from the first motor into rotation of a lance; and

a drive shaft configured to convert bidirectional rotation from the second motor into bidirectional translational motion of the lance;

wherein the drive assembly comprises a gear train having a first spur gear, a second spur gear, and a bevel gear;

wherein the first motor is configured to provide rotation to the first spur gear;

wherein the first spur gear is configured to provide rotation to the second spur gear;

wherein the second spur gear is configured to provide rotation to the bevel gear; and

wherein the bevel gear is configured to provide rotation to the lance.

14. The sootblower of claim 13, wherein the second spur gear is attached to the bevel gear to provide rotation from the second spur gear to the bevel gear.

15. The sootblower of claim 13, further comprising:

a first worm gear disposed about the drive shaft and a second worm gear attached to the drive shaft;

wherein the first motor is configured to provide rotation to a first worm engaging the first worm gear, thereby providing rotation to the gear train; and

wherein the second motor is configured to provide bidirectional rotation to a second worm engaging the second worm gear, thereby providing bidirectional rotation to the drive shaft.

16. The sootblower of claim 13, wherein a first end of the lance is configured to be received by a hub and a second end of the lance is configured to project the blowing medium.

17. The sootblower of claim 13, wherein the drive assembly and the drive shaft are disposed within a housing.

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

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

20. A method for cleaning a boiler using a sootblower in accordance with claim 13.