Patent Grant
7367079
The present invention relates to sootblowers used to clean industrial boilers and, more particularly, relates to an integral packing and packing housing unit that makes it faster, easier and safer to replace the sacrificial packing used to seal the steam joint in industrial sootblowers.
Industrial boilers, such as oil-fired, coal-fired and trash-fired boilers in power plants used for electricity generation and waste incineration, as well as boilers used in paper manufacturing, oil refining, steel and aluminum smelting and other industrial enterprises, are huge structures that generate tons of ash while operating at very high combustion temperatures. These boilers are generally characterized by an enormous open furnace in a lower section of the boiler housed within walls constructed from heat exchanger tubes that carry pressurized water, which is heated by the furnace. An ash collection and disposal section is typically located below the furnace, which collects the ash and carts it away for disposal, typically using a hopper and a conveyor or rail car.
There is a high demand for thermal energy produced by these large industrial boilers, and they exhibit a high cost associated with shutting down and subsequently bringing the boilers back up to operating temperatures. For these reasons, the boilers preferably run continuously for long periods of time, such as months, between shut down periods. This means that large amounts of ash, which is continuously generated by the boiler, must be removed while the boiler remains in operation. Further, fly ash tends to adhere and solidify into slag that accumulates on high-temperature interior boiler structures, including the furnace walls, the superheater platens, and the other heat exchangers of the boiler. If the slag is not effectively removed while the boiler remains in operation, it can accumulate to such an extent that it significantly reduces the heat transfer capability of the boiler, which reduces the thermal output and economic value of the boiler. In addition, large unchecked accumulations of slag can cause huge chunks of slag to break loose, particularly from the platens, which fall through the boiler and can cause catastrophic damage and failure of the boiler. The slag accumulation problem in many conventional boilers has been exacerbated in recent years by increasingly stringent air quality standards, which have mandated a change to coal with a lower sulphur content. This low-sulphur coal has a higher ash content and produces more tenacious slag deposits that accumulate more quickly and are more difficult to remove, particularly from the superheater platens.
To combat this problem, the industry has developed increasingly sophisticated boiler cleaning equipment. In particular, steam and multi-media (e.g., water and steam) sootblowers have been developed for periodically cleaning the heat exchangers while the boiler remains in operation. These sootblowers generally include lance tubes that are inserted into the boiler adjacent to the heat exchangers and operate like large pressure washers to clean the heat exchangers with a cleaning fluid, such as water, steam, or both water and steam, while the boiler remains in operation. These sootblowers are generally characterized by rotating and linearly traveling lance tubes that blast the cleaning fluid in a corkscrew pattern to clean as wide an area as possible as the lance advances. To allow the lance tube to move freely while transporting the steam, the lance tube is typically received telescopically over an open steam tube. This allows the steam tube to deliver steam into an interior cavity of the lance tube as the lance rotates and moves telescopically on the steam tube.
The configuration described above creates moving steam joint between the steam tube and the lance that must remain sealed as the lance rotates and moves telescopically along the steam tube. This steam joint is typically sealed by a set of sacrificial gaskets known as a “packing,” which consisting of a series of rings constructed from a deformable, heat-resistant material, such as an oil impregnated graphite material known in the trade as GRAPHOIL™. TEFLON™ based materials have also been successfully used for sootblower packing.
The packing rings have an inner diameter approximately the size of the steam tube and an outer diameter approximately the size of the inner dimension of a spindle surrounding the packing. The spindle, in turn, supports the lance as the lance rotates and moves linearly along the steam tube. To form a seal, the packing is loaded by a compression plate that is typically biased by spring washers (also called “Belleville washers”). Compression presses the packing material against the spindle and steam tube and thereby causes the packing to deform sufficiently to form a steam-tight seal. The spring washers expand over time to maintain the load on the packing as friction wears away sacrificial packing material. Eventually, the packing becomes spent and must be replaced.
The packing is replaced by sliding the steam tube out the spindle and then picking, prying and scraping the spent packing material out of the spindle. This packing, which has been mashed an repeatedly heated and cooled over time, can be difficult to coax out of the spindle. For this reason, technicians have been known to resort to non-recommended packing removal methods, such as opening the steam valve adjacent to the packing in an attempt to blow the packing out of the spindle. It should be appreciated that the sootblowers are typically used continually every day (e.g., hourly) while the boiler is in operation. For this reason, an extended packing replacement process, as occurs when technicians grapple with picking and scraping jammed packing out of the spindle, can interfere with the boiler cleaning regimen.
Accordingly, a continuing need exists for improved packing and packing replacement procedures for sootblowers used to periodically clean industrial boilers. More specifically, a need exists for a sootblower packing that lasts longer and can be removed and replaced faster, easier and more safely than a conventional sootblower packing.
The present invention meets the needs described above in an integral packing unit including a housing and packing material that makes it faster, easier and safer to replace the sacrificial packing used to seal the steam joint between the steam tube and lance in industrial sootblowers. The integral packing unit allows the packing material, which is typically designed to be sacrificial, to be replaced by removing the entire packing unit intact from the spindle. The packing unit can then be disassembled on a workbench or other suitable work area, where the spent packing material is removed and a new packing is installed. The packing unit is then reassembled and installed intact on the sootblower. For example, the packing unit may include a cylindrical packing housing configured to receive a number sacrificial packing rings, which are replaced from time to time as the packing rings wear away.
The packing unit works with a compression unit that may be integral with or separable from the housing. The compression unit typically includes a system of coil springs to load the packing rings evenly and over a greater linear travel distance of the compression plate than is possible with spring washers. To facilitate removal of the packing unit for packing ring replacement, the compression unit typically includes a detent mechanism, such as a pair of set screws that can be screwed into the compression unit into an active position to relieve the load on the packing. Once the set screws have been installed to relieve the load on the packing material, the compression unit may be removed from the sootblower. The packing housing holding the spent packing material can then be easily removed for packing replacement. The packing unit is then reassembled and installed intact on the sootblower, the compression unit is reinstalled, and the detent mechanism is deactivated to load the packing. If the packing housing is integral with or connected to the compression unit, the packing material, packing housing and compression unit may be removed and reinstalled as an integral unit. The packing unit also typically includes a packing wear monitor, such as a viewing port revealing the linear travel position of the compression unit, which allows a technician to easily determine when the packing rings require replacement.
Generally described, the invention may be implemented as an integral and removable packing unit that includes a housing for removably holding a sacrificial packing material. This packing material is configured to form a steam seal between a sootblower steam tube and lance spindle when the packing unit is installed in an operative position and the packing material is loaded through compression. A compression unit is typically coupled to the housing unit to apply such compression to load the packing material while the packing unit is installed in the operative position. The compression unit may also include a detent mechanism, such as one or more set screws, for unloading the packing material to facilitate installing the packing unit intact on, and removing the packing unit intact from, the operative position.
More specifically, the packing material typically includes a series of equally-sized, concentric, sacrificial packing rings having an inner dimension approximately equal to an outer dimension of the steam tube and an outer dimension approximately equal to an inner dimension of the packing unit housing. In addition, the packing unit ordinarily defines a cylindrical opening for receiving the steam tube, and the compression unit typically includes one or more coil springs located between first and second compression plates. This allows the packing material to be captured on the steam tube and compressed by the compression unit when the packing unit is in the operative position and the detent mechanism is inactive.
In a particular configuration, the compression unit includes eight compression springs located around the cylindrical opening surrounding the steam tube. In this embodiment, the set screws threadably engage at least one of the compression plates to compress the coil springs and thereby unload the packing material. The packing unit may also include a packing wear monitor, such as a viewing port revealing the linear travel position of the second compression plate.
The invention also includes a sootblower including a lance tube telescopically received on a steam tube and an integral packing housing, a packing material and packing compression unit, as described above. The packing material may be sacrificial, and the packing unit may include a packing wear monitor to gauge the extent of depletion of the sacrificial packing material. This configuration represents an improvement in sootblower design including an integral packing unit that can be removed and reinstalled intact for the purpose of replacing the packing material. The invention also includes an industrial boiler having a cleaning system including a plurality of the sootblowers with integral packing units, and a power plant having an output rating maintained by a boiler cleaning system including a number of sootblowers with integral packing units.
The invention also includes a method for replacing the packing material in an integral packing housing, packing material and packing compression unit for an industrial sootblower. A detent mechanism is activated to unload the packing material while the packing unit is installed in an operative position on the sootblower. The packing unit is then removed intact from the sootblower. The spent packing material is then removed and new packing material is installed in the packing unit, typically at a workbench or other suitable work location. The packing unit with the new packing material is then reinstalled intact in the operative position on the sootblower, and the detent mechanism is deactivated to load the packing material. This packing replacement method also supports a method for maintaining a desired output rating for an industrial boiler by continually cleaning the boiler with sootblowers while the boiler is in operation, and by periodically maintaining the sootblowers with packing replacement using the packing replacement method described above.
In view of the foregoing, it will be appreciated that the present invention avoids the drawbacks of prior packing systems for industrial sootblowers by providing an integral packing unit that makes it safer, faster and easier to replace the spent packing material. The invention also provides an improved method for packing replacement, boiler cleaning, and maintenance of a desired boiler output rating. The specific techniques and structures for implementing the invention, and thereby accomplishing the advantages described above, will become apparent from the following detailed description of the illustrative embodiments of the invention and the appended drawings and claims.
The present invention relates to industrial sootblowers and associated boiler cleaning equipment. In general, the integral packing and packing housing unit described below may be employed with any type of sootblower, but is particularly well adapted to sootblowers that use steam as a cleaning fluid. The illustrative sootblower described below selectively applies two cleaning fluids, typically water and steam, which may be applied individually or in combination during a cleaning operation. However, the principles realized by the exemplary embodiments of the invention as described in this specification may be directly modified and extrapolated to develop sootblowers capable of applying more than two independently controlled cleaning fluids, having more then two independently controlled systems for applying any particular cleaning fluid, and for applying different types of cleaning fluids, such as air, solvents, sand blast streams, bead blast streams, liquid nitrogen or other very cold fluids, superheated plasma or other very hot fluids, or any other cleaning fluid that may be appropriate for a particular application. It should also be appreciated that the sootblower may be used for purposes other than cleaning, such as applying paint, sealant, or other desired coatings to interior boiler components.
The exemplary sootblower described below also includes two independently controlled water application systems that each include two nozzles. Of course, the number of independently controlled water systems, and the number of nozzles included in each water application system, are design choices that may be altered to meet the objectives of a particular application. Similarly, the exemplary sootblower includes a single steam application system with two nozzles, but additional steam systems and different numbers of steam nozzles may be included, as desired, for particular applications.
The particular multi-media rotating sootblower and associated automatic boiler cleaning system described below are well adapted for use in large-scale coal-fired, oil-fired and trash-fired boilers that are typically used to generate electric power and heat or process steam for industrial enterprises, such as electricity generation, paper manufacturing and municipal incineration. Nevertheless, it should be understood that these or modified sootblowers may also be used in other types of industrial boilers, such as wood, straw, peat and manure-fired boilers, as well as heat recovery boilers commonly used in steel and aluminum smelters, chemical manufacturing, oil refineries, and other industrial processes. Basically, all industrial boilers can benefit from effective cleaning, and a variation of the multi-media rotating sootblower described below may be readily adapted to any particular industrial boiler configuration and cleaning requirement.
It should also be understood that many design modifications and additions may be readily deployed with specific embodiment described below, such as independently articulating and controlled nozzles, articulating lances (which are described as rotating and linearly traveling, but not otherwise articulating), pulsating cleaning fluid streams, varying pressure cleaning fluid streams, alternating cleaning media fluid streams, and so forth. However, each of these modifications would add cost and complexity to the system. Therefore, it should also be appreciated that the preferred embodiments described below are presently considered by the inventors to embody the most technically and economically feasible sootblowers and automatic cleaning systems for today's industrial boilers, and in particular the boilers found in oil-fired, coal-fired and trash-fired boilers in power plants used for electricity generation and waste incineration, as well as boilers used in paper manufacturing, oil refining, steel and aluminum smelting.
The illustrative embodiment of the integral packing unit described below is configured to work with a compression unit including eight coil springs located between and around the perimeter of a pair of compression plates. However, other spring arrangements could be employed, such as a single coil spring that receives the steam tube through its center, or a different number of or configuration of coil springs or other types of springs, such as spring washers, leaf springs, expandable blocks (e.g., rubber), ball screws, electrically activated expanding materials, and the like. In addition, loading mechanisms other than springs may be employed, such as air cylinders, air bags, hydraulic cylinders, ratchet assemblies, and the like.
Further, the packing material need not be sacrificial and need not be configured in the form of equally-sized, concentric rings. For example, the packing material may be a solid cylinder or another shape suitable for a particular application, and may use a technique other than a deformable sacrificial gasket to for a seal, such as an air flow, fluid flow, magnetic barrier, or other type extruded of induced barrier. Similarly, detent mechanisms other than set screws may be employed, such as levers, ratchets, cams, air cylinders, hydraulic cylinders, air bags, ball screws, and the like. In addition, the packing unit may be deployed without a detent mechanism, in which case the unit would have to be disassembled and reassembled in-place on the sootblower to replace the packing.
In addition, the packing unit is typically coupled to the compression unit, either removably or as an integral unit. For example, the compression unit and the packing housing may be formed of a continuous material or welded together, or they may be held together by bolts, pins, retention clips, or any other suitable connection device. In any case, the compression unit is typically attached directly to packing housing in some manner to facilitate easy installation and removal of the assembly. However, it should be appreciated that the compression unit need not be attached directly to the packing unit housing, and could be supported by another structure, such as the steam tube, lance, spindle, frame or other suitable supporting structure.
It should also be appreciated that the preferred configuration described below is presently considered by the inventors to be the best and most cost effective way to implement an integral packing unit for conventional industrial sootblowers, and that any significant variation from the preferred configuration would likely add cost and complexity the system. However, it is also evident that those skilled in the art will recognize that many variations to the preferred configuration, such as those described above as well as many routine design choice, may be employed to accomplish the principles and achieve the advantages illustrated by specific embodiment described below. In addition, a similar packing unit may also find use in devices other than industrial sootblowers, such as paint sprayers, solvent sprayers, sand blasters, and so forth.
Turning now to the figures, in which similar reference numerals indicate similar elements in the several figures,
In general, the sootblower 10 includes a steam tube 14 and a lance tube 16 that rotates and moves telescopically on the steam tube to enter and clean internal components of an industrial boiler. The steam tube 14 delivers steam into an internal chamber within the lance tube 16, which is in fluid communications with one or more steam jets located in an nozzle at the end of the lance tube. The steam jets, in turn, blast the steam to act as a large industrial pressure washer to clean the internal components of the boiler. This is illustrated by
The purpose of the integral packing unit 12 is to form a steam-tight seal between the steam tube 14 and the lance 16 as the lance rotates and moves telescopically on the steam tube. It is therefore located between the steam tube 14 and a spindle 21 (see
As shown in
Thus, the packing rings 60 are positioned so that they are captured on the steam tube when the steam tube is received through the cylindrical opening 46. The packing rings 60 are also positioned for compression between the plunger 58 and the bushing 62 when the detent mechanism, in this case the set screws 30 (only one set screw is shown in
In this position, the detent mechanism formed by the set screws 30 is said to be “active” in that the detent mechanism is opposing the compression force of the springs 50. The set screws 30 can also be screwed out of the second compression plate 56 sufficiently to allow the compression unit to load the packing rings 60. In this position, the detent mechanism is said to be “inactive.” In practice, the set screws 30 are typically removed completely from the packing unit 12 once the unit has been installed in its operative position on the sootblower 10.
All of the following parameters are for a typical packing unit 12 as shown and described with reference to
In view of the foregoing, it will be appreciated that present invention provides significant improvements in packing systems for sootblowers and that numerous changes may be made therein without departing from the spirit and scope of the invention as defined by the following claims.
This application claims priority to commonly-owned U.S. Provisional Patent Application Ser. No. 60/394,495, entitled “Soot Blower Packing,” filed on Jul. 9, 2002.
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| Number | Date | Country | |
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| 20040019999 A1 | Feb 2004 | US |
| Number | Date | Country | |
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| 60394495 | Jul 2002 | US |
