1. Field of the Invention
The invention relates generally to a sootblower for removing debris from an interior of a boiler. More specifically, the invention relates to a sootblower that emits a pressure wave into an interior volume of the boiler to remove debris from surfaces located therewithin.
2. Related Technology
During the operation of large-scale combustion devices, such as boilers that burn fossil fuels, slag and ash encrustations develop on interior surfaces of the boiler. For example, boiler tubes that are grouped together as a tube bank and that each extend generally vertically within the boiler interior volume are particularly susceptible to the above-described deposits. The presence of these deposits degrades the thermal efficiency of the boiler. Therefore, it is periodically necessary to remove such encrustations. Various systems are currently used to remove these encrustations.
One such type of system includes a device referred to as a sootblower. Conventional sootblowers project a stream of cleaning fluid, such as air, steam or water, into the interior volume of the boiler. In the case of retracting type sootblowers, a lance tube is periodically advanced into and withdrawn from the boiler and conducts the cleaning fluid to spray from one or more nozzles fastened to the lance tube. As the lance tube is advanced into and withdrawn from the boiler, it may rotate or oscillate in order to direct one or more jets of cleaning fluid at desired surfaces within the boiler. In the case of stationary sootblowers, the lance tube is always maintained within the boiler.
Conventional sootblowers deliver the cleaning fluid, typically steam, into the boiler at a relatively high pressure to facilitate the removal of the encrustations. The high pressure steam typically must be heated and/or pressurized before entering the sootblower, thereby consuming energy and lowering the overall efficiency of the boiler system. In addition, conventional sootblowers depend on direct impact of the fluid stream with the boiler tubes to remove the deposits. As a result, the boiler tubes are often only cleaned on the leading side (the side directly impacted by the fluid stream). Furthermore, the jet penetration may be impeded by an obstruction, such as another boiler tube.
Systems that harness the power of chemically-driven combustion events, such as detonation and deflagration, are beneficial for boiler cleaning because they may have an improved efficiency. More specifically, the combustion events generate pressure waves, which are directed into the boiler interior volume to vibrate the interior components of the boiler and loosen debris therefrom. Additionally, the pressure waves may be more effective tubes than conventional sootblowers at removing deposits from the boiler tubes because the pressure waves are able to reverberate within the deposits. The reverberation is able to travel into the deposit and to wrap around the boiler tubes to effectively loosen the deposits from both the leading side and the trailing side of the boiler tubes.
A shock tube is a tube having an open end and a closed end that is used to generate the detonation or deflagration event. An explosive gas mixture is ignited at the closed end of the shock tube and a deflagration combustion wave is formed and accelerated to the point where transition from deflagration to detonation occurs. The detonation event produces a sharp shock wave having a peak pressure that may be several times greater than a reference pressure, depending primarily on the fuel and oxidizer that are utilized in the shock tube.
Detonation combustion differs from deflagration combustion in that during a detonation event a fuel/oxidizer mixture is detonated rather than burned. Detonation combustion leads to a much greater release of energy than deflagration, thereby creating greater pressures, higher temperatures, and much greater pressure wave velocities. Thus, while the pressure wave velocity due to a deflagration process is typically less than 0.03 times the speed of sound and typically develops a relatively low pressure, the pressure wave or shock wave velocity associated with detonation combustion typically approaches 5 to 10 times the speed of sound and offers pressure differentials of approximately 13 to 55 times greater than the reference pressure.
Stationary detonation or deflagration cleaners include a long, stationary tube positioned outside the boiler walls. The stationary tube is positioned in the opening such that a tube outlet that emits a pressure wave towards the boiler tubes does not extend into the interior volume. Alternatively, the tube slightly extends through the opening such that only a relatively small length of the tube extends into the boiler interior volume. In both of these cases, however, the tube outlet is positioned a relatively large distance from the boiler tubes, thereby reducing the cleaning effectiveness of the pressure wave. More specifically, the pressure wave typically decays in an exponential fashion after exiting the stationary tube. For example, the pressure wave may be able to effectively clean the first row of boiler tubes but not the rows located further away from the stationary tube outlet. Therefore, given the distance between the outlet of pressure wave generator and the boiler tubes, and given the obstruction represented by the banks of boiler tubes, cleaning by a stationary detonation tube may be limited. Furthermore, even if the sootblower is able to produce extremely high pressure waves that maintain enough strength to clean the back rows of boiler tubes, the front rows of boiler tubes may be damaged by the pressure waves, especially those associated with detonation combustion. The stationary detonation/deflagration lance tubes may have an especially limited cleaning effect on tenacious ash deposits.
In another cleaning system currently known in the art, disclosed in U.S. Pat. No. 5,494,004 entitled “ON LINE PULSED DETONATION/DEFLAGRATION SOOT BLOWER”, a cleaning apparatus is able to be moved through an inlet opening formed in a boiler wall. The cleaning apparatus includes a pair of elongated housing members that are pivotable with respect to each other to move between a folded position and a partially extended position. More specifically, when the housing members are in the folded position, the cleaning apparatus is able to be extended through the boiler wall inlet. Once inside the boiler, the pivoting housing member is pivoted to an angle Ø (
During operation of currently known, combustion-event cleaners, the pressure wave may fail to occur or may be undesirably weak due to various factors. For instance, if the mixture of the fuel and the oxidizer is not proper, then detonation or deflagration may not occur. If the pressure wave is not effective, the boiler tubes may experience undesirable deposit build-ups, which could reduce boiler efficiency or cause boiler shutdown. Although some currently-known combustion-event cleaners include a detonation/deflagration detection system, this system operates by measuring pressure waves generated by the cleaner, which may be difficult. More specifically, the pressure waves generated by the cleaner are in the range of microseconds and a direct data sampling is therefore not feasible.
It is therefore desirous to provide a combustion-event sootblower that is able to effectively loosen deposits from surfaces within a boiler and that is able to effectively detect unsuccessful detonation or deflagration.
In overcoming the limitations and drawbacks of the prior art, the present invention provides a sootblower for cleaning a plurality of surfaces within an interior volume of a combustion device. The sootblower includes a combustion assembly configured to generate a pressure wave, a delivery assembly having an outlet for delivering the pressure wave into the interior volume of the combustion device, and a translating assembly to selectively position the outlet portion of the delivery assembly within the interior volume of the combustion device. The delivery assembly defines a pressure wave path extending in a substantially linear direction between the combustion assembly and the outlet portion of the delivery assembly to substantially prevent degradation of the pressure wave within the delivery assembly.
In one preferred design, the outlet portion includes a generally non-linear portion to guide the pressure wave towards the surfaces of the combustion device. For example, the non-linear portion is generally arcuate-shaped and defines a generally gradually-angled path to minimize degradation of the pressure wave within the outlet portion.
In another preferred design, the outlet portion includes a pair of diametrically opposed nozzles. Additionally, the outlet portion is preferably configured to rotate with respect to the surfaces of the combustion device to control a projection of the pressure wave.
The combustion assembly preferably generates the pressure wave via a deflagration event or via a detonation event.
For a detonation sootblower, the delivery assembly preferably includes at least one obstruction positioned along the pressure wave path to increase the velocity of the deflagration flame. The increased velocity of the deflagration flame causes a velocity gradient of layers of unburned gases, which increases the mass burning rate of the gases and initiates detonation. In one design, the obstruction is a generally spiral-shaped ridge extending from a wall of the delivery assembly. The obstruction is preferably integrally formed with a wall of the delivery assembly.
In another preferred design, the combustion assembly includes an ignition chamber configured to receive fuel and an oxidizer, an obstruction to increase turbulence within the ignition chamber and to promote mixing of the fuel and the oxidizer, and an ignition element configured to ignite the fuel. Additionally, the ignition chamber diameter is preferably 1 to 3 times greater than the delivery assembly diameter. Furthermore, the ignition chamber axial length is 1 to 4 times greater than the ignition chamber diameter.
In another aspect of the present invention, the sootblower includes a combustion detection assembly having a temperature sensor coupled to the combustion assembly or the delivery assembly to measure a sootblower temperature for detecting an unsuccessful detonation/deflagration event. The sootblower in this design preferably includes a controller that is electrically connected with the temperature sensor to control the combustion assembly. For example, the controller is preferably configured to control the combustion assembly based on a gradient of the sootblower temperature. More specifically, the controller is configured to deactivate the combustion assembly if the gradient of the sootblower temperature is less than a threshold, and in some events if the absolute temperature exceeds a maximum temperature threshold.
In another aspect of the present invention, the sootblower includes a delivery assembly defining a pressure wave path extending between the combustion assembly and an outlet portion of the delivery assembly and the pressure wave path has an adjustable length. The delivery assembly preferably includes a lance tube and a feed tube slidably received within the lance tube to define an overlapping portion having an adjustable overlapping length. Additionally, the lance tube is preferably movable between a first position second section, wherein a portion of the lance tube positioned within the interior volume in the second position.
In another aspect of the present invention, a method of cleaning the surfaces within the combustion device is provided. The method includes the steps of: generating a pressure wave within the combustion assembly, translating the delivery assembly along a path extending into the interior volume of the combustion device, and delivering the pressure wave to the interior volume of the combustion device to remove deposits from the surfaces of the combustion device while translating the delivery assembly along the path.
The method also preferably includes the step of measuring an oxygen content within the combustion assembly after, and/or before, a combustion event. Additionally, the method preferably includes the step of controlling the combustion assembly based on an electrical signal.
Further objects, features and advantages of this invention will become readily apparent to persons skilled in the art after a review of the following description, with reference to the drawings and claims that are appended to and form a part of this specification.
a is a cross-sectional of the lance tube taken along line 2-2 in
b is a cross-sectional of the lance tube similar to that shown in
a is a side view of an ignition assembly shown in
b is a cross-sectional view of the ignition assembly taken along line 6b-6b in
a is a partial cross-sectional view of a lance tube in an alternative design embodying the principles of the present invention;
b is a cross-section taken along line 7b-7b in
a and 11b are first and second alternative configurations of the nozzle shown in
a and 12b are third and fourth alternative configurations of the nozzle shown in
a and 13b is a lance tube in an alternative design embodying the principles of the present invention.
Referring now to the drawings,
During operation of the sootblower 10 shown in the figures, when the lance tube 14 is advanced into the interior of the boiler a cleaning medium is discharged from one or more nozzles 21 located adjacent to the distal end of the lance tube 14. In one design, the nozzles 21 direct the pressure waves 25 at an angle with respect to the lance tube 14 longitudinal axis, such as the 90 degree angle shown in
The frame assembly 12 shown in
However, in an alternative design shown in
The feed tube 15 and the lance tube 14 filled with a mixture of fuel and oxidant 33 to a fuel/oxidant fill length 35 to adjust an intensity of the pressure waves 25. For example, the greater the fuel/oxidant fill length 35, the greater the intensity of the pressure waves 25.
Referring to
The collective capacity of the air injectors 34 should be larger than that of the fuel injector 32 because the stoichiometric combustion process requires more air mass than fuel mass. For example, the air-fuel mass ratio of air-propane mixture burning at stoichiometric condition is 15.7:1, so the air injectors 34 should be able to combine to have a mass flow rate that is 15.7 times greater than the mass flow rate of through the fuel injector 32 during the same injection period. This is critical for ensuring stoichiometric burning process because the detonation process can be hindered if the mixture is burning rich or lean. As is known in the art, the stoichiometric condition varies based on the type of fuel used in the sootblower 10.
Referring to
The fuel supply system 60 generally includes: a fuel inlet 64 for receiving fuel from a fuel supply such as a propane tank or a natural gas supply line (not shown), a fuel accumulator 66, a fuel orifice plate 68, a fuel isolation valve 70, the fuel supply hose 28, and the fuel injector 32. Located internally within the fuel inlet 64 are a check valve (not shown) to prevent backflow towards the fuel supply and a regulating valve (not shown) to regulate the fuel through the fuel inlet 64. Therefore, fuel is permitted to flow through the fuel inlet 64 and into the fuel accumulator 66 or towards the fuel orifice plate 68, depending on whether the fuel accumulator 66 is full. The fuel accumulator 66 compensates for any time delay in the fuel delivery into the sootblower 10. For example, the fuel should be injected into the mixing tube 26 at a particular velocity to create an effective fill within the combustion assembly 8. Therefore, an effective supply of fuel should be readily available when needed, and the fuel accumulator 66 provides such an effective supply. The fuel orifice plate 68 is sized such that a choked condition exists to further control the amount of fuel delivered to the fuel isolation valve 70 and ultimately to the fuel supply hose 28. Finally, the fuel injector 32 regulates the delivery of the fuel into the mixing tube 26, as is discussed above.
The air supply system 62 generally includes: an air filter and regulator 72, an air accumulator 74, the air supply hose 30, and the air injector. The air is able to flow from an air supply, such as a pressurized tank or ambient air, into the air filter and regulator 72 where it is filtered. Next, the air is permitted to flow into the air accumulator 74 or towards the air supply hose 30, depending on whether the air accumulator 74 is full. Similarly to the fuel accumulator 66, the air accumulator 74 compensates for any time delay in the air delivery into the sootblower 10. The air injector 34 is also used as a flow regulating mechanisms to regulate the flow into the device. Inlet pressure versus mass flow rate calibration curves are developed for the air injectors 34 so that an operator is able to control the air inlet pressure to obtain the desired fill flow rates for stoichiometric combustion.
In addition to a proper fuel-air ratio, proper mixing of air and fuel streams 50, 52 prior to ignition is also crucial in ensuring stoichiometric burning. As shown in
As is known in the art of detonation, two general modes of detonation combustion initiation exist: a slow mode initiation where a flame is formed via ignition and the flame is then accelerated to cause detonation, and a fast mode initiation where detonation is formed instantaneously when a sufficient amount of energy is produced at once. A self-ignition mode typically uses air as the oxidizer and transitions from deflagration to detonation to form the pressure wave 25. Conversely, direct ignition mode typically uses oxygen as the oxidizer instead of air and transitions directly to detonation. Furthermore, self ignition mode systems require a distance between the point of ignition and the point of transition from deflagration to detonation, a distance that is commonly known as run-up distance. In the present invention, a self-initiation is preferably used by initiating a flame in the ignition chamber 16 and accelerating the flame along the feed tube 15 and along a portion of the lance tube 14 until detonation occurs. However, any other suitable process, such as direct detonation, may alternative be used with the present invention.
In furtherance of the self-initiation detonation process described above, the mixed fuel-air flow 58 flows into a combustion chamber 76 within the ignition assembly 16 and is ignited. The mixed fuel-air flow 58 flows through the mixing tube 36 at a relatively high velocity, such as 75 feet per second. If the mixed fuel-air flow 58 were to be ignited in the absence of chamber 76 at such a velocity, the boundary layers at the wall would be too thin for flame stabilization to occur. Therefore, it is beneficial to provide a mechanism for flame stabilization, such as the combustion chamber 76, which reduces the flow velocity of the mixed fuel-air flow 58 and recirculate part of the flow and continually ignites the fuel-air flow 58.
In a first exemplary design for flame stabilization, the flow area of the combustion chamber 76 is greater than the flow area of the mixing tube 36, thereby reducing flow velocities in the combustion chamber 76. For example, the combustion chamber diameter D is between 1 and 3 times larger than the mixing tube diameter d1 to create a sufficient velocity drop as the fuel-air flow 58 enters the combustion chamber 76. More preferably, the combustion chamber diameter D is 3 times larger than the mixing tube diameter d1. Similarly, the combustion chamber diameter D is between 1 and 3 times larger than the feed tube diameter d2 to create a sufficient velocity increase as the fuel-air flow 58 exits the combustion chamber 76. More preferably, the combustion chamber diameter D is 3 times larger than the feed tube diameter d2. Additionally, the length 77 of the combustion chamber 76 is preferably approximately 4 times greater than the combustion chamber diameter D.
In a second exemplary design for flame stabilization, first and second recirculation zones 78, 80 are generated near the inlet and the outlet of the combustion chamber 76. For example, the immediate change in diameter between the mixing tube 36 and the combustion chamber 76 generates the first recirculation zone 78 and causes the fuel-air flow 58 to circulate at the inlet of the combustion chamber 76. Similarly, the immediate change in diameter between the combustion chamber 76 and the lance tube 14 generates the second recirculation zone 80 and causes the fuel-air flow 58 to circulate at the outlet of the combustion chamber 76.
In a third exemplary design for flame stabilization, an obstruction 81 (best shown in
During testing, a device having the three above-described features has been shown to cause an additional 50% more flow to be successfully ignited compared with a design without the three features.
The fuel-air flow 58 is ignited within the combustion chamber 76 to generate the above-described flame by at least one spark plug 82 extending into the combustion chamber 76. The spark plug 82 is preferably a standard spark plug powered by a suitable power supply in order to deliver a sufficient amount of energy for starting the combustion process. One or several spark plugs may be used depending on the configuration of the combustion chamber 76 and the type of fuel used. The spark plugs 82 are preferably located at the corners of the combustion chamber 76 adjacent to the downstream end.
In furtherance of the self-initiation detonation process described above, once the flame has been formed and stabilized in the combustion chamber 76, flame acceleration is needed to transition to detonation. Although an ignited flame traveling within a tube may naturally accelerate to a point of detonation given a sufficient tube length, a tube with such a run-up distance may not be practical for use with a sootblower. Therefore, to decrease the required run-up distance, which is accomplished by achieving faster flame acceleration, an obstacle is located along the path of propagating flame to enhance volumetric burning rate thereby amplifying flame speed, which ultimately results in a generation of pressure waves 25 and eventually a transition to detonation.
The obstruction shown in
In an alternative design, shown in
Referring to
The sootblower shown in
To improve fuel efficiency of the sootblower 10, depending on the configuration of the sootblower 10 and the operating conditions, the lance tube 14 may have a particular length that is not filled with the mixed fuel-air flow 58. More particularly, if the distance that the lance tube travels into the boiler is indicated with “T” and a constant K is between 0.4 and 0.6, then the ideal unfilled lance tube length “Y” is preferably calculated with the following formula: Y=K*T. The fill length is controlled by the timing of the ignition process. More particularly, the longer the injectors 32, 34 are opened, the more the lance tube will fill with the mixed fuel-air flow 58.
Referring back to
The controller 40 orchestrates the various events of a deflagration/detonation combustion cycle, including the cycling of the fuel injector 32 and air injector 34, igniting the spark plugs 82, and providing alarms for un-expected events. The controller 40 preferably is electrically connected to the spark plugs 82, the fuel injector 32, the air injector 34, the water injector 87, and to one or more sensors, such as a pressure feedback sensor 94, a temperature feedback sensor 96, or a pair of oxygen feedback sensors 98, 100. The controller receives inputs from some or all of the above sensors 94, 96, 98, 100 and controls the spark plugs 82, the injectors 32, 34, and the water injector 87 in response thereto. Although the feedback sensors 94, 96 are shown as being connected to the lance tube 14 in the figures, this configuration may be difficult in a rotating sootblower application. For example, the rotation of the lance tube 14 may cause any wires connected to the feedback sensors 94, 96 to become entangled. Therefore, the feedback sensors 94, 96 are preferably connected to the surface of the feed tube or are preferably wireless feedback sensors.
The controller 40 can be utilized to initiate a proper combustion. For example, one of the oxygen feedback sensors 100 is located adjacent to the upstream side of the combustion chamber 76 to measure the oxygen level in the mixed fuel-air flow 58 before combustion, and the other one of the oxygen feedback sensors 98 is located adjacent to the downstream side of the combustion chamber 76 to measure the oxygen level in the mixture of fuel and air after combustion. Consequently, the controller 40 is able to more precisely control the combustion and ensure a proper combustion. More specifically, the upstream oxygen feedback sensor 100 is utilized to determine whether the air-fuel ratio is proper and the downstream oxygen feedback sensor 98 is utilized to determine whether the mixed fuel-air flow 58 was completely combusted. Then, the controller 40 adjusts the fuel injector 32 and/or the air injector 34 to achieve the proper air-fuel ratio. More specifically, if the oxygen feedback sensors 98, 100 indicate that the air-fuel ratio is lean (lower than 15.7:1), as shown at point 106, then the air injector 34 will be restricted to reduce the airflow therethrough. Conversely, if the oxygen feedback sensors 98, 100 indicate that the air-fuel ratio is rich (higher than 15.7:1) then the fuel injector 32 will be adjusted to decrease the fuel flow therethrough. Alternatively, one oxygen sensor located downstream of ignition chamber may be used instead of two.
The data from the respective oxygen feedback sensors 100 is aggregated by the controller. Then, as shown in
As another example of the controller 40 initiating a proper combustion, the controller 40 controls the timing of and the size of the combustion by controlling the timing of the spark plugs 82 and the fuel and air injectors 32, 34. As with an internal combustion engine for a motor vehicle, spark plugs 82 should be ignited when the combustion assembly 16 is filled to a desired level with the mixed fuel-air flow 58. Furthermore, as discussed above, the fill length of the lance tube 14 with the mixed fuel-air flow 58 depends on the volume of the fuel and the air that is permitted to flow through the respective injectors 32, 34. Therefore, if the frequency of the combustions is lower than the desired frequency, the controller 40 will ignite the spark plugs 82 more often. Similarly, if the combustions do not produce a desired amount of energy, the fuel and air injectors 32, 34 will be opened for a longer duration to increase the fluid flow therethrough.
In addition to controlling the characteristics of the combustion, the controller 40 also monitors whether detonation occurs within the sootblower 10. As mentioned above, if detonation fails to occur, then the pressure wave 25 may not be strong enough to effectively loosen the deposits 29 on the boiler tubes 27. Under this scenario, the operation of the sootblower 10 should be compensated to prevent undesirable build-up of the deposits 29. For example, in one design the controller 40 alerts a sootblower operator that detonation has failed to occur so that the operator can operate the sootblower for a greater duration of time or so that the operator can undertake another corrective action, such as performing maintenance on the sootblower 10. In another design, the controller 40 automatically undertakes a corrective action, such as operating the sootblower for a greater duration of time or adjusting the respective injectors 32, 34 until detonation occurs.
In one embodiment, the pressure feedback sensor 94 is utilized to determine whether detonation has occurred. For example, when detonation occurs the shock wave traveling across the lance tube 14 increases the local pressure across the shockwave dramatically. Meanwhile, rarefaction waves traveling in the opposite direction to the shock waves raise the pressure at the feed tube 15 to a lesser degree. Therefore, the pressure feedback sensor 94 is preferably positioned on an outer surface of feed tube 15 or the lance tube 14. More preferably, to prevent heat damage thereto, the pressure feedback sensor 94 is positioned on a portion of the lance tube 14 that does not typically enter the boiler interior volume 19 when the lance tube is in the operational position 14b.
When detonation occurs, the pressure feedback sensor 94 measures a relatively high shock wave for a relatively short time duration. Due to the short duration of the shock wave, the controller 40 must have a very high recording speed. For example, in one design, the controller 40 records over 1,000,000 data points per second. Relatively complex and expensive hardware and software is required to analyze such a high number of data points in a timely fashion. Therefore, rather than evaluating each data point that is recorded, the controller 40 detects data points having values above a certain threshold. Then, during operation of the sootblower 10, if the controller 40 fails to detect a data point having a value above the threshold for a predetermined amount of time, the controller 40 alerts the operator or performs internal corrective actions. For example, if a particular sootblower 10 typically produces pressure peaks greater than 100 pounds per square inch (psi) during normal detonation, and the sootblower 10 is operating at a frequency of 2 Hertz (2 combustion cycles per second), then the controller 40 alerts the operator or performs internal corrective actions if it fails to detect a data point having a value of at least 100 psi every 0.5 seconds.
As a design modification, the controller 40 may be programmed to wait for a predetermined number of detected failed detonations before alerting the operator or performing internal corrective actions. This design modification may be particularly desirable because an occasional failed detonation or a relatively small amount of failed detonations may not substantially degrade the performance of the sootblower 10 and because it may be time-consuming or inefficient for the controller 40 to frequently alert the operator or to perform internal corrective actions.
In a second embodiment, the temperature feedback sensor 96 is utilized to determine whether detonation has occurred. When detonation occurs the temperature within the sootblower 10, particularly within the feed tube 15 and the lance tube 14, increases dramatically. However, when detonation fails to occur or ceases to occur, the temperature within the feed tube 15 and the lance tube 14 ceases to increase and/or starts to decrease. Furthermore, the temperatures of the exterior surface of the feed tube 15 and the lance tube 14 are directly related to the temperatures of the internal temperatures of the respective components 15, 14. Therefore, the temperature feedback sensor 96 is preferably positioned on an outer surface of feed tube 15 or the lance tube 14. More preferably, to prevent heat damage thereto, the temperature feedback sensor 96 is positioned on a portion of the lance tube 14 that does not typically enter the boiler interior volume 19 when the lance tube is in the operational position 14b.
When detonation occurs, as indicated by point 108 in
The pressure feedback sensor 94 and the temperature feedback sensor 96 are both shown as being utilized in the embodiment in
Referring now to
In one design, the injection block 116 shown in
Referring now to
a and 12b depict more fundamental characteristics of nozzle designs 150, 152; namely the direction of travel of the shock waves caused by the nozzles 150, 152. The nozzle 150 shown in
One type of sootblower embodying the principles of the present invention is a rotating, traversing detonation sootblower. The rotating, traversing detonation sootblower typically rotates in a single direction and typically has a range of rotation of 360 degrees. A rotating detonation sootblower may have a more expansive cleaning area than a non-rotating detonation sootblower because the rotating detonation sootblower is not limited to a cleaning area in a particular radial direction from the axial direction (where the axial direction is defined as the axis of traversing movement of the sootblower lance).
Another type of sootblower embodying the principles of the present invention is an oscillating, traversing detonation sootblower. The oscillating, traversing detonation sootblower typically rotates in two directions and typically has a range of rotation of less than 360 degrees.
Yet another type of sootblower embodying the principles of the present invention is a non-rotating, non-oscillating, traversing sootblower. The non-rotating, non-oscillating, traversing sootblower typically inherently has a coverage area that is more limited than that of the rotating or oscillating sootblowers.
Another type of sootblower embodying the principles of the present invention is a non-traversing sootblower. Because the non-traversing sootblower is preferably able to dean boiler tubes that are furthest away from the boiler wall, and because the shock waves decay during the travel between the sootblower nozzle and the boiler tubes, the shock wave is preferably relatively strong when emitted from the sootblower. However, this may cause damage to the boiler tubes located relatively dose to the sootblower nozzle.
It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.
This patent application claims the benefit of U.S. provisional patent application 60/579,572, filed Jun. 14, 2004.
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