Sootblower nozzle assembly with an improved downstream nozzle

Information

  • Patent Grant
  • 6764030
  • Patent Number
    6,764,030
  • Date Filed
    Wednesday, January 2, 2002
    22 years ago
  • Date Issued
    Tuesday, July 20, 2004
    20 years ago
Abstract
The present invention discloses a new design of the nozzle and the lance tube of a sootblower to clean the interior of a heat exchanger by impingement of a jet of cleaning medium. In accordance with the teachings of the present invention the sootblower design developed, incorporates a nozzle at the tip of the distal end of the lance tube (downstream nozzle). The lance tube also includes an upstream nozzle positioned opposite and longitudinally apart the distal end nozzle. This design allows for the flow of the cleaning medium to enter into the inlet end of the nozzle without coming to a halt at the end of the lance tube. Further, the present invention also provides for a converging channel to be disposed in the interior of the lance tube to direct the flow of cleaning medium passing the upstream nozzle into the inlet end of the downstream nozzle with minimal hydraulic losses and flow maldistribution. The present invention also discloses an airfoil body to be placed around the upstream nozzle to minimize the flow disturbances caused by the bluff body of the converging channel.
Description




TECHNICAL FIELD OF THE INVENTION




This invention generally relates to a sootblower device for cleaning interior surfaces of large-scale combustion devices. More specifically, this invention relates to new designs of nozzles for a sootblower lance tube providing enhanced cleaning performance.




BACKGROUND OF THE INVENTION




Sootblowers are used to project a stream of a blowing medium, such as steam, air, or water against heat exchanger surfaces of large-scale combustion devices, such as utility boilers and process recovery boilers. In operation, combustion products cause slag and ash encrustation to build on heat transfer surfaces, degrading thermal performance of the system. Sootblowers are periodically operated to clean the surfaces to restore desired operational characteristics. Generally, sootblowers include a lance tube that is connected to a pressurized source of blowing medium. The sootblowers also include at least one nozzle from which the blowing medium is discharged in a stream or jet. In a retracting sootblower, the lance tube is periodically advanced into and retracted from the interior of the boiler as the blowing medium is discharged from the nozzles. In a stationary sootblower, the lance tube is fixed in position within the boiler but may be periodically rotated while the blowing medium is discharged from the nozzles. In either type, the impact of the discharged blowing medium with the deposits accumulated on the heat exchange surfaces dislodges the deposits. U.S. Patents which generally disclose sootblowers include the following, which are hereby incorporated by reference U.S. Pat. Nos. 3,439,376; 3,585,673; 3,782,336; and 4,422,882.




A typical sootblower lance tube comprises at least two nozzles that are typically diametrically oriented to discharge streams in directions 180° from one another. These nozzles may be directly opposing, i.e. at the same longitudinal position along the lance tube or are longitudinally separated from each other. In the latter case, the nozzle closer to the distal end of the lance tube is typically referred to as the downstream nozzle. The nozzle longitudinally furthest from the distal end is commonly referred to as the upstream nozzle. The nozzles are generally but not always oriented with their central passage perpendicular to and intersecting the longitudinal axis of the lance tube and are positioned near the distal end of the lance tube.




Various cleaning mediums are used in sootblowers. Steam and air are used in many applications. Cleaning of slag and ash encrustations within the internal surfaces of a combustion device occurs through a combination of mechanical and thermal shock caused by the impact of the cleaning medium. In order to maximize this effect, lance tubes and nozzles are designed to produce a coherent stream of cleaning medium having a high peak impact pressure on the surface being cleaned. Nozzle performance is generally quantified by measuring dynamic pressure impacting a surface located at the intersection of the centerline of the nozzle at a given distance from the nozzle. In order to maximize the cleaning effect, it is desired to have the stream of compressible blowing medium fully expanded as it exits the nozzle. Full expansion refers to a condition in which the static pressure of the stream exiting the nozzle approaches that of the ambient pressure within the boiler. The degree of expansion that a jet undergoes as it passes through the nozzle is dependent, in part, on the throat diameter (D) and the length of the expansion zone within the nozzle (L), commonly expressed as an L/D ratio. Within limits, a higher L/D ratio generally provides better performance of the nozzle.




Classical supersonic nozzle design theory for compressible fluids such as air or steam require that the nozzle have a minimum flow cross-sectional area often referred to as the throat, followed by an expanding cross-sectional area (expansion zone) which allows the pressure of the fluid to be reduced as it passes through the nozzle and accelerates the flow to velocities higher than the speed of sound. Various nozzle designs have been developed that optimize the L/D ratio to substantially expand the stream or jet, as it exits the nozzle. Constraining the practical lengths that sootblower nozzles can have is a requirement that the lance assembly must pass through a small opening in the exterior wall of the boiler, called a wall box. For long retracting sootblowers, the lance tubes typically have a diameter on the order of three to five inches. Nozzles for such lance tubes cannot extend a significant distance beyond the exterior cylindrical surface of the lance tube. In applications in which two nozzles are diametrically opposed, severe limitations in extending the length of the nozzles are imposed to avoid direct physical interference between the nozzles or an unacceptable restriction of fluid flow into the nozzle inlets occurs. In an effort to permit longer sootblower nozzles, nozzles of sootblower lance tubes are frequently longitudinally displaced. Although this configuration generally enhances performance by facilitating the use of nozzles having a more ideal L/D ratio, it has been found that the upstream nozzle exhibits significantly better performance than the downstream nozzle. Thus, an undesirable difference in cleaning effect results between the nozzles.




Initially, low performance of the downstream nozzle was attributed to the loss of static pressure associated with the fluid flow passing around the bluff body presented by the upstream nozzle in the form of the cylindrical projection of the nozzle into the lance tube interior. However, experiments conducted revealed that even when the upstream nozzle is moved radially outward to present no obstruction to the flow through the lance tube, the performance of the downstream nozzle did not significantly improve. The low performance of the downstream nozzle is believed to be due, in a significant manner, to the stagnation area created in the distal end of the conventional lance tube. A typical lance tube end or “nozzle block” has a rounded, hemispherical distal end surface. Since the downstream nozzle penetrates the nozzle block before the distal end hemispherical end surface, an internal volume exists beyond the downstream nozzle. Accordingly, a significant portion of the cleaning fluid approaching the downstream nozzle is forced to flow past the nozzle inlet and come to a stagnation condition at the distal end of the lance tube, and then re-accelerate to enter the nozzle. Furthermore, the back streams returning from the distal end are colliding with the forward streams at the downstream nozzle inlet leading to greater hydraulic losses and most importantly distorting the flow distribution into the nozzle. The hydraulic losses associated with the stagnation conditions at the distal end and at the nozzle inlet coupled with the flow mal-distribution which, based on concepts developed in connection with this invention, were believed, in large part, responsible for the low performance of the downstream nozzle. Therefore, there is a need in the art to provide a new lance tube design that will substantially increase the performance of the downstream nozzle.




SUMMARY OF THE INVENTION




In accordance with this invention, improvements in nozzle design are provided which provide enhanced performance of the downstream nozzle. In each case according to this invention, the nozzle block is formed to substantially eliminate the stagnation within the lance tube area beyond the downstream nozzle found in the prior art designs. Another beneficial feature of this invention involves streamlining at the upstream nozzle which minimizes the disruption to flow of cleaning medium to the downstream nozzle.




Briefly, a first embodiment of the present invention includes a downstream nozzle at the distal end of the lance tube with a converging channel formed in the interior of the lance tube to direct the flow of the cleaning medium passing the upstream nozzle and directing the flow to the downstream nozzle. The converging channel substantially eliminates the stagnation volume of the distal end of the conventional lance tube. This has the benefit of reducing hydraulic losses and improving the degree of uniformity of flow velocity at the throat, which in turn enhances the flow expansion and the conversion of static energy into kinetic energy.




The second embodiment of the present invention has an interior surface substantially identical to the first embodiment. However, the second embodiment nozzle block has a thin wall configuration which reduces the mass of the nozzle block.




A third embodiment of the present invention includes an airfoil body around the outside surface of the upstream nozzle. By providing streamline design of the outer surface of the upstream nozzle, the flow disturbances associated with the upstream nozzle is minimized.




A fourth embodiment of the invention features an upstream nozzle with its inlet end tipped toward the flow of the cleaning medium flowing through the lance tube.




In a fifth embodiment, the upstream nozzle features a longitudinal axis perpendicular to the longitudinal axis of the lance tube with the nozzle inlet tipped toward the flow of the blowing medium.




In a sixth embodiment in accordance with the teaching of the present invention provides for the design of the upstream nozzle having its outlet end flush with the body of the lance tube.











BRIEF DESCRIPTION OF THE DRAWINGS




Further features and advantages of the invention will become apparent from the following discussion and accompanying drawings, in which:





FIG. 1

is a pictorial view of a long retracting sootblower which is one type of sootblower which may incorporate the nozzle assemblies of the present invention;





FIG. 2

is a cross-sectional view of a sootblower nozzle block according to prior art teachings;





FIG. 2A

is a cross section view similar to

FIG. 2

but showing alternative stagnation regions for the nozzle head;





FIG. 3

is a perspective representation of a lance tube nozzle block incorporating the features according to a first embodiment of the invention;





FIG. 4

is a cross section front view of the lance tube nozzle block according to the first embodiment of the present invention as shown in

FIG. 3

;





FIG. 5A

is an enlarged cross-sectional view of the upstream nozzle in accordance with the teachings of the first embodiment of the present invention;





FIG. 5B

is an enlarged cross-sectional view of the downstream nozzle in accordance with the teachings of the first embodiment of the present invention;





FIG. 6

is a cross-sectional front view of the lance tube nozzle block having a thin wall configuration in accordance with the teachings of the second embodiment of the present invention;





FIG. 7

is a cross-sectional front view of the lance tube nozzle block incorporating the airfoil or streamlining body around the upstream nozzle in accordance with the teachings of the third embodiment of the present invention;





FIG. 7A

is an elevated cross-section view of the lance tube nozzle block incorporating the airfoil body around the upstream nozzle in accordance with the teachings of the third embodiment of the present invention;





FIG. 7B

is a top perceptive view of the lance tube nozzle block incorporating the airfoil body around the upstream nozzle wherein the external surface of the nozzle has a trapezoidal cross section in accordance with the teachings of the third embodiment of the present invention;





FIG. 8

is a cross-sectional representation of the lance tube nozzle block having a curved upstream nozzle with respect to the longitudinal axis of the lance tube in accordance with the fourth embodiment of the present invention;





FIG. 9

is a cross-sectional representation of the lance tube nozzle block having an upstream nozzle with a straight discharge axis and a slanted inlet opening in accordance with the fifth embodiment of the present invention; and





FIG. 10

is a cross-sectional representation of the lance tube nozzle block having a exit plane of the upstream nozzle flush with the outer diameter of the lance tube nozzle block and having a thin wall construction in accordance with the sixth embodiment of the present invention.











DETAILED DESCRIPTION OF THE INVENTION




The following description of the preferred embodiment is merely exemplary in nature, and is in no way intended to limit the invention or its application or uses.




A representative sootblower, is shown in FIG.


1


and is generally designated there by reference number


10


. Sootblower


10


principally comprises frame assembly


12


, lance tube


14


, feed tube


16


, and carriage


18


. Sootblower


10


is shown in its normal retracted resting position. Upon actuation, lance tube


14


is extended into and retracted from a combustion system such as a boiler (not shown) and may be simultaneously rotated.




Frame assembly


12


includes a generally rectangularly shaped frame box


20


, which forms a housing for the entire unit. Carriage


18


is guided along two pairs of tracks located on opposite sides of frame box


20


, including a pair of lower tracks (not shown) and upper tracks


22


. A pair of toothed racks (not shown) are rigidly connected to upper tracks


22


and are provided to enable longitudinal movement of carriage


18


. Frame assembly


12


is supported at a wall box (not shown) which is affixed to the boiler wall or another mounting structure and is further supported by rear support brackets


24


.




Carriage


18


drives lance tube


14


into and out of the boiler and includes drive motor


26


and gear box


28


which is enclosed by housing


30


. Carriage


18


drives a pair of pinion gears


32


which engage the toothed racks to advance the carriage and lance tube


14


. Support rollers


34


engage the guide tracks to support carriage


18


.




Feed tube


16


is attached at one end to rear bracket


36


and conducts the flow of cleaning medium which is controlled through the action of poppet valve


38


. Poppet valve


38


is actuated through linkages


40


which are engaged by carriage


18


to begin cleaning medium discharge upon extension of lance tube


14


, and cuts off the flow once the lance tube and carriage return to their idle retracted position, as shown in FIG.


1


. Lance tube


14


over-fits feed tube


16


and a fluid seal between them is provided by packing (not shown). A sootblowing medium such as air or steam flows inside of lance tube


14


and exits through one or more nozzles


50


mounted to nozzle block


52


, which defines a distal end


51


. The distal end


51


is closed by a semispherical wall


53


.




Coiled electrical cable


42


conducts power to the drive motor


26


. Front support bracket


44


supports lance tube


14


during its longitudinal and rotational motion. For long lance tube lengths, an intermediate support


46


may be provided to prevent excessive bending deflection of the lance tube.




Now with reference to

FIG. 2

, a more detailed illustration of a nozzle block


52


according to prior art is provided. As shown, nozzle block


52


includes a pair of diametrically opposite positioned nozzles


50


A and


50


B. The nozzles


50


A and


50


B are displaced from the distal end


51


, with nozzle


50


B being referred to as the downstream nozzle (closer to distal end


51


) and nozzle


50


A being the upstream nozzle (farther from distal end


51


).




The cleaning medium, typically steam under a gage pressure of about 150 psi or higher, flows into nozzle block


52


in the direction as indicated by arrow


21


. A portion of the cleaning medium enters and is discharged from the upstream nozzle


50


A as designated by arrow


23


. A portion of the flow designated by arrows


25


passes the nozzle


50


A and continues to flow toward downstream nozzle


50


B. Some of that fluid directly exits nozzle


50


B, designated by arrow


27


. As explained above, the downstream nozzle


50


B typically exhibits lower performance as compared to the upstream nozzle


50


A. This is attributed to the fact that the flow of cleaning medium that passes the upstream nozzle


50


A and downstream nozzle


50


B designated by arrows


29


comes to a complete halt (stagnates) at the distal end


51


of the lance tube


14


, thereby creating a stagnation region


31


at the distal end


51


beyond downstream nozzle


50


B. Hence, the cleaning medium represented by arrow


33


has to re-accelerate, flow backward and merge with the incoming flow


27


. The merging of the forward flow represented by arrow


27


and backward flow represented by arrow


33


results in loss of energy due to hydraulic losses at the nozzle inlet, and also results in flow mal-distribution. The loss of energy associated with stagnation conditions at the distal end and hydraulic losses at the nozzle inlet, and the deformation of the inlet flow profile is believed to be responsible for the downstream nozzle's lower performance in prior art designs.




As mentioned previously, there are various explanations for the comparatively lower performance of downstream nozzle


50


B as compared with nozzle


50


A. These inventors have found that the performance of downstream nozzle


50


B is enhanced by eliminating the stagnation area at nozzle block distal end


51


and moving the stagnation area to the inlet of the downstream nozzle; in other words, substantially eliminating the cleaning medium flows represented by arrows


29


and


33


shown in FIG.


2


. The advantages of this design concept can be described mathematically with reference to the following description and FIG.


2


A.




One of the key parameters in designing an efficient convergent-divergent Laval nozzle, such as nozzles


50


A and


50


B, is the throat-to-exit area ratio (Ae/At). A nozzle with an ideal throat-to-exit area ratio would achieve uniform, fully expanded, flow at the nozzle exit plane. The amount of gas expansion in the divergent section is given by the following equation which characterizes cleaning medium flow as one-dimensional for the same of simplified calculation.











A





e


A





t


=



1

M





e




[


(

2

γ
+
1


)

·

(

1
+




γ
-
1

2

·
M







e
2



)


]




(

γ
+
1

)


2


(

γ
-
1

)








Equation





1













Where,




Ae=Nozzle exit area




At=Throat area which is also equal to the area of the ideal sonic plane




The exit Mach number, Me, is related to the throat-to-exit area ratio via the continuity equation and the isentropic relations of an ideal gas (See Michael A. Saad, “Compressible Fluid Flow”, Prentice Hall, Second Edition, page 98.)










P





e

=

P






o
·


(

1
+




γ
-
1

2

·
M







e
2



)


γ

1
-
γ









Equation





2













Where,




γ=Specific heat ratio of cleaning fluid. For air γ=1.4. For steam, γ−1.329




Pe=Nozzle exit static pressure, psia




Po=Total pressure, psia




Me=Nozzle exit Mach number




In the above equation 2, the relationship between exit Mach number and the pressure ratio is based on the assumption that the flow reaches the speed of sound at the plane of the smallest cross-sectional area of the convergent-divergent nozzle, nominally the throat. However, in practice, especially in sootblower applications, the flow does not reach the speed of sound at the throat, and not even in the same plane. The actual sonic plane is usually skewered further downstream from the throat, and its shape becomes more non-uniform and three-dimensional.




The distortion of the sonic plane is mainly due to the flow mal-distribution into the nozzle inlet section. In sootblower applications, as shown by arrows


23


for nozzle


50


A and arrows


33


and


27


for nozzle


50


B in

FIG. 2

, the cleaning fluid approaches the nozzle at 90° off its center axis. With such configuration, the flow entering the nozzle favors the downstream half of the nozzle inlet section because the entry angle is less steep.




The distortion and dislocation of the sonic plane consequently impacts the expansion of the cleaning fluid in the divergent section, and results in non-uniformly distributed exit pressure and Mach number. These findings were consistent with the measured and predicted exit static pressure for one of the conventional sootblower nozzles.




To account for the shift in the sonic plane, the actual Mach number at the exit can be related to the ideal throat-to-exit area as follows:












A





e


A





t


·


A





t


A





t_a



=



1

M





e_a




[


(

2

γ
+
1


)

·

(

1
+




γ
-
1

2

·
M







e_a
2



)


]




(

γ
+
1

)


2


(

γ
-
1

)








Equation





3













Where,




At_a=Effective area of the actual sonic plane




Me_a=Average of the actual Mach number at the nozzle exit




The degree of mal-distribution of the exit Mach number and the static pressure varies between the upstream and downstream nozzles


50


A and


50


B respectively of a sootblower. It appears that the downstream nozzle


50


B exhibits more non-uniform exit conditions than the upstream nozzle


50


A, which is believed to be part of the cause of its relatively poor performance.




The location of the downstream nozzle


50


B relative to the distal end


51


not only causes greater hydraulic losses, but also causes further misalignment of the incoming flow streams with the nozzle inlet. Again, greater flow mal-distribution at the nozzle inlet would translate to greater shift and distortion in the sonic plane, and consequently poorer performance. For the prior art designs, the ratio (At/At_a) is smaller for the downstream nozzle


50


B compared to the upstream nozzle


50


A.




In designing more efficient sootblower nozzles, it is necessary to keep the ideal and actual area ratio (At/At_a) closer to unity. Several methods are proposed in this discovery to accomplish this goal. For the upstream nozzle, the “At/At_a” ratio is in part influenced by dimension “X” and “α” shown in

FIG. 2A

, (At/At_a=f(α, X). Dimension X designates the longitudinal separation between nozzles


50


A and


50


B.




A smaller spacing X would cause the incoming flow stream


27


to become more mis-aligned with the upstream nozzle axis. For example, a five inch space for X has a relatively better performance than a four inch spacing for X.




While the greater X distance is beneficial, it is at the same time desired in most sootblower applications to keep X to a minimum for mechanical reasons. In such circumstances, an optimum X distance should be used which would minimize flow disturbance and yet satisfy mechanical requirements. Also, reducing the flow streams approach angle (α) shown in

FIG. 2A

would reduce flow mal-distribution at the nozzle inlet, and potentially reduce inlet losses.




For downstream nozzle


50


B, the “At/At_a” ratio is in part influenced by dimension “Y” shown in

FIG. 2A

, (At/At_a=f(Y)). Dimension Y is defined as the longitudinal distance between the inside surface of distal end


51


and the inlet axis of downstream nozzle


50


B.




Again referring to

FIG. 2A

, the location of the distal plane relative to the downstream nozzle


50


B, influences the alignment of the flow stream into the nozzle and cause greater flow mal-distribution. For instance, Y1 (which typifies the prior art) is the least favorable distance between the nozzle center axis and the distal end


51


of the lance tube. With such configuration, the nozzle performance is relatively poor. Y2 is an improved distance which is based on a modified distal end surface designated as


51


′. In the case of Y2, the cleaning fluid


25


does not flow past the downstream nozzle


50


B, therefore eliminating stagnation conditions of the flows represented by arrows


29


and


33


. Instead the flow is efficiently channeled to the nozzle inlet. Thus, if the dimension Y is assumed positive in the left hand direction along the longitudinal axis of nozzle block


52


shown in

FIG. 2A

, there is an absence of any substantial flow of cleaning medium in the negative Y direction. Also, if the longitudinal axis (shown as a dashed line) of nozzle


50


B defines a Z axis assumed positive in the direction of discharge from the nozzle, then it is further true that once the longitudinal point is reached along the nozzle block


52


where flow first begins to enter downstream nozzle


50


B, there is a complete absence of any flow velocity vector having a negative Z component. In this way the hydraulic and energy losses at the nozzle inlet are minimized, improving the performance of downstream nozzle


50


B. Furthermore, with this improvement the cleaning fluid enters the downstream nozzle


50


B more uniformly, therefore minimizing the distortion of the sonic plane which in turn enhances the fluid expansion and the conversion of total pressure to kinetic energy. The optimal value of Y is substantially equal to Y2 which is one-half the diameter of the inlet end of downstream nozzle


50


B.




On the other hand, providing a shape of the distal end inside surface to


51


″ is not beneficial. In such a configuration, the inlet flow area is reduced and the flow streams are further mis-aligned relative to the nozzle center axis, which could lead to flow separation and shedding.




Now with reference to

FIGS. 3 and 4

, a lance tube nozzle block


102


in accordance with the teachings of the first embodiment of this invention is shown. The lance tube nozzle block


102


comprises a hollow interior body or plenum


104


having an exterior surface


105


. The distal end of the lance tube nozzle block is generally represented by reference numeral


106


. The lance tube nozzle block includes two nozzles


108


and


110


radially positioned and longitudinally spaced. Preferably, lance tube nozzle block


102


and the nozzles


108


and


110


are formed as one integral piece. Alternatively, it is also possible to weld the nozzles into the nozzle block


102


.





FIG. 4

illustrates in detail the nozzles


108


and


110


. As shown, the nozzle


108


is disposed at the distal end


106


of the lance tube nozzle block


102


and is commonly referred to as the downstream nozzle. The nozzle


110


disposed longitudinally away from the distal end


106


is commonly referred to as the upstream nozzle.




With reference to

FIGS. 4 and 5A

the upstream nozzle


110


is shown which is a typical converging and diverging nozzle of the well-known Laval configuration. In particular, the upstream nozzle


110


defines an inlet end


112


that is in communication with the interior body


104


of the lance tube nozzle block


102


. The nozzle


110


also defines an outlet end


114


through which the cleaning medium is discharged. The converging wall


116


and the diverging wall


118


form the throat


120


. The central axis


122


of the discharge of the nozzle


110


is substantially perpendicular to the longitudinal axis


125


of the lance tube nozzle block


102


. However, it is also possible to have the central axis of discharge


122


oriented within an angle of about seventy degrees (70°) to about an angle substantially perpendicular to the longitudinal axis. The diverging wall


118


of the nozzle


110


defines a divergence angle φ


1


as measured from the central axis of discharge


122


. The nozzle


110


further defines an expansion zone


124


having a length L


1


between the throat


120


and the outlet end


114


.




With reference to

FIGS. 4 and 5B

, the downstream nozzle


108


also comprises an inlet end


126


and outlet end


128


formed about axis


136


. A portion of the cleaning medium not entering the upstream nozzle


110


, enters the downstream nozzle


108


at the inlet end


126


. The cleaning medium enters the inlet end


126


and exits the nozzle


108


, through the outlet end


128


. The converging wall


130


and the diverging wall


132


define the throat


134


of the downstream nozzle


108


. The plane of the throat


134


is substantially parallel to the longitudinal axis


125


of the nozzle block. The diverging walls


132


of the downstream nozzle


108


are straight, i.e. conical in shape, but other shapes could be used. The central axis


136


of nozzle


108


is oriented within an angle of about seventy degrees (70°) to about an angle substantially perpendicular to the longitudinal axis


125


of the lance tube nozzle block


102


. The nozzle


108


defines a divergent angle φ


2


as measured from the central axis of discharge


136


. An expansion zone


138


having a length L


2


is defined between throat


134


and the outlet end


128


.




Referring to

FIG. 4

, since the performance of a nozzle depends, in part, on the degree of expansion of the cleaning medium jet that exits through the nozzle. Preferably, the downstream nozzle


108


and the upstream nozzle


110


have identical geometry. Alternatively, the present invention may also incorporate downstream and upstream nozzle


108


and


110


, respectively, having different geometry. In particular, the diameter of throat


134


of the downstream nozzle


108


may be larger than the diameter of throat


120


of the upstream nozzle


110


. Further, the length L


2


of the expansion chamber


138


may be greater than the length L


1


of the expansion chamber


124


of the upstream nozzle


110


. In an alternate embodiment, the diameter of the throat


134


is at least 5% larger than the diameter of throat


120


and the length L


2


is at least 10% greater than length L


1


. Hence, the L/D ratio of the downstream nozzle


108


may be larger than the L/D ratio of the upstream nozzle


110


.




As shown in

FIG. 4

, the flow of cleaning medium that passes the upstream nozzle


110


represented by arrow


152


is directed by a converging channel


142


. The converging channel


142


is formed in the interior


104


of the lance tube nozzle block


102


between the upstream nozzle


110


and the downstream nozzle


108


. The converging channel


142


is preferably formed by placing an aerodynamic converging contour body


144


around the surface of downstream nozzle throat


134


. The converging channel


142


gradually decreases the cross-section of the interior


104


of the lance tube nozzle block


102


between the inlet end


112


of the upstream nozzle


110


and the inlet end


126


of the downstream nozzle


108


. The tip


148


of the body


144


is in the same plane as the inlet end


126


of the nozzle


108


. In the preferred embodiment, the contour body


144


is an integral part of the lance tube nozzle block


102


and the downstream nozzle


108


. The contour body


144


has a sloping contour such that the flow of the cleaning medium will be directed toward the inlet end


126


of the downstream nozzle


108


. Thus, converging channel


142


presents a cross-sectional flow area for the blowing medium which smoothly reduces from just past upstream nozzle


110


to the downstream nozzle


108


and turns the flow of cleaning medium to enter the downstream nozzle with reduced hydraulic losses.




As shown in

FIG. 4

, operation of nozzle block


102


in accordance with the first embodiment of the present invention is illustrated. The cleaning medium flows in the interior


104


of the lance tube nozzle block


102


in the direction shown by arrows


150


. A portion of the cleaning medium enters the upstream nozzle


110


through the inlet end


112


. The cleaning medium then enters the throat


120


where the medium may reach the speed of sound. The medium then enters the expansion chamber


124


where it is further accelerated and exits the upstream nozzle


110


at the outlet end


114


.




A portion of the cleaning medium not entering the inlet end


112


of the upstream nozzle


110


flows towards the downstream nozzle


108


as indicated by arrows


152


. The cleaning medium flows into the converging channel


142


formed in the interior


104


of the lance tube nozzle block


102


. The converging channel


142


directs the cleaning medium to the inlet end


126


of the downstream nozzle


108


. Therefore, the cleaning medium does not substantially flow longitudinally beyond the inlet end


126


of the downstream nozzle


108


. In addition, once the flow reaches inlet end


126


, there is no flow velocity component in the negative “Z” direction (defined as aligned with axis


136


and positive in the direction of flow discharge). Due to the presence of the converging channel


142


, the flow of the cleaning medium is more efficiently driven to the nozzle inlet


126


. The loss of energy associated with the cleaning medium entering the throat


134


of the downstream nozzle


108


is reduced, hence increasing the performance of the downstream nozzle


108


. Unlike prior art designs, the flowing medium does not have to come to a complete halt in a region beyond the downstream nozzle and then re-accelerate to enter the inlet end


126


of the nozzle


108


. Further, since it is also possible to have different geometry for the upstream nozzle


110


and the downstream nozzle


108


, the cleaning medium entering the expansion zone


138


in the downstream nozzle


108


is expanded more than the cleaning medium in the expansion zone


124


of the upstream nozzle


110


so as to compensate for any nozzle inlet pressure difference between the nozzles


108


and


110


. The kinetic energy of the cleaning medium exiting the downstream nozzle


108


more closely approximates the kinetic energy of the cleaning medium exiting the upstream nozzle


110


.




With particular reference to

FIG. 6

, a lance tube nozzle block


202


in accordance with the second embodiment of the present invention is shown. The lance tube nozzle block


202


is similar to the lance tube nozzle block


102


defining a hollow interior


204


and exterior surface


205


. The lance tube nozzle block


202


has a downstream nozzle


208


and an upstream nozzle


210


that have identical configuration to nozzles


108


and


110


of the first embodiment. Further, the nozzle block


202


has identical internal volume and flow paths as the nozzle block


102


.




The second embodiment differs from the first embodiment in the wall thickness of the nozzle block


202


is reduced. The flow obstruction


244


is hollow, thereby reducing the mass of the nozzle block


202


.




With reference to

FIGS. 7

,


7


A and


7


B, a lance tube nozzle block


302


for a sootblower in accordance with the teaching of the third embodiment of the present invention is shown. The lance tube nozzle block


302


includes a hollow interior


304


. The lance tube nozzle block


302


includes a downstream nozzle


306


and an upstream nozzle


310


. The dimension and geometry of the downstream and upstream nozzles


306


and


310


, respectively, are identical to the dimension and geometry of the nozzles


108


and


110


of the first embodiment.




This embodiment of the lance tube nozzle block


302


differs from the previously described embodiment in that the upstream nozzle


310


includes an airfoil or streamline body


311


around the nozzle diverging surface


312


of the upstream nozzle


310


. Preferably, the upstream nozzle airfoil body


311


has a trapezoidal cross section. The divergent section


307


(as shown in

FIG. 7A

) of the upstream nozzle


310


is circular at each point along its axis from the inlet to the exit plane. The airfoil body


311


has a smooth upstream incline surface


314


A and a downstream incline surface


314


B. The upstream incline surface


314


A receives the cleaning medium from the proximate end of the nozzle block which flows in the direction as shown by arrows


319


in FIG.


7


. The downward incline surface


314


B allows a smooth flow of the cleaning medium past the upstream nozzle


310


to the inlet end


316


of the downstream nozzle


306


as shown by arrows


320


. The angle of incline Ψ


1


of the airfoil body


311


is measured between central axis


315


of upstream nozzle


310


and the inclining surface


314


B of the airfoil body


311


as shown in FIG.


7


. In the preferred embodiment the airfoil body


311


is made of same material as the nozzle block


302


. The airfoil body


311


provides for a smooth flow of the cleaning medium to the inlet end


316


of the downstream nozzle


306


as shown by arrows


320


. Further, the airfoil body


311


will help reduce the turbulent eddies influencing the upstream nozzle


310


and minimize pressure drop of the flow


320


that passes upstream nozzle


310


to feed the downstream nozzle


306


.

FIG. 7A

is a sectional view of nozzle block


302


which is tipped slightly. This perspective helps to further illustrate the contours of hollow interior


304


.

FIG. 7B

shows particularly a solidified form of airfoil body


311


. This view shows that airfoil body


311


′, like airfoil body


311


, includes side surfaces


324


. Airfoil bodies


311


and


311


′ are configured to minimize obstructions of flow area past nozzle


310


. This is, in part, provided by having side surface


324


closely approach these inside surfaces,


307


, of nozzle


310


.




Now referring to

FIG. 8

, a lance tube nozzle block


402


in accordance with the fourth embodiment of the present invention is illustrated. The lance tube nozzle block hollow interior


404


defines a longitudinal axis


407


. The lance tube nozzle block


402


has a downstream nozzle


408


, positioned at a distal end


406


of the lance tube nozzle block


402


. The upstream nozzle


410


is longitudinally spaced from the downstream nozzle


408


. In this embodiment, the downstream nozzle


408


has the same configuration as the nozzle


108


of the first embodiment. However, the geometry of the upstream nozzle


410


is different. In this embodiment, the upstream nozzle


410


has a curved interior shape such that the inlet end


412


curves towards the flow of the cleaning medium as shown by arrows


411


. The central axis of discharge end


416


as measured from the inlet end


412


to the outlet end


418


is curved and not straight. The upstream nozzle


410


has converging walls


420


and diverging wall


422


joining the converging walls. The converging walls


420


and the diverging walls


422


define a throat


424


. A central axis of throat


424


is curved such that the angle Ψ


3


defined between the throat


424


and the longitudinal axis


407


of the nozzle block


402


is in the range of 0 to 90 degrees. Preferably the angle Ψ


3


is equal to about 45 degrees.





FIG. 9

represents a lance tube nozzle block


502


in accordance with the fifth embodiment of the present invention. The lance tube nozzle block


502


has identical configuration as the lance tube nozzle block in the fourth embodiment. The lance tube nozzle block


502


has a downstream nozzle


508


positioned at the distal end


506


of the lance tube nozzle block


502


. The lance tube nozzle block


502


has an upstream nozzle


510


that defines an inlet end


512


and an outlet end


514


. A throat


516


is defined by converging walls


520


and diverging walls


522


.




The present embodiment differs from the nozzle geometry in the fourth embodiment in that the upstream nozzle


510


has a central axis


518


, which is straight and not curved as described in the previous embodiment. The present embodiment has an inlet end


512


angled towards the flow of the cleaning medium, as shown by arrows


511


. In order to have the inlet end


512


angled toward the flow of the cleaning medium, the converging and diverging walls


520


and


522


, diametrically opposite each other are of different length. Thus, the diverging wall


522


A is longer than the diverging wall


522


B.





FIG. 10

represents the sixth embodiment of the present invention. The lance tube nozzle block


602


defines an interior surface


604


and an exterior surface


606


. The downstream nozzle


608


is positioned at the distal end


607


of the lance tube nozzle block


602


. The downstream nozzle


608


is of the same configuration and dimension as the nozzle


108


of the first embodiment.




The upstream nozzle


610


is a straight nozzle having an inlet end


612


and an outlet end


614


. Like the upstream nozzle of the previous embodiments, the upstream nozzle


610


has a throat


616


defined by the converging walls


618


and diverging walls


620


. The upstream nozzle


610


defines a central axis of discharge


622


between the inlet end


612


and the outlet end


614


. In this embodiment, the plane


624


of the outlet end


614


is flush with the exterior surface


606


of the lance tube nozzle block


602


. The nozzle expansion zone


622


provided by the diverging walls


620


is located entirely inside the diameter of lance tube nozzle block


602


. Nozzle block


602


further features a “thin wall” construction in which the outer wall has a nearly uniform thickness, yet forms ramp surfaces


628


and


630


, and tip


632


.




The foregoing discussion discloses and describes a preferred embodiment of the invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that changes and modifications can be made to the invention without departing from the true spirit and fair scope of the invention as defined in the following claims.



Claims
  • 1. A lance tube nozzle block for a sootblower for cleaning internal heat exchanger surfaces by impingement of a jet of a cleaning medium, the nozzle block comprising:a nozzle block body defining a longitudinal axis, a hollow interior, a distal end, and a proximate end with the proximate end receiving the cleaning medium; a downstream nozzle positioned adjacent the distal end of the nozzle block body for discharging the cleaning medium, the downstream nozzle having a first inlet end, a first converging section near the first inlet end, a first diverging section joining the first converging section and terminating with a first outlet end, a first throat at the point where the first converging section and the first diverging section are joined, a first expansion zone between the first throat and the first outlet end, the downstream nozzle having a first axis of discharge substantially perpendicular to the nozzle block body longitudinal axis, the nozzle block body hollow interior and the downstream nozzle cooperating such that the cleaning medium flowing in the direction of the longitudinal axis from the proximate end to the distal end through the nozzle block body hollow interior does not flow substantially beyond the downstream nozzle first inlet end; and an upstream nozzle for discharging the cleaning medium positioned at a longitudinal position of the lance tube nozzle block displaced from the distal end and the downstream nozzle, the upstream nozzle having a second inlet end, a second outlet end, wherein the cleaning medium enters the upstream nozzle through the second inlet end and exits through the second outlet end with a second axis of discharge substantially perpendicular to the nozzle block body longitudinal axis, a second converging section near the second inlet end, a second diverging section joining the second converging section defining a second throat, and a second expansion zone between the second throat and the second outlet end.
  • 2. The nozzle block of claim 1 wherein the downstream nozzle first expansion zone defines a first expansion length and the first throat defines a first diameter, and the upstream nozzle second expansion zone defines a second expansion length and the second throat defines a second diameter, and wherein the ratio of the first expansion length to the first diameter is different than the ratio of the second expansion length to the second diameter.
  • 3. The nozzle block of claim 1 wherein the downstream nozzle first expansion zone defines a first expansion length and the first throat defines a first diameter, and the upstream nozzle second expansion zone defines a second expansion length and the second throat defines a second diameter, and wherein the ratio of the first expansion length to the first diameter is equal to the ratio of the second expansion length to the second diameter.
  • 4. The nozzle block of claim 1 wherein the nozzle block body defines an exterior surface and the second outlet end is substantially within the cylinder defined by the exterior surface of the nozzle block body.
  • 5. The nozzle block of claim 1 wherein the nozzle block body defines an exterior surface and the first outlet end is substantially within the cylinder defined by the exterior surface of the nozzle block body.
  • 6. The nozzle block of claim 1 wherein the cleaning medium is comprised at least in part of steam.
  • 7. The nozzle block of claim 1 adapted to be connected with a lance tube, the nozzle block and the lance tube having a cylindrical exterior surface with both the downstream nozzle and the upstream nozzle located within the cylindrical surface.
  • 8. A lance tube nozzle block for a sootblower for cleaning internal heat exchanger surfaces by impingement of a jet of a cleaning medium, the nozzle block comprising:a nozzle block body defining a longitudinal axis, a hollow interior, a distal end, and a proximate end with the proximate end receiving the cleaning medium; a downstream nozzle positioned adjacent the distal end of the nozzle block body for discharging the cleaning medium, the downstream nozzle having an inlet end and an axis of discharge substantially perpendicular to the nozzle block body longitudinal axis, the nozzle block body hollow interior and the downstream nozzle cooperating such that the cleaning medium flowing in the direction of the longitudinal axis from the proximate end to the distal end through the nozzle block body interior does not flow substantially beyond the downstream nozzle inlet end; and an upstream nozzle for discharging the cleaning medium positioned at a longitudinal position of the lance tube nozzle block displaced from the distal end and the downstream nozzle; wherein the upstream nozzle creates a stream of the cleaning medium directed in a direction which is diametrically opposite the direction of a stream of the cleaning medium created by the downstream nozzle.
  • 9. The nozzle block of claim 8 wherein the cleaning medium is comprised at least in part of steam.
  • 10. The nozzle block of claim 8 adapted to be connected with a lance tube, the nozzle block and the lance tube having a cylindrical exterior surface with both the downstream nozzle and the upstream nozzle located within the cylindrical surface.
  • 11. A lance tube nozzle block for a sootblower for cleaning internal heat exchanger surfaces by impingement of a jet of a cleaning medium, the nozzle block comprising:a nozzle block body defining a longitudinal axis, a hollow interior, a distal end, and a proximate end with the proximate end receiving the cleaning medium; a downstream nozzle positioned adjacent the distal end of the nozzle block body for discharging the cleaning medium, the downstream nozzle having an inlet end and an axis of discharge substantially perpendicular to the nozzle block body longitudinal axis, the nozzle block body hollow interior and the downstream nozzle cooperating such that the cleaning medium flowing in the direction of the longitudinal axis from the proximate end to the distal end through the nozzle block body interior does not flow substantially beyond the downstream nozzle inlet end; wherein the nozzle block body hollow interior defines a converging channel of decreasing cross-sectional area at all points distal of the downstream nozzle; and an upstream nozzle for discharging the cleaning medium positioned at a longitudinal position of the lance tube nozzle block displaced from the distal end and the downstream nozzle.
  • 12. The nozzle block of claim 11 wherein the converging channel is defined at least in part by a contoured body disposed adjacent the downstream nozzle inlet end and defining a surface of the hollow interior of the nozzle block body.
  • 13. The nozzle block of claim 12 wherein a tip of the contoured body in part defines the downstream nozzle inlet end.
  • 14. The nozzle block of claim 11 wherein the cleaning medium is comprised at least in part of steam.
  • 15. The nozzle block of claim 11 adapted to be connected with a lance tube, the nozzle block and the lance tube having a cylindrical exterior surface with both the downstream nozzle and the upstream nozzle located within the cylindrical surface.
  • 16. A lance tube nozzle block for a sootblower for cleaning internal heat exchanger surfaces by impingement of a jet of a cleaning medium, the nozzle block comprising:a nozzle block body defining a longitudinal axis, a hollow interior, a distal end, and a proximate end with the proximate end receiving the cleaning medium; a downstream nozzle positioned adjacent the distal end of the nozzle block body for discharging the cleaning medium, the downstream nozzle having an inlet end and an axis of discharge substantially perpendicular to the nozzle block body longitudinal axis, the nozzle block body hollow interior and the downstream nozzle cooperating such that the cleaning medium flowing in the direction of the longitudinal axis from the proximate end to the distal end through the nozzle block body interior does not flow substantially beyond the downstream nozzle inlet end; an upstream nozzle for discharging the cleaning medium positioned at a longitudinal position of the lance tube nozzle block displaced from the distal end and the downstream nozzle; and wherein an airfoil body surrounds the upstream nozzle and defines a portion of the hollow interior of the nozzle block body.
  • 17. The nozzle block of claim 16 wherein the airfoil body has an upstream incline to direct the flow of the cleaning medium from the nozzle block proximate end to the upstream nozzle and a downstream incline to direct the cleaning medium towards the downstream nozzle past the upstream nozzle.
  • 18. The nozzle block of claim 16 wherein the cleaning medium is comprised at least in part of steam.
  • 19. The nozzle block of claim 16 adapted to be connected with a lance tube, the nozzle block and the lance tube having a cylindrical exterior surface with both the downstream nozzle and the upstream nozzle located within the cylindrical surface.
  • 20. A lance tube nozzle block for a sootblower for cleaning internal heat exchanger surfaces by impingement of a jet of a cleaning medium, the nozzle block comprising:a nozzle block body defining a longitudinal axis, a hollow interior, a distal end, and a proximate end with the proximate end receiving the cleaning medium; a downstream nozzle positioned adjacent the distal end of the nozzle block body for discharging the cleaning medium, the downstream nozzle having an inlet end and an axis of discharge substantially perpendicular to the nozzle block body longitudinal axis, the nozzle block body hollow interior and the downstream nozzle cooperating such that the cleaning medium flowing in the direction of the longitudinal axis from the proximate end to the distal end through the nozzle block body interior does not flow substantially beyond the downstream nozzle inlet end; wherein the nozzle block body hollow interior and the downstream nozzle define a distance (Y) measured along the nozzle block body longitudinal axis from the downstream nozzle axis of discharge to an inside surface of the hollow interior at the distal end and wherein the distance (Y) is not substantially greater than one-half the diameter of the downstream nozzle inlet end; and an upstream nozzle for discharging the cleaning medium positioned at a longitudinal position of the lance tube nozzle block displaced from the distal end and the downstream nozzle.
  • 21. The nozzle block of claim 20 wherein the flow of cleaning medium in the direction of the longitudinal axis is assumed positive from the proximate end to the distal end and once the cleaning medium enters the downstream nozzle inlet, there is an absence of the flow of the cleaning medium in the negative (Y) direction.
  • 22. The nozzle block of claim 20 wherein the cleaning medium is comprised at least in part of steam.
  • 23. The nozzle block of claim 20 adapted to be connected with a lance tube, the nozzle block and the lance tube having a cylindrical exterior surface with both the downstream nozzle and the upstream nozzle located within the cylindrical surface.
  • 24. A lance tube nozzle block for a sootblower for cleaning internal heat exchanger surfaces by impingement of a jet of a cleaning medium, the nozzle block comprising:a nozzle block body defining a longitudinal axis, a hollow interior, a distal end, and a proximate end with the proximate end receiving the cleaning medium; a downstream nozzle positioned adjacent the distal end of the nozzle block body for discharging the cleaning medium, the downstream nozzle having an inlet end and an axis of discharge substantially perpendicular to the nozzle block body longitudinal axis, the nozzle block body hollow interior and the downstream nozzle cooperating such that the cleaning medium flowing in the direction of the longitudinal axis from the proximate end to the distal end through the nozzle block body interior does not flow substantially beyond the downstream nozzle inlet end; and an upstream nozzle for discharging the cleaning medium positioned at a longitudinal position of the lance tube nozzle block displaced from the distal end and the downstream nozzle; and wherein the upstream nozzle axis of discharge is tipped from perpendicular to the nozzle block body longitudinal axis toward the proximate end.
  • 25. The nozzle block of claim 24 wherein the upstream nozzle axis of discharge defines a curved line.
  • 26. The nozzle block of claim 25 wherein the nozzle block body has a substantially uniform wall thickness.
  • 27. The nozzle block of claim 24 wherein the axis of discharge defines a straight line.
  • 28. The nozzle block of claim 24 wherein the cleaning medium is comprised at least in part of steam.
  • 29. The nozzle block of claim 24 adapted to be connected with a lance tube, the nozzle block and the lance tube having a cylindrical exterior surface with both the downstream nozzle and the upstream nozzle located within the cylindrical surface.
  • 30. A lance tube nozzle block for a sootblower for cleaning internal heat exchanger surfaces by impingement of a jet of a cleaning medium, the nozzle block comprising:a nozzle block body defining a longitudinal axis, a hollow interior, a distal end, and a proximate end with the proximate end receiving the cleaning medium; a downstream nozzle positioned adjacent the distal end of the nozzle block body for discharging the cleaning medium, the downstream nozzle having an inlet end and an axis of discharge substantially perpendicular to the nozzle block body longitudinal axis, the nozzle block body hollow interior and the downstream nozzle cooperating such that the cleaning medium flowing in the direction of the longitudinal axis from the proximate end to the distal end through the nozzle block body interior does not flow substantially beyond the downstream nozzle inlet end; wherein the downstream nozzle axis of discharge defines an axis (Z) and wherein once the flow of the cleaning medium reaches the inlet end of the downstream nozzle, there is an absence of any cleaning medium flow component in the negative Z direction; and an upstream nozzle for discharging the cleaning medium positioned at a longitudinal position of the lance tube nozzle block displaced from the distal end and the downstream nozzle.
  • 31. The nozzle block of claim 30 wherein the cleaning medium is comprised at least in part of steam.
  • 32. The nozzle block of claim 30 adapted to be connected with a lance tube, the nozzle block and the lance tube having a cylindrical exterior surface with both the downstream nozzle and the upstream nozzle located within the cylindrical surface.
  • 33. A lance tube nozzle block for a sootblower for cleaning internal heat exchanger surfaces by impingement of a jet of a cleaning medium, the nozzle block comprising:a nozzle block body defining a longitudinal axis, a hollow interior, a distal end, a proximate end with the proximate end receiving the cleaning medium; a downstream nozzle positioned adjacent the distal end of the nozzle block body for discharging the cleaning medium, the downstream nozzle having an inlet end and an axis of discharge substantially perpendicular to the nozzle block body longitudinal axis, the nozzle block body hollow interior and the downstream nozzle cooperating such that the cleaning medium flowing in the direction of the longitudinal axis from the proximate end to the distal end through the nozzle block body interior does not flow substantially beyond the downstream nozzle inlet end; and an upstream nozzle for discharging the cleaning medium positioned at a displaced longitudinal position of the lance tube nozzle block from the distal end, wherein said upstream nozzle creates a stream of the cleaning medium directed in a direction which is diametrically opposite the direction of a stream of the cleaning medium created by the downstream nozzle and wherein the hollow interior defines a converging channel of smoothly decreasing cross-sectional area between the upstream nozzle and the downstream nozzle for directing the flow of the cleaning medium past the upstream nozzle to the downstream nozzle inlet end.
  • 34. The nozzle block of claim 33 wherein the downstream nozzle includes a first converging section near the downstream nozzle inlet end, a first diverging section joining the first converging section and terminating with a first outlet end, a first throat at the point where the first converging section and the first diverging section are joined, a first expansion zone between the first throat and the first outlet end; andthe upstream nozzle having a second inlet end and a second outlet end, wherein the cleaning medium enters the upstream nozzle through the second inlet end and exits the nozzle block through the second outlet end with a second axis of discharge substantially perpendicular to the longitudinal axis of the upstream nozzle block body, a second converging section near the second inlet end, a second diverging section joining the second converging section defining a second throat, and a second expansion zone between the second throat and the second outlet end.
  • 35. The nozzle block of claim 34 wherein the first throat defines a first diameter, the first expansion zone defines a first expansion length, and the second throat defines a second diameter, the second expansion zone defines a second expansion length, and wherein the ratio of the first expansion length to the first diameter is different than the ratio of the second expansion length to the second diameter.
  • 36. The nozzle block of claim 34 wherein the first throat defines a first diameter, the first expansion zone defines a first expansion length, and the second throat defines a second diameter, the second expansion zone defines a second expansion length, and wherein the ratio of the first expansion length to the first diameter is the same as the ratio of the second expansion length to the second diameter.
  • 37. The nozzle block of claim 33 wherein the nozzle block defines an exterior surface and at least one of the first outlet end and the second outlet end is substantially within the cylinder defined by the exterior surface of the nozzle block body.
  • 38. The nozzle block of claim 33 wherein the converging channel is defined at least in part by a contoured body disposed adjacent the downstream nozzle inlet end.
  • 39. The nozzle block of claim 38 wherein the contoured body defines a tip and the tip in part defines the downstream nozzle inlet end.
  • 40. The nozzle block of claim 38 wherein an airfoil body surrounds the upstream nozzle and defines a portion of the hollow interior of the nozzle block body.
  • 41. The nozzle block of claim 40 wherein the airfoil body has an upstream incline to direct the flow of the cleaning medium from the proximate end of the nozzle block body to the upstream nozzle second inlet end and a downstream incline to direct the cleaning medium toward the downstream nozzle past the upstream nozzle.
  • 42. The nozzle block of claim 33 wherein the cleaning medium is comprised at least in part of steam.
  • 43. The nozzle block of claim 33 wherein the nozzle block body hollow interior and the downstream nozzle define a distance (Y) measured along the nozzle block body longitudinal axis from the downstream nozzle axis of discharge to an inside surface of the hollow interior at the distal end and wherein the distance (Y) is not substantially greater than one-half the diameter of the downstream nozzle inlet end.
  • 44. The nozzle block of claim 43 wherein the flow of the cleaning medium in the direction of the longitudinal axis is assumed positive from the proximate end to the distal end and once the cleaning medium enters the downstream nozzle inlet end, there is an absence of flow of the cleaning medium in the negative direction.
  • 45. The nozzle block of claim 43 wherein the upstream nozzle defines a second axis of discharge which is tipped from perpendicular to the nozzle block body longitudinal axis toward the proximate end.
  • 46. The nozzle block of claim 45 wherein the second axis of discharge defines a curved line.
  • 47. The nozzle block of claim 45 wherein the second axis of discharge defines a straight line.
  • 48. The nozzle block of claim 33 wherein the nozzle block body has a substantially uniform wall thickness.
  • 49. The nozzle block of claim 33 wherein the downstream axis of discharge defines an axis (Z) and wherein once the flow of the cleaning medium reaches the inlet end of the downstream nozzle, there is an absence of any cleaning medium flow component in the negative Z direction.
  • 50. A lance tube nozzle block for a sootblower for cleaning internal heat exchanger surfaces by impingement of a jet of a compressible cleaning medium, the nozzle block comprising:a nozzle block body defining a longitudinal axis, a hollow interior, a distal end, and a proximate end with the proximate end receiving the cleaning medium; a downstream nozzle positioned adjacent the distal end of the nozzle block body for discharging the cleaning medium, the downstream nozzle having an inlet end and an axis of discharge substantially perpendicular to the nozzle block body longitudinal axis; an upstream nozzle for discharging the cleaning medium positioned at a displaced longitudinal position of the lance tube nozzle block from the distal end and the upstream nozzle; and an airfoil body integrally surrounding the upstream nozzle in communication with the hollow interior of the nozzle block body, and the airfoil body defining a surface of the hollow interior of the nozzle block body, such that the airfoil body provides a smooth flow for the cleaning medium from the upstream nozzle to the downstream nozzle.
  • 51. The nozzle block of claim 50 wherein the airfoil body has a sloping geometry having an upstream incline and a downstream incline, the upstream incline directing the flow of the cleaning medium from the proximate end of the nozzle block body to the upstream nozzle and the downstream incline directing the flow of cleaning medium past the upstream nozzle to the downstream nozzle.
  • 52. The nozzle block of claim 50 wherein the airfoil body reduces the presence of eddy current around a downstream surface of the upstream nozzle to thereby act to reduce irrecoverable hydraulic losses.
  • 53. The nozzle block of claim 50 wherein the upstream nozzle has a surface having a trapezoidal cross section.
  • 54. The nozzle block of claim 50 wherein the upstream nozzle defines an upstream nozzle inlet end and a an upstream nozzle discharge end with an upstream nozzle axis of discharge substantially perpendicular to the longitudinal axis of the nozzle block, the cleaning medium entering the hollow interior of the nozzle block body through the proximate end and exiting the nozzle block through the downstream nozzle and the upstream nozzle.
  • 55. The nozzle block of claim 50 the inlet end of the downstream nozzle is in communication with the hollow interior of the nozzle block body.
  • 56. The nozzle block of claim 50 wherein the nozzle block hollow interior defines a converging channel of decreasing cross section between the upstream nozzle and the downstream nozzle for directing the flow of the cleaning medium past the upstream nozzle to the inlet end of the downstream nozzle.
  • 57. The nozzle block of claim 56 wherein the converging channel is defined at least in part by a contoured body disposed adjacent the downstream nozzle and contacting the hollow interior of the nozzle block body.
  • 58. The nozzle block of claim 56 wherein the contoured body defines a tip which in part defines the inlet end of the downstream nozzle.
  • 59. The nozzle block of claim 50 wherein the upstream nozzle and the airfoil body are formed of an integral piece.
  • 60. The nozzle block of claim 50 wherein the nozzle block body and the downstream nozzle cooperating such that the flow of the cleaning medium flowing in the direction of the longitudinal axis from the proximate end to the distal end through the nozzle block body interior does not flow substantially beyond the downstream nozzle inlet end.
  • 61. The nozzle block of claim 50 wherein the flow of cleaning medium in the direction of the longitudinal axis is assumed positive from the proximate end to the distal end and once the cleaning medium enters the downstream nozzle inlet, there is an absence of the flow of the cleaning medium in the negative direction.
  • 62. The nozzle block of claim 50 wherein the downstream nozzle axis of discharge defines an axis (Z) and wherein once the flow of the cleaning medium reaches the inlet end of the downstream nozzle, there is an absence of any cleaning medium flow component in the negative Z direction.
  • 63. The nozzle block of claim 50 wherein the cleaning medium is comprised at least in part of steam.
  • 64. The nozzle block of claim 50 adapted to be connected with a lance tube, the nozzle block and the lance tube having a cylindrical exterior surface with both the downstream nozzle and the upstream nozzle located within the cylindrical surface.
CROSS REFERENCE TO RELATED APPLICATION

This specification claims priority to U.S. Provisional Patent Application No. 60/261,542, filed on Jan. 12, 2001, entitled “Sootblower Nozzle Assembly With an Improved Downstream Nozzle”.

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Entry
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Number Date Country
60/261542 Jan 2001 US