Abstract:
A spray nozzle, particularly well adapted for use in compressor spray cleaning systems, has a nozzle body with a right angle fluid delivery bore having a first passageway section extending longitudinally and at least one connected transverse nozzle bore section terminating in a reduced diameter spray bore at a sidewall of the nozzle body. A swirler is mounted in the nozzle bore section, and has a head section with a plurality of passageways formed between swirl vanes arranged about a periphery of the head section to pass fluid to the spray bore and an adjacent neck section of a reduced diameter. The neck forms an annulus between the neck and the nozzle body in fluid-passing contact with the first passageway section and head section to direct fluid from the first passageway through the head passageway for exit through the spray bore. The nozzle can be used in spray systems over a wide range of fluid delivery volumes and pressures.

Description:
The present invention relates to a nozzle construction, and particularly to a nozzle construction having significant utility in connection with directing cleaning fluids into the intakes of gas turbines to provide a thorough cleaning of the compressor and other elements thereof. 
     BACKGROUND OF THE INVENTION 
     U.S. Pat. No. 5,011,540 to the present inventor teaches the use of a series of nozzles arranged and positioned to generate a mist or fine droplet fog of a washing fluid around, for example, the periphery of the air intake of a gas turbine engine. The washing fluid is supplied to the nozzles under pressure, the nozzles converting the fluid flow into a fog, which is drawn through the turbine as it operates and contacts the vanes and blades of the turbine&#39;s compressor to attack and remove contaminants from the compressor surfaces. The nozzles are positioned to inject the fog into areas of relatively low-speed turbulent air, the fog being drawn into the turbine in a manner that creates a uniform dispersion of the fog and effective cleaning of the compressor surfaces. Different wash fluids may be injected, depending on the nature of the cleaning to be accomplished, and different fluids may be used during different phases of the cleaning process. 
     Depending on the specific application, a wide range of fluid pressures and droplet sizes that may be employed. In “on-line” washing, the turbine is fired and can be running at any load or speed conditions, so the compressor wash solutions must be injected with droplets sufficiently small that they do not cause any erosive or mechanical damage when they impinge at high velocity onto the stationary and rotating compressor airfoils. At the same time, however, the droplets must be sufficient size, mass and quantity to break through the airfoil surface boundary layer and provide comprehensive wetting to the surface deposits. In practice such droplets are typically in the size range of about 100-200μ, the recognized industry standard for chemical cleaning processes of this type. 
     “Off-line” or “off-crank” cleaning is performed by injecting cleaning solution into the compressor via a nozzle system while the turbine rotor is being turned at about 10 to 25 percent of its normal operating speed in order to disperse the cleaning fluid effectively throughout the compressor section. The rotor is physically turned by an electric motor or diesel powered starting device or, in the case of large gas turbine generators, by inducting the generator itself to turn the rotor. Since off-line cleaning has to date been designed as a short duration, high volume deluge wash procedure, their injection nozzle systems have tended to be cruder, with larger droplet sizes and higher flow rates. In some cases high pressure injection, up to about 2,000 PSIG have been employed, but in either case such nozzle systems are not suited to on-line washing because of the dangers of thermal shock, mechanical damage, and compressor blade erosion. 
     The common arrangement for compressor cleaning systems is therefore to have a separate arrangement of nozzles, and sometimes a separate wash skid, for on-line cleaning and off-line cleaning—thus increasing the cost of hardware and installation. 
     The present invention provides a spray nozzle that offers the opportunity, when operating in conjunction with a variable pressure fluid delivery system or wash skid, of being ideal for both on-line and off-line compressor washing. 
     For example, in on-line cleaning there is no advantage in injecting a specific volume of cleaning solution over a short period of just a few minutes, since a large percentage of the solution would be immediately wasted to the combustion system and, more importantly, the actual chemical contact time with the compressor deposits would be insufficient to ensure a good cleaning result. Instead the ideal is to inject the same or even a smaller volume of cleaning solution over a longer period—say 10 to 15 minutes or even more—by lowering system operating pressure to about 100 to 150 PSIG to reduce the nozzle flow rates. This simple procedure substantially reduces the wastage of cleaning fluid and substantially increases the all-important chemical contact time with the surface deposits on the compressor airfoils to produce a better cleaning result. 
     Likewise in the case of off-line cleaning the injection of the cleaning solution into the compressor does not actually require the cleaning fluid to be injected in a deluge process over a short period of time, as this procedure also results in the wastage of much of the costly cleaning chemical directly to the drains without it having done any useful work. Like on-line cleaning, good results from off-line cleaning also very much depend on allowing the chemical cleaning solution to remain in contact with the surface deposits for as long as possible during the actual injection of the cleaning solution (about 10 to 15 minutes or more) and during a soak period, typically 30 to 60 minutes, when the rotor is at rest. 
     Thus, a realistic fluid injection pressure of 100 to 150 PSIG is all that is required to deliver the cleaning solution to the compressor for off-line washing. However, a vital element of the off-line washing procedure is to ensure thorough post-wash rinse-out of the entire compressor, combustor and turbine section of the gas turbine with plain water is achieved; if loosened deposits containing corrosive elements, such as salt, etc. are left in the machine when it is fired up they can subsequently cause accelerated compressor and, more particularly, hot section corrosion. 
     To ensure effective post-wash rinsing it is therefore essential to ensure an adequate flow and velocity of rinsing water. The nozzle design of the present invention allows this to be easily achieved by simply increasing the nozzle injection pressure. The nozzle design enables the nozzle flow rate to be increased approximately four-fold between 100 and 900 PSIG for highly effective post-wash rinsing. 
     Conventional nozzle systems are typically ill equipped to operate satisfactorily across the range of pressures and flows needed to meet safety and practical requirements of both on- and off-line compressor cleaning. While nozzles are known that deliver a spray through a nozzle aperture located on the end wall of the nozzle as well as from a nozzle aperture located on the nozzle sidewall, neither configuration has heretofore been able to function over a range of operating pressures and droplet sizes with a consistent design, thus preventing real economies in manufacture and use to be realized. 
     Further, since the orientation of the spray nozzles is dependent upon the nature and configuration of the turbine and the compressor with which they are to be employed, as well as the intended primary target for the wash spray, it is of significant benefit to have a nozzle construction that may be easily adapted for a variety of turbine configurations. Nozzle constructions in which the outlet orifice is in a nozzle end wall are difficult to mount and orient properly and often require a large plurality of individual nozzles to provide the desired spray pattern, and current side spray nozzles of consistent design have also been unable to provide the needed variability in overall spray configurations. 
     Benefits of the nozzle construction of the present invention include the ability to accommodate a wide range of fluid pressure and droplet sizes, as well as the ability to incorporate a plurality of nozzle outlets in a unitary body. The present invention has a side-spray configuration, allowing great adaptability to a wide variety of use environments, and the individual nozzle outlets can each be of a different geometry to provide differing spay patterns, and can be differently oriented along and about the nozzle body to create the appropriate spay pattern for the turbine and compressor configuration with which the nozzle is to be employed. 
     In addition to use in spray cleaning operations, the nozzle of the present invention may have utility in other turbine-related applications, such as for the injection of fluid to increase mass flow, as well as in other non-turbine applications, wherever a fine droplet spray or fog is needed. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In accordance with the foregoing, a spray nozzle designed and constructed in accordance with the present invention comprises an elongated nozzle body with a fluid delivery bore located therein. The delivery bore is in the form of a right angle channel, having a longitudinally-extending main channel with an entranceway at one end of the nozzle and a transverse bore or channel terminating at a spray exit bore or aperture extending through a lateral side of the nozzle. A swirler head is mounted in the transverse bore. The swirler head creates a swirling turbulent flow for the fluid passing through and about the head, and in conjunction with the spray bore allows the flow existing through the spray bore to be in the form of a fine mist of appropriately sized fluid particles. The swirler head includes a reduced diameter neck portion about which the fluid is introduced, allowing the fluid full circumferential contact with and passage through and about the swirler. 
     The simplified construction of the nozzle, consisting essentially of an elongated body and mounted swirler, allows the nozzle to be manufactured and assembled efficiently, and permits appropriate adjustment of the associated parameters in accordance with specific use requirements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A fuller understanding of the present invention will be acquired upon consideration of the following detailed description of preferred but nonetheless illustrative embodiments of the invention, when considered in association with the annexed drawings, wherein: 
         FIGS. 1A ,  1 B and  1 C are diagrammatic representations of representative orientations for nozzles of the present invention in conjunction with gas turbine systems; 
         FIG. 2  is an exploded perspective view of an embodiment of the invention; 
         FIG. 3  is a perspective view of the embodiment of  FIG. 2  in which the spray aperture is visible; 
         FIG. 4  is a sectional view taken along line  4 - 4  of  FIG. 3 ; 
         FIG. 5  is an enlarged view of a swirler of the inventive construction; 
         FIG. 6  is a sectional view, similarly oriented to that of  FIG. 4 , presenting an alternative embodiment of the invention; 
         FIG. 7  is a sectional view, similarly oriented to that of  FIG. 4 , presenting a further embodiment of the invention; and 
         FIG. 8  is a chart illustrating flow rate and droplet size a various fluid pressures for a series of nozzles constructed in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1A through 1C  depict illustrative orientations of spray nozzles of the present invention, presented as diagrammatic half-section views of the inlet side of representative turbine configurations with which the invention may be employed. It is to be appreciated that a plurality of nozzles may be arranged in similar fashion about the periphery of the housings to achieve the desired full spray coverage. 
       FIG. 1A  depicts a pair of nozzle assemblies  10 , one of which is mounted on plenum wall  12  and one mounted on cone wall  14  of a radial inward compressor for an industrial gas turbine. As known in the art, the nozzles are positioned to generate spray fogs in areas of low-speed, relatively turbulent air to facilitate a uniform intake of the spray into the compressor, passing through and cleaning, for example, bell-mouth struts  16  and inlet guide vanes  18 , as well as the compressor blades (not shown). 
       FIG. 1B  depicts the alternative positioning of nozzle assemblies  10  in an industrial type axial flow inlet gas turbine of an aero derivative construction. Nozzle  10 ′ is shown in a typical position for on-line cleaning operation, while nozzle  10 ″ is in a position appropriate for off-line cleaning operation. Once again, the positioning of the nozzle in a region of relatively low velocity high turbulence flow facilitates full distribution of the spray. 
       FIG. 1C  likewise presents the positioning of the nozzles  10  in conjunction with a turbofan jet engine for aeronautical use. Nozzle  10 A is mounted to engine casing  20 . Its spray is directed for cleaning of main fan  22  and thereafter core engine compressor  24 . Second spray nozzle assembly  10 B is mounted to the engine core  26  and further provides a dedicated spray for the core engine compressor  24 . 
     As the foregoing illustrates, nozzle systems of the present invention may be employed in a variety of situations. The specific uses and positioning of the nozzles as depicted are not intended to be in any way limiting. 
     Referring next to  FIGS. 2 through 4 , a first embodiment of nozzle  10  includes nozzle body  28 , formed of a solid rod of an appropriate material, typically stainless steel. The nozzle body  28  may be provided with an integral threaded mounting portion  30 , allowing the body to be threadedly-engaged with an appropriate fluid delivery pipe  32 . Typically, the delivery pipe  32  may incorporate fittings, flanges, collars and/or the like to allow an integrated nozzle system, including nozzle  10 , to be mounted to as appropriate, such as on a plenum wall, engine casing, or the like, as exemplified in  FIGS. 1A-C . As further suggested by  FIGS. 1A through 1C , fluid delivery pipe  32  may also be of an angled construction to facilitate proper orientation of the nozzle and its emitted spray. 
     Nozzle body  28  is provided with a central longitudinal bore  34  which extends from the threaded connector end of the body. The bore terminates adjacent the distal end of the body, and intersects at its distal end with a transverse bore  36  through the sidewall of the nozzle body in which swirler head  38  is mounted. Advantageously, both longitudinal bore  34  and transverse bore  36  are cylindrical, allowing them to be efficiently and economically machined. The transverse bore  36  is provided with a relatively small diameter spray outlet bore  40 , as known in the art, at its bottom face which provides an outlet for the washing fluid introduced into central bore  34  by fluid delivery pipe  32  and which subsequently passes through transverse bore  36  and the mounted swirler. 
     Swirler body  38  provides the means by which the cleaning fluid is transferred from the central bore  34  through the transverse bore  36  and spray outlet  40 . As detailed in  FIG. 5 , it comprises a base  42  dimensioned to fit with a high degree of precision within transverse bore  36  and to support the swirler in position therein. Base  42  supports a neck  44  of reduced diameter which at its distal end supports a head having a plurality of angled vanes  46 , forming a plurality of angled fluid flow channels therebetween. A transverse bore  48  extends through the neck. As may be seen in  FIG. 4 , the swirler  38  is so oriented in the nozzle body and transverse bore  36  such that the central annular portion of neck  44  is aligned with main bore  34 , with transverse neck bore  48  facilitating the flow of washing fluid from main bore  34  around the full periphery of the neck. The flow channels between angled vanes  46  impart an angular velocity and turbulence to the fluid, which then passes into the end chamber portion  50  of transverse bore  36 . The swirling, turbulent flow of fluid is atomized and is ejected through the spray outlet  40  as a fog of small size droplets. 
     The two-piece construction of the nozzle head as depicted in  FIG. 4  allows for both economical and high precision construction and installation to be performed. With the swirler  38  inserted in the transverse bore, it may be TIG-welded into place, forming a rigid integral unit. Alternatively, the base  42  of the swirler and the corresponding portion of bore  36  may be complementarily threaded to allow the swirler to be mounted in the bore. In a similar manner, nozzle body  28  may be TIG-welded at  54  to the threaded connector portion  30 , the welds being subsequently machined as known in the art to yield a construction that has the appearance of a single unitary element capable of withstanding the rigors of the environment in which it is placed. 
     Advantageously, transverse bore  36  may be bored or machined with an arcuate transition portion  52  between its cylindrical sidewall and planar bottom face. The commencement of the arcuate section on the bore sidewall can provide a stop for the swirler  38 , allowing it to be inserted against the stop with the main axis of its transverse bore  48  aligned with that of central bore  34 . 
       FIG. 6  depicts an alternative embodiment of the invention in which two spray outlets  40  are provided, allowing the resulting fluid spray pattern to encompass a greater area. In a manner analogous to the construction of the first embodiment, the nozzle body  28  incorporates a central bore  34  that intersects with a pair of spaced transverse bores  36 . While the bores  36  may be aligned parallel to each other, as depicted in the Figure, it is to be appreciated that they can be radially offset with respect to each other, whereby the respective spray outlets  40  direct the exiting spray in differing radial directions. Each of the transverse bores  36  carries a respective swirler  38 , the transverse bores  48  of which are aligned with central bore  34 , providing a continuous pathway for the fluid to and around both swirlers for delivery by the respective spray outlets  40 . It is to be appreciated that additional transverse bores, swirlers and spray outlets can likewise be provided. 
     In addition to constructions in which a transverse bore  36  for a swirler extends in a radial direction, perpendicular to the main axis of the nozzle body and main bore  34 , it is also possible to machine a transverse bore  36  at an angle other than perpendicular to the axis of bore  34 , providing further control over the ultimate direction and configuration of the produced spray in accordance with requirements of the installation, as depicted in  FIG. 7 . While the angle between the main axes of the central bore  34  and the transverse bore  36  can be at any angle greater than 0 and less than 180 degrees with respect to the main axis of the central bore  34 , the figure shows the transverse bore  36  at an angle of about 45 degrees. The portion of the body sidewall through which the spray outlet bore  40  extends may be chamfered at  56  to be perpendicular to the axis of the outlet bore. The distal end of the swirler&#39;s base is likewise machined on a bias to be flush with the nozzle body. 
     In a typical application, the swirler  38  may be preferably provided with four or seven vanes and channels at a 45 degree angle to the main longitudinal axis of the head. Typical dimensions for the channels in a seven vane configuration are approximately 1.45 mm width×0.9 mm depth. The diameter of the swirler, and thus the transverse bore in which it is mounted, may be on the order of 6.35 mm with the neck being 4.5 mm in length and supporting a transverse bore of 2.7 mm diameter. 
     A nozzle body  28  may be, for example, on the order of 40 mm long with a main diameter of 13.8 mm. Spray outlet bore  40  may be on the order of 0.6 mm diameter, but it is to be appreciated that the specific size thereof may be adjusted as appropriate for the spray pattern desired. Typically outlet bore diameters range from 0.50 to 3.50 mm, with four slot swirlers being preferable at smaller diameter outlet bores. Seven slot swirlers have been found to be more appropriate with outlet bore of about 1.5 mm and above. For a given slot configuration outlet droplet size decreases and flow rate increases as fluid pressure is increased. The fewer the number of slots the lesser the fluid flow rate. With a typical swirled diameter of 6.35 mm seven slots represent a practical maximum for efficient machining. 
       FIG. 8  depicts flow rates and observed droplet sizes for a single bore nozzle of the present invention with spray bore diameters of from 0.50 to 3.50 mm. Consistent with observed results, 4 slot swirlers are employed with smaller spray bore diameter systems. The chart illustrates the wide range of droplet sizes and flow rates that can be accommodated with the same basic construction. Pressures are expressed in BARG (bar gauge); 1 bar=100 kPa (kilopascals). 
     The side spray nozzle of the invention allows a multiplicity of sprays to be accommodated in a single spray body of relatively small diameter, allowing a reduction in the physical number of nozzles needed to achieve the desired comprehensive wetting effect. Reduction of the number of nozzles equates to a lower capital cost and cost of installation. 
     Increased overall flow rates can be accomplished at a desired droplet size by increasing the number of nozzle outlets, rather than by enlarging the orifice size as would be required in a single outlet spray nozzle, resulting in an increased droplet size. The flow range of a nozzle of the invention can be varied within a reasonable range without substantial droplet size change simply by changing the pressure, allowing the same nozzle system to be used for both on- and off-line cleaning. 
     Those skilled in the art will appreciate that modifications and adaptations of the foregoing may be accomplished without departing from the spirit and scope of the invention, which is to be determined with consideration of the foregoing and the annexed claims.