Patent Grant
8028936
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.
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'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.
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.
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:
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
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
The two-piece construction of the nozzle head as depicted in
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.
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
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.
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.
| Number | Name | Date | Kind |
|---|---|---|---|
| 1665744 | Landberg | Apr 1928 | A |
| 2358177 | Madison | Sep 1944 | A |
| 2458876 | Rehn | Jan 1949 | A |
| 2984421 | Hession, Jr. | May 1961 | A |
| 3762652 | Huling | Oct 1973 | A |
| 7611080 | Peterson et al. | Nov 2009 | B2 |
| Number | Date | Country | |
|---|---|---|---|
| 20100206966 A1 | Aug 2010 | US |
