Like reference characters denote like elements throughout the drawings.
The present invention provides a single nozzle assembly that may be used for both offline and online washing of turbines, and that may be installed in locations presently used for offline washing nozzles.
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Nozzle assembly 48 has a nozzle body 50 with two liquid feed lines 52, 54 housed within the nozzle body 50. The two feed lines 52, 54 are each connected at one end 56, 58 to one outlet 60, 62, respectively, of a three way valve 64. A liquid feed line 66 is connected between the inlet 68 of valve 64 and a pump 70, for example a variable speed pump, for pumping wash liquid. Pump 70 receives liquid from a liquid source that is not shown and well known to those skilled in the art. Valve 64 is therefore structured to route liquid to either feed line 52 or feed line 54, but not both feed lines simultaneously.
The pump 70 is capable of supplying cleaning fluid at a high pressure range, with an example of the range of pressures being at least about 10 bar to about 140 bar, with a more preferable range being about 40 bar to about 140 bar, and even more preferably about 60 bar to about 140 bar. This supply pressure, in conjunction with the nozzle design described herein, facilitates a controlled atomization that enables the cleaning liquid to effectively travel to the fouled compressor blade. This supply pressure further causes the cleaning liquid to scrub the surface without removing base material or coating. Additionally, as explained below, the ability of the pump 70 to supply cleaning liquid at two or more pressure levels within a range of pressures provides a simplified means of switching between offline and online cleaning, as explained below.
The pump 70 can comprise a single pump 70 (if the pump unit is appropriately engineered for that service), one variable speed pump 70 (where the speed is governed by frequency and where the appropriate frequency is set by a frequency controller) or multiple parallel pumps 70, for example, typically five pumps in certain embodiments, each one with different flow capacities. By running one, two or more pumps in different combinations a very large range of pump capacities is accomplished.
The pressurized water emanating from the pump 70 is fed to a supply line 66. The supply line acts as a distributor of the high pressure water to different users such as an evaporative cooling system, a wash system, a compressor intercooling system and a combustor flame cooling system. The pump 70 may be a displacement type pump driven by a frequency controlled electric AC motor, where the frequency governs the pump speed. Alternatively, the pump 70 may include a motor such as a DC motor, where the motor current governs the pump speed. Other suitable pumps 70 are well known to those skilled in the art.
In addition, for washing purposes the use of heated water and chemicals (e.g., for use as washing detergents or as compressor corrosion inhibitors at completion of an operating period) can be advantageous. Therefore, the pump 70 can further include tanks and heaters (i.e., for providing heated water) as well as a chemical injection unit for injecting chemicals into the water.
The pump 70 can be connected to a water collection unit and a water processing unit (i.e., capable of purifying water), since waste water emanates from the gas turbine engine during washing and/or power augmentation. The water processing unit can comprise particle separation filters, de-ionization filters, and/or osmotic filters. For example, the waste water can be in the form of water vapor through the stack or may be produced in a condensed form, where in the case of off-line washing, wash water will flood out from the gas turbine's engine exhaust. This waste water contains any released fouling material as well as oils, fats and metal ions coming from the gas turbine engine itself. This water is typically hazardous and preferably must be collected and treated. Water may also show up in the inlet air duct when evaporative spray cooling is practiced. This water can be collected by the water collection unit and treated in the water processing unit. Alternatively, the water processing unit can also process raw water from a water source (not shown in the Figs.). The treated waste water can be recycled and re-used for washing, thereby providing a closed loop system with no water emissions. Further, the re-used water reduces the total water consumption.
The water processing unit may in some examples purifies the water to “de-mineralized” water quality so that the water is suitable for injection into the gas turbine's air mass path where the total dissolved solids ranges, in certain embodiments, from about 1-5 ppm. Suitable water purifier systems are known to those skilled in the art. Alternatively, the water may be purified to a “deionized” quality.
Pump 70 may in some examples controlled by a control unit. The control unit can be controlled from a control room or from a panel by the pump unit, as examples. The control unit comprises manual controls as well as programmable controls that enable operation of the pump unit via a signal feed. The control unit includes a storage means, for example, a random access memory (RAM) and/or a non-volatile memory such as read-only memory (ROM). One of ordinary skill in the art readily understands that a storage means can include various types of physical devices for temporary and/or persistent storage of data including, but not limited to, solid state, magnetic, optical and combination devices. For example, the storage means may be implemented using one or more physical devices such as DRAM, PROMS, EPROMS, EEPROMS, flash memory, and the like. The storage means can further comprise a computer program product including software code portions for performing the method steps in accordance with embodiments of the invention when the computer program product is run on the computer device, for example, controlling an opening degree of a valve in order to, in turn, control a water flow rate being supplied to at least one nozzle and performing the computational fluid dynamics analysis transfer scheduling to form the control model.
Additionally the supply line 66 and all the conduits can comprise a hydraulic type high pressure flex hose, thus simplifying installation. Alternatively a fixed pipe may be installed. The valve 64 can be opened or closed from the control room or other remote location(s). Alternatively, the valves may be manually opened or closed.
The control unit can also be used to implement computational fluid dynamic transfer analysis (CFD). CFD allows embodiments of the present invention to predict (i.e., form a model) the amount of water needed to be injected into the gas turbine engine to fully saturate or oversaturate the air. CFD provides for a computational model representing the system in accordance with embodiments of the present invention. Subsequently, the dynamics of the fluid flow through the system can be analyzed and predicted in light of one or more of the defined parameters including, but not limited to, the ambient weather conditions and specific parameters pertaining to the gas turbine (i.e., turbine geometry and the velocity field of air movement) and load-limiting design aspects of the turbine (i.e., compressor blades, engine casing, combustor components and hot gas path working elements). CFD provides a control model that is interpreted and implemented by a programmed logic controller (PLC) for adjusting the level of water injection. The defined parameters or boundaries can be input into the system according to embodiments of the present invention either manually or automatically by the use of various sensors and/or weather monitoring units. CFD provides simulated fluid flow and thus, a predicted gas turbine performance level, which corresponds to the air mass flow through the turbine. As a result of the generated model, embodiments of the present invention can adjust the level of water injected on a continual basis or intermittent basis so that the power output of the gas turbine is optimized. The basic CFD process comprises, in one exemplary embodiment, defining the geometry of the gas turbine; determining the volume occupied by the fluid (e.g., water vapor) where the volume is divided into discrete cells (where the totality of the cells form a mesh); defining the boundary conditions such as the particular properties of the fluid utilized (i.e., for those processes that undergo substantially constant changes regarding the defined boundaries, the initial boundaries are typically defined); employing algorithms and equations (i.e., computer software or a computer loadable product loadable onto a digital computing device) for calculating predicted results; interpreting the predicting results to form a model.
If the valve 64 is not controlled by the control unit, then valve 64 may be switched by direct or remote manipulation of the valve 70, or by a pressure switch coupled to feed line 66. Example pressure switches are produced by Norgren or Stahl and open a circuit to activate a valve when a threshold pressure is detected. The pressure switch may be an integral part of the valve 64, or alternatively may be a separate component. The pressure switch is structured so that, when liquid pressure in feed line 66 is lower than a predefined pressure, the valve 64 is opened to feed liquid into the offline feed line 52. When liquid pressure is raised beyond a predefined pressure, the valve is switched so that feed line 52 is closed while the online feed line 54 receives the liquid. The pressure switch may be structured so that online washing is selected when the pressure is set to a level that is at any desired level between about 0.1 to about 0.9 times the maximum operating pressure, and which is more preferably between about 0.5 and about 0.9 times the maximum operating pressure. Switching of the valve 64 is thereby entirely regulated by switching the pump 70 to supply the liquid within the line 66 at a pressure level that is appropriate for the type of cleaning to be performed. This feature simplifies the cost for the wash system and simplifies maintenance.
As another alternative, similar supply pressures may be supplied for online and offline washing, and switching of the valve 64 may be accomplished independently of the pressure supplied by the pump 70. For example, the valve 64 can be actuated by a solenoid system that may be actuated by the above-described control unit.
The other end of feed lines 52, 54 are connected to nozzles 72, 74, 76. Offline washing nozzle 72 is connected to the end of the feed line 52. Likewise, online washing nozzles 74, 76 are connected to the end of the feed line 54. Each of the nozzles 72, 74, 76 define an opening that is structured to atomize the emanating liquid and to shape and inject the spray for achieving the best wash effect.
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The two nozzles 74, 76 have similar spray characteristics, with each generating a spray pattern of a flat fan shape as a result of their elongated shape. A flat fan spray is characterized by having a widthwise droplet distribution and a thicknesswise droplet distribution where the widthwise distribution is greater than the thickness wise distribution. The sprays generated by the openings 82, 84 has widthwise spray distributions coinciding with the longest axis of these openings, which are substantially parallel to the direction of the air flow.
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Washing may be conducted manually, or alternatively may be performed automatically by configuring the pump 70 so that it may be controlled by a programmable control device such as a microprocessor. The microprocessor may be programmed to conduct online washing at regular intervals and for a desired duration at each time interval during operation of the turbine 10, and to conduct offline washing at times when it is known that the turbine 10 will be shut down.
The present invention therefore provides a single nozzle that may be used for both online and offline cleaning of turbine. The nozzle may be installed within presently existing nozzle openings in the inlet air duct for turbines that are typically used for offline cleaning nozzles. The online cleaning nozzle tips direct a pair of fan-shaped cleaning fluid spray patterns along intersecting paths that are substantially perpendicular to the direction of air flow within the inlet air duct, and which have the longest dimension of the fan shape substantially parallel to the direction of air flow. This spray pattern maximizes the mass of cleaning fluid within a given cross-sectional area of the inlet air duct, thereby maximizing the momentum of the cleaning fluid towards the core of the air flow. The invention further provides a means for directing the cleaning fluid towards either the offline cleaning nozzle or the online cleaning nozzle based on the pressure at which the cleaning fluid is delivered. Selection of the appropriate pressure for a desired type of cleaning automatically delivers the cleaning fluid to the appropriate nozzle for the type of cleaning. Cleaning may, if desired, be actuated automatically by a microprocessor operatively connected to the pump for the cleaning fluid.
A variety of modifications to the embodiments described will be apparent to those skilled in the art from the disclosure provided herein. Thus, the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention.