Abstract:
Blockages of turbomachine cooling circuit cooling holes resulting from coating processes can be removed by introducing a cleaning agent into the cooling circuit. The cooling circuit can be connected to a cleaning agent supply under pressure, adding force on the blockage to chemical action by the cleaning agent. The cleaning agent is chemically reactive with the coating material and substantially chemically non-reactive with the underlying material of the cooling circuit and other parts of the turbomachine. A neutralization agent can also be introduced to reduce toxicity and/or action of the cleaning agent. A turbomachine cooling hole cleaning method includes introducing a cleaning agent into a cooling circuit of a turbomachine part, pressurizing the cleaning agent in the cooling circuit until a first defined condition is met, and introducing a neutralization agent to the turbomachine part while the cleaning agent is applied to the cooling circuit.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional application of co-pending U.S. patent application Ser. No. 13/745,136, filed Jan. 18, 2013, which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The disclosure relates generally to rotating machinery or turbomachinery, such as gas and/or steam turbines, compressors, and/or machines including such turbines and/or compressors. More particularly, the disclosure relates to the removal of material deposited over and/or in cooling holes of a part, such as a combustor jacket. 
     During manufacture, repair, and/or rehabilitation of gas turbines, coatings are applied to some parts. For example, in turbomachinery, particularly in gas turbines, a thermal barrier coating (TBC) can be applied to protect underlying material of the parts to which the TBC is applied from heat. A TBC can include a ceramic layer, which can include a variety of ceramic materials, the most commonly used of which is currently yttria-stabilized zirconia (YSZ). In addition, a typical TBC can include a metallic bonding layer applied to the underlying material of the part, and a thermally grown oxide layer on the metallic bonding layer, to which the ceramic layer is applied. 
     When such a coated turbomachine part includes cooling holes, the cooling holes can become partially or completely occluded, and the coating(s) can also form deposits on interior portions of passages leading to the cooling holes. Typically, portions of the part on which the coating is not desired are covered with a masking agent, the coating is applied to the part, and overspray is removed by mechanical grinding. The masking agent can then be removed, such as by abrasion and/or burning or other chemical means. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Embodiments of the invention disclosed herein may take the form of a turbomachine cooling hole cleaning apparatus having a supply of a fluid that includes a cleaning agent. A pressurization apparatus can be configured for fluid communication with the cleaning agent supply and with a cooling circuit of a turbomachine part, the cooling circuit including at least one cooling passage with a respective cooling hole. The pressurization apparatus can further be configured to introduce cleaning agent into the cooling circuit from the supply into the cooling circuit. 
     Embodiments of the invention may also take the form of a turbomachine cooling hole cleaning method including introducing a cleaning agent into a cooling circuit of a turbomachine part, pressurizing cleaning agent in the cooling circuit until a first defined condition is met, and introducing a neutralization agent to the turbomachine part while the cleaning agent is applied to the cooling circuit. 
     Embodiments of the invention may further take the form of a turbomachine cooling hole cleaning apparatus including a conduit configured for connection to and fluid communication with a cooling circuit of a turbomachine part that includes at least one cooling passage with a respective cooling hole. A supply of a cleaning agent can be configured for fluid communication with the conduit, and a pressurization apparatus can be configured for fluid communication with at least the conduit and the supply. In addition, the pressurization apparatus can be configured to send cleaning agent from the supply into the conduit under pressure. 
     Other aspects of the invention provide apparatus and/or methods of using and/or generating each, which can include and/or implement some or all of the actions described herein. The illustrative aspects of the invention are designed to solve one or more of the problems herein described and/or one or more other problems not discussed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features of the disclosure will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings that depict various aspects of the invention. 
         FIG. 1  shows a schematic diagram of an example of a part and apparatus with which embodiments of the invention disclosed herein may be employed. 
         FIG. 2  shows a schematic cross sectional view of a coated part being cleaned according to embodiments of the invention disclosed herein. 
         FIG. 3  shows a schematic diagram of an example of a part and apparatus with which embodiments of the invention disclosed herein may be employed. 
         FIG. 4  is a schematic flow diagram of an example of a cooling hole cleaning method according to embodiments of the invention disclosed herein. 
     
    
    
     It is noted that the drawings may not be to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings. 
     The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the invention disclosed herein can take advantage of an existing fluid distribution system in a turbomachine part to remove blockages of cooling holes and deposits from cooling passages resulting from application of a coating to the part, such as a thermal barrier coating (TBC). As used herein, “cooling holes” can include any opening of a cooling circuit of a turbomachine part through which fluid can leak, and “cooling passages” can include and line, conduit, or other passage that is part of the cooling circuit. As discussed above, a typical TBC can include a metallic bonding layer applied to the part, a thermally grown oxide layer derived from the metallic bonding layer, and a ceramic or other suitable material applied to the oxide layer. As also discussed above, a widely used ceramic material can include yttria-stabilized zirconia (YSZ), though other materials have been used in the past, can and are used now, and may be used in the future. A supply of cleaning agent can be substituted for a supply of cooling fluid in a cooling circuit in which the deposits and blockages occur. The cleaning agent can include a compound that is chemically reactive with the coating. For example, where YSZ is employed, the cleaning agent can include an acid, which can be used to remove metallic bonding layer material(s), and a base, which can be used to remove additional TBC material(s). By introducing cleaning agent, particularly under pressure, into the cooling circuit, the cleaning agent can act chemically and physically to remove deposits and blockages, and, particularly when a neutralization agent is introduced, such as by spraying and/or immersion, application of a masking agent may not even be required, saving time, material, and cost. 
     With reference to  FIG. 1 , a turbomachine part  10  can include at least one cooling hole  12  that can become blocked. With additional reference to  FIG. 2 , cooling hole(s)  12  can be part of a cooling circuit  14  of turbomachine part  10 . During normal operation, cooling circuit  14  can be configured to convey fluid, such as a cooling fluid, from a supply  16  to an internal passage  18  on an interior of a wall  20  of turbomachine part  10 . While fluid supply  16  is depicted in such a way as might be interpreted as a tank or the like, it should be understood that fluid supply  16  can take the form of a line to a compressor stage or any other source of fluid in a turbomachine in which turbomachine part  10  would ordinarily be installed and/or to which cooling circuit  14  might be connected. A plurality of cooling passages  22  can further convey fluid from internal passage  18  to an exterior of turbomachine part  10  via cooling hole(s)  12  as part of cooling circuit  14 . However, a coating  24  applied to turbomachine part  10  can result in blockage  26  of a cooling hole  12  or multiple holes  12 , as well as narrowing cooling passage(s)  22  with deposit(s)  28  along a wall of cooling passage(s)  22 . 
     Referring again to  FIG. 1 , as well as  FIG. 2 , noting that not all reference numerals used herein are necessarily shown in both  FIGS. 1 and 2 , embodiments can introduce a cleaning agent into cooling circuit  14 . For example, a conduit  110  can be connected to cooling circuit  14  and to a cleaning agent supply  120 , such as a reservoir of cleaning agent. Cleaning agent can then be forced into cooling circuit  14  using a pressurization apparatus  130 , such as a pump. As pressurized cleaning agent enters cooling circuit  14 , it can enter internal passage  18  and cooling passage(s)  22 . Cleaning agent can then act on blockage(s)  26  chemically and physically as a result of pressure exerted on blockage(s)  26 . In addition, cleaning agent can act on deposit(s)  28 , primarily chemically, but also physically as a result of erosion as cleaning agent passes deposit(s)  28 . Cleaning agent can exit cooling circuit  14  through hole(s)  12  and/or other openings, so embodiments can include a catchment  140  to capture exiting cleaning agent. Catchment  140  can include a drain  142 , which can divert captured cleaning agent to a container or other destination for disposal and/or reuse. In embodiments, neutralization agent can be introduced into cooling circuit  14  to reduce toxicity and/or hostile action of any cleaning agent remaining in cooling circuit  14 . For example, a neutralization agent supply  122  can be connected to conduit  110  and/or pressurization apparatus  130  so that neutralization agent can be fed into cooling circuit  14 . To avoid accidental removal of coating  24  from areas in which it is desired, a masking agent  29  ( FIG. 2 ), such as a coating, can be applied before cleaning agent is supplied to cooling circuit  14  so that cleaning agent escaping cooling circuit  14 , such as through cooling hole(s)  12 , does not react with coating  24  that is covered by masking agent  29 . 
     With reference to  FIG. 3 , embodiments of the invention disclosed herein can employ a different approach to avoiding accidental removal of coating  24  that can avoid the use of masking agents entirely. More specifically, neutralization agent supply  122  can be placed in a tank  124  or the like into which turbomachine part  10  can be immersed. With turbomachine part  10  so immersed, cleaning agent can be supplied to cooling circuit  14 , and any cleaning agent that escapes through cleaning holes  12  is neutralized as it escapes into neutralization agent supply  122 . In embodiments, rather than immersing turbomachine part  10 , neutralization agent can be sprayed or otherwise applied to turbomachine part  10  as cleaning agent is supplied to cooling circuit  14 . For example, as seen in  FIG. 1 , one or more spray heads  126  could be connected to neutralization agent supply  122  via conduit(s) or line(s)  128  so that neutralization agent can be sprayed onto turbomachine part  10 , particularly during supply of cleaning agent to cooling circuit  14 . 
     An example of a method  200  of cleaning cooling holes and/or passages of a turbomachine part according to embodiments is shown in  FIG. 4 . In embodiments, a masking agent can be applied (block  202 ) prior to cleaning to protect coating in areas in which the coating is desired. Cleaning can begin by introducing cleaning agent to turbomachine part (block  210 ), such as by using a pressurized feed (block  212 ) of cleaning agent from a supply, through a conduit, and into cooling circuit  14 . Using a pressurized feed can include, for example, running a pump connected to the cleaning agent supply and to the conduit. The cleaning agent can be maintained in the cooling circuit until a defined condition has been met (block  214 ), such as an elapsed time, until all blockages and/or deposits are removed, or until some other condition has been met as may be suitable and/or desired. Embodiments can also include introducing a neutralization agent (block  220 ) to protect coating(s) in areas in which the coating(s) is wanted to reduce toxicity of the cleaning agent, and/or to reduce toxicity and/or action of cleaning agent remaining in and/or escaping from the cooling circuit. Neutralization agent can be introduced, for example, from a neutralization agent supply using a pressurized feed (block  222 ), such as by using the same pressurized feed used to introduce cleaning agent into the cooling circuit. As with cleaning agent, neutralization agent can be maintained in the cooling circuit until a defined condition is met (block  224 ), such as elapsed time, a chemical property of fluid exiting the cooling system reaching a defined value, and/or another condition as may be desired and/or appropriate. Rather than sending neutralization agent through the cooling circuit, embodiments can apply neutralization agent to the part being cleaned (block  226 ), such as by spraying neutralization agent onto the part and/or by immersing the part in neutralization agent. In addition, embodiments can include drying and/or removing cleaning and/or neutralization agent from the part (block  230 ). 
     Using embodiments of the invention, blockages and/or deposits in a cooling circuit of a turbomachine part can be removed more quickly and effectively by virtue of the combined chemical and physical action of cleaning agent fed into the cooling circuit. In addition, the use of neutralization agent, whether by feeding through the cooling circuit, external application by spraying, and/or by immersion, can reduce risk of removing coating in areas where the coating is desired, as well as reduce action/toxicity of the cleaning agent as it escapes the turbomachine part. A single application of masking can be used until blockage and deposit removal is complete, which can also save time, cost, and effort. Further, it may be easier to determine when a cooling hole has been cleared, since fluid will begin to exit through the cooling hole when the blockage has been breached and/or removed. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.