On-wing combustor cleaning using direct insertion nozzle, wash agent, and procedure

A cleaning method for a combustor comprises positioning a spray portion of a nozzle through an igniter plug boss and spraying an acid solution inside the combustion chamber. The acid solution impinges the inner liner and the outer liner, dissolving contaminant deposits inside the effusion holes. The nozzle can have a second spray portion outside the combustion chamber to provide acid solution to the radially outward surface of the outer liner. After cleaning, distilled water is sprayed through the nozzle to remove the acid solution residue from the combustor. The used acid solution and distilled water can be collected, filtered and pumped through the nozzle to provide a recirculating cleaning/rinsing system.

BACKGROUND OF THE INVENTION

The present invention generally relates to methods and apparatus for cleaning components, more particularly, to methods and apparatus for cleaning gas turbine combustors.

A combustor is an important component of a gas turbine engine. Combustors comprise a combustion chamber defined by one or more combustor liners and a combustor dome. One of the more common combustor configuration types used in gas turbine engines, such as auxiliary power units (APU), is an annular combustor. An inner liner, an outer liner and a dome define the combustion chamber of an annular combustor. A mixture of fuel and air is introduced into the combustion chamber where it is ignited to produce combustion gases for a downstream turbine.

Because combustors are exposed to the temperatures generated by hot combustion gases (commonly in excess of 3500° F.) and the materials used in combustor construction are limited to about 1700-1800° F., cooling must be provided to the combustor components. A widely used technique for protecting combustor liners from hot combustion gases involves covering the combustor liners with a matrix of small holes, usually about 0.015 to 0.030 inches in diameter (effusion holes). A supply of cooling air is passed through the effusion holes to cool the liners and to add airflow to the combustion gases.

During the normal operation of the gas turbine engine, environmental contaminants can accumulate on the surfaces of the combustor, reducing engine efficiency. Additionally, contaminants can gather in the effusion cooling holes, the subsequent effusion hole plugging restricts airflow into the combustor, reducing the lean blowout margin until the gas turbine engine has little or no margin, resulting in uncommanded shutdowns of the gas turbine engine. Contaminant deposits in the effusion holes can also reduce liner cooling efficiency. Methods for removing contaminant deposits from engine components have been described.

Solid particle abrasives comprising nutshells, coke, molybdenum and/or graphite particles have been used to clean components. In these methods, the particles impinge on the surfaces of the component to dislodge deposit buildup. These techniques have been useful in removing deposits in some applications. Unfortunately, the abrasive particles can damage the base alloy and may become lodged in cracks or effusion holes during the cleaning process. Additionally, some engine components include internal passageways, such as effusion holes, which may not be sufficiently cleaned using these methods.

A component cleaning process that does not require the use of abrasive particles is disclosed in U.S. Patent Application No. 2002/0103093. In the described method, an engine component is immersed in an acid solution bath. The bath is agitated to aid in component cleaning. Although this method may remove contaminant buildup from effusion holes, it requires the component to be removed from the engine and immersed in the solution. For some applications, component removal is a time consuming and costly process.

Another cleaning process is disclosed in Japanese Patent Publication No. 2001214755. In the disclosed method, a nozzle is mounted to the combustor plenum and used to spray a cleaning fluid onto the outer surface of a combustor liner. Although this method may be useful for cleaning some combustors, it may not be suitable for cleaning all combustor configuration types. For example, the described method may not provide sufficient cleaning to the inner liner of an annular combustor because the cleaning fluid may not adequately contact the surfaces of the inner liner.

As can be seen, there is a need for improved component cleaning methods. Further, a cleaning method is needed that does not require the use of abrasive particles or the removal of the component. A method of removing contaminant deposits from combustor effusion holes is needed that does not require combustor removal.

SUMMARY OF THE INVENTION

In one aspect of the present invention, a method of cleaning a component comprises a step of spraying a fluid through at least one nozzle assembly and towards at least one surface of the component, the nozzle assembly held in position relative to the component by an adapter portion of the nozzle assembly.

In another aspect of the present invention, a method of cleaning a component having an interior surface and an exterior surface comprises a step of spraying a cleaning fluid through at least one nozzle assembly such that a first portion of the cleaning fluid passes through a first spray portion of the nozzle assembly and towards the interior surface and a second portion of the cleaning fluid passes through a second spray portion of the nozzle assembly and towards the exterior surface.

In still another aspect of the present invention, a method of cleaning a combustor having at least one igniter plug boss comprises the steps of inserting a spray portion of a nozzle assembly through the igniter plug boss; and pumping a cleaning flow through the nozzle assembly such that at least one fluid stream impinges an interior surface of the combustor.

In yet another aspect of the present invention, a method of cleaning an annular combustor comprises a step of pumping an acid solution through at least one nozzle assembly such that a first portion of the acid solution passes through a first rotating spray head of the nozzle assembly and towards an interior surface of the annular combustor and a second portion of the acid solution passes through a second rotating spray head of the nozzle assembly and towards an exterior surface of the annular combustor.

In another aspect of the present invention, a method of removing a contaminant deposit from an effusion hole of a combustor comprises the steps of pumping a recirculating flow through at least one nozzle assembly, the recirculating flow comprising between about 3% and about 5% acetic acid, the nozzle assembly having a first rotating spray head, a second rotating spray head and an adapter portion, wherein a first portion of the recirculating flow passes through the first rotating spray head and impinges an interior surface of the combustor and a second portion of the recirculating flow passes through the second rotating spray head and impinges an exterior surface of the combustor, the pumping capable of removing the contaminant deposit; and pumping a rinse flow comprising distilled water through the nozzle assembly.

In a further aspect of the present invention, an apparatus for a cleaning a combustor comprises a first spray portion capable of being inserted through an opening of the combustor, the first spray portion capable of providing at least one fluid stream to an inner liner of the combustor; and an adapter portion in contact with the spray portion and capable of holding the apparatus in position relative to the combustor.

DETAILED DESCRIPTION OF THE INVENTION

Broadly, the present invention provides apparatus and methods for cleaning components, such as combustors, and methods for producing the same. The cleaning apparatus and methods according to the present invention may find beneficial use in many industries including aerospace, automotive, and electricity generation. The present invention may be beneficial in applications including maintenance and repair of engine components. This invention may be useful in any component cleaning application.

In one embodiment, the present invention provides a method for cleaning a component, such as a combustor. The method may comprise positioning at least one nozzle such that a cleaning fluid passed through the nozzle can impinge an interior surface of the combustor. This is unlike the prior art that positions a nozzle such that a cleaning fluid passed through the nozzle impinges the exterior surface of the combustor only. Because the prior art sprays the cleaning fluid only on the exterior surface of an annular combustor, the cleaning fluid impinges only the radially outward surface of the outer liner, resulting in insufficient cleaning of the inner liner. Unlike the prior art, the cleaning fluid of the present invention can impinge the radially outward surface of the inner liner of an annular combustor to provide inner liner cleaning.

A method30of cleaning a component according to an embodiment of the present invention is shown inFIG. 1. The method30may comprise a step31of providing at least one nozzle assembly, a step32of positioning a spray portion of the nozzle assembly such that at least one fluid stream from the nozzle assembly is capable of impinging a surface of the component, a step33of positioning an adapter portion of the nozzle assembly such that the nozzle assembly is held in position relative to the component, and a step34of providing a flow to the nozzle assembly such that at least one fluid stream is produced.

The component may comprise any turbine engine component. The component may comprise a chamber. For example, the component may comprise a combustor60having a combustion chamber55, as depicted inFIG. 2. The chamber may be defined at least in part by one or more effusion panels, such as combustor liners. For example, the chamber may be defined in part by a combustor inner liner56and a combustor outer liner57.

The step31of providing at least one nozzle assembly may comprise providing a nozzle assembly40having at least one spray portion42and an adapter portion45, as depicted inFIG. 2. The spray portion42may be in contact with the adapter portion45. The number of nozzle assemblies40may vary with application. For example, when the component comprises a combustor60having two igniter plug bosses47, the step31may comprise providing two nozzle assemblies40.

The spray portion42of the nozzle assembly40may be capable of receiving a flow58and providing at least one fluid stream41. For some applications, the spray portion42may comprise conventional spray apparatus. The spray portion42may comprise a fixed spray bar43, as shown inFIG. 2. The fixed spray bar43may comprise a cylindrical member having at least one nozzle opening50, as shown inFIG. 9. Alternatively, the spray portion42may comprise a rotating spray head44, as depicted inFIGS. 3 and 4. The rotating spray head44, better seen inFIGS. 5aandb, may comprise at least one nozzle opening50. Rotating spray heads44are known in the art and may rotate in response to a flow through the nozzle assembly40due to the orientation of the nozzle openings50. Although the spray portion42depicted inFIG. 5acomprises a bolt72and a washer73, other spray portion configurations may be useful for some applications. The spray portion42may comprise a receiving aperture70and at least one nozzle opening50, as depicted inFIGS. 3 and 4.

A receiving aperture70may be an opening capable of receiving the flow58. The receiving aperture70may be in flow communication with at least one nozzle opening50. The flow58may enter the receiving aperture70and pass through at least one nozzle opening50to provide at least one fluid stream41. For a given volume of flow58through the receiving aperture70, the volume of the fluid stream41may be inversely proportional to the number of nozzle openings50of the nozzle assembly40.

The nozzle opening50may be an opening capable of providing the fluid stream41. The diameter of the nozzle opening50may vary with application and may depend on factors including the dimensions of the component to be cleaned and the pressure of the flow58. For example, for some annular combustor applications the diameter of the nozzle opening50may be between about 0.01 inches and about 0.05 inches. The number of nozzle openings50of the spray portion42may vary with application and may depend on factors including the pressure and velocity of the flow58, the number of spray portions42of the nozzle assembly40, and the dimensions of the component. For example, for a combustor60having a diameter77(shown inFIG. 6) of 15.53 inches, the spray portion42may have about 18 nozzle openings50, each having a diameter of about 0.02 inches. Computational fluid dynamic (CFD) analysis may be useful in determining the desired number and diameter of the nozzle openings50for a particular application.

The nozzle opening50may be capable of providing the fluid stream41at an angle52relative to a nozzle centerline51, as shown inFIG. 2. The angle52may have radial, axial, and tangential components with respect to the nozzle centerline51and the interface between the nozzle assembly40and an igniter plug boss47. Each nozzle opening50of the spray portion42may provide a fluid stream41at a different angle52. By varying the angle52, a larger portion of the component surface may be impinged by the fluid streams41. For some applications, the spray portions42may distribute the fluid streams41axially, radially, and circumferentially over an entire combustor. CFD analysis may be useful in determining the desired angle52of the nozzle openings50for a particular application.

The adapter portion45of the nozzle assembly40may be capable of holding the nozzle assembly40in position with respect to the component. The adapter portion45may comprise any apparatus capable of holding the nozzle assembly40in position during component cleaning. The adapter portion45may be capable of releasably coupling the nozzle assembly40to an engine component. In other words, the nozzle assembly40may be attached to an engine component during component cleaning and removed during normal engine operation. Adapter portions45are known in the art and may include spindles, fittings and o-rings. For example, when the nozzle assembly40is positioned in the APU igniter plug boss47, the adapter portion45may comprise a first fitting46in contact with the igniter plug boss47, a second fitting48in contact with the first fitting46and an o-ring49in contact with and between the first and second fittings,46and48, as depicted inFIG. 2. Alternatively, the adapter portion45may comprise a spindle67in contact with the igniter plug boss47, as depicted inFIG. 4. The spindle67, better seen inFIGS. 5aandb, may be adapted to accommodate at least one rotating spray head44. The adapter portion45may vary with application and may depend on the configuration of the component, the configuration of the nozzle application point and manufacturing limitations.

A nozzle application point66, as depicted inFIG. 3, may comprise an opening through which the spray portion42of the nozzle assembly40may be passed. The nozzle application point66may comprise an opening78capable of being in contact with the adapter portion45of the nozzle assembly40, as shown inFIG. 2. The nozzle application point66may be a generic term and may comprise the igniter plug boss47, as depicted inFIGS. 2 and 6. When the nozzle application point66comprises the igniter plug boss47, the nozzle assembly40may be positioned such that the nozzle assembly40extends through a combustor case68and the spray portion42of the nozzle assembly40is positioned within a combustion chamber55. The nozzle application point66may be located at a fuel nozzle62, as depicted inFIGS. 6 and 7. The nozzle application point66may vary and may depend on the configuration of the component and the accessibility of the opening. For example, the nozzle application point66for an annular combustor application may comprise the igniter plug boss47. Nozzle application points66may be provided by modifying and/or removing existing structures, such as a fuel atomizer bolt63, a fuel nozzle62, a turbine housing bolt64, a combustor housing drain65, and an APU inlet61, as depicted inFIG. 8.

The step32of positioning the spray portion42may comprise inserting the spray portion42through the nozzle application point66. The spray portion42may be positioned such that a fluid stream41from the nozzle assembly40is capable of impinging a surface of the component. When the spray portion42is positioned within a component chamber, such as a combustion chamber55, the fluid streams41may impinge an interior surface53of the component, as depicted inFIG. 9. When the spray portion42is positioned outside the component, the fluid streams41may impinge an exterior surface59of the component, as depicted inFIG. 10. For nozzle assemblies40comprising more than one spray portion42, one spray portion42may be positioned within a component chamber and another spray portion may be positioned outside the component, as depicted inFIG. 11. Nozzle assemblies40comprising more than one spray portion42may provide a plurality fluid streams41that impinge an interior surface53of the component and a plurality fluid streams41that impinge an exterior surface59of the component. Interior surface53and exterior surface59may be defined with reference to a component chamber, such as combustion chamber55. For example, exterior surface59of an annular combustor79, depicted inFIG. 8, may include a radially outward surface of an outer liner57. Exterior surface59may include a radially inward surface of an inner liner56. An interior surface53of an annular combustor79may include a radially inward surface80of an outer liner57and a radially outward surface81of an inner liner56.

The step33of positioning the adapter portion45may comprise placing the adapter portion45in contact with the nozzle application point66and manually rotating the first fitting46and/or second fitting48. The step33may comprise inserting a spindle67in the nozzle application point66. The step33may comprise removably attaching the adapter portion45to the nozzle application point66, such as igniter plug boss47. The step33may result in the spray portion42being held in position relative to the combustor60. The step33may vary with application and may depend on the configuration of the nozzle application point66and the configuration of the adapter portion45.

The step34of providing a flow58to the nozzle assembly40may comprise pumping a fluid into the nozzle assembly40. Methods of providing a flow58may comprise conventional pumping techniques. Methods of providing a flow58may comprise a length of tubing74, a nozzle/tubing coupler75, and a pump (not shown), depicted inFIG. 7. The pump may force the flow58through the length of tubing74from a container (not shown) to the nozzle assembly40. The nozzle/tubing coupler75may couple the tubing74to the nozzle assembly40. The pressure and flow rate of the flow58may vary with application. The pressure and flow rate of the flow58may depend on factors including the dimensions of the component and the diameter of the nozzle openings50. For example, for an annular combustor application, the flow58may be provided at about ½ gallon per minute and about 60 psi. For some applications, the flow58may be provided at a flow rate between about ½ gallon per minute and about 30 gallons per minute. For some applications, the flow58may be provided at a pressure between about 10 psi and about 250 psi. The volume of the flow58provided may vary with application and may depend on the dimensions and configuration of the component and the composition of the flow58. The composition of the flow58may be selected such that the flow58does not attack the metal and/or thermal barrier coating (TBC) of the component. For example, for an annular combustor79of an APU, the flow58may comprise about 24 gallons of 5% acetic acid solution.

For some applications, the nozzle assembly40may be manually rotated during the step34. For example, when the spray portion42comprises a fixed spray bar43, the fixed spray bar43may be rotated by hand while the flow58is pumped through the nozzle assembly40. The rotation of the spray portion42may improve the distribution of the fluid streams41. For some applications, the spray portion42may comprise a rotating spray head44and manual rotation may be unnecessary.

The method30may comprise at least one step34of providing a flow58. The method30may comprise more than one step34. For example, the method30may comprise a first step34wherein the flow58comprises 5% acetic acid solution and a second step34wherein the flow58comprises distilled water. In this example, the first step34may dissolve a contaminant deposited on the component surface and the second step34may remove an acid solution residue left on the component surface by the first step34.

The method30may comprise more than one step34with a wait period or dwell time between the successive steps34. For example, the method30may comprise a step34wherein the flow58comprises 5% acetic acid solution followed by a waiting period of ten minutes and then another step34wherein the flow58comprises 5% acetic acid solution. In this example, the dwell time may be provided to allow additional time for the acid solution to react with the contaminant deposit76. For some applications, the contaminant deposit76may not be sufficiently removed by one acid wash step and more than one acid wash step may be useful. The number of steps34may vary with application and may depend on factors including the composition of the flow58and the composition and mass of the contaminant deposit76.

The method30may comprise a step34of providing a flow58wherein the flow58comprises a recirculating flow. For a recirculating flow, an effluent69may be collected, filtered and provided to the receiving aperture70. For some recirculating flows, the effluent may be collected and provided to the receiving aperture70without filtering. The effluent69may comprise a cleaning solution or rinse water that has been sprayed through the nozzle assembly40and then drained from the component. After the fluid streams41impinge a surface of the component, they may provide an effluent69, as depicted inFIG. 2. For example, a spray portion42positioned inside a combustion chamber55may provide a plurality of fluid streams41that impinge an interior surface53of a combustor60. After impinging the interior surface53, the fluid streams41may exit the combustion chamber55though the effusion holes71(shown inFIG. 12b) of the outer liner57and pass through the combustor housing drain65to provide an effluent69. The effluent69may be collected, filtered, and returned the nozzle assembly40by known techniques. Methods for collecting, filtering and returning the effluent69may comprise providing a length of tubing and a filter apparatus between and in flow communication with the combustor housing drain65and the receiving aperture70.

The flow58of step34may comprise a cleaning flow or a rinse flow. The cleaning flow may be any flow58that is capable of cleaning the component. The cleaning flow may be capable of dissolving a contaminant deposit76, shown inFIG. 12b. The cleaning flow may be capable of dissolving environmental contaminants, such as Si, O, and S. Useful cleaning flows may comprise an acidic solution having a pH between about 2.0 and about 3.0. Useful cleaning flows may include acetic acid, phosphoric acid, citric acid, and others. For some applications, the cleaning flow may comprise an acetic acid solution with a pH between about 2.0 and about 3.0. For some applications, the cleaning flow may comprise a solution with a pKa of about 4.76. The cleaning flow may comprise an additive such as a surfactant or a wetting agent. The cleaning flow may comprise one or more additives. Conventional surfactants and wetting agents may improve component cleaning by reducing the surface tension of the flow58, which may provide improved contact between the flow58and the contaminant deposit76. The composition of the cleaning flow may vary with application and may depend on the composition of the component and the composition of the contaminant deposit76. The cleaning flow may comprise any fluid capable of removing contaminant deposits76from effusion holes71without attacking the metal of the component. For example, the cleaning flow may comprise 5% acetic acid. For some applications, the cleaning flow may comprise between about 0% and about 25% acetic acid. For some applications, the cleaning flow may comprise between about 1% and about 10% acetic acid. For some applications, the cleaning flow may comprise between about 3% and about 5% acetic acid. Some cleaning flows may leave a cleaning flow residue on the component. The flow58may comprise a rinse flow capable of removing the cleaning flow residue from the component. The rinse flow may be any flow58that is capable of rinsing the component. The rinse flow may comprise water, such as distilled water and deionized water.

An annular combustor having two igniter plug bosses was provided, as shown inFIGS. 12aandb. The combustor was about 65 percent plugged. Several completely plugged effusion holes (indicated by arrows inFIG. 12b) were circled for later observation. A nozzle assembly comprising a fixed spray bar was inserted into the first igniter plug boss, as shown inFIG. 2. The nozzle assembly was held in position by an adapter portion comprising two fittings and an o-ring. The receiving aperture of the nozzle assembly was attached to a quick disconnect fluid fitting elbow. The spray portion of the nozzle assembly was manually rotated while ½ gallon of 5% acetic acid was pumped through the nozzle at 60 psi using a pump assembly with a minimum flow rate of ½ GPM. The nozzle assembly was removed from the first igniter plug boss and positioned in the second igniter plug boss. The nozzle was manually rotated while another ½ gallon of 5% acetic acid was pumped through the nozzle at 60 psi using a pump assembly with a minimum flow rate of ½ GPM. This was followed by a ten minute wait period. The pumping and wait period were repeated six times to deliver a total of six gallons of acetic acid solution and complete the first wash cycle. The nozzle and pump assembly was then used to deliver 6 gallons of distilled water in the same manner to complete the first rinse cycle. The wash and rinse cycles were then repeated to deliver another 6 gallons of acetic acid solution and 6 gallons of distilled water. The APU was operated and cooled. The wash and rinse cycles were repeated twice to deliver another 12 gallons of acetic acid solution and 12 gallons of distilled water. The total cleaner volume was 24 gallons and the total soak time was 240 minutes for this example. Combustor cold flow verification confirmed improved flow through the combustor. The flow data is shown inFIG. 13. The table shows the airflow improvement with respect to total cleaner volume and total soak time. As can be seen, other cleaner volumes and soak times also resulted in reduced blockage. The graph inFIG. 14shows the airflow improvement with respect to hours of cleaning. For some applications, the time required to perform the cleaning procedure may be reduced by reducing the number of intermediate rinse cycles and/or rinse volume.

As can be appreciated by those skilled in the art, the present invention allows aircraft operators and maintenance facilities to remove the blockage within combustor effusion cooling holes at specific maintenance intervals without removing the engine from the aircraft. This regular cleaning schedule may eliminate the possibility of experiencing uncommanded engine shutdowns that result from reduced lean blowout margin due to blocked combustor effusion cooling holes, or wall distress due to reduced cooling effectiveness.