Patent Description:
The present invention is directed, in general, to removing debris from a flow path, and more particularly, to a system and method for removing debris from the flow path of components having cooling holes.

Debris in the form of scaling oxidation can make its way inside turbine airfoils and clog the cooling holes. Clogged cooling holes may result in overheating and breaching of the airfoils, particularly the row two turbine vanes, requiring a forced outage to replace or repair the vanes.

In one approach, an in-line witch hat strainer may be used, which is located inside the cooling air pipes leading to the row two vanes. However, such a strainer may cause an undesirable pressure drop, may clog, and may only be cleaned or inspected by shutting down the unit and removing the section of pipe containing it.

Another approach may include using an in-line cyclonic separator. However, such a separator may need to be tuned for each specific application, is relatively expensive, and may require a significant amount of pipe space compared to other approaches described herein.

Thus, systems to limit or eliminate such clogging are desirable.

<CIT> discloses a cooled turbine blade with a centrifugal particle separator wherein cooling flow is communicated to cooling holes via piping that includes a dead leg debris extractor, wherein the dead leg debris extractor includes a means to capture and retain debris from the cooling flow continuously during online operation of the turbine. According to <CIT>, in operation, the mixture of cooling air and microscopic dust particles enters through the inlet port. The mixture enters the centrifugal particle separator with a particular velocity that arises because of a pressure differential in the cooling network. The rotation creates a centrifugal force, slinging microscopic dust particles within the air flow away from the central axis. The microscopic dust particles migrate toward the conical section while the filtered air exits the centrifugal particle separator through the outlet tube. <CIT> further discloses a conical section arranged proximate to the first end of the centrifugal particle separator. The conical section tapers to a narrow exit portion, where a portion of air and filtered microscopic dust particles exit the centrifugal particle separator.

<CIT> discloses a cooling system for a turbine blade comprising a particle collection chamber. The inertia of particulate carries the particulate into particle collection chamber where it is collected and prevented from entering the smaller cross-sectional area metering passage as pressurized air makes a sharp turn into metering passage.

Briefly described, aspects of the present disclosure relate to a system and a method for removing debris from a flow path of a cooling flow. The aspects are met by the independent claims.

The system removes debris from a flow path of a cooling flow. The system includes at least one airfoil to which a cooling flow is communicated, the cooling flow flowing through the cooling holes in the airfoil to cool the airfoil. The cooling flow is communicated to the cooling holes through piping that includes a dead leg debris extractor. The dead leg debris extractor includes a means to capture and retain debris from the cooling flow continuously during online operation of the turbine.

The method removes debris from a cooling flow communicated to cooling holes of an airfoil in a turbine. The method includes installing a dead leg extractor to piping communicating the cooling flow to the cooling holes of the airfoil and extracting debris from the cooling flow via the dead leg extractor continuously during operation of the turbine.

Piping dead legs are commonly used in different industrial applications to remove debris or other unwanted substances from a flow path. Typically, the dead leg device is placed on the end of a <NUM>° pipe turn and captures substances which have a higher density than the flow medium by simple inertia. However, dead leg devices typically accumulate debris over time and must be periodically cleaned out while the operating device is offline.

The following describes a further approach to collect such debris, in which a piping dead leg is used to remove and retain debris from a cooling flow path of a turbine engine. Such a dead leg extractor may be placed as described above at the end of a <NUM>°pipe turn and includes features that will capture and retain almost all the debris in the cooling flow path over time. Additionally, the dead leg extractor allows for periodic removal of the retained debris while the turbine is in on-line operation. While a turbine engine and its corresponding vanes and blades are used throughout the disclosure to exemplify the proposed debris extractor, one skilled in the art would understand that the debris extractor may be utilized to remove debris en route via piping to components further downstream and in particular components including holes through which a fluid flows.

To facilitate an understanding of embodiments, principles, and features of the present disclosure, they are explained hereinafter with reference to implementation in illustrative embodiments. Embodiments of the present disclosure, however, are not limited to use in the described systems or methods.

The components and materials described hereinafter as making up the various embodiments are intended to be illustrative and not restrictive. Many suitable components and materials that would perform the same or a similar function as the materials described herein are intended to be embraced within the scope of embodiments of the present disclosure.

Broadly, a system and method for removing debris from a flow path of a cooling flow is proposed. The system includes a turbine having at least one airfoil via which a cooling flow is communicated to cooling holes in the airfoil via piping that includes a dead leg debris extractor. The dead leg debris extractor comprises a dead leg and a cone within the dead leg. The method includes installing the dead leg extractor to the piping communicating the cooling flow to the cooling holes of the airfoil and, during operation of the turbine continuously extracting debris from the cooling flow via the dead leg extractor.

Referring now to the <FIG>--<NUM>, a turbine component for a gas turbine engine is shown in <FIG> in the form of a stationary turbine vane <NUM>. The vane <NUM> includes an elongated airfoil having a body <NUM> with an outer wall <NUM> and an inner wall. The vane <NUM> may also include an outer shroud <NUM> at a first end of the vane <NUM> and an inner shroud <NUM>, also known as a platform, at a second end of the vane <NUM>. The vane <NUM> may be configured for use in a gas turbine engine. The body <NUM> of the vane may define one or more hollow pockets <NUM> to allow for a cooling fluid to flow therethrough for cooling of the vane <NUM>. The temperatures to which blades and vanes of a gas turbine are exposed due to the flow of hot gas may be upwards of <NUM>° C and possibly even as high as <NUM>-<NUM>° C in the flow path. The more efficiently that heat is removed from the component, the higher the overall efficiency that can be achieved. For this purpose, the vane <NUM> may additionally include a plurality of cooling holes <NUM> which are used to cool the internal wall of the vane <NUM>. Extending spanwise within the hollow pockets, the vane <NUM> may include vane inserts <NUM> having cooling holes for further cooling.

<FIG> illustrates a perspective view of a gas turbine engine <NUM>. Piping <NUM> is attached to the outer casing <NUM> for the purpose of bleeding cooling air from the compressor section and directing it to the vanes in the turbine section of the engine for cooling purposes. However, as mentioned above, compressor debris in the form of oxidation and airborne particulates, for example, may also exist in the cooling air flow which may clog the cooling holes <NUM> of the vanes. In order to remove and retain this debris, a dead leg extractor <NUM>,<NUM> may be installed on the existing piping <NUM> attached to the outer casing <NUM> of the turbine engine.

Referring now to <FIG>, cross sectional views of embodiments of the dead leg extractor <NUM>, <NUM> are shown. <FIG> illustrates the dead leg extractor <NUM> in a vertical orientation and <FIG> illustrates a horizontal orientation of the dead leg extractor <NUM>. The embodiments shown include design features that enhance the amount and type of debris captured by the dead leg extractor <NUM>, <NUM> while retaining the debris and preventing their escape back into the flow stream. Additionally, the embodiments allow for online removal or purging of the debris from the dead leg to permit the turbine <NUM> to be operated continuously without having to be shut down for dead leg cleaning.

For example, in the vertical embodiment as shown in <FIG>, a cooling flow (as shown by the arrows) flows vertically through the piping <NUM> within an inlet pipe <NUM> until it reaches a piping junction <NUM>. At this junction <NUM>, the cooling air continues to flow within the piping <NUM> through an outlet pipe <NUM>, as shown by the arrows. Debris, having a higher density than the cooling air flow, by inertia, is projected into a dead leg extractor <NUM>. As illustrated in <FIG>, the dead leg extractor <NUM> may comprise a dead leg <NUM>, which may be a vertical extension of the inlet pipe <NUM> from the junction <NUM> as shown, and a ringed pipe segment <NUM>. In an embodiment, as shown in <FIG>, the ringed pipe segment <NUM> is a cone.

In an embodiment, the cone <NUM> in the dead leg extractor <NUM>, <NUM> functions as a means to capture and retain the debris that enters the dead leg <NUM>. The incorporation of a cone geometry in the dead leg <NUM> has been shown through laboratory testing to significantly reduce the amount of debris lost over time once captured in the dead leg <NUM>, especially micron sized debris. In an embodiment, the cone <NUM> includes a first opening through which a flow containing debris enters, a smaller second opening through which the flow exits and a height. An outer diameter of the cone <NUM> at the first opening may abut an inner diameter of the dead leg pipe <NUM> such that the entire flow enters the first opening. In an embodiment, the height of the cone lies in a range of <NUM> to <NUM> x2,<NUM>. In another embodiment, the second opening of the cone lies in a range of <NUM> to <NUM> x2,<NUM>. While some ranges have been given, it should be appreciated that other cone geometries may be used depending on the flow characteristics and piping characteristics involved in the implementation.

In an embodiment, the system may include a cutback feature <NUM>. Testing has shown that approximately <NUM>% of the debris would impinge on the corner of the joint at the junction <NUM> and flow downstream into the outlet pipe <NUM> with the cooling flow without such a cutback feature. With a cutback feature <NUM>, the debris is more likely to enter the dead leg <NUM> instead. The cutback feature <NUM> may comprise angling the pipe at the lower portion of the joint so that debris is drawn down into the dead leg <NUM>.

In an embodiment, the system may include the incorporation of a blow down valve <NUM> connected at an end of the dead leg <NUM>, <NUM> opposite the junction <NUM>. The blow down valve <NUM> may open periodically on a timer in order to blow out debris. The blow down valve <NUM> allows the dead leg <NUM> to be purged of debris (due to the positive internal pressure) while the system is operating. The purged debris may be disposed into a solid waste container, for example. No shut down would be required to clean the dead leg <NUM>, as would be case with a traditional filter application such as the witch hat implementation.

In the illustrated embodiments shown in <FIG>, the pipe geometry may be optimized for both vertically and horizontally oriented dead legs <NUM>, <NUM> to maximize debris capture and retention. In the horizontal embodiment of the dead leg extractor <NUM>, a horizontal portion of the dead leg containing the cone <NUM> may have a slight downward slope ending in an elbow that flows into a vertically oriented portion of the dead leg <NUM>. A blow down valve <NUM> may be disposed at the end of the vertically oriented portion. The slight downward slope allows gravity to prevent debris from accumulating underneath the cone <NUM>, instead drawing it towards the blow down valve <NUM>. In an embodiment, the slight downward slope lies in a range of <NUM>-<NUM> degrees.

The proposed system and method reduces the risk of downstream damage, particularly to vanes of a gas turbine, in a turbine system. Advantageously, the proposed dead leg extractor can be implemented quickly, causes little if any decrease in cooling flow, carries low risk, takes up little piping space and requires little if any maintenance. For example, the dead leg extractor may simply be installed onto the existing piping of a gas turbine engine as shown in the <FIG>. The dead leg extractor is further relatively inexpensive to manufacture and provides a simple solution that may be installed on newly manufactured turbines as well as already existing turbines.

Claim 1:
A system for removing debris from a flow path of a cooling flow, comprising:
a turbine (<NUM>) including at least one airfoil (<NUM>) to which a cooling flow is communicated, the cooling flow flowing through the cooling holes (<NUM>) in the airfoil (<NUM>) to cool the airfoil (<NUM>), wherein the cooling flow is communicated to the cooling holes (<NUM>) via piping (<NUM>) that includes an inlet pipe (<NUM>), an outlet pipe (<NUM>), a junction (<NUM>) between the inlet pipe (<NUM>) and the outlet pipe (<NUM>) and dead leg debris extractor (<NUM>, <NUM>), dead leg debris extractor (<NUM>, <NUM>) comprising a dead leg (<NUM>) being an extension of the inlet pipe (<NUM>) from the junction (<NUM>),
wherein the dead leg debris extractor (<NUM>, <NUM>) includes a means to capture and retain debris from the cooling flow continuously during online operation of the turbine (<NUM>),
characterized in that
the dead leg debris extractor (<NUM>, <NUM>) further comprises a cone (<NUM>) within the dead leg (<NUM>) as the means to capture and retain debris and a blow down valve (<NUM>) connected at an end of the dead leg (<NUM>, <NUM>) opposite the junction (<NUM>),
wherein in case the cooling flow flows vertically within the inlet pipe (<NUM>) the dead leg is a vertical extension of the inlet pipe (<NUM>),
wherein in case the cooling flow flows horizontally within the inlet pipe (<NUM>) the dead leg is a horizontal extension of the inlet pipe (<NUM>) and includes a portion with a slight downward slope containing the cone (<NUM>) connected to a vertical portion containing the blow down valve (<NUM>), and
wherein the blow down valve (<NUM>) may open periodically on a timer in order to blow out debris.