Patent Application
20130081654
The subject matter disclosed herein relates to the cleaning of gas turbine combustion cans.
Certain gas turbines, such as General Electric F-Series gas turbines using quaternary fuel, have components that are constructed of mild steel. Debris, including iron oxide corrosion products, may form inside fuel pathways or channels of the turbine combustion casings, or “cans”. For example,
At present, one method of mechanically cleaning the quaternary fuel gas distribution annulus chamber involves cutting off the fuel pegs followed by attempts to hydro-blast the iron deposits by gaining access to the quaternary annulus channel via the fuel peg holes. Another method of cleaning the quaternary fuel gas distribution annulus chamber involves the use of chemical rinsing agents. Yet another method of cleaning the quaternary fuel gas distribution annulus chamber involves the use of a lubricant and round objects placed in the chamber that is then shaken by large equipment to dislodge any debris. In many cases, these existing cleaning processes require removal of the combustor cans from the turbine and shipment offsite, which can be time consuming and costly.
It would be desirable to provide a rapid method to clean critical fuel pathways in a gas turbine thus removing the potential for iron deposits to block fuel gas passages. The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.
A method is disclosed, wherein the annulus chamber of a gas turbine fuel chamber is cleaned. An advantage that may be realized in the practice of some disclosed embodiments of the method is that it is possible to clean the annulus chamber while the fuel chamber is mounted to the turbine (i.e. removal is not required) without resorting to chemical cleaning agents.
In one exemplary embodiment, a method for cleaning an annulus chamber is disclosed. The method comprises the steps of feeding a cable through the annulus chamber in a first direction to a position at least 180 degrees from the fuel inlet orifice and then rotating the cable. The annulus chamber is then aerated to remove dislodged debris.
In another exemplary embodiment, the method comprises the steps of feeding a vacuuming tool through the annulus chamber followed by feeding a cable through the annulus chamber in a first direction to a position at least 180 degrees from the fuel inlet orifice and then rotating the cable. The annulus chamber is then aerated to remove dislodged debris.
In another exemplary embodiment, a method for cleaning an annulus chamber is disclosed. The method comprises the steps of feeding a vacuuming tool through the annulus chamber followed by feeding a cable through the annulus chamber in a first direction to a position at least 270 degrees from the fuel inlet orifice and then rotating the cable. The cable is then fed through the annulus in a second direction to a position at least 270 degrees from the fuel inlet orifice and is then rotated. The annulus chamber is then aerated to remove dislodged debris.
This brief description of the invention is intended only to provide a brief overview of subject matter disclosed herein according to one or more illustrative embodiments, and does not serve as a guide to interpreting the claims or to define or limit the scope of the invention, which is defined only by the appended claims. This brief description is provided to introduce an illustrative selection of concepts in a simplified form that are further described below in the detailed description. This brief description is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all disadvantages noted in the background.
So that the manner in which the features of the invention can be understood, a detailed description of the invention may be had by reference to certain embodiments, some of which are illustrated in the accompanying drawings. It is to be noted, however, that the drawings illustrate only certain embodiments of this invention and are therefore not to be considered limiting of its scope, for the scope of the invention encompasses other equally effective embodiments. The drawings are not necessarily to scale, emphasis generally being placed upon illustrating the features of certain embodiments of invention. In the drawings, like numerals are used to indicate like parts throughout the various views. Thus, for further understanding of the invention, reference can be made to the following detailed description, read in connection with the drawings in which:
It is known that deposits (e.g. iron oxide corrosion products, dust and other debris) collect in the quaternary annulus chamber 16 and may result in blockage of fuel gas passages in the quaternary pegs 18. This potentially interferes with the flame pattern in the combustion chamber of the forward combustion can 10. The method disclosed is directed to a method of removing this debris from the quaternary annulus chamber 16 of the forward combustion cans 10. The forward combustion cans 10 are cleaned at a repair facility or on-site with a mobile cleaning unit using a novel procedure such that the cans 10 can be cleaned within a matter of a few hours or days rather than the weeks conventional methods required. The described embodiments contemplate both removing the forward combustion cans 10 from the turbine as well as cleaning the combustion cans 10 while in place on the turbine. Both such embodiments are within the scope of the invention.
Generally, as depicted in
Referring to
At first vacuuming step 104, a first end of an elongated vacuuming tool is inserted through the fuel inlet orifice 14 and into the annulus chamber 16 in a first circumferential direction. For example, and with reference to
At second vacuuming step 106 the first end of the elongated vacuuming tool is inserted through the fuel inlet orifice and into the annulus chamber 16 in a second circumferential direction, opposite the first circumferential direction. The vacuuming tool may be fed into the annulus chamber 16 from 180 degrees to 360 degrees from the fuel inlet orifice 14, and all subranges therebetween. Second vacuuming step 106 is particularly useful for those embodiments where the first vacuuming step traverses less than the full length of the annulus chamber 16. After step 106 is completed, the vacuuming tool is removed from annulus chamber 16.
At first rotary cleaning step 108, a first end of an elongated cleaning cable is inserted through the fuel inlet orifice 14 and into the annulus chamber 16 in a first circumferential direction. The first circumferential direction of step 108 (rotary cleaning) may be the same or opposite the first circumferential direction of step 104 (vacuuming). Like the feeding step of the vacuuming tool (when the tool is passed in circumferential direction A) the cable passes first position 26 (90 degrees from the fuel inlet orifice 14) to at least second position 28 (180 degrees from the fuel inlet orifice 14). In another embodiment, the cable passes first position 26, second position 28 to reach at least to third position 30 (270 degrees from the fuel inlet orifice 14). Any suitable elongated cleaning cable may be used including, for example, the cable commonly used in speedometers. In one embodiment the cable is encased in a protective sheath (e.g. a polymeric sheath) to protect the walls of annulus chamber 16 from damage. In one embodiment, the first end of the cable is bent to provide a hook, for example, a 90 degree bend, or is attached to a suitable cleaning tool for dislodging debris. Advantageously, this hooked-end assists in removing debris during subsequent rotational cleaning steps.
First rotational step 110 is executed by attaching the second end of the cable to a rotary instrument such as a manual rotary tool or power rotary tool (e.g. DREMEL brand rotary tool or an air die grinder). The activation of the rotary tool causes the cable to rotate within the confines of annulus chamber 16 about the longitudinal axis that stretches over the cable's length. Advantageously, this rotary action of the cable dislodges debris from the inner wall surface of annulus chamber 16 without resorting to chemical cleaning agents. This minimizes the costs associated with the disposal of such cleaning agents. In certain embodiments, the rotary instrument is operated at one of its lower power settings as higher settings can entangle the cable and/or cause elements to overheat due to frictional forces. In one embodiment, the cable is slowly withdrawn as it rotates. In another embodiment, the cable is rotated, stopped, and then withdrawn. By way of illustration and not limitation, the cable may be withdrawn over a period of two to three minutes. After step 110 is completed, the elongated cable is withdrawn and steps 112 and 114 are executed.
Steps 112 and 114 are similar to steps 108 and 110 except in that the cable is fed about the annulus chamber 16 in a second circumferential direction that is opposite the first circumferential direction of step 108. In step 116, a vent brush is passed through the annulus chamber 16. In one embodiment, the vent brush has bristles that span the diameter of the annulus chamber 16. The vent brush may be passed to the 180 degree position and subsequently withdrawn, passed to the 270 degree position and then withdrawn, or passed through the entire length of the annulus chamber. In one embodiment, the vent brush is passed through annulus chamber two or more times. In another embodiment, the vent brush is passed through the annulus chamber three or more times. In one embodiment, the vent brush is about 2.4 meters long with bristles at a first end of the elongated, flexible vent brush.
In step 118, the annulus chamber 16 is aerated by first attaching an adapter to the fuel flange 20 that includes an air inlet and an air outlet. The flowing air pushes dislodged debris out of the air outlet. In one embodiment, the air outlet is connected to a vacuum. Pressurized air is supplied to the air inlet. The air travels through the annulus chamber 16 and exits the air outlet. In one embodiment, about 3.5 to about 10.5 atmospheres of pressure is delivered to the air inlet. In another embodiment, about 6.0 to 7.0 atmospheres of pressure is delivered. The air flow is continued for a predetermined period of time. In one embodiment, the air flow is continued for fifteen seconds to a minute. In another embodiment, the air flow is continued for thirty to forty-five seconds.
In step 120, a post-cleaning visual inspection of annulus chamber 16 is conducted with a borescope. Step 120 is substantially similar to step 102 (pre-cleaning visual inspection).
The aforementioned steps can be performed while the forward combustion can 10 is removed from the turbine or while it is still mounted to the turbine. In those embodiments where the steps are performed while it is removed from the turbine, the inner fuel pegs 18 are accessible. Such an embodiment provides an opportunity also clean the pegs 18.
Referring again to
Referring now to
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.
