Patent Application
20150089908
The present invention generally relates to a modular trash screen component for an air inlet duct of a turbine system, an air inlet duct including a trash screen assembly including a plurality of the trash screen components, and a method of assembling a trash screen assembly using a plurality of the modular trash screen components.
A turbine system typically includes an air inlet section for delivering intake air to a turbine, such as a gas turbine. The air inlet section typically has large ducting defining an enclosed flow path for air to flow to the turbine. Large pieces of debris (e.g., trash) can find its way into the ducting and become entrained in the air flow being delivered to the turbine. If debris enters the intake of the turbine, it can cause substantial damage. To inhibit large pieces of debris from making its way to the intake of the turbine, the air inlet section may include a trash screen assembly that allows the flow of air therethrough while inhibiting the pieces of debris from entering the turbine.
A typical conventional trash screen assembly includes upper and lower sections. Each section includes a rectangular support frame including vertical braces welded to the interior of the air inlet duct. A wire screen (e.g., sections of wire screen) is laid over a front or upstream face of the support frame. Flat bars are laid over the wire screen and welded to the support frame.
In one aspect, a modular trash screen component for an air inlet duct of a turbine system generally comprises a support frame and a wire screen secured to the support frame. The support frame encloses and defines a central opening of the support frame. The support frame has interior and exterior surfaces, a base portion, and a peripheral portion extending outward from the base portion. A wire screen is secured to the support frame. The wire screen has a base portion generally coextensive with the central opening of the support frame, and a peripheral portion extending outward from the base portion of the wire screen. The wire screen is nested in the support frame such that outer edge margins of the base portion of the wire screen are in generally opposing relationship with the interior surface of the base portion of the support frame, and the peripheral portion of the wire screen is in generally opposing relationship with the interior surface of the peripheral portion of the support frame.
In another aspect, a method of assembling a trash screen assembly in an inlet duct for a turbine system generally comprises providing a plurality of modular trash screen components, wherein each modular trash screen component includes a support frame enclosing and defining a central opening of the support frame, the support frame having interior and exterior surfaces, a base portion, and a peripheral portion extending outward from the base portion; and a wire screen secured to the support frame, the wire screen having a base portion generally coextensive with the central opening of the support frame, and a peripheral portion extending outward from the base portion of the wire screen, wherein the wire screen is nested in the support frame such that an outer edge margin of the base portion of the wire screen is in generally opposing relationship with the interior surface of the base portion of the support frame, and the peripheral portion of the wire screen is in generally opposing relationship with the interior surface of the peripheral portion of the support frame. The modular trash screen components are secured to the air inlet duct so that the modular trash screen components are arranged side-by-side in the air inlet duct.
In yet another aspect, an air inlet duct assembly generally comprises an air inlet duct for air inlet ducting of a turbine system. The air inlet duct includes upper, lower, left, and right side walls defining and enclosing an air passage having an inlet opening, an outlet opening, and a flow path extending between the inlet and outlet openings. A plurality of modular trash screen components are secured to the air inlet duct and arranged side-by-side within the air passage so that the modular trash screen components span horizontally across the air passage. Each modular trash screen component includes a generally rectangular support frame enclosing and defining a central opening of the support frame. The support frame has interior and exterior surfaces, a base portion, and a peripheral portion extending outward from the base portion. A generally rectangular wire screen is secured to the support frame. The wire screen has a base portion generally coextensive with the central opening of the support frame, and a peripheral portion extending outward from the base portion of the wire screen. The wire screen is nested in the support frame such that an outer edge margin of the base portion of the wire screen is in generally opposing relationship with the interior surface of the base portion of the support frame, and the peripheral portion of the wire screen is in generally opposing relationship with the interior surface of the peripheral portion of the support frame.
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An exemplary method of forming each of the modular trash screen components 132 and assembling the trash screen assembly 120 within the air inlet duct will now be described. In one embodiment, the desired horizontal dimensions W2 (e.g., widths) of the trash screen components are based, at least in part, on the inner horizontal dimension W1 of the air inlet duct 122. In one example, the number and horizontal dimensions W2 of trash screen components 132 used in each trash screen component set 134, 136 are determined by dividing the inner horizontal dimension W1 of the air inlet duct 122 into equal dimensions (e.g., two to six or more equal dimensions). Thus, each of the trash screen components 132 will have generally the same horizontal dimension W2 so that together the trash screen components span substantially the entire inner horizontal dimension of the air inlet duct. For example, in the illustrated embodiment each trash screen component set 134, 136 includes five trash screen components 132 having substantially identical horizontal dimensions W2.
In one example, the support frame 146 of each trash screen component 132 is constructed by welding together four angle irons (broadly, the support members) having dimensions suitable for forming the trash screen component of desired dimensions. For example, the iron angles may be laser-cut, 3/16″ stainless steel plate. The cross section of the support frame 146, as determined by the iron angles, can be chosen based, in part, on local strength requirements. The base portions 180 of the two braces 162, as in the illustrated embodiment, are welded to the interior surfaces of the opposite left and right angle irons 150 at locations that are ⅓ of the horizontal dimension W3 of the central opening 152 so that the braces divide the central opening into three equal sections. The base portions 180 of the braces 162 may include flat bars formed from 3/16″ stainless steel plate.
In one example, the rectangular wire screen 148 is formed from the continuous sinuous weft wire 166 extending generally transverse to and interwoven with the warp wires 164, as disclosed above. The peripheral portion 172 of the wire screen 148 is formed by bending the side edge margins of the screen forward. As shown in
With the wire screen 148 nested in the support frame 146, the upper, lower, left, and right clamping members 178 are plug welded to the interior surface of the peripheral portion 156 of the support frame 146 at the plug-welding locations 179. The peripheral portion 172 and the outer edge margins of the base portion 170 of the wire screen 148 are clamped between the respective clamping members 178 and the interior surface of the support frame 146. Each clamping member 178 may comprise a flat bar of stainless steel defining a plurality of openings at the plug-welding locations 179 for use in plug welding the clamping member to the support frame 146. With respect to the sides of the screen 148 defined by the warp wires 164, before plug welding the corresponding clamp member 178, portions of the weft wire 166 (or other wire extending transverse to the corresponding warp wires) adjacent the respective side edges defined by the warp wires may be removed, as shown in
Next, the wire screen 148 is secured to the braces 162. The extensions 186 of the stem portion 182 of each brace 162 are inserted into the openings 184 in the corresponding base portion 180 of the brace. The extensions 186 are then welded to the base portion 180 of the brace 162. The wire screen 148 may be secured to the braces 162 in other ways.
When assembling the trash screen assembly 120, the upper and lower flanges 140, 142 (i.e., screen-attachment members) are provided (e.g., secured) in the air inlet duct 122. The upper and lower flanges 140, 142 span the inner horizontal dimension W1 of the air inlet duct 122 and provide a surface to which the trash screen components 132 are secured. In one example, the upper and lower trash screen component sets 134, 136, which are offset along the flow path, are assembled in the inlet air duct 122. In such an example, each trash screen component set 134, 136 is secured (e.g., welded) to respective upper and lower vertical flanges 140, 142 within the inlet air duct. At least some of the upper and lower vertical flanges 140, 142 may comprise angle irons secured the left and right side walls 126c, 126d of the inlet duct housing 124 and spanning horizontally across the air passage 130. A plurality of the trash screen components 132 are secured (e.g., welded) to respective ones of the upper and lower vertical flanges 140, 142 to form the sets 134 of trash screen components 132. The trash screen components 132 in the upper set 134 are arranged side-by-side and span substantially the entirety of the inner horizontal dimension W1 of the air inlet duct 122. A plurality of additional trash screen components 132 are secured (e.g., welded) to respective ones of the upper and lower vertical flanges 140, 142 to form the lower set 136 of trash screen components 132. The trash screen components 132 in the lower set 136 are arranged side-by-side and span substantially the entirety of the inner horizontal dimension W1 of the air inlet duct 122. When retrofitting an existing inlet duct 122, existing trash screen assemblies may include the upper and lower vertical flanges 140, 142 spanning the inner horizontal dimension W1 of the air inlet duct 122. The existing trash screen assemblies may be removed while retaining the upper and lower vertical flanges 140, 142.
As can be appreciated from the above disclosure, one or more of the following advantages may be obtained:
modular trash screen components can be built and easily assembled as trash screen assemblies within the inlet duct, improving the dimensional accuracy and fabrication time of the trash screen assemblies;
the modular trash screen components can be built off-site and easily assembled as trash screen assemblies for retro-fit applications;
all portions of the wire screen are trapped within the trash screen components, which lessen the likelihood of broken fragments of the screen detaching from the trash screen components;
the screen is clamped to the frame to provide a shear connection that resists the tensile loads along the full perimeter of the screen;
the clamping members stretch the screen across the central opening before the clamping members are secured to the support frame to provide a taut screen; and
the screen is held captive by the braces, which increases the pull-out resistance and overall strength of the modular components.
Having described the invention in detail, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.
When introducing elements of the present invention or the preferred embodiments(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
As various changes could be made in the above constructions, products, and methods without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
