The field of the present invention relates generally to steam turbine engines, and more particularly, to sealing systems for use with steam turbine engines.
At least some known steam turbines have a defined steam path that includes a steam inlet, a turbine, and a steam outlet. Moreover, at least some known steam turbines include stationary nozzle segments that channel a flow of steam downstream towards turbine blades extending from a rotor. At least some known stationary nozzle segments include airfoils that facilitate channeling the steam flow. Each nozzle segment, in conjunction with an associated row of rotor blades, is typically referred to as a turbine stage. Most known steam turbines include a plurality of stages.
Generally, a gap is defined between a rotor blade tip and a stationary component, such as an engine casing. Although necessary for operation, such gaps undesirably enable steam to flow around the rotor blades rather than past the rotor blades, thereby reducing the efficiency of the turbine and causing losses in the steam flow. In at least some known steam turbines, a gap defined between the rotor blade tips and the engine casing may be reduced by replacing the stationary nozzle segments for each stage. Specifically, the steam turbine is disassembled and the stationary nozzle segments for each stage are replaced with nozzle segments that include a sealing extension coupled thereto. The sealing extension is positioned between the rotor blade tip and the engine casing such that the gap is substantially sealed.
However, replacement of the stationary nozzle segments for each stage may be time consuming and may result in extended operating downtimes of the steam turbine. As a result, the costs associated with turbine repair may be increased.
In one aspect, a method is provided for assembling a turbine engine. The method includes providing a retro-fit seal ring assembly that includes a plurality of unitary, arcuate ring segments that are circumferentially-spaced about a center axis of the ring assembly. Each of the plurality of ring segments includes a body and at least one integrally formed tooth that extends radially inward therefrom. The methods also includes extending at least one fastener through the body of each of the plurality of ring segments, and removably coupling each of the plurality of ring segments to an outer surface of a stationary component within the turbine engine using the at least one fastener.
In another aspect, a seal ring assembly is provided for use in a turbine engine. The assembly includes a plurality of unitary, arcuate ring segments that are circumferentially-spaced about a center axis of the assembly. Each of the plurality of ring segments includes a body and at least one integrally formed tooth extending radially inward therefrom. At least one fastener extends through the body of each of the plurality of arcuately-shaped ring segments. Each of the plurality of ring segments is removably coupled to an outer surface of a stationary component within the turbine engine using the at least one fastener.
In a further aspect, a turbine engine is provided. The engine includes a stationary component, and a seal ring assembly that is coupled to the stationary component. The assembly includes a plurality of unitary, arcuate ring segments that are circumferentially-spaced about a center axis of the assembly. Each of the plurality of ring segments includes a body and at least one integrally formed tooth extending radially inward therefrom. At least one fastener extends through the body of each of the plurality of arcuately-shaped ring segments. Each of the plurality of ring segments is removably coupled to an outer surface of a stationary component within the turbine engine using the at least one fastener.
An annular section divider 134 extends radially inward from central section 118 towards a rotor shaft 140 that extends between HP section 102 and IP section 104. More specifically, divider 134 extends circumferentially around a portion of rotor shaft 140 between a first HP section inlet nozzle 136 and a first IP section inlet nozzle 138. Divider 134 is received in a channel 142 defined in a packing casing 144. More specifically, in the exemplary embodiment, channel 142 is C-shaped and extends radially into packing casing 144 and around an outer circumference of packing casing 144, such that a center opening of channel 142 faces radially outward.
Steam turbine 100, in the exemplary embodiment, also includes a plurality of turbine rotor blades, or buckets, 146 (not shown in
In the exemplary embodiment, steam turbine 100 is an opposed-flow high pressure and intermediate pressure steam turbine combination. In an alternative embodiment, steam turbine 100 may be used with any individual turbine including, but not being limited to low pressure turbines. In another alternative embodiment, steam turbine 100 may be used with steam turbine configurations that include, but are not limited to, single-flow and double-flow turbine steam turbines. In yet another alternative embodiment, steam turbine 100 may be used with a gas turbine engine.
During operation, HP steam inlet 120 receives high pressure/high temperature steam from a steam source, for example, a power boiler (not shown). The steam is channeled through HP section 102 from inlet nozzle 136 wherein work is extracted from the steam to rotate rotor shaft 140 via rotor blades 146.
Seal ring assembly 200 is removably coupled to the radially outer portion 156 of each bling assembly 152 in each turbine stage 147. In the exemplary embodiment, seal ring assembly 200 is substantially circular and is formed from a plurality of circumferentially-adjacent seal segments 202. Each seal segment 202 includes a first end 204, a second end 206, and a body 208 extending therebetween. Moreover, at least one tooth 210 extends radially inward from seal segment 202. Specifically, in the exemplary embodiment, each segment 202 is integrally formed with the at least one tooth 210 such that each segment 202 is a unitary component. In the exemplary embodiment, each seal segment 202 is formed from a rub-tolerant material. As a result, in the event that rotor blade tip 141 contacts seal segment 202, seal segments 202 will deform to facilitate reducing and/or preventing any damage to rotor blades 146.
In the exemplary embodiment, each seal segment 202 is removably coupled to outer portion 156 such that each segment 202 extends between rotor blade tip 141 and carrier top half 150. Accordingly, in the exemplary embodiment, at least one tooth 210 is positioned adjacent to rotor blade tip 141 to facilitate sealing gap 149. More specifically, in the exemplary embodiment, seal ring assembly 200 is a retro-fit upgrade for steam turbines 100 that do not include rotor tip seal assemblies. Alternatively, seal ring assembly 200 may be installed in newly fabricated steam turbines 100. Removably coupling each seal segment 202 to outer portion 156 substantially eliminates the need to replace the entire bling assembly 152, thereby sealing gap 149 in a more cost effective manner. Accordingly, an amount of time that steam turbine 100 is offline is facilitated to be reduced. Moreover, removably coupling seal ring assembly 200 to bling assemblies 152 of each stage facilitates reducing the costs associated with sealing gap 149 as compared to other steam turbines that must replace the entire bling assembly 152 with an integral sealing extension extending therefrom.
Each seal segment 202, in the exemplary embodiment, is coupled to the existing outer portion 156 using at least one fastener 212. Alternatively, each seal segment 202 may be removably coupled to outer portion 156 using any means that enables seal segment 202 to function as described herein. In the exemplary embodiment, at least one fastener 212 extends away from each seal segment 202 and couples to outer portion 156. More specifically, each fastener 212 is substantially centered within each seal segment 202. Each seal segment 202 is circumferentially-spaced a distance away from each adjacent seal segment 202 such that a circumferential gap 214 is defined between each pair circumferentially-adjacent seal segments 202. Each circumferential gap 214 enables each seal segment 202 to thermally expand and contract with respect to at least one adjacent seal segment 202, outer portion 156, and/or the center portion of body 208, as described in more detail below.
During operation, steam is channeled through section 102, and more specifically, along steam path 148. Moreover, steam is channeled towards rotor blades 146 through inlet nozzle 136 and nozzles 158. Seal ring assembly 200, and more specifically, tooth 210 facilitates reducing an amount of steam that may flow past rotor blades 146 and through gap 149. More specifically, seal ring assembly 200 facilitates mitigating steam flow losses by substantially sealing gap 149. As a result, the amount of steam that may flow over rotor blades 146 is substantially reduced, which in turn increases the efficiency of steam turbine 100.
In the exemplary embodiment, each seal segment 302 is removably coupled to top half 150 such that each segment 302 extends between rotor blade tip 141 and carrier top half 150 and such that tooth 310 is positioned adjacent rotor blade tip 141 to facilitate sealing gap 149. Specifically, in the exemplary embodiment, seal ring assembly 300 is a retro-fit upgrade for steam turbines 100 that do not include rotor tip seal assemblies. Alternatively, seal ring assembly 300 may be installed in newly fabricated steam turbines 100. Removably coupling each seal segment 302 to top half 150 facilitates substantially eliminating the need to replace the entire bling assembly 152, which facilitates more efficient sealing of gap 149. In addition, because the entire bling assembly is not replaced, the amount of time steam turbine 100 is offline is substantially reduced. Moreover, removably coupling seal ring assembly 300 to bling assemblies 152 of each stage facilitates reducing the costs associated with sealing gap 149 as compared to steam turbines that must replace the entire bling assembly 152 with an integral sealing extension extending therefrom.
Each seal segment 302, in the exemplary embodiment, is coupled to top half 150 using at least one bolt 312. Alternatively, each seal segment 302 may be removably coupled to top half 150 using any means that enable seal segment 302 to function as described herein. In the exemplary embodiment, at least one bolt 312 extends away from each seal segment 302 to facilitate coupling segment 302. More specifically, each bolt 312 is substantially centered within each seal segment 302, and each seal segment 302 is circumferentially-spaced a distance away from each adjacent seal segment 302 such that a circumferential gap 314 is defined between each pair of circumferentially-adjacent seal segments 302. Circumferential gap 314 enables each seal segment 302 to thermally expand and contract with respect to at least one of adjacent seal segments 302, top half 150, and/or the center portion of body 308, as described in more detail below.
In the exemplary embodiment, seal ring assembly 300 is installed in steam turbine 100 as a retro-fit upgrade. Alternatively, seal ring assembly 300 may be installed on a newly manufactured steam turbine 100. A method of assembling a steam turbine with a retro-fit sealing assembly includes providing a retro-fit seal ring assembly 300. The method also includes extending at least one fastener 312 through body 308 of each seal segment 302. The method further includes coupling each seal segment 302 to an outer surface of a stationary component using the at least one fastener 312.
During operation, steam is channeled through section 102, and more specifically, along steam path 148. Moreover, steam is channeled towards rotor blades 146 through inlet nozzle 136 and nozzles 158. Seal ring assembly 300, and more specifically, tooth 310 facilitates reducing an amount of steam that may flow past rotor blades 146 and through gap 149. More specifically, seal ring assembly 300 facilitates mitigating steam flow losses by substantially sealing gap 149. As a result, the amount of steam that may flow over rotor blades 146 is substantially reduced, which in turn increases the efficiency of steam turbine 100.
In one embodiment, a method is provided for assembling a turbine engine. The method includes providing a retro-fit seal ring assembly that includes a plurality of unitary, arcuate ring segments that are circumferentially-spaced about a center axis of the ring assembly. Each of the plurality of ring segments includes a body and at least one integrally formed tooth that extends radially inward therefrom. The methods also includes extending at least one fastener through the body of each of the plurality of ring segments, and removably coupling each of the plurality of ring segments to an outer surface of a stationary component within the turbine engine using the at least one fastener.
In one embodiment, a first ring segment and a circumferentially-adjacent second ring segment are coupled to the outer surface of the stationary component such that a gap is defined therebetween to facilitate thermal expansion of the first ring segment with respect to the second ring segment. Further, in one embodiment, the at least one fastener is extended at an oblique angle to and/or parallel to the center axis of the ring segment. In the exemplary embodiment, the fastener is extended through a center portion of each ring segment. Moreover, in one embodiment, the plurality of ring segments each include a rub-tolerant material.
Exemplary embodiments of seal ring assemblies are described in detail above. The seal ring assemblies are not limited to use with the steam turbine described herein, but rather, the seal ring assemblies can be utilized independently and separately from other steam turbine components described herein. Moreover, the invention is not limited to the embodiments of the seal ring assemblies described above in detail. Rather, other variations of the seal ring assemblies may be utilized within the spirit and scope of the claims.
The above-described systems and method facilitate reducing an amount of steam that may flow past rotor blades and through a gap of a steam turbine. More specifically, the above-described systems and method facilitate mitigating steam flow losses by substantially sealing the gap. As a result, an amount of steam that may flow over the rotor blades is substantially reduced, which in turn increases the efficiency of the steam turbine. Accordingly, costs and/or time associated with maintaining and/or repairing the steam turbine are facilitated to be reduced.
While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.