Patent Application
20180080324
The subject matter disclosed herein relates to steam turbines. Specifically, the subject matter disclosed herein relates to a turbine inlet and related apparatus or system for providing steam flow into the first stage(s) of a turbine.
Steam turbines include static nozzle assemblies that direct flow of steam, a working fluid, into turbine blades connected to a rotating rotor. The steam is passed through a number of turbine stages, each stage including a row of stationary nozzles mounted to the outer casing and rotating blades mounted to a rotating rotor. The stationary nozzles direct flow of the steam into the blades, rotating the rotor.
In low pressure steam turbines, steam from a high pressure section feeds into the low pressure steam turbine through a low pressure turbine inlet. The turbine inlet includes a housing, a turbine inlet port in the housing, and an annular inlet chamber defined by the housing. The steam flows from a turbine inlet conduit, through the turbine inlet port, through a steam outlet of the inlet chamber, to the first stage nozzles and rotor blades. In many arrangements, the steam does not flow through the annular inlet chamber to the steam outlet evenly or uniformly, meaning the steam does not approach the steam outlet at equal angles at all locations around the steam outlet, or in equal mass flow at all locations around the steam outlet. For example, in many configurations, a disproportionately large portion of the steam flows in a direct stream to the steam outlet and the first stage of nozzles and rotor blades. Toward the periphery of the direct stream, some relatively small percentage of the steam arcs away from the steam outlet and enters the steam outlet at an angle of incidence deviated from a perpendicular to a tangent of the steam outlet where the steam enters the steam outlet. Some relatively small percentage of the steam at the periphery of the direct stream may push farther away from the steam outlet and follow a circumferential path of the annular inlet chamber, before the steam feeds radially inwardly and turns axially through a steam outlet into the first stage.
As a result of this uneven and/or non-uniform flow in the inlet chamber to the steam outlet, the steam does not enter the steam outlet evenly spaced around the circumference of the steam outlet or at uniform angles of incidence to the steam outlet. The steam that does flow circumferentially is turbulent, such that it loses velocity, resulting in energy losses. Also, uneven flow entering the first stage of the low pressure turbine results in a pressure imbalance on the rotor blades, which may stress and fatigue the rotor blades and the rotor, and reduces the life of each. This effect is continued throughout the subsequent stages of the turbine but with a lowering severity until the steam is evenly distributed around the circumference by the blades. Further, the non-uniform angles of incidence of steam at the steam outlet can range plus or minus 40 degrees, which can further cause pressure imbalance, and due to the indirect, non-optimum angles of approaching the components of the first stage, can considerably lower the degree of energy transferred to rotor rotation. Overall cylinder efficiency, because of each of the above reasons, is reduced.
Methods to address these problems include adding vanes inside the annular inlet chamber of the turbine inlet in an attempt to direct the incoming steam circumferentially, to more uniformly and evenly direct the flow of steam to and through the steam outlet. Due to the high-energy conditions inside the turbine inlet, namely the high pressure and velocity of the steam, physical components such as vanes attached inside the turbine inlet, have been found undesirable. Further, the extra components inside the turbine inlet necessitate additional inspections and maintenance, and decrease accessibility inside the turbine inlet. Additional maintenance entails additional shutdowns of the turbine, and less productivity.
Further, in steam turbine retrofits to address problems with uneven and/or non-uniform flow, there are limitations regarding modifications that can be made to the original inner and outer casing geometry, which limit possible solutions to address the uneven and/or non-uniform flow.
A first aspect of the disclosure includes a turbine inlet. The turbine inlet includes an annular housing, a main inlet port in the annular housing, a steam outlet in the annular housing, and a flow diversion port in the annular housing. The annular housing has an outer surrounding peripheral wall and a pair of axially spaced side walls, the annular housing defining an internal chamber. The main inlet port is in fluid communication with the internal chamber for transmitting steam into the internal chamber. The steam outlet is in fluid communication with the internal chamber for passing steam from the internal chamber into a first stage of the turbine, the steam outlet having a center axis. The flow diversion outlet is located and oriented such that flow from the flow diversion port has a center axis angled to avoid intersecting the center axis of the steam outlet.
A second aspect of the disclosure includes a turbine system. The turbine system includes a turbine inlet, a fluid supply, and a flow diversion supply conduit. The turbine inlet has an annular housing which includes a main inlet port therein, a steam outlet centrally positioned therein, a flow diversion port therein, and an outer surrounding peripheral wall and a pair of axially spaced side walls defining an internal chamber. The main inlet port is in fluid communication with the internal chamber for transmitting steam into the internal chamber, and the steam outlet is in fluid communication with the internal chamber for passing steam from the internal chamber into a first stage of a turbine of the turbine system. The flow diversion supply conduit couples the fluid supply to the flow diversion port. The fluid supply is configured to supply fluid into the internal chamber at a higher pressure than steam entering the internal chamber from the main inlet port.
A third aspect of the disclosure includes a method of retrofitting a turbine inlet in a turbine system. The method comprises opening a flow diversion port through an annular housing of a turbine inlet, connecting a flow diversion supply conduit to the flow diversion port, and connecting the flow diversion supply conduit to the fluid supply. The turbine inlet has the annular housing, a main inlet port in the annular housing, and a steam outlet centrally positioned in the annular housing. The annular housing has an outer surrounding peripheral wall and a pair of axially spaced side walls. The annular housing defines an internal chamber. The main inlet port is in fluid communication with the internal chamber for transmitting steam into the internal chamber. The steam outlet is in fluid communication with the internal chamber for passing steam from the internal chamber into a first stage of the turbine. Opening the flow diversion port includes facing the flow diversion port so flow from the flow diversion port has a center axis angled more than five degrees from the center axis of the steam outlet. The fluid supply is configured to supply fluid into the internal chamber at a higher pressure than steam entering the internal chamber from the main inlet port.
These and other features of this invention will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings that depict various embodiments of the disclosure, in which:
It is noted that the drawings of the invention are not necessarily to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings.
As an initial matter, in order to clearly describe the current disclosure it will become necessary to select certain terminology when referring to and describing relevant machine components within a steam turbine. When doing this, if possible, common industry terminology will be used and employed in a manner consistent with its accepted meaning. Unless otherwise stated, such terminology should be given a broad interpretation consistent with the context of the present application and the scope of the appended claims. Those of ordinary skill in the art will appreciate that often a particular component may be referred to using several different or overlapping terms. What may be described herein as being a single part may include and be referenced in another context as consisting of multiple components. Alternatively, what may be described herein as including multiple components may be referred to elsewhere as a single part.
In addition, several descriptive terms may be used regularly herein, and it should prove helpful to define these terms at the onset of this section. These terms and their definitions, unless stated otherwise, are as follows. As used herein, “downstream” and “upstream” are terms that indicate a direction relative to a position within the flow of a fluid, such as the working fluid through the turbine engine or, for example, the flow of steam through a turbine stage. The term “downstream” corresponds to the direction of flow of the fluid, and the term “upstream” refers to the direction opposite to the flow. The terms “forward” and “aft”, without any further specificity, refer to directions, with “forward” referring to the front or turbine end of the engine, and “aft” referring to the rearward or generator end of the engine. It is often required to describe parts that are at differing radial positions with regard to a center axis. The term “radial” refers to movement or position perpendicular to an axis. In cases such as this, if a first component resides closer to the axis than a second component, it will be stated herein that the first component is “radially inward” or “inboard” of the second component. If, on the other hand, the first component resides further from the axis than the second component, it may be stated herein that the first component is “radially outward” or “outboard” of the second component. The term “axial” refers to movement or position parallel to an axis. Finally, the term “circumferential” refers to movement or position around an axis. It will be appreciated that such terms may be applied in relation to the center axis of the turbine.
In operation, steam 24 enters a turbine inlet 26 of steam turbine 10 and is channeled through stationary vanes 22. Vanes 22 direct steam 24 downstream against blades 20. Steam 24 passes through the remaining stages imparting a force on blades 20 causing shaft 14 to rotate. At least one end of turbine 10 may extend axially away from rotor 12 and may be attached to a load or machinery (not shown) such as, but not limited to, a generator, and/or another turbine.
In one embodiment of the present invention as shown in
Main steam supply conduit 214 and main inlet port 212 can be located and oriented anywhere to direct steam into internal chamber 210, such that flow toward and through steam outlet 220 is not even and/or uniform, or such that flow toward and through steam outlet 220 can be redirected or diverted to improve its evenness and uniformity approaching and passing through steam outlet 220. In the example illustrated in
Main steam supply conduit 214 and main inlet port 212 can also be oriented to face less directly at the center of internal chamber 210 or the center of steam outlet 220, i.e., be more radially misaligned. Main steam supply conduit 214 and main inlet port 212 can face off-center with center of steam outlet 220 such that center axis 232 of steam flow directed from main steam supply conduit 214 is offset from center axis 224 of steam outlet 220 as far as a radius of steam outlet 220, or in some cases a diameter of steam outlet 220. An offset greater than a radius of steam outlet 220 can have steam outlet 220 outside a direct path of a majority of steam flow from main steam supply conduit 214.
Flow diversion port 216 and flow diversion supply conduit 218 can be oriented to direct fluid (e.g., steam, air, etc.) from flow diversion port 216 away from the center of internal chamber 210 or steam outlet 220, and divert steam from main inlet port 212 into a circumferential flow around steam outlet 220, wherein steam more evenly enters steam outlet 220 around the circumference of steam outlet 220, and at more uniform angles of incidence, as schematically depicted in
Depending on how much adjustment is desired for the main steam flow entering internal chamber 210 at main inlet port 212, a location and orientation can be anywhere in the annular housing 202. In some embodiments, a longitudinal axis 228 of flow diversion supply conduit 218, and/or a center axis 230 of flow exiting flow diversion port 216, avoids intersecting center axis 224 of steam outlet 220. Each flow diversion port 216 illustrated in
In some embodiments, flow diversion port 216 can be angled so no line extending within a periphery of flow diversion port 216 parallel to center axis 230 of flow diversion port 216 intersects center axis 224 of steam outlet 220, as illustrated in
In some of these cases discussed above, flow from flow diversion port 216 is directed into the main steam flow entering internal chamber 210 from main inlet port 212. Aiming flow diversion inlet 216 more directly into the path of steam entering inlet 200 through main inlet port 212 can have a greater impact in redirecting the flow circumferentially, which can allow reduction of the pressure and mass flow of diversion flow necessary to achieve a desired level of circumferential flow.
Flow diversion port 216 can have a smaller area than main inlet port 212. A smaller area can facilitate higher pressure to create more impact where the fluid enters internal chamber 210 from flow diversion port 216. The fluid entering inlet 200 through flow diversion port 216 can also have less mass flow than steam entering main inlet port 212. In various embodiments, for example, while many other mass flow values can be implemented, steam can enter inlet 200 through main inlet port 212 at about X kg/s while fluid can enter flow diversion inlet 216 at about X/30 kg/s. For example, in one case, steam can enter inlet 200 through main inlet port 212 at about 210 kg/s while fluid can enter flow diversion inlet 216 at about 7 kg/s. Again, this embodiment is merely one example, and a great range of values can be desirable and implemented. In this embodiment, with flow from flow diversion port 216 being directed into the main steam flow entering internal chamber 210 from main inlet port 212, the range of incidence of steam at steam outlet 220 can be reduced from plus or minus 40 degrees to plus or minus 15 degrees, or less.
Alternatively, flow diversion supply conduit 807 can be coupled to high pressure turbine 804. As with intermediate pressure turbine 806, the energy extracted from high pressure turbine 804 can be sufficient to achieve the desired circumferential flow, with relatively low energy loss that can be regained in excess from the improved, circumferential flow in the turbine inlet of low pressure turbine 802, and from reclaiming enthalpy (i.e., having a higher enthalpy fluid enter low pressure turbine 802). The shorter distance between intermediate pressure turbine 806 and low pressure turbine 802 than the distance between high pressure turbine 804 and low pressure turbine 802 can demand less equipment, space, and expense.
Also, high pressure turbine 804 extractions could be used to improve the inlet conditions of intermediate pressure turbine 806 inlet. The smaller the gap to reintroduce the extracted steam, the fewer stages that are bypassed and the more energy that is transferred to the rotor upstream of the inlet improved by a flow diversion port. The farther upstream in the turbine train the greater influence the extracted steam will have on the main steam flow into the inlet. The number of stages effected by the bypass increases, though, which may incur a performance penalty. There is a balance between extraction location and penalty incurred by the bypass.
Teachings of the disclosure, as illustrated relative to turbine systems 700, 800, can be implemented as a new design or retrofitted to an existing turbine system. For a retrofit, the outer casing 16 of turbine 10 (
In various embodiments, components described as being “coupled” to one another can be joined along one or more interfaces. In some embodiments, these interfaces can include junctions between distinct components, and in other cases, these interfaces can include a solidly and/or integrally formed interconnection. That is, in some cases, components that are “coupled” to one another can be simultaneously formed to define a single continuous member. However, in other embodiments, these coupled components can be formed as separate members and be subsequently joined through known processes (e.g., soldering, fastening, ultrasonic welding, bonding). In various embodiments, electronic components described as being “coupled” can be linked via conventional hard-wired and/or wireless means such that these electronic components can communicate data with one another.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.
When an element or layer is referred to as being “on”, “engaged to”, “connected to” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to”, “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
Spatially relative terms, such as “inner,” “outer,” “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
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 languages of the claims.
