JP5570182B2 - Steam turbine - Google Patents

Description

  The present invention is a steam turbine having an operating temperature of over 650 ° C., the steam turbine having a thermally loaded housing at least partially manufactured from a nickel-based alloy by casting technology. Related to things.

  A large steam power plant having an output range of about 1000 MW has a group of steam turbines, which are divided into a high pressure turbine, an intermediate pressure turbine and a constant pressure turbine (for example, L. Busse). et al., “World's highest capacity steam turbosets for the lignite-fired Lippendorf power station”, ABB ABB Review 6/1997, pages 13-22 (1997)). In FIG. 4 of the above article, it is shown that intermediately heated steam is fed tangentially to the intermediate pressure steam turbine from two opposite sides via corresponding valve units. Each unit has a stop valve (Stoppventil) and an intercept valve (Abfangventil).

  Currently, this size medium pressure steam turbine has a valve unit on each side of the turbine as shown in FIG. The intermediate pressure steam turbine 10 shown in FIG. 1 parallel to the machine axis 16 in the line of sight has an outer housing 11 and an inner housing 12, both housings 11, 12 being in relation to the axis 16. Are concentrically formed. Inner housing 12 surrounds a rotatably supported rotor (not shown) with an associated wing arrangement. The intermediate superheated steam flows into the inner housing 12 from the two sides facing each other through the steam inlets 13 and 14 in the tangential direction and into the inner housing 12 through the spirally shaped inlet region, where it changes axially. Directed to load the rotor blade array and out again through the steam outlet 15. The supply of steam performed via the steam supply lines 17 and 18 is affected by the two valve units VE1 and VE2. A comparable valve unit is known, for example, from WO-A1-03 / 093653.

  The valve units VE1 and VE2 shown in FIG. 1 mainly consist of a stop valve part V11; V21 and a control valve part V12; V22, each of which can be operated by a (hydraulic) drive device. is there. The valves V11, V12, V21, and V22 have a substantially spherical shape inside the valve unit as shown in FIG. 2 of WO-A1-03 / 093653. For large steam power plants (about 1100 MW), the spherical stop valve part V11; V21 typically weighs 39 tons (for a diameter of 1100 mm) and the spherical control valve part V12; V22 is typical Specifically, it has a weight of 28 tons (for a diameter of 815 mm). If the housing to which it belongs is manufactured as a unitary casting in a general-purpose format, this casting has a weight of more than 60 tons.

For steam turbines with operating temperatures in excess of 650 ° C., the valve unit housing of the valve unit exposed to full steam pressure must be manufactured from a nickel-based alloy. However, this has the following drawbacks. That is,
The cost per kilogram of material is extremely high.

  Basically, it is difficult to process the inner surface of a workpiece with a nickel-based alloy.

  It is difficult to find a manufacturer for casting such a large nickel-based alloy workpiece.

  Based on the size of the cast product, segregation of individual elements occurs during casting, which results in a defect area having a non-uniform composition in the workpiece. In this case, the degree of segregation is related to the size of the workpiece.

  It is an improvement of the steam turbine of the type mentioned at the outset to eliminate the disadvantages of the prior art and to provide a steam turbine that stands out by reducing the size of components cast in particular from nickel-based alloys.

  In order to solve this problem, in the configuration of the present invention, the housing is divided into a plurality of small housing parts, and these housing parts are joined together to form a housing together for ease of manufacture. I was doing it.

  That is, in the present invention, a large casting made of one material is divided into a plurality of small castings made of the same material, and the plurality of small castings are manufactured separately, and then bonded to the material ( stoffschluessig) coupled to each other. An important point of the solution of the present invention is to divide the necessary large components made of nickel-base alloy into a plurality of small partial components, which are manufactured as separate castings and then to each other Combined. Such a treatment is particularly important and advantageous, for example for very large turbines with a power output exceeding 500 MW. The treatment according to the invention (there are several partial components, each of which is small in size or weight) can be applied in a steam turbine within the framework of the invention to a valve unit and its housing arranged in the steam turbine. It can be applied not only to the inner housing of the steam turbine.

  In another configuration of the invention, at least some of the housing portions are welded together to form the housing. For nickel-based alloys, the weld seam, as compared to steel, only slightly reduces the creep resistance when loaded with high internal pressure, thus ensuring a high mechanical strength of the welded member. In this case, it is advantageous if the housing parts are welded together in a plane oriented in the direction perpendicular and / or parallel to the direction of flow of the steam.

  In another configuration of the invention, the steam turbine is an intermediate pressure steam turbine and the housing consisting of a plurality of small housing parts is the inner housing of the intermediate pressure steam turbine. In particular, the inner housing is divided into at least two partial shells along a dividing plane that lies parallel to the axis of the steam turbine, and the reinforcing element, in particular the shaft, is used to mechanically reinforce the inner housing. It is advantageous if a shrink ring distributed in the direction is provided and the reinforcing element firmly surrounds the inner housing.

  In another configuration of the invention, the steam turbine is an intermediate pressure steam turbine and at least one valve unit is disposed at the steam inlet of the intermediate pressure steam turbine to control the supply of steam to the intermediate pressure steam turbine. The housing divided into a plurality of small housing parts is the housing of at least one valve unit.

  The intermediate pressure steam turbine is provided with two steam inlets located opposite each other, each of which has a valve unit assigned thereto, each of which has a plurality of small housing parts. It is advantageous to divide into two.

  In another configuration of the present invention, each valve unit includes a first valve and a second valve arranged one after the other in the flow direction, and the first valve and the second valve Are housed together in a housing, the first valve being formed as a stop valve and the second valve being formed as a control valve.

  In particular, the housing of each valve unit for the first and second valves each has one substantially spherical housing part, each spherical housing part being divided into a plurality of partial shells, Each of these partial shells is joined together using at least one weld seam extending in the flow direction.

  In this case, furthermore, the housing of each valve unit has a steam supply line leading to the first valve, and the steam supply line is formed as a respective integral housing part and is welded in the circumferential direction. The seam is connected to the housing part of the first valve.

  Still further, the housing of each valve unit has a connecting line extending from the second valve, the connecting line being formed as a respective integral housing part and being welded by a circumferentially extending weld seam. It is connected to the housing part of the two valves.

  In an advantageous configuration for obtaining a high mechanical strength despite the reduction in material, a reinforcing element, in particular in the form of a shrink ring, is provided to mechanically reinforce the housing, The housing is tightly enclosed at different points, in particular in the region of the spherical housing part.

  However, in another configuration which is advantageous for reducing the proportion of nickel-based alloy, the housing of each valve unit is the inner part of a double-walled housing structure, the inner part being made of a nickel-based alloy, The outer part is made of steel.

  In another configuration of the invention, the steam turbine is an intermediate pressure steam turbine and at least one valve unit is disposed in the intermediate pressure steam turbine to control the supply of steam to the intermediate pressure steam turbine, The unit has at least two similar valves that operate in parallel with each other. By dividing one valve into two valves which are parallel or parallel to each other, the valve can be designed to be small, which correspondingly reduces the size of the castings to which it belongs. In this case, it is advantageous if at least two valves are formed as control valves, the steam is supplied separately to the control valves and the steam is brought together behind the control valves.

  However, in another configuration of the invention, at least two valves are formed as stop valves, steam is supplied separately to the stop valves and formed as control valves behind both stop valves in the flow direction. A third valve is arranged to collect the steam from both stop valves in the third valve.

  Both stop valves are connected to the control valve via a connecting line, the control valve is connected to the steam turbine via a connecting line, and the connecting line is oriented perpendicular to the connecting line. It is advantageous.

  Alternatively, the coupling line may have a Y-shaped arrangement with the connection line.

  In yet another configuration, the connecting conduit has a fork-shaped arrangement with the connecting conduit.

1 shows a large medium pressure steam turbine with a steam supply on both sides and an associated valve unit for controlling the steam supply, suitable for carrying out the invention, in cross section perpendicular to the machine axis. FIG. FIG. 2 is a perspective view showing a housing divided into partial elements of the valve unit shown in FIG. 1 according to an embodiment of the present invention. FIG. 3 is a perspective view of another embodiment of the present invention showing the housing of the valve unit shown in FIG. 1 divided into partial elements and reinforced by an additional shrink ring. FIG. 7 is a view schematically showing another embodiment of the present invention, in which the stop valve of the valve unit shown in FIG. 1 is divided into two small stop valves working in parallel. . It is a figure similar to FIG. 4, and is a figure which shows the Example by which a steam pipe line or a steam pipe is arrange | positioned by the Y-shaped arrangement configuration. FIG. 5 is a view similar to FIG. 4, showing an embodiment in which steam pipes or steam pipes are arranged in a fork-shaped arrangement. FIG. 2 is a perspective view showing an inner housing of the steam turbine shown in FIG. 1 divided into partial elements.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 2 is a perspective view of the housing G of the valve unit VE1 shown in FIG. 1 divided into partial elements according to an embodiment of the present invention. The housing G is divided into four housing parts G1, G2, G3, G4, for example in the direction of the flow of steam flowing in through the steam supply line 17 and flowing out through the connection line 19. The housing part G1 is a connection line 19 with a connection flange 19 '. The housing part G4 is a steam supply line 17. The two housing parts G2, G3 are formed in a substantially spherical shape and are part of two valves V11, V12, ie a stop valve and a control valve. Both housing parts G2, G3 consist of two shell halves, namely an upper shell half G22; G32 and a lower shell half G21; G31.

  In order to allow the valve unit VE1 to withstand the internal pressure of the flowing steam, the half shells G21, G22; G31, G32 extend in parallel to the flow direction (longitudinal or horizontal) welding seams S1, They are connected to each other by S4. The housing parts G1, G2, G3, G4 are connected to each other by welded seams S1, S3, S5 extending in the circumferential direction.

  In order to mechanically reinforce the longitudinally welded spherical housing parts G2, G3, the tube pieces of these housing parts G2, G3 are additionally provided with outer reinforcing elements, in particular according to FIG. 20, 21 can be provided, or an interference fit. Instead of or in addition to the shrink rings 20, 21, it is also possible to use flanges that are screwed in the axial direction for reinforcement. In FIG. 3, only one contraction ring 20; 21 each is an interference fit in the tube piece for driving the valve, but a further contraction ring is provided between the two spherical housing parts G2 and G3 of the valve. And between the housing part G2 and the connecting flange 19 '. These further shrink rings must be moved in the axial direction in order to allow longitudinal welding (weld seams S2, S4) and then heated and moved to their final position.

  It is advantageous if the shrink rings 20, 21 have a larger coefficient of thermal expansion than the housing G (eg the ring is made of austenitic steel and a nickel base alloy is used for the housing). . Alternatively, however, the ring may also consist of a plurality of ring segments, which can be assembled together as disclosed, for example, in DE-A1-197558160.

  In order to reduce the weight of individual castings or housing parts made of nickel-base alloys, the cold sections of these housing parts can be replaced by inexpensive steels with a similar expansion coefficient as nickel-base alloys, for example 1-2% CrMoV- It is advantageous to manufacture from cast steel. A similar coefficient of thermal expansion is useful because only a small amount of stress is created in the part during welding and operation.

  Further improvements can be achieved by forming the valve unit in a double wall. When configured in this way, only the inner part is formed from a nickel-base alloy with a longitudinal weld seam and possibly additionally reinforced by a shrink ring. The outer part is manufactured from steel and possibly reinforced by flanges and / or longitudinal weld seams and / or shrink rings. In this case, the medium is circulated in the intermediate chamber between the walls, thereby limiting the high temperature in the inner part and reducing the heat transfer to the outer part. The heat absorbed by this medium can be used to improve the efficiency of the steam cycle.

  The intermediate chamber between the inner part and the outer part can in particular be filled with cooling steam, in which case the pressure of the cooling steam can be higher or lower than the steam pressure inside the inner part. Other embodiments evacuate the intermediate chamber, for example, by connecting the outer part and the condenser via a conduit, thereby creating a near vacuum in the intermediate chamber. This vacuum acts as a thermal insulator between the inner and outer parts and lowers the temperature in the outer part. This thermal insulation effect is further enhanced by providing the inner wall of the outer part with a highly reflective surface, for example by means of a coating layer. This is because heat transfer is reduced by radiation.

  However, the reduction of individual partial components can also be achieved by “functional” decomposition. In this case, for example, instead of a large valve with a large spherical housing part in the valve unit of a steam turbine, two or more small valves working in parallel with each other with a correspondingly small spherical housing part are used. Is done. In such a configuration, steam for the steam turbine is supplied separately to two or more small valves and is grouped together behind these valves (eg, using a Y-shaped tube member) at one location. In the steam turbine. Such a valve split configuration can be performed on both sides of the steam turbine if the supply is performed on opposite sides.

  Such a “functional” disassembly or division can also be advantageously used in the configuration of the valve unit shown in FIGS. For example, the spherical housing part G3 of the stop valve V11; V21 is significantly larger than the spherical housing part G2 of the control valve V12; V22, so that instead of the stop valves in both valve units VE1, VE2, two or more of each other It is advantageous to use stop valves working in parallel, in which case the steam of these stop valves is collected in a (only one) control valve located downstream and from there into the steam turbine.

  FIG. 4 to FIG. 6 show three different embodiments in such a division format. In FIG. 4, the valve unit VE3 has one control valve V1 provided with the drive device A1 and two stop valves V2 and V3 provided with the drive devices A2 and A3. Steam is supplied to stop valves V2, V3 by steam supply lines 22, 23 extending from below perpendicular to the plane of the drawing. The stop valves V2, V3 are connected to (only one) control valve V1 via two coupling lines 24, 25. The control valve V1 supplies the combined steam to a steam turbine (not shown) via a connection line 19 with a connection flange 19 '. The coupling lines 24, 25 are in this case oriented perpendicular to the connection line 19.

  In an alternative embodiment (FIG. 5), the coupling lines 24 ', 25' and the connecting line 19 of the valve unit VE4 have a Y-shaped arrangement. In another alternative embodiment (FIG. 6), the connecting lines 24 ", 25" and the connecting line 19 of the valve unit VE5 have a fork-shaped arrangement. In all three embodiments, the Y-shaped tube member can be omitted by consolidating the steam flow at the control valve V1.

  When the principles of the present invention are applied to the inner housing 12 of the steam turbine 10 (FIG. 10), the inner housing divided in the first dividing plane T1 for accessibility as shown in FIG. The twelve partial shells TS1, TS2 can be further divided in the axial direction and / or circumferential direction, for example along a dividing plane T2 extending perpendicular to the axis (housing parts G7, G8 in FIG. 7). This can reduce the size and weight of the individual castings. Again, the mechanical strength can be increased by an additional shrink ring surrounding the outside of the inner housing 12.

  10 Medium Pressure Steam Turbine, 11 Outer Housing, 12 Inner Housing, 13, 14 Steam Inlet, 15 Steam Outlet, 16 Axis, 17, 18 Steam Supply Line, 19 Connection Line, 19 'Connection Flange, 20, 21 Shrink Ring , G housing (valve unit), G1, G2, G3, G4, G5, G6, G7, G8 housing part, G21, G22, G31, G32 partial shell, S1, S2, S3, S4, S5 welded seam, T1, T2 split plane, VE1, VE2, VE3, VE4, VE5 valve unit, V1, V2, V3, V11, V12, V21, V22 valves, 22, 23 steam supply lines, 24, 24 ', 24 ", 25, 25 ', 25' 'connecting pipe

Claims (16)

A steam turbine (10) having an operating temperature of over 650 ° C., wherein the steam turbine (10) is at least partially manufactured from a nickel base alloy by a casting technique (12, G In order to simplify the manufacture of the housing (12, G), a plurality of small housing parts (G1, G2, G3, G4; G21, G22, G31, G32; G5, G6, G7, G8), these housing parts being joined together to form a housing (12, G) together , the steam turbine being a medium pressure steam turbine (10), In order to control the steam supply to the intermediate pressure steam turbine (10), at least one valve unit (VE1, VE2, VE3, VE4, VE5) is connected to the steam inlet of the intermediate pressure steam turbine (10). A housing arranged at the mouth (13, 14) and divided into a plurality of small housing parts (G1, G2, G3, G4; G21, G22, G31, G32; G5, G6) has at least one valve unit (VE1, VE2, VE3, VE4, VE5) and the first valve (V11, V21) in which each valve unit (VE1, VE2) is arranged one after the other in the flow direction. Two valves (V12, V22), the first valve (V11, V21) and the second valve (V12, V22) are housed together in a housing (G), A steam turbine characterized in that the first valve (V11, V21) is formed as a stop valve and the second valve (V12, V22) is formed as a control valve .   At least some of the housing parts (G1, G2, G3, G4; G21, G22, G31, G32; G5, G6, G7, G8) are welded together to form the housing (12, G). The steam turbine according to claim 1, wherein (S1, S2, S3, S4, S5).   In a plane in which the housing parts (G1, G2, G3, G4; G21, G22, G31, G32; G5, G6) are oriented in the direction perpendicular to and / or parallel to the flow direction of the steam The steam turbine of claim 2, wherein the steam turbines are welded together.   Up to 1 to 3, wherein the steam turbine is an intermediate pressure steam turbine (10) and the housing consisting of a plurality of small housing parts (G7, G8) is the inner housing (12) of the intermediate pressure steam turbine (10) The steam turbine according to claim 1.   The inner housing (12) is divided into at least two partial shells (TS1, TS2) along a dividing plane (T1) located parallel to the axis (16) of the steam turbine, and the inner housing (12 5) is provided, in particular a shrink ring distributed in the axial direction, which tightly surrounds the inner housing (12). Steam turbine. The intermediate pressure steam turbine (10) is provided with two steam inlets (13, 14) positioned to face each other, and one valve unit (VE1, VE2) is provided in each of the steam inlets (13, 14). The housing (G) of both valve units (VE1, VE2) is divided into a plurality of small housing parts (G1, G2, G3, G4; G21, G22, G31, G32; G5, G6). The steam turbine according to claim 1 . The housing (G) of each valve unit (VE1, VE2) for the first and second valves (V11, V21; V12, V22) has one substantially spherical housing part (G2, G3), respectively. Each of the spherical housing parts (G2, G3) is divided into a plurality of partial shells (G21, G22; G31, G32), each of these partial shells extending in the flow direction. The steam turbine according to claim 1 , wherein the steam turbines are coupled together using (S2; S4). The housing (G) of each valve unit (VE1, VE2) has a steam supply line (17, 18) communicating with the first valve (V11, V21), and the steam supply line (17, 18). Are formed as respective integral housing parts (G4) and are connected to the housing part (G3) of the first valve (V11, V21) by a circumferentially extending weld seam (S5). The steam turbine according to claim 7 . The housing (G) of each valve unit (VE1, VE2) has a connecting line (19) extending from the second valve (V12, V22), and each connecting line (19) is an integral housing. Steam turbine according to claim 7 or 8 , wherein the steam turbine is formed as part (G1) and is connected to the housing part (G2) of the second valve (V12, V22) by a circumferentially extending weld seam (S1). . In order to mechanically reinforce the housing (G), a reinforcing element, in particular in the form of a shrink ring (20, 21), is provided, the reinforcing element being particularly spherical in shape at different locations. The steam turbine according to claim 7 , which is tightly enclosed in the region of the housing part (G2, G3). The housing (G) of each valve unit (VE1, VE2) is the inner part of a double-walled housing structure, the inner part being made of nickel base alloy and the outer part being made of steel. The steam turbine according to any one of 7 to 9 . A steam turbine (10) having an operating temperature of over 650 ° C., wherein the steam turbine (10) is at least partially manufactured from a nickel base alloy by a casting technique (12, G In order to simplify the manufacture of the housing (12, G), a plurality of small housing parts (G1, G2, G3, G4; G21, G22, G31, G32; G5, G6, G7, G8), these housing parts being joined together to form a housing (12, G) together, the steam turbine being a medium pressure steam turbine (10), In order to control the supply of steam to the intermediate pressure steam turbine (10), at least one valve unit (VE3, VE4, VE5) is arranged in the intermediate pressure steam turbine (10), Knit (VE3, VE4, VE5) can have at least two similar valves (V2, V3) to operate in parallel with each other, at least two valves (V2, V3) is designed as a stop valve The steam is separately supplied to the stop valve, and a third valve (V1) formed as a control valve is arranged behind the both stop valves (V2, V3) in the flow direction, and the third valve A steam turbine characterized in that steam from both stop valves (V2, V3) is collected in the valve (V1) . The steam turbine according to claim 12 , wherein at least two valves are formed as control valves, the steam is supplied separately to the control valves, and the steam is collected behind the control valves. Both stop valves (V2, V3) are connected to a control valve (V1) via coupling pipes (24, 25; 24 ', 25'; 24 ", 25"). 13 ) is connected to the steam turbine via a connecting line (19) and the connecting lines (24, 25) are oriented perpendicular to the connecting line (19). Steam turbine. Both stop valves (V2, V3) are connected to a control valve (V1) via coupling pipes (24 ', 25'), and the control valve (V1) is connected to steam via a connecting pipe (19). The steam turbine according to claim 12 , wherein the steam turbine is connected to the turbine and the coupling lines (24 ′, 25 ′) form a Y-shaped arrangement with the connection line (19). Both stop valves (V2, V3) are connected to a control valve (V1) via coupling pipes (24 ″, 25 ″), and the control valve (V1) is connected via a connecting pipe (19). The steam turbine according to claim 12 , wherein the connecting pipe ( 24 ″ , 25 ″ ) and the connecting pipe (19) form a fork-shaped arrangement.

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