US20120017592A1 - Steam turbine and method for adjusting thrust forces thereof - Google Patents
Steam turbine and method for adjusting thrust forces thereof Download PDFInfo
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- US20120017592A1 US20120017592A1 US13/171,563 US201113171563A US2012017592A1 US 20120017592 A1 US20120017592 A1 US 20120017592A1 US 201113171563 A US201113171563 A US 201113171563A US 2012017592 A1 US2012017592 A1 US 2012017592A1
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- Prior art keywords
- steam
- dummy member
- valve
- steam turbine
- pressure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D3/00—Machines or engines with axial-thrust balancing effected by working-fluid
- F01D3/04—Machines or engines with axial-thrust balancing effected by working-fluid axial thrust being compensated by thrust-balancing dummy piston or the like
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
- F01D25/16—Arrangement of bearings; Supporting or mounting bearings in casings
Definitions
- the present invention relates to a steam turbine and a method of adjusting a thrust force of the steam turbine, particularly regarding a steam turbine and a method of adjusting a thrust force of the steam turbine which are capable of balancing of a thrust force acting on a rotor shaft of the steam turbine which includes at least a high-pressure (HP) blade cascade, an intermediate-pressure (IP) blade cascade and a plurality of dummy members that are attached to a common rotor shaft.
- HP high-pressure
- IP intermediate-pressure
- the steam turbine Since the rotor shaft is subjected to the thrust force acting thereon, the steam turbine is provided with a thrust bearing. With a limited load capacity of the bearing, it is necessary to design the steam turbine in consideration of a thrust balance so that the thrust force acting on the rotor shaft does not exceed the load capacity of the bearing under any operating condition.
- the dummy members (dummy pistons) and the blade cascades are attached to the same rotor shaft, so as thrust forces in a counter-thrust direction are generated by the dummy members to balance the forces acting in an axial direction of the entire rotor shaft.
- the thrust force acting on the rotor shaft is kept within the scope of the load capacity of the bearing under any operation condition.
- FIG. 13 shows an outline view regarding a conventional steam turbine under a normal operating condition, the conventional steam turbine being provided with dummy members for adjusting the thrust forces.
- a turbine casing (not shown) is formed around a rotor shaft 10 .
- the turbine casing includes an inlet part (not shown) for introducing high-pressure (HP) main steam 22 , an inlet part (not shown) for introducing reheat steam 24 and an inlet part (not shown) for introducing low-pressure (LP) main steam 26 .
- HP high-pressure
- LP low-pressure
- a HP blade cascade 2 to which the HP main steam is supplied, an IP blade cascade 4 to which the reheat steam 24 is supplied and a low-pressure (LP) blade cascade 6 to which the LP main steam 26 is supplied are attached to the rotor shaft 10 in this order.
- the IP blade cascade 4 and the LP blade cascade 6 have steam inlets that are open to one side, whereas the HP blade cascade 2 has a steam inlet is open to other side being opposite to the one side.
- a high-pressure (HP) dummy member 12 is provided between the steam inlet of the HP blade cascade 2 and the steam inlet of the IP blade cascade 4 .
- an intermediate-pressure (IP) dummy member 14 and a low-pressure (LP) dummy member 16 are provided in this order. Further, a thrust balance conduit 30 is provided so as to communicate the outlet side of the IP dummy member 14 to a latter half of the IP blade cascade 4 .
- the HP main steam 22 from a boiler and the like enters the HP blade cascade 2 .
- the HP main steam 22 gives a rotary force to the rotor shaft 10 while the steam passes through the HP blade cascade 2 .
- the steam that has done the work through the HP blade cascade 2 drops the pressure and the temperature gradually and is discharged out of the steam turbine 1 as a low-temperature reheat steam 28 .
- the low-temperature reheat steam 28 discharged out of the steam turbine 1 is reheated by a reheat boiler (not shown) to be the reheat steam 24 .
- the IP reheat steam 24 that is reheated by the reheat boiler gives the rotary force to the rotor shaft 10 and gradually reduces the pressure and the temperature while the reheat steam 24 passes through the IP blade cascade 4 .
- the LP main steam 26 gives the rotary force to the rotor shaft 10 and gradually reduces the pressure and the temperature while the LP main steam 26 passes through the LP blade cascade 6 .
- a part of the high-pressure (HP) main steam 22 passes by the high-pressure (HP) dummy member 12 and a part of the low-temperature reheat steam 28 that has passed through the HP blade cascade and has reduced the temperature and the pressure, passes by the intermediate-pressure (IP) dummy member 14 and the low-pressure (LP) dummy member 16 .
- the thrust forces acting on the rotor shaft 10 at the cascades and the dummy members on the rotor shaft are represented by encircled numbers, 1 to 6 and an example regarding a set of the pressure values between adjacent pair of each blade cascade (dummy parts) are shown in FIG. 13 .
- the thrust forces indicated by encircled numbers 1 , 2 , 3 , 4 , 5 and 6 denote the thrust forces acting on the LP dummy member 16 , the IP dummy member 14 , the HP blade cascade 2 , the HP dummy member 12 , the IP blade cascade 4 and the LP blade cascade 6 , respectively.
- the thrust force acing on each of the blade cascades can be computed based on the gas pressure force working on each blade cascade and the thrust force acting on each of the dummy members can be computed based on a pressure difference between both sides of each dummy member and a cross-sectional area of each dummy member.
- the dummy members 12 , 14 and 16 , and the thrust balance conduit 30 are provided so as to balance the thrust forces by the steam pressure.
- the thrust force acting on the HP dummy member 12 roughly serves as a counterbalance to the thrust force acting on the HP blade cascade 2
- the thrust acting on the IP dummy member 14 roughly serving as a counterbalance to the thrust force acting on the IP blade cascade 4
- the thrust force acting on the LP dummy member 16 roughly serving as a counterbalance to the thrust force acting on the LP blade cascade 6 .
- the resultant thrust force acting on the whole steam turbine 1 is balanced.
- the resultant thrust force needs to be brought into balance not only in a case where the steam turbine is operated under a normal operating condition but also in a case where either the HP main steam supply or the reheat steam supply is stopped.
- FIG. 14 shows the outline of the state of the steam turbine provided with conventional dummy parts for adjusting thrust balance, when the supply of the HP main steam 22 is stopped.
- FIG. 15 shows the outline of the state of the steam turbine provided with conventional dummy parts for adjusting thrust balance, when the supply of the reheat steam and the LP main steam is stopped.
- the pressure at the outlet of the IP dummy member 14 becomes a level of vacuum pressure and in response to the vacuum pressure level, the thrust force represented by the encircled numeral 2 as shown in FIG. 15 increases.
- the pressure difference between both sides of the IP blade cascade 4 becomes approximately 0.
- the thrust force represented by the encircled numeral 5 becomes approximately 0.
- the resultant thrust force acting toward the direction of the IP dummy member side increases.
- the thrust force generated in the HP blade cascade 2 represented by the encircled numeral 3 is approximately the same as that of a normal operation condition, whereas the thrust force represented by the encircled numeral 2 generated in the HP dummy member 12 increases by an amount corresponding to the vacuum pressure level at the outlet of the HP dummy member 12 .
- the thrust force acting in the direction of the HP dummy member (rightward in FIG. 15 ) increase.
- the increase of the thrust force generated in the IP system is greater than the increase of the thrust force generated in the HP system. Accordingly, the resultant thrust force generated in the whole steam turbine 1 increases in the leftward direction in FIG. 15 . Thus, the resultant thrust force acting on the whole steam turbine is not balanced.
- the HP dummy member 12 is upsized so that thrust force in the rightward direction increases and the resultant thrust force is balanced.
- the upsizing of the HP dummy member 12 spoils the balancing in the normal operation and thus, this approach is not appropriate.
- the IP dummy member 14 is downsized and the LP dummy member 16 is upsized.
- Patent Reference 1 discloses another technology; according to this technology, thrust forces acting on the steam turbine are evaluated based on the measured data such as bearing temperatures. Based on the results of the measurements, the thrust forces acting on the dummy members can be adjusted in an electronic control approach, and the resultant thrust force developed in the whole steam turbine is brought into balance.
- Patent Reference 1 JP1996-189302
- Patent Reference 1 where the balancing of the thrust forces is performed by use of an electric control, there is a possibility that the reliability of the electric system may cause a problem.
- the present invention provides a steam turbine having at least a high-pressure (HP) blade cascade, an intermediate-pressure (IP) blade cascade and a plurality of dummy members that are attached to a common rotor shaft.
- the steam turbine may include, but is not limited to:
- IP intermediate-pressure
- a pressure reducing unit that reduces a pressure difference between both sides of a target dummy member of said plurality of the dummy members when the steam flow into the IP chamber stops, the target dummy member having one side communicating with a part of the IP chamber;
- control unit that controls the pressure reducing unit based on a detection result obtained by the detection unit.
- the thrust force generated at the IP dummy member when the steam flow into the IP chamber stops can be eliminated.
- the diameter of the LP dummy member can be reduced and the thrust forces acting on the rotor of the steam turbine can be balanced in the entire operation range of the steam turbine without using the electric control of the complicated system.
- the above pressure reducing unit may include, but is not limited to, a first conduit that connects the both sides of the target dummy member and a first valve that is provided in the first conduit to adjust the pressure difference between the both sides of the target dummy member.
- the above steam turbine may further include:
- control unit may control the third valve to open so as to generate the pressure difference between the both sides of the target dummy member.
- the above pressure reducing unit may include, but is not limited to:
- a second valve that is provided in the second conduit to adjust the difference between the both sides of the target dummy member.
- the second valve may be closed when the steam flow into the IP chamber stops.
- the second conduit is often provided even in the conventional steam turbines.
- the pressure reducing unit can be provided by simply fitting the second valve to the existing second conduit without newly installing a conduit to the steam turbine.
- the remodeling can be easily accomplished.
- the above steam turbine may further include:
- the above steam turbine may also include:
- control unit may control the third valve to open so as to generate the pressure difference between the both sides of the target dummy member.
- the present invention provides a method of adjusting a thrust force of a steam turbine having at least a HP blade cascade, an IP blade cascade and a plurality of dummy members that are attached to a common rotor shaft.
- the method may include, but is not limited to, the step of reducing a pressure difference between both sides of a target dummy member of said plurality of the dummy members when the steam flow into the IP chamber stops, the target dummy member having one side communicating with a part of the IP chamber.
- the pressure difference between the both sides of the target dummy member may be reducible by use of a first valve provided in a first conduit that connects the both sides of the target dummy member.
- the pressure difference may be generated between the both sides of the target dummy member by opening a third valve which is provided in a third conduit that connects the one side of the target dummy member to an outlet of the IP chamber.
- the pressure difference between the both sides of the target dummy member may be reducible by use of a second valve provided in a second conduit that connects the part of the IP chamber and the one side of the target dummy member.
- the pressure difference may be generated between the both sides of the target dummy member by opening a third valve which is provided in a third conduit that connects the one side of the target dummy member to an outlet of the IP chamber.
- the steam turbine and the method of adjusting the thrust force of the steam turbine can be provided which are operable to balance the thrust forces in the entire operation range of the steam turbine without upsizing the LP dummy member, as well as, without using the electric control of a complicated system.
- FIG. 1 shows a configuration of a single-casing reheat steam turbine provided with a plurality of dummy members for adjusting thrust forces, according to a first preferred embodiment of the present invention.
- FIG. 2 shows an outline of a normal operating state of the steam turbine provided with the dummy members for adjusting thrust forces, according to the first preferred embodiment of the present invention.
- FIG. 3 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces when the supply of the HP main steam is stopped, according to the first preferred embodiment of the present invention.
- FIG. 4 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces when the supply of the reheat steam and the LP main steam is stopped, according to the first preferred embodiment of the present invention.
- FIG. 5 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces in a case where a valve is in an abnormal condition in the normal operating state of the steam turbine, according to the first preferred embodiment of the present invention.
- FIG. 6 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces, after taking a countermeasure against the malfunction of the valve in the normal operating state of the steam turbine, according to the first preferred embodiment of the present invention.
- FIG. 7 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces in a case where another valve is in an abnormal condition in the normal operating state of the steam turbine, according to the first preferred embodiment of the present invention.
- FIG. 8 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces, after taking a countermeasure against the malfunction of said another valve in the normal operating state of the steam turbine, according to the first preferred embodiment of the present invention.
- FIG. 9 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces, according to the first preferred embodiment of the present invention, in a case where the function of a valve is out of order while the supply of the reheat steam and the LP main steam is stopped.
- FIG. 10 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces, according to the first preferred embodiment of the present invention, after taking a countermeasure against the malfunction of the valve while the supply of the reheat steam and the LP main steam is stopped.
- FIG. 11 shows an outline of a HP-IP steam turbine provided with the dummy members for adjusting thrust forces, according to a second preferred embodiment of the present invention.
- FIG. 12 shows an outline of a HP-IP steam turbine provided with the dummy members for adjusting thrust forces, according to a third preferred embodiment of the present invention.
- FIG. 13 shows an outline of a normal operating state of the steam turbine provided with conventional dummy members.
- FIG. 14 shows an outline of a state of the steam turbine provided with conventional dummy parts for adjusting thrust balance, when the supply of the HP main steam is stopped.
- FIG. 15 shows an outline of a state of the steam turbine provided with conventional dummy parts for adjusting thrust balance, when the supply of the reheat steam and the LP main steam is stopped.
- FIG. 1 shows a configuration of a single-casing reheat steam turbine provided with a plurality of dummy members for adjusting thrust forces, according to a first preferred embodiment of the present invention.
- a low-pressure (LP) casing 32 and a HP-IP casing 34 are formed around a rotor shaft 10 .
- the HP-IP casing 34 is provided with a high-pressure (HP) steam inlet 23 through which HP steam 22 is supplied to the steam turbine and a reheat steam inlet 25 through which reheat steam 24 is supplied to the steam turbine.
- the LP casing 32 is provided with a low-pressure (LP) steam inlet 27 through which LP steam 26 is supplied to the steam turbine.
- a HP blade cascade 2 to which the HP main steam is supplied
- an intermediate-pressure (IP) blade cascade 4 to which the reheat steam 24 is supplied
- a low-pressure (LP) blade cascade 6 to which the LP main steam 26 is supplied in this order.
- steam inlet sides of the IP blade cascade 4 and the LP blade cascade 6 are arranged such that the steam streams through the IP blade cascade 4 and the LP blade cascade 6 in the same direction, whereas a steam inlet side of the HP blade cascade 2 is arranged such that the steam streams through the HP blade cascade 2 in the opposite direction.
- a HP dummy member 12 is provided between the steam inlet side of the HP blade cascade 2 and the steam inlet side of the IP blade cascade 4 .
- an IP dummy member 14 and a LP dummy member 16 are provided in this order.
- a thrust balance conduit 30 is provided to communicate the steam outlet side of the IP dummy member 14 to a part of the IP blade cascade 4 .
- FIG. 2 shows an outline of a normal operating state of the steam turbine provided with the dummy members for adjusting thrust forces.
- a normal operating state means an operating state of the steam turbine in which all of the HP steam 22 , the reheat steam 24 and the LP steam 26 are supplied to the steam turbine.
- the diameter of the IP dummy member 14 is upsized in comparison with the conventional dummy member 14
- the diameter of the LP dummy member 16 is downsized in comparison with the conventional dummy member 16 .
- a conduit 42 is provided to communicate the steam inlet side of the IP dummy member 14 to the steam outlet side thereof and a valve 43 is provided on the conduit 42 .
- a conduit 44 is connected to the conduit 42 on a side closer to the steam outlet side of the IP dummy part than the valve 43 and in communication to the steam outlet side of the IP blade cascade 4 .
- a valve 45 is provided on the conduit 44 .
- a valve 41 is provided on the thrust balance conduit 30 .
- a control unit 52 is provided.
- the control unit 52 reads a detected value detected by a pressure sensor 54 which is provided at the reheat steam inlet 25 and controls opening and closing of the valves 41 , 43 and 45 based on the detected value.
- the control unit 52 controls the valve 41 to open and the valves 43 and 45 to close as shown in FIG. 2 .
- the valve mark filled in with black indicates an opened state
- the valve mark filled in with white indicates a closed state.
- the unit k denotes a pressure value in kgf/cm 2 to show pressure values as only example values at indicated places.
- the steam turbine is provided with the dummy members 12 , 14 and 16 , and the thrust balance conduit 30 .
- the resultant thrust force generated by the steam pressures is balanced.
- FIG. 3 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces of the present invention when the supply of the HP main steam is stopped.
- the control unit 52 is omitted.
- FIG. 4 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces of the present invention when the supply of the reheat steam and the LP main steam is stopped.
- the control unit 52 determines that the reheat steam 24 is not supplied based on the pressure value detected by the pressure sensor 54 (not shown in FIG. 4 )
- the control unit 52 opens the valve 43 .
- the pressure difference between both sides of the IP dummy member 14 becomes approximately 0.
- an excessive thrust force is generated at the IP dummy member 14 in the leftward direction.
- the thrust force can be prevented from being generated at the IP dummy member 14 .
- the diameter of the LP dummy member 16 is designed so as to generate a counter thrust force (leftward in FIG. 4 ) approximately by an amount corresponding to the above-described increased thrust force generated in the HP system.
- the thrust force generated in the whole steam turbine 1 is balanced.
- the diameter of the LP dummy member 16 is designed in advance so as to balance the thrust forces in a case where the valves 41 and 43 are opened in the state where the supply of the reheat steam and the LP main steam is stopped and, the diameter of the IP dummy member 14 is designed in advance so as to balance the thrust forces in the normal operating state and the state where the supply of the HP main steam is stopped.
- the thrust force is prevented from being generated at the IP dummy member 14 when the supply of the reheat steam and the LP main steam is stopped, and it becomes unnecessary to upsize the diameter of the LP dummy member 16 , apart from the conventional technology in which the diameter upsizing was inevitable.
- the diameter of the LP dummy member 16 can be small and the steam leakage to the gland can be reduced. As a result, the performance of the steam turbine can be enhanced.
- FIG. 5 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces of the present invention in a case where the valve 43 is in an abnormal condition in the normal operating state of the steam turbine.
- the control unit 52 determines that the valve 43 or 41 is not working properly.
- control unit 52 opens the valve 45 .
- FIG. 6 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces of the present invention, after taking a countermeasure against the malfunction of the valve 43 in the normal operating state of the steam turbine.
- the steam outlet side of the IP dummy member 14 communicates with the steam outlet side of the IP blade cascade 4 via the conduit 44 .
- a part of the steam at the steam outlet side of the IP dummy member 14 streams to the steam outlet side of the IP blade cascade 4 .
- This causes the pressure at the steam outlet side of the IP dummy member 14 to drop so that the pressure difference between both sides of the IP dummy member 14 is generated, thereby generating the thrust force at the IP dummy member 14 .
- the resultant thrust force generated in the whole steam turbine 1 is balanced.
- it is necessary to design the conduits 44 and the valve 45 in advance so that the steam flow rate through the conduit 44 is almost the same as the steam flow rate through the valve 43 when the valve 45 is opened in a case when the valve 43 is abnormally opened.
- FIG. 7 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces of the present invention in a case where the valve 41 is in an abnormal condition in the normal operating state of the steam turbine.
- the control unit 52 determines that the valve 43 or 41 is not working properly.
- control unit 52 opens the valve 45 .
- FIG. 8 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces of the present invention, after taking a countermeasure against the malfunction of the valve 41 in the normal operating state of the steam turbine.
- the steam outlet side of the IP dummy member 14 communicates with the steam outlet side of the IP blade cascade 4 via the conduit 44 . Then, a part of the steam at the steam outlet side of the IP dummy member 14 streams into the steam outlet side of the IP blade cascade 4 .
- the pressure at the steam outlet side of the IP dummy member 14 drops so that the pressure difference between both sides of the IP dummy member 14 is generated. Accordingly, the thrust force is generated at the IP dummy member 14 so that the resultant thrust force generated in the whole steam turbine 1 is balanced.
- FIG. 9 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces of the present invention, in a case where the function of the valve 43 is out of order while the supply of the reheat steam and the LP main steam is stopped
- FIG. 9 shows the case where the valve 43 stays closed.
- both sides of the IP dummy member 14 are not in communication with each other.
- the pressure difference between both sides of the IP dummy member 14 is generated so that the thrust force is generated at the dummy member 14 .
- the thrust force generated at the dummy member 14 causes the resultant thrust force generated in the whole steam turbine 1 to be unbalanced.
- the diameter of the IP dummy member 14 is greater than that of the conventional IP dummy member. For a corresponding amount, the unbalance (i.e. being out of balance) regarding the developed resultant thrust force increases.
- the control unit 52 determines that the valve 43 is not working properly.
- control unit 52 closes the valve 41 .
- FIG. 10 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces of the present invention, after taking a countermeasure against the malfunction of the valve 43 while the supply of the reheat steam and the LP main steam is stopped.
- the resultant force is kept balanced, even when the abnormal condition regarding the valve 43 takes place.
- the disclosed technology of the present invention is also applicable to HP-IP steam turbines.
- FIG. 11 shows an outline of a HP-IP steam turbine provided with the dummy members for adjusting thrust forces according to a second preferred embodiment of the present invention.
- the HP-IP steam turbine 101 depicted in FIG. 11 is provided with a turbine casing (not shown) is formed around a rotor shaft (not shown).
- the turbine casing encloses the inlet parts (not shown) for introducing HP steam and IP steam.
- a high-pressure (HP) chamber blade cascade 102 to which the HP steam is supplied and an intermediate-pressure (IP) chamber blade cascade 104 to which the IP steam is supplied are attached to the rotor shaft such that steam inlets of the HP chamber blade cascade 102 and the IP chamber blade cascade 104 are disposed facing each other. Further, between the steam inlet of the HP chamber blade cascade 2 and the steam inlet the IP chamber blade cascade 104 , a first dummy member 111 and a second dummy member 112 are provided. Further, a third dummy member 113 is provided at a steam outlet of the HP chamber blade cascade 102 .
- a balance conduit 121 is provided to communicate a location between the first dummy member 111 and the second dummy member 112 to both sides of the third dummy member 113 .
- a balance conduit 122 is provided to communicate the steam outlet of the third dummy member 113 to the steam outlet of the IP chamber blade cascade 104 .
- a valve 141 is provided on the balance conduit 121 between both sides of the third dummy member 113 and the downstream side of the third dummy member 113 and a valve 142 is provided on the balance conduit 122 .
- the table in FIG. 11 summarizes a balance of the thrust forces of the cases, when the turbine is operated normally, the supply of the HP steam is stopped (the HP system is closed), and the IP steam is stopped (the IP system is closed).
- the figures of the thrust forces in the table of FIG. 7 show not the absolute values but the relative ratios among thrust forces appearing in design calculations.
- the resultant thrust force is substantially balanced when the HP system is closed.
- the resultant thrust force becomes unbalanced because of the thrust force acting on the third dummy member 113 and the resultant thrust force increases rightward.
- the valve 41 (CV 1 ) is opened, the pressure difference between both sides of the third dummy member 113 is reduced and thus, the resultant thrust force generated in the whole steam turbine can be balanced.
- the pressure difference between both sides of the third dummy member 113 can be also reduced via the steam leakage through the dummy member 113 , by appropriately closing the valve 142 instead of opening the valve 141 . As a result, the resultant thrust force generated in the whole steam turbine can be balanced.
- FIG. 12 shows an outline of the HP-IP steam turbine provided with the dummy members for adjusting thrust forces according to a third preferred embodiment of the present invention.
- FIG. 12 As in FIG. 11 are given common numerals and are not explained further.
- a first dummy member 111 ′ is provided.
- the first dummy member 111 ′ is formed by integrating the first dummy member 111 and the second dummy member 112 (shown in FIG. 11 ), whose diameter is as same as the diameter of the first dummy member 111 .
- the steam turbine in FIG. 12 is not provided with the balance conduit 121 .
- the balance conduit 122 is provided with a bypass conduit 123 that bypasses the valve 142 .
- an orifice 124 is provided on the bypass conduit 123 .
- the resultant thrust force can be balanced, except when the IP system is closed.
- the resultant thrust force can be balanced by adjusting the opening of the valve 142 .
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Abstract
A steam turbine having at least a HP blade cascade, an IP blade cascade and a plurality of dummy members that are attached to a common rotor shaft, is provided with, but not limited to, a detection unit that detects a steam flow into an IP chamber, a pressure reducing unit that reduces a pressure difference between both sides of a target dummy member of said plurality of the dummy members when the steam flow into the IP chamber stops, the target dummy member having one side communicating with a part of the IP chamber, and a control unit that controls the pressure reducing unit based on a detection result obtained by the detection unit.
Description
- The present invention relates to a steam turbine and a method of adjusting a thrust force of the steam turbine, particularly regarding a steam turbine and a method of adjusting a thrust force of the steam turbine which are capable of balancing of a thrust force acting on a rotor shaft of the steam turbine which includes at least a high-pressure (HP) blade cascade, an intermediate-pressure (IP) blade cascade and a plurality of dummy members that are attached to a common rotor shaft.
- Since the rotor shaft is subjected to the thrust force acting thereon, the steam turbine is provided with a thrust bearing. With a limited load capacity of the bearing, it is necessary to design the steam turbine in consideration of a thrust balance so that the thrust force acting on the rotor shaft does not exceed the load capacity of the bearing under any operating condition.
- Hence, the dummy members (dummy pistons) and the blade cascades are attached to the same rotor shaft, so as thrust forces in a counter-thrust direction are generated by the dummy members to balance the forces acting in an axial direction of the entire rotor shaft. In this manner, the thrust force acting on the rotor shaft is kept within the scope of the load capacity of the bearing under any operation condition.
-
FIG. 13 shows an outline view regarding a conventional steam turbine under a normal operating condition, the conventional steam turbine being provided with dummy members for adjusting the thrust forces. - In a
conventional steam turbine 1 depicted inFIG. 13 , a turbine casing (not shown) is formed around arotor shaft 10. The turbine casing includes an inlet part (not shown) for introducing high-pressure (HP)main steam 22, an inlet part (not shown) for introducingreheat steam 24 and an inlet part (not shown) for introducing low-pressure (LP)main steam 26. - Further, a HP
blade cascade 2 to which the HP main steam is supplied, anIP blade cascade 4 to which thereheat steam 24 is supplied and a low-pressure (LP)blade cascade 6 to which the LPmain steam 26 is supplied are attached to therotor shaft 10 in this order. TheIP blade cascade 4 and theLP blade cascade 6 have steam inlets that are open to one side, whereas the HPblade cascade 2 has a steam inlet is open to other side being opposite to the one side. Between the steam inlet of the HPblade cascade 2 and the steam inlet of theIP blade cascade 4, a high-pressure (HP)dummy member 12 is provided. On a steam outlet side of the HPblade cascade 2, an intermediate-pressure (IP)dummy member 14 and a low-pressure (LP)dummy member 16 are provided in this order. Further, athrust balance conduit 30 is provided so as to communicate the outlet side of theIP dummy member 14 to a latter half of theIP blade cascade 4. - In the
steam turbine 1 as described above, the HPmain steam 22 from a boiler and the like (not shown) enters the HPblade cascade 2. And, the HPmain steam 22 gives a rotary force to therotor shaft 10 while the steam passes through the HPblade cascade 2. The steam that has done the work through the HPblade cascade 2 drops the pressure and the temperature gradually and is discharged out of thesteam turbine 1 as a low-temperature reheat steam 28. The low-temperature reheat steam 28 discharged out of thesteam turbine 1 is reheated by a reheat boiler (not shown) to be thereheat steam 24. - The
IP reheat steam 24 that is reheated by the reheat boiler gives the rotary force to therotor shaft 10 and gradually reduces the pressure and the temperature while thereheat steam 24 passes through theIP blade cascade 4. Further, the LPmain steam 26 gives the rotary force to therotor shaft 10 and gradually reduces the pressure and the temperature while the LPmain steam 26 passes through theLP blade cascade 6. - Further, a part of the high-pressure (HP)
main steam 22 passes by the high-pressure (HP)dummy member 12 and a part of the low-temperature reheat steam 28 that has passed through the HP blade cascade and has reduced the temperature and the pressure, passes by the intermediate-pressure (IP)dummy member 14 and the low-pressure (LP)dummy member 16. - Further, in
FIG. 13 , the thrust forces acting on therotor shaft 10 at the cascades and the dummy members on the rotor shaft are represented by encircled numbers, 1 to 6 and an example regarding a set of the pressure values between adjacent pair of each blade cascade (dummy parts) are shown inFIG. 13 . In addition, the thrust forces indicated byencircled numbers LP dummy member 16, theIP dummy member 14, the HPblade cascade 2, the HPdummy member 12, theIP blade cascade 4 and theLP blade cascade 6, respectively. The thrust force acing on each of the blade cascades can be computed based on the gas pressure force working on each blade cascade and the thrust force acting on each of the dummy members can be computed based on a pressure difference between both sides of each dummy member and a cross-sectional area of each dummy member. - As shown in
FIG. 13 , thedummy members thrust balance conduit 30 are provided so as to balance the thrust forces by the steam pressure. In other words, the thrust force acting on the HPdummy member 12 roughly serves as a counterbalance to the thrust force acting on the HPblade cascade 2, the thrust acting on theIP dummy member 14 roughly serving as a counterbalance to the thrust force acting on theIP blade cascade 4, the thrust force acting on theLP dummy member 16 roughly serving as a counterbalance to the thrust force acting on theLP blade cascade 6. Thus, the resultant thrust force acting on thewhole steam turbine 1 is balanced. - Further, in the steam turbine, in order to prevent the thrust bearing from being damaged, the resultant thrust force needs to be brought into balance not only in a case where the steam turbine is operated under a normal operating condition but also in a case where either the HP main steam supply or the reheat steam supply is stopped.
- First, attention is paid to a case where the flow of the HP
main steam 22 through thesteam turbine 1 as shown inFIG. 13 is stopped due to a trouble, a tuning operation or the like.FIG. 14 shows the outline of the state of the steam turbine provided with conventional dummy parts for adjusting thrust balance, when the supply of the HPmain steam 22 is stopped. - As shown in
FIG. 14 , when the supply of the HPmain steam 22 is stopped, the flow of the steam streaming through the HPblade cascade 2 stops, causing the pressure difference of the HP blade cascade to be 0. Accordingly, the thrust force represented by the encircled numeral 3 as depicted inFIG. 14 also becomes 0. Further, the pressure difference of the HPdummy member 12 becomes infinitesimal and, the thrust force represented by theencircled numeral 4 becomes approximately 0. Therefore, as shown inFIG. 14 , the resultant thrust force developed in thewhole steam turbine 1 is substantially balanced, even in a case where the supply of the HPmain steam 22 is stopped. - In the next place, attention is paid to a case in which the flow of the
reheat steam 24 and the LPmain steam 26 through thesteam turbine 1 as shownFIG. 13 is stopped due to a trouble, a tuning operation or the like.FIG. 15 shows the outline of the state of the steam turbine provided with conventional dummy parts for adjusting thrust balance, when the supply of the reheat steam and the LP main steam is stopped. - As shown in
FIG. 15 , when the supply of thereheat steam 24 and the LPmain steam 26 is stopped, the flow of the steam streaming through theIP blade cascade 4 and theLP blade cascade 6 ends. Each of the pressures on both sides of theIP blade cascade 4 and the pressures on both sides of theLP blade cascade 6 becomes approximately a level of vacuum pressure. Further, due to the thrust balance conduit 30 that communicates theIP dummy member 14 to the latter half of theIP blade cascade 4, the pressure between theIP dummy member 14 and theLP dummy member 16 also becomes a level of vacuum pressure. - In such case, in an LP system (a low-pressure part of the steam turbine), the pressure difference between both sides of the
LP blade cascade 6 and the pressure difference between both sides of theLP dummy member 16 become approximately 0, resulting in the thrust force acting on the rotor shaft being 0. - Further, in relation to the IP system (the intermediate-pressure part of the steam turbine), the pressure at the outlet of the
IP dummy member 14 becomes a level of vacuum pressure and in response to the vacuum pressure level, the thrust force represented by theencircled numeral 2 as shown inFIG. 15 increases. In addition, the pressure difference between both sides of theIP blade cascade 4 becomes approximately 0. In this manner, the thrust force represented by the encircled numeral 5 becomes approximately 0. As a result, the resultant thrust force acting toward the direction of the IP dummy member side (leftward inFIG. 15 ) increases. - Further, in relation to a HP system (a high-pressure part of the steam turbine), the thrust force generated in the HP
blade cascade 2 represented by the encircled numeral 3 is approximately the same as that of a normal operation condition, whereas the thrust force represented by theencircled numeral 2 generated in the HPdummy member 12 increases by an amount corresponding to the vacuum pressure level at the outlet of the HPdummy member 12. Thus, the thrust force acting in the direction of the HP dummy member (rightward inFIG. 15 ) increase. - Hereby, the increase of the thrust force generated in the IP system is greater than the increase of the thrust force generated in the HP system. Accordingly, the resultant thrust force generated in the
whole steam turbine 1 increases in the leftward direction inFIG. 15 . Thus, the resultant thrust force acting on the whole steam turbine is not balanced. - In a case where the flow of the
reheat steam 24 is stopped, it may be considered that the HPdummy member 12 is upsized so that thrust force in the rightward direction increases and the resultant thrust force is balanced. However, the upsizing of the HPdummy member 12 spoils the balancing in the normal operation and thus, this approach is not appropriate. - Hence, in relation to each of
FIG. 13 toFIG. 15 , theIP dummy member 14 is downsized and theLP dummy member 16 is upsized. By this, the balance of the thrust force can be maintained under the normal operating condition, even in a case where the supply of any one of the HP main steam and the reheat steam is stopped. - In addition,
Patent Reference 1 discloses another technology; according to this technology, thrust forces acting on the steam turbine are evaluated based on the measured data such as bearing temperatures. Based on the results of the measurements, the thrust forces acting on the dummy members can be adjusted in an electronic control approach, and the resultant thrust force developed in the whole steam turbine is brought into balance. - Patent Reference 1: JP1996-189302
- In the conventional technology as explained above in reference to
FIG. 13 throughFIG. 15 , it is necessary to downsize theIP dummy member 14 and upsize the LP-dummy member 16 so as to balance the resultant thrust force even when the supply of the reheat steam in addition to the HP main steam is stopped in the normal operation. Upsizing of theLP dummy member 16 accompanies upsizing of the casing that is located at the outer periphery of theLP dummy member 16. Accordingly, thewhole steam turbine 1 is inevitably upsized and the manufacturing cost increases. Moreover, when the diameter of theLP dummy member 16 is increased, the steam leakage from theLP dummy member 16 toward the gland increases. Inevitably, there arises a possibility that the performance of thesteam turbine 1 deteriorated. In recent years, the LP blade cascade is becoming larger, accompanying upsizing of the LP dummy member. However, it is not desirable to upsize the LP dummy member to balance the thrust forces. - Further, in the technology as disclosed by
Patent Reference 1 where the balancing of the thrust forces is performed by use of an electric control, there is a possibility that the reliability of the electric system may cause a problem. - In view of the above problems of the related art, it is an object of the present invention to provide a steam turbine and a method of adjusting a thrust force of the steam turbine acting on a rotor shaft of the turbine in an entire operating range of the steam turbine without upsizing a LP dummy member or without using an electric control of a complicated system.
- To solve the above issues, the present invention provides a steam turbine having at least a high-pressure (HP) blade cascade, an intermediate-pressure (IP) blade cascade and a plurality of dummy members that are attached to a common rotor shaft. The steam turbine may include, but is not limited to:
- a detection unit that detects a steam flow into an intermediate-pressure (IP) chamber;
- a pressure reducing unit that reduces a pressure difference between both sides of a target dummy member of said plurality of the dummy members when the steam flow into the IP chamber stops, the target dummy member having one side communicating with a part of the IP chamber; and
- a control unit that controls the pressure reducing unit based on a detection result obtained by the detection unit.
- In this manner, the thrust force generated at the IP dummy member when the steam flow into the IP chamber stops can be eliminated. Thus, it is no longer necessary to increase the diameter of the LP dummy member which was conventionally needed to balance the thrust force generated at the IP dummy member. As a result, the diameter of the LP dummy member can be reduced and the thrust forces acting on the rotor of the steam turbine can be balanced in the entire operation range of the steam turbine without using the electric control of the complicated system.
- The above pressure reducing unit may include, but is not limited to, a first conduit that connects the both sides of the target dummy member and a first valve that is provided in the first conduit to adjust the pressure difference between the both sides of the target dummy member.
- In this way, the thrust forces acting on the rotor shaft of the steam turbine can be balanced, with a simple configuration.
- The above steam turbine may further include:
- a third conduit that connects the one side of the pressure reducing unit to an outlet of the IP chamber; and
- a third valve that is provided in the third conduit.
- When the first valve opens while the steam flow into the IP chamber is not stopped, the control unit may control the third valve to open so as to generate the pressure difference between the both sides of the target dummy member.
- In this way, even when the first valve is out of order, the thrust forces generated in the steam turbine can be balanced and, the reliability of the steam turbine can be enhanced.
- The above pressure reducing unit may include, but is not limited to:
- a second conduit that connects the part of the IP chamber and the one side of the target dummy member; and
- a second valve that is provided in the second conduit to adjust the difference between the both sides of the target dummy member.
- The second valve may be closed when the steam flow into the IP chamber stops.
- In relation to the above, the second conduit is often provided even in the conventional steam turbines. Thus, in remodeling or modernizing the conventional existing steam turbine, the pressure reducing unit can be provided by simply fitting the second valve to the existing second conduit without newly installing a conduit to the steam turbine. Thus, the remodeling can be easily accomplished.
- The above steam turbine may further include:
- a bypass conduit that is provided to bypass the second valve; and
- an orifice that is provided in the bypass conduit.
- In this way, the thrust forces generated in the steam turbine can be easily balanced.
- The above steam turbine may also include:
- a third conduit that connects the one side of the pressure reducing unit to an outlet of the IP chamber; and
- a third valve that is provided in the third conduit.
- When the second valve closes while the steam flow into the IP chamber is not stopped, the control unit may control the third valve to open so as to generate the pressure difference between the both sides of the target dummy member.
- To achieve the object of the present invention, the present invention provides a method of adjusting a thrust force of a steam turbine having at least a HP blade cascade, an IP blade cascade and a plurality of dummy members that are attached to a common rotor shaft. The method may include, but is not limited to, the step of reducing a pressure difference between both sides of a target dummy member of said plurality of the dummy members when the steam flow into the IP chamber stops, the target dummy member having one side communicating with a part of the IP chamber.
- Further, in the above method, the pressure difference between the both sides of the target dummy member may be reducible by use of a first valve provided in a first conduit that connects the both sides of the target dummy member.
- Further, in the above method, when the first valve opens while the steam flow into the IP chamber is not stopped, the pressure difference may be generated between the both sides of the target dummy member by opening a third valve which is provided in a third conduit that connects the one side of the target dummy member to an outlet of the IP chamber.
- In the above method of adjusting the thrust force of the steam turbine, the pressure difference between the both sides of the target dummy member may be reducible by use of a second valve provided in a second conduit that connects the part of the IP chamber and the one side of the target dummy member.
- In the above method of adjusting the thrust force of the steam turbine, when the second valve closes while the steam flow into the IP chamber is stopped, the pressure difference may be generated between the both sides of the target dummy member by opening a third valve which is provided in a third conduit that connects the one side of the target dummy member to an outlet of the IP chamber.
- According to the present invention, the steam turbine and the method of adjusting the thrust force of the steam turbine can be provided which are operable to balance the thrust forces in the entire operation range of the steam turbine without upsizing the LP dummy member, as well as, without using the electric control of a complicated system.
-
FIG. 1 shows a configuration of a single-casing reheat steam turbine provided with a plurality of dummy members for adjusting thrust forces, according to a first preferred embodiment of the present invention. -
FIG. 2 shows an outline of a normal operating state of the steam turbine provided with the dummy members for adjusting thrust forces, according to the first preferred embodiment of the present invention. -
FIG. 3 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces when the supply of the HP main steam is stopped, according to the first preferred embodiment of the present invention. -
FIG. 4 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces when the supply of the reheat steam and the LP main steam is stopped, according to the first preferred embodiment of the present invention. -
FIG. 5 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces in a case where a valve is in an abnormal condition in the normal operating state of the steam turbine, according to the first preferred embodiment of the present invention. -
FIG. 6 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces, after taking a countermeasure against the malfunction of the valve in the normal operating state of the steam turbine, according to the first preferred embodiment of the present invention. -
FIG. 7 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces in a case where another valve is in an abnormal condition in the normal operating state of the steam turbine, according to the first preferred embodiment of the present invention. -
FIG. 8 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces, after taking a countermeasure against the malfunction of said another valve in the normal operating state of the steam turbine, according to the first preferred embodiment of the present invention. -
FIG. 9 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces, according to the first preferred embodiment of the present invention, in a case where the function of a valve is out of order while the supply of the reheat steam and the LP main steam is stopped. -
FIG. 10 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces, according to the first preferred embodiment of the present invention, after taking a countermeasure against the malfunction of the valve while the supply of the reheat steam and the LP main steam is stopped. -
FIG. 11 shows an outline of a HP-IP steam turbine provided with the dummy members for adjusting thrust forces, according to a second preferred embodiment of the present invention. -
FIG. 12 shows an outline of a HP-IP steam turbine provided with the dummy members for adjusting thrust forces, according to a third preferred embodiment of the present invention. -
FIG. 13 shows an outline of a normal operating state of the steam turbine provided with conventional dummy members. -
FIG. 14 shows an outline of a state of the steam turbine provided with conventional dummy parts for adjusting thrust balance, when the supply of the HP main steam is stopped. -
FIG. 15 shows an outline of a state of the steam turbine provided with conventional dummy parts for adjusting thrust balance, when the supply of the reheat steam and the LP main steam is stopped. - A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings. It is intended, however, that unless particularly specified, dimensions, materials, shape, its relative positions and the like shall be interpreted as illustrative only and not limitative of the scope of the present invention.
-
FIG. 1 shows a configuration of a single-casing reheat steam turbine provided with a plurality of dummy members for adjusting thrust forces, according to a first preferred embodiment of the present invention. In a steam turbine shown inFIG. 1 , a low-pressure (LP)casing 32 and a HP-IP casing 34 (a high-intermediate-pressure casing) are formed around arotor shaft 10. The HP-IP casing 34 is provided with a high-pressure (HP)steam inlet 23 through which HP steam 22 is supplied to the steam turbine and a reheat steam inlet 25 through which reheatsteam 24 is supplied to the steam turbine. Further, theLP casing 32 is provided with a low-pressure (LP)steam inlet 27 through which LP steam 26 is supplied to the steam turbine. - To the
rotor shaft 10, attached are aHP blade cascade 2 to which the HP main steam is supplied, an intermediate-pressure (IP)blade cascade 4 to which thereheat steam 24 is supplied and a low-pressure (LP)blade cascade 6 to which the LPmain steam 26 is supplied in this order. - In the steam turbine, steam inlet sides of the
IP blade cascade 4 and theLP blade cascade 6 are arranged such that the steam streams through theIP blade cascade 4 and theLP blade cascade 6 in the same direction, whereas a steam inlet side of theHP blade cascade 2 is arranged such that the steam streams through theHP blade cascade 2 in the opposite direction. Further, aHP dummy member 12 is provided between the steam inlet side of theHP blade cascade 2 and the steam inlet side of theIP blade cascade 4. On the steam outlet side of theHP blade cascade 2, anIP dummy member 14 and aLP dummy member 16 are provided in this order. Furthermore, athrust balance conduit 30 is provided to communicate the steam outlet side of theIP dummy member 14 to a part of theIP blade cascade 4. -
FIG. 2 shows an outline of a normal operating state of the steam turbine provided with the dummy members for adjusting thrust forces. Hereby, the same components inFIG. 2 as inFIG. 1 ,FIG. 13 throughFIG. 15 are given common numerals and are not explained further. Herein, a normal operating state means an operating state of the steam turbine in which all of theHP steam 22, thereheat steam 24 and theLP steam 26 are supplied to the steam turbine. - Differently from the conventional technology shown in
FIG. 13 , in the first preferred embodiment of the present invention as shown inFIG. 2 , the diameter of theIP dummy member 14 is upsized in comparison with theconventional dummy member 14, whereas the diameter of theLP dummy member 16 is downsized in comparison with theconventional dummy member 16. With theLP dummy member 16 having larger diameter, the thrust forces of the steam turbine as a whole are prevented from being unbalanced. - Further, a
conduit 42 is provided to communicate the steam inlet side of theIP dummy member 14 to the steam outlet side thereof and avalve 43 is provided on theconduit 42. Aconduit 44 is connected to theconduit 42 on a side closer to the steam outlet side of the IP dummy part than thevalve 43 and in communication to the steam outlet side of theIP blade cascade 4. Avalve 45 is provided on theconduit 44. Avalve 41 is provided on thethrust balance conduit 30. - Further, a
control unit 52 is provided. Thecontrol unit 52 reads a detected value detected by a pressure sensor 54 which is provided at the reheat steam inlet 25 and controls opening and closing of thevalves reheat steam 24 is supplied to thesteam turbine 1 and the pressure detected by the pressure sensor 54 is within a normal pressure range of thereheat steam 24, thecontrol unit 52 controls thevalve 41 to open and thevalves FIG. 2 . As for the open-close state of the valves in the attached drawings, the valve mark filled in with black indicates an opened state, whereas the valve mark filled in with white indicates a closed state. - In
FIG. 2 throughFIG. 10 andFIG. 13 throughFIG. 15 , the unit k denotes a pressure value in kgf/cm2 to show pressure values as only example values at indicated places. - As shown in
FIG. 2 , the steam turbine is provided with thedummy members thrust balance conduit 30. In the normal operating state, the resultant thrust force generated by the steam pressures is balanced. - Next, a case where the supply of the HP
main steam 22 is stopped in thesteam turbine 1 shown inFIG. 2 is explained.FIG. 3 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces of the present invention when the supply of the HP main steam is stopped. InFIG. 3 throughFIG. 15 , thecontrol unit 52 is omitted. - In
FIG. 3 , when the supply of the HPmain steam 22 is stopped, no steam is supplied to theHP blade cascade 2, and the pressure difference at theHP blade cascade 2 becomes 0. Thus, the thrust force represented by the encircled numeral 3 as depicted inFIG. 14 also becomes 0. Accordingly, the pressure difference at theHP dummy member 12 becomes significantly small and the thrust force represented by the encirclednumeral 4 becomes close to 0. Therefore, as shown inFIG. 3 , even when the supply of the HPmain steam 22 is stopped, the resultant thrust force acting on thewhole steam turbine 1 is balanced. - Next, a case where the supply of the
reheat steam 24 and the LPmain steam 26 is stopped in thesteam turbine 1 shown inFIG. 2 is explained.FIG. 4 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces of the present invention when the supply of the reheat steam and the LP main steam is stopped. - In
FIG. 4 , when the supply of thereheat steam 24 and the LPmain steam 26 is stopped, no steam is supplied to theIP blade cascade 4 and theLP blade cascade 6. This causes the pressures at both sides of theIP blade cascade 4 and theLP blade cascade 6 to be approximately at vacuum level. In the HP system (the high-pressure part of the steam turbine), the thrust force represented by the encircled numeral 3 generated at theHP blade cascade 2 is almost the same as the thrust force in the normal operating state of the steam turbine. However, the thrust force represented by the encircled numeral 2 generated at theHP dummy member 12 increases in response to the increase regarding the level of the vacuum pressure at the outlet of theHP dummy member 12. By this, the thrust force acting on theHP dummy member 12 increases in the direction of the steam flow along the HP dummy member (in the rightward direction inFIG. 4 ). - When the control unit 52 (not shown in
FIG. 4 ) determines that thereheat steam 24 is not supplied based on the pressure value detected by the pressure sensor 54 (not shown inFIG. 4 ), thecontrol unit 52 opens thevalve 43. By this, the pressure difference between both sides of theIP dummy member 14 becomes approximately 0. Specifically, in a case where thereheat steam 24 is not supplied to the steam turbine in the conventional technology, an excessive thrust force is generated at theIP dummy member 14 in the leftward direction. On the other hand, in this preferred embodiment of the present invention, the thrust force can be prevented from being generated at theIP dummy member 14. - Further, in the case of
FIG. 4 , the diameter of theLP dummy member 16 is designed so as to generate a counter thrust force (leftward inFIG. 4 ) approximately by an amount corresponding to the above-described increased thrust force generated in the HP system. Thus, the thrust force generated in thewhole steam turbine 1 is balanced. - In addition, the diameter of the
LP dummy member 16 is designed in advance so as to balance the thrust forces in a case where thevalves IP dummy member 14 is designed in advance so as to balance the thrust forces in the normal operating state and the state where the supply of the HP main steam is stopped. In this way, the thrust force is prevented from being generated at theIP dummy member 14 when the supply of the reheat steam and the LP main steam is stopped, and it becomes unnecessary to upsize the diameter of theLP dummy member 16, apart from the conventional technology in which the diameter upsizing was inevitable. Hence, the diameter of theLP dummy member 16 can be small and the steam leakage to the gland can be reduced. As a result, the performance of the steam turbine can be enhanced. - Next, the countermeasures against the possible abnormal-conditions that may be caused by providing the
valves - First, abnormal conditions of the
valve 43 are now explained. -
FIG. 5 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces of the present invention in a case where thevalve 43 is in an abnormal condition in the normal operating state of the steam turbine. - In
FIG. 5 , when thevalve 43 becomes out of order due to a fault and so on, thevalve 43 is opened and then both sides of theIP dummy member 14 are in communication with each other, and the pressure at the steam outlet side of theIP dummy member 14 increases. And, the pressure difference between both sides of theIP dummy member 14 becomes almost 0. Thus, the thrust force generated at theIP dummy member 14 becomes almost 0. As a result, the resultant thrust force of thewhole steam turbine 1 becomes unbalanced. - In the event as described above, the pressure detected by a
pressure sensor 56 provided in thethrust balance conduit 30 increases. When the detected pressure value exceeds a prescribed value, then the control unit 52 (not shown inFIG. 5 ) determines that thevalve - Once it is determined that the
valve control unit 52 opens thevalve 45. -
FIG. 6 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces of the present invention, after taking a countermeasure against the malfunction of thevalve 43 in the normal operating state of the steam turbine. - When the
control unit 52 opens thevalve 45, the steam outlet side of theIP dummy member 14 communicates with the steam outlet side of theIP blade cascade 4 via theconduit 44. A part of the steam at the steam outlet side of theIP dummy member 14 streams to the steam outlet side of theIP blade cascade 4. This causes the pressure at the steam outlet side of theIP dummy member 14 to drop so that the pressure difference between both sides of theIP dummy member 14 is generated, thereby generating the thrust force at theIP dummy member 14. As a result, the resultant thrust force generated in thewhole steam turbine 1 is balanced. In addition, it is necessary to design theconduits 44 and thevalve 45 in advance so that the steam flow rate through theconduit 44 is almost the same as the steam flow rate through thevalve 43 when thevalve 45 is opened in a case when thevalve 43 is abnormally opened. - As described above, even when the
valve 43 is in the abnormal condition, the resultant thrust force can be kept balanced; thus, the reliability of thesteam turbine 1 can be enhanced with additionally provided simple-components. - Next, the abnormal-conditions of the
valve 41 are explained. -
FIG. 7 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces of the present invention in a case where thevalve 41 is in an abnormal condition in the normal operating state of the steam turbine. - In
FIG. 7 , when thevalve 41 becomes out of order because of a fault and so on and thevalve 41 is closed, then the steam at the outlet side of theIP dummy member 14 is no longer able to stream toward theIP blade cascade 4 through thethrust balance conduit 30. On the other hand, when there is a pressure difference between both sides of theIP dummy member 14, the steam in a labyrinth seal provided at an outer periphery of theIP dummy member 14 leaks toward the steam outlet side thereof. Thus, the pressure difference between both sides of theIP dummy member 14 becomes approximately 0. Accordingly, the thrust force acting on theIP dummy member 14 becomes approximately 0. As a result, the resultant force is unbalanced. - In the event as described above, the pressure detected by the
pressure sensor 56 provided on thethrust balance conduit 30 increases. When the detected pressure exceeds a prescribed value, then the control unit 52 (not shown inFIG. 5 ) determines that thevalve - Once it is determined that the
valve control unit 52 opens thevalve 45. -
FIG. 8 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces of the present invention, after taking a countermeasure against the malfunction of thevalve 41 in the normal operating state of the steam turbine. - When the
control unit 52 opens thevalve 45, the steam outlet side of theIP dummy member 14 communicates with the steam outlet side of theIP blade cascade 4 via theconduit 44. Then, a part of the steam at the steam outlet side of theIP dummy member 14 streams into the steam outlet side of theIP blade cascade 4. Thus, the pressure at the steam outlet side of theIP dummy member 14 drops so that the pressure difference between both sides of theIP dummy member 14 is generated. Accordingly, the thrust force is generated at theIP dummy member 14 so that the resultant thrust force generated in thewhole steam turbine 1 is balanced. - As described above, even when the abnormal condition of the
valve 41 happens, the resultant thrust force is kept balanced. Thus, the reliability of the steam turbine can be enhanced with additional simple-components. - Next, abnormal-conditions that may occur on the
valve 41 in a case where the supply of the reheat steam and the LP main steam is stopped are explained. -
FIG. 9 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces of the present invention, in a case where the function of thevalve 43 is out of order while the supply of the reheat steam and the LP main steam is stopped - As described already based on
FIG. 3 , it is necessary to open thevalve 43 in the case where the supply of the reheat steam and the LP main steam is stopped. However,FIG. 9 shows the case where thevalve 43 stays closed. - In
FIG. 9 , with thevalve 43 being closed, both sides of theIP dummy member 14 are not in communication with each other. Thus, the pressure difference between both sides of theIP dummy member 14 is generated so that the thrust force is generated at thedummy member 14. The thrust force generated at thedummy member 14 causes the resultant thrust force generated in thewhole steam turbine 1 to be unbalanced. In the present invention, the diameter of theIP dummy member 14 is greater than that of the conventional IP dummy member. For a corresponding amount, the unbalance (i.e. being out of balance) regarding the developed resultant thrust force increases. - In the event as described above, the pressure detected by the
pressure sensor 56 provided on thethrust balance conduit 30 drops. When the detected pressure value is processed below a prescribed value, then the control unit 52 (not shown inFIG. 9 ) determines that thevalve 43 is not working properly. - Once it is determined by the
control unit 52 that thevalve 43 is not working properly, thecontrol unit 52 closes thevalve 41. -
FIG. 10 shows an outline of a state of the steam turbine provided with the dummy members for adjusting thrust forces of the present invention, after taking a countermeasure against the malfunction of thevalve 43 while the supply of the reheat steam and the LP main steam is stopped. - With the
valve 41 being closed, the pressure difference between both sides of theIP dummy member 14 becomes approximately 0 due to the steam leakage from theIP dummy member 14. Accordingly, the thrust force acting on theIP dummy member 14 becomes almost 0. - In this manner, the resultant thrust force is balanced as is the case with
FIG. 4 in which there is no abnormal condition regarding thevalve 43. - Specifically, the resultant force is kept balanced, even when the abnormal condition regarding the
valve 43 takes place. - The disclosed technology of the present invention is also applicable to HP-IP steam turbines.
-
FIG. 11 shows an outline of a HP-IP steam turbine provided with the dummy members for adjusting thrust forces according to a second preferred embodiment of the present invention. - The HP-
IP steam turbine 101 depicted inFIG. 11 is provided with a turbine casing (not shown) is formed around a rotor shaft (not shown). The turbine casing encloses the inlet parts (not shown) for introducing HP steam and IP steam. - Further, a high-pressure (HP)
chamber blade cascade 102 to which the HP steam is supplied and an intermediate-pressure (IP)chamber blade cascade 104 to which the IP steam is supplied are attached to the rotor shaft such that steam inlets of the HPchamber blade cascade 102 and the IPchamber blade cascade 104 are disposed facing each other. Further, between the steam inlet of the HPchamber blade cascade 2 and the steam inlet the IPchamber blade cascade 104, afirst dummy member 111 and a second dummy member 112 are provided. Further, athird dummy member 113 is provided at a steam outlet of the HPchamber blade cascade 102. Further, abalance conduit 121 is provided to communicate a location between thefirst dummy member 111 and the second dummy member 112 to both sides of thethird dummy member 113. Furthermore, abalance conduit 122 is provided to communicate the steam outlet of thethird dummy member 113 to the steam outlet of the IPchamber blade cascade 104. In addition, avalve 141 is provided on thebalance conduit 121 between both sides of thethird dummy member 113 and the downstream side of thethird dummy member 113 and avalve 142 is provided on thebalance conduit 122. - In relation to the HP-IP steam turbine as described above, the table in
FIG. 11 summarizes a balance of the thrust forces of the cases, when the turbine is operated normally, the supply of the HP steam is stopped (the HP system is closed), and the IP steam is stopped (the IP system is closed). The figures of the thrust forces in the table ofFIG. 7 show not the absolute values but the relative ratios among thrust forces appearing in design calculations. - As shown in
FIG. 7 , in the normal operation state, the resultant thrust force is substantially balanced when the HP system is closed. In contrast, when the IP system is closed, the resultant thrust force becomes unbalanced because of the thrust force acting on thethird dummy member 113 and the resultant thrust force increases rightward. In this event, when the valve 41 (CV1) is opened, the pressure difference between both sides of thethird dummy member 113 is reduced and thus, the resultant thrust force generated in the whole steam turbine can be balanced. In addition, when the IP system is closed, the pressure difference between both sides of thethird dummy member 113 can be also reduced via the steam leakage through thedummy member 113, by appropriately closing thevalve 142 instead of opening thevalve 141. As a result, the resultant thrust force generated in the whole steam turbine can be balanced. -
FIG. 12 shows an outline of the HP-IP steam turbine provided with the dummy members for adjusting thrust forces according to a third preferred embodiment of the present invention. - The same components in
FIG. 12 as inFIG. 11 are given common numerals and are not explained further. - In
FIG. 12 , afirst dummy member 111′ is provided. Thefirst dummy member 111′ is formed by integrating thefirst dummy member 111 and the second dummy member 112 (shown inFIG. 11 ), whose diameter is as same as the diameter of thefirst dummy member 111. Hereby, the steam turbine inFIG. 12 is not provided with thebalance conduit 121. Instead, thebalance conduit 122 is provided with abypass conduit 123 that bypasses thevalve 142. Further, anorifice 124 is provided on thebypass conduit 123. - In a manner similar to the second preferred embodiment, the resultant thrust force can be balanced, except when the IP system is closed. When the IP system is closed, the resultant thrust force can be balanced by adjusting the opening of the
valve 142. - In the above event, when it is difficult to adjust the opening of the valve such as setting the opening of the
valve 142 at a minimal level, it is recommendable to close thevalve 42 and use theorifice 123. In relation to this event, it is necessary to set the size of the orifice in advance so that with thevalve 142 being full-closed, the steam pressure at a back side of thethird dummy member 113 is appropriate. - In other words, in a case where the IP system is closed, the
valve 142 is closed and the steam streams through theorifice 124. Thus, the steam pressure at the back side of thethird dummy member 113 is appropriately maintained. Hence, the resultant thrust force can be balanced. - According to the present invention, it is possible to provide a steam turbine and a method of adjusting a thrust force of the steam turbine acting on a rotor shaft of the turbine in an entire operating range of the steam turbine without upsizing a LP dummy member or without using an electric control of a complicated system.
Claims (11)
1. A steam turbine having at least a high-pressure blade cascade, an intermediate-pressure blade cascade and a plurality of dummy members that are attached to a common rotor shaft, the steam turbine comprising:
a detection unit that detects a steam flow into an intermediate-pressure chamber;
a pressure reducing unit that reduces a pressure difference between both sides of a target dummy member of said plurality of the dummy members when the steam flow into the intermediate-pressure chamber stops, the target dummy member having one side communicating with a part of the intermediate-pressure chamber; and
a control unit that controls the pressure reducing unit based on a detection result obtained by the detection unit.
2. The steam turbine according to claim 1 ,
wherein the pressure reducing unit comprises:
a first conduit that connects the both sides of the target dummy member; and
a first valve that is provided in the first conduit to adjust the pressure difference between the both sides of the target dummy member.
3. The steam turbine according to claim 2 , further comprising:
a third conduit that connects the one side of the pressure reducing unit to an outlet of the intermediate-pressure chamber; and
a third valve that is provided in the third conduit,
wherein, when the first valve opens while the steam flow into the intermediate-pressure chamber is not stopped, the control unit controls the third valve to open so as to generate the pressure difference between the both sides of the target dummy member.
4. The steam turbine according to claim 1 ,
wherein the pressure reducing unit comprises:
a second conduit that connects the part of the intermediate-pressure chamber and the one side of the target dummy member; and
a second valve that is provided in the second conduit to adjust the difference between the both sides of the target dummy member,
wherein the second valve is closed when the steam flow into the intermediate-pressure chamber stops.
5. The steam turbine according to claim 4 , further comprising:
a bypass conduit that is provided to bypass the second valve; and
an orifice that is provided in the bypass conduit.
6. The steam turbine according to claim 4 , further comprising:
a third conduit that connects the one side of the pressure reducing unit to an outlet of the intermediate-pressure chamber; and
a third valve that is provided in the third conduit,
wherein, when the second valve closes while the steam flow into the intermediate-pressure chamber is not stopped, the control unit controls the third valve to open so as to generate the pressure difference between the both sides of the target dummy member.
7. A method of adjusting a thrust force of a steam turbine having at least a high-pressure blade cascade, an intermediate-pressure blade cascade and a plurality of dummy members that are attached to a common rotor shaft, the method comprising the step of:
reducing a pressure difference between both sides of a target dummy member of said plurality of the dummy members when the steam flow into the intermediate-pressure chamber stops, the target dummy member having one side communicating with a part of the intermediate-pressure chamber.
8. The method of adjusting the thrust force of the steam turbine according to claim 7 ,
wherein the pressure difference between the both sides of the target dummy member is reducible by use of a first valve provided in a first conduit that connects the both sides of the target dummy member.
9. The method of adjusting the thrust force of the steam turbine according to claim 8 ,
wherein, when the first valve opens while the steam flow into the intermediate-pressure chamber is not stopped, the pressure difference is generated between the both sides of the target dummy member by opening a third valve which is provided in a third conduit that connects the one side of the target dummy member to an outlet of the intermediate-pressure chamber.
10. The method of adjusting the thrust force of the steam turbine according to claim 7 ,
wherein the pressure difference between the both sides of the target dummy member is reducible by use of a second valve provided in a second conduit that connects the part of the intermediate-pressure chamber and the one side of the target dummy member.
11. The method of adjusting the thrust force of the steam turbine according to claim 10 ,
wherein, when the second valve closes while the steam flow into the intermediate-pressure chamber is stopped, the pressure difference is generated between the both sides of the target dummy member by opening a third valve which is provided in a third conduit that connects the one side of the target dummy member to an outlet of the intermediate-pressure chamber.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2010148624A JP5517785B2 (en) | 2010-06-30 | 2010-06-30 | Steam turbine and method for adjusting thrust of steam turbine |
JP2010-148624 | 2010-06-30 |
Publications (1)
Publication Number | Publication Date |
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US20120017592A1 true US20120017592A1 (en) | 2012-01-26 |
Family
ID=45401786
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/171,563 Abandoned US20120017592A1 (en) | 2010-06-30 | 2011-06-29 | Steam turbine and method for adjusting thrust forces thereof |
Country Status (6)
Country | Link |
---|---|
US (1) | US20120017592A1 (en) |
EP (1) | EP2589747B1 (en) |
JP (1) | JP5517785B2 (en) |
KR (1) | KR101466457B1 (en) |
CN (1) | CN102906373B (en) |
WO (1) | WO2012002051A1 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2016066316A1 (en) * | 2014-10-29 | 2016-05-06 | Siemens Aktiengesellschaft | Turbine with axial pressure equalization |
US20170226886A1 (en) * | 2016-02-04 | 2017-08-10 | United Technologies Corporation | Method for clearance control in a gas turbine engine |
WO2018203985A1 (en) * | 2017-05-01 | 2018-11-08 | General Electric Company | Systems and methods for dynamic balancing of steam turbine rotor thrust |
CN112412548A (en) * | 2020-11-23 | 2021-02-26 | 东方电气集团东方汽轮机有限公司 | Adjusting system for axial thrust of steam turbine under variable working conditions and using method thereof |
US11105201B2 (en) | 2017-03-16 | 2021-08-31 | Mitsubishi Heavy Industries Compressor Corporation | Steam turbine |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
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KR102525617B1 (en) * | 2021-02-04 | 2023-04-24 | 한국수력원자력 주식회사 | Thrust control apparatus for balance piston of nuclear power plant |
CN113047911B (en) * | 2021-03-10 | 2022-01-14 | 东方电气集团东方汽轮机有限公司 | Thrust balancing structure |
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- 2011-05-13 KR KR1020127031324A patent/KR101466457B1/en active IP Right Grant
- 2011-05-13 WO PCT/JP2011/061109 patent/WO2012002051A1/en active Application Filing
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WO2018203985A1 (en) * | 2017-05-01 | 2018-11-08 | General Electric Company | Systems and methods for dynamic balancing of steam turbine rotor thrust |
US10871072B2 (en) * | 2017-05-01 | 2020-12-22 | General Electric Company | Systems and methods for dynamic balancing of steam turbine rotor thrust |
CN112412548A (en) * | 2020-11-23 | 2021-02-26 | 东方电气集团东方汽轮机有限公司 | Adjusting system for axial thrust of steam turbine under variable working conditions and using method thereof |
Also Published As
Publication number | Publication date |
---|---|
EP2589747A1 (en) | 2013-05-08 |
WO2012002051A1 (en) | 2012-01-05 |
JP2012012970A (en) | 2012-01-19 |
KR101466457B1 (en) | 2014-11-28 |
EP2589747A4 (en) | 2014-08-27 |
EP2589747B1 (en) | 2018-08-15 |
KR20130004403A (en) | 2013-01-09 |
CN102906373A (en) | 2013-01-30 |
JP5517785B2 (en) | 2014-06-11 |
CN102906373B (en) | 2015-02-18 |
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