CA1053537A - Combined stop and intercept valve for steam turbines - Google Patents
Combined stop and intercept valve for steam turbinesInfo
- Publication number
- CA1053537A CA1053537A CA255,010A CA255010A CA1053537A CA 1053537 A CA1053537 A CA 1053537A CA 255010 A CA255010 A CA 255010A CA 1053537 A CA1053537 A CA 1053537A
- Authority
- CA
- Canada
- Prior art keywords
- valve
- discs
- intercept
- steam
- stop
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K1/00—Lift valves or globe valves, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces
- F16K1/16—Lift valves or globe valves, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces with pivoted closure-members
- F16K1/18—Lift valves or globe valves, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces with pivoted closure-members with pivoted discs or flaps
- F16K1/22—Lift valves or globe valves, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces with pivoted closure-members with pivoted discs or flaps with axis of rotation crossing the valve member, e.g. butterfly valves
-
- 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
- F01D17/00—Regulating or controlling by varying flow
- F01D17/10—Final actuators
- F01D17/12—Final actuators arranged in stator parts
- F01D17/14—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits
- F01D17/141—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits by means of shiftable members or valves obturating part of the flow path
- F01D17/145—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits by means of shiftable members or valves obturating part of the flow path by means of valves, e.g. for steam turbines
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T137/00—Fluid handling
- Y10T137/8593—Systems
- Y10T137/87917—Flow path with serial valves and/or closures
Abstract
ABSTRACT OF THE DISCLOSURE
A combined stop and intercept valve is provided for controlling steam flow from a high-pressure steam turbine to a low-pressure steam turbine and comprises a substantially cylindrical casing having two identical butterfly discs fixed to rotatable shafts and disposed within the casing one immediately downstream of the other.
Under normal operating conditions, both the stop (upstream) and intercept (downstream) valves are opened providing a relatively unrestricted passage for the flow of steam.
During a turbine overspeed condition when the turbine speed reaches 103% of rated speed, the intercept valve closes substantially all the way. The stop valve backs up the intercept valve. Should the turbine speed reach 108% of rated speed, the stop valve closes completely shutting off the flow of steam to the low-pressure turbine. When opened, the discs partially overlie each other so that any wakes in the stream flow produced by the stop disc will not cause the intercept disc to flutter. The interior of the casing is provided with annular grooves which receive valve seats with which the discs mate in a face sealing arrangement. The positions of the seats in the grooves may be adjusted in an axial direction to maintain optimum sealing with the discs when the shafts flex under the pressure of the steam flow.
A combined stop and intercept valve is provided for controlling steam flow from a high-pressure steam turbine to a low-pressure steam turbine and comprises a substantially cylindrical casing having two identical butterfly discs fixed to rotatable shafts and disposed within the casing one immediately downstream of the other.
Under normal operating conditions, both the stop (upstream) and intercept (downstream) valves are opened providing a relatively unrestricted passage for the flow of steam.
During a turbine overspeed condition when the turbine speed reaches 103% of rated speed, the intercept valve closes substantially all the way. The stop valve backs up the intercept valve. Should the turbine speed reach 108% of rated speed, the stop valve closes completely shutting off the flow of steam to the low-pressure turbine. When opened, the discs partially overlie each other so that any wakes in the stream flow produced by the stop disc will not cause the intercept disc to flutter. The interior of the casing is provided with annular grooves which receive valve seats with which the discs mate in a face sealing arrangement. The positions of the seats in the grooves may be adjusted in an axial direction to maintain optimum sealing with the discs when the shafts flex under the pressure of the steam flow.
Description
This invention relates to combined stop and intercept valves for steam turbines.
In large steam turhine generator sets, it is necessary to control the amount of steam admitted to the steam turbine to control the speed thereof; or, in an emergency situation, such as the loss of the electrical load on the generator, to shut down the turbine completely.
To achieve this control of steam turbine speed, it has been the pract;ce to provide steam valves for controlling steam flow from a high-pressure steam turbine to a low-pressure steam turbine, these valves being individually actuated in response to power plant conditions~ Under normal operating conditions, both a stop valve (upstream) and an intercept valve (downstream~ are opened providing for a maximum amount of steam flow between the high-pressure and low-pressure turbines. During a turbine overspeed condition, when the turbine speed reaches 103% of rated speed, the intercept valve closes substantially all the way to shut off the supply of steam to the low-pressure ~urbine. The stop valve backs up the intercept valve.
Should the turbine speed reach 108% of rated speed, the stop valve closes completely in response to a general turbine trip, shutting off the supply of steam to the low-pressure turbine. Should the overspeed condition be relieved before the general turbine trip and the resulting closing of the stop valve, the intercept valve may be opened restoring the supply of steam to the low-pressure turbine without shutting down the turbine.
Prior art combined stop and intercept valves are of a cup and plunger type. Such a cup and plunger type combined stop and intercept valve, which includes a generally annUlar seat engageable by a cup-shaped intercept ~0S;~537 valve element and a plung~r-shaped stop valve element, has certain disadvantages. One such disadvantage is that it is necessary to turn the steam flow through the valve through a 90 angle, removing substantial quantities of available energy from the steam flow. In addition, the cup-shaped and plunger-shaped members cannot be formed in an aerodynamic shape, contributing further to the losses associated with this prior art valve. The cup and plunger type combined stop and intercept valve is also costly to manufacture.
To overcome the deficiencies of prior art cup and plunger type combined stop and intercept valves, the present invention provides a combined stop and intercept valve employing butterfly discs as both stop and intercept ` valve elements and arranged in line with the steam flow between the high and low-pressure turbines. Butterfly valves have been used in the past to control the flow of steam to a steam turbine. ~owever, in prior art serial arrangements of two or more butterfly discs, the downstream disc exhibited a fluttering in the wake o~ the fluid flowing around the upstream disc, removing substantial amounts of available energy from the flow.
, Therefore, it is an object of this invention to provide an improved stop and intercept valve disposed between and in fluid communication with a high-pressure and a low-pressure steam turbine wherein a downstream valve element will not be affected by a wake of the steam flowing around an upstream valve element thereby preventing - the removal of available energy from the steam flow.
It is another object of this invention to provide an improved combined ~top and intercept valve disposed between and in communication with a high-pressure and : - 2 -10~i3537 17TU-2219 low-pressure steam turbine wherein changing the direction of the steam flow through the valve is eliminated thereby avoiding losses of available energy from the steam flow.
It is another object of this invention to provide an improved combined stop and intercept valve disposed between and in fluid communication with a high-pressure and a low-pressure steam turbine wherein the valve elements are of aerodynamic shape minimizing the removal of available energy from the flow of steam through the valve.
It is another object of this invention to provide an improved combined stop and intercept valve disposed between and in fluid communication with a high-pressure and a low-pressure steam turbine which is less expensive to produce than prior art combined stop and intercept valves.
The objects of the present invention in one embodiment thereof are attained by providing a combined stop and intercept valve, wherein both the stop and intercept portions are of the butterfly type. The combined - stop and intercept valve of the present invention comprises a substantially cylindrical casing having two identical butterfly discs fixed to rotatable shafts and disposed within the casing, one immediately downstream of the other.
One disc operates as the stop portion of the valve; the other operates as the intercept portion. Both butterfly discs are of an aerodynamic shape and are axially spaced . ~
~ apart a distance less than one disc diameter such that ;, when they are open, they overlie each other, thereby preventing the fluttering of the downstream disc in the wake of the ~pstream disc. The interior of the casing is provided with annular grooves which receive valve seats mating in a face sealing arrangement with the butterfly discs.
This face sealing arrangement insures that no binding .
-- . . :
between the discs and the seats irnpeding the rotation of the shafts will occur. The seats are adjustably positioned in the grooves to insure the effective sealing of the discs with the seats under conditions of shaft flexure.
FIG. 1 is a view in partial section of a prior art cup and plunger-type combined stop and intercept valve.
F~G. 2 is a view in partia~ section of a preferred embodiment of the invention.
FIG. 3 is a plan view of a butterfly disc employed in the preferred embodiment of the invention.
FIG. 4 is a view of that portion of the valve seat enclosed within the dotted line in FIG. 2, enlarged ^ to show details of the valve seat structure.
FIG. 5 is an exploded view of one of the seats employed in the valve of the present invention.
FIG. 6 is a perspective view of a portion of one of the seats of the valve of the present invention. ~ ~ -- FIGS. 7 and 8 are views in partial section of one of the butterfly discs and a mating seat employed in the ' 20 preferred embodiment of the invention simplified to more clearly bring out a specific feature thereof.
Referring to FIG. 1, there is shown a prior art ` cup and plunger-type combined stop and intercept valve.
Th;s valve comprises a valve casing 1, a generally annular valve seat 2 engageable by a plunger-shaped valve element 3 and a cup-shaped valve element 4, each element being actuated by an individual hydraulic actuator. Steam flow enters the valve through pipe 5 and exits the valve through pipe 6. Valve element 4 and seat 2 comprise an intercept portion of the valve and valve element 3 and j seat 2 comprise a back-up or stop portion of the valve.
This stop portion is provided to completely block the flow of steam to the turbine should the intercept va~ve fail to function. It can be seen that in employing such a cup and plunger-type combined stop and intercept valve, it is necessary because of casing design constraints, to turn the flow of steam passing through the valve 90, removing a substantial quantity of available energy from the steam and lowering the pressure thereof. Moreover, the cup and plunger valve elements are not aerodynamic in shape and therefore cause an additional pressure drop across this valve. The removal of available energy from the steam flow and the pressure drop across the valve associated with that removal adversely affect the performance of the steam turbine and, therefore, the entire large steam turbine generator ;~ set.
Referring now to FIGS. 2, 3 and 4, there is shown an improved combined stop and intercept valve employed between and in fluid communication with a high and a low-pressure steam turbine and employing a generally cylindrical casing 7 provided with grooves 8 in its interior surface. ~he grooves 8 accept valve seats 9 and spacers 10 for adjusting the position of each seat within the .~
corresponding groove.
The valve of the present invention is provided with two shafts 11 mounted for rotation wîthin casing 7 and keyed by keys 12 to two butterfly discs 13. Each disc engages its mating seat in a face sealing arrangement along a lip 14 provided in seats 9 (see FIG. 5). One of the discs and its associated seat provide an intercept portion of the valve of the present invention while the remaining - 30 disc and its associated seat provide the stop portion of the valve.
Because of the face sealing arrangement of the ~053~537 l7TU-2219 discs and the seats of the valve of the present invention, there is no friction between these members and hence no possibility of any binding therebetween. This insures effective opening and closing of the discs. Moreover, this face sealing arrangement enables the seats to absorb substantial quantities of energy when the discs are impacted thereagainst in, for example, an emergency closing situation.
The ability of the seats to absorb this impact energy reduces the stresses in shafts 11 and the actuators there-for during such closing.
; As can be seen from FIG. 2, the discs 13 have an aerodynamic shape to minimize fluid losses and thus the pressure drop across the valve. Additionally, the stop portion of the valve is disposed close enough to the inter-cept portion within one disc diameter so that when the valve is open, as shown by the dotted line representation of the d~scs in FIG. 2, the discs overlap. This prevents the fluttering of the downstream disc in the wake of the steam flow around the upstream disc and thereby reduces ; 20 any fluid losses within the valve.
Referring again to FIGS. 2, 3 and 4, it can be seen that each valve disc comprises first and second substantially cixcular overlying plates 15 and 16 held together by a plurality of bolts 17 or other suitable fasteners. Referring more particularly to FIG. 3, it can be seen that each plate is provided with a first portion 18 having a radius R1 slightly larger than the radius R2 of a second portion 19. Each disc, as employed in the valve of the present invention, is formed by disposing first plate 15 in an overlying relation with second plate 16 such that that portion of plate 15 of smaller radius R2 overlies that portion of plate 16 of .
, ~0~3537 larger radius ~1- Similarly, that portion of plate 15 having a larger radius Rl overlies that portion of plate 16 of smaller radius R2. The peripheral portions of larger radius Rl of each of the plates 15 and 16 form sealing surfaces 20 of discs 13~ It can be seen that each disc 13 is provided with two such sealing surfaces in a co-planar arrangement.
Referring now to FIGS. 4, 5 and 6 there is shown seat 9 disposed in groove 8 formed in the interior of casing 7. Each seat is adjustakly positioned within the groove by spacer elements 10 of varying widths. As shown in FIGS. 5 and 6 each seat 9 is formed from two generally opposed se~iannular seat members 21 and 22. It can be seen from FIG. 6 that the lips 14 in two mating semiannular members define a sealing plane disposed approximately 1~
from vertical. This sealing plane mates with peripheral sealing surfaces 20 of the corresponding valve disc 13 (see FIG. 2).
It can be seen that the valve of the present invention is economical to manufacture because a number of duplicate parts are employed therein. For example, the seats of both the stop and intercept portions are identical as are the butterfly discs and the shafts to which the discs are keyed. Likewise, both discs are formed from identical plates. Similarly, both seats are formed from identical semiannular members. Therefore, unlike the prior art cup and plunger-type combined stop and inter-cept valves, the duplicate parts employed in the valve of the present invention maXe that valve economical to produce.
Referring now to FIGS. 7 and 8, there are shown simplified representations of valve discs 13 and semi-annular members 21 and 22. For convenience of representa-tion, seats 9 are represented as thin semiannular seat members mating with discs 13 in a vertical plane. In the arrangement to be described, to provide an effective seal between disc 13 and semiannular members 21 and 22 during conditions of shaft flexure, a slight leak between the disc and one of these seat members is built into t~e valve of the present invention. When the valve is closed blocking the supply of steam, the steam pressure may cause the shaft to deflect a distance ~ to the right. As shown in FIG. 7, if the semiannular seat members are arranged so that lips 14 define a single plane, the deflection of the shaft a distance ~ to the right causes the disc to engage ; semiannular seat member 21 at point 23 thereby angularly displacing the disc from its face sealing engagement with this semiannular seat member and opening a relatively large area 24 at the upper portion of the valve to the - flow of leakage steam.
In the present invention, this problem is over-come by the provision of spacers of varying widths 10 within grooves 8 allowing the upper semiannular seat member 21 to be offset to the right a distance ~ with respect to - lower semiannular seat member 22, as shown in FIG. 8.
When semiannular seat member 21 is thus offset, a shaft deflection of distance ~ will cause seating surface 20 ::`
at the upper portion of the disc to engage this semiannular seat member substantially all the way around its circum-ference. Moreover, as also shown in FIG. 8, by offsetting - semiannular seat member 21, the lower portion of the disc is only displaced a distance ~ from the lower semiannular seat member 22. Since the disc in this arrangement is only axially displaced a distance ~ rather than , . .. . . . . . . . . . . .
angularly displaced as in the arrangement shown in FIG. 7, only a very small area is opened at the lower portion of the disc to the flow of leakage steam as compared to the large area opened at 24 of FIG. 7. Therefore, it can be seen that a provision of spacers 10 of varying widths allows the variable positioning of valve seats 9 within grooves 8, preventing much of the leakage due to shaft flexing which could ordinarily occur between a disc and a mating unadjustable seat.
1~ It can be seen then, that the combined stop and intercept valve of the present invention is economical to manufacture due to the use of duplicate parts and efficient, i.e., free from many of the fluid losses associated with prior art combined stop and intercept valves, due to the aerodynamic shape of the discs and the spacing of the discs allowing them to overlap when the valve is open, providing a straight path for the steam flow. The combined stop and intercept valve of the present invention is reliable since there is no friction between the valve discs and the seats therefor. Additionally the shafts to which the discs are keyed employed in the ` valve of the present invention are not subjected to large magnitudes of stress upon emergency closing of the valve f~ since the valve seats in their face sealing engagement with the discs absorb much of the energy of the discs in their closing. Moreover, the provision of means to axially adjust the position of the semiannular seat members within the grooves accommodating those seats insures that the valve will not leak substantially should the shafts to which the discs are keyed flex under steam pressures of large magnitude~
_ g .
1~53537 Modifications of the apparatus may be employed by those skilled in the art without departing from thi.s invention and it is intended by the appended claims to cover such modifications.
~'"' .
;. :
:
,.
.
., ~
.
,
In large steam turhine generator sets, it is necessary to control the amount of steam admitted to the steam turbine to control the speed thereof; or, in an emergency situation, such as the loss of the electrical load on the generator, to shut down the turbine completely.
To achieve this control of steam turbine speed, it has been the pract;ce to provide steam valves for controlling steam flow from a high-pressure steam turbine to a low-pressure steam turbine, these valves being individually actuated in response to power plant conditions~ Under normal operating conditions, both a stop valve (upstream) and an intercept valve (downstream~ are opened providing for a maximum amount of steam flow between the high-pressure and low-pressure turbines. During a turbine overspeed condition, when the turbine speed reaches 103% of rated speed, the intercept valve closes substantially all the way to shut off the supply of steam to the low-pressure ~urbine. The stop valve backs up the intercept valve.
Should the turbine speed reach 108% of rated speed, the stop valve closes completely in response to a general turbine trip, shutting off the supply of steam to the low-pressure turbine. Should the overspeed condition be relieved before the general turbine trip and the resulting closing of the stop valve, the intercept valve may be opened restoring the supply of steam to the low-pressure turbine without shutting down the turbine.
Prior art combined stop and intercept valves are of a cup and plunger type. Such a cup and plunger type combined stop and intercept valve, which includes a generally annUlar seat engageable by a cup-shaped intercept ~0S;~537 valve element and a plung~r-shaped stop valve element, has certain disadvantages. One such disadvantage is that it is necessary to turn the steam flow through the valve through a 90 angle, removing substantial quantities of available energy from the steam flow. In addition, the cup-shaped and plunger-shaped members cannot be formed in an aerodynamic shape, contributing further to the losses associated with this prior art valve. The cup and plunger type combined stop and intercept valve is also costly to manufacture.
To overcome the deficiencies of prior art cup and plunger type combined stop and intercept valves, the present invention provides a combined stop and intercept valve employing butterfly discs as both stop and intercept ` valve elements and arranged in line with the steam flow between the high and low-pressure turbines. Butterfly valves have been used in the past to control the flow of steam to a steam turbine. ~owever, in prior art serial arrangements of two or more butterfly discs, the downstream disc exhibited a fluttering in the wake o~ the fluid flowing around the upstream disc, removing substantial amounts of available energy from the flow.
, Therefore, it is an object of this invention to provide an improved stop and intercept valve disposed between and in fluid communication with a high-pressure and a low-pressure steam turbine wherein a downstream valve element will not be affected by a wake of the steam flowing around an upstream valve element thereby preventing - the removal of available energy from the steam flow.
It is another object of this invention to provide an improved combined ~top and intercept valve disposed between and in communication with a high-pressure and : - 2 -10~i3537 17TU-2219 low-pressure steam turbine wherein changing the direction of the steam flow through the valve is eliminated thereby avoiding losses of available energy from the steam flow.
It is another object of this invention to provide an improved combined stop and intercept valve disposed between and in fluid communication with a high-pressure and a low-pressure steam turbine wherein the valve elements are of aerodynamic shape minimizing the removal of available energy from the flow of steam through the valve.
It is another object of this invention to provide an improved combined stop and intercept valve disposed between and in fluid communication with a high-pressure and a low-pressure steam turbine which is less expensive to produce than prior art combined stop and intercept valves.
The objects of the present invention in one embodiment thereof are attained by providing a combined stop and intercept valve, wherein both the stop and intercept portions are of the butterfly type. The combined - stop and intercept valve of the present invention comprises a substantially cylindrical casing having two identical butterfly discs fixed to rotatable shafts and disposed within the casing, one immediately downstream of the other.
One disc operates as the stop portion of the valve; the other operates as the intercept portion. Both butterfly discs are of an aerodynamic shape and are axially spaced . ~
~ apart a distance less than one disc diameter such that ;, when they are open, they overlie each other, thereby preventing the fluttering of the downstream disc in the wake of the ~pstream disc. The interior of the casing is provided with annular grooves which receive valve seats mating in a face sealing arrangement with the butterfly discs.
This face sealing arrangement insures that no binding .
-- . . :
between the discs and the seats irnpeding the rotation of the shafts will occur. The seats are adjustably positioned in the grooves to insure the effective sealing of the discs with the seats under conditions of shaft flexure.
FIG. 1 is a view in partial section of a prior art cup and plunger-type combined stop and intercept valve.
F~G. 2 is a view in partia~ section of a preferred embodiment of the invention.
FIG. 3 is a plan view of a butterfly disc employed in the preferred embodiment of the invention.
FIG. 4 is a view of that portion of the valve seat enclosed within the dotted line in FIG. 2, enlarged ^ to show details of the valve seat structure.
FIG. 5 is an exploded view of one of the seats employed in the valve of the present invention.
FIG. 6 is a perspective view of a portion of one of the seats of the valve of the present invention. ~ ~ -- FIGS. 7 and 8 are views in partial section of one of the butterfly discs and a mating seat employed in the ' 20 preferred embodiment of the invention simplified to more clearly bring out a specific feature thereof.
Referring to FIG. 1, there is shown a prior art ` cup and plunger-type combined stop and intercept valve.
Th;s valve comprises a valve casing 1, a generally annular valve seat 2 engageable by a plunger-shaped valve element 3 and a cup-shaped valve element 4, each element being actuated by an individual hydraulic actuator. Steam flow enters the valve through pipe 5 and exits the valve through pipe 6. Valve element 4 and seat 2 comprise an intercept portion of the valve and valve element 3 and j seat 2 comprise a back-up or stop portion of the valve.
This stop portion is provided to completely block the flow of steam to the turbine should the intercept va~ve fail to function. It can be seen that in employing such a cup and plunger-type combined stop and intercept valve, it is necessary because of casing design constraints, to turn the flow of steam passing through the valve 90, removing a substantial quantity of available energy from the steam and lowering the pressure thereof. Moreover, the cup and plunger valve elements are not aerodynamic in shape and therefore cause an additional pressure drop across this valve. The removal of available energy from the steam flow and the pressure drop across the valve associated with that removal adversely affect the performance of the steam turbine and, therefore, the entire large steam turbine generator ;~ set.
Referring now to FIGS. 2, 3 and 4, there is shown an improved combined stop and intercept valve employed between and in fluid communication with a high and a low-pressure steam turbine and employing a generally cylindrical casing 7 provided with grooves 8 in its interior surface. ~he grooves 8 accept valve seats 9 and spacers 10 for adjusting the position of each seat within the .~
corresponding groove.
The valve of the present invention is provided with two shafts 11 mounted for rotation wîthin casing 7 and keyed by keys 12 to two butterfly discs 13. Each disc engages its mating seat in a face sealing arrangement along a lip 14 provided in seats 9 (see FIG. 5). One of the discs and its associated seat provide an intercept portion of the valve of the present invention while the remaining - 30 disc and its associated seat provide the stop portion of the valve.
Because of the face sealing arrangement of the ~053~537 l7TU-2219 discs and the seats of the valve of the present invention, there is no friction between these members and hence no possibility of any binding therebetween. This insures effective opening and closing of the discs. Moreover, this face sealing arrangement enables the seats to absorb substantial quantities of energy when the discs are impacted thereagainst in, for example, an emergency closing situation.
The ability of the seats to absorb this impact energy reduces the stresses in shafts 11 and the actuators there-for during such closing.
; As can be seen from FIG. 2, the discs 13 have an aerodynamic shape to minimize fluid losses and thus the pressure drop across the valve. Additionally, the stop portion of the valve is disposed close enough to the inter-cept portion within one disc diameter so that when the valve is open, as shown by the dotted line representation of the d~scs in FIG. 2, the discs overlap. This prevents the fluttering of the downstream disc in the wake of the steam flow around the upstream disc and thereby reduces ; 20 any fluid losses within the valve.
Referring again to FIGS. 2, 3 and 4, it can be seen that each valve disc comprises first and second substantially cixcular overlying plates 15 and 16 held together by a plurality of bolts 17 or other suitable fasteners. Referring more particularly to FIG. 3, it can be seen that each plate is provided with a first portion 18 having a radius R1 slightly larger than the radius R2 of a second portion 19. Each disc, as employed in the valve of the present invention, is formed by disposing first plate 15 in an overlying relation with second plate 16 such that that portion of plate 15 of smaller radius R2 overlies that portion of plate 16 of .
, ~0~3537 larger radius ~1- Similarly, that portion of plate 15 having a larger radius Rl overlies that portion of plate 16 of smaller radius R2. The peripheral portions of larger radius Rl of each of the plates 15 and 16 form sealing surfaces 20 of discs 13~ It can be seen that each disc 13 is provided with two such sealing surfaces in a co-planar arrangement.
Referring now to FIGS. 4, 5 and 6 there is shown seat 9 disposed in groove 8 formed in the interior of casing 7. Each seat is adjustakly positioned within the groove by spacer elements 10 of varying widths. As shown in FIGS. 5 and 6 each seat 9 is formed from two generally opposed se~iannular seat members 21 and 22. It can be seen from FIG. 6 that the lips 14 in two mating semiannular members define a sealing plane disposed approximately 1~
from vertical. This sealing plane mates with peripheral sealing surfaces 20 of the corresponding valve disc 13 (see FIG. 2).
It can be seen that the valve of the present invention is economical to manufacture because a number of duplicate parts are employed therein. For example, the seats of both the stop and intercept portions are identical as are the butterfly discs and the shafts to which the discs are keyed. Likewise, both discs are formed from identical plates. Similarly, both seats are formed from identical semiannular members. Therefore, unlike the prior art cup and plunger-type combined stop and inter-cept valves, the duplicate parts employed in the valve of the present invention maXe that valve economical to produce.
Referring now to FIGS. 7 and 8, there are shown simplified representations of valve discs 13 and semi-annular members 21 and 22. For convenience of representa-tion, seats 9 are represented as thin semiannular seat members mating with discs 13 in a vertical plane. In the arrangement to be described, to provide an effective seal between disc 13 and semiannular members 21 and 22 during conditions of shaft flexure, a slight leak between the disc and one of these seat members is built into t~e valve of the present invention. When the valve is closed blocking the supply of steam, the steam pressure may cause the shaft to deflect a distance ~ to the right. As shown in FIG. 7, if the semiannular seat members are arranged so that lips 14 define a single plane, the deflection of the shaft a distance ~ to the right causes the disc to engage ; semiannular seat member 21 at point 23 thereby angularly displacing the disc from its face sealing engagement with this semiannular seat member and opening a relatively large area 24 at the upper portion of the valve to the - flow of leakage steam.
In the present invention, this problem is over-come by the provision of spacers of varying widths 10 within grooves 8 allowing the upper semiannular seat member 21 to be offset to the right a distance ~ with respect to - lower semiannular seat member 22, as shown in FIG. 8.
When semiannular seat member 21 is thus offset, a shaft deflection of distance ~ will cause seating surface 20 ::`
at the upper portion of the disc to engage this semiannular seat member substantially all the way around its circum-ference. Moreover, as also shown in FIG. 8, by offsetting - semiannular seat member 21, the lower portion of the disc is only displaced a distance ~ from the lower semiannular seat member 22. Since the disc in this arrangement is only axially displaced a distance ~ rather than , . .. . . . . . . . . . . .
angularly displaced as in the arrangement shown in FIG. 7, only a very small area is opened at the lower portion of the disc to the flow of leakage steam as compared to the large area opened at 24 of FIG. 7. Therefore, it can be seen that a provision of spacers 10 of varying widths allows the variable positioning of valve seats 9 within grooves 8, preventing much of the leakage due to shaft flexing which could ordinarily occur between a disc and a mating unadjustable seat.
1~ It can be seen then, that the combined stop and intercept valve of the present invention is economical to manufacture due to the use of duplicate parts and efficient, i.e., free from many of the fluid losses associated with prior art combined stop and intercept valves, due to the aerodynamic shape of the discs and the spacing of the discs allowing them to overlap when the valve is open, providing a straight path for the steam flow. The combined stop and intercept valve of the present invention is reliable since there is no friction between the valve discs and the seats therefor. Additionally the shafts to which the discs are keyed employed in the ` valve of the present invention are not subjected to large magnitudes of stress upon emergency closing of the valve f~ since the valve seats in their face sealing engagement with the discs absorb much of the energy of the discs in their closing. Moreover, the provision of means to axially adjust the position of the semiannular seat members within the grooves accommodating those seats insures that the valve will not leak substantially should the shafts to which the discs are keyed flex under steam pressures of large magnitude~
_ g .
1~53537 Modifications of the apparatus may be employed by those skilled in the art without departing from thi.s invention and it is intended by the appended claims to cover such modifications.
~'"' .
;. :
:
,.
.
., ~
.
,
Claims
1. In a combined stop and intercept valve disposed between and in fluid communication with a high-pressure stage and a low-pressure stage of a steam turbine, the improvement comprising:
a) a generally cylindrical valve casing having annular grooves disposed in the interior surface thereof;
b) first and second shafts mounted for rotation within said casing;
c) first and second substantially circular aero-dynamic butterfly valve discs rotatably mounted within said casing on said shafts, said discs being axially spaced apart a distance less than one disc di meter such that a portion of said second disc overlaps a portion of said first disc when said valve is open, each of said discs comprising two offset overlying plates, the offset portions of said plates defining flat sealing surfaces;
d) first and second valve seats disposed within said annular grooves and in face sealing engagement with said flat sealing surfaces of said discs when said valve is closed each of said valve seats comprising two generally opposed semi-annular seat members; and e) spacing means to adjustably vary the position of one of said semiannular seat members within its groove relative to the opposed semiannular seat member.
a) a generally cylindrical valve casing having annular grooves disposed in the interior surface thereof;
b) first and second shafts mounted for rotation within said casing;
c) first and second substantially circular aero-dynamic butterfly valve discs rotatably mounted within said casing on said shafts, said discs being axially spaced apart a distance less than one disc di meter such that a portion of said second disc overlaps a portion of said first disc when said valve is open, each of said discs comprising two offset overlying plates, the offset portions of said plates defining flat sealing surfaces;
d) first and second valve seats disposed within said annular grooves and in face sealing engagement with said flat sealing surfaces of said discs when said valve is closed each of said valve seats comprising two generally opposed semi-annular seat members; and e) spacing means to adjustably vary the position of one of said semiannular seat members within its groove relative to the opposed semiannular seat member.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/588,767 US4020869A (en) | 1975-06-20 | 1975-06-20 | Combined stop and intercept valve for steam turbines |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1053537A true CA1053537A (en) | 1979-05-01 |
Family
ID=24355219
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA255,010A Expired CA1053537A (en) | 1975-06-20 | 1976-06-16 | Combined stop and intercept valve for steam turbines |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4020869A (en) |
| JP (1) | JPS521304A (en) |
| CA (1) | CA1053537A (en) |
| CH (1) | CH600210A5 (en) |
| DE (1) | DE2626474A1 (en) |
| FR (1) | FR2315049A1 (en) |
| GB (1) | GB1546149A (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4266753A (en) * | 1975-10-18 | 1981-05-12 | Kubota, Ltd. | Butterfly valve |
| WO1988001051A1 (en) * | 1986-08-07 | 1988-02-11 | The Secretary Of State For Environment In Her Brit | Fluctuating stress generating apparatus and method |
| US4846281A (en) * | 1987-08-27 | 1989-07-11 | Otis Engineering Corporation | Dual flapper valve assembly |
| JPH0162260U (en) * | 1987-10-13 | 1989-04-20 | ||
| US4832079A (en) * | 1988-03-15 | 1989-05-23 | Sterner Industries, Inc. | Dual valve system |
| JPH0577287U (en) * | 1992-03-26 | 1993-10-22 | 浩一 松岡 | Storage device for socks knitted fabric |
| JP2515842Y2 (en) * | 1992-08-07 | 1996-10-30 | 浩一 松岡 | Sock knitted fabric container |
| DE10219948A1 (en) | 2002-05-03 | 2003-11-13 | Alstom Switzerland Ltd | steam turbine |
| ITBO20040124A1 (en) * | 2004-03-01 | 2004-06-01 | Vima Impianti S R L | VALVE DEVICE |
| DE102007036244A1 (en) * | 2007-08-02 | 2009-02-05 | Adams Gmbh & Co Armaturen Kg | Shut-off valve with anchored sealing element |
| DE102010042924A1 (en) * | 2010-10-26 | 2012-04-26 | Siemens Aktiengesellschaft | Valve for controlling flow of working medium of steam turbine, has lateral edge areas which are extended towards seal surfaces to rotational axis with rotation of position element into closing position sealing to plant at seal surfaces |
| WO2012055041A1 (en) * | 2010-10-26 | 2012-05-03 | Blue Energy Canada Inc. | Tidal flow modulator |
| US10041367B2 (en) | 2013-12-12 | 2018-08-07 | General Electric Company | Axially faced seal system |
| US10234039B2 (en) * | 2017-05-18 | 2019-03-19 | Dresser, Llc | Arranging butterfly valves for positive sealing of a valve assembly |
| CN112648023A (en) * | 2020-12-14 | 2021-04-13 | 国家能源(山东)工程技术有限公司 | Valve control card for preventing main steam valve of steam turbine from being closed by mistake and control method |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1332000A (en) * | 1918-03-24 | 1920-02-24 | Allis Chalmers Mfg Co | Valve device |
| US1682075A (en) * | 1925-12-09 | 1928-08-28 | Pelton Water Wheel Co | Water-tight seat for butterfly valves |
| DE729356C (en) * | 1941-01-14 | 1942-12-14 | Babcock & Wilcox Dampfkessel W | Throttle valve for smoke gas ducts |
| US2946554A (en) * | 1956-06-13 | 1960-07-26 | Desomatic Products Inc | Butterfly valve |
| US3048363A (en) * | 1957-02-21 | 1962-08-07 | Garrigan Helen | Butterfly valve |
| US3144040A (en) * | 1958-02-11 | 1964-08-11 | Baldwin Lima Hamilton Corp | Butterfly valve |
| US3393697A (en) * | 1958-03-10 | 1968-07-23 | Pratt Co Henry | Valve seat |
| GB881436A (en) * | 1958-12-11 | 1961-11-01 | Herbert Sydney Jeffery | Butterfly valve |
| DE1236709B (en) * | 1962-08-02 | 1967-03-16 | Maschf Augsburg Nuernberg Ag | Shut-off device for round or rectangular hot air and smoke gas ducts |
| GB1084452A (en) * | 1962-12-15 | 1967-09-20 | Standard Motor Co Ltd | Transmission unit for a motor vehicle |
-
1975
- 1975-06-20 US US05/588,767 patent/US4020869A/en not_active Expired - Lifetime
-
1976
- 1976-06-12 DE DE19762626474 patent/DE2626474A1/en active Pending
- 1976-06-15 FR FR7618083A patent/FR2315049A1/en active Granted
- 1976-06-16 CA CA255,010A patent/CA1053537A/en not_active Expired
- 1976-06-17 CH CH776176A patent/CH600210A5/xx not_active IP Right Cessation
- 1976-06-18 GB GB25415/76A patent/GB1546149A/en not_active Expired
- 1976-06-18 JP JP51071288A patent/JPS521304A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5523324B2 (en) | 1980-06-23 |
| FR2315049A1 (en) | 1977-01-14 |
| JPS521304A (en) | 1977-01-07 |
| US4020869A (en) | 1977-05-03 |
| CH600210A5 (en) | 1978-06-15 |
| DE2626474A1 (en) | 1976-12-30 |
| FR2315049B1 (en) | 1982-10-08 |
| GB1546149A (en) | 1979-05-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1053537A (en) | Combined stop and intercept valve for steam turbines | |
| US5409351A (en) | Steam turbine with a rotary slide | |
| US8172516B2 (en) | Variable geometry turbine | |
| EP0654587B1 (en) | Turbine with variable inlet geometry | |
| US7258524B2 (en) | Method of regulating the flow rate of air in a rotary shaft of a turbomachine | |
| US4776168A (en) | Variable geometry turbocharger turbine | |
| US5465756A (en) | Butterfly valve plate for a pneumatic surge valve | |
| US3999883A (en) | Variable turbomachine stator | |
| US3232581A (en) | Adjustable turbine inlet nozzles | |
| US4973223A (en) | Variable geometry turbine | |
| US2382913A (en) | Centrifugal compressor | |
| US5269648A (en) | Arrangement for controlling the flow cross section of a turbomachine | |
| EP0101323A2 (en) | Rotary control valves | |
| JP4435425B2 (en) | Integrated bleed regulator system for steam turbines | |
| US5183381A (en) | Variable geometry turbine inlet wall mounting assembly | |
| US5678594A (en) | Value for high temperature fluids | |
| EP3673161B1 (en) | Turbine bypass valve | |
| US6929447B2 (en) | Steam line closing valve and steam turbine plant comprising such a steam line closing valve | |
| US4032252A (en) | Pressure gas engine | |
| EP3842619B1 (en) | Valve assembly for an active clearance control system | |
| EP0898640A1 (en) | A steam turbine | |
| US3693666A (en) | Flow control valve | |
| JPS6397875A (en) | Crossflow turbine | |
| JPS61255220A (en) | Variable nozzle device of exhaust gas turbine supercharger | |
| JPS59155533A (en) | Gas turbine plant |