US2571707A

US2571707A - Turbine apparatus

Info

Publication number: US2571707A
Application number: US43719A
Authority: US
Inventors: Gottlieb Manious
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1948-08-11
Filing date: 1948-08-11
Publication date: 1951-10-16
Anticipated expiration: 1968-10-16
Also published as: GB664810A

Description

Oct. 16, 1951 M. Gamma 2,571,101

'TURBINE APPARATUS Filed Aug. 11, 1948 3 Sheets-Sheet l wnmzsszs: INVENT Maniaus Goff/i uwilM d'vo pe, BY I an E ATTORN EY Oct. 16, 1951 M. GOTTLIEB TURBINE APPARATUS 3 Sheets-Sheet 3 Filed Aug. 11, 1948 m mm hmkm INVENTOR Man/'00s Goff/fab WITNESSES:

ATTORN EY Patented Oct. 16, 1951 TURBINE APPARATUS Manious Gottlieb, Philadelphia, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 11, 1948, Serial No. 43,719

1 Claim. (Cl. 137-139) The invention relates to turbines and it has for an object to provide apparatus of this character wherein working fluid is supplied to the turbine in accordance with the load by means of an improved relay motivated by working fluid supplied thereto under control of the governor.

With small steam turbines, it is customary tohave a balanced type of admission valve connected to a lever operated by a shaft governor and to provide the turbine with self-lubricating or ring-oiling type journal bearings; With increase in sizefor. capacity of the turbine, the

'admission valve must be made larger and the ployed, it is desirable to keep the latter as small as practicable and to minimize the controlling effort required of it. An oil-operated relay may be interposed between the governor and the admission valve, but this involve the expense and complication of a pump-operated oil system which is not economically justifiable unless the bearings require force-feed lubrication. Furthermore, experience has shown that the plugtype diffuser valve has better flow characteristics and involves less chatter and wear than the ordinary balanced valve. Accordingly, a more particular object of the invention is to make it practicable to build, not only larger turbines of the conventional type above indicated, but, more particularly, turbines of the plug-valve type, by the use of a steam relay under control of the governor.

Another object of the invention is to provide a governor-contro led steam relay operating a plug valve for varying the admission of steam to a turbine to suit the load.

A further object of the invention is to provide a steam turbine having a shaft governor or any small direct-acting governor, applying motion to a lever which controls a steam relay for oper ating a plug valve.

Another object of the invention is to provide a turbine having a steam chest with a valve and steam relay assembly held in place with respect to the steam chest by a steam chest cover carrying means through which the governor exercises control over the relay.

A further object of the invention is to provide a governor-controlled steam relay operating the admission valve of a steam turbine to vary the admission of steam thereto in accordance with the load, wherein the relay is of the differential piston type, with one piston of a differential piston construction directly exposed to inlet passage steam pressure and the other piston thereof exposed to pressure in a cylinder, which is supplied with steam flowing through an orifice from the inlet passage and from which steam is exhausted under control of the governor, and wherein the relay is formed by a tubular member and a core structure having flanges clamped between the steam chest and the steam chest cover flanges with the tubular member providing the seat for the movable valve member connected to the differential piston construction and with the orificed passage formed by the annular clearances between the tubular member and the core structure and between the steam chest cover and the core structure and connected by an orifice formed in the core structure flange and recesses formed in the latter and in the steam chest cover.

Still another object is to provide a governorcontrolled relay of the character just described wherein the components are assembled incident to assembly and fastening thereof with respect to the steam chest and wherein the steam strainer is carried by the core structure in such manner as not to interfere with insertion of the core structure into and removal thereof from the tubular member.

A further object of the invention is to provide a governor-controled steam relay for operating the admission valve with means normally storing energy and which is releasable, in the event of overspeeding of the turbine, to close the admission valve.

The foregoing and other objects are effected by the invention as will be apparent from the following description and claim taken in connection with the accompanying drawings, forming a part of this application. in which:

Fig. 1 is a perspective view of a turbine having the invention applied thereto;

F g. 2 is an axial sectional view of the turbine and the steam chest;

Fig. 3 is an enlarged detail sectional view showing the admission valve of the plug type and operated by a steam relay; and

Fig. 4 is a sectional view taken along the line IVIV of Fi 3.

In the drawings, there is shown a turbine, at 8, having a shaft governor 9 and an emergency governor Ill. The turbine includes a housing H having asteam chest l2 and a steam chest cover it.

The steam chest includes an inlet passage I6 and a space or passage ll for delivering steam to the turbine nozzles l8. The steam chest includes wall structure l9 bounding the inner end of the inlet passage i and having opposed and alined openings 2| and 22 formed therein. The chest also has an opening 23 within which is retained the valve and relay assembly, at 24, by means of the cover M.

The valve and relay assembly, at 24, includes the outer tubular member 25, the core structure 26, differential piston construction, at 21, and a valve member, at 28, preferably of the plug type, all maintained in coaxial relation.

The tubular member 25 has an inner tip portion fitting the opening 2| and joined by cage structure 3| to the portion 32 fitting the opening 22 and it has a flange 33 at its outer end positioned in the rabbeted recess 34 formed in the steam chest flange portion 35 and bounding the opening 23 formed therein.

The core structure 25 is held coaxial with the tubular member 25 by means of a flange 36 at its outer end fitting rabbeted

recesses

31 and 38 formed in the flange 33 and in the steam chest cover flange 39, respectively. The nested flanges 33 and 36 are clamped between the steam chest flange portion 35 and the cover flange 39 by means of bolts 40 connecting the latter to the steam chest wall.

The core structure 25 includes an inner cylinder 4| for the inner piston 42 of the differential piston construction, the outer cylinder 43 for the outer piston 44 of such differential piston construction, and a connecting bore 45 for the stem 46 spacing the pistons, the stem preferably having its inner end connected to the inner piston and having its outer end in thrust engagement with the outer piston 44.

The valve member 28 is preferably of the plug type, it cooperating with the diffuser seat 41 formed in the tubular member tip portion 33 and being connected to the inner piston 42 so that, with the valve closed, the inner piston provides an annular piston area 48 exposed to steam pressure in the inlet passage IS in order that the latter may exert force on the valve member tend ing to open it.

The steam chest cover |4 cooperates with the outer cylinder 43 to provide an expansible chamber 50 to which is exposed the piston area 5| provided by the outer piston 44 and the assembly is provided with means by which steam may be supplied from the inlet passage IE to the expansible chamber 50 to act on the piston area 5| to exert force on the valve member 28 to close it against the force of such pressure acting on the piston area 48, the piston area 5| being sunicient- 1y larger than the piston area 48 for this purpose as well as for the governor-controlled operation to be described.

As shown, steam is supplied from the inlet passage I6 through the annular clearance space 53 between the tubular member 25 and the core structure 26, the orifice 54 and opening 55 formed in the flange 36, the recess 56 formed in the steam chest cover l4 and the annular clearance 51 between the steam chest cover and the outer end of the core structure. The small radial dimension of the clearance 53 makes the latter also useful as a strainer to avoid clogging of the orifice 54.

Steam exhausts from the expansible chamber through a passage including a portion 58 formed in the outer piston 44 and which has its inlet end opening into the expansible chamber 50 through a valve seat 53 with which the governor-controlled needle valve 60 cooperates, the needle valve being carried at the inner end of the governor-operated valve rod 6|. The other end of the exhaust passage 58 opens into the cylinder exhaust space 58a communicating with the exhaust or drain passage 58b formed in the core structure and the cover.

For any position of the needle valve 50, the admission valve 28 and the difierential piston assembly, at 27, take up a position with the opening and closing forces applied to the valve in balanced relation, this relation being secured with flow occurring through the needle valve to maintain the required pressure in the expansible chamber 50 and which pressure is lower than that in the steam inlet passage i5 due to restricted flow occurring through the orifice 54.

If the needle valve is moved to restrict discharge of steam from the expansible chamber, then the pressure therein builds up, unbalancing the balancing relation of pressures, and the piston construction moves inwardly relative to the needle valve to restore the balancing relation of opening and closing pressures. On the other hand, if the needle valve is moved outwardly to increase discharge from the expansible chamber,

the pressure therein decreases, in consequence of which the differential piston construction moves outwardly relative to the needle valve torestore the balancing relation of pressures.

The steam chest cover I4 is formed with a guide 63, axially alined with the valve seat 59, for the valve rod 6| and with a cylindrical bore 64 axially alined with the guide 63. A rabbeted cover 65 is secured to the steam chest cover in covering relation with respect to the bore 64 and it is provided with a guide 65 for the outer end portion of the needle valve rod 6|. The outer end 61 of the valve rod is maintained in thrust engagement with the adjacent end 68 of the lever 69 fulcrumed, at '10, with respect to a bracket 1| carried by the steam chest cover. The rod is moved by means of the spring 12 between the cover 65 and the rod flange 13 having the rod abutment end 61 and by the lever 69 operated by the shaft governor 3.

With the apparatus so far described, it the turbine load increases, thereby tending to reduce the turbine speed, the shaft governor moves the lower abutment end 68 of the lever 69 outwardly, the spring 12 causing the valve rod to follow the lever and to move the needle valve in a direction to increase the flow of steam exhausting from the expansible chamber and thereby to bring about lowering of pressure in the latter to unbalance the opening and closing steam forces applied by the inner and outer piston areas to the admission valve, resulting in movement of the latter and of the differential piston construction outwardly relative to the needle valve until the balanced relation of opening and closing forces is restored. On the other hand, with decrease in load and consequent tendency for increase in turbine speed the needle valve is moved inwardly to restrict the flow of steam exhausting from the expansible chamber, thereby bringing about increase in pressure in the latter and an unbalanced relation of opening and closing steam forces applied to the valve to cause the differential piston and the valve to move inwardly until the balanced relation of forces is restored. Thus, the needle valve is positioned by the governor and the pressure of steam is applied to the differential piston construction to cause it to follow the needle valve.

A cup 14 slidably fits the bore 64 and it has a bottom I provided with an opening I6 through which the valve rod 0| freely passes. A compression spring 11 is positioned in the cup with one end bearing against the bottom 15 and the other end bearing against the cover 65.

The spring 11 is normally held under compression between the bottom 15 and the cover 65 by means of the latch or pawl 18 formed on the rock shaft 19 carried by the steam chest cover and cooperating with the recess 80 provided on-the cup.

Upon overspeeding of the turbine, the emergency governor I 0 moves the member 8| to tilt the rock shaft against biasing means 82 to disengage the pawl or detent 18 from the notch or shoulder 80, thereby releasing the cup, whereupon the latter is moved by the spring 11 to engage with the collar 84 carried by the valve rod and then to move the valve rod inwardly to operate the steam relay and the admission valve to close the latter.

To reset the emergency governor-operated mechanism after shutdown, the steam chest cover I4 is provided with a hand lever 85 fulcrumed, at 85, to the steam chest cover and having its inner end 81 formed to engage with the bottom of the cup to move the latter to the right with compression of the spring 11 until the pawl or detent I8 is free to enter the recess 80 under the influence of its biasing means.

The inner and outer pistons 42 and 44 and the stem 46 are preferably helically grooved as indicated at 89, such grooves not only providing for steam films distributed about the pistons and the stem to reduce friction but space within which dirt, which might otherwise interfere with free movement of the differential piston construction, may collect. Also, to improve sealing and provide friction damping, the inner piston is preferably provided with a piston ring 90 fitting the cylinder 4| and the outer piston 44 has a similar piston ring 9| fitting in the cylinder 56.

The strainer through which steam is supplied to the admission valve 28 is preferably comprised by a cylindrical screen 92 having one end secured in place about the reduced portion 93 formed at the inner end of the core structure, whereby the outside diameter of the screen is kept approximately that of the core structure so that the latter with the attached screen is freely movable into and out of the tubular member 25. The other end of the tubular screen fits the ring 94 located in the annular recess 95 formed in the tip portion 30 of the tubular member. Thus, the ends of the tubular screen may encompass adjacent ends of the core structure and of the ring and be joined or welded thereto without either the outside diameter of the screen or of the ring exceeding the outside diameter of the core structure, whereby the screen is properly located and adequately supported so as not to interfere with freedom of insertion and removal of the core structure.

While the invention has been shown in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.

What is claimed is:

In a steam relay adapted for operation by a governor to position a valve to control the flow of steam from an inlet passage to a turbine and including a differential piston construction operatively connected to said valve, said differential piston construction including inner and outer piston members with the inner piston member disposed between the valve and the outer piston member, said inner piston member having a piston area facing toward the valve and said outer piston member having a piston area larger than the inner piston area and facing away from the valve, inner and outer cylinders for the piston members, means providing for direct application of inlet passage steam pressure to the inner piston area of the inner piston member, means providing for application of steam pressure to the outer piston area of the outer piston member and comprising a passage having an orifice for supplying steam from the inlet passage to the portion'of the outer cylinder to which the outer piston area is exposed, means providing for escape of steam from the outer cylinder including an exhaust passage having a portion provided in the outer piston and which opens through a seat to the portion of the outer cylinder to which said outer piston area of the outer piston is exposed and a valve cooperating with said seat, and means for moving the last-named valve to change the steam pressure acting on the outer piston area of the outer piston to change the balanced relation of opposed forces acting on the differential piston construction in consequence of which the latter moves until the balanced relation of forces acting thereon is restored.

MANIOUS GOTTLIEB.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 861,054 Samuelson July 23, 1907 934,432 Ehrhart Sept. 21, 1909 1,093,116 Cubelic Apr. 14, 1914 1,616,953 Dahlstrand Feb. 8, 1927 FOREIGN PATENTS Number Country Date 275,572 Great Britain Mar. 1, 1928