US1620662A - Housb electric - Google Patents

Description

March 15, 1927. 1,620,662

A. T. KASLEY TURBINE Filed April 12, 1923 WiiilllillllflljlL 1 [j J a: 50 22 i I'Ifasle WITNESS l INVENTOR y Fig: 2. BY AQQS W ATTORNEY Patented Mar. 15, 1927.

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ALEXANDER '1. KASLEY, OF ESSINGTON, PENNSYLVANIA, ASSIGNOR TO TESTING- I-IOUSE ELECTRIC 8c MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

TURBINE.

My invention relates to turbine installations, more particularly of the marine type employing ahead and astern sections, and it has for its object to provide means for permitting flow of fluid by the pumping action of ahead blading when operated reversely in order to avoid fluid vibrations and consequent vibrations of the ahcad section blading which may be of such magnitude as to result in breakage of the ahead blading.

Apparatus made in accordance with my invention is illustrated in the accompanying drawings forming a part of this application in which Fig. 1 is a diagrammatlc View of a turbine installation incorporating my pressure-relieving means for the ahead blading; and Fig. 2 is a sectional view of a relief valve.

Marine turbines having ahead reaction blading have given trouble due to break ing of such blading when the turbines are operated astern. As astern speed is nor mally lower than ahead speed, apparently breakage is due rather to forced vibrations than to inherent inability of the blading to withstand centrifugal stresses.

It is well known that reaction turbines when operated reversely develop a compressor or pumping action, and experience shows that, with turbine blowers, excessive fluid vibrations which occur when no flow is permitted have been avoided by allowing for flow. If a turbine of the character referred to is operated reversely, the highpressure end being closed, pressure wa es are set up whose frequency appears to depend in some way upon the rotor speed. If these fluid vibrations or their higher harmonies coincide with the natural period of any of the blading, a resonant condition results and blade breakage may ensue. As the rotor is speeded up, the frequency of fluid vibrations changes and hence it is pos sible that such vibrations may be resonant, as the speed changes, with several rows of blading of different lengths in succession. In accordance with my invention, I provide relief means adjacent to the inlet end of the reaction blading to minimize fluid vibrations and consequent vibrations of the blading.

Referring now to the accompanying drawings for a better understanding. of my invention, in Fig. 1, I show a hlgh-pressure turbine, at 10, which includes an ahead section, at 11, and a reversing or astern section, at 12, and a low-pressure turbine, at 13, which includes an ahead section, at 1 1-, and a reversing or astern section, at 15.

The high-pressure ahead section, at 11, as illustrated, includes impulse blading 16,

which receives steam from an inlet passage 17 having an admission valve 18. After passage through the impulse blading 16, steam then passes through the reaction blades 19, from which it is discharged to. the receiver passage 20 leading to the inlet end of the reaction blading 21 0f the low-pressure ahead section, at 14.

The highpressure reversing or astern section, at 12, is separated from the high-pressure ahead section, at 11, by a diaphragm 22 in order to segregate the exhaust steam of these sections. Steam is supplied to the blading 23 of the high-pressure astern section, at 12, by a conduit or passage 24 havlng an admission valve 25. After discharge from the blading 23, steam then passes through the astern receiver passage 25 to the blading 26 of the low-pressure astern or reversing section, at 15.

The blading 21 of the low-pressure ahead section, at 14, and the blading 26 of the low-pressure astern section, at 15, discharge to a common exhaust connection 27, which leads to any suitable condenser 28.

lVhen the turbines, at 10 and 13, are operated astern, the react- ion blading 19 and 21 is operated reversely and the pumping action thereof develops vibrations or pulsations of elastic fluid which set up forced vibrations of the reaction blading; and, when the frequency of the fluid vibrations is resonantr with the natural period of any of the blading, a dangerous condition results in the resonant blading which may have amplitudes of vibration sufliciently great to result in breakage. Accordingly, it is the object of my invention. to relieve the compression effects dueto the pumping action of the reaction blading: when operated reversely; and, therefore, Iprovide relief passages or connections 29 and 30 for the high-pressure reaction blading 19 and for the low-pressure reaction blading 21, respectively.

As illustrated, the relief connection 29 for the high-pressure reaction bladin 19 consists of a conduit leading from the mlet side of such reaction blading to the receiver passage 20 and it is provided With a valve 31, which is adapted to be open when the astern section, at 12, is in operation. The inlet side of the low-pressure reaction blading 21 is connected to the exhaust by a conduit 30, which is provided with a valve 32 adapted to be open when the astern section, at 15, is in operation.

The valves 31 and 32 may be identical in design and the description of one, with reference to Fig. 2, will suffice. In this view, I show a valve having a movable member 33, connected to a stem 34, and the latter is con nected to a piston 35. The stem 34: of the piston 35 is subject to the effect of a spring 36 tending to open the valve, and fluid under pressure admitted to the cylinder 37 is effective to move the piston 35 against the force of the spring 36 to close the valve.

The cylinders of the valves 31 and 32 are connected to a fluid supply passage 33, which, in turn, is connected to the admission passage 17 between the admission valve 13 and the turbine, at 10. Whenever the admission valve 18 is closed, pressure of fluid exerted on the pistons 35 of the valves 31 and 32 is relieved, permitting the springs 36 to open such valves, so that the passages 29 and 30 may be open to relieve compression due to the pumping action of the reaction blading 19 and 21 when the turbines are ope ated astern. hen the admission valve 18 is opened to supply steam to the ahead turbine sections, steam also passes through the passage 38 and acts upon the pistons 35 to close the valves 31 and 32 against the tension of the springs 36.

While I have described one way of operating the valves 31 and 32 in the relief passages 29 and 30, it is to be understood that my invention is not limited in this respect but that any suitable interconnection may be used between the valves 31 and 32 and the admission valve 18 or the admission valve 25 in order to assure that the valves 31 and 32 are closed when the ahead turbine sections, at 11 and 14, are in operation. and are open when the astern sections, at 12 and 15, are in operation.

The operation of apparatus made in accordance with my invention is evident from the foregoing description. In other words, it will be apparent that I have provided means whereby ahead reaction blading is relieved of forced vibrations due to vibrations or pulsations of elastic fluid produced by reaction blading when operated reversely.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible to various other changes and modifications, without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon, as are imposed by the prior art, or as are specifically set forth in the appended claims.

\Vhat I claim is:

1. A turbine comprisingan ahead section, an admission valve for said ahead section, a passage providing communication between the admission valve and the ahead section, a reversing section, apassage providing comn'iunication between the inlet and exhaust ends of the ahead section, a valve in the second-mentioned passage, means urging said valve to open position, pressure-responsive means for closing said valve, and means in dependent of the second-n'ientioned passage for providing communication between the fi1st-menti0ned passage and the pressure-responsive means.

2. In a turbine installation, in combination, a high-pressure turbine including an ahead section having reaction blading and an astern section, a low-pressure turbine including an ahead section having reaction binding and an astern section, a connection between the exhaust side of the high pressure ahead section and the inlet side of the low pressure ahead section and between the exhaust side of the high pressure astern section and the inlet side of the low pressure astern section, an exhaust connection for the low-pressure ahead and astern sections, a bypass connection between the inlet side of the high-pressure reaction blading and the connection between the inlet side of the low pressure reaction blading and the exhaust side of the high-pressure reaction blading, a bypass connection between the inlet and exhaust sides of the low-pressure reaction blading, valves in the bypass connections, and means dependent upon cutting off the supply of steam to the ahead sections for opening the by-pass valves, whereby pressure of fluid developed by the pumping ac tion of the reaction blading of the ahead sections is'relieved in order to minimize fluid vibrations sufiicient to induce dangerous vibrations of the reaction blading.

In testimony whereof, I have hereunto subscribed my name this ninth day of April,

ALEXANDER T. KASLEY.

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