Safety diaphragm

March 17, 1942.

2,276,830

J. H. DORAN

SAFETY DIAPHRAGM

Filed Sept. 11, 1940

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Patented Mar. 17, 1942

2,276,830

UNITED STATES PATENT OFFICE

2,276,830

SAFETY DIAPHRAGM

John H. Doran, Scotia, N. Y., assignor to General Electric Company, a corporation of New York

Application September 11,1940, Serial No. 356,279

Claim. (Cl. 220—89)

The present invention relates to safety diaphragms for elastic fluid turbine arrangements. More specifically, the invention relates to arrangements including a diaphragm and a cutting edge associated therewith for cutting open the diaphragm upon the occurrence of a predetermined high pressure in the exhaust end of the turbine. In arrangements in which the diaphragm is completely cut it is forced into the power plant room and thereby may cause damage to apparatus with which it may come into contact.

One object of my invention is to provide an improved safety diaphragm arrangement whereby the above danger is substantially eliminated. Another object of my invention is to provide an improved safety diaphragm arrangement in elastic fluid turbines whereby excessive pressures in the exhaust and the inlet portion thereof are eliminated.

For a consideration of what I believe to be novel and my invention, attention is directed to the following description and the claim appended thereto in connection with the accompanying drawing.

In the drawing, Fig. 1 illustrates an elastic fluid turbine arrangement embodying my invention; Fig. 2 is a top view of a safety diaphragm shown in Fig. 1; and Fig. 3 is a section along line 3—3 of Fig. 2.

The arrangement shown in the drawing comprises a high pressure elastic fluid turbine 10 having an exhaust end connected by a crossover conduit I i to the inlet i 2 of a double flow low pressure turbine 13. The latter has two halves 14, i 5 exhausting into an exhaust casing or hood 16. The exhaust hood and the crossover conduit are fabricated and the inner walls of the cross-over conduit are formed by the exhaust hood 13. The turbine rotor is supported on bearings 17, 18 secured to and held on the exhaust hood 13. An arrangement of this kind is more fully disclosed in the patent to O. Junggren, No. 2,102,416, issued December 14,1937, and assigned to the same assignee as the present application. In order to prevent the setting up of excessive pressure in the exhaust casing 16 the latter is provided with a safety or blow-out diaphragm 19 which is cut open upon the occurrence of a predetermined pressure in the exhaust hood to permit exhaust fluid to discharge directly into the atmosphere or other point of low pressure.

In accordance with my invention a similar safety or blow-out diaphragm arrangement 20 is provided with regard to the cross-over conduit io

11. The safety diaphragm arrangements 19, 20 are substantially alike and as shown in Figs. 2 and 3 each safety diaphragm arrangement comprises a diaphragm 21 held between a grid 22 and a ring 23 secured together and fastened to a flanged opening 24 by means of a plurality of bolts 25. A cutting member 26 is fused to the ring 23 and has a cutting edge closely spaced with the diaphragm 21. The purpose of the grid 22 is to support the diaphragm during low pressure conditions existing inside the turbine. The pressure in the exhaust hood during normal operating condition is substantially below that of the atmosphere and the pressure in the crossover conduit is below that of the atmosphere during starting operation. If during operation the pressure inside the exhaust hood or the crossover conduit rises a predetermined value above atmosphere, the corresponding diaphragm 21 is forced away from the supporting grid toward the edge of the cutting member 26 whereby the diaphragm is cut open. In order to retain the central diaphragm portion cut away from the outer or rim portion, means are provided in accordance with my invention whereby the central diaphragm portion is supported on the ring 23. In the present example a cross-bar 27 extending diametrically across the diaphragm is secured to the ring 23 by bolts 28. The bar 27 is formed with a central opening 29. A pin or like member 30 is secured to the central portion of the diaphragm 21 and projects freely through the opening 29. An outer portion of the pin 30 is provided with a cotter pin 31. If now the diaphragm is cut open during operation, the central or cut away portion secured to the pin 30 is retained on the cross bar 27, that is, it can no longer be thrown out into the open power plant room. The pin 30, as will be noticed, forms a clearance with the opening 29 in the cross-bar 27, thereby preventing interference with the free movement of the diaphragm 21 during operation.

Having described the method of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.