CH666937A5 - High pressure steam turbine. - Google Patents

Description

666937

PATENT CLAIMS High-pressure steam turbine, consisting essentially of a two-part outer casing, a two-part inner casing and a rotor, the inner casing being held together by shrink rings, characterized in that the separation plane (3) of the inner casing (2) is opposite the separation plane (4) of the outer casing (1) is substantially offset by 90 °.

DESCRIPTION

In the case of high-pressure turbines, the division of the operational pressure and temperature gradient into two housings makes it possible to provide favorable wall thicknesses in terms of both casting technology and stress. The division also results in a favorable flange connection on the outer housing.

The housing technology of the known high-pressure turbines provides an outer housing lower part that is supported on the foundation. The horizontal partial flange of this outer housing half generally has two recesses, each mirror-symmetrical to the longitudinal axis of the turbine, in which the claws of the inner housing lower part are supported. The lower part of the inner housing is thus inserted into the lower part of the outer housing; then the runner can be placed in it. The then placed upper part of the inner housing is screwed to the lower part of the same, whereupon the high-pressure turbine is completed by fitting the upper part of the outer housing.

A pair of claws on the inner housing lies in the plane of the inflow spiral. Since the two partial spirals lying on top of each other have to be sealed from the halves of the inner housing by means of screw connections, the claws cannot directly connect to the inner housing, but only start beyond the screw connections. The consequence of this is that the circumference of the inner casing increases correspondingly with direct repercussions on the outer casing and consequently on the outer dimension of the high-pressure turbine itself. It is now known that any increase in dimensions in high-pressure turbines has a square effect in terms of production costs. The fact that accessibility to the rotor by lifting first the upper part of the outer housing and then the upper part of the inner housing is characterized by certain logistical advantages would perhaps speak for the retention of this housing technology. However, since the highly loaded inner housing is now held together by shrink rings, it must be completely assembled separately before it is inserted. The advantages mentioned above are therefore no longer effective.

The invention seeks to remedy this. The invention, as characterized in the claim, is based on the object of minimizing the outer dimension of the inner housing - and consequently also of the outer housing - of a high-pressure steam turbine.

The advantage of the invention is essentially to be seen in the fact that by displacing the parting plane of the inner housing by essentially 90 ° with respect to the parting plane of the outer housing, the claws can directly connect to the inner housing in the parting plane of the outer housing. Since the separation plane of the inner housing now comes to rest in the area of the inlet connection, the screw connection for the seal can be accommodated here without any problems, without any consequences for the

Unfold the outer dimensions of the inner housing. The assembly process of the high-pressure turbine, based on the fact that the inner casing is now held together by shrink rings, remains the same.

In the drawing, an embodiment of the invention is shown schematically.

The only figure shows: a cross section through a high-pressure turbine in the area of the inlet connection.

The outer housing 1 is divided into a lower part la and an upper part 1b. The parting plane 4 of the outer housing 1 is plane-parallel with the surface of the foundation 17. The inner part 2 is also divided into two parts 2a, 2b, the parting plane 3 of which is offset by 90 ° with respect to the parting plane 4 of the outer part 1. The lower part la of the outer housing preferably has two recesses arranged in mirror symmetry to the longitudinal axis of the high-pressure turbine. A pair of them can be seen in the figure. These recesses 14 shown are in the steam inflow plane 15. The other two are preferably provided towards the end of the blading, that is to say in the outlet region, in order to uniformly support the inner housing 2 with the rotor, which essentially consists of rotor shaft 9 and blading 8. The highly loaded inner housing 2, now vertically divided with respect to the outer housing 1, is held together by shrink rings, not shown. The shrink ring connection enables a rotationally symmetrical centering of the inner housing. This is axially fixed in the plane of the steam inflow 15 at the joint height of the outer housing 1. At the same height, the inner housing 2 is supported on both sides in the recesses 14 of the outer housing 1 via claws 13.

The lateral guidance of the inner housing 2 is ensured in the steam inflow plane 15 by wedges 5 above and below, in the outlet area, not shown, by a centering bolt below. The inflow section of the inner housing 2 is designed in the form of two semi-spirals 16 so that the steam reaches the blades 8 in a well-guided manner. Metallic sealing is carried out in the parting plane 3 of the inlet housing 2. In addition to the shrink ring connection, threaded bolts 6 with nuts 7 are also provided in the inlet connection 2c in order to maintain a 100% seal. The threaded bolts 6 are preferably placed on a circular plane outside the semi-spiral 16, so that the entire inflow cross section is covered well. Depending on the size of the inflow cross section, two and more threaded bolts 6 are to be provided. Because this absolutely necessary screw connection is offset by 90 ° with respect to the parting plane 4 of the outer housing 1, the claws 13 can connect directly to the inner housing 2. Because the threaded bolts 6 have sufficient space radially in the inlet connection 2c, the outer dimension over all of the inner housing 2 is thus determined solely by the projection of the claws 13.

Since the outer dimension of the outer housing 1 is directly dependent on the specification of the inner housing 2, the concept shown here, i.e. the offset of the parting planes 3.4 by 90 ° to each other, a minimization of the outer contour of the high pressure turbine can be achieved. Upper part lb and lower part la of the outer housing 1 are connected by hydraulically tightened expansion screws 11. Correspondingly strong nuts 10 are to be provided for this purpose. Metallic sealing is also carried out in the parting plane 4.

After the inner housing 2 is held together by shrink rings, its assembly can only be

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half of the outer housing 1. As a unit, depending on the design of the inflow connector 2c

Inner housing 2 together with rotor inserted into the lower part 1 a of the outer separation plane 3 to be created there from the ideal 90 ° angle housing 1. It is therefore irrelevant that those of the separation level 4 naturally vary slightly. Separation levels 3 and 4 are offset from one another.

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1 sheet of drawings