Pipe joints or couplings – With heating or cooling
Reexamination Certificate
1999-12-27
2001-05-08
Nicholson, Eric K. (Department: 3627)
Pipe joints or couplings
With heating or cooling
C285S187000, C285S368000
Reexamination Certificate
active
06227575
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to an apparatus for the connection of line sections of a line, through which a hot and highly compressed medium flows, in particular a pipeline, through which steam flows.
A steam feed line for a steam turbine is conventionally constructed for a steam temperature of more than 500° C. and for a steam pressure of more than 300 bar. In a steam feed line of this type, the connection point between a steam-feeding pipeline and a steam inlet valve is conventionally of the welded type. In order to break this connection, for example for assembly or inspection purposes on the steam turbine, the line has to be separated mechanically. In the case of a steam turbine with a steam inlet disposed above a housing parting plane, this signifies a considerable additional outlay in inspection of the steam turbine. During assembly, in addition to the time spent in welding and annealing the connection point, there is the problem of a line which is shortened due to the separating cut, so that undesirable mechanical stresses may be introduced into the line when the connection is made again.
Due to a very high transfer of heat through the hot medium into the flange as a consequence of operation, the use of a conventional flanged connection at this point leads to inadmissible thermal stress within the flange and, in particular, in the region of the flange screws. Since the flange screws are subjected to extreme thermal loading, they may relax to a high degree. The relaxation of the flange screws leads, in turn, to an undesirable loss of force exerted on the parting plane, so that the latter often can no longer be kept closed against the high pressure of the medium flowing through the line.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide an apparatus for the connection of line sections which overcomes the above-mentioned disadvantages of the prior art devices of this general type.
With the foregoing and other objects in view there is provided, in accordance with the invention, an apparatus for connecting line sections of a line through which a hot and highly compressed medium flows, including a double-walled flanged connection having an outer flange and an inner flange, the outer flange and the inner flange defining an interspace there-between through which a cooling medium can flow.
The cooling medium flows through the interspace in order to cool the outer flange.
By subjecting the interspace to a cooling medium, for example air, water or steam, in practice an insulating cushion is produced within the flanged connection. A line system provided for the cooling medium may then also be used for intermediate suction extraction that is often provided in a steam feed line of this type. Likewise, in an existing steam turbine plant, intermediate suction extraction may be utilized for flange cooling.
The flange parts to be connected to one another on the end face are formed by a U-shaped collar contour for fitting a respective line section. For positive and non-positive connection, the flange outer wall or the outer flange of the flanged connection is merely screw-connected by a number of flange screws disposed, distributed, on the circumference the flange. In this case, the two mutually opposite outer flange sections are advantageously provided, on the end face, with corresponding shoulder or step contours, so that the two flange parts are always in alignment with one another. This makes it considerably easier to assemble the flange parts.
By contrast, the flange inner wall or the inner flange is expediently configured to be thermally movable. The thermally movable connection of the two inner flange sections may be configured, for example, in a simple form as a tongue-and-groove connection. In this case, an I-ring connection, with an I-shaped compensating or sealing ring inserted into corresponding axial grooves of the inner flange sections, or a piston-ring-like connection of the inner flange, with engagement over (behind) the inner flange sections, is particularly expedient.
Preferably, however, an angle ring connection is provided, which allows movements of the inner flange sections relative to one another in different directions of movement. For this purpose, a sealing and compensating ring of L-shaped cross-section, which can absorb expansions and, at the same time, has a sealing effect, is expediently provided. This compensating ring allows relative movements of the two mutually opposite inner flange sections both in the longitudinal direction of the line and transversely to the longitudinal axis of the latter.
The compensating ring is expediently held on one of the inner flange sections by a threaded ring. For this purpose, when the threaded ring is in the screwed-in state, a radial annular groove for receiving one leg of the compensating ring is configured between the corresponding inner flange section and a shoulder contour of the threaded ring. An axial annular groove of the opposite inner flange section serves for receiving the other leg of the compensating ring. By virtue of these mutually perpendicular expansion joints or expansion grooves, corresponding relative movements in two mutually perpendicular directions are possible. In this case, the compensating ring is held in the grooves so as to execute a sliding movement with little play. This type of connection or sealing by use of an L-ring connection is particularly advantageous in the case of high differential expansions and pronounced relative movements between the inner flange sections in the radial direction.
Alternatively, a U-ring connection, with a U-shaped compensating or sealing ring inserted into corresponding shoulder-like recesses of the inner flange sections, may also be provided. The use of a U-ring connection is particularly suitable in the case of short inner flange sections and when there is a risk of scaling.
The advantages achieved by the invention are, in particular, that, by use of a double-walled flanged connection, with a cooling system being configured between an outer flange and an inner flange in the form of an interspace through which a cooling medium flows, a line of this type can be separated and reconnected many times in a simple way.
The line may therefore be configured for maximum steam states (300 bar/600° C.). Owing to the fact that the interspace has flowing through it a cooling medium, which is preferably supplied and discharged via lead-throughs provided in the flange outer wall, the heat from the flanged connection can be discharged in a simple reliable way. Inadmissibly high thermal and/or mechanical loading on the flange screws is thereby reliably avoided.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an apparatus for the connection of line sections, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
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“Flange Seal With Rubber Washers For An Ultrahigh Vacuum” (Epifanov et al.), Instruments and Experimental Techniques, vol. 18, No. 3, Ju
Becker Ralph
Dallinger Heinz
Kern Holger
Monning Karl-Heinz
Pollak Helmut
Greenberg Laurence A.
Lerner Herbert L.
Nicholson Eric K.
Siemens Aktiengesellschaft
Stemer Werner H.
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