Patent Application
20090092218
This application claims the priority, under 35 U.S.C. ยง119, of German application DE 10 2007 048 478.1, filed Oct. 9, 2007; the prior application is herewith incorporated by reference in its entirety.
The present invention relates to a steam dryer for a reactor pressure vessel, in particular a steam dryer, through which steam flows vertically, for a nuclear reactor, containing a plurality of water tanks for removing water which has been separated from the steam, which water tanks are arranged below dryer elements through which the steam flows.
The reactor pressure vessel of a modern light water reactor is a cylindrical steel vessel having a semi-spherical bottom and cover, which is connected to pipelines for a coolant. The upper cover can be lifted off in order to replace fuel assemblies and to carry out maintenance work. The cover is connected to the pressure vessel bottom part by numerous pre-tensioned threaded bolts and nuts. The reactor pressure vessel contains in particular a reactor core with urananium-containing fuel assemblies and the structures which are referred to as core components which fix the fuel assemblies at their intended location, such as the upper and lower core grid, the fuel assembly tanks, etc.
In a boiling water reactor, the reactor pressure vessel additionally contains a water separator or a steam dryer which separates off water droplets from the generated steam and retains them in the reactor pressure vessel. The water droplets contained in the steam could otherwise damage the turbine. Known water separators or steam dryers have water tanks which collect and discharge the water separated off from the steam. Since these water tanks are disposed upstream of the flow of steam to be dried, they exert a certain resistance counter to the flow and are in part responsible for the formation of eddies and flow disturbances. If more output is required from the steam dryer, this can result in difficulties.
It is accordingly an object of the invention to provide a a steam dryer for a reactor pressure vessel which overcomes the above-mentioned disadvantages of the prior art devices of this general type, which is suitable to a certain extent for output increases with increased steam throughput.
The object is achieved according to the invention by way of a novel steam dryer. The steam dryer through which steam flows vertically has a plurality of water tanks for removing water which has been separated from the steam, which water tanks are arranged below dryer elements through which the steam flows. The invention provides that the water tanks have in each case in the flow direction a cross section which is favorable in terms of flow. The water tanks can have, for example, in each case in the flow direction a rounded cross section. Alternatively, they can have a wedge-shaped, a drop-shaped, an oval or other cross section which is favorable in terms of flow. Avoiding a constriction in the flow can achieve an increased steam throughput with reduced spacings between water tanks. The same basic area can accommodate more dryer elements, and therefore an improved action of the dryer can be achieved. Additionally, avoiding edge eddies in the inlet flow can reduce the excitation of vibrations in the flow.
Another embodiment of the invention provides for the water tanks to have in each case largely the same spacings between one another with largely constant aperture cross sections for the steam to be dried. The water tanks preferably have in each case passages, which are favorable in terms of flow, to the dryer elements which are arranged downstream. Additionally, it can be advantageous if the water tanks are in each case connected to discharge lines which likewise have in each case one cross section which is favorable in terms of flow.
The inlets which are favorable in terms of flow can be produced without a significant increase in manufacturing complexity with respect to the cross sections and geometries used to date, with adequate cross sections for the discharged water also being retained.
Considerable output increases in steam dryers can be achieved with the aid of the embodiments according to the invention without this resulting in further problems such as overload effects. The embodiment, which is favorable in terms of flow, of the components which are situated traversly with respect to the flow prevents or reduces the formation of eddies. The steam-containing medium can flow past the place of disturbance without being impeded and without any noteworthy constriction, with the cross-sectional area of the water tanks being completely retained. The dryer packets can thus be pushed together more closely or have a greater structural height. In this manner it is possible overall to accommodate a larger dryer area in the reactor pressure vessel without this being accompanied by any other negative effects on the function.
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 a steam dryer for a reactor pressure vessel, 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.
Referring now to the figures of the drawing in detail and first, particularly, to
The schematic representation of
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2007 048 478.1 | Oct 2007 | DE | national |
