| 摘要 |
In a steam generator, there is provided an annular foraminous or perforated flow distribution plate (100) which may be in the form of a single-piece annulus fixedly secured to the lower end of the heat exchange tube wrapper (146) for installation within new steam generator facilities, or alternatively, may comprise a plurality of arcuately-shaped segments (210) secured together by suitable bolt fasteners (226) for installation within existing steam generator facilities. The plate (100) is adapted to be wedgingly interposed between the lower end of the tube wrapper (146) and the upper surface (204) of the heat exchange tube bundle tubesheet (122), and the plate (100) has the configuration of a conical frustum for stability. The foraminous plate (100) serves to impart uniform, non-turbulent, flow conditions to the infeed water (206) flowing downwardly through the downcomer region (148) of the generator, defined between the generator outer shell (116) and the tube wrapper (146), and passing through the transition region (216) of the generator for entrance into the tube bundle section (208) of the generator. In addition, the predetermined size of the apertures (212) defined within the plate (100) prevents the entrance of foreign particles into the tube bundle section (208) of the generator having, for example, a diametrical size greater than the predetermined size of the plate apertures (212). The plate (100) is fabricated from INCONEL 60 nickel-chromium alloy for good service life characteristics.
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