Patent Number: 044850697
Section: summary

BACKGROUND OF THE INVENTION This invention relates to moisture separator reheaters for nuclear power plants and more particularly to moisture separator reheaters with round tube bundles. In nuclear power plants, moisture separator reheaters are disposed between high and low pressure turbines. The moisture separator reheaters function to remove moisture from the motive steam and reheat it to a superheated condition. The superheated condition of the motive steam entering the low pressure turbine reduces blade erosion within the turbine and improves and heat rate or operating efficiency thereof. With the current emphasis on reduced energy cost and high capital cost of central station power generating plants, every opportunity possible is being pursued to improve the efficiency and load carrying capability of existing nuclear power plants. SUMMARY OF THE INVENTION In general, a moisture separator reheater, when made in accordance with this invention, comprises a generally horizontally disposed cylindrical shell, a head on each end of the shell forming end closures for the moisture separator reheater, a plurality of long tubes disposed in a generally parallel array to form a generally round tube bundle with the top and bottom portions of the tube bundle generally flattened, a tube sheet having a plurality of holes which receive at least one end of the tubes. The ends of the tubes are seal welded in the tube holes. A plurality of tube supports are spaced along the length of the tube bundle and a pair of arcuate plates are disposed on opposite sides of the tube bundle and fastened to the tube supports forming a wrapper subtending the round portion of the tube bundle. A pair of cylindrically shaped plates are disposed longitudinally in the central portion of the shell. The cylindrically shaped plates have generally horizontal upper and lower margins which generally extend the length of the shell. A plurality of upper plate portions extend from the upper margins of the cylindrically shaped plates to the upper portion of the shell and a plurality of lower plates extend from the lower margins of the cylindrically shaped plates to the lower portion of the shell. The upper, lower and cylindrically shaped plates and shell are cooperatively associated in a sealed relationship to form within the shell a central chamber flanked by two side chambers. Openings in the lower plates place the side chambers in fluid communication with the central chamber. Moisture separators are disposed in the fluid path between the central and side chambers. A tongue and groove juncture is disposed between adjacent arcuate and cylindrically shaped plates. The tongue and groove juncture generally extends the length of the plates to provide a seal between the arcuate and cylindrical plates and to allow easy installation and removal of the tube bundle with respect to the central chamber. An inlet is disposed in fluid communication with the side chambers and an outlet is disposed in fluid communication with the upper portion of the central chamber whereby motive steam has its moisture removed and is heated as it passes over the outer side of the tube bundle.