Patent Number: 044850697
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in detail, there is shown a moisture separator reheater 1 comprising a generally horizontal elongated cylindrical shell portion 3 having a head 5 disposed on each end thereof (only one is shown) which form end closures for the shell 3. A motive steam inlet nozzle (not shown) is in fluid communication with a pair of distribution manifolds 7 which are disposed horizontally within the shell 3. A plurality of distribution slots 8 are disposed along the length of the distribution manifold 7 to distribute motive steam evenly throughout the shell 3. A pair of cylindrically shaped plates 9 are disposed longitudinally in the central portion of the shell 3. The plates 9 have generally horizontally disposed parallel upper and lower margins. A plurality of generally flat upper plates 11 and 13 extend from the upper margins of the cylindrical plates 9 to the upper portion of the shell 3. A plurality of generally flat lower plates 15 extend from the lower margins of the cylindrical plates 9 to the lower portion of the shell. The plates 9, 11, 13 and 15 cooperate with the shell in a sealed relationship to form within the shell a central chamber 17 flanked by two side chambers 19 and 21. The lower plates 15 have openings 23, placing the side chambers 19 and 21 in fluid communication with the central chamber 17. Disposed adjacent the openings 23 is a chevron-shaped moisture separator or other moisture separating means 25. The lower plates 15 may also end at the separator 25. A motive fluid outlet nozzle 27 is disposed in the upper portion of the shell 3 in fluid communication with the central chamber 17. A plurality of long tubes 31 are disposed on a triangular pitch in a generally parallel array to form a generally round tube bundle 33 with flat top and bottom portions. At least one end of the tubes 31 extend through holes 35 in a tubesheet 37. The ends of the tubes are preferably seal welded to the tubesheet 37. In the preferred embodiment, U-shaped tubes are utilized, however, it is understood that straight tubes and a floating head could be used. A hemispherical head 39 is attached to the tubesheet 37 by welding or other means and has a dividing plate 41 disposed therein to form two chambers 43 and 45 within the head 39. The chamber 43 has a heating steam inlet nozzle 47 in fluid communication therewith and the chamber 45 has a drain nozzle 49 in fluid communication therewith. A manifold 51 is disposed in the chamber 43 and is in fluid communication with a plurality of tubes 31 having smaller radius bends. Also in fluid communication with the manifold 51 are two intersecting holes 53 drilled at right angles in the tubesheet. The holes 53 form a drain for draining fluid from the manifold 51. The manifold 51 is held in a sealed relationship with the tubesheet by studs 55 which fasten to holes in the tubesheet. A plurality of tube supports 57 preferably formed from plates are spaced longitudinally along the length of the tube bundle 33, normal to the tubes 31 to maintain the spacing between the tubes 31. Disposed along each side of the tube bundle 33 and fastened to the tube support plates 57 by welding or other means are a pair of arcuate plates 59, which are generally disposed along the length of the tube bundle 33 adjacent the generally round portion thereof. The arcuate plates 59 form a wrapper which subtends only the generally round sides of the tube bundle 33 and add rigidity to the tube bundle and prevent it from damage as it is installed and removed from the shell 3. Tongue and groove or other sliding sealed junctures 61 extend generally the length of the tube bundle 33 and are disposed between the arcuate plates 59 and the cylindrically shaped plates 9. The tongue and groove junctures 61 are formed from three flat bars 62, 63 and 64 slidably disposed adjacent each other. The central bar 63 being attached to one of the pairs of plates 59 and the other two bars 62 and 64 being attached to the other pairs of plates 9 to form a tongue and groove juncture which allows the tube bundle to slide in and out of the moisture separator reheater and form a seal between the wrapper plate 59 and the cylindrically shaped plates 9. The moisture separator reheater hereinbefore described advantageously provides a generally round tube bundle 33, which replaces square or rectangular tube bundle arrangements and improves the heat rate of the moisture separator reheater by about 20 to 50 BTU's per kilowatt hour. The arcuate plates 59 form a wrapper significantly improving the structural rigidity of the tube bundle 33 to enhance bundle alignment within the moisture separator reheater. The tongue and groove juncture 61 between the wrapper 59 and the cylindrically shaped plates 9 in the central chamber 17 facilitate rapid removal and replacement of the round tube bundle 33 and provide a seal which is not affected by surges in pressure of the motive fluid.