GB889608A - Improvement in a steam generating plant - Google Patents

Abstract

889,608. Water-tube steam boilers; partitions in water drums. NORDLUND, K. F. Feb. 23, 1960 [Feb. 24, 1959], No. 6386/60. Class 123(2) A large steam generating plant comprises two groups of steam generating pipes 8, 9 which are heated by downwardly flowing hot gases and which are connected to the steam and water spaces of a primary separator 2 by primary down pipes 6, 7 and primary ascending steam pipes 9, 11 the steam and water spaces of the primary separator 2 being connected to the corresponding spaces in a secondary steam separator 1 by means of steam ascending and water descending pipes 13, 12 respectively. The secondary descending pipe 12 has a bend located below the primary separator 2 to serve as a water trap the secondary ascending pipe 13 also being provided with a return bend above the secondary steam separator. A second group of steam generating pipes 16, associated with a primary separator 3 and connected in a similar manner to the secondary steam separator 1, may form a different part of a large single steam generator or, it may belong to a separate furnace in the same plant. Each secondary circulation system 1, 12, 2, 13, 1 or 1, 17, 3, 18, 1 is dimensioned for a certain maximum steam flow through the secondary steam ascending pipe 13 or 18 and a corresponding water flow through the secondary descending pipe 12 or 17 in kg./sec. which is a predetermined multiple of, e.g. two or three times, the steam flow. In this manner the water level in each primary steam separator 2 or 3 is automatically regulated within fine limits. The circulating force in each system, which depends upon the difference between the effective head of water in the descending pipe 12 or 17 and the pressure of steam and water in the ascending pipe 13, 18, is influenced by the rapid fluctuations in the amount of water sucked into the ascending pipe 13 or 18 so that the oscillations of water level are of such a high frequency to maintain variations of level above the average very small. A primary steam separator, Fig. 2, comprises a cylindrical container 19 having centrally located openings for primary steam ascending pipes 29 and primary descending tubes 20, 21 leading from the bottom of the separator, secondary descending tubes 27, 28 being connected to the end walls of the container. Secondary steam ascending tubes 23, 24 extend laterally and then upwardly from spaces 25, 26 formed above the container 19. In a modification, Fig. 4, primary steam ascending, and water descending, pipes 31, 32 communicating respectively with the upper and lower portions of the left side of the container are separated by a baffle 33 a secondary steam ascending pipe 35 being led from the upper end at the other end of the drum above a separating plate 34. Water is delivered by the secondary descending pipe 36. In a further modification a secondary ascending pipe is located at one end of the container above a separating plate below which are arranged the primary and secondary descending tubes, the primary steam ascending tubes being connected to the other end of the container. Another arrangement is described in which a primary separator is adapted to be arranged in a position slightly inclined from the horizontal.