GB690993A - Improvements in or relating to steam generators - Google Patents

Abstract

690,993. Steam boilers; drums; desuperheating. METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. Aug. 2, 1950 [Aug. 16, 1949], No. 21333/49. Classes 123 (ii) and 123 (iii) A steam-and-water drum 1 for a forced-flow boiler is of vertical cylindrical shape and is provided at its upper end with a steam separator 3 and at its lower end with a desuperheater 19. The separator 3. has tangentiallyarranged inlet pipes 4, 5, connected to the steam-generating tubes of the boiler, a steam outlet 8, and an internal baffle 7, with perforations 6 which, with a further baffle 9, directs any water passing through the pipes 4, 5 downwardly along the inner wall of the drum. Spaced within the drum is a cylindrical shell 11 which extends to near the bottom thereof, terminates at its upper end in a baffle cap 16 having perforations 17, and is apertured at 14 and provided with a circumferential lip 15 to deflect separated water flowing down the drum wall into a space 23 defined by a second shell 27 which is disposed within the shell 11 and forms with the latter an annular space 24 closed at its bottom and surrounding the superheater 19. The lower end of the shell 11 is fitted with an outlet pipe 25 leading to the boiler recirculating pump, not shown, and both shells 11, 27 are perforated at 30, 31 above the level of the upper ends of the desuperheater, the arrangement being such that feedwater supplied to the drum through a pipe 26 must first pass upwardly around the annular space 24 and then through the perforations 30, 31 and said space, being meanwhile preheated, before reaching the outlet 25. The desuperheater 19 is constituted by inverted-U tubes projecting upwardly from the bottom closing plate 12 of the drum, the plate 12 having a cover 20 forming a divided steam chest with inlet and outlet openings 21, 22 for superheated and desuperheated steam respectively.