GB803153A - Improvements in natural circulation steam generators - Google Patents

Abstract

803,153. Water-tube steam boilers; feedwater distributers. BABOOCK & WILCOX, Ltd. Oct. 10, 1956 [Oct. 19, 1955], No. 30879/56. Class 123(2) In a convection circulation steam boiler, for example, that shown in Fig. 1 which illustrates a boiler heated by gases from a copper smelter, the gases entering a steam generating tube lined chamber 13 and flowing successively through generating tube screens 46, 47, a superheater 45, spaced banks 20, 21 of generating tubes and a bank 22 of downcomer tubes to an outlet 19, the tubes of the banks 20...22 connecting a water drum 24 with a steam and water drum 23, the boiler feedwater is supplied to the drum 23 at below saturation temperature and is distributed therewithin so that water vowing from the water space 71 of the drum into the downcomers 22 is free from steam bubbles and the water entering the riser tubes is substantially at saturation temperature, thus ensuring the optimum circulating head. The main feed pipe 60 is divided into two branch pipes 61. 62. The larger pipe 61 is disposed longitudinally at the top of a peripheral steamwater mixture receiving compartment 56, the pipe being perforated at 65 to direct jets of feed-water into the steam-water mixture flowing from the compartment to cyclone separators 67, the main bulk of the feedwater thus being heated to saturation temperature. The smaller pipe 62 is disposed longitudinally in the water space 71 of the drum and is perforated at 72 to direct jets of feedwater towards the downward flow of water from the separators, the flow in the pipe 62 being adjusted to a quantity sufficient to condense all the steam entrapped in this downward flow and so render the water discharging to the downcomers free of steam bubbles.