GB657799A - Improvements relating to steam boilers of the water tube type - Google Patents

Abstract

657,799. Water-tube steam boilers ; feedwater supply systems. PEARCE, A. P. Feb. 25, 1949, No. 5213. [Class 123(ii)] In a steam boiler comprising an upper steam-and water drum 4, Fig. 1, and a lower water drum 3 connected by radiantly-heated tubes 2 lining the furnace chamber 1 and tube banks 2a, 18, 18 located in convection passages 13, 14, 15 defined by baffles 9, 10, 11, the banks 2, 2a define one circulatory circuit and the two banks 18 a second separate circuit supplied with water from the first. The drums 3 is divided into two compartments 3a, 3b by a baffle 5 and the water space of the drum 4 is also divided into compartments 4a, 4b by a baffle or weir 6, the compartments 3a, 4b being connected by downcomers 17; moreover the drum 4 is provided, above the water level, with a trough 22 having a water discharge pipe 22a leading to the compartment 4b in which may be located a tubular feed heater 20. Supplied feedwater, after passage through the heater 20, enters the compartment 4a and circulates through the tubes 17, 2, 2a to the trough partment 4b and trough 22 respectively by comparment 4b and the tubes 19. The compartments 3a, 3b are provided with blow-down fittings 23, 24. Fig. 6 shows a modified boiler with radiant tubes 2 extending between headers 3a, 31 and two rows of convection tubes 18 between headers 3b, 33. The headers 3a, 31 are connected to the compartment 4a and to a trough 22 in the latter respectively by a downcomer 17 and risers 32, the trough 22 having outlets 22a leading to the compartment 4b, and the headers 3b, 33 to the compartment 4b and trough22 respectively by pipes 18a, 35. The tubes 2 of this construction may be replaced by tubes which line the furnace chamber 1.