Patent GB-862993-A (GB)
Title: Improvements in tubulous vapour generating units
IPC: F22B21/34
Filed: 1959-01-27
Abstract: 862,993. Steam generators. BABCOCK & WILCOX CO. Jan. 27, 1959 [Jan. 27, 1958], No. 2862/59. Class 123(2) A steam generating unit, which may be shop assembled, comprises a rectangular setting 10 having front, rear and side walls 11 ... 14 and a roof 15 which define a rearwardly arranged convection section 16 accommodating a pair of side-by-side water tube bank units 17, 18, and a forwardly located combustion chamber 19 which is common to each tube bank unit 17, 18. Solid fuel, e.g. coal, is fed from a hopper 22 on to a travelling grate stoker 23, overfire air being supplied through a number of jet nozzles 24 arranged in the-furnace front wall 11. A refractory bridge wall 20, at the junction of the combustion chamber 19 and the convection section 16, extends upwardly a short distance and, with the side walls 13, 14 and the roof 15, defines an opening 21 through which the combustion gases pass from the combustion chamber into the convection section 16. The tube bank units 17, 18 comprise respectively laterally located upper steam and water drums 26, 29 disposed above a corresponding water drum 27, 30 and banks of parallel flow circulating tubes 28, 31, all of the drums being of a length approximately equal to the length of the convection chamber 16 except the steam and water drum 26 which is co-extensive with the setting 10. The outermost columns of tubes of the banks 28, 31 line the vertical walls of the convection section 16, the forward-most row of tubes being inclined for- .wardly adjacent their lower ends to cool the bridge wall 20. The rear portion 26A of the main drum 26 communicates with the lower drum 30 of the unit 18 through a column of S-shaped tubes 32 disposed intermediate the banks 28, 31, and at least one steam pipe 33 connects the steam spaces of the drums 26, 29, the drum 26 having a steam outlet 34. The side walls 13, 14 and the end wall 11 of the furnace chamber 19 are lined interiorly and exteriorly With riser and downcomer tubes 40, 41. 45 and 38, 39, 43, respectively, all of the tubes being connected between lower side and end wall headers 36, 37 and 44 and the main drum 26. The headers 36. 37, 44 are interconnected. the rear ends of the headers 36, 37 being connected to the corresponding ends of the water drums 30, 27. The front wall riser tubes 45 may be either bunched at their upper ends for connection to the drum 26, or the tubes laterally of the drum may be connected to a separate upper header leading to the drum 26. The side wall riser tubes 42. having roof extensions 41A which shield the drum from the radiant heat of the furnace, are connected to the same sector of the drum 26 as the side wall riser tubes 40. Laterally aligned baffies 46. 47, extending inwardly from the side walls of the convection section 16, deflect the gas flow through a central opening 48 to a second baffle 49 which causes the combustion gas to diverge outwardly through openings 50, 51 between the edges of the baffle 49 and the corresponding side walls of the furnace to an outlet 25 in the rear wall 12 of the unit. In a modification, which is adapted' for oil and gaseous fuels, the front wall of the furnace chamber and the floor are lined with refractory, the front wall being provided with burner ports for burners.