GB760502A - Improvements in or relating to vapour generating and superheating units - Google Patents

Abstract

760,502. Water-tube steam boilers; superheaters. BABCOCK & WILCOX, Ltd. Feb. 17, 1955 [Feb. 17, 1954], No. 4653/54. Addition to 714,050. Classes 123(2) and 123(3) The water-tube steam boiler described in the parent Specification is modified in that the superheater headers are disposed externally of the superheater pass and are spaced apart sufficiently for the superheater tubes to be removed or inserted between them and in that the tubes of the superheater bank are so disposed as to provide an access space either beside or within the bank from which the tubes may be cleaned and the-baffle separating the two passes repaired. The boiler includes a tube-lined combustion chamber 19 fired by oil burners 49, the combustion gases passing laterally through a screen 58 of steam generating tubes into parallel passes 140, 141, separated by a tubulous baffle 59, the gas flow through each pass being controlled by dampers such as 160 at the respective outlets therefrom to regulate the superheat temperature. The passes locate vertical banks 61, 75, 77 of steam generating tubes arranged in staggered relation so that the baffle wall 59 is accessible for repair from one side or the other from spaces 87, 89, or 107. The superheater 105 is disposed in space 107 between screen 58 and tube bank 61. It comprises vertical headers 109, 111 disposed outwardly of the side wall 99 of the unit and a large number of horizontal sinuous tubes 113 joining the two headers, each tube consisting of four limbs 113a ... 113d joined by return bends 114...116, the tubes being arranged in nested groups of three. Each tube group is supported by fingers 120, 123, 125, 127 projecting from large diameter water tubes 121, 124, 126, 128 respectively, the fingers being placed, see Fig. 5, so that each tube has a continuous downward inclination from one header to the other to allow it to be drained. The end portions of tubes 113 are bent outwardly to connect the headers 111, 109, a removable panel 132 closing the space between the headers, so that any tube group can be renewed by first cutting the tube ends and pulling the individual tubes out through the space and inserting the new tubes in the same manner. Access to the cleaning and maintenance space 107 between the limbs 113b, 113c of the superheater tubes is provided by a passage disposed underneath the superheater. In modifications, an equivalent space is arranged beside the superheater bank or between tube limbs corresponding to limbs 113b, 113c, which in that case are connected to an intermediate header disposed in the same plane as headers 109, 111.