GB524052A - Improvements in or relating to water tube boilers with superheaters - Google Patents

Abstract

524,052. Water-tube steam boilers ; steam superheaters. BABCOCK & WILCOX, Ltd. Jan. 20, 1939, No. 2039. Convention date, Jan. 21, 1938. [Classes 123 (ii) and 123 (iii)] In a boiler having tubes connected to upper and lower drums and with a superheater in the path of the heating gases before they enter the passes along or across the boiler tubes, part of the gases are diverted under the control of a damper directly into the passes where they mix with the main stream from the superheater. The superheater 22 of a three-drum boiler having vertical tube banks 18, 20, is shielded from ash particles by slag screens 40, 42, furnace gases being directed by a baffle 62 into a radiant heat absorption chamber 44 before passage through screen 42 and over the superheater. Horizontal baffles 82, 74, 86 with a baffle 76 in front of the upper part of tube bank 20 define successive transverse passes 72, 84, 88, a pass 60 under baffle 82 having an entry formed by the spacing of the lower portions of the tubes of baffle 62, and constituting a superheater byepass controlled by a damper 92. In a modification the gases contact with a horizontal loop superheater in 'an up-pass immediately above a slag screen the lower loops of the superheater elements being wider and staggered to provide a screen. The tube bank baffles lie along the tubes and the entry into the first pass includes the top portions only of the front tubes the rest lying in the superheater byepass which has a regulated outlet near the lower drum. A second byepass formed by a lateral passage between the front water tubes and the superheater may be more or less closed by the extension of a baffle to adjust superheat to meet different operating conditions. The .superheater of another embodiment has vertical tube loops.