GB802173A - Improvements in tubulous steam boilers - Google Patents

Abstract

802,173. Pulverulent-fuel furnaces. BABCOCK & WILCOX, Ltd. Jan. 25, 1957 [Jan. 27, 1956], No. 2763/56. Class 51 (1). [Also in Group XIII] In a water-tube boiler having a generating tube lined combustion chamber 1, the lower part 13 of which has front and rear walls 3, 5 respectively formed with arches 7, 9 through which low-volatile, pulverized fuel burners 37, 39 of the non-turbulent type are arranged to discharge downwardly, the combustion gases flowing upwardly in an upper radiation section 11 of reduced depth compared with the lower combustion chamber 13 and containing in its upper part widely-spaced platens of a high temperature superheater 121 and then flowing through a lateral pass 55 locating further steam heaters and a downpass 137 in which are disposed economizers 139 to outlet ducting containing an air heater 143, adequate flame cooling in chambers 13, 11 is ensured by providing a partition wall 27 of generating tubes which divides the chambers into equal parts 23, 25. The tubes lining the side, front and rear walls of the chambers 13, 11 and forming the wall 27 are bare except in the zone immediately below the burners and in the flame turning zone where they are covered with refractory material, all the tubes being connected between lower headers such as 41, 51 and an upper steam and water drum 75. The pass 55 is divided into two gas flow passages 102, 104 by a rearward extension 103 of the partition 27, the extension being formed of generating tubes in the part of the pass upstream of a generating-tube screen 57 extending thereacross and of superheater tubes in the part downstream of the screen, the division of gas flow being continued in the down pass 137 by a metallic partition wall. The gas passes 102, 104 locate respectively secondary and primary superheaters 127, 113 and reheater sections 133, 135. The temperatures of reheat and superheat are controlled by differentially firing the burners associated with the combustion chamber sections 23, 25 or by proportioning the gas flow over the reheater and superheater by adjustment of dampers 141 disposed at the downpass outlets. In the latter case, ports are provided in the wall 27 to permit gas flow between the sections 23, 25.