GB311019A - Burner for coal dust firing - Google Patents

Abstract

311,019. B³ttner-Werke Akt.-Ges. and Zikesch, H. Feb. 13, 1928. Pulverulent - fuel burners. - In a coal dust burner, a mixture of fuel and air is admitted at the apex of a gradually diverging or stepped chamber and additional air is admitted tangentially to the chamber at a number of points at different distances along the axis of the burner so that the mixture is set in rotation and the smaller fuel particles tend to form a core in the whirling mixture, surrounded by the heavier fuel particles and an enveloping mantle of air. Fig. 1 shows a burner having a bell-shaped combustion chamber at the apex of which coal dust and air are supplied through a pipe 2 containing a helical blade 3. Secondary air is introduced tangentially from a casing 4 surrounding the combustion chamber through tangential openings 11 - - 14. The mixture is ignited by an oil or other primary burner 15 passing through the conduit 2. The oil burner 15 is preferably of sufficient heating power to maintain the operation of the burner during temporary interruption of the coal dust supply. Fig. 5 shows another burner construction in which the combustion chamber is stepped so as to allow three expansions of the fuel mixture introduced through the conduit 12 to take place. The priming burners 21, 22 are preferably arranged obliquely or tangentially so as to assist in whirling the burning mixture. Figs. 8 and 9 show a further burner construction in which three priming burners 35, 36, 37 are provided while two coal dust supply conduits 27, 28 and two compressed air feeders 29, 30 are arranged tangentially in the side wall of the chamber. Additional air is supplied through openings 54, 55 in the stepped portion of the chamber. The fuel and air openings are preferably of slit form so that the fuel and air currents are discharged in spiral bands which wind on each other. The Specification states that by the use of the burner the fuel mixture may be supplied at a velocity of over 20 metres per second, a pressure of over 300 m.m. of mercury and at a temperature from 100‹ to 150‹ C. while the secondary air may be supplied at a pressure of over 20 of mercury and at temperatures up to 450‹ C.