GB400579A - Improvements in and relating to boiler and the like furnaces - Google Patents

Abstract

400,579. Air supply to furnaces. ARTHUR, J., 99, Cardigan Terrace, Heaton, and LOADES, A., 26, Grace Street, Byker, both in Newcastle-on-Tyne. Feb. 15, 1932, No. 14227/31. [Class 51 (i).] In a steam-generator furnace of the kind in which the ashpit is divided by an horizontal partition H into an upper compartment C through which primary air is supplied to the grate a<2> and a lower passage D traversed by secondary air on its way to the flue beyond the bridge a<3>, the secondary air is heated before delivery to the gases in a refractory arch B disposed behind the bridge a<3> and formed with circumferential passages' b<4>, Fig. 5, with which the radial delivery ports b<5> communicate. In the construction shown in Fig. 1, the supplies of primary and secondary air to the compartments C, D are controlled by a single sliding damper K interconnected with the fire-door T in such a manner that, when the door is opened for firing, the damper is moved to a position in which the primary air inlet is substantially closed while the secondary air inlet is fully open. A three-armed lever, pivoted at r<4>, has one arm R<2> connected to the damper, a second arm R<3> carrying a counterweight r<5>, and a third arm R<1> projecting into the path of a stop F<1> on a shaft J. The latter is so arranged that it is moved longitudinally by the opening and closing of the door T, and is secured at its outer end to the piston of a dashpot E<1> which regulates the speed at which the damper K returns to normal position after the door T is closed. Fig. 10 shows a modification in which the two air supplies are controlled in constant proportions by dampers C<1>, D<1> adapted for automatic operation by a pyrometer or pressure gauge P arranged within the furnace, or alternatively by the opening and closing of the firedoor T. The movable member p<1> of the device P is arranged to contact, on any deviation from the normal temperature or pressure, with one or other of a pair of contacts to start up an electric motor M which rotates in a direction to open or close the dampers C<1>, D<1> as the case may be. The connections between the motor M and the dampers comprise worm gearing m<2>, m<3>, shaft G, rods f<1>, adjustable lost-motion devices F, and dashpots E. The shaft G is connected by a clutch t<2> to the spindle t<1> of the fire-door T, the clutch being operable to cut out the control by the motor M and connect the shaft G directly to the spindle t<1>. A device is provided to enable, when fire-door control is being employed, the shaft G to be disconnected from the worm wheel< >m<3>. The normal positions of the dampers C<1>, D<1> are determined by the angular adjustment of a member d<4>, Fig. 13, which is fitted with compression springs d2, d<3>, connected to the damper rod d<1>.