Patent GB-190225547-A (GB)
Title: Improvements in or Pertaining to Furnaces.
Inventor: KOWITZKE HERMANN
Filed: 1902-11-20
Granted: 1903-10-22
Abstract: 25,547. Kowitzke, H. Nov. 20. Steam - generator &c. furnaces; smoke - consuming; dampers; firebridges. - Relates to automatic arrangements for operating the flue damper and for regulating the admission of an additional supply of air for consuming smoke when the fire-door is opened for stoking ; also to the construction of the firebridge. Figs. 1 and 2 show the application to the furnace of a steam boiler. The firebridge 22 is cast hollow with a sloping face, and is provided a the bottom with airinlet apertures controlled by valves 24, and at the top, which is circular, with air-outlet apertures 23 leading into the furnace. The valves 24 are connected by levers 45 with a rod 25, which is actuated automatically by an arm 26 on a shaft 27 ; a handle is provided for actuating the rod by hand, if necessary. The shaft 27 also carries an arm 29, having a series of holes from any one of which a weight 28 is suspended. To the arm 29 is secured a chain 30, which passes upwards and is wound on the barrel 31 of a clockwork mechanism A, Fig. 3, supported on a wall bracket 50. Another chain 300 is wound in the opposite direction on the barrel 31, and its free end is secured to an arm 33 on a shaft 32 enclosed by a casing 59. A bent lever f, carrying a weight f<1>, is mounted on the outer end of the shaft 32. The weight 28 is arranged to exert a greater pull on the barrel 31 than the weighted lever f in order to set the clock work in motion. On the fire-door 20, Fig. 2, at a certain distance from its hinge, is secured a vertical rod 55, to which are jointed two horizontal rods a, 2. The lower rod a is adapted to slide in a sleeve b mounted on the lower arm of a bell-crank lever 34 keyed on a shaft 60. A stud or pin on the other arm of the bell crank engages a slot in a plate 36, Fig. 3, inserted in the chain 30. Normally, the valves 24 are in the closed position, and the clockwork A is run down ; in addition, the sleeve b rests against a tappet b<1> on the rod a. On opening the fire-door for stoking, the tappet b<1> pushes the sleeve b to the right, thereby causing the bell crank 34 to lift the weight 28 ; the weighted lever f then rotates the barrel 31, and winds up the slack in the chain 30. At the same time, the valves 24 are opened to admit air to the furnace through the firebridge. On again closing the fire-door, the weight 28 descends slowly and closes the valves 24 gradually, thus diminishing the quantity of air admitted. The time occupied in closing the valves 24 may be regulated by varying the length of the chain 30 to be wound on the barrel 31. For this purpose, there is fixed to the casing 59 a plate 61 having a series of holes to receive a pin for limiting the downward movement of the weighted lever f, when the weight 28 is raised by the bell crank. The flue damper, not shown, is partially counterbalanced and is connected with a chain 37, which is led to the front of the boiler and carries at its end a weight 40. The chain may be passed over a large chain-wheel 38, Fig. 3, or a small chain-wheel on the same shaft, and also over a roller 39. The descent of the damper is regulated by a second clockwork B mounted on the same plate as A and provided with a fly 54. Motion is imparted to the clockwork from the shaft 41 of the wheels 38, 38<1> by a clutch m, which may be disengaged by a lever o. This lever can be actuated either by hand or by the fire-door. In the latter case, the rod a is fitted with an adjustable tappet o' and the shaft 60 with a two-armed lever o<2>, Fig. 3, which is connected by a rod o' with the lever o. On opening the fire-door, the tappet o<3> strikes the lower arm of the lever o<2>, and thus causes the lever o to disengage the clutch m and release the damper, which then drops. On closing the fire-door, the damper can be raised by hand to increase the draught, by pulling down the weight 40, preferably after the clutch m has been disengaged. The rate at which the damper descends can be varied by placing the chain 37 over the large wheel 38 or over the small wheel, or by increasing or decreasing the weight 40. In order to hold the damper in the raised position until the valves 24 are closed, the fly 54 is engaged by the upper bent arm p of a movable rod p<1>. When the clockwork A is about to run down, a projection p<2> on the arm 33 strikes the end of the rod p<1> and raises it, thereby releasing the fly. If, however, smoke continues to be formed after the valves 24 are closed, the damper must still be maintained in its raised position for a time determined by the nature of the fuel. For this purpose, the fly 54, after it has been released by the rod p<1>, is still prevented from rotating by the upper bent arm of a second movable rod 16, operated by a third clockwork C, Figs. 3 and 4, which is similar in construction to A and provided with a fly 55 and barrel 4. On this barrel are wound in opposite directions two chains carrying weights 7, 8, which are guided up and down by rods 9, 10. The weight 7 is made heavier than the weight 8 in order to set the clockwork C in motion. The horizontal rod 2, referred to above, is connected with the upper arm of a bell-crank lever 3, the other arm of which carries at the end a long pin 11 and near the hub a short pin 17. The long pin 11 extends beneath the weight 7 and serves to raise it. When the fire-door is opened, the bell crank 3 raises the weight 7, and at the same time the pin 17 operates the lever o so as to disengage the clutch m and allow the damper to drop. On again closing the fire-door, the pin 11 releases the weight 7, which then descends and sets the clockwork C in motion. When this clockwork is about to run down, the weight 8, in rising, lifts the rod 16, thereby releasing the fly 54 and allowing the clockwork B to run down gradually. The time occupied by the clockwork C in running down can be regulated by a forked stop which extends on opposite sides of the guide-rod 10 and limits the downward movement of the weight 8. This stop passes through a slot in graduated plate 68, and is provided on the outside with a knob 13. Notches are formed in the sides of the slot to receive an enlarged part on the stop and hold it in any position to which it is adjusted. In addition, a spring 71 is provided for keeping the enlarged part in the notches. When using smokeless fuel, the valves 24 and clockwork A can be dispensed with.