Patent GB-190708795-A (GB)
Title: Regulating Apparatus for Furnace Draughts.
Inventor: BARKER GEORGE
Filed: 1907-04-16
Granted: 1908-03-05
Abstract: 8795. Barker, G., [Boiler Room Economy Co.]. April 16. Dampers; air supply, regulating.-Means are provided for regulating the position of furnace dampers, or for controlling the supply of air, according to the proportion of carbonic acid contained by the furnace gases. The invention is shown applied to doublefloat gas - analysing apparatus of the kind decribed in Specification No. 5244, A.D. 1907, [Abridgment Class Registering &c.], and to a wellknown form of single-float recording-analyser. Reference is made to Specification No. 27,757, A.D. 1896, which describes similar apparatus. The floats 2, 3 are connected together by flexible pins 11, and rise and fall with a liquid which is pumped into and out of the casing 1. The float 3 enters a chamber 4, into which furnace gas is drawn through the automatically-operated valve 5 by lowering the level of the liquid in the casing. The gas is then pumped into the chamber 6 by raising the liquid, and the carbonic acid is absorbed by a solution of caustic potash. The liquid is again lowered, the floats 2, 3 fall, and contact is broken between the points 14 and the plate 9. This allows the electromagnets 8 to release the spring-controlled carriage 25, and contact is made between pairs of terminals 24 by a bridge 27 carried by the float 2. The position of the float when contact is broken thus determines which, if any, of a series of coils on solenoids 18, 19 shall be energized to operate the damper. In a modified arrangement, the points 14 and the plate 9 are normally separated, and contact between them completes a circuit through the coils of an electro-magnet, which moves the carriage and terminals into contact with the bridge as before. A latch, operated by a cam on the valve 5, may be provided to prevent movement of the floats during the preliminary operations. Coils may be provided on the solenoid to be energized according to the pressure of the steam in the boiler, and these are so arranged that the steam control always predominates. In the arrangement shown in Fig. 18, contact across the terminals operates the switch of a reversible electric motor by which the damper is moved. In this arrangement, the pairs of terminals are preferably replaced by rails 38, 39, one of which is broken at a position corresponding with the level of the float when the normal proportion of carbonic acid is present. Assuming the bridge 27 to be in contact with the upper portion of the rails, circuit is completed between terminals 67, 73 through a wire 68, lamps 69, resistance 70. wire 71, coils of magnet 66, solenoid 59, and wire 72. The switch 62, 63 is operated, and circuit is completed between the terminals 67, 73 through the wire 68, field coils of the motor 40, limiting switch 74 (operated at the extreme position of the damper by an arm), switch contact 63, motor armature, wire 76, contact 62, and wire 72. The motor is thus operated, and the damper 43 is moved. The contact at the rails 38, 39 is only momentary, and a substitute circuit through a wire 77, lever 64, contact 78, electromagnet 66, and solenoid 59 is provided. The motor operates until the point 79 makes contact with the pin 50 when the current through the electro-magnet 66 is short-circuited through the arm 47 and wire 81. The pins 50, 51 are carried on a rotatable disk held fixed, when the solenoid 59 is in circuit, by braking- levers 57, Fig. 17, but free, when no current passes, to be moved by springs into position so that the pins 50, 51 are equidistant from the arm 47. The damper is thus given a step - by - step motion. Pressure control may be provided by a gauge 85 and contacts 86, 87, and in this case the magnet which operates when steam pressure is too low is made stronger than the other, so that the damper opens to increase deficient steam pressure in spite of the energizing of the other magnet due to deficient carbonic acid. The system of control may be used to operate the switch of an air-supply fan motor, or the valve of a steam-air injector. A polarized relay may be used instead of the electromagnets shown in Fig. 18. As applied to a battery of boilers with a single gas-analyser as shown in Fig. 21, the main flue damper 117 is operated according to the steam pressure, while the separate boiler dampers are controlled according to the proportion of carbonic acid. Separate motors may be provided for each damper, as shown fitted to the right-hand boiler, or one motor may operate a number as shown for the other five. The valve arrangements for the second method are shown in Figs. 23 and 24. The gas-conveying pipes 121, which lead samples of the flue gases from the separate furnaces to a common analyser, are brought successively into communication with the intake pipe 123 of the analyser by means of the passage 124 in the rotating valve 125. When circuit is closed at some portion of the working mechanism of the analyser, the magnet 126 is energized and the pawl 128 turns the ratchet-wheel to bring a new pipe into communication with the intake pipe 123. At the same time a brush 154 touches a tongue on a metal band surrounding the valve 125, and a circuit is completed which operates a clutch 135 on the corresponding damper shaft. In the arrangement in which a separate motor is provided for each damper, a similar valve is employed, but three bands 138, 139, 140 with tongues 141, 142, 143 are fitted as shown in Fig. 27. The pairs of brushes 146, 147 are connected to the armature brushes of the different damper motors. and the brushes 144, 145 are connected to the terminals 63, 62, Fig. 18, respectively. The brush 148 is connected to the wire 68, and the brushes 149 are each connected to one terminal of the different motor field magnet?. The parallel dotted lines, Fig. 18, indicate these connexions. When the analyser is situated at some distance from the furnace, means are provided for ejecting from the pipe 121 gas which may be therein, so that a sample fresh from the furnace is used in each test. The arrangement is shown in Fig. 28 applied to a one-float form of analyser The gas from the gas-directing valve 125 passes through the pipe 123 to a valve 155 operated by a solenoid 156 and spring 157. When the solenoid is energized, it turns the valve into the position shown in Fig. 29, so that steam from a pipe 158 passes to the suction nozzle 160, and draws the gas from the tube 123 through the passage 162, discharging it through the pipe 163. The solenoid is preferably in circuit with the electro-magnets 126, 102, the latter of which acts, in this form of apparatus, to move the carriage 25, Fig. 1. Contact is made momentarily at the beginning of each operation by a spring 166 on an arm of the gas valve, and a pin 97 on a pulley 95 operated by a float 93. In applying the invention to a recording gas-analyser, the bridge 27, Fig. 1, is mounted on the recording stylus. and the primary circuit is completed in a manner similar to that shown in Fig. 28.