Improvements in or relating to method and apparatus for measuring and controlling the level of the molten glass in tank furnaces

摘要

690,261. Automatic level control systems. UNION DES VERRERIES MECANIQUES BELGES SOC. ANON, and BRICHARD, E. July 16, 1951 [Sept. 7, 1950], No. 16825/51. Class 38 (iv). [Also in Group XVIII] A method of regulating the level 3 in a tank 1 of molten glass comprises directing a constant delivery jet of gas, e.g. cold air, from an outlet in a pipe 6 on to the surface of the glass at a point 5, and utilizing the pressure variations in the air delivery, consequent on changes in the glass level, to operate means for regulating the delivery of glass. A fan 17 delivers air to an adjustable nozzle 11 through the pipe 6, the pressure in which acts on a water-filled manometer 18, 20. A float 21 in the limb 20 is connected to a wire 22 fixed to a pulley 23, the spindle 24 of which carries a needle 26, 27 which alternatively contacts two electric contacts 34, 35, each in a relay circuit 32, 33 respectively. Glass is delivered to the tank by a compound-wound motor 43, the armature 44 of which is in series with a resistance 45 and in parallel with a rheostat 46, the slider 47 of which is controlled by a reversible motor 52, Fig. 8. Energization of one of the relays 32, 33 initiates the two following operations. Firstly, resistances 56, 57 in series with the field coil are short-circuited or brought into circuit respectively to vary the speed of the motor 43, and secondly an electromagnet 55 is appropriately energized to actuate one or other of two double contacts 53, 54 to determine the direction of rotation of the motor 52 and hence the value of the rheostat 46. The time during which the speed of the motor 43 is controlled is made proportional to the deflection of the needle 27 by employing contacts 34, 35 of the shape indicated in Fig. 7. A constantly rotating cam 41 periodically deflects the needle 27 an amount " d," and depending on the extent of the right- or left-hand deflection of the needle 27 due to the pressure variations, so is the time during which it touches the contact 34 or 35 determined. Precautions may be taken to cool the glass at the point 5 to prevent wrinkling, e.g. by water-cooling the nozzle head 11 and shielding the glass at 5 from the tank atmosphere. The manometer may be replaced by a pendulous torroidal pressure gauge, (see Fig. 2, not shown), to permit one arm of the device to communicate with the tank atmosphere to eliminate the effects of pressure variations in the tank.