Patent GB-1163531-A (GB)
Title: Improvements relating to a method of melting and supplying glass along a Feeder Duct
Inventor: WATERWORTH THOMAS HUGALL
IPC: G05D23/20
Filed: 1965-07-01
Abstract: 1,163,531. Glass melting furnaces. ELEMELT Ltd. 3 Oct., 1966 [1 July, 1965 (2)], Nos. 27983/65 and 27984/65. Heading F4B. [Also in Divisions G3 and H5] A feeder duct 11 for conveying molten glass is comprised of two zones 35, 41 independently supplied with heat, from burners 40, 40a or resistance heaters controlled manually or automatically by thermo-couples or radiation pyrometers TC3, TC5 and from A.C. supply circuits, (only the circuit for zone 35 being shown) through electrodes 37, 38 and 38, 42 controlled manually or automatically by thermocouples &c. TC4, TC6. Cooling nozzles 39, 39a are provided. Mains current is supplied to zone 35 through a transformer T 1  where primary voltage is adjusted in discrete steps by tap-changing autotransformer T 3 . The tap adjusting slider of transformer T 3  is operated by a motor M having stator terminals t 5 , t 6 , t 7 , the last being connected to the neutral side of the supply at t 12 . Terminals t 5 , t 6  are alternatively energized when the voltage applied to transformer T 1  is to be raised or lowered. For automatic operation, switch S2 is set to close contacts c 2 , a 2 , and d 2 , e 2  and g 2 , i 2  so that current flows from live terminal t 13  through c 2 , a 2  and d 2 , e 2 , through normally closed contacts d 4 , e 4  and c 4 , b 4  of an overriding current sensitive control means OCM, through g 2 , i 2 , through a rate control device RCM, to a contact b 6  of a temperature sensitive control means TCM. When contact b 6  is open, the pointer CP is within a pre-set range on a scale CS as determined by thermocouple TC4. Contacts b 6 , c 6  and b 6 , a 6  close respectively when the molten glass temperature is too low or too high, and respectively energize terminals t 9 , t 10  to raise or lower the voltage through terminals t 5 , t 6 . Device TCM has knob(s) k for adjusting the set range. When contacts b 4 , c 4  and d 4 , e 4  are closed, the device OCM is inoperative and the current is within a pre-set adjustable range. If the current, fed from current transformer T 5 , exceeds or is lower than this range, contacts e 4 , f 4  and a 4 , b 4 , respectively close to energize terminals t 10  and t 9  to reduce. or raise the voltage until the current resets to within the range. When device OCM is operative, terminal t 13  is disconnected from device TCM. The device RCM comprises a motor Ma for cyclically opening and closing contacts a 5 , b 5  for adjustable periods so that the slider of transformer T 3  moves in steps. For manual operation, switch S 2  is set to close contacts b 2 , c 2  and d 2 , f 2  and g 2 , h 2  and terminal t 13  is permanently connected to a terminal t 8  and transformer T 3  is operated by push-button switches S1A or S1B to raise or lower the voltage through terminals t 5 , t 6 . Alternatively, a manual selector switch S 3  has contacts a 3 , b 3  and a 3 , c 3  which operate the transformer T 3  through respective terminals t 9 , t 10 . Lamps l 1 and l 2  indicate respectively when power is applied from transformers T 3  and T 1  and when switch S 2  is set for manual or automatic control. The control means applied to the top and bottom of zone 35 provide a coarse control, while those applied to zone 41 provide a fine control. Transformers T 1  and T 2  can be replaced by one transformer with two tapped secondary windings, and transformer T 3  is controlled by a single motor by and controller C.