Patent GB-569958-A (GB)
Title: Safety apparatus for the fuel gas systems of coke oven installations
IPC: C10B21/14
Filed: 1943-09-10
Abstract: 569,958. Reversing apparatus for regenerators. COLVILLES, Ltd., and TODD, D. Sept. 10, 1943, No. 14895. [Class 64 (i)] [Also in Group XXXVII] In the heating system of a coke oven installation with two sets of reversible regenerators and two sets of associated air and gas valves which are operated by a reversing machine so that in one limit position of that machine one set of air and gas valves is fully open and the other fully closed while in the other limit position the first set is closed and the second open, and in an intermediate neutral position both sets are closed, a pressure responsive device subject to the pressure of the gas system sets the reversing machine in operation if the gas pressure is unduly reduced, until the neutral position is reached, to prevent the formation of an explosive mixture by air passing into the gas system. The pressure responsive devices 20A, 20B act as electric switches in the control circuit of an alternating-current motor which drives the reversing machine. In each device 20A, 20B the pointer makes contact with one terminal H at the gas pressure necessary for satisfactory starting, and with another terminal L if the gas pressure falls to a dangerous level. Associated with the reversing machine is a drum controller carrying segmental conducting bars such as 5, 6, 7, 8A, 8B which co-operate with brushes such as 9, 10, 11, 12. The bars 5, 6 are semi-circular, the bar 7 is circular, and the bars 8A, 8B are quadrantal. The drum rotates through 180‹ when the reversing machine moves from one limiting position to the other. Initially the drum and reversing machine are in their neutral positions. Time switches 13A, 13B are alternately opened and closed at predetermined time intervals. When the operator closes the switch 29, the switches 25SA, 25SB operated by the coil 25C are closed. If the gas pressures are set at the required initial pressure the pointers 21 are in contact with the terminals H and the coils 26CA and 26CB are energised, so that their associated pairs of switches 26SA and 26SB are closed. The consequent energising of the coil 23C causes the switch 23S to open and the switch 23SS to close. When one of the time switches, say 13A, is next closed, the circuit through the brush 10, strips 6, 7, brush 11, switch 23SS, brush 12, strip 8A and coil 4C is completed. The switch 4S operated by the coil 4C is thus closed, so energising the coil 2C and closing its associated switches 2S. This starts the motor, which runs until the reversing machine and drum reach the other limiting position. The drum has then rotated through 90‹, and reached the position where the brush 10 leaves the strip 6 and the brush 9 makes contact with the strip 5. Consequently, the solenoid 4C is de-energised, the switch 4S opened, the solenoid 2C de-energised, the switches 2S opened, and the motor, the reversing machine and the drum stopped. The time switch 13A subsequently opens and, after the pre-determined time interval, the other time switch 13B closes and initiates a similar cycle, in which, however, the drum rotates through 180‹ to its other limit position. This process continues so long as the gas pressure is above the danger level. If, however, the pressure in the part of the gas system to which, say, the device 20A is subject becomes dangerously low, the pointer 21 makes contact with the terminal L, the coil 26CA is short-circuited, the pair of switches 26SA is opened, the coil 23C de-energised, the switch 23SS opened, and the switch 23S closed. Thereby the circuit through the brush 11, strip 7, strip 8A, and coil 4C is completed and consequently the motor started. It runs until the reversing machine reaches the neutral position, when the brush 12 reaches a gap between the strips 8A, 8B. The circuit through the coil 4C is then broken and consequently the switches 2S open and the motor stops, with all the valves closed.