Patent GB-554247-A (GB)
Title: Improvements in blast furnaces
IPC: C21B7/18
Filed: 1942-01-05
Abstract: 554,247. Control of several motors. FREYN ENGINEERING CO. Jan. 5, 1942, No. 143. Convention date, Jan. 7, 1941. [Class 38 (iii)] [Also in Group XII] In a blast furnace fitted with a distributary hopper discharging on to a large bell operated after a prescribed number of operations of the hopper the rotation of the hopper is effected by a motive instrumentality under the control of means which is responsive to each dump or multiple of dumps of the large bell and which causes a change in the angle of rotation of the hopper to occur before any of the charges constituting the group of charges succeeding such dump or multiple of dumps is delivered into the large bell. The parts are operated electrically. Each angle programme drum 24 is moved one step by a pilot motor 26 over contacts 29 or 30. The drum 24 by bridging the odd contacts 31 ... 39 determines the extent of rotation of the hopper motor 20 for each succeeding strip load. As each strip load is dumped switches LS or RS close and a coil SR closes contacts SR'. If the drum 24 is in the position 1 the contacts SR' are ineffective to cause the rotation of the hopper motor 20. If the drum is in any of the positions 2 to 6 the coil F is energized over certain of the odd contacts 31 to 39 in series with even contacts 32 to 40 on a drum 25. Energization of the coil F closes contacts F' and starts the motor 20. Contacts 25, bridged by a hopper switch 22, ensure that the motor turns the hopper an integral multiple of 60 degrees, and contacts 46 are closed once in each 60 degrees of turn to energize momentarily a coil DP. This coil causes the pilot motor 27 to move the distributer programme drum 25 one step. When the drum 25 has advanced to the same position as the drum 24, the circuit through the contacts 31 to 39 and 32 to 40 is broken and the motor 20 is stopped. The small bell is now opened and closes contacts SBT which set up a " homing circuit " for a motor 27 over contacts 44 bridged by the drum 25, so that the drum is returned to position 1 ready to determine again the extent of rotation of hopper motor 20 after the next strip load is dumped. In a modification, Fig. 4 (not shown), the angle programme drum is mechanically ratched one step each time the large bell is opened and the distributer programme drum is replaced by a chain of latched counting relays sequentially operated one during each revolution of the hopper switch 55 until the extent of revolution of the hopper corresponds to the setting of the angle programme switch. When the small bell is opened this chain of relays is unlatched ready for a fresh count. A time delay DT prevents starting of the hopper motor until an interval after a skip has made its complete travel and the skip cannot be restarted until the hopper motor has stopped. In another modification, Fig. 5 (not shown), the hopper switch is replaced by a time delay relay NT, the delay of which is determined by a discharge tube and a condenser charged through one of a set of resistances R<SP>1</SP> . . . R<SP>5</SP>. The relevant resistance is selected by the angle programme drum and the magnitude of the delay determines the duration of the run of the hopper motor and thus the angle through which the hopper turned. In a further modification, Fig. 6 (not shown), means are provided to allow the strip to be restarted before the hopper motor has stopped. The earliest moment of starting is made dependent upon the angle through which the hopper motor has to rotate by associating extra contacts on the counting relays of Fig. 4 with extra contacts on the angle programme switch. U.S.A. Specifications 1,801,502, 1,888,501 and 1,937,951 are referred to.