GB1095106A - Expendable immersion thermocouple assembly - Google Patents

Abstract

1,095,106. Thermoelectric devices. LEEDS & NORTHRUP CO. April 5, 1966 [April 6, 1965], No. 15093/66. Heading H1K. An expendable immersion thermocouple assembly, for measuring the temperature of molten metal, is provided with thermallyinsulated lead wires packed adjacent to the assembly so that the wires may be extended in use. The assembly may be dropped into a " basic oxygen " furnace, or may form part of a telescopic lance which is extended before insertion into an " open hearth " furnace. As shown, Fig. 1, the thermocouple wires 11, 12 are mounted in refractory cement 15 and are protected by a refractory tube 14 and a fusible cover 17. The arrangement is mounted in the end of a cardboard tube 18 which is provided with a steel or cast iron weight 28. The thermocouple wires are connected to lead wires 23, 24 which are protected by a thermallyinsulating cover to form a cable 25 which extends through tube 18, to the end of which it is fixed by staples 27. The remainder of the cable is wound round the tube 18, and the ends 23a, 24a of the leads are connected to measuring apparatus. When the assembly is dropped into the furnace, the cable 25 unwinds and provides a spring effect which reduces the impact when the assembly hits the surface of the molten iron. The thermocouple wires are of platinum plus 6% rhodium and platinum plus 30% rhodium and both lead wires are of copper. A known type of temperature recorder for use with platinum/platinum plus 10% rhodium thermocouples may be used by incorporating a compensating circuit, Fig. 2 (not shown). In a modification, Fig. 3 (not shown), the cable is packed inside the cardboard tube (18A) which fits inside a fixed tube (55) from which it may be projected by means of a spring (58) or an explosive. The head of the assembly is provided with a ceramic rod (68) to prevent the thermocouple coming in contact with the bottom of the furnace. The assembly may also be projected by packing the tube with a propellant so that the device forms a rocket. In a second modification, Figs. 4 and 5 (not shown), the thermoelectric assembly is mounted directly in the weight (72) and the cable is coiled and supported by paper strips (18B) or is wound round a cardboard tube which is not projected into the furnace. An extending lance, Figs. 6 to 9 (not shown), comprises a cardboard tube (18C) lying in a pipe (86) and having the thermocouple assembly mounted at one end. The cable (25C) is folded inside the tube (18C) and is terminated by a connector (81) cemented to the end of the cardboard tube (18C) and engaging a connector (85) provided on the end of the pipe (86). The pipe (86) is provided with a slot through which a pointed projection of a handle (92) may be forced into the cardboard tube (18C) so that the tube can be mechanically separated from its connector (81) and moved down the pipe, thus doubling the length of the lance.