新熱電對に依る熔鋼温度の測定(第2報)

Abstract

In the steel making practice, it is very difficult to know the true temperature of molten steel in the furnace. As the steel is covered with molten slag, it is difficult to measure the temperature with the optical method, and also the temperature is too high to be measured with the Pt-Ft-Rh thermo-couple.The author succeeded to measure accurately and easily the temperature of molten steel in the furnace by using the Tungsten-Carbon thermo-couple with a special device.The principle of construction of his measuring device is as follows:1) Tungsten wire, one end of which being made flat, is inserted in a carbon tube (one member constituting the couple), and that flat end is in contact with one end of the tube, a spring holding the contact. The end makes a hot junction.2) The hot junction is covered with a carbon cap. This carbon cap is dipped directly into molten steel. By making use of the carbon cap in place of ordinary refractory covers, the temperature can be quickly and accurately measured, as the time lag of heat conduction is very small.3) The part which is in contact with molten slag have double protection tubes which consist of a carbon tube and a tube of refractory material. The part which is rot in contact with molten metal and slag has a protection tube of cast iron covered with asbestos paper against gas flame.4) In this method, it is unnecessary to use inert gases (H2 or N2) to prevent oxydation of the couple. The device is not heavy, so that a man can easily carry it.The author measured the temperature of molten steel in Siemens furnaces, electric arc furnaces and high-frequency electric furnaces with the new devices, and have found various interesting facts as the results