Light guide for transmitting thermal radiation from melt to pyrometer and method of measuring temperature of molten metal in metallurgical vessel with the aid of said light guide

摘要

The light guide and the method of measuring temperature with the aid of said light guide relate to optical pyrometry of melts.P PA light guide 1 is made from a light-permeable refractory corrosion- resistant material such as leucosapphire, for example, and according to the invention comprises 2 portions: a narrow portion 2 in the form of a rod, and a large portion 3 with a flat end 3a being an operating end of the light guide 1. The large portion 3 of the light guide 1 represents with respect to the narrow portion 2 an optical cavity producing radiation of the operating end 3a substantially in the form of a radiation of an absolutely black body. The ratio of the cross-section area of the narrow portion 2 at the place where it adjoins the large portion 3 does not exceed 0.5.PPAccording to the method the light guide 1 is mounted in a lining 6 so that the large portion 3 is exposed to a melt 5 and the narrow portion 2 extends to a pyrometer 7 so that the geometrical axis of the light guide 1 passes through the point of the inner surface of the lining 6, located in a zone l of the maximum circulation of the melt 5. Said point is located with respect to a residual level 5a of the melt 5 at a depth h not less than the sum of a thickness t of the lining 6 at said level and a value equal to the half maximum transverse size d of the large portion 3 of the light guide 1. With the aid of the pyrometer 7 the temperature of the melt 5 is determined by measuring characteristics of the thermal radiation caused by the melt 5 in the area directly adjacent to said point on the inner surface of the lining 6 and transmitted to said pyrometer through the light guide 1.PPThe light guide and the method may substantially be employed in metallurgy and foundry for measuring temperatures of molten ferrous and non-ferrous metals.