Thermal measuring and testing – Temperature measurement – In spaced noncontact relationship to specimen
Patent
1982-04-19
1984-08-28
Yasich, Daniel M.
Thermal measuring and testing
Temperature measurement
In spaced noncontact relationship to specimen
350 9624, 356 44, 374139, G01K 112, G01K 508
Patent
active
044687710
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to measurement technology and, in particular, to optical pyrometry, and is specifically concerned with a light guide unit mounted in the lining of a metallurgical vessel and designed for transmitting thermal radiation from a melt to a pyrometer.
BACKGROUND OF THE INVENTION
Along with indisputable advantages the optical pyrometry has over the other measuring meathods, and in particular, over the measuring method based on the use of thermocouple elements immersed in a melt (which enables continuously controlling the temperature, contactlessly effecting the measuring process etc.) it has a number of disadvantages which manifest itself under operating conditions. Thus, the measurement accuracy of pyrometers depends to a great extent on the optical properties of a radiating surface and intermediate medium.
One of the promising trends in optical pyrometry used in measuring the temperature of molten metals is the development of methods which are based on the use of light guides which form an insulated channel for transmitting thermal radiation from a melt to a pyrometer, thereby making it possible to reduce the influence of the above factors on the measurement accuracy. To enhance the efficiency of such light guides they are incorporated in light guide units which are mounted in the lining of a metallurgical vessel so that one end of the light guide is exposed to the melt and the other one is brought out to a pyrometer.
However, providing a light-guide unit, having a high operational reliability and satisfactory optical features which would ensure an improved measurement accuracy and wherein the light guides could be used repeatedly, is a problem the specialists in this field encounter in their attempts to develop such a light-guide unit.
DESCRIPTION OF THE PRIOR ART
There is a great number of patents which have been recently granted in various countries (cf. USSR Authors' Certificates Nos. 146,533 and 271,067; Austria Pat. No. 280,650; Federal Republic of Germany Pat. No. 2,338,532) and which confirm that this problem is an urgent one. Although a great many attempts have been made, the above problem has not been satisfactorily solved yet.
There is known a light-guide unit comprising a light-transmitting rod made of light-permeable corrosion-resistant refractory material, preferably of quartz glass, housed within a thin steel pipe mounted inside another pipe made from refractory material (cf. for example, British Pat. No. 1,210,993). An annular gap formed between said pipes is filled with a refractory powder, in particular zirconium oxide. One end of the light guide is exposed to a molten metal, and the other one which extends outside the vessel is connected with a light-absorbing pyrometer by means of a flange.
The use of the above light-guide unit for measuring the temperature of molten metal is associated with a number of difficulties. First, the light-transmitting rod of the above light-guide unit cannot be used repeatedly since this light-transmitting rod fails when the operation of the metallurgical vessel is stopped and the lining thereof fully cooled, for example, in the case of replacing the lining after its service life has run out. Since the service life of the lining in many metallurgical vessels is not longer than several days, the frequent replacement of the light-transmitting rod makes the measuring process with the use of the above light-guide unit costly, especially when they incorporate high-priced materials such as synthetic corundum. In the metallurgical vessels having a lining with a longer service life (several months), and wherein the cost of the measuring process is lower as a result, nevertheless the problem of repeatedly using light-transmitting rods remains an urgent one.
It is to be noted that because in the prior art light-guide unit the annular gap between the tubes is filled with the zirconium oxide powder having a relatively high sintering temperature, said powder is not sintered when the lining is sintered or during the melting
REFERENCES:
patent: 3051035 (1962-08-01), Root
patent: 3077539 (1963-02-01), Blau, Jr. et al.
patent: 3570277 (1971-03-01), Dorr et al.
patent: 3745834 (1973-07-01), Veltze et al.
patent: 3862574 (1975-01-01), Antoine et al.
Chugunny Evgeny G.
Shumikhin Vladimir S.
Zhukov Leonid F.
Institut Problem Litya Akademii Nauk Ukrainskoi SSR
Yasich Daniel M.
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