Patent GB-924408-A (GB)
Title: Temperature measuring apparatus
IPC: C21C5/46
Filed: 1962-01-24
Abstract: 924,408. Transducer casings. MAX-PLANCK-INSTITUT FUR EISENFORSCHUNG, and PHOENIX-RHEINROHR A.G. VEREINIGTE HUTTEN UND ROHRENWERKE. Jan. 24, 1962 [Feb. 18, 1961; Oct. 13, 1961], No. 2661/62. Class 40 (1). An apparatus for continuously measuring the temperature of iron and steel melts comprises means for preventing a ceramic plug between the masonry of the melt vessel and a protective tube enclosing the sensitive element from becoming sintered to the masonry. Fig. 1 shows a protective tube 4 containing a thermocouple element 3 which extends below the surface of the metal when the converter vessel is operative. The portion of the tube 4 passing through a passage 2 in the masonry vessel wall is surrounded by a refractory bearing member 7 of material impervious to gas a cylindrical part 7<SP>1</SP> partially sealing the passage 2 so that a narrow annular passage results through which an inert gas such as argon is injected. The member 7 may be backed with a granular substance 13 such as magnesite or aluminium oxide. A tube 6, say of steel is cemented to the protective tube 4 and contains the thermocouple wires, the tube 6 being centred by radial arms 8. A cover 9 hermetically closes passage 2 and inert gas, the pressure of which is measured at 12 is introduced through a convector 10. Gas flow over the periphery of the plug 7 may be achieved in various ways. Thus Fig. 2 shows a plug 7 made from porous material the part 7<SP>1</SP> now sealing the passage 2. Alternately the porous material may extend around an impervious ceramic core. In another embodiment an impervious plug is slotted to admit the gas. Fig. 5 shows a porous plug 27, 28, the vessel wall passage 2 being lined with either sleeve bricks or a material 2<SP>1</SP> which is sintered. The porous material may comprise mixtures of magnesite or burned dolomite or lime or magnesia or corundum, or silicon or quartz. Substantially equal proportions of grains less than 0.06 mm. and grains of from 0.12 to 0.25 mm. and used together with waterglass or phosphoric acid as a binding agent. A 50% to 70% aqueous solution of the binding agent is used and added in an amount of between <SP>1</SP>/ 6  to ¢ preferably from 1/4 to <SP>1</SP>/ 3  of the volume of the refractory substance. The proportion of aqueous solution used determines whether the mixture is tamped pressed or poured into the channel 2<SP>1</SP>. Additives giving off gases or vapours at the masonry temperature, such as wood chips, granular plastic compositions or other decomposing inorganic or organic compounds such as limestone, soda, cellulose or sugar may be mixed with the material to render the plug porous. In the construction shown in Fig. 5 the ceramic tube 2 is prepared by tamping and sintering a composition such as magnesia having a small addition of waterglass. Ceramic disc 27 extends from 1 to 5 cm. from the closed end of a tube 4, over an iron extension 25. The gap between the tube 2 and the disc 27 is filled with a plug compound 28, the water from which evaporating at the masonry temperature whilst the waterglass or phosphoric acid or boric acid melts and sinters the ingredients of the mixture. To replace the detector head, the element 3 is removed from the tube 4, the iron tube 25 is extracted or knocked into the converter and the plug 27, 28 drilled out.