US 1773826 A
Description (OCR text may contain errors)
Aug. 26, 1930. F. c. slMMs 1,773,826
PYROMETER TUBE Filed July 14, 1928 INVENTOR Fanh C. Simms BY`7(/777 Z ATTORNEY Patented Aug. 26, 1930 UNITED STATES FRANK C. SIMMS, F EAST PALESTINE, OHIO PYROMETER TUBE Application led July 14,
My invention relates to temperature measuring devices, and particularly to pyrometer tubes.
An object of my invention is to provide a unitary structure for a composite pyrometer tube that shall permit of the tube being quickly inserted in and withdrawn from the chamber of a furnace without danger of breaking or cracking.
Another object of my invention is to provide a unitary pyrometer tube structure that shall embody a gas tight inner refractory member, a heat-equalizing intermediate ceramic member, and an outer highly refractory and gas and slag resistant member. These three elements are preferably made each in the form of a tube, closed at one end and open at the other, and in intimate Contact with each other over their engaging surfaces.
In practicing my invention, I provide a laminated tube structure comprising an inner tube closed at one end, made of ceramic material and fired or burned at such heat as to ensure vitrifaction, an intermediate tube also closed at one end molded or placed on the inner tube and composed of such ceramic materials as to permit of reasonably slow penetration thereof by heat, and an outermost coating or tube of suitable thickness, and composed of a ceramic material which will prevent slag from penetrating the bodies of the other tubes.
In the single sheet of drawings, Figure l is a view, in longitudinal section, of a pyrometer tube embodying my invention,
Fig. 2 is a view, in Vertical lateral section of a furnace, shown generally only, with which is associated the device embodying my invention.
rIhe pyrometer tubes used heretofore have been made of a material which had to be handled very carefully in actual use, the tube being inserted in and withdrawn from a high rate of movement in order to prevent fracture thereof. If a tube 0f this kind was inserted into a furnace chamber very quickly the effect of the high heat was such as to cause the tube to crack or break.
temperature furnace chamber at a very slow 1928. Serial No. 292,859.
Referring more particularly to Fig. 1 of the drawings, I have there illustrated a laminated pyrometer tube 11 embodying an inner tube 12 which is preferably made of a hard, dense clay, such as is used for porcelain articles and which has been fired at a temperature of approximately 2000 F.
An intermediate tube 13 is located therearound and in intimate engagement therewith, the material of this tube being a mixture of comminuted fused alumina,a high temperature clay, and a small amount of a. suitable binder such asdextrine. I prefer to use a mixture of 30% of high temperature cla and approximately of fused alumina, a 65 though I desire it to be understood that these proportions are illustrative only and may be departed from to a certain' extent. Enough suitable binder is added to the finely divided clay and the fused alumina to make a rela- 70 tively moist mixture of the general consistency of heavy cream.
The tube 12, which may be of any desired thickness on the order of from 1/8 to 5% inch wall thickness and which is closed at one end as shown, may be dipped into the moistened mixture of clay and alumina a sufficient number of times to provide a relatively thick closely adherent coating around the exterior of the tube 12. It may be necessary to permit the coating obtained by each dipping to dry for a short period in air before another coating is applied. A sufiicient number of dippings are made to provide a relatively thick coating or tube 13, which thickness may be equal to or slightly greater than the thickness of the wall of tube 12. I may also mold the fused alumina and clay coating around or on the inner tube.
An outer tube or coating 14 is provided and 90 I may make this of a ceramic material suitable for the desired purpose, such as magnesite or zirconium, the method of application being substantially the same as was hereinbefore set forth in connection with the coating 13. The Outer layer or coating may be applied as soon as the last layer of coating 13 has been thorf oughly dried.
I prefer, as noted above, to lire the porcelain tube 12, which I make in any suitable 10 or desi-red manner well knorm in the before applying thereto the two outer tubes orv coatings as explained above. .rfter these'plurality of coatin s have been thorou dried in air l place t e tube in a suitabe -rurnace chamber operating at a temperat re 'of not less than 20009 F and ossibly up to 390? F. rEhe firing is continue until the inner tube 12 has been vitried or re-fused to a greater extent than occurred during its initial hring,`
whereby it is rendered substantially gastight. Referring to Fig. 2 of the drawings, l have there illustrated a furnace structure 15 comprising a plurality-of walls of heat-insulating and high temperature resisting bricks or blocks surrounding a furnace chamberA 15' Any suitable means (not shown) may be provided to heat the furnace chamber. an o ening 16 is provided in one of the walls w ich is of such size'as to receive the pyrometer tube structure 11.
A thermocouple 17 is located within the pyrometer tube assembly 11 the tube extending suciently far into the furnace to subJect the thermocouple joint to the operating temperature existing in the chamber. Suitable indicating means (not shown) are connected to the two wires of the thermocouple to indicate the temperature, all as well hown in the art.
My improved laminated pyrometer tube structure is particularly adapted for use in furnaces in which special processes are being effected which give rise to fumes which attack ordinary ceramic materials, or in furreaches the innermost tube is substantially lib' uniformly distributed, thereby avoiding the possibility of breakage of the inner tube by reason of one portion thereof being at a temperature different from that of another portion. Finally, the outermost coating 14 provides a slag, gas, and fume resistant coat@ ing so that the'unitary tube structure embodying my invention can be used a relatively large number of times without any apprecia le sign of the material having been attached. I find it possible to insert a tube of this kind quickly intoa furnace or to withdraw it quickly from a furnace without danger of such thermal shock as would ordinarily result in fracture ofa single layer tube.v
The intermediate' coating or tube V13 has such thermal conductivity as will appreciably Second, an intermediate tube of such material and oharacteristlcs as to withstand smittenV thermal shock. This tube or lamination-absorbs the heat relatively slowly and prevents a sudden heat shock from injuring 'the inner tube. Third, an outer lamination or tube of a suitable ceramic lmaterial adapted to withstand the penetrating action of slag'and fumes, to thereby save the other two tubes from the injury which may be caused by slag found in various types of furnaces.
Various modifications may be made in the device embodying my invention without departing'from the spirit and scope thereof, and I desire therefore that only such limitations shall be placed thereon as are imposed by the prior art or are set forth in the appended claims.
ll claim as my invention t-f L'As a new article of manufacture of the class described, a unitary laminated pyrometer tube structure comprising an inner highly refractory gas-tight tube of ceramic material, an intermediate tube of a refractory material constituting a heat shield for the inner tube, and an outer tube of a slag and fume resistant refractory material, all of said tubes being intimately bonded with each other by firing' the outer tubes and the inner tube as a unit.
2. As a new article of manufacture of the class described, a unitary triple wall pyrometer tube structure comprising an inner gastight layer of highly refractory ceramic material, an intermediate layer of a refractory material constituting a heat shield for the inner tube, and an outer coating of a slag and fume resistant refractory material, each of said layers being in intimate engagement with an adjacent layer and bonded thereto by firing the outer layers in position upon the inner layers.
3.' As a new article of manufacture of the class described, a unitary triple wall pyromlain, an intermediate layer of a mixture of fused alumina and a high temperature clay, and an outer layer of magnesite, eachv of said layers being in intimate engagement with an adjacent layer, the intermediate and outer v layers` being coated upon the adjacent inner layer and bonded thereto by rin-g said layers. i
4. As a new article of manufacture of the class described, a unitary triple wall pyrometer tube comprising a doubly fired inner layer of porcelain-like ceramic material, a singly fired intermediate layer of fused alumina and a high temperature clay, and a singly fired outer layer of a slag and fume reslstant ceramic material, each of said layers being .in intimate engagement with an adjacent layer and bonded thereto by the firing of the outer layers.
In testimony whereof I aiix my signature.
FRANK C. SIMM-Q`