US3647558A - Protected thermocouple and protection tube - Google Patents

Protected thermocouple and protection tube Download PDF

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Publication number
US3647558A
US3647558A US648821A US3647558DA US3647558A US 3647558 A US3647558 A US 3647558A US 648821 A US648821 A US 648821A US 3647558D A US3647558D A US 3647558DA US 3647558 A US3647558 A US 3647558A
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United States
Prior art keywords
tube
protection tube
refractory
composite protection
molten
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Expired - Lifetime
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US648821A
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English (en)
Inventor
Carl H Mcmurtry
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Stemcor Corp
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Carborundum Co
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Assigned to KENNECOTT CORPORATION reassignment KENNECOTT CORPORATION MERGER (SEE DOCUMENT FOR DETAILS). EFFECTIVE DEC. 31, 1980 NORTH DAKOTA Assignors: BEAR CREEK MINING COMPANY, BEAR TOOTH MINING COMPANY, CARBORUNDUM COMPANY THE, CHASE BRASS & COPPER CO. INCORPORATED, KENNECOTT EXPLORATION, INC., KENNECOTT REFINING CORPORATION, KENNECOTT SALES CORPORATION, OZARK LEAD COMPANY, PLAMBEAU MINING CORPORATION, RIDGE MINING CORPORATION (ALL MERGED INTO)
Assigned to STEMCOR CORPORATION, 200 PUBLIC SQUARE, CLEVELAND, OHIO 44114 A DE. CORP. reassignment STEMCOR CORPORATION, 200 PUBLIC SQUARE, CLEVELAND, OHIO 44114 A DE. CORP. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: KENNECOTT MINING CORPORATION
Assigned to KENNECOTT MINING CORPORATION reassignment KENNECOTT MINING CORPORATION CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). EFFECTIVE DEC. 31, 1986. (SEE DOCUMENT FOR DETAILS) Assignors: KENNECOTT CORPORATION
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Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K1/00—Details of thermometers not specially adapted for particular types of thermometer
    • G01K1/08—Protective devices, e.g. casings
    • G01K1/10—Protective devices, e.g. casings for preventing chemical attack
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
    • H10N10/10—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects
    • H10N10/17—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects characterised by the structure or configuration of the cell or thermocouple forming the device

Definitions

  • PROTECTED THERMOCOUPLE AND PROTECTION TUBE Filed June 26, 1967 CARL H. MCMURTRY United States Patent t fine 3,647,558 PROTECTED THERMOCOUPLE AND PROTECTION TUBE Carl H. McMurtry, Lewiston, N.Y., assignor to The Carborundum Company, Niagara Falls, N .Y. Filed June 26, 1967, Ser. No. 648,821 Int. Cl. H01r 1/04 U.S. Cl.
  • a composite protection tube for protecting a temperature measuring means in a molten metal bath comprising an inner refractory tube, a consumable outer metallic casing, and an intermediate layer of a carbon impregnated refractory grain to minimize thermal shock and resist the corrosive attack of molten metals and their associated slag.
  • This invention relates to a composite protection tube and more particularly to a composite protection tube for a temperature measuring means for enabling utility of the same at elevated temperatures under adverse conditions.
  • the present invention may be applicable in various metal producing environments, it will be convenient to refer specifically to its use in association with the steel producing art.
  • an oxygen blowing process of relative contemporary origin, is becoming increasingly popular and is rapidly replacing the open hearth steelmaking process.
  • oxygen of high purity is blown onto the surface of a molten steel bath to produce a product comparable to, or better than, that obtained in an open hearth furnace.
  • the time required to rene the melt may be as little as thirty minutes as contrasted to ten hours with the open hearth process.
  • One of the critical problems encountered in the rapid steel-making process is in the measurement of the bath temperature in order to ascertain when the proper tapping temperature, which is in the neighborhood of 2900-3000 F., is reached. Because of the relatively short time involved as contrasted to the open hearth process, the techniques employed in the open hearth process for measuring the temperature of the molten bath are unsatisfactory for the oxygen process.
  • One temperature measuring device currently in use comprises a thermocouple encased in a sheathing which is lowered into the molten bath. The temperature is quickly measured before the device is consumed within the molten bath.
  • any temperature indication below or above the tapping temperature requires that the molten bath be retreated accordingly and repeated temperature measurements must be taken during the heat. It is readily apparent that eiliciency and production are seriously impaired resulting in excessive costs.
  • the general purpose of the present invention provides a solution to the above problem by utilizing a composite protection tube for a temperature measuring device which may be immersed in a molten metal bath for relatively long periods of time to enable the temperature measuring device to continuously measure the temperature of said bath.
  • thermocouples for relatively long periods of time at very high temperatures and in many different environments.
  • FIG. 1 is a longitudinal sectional 'View of the composite protection tube constructed in accordance with the principles of this invention illustrating a temperature measuring means mounted and encased therein;
  • FIG. 2 is an enlarged fragmentary longitudinal sectional view of the composite protection tube of FIG. 1 showing the tube before use;
  • FIG. 3 is an enlarged fragmentary longitudinal sectional vieW of the composite protection tube of FIG. 1 illustrating the tube after it has been immersed in a molten bath of metal.
  • the annulus 16 defined by the exterior wall surface of the inner tube 12 and the interior wall surface or the casing 14 is lled with a slag resisting material 18, such as carbon impregnated magnesia grain, for example, which is known to have excellent resistance tcl) the corrosive attack of most metals and to high-lime s ags.
  • thermocouple such as a thermocouple, generally designated 20, is encased within protection tube 10.
  • the thermocouple comprises a pair of thermocouple lead wires 22 and 24 having a suitable insulated sheathing 26 disposed thereabout, said lead wires joined together at one end as by means of welding for example, to form a hot junction 28.
  • the protection tube 10 is closed at one end as indicated at 30 and is provided with a threaded portion 32 at the other end releasably secured to a coupling 34 having a threaded bore 36 at one end and a threaded counterbore 38 at the other end thereof for releasably securing one end of an externally threaded hollow member 40 thereto.
  • a terminal assembly Releasably secured to the other end of member 40 is a terminal assembly, generally designated 42, having a housing comprised of a metallic shroud 44 and a dielectric collar 46 suitably secured in axial abutting relationship to shroud 44 by means of screws 48.
  • thermocouple lead wires 22 and 24 are connected to the screws 56 of terminals 52 and 54, respectively.
  • Screws 58 of terminals 52 and 54 are adapted to accommodate electrical leads (not shown) connected to an indicating meter (not shown) in a conventional manner.
  • An inner tube having a closed end is inserted in a vertically extending iron pipe having a threaded portion at one end.
  • the open end of the inner tube protrudes beyond the threaded portion of the pipe, said inner tube being disposed coaxially in the pipe and maintained in position by means of a pig or the like.
  • a suitable granular refractory material such as dry MgO grain, is poured into the annulus dened by the exterior wall surface of inner tube 12 and the interior wall surface of casing 14.
  • the granular refractory material is vibrated as it is poured in order to obtain optimal density.
  • the provision of various size graded particles increases the density of the finished product.
  • a suitable carbonizable binder, such as pitch for example is heated to a liquid state and poured into the casing to infiltrate or impregnate the granular refractory grain. The resulting mixture is heated slowly to a temperature of 800 C. in
  • the above process is repeated with the exception that instead of pitch, the mixture is reimpregnated with a suitable resin, such as liquid furfuryl alcohol polymer for example.
  • a suitable resin such as liquid furfuryl alcohol polymer for example.
  • the process is repeated a third time to further increase density, completely lill the voids in the mixture, and increase the carbon yield. Not only does the carbon serve as an efficient bonding agent for the refractory particles, but also aids the refractory body in resisting the chemical attack of the slag present in the vessel during the metalmaking process.
  • the assembly is desirable to subject the assembly to a vacuum treatment before each impregnation or reimpregnation step to facilitate the absorption of the impregnant by the refractory particles.
  • the bonding agent can be mixed with the refractory grain prior to pouring.
  • a composite protection turbe was constructed by inserting an alumina inner tube into a vertically extending iron pipe having a threaded portion at one end.
  • the alumina tube was coaxially located relative to the pipe and the closed end of said tube was disposed inwardly from the end of the pipe remote from the threaded portion.
  • a jig or the like may be employed to maintain the alumina tube in the desired position relative to the pipe.
  • a size graded MgO mix of about the following screen analysis, -lO +16 mesh, 10% -80 -l-lOO mesh and 30% -200 mesh, was poured into the annulus between the alumina tube and pipe. The pipe and mixture were vibrated as the mix was poured in order to obtain the optimal bulk density of said mix.
  • the jig was removed, the pipe inverted and the remainder of the annulus lilled with the refractory grain.
  • the assembly was placed in an autoclave and subjected to a vacuum in order to facilitate the absorption of an impregnant by the granular material.
  • a carbonizable binder such as a heated liquied bonding pitch, comprising approximately 11.5 percent by weight of the refractory material, was pressure poured into the annulus of the assembly to impregnate or infiltrate the MgO mix. The assembly was then heated slowly up to a temperature of 800 C. to carbonize and drive off the volatiles.
  • the assembly was cooled and the impregnating and carbonizing cycles were repeated two more times with the exception that a liquid furfuryl alcohol polymer catalyzed with 5 percent maleic anhydride was utilized as the impregnant rather than pitch.
  • the reimpregnating and carbonizing cycles strengthen the carbon bond between the refractory particles by completely filling the pores in and around the refractory particles.
  • liquidified bonding agent comprise about l-20 percent by weight of the refractory material used.
  • three impregnations are preferable, it should be realized that the principles of this invention envisage more or less than three impregnations, as desired. It should be appreciated by those skilled in the art that either of the two carbonizable bonding agents mentioned above may be substituted for the other in any of the three impregnating steps. Also, other impregnants, such as the phenol-formaldehyde types for example, may be substituted for those heretofore mentioned.
  • the closed end of the inner tube is preferably disposed inwardly of the bottom end of the outer casing
  • the principles of this invention also contemplate mounting the closed end of the inner tube flush with the bottom end of the casing or protruding therebeyond, as desired.
  • the length and diameter of the protection tube may be varied dependent on the specific environment in which it is to be used and the economics of design.
  • Tests were conducted on composite protection tubes made in accordance with the above example to determine its resistance to thermal shock, corrosion and resistance to chemical attack from molten metal and its associated slag.
  • thermocouple 3 was observed at the slag line of the protection tube but subsequent sectioning disclosed that no slag or steel had penetrated the inner alumina tube indicating that the useful life of the tube was not expended and could survive immersion for a longer period of time.
  • a third test was conducted in the research laboratory of a large steel manufacturer in connection with an oxygen blowing process for making steel.
  • the protection tube was immersed 2 inches below the slag line in a bath of molten steel for the entire duration of a 30-minute blow, and temperatures were recorded continuously ranging from 2650 F. at the beginning to 3080 F. at the end. After removal, little erosion or corrosion was detected and no fissures or cracks were observed. The thermocouple was unaffected by this immersion test and could be used again.
  • the slag composition was basic with a CaO/SiOz ratio of approximately 2/1 and was similar to the slag which prevails under normal operating conditions.
  • the rate of surface removal of the MgO layer of the tube at the slag line was 0.12 inch per hour and there was no surface removal of the MgO ⁇ layer on that portion of the tube exposed to the melt.
  • magnesia grain is preferable as the protective layer
  • any suitable refractory oxide grain may be used such as zirconia, alumina, mullite, and dolomite by Way of example.
  • other carbides, borides and nitrides may be used, such as zirconium carbide, zirconium diboride, zirconium carbonitride and aluminum nitride, each suitably impregnated with carbon in a manner similar to that described in connection with the refractory oxides, within the purview of the present invention.
  • this invention contemplates the use of inner tubes that are made, for example, of zirconia, thoria, beryllia, mullite, an alumina-zirconia mixture, and other refractory materials resistant to the molten metal environment in which it is to be used.
  • the outer tube or casing need not be restricted to a cast iron composition but may be made of the same metal in which it is to be immersed, such as nickel, stainless steel, copper and aluminum by way of example.
  • the composite protection tube of this invention has utility in applications other than for shielding temperature measuring devices.
  • the tube may be hollow throughout its length and serve as a pressure pouring tube or a lance for directing oxygen therethrough in those metal producing operations that require the lance to be inserted through the slag line into the melt. Still other uses Will be readily apparent to those skilled in the art.
  • a new and improved composite protection tube for housing a temperature measuring device in an improved and more efficient manner.
  • An expendable outer metallic tube or casing is employed for providing the mechanical strength required to pierce the semi-molten material at the slag line and to distribute heat evenly during insertion to minimize thermal shock.
  • An inner refractory tube, resistant to the chemical attack of the molten metal is provided for encasing a temperature measuring device and an intermediate layer of a carbon impregnated refractory grain surrounds the inner refractory tube for resisting the corrosive attack of slag upon melting of the expendable outer casing.
  • a composite protection tube adapted to be immersed in a molten metal bath comprising: an elongated inner tube having an exterior wall surface; an elongated outer tube having an interior wall surface spaced radially from said exterior wall surface and defining an annulus therebetween; and a solid body filling said annulus, said solid body consisting of granular refractory material bonded together by carbon.
  • a composite protection tube as defined in claim 1 wherein said refractory solid body comprises granular refractory material selected from the group consisting of oxides, borides, carbides and nitrides bonded with carbon.
  • thermocouple junction is located adjacent said closed end.
  • a composite protection tube as defined in claim 10 in which said outer tube has one end adapted for immersion in molten metal and said inner tube is closed at one end; said closed end of said inner tube being located inwardly from said one end of said outer tube; and a thermocouple junction located adjacent said closed end of said inner tube.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Temperature Or Quantity Of Heat (AREA)
US648821A 1967-06-26 1967-06-26 Protected thermocouple and protection tube Expired - Lifetime US3647558A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US64882167A 1967-06-26 1967-06-26

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US648821A Expired - Lifetime US3647558A (en) 1967-06-26 1967-06-26 Protected thermocouple and protection tube

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US (1) US3647558A (de)
BE (1) BE717107A (de)
DE (1) DE1773710C3 (de)
FR (1) FR1569518A (de)
GB (1) GB1184306A (de)
SE (1) SE352737B (de)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4060095A (en) * 1975-08-23 1977-11-29 Koransha Co., Ltd. Thermocouple protecting tube
US4721533A (en) * 1986-08-01 1988-01-26 System Planning Corporation Protective structure for an immersion pyrometer
US4871263A (en) * 1988-05-16 1989-10-03 Pyromation, Inc. Protective tube for a temperature sensor
US4984904A (en) * 1987-12-24 1991-01-15 Kawaso Electric Industrial Co., Ltd. Apparatus for continuously measuring temperature of molten metal and method for making same
US5181779A (en) * 1989-11-22 1993-01-26 Nippon Steel Corporation Thermocouple temperature sensor and a method of measuring the temperature of molten iron
US5230565A (en) * 1990-06-06 1993-07-27 Netsushin Co., Ltd. Pyrometer and a method for fusing an alumina pipe having a high purity
US5242226A (en) * 1991-07-27 1993-09-07 Hoechst Aktiengesellschaft Temperature-measuring instrument
US5456761A (en) * 1993-07-15 1995-10-10 Alcan International Limited High temperature and abrasion resistant temperature measuring device
US5474618A (en) * 1994-04-19 1995-12-12 Rdc Controle Ltee Protective ceramic device for immersion pyrometer
US5917145A (en) * 1996-03-14 1999-06-29 Alcan International Limited Method and apparatus for measurement of temperatures of molten aluminum and aluminum alloys
US6280083B2 (en) * 1998-01-12 2001-08-28 Isuzu Ceramics Research Institute Co., Ltd. Thermocouple lance with layered sheath for measuring temperature in molten metal
US6830374B1 (en) * 1999-08-16 2004-12-14 Temperature Management Systems (Proprietary) Limited Metallurgical thermocouple

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5036598B1 (de) * 1970-08-06 1975-11-26
JPS5376975U (de) * 1976-11-30 1978-06-27
US4238957A (en) * 1977-07-04 1980-12-16 Commonwealth Scientific And Industrial Research Organization Pyrometric sheath and process
GB2196430A (en) * 1986-09-22 1988-04-27 Electro Nite Probe for measuring in molten metal
BE905463A (nl) * 1986-09-22 1987-03-23 Electro Nite Sonde voor het meten in vloeibaar metaal.
GB9309931D0 (en) * 1993-05-14 1993-06-30 Winder Horbury Temperature sensing means

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4060095A (en) * 1975-08-23 1977-11-29 Koransha Co., Ltd. Thermocouple protecting tube
US4721533A (en) * 1986-08-01 1988-01-26 System Planning Corporation Protective structure for an immersion pyrometer
US4984904A (en) * 1987-12-24 1991-01-15 Kawaso Electric Industrial Co., Ltd. Apparatus for continuously measuring temperature of molten metal and method for making same
US4871263A (en) * 1988-05-16 1989-10-03 Pyromation, Inc. Protective tube for a temperature sensor
US5181779A (en) * 1989-11-22 1993-01-26 Nippon Steel Corporation Thermocouple temperature sensor and a method of measuring the temperature of molten iron
US5230565A (en) * 1990-06-06 1993-07-27 Netsushin Co., Ltd. Pyrometer and a method for fusing an alumina pipe having a high purity
US5242226A (en) * 1991-07-27 1993-09-07 Hoechst Aktiengesellschaft Temperature-measuring instrument
US5456761A (en) * 1993-07-15 1995-10-10 Alcan International Limited High temperature and abrasion resistant temperature measuring device
US5474618A (en) * 1994-04-19 1995-12-12 Rdc Controle Ltee Protective ceramic device for immersion pyrometer
US5917145A (en) * 1996-03-14 1999-06-29 Alcan International Limited Method and apparatus for measurement of temperatures of molten aluminum and aluminum alloys
US6280083B2 (en) * 1998-01-12 2001-08-28 Isuzu Ceramics Research Institute Co., Ltd. Thermocouple lance with layered sheath for measuring temperature in molten metal
US6830374B1 (en) * 1999-08-16 2004-12-14 Temperature Management Systems (Proprietary) Limited Metallurgical thermocouple

Also Published As

Publication number Publication date
DE1773710A1 (de) 1972-01-13
FR1569518A (de) 1969-05-30
SE352737B (de) 1973-01-08
BE717107A (de) 1968-12-02
GB1184306A (en) 1970-03-11
DE1773710C3 (de) 1978-04-20
DE1773710B2 (de) 1977-08-25

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AS Assignment

Owner name: KENNECOTT CORPORATION

Free format text: MERGER;ASSIGNORS:BEAR CREEK MINING COMPANY;BEAR TOOTH MINING COMPANY;CARBORUNDUM COMPANY THE;AND OTHERS;REEL/FRAME:003961/0672

Effective date: 19801230

AS Assignment

Owner name: STEMCOR CORPORATION, 200 PUBLIC SQUARE, CLEVELAND,

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:KENNECOTT MINING CORPORATION;REEL/FRAME:004815/0091

Effective date: 19870320

Owner name: KENNECOTT MINING CORPORATION

Free format text: CHANGE OF NAME;ASSIGNOR:KENNECOTT CORPORATION;REEL/FRAME:004815/0036

Effective date: 19870220