MXPA00004370A - Self-floating device for measuring the temperature of liquids - Google Patents

Abstract

A temperature sensor is supported in a device which floats in a liquid, the temperature of which is to be determined. Typically the sensor is the hot thermocouple element of a thermocouple and the liquid is a molten metal;the device may be constructed to float with the temperature sensor disposed at a desired distance below the upper surface of the liquid.

Description

AUTO-FLOATING DEVICE FOR MEASUREMENT OF LIQUID TEMPERATURE This invention relates to a device for supporting a temperature sensor inside a liquid, to a temperature sensor assembly incorporating such a device and to a method for determining the temperature of a liquid; more especially the invention has to do with such a device, sensor assembly and method in which the temperature sensor is an immersion pyrometer for measuring the temperature of a molten metal, molten salt or other liquid at a high temperature. In particular, the invention has to do with such a device, sensor assembly and method in which the device supports a hot thermocouple element, and the device floats in the liquid, whereby the hot thermocouple element can be disposed in a Default, desired or selected position within the liquid.

BACKGROUND OF THE INVENTION Immersion pyrometers for measuring the temperature of a molten metal or other liquid at a high temperature are typically immobile and are placed in a fixed position in the liquid. For example, the pyrometer may be extended in the liquid through a wall of a container containing the liquid.

The immersion pyrometer is housed or supported in a device which protects the pyrometer from the liquid. Examples of protection devices are described in U.S. Patent No. 5,474,618 to C. Allaire; U.S. Patent No. 5,577,841 to Cowall; Patent of E. U., No. 4,692,556 of T. Bollen et al. And Patent of E. U., No. 5,456,761 of M. Auger et al. Since the immersion pyrometer is immobile, different parts of the pyrometer are exposed to the liquid as the liquid level rises or falls in the container in which it is housed. Similarly, in the case where the liquid is a molten metal, and a slag is formed on the surface of the molten metal, the rise or fall of the level of the molten liquid results in exposure of different parts of the pyrometer to the slag. In addition, the pyrometer / portion not immersed in the liquid and which is exposed to possible attack by the atmosphere above the liquid, varies with the rise and fall of the liquid. A further problem is that these previous pyrometers are subject to a fluctuating thermal gradient in the liquid, as well as to a fluctuating liquid line level.

BRIEF DESCRIPTION OF THE INVENTION It is an object of this invention to provide a device for supporting a temperature sensor such as a thermocouple element for determining the temperature of a liquid, which floats in the liquid. It is a further object of the invention to provide a temperature sensor assembly that employs a device to support a temperature sensor of the assembly, which floats in the liquid, whose temperature is to be detected. It is still another object of the invention to provide a method for determining the temperature of a liquid in which a device supporting a temperature sensor floats in the liquid with the temperature sensor disposed below the upper surface of the liquid. According to the invention, there is provided a device for supporting a temperature sensor within the interior of a liquid comprising: a case having an interior cavity extending from an open end to a closed end for receiving the temperature sensor, said device being adapted to float in the liquid with said closed end immersed in the liquid. According to another aspect of the invention, there is provided a temperature sensor assembly for determining the temperature of a liquid comprising: a) a temperature sensor, b) a device for housing the temperature sensor to support the sensor within the interior of the liquid, said device comprising a case having an interior cavity extending from an open end to a closed endsaid temperature sensor being housed within said cavity, said device being adapted to float in the liquid with said closed end immersed in the liquid. According to yet another aspect of the invention there is provided a method for determining the temperature of a liquid, comprising: providing a liquid bath having a top surface, floating in said liquid a device supporting a temperature sensor, said device comprising a case having an inner cavity extending from an open end to a closed end, said temperature sensor being housed in said cavity at said closed end, and said closed end being submerged in said liquid, allowing the temperature of the sensor is adjusted in response to the temperature of the liquid, and determining the temperature of the liquid from the adjusted sensor.

DESCRIPTION OF PREFERRED MODALITIES The invention is applicable to detect the temperature of liquids, but has particular application in the detection of the temperature of materials that are solid at normal temperatures and liquids at elevated temperatures. In preferred embodiments the invention relates to the detection of the temperature of molten metals and salts and is described more particularly hereinafter by reference * to a particularly important embodiment in which the temperature of a molten metal is to be determined. i) Support Device The support device of the invention, which supports a temperature sensor, eg, a hot thermocouple element, is constructed of materials and / or has such design parameters that it floats on the molten metal, with a lower portion of the device, housing the hot thermocouple element, immersed in the molten metal. In this way an upper end of the device extends above the upper surface of the molten metal, and a lower end of the device extends below the surface of the molten metal. Alternatively, if the device is not made of a material or is constructed with such parameters that it floats on the molten metal, a separate component or member can be employed which makes it floatable. The case is suitably formed of a refractory material that will support the molten metal, and retains its structural integrity when it floats on the molten metal with its lower end immersed in the molten metal. The case has an internal cavity defined by an elongated hole which is closed at the lower end of the case and open at the upper end of the case. A hot thermocouple element and its connecting conductor can thus be inserted along the cavity to place the hot thermocouple element at the closed end of the bore. The refractory case thus protects the hot thermocouple element and its connection conductor. The refractory material can be a mixture of AI2O3, SiO2, CaO, MgO, ZrO2, AlN, SiC, Si3N4, C and the like. The selected composition is such that it confers on the refractory case the resistance required against corrosion by the liquid whose temperature is to be measured, as well as the required thermomechanical properties, including mechanical strength and resistance to thermal shock. The device also includes an external protective case surrounding the refractory case, for example, a metal shield and a particular reference will be made hereinafter to a metal shield. This metallic shield is suitably of the shape of a cylinder with an open end (toward the bottom part of the device) and a closed end (towards the top of the device) through which the thermocouple element and its conductor is inserted. The length of this metal shield is at least equal to the length of the non-submerged part of the refractory shield after the latter has been introduced into the liquid whose temperature is already being measured. The metallic shield is suitably made of a pure metal or an alloy whose melting temperature must be higher than the temperature of the atmosphere located above the liquid whose temperature is being measured. If the atmosphere is oscillating, it is preferred to use a metal or alloy having a high oxidation resistance, such as Ni-Cr or Ni-Co alloys. The internal diameter of the metal shield is greater than the external diameter of the refractory case. This creates a space between the shield and the case. This space, whose width or thickness is preferably less than 5 mm, is closed at one end by the closed end of the metal shield, and at the other end by the liquid in which the device is submerged.

The metal shield provides a number of functions that include: a) prevents deterioration of the refractory case by the action of the atmosphere above the liquid level; b) minimizes the corrosion of the refractory shield by the action of slag or foam present in the upper surface of the liquid; c) minimizes the effect of thermal shock on the refractory case during its insertion into the liquid. For example, the refractory case made of materials such as AI2O3 / C, MgO / C or ZrO2 / C, are protected by the metal shield against oxidation of the oxidizing atmosphere found above the molten steel in a pot. The sealed space between the shield and the case is quickly filled with reducing gas, during use, after the oxygen initially contained in the space has been converted to carbon monoxide by reaction with the carbon contained within the refractory materials. In this same example, the molten slag that forms on the upper surface of the molten metal in the pot, is prevented from reaching the refractory case by the presence of the metallic shield whose resistance to dissolution by the slag is much greater. When the device is immersed in the molten steel, the submerged bottom end of the refractory case is exposed rapidly to a temperature of about 1500-1600 ° C while the non-submerged upper end is exposed to a maximum temperature of less than about 800 ° C. With the presence of the surrounding metal shield, which is highly thermally conductive compared to the refractory case, the initial thermal gradient in the refractory shield near the upper surface of the metal is reduced since the heat is conducted more rapidly towards the top of the shield. The refractory case must have sufficient heat conductivity to allow the thermocouple element it houses to respond to the temperature of the molten metal. In preferred embodiments especially the device is adapted to float with the closed or lower end disposed at a predetermined or selected distance below the upper surface of the liquid, eg, molten metal, in which the device floats. In this way, the thermocouple element can be disposed at a desired, predetermined or selected distance below the upper surface of the liquid, so that the temperature at a desired location within the liquid can be determined. Thus, in a particularly preferred embodiment of the invention there is provided a device for supporting a thermocouple conductor within the interior of a liquid whose temperature is to be determined, comprising: i) a refractory housing having an interior cavity for receiving a conductor thermocouple, said housing having an upper end and a lower end, ii) an outer protective shield surrounding at least the upper end of said refractory housing, iii) means for making said device in the liquid with said upper end of said device. said refractory housing extending above the liquid, and said lower end of said refractory housing submerged in the liquid, and with said external protective shield protecting said upper end of said refractory housing from an environment above the liquid, and iv) said refractory housing being adapted to isolate the thermocouple conductor from the liquid. ii) Temperature Sensor The temperature sensor assembly comprises a support device as described hereinabove, and a temperature sensor. In particular the temperature sensor may comprise the hot thermocouple element of a thermocouple, the hot thermocouple element being disposed in the perforation of the case, adjacent to the closed or lower end and the cold thermocouple element and relative components of the thermocouple being placed away of the device and the molten metal. As is well known, the hot element of the thermocouple is electrically connected to the cold element of the thermocouple, and the potential difference between the elements, which arises from its difference in temperatures, is measured by conventional means. The potential difference provides a parameter from which the temperature of the liquid can be determined. The thermocouple can be made of conventional thermoelectric elements, such as Pt / Pt-Rh metals or the like, which are usually inserted within a ceramic or metal protective shield, such as alumina or Ni-Cr or Ni-Co alloys or the similar ones. The hot junction of the thermocouple element is suitably in contact with the closed end of the refractory case. Thus, in a particularly preferred embodiment of the invention, a thermocouple assembly for determining the temperature of a liquid is provided, comprising: a) a thermocouple having a hot thermocouple element and a cold thermocouple element and means for determine a potential difference between these elements, b) a device that supports said hot thermocouple element within the interior of a liquid whose temperature is to be determined, said device comprising: i) a refractory housing having an interior cavity for receiving said hot thermocouple element, said housing having an upper end and a lower end, ii) a protective shield Externally surrounding at least the upper end of said refractory housing, and means for making said device floatable in the liquid with said upper end of said refractory housing extending above the liquid, and said lower end of said refractory housing submerged therein. liquid, and with said shield external protector protecting said upper end of said refractory housing from an environment above the liquid, and iv) said refractory housing being adapted to isolate the hot thermocouple element from the liquid.

Iii) Method for Determining Temperature In the method of the invention, the support device that houses the temperature sensor floats in the molten metal. In this way the temperature sensor can be placed at a desired, predetermined or selected distance below the upper surface of the molten metal, in a bath of molten metal. Even though the level of molten metal and thus the location of the upper surface of the molten metal can rise and fall, the floating device will keep the temperature at the same distance below the upper surface of the molten metal. Thus, the temperature sensor can be maintained at a constant distance from the metal surface rising and falling, inside the metal bath, and the temperature at a desired location within the metal bath can thus be continuously monitored over a long period. . Thus, in a particular embodiment of the invention there is provided a method for monitoring the temperature of a liquid comprising: A) providing a thermocouple assembly having a hot thermocouple element, a cold thermocouple element and means for determining a difference in potential between said elements, B) isolating said hot thermocouple element within an interior cavity of a refractory housing having an upper end and a closed lower end, at least said upper end which is surrounded by an external protective shieldsaid refractory housing and said outer protective shield defining a flotation device, C) floating said device in said liquid with said lower end of said refractory housing submerged in said liquid and said upper end extending above said liquid so that said external protective shield protects said upper end of an environment above the liquid, D) allow the temperature of the hot thermocouple element to adjust in response to the surrounding liquid temperature, and E) measure the potential difference between said hot and cold elements at the cold ends of the conductors thereof and determine the temperature of the liquid therefrom.

BRIEF DESCRIPTION OF THE DIAMETERS Figure 1 is a schematic representation of a floating support device of the invention; Figure 2 is a schematic representation of a floating support device of the invention in another embodiment; Figure 3 is a schematic representation of a device of the invention in use, with a guide member; and Figure 4 is a schematic representation of a device of the invention as shown in Figure 3 as used in a pot test.

DESCRIPTION OF THE PREFERED MODALITY WITH REFERENCE TO THE DRAWINGS With reference to Figure 1, a device 10 of the invention is shown in a molten metal 12.

The device 10 includes a refractory case 14 having an internal cavity or bore 16 having a blind or closed end 18 and an open end 20. The device 10 has an upper end 22 and a lower end 24. A metal shield 26 surrounds the upper end 22 of the case 14.

The metal shield 26 includes a circumferential or circumscribing wall 28 and a roof 30. An inner face of the wall 28 is separated from an outer face of the upper end 22 by a space 32. A conductive or extending wire 34 of the thermocouple (no. shown) extends through the roof 30 to the bore 16 to place a hot thermocouple element (not shown) at the closed end 18 of the bore 16. The molten metal /) 12 forms a bath having a top surface 36. The device 10 thus floats on the molten metal 12 with the lower end 24 of the refractory case 14 submerged in the molten metal 12 and the upper end 22 of the refractory case 14 extending above the upper surface 36 of the molten metal 12. The peripheral wall 28 of the metal shield 26 extends upwardly of the upper surface 36, and protects the upper end 22 of the environment above the surface 36 of the metal, said environment may include slag (not shown) floating on the surface 36, and a oxidizing atmosphere above the surface 36. Also shown in Figure 1 is a lower part 38 of the shield 26 which has been dissolved by the molten metal 12 as a result of the immersion, which includes a damper 40.

In particular, the metal shield 26 is of a material that dissolves or melts when immersed in the molten metal 12, and the case 14 is of a material subject to deterioration by exposure to an environment above the molten metal 12. In the Figure 1 shows several parameters which are explained in Table 1.

TABLE 1 LIST OF PARAMETERS PARAMETERS DESCRIPTION RADIO R1 -. Internal radius of the refractory case R2 -. External radio of the refractory case R3? Internal radius of the metallic shield R4? External radio of the metallic shield LENGTH L1 - Length of the refractory case; L2? Immersion depth of the refractory case; L3 -. Thickness of the upper part of the metal shield; L4? Thickness of the bottom part of the refractory case; LB? Length of the "SHOCK ABSORBER".

WEIGHT W1? Weight of the refractory case; W2 - »Weight of the non-submerged side of the metal shield; W3 - »Weight of the upper part of the metal shield; WE? Weight of the extension wire.

DENSI DAD DD11 ?? Density of the refractory case; D2 - »Density of the metal shield; DL? Density of the liquid (whose temperature is to be measured); 1 DB - > Density of the "SHOCK ABSORBER".

When the device 10 is introduced to its floating position in the molten metal 12, the submerged portion 38 of the metal shield 26 dissolves or melts in the molten metal 12. If the density of the shield 26 is greater than the density of the molten metal the loss the resultant weight of the device 10 would be greater than the fall in the upward force exerted by the molten metal 12; the upward force being equal to the weight of the molten metal 12 in a volume equal to that of the submerged portion 38 (Archimedes Principle). In this case the device 10 would rise (climb) until its immersion volume reaches a value such that the upward force exerted by the molten metal 12 equals the new lower weight of the device 10 (without the portion 38). The damper 40 is employed so that the overall density of the submerged portion 38 (of the shield 26) is less than, or equal to, that of the molten metal 12. The damper 40 is of a material that is soluble in - 5 has a lower melting temperature than molten metal 12, and whose density is lower than that of shield 26. iv) Flotation Any means can be used to make the device floatable of support provided that its use is not inconsistent with the intended use of the support device. Two methods available depend on the density of the liquid, whose temperature is to be determined. , CASE 1: The density of the liquid whose temperature is to be measured is such that any combination of the parameters listed in Figure 1 and Table 1, (ie L1, L2, L3, L4, LB, R1, R2, R3 , R4, WE, D1, D2, DL, and DB) fails to return the self-floating device to the depth of immersion required (typically more than 15 cm). This is typically the case with low density liquids having a density of less than 4 g / cm 3. In such a case, a float can be attached to the device. The float could be made of ceramic fibers, such as insulating panels, or porous refractories, such as composites for molding insulators, having a low density, typically less than 0.5 g / cm 3. The latter case is shown, as an example, in Figure 2. With additional reference to Figure 2 a support device 1 10 includes a refractory case or case 1 14, a metal shield 126 and a float 142 engages with the external wall of the shield 126. In general, this device 1 10 shown in Figure 2 is the same device 10 shown in Figure 1, with the addition of the float 142. The parts of the device 1 10 which are the same as those in Figure 1 carry the same identification integers, but increased by 100. The material used as the float 142 must be resistant to corrosion by the liquid in which it is submerged partially. The dimensions of the float 142 are such that "the float 142 allows the desired immersion depth of the lower end 124 of the case 1 14.

CASE 2: In this preferred embodiment the density of the liquid whose temperature is to be measured is such that three exist in combination of the parameters listed in Figure 1 and Table 1, (ie, L1, L2, L3, L4, LB, R1, R2, R3, R4, WE, D1, D2, DL, and DB) whereby the device becomes self-floating, with the desired immersion depth (typically more than 15 cm) of the lower end 24. This is typically the case with liquids that have a high density greater than 4 g / cm3.

In this case, the relationship between the previous parameters is given by the following equation (see Table 1): P s WT = W1 + W2 + W3 + WE (1) where: P = (DL) p (R2) 2 (L2) (2) W1 = (D1) p [(R2) 2 (L1) - (R1) 2 (L1) + (R1) (L4)] (3) W2 = (D2) p [(L1) - (L2)] [(R4) 2- (R3) 2] (4) W3 = (D2) p (R4) 2 (L3) (5) P is the Arquimedian thrust upwards. WT is the overall weight of the device after partial immersion to a floating position. If the nuclear shield 26 is soluble or melts in the liquid in which it is immersed, a damper 40 should be used as shown in Figure 1 to prevent the rise of the device 10 after its immersion. In such a case, the required length of the shock absorber 40 (LB) is given by the following equation (see Table 1): [(D2) - (DL)] (L2) LB = (6) t (D2) - (DB) ] Otherwise, the rise or elevation of the device 10 above the surface 36 would cause two problems: 1) The inability to measure the temperature of the liquid at predetermined locations below the surface 36; 2) The exposure of the refractory case 14 near the top of the liquid, to the atmosphere as well as to the slag or foam that may be present, that is, the environment above the surface 36. The need for the damper 40 under the conditions above is also applicable for "CASE 1" above. With further reference to Figure 3, a device 10 of Figure 1 floating in the molten metal 12 is shown. The device 10 is held upright by a tubular guide 44 which extends through an opening 46 in a cover 48 of a container (not shown) housing the molten metal 12. The tubular guide 44 has a lower end 50 tapered inward which facilitates the removal of slag from the device 10 as it is removed from the container.

EXAMPLE 1: This example is to show how the equations can be used (1) to (6) to calculate the dimensions of each component in the Figure 1, which allow to achieve a self-floating device to measure the temperature of molten steel in a pot, 40.64 cm from the top of the liquid metal. Consider the following values: R2 = 3.175 cm R3 = 3.275 cm (ie, (R3) - (R2) = 1 mm) W1 = 4.761 Kg WE = 0 (ie without extension wire) DL = 7 g / cm3 (ie, lower limit for density of molten steel D2 = 8.08 g / cm3 (ie alloy density * "H R-160") DB = 2.7 g / cm3 (ie aluminum density) L1 = 76 cm L2 = 40.64 cm L3 = 0.635 cm *: a "Ni-Co" alloy sold by Haynes International Inc., Kokomo, IN, USA) From equations (1) to (5): (DL) p (R2) 2 (L2) + (D2) p [(L1) - (L2)] (R3) 2 - [(W1) + (WE)] (R4) = (7), (DL) p [(L1) - (L2) + (L3)] === > 4 = 3.90 cm Thus, the required thickness (T) of the metal shield is: T = (R4) - (R3) = 0.625 cm Finally, the length of the shock absorber is given by equation (6) and is: LB = 8.16 cm .

EXAMPLE 2: This example is to show that a cushion is effectively required when the metal shield is soluble or melts in the liquid in which it is submerged. The rise or rise (d) of the device after its first immersion in such a liquid, when no damper is used, is given by the following equation: (x-1) (WT) (A2) d = (8) (DL) [(A1) + (A2)] (A1) where: x = (D2) / (DL) y: WT = Initial total weight of the device before its immersion; A1 = External section of the refractory case; A2 = Section of the lateral part of the metal shield; D2 = Density of the metal shield; DL = Density of the molten metal; Considering the same values as in Example 1: d = 2.84 cm.

According to equation (8), the level of immersion of the device is kept constant during the dissolution or melting of the metal shield, only when its density (D2) is equal to the density of the liquid (DL).

EXAMPLE 3: This example is to show that the use of a metallic shield is required to protect the refractory case against the action of the atmosphere that is located in the upper part of the liquid whose temperature is to be measured. A first device was made according to Figure 1, but without the use of a metal shield. The refractory case was made of a refractory MgO / C material. This device was immersed at a constant level in molten iron which was contained within an induction furnace operating at approximately 1500 ° C. The results obtained showed that the refractory case was subjected, during the test, to severe oxidation from above. of the metal line and that its expected life in such conditions was only about 12 hours. A second device was made according to Figure 1 using the same refractory material as before, but without the use of a metal case made of "HR-160" alloy and having a thickness of 0.635 cm. This device was tested as the first device. The test was started by inserting the device in the molten metal for 12 hours at a constant immersion depth. Then the device was removed and left to cool. After cooling, the device was inserted again into the molten metal, but 2.54 cm deeper. The new position remained constant for 18 hours. After that period, the device was removed from the molten metal and allowed to cool to room temperature. After cooling the metal shield was removed and the refractory shield was visually inspected. No sign of oxidation was observed in the part of the refractory case that was placed above the molten metal during this 30-hour test. It should be noted that molten slag was also present in the metal line during the previous tests. No corrosion sign of the refractory shield was observed during the last test of the second device at the metal line level.

EXAMPLE 4: The device 10 illustrated in Figure 4 was inserted vertically with the aid of the guide 44 into molten steel in a pan for 262 minutes. The refractory case 14 was made from a mixture of alumina and carbon (the case 14 is commercially available from Vesuvius Crucible). During the test, the height of the molten steel in the pot varied from 58.42 to 78.74 cm, and the corresponding variation in the weight of molten steel in the pot was 14.75 to 16.50 tons. The molten steel was at a temperature of about 1565 ° C, and was covered by a slag layer having a thickness of about 12.7 centimeters. The device 10 floated on the molten steel and maintained an immersion depth of approximately 38.1 centimeters, which was close to 34,925 centimeters. At the termination of the test, the device 10 was examined and the following results were achieved: i) the unmelted portion of the metal shield 26 coincided with the non-submerged part of the device 10, as expected; I) in the non-submerged part of the device 10, the refractory case 14 was not oxidized, as expected; and iii) the dissolution of the refractory case 14 in contact with the slag layer was about four times less than that which is usually observed using the same refractory case in a fixed, non-floating position. This shows that the floating device 10 not only increases the oxidation resistance of the refractory case 14 above the liquid line, but also reduces the slag corrosion of the refractory case 14. This protection against corrosion can be explained by the fact that the absence of oxidation of the refractory case 14 in the liquid line prevents the loss of carbon from the case 14, and hence avoids the creation of pores, whereby the penetration of slag into the case 14 is reduced. Additionally, the absence of significant immersion depth variation in the case 14, because it floats at a relatively constant immersion depth, reduces the thermal cycles, in the region of the liquid line, for which the case 14 is exposed (typically the atmosphere above the line or level of liquid in the pot is less than 1000 ° C). In this way the case 14 experiences reduced thermal shock compared to a non-floating, fixed device, whereby the formation of micro cracks on the surface of the case 14 is reduced so that the penetration of slag is reduced. With further reference to Figure 4, to the extent that the same parts appear in Figure 3, the same integers are used. Thus, the device 1 0 is held vertically disposed in the molten steel 12 in the pot by the tubular guide 44 which is mounted on the cover 48 of the pot.

An alumina mortar 52 was arranged in space 32 between the refractory shield 14 and the metal shield 26 in an upper region. A steel extension 34 supports a thermocouple element 54. The extension 34 extends from a plug 56. The metal shield 26 is made of steel 316, has an internal diameter of 7 cm and a thickness of 0.3175 cm. The guide 44 is made of steel 316 as well and has an internal diameter of 8.03 cm and a thickness of 0.635 cm, the shock absorber 40 has a length of 17.78 cm. The refractory case 14 has a length of 76.2 cm and an external diameter of 6.8 cm. The guide 44 has a vertical length of 15.24 cm below the cover 48. The device 10 has a depth of immersion below the level of molten metal of 35 cm. Space 32 has a width of 1 mm; the roof 30 is 12.7 cm below the steel plug 56 which is 316 steel and has a thickness of 0.635 cm and a diameter of 9.3 cm. A space of 2 mm is defined between the guide 44 and the metal shield 26.

Claims (15)

1. REVIVAL DICATIONS 1. A floating device for supporting a temperature sensor within the interior of a liquid comprising: a case having an interior cavity extending from an open end to a closed end for receiving the temperature sensor, said device floating in the liquid with said closed end immersed in the liquid and being disposed at a predetermined distance below the upper surface of the liquid in which the device floats. A device according to claim 1 wherein the temperature sensor comprises a thermocouple conductor, and the case comprises a refractory housing. A device according to claim 2 further comprising: i) an outer protective shield surrounding at least the open end of said refractory housing, said shield being a metallic shield that dissolves or melts when immersed in liquid; ii) said device floating in the liquid with said open end of said refractory housing extending above the upper surface of the liquid, and said closed end of said refractory housing that is submerged in the liquid, and with said external protective shield protecting said open end of said refractory housing from an environment above the liquid; and iii) said refractory housing that isolates the thermocouple conductor from the liquid. 4. A temperature sensor assembly for determining the temperature of a liquid comprising: a) a temperature sensor; b) a floating device that houses the temperature sensor to support the sensor within the interior of the liquid, said device comprising a case having an interior cavity extending from an open end to a closed end, said temperature sensor being housed within said cavity, said device floating in the liquid with said closed end immersed in the liquid, the closed end being disposed at a predetermined distance below the upper surface of the liquid in which the device floats, the sensor being disposed to a predetermined distance below the upper surface of the liquid. An assembly according to claim 4 wherein the temperature sensor is a thermocouple comprising a hot thermocouple element and a cold thermocouple element and means for determining a potential difference between said elements. 6. An assembly according to claim 5 wherein said case comprises a refractory housing. An assembly according to claim 6 further comprising: i) an outer metallic shield surrounding at least the open end of said refractory housing, said metallic shield that dissolves or melts when immersed in the liquid; ii) said device floating in the liquid with said open end of said refractory housing extending above the surface of the liquid, and said lower end of said refractory housing being submerged in the liquid, and with said external protective shield protecting said open end of said refractory housing of an environment above the surface of the liquid; and iii) said refractory housing that isolates the hot thermocouple element from the liquid. 8. A method for determining the temperature of a liquid comprising: providing a liquid bath having a top surface; - floating, in said liquid a device according to claim 1 supporting a temperature sensor; - allow the temperature of the sensor to adjust in response to the temperature of the liquid; and - determining the temperature of the fluid; whereby the temperature is determined at a selected distance below said upper surface. 9. A method according to claim 8 wherein said liquid is a molten metal. 10. A method for monitoring the temperature of a liquid comprising: providing a thermocouple assembly having a hot thermocouple element, a cold thermocouple element; - isolating said hot thermocouple element within an interior cavity of a refractory housing having an open end and a closed end, at least said open end which is surrounded by an external protective shield, said refractory housing and said outer protective shield defining a flotation device; - floating said device in said liquid with said closed end of said refractory housing that is submerged in said liquid and said open end extending above the upper surface of the liquid so that said external protective shield 'protects said open end of an environment above the surface of the liquid; - allow the temperature of the hot element of the thermocouple to adjust in response to the temperature of the surrounding liquid; and - measuring the potential difference between said hot and cold elements at the cold end of the conductors thereof and determining the temperature of the liquid therefrom, whereby the temperature is determined at a selected distance below said temperature. upper surface. eleven . A method according to claim 10 wherein said liquid is a molten metal. 12. A device according to claim 1 wherein the kit comprises AI2O3 / C, MgO / C, ZrO2 / C, CaO, SiO2, AlN, SiC, Si3N4, C and mixtures thereof. 13. An assembly according to claim 4 wherein the kit comprises AI2O3 / C, MgO / C, ZrO2 / C, CaO, SiO2, AlN, SiC, Si3N4, C and mixtures thereof. 14. A device according to claim 12 wherein the kit comprises AI2O3 / C, MgO / C, or ZrO2 / C. 15. An assembly according to claim 13 wherein the kit comprises AI2O3 / C. MgO / C or ZrO2 / C.