JP4004053B2 - Sheath type thermocouple - Google Patents

Description

  The present invention relates to a sheath type thermocouple used in a heavy oil boiler or an incinerator.

  A conventional sheathed thermocouple is shown in FIGS.

101 is a metal sheath, 102 is an inorganic insulating material such as magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), 103 is a (+) side thermocouple core wire, 104 is a (−) side thermocouple core wire, 105 Is a seal made of an epoxy resin or the like for preventing moisture from entering the inorganic insulating material 102 to deteriorate the insulation. The terminal portion of 105 may further be provided with a sleeve that accommodates the connection portion between the thermocouple element and the compensation conductor, and a terminal box that accommodates a terminal block for connection with the compensation conductor. Reference numeral 113 denotes a temperature sensing unit.

  As for the thermocouple core wire, for example, in the K thermocouple, an alloy mainly composed of nickel and chromium is used for the (+) side thermocouple core wire, and an alloy mainly composed of nickel is used for the (−) side thermocouple core wire.

  Conventionally, when this sheath type thermocouple is used in a high temperature atmosphere exceeding 800 ° C., as a sheath material, Hastelloy X (a metal material name of Haynes International Co., Ltd.) having excellent strength and oxidation resistance at high temperature, SUH446, etc. However, when used in a high-temperature atmosphere of 800 ° C or higher in a heavy oil combustion furnace such as a heavy oil boiler or a garbage incinerator, the sheath is sheathed by high-temperature corrosion called vanadium attack by vanadium contained in heavy oil. In the short case, the sheath breaks within a few months, and there is a problem that a measurement error occurs due to insulation deterioration of the insulating material.

Specific examples of use of the sheath type thermocouple for measuring the surface temperature of piping or the like in a heavy oil boiler or an incinerator are shown in FIGS. 106 is a sheath type thermocouple shown in FIGS. 3 and 4, 107 is a terminal box, 108 is a pad welded to the pipe, and a temperature sensing portion at the tip of the thermocouple is inserted into the pad 108. Reference numeral 109 denotes a sheath type thermocouple fastener, and 110 denotes a pipe to be measured. Since the sheath material of the sheath type thermocouple is exposed to a high-temperature combustion atmosphere, the heat-resistant and corrosion-resistant alloy called Hastelloy X is used. However, due to the vanadium attack contained in heavy oil, the sheath will only break for a few months at most.
JP 2002-005749 A

  Hastelloy X and SUH446, which have excellent strength and oxidation resistance at high temperatures, are used as the sheath material for high temperature sheathed thermocouples. These sheathed thermocouples are used in heavy oil boilers, garbage incinerators, etc. When used in a high-temperature atmosphere where heavy oil combustion is performed, the sheath is eroded by high-temperature corrosion called vanadium attack by vanadium contained in heavy oil, and the sheath is damaged in a short period of time, resulting in measurement errors due to insulation deterioration of the insulating material. There is a problem, and there is a need for a sheathed thermocouple that is sound for a long time and does not cause measurement errors even when used in such an atmosphere.

  The present invention relates to a sheath-type thermocouple in which a thermocouple core wire is accommodated by interposing an inorganic insulating material in a metal sheath, even if it is used in a high-temperature atmosphere where heavy oil combustion is performed such as a heavy oil boiler or an incinerator. A sheath type thermocouple in which a sheath is a double tube and an outer sheath material is made of HR160 (a metal material name of Haynes International) and an inner sheath is made of SUS310S. did.

  Further, according to the present invention, in a sheath type thermocouple in which a thermocouple core wire is accommodated by interposing an inorganic insulating material in a metal sheath, the sheath is a double tube, the outer sheath is HR160, the inner sheath is SUS316, SUS304. Or it was set as the sheath type | mold thermocouple manufactured by NCF600.

  HR160 (a metal material name of Haynes International) is a high-temperature-resistant material having excellent strength and oxidation resistance even in a high-temperature atmosphere. This is a sheath-type thermoelectric having a conventional structure shown in FIGS. When used as a pair of sheath materials, measurement errors occur in a short period of time when used in a high temperature atmosphere. This is the reason why HR160 has not been used as a sheath material for a sheath type thermocouple for high temperature. When analysis was conducted to investigate the cause of the error, the component of HR160, which is the sheath material, evaporated and diffused due to the high temperature and adhered to the thermocouple core wire and reacted, and this caused the thermoelectromotive force of the thermocouple core wire. The change was the cause of error.

  On the other hand, even when a thermocouple using HR160 as a sheath material is used in a high-temperature atmosphere in a furnace in which heavy oil burns, the sheath is less than a conventional thermocouple made of Hastelloy X or SUH446. It was rarely eroded by the vanadium attack, and the function of the sheath as a boundary wall against the external atmosphere was sound for a long time.

  In the present invention, a sheath type thermocouple in which a thermocouple core wire is accommodated by interposing an inorganic insulating material in a metal sheath, the sheath is a double tube, the outer sheath is made of HR160, and the inner sheath is made of SUS310S. As a sheath-type thermocouple, the outer HR160 sheath is less likely to be eroded by vanadium attack even when used in high-temperature atmospheres where heavy oil combustion is performed, such as heavy oil boilers and incinerators. Since the inner sheath is provided, the evaporation component at a high temperature of HR160 does not diffuse into the inner sheath more than the inner sheath. Therefore, the diffusion component of HR160 and the thermocouple core wire react with each other. Measurement error will not occur.

  Further, the SUS310S of the inner sheath does not react even if the evaporation component diffuses and adheres to the thermocouple core wire at a high temperature, and no measurement error occurs due to the adhesion.

  As described above, since the sheath is a double tube, the outer sheath uses HR160 which is strong against vanadium attack, and the inner sheath uses SUS310S, the sheath can be damaged even if used in a high temperature atmosphere where heavy oil combustion is performed for a long time. It was possible to obtain a sheath-type thermocouple that is sound and has no measurement error.

  Further, according to the present invention, in a sheath type thermocouple in which a thermocouple core wire is accommodated by interposing an inorganic insulating material in a metal sheath, the sheath is a double tube, the outer sheath is HR160, and the inner sheath is SUS316, SUS304 or A sheath-type thermocouple made of NCF600 was used. Similar to SUS310S, these inner sheaths do not react even if their evaporated components diffuse and adhere to the thermocouple core wire at high temperatures, and do not cause measurement errors due to adhesion. Even if it was used, the sheath was healthy without being damaged, and a sheath-type thermocouple free from measurement errors could be obtained.

  A sheathed thermocouple according to the present invention is shown in FIGS.

  In the sheath type thermocouple of the present invention, the sheath is a double tube, the material of the outer sheath 11 is HR160, and the material of the inner sheath 12 is SUS310S.

2 is an inorganic insulating material such as magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), 3 is a (+) side thermocouple core wire, 4 is a (−) side thermocouple core wire, and 5 is moisture to the inorganic insulating material. It is a seal made of epoxy resin or the like for preventing penetration and deterioration of insulation. Reference numeral 13 denotes a temperature sensitive part.

  The sheath 101 of the sheath-type thermocouple of FIGS. 3 and 4 is set to HR160, and the thermocouple core wires 103 and 104 are inserted into the sheath 101 so that the inorganic insulating material 102 is hardly filled with magnesia powder and insulated. At high temperature, the metal vapor of HR160 diffuses into the thermocouple core wires 103 and 104 via the gaps between the magnesia powder particles, which are inorganic insulators, and the thermoelectromotive force is distorted.

  In order to prevent this, as shown in FIGS. 1 and 2, the sheath is doubled, the outer sheath 11 is made of HR160, and the inner sheath 12 is made of SUS310S. 4 can be prevented from diffusing.

  Further, even if the SUS310S component of the inner sheath 12 diffuses and adheres to the thermocouple core wire, it does not react and no measurement error occurs.

  Incidentally, in the case of a sheath type thermocouple for measuring the surface temperature of piping or the like in a heavy oil boiler or an incinerator, conventional specific examples are shown in FIGS. 5 and 6. Here, the double tube sheath thermocouple according to the present invention is used. Even if it is used, the configuration of FIG. 5 does not change, and the internal configuration of the sheath type thermocouple 106 and the sheath material in the drawing only change as described above.

  The sheath type thermocouple shown in FIG. 1 and FIG. 2 is a high temperature sheath type thermocouple that uses conventional Hastelloy X, SUH446, etc. as a single sheath material even when used in a high temperature atmosphere in a furnace where the heavy oil burns. It was confirmed that the sheath was alive for a long period of time compared to the pair, and the measurement accuracy was not degraded.

  Hereinafter, this effect will be described.

  HR160 is a high temperature resistant material having excellent strength and oxidation resistance even in a high temperature atmosphere, but when this is used as a sheath material of a sheath type thermocouple having a conventional structure shown in FIGS. When used in a high temperature atmosphere, measurement errors occur in a short period of time. This is the reason why HR160 has not been used as a sheath material for a sheath type thermocouple for high temperature. When an analysis was conducted to investigate the cause of the error, the component of HR160, which is the sheath material, evaporated and diffused due to high temperature and adhered to and reacted with the thermocouple core wire, which changed the thermoelectromotive force of the thermocouple core wire. It was found that there was an error.

  On the other hand, even when a thermocouple using HR160 as a sheath material is used in a high-temperature atmosphere in a furnace in which heavy oil burns, the sheath is less than a conventional thermocouple made of Hastelloy X or SUH446. It was rarely eroded and the sheath was healthy for a long time.

  Accordingly, in the sheath type thermocouple using HR160 as a sheath material, the HR160 prevents the penetration of the HR160 into the sheath, so that the sheath can be used for a long time even when used in a high temperature atmosphere in a furnace where heavy oil burns. Was found to be sound and without any decrease in measurement accuracy.

  Based on the above, the sheath-type thermocouple of the present invention shown in FIG. 1 and FIG. 2 has an outer sheath material HR160, and a sheath made of SUS310S is provided on the inner side to prevent intrusion into the sheath material. Is doubled. The reason why SUS310S is used is that the evaporation component at high temperature of HR160 diffuses and adheres to the thermocouple core wire, so that no reaction occurs and no measurement error occurs. SUS316, SUS304, or NCF600 having the same properties as SUS310S may be used as the material of the inner sheath. Secondary, like these HR160 outer sheaths, these inner sheaths also serve as boundary walls for the external atmosphere. That is, even when the outer sheath of the HR 160 is broken, the measurement can be continued normally if the sealing property of the inner sheath with respect to the external atmosphere, that is, the function as the boundary wall is sound. Although it is possible to use Hastelloy X or SUH446 that does not cause a measurement error even if it adheres to the thermocouple core wire on the inner sheath, this is an expensive material, so there is no advantage of adopting it.

  With such a configuration, a sheath-type thermocouple that has a healthy sheath for a long period of time and does not deteriorate in measurement accuracy even when used in a high-temperature atmosphere in a furnace where heavy oil burns is realized.

  In actual use in the high-temperature atmosphere in which heavy oil burns, the sheath thermocouple with the outer sheath material HR160 and the inner sheath material SUS310S is compared to the conventional high-temperature sheathed thermocouple, For a long period of time, the sheath remains healthy and performs normal measurements.

  For example, in the use in an incinerator where heavy oil burns, the conventional single-sheath sheath using Hastelloy X has been damaged by vanadium attack in about two to three months, resulting in measurement errors. As for the thing, even if it uses for one year, both double sheaths are healthy and continue normal measurement.

  The sheath type thermocouple of the present invention is used in a heavy oil boiler or an incinerator, but the sheath material evaporates and diffuses, adheres to and reacts with the thermocouple core wire, and the thermoelectromotive force of the thermocouple core wire changes to cause an error. Can be used at high temperatures.

It is a longitudinal cross-sectional view of the sheath type thermocouple of this invention. It is II-II sectional drawing of FIG. It is a longitudinal cross-sectional view of the conventional sheath type thermocouple. It is IV-IV sectional drawing of FIG. It is the top view which mounted | wore in order to measure the surface temperature to the piping of a heavy oil boiler or an incinerator with the conventional sheath type thermocouple. FIG. 6 is a side view of FIG. 5.

Explanation of symbols

2 ... Inorganic insulating material 11 ... Outer sheath 12 ... Inner sheath

Claims (2)

  A sheath type thermocouple in which a thermocouple core wire is accommodated by interposing an inorganic insulating material in a metal sheath, wherein the sheath is a double tube, the outer sheath is made of HR160, and the inner sheath is made of SUS310S. In a sheath type thermocouple in which a thermocouple core wire is accommodated by interposing an inorganic insulating material in a metal sheath, the sheath is a double tube, the outer sheath is made of HR160, and the inner sheath is made of SUS316, SUS304 or NCF600 Type thermocouple.

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