Temperature measuring tube and temperature measuring method

Abstract

To provide a temperature measurement tube capable of surely measuring the in-furnace temperature of heat treatment equipment for a long time.SOLUTION: A temperature measurement tube comprises: a graphite tube at least a part of which is arranged in a furnace; a first cap 112 which seals one end of the graphite tube; a second cap 122 which is provided at the other end of the graphite tube and has an opening which serves as an observation window; and a transparent plate 123 which seals the observation window. A radiation thermometer 300 measures via the transparent plate 123, the temperature of the first cap 112 located at a measuring position in the furnace. The graphite tube comprises a gas blowing hole 121a for blowing the inert gas into the inside of the graphite tube, and the inert gas is blown into the inside of the graphite tube to create positive pressure inside the graphite tube graphite tube.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a temperature measuring tube used for measuring the temperature inside a heat treatment furnace and a temperature measuring method using this temperature measuring tube.

Background Art

[0002] As heat treatment apparatuses used for heat treatment of carbon materials, ceramic materials, etc., high-temperature heating furnaces such as resistance furnaces, induction furnaces, arc furnaces, and plasma furnaces are known. Generally, when the heat treatment temperature of a material is 2000°C or higher, the temperature inside the furnace is measured by a non-contact thermometer such as a radiation thermometer, a brightness thermometer, or a two-color thermometer. For example, when measuring the temperature inside a Tamman furnace, which is a type of resistance furnace, by providing a viewing window leading to the inside of the furnace core, the temperature inside the furnace can be measured with a radiation thermometer through this viewing window.

[0003] The Tamman furnace is a relatively small-scale heat treatment apparatus, but as a relatively large-scale heat treatment apparatus for mass production, an indirectly heated Acheson furnace and a directly heated LWG furnace are known. Also, as continuous heat treatment furnaces, horizontal types as shown in Patent Document 1 and vertical types as shown in Patent Documents 2 and 3 have been proposed. In these heat treatment apparatuses as well, by providing a viewing window in the furnace shell, the temperature can be measured using a radiation thermometer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, when using a radiation thermometer, it is necessary to ensure that there are no effects from radiation absorption or scattering in the optical path, and that nothing other than the object being measured is within the field of view of the radiation thermometer. In the case of relatively small-scale heat treatment equipment used in experimental apparatus and test plants, furnace control, such as creating a vacuum inside the furnace or creating an inert atmosphere inside the furnace, is easy, and because the distance from the viewing window to the object being measured is short, problems such as absorption or scattering of radiation by gases generated from the material or furnace walls during heat treatment are less likely to occur.

[0006] However, in relatively large-scale heat treatment equipment used for mass production, controlling the atmosphere inside the furnace is difficult, and the optical path from the viewing window to the object being measured is long. As a result, it is not possible to sufficiently suppress the effects of radiation absorption and scattering by gases generated inside the furnace, and there is a risk that temperature measurements using radiation thermometers may not be successful. In particular, in the case of Acheson furnaces, since the system uses packing coke such as coke breeze to conduct electricity, it is difficult to even install a viewing window.

[0007] The present invention aims to solve the above problems by providing a thermometer used for measuring the temperature inside a furnace of a heat treatment apparatus. [Means for solving the problem]

[0008] The thermometer tube of the present invention has the following configuration. (1) A temperature measuring tube inserted into the inside of a heat treatment apparatus in order to measure the temperature inside the furnace of the heat treatment apparatus using a radiation thermometer. (2) The apparatus comprises a graphite tube, of which at least a portion is placed inside the furnace; a first cap that seals one end of the graphite tube; a second cap provided at the other end of the graphite tube and having an opening that serves as a viewing window; and a transparent plate that seals the viewing window. (3) The radiation thermometer measures the temperature of the first cap located at the measurement position inside the furnace through the transparent plate. (4) The graphite tube is equipped with a gas injection hole for blowing an inert gas into the inside of the graphite tube, and the inside of the graphite tube is under positive pressure due to the inert gas being blown in.

[0009] The thermometer tube of the present invention may further have the following configuration. (1) The graphite tube consists of a first graphite tube, at least a part of which is placed inside the furnace, and a second graphite tube, which is placed outside the furnace. The first cap seals one end of the first graphite tube, and the other end of the first graphite tube and one end of the second graphite tube are connected to each other. The second cap is provided on the other end of the second graphite tube. The first cap and the first graphite tube are detachable from each other. The first graphite tube and the second graphite tube are detachable from each other. The second graphite tube and the second cap are detachable from each other.

[0010] Furthermore, the thermometer tube of the present invention has the following configuration. (1) A temperature measuring tube inserted into the inside of a heat treatment apparatus in order to measure the temperature inside the furnace of the heat treatment apparatus using a radiation thermometer. (2) The apparatus comprises a graphite tube, at least a portion of which is placed inside the furnace; a connecting pipe connected to one end of the graphite tube; another graphite tube connected to the connecting pipe and extending out of the furnace from the connecting pipe; a first cap sealing one end of the other graphite tube; a second cap provided at the other end of the graphite tube and having an opening that serves as a viewing window; and a transparent plate sealing the viewing window. (3) The radiation thermometer measures the temperature of the connecting pipe located at the measurement position inside the furnace through the transparent plate. (4) The graphite tube is equipped with a gas injection hole for blowing in an inert gas into the inside of the graphite tube, and the inside of the graphite tube, the connecting pipe and the other graphite tubes are under positive pressure due to the inert gas being blown in.

[0011] The temperature measurement method of the present invention has the following configuration. (1) This is a temperature measurement method that measures the temperature inside the furnace of a heat treatment device using a temperature sensing tube. (2) Insert the temperature measuring tube into the heat treatment apparatus, and position a cap for sealing one end of the temperature measuring tube at the measurement position inside the furnace. (3) Blow an inert gas into the temperature measuring tube so that the inside of the temperature measuring tube becomes a positive pressure. (4) Measure the temperature of the cap with a radiation thermometer through a transparent plate provided at the other end of the temperature measuring tube. [Advantages of the Invention]

[0012] According to the present invention, the temperature inside the furnace of the heat treatment apparatus can be reliably measured over a long period of time. [Brief Description of the Drawings]

[0013] [Figure 1] Cross-sectional view showing a temperature measuring tube according to the first embodiment. [Figure 2] Cross-sectional view showing a temperature measuring tube according to another embodiment. [Embodiments for Carrying Out the Invention]

[0014] [1. First Embodiment] [Configuration] [Temperature Measuring Tube] The temperature measuring tube 100 will be described while referring to FIG. 1. The temperature measuring tube 100 includes a first graphite tube 111, a first cap 112 provided at one end of the first graphite tube 111, a second graphite tube 121 having one end connected to the other end of the first graphite tube 111, and a second cap 122 provided at the other end of the second graphite tube 121.

[0015] The first graphite tube 111 is, for example, made by processing a material made of artificial graphite into a cylindrical shape. Thread grooves are cut on the outer sides of both ends of the first graphite tube 111. One end meshes with the thread groove cut on the inner side of the first cap 112, and the other end meshes with the thread groove cut on the inner side of one end of the second graphite tube 121, and they are detachably fixed to each other. The first cap 112 is made of, for example, a material made of artificial graphite, is cylindrical with a bottom surface for sealing one end of the first graphite tube 111, and has a thread groove cut on the inner side that meshes with the thread groove cut on one end of the first graphite tube 111.

[0016] The second graphite tube 121 is, like the first graphite tube 111, for example, made by processing a material made of artificial graphite into a cylindrical shape. A thread groove that meshes with the thread groove cut on the other end of the first graphite tube 111 is cut on the inner side of one end of the second graphite tube 121. On the other hand, a thread groove is cut on the outer side rather than the inner side of the other end of the second graphite tube 121. This thread groove meshes with the thread groove cut on the inner side of the second cap 122 and they are detachably fixed to each other.

[0017] The second cap 122 is made of, for example, a material made of artificial graphite, is cylindrical with a bottom surface, and has a thread groove cut on the inner side that meshes with the thread groove cut on the other end of the second graphite tube 121. A viewing window that opens concentrically with the bottom surface is provided on the bottom surface of the second cap 122. This viewing window is sealed from the inside by a transparent plate 123 such as quartz glass. In other words, the transparent plate 123 is fitted inside the second cap 122 and is sandwiched between the second cap 122 and the second graphite tube 121. Also, a cooling device (not shown) is provided near the second graphite tube 121 and the second cap 122, and the second graphite tube 121 and the second cap 122 are constantly cooled by the cooling water circulating inside this cooling device.

[0018] A gas injection hole 121a is opened on the side of the second graphite tube 121. Through this gas injection hole 121a, an inert gas such as argon gas or nitrogen gas is injected from the outside into the second graphite tube 121 and the first graphite tube 111. This inert gas constantly applies pressure to the inside of the second graphite tube 121 and the first graphite tube 111. It is thought that the gas injected into the inside of the second graphite tube 121 and the first graphite tube 111 leaks out to the outside of the temperature measuring tube 100 through the small gaps in the joints of the temperature measuring tube 100 and through the countless pores in the graphite material.

[0019] [Heat treatment equipment] Referring to Figure 1, a heat treatment apparatus 200 in which the temperature inside the furnace is measured by a temperature measuring tube 100 will be described. In the heat treatment apparatus 200, the inside of the furnace, which becomes hot during heat treatment, is covered by a furnace shell 210 and a furnace wall 220 made of refractory material such as refractory bricks, which is provided inside the furnace shell 210. That is, the inside of the furnace refers to the space inside the furnace wall 220 in the heat treatment apparatus 200. The furnace shell 210 and the furnace wall 220 are provided with openings into which the temperature measuring tube 100 is inserted. In the gap between this opening and the temperature measuring tube 100 inserted into the opening, refractory material 230, such as refractory fiber or refractory castable, is embedded to fix the temperature measuring tube 100 in place.

[0020] A heat-treated object 240 is located inside the furnace. A measurement position for measuring the furnace temperature is set outside the heat-treated object 240, at an arbitrary distance. When the temperature-sensing tube 100 is inserted into the heat treatment apparatus 200, the first cap 112 is positioned at this measurement position.

[0021] The inside of the furnace, that is, the inside of the furnace wall 220, is filled with an insulating material such as carbon black. In addition, the area around the heat-treated object 240 placed inside the furnace is filled with a packing material such as coke breeze. In other words, the temperature sensing tube 100 inserted into the furnace wall 220 is embedded in the insulating material, and the heat-treated object 240 is embedded in the packing material.

[0022] [Radiation thermometer] A radiation thermometer 300 is provided at a position opposite the viewing window of the second cap 122. The radiation thermometer 300 measures the temperature of the first cap 112 with the temperature measuring tube 100 inserted into the furnace through this viewing window. In other words, the radiation thermometer 300 does not directly measure the furnace temperature, but measures the furnace temperature at the position of the first cap 112. To put it another way, the first cap 112 is the component whose temperature is measured in this embodiment.

[0023] [Effect] A method for measuring the furnace temperature of a heat treatment apparatus 200 using a thermometer 100 and a radiation thermometer 300 will be described. When measuring the furnace temperature, the first cap 112 side of the thermometer 100 is inserted into the internal space of the heat treatment apparatus 200 through an opening provided in the furnace shell 210 and furnace wall 220 of the heat treatment apparatus 200. This positions the first cap 112 at the measurement position inside the furnace. To prevent the first cap 112 from shifting at the measurement position, the thermometer 100 is fixed to the opening in the furnace shell 210 and furnace wall 220 by refractory material 230. At this time, the first cap 112 is inside the furnace, part of the first graphite tube 111 is inside the furnace, and the second graphite tube 121 and the second cap 122 are outside the furnace.

[0024] With the temperature measuring tube 100 fixed to the heat treatment apparatus 200, an inert gas is blown into the temperature measuring tube 100 from the gas injection hole 121a. In this state, a radiation thermometer 300 is positioned opposite the viewing window of the second cap 122. The radiation thermometer 300 measures the temperature of the first cap 112 through a transparent plate 123 provided in the viewing window. This allows the furnace temperature of the heat treatment apparatus 200 to be measured directly.

[0025] [effect] (1) In this embodiment, a gas injection hole 121a is opened on the side of the second graphite tube 121 of the temperature sensing tube 100, and an inert gas is injected into the inside of the temperature sensing tube 100 through this gas injection hole 121a. As a result, the inside of the temperature sensing tube 100 is always under positive pressure, preventing furnace-generated gas from entering the inside of the temperature sensing tube 100, and thus suppressing the effects of radiation absorption and scattering in the optical path of the radiation thermometer 300. Therefore, the furnace temperature can be measured reliably.

[0026] Furthermore, while oxidation and wear of the temperature sensing tube 100 are unavoidable due to oxygen present in the furnace and gases generated from the materials and furnace walls during heat treatment, inert gases leak out from the joints and numerous pores within the temperature sensing tube 100. Therefore, even in furnaces where the temperature exceeds 2000°C, the progression of oxidation and wear of the temperature sensing tube 100 can be slowed down. Consequently, the furnace temperature can be measured over a long period of time.

[0027] (2) The temperature sensing tube 100 experiences different degrees of oxidation and wear due to the difference in ambient temperature between the portion located inside the furnace and the portion located outside the furnace. Specifically, the first graphite tube 111 and the first cap 112, of which at least a portion is located inside the furnace, are repeatedly exposed to high temperatures, and therefore deteriorate and undergo oxidation and wear more rapidly with repeated use compared to the second graphite tube 121 and the second cap 122, which are located outside the furnace. Therefore, the first graphite tube 111, the first cap 112, the second graphite tube 121, and the second cap 122 of the temperature sensing tube 100 in this embodiment are fixed to each other so that they can be attached and detached. This makes it economical as only the deteriorated or oxidized parts can be replaced.

[0028] (3) The second graphite tube 121 and the second cap 122 are cooled by a cooling device (not shown). This prevents oxidative wear of the second graphite tube 121 and the second cap 122, and also prevents heat from being radiated to the radiation thermometer 300, thereby reducing the risk of the radiation thermometer 300 malfunctioning.

[0029] (4) If an insulating material such as alumina castable is used as the refractory material 230, the temperature sensing tube 100 in this embodiment will be insulated from the furnace shell 210 and the furnace wall 220. In other words, the temperature sensing tube 100 is insulated from the heat treatment apparatus 200. This prevents unexpected bypass currents and leakage currents, and ensures the operational stability and safety of the heat treatment apparatus 200.

[0030] (5) Since the radiation thermometer 300 is a separate component from the temperature sensing tube 100, even if the optical path of the radiation thermometer 300 is shifted relative to the measurement position due to expansion of the temperature sensing tube 100 or the heat treatment device 200 during heat treatment, it can be easily corrected.

[0031] [2. Other Embodiments] The present invention is not limited to the embodiments described above, and the components can be modified and implemented in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriate combinations of the multiple components disclosed in the embodiments described above. For example, some components may be deleted from all the components shown in the embodiments. Specifically, the invention also includes the following other embodiments.

[0032] (1) The temperature sensing tube 100 in the first embodiment is arranged horizontally as shown in Figure 1, but is not limited to this. For example, as shown in Figure 2, it may be arranged at an angle so as to be inserted into the heat treatment apparatus 200 from diagonally above. Below, only the differences from the first embodiment will be described. Note that the heat treatment apparatus 200 in Figure 2 is an example of a horizontal Acheson furnace. Therefore, the heat treatment apparatus 200 in Figure 2 does not have a furnace shell 210, furnace walls 220, or refractory material 230, but is a container made of refractory material such as brick. This container is filled with a packing material such as coke, and a part of the temperature sensing tube 100 and the heat treatment object 240 are embedded in it.

[0033] In this embodiment, multiple first temperature measuring tubes 111 are provided because the distance to the measurement position is long. The multiple first temperature measuring tubes 111 are fixed to each other so as to be detachable by screw grooves or the like. A first cap 112 is not provided; instead, a V-shaped connecting pipe 132 is connected. The connecting pipe 132 is made of, for example, an artificial graphite material. The other end of the connecting pipe 132 is connected to a third graphite tube 131 that extends upward and protrudes outside the furnace. The third graphite tube 131 is porous, similar to the first graphite tube 111 and the second graphite tube 121. In this embodiment, the third graphite tube 131 is composed of multiple third graphite tubes 131, similar to the first temperature measuring tube 111. The other end of the third graphite tube is open, and therefore the inert gas blown in from the gas injection hole 121a escapes to the outside of the furnace through the opening at the other end of the third graphite tube 131 via the first temperature measuring tube 111 and the connecting pipe 132. In the first embodiment, if the first cap 112 provided at one end of the first temperature measuring tube 111 had an opening, there was a risk of furnace-generated gas flowing in through this opening, but in this embodiment there is no such risk, hence this configuration. Furthermore, by creating a gas passage, even if furnace-generated gas enters the inside of the temperature measuring tube 100, it can be escaped to the outside of the furnace through the opening at the other end of the third graphite tube 131 along with the inert gas. Note that, as in the first embodiment, the opening at the other end of the third graphite tube 131 may be sealed with a cap.

[0034] In this embodiment, the radiation thermometer 300 can measure the temperature inside the furnace by measuring the temperature of the connecting pipe 132 of the temperature measuring tube 100. In other words, the connecting pipe 132 is the component whose temperature is measured in this embodiment. This embodiment is an example in which the temperature measuring tube 100 of the first embodiment is applied to a horizontal heat treatment apparatus 200.

[0035] (2) Instead of the radiation thermometer 300 of the first embodiment, other non-contact thermometers such as two-color thermometers may be used.

[0036] (3) In the first embodiment, each component of the temperature measuring tube 100 is detachable by screw threads, but some parts may be fitted together. In this case as well, some parts can be made detachable.

[0037] (4) In the first embodiment, one end of the temperature measuring tube 100 is sealed with the first cap 112, but it is also possible to provide an opening in the first cap 112 if measures are taken to increase the amount of inert gas flowing in to prevent the inflow of gas generated in the furnace.

[0038] (5) The heat treatment apparatus 200 that is the target of measurement by the temperature measuring tube 100 of the first embodiment is not limited to a vertical type, but may also be horizontal. Furthermore, the temperature measuring tube 100 of the first embodiment may be inserted diagonally into the heat treatment apparatus 200 to measure the temperature without using the V-shaped connecting pipe 132 and the third graphite tube 131. [Explanation of Symbols]

[0039] 100 Temperature tube 111 First graphite tube 112 First Cap 121 Second graphite tube 122 Second cap 121a Gas injection port 123 Transparent plate 131 The third graphite tube 132 Connecting pipes 200 Heat treatment equipment 210 Furnace shell 220 Furnace wall 230 Fireproof materials 240 Heat-treated items 300 radiation thermometer

Claims

1. A thermometer tube inserted into the interior of a heat treatment apparatus to measure the temperature inside the furnace of the heat treatment apparatus using a radiation thermometer, At least a portion of them are graphite tubes placed inside the furnace, A first cap that seals one end of the graphite tube, A second cap is provided at the other end of the graphite tube and has an opening that serves as a viewing window, A transparent plate that seals the aforementioned viewing window, Equipped with, The radiation thermometer measures the temperature of the first cap located at the measurement position inside the furnace through the transparent plate. The graphite tube consists of a first graphite tube, at least a portion of which is placed inside the furnace, and a second graphite tube, which is placed outside the furnace. The first graphite tube and the second graphite tube are connected to each other and are configured to be detachable. The portion of the first graphite tube located outside the furnace is provided with a gas injection hole for blowing inert gas cooled outside the graphite tube into the inside of the graphite tube. When the inert gas is blown into the first graphite tube through the gas injection hole, the inside of the graphite tube is constantly maintained at positive pressure by the inert gas from the gas injection hole, and the first graphite tube, including the first cap portion inside the furnace, is cooled by the inert gas. A temperature measuring tube characterized by preventing furnace atmosphere gas from entering the graphite tube while suppressing the temperature rise of the component to be measured.

2. The first cap seals one end of the first graphite tube, The other end of the first graphite tube and one end of the second graphite tube are connected to each other. The second cap is provided at the other end of the second graphite tube. The first cap and the first graphite tube are detachable from each other. The first graphite tube and the second graphite tube are detachable from each other. The second graphite tube and the second cap are detachable from each other. A thermometer tube according to claim 1.

3. A method for measuring the temperature inside a furnace of a heat treatment apparatus using a thermometer tube as described in claim 1, The steps include inserting the temperature measuring tube into the heat treatment apparatus and positioning the temperature measurement target member provided on the temperature measuring tube at the measurement position inside the furnace, The process involves blowing inert gas, cooled outside the graphite tube, into the first graphite tube from a gas injection hole located outside the furnace of the first graphite tube, so that the inside of the temperature measuring tube becomes positive pressure, The process of allowing the inert gas inside the graphite tube to leak out of the graphite tube through pores provided in the graphite tube, The process of measuring the temperature of the component to be measured using a radiation thermometer through a transparent plate provided at the outer end of the temperature measuring tube, A temperature measurement method comprising the following features.

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