JPH0572050A - Accuracy controlling method for thermocouple thermometer - Google Patents

Abstract

PURPOSE:To establish a simple means which can secure high temperature measuring accuracy stably without causing the especially high cost in temperature measurement with a thermocouple thermometer. CONSTITUTION:A protecting pipe 14 housing the thermal contact point of a thermocouple is submerged and brought into contact with a test specimen 11. A displaying meter or a recorder 22 is connected to the cold contact point of the thermocouple through a conductor. When temperature measurement is performed with this thermocouple thermometer, the thermometer is arranged a cold contact part (terminal box 17), and the temperature of the cold contact part is controlled.

Description

Detailed Description of the Invention

The present invention relates to a quality control method for a thermocouple thermometer used to measure the temperature of a high temperature material such as molten metal.

[0002]

2. Description of the Related Art Conventionally, a thermocouple thermometer is generally used when continuously measuring the temperature of a high temperature material such as molten metal. For example, FIG. 3 shows a typical example of a thermocouple thermometer for continuously measuring the molten steel temperature in the tundish during continuous casting. The thermocouple thermometer is immersed in the molten steel 2 in the tundish 1. The protected contact tube 3 (generally made of alumina graphite refractory) accommodates the heat contact part of the thermocouple such as platinum-platinum rhodium (the thermocouple inside the protect tube is covered with an alumina ceramic tube for insulation). The display instrument or the recorder 5 is connected to the cold junction of the thermocouple via the lead wire 4. The connection between the cold junction of the thermocouple and the lead wire 4 is provided at the upper end of the protective tube 3.
The operation is performed in the terminal box 6, and the periphery of the terminal box 6 is cooled to room temperature by a cooling gas such as air, N ₂ gas or Ar gas in order to ensure temperature measurement accuracy.

However, in the thermocouple thermometer as described above, the temperature tends to change under the influence of the temperature of the material to be measured.
In order to keep the temperature of the minal box 6 (that is, the temperature of the cold junction) at a constant room temperature, it is necessary to change / adjust the amount of cooling gas to be fed, but the amount of feeding cannot be adjusted accurately. It has been pointed out that it is very difficult to stably secure high temperature measurement accuracy due to problems such as "forgetting to supply cooling gas" and "fluctuations in cooling gas pressure".

Therefore, a method has been proposed in which the cold junction of the thermocouple is rearranged from above the heat source (tundish, furnace, etc.) (Japanese Patent Laid-Open No. 62-28626). Since the thermocouple wire has to be lengthened as much as it is separated from the upper side of the heat source, the cost is increased and it cannot be said to be an industrially satisfactory means. However, if the above-mentioned extension is replaced with a thermocouple wire and a compensating lead wire having a relatively low price is substituted, the cost disadvantage is alleviated to some extent, but even if the connecting lead wire is a compensating lead wire, When the temperature rises above the temperature, it causes an error, and it cannot be said to be a practical measure.

In view of the above, the object of the present invention is to solve the above-mentioned problems pointed out in the thermocouple thermometer and to increase the cost significantly when measuring the temperature in the thermocouple thermometer. It was to establish a simple means that can stably ensure high temperature measurement accuracy without inviting.

[0006]

The present invention has been completed based on the results of research conducted by the inventors of the present invention, which have been earnestly conducted to achieve the above-mentioned object. When the tube is brought into contact with the temperature-measuring material, and the temperature is measured by a thermocouple thermometer comprising a display instrument (millivolt meter) or a recorder connected to the cold junction of the thermocouple via a conductor, It has a great feature in that a thermometer is provided in the cold junction portion and the temperature of the cold junction portion is controlled so that a high temperature measurement accuracy can be stably ensured. "

Hereinafter, the present invention will be described in more detail along with its operation and effects based on the embodiments. FIG. 1 is a schematic explanatory diagram of a situation in which the temperature measuring means according to the present invention is applied to “continuous temperature measurement of hot metal tapped from a blast furnace”, and FIG. 2 is a main part (thermometer) of a thermocouple thermometer used. Contact part and cold contact part).

In FIGS. 1 and 2, an alumina graphite refractory having a lower end supported by a support pipe 13 fixed to a skin cover 12 is attached to a "hot metal discharged from a blast furnace" 11 which is a temperature-measured material. The product protection tube 14 is immersed. The protection tube 14 is necessary to enable continuous temperature measurement of the hot metal by the thermocouple, and the protection tube 14 contains a platinum-platinum rhodium thermocouple 15. The thermocouple 15 is provided with a porcelain tube 16 made of alumina ceramics or the like to electrically insulate the thermocouple 15 from the protective tube 14 and the like. A terminal box 17 is attached to the upper end of the support tube 13, and the upper end (cold junction) of the thermocouple wire is attached to the terminal box 17.
It is connected to the "connector for connecting the thermocouple 15 and the display meter or recorder 18" attached to the "18".

The feature here is that the number of pins on the thermocouple wire side of the connector-18 is 3 as shown in FIG.
With pin specifications, insert a copper short-circuit wire 19 into an empty pin remaining from one of the pins to which one end of the thermocouple wire is connected, and connect one end of the thermocouple wire to the display instrument or recorder side of the connector-18. The copper pins 20 and 20 are connected to the pins, and the pin containing the short-circuit line 19 has a constantan (60%
Cu-40% Ni) conducting wires 21 are connected, and the other end of each of these conducting wires is connected to a display meter (millivolt meter) or recorder 22.

Therefore, one of the copper conductors 20 and the constantan conductor 21 is connected to the short-circuit wire 19 in the terminal box 17.
Thus, a copper-constantan thermocouple with the connector pin containing the above as a thermal contact will be constructed. Therefore, in the above thermocouple thermometer, only the temperature of the hot metal 11 (platinum-thermoelectromotive force of the platinum-rhodium rhodium thermocouple 15) is indicated by the display instrument or the recorder 22.
Continuously monitors the temperature of the cold junction (terminal box 17) of the platinum-platinum-rhodium thermocouple 15 (thermoelectromotive force of the copper-constantan thermocouple consisting of one of the conductors 20 and 21).・ It can be recorded.

By the way, the output of the copper-constantan thermocouple is not only monitored by the display instrument or the recorder 22, but is also monitored by the limiter provided with the alarm device 23 as shown in FIG. In some cases, it is also a preferable means to issue an alarm with a lamp or buzzer output.

Therefore, using the thermocouple thermometer described above, the terminal portion (cold junction portion) of the thermocouple for measuring the hot metal temperature is always available.
If the temperature of the hot metal is kept constant while the temperature is kept constant (when there is a change, the cooling gas can be adjusted immediately), and if the continuous measurement of the hot metal temperature is carried out, it is necessary to use a three-wire conductor. However, high temperature measurement accuracy can be secured without incurring a particularly high cost. Moreover, it is possible to adopt a configuration that is easy to maintain in terms of equipment.

The material to be measured to which the present invention is applied is not limited to molten metal such as hot metal and molten steel, and any material whose temperature is measured by using a high temperature continuous thermometer can be used. It goes without saying that it can be a good target. Further, the monitoring of the cold junction temperature of the temperature-measuring thermocouple does not necessarily have to be performed by configuring the copper-constantan thermocouple described in the embodiment, and temperature sensing and sensing means using other resistance temperature detectors or the like. There is no problem even if the arrangement is made.

[0014]

[Summary of Effects] As described above, according to the present invention, the cold junction portion of the thermocouple for temperature measurement is constantly managed by the thermometer so that "forgetting to supply cooling gas" and "fluctuation of cooling gas pressure". It is easy to keep the temperature of the cold junction constant, which greatly improves the temperature measurement accuracy and reliability of the thermocouple thermometer. It has a useful effect.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a situation in which a temperature measuring means according to the present invention is applied to “continuous temperature measurement of hot metal tapped from a blast furnace”.

FIG. 2 is a description of essential parts (hot contact part and cold contact part) of the thermocouple thermometer used in FIG.

FIG. 3 is an explanatory diagram of a conventional method for measuring a molten steel temperature in a tundish by a thermocouple thermometer.

[Explanation of symbols]

 1 Tundish 2 Molten steel 3 Protective tube 4 Conductor wire 5 Display instrument or recorder 6 Terminal box 11 Hot metal 12 Skinmer cover 13 Support tube 14 Protective tube 15 Thermocouple 16 Magnetic tube 17 Terminal box 18 Connector-19 Copper Short-circuit wire 20 Copper conductor wire 21 Constantan conductor wire 22 Indicator or recorder 23 Alarm device

Claims (1)

[Claims] 1. A thermocouple temperature measuring device comprising a protective tube accommodating a thermocontact of a thermocouple in contact with a material to be measured, and a cold junction of the thermocouple connected to a display instrument or a recorder through a lead wire. When performing temperature measurement with a meter, the temperature of the cold junction is controlled by disposing a thermometer on the cold junction.
Accuracy control method of thermocouple thermometer.