JP2010122232A - Heating furnace and thermometer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure a temperature at as near to a billet as possible in a furnace. <P>SOLUTION: The heating furnace includes: a protective tube 16 and an insulating tube 12a for an upper combustion-controlling thermocouple-type thermometer 11 set at the ceiling inside the furnace; and a terminal board 13 to fix the insulating tube 12a. The protective tube 16 is fixed to a ceiling wall 14 inside the furnace. The terminal board 13 is attached to the protective tube 16 movably in horizontal and vertical directions so that ambient temperature near the surface of material conveyed in the furnace is measurable. Thereby, ambient temperature near the back surface of a billet conveyed in the furnace is measurable. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heating furnace capable of suppressing uneven heat of in-furnace material, and a thermometer for controlling the temperature in the furnace installed in the heating furnace.

  For example, in the walking beam type heating furnace 31 shown in FIG. 4, a pre-tropical zone 32, a heating zone 33, and a soaking zone 34 are formed from the charging side, and each zone 32 to 34 is heated to a predetermined temperature, for example, a billet or the like. In-furnace material (hereinafter referred to as “billette 35”) is sequentially extracted from the outlet side. Therefore, in-furnace temperature control in each of the bands 32 to 34 is extremely important in order to suppress uneven heat of the billet temperature. In particular, temperature control in the soaking zone 34 immediately before extraction is in demand. And in controlling this furnace temperature, the thermometer which measures the furnace temperature is the most important sensor.

  In order to optimally control the temperature of the billet, it is desirable to measure the temperature in the vicinity of the billet and control the temperature in the furnace based on the measured value. However, a thermometer (thermocouple device) for controlling the temperature in the furnace ) Is generally installed on the furnace wall in terms of price, life and operability.

  For example, the upper combustion control thermometer 36a is installed on the ceiling wall as shown in FIG. 4A, and the lower combustion control thermometer 36b is installed on the side wall as shown in FIG. 4B. It is often attached to. The reason why the thermometer for lower combustion control is attached to the side wall without being attached to the hearth is that it is necessary to install it in a place where it can be easily replaced in the event of a failure. Since the thermometer for controlling the lower combustion is provided on the furnace wall, it tends to be considerably different from the temperature around the lower portion of the billet in the actual extraction zone. This is because the extraction door, the discharge roller, the lower burner, the scale pit, etc. are close to each other and are easily affected by disturbance.

  However, even with the same furnace wall, the temperature is considerably different between the ceiling wall, the side wall, and the hearth. Usually, the heat loss is low, and the hearth near the burner frame has the highest temperature, followed by the ceiling wall and side walls. In particular, in a large and large furnace such as a walking beam heating furnace, the ambient temperature around the thermometer actually used for control and the temperature around the billet are often quite different. This is mainly because the frame length, that is, the peak temperature point of the flame changes depending on the influence of the disturbance described above and the amount of burning of the burner.

  In the walking beam type continuous heating furnace, the ambient temperature around the beam (near the billet) is considerably lower than the ceiling and side walls due to the cooling water that cools the carrier beam and fixed beam. The inventors found that the temperature was extremely low.

  Therefore, in order to know the billet temperature more accurately, it is desirable to install the thermometer for controlling the furnace temperature in the vicinity of the billet as much as possible. However, in the walking beam heating furnace, the furnace temperature is 1200. In order to measure the temperature in the furnace near the billet with a thermometer inserted from the ceiling wall or side wall, a thermometer as long as 2 m is required. It is extremely difficult environmentally, and the actual situation is that the ambient temperature at the position inside the furnace is measured about 100 mm from the ceiling and side walls.

  Therefore, in the in-furnace temperature control using the measured value by the conventional thermometer installed at the position as shown in FIG. 4, when the situation changes, such as when the extraction is stagnant, the temperature difference in the vertical direction of the billet It is easy to stick and causes uneven thickness failure during rolling.

  Incidentally, as shown in FIG. 5, the thermometer (thermocouple device) includes a thermal contact 37 and two thermocouple strands 38, for example, platinum 38a and platinum rhodium 38b connected to the thermal contact 37. This is a configuration in which a thermocouple element 40 including an insulating tube 39 for insulating and holding is housed inside a protective tube 41 (Patent Document 1). The insulating tube 39 is divided in the axial direction.

  The failure of the thermometer having such a configuration can be divided into a failure of a protective tube and a failure of a thermocouple element. Among these, the failure of the protective tube is mainly due to mechanical thermal distortion due to the rise and fall of the furnace temperature and deterioration due to the burner frame and the atmosphere gas in the furnace. On the other hand, defective thermocouple wires are broken due to their own weight due to the fact that the insulation tube must be held due to their configuration, broken due to thermal expansion and contraction due to the rise and fall of the furnace temperature, and material change due to furnace atmosphere gas This is mainly due to errors caused by

  In addition, as a result of the investigation by the present inventors, the thermocouple element itself is more likely to be twisted and broken easily because the platinum side of platinum / rhodium rhodium is stretched more intensely than the platinum rhodium side each time the expansion / contraction is repeated due to thermal stress. It has been found.

  This is because platinum is softer and heavier than platinum rhodium, and is easy to stretch because it is easy to stretch and has low tensile strength. In addition, as shown in FIG. 5B, the insulation tube 39 has a W-shaped outlet, or as shown in FIG. Disconnection is also caused by rubbing at the corner of the outlet of the tube 39 when the expansion / contraction is repeated.

Japanese Utility Model Publication No. 5-23079

  The problems to be solved by the present invention are that the furnace temperature in the vicinity of the billet cannot be measured stably for a long time, and it can withstand thermal stress etc. even if it is somewhat affected by the burner frame. There is no thermometer that can be used.

The present invention has been made on the basis of the above findings, etc.
The heating furnace of the present invention is
To enable temperature measurement near the billet located in the furnace as much as possible,
A protective tube and an insulating tube for an upper combustion control thermocouple thermometer installed on the ceiling in the furnace, and a terminal plate for fixing the insulating tube;
The protective tube is fixed to a ceiling wall in the furnace,
The terminal board is most characterized by being attached to the protective tube so as to be movable in the horizontal and vertical directions.

  In the heating furnace of the present invention, at least the thermometer installed in the furnace has the above-described configuration.If the billet is not at a predetermined temperature in the furnace, uneven thickness occurs in subsequent rolling, As described above, the temperature in the furnace is particularly low near the extraction roller, and it is necessary to measure the ambient temperature near the billet more accurately.

Further, the thermocouple thermometer for upper combustion control of the present invention installed in the heating furnace of the present invention,
In order to eliminate the influence of the burner frame etc. and to extend the life,
A thermocouple element constituting the protective tube, the insulating tube, and the thermocouple thermometer;
The insulating tube is attached to the protective tube so as to be movable in the horizontal and vertical directions,
The most important feature of the thermocouple element is that it is insulated and held in the insulating tube.

In the upper combustion control thermocouple thermometer installed in the heating furnace of the present invention,
Having two thermocouple wires and the insulating tube,
The insulating tube has a wedge-shaped tip, and an outlet of the two thermocouple wires is provided on the wedge-shaped surface,
The thermocouple wire is composed of two parts, platinum rhodium and platinum,
The platinum rhodium part is longer than the platinum part, and the contact position of the two thermocouple wires is located closer to the platinum side, the disconnection of the thermocouple wire due to the contact at the outlet of the insulating tube It is desirable from the point of preventing. In addition, it is desirable that the protective tube of the upper combustion control thermocouple thermometer is made of recrystallized alumina from the viewpoint of extending the life.

  In the present invention, since the temperature in the furnace near the billet can be measured as much as possible while extending the life of the thermometer, there is an advantage that the occurrence of uneven heat can be suppressed.

It is an explanatory view of the thermocouple thermometer for upper combustion control in the heating furnace of the present invention, and is a view for explaining the case where it is installed on a soaking ceiling wall, (a) is installed on both sides in the furnace width direction, (B) is installed at the center in the furnace width direction. It is the figure which showed the detail of the thermocouple type thermometer for upper combustion control in the heating furnace of this invention in cross section, (a) is the figure seen from the front, (b) is a protection tube, an insulation tube, and a thermocouple element It is the figure which looked at the line from the side. It is explanatory drawing of the shape and heat | fever contact in the exit of the insulation pipe | tube in the thermocouple thermometer of this invention, (a) is normal temperature (before use), (b) is high temperature (after use), (c) is ( a) It is the figure which looked at the figure from the side. It is a figure explaining the installation position of the thermometer for furnace temperature control in a walking beam type heating furnace. It is a figure explaining an example of the conventional thermometer, (a) is a general view, (b) shows explanatory drawing of a thermocouple element. It is a figure of the thermocouple element explaining the other example of the conventional thermometer.

  In the present invention, the purpose of measuring the temperature in the furnace near the billet as much as possible while extending the life of the thermometer is to allow the terminal plate for fixing the insulating tube to be moved in the horizontal and vertical directions. This was realized by attaching to the protection tube of the thermocouple thermometer for upper combustion control fixed to the ceiling wall in the furnace.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to FIGS.

  FIG. 1 is an explanatory diagram of a thermocouple thermometer for upper combustion control in a heating furnace of the present invention when applied to a walking beam type heating furnace. FIG. It is the figure which carried out the cross section and showed the detail of the thermocouple thermometer for upper combustion control.

  Reference numeral 11 denotes an upper combustion control thermocouple thermometer. As shown in FIG. 2, the insulating tube 12a constituting the thermocouple element 12 is integrally formed without being divided in the axial direction, and is integrally formed. The insulated tube 12a is fixed to the terminal plate 13 at its upper end. By doing so, the insulating tube 12a is not held by the thermocouple element 12b, and disconnection of the thermocouple element 12b due to its own weight can be prevented and intrusion of furnace atmosphere gas can also be prevented.

  The terminal board 13 is attached to a recrystallized alumina protective tube 16 fixed to the ceiling wall 14 by, for example, a flange 15 so as to be movable in the horizontal direction and the vertical direction. The means for attaching the terminal plate 13 to the protective tube 16 so as to be movable in the horizontal direction and the vertical direction is not particularly limited, but the example shown in FIG. 2 has the following configuration.

  That is, the protective tube 16 is constituted by a double of an outer protective tube 16a and an inner protective tube 16b, and the holding plate 19 is placed in a case 18 made of stainless steel, for example, which is further bonded to the outside of the outer protective tube 16a by a heat-resistant cement 17. To fix. In addition, the length of the stainless steel portion is set so as not to enter the furnace because of the heat resistant temperature.

  A seat 21 having a hole 21 a having a diameter larger than that of the screw shaft 20 attached to the holding plate 19 so as to protrude is placed on the holding plate 19 through the screw shaft 20, and provided on the shaft center of the seat 21. The terminal plate 13 is fitted into the shaft hole 21b. By doing in this way, the terminal board 13 can move freely with respect to the protective tube 16 in a horizontal direction and an up-down direction.

FIG. 3 is an explanatory diagram of the shape and the hot junction at the tip of the insulating tube in the thermocouple thermometer of the present invention.
In the upper combustion control thermocouple thermometer 11, the tip of the insulating tube 12a constituting the thermocouple element 12 is formed in a wedge shape as shown in FIG. As shown in FIG. 3A, the platinum rhodium 12bb having a small coefficient of thermal expansion of the two thermocouple wires 12b is thermally expanded at room temperature as shown in FIG. It is desirable that the position of the thermal contact 22 is positioned closer to the platinum 12ba side than the platinum 12ba having a high rate in advance.

  With such a configuration, when the two thermocouple wires 12b expand and contract, contact at the corner of the outlet of the insulating tube 12a can be effectively prevented, and disconnection of the thermocouple wires 12b can be prevented. it can.

  For example, in a walking beam heating furnace in which the upper combustion control thermocouple thermometer 11 is installed in the soaking zone, the furnace atmosphere temperature near the billet is measured, and the furnace temperature can be optimally controlled. The occurrence of uneven heat can be suppressed.

  The above example is merely an example, and the present invention is not limited to the above example, and it goes without saying that the embodiment may be appropriately changed within the scope of the technical idea described in each claim.

  The present invention as described above can be applied not only to a heating furnace but also to a heat-retaining furnace or any furnace. It can also be applied to furnaces other than walking beam furnaces.

11 Thermocouple Thermometer for Upper Combustion Control 12 Thermocouple Element 12a Insulating Tube 12aa Wedge Surface 12b Thermocouple Wire 12ba Platinum 12bb Platinum Rhodium 13 Terminal Board 14 Ceiling Wall 16 Protective Tube

Claims (4)

A protective tube and an insulating tube for an upper combustion control thermocouple thermometer installed on the ceiling in the furnace, and a terminal plate for fixing the insulating tube;
The protective tube is fixed to a ceiling wall in the furnace,
A heating furnace characterized in that the terminal plate is attached to the protective tube so as to be movable in the horizontal direction and the vertical direction, and is capable of measuring the ambient temperature in the vicinity of the surface of the material transported in the furnace. A thermocouple element constituting the protective tube, the insulating tube, and the thermocouple thermometer;
The insulating tube is attached to the protective tube so as to be movable in the horizontal and vertical directions,
The thermocouple thermometer for upper combustion control installed in a heating furnace according to claim 1, wherein the thermocouple element is insulated and held in the insulating tube. Having two thermocouple wires and the insulating tube,
The insulating tube has a wedge-shaped tip, and an outlet of the two thermocouple wires is provided on the wedge-shaped surface,
The thermocouple wire is composed of two parts, platinum rhodium and platinum,
3. The upper combustion installed in a heating furnace according to claim 2, wherein the platinum rhodium portion is longer than the platinum portion, and the contact position of the two thermocouple wires is located closer to the platinum side. Thermocouple thermometer for control.   4. The upper combustion control thermocouple thermometer installed in a heating furnace according to claim 2, wherein the protective tube of the upper combustion control thermocouple thermometer is made of recrystallized alumina.

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