JP2014199773A - MoSi2-BASED HEATER UNIT - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve uniform heating performance and reduce energy loss in a MoSi-based heater unit including a plurality of heater modules comprising a MoSi-based material.SOLUTION: A heater module includes a resistance heating part and a terminal part connected to both ends of the resistance heating part and provided to a heat insulation body. The electrical resistance of the resistance heating part is 4-1,000 times the electrical resistance of the terminal part.

Description

The present invention relates to a MoSi ₂ heater unit including a plurality of heater modules made of a MoSi ₂ material.

A large-bore tubular furnace heater unit using MoSi ₂ -based material as a heating element is a semi-cylindrical multi-shank heater formed by joining MoSi ₂ -based U-shaped materials according to the inner diameter of the furnace. It has been adopted. In furnaces where the distance from the hearth to the ceiling is high, modules or heaters are divided into several zones, and the temperature control is performed by improving the temperature distribution and creating a temperature gradient by controlling the input power for each zone.

However, in the multi-shank heater unit, since the tip portions of the shanks face each other, a temperature difference is likely to occur between the central portion of the zone and the joint portion. Furthermore, although the heating element of the MoSi ₂ material has plasticity at a high temperature, since there is a limit to the curvature that can be bent, it is difficult to arrange the heater densely.

  In order to improve this, the method of arrange | positioning so that the front-end | tip part of a shank may be nested is disclosed. However, even if one shank is disconnected, all zones must be replaced, which is disadvantageous in terms of running costs.

Patent Document 1 discloses an electric furnace composed of two or more zones as a combination of a metal heater and a MoSi ₂ heater module.

Patent Document 2 describes that the durability and heat uniformity of the tubular heater module are excellent when the relationship between the coil inner diameter of the MoSi ₂ coil heater and the distance between the heaters takes an appropriate value.

Republished patent WO2004 / 049414 Japanese Patent Application No. 2012-184115

By the way, in order to operate the MoSi ₂ system heater unit at 1000 ° C. or higher, it is necessary to pass a large current through the resistance heating element, and it is necessary to provide terminal portions for energization from the outside of the heater unit at both ends of the heating element. Therefore, energy loss occurs due to the electrical resistance of the terminal portion. This can be avoided by shortening the terminal part length or increasing the terminal part diameter, but the heat capacity of the terminal part itself and the heat flow loss to the wiring side due to high heat conduction and the resulting decrease in thermal uniformity, Furthermore, problems such as an increase in contact resistance due to the high temperature have occurred.

In the present invention, there is provided a heater unit using a plurality of MoSi ₂ -based heater modules that improve the thermal uniformity in the heater unit and reduce energy loss.

The heater unit of the present invention is a heater unit including a plurality of heater modules including a heat insulating material made of a ceramic board and the like and a resistance heating element that generates heat when energized. The resistance heating element of the heater module is based on MoSi _2. A resistance heating portion made of a material and a terminal portion disposed inside the heat insulating material and electrically connected to an end portion of the resistance heating portion, the resistance of the resistance heating element portion being 4 of the electrical resistance of the terminal portion. It is characterized by -1000 times.

  The heater unit of the present invention is characterized in that the terminal portion is made of the same material as the resistance heating portion.

  The heater unit of the present invention is characterized in that the input power of each of the plurality of heater modules is individually controlled.

  The heater unit of the present invention is characterized in that the heat insulating material can be divided for each heater module.

The heater unit of the present invention includes a plurality of heater modules including a heat insulating material such as a ceramic board and a resistance heating element that generates heat when energized, and the resistance heating element of the heater module is a resistance heating part made of a MoSi ₂ material. And a terminal portion connected to both ends of the resistance heating portion disposed inside the heat insulating material, and the resistance of the resistance heating element portion is set to 4 to 1000 times the electrical resistance of the terminal portion. In addition to reducing the energy loss of the unit, soaking can be improved.

  Since the terminal part of the heater unit of the present invention is made of the same material as that of the resistance heating part, the resistance heating part and the terminal part can be manufactured integrally, and therefore, manufacture is easy.

  Furthermore, the terminal part of the heater unit of the present invention is made of the same material as that of the resistance heating part, and is manufactured integrally, thereby reducing the contact resistance between the resistance heating part and the terminal part and ensuring the heat resistance of the terminal part. I can do it.

  The heater unit of the present invention can improve the heat uniformity in the heater unit by individually controlling the input power of the plurality of heater modules.

  In the heater unit of the present invention, since the heat insulating material can be divided for each heater module, even if a defect occurs in some of the heater modules, it can be repaired by replacing only the heater module and the heat insulating material. Therefore, repair becomes easy.

It is sectional drawing of 1 form of the heater unit of this invention. It is the schematic of 1 form of the heater unit of this invention. It is sectional drawing of another form of the heater unit of this invention. It is the schematic of another form of the heater unit of this invention.

  One embodiment of the heater unit of the present invention will be described with reference to FIGS. 1 and 2.

As shown in FIG. 1, one form of the heater unit 100 of the present invention insulates the outside from the inside of the furnace 105 with a cylindrical heat insulating material 101 made of a ceramic board (aggregate of ceramic fibers) and the like. consisting MoSi ₂ material disposed between the resistance heating portion 300, consisting of Metropolitan terminal portion 200 disposed within the heat insulating material 101 is connected to both ends of the resistance heating portion 300 consists MoSi ₂ material, heater module 600 (corresponding to zone A (700) and zone B (701) in FIG. 1).

  The resistance heating part 300 disposed in the furnace 105 in one form of the heater unit 100 of the present invention has a spiral shape along the inner wall of the furnace 105, and both ends thereof penetrate the heat insulator 101, respectively. To the terminal portion 200 to be connected.

  As shown in FIG. 1, one form of the heater unit 100 of the present invention has two heater modules 600 so as to overlap in the vertical direction, and the cylindrical heat insulating material 101 is respectively formed as shown in FIG. 2. The heater module 600 is separated in the vertical direction.

  The outer diameter (inner diameter of the heat insulating material 101) of the furnace 105 in one form of the heater unit 100 of the present invention is 500 mm, the outer diameter of the heat insulating material 101 is 700 mm, and the height is 1000 mm.

  The electrical resistance of the resistance heating unit 300 according to one embodiment of the present invention is 4 to 1000 times the electrical resistance of the terminal unit 200, thereby suppressing energy loss due to generation of Joule heat in the terminal unit 200 and at the terminal unit 200. Heat dissipation loss can be prevented.

  If the electric resistance of the resistance heating part 300 is smaller than four times the electric resistance of the terminal part 200, the generation of Joule heat in the terminal part 200 is relatively large compared to the input power, so that the energy loss is 20% or more. In addition to the increase, the temperature in the vicinity of the terminal portion 200 in the furnace 105 is rapidly increased as compared with the other portions, so that the thermal uniformity is greatly reduced. .

  On the other hand, if the electrical resistance of the resistance heating part 300 exceeds 1000 times the electrical resistance of the terminal part 200, the heat dissipation through the terminal part 200 increases, and the energy loss greatly increases to 20% or more. The soaking property near 200 is rapidly reduced. In addition, the local resistance distribution of the resistance heating unit 300 causes local heat generation variation of the resistance heating unit 300, and as a result, the heat uniformity in the furnace 105 is lowered.

  In one embodiment of the heater unit 100 of the present invention, the input power is controlled separately for the two heater modules 600 in consideration of the electrical resistance of the resistance heating part 300 and the terminal part 200, the shape of the furnace 105, and the like. Is preferred. Thereby, the soaking | uniform-heating property of the furnace 105 can be improved more.

  A heat insulator 101 according to one embodiment of the heater unit 100 of the present invention has an inner diameter: 500 mm, an outer diameter: 700 mm, and a height: 1000 mm, and is divided into two upper and lower zones, zone A (700) and zone B (701). (Ie, two heater modules 600). The resistance heating unit 300 is formed by spiraling a round bar having an outer diameter of 3 mm. The helix spacing was 15 mm. The seam portion of each zone of the heat insulating body 101 is not a straight line as shown in FIG. 2 but an oblique cross section along the resistance heat generating portion 300, so that the arrangement of the resistance heat generating portion 300 is made uniform even at the seam portion of each zone. I was able to.

  The resistance heating part 300 of one form of the heater unit 100 of the present invention is 6Ω per heater module, and the resistance of the terminal part 200 of each heater module is 0.006Ω to 1.5Ω in total at both ends. did. When the electric resistance of the terminal part 200 is smaller than 0.006Ω, the heat in the furnace 105 is released to the outside through the terminal part 200, and the thermal uniformity in the vicinity of the terminal part 200 is lowered. On the other hand, when the electric resistance of the terminal part 200 exceeded 1.5Ω, Joule heat was generated by energization of the terminal part 200, so that the heat uniformity in the furnace 105 was lowered and the energy loss was rapidly increased. In particular, the electrical resistance of the resistance heating part 300 is 10 to 60 times the electrical resistance of the terminal part 200, that is, the electrical resistance of the terminal part 200 is changed from 0.6Ω to 0.12Ω with respect to the electrical resistance of 6Ω of the resistance heating part 300. In this case, the heat variation in the vicinity of the terminal portion 200 in the furnace 105 was 0.1 ° C. or less, which is the measurement limit, and a heater unit having complete heat uniformity was obtained. At this time, the set temperature in the furnace 105 was set to 1500 ° C., and the terminal portion 200 was made of the same material as that of the resistance heating portion 300 by integral molding. As a result, the heat resistance of the terminal portion 200 is ensured, and at the same time, the reliability at the connection portion with the resistance heating portion 300 is ensured, and destruction due to thermal strain or the like was not confirmed. However, when the set temperature in the furnace 105 is, for example, 1000 ° C. or less, the terminal portion 200 is heat resistant and has an electrical resistance that is 1/1000 to 1/4 of that of the resistance heating portion 300. It is also possible to form with stainless steel or the like.

  On the other hand, the electrical resistance of the resistance heating unit 300 is increased by increasing the outer diameter of the resistance heating unit 300 from 3 mm to 0.3 mm and the length of the resistance heating unit 300 by 10 times the electrical resistance of the terminal unit 200 of 0.006Ω. When the resistance was increased to 600Ω, the electrical resistance of the resistance heating part 300 increased to 1 kΩ immediately after energization, and further the electrical resistance continued to increase gradually. This is presumably because thermal distortion or the like is likely to occur between the resistance heating unit 300 and the terminal unit 200, and the defect is amplified.

  In addition, the heat insulating body 101 was formed with a groove so that the resistance heating part 300 could be installed on the inner wall of the heat insulating material 101. The energization conditions were such that the temperature in the furnace 105 was 1500 ° C. and became uniform within an error of ± 2.3 ° C.

  Although the heater unit of the present invention has been described with reference to FIGS. 1 and 2 with two heater modules, if the electrical resistance of the terminal unit 200 is 4 to 1000 times the electrical resistance of the resistance heating unit 300, Three or more may be sufficient and it is not limited to the form of FIGS.

  1 and 2, the thickness of the heat insulator 101 can be arbitrarily set as long as the interior 105 of the furnace can be sufficiently insulated. Furthermore, in order to prevent deformation of the heat insulating material 101 due to thermal stress, the periphery of the heat insulating material 101 may be covered with a metal frame such as stainless steel.

  Another embodiment of the present invention will be described with reference to FIGS.

  In the present embodiment, the heat insulator 101 is divided into two zones C (703) and D (704) so as to divide the cylinder vertically. Unlike the first embodiment, the resistance heating unit 300 has a zigzag shape, and one heat insulator 101 is provided with two heater modules 600, one on each of the upper and lower sides.

  Also in the present embodiment, the electrical resistance of the terminal unit 200 is designed to be 4 to 1000 times the electrical resistance of the resistance heating unit 300, and the heater module (zone C and zone D) in the heater unit 100 is designed. 1 is the same as the embodiment of FIGS. 1 and 2 except that the arrangement is different from that of the embodiment of FIGS. In the present embodiment, it is easy to repair a large vertical heater unit, and the heater module has a high degree of design freedom, so that it is possible to design the heat uniformity in the furnace 105 to be higher.

DESCRIPTION OF SYMBOLS 100 Heater unit 101 Heat insulating material 105 In-furnace 200 Terminal part 300 Resistance heating part 600 Heater module 700 Zone A
701 Zone B
703 Zone C
704 Zone D

Claims (4)

A heater unit comprising a plurality of heater modules composed of a heat insulating material made of a ceramic board or the like and a resistance heating element that generates heat when energized,
The resistance heating element of the heater module includes a resistance heating part made of a MoSi ₂ material and a terminal part disposed inside the heat insulating material and electrically connected to an end of the resistance heating part.
The heater unit according to claim 1, wherein an electric resistance of the resistance heating element is 4 to 1000 times greater than an electric resistance of the terminal part.   The heater unit according to claim 1, wherein the terminal portion is made of the same material as the resistance heating portion.   The heater unit according to claim 1 or 2, wherein the input power of each of the plurality of heater modules is individually controlled. 4. The heater unit according to claim 1, wherein the heat insulating material can be divided for each heater module.

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