JPH0712878Y2 - Electric furnace - Google Patents

Description

[Detailed Description of the Invention] [Industrial application] Electric furnace used for simple thermobalance used for measuring physical properties of minerals or compounds that decompose thermally such as limestone and dolomite, or water of crystallization of compounds .

More specifically, the present invention provides an electric furnace having a long heating life and a high thermal efficiency.

[Prior Art] Regarding the electric furnace of the present invention, a rapid quality measuring device for limestone and dolomite filed by the applicant of the present invention (Japanese Patent Application No. 61-170493)
The conventional technique will be described by taking a partially improved furnace as an example of the electric furnace used in. FIG. 3 is a vertical cross-sectional view of an electric furnace conventionally used in the above measuring device.

In this electric furnace, an outer wall is formed by a cylindrical metal outer cylinder 1, an annular metal top plate 2 and the same bottom plate 3, and a fireproof material having the same inner diameter as that of the outer wall top plate and bottom plate. A furnace body portion composed of a product inner cylinder 5 and a heat insulating material 4 sandwiched between the outer walls, and a heating element 7 such as a nichrome wire spirally wound in a quartz glass tube 6. And a plurality of heating elements are provided inside the inner cylinder in the longitudinal sectional direction. The both ends of the nichrome wire in the heating element are connected to a sliderac and a temperature control device (not shown) to control the temperature inside the electric furnace to a predetermined temperature.

[Problems to be solved by the invention]

A heating element, such as a nichrome wire wound in a spiral shape in a quartz glass tube, is vertically installed inside the furnace, so the heating element hangs downward due to the weight of the heating element. Since the heating portion inside the furnace moves downward and the heating efficiency deteriorates while protruding outside the quartz tube, it was necessary to frequently replace the heat generating portion.

[Means for solving problems]

As a result of various studies aimed at solving the above problems and developing an electric furnace having high heating efficiency and long life of the heating element, the following electric furnace has been developed.

A heat-generating portion formed by winding a heat-resistant ceramics tube in a spiral shape, and inserting a heating element such as a wire or spirally wound nichrome wire into the heat-resistant ceramics tube, and An electric furnace composed of a heat insulating material layer made of ceramics, asbestos, or the like is attached to the outer circumference, and a furnace body part having an outer wall having a ring-shaped top plate and a bottom plate is provided around the outer circumference of the heat insulating material layer. By developing it, we were able to solve the above problems.

[Action]

A heat-resistant ceramic tube wound in a spiral shape with a heating element such as a wire-shaped or spiral-wound nichrome wire inserted therein is installed in a furnace body, and electricity is applied to both ends of the nichrome wire. As a result, the heating element is heated, and the measurement object installed in the furnace is heated by the heating element.

By inserting the heating element into the heat-resistant glass tube wound in a spiral shape, it is possible to install the heating element in a nearly horizontal state, so it is possible to prevent the phenomenon of sagging due to its own weight during heating, and to place it in the necessary location in the furnace. Since the heating elements can be centrally installed, the heating efficiency of the furnace can be improved.

As the heat-resistant ceramics tube, a ceramics tube that generates infrared rays by heating quartz glass, an alumina-based ceramics tube, or the like and has good heat resistance and workability can be used.

The heating element may be a wire that can be easily deformed and has a large electric resistance, such as a tantalum wire or a supertank wire, in addition to a nichrome wire.

〔Example〕

 FIG. 1 is a vertical sectional view of the electric furnace of the present invention.

In the electric furnace of the present invention, a quartz glass tube 6 with a diameter of 15 mmφ manufactured by Aoba Riken Co., Ltd. is used as a heat-resistant ceramic tube.
The quartz glass tube 6 is wound in a cylindrical shape having an inner diameter of 50 mmφ and spirally so that there is no gap between the adjacent quartz glass tubes 6, and a nichrome wire having a wire diameter of 1 mmφ which is commonly known as Pyromax (trade name) is spirally wound. The heating element 7 wound like a wire is inserted into the quartz glass tube 6, and both ends of the heating element 7 are extended outside the furnace to form a heating section.

Further, the furnace body portion is made of a commercially available heat insulating material 4 called Kao Wool Wet Felt (trade name) and the outer wall temperature of the heating furnace is 30
In the electric furnace of the present invention, the dimensions are below ℃,
The thickness of the heat insulating material 4 is about 50 mm, and the heat insulating material 4 is attached so as to cover the outer peripheral portion and the upper and lower end portions of the quartz glass tube 6.
Further, the outer periphery of the heat insulating material 4 is covered with an outer wall made of a metal outer cylinder 1, a metal annular top plate 2 and a bottom plate 3.

The spiral density of the nichrome wire, which is the heating element of the heating part used in the electric furnace of the present invention, may be appropriately determined according to the required heating temperature, and may be linear if it does not require so much heat. Actual application filed by the applicant Sho 61-170493
In the electric furnace used in the "quick measuring device for quality of limestone and dolomite", it is necessary to rapidly heat the sample consisting of limestone and dolomite to 1000 ° C or higher, which is the dissociation temperature of both, and therefore the spiral density of the nichrome wire. It was possible to concentrate the heat source consisting of nichrome wire at a predetermined place by making the quartz glass tube dense and making the quartz glass tube through which the nichrome wire passes spirally. As a result, not only was it possible to measure the quality of limestone quickly and efficiently, but it was possible to use it without any abnormality even after 3 months had passed since the replacement time of the nichrome wire used in the conventional electric furnace. In addition, since the heating efficiency in the electric furnace was further improved, the measurement time could be shortened by about 15 minutes.

[Effect of device]

By using the electric furnace of the present invention, not only the life of the heating element used for the heating element is extended, but also the sagging phenomenon of the heating element is eliminated, so that the maintenance of the electric furnace is facilitated and the heating element is Can be replaced without disassembling the furnace body
Only the heating element in the heat resistant ceramic tube can be replaced.

Further, since the heat load per unit area can be large and the structure is simple, it is possible to downsize the electric furnace.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an electric furnace of the present invention, and FIG. 2 is a view taken along the line AA of FIG. FIG. 3 is a vertical cross-sectional view of a conventional electric furnace, and FIG. 4 is a BB arrow view of FIG. 4: Thermal insulation material 6: Quartz glass 7: Heating element

Claims (1)

[Scope of utility model registration request] 1. A heat-resistant ceramics tube is wound in a spiral shape,
A heat generating portion formed by inserting a heating element wound in a linear or spiral shape into the heat resistant ceramics tube, and a heat insulating material layer are attached to the outer circumference of the heat generating portion, and the heat insulating material layer is attached to the outer circumference of the heat insulating material layer. An electric furnace characterized in that the outer wall is constructed by a furnace body part.