JP2995312B2 - Atmosphere heating furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an atmosphere heating furnace for performing various heat treatments such as sintering and quenching of sintered parts, in which a furnace core tube is provided, and a heat-treated product is flowed through the furnace core tube for heating. The present invention relates to an atmosphere heating furnace to be processed.

[0002]

2. Description of the Related Art An atmosphere heating furnace (hereinafter referred to as a heating furnace) used for producing sintered parts, heat-treating metal parts, and the like is disclosed in Japanese Patent Application Laid-Open No. 56-66682. There is also one using a furnace core tube. This is, for example, FIG.
As shown in (1), a furnace core tube (2) made of heat-resistant cast steel is provided in a furnace body (1) formed by stacking heat-resistant members, for example, heat-resistant bricks in layers, in a cylindrical shape. A heater (3) is arranged around the furnace, and a supply pipe (4) for supplying an atmospheric gas into the furnace core tube (2) is provided at an appropriate place in the furnace body (1), and a mesh is provided in the furnace core tube (2). The belt (5) is circulated.

[0003] The heating furnace heats the inside of the furnace core tube (2) with a heater (3), supplies atmospheric gas from the supply pipe (4) into the furnace core tube (2) and fills it with a mesh. The belt (5) is circulated, and the heat-treated product (6) is conveyed into the furnace core tube (2) by the mesh belt (5) to perform heat treatment.

As the atmosphere gas used in the heating furnace, a reducing gas mainly composed of carbon monoxide, modified hydrocarbon gas, or the like is used. Further, since the furnace core tube (2) expands and contracts by raising and lowering the temperature in the furnace, one end is fixed to the furnace main body (1) and the other end is free to allow expansion and contraction of the furnace core tube (2). It has become.

[0005]

The heating furnace using the above furnace core tube (2) absorbs the expansion and contraction of the furnace core tube (2) . A sealing material (7) is mounted on the inner surface of the inlet portion, and the end of the furnace core tube (2) is slidably held by the sealing material (7), and the atmospheric gas leaks to the heater (3). I also try not to.

However, in the above structure, the sealing material (7) is worn by the expansion and contraction of the furnace core tube (2), and a gap is generated between the sealing material (7) and the furnace core tube (2), and the atmosphere gas is removed. From the gap to the heater (3) side in some cases. Since the atmosphere gas is a flammable gas, the leaked atmosphere gas may be directly heated by the heater (3) and explode. Also, when replacing the heater (3) or replacing the thermocouple during operation, the atmosphere gas leaked from the furnace mixes with the air,
When the mixing ratio was constant, there was a risk of explosion, so maintenance work during operation was not possible. Therefore, maintenance work can only be performed after the operation of the heating furnace has stopped and the temperature inside the furnace has decreased, and it takes time to adjust the temperature of the furnace during maintenance and inspection of the heating furnace, and the operating rate decreases. , Large energy loss.

An object of the present invention is to provide a heating furnace in which atmospheric gas leaking from between the furnace core tube and the sealing material is prevented from flowing into the heating heater.

[0008]

According to the present invention, a furnace core tube is provided in a furnace body, one end of the furnace core tube is fixed to the furnace body, and the other end is slid to the furnace body via a sealing material. In an atmosphere heating furnace which is freely held and heats the furnace core tube with a heater, and heat-treats the heat-treated product by flowing the heat-treated product into the furnace core tube, the outer periphery of the sealing material is provided on a part of the furnace body. Position facing the surface and adjacent to the heater
An exhaust pipe extending to the position shown in the figure is attached, an ignition device is provided at a protruding end of the exhaust pipe, and the exhaust pipe is brought close to the sealing material.
Atmosphere gas is detected in the heater chamber where the heater is installed.
Provide a gas sensor that knows and supplies an inert gas to the heater chamber.
It is provided with an inert gas supply device for supplying .

[0009]

In the heating furnace, the atmosphere gas leaking from between the furnace core tube and the sealing material is exhausted from the exhaust pipe to the outside of the furnace, and the exhausted atmosphere gas is ignited by an ignition device and burned for processing. is there.

[0010] Also, by detecting the ambient gas at the gas sensor, the detected density of the gas sensor exceeds a predetermined level, the inert gas from the inert gas supply device is supplied to the heater chamber, the inert gas atmosphere gas Is to be replaced.

As described above, in any heating furnace, the leakage of the atmospheric gas to the heating heater is prevented, so that there is no danger of explosion.
Maintenance and inspection work such as replacement of the heater can be performed in the operating state.

[0012]

An embodiment of the present invention will be described below with reference to FIG . The same components as in the prior art are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 1, the heating furnace has a furnace body (1).
And an exhaust pipe (10) is inserted so that the end of the exhaust pipe (10) faces the sealing material (7). Cover the upper end of the exhaust pipe (10) with an exhaust hood (11),
And an ignition device (12) near the upper end of the exhaust pipe (10).
Is provided.

In the above heating furnace, when atmospheric gas leaks from between the furnace core tube (2) and the sealing material (7), the atmospheric gas is exhausted from the exhaust pipe (10) to the outside of the furnace main body (1). You. Here, the exhaust pipe (1) is connected to the ignition device (12).
Atmosphere gas exhausted from 0) is ignited and burned. This prevents the atmospheric gas from flowing into the heater (3),
No risk of explosion. Therefore, replacement of the heater (3) can also be performed during operation.

[0015] Also, a heater chamber mounting the heater (3) to (13) is brought close to the seal member (7) attached to the gas sensor (14) for detecting the atmospheric gas, the gas sensor (1
An air supply pipe (15) of an inert gas supply device (17) is attached to the side of 4), and the gas supply pipe (15) is inserted into the heater chamber (13). An open / close valve (16) is attached to the air supply pipe (15) and is connected to an inert gas supply device (not shown).

Accordingly, when the atmospheric gas leaks from between the furnace core tube (2) and the sealing material (7), the gas sensor (14) detects the leak, and the gas sensor (14) detects the atmospheric gas at a certain concentration or more. Then, the open / close valve (16) is opened, and the inert gas is supplied from the air supply pipe (15) to the heater chamber (13), and is replaced with the atmospheric gas to prevent explosion.

In the heating furnace, the atmospheric gas leaking to the sealing material (7) is exhausted from the exhaust pipe (10) and burned, and further, there is a gas leaked from the sealing material (7) to the heater chamber (13). Is also detected by the gas sensor (14),
When the concentration exceeds a certain level, the inert gas is supplied from the air supply pipe (15) and replaced with the atmospheric gas, so that the safety becomes very high.

[0018]

According to the present invention, even if the sealing material wears due to shrinkage of the furnace core tube and the atmospheric gas leaks, the leaked atmospheric gas is exhausted from the exhaust pipe to the outside of the furnace main body and burned. Since the atmospheric gas does not enter the heater chamber and there is no danger of explosion, maintenance and inspection such as replacement of the heater can be performed during the operation of the heating furnace, and the operating rate of the heating furnace is improved.

[0019] In addition, even if leakage of atmosphere gas to the heater chamber,
When the gas sensor detects this and the ambient gas reaches a certain concentration or higher, it supplies an inert gas from the air supply pipe to the heater chamber and replaces it with the ambient gas, eliminating the risk of explosion and maintaining the furnace during operation. Inspection can be performed.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a characteristic portion of a heating furnace according to the present invention.

FIG. 2 is a partial sectional view showing another embodiment of the heating furnace according to the present invention.

FIG. 3 is a sectional view showing an example of a heating furnace using a furnace core tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace main body 2 Furnace core tube 3 Heater 7 Sealing material 10 Exhaust pipe 12 Ignition device 14 Gas sensor 17 Inert gas supply device

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F27B 9/24 C21D 1/74 F27B 9/30

Claims (1)

(57) [Claims] A furnace core tube is provided in a furnace body, one end of the furnace core tube is fixed to the furnace body, and the other end is slidably held by the furnace body via a sealing material. In an atmosphere heating furnace in which a tube is heated by a heater and a heat-treated product is flowed into the furnace core tube to perform heat treatment, a part of the furnace body faces the outer peripheral surface of the sealing material.
Mounting an exhaust pipe extending to a position adjacent to the heater I, an ignition device provided in the projecting end of the exhaust pipe, before
Heater for mounting the heater close to the sealing material
A gas sensor for detecting atmospheric gas is provided in the
An inert gas supply device for supplying inert gas to the
Atmosphere furnace, characterized in that digit.