JPS5884921A - Heat exchanging type continuous heat treating furnace - Google Patents

Abstract

PURPOSE:To improve the heat exchanging efficiency of treating materials and atmosphere gases in respective zones of preheating and cooling by segmenting the preheating zone and cooling zone which are provided continuously before and behind a high temp. treating zone and in which the atmosphere gases are circulated into plural zones provided with convection fans on the ceilings. CONSTITUTION:A continuous treating furnace T consists of a preheating zone A, a high temp. treating (heating) zone B and a cooling zone C, which are partitioned by means of walls 2, 2. The zones A, C are segmented respectively by walls 3, 4, and convection fans 7 are provided in the respective divided zones and the zone B. The terminal zone 5b of the zone A and the beginning zone 6a of the zone C are communicated with a duct 8 and further the beginning zone 5a of the zone A and the terminal zone 6c of the zone C are communicated with a duct 9. Atmosphere gases circulate through the zones 6a 5b 5a 6c 6b 6a in this order. Then the stepwise temp. differences in the respective zones of the zones A, C are assured, treating materials W are heat-exchanged efficiently and the treating materials are preheated and cooled easily to desired final temps.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous heat treatment furnace that takes energy saving measures.

Conventionally, various ideas have been proposed to save energy in continuous heat treatment furnaces consisting of a pre-heating zone, a high-temperature treatment zone, and a cooling zone.

One of them is Japanese Patent Publication No. 45-10610. This idea consists of arranging a continuous heat treatment furnace in a U-shape so that the pre-heating zone and the cooling zone are parallel to each other through a furnace partition wall provided with a space between the ceiling wall and the cooling zone. It is designed to perform heat exchange.

However, the above-mentioned method has the disadvantage that the furnace atmosphere gases mix in the same zone of the pre-cooling zone or the cooling zone, making it difficult to maintain a temperature difference between the furnace and the treated material, resulting in low heat exchange efficiency.

Therefore, in order to eliminate the above-mentioned drawbacks, the present applicant previously proposed in Japanese Patent Application No. 56-24463 that the pre-preparation zone and the cooling zone are arranged on both sides of the high-temperature treatment zone through an intermediate door, and in one unified manner. The preheating zone and the cooling zone are connected to each other as a zone, and the terminal end of the preheating zone and the starting end of the cooling zone are connected through ducts, respectively, and convection fans are arranged in the preheating zone and the cooling zone. , the atmospheric gas between the pre-preparation zone and the cooling zone is circulated from the beginning of the pre-cooling zone → the end of the pre-preparation zone → the start of the pre-preparation zone → the end of the cooling zone → the beginning of the cooling zone, and the atmospheric gas between the pre-preparation zone and the cooling zone is By circulating the gas countercurrently to the moving direction of the treated material and forming convection of atmospheric gas in each zone, the treated material is efficiently heat-exchanged in the preheating zone and the cooling zone, thereby saving energy. A continuous heat treatment furnace was proposed.

However, in the above method, the temperature of the atmospheric gas in the preheating zone and the cooling zone is homogenized over the entire zone due to the agitation action of the convection fan, the average temperature difference between the atmospheric gas and the material is small, and the final preheating and cooling temperatures are This has the disadvantage that it is difficult to achieve a desired value and it is difficult to ensure a predetermined cooling rate.

As a result of the study, it was found that because the preheating zone and the cooling zone are one zone, the atmospheric gas, which originally has a temperature difference between the starting end and the ending end, is stirred and homogenized by the convection fan. I found out.

The present invention has been made based on the above findings, and includes a continuous heat treatment furnace in which a preheating zone and a cooling zone are connected to a high-temperature treatment zone equipped with a heating means. In addition to dividing the area into multiple zones equipped with fans,
The terminal zone of the pre-heating zone and the starting zone of the cooling zone are connected through a duct, and the atmospheric gas in the cooling zone is allowed to flow from the starting zone of the cooling zone to the terminal zone of the pre-cooling zone and the starting zone of the pre-cooling zone. It is an object of the present invention to provide a heat exchange type continuous heat treatment furnace that solves the above-mentioned problems by ensuring a stepwise temperature difference between the atmospheric gas and the zone in each zone.

Next, the present invention will be explained based on the male side of the drawings.

1 and 2 show a first embodiment, in which a continuous heat treatment furnace T consists of a preheating zone A, a heating zone B which is a high temperature treatment zone equipped with a direct-fired burner 1, and a cooling zone C. Each band A,
B and C are separated by partition walls 2 and 2, and preheating zone A and cooling zone C are separated by partition wall 3. 3 Sea 76a, 6
Each divided zone and heating zone B is equipped with a circulation (convection) fan 7.

A second zone 5 is the terminal zone of the preheating zone A.
ducts 8 and 9, respectively. The atmospheric gas is communicated with the cooling zone 1st zone 6a → the pre-preparation zone 2 zone 5b → the pre-preparation zone 1 zone 5a.
→ Third cooling zone, 5c → Second cooling zone 6b → First cooling zone 6a.

In the embodiment, the first and second zones 5a, 5b of the preheating zone A and the first zone of the cooling zone C are provided with a hood 10 having a large number of jet nozzle holes 11 on the lower surface, and the circulation fan 7, the atmospheric gas is moved to the hood 1 by the positive pressure inside the hood 10 or the negative pressure outside the hood 10.
The above-mentioned circulation is carried out by means of a duct 8.9 which opens into and out. Moreover, it is of course possible to separately provide blowers in the ducts 8 and 9 depending on the case.

Therefore, the processing material W is charged into the preheating zone A through the charging door 12a, and transferred to the heating zone B by the conveyance rollers 13.

The treated material W is heat-treated through the cooling zone C and extracted through the extraction door 12b, but the treated material W is preheated in the first zone 5a of the preheating zone A with atmospheric gas at approximately 510° C. from the second zone 5b.

Then, the treated material W is preheated in the next second zone 5b with a mixed gas of the high temperature atmospheric gas from the first zone 6a of the cooling zone C and the combustion exhaust gas from the heating zone B at a temperature of about 600°C. It is heated to 720°C.

On the other hand, the treated material W treated in the heating zone B is
In zone 6a, it is cooled by the low-temperature atmospheric gas of approximately 420° C. from second zone 6b.

In this first zone 6a, the atmospheric gas is in the heating zone B.
Since the treatment material W is heated to approximately 720° C., the temperature is increased to approximately 550° C., and then the treated material W is supplied to the second zone 5b of the preheating zone A as described above. Note that 14 is a circulating gas control damper.

Next, the treated material W is similarly transferred to the second and third zones 5b,
5c, it is cooled along a predetermined cooling curve and extracted from the extraction door 12b.

FIG. 3 shows the temperature of the treated material (a) and the atmospheric gas temperature of each zone (including the zone) in the above case.

The direct-fired burner 1 may be a radiant tube or an electric heating element, and the first
The duct 9 that connects the zone 5a and the third zone 6C, which is the terminal end of the cooling zone C, may be omitted depending on the case.

FIG. 4 shows a second embodiment, in which the burner in the heating zone B is a radiant tube 15 which is an indirect heating means, and the high-temperature smoldering exhaust gas is used for the first zone 6a of the cooling zone C and the first zone 6a of the preheating zone A.
The duct 8 communicating with the second zone 5b is heated, and the processing material W is heated.
The aim is to make preheating more effective.

That is, in the figure, the duct 8 penetrates the inside of the heat exchanger 17 composed of the duct 8 and the exhaust collection duct 18 of the radiant tube burner 1.
The high-temperature exhaust gas No. 6 heats the exhaust gas from the first zone 6a of the cooling zone C flowing through the duct 8 to about 700° C., preheats the combustion air of the radiant tube burner 16 in the heat exchanger 19, and then exhausts it. It looks like this. In addition,
20 is a blower.

As is clear from the above description, according to the present invention, the atmospheric gas, which has become high in temperature due to the cooling heat of the high-temperature treatment material transported from the high-temperature treatment zone to the cooling zone, is pre-empted from the cooling zone start zone through the duct. In the tropical starting zone, a convection fan applies convection in the direction of movement of the treated material while preheating the treated material by countercurrent flow.The preheating zone and cooling zone are divided into multiple zones equipped with convection fans on the ceiling. Because the atmospheric gases in adjacent zones do not mix directly with each other, the atmospheric gas temperature between adjacent zones is always higher or lower than the temperature of the processing material passing through, and the processing material and circulating atmospheric gas are It is possible to efficiently exchange the amount of heat held by the material with the material, resulting in significant energy savings, and the material to be processed can be cooled along a predetermined cooling curve.

In addition, as in the second embodiment, if the atmospheric gas introduced into the pre-heating zone is heated by the combustion exhaust gas of the radiant tube and the temperature-lowering atmosphere of the pre-heating zone is introduced from the starting end of the pre-heating zone to the terminal end of the cooling zone, it is possible to further increase the temperature. The preheating effect and the consumption of protective atmosphere can be reduced.

Note that the atmospheric temperature in the cooling zone C is adjusted by the circulating gas control damper 14, cooling air introduction dampers (not shown) provided in the first to third zones 6a to 6C of the cooling zone C, and heating means provided as necessary. The processing material is cooled along a predetermined cooling curve.

[Brief explanation of drawings]

Fig. 1 is a plan view of the heat exchange type continuous heat treatment furnace of the present invention, Fig. 2 is a longitudinal sectional view, Fig. 3 is a graph showing the relationship between ambient gas temperature and processing material temperature, and Fig. 4 is a graph showing the relationship between ambient gas temperature and processing material temperature. ”H6b
+6C” Zone, 7...Convection fan, 8,9...
・Duct, 15...Radiant tube, 17...
Heat exchanger, A... preheating zone, B... heating zone, C...
cooling zone.

Claims (2)

[Claims] (1) In a continuous heat treatment furnace in which a preheating zone and a cooling zone are connected to a high temperature treatment zone equipped with a heating means, the preheating zone and the cooling zone are divided into multiple zones equipped with convection fans on the ceiling, and A heat exchange type characterized in that the terminal zone of the preheating zone and the starting zone of the cooling zone are connected through a duct, and the atmospheric gas in the cooling zone is caused to flow from the cooling zone starting zone to the preheating zone termination zone and the preheating zone starting zone. Continuous heat treatment furnace. (2) In a continuous heat treatment furnace in which a preheating zone and a cooling zone are connected to a high temperature treatment zone equipped with a heating means, the preheating zone and the cooling zone are divided into multiple zones equipped with convection fans on the ceiling, and The terminal zone of the pre-cooling zone and the starting zone of the cooling zone are connected by a duct, and the final zone of the cooling zone and the starting zone of the pre-cooling zone are connected by a duct, so that atmospheric gas between the cooling zone and the pre-cooling zone is communicated. , a heat exchange type continuous heat treatment furnace characterized in that circulation is carried out from a cooling zone starting zone to a preheating zone ending zone, through the preheating zone starting zone, and then to a cooling zone ending zone.