JPS638169B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous heat treatment furnace for metal strip.

Conventionally, in continuous heat treatment furnaces for metal strips, the metal strips are heated and soaked to a predetermined temperature.
After that, heat treatment is performed by cooling,
Sensible heat released from the treated material during the cooling process was directly dissipated into the atmosphere, resulting in a large loss of energy.

Therefore, in order to improve the energy loss in the continuous heat treatment furnace for metal strips of the above-mentioned type, the applicant proposed a heat exchange zone (preheating and precooling) for preheating and precooling the metal strips in Japanese Patent Application No. 112328/1983. A pre-cooling zone) and a heating/soaking zone are separated by a partition wall arranged in the width direction of the furnace, and the metal strip is conveyed in opposite directions in the heat exchange zone, and heat is exchanged on both sides of the running metal strip in the heat exchange zone. A nozzle header for injecting a belt of atmospheric gas, an atmosphere supply duct for the nozzle header, and a circulation fan are provided,
We have proposed a continuous heat treatment furnace for metal strips that can save energy by using the sensible heat released from the metal strips during precooling for preheating.

However, in the continuous heat treatment furnace for metal strips, the heat curve is adjusted by increasing or decreasing the heat transfer coefficient by adjusting the air volume of the circulation fan, but there is a limit to this increase or decrease, and it depends on the steel type. However, it has the disadvantage that it cannot be used in cases where rapid cooling or heating is required.

The present invention was made in order to eliminate the drawbacks of the continuous heat treatment furnace for metal strips.
At least a part of the precooling zone (heat exchange zone) is partitioned by a partition wall to form a partitioned preheating chamber and a partitioned precooling chamber, and a heater is provided on the suction side of a circulation fan for a jet nozzle header provided in the partitioned preheating chamber. The compartment pre-cooling chamber atmosphere suction duct and the compartment pre-cooling chamber atmosphere suction duct are connected, and the compartment pre-cooling chamber atmosphere suction duct and the compartment pre-cooling chamber atmosphere suction duct have a cooler on the suction side of the circulation fan for the jet nozzle header provided in the compartment pre-cooling chamber. The purpose of the present invention is to provide a continuous heat treatment furnace for metal strips that is connected to a duct and can handle wide changes in the heat curve by changing the atmosphere circulation path by operating an opening/closing damper provided in the suction duct. shall be.

Next, the present invention will be explained with reference to drawings which are embodiments.

FIG. 1 shows a schematic cross-sectional view of a heat treatment furnace 1 for metal strip according to the present invention. Inside the furnace body 2, the metal strip is preheated by a partition wall 3 disposed in the width direction of the furnace, and after heating and soaking, the metal strip is preheated. It is divided into a preheating/precooling zone (heat exchange zone) 4 for cooling the metal strip and a heating/soaking zone 5, and the heating/soaking zone 5 is provided in the furnace length direction with an end space 6 left. The preheating/precooling zone 4 is partitioned into a plurality of preheating/precooling chambers 11 by a plurality of partition walls 10 in the width direction of the furnace, One preheating/precooling chamber 11 is
The furnace is divided into a precooling chamber 11a and a preheating chamber 11b by a partition wall 19 extending in the furnace length direction. Note that the partition walls 10 other than the partition wall 7 and the partition wall 10 forming the partition precooling chamber 11a and the partition preheating chamber 11b
does not necessarily need to be provided.

Then, the metal strip W is connected to the partition wall 1.
0, the lower part of the preheating/precooling chamber 11 is conveyed in the direction of the arrow through the U-shaped conveyance path P formed by the opening a provided in the partition wall 3, the support roll 12 provided in the heating/soaking zone 5, and the reversing roll 13. is preheated and heated/
It is heated to a predetermined temperature in the soaking zone 5 and precooled in the upper part for heat treatment.

Further, the partition wall 19 of the preheating/precooling chamber 11
As shown in FIG. 2, a pair of jet nozzle headers 15a, 15b and a circulation fan 16 are provided in the areas where nozzles are provided, as shown in FIG.
A common atmosphere supply duct 17 having a
The atmospheric gas in the preheating/precooling chamber 11 is sucked and pressurized by the circulation fan 16 to each jet nozzle header 15.
It is sprayed onto the front and back surfaces of the metal strip W conveyed from a and 15b to pre-cool or pre-heat the metal strip W and to support it in a floating manner. Note that 14 is a conventionally known cooling zone.

As shown in FIG. 3, a pair of jet nozzle headers 20a and 20b are provided in the compartment precooling chamber 11a and the compartment preheating chamber 11b, which are separated by the division wall 19, with each conveyance path P in between. The jet nozzle header 20a of the precooling chamber 11a communicates with the compartment preheating chamber 11b, and the jet nozzle header 20b of the compartment preheating chamber 11b communicates with the compartment precooling chamber 11a through suction ducts 21a, 21b via jet nozzle header circulation fans 22a, 22b, respectively. ing. In addition, a suction duct 24 with a built-in cooler 23 is provided in the pre-cooling chamber 11a, and a suction duct 26 with a built-in heater 25 is provided in the pre-heating chamber 11b. Connected to the suction side. Note that 27a, 27b, 28a, and 28b are dampers.

Next, the operation of the heat treatment furnace having the above configuration will be explained.

First, place the metal strip W into the furnace 1 as shown in Figure 1.
Heater 18 and circulation fan 1 for preheating/precooling zone (heat exchange zone) 4 and heating/soaking zone 5
6, 22a, and 22b are operated to raise the temperature of each preheating/precooling chamber 11 and heating/soaking zone 5 to a predetermined temperature. Note that the dampers 27a, 28a
is open, dampers 27b and 28b are closed, and cooler 23 and heater 25 are stopped. and,
When the furnace 1 is ready for operation, the metal strip W is continuously transported and heat treated, and after confirming a steady state, the heater 18 of the preheating/precooling zone 4 is turned off.

Note that the heater 18 of the preheating/precooling zone 4 is intended to raise the temperature to a steady temperature that allows continuous operation at an early stage to improve operational efficiency, but it is not necessarily necessary to provide it.

Metal strip W that is continuously conveyed inside the furnace 1
passes through the preheating/precooling zone 4, is transported to the heating/soaking zone 5, is heated and soaked to a predetermined temperature by the heater 18, and enters the preheating/precooling zone 4 again. In the preheating/precooling zone 4, the metal strip Wa that has become high temperature in the heating/soaking zone 5 passes through the metal strip Wb below.
By exchanging heat as described below, the lower metal strip Wb is preheated, while itself is precooled.

That is, the atmospheric gas at the temperature Tg in the preheating/precooling chamber 11 is transferred to the duct 17 by the circulation fan 16.
Then, it is injected from the upper nozzle header pair 15a onto the front and back surfaces of the high-temperature metal strip Wa, absorbing sensible heat from the metal strip Wa, and raising the temperature to TgH. On the other hand, the atmospheric gas at the temperature Tg injected from the lower nozzle header pair 15b passes through the metal strip Wb.
gives heat to the temperature, and the temperature drops to TgC. and,
As mentioned above, the atmospheric gases at temperatures TgH and TgC that have undergone heat exchange with the metal strip W are suction-mixed by the circulation fan 16 to become atmospheric gas at temperature Tg.
The heat exchange described above will be repeated (see Figure 5).
The heat exchange action in each preheating/precooling chamber 11 is exactly the same except that the atmospheric gas temperature Tg increases toward the heating/soaking zone 5 side.

Therefore, for example, the metal strip W at 20°C charged from the charging port 2a is gradually preheated to 700°C in the lower part of the preheating/precooling zone 4, and then heated and maintained at 1000°C in the heating/soaking zone 5. and then preheat and
It is gradually precooled to 300°C in the upper part of the precooling zone 4, and reaches a known cooling zone 14 from the extraction port 2b, where it
It will be extracted after being cooled to 200℃ (6th
(see figure).

Next, when it is necessary to change the heat curve due to a change in the steel type, etc., and rapidly heat and cool the metal strip, the dampers 27a and 28a are closed, and the dampers 27b and 28b are While opening the cooler 2
3 and the heater 25. In other words, the precooling chamber 11a and the preheating chamber 11b are independent, and the atmosphere cooled by the cooler 23 is injected from the pair of nozzle headers 15a of the precooling chamber 11a, while the pair of nozzle headers 1
Atmosphere heated by the heater 25 is injected from 5b, rapidly cooling the metal strip Wa and rapidly heating the metal strip Wb.

The atmosphere circulation means and switching means provided in the section precooling chamber 11a and the section preheating chamber 11b are not limited to those shown in FIG. 3, but may be of various types. For example, FIGS. 7 and 8 show the suction duct 2
One damper 29 is provided at the confluence point of suction ducts 21a and 24, and FIG.
A plurality of dampers 29 are provided in each of the dampers 4. In addition, as shown in FIG. 10, the suction duct 2
It is also possible to provide a cooler 23 only in a part of the air conditioner 4 and to bypass a part of the atmosphere.
Although one of the circulation paths has been described in FIGS. 7 to 10, the other circulation path is provided with a heater 25 instead of the cooler 23.

In the above embodiment, the present invention was applied to a horizontal furnace, but a vertical furnace may also be used, and the in-furnace conveying means is not limited to the above embodiment, and the entire area may be a floater type, A roller method, a catenary method, or a combination thereof may be used. In addition, the heating method in the heating/soaking zone 5 may of course be side radiation heating, or convection heating in some cases. Any location is fine.

As is clear from the above explanation, according to the present invention, the heat source for preheating the metal strip is basically the amount of heat released by the high temperature metal strip after leaving the heating/soaking zone, and the heat source from the outside. Since no energy is required, the fuel consumption rate for conventional methods is 25%.
×10 ⁴ Kcal/Ton with a furnace efficiency of 70%, in the present invention, the furnace efficiency was improved to 12.8 × 10 ⁴ Kcal/Ton and 140%. Furthermore, the amount of cooling water conventionally used in the cooling zone can be greatly reduced.

Furthermore, in the present invention, an independent compartment is provided in at least a part of the preheating/precooling zone, a cooler or a heater is provided in the suction duct of this compartment,
Since the metal strip can be rapidly heated or cooled by the damper operation, the heat curve can be changed freely, and various types of heat treatments can be performed on the metal strip.

Moreover, if a part of the preheating/precooling zone (heat exchange zone) is made to have a cooling chamber and a preheating chamber in the same space,
In this chamber, heat exchange by radiation between the upper and lower metal strips works to improve heat exchange efficiency, and only one circulation fan is required for convective heat exchange, which makes the structure simple and allows for inexpensive heat treatment. It also has the effect of being able to be used as a furnace.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a heat treatment furnace according to the present invention, FIG. 2 is a sectional view taken along the line - in FIG. 1, FIG. 3 is a sectional view taken along the line - in FIG. A cross-sectional view when the chamber is an independent chamber, Figure 5 is a principle diagram of the heat exchange action of the heat exchange zone, Figure 6 is the heat curve of the heat treatment furnace under normal conditions, and Figures 7 to 10.
This figure is an explanatory sectional view of a one-way portion showing a modification of FIG. 3. 2...furnace body, 3...partition wall, 4...preheating/precooling zone (heat exchange zone), 5...heating/soaking zone, 10...
...Division wall, 11... Preheating/precooling room (heat exchange room),
11a, 11b...Division chamber (division precooling chamber, division preheating chamber), 15a, 15b, 20a, 20b...Nozzle header, 16, 22a, 22b...Circulation fan, 17...Duct, 21a, 21b, 24, 2
6... Suction duct, 23... Cooler, 25... Heater, 27a, 27b, 28a, 28b, 29...
...damper, W...metal strip.

Claims (1)

[Claims] 1. In a metal strip continuous heat treatment furnace in which a preheating/precooling zone and a heating/soaking zone are separated by a partition wall arranged in the width direction of the furnace, the sections arranged in the preheating/precooling zone in the width direction and furnace length direction. A compartment preheating chamber atmosphere suction duct and a compartment precooling chamber atmosphere suction duct which form at least one divisional preheating chamber and one divisional precooling chamber by walls, and each have a heater on the suction side of a circulation fan for a jet nozzle header provided in the divisional preheating chamber. At the same time, a compartment precooling chamber atmosphere suction duct having a cooler and a compartment preheating chamber atmosphere suction duct having a cooler are connected to the suction side of a circulation fan for a jet nozzle header provided in the compartment precooling chamber, and a compartment preheating chamber atmosphere suction duct provided in the suction duct is connected to A metal strip continuous heat treatment furnace characterized by changing the atmosphere circulation path by operating an opening/closing damper.