JPH0332518Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a direct-fired metal strip heat treatment furnace.

(Conventional technology and its problems) Conventionally, in a direct-fire metal strip heat treatment furnace equipped with a heating zone and a cooling zone, the exhaust gas generated in the heating zone is cooled and used as an atmosphere in the cooling zone. .

By the way, when replacing the metal strip or when the line is stopped, the metal strip remains in the furnace, so the combustion amount of the burner is reduced in order to prevent the metal strip from overheating. In this way, when the amount of combustion decreases, the amount of exhaust gas generated decreases, and when the atmosphere in the heating zone is circulated to the cooling zone in this state, the pressure inside the furnace decreases, outside air enters the furnace, and the metal strip In some cases, the ratio of CO and H ₂ in the reactor exceeds the explosion limit, creating a risk of explosion.

To solve this problem, the burner should be fired so that the pressure inside the furnace does not drop below a predetermined value, but that wastes fuel. It is also conceivable to provide another cooling atmosphere generating device in the cooling zone to supply an atmosphere to the cooling zone, but this has the same problems as above in that fuel is wasted and the equipment cost increases.

Focusing on the fact that during regular furnace operation, the amount of exhaust gas generated from the heating zone is greater than the amount used in the cooling zone, this invention temporarily stores the excess exhaust gas generated in the heating zone and The object of the present invention is to provide a direct-fired metal strip heat treatment furnace that uses this stored exhaust gas when the system is shut down.

(Means to Solve the Problems) In order to achieve the above object, the present invention provides a heat treatment furnace equipped with a heating zone for heating a metal strip with an open flame and a cooling zone for cooling the heated strip. a flow path for cooling the exhaust gas in the heating zone and supplying it to the cooling zone; a storage tank for pressurizing and storing excess cooling exhaust gas; , a flow path for supplying the stored exhaust gas in the storage tank to at least one of the heating zone and the cooling zone, and an adjustment device for adjusting the supply amount of the stored exhaust gas based on the furnace internal pressure. .

(Example) Next, the present invention will be explained with reference to the drawings which are one example.

The direct-fired metal strip heat treatment furnace T consists of a heating zone 1 having a direct-fired burner 2 and a cooling zone 3.

A flow path 8 equipped with a cooling device 5, a control valve 6 operated by the furnace pressure regulator 4 of the heating zone 1, and a blower 7 is provided between the heating zone 1 and the cooling zone 3. .

Further, downstream of the blower 7 in the flow path 8, a flow path 9 that communicates with the cooling zone 3 is branched, and this flow path 9 includes a shutoff valve 10, a booster 11, a storage tank 12, a pressure reducing Valve 13, control valve 14
These shutoff valve 10, booster 11, and control valve 14 are controlled by a controller 15, which will be described below. Note that downstream of the control valve 14 in the flow path 9, a branch flow path 9a having a control valve 14a is provided, and communicates with the heating zone 1.

The controller 15 detects the furnace pressure in the cooling zone 3 with a furnace pressure detector 16, and when the furnace pressure in the cooling zone 3 exceeds a predetermined value, the controller 15 opens the shutoff valve 10 and closes the control valve 14. , the booster 11 is driven, and conversely, when the furnace pressure in the cooling zone 3 falls below a predetermined value, the shutoff valve 10 is closed, the control valve 14 is opened, the booster 11 is stopped, and the pressure inside the storage tank 12 is The stored exhaust gas is supplied to the cooling zone 3. In this case, the control valve 14a may also be opened or closed.

17 is a recoiler of metal strip S, and 18 is a coiler.

Therefore, when the burner 2 is burned and the furnace pressure in the heating zone 1 increases, the control valve 6 is opened, and the high temperature exhaust gas in the heating zone 1 is cooled to a predetermined temperature by the cooling device 5, and then the blower 7 to the cooling zone 3 via a flow path 8 as an atmospheric gas.

When the furnace pressure detector 16 detects that the furnace pressure in the cooling zone 3 is equal to or higher than a predetermined value, the controller 1
The shutoff valve 10 is opened by the command from 5, and
The booster 11 operates to boost the pressure and store a portion of the exhaust gas in the storage tank 12 .

After that, when the line stops and the combustion amount of the burner 2 decreases, the blower 7 is still operating, so
At the same time as the furnace pressure in the heating zone 1 decreases and the control valve 6 closes, the blower 7 stops. As a result, the furnace pressure in the cooling zone 3 is reduced.

When the furnace pressure detector 16 detects this decrease in the pressure inside the furnace, in response to a command from the controller 15, the shutoff valve 10 is closed, the booster 11 is stopped, and the control valve 14 is opened at the same time as the storage tank 12. The exhaust gas inside the furnace is supplied to the cooling zone 3, thereby preventing a drop in the pressure inside the furnace.

In addition, since the line stop time is generally within about 10 minutes and the burner operating time is 1 to 3 hours, the storage tank 12 may be relatively small.

(Effects of the invention) As is clear from the above explanation, the direct-fired metal strip heat treatment furnace according to the invention can maintain the furnace internal pressure when the line is stopped, and store the combustion exhaust gas in the storage tank during steady operation. This is done by releasing the atmospheric gas in advance when the pressure inside the furnace decreases, and does not require a special atmosphere gas generator, so it is possible to achieve the intended purpose at low cost.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a direct-fired metal strip heat treatment furnace according to the present invention. 1... Heating zone, 2... Burner, 3... Cooling zone,
5... Cooling device, 6, 14, 14a... Control valve, 7... Blower, 8, 9, 9a... Channel, 10... Shutoff valve, 11... Booster, 12...
Storage tank, 15...controller, S...metal strip.

Claims (1)

[Scope of claims for utility model registration] (1) A heating zone for heating a metal strip with an open flame;
A heat treatment furnace equipped with a cooling zone for cooling the heated strip, a flow path for cooling the exhaust gas in the heating zone and supplying it to the cooling zone, a storage tank for pressurizing and storing excess cooling exhaust gas, and A flow path for supplying the stored exhaust gas in the storage tank to at least one of the heating zone and the cooling zone so as to maintain the furnace internal pressure at a predetermined value or higher during low-temperature firing in the heating zone; A direct-fired metal strip heat treatment furnace, characterized in that it is equipped with an adjustment device for adjusting the amount of exhaust gas supplied. (2) The direct-fired metal strip heat treatment furnace according to claim 1, wherein the adjustment device is provided in each of the supply channels to the cooling zone and the heating zone.