JPS6286127A - Control device for preheating or continuous heat treatment furnace - Google Patents

Abstract

PURPOSE:To make the preheating temp. of a metallic strip uniform and constant in the transverse direction thereof with the titled furnace which makes use of the waste heat of heating and holding zones by controlling the fluid ejection rate and the heating temp. of a heater for preheating the metallic strip by ejection and contact heat transfer. CONSTITUTION:The metallic strip (sheet) 3 is wound on the outside surface of heating rolls 2 in the preheating furnace 1 and is fed into a heating furnace 28. A fluid heat medium is kept circulated and is heated in a heat exchanger 15 by the waste combustion gas of the holding zone C and is heated by the heater 18 in the stage of preheating the sheet 3 in the preheating zone A. The heated medium is passed in the rolls 2 respectively to heat the rolls. On the other hand, the fluid gas in the furnace 1 is kept circulated and is heated by the waste combustion gas of the heating zone B in a heat exchanger 8 and is heated by a heater 12. The heated gas is ejected to the sheet 3 wound on the rolls 2 respectively. The temp. distribution in the transverse direction of the wound sheet 3 is detected by temp. distribution detectors 21a-2e and the signals thereof are inputted to temp. indicating controllers 22a'22e to control the air flow rate in the transverse direction of the sheet 3. A preheating temp. detector 24 detects the temp. of the sheet 3 near the outlet of the furnace 1. The combustion temp. of the heaters 12, 18 are similarly controlled by temp. indicating controllers 25, 26.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a preheating control device in a continuous heat treatment furnace for heat treating metal strip.

<Prior Art> To heat a metal strip in a continuous heat treatment furnace, radiation heat transfer using a radiant tube or the like, nozzle jet heat transfer using a gas jet or the like, contact heat transfer using a heating roll or the like are utilized. For preheating the metal strip in the preheating zone of a continuous heat treatment furnace, jet heat transfer or contact heat transfer using waste heat from heating 4i), soaking zone, cooling zone, etc. is often used.

In those that utilize jet heat transfer, the combustion waste gas from the radiant tubes in the heating zone and soaking zone is passed through a heat exchanger, the atmospheric waste is heated in the eight exchangers, and the heated atmospheric gas is transferred from the jet nozzle to the preheating zone. Some types spray on both sides of a metal strip that is being conveyed vertically by rolls.

On the other hand, those that utilize contact heat transfer use a burner to heat the inside of a heating roll around which a metal strip is wound.
The heating roll in the preheating zone is heated by the waste heat of the cooling zone by circulating a fluid heat medium between the cooling roll in the cooling zone and the heating roll in the preheating zone, and the inside of the heating roll is uneven in the roll axis direction. There are some that use heating induction coils with a high winding density.

<Problems to be Solved by the Invention> In the jet heat transfer and contact heat transfer described above, the plate of the ejection nozzle is It is difficult to adjust the spray amount in the width direction and the temperature in the axial direction of the heating roll, making temperature control in the heating zone complicated. In other words, when a metal strip with a poor shape enters the preheating zone, with the center part in the width direction convex toward the injection nozzle, the center part is closer to the injection nozzle than both ends, and the central part There was a drawback that the metal strip was overheated and the temperature distribution in the width direction of the metal strip was uneven. Furthermore, when a heating roll is used, if the metal strip is warped in the width direction, only a portion of the metal strip comes into contact with the heating roll, resulting in poor heat transfer efficiency.

The present invention has been made to effectively solve the above-mentioned drawbacks, and is a preheating control for a continuous heat treatment furnace that can make the preheating temperature of the metal strip uniform in the width direction of the metal strip and maintain the metal meter at a constant temperature. The purpose of the present invention is to provide a device to improve the heat transfer efficiency of the heating roll by bringing the entire widthwise surface of the metal strip into uniform contact with the heating roll regardless of the shape of the metal strip, and to facilitate temperature control of the metal strip in the heating section. shall be.

<Means for Solving the Problems> The configuration of the present invention for achieving the above object is provided in a continuous heat treatment furnace for metal strips having a heating section consisting of a heating/soaking zone and a preheating section consisting of a preheating zone. A device for controlling the preheating temperature of the metal strip in the preheating section to a predetermined temperature, the heating roll being provided in the preheating section and winding the metal strip and heating the metal strip by contact heat transfer, and the heating roll. a fluid jet nozzle disposed toward the metal strip winding portion of the heating roll for spouting a high-temperature fluid onto the metal strap wound around the heating roll; and a first heating fluid for heating a fluid heating medium for heating the heating roll. a second heater for heating the fluid in the preheating zone and feeding the heated fluid to the fluid jet nozzle; and a second heater for heating the fluid in the preheating zone and feeding the heated fluid to the fluid jet nozzle, and a second heater for heating the fluid in the preheating zone and feeding the heated fluid to the fluid jet nozzle; Multiple t! ! Temperature distribution detectors are arranged in parallel, and a first temperature indicator trip is installed in the plate passing section to control the daily amount of fluid of the fluid jet nozzle based on the detection signal of the temperature distribution detector, and the temperature of the metal strip is adjusted. A preheating temperature detector to detect, and a first temperature to control the heating temperature in the first heater and the second heater, or the first heater or the second heater based on the detection signal of the preheating temperature detector. It is characterized by being equipped with an indicating controller.

<Function> The temperature of the heating roll is raised via the first heater and the fluid heating medium, and the metal strip is wound around the heated heating roll to preheat the metal strip by contact heat transfer. The fluid in the preheating zone is heated through a second heater, the heated fluid is sent to a fluid jet nozzle, and the heated fluid is injected from the fluid jet nozzle onto a metal strip wound around a heating roll. Perform injection heat transfer. The temperature in the width direction of the metal strap wound around the heating roll is detected by multiple temperature distribution detectors, and the first temperature indicating regulator is controlled based on the temperature detected by the temperature distribution detectors to adjust the fluid jet flow rate of the fluid jet nozzle. The fluid temperature is adjusted to make the temperature uniform across the width of the metal strip, and the jet pressure of the fluid jet nozzle helps tension the metal strip in the longitudinal direction to bring the metal strip into complete contact with the heating roller. On the other hand, the temperature of the metal strip at the outlet of the preheating furnace is detected by a preheating temperature detector, and the second temperature indicating regulator is controlled based on the temperature detected by the preheating temperature detector, and the first heater and the second heater heat the metal strip. Adjust the temperature to keep the preheating temperature of the metal strip constant.

<Example> Fig. 1 shows the structural concept of a continuous heat treatment furnace equipped with a preheating control device δ according to the first embodiment of the present invention, and Fig. 2 shows a partially broken side view of the heating roll part in Fig. 1. , m3 figure shows 1 in figure 2.
-■ line arrow view, FIG. 4 shows the structural concept of an a-class heat treatment furnace equipped with a preheating control device according to a second embodiment of the present invention.

As shown in FIG. 1, a pair of upper and lower heating rolls 2 are installed in the preheating furnace 1, and a fluid jet nozzle 4 is installed in the preheating furnace 1 facing the winding portion of the metal strip 3 of the heating roll 2. There is. The upper fluid jet nozzle 4 is arranged to penetrate the furnace wall of the preheating furnace 1 and circulate the fluid in the preheating furnace 1 through a first gas circulation furnace 5, a fan 6, and a damper 7, and then a first heat exchanger 8. The lower fluid jet nozzle 4 is connected to a second gas Wl ring furnace 9 and a fan 10 which are disposed through the furnace wall of the preheating furnace 1 and circulate the fluid in the preheating furnace 1.
, are connected to a second heater 12 via a damper 11. On the other hand, the upper heating roll 2 passes through the furnace wall of the preheating furnace 1 and passes through a first heating medium circulation path 13 and a pump 14 for circulating a fluid heating medium of molten fn':J, for example, to a second heating roll 2. The lower heating roll 2 is connected to the heat exchanger 15 and is connected to the preheating furnace l.
It is connected to the first heater 18 via the second heat medium circulation path 1B and the pump 17, which are disposed through the furnace wall. In the figure, 19.20 is a molten salt 7 cumulate tank. .

As shown in Fig. 2.3, in the heating roll 2 part, a hollow roll 2a is supported by a bearing 2b, and a rotary joint 2c attached to the shaft of the hollow roll 2a connects the first (second) heat medium to the ring. It is connected to road 13 (18). The fluid jet nozzle 4 includes a header 4d, a nozzle 4b that is attached to the surface of the header 4a facing the hollow roll 2a (the metal strip 3 winding part of the heating roll 2), and has a slit-like opening in the axial direction of the hollow roll 2a. The back surface of the header 4a is connected to the first (second) gas circulation path 5 (8) via a damper 7 (11). The damper 7 (11) has internal blades 7a to 7e (lla to 1le) and a partition plate 7F.
(Ilf) and a feather? a ~ 7e (Ila
~1ie) By setting the opening degree to yJffi, the air volume can be arbitrarily adjusted in the width direction of the metal strip 3. Temperature distribution detectors 21a to 2 are installed in the axial direction of the heating roll 2 on the downstream side of the passing portion of the metal strip 3 near the heating roll 2.
1e are arranged in parallel, and the temperature distribution detectors 21a to 21e are connected to the first temperature indicating regulators 22a to 22e. The first temperature indicating regulators 22a to 22e are opening degree regulating devices 23a to 2.
Damper 7 (11) blade via 3e? a ~7e(+
la ~ 1le), and temperature distribution detectors 21a ~
Based on the detection signal of 21e, the blades 7a to 7e (11a to 1
Perform the opening adjustment in step 1e).

- On the other hand, a preheating temperature sensor 24 for the metal strip 3 is connected to a second temperature indicating regulator 25, 26 at a passing portion of the metal strip 3 near the outlet 1 in the preheating furnace 1.

The second temperature indicating regulator 25 is connected to the second heater 12 , the second temperature indicating regulator 26 is coupled to the first heater 18 , and the second temperature indicating regulator 25 , 26 is connected to the preheating temperature detector 24 . The heating temperatures of the second heater 12 and the first heater 18 are controlled based on the detection signal.

The preheating zone A is configured by the above.

A heating furnace 28 is connected to the preheating furnace 1 by a connecting furnace 27, and a radiant tube 29 and a conveyance roll 30 are installed inside the heating furnace 28. A gas combustion device (not shown) of the radiant tube 29 is installed outside the heating furnace 28, and a heating zone B is configured by 0 or more gas combustion devices connected to the first heat exchanger 8 via an exhaust gas path (not shown). There is.

A soaking furnace 31 is connected to the heating furnace 28 by a connecting furnace 34, and a radiant tube 32 and a conveyance roll 33 are installed inside the soaking furnace 31. A gas combustion device (not shown) of the radiant tube 32 is installed outside the soaking furnace 31, and the gas combustion device is charged through an exhaust gas path (not shown).
A cooling furnace (not shown) is connected to the soaking furnace 31 by a connection cutter 33, and a soaking zone C is formed by 0 or more.

Next, the operation of the '1f1 continuous heat treatment furnace equipped with the preheating control device configured as described above will be explained.

The metal strip 3 is fed into the preheating furnace 1, the metal strip 3 is wound around the outer surface of the heating roll 2, and the metal strip 3 is fed into the heating furnace 2 through the connecting cut 27. Then, the metal strip 3 is transferred to the rank ant tube 2 by a conveyor roll 30.
660 with the radiant heat of the radiant tube 29 through the plate between 3
It is heated to ~850°C and sent to the soaking furnace 31.

When preheating the metal slip 3 in the preheating zone A, for example, salt mixed with NaNO2, NaNO3, KNO3, etc. having a melting point of 140° C. is melted in a melting device (not shown), and the molten fluid (fluid heating medium) is passed through the first heating medium circulation path. 13 and the second heat medium circulation path 16. The fluid heat medium supplied to the first heat medium circulation path 13 is circulated within the first heat medium circulation path 13 by the pump 14, and is heated by exchanging heat with the combustion exhaust gas of the radiant tube 32 in the second heat exchanger 15. Then, the heated fluid heat medium is passed through the hollow roll 2a of the heating roll 2 to heat the heating roll 2. The fluid heat medium supplied to the second heat medium circulation path 16 is
The temperature is raised to an appropriate temperature by the first heater 18 while pumping 17 through the second heating medium circulation path IB, and the heated fluid heating medium is passed through the hollow roll 2a of the heating roll 2.
heat up. - On the other hand, the fluid gas in the preheating furnace 1 is heated by exchanging heat with the combustion exhaust gas of the radiant tube 28 in the first heat exchanger 8 while circulating through the first gas circulation path 5, and the heated fluid gas is passed through the fan. 6 into the header 4a of the fluid jet nozzle 4, and the heated fluid gas is injected from the nozzle 4b onto the outer surface of the metal strip 3 wound around the heating roll 2. Further, the fluid gas in the preheating furnace 1 is heated to an appropriate temperature by the second heater 12 while circulating through the second gas circulation path 9, and the heated fluid gas is sent to the header 4 of the fluid jet nozzle 4 by the fan 10.
a, and the heated fluid gas is injected onto the outer surface of the metal strip 3 wound around the heating roll 2.

The temperature distribution detectors 21a to 21e detect the temperature distribution in the width direction of the metal strip 3 wound around the heating roll 2, that is, the occurrence of non-contact with the heating roll 2 due to warping of the metal strip 3, etc. The detection signal is input to the first temperature indicating regulators 22a to 22e. The first temperature indicating regulators 22a to 22e control the blades 7a to 7e (I la to 1
1e) is adjusted to adjust the amount of the metal strip 3 in the width direction of the metal strip 3, so that the temperature distribution of the metal strip 3 in the width direction of the metal strip is made uniform and the entire surface of the metal strip 3 is brought into contact with the outer surface of the heating roll 2.

The preheating temperature detector 24 also detects the temperature of the metal strip 3 near the outlet of the preheating furnace 1, and this detection signal is input to the second temperature indicating regulator 25,26. The second temperature indicating regulator 25 adjusts the combustion temperature of the second heater 12 based on the detection signal of the preheating temperature detector 24, and adjusts the temperature of the gas sent to the fluid jet nozzle 4 below. The second temperature indicating regulator 2B adjusts the preheating salting temperature and adjusts the temperature of the fluid heating medium that heats the heating roll 2 below. By adjusting the temperature of the gas fed into the fluid jet nozzle 4 and the temperature of the fluid heating medium heating the heating roll 2, the preheating temperature of the metal strip 3 is maintained at 150 to 300 degrees.

Therefore, even if the metal strip 3 is warped in the width direction, the fluid gas injection is controlled so that the temperature in the width direction is uniform. Contact heat transfer takes place. In addition, preheating furnace 1
Since the fluid gas injected to the metal strip 3 and the combustion temperature of the first heater 18 and second heater 12 that heat the heating roll 2 are controlled based on the temperature of the metal strip 3 near the exit of the The metal strip 3 is always kept at a constant preheating temperature.

In addition, as another embodiment, for example, as shown in FIG. 4, the upper heating roll 2 and the first heater 18 are connected, and the lower heating roll 2 and the second heat exchanger 15 are connected. The structure shown in FIG. 4 is not limited to the configuration shown in FIG.
5 is a safety valve.

<Effects of the Invention> The continuous heat treatment furnace preheating control device of the present invention can make the preheating temperature of the metal strip uniform in the width direction of the metal strip, and can also maintain the temperature of the metal strip constant. As a result, regardless of the shape of the metal strip, it is possible to bring the entire widthwise surface into contact with the heating roll to improve the heat transfer efficiency of the heating roll and to facilitate temperature control of the metal strip in the heating section.

[Brief explanation of drawings]

FIG. 1 is a structural conceptual diagram of a continuous heat treatment furnace equipped with a preheating control device according to the first embodiment of the present invention, FIG. 2 is a partially cutaway side view of the heating roll section in FIG. 1, and FIG. ■-m in Figure 2
4 is a conceptual structural diagram of a continuous heat treatment furnace equipped with a preheating control device according to a second embodiment of the present invention. With the symbols in the figure, 1... Preheating furnace, 2... Heating roll, 3... Metal strip, 4... Fluid jet nozzle, 8... First heat exchanger, 12... No. Second heater, 15...Second heat exchanger, 18...First heater, 21a to 21e...
・Temperature distribution detector, 22a to 22e...First temperature indicating regulator, 24...Preheating temperature detector, 25.26...
Second temperature indicating regulator, 28... Heating furnace, 31... Soaking furnace, A... Pre-heating zone, B... Heating zone, C... Soaking zone.

Claims (1)

[Claims] A device for controlling the preheating temperature of the metal strip in the preheating section to a predetermined temperature, which is installed in a continuous heat treatment furnace for metal strips and has a heating section consisting of a heating/soaking zone and a preheating section consisting of a preheating zone. a heating roll for winding the metal strip and heating the metal strip by contact heat transfer, and a heating roll for heating the metal strip by contact heat transfer; a fluid jet nozzle that spouts fluid; a first heater that heats a fluid heating medium for heating the heating roll; and a first heater that heats the fluid in the preheating zone and supplies the heated fluid to the fluid jet nozzle. a second heater for heating the metal strip; a plurality of temperature distribution detectors arranged in parallel in the axial direction of the heating roll on the downstream side of the metal strip passing section near the heating roll; a first temperature indicating regulator that controls the amount of fluid ejected from the nozzle; a preheating temperature detector that is installed in a metal strip passing section near the outlet of the preheating furnace and detects the temperature of the metal strip; and a preheating temperature detector that detects the temperature of the metal strip. Preheating control of a continuous heat treatment furnace comprising the first heater and the second heater or a second temperature indicating regulator that controls the heating temperature in the first heater or the second heater based on the detection signal of the furnace. Device.