JPH11236625A - Apparatus for supplying gas in gas jet heating and cooling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas supplying apparatus in gas jet heating and cooling, in which hydrogen concn. in each gas jet is controlled so as to become a prescribed concn. and the temp. of a steel strip and the cooling speed can easily be controlled, in a gas jet heating and cooling device in a continuous annealing process. SOLUTION: In the apparatus for supplying the gas from a forcibly gas feeding device arranged at out of the furnace in the gas jet device constituting gas jet heating and cooling zones in the continuous annealing furnace of the steel strip, a hydrogen concn. detector and a flow rate meter arranged at the suction side of the forcibly gas feeding device and measuring the hydrogen concn. and the circulating gas flow rate in the atmosphere in the furnace, respectively, and a means for supplying a prescribed hydrogen and/or nitrogen gas into the forcibly gas feeding device from a hydrogen supplying hole and a nitrogen supplying hole, respectively, so that the gas spouted from the gas jet device becomes a prescribed hydrogen concn. and spouted gas flow rate based on these measured results, are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gas supply device for heating and cooling a steel strip in a continuous annealing furnace.

[0002]

2. Description of the Related Art Conventional gas jet cooling having a low hydrogen concentration is not suitable for rapid cooling of steel strip because of its low heat transfer coefficient. Therefore, in order to improve the heat transfer coefficient, attempts have been made to increase the gas discharge velocity and shorten the distance between the cooling nozzle and the steel strip. However, flapping and scratching of the steel strip are likely to occur. A problem has arisen that a presser roll must be installed in the machine. Therefore, for the purpose of rapid cooling with a high heat transfer coefficient, a cooling method using a high hydrogen concentration has been proposed (for example, Japanese Patent Application Laid-Open No. 6-34615).
No. 6, JP-B-55-1969).

[0003]

However, in the above-mentioned conventional method, as shown in FIG. 3, a sealing device is installed before and after a heating or cooling zone, and a predetermined amount of hydrogen or nitrogen is supplied into the furnace. The gas atmosphere is heated and cooled by circulating the atmosphere gas in the furnace as the hydrogen concentration, but has the following problems.

(1) In the case where the apparatus is constituted by a plurality of gas jet devices, the hydrogen concentration cannot be changed only by an arbitrary gas jet device (gas jet zone) in the conventional method. Also, even when a sealing device is provided before and after each gas jet device, it is difficult to control the concentration of the atmospheric gas due to the draft of the atmospheric gas and the inflow and outflow of gas into and from another gas jet device due to the accompanying flow of the steel strip. Met.

[0005] Therefore, it has been difficult to produce a high-strength steel strip and a general soft material in the same gas jet cooling zone. (2) When the hydrogen concentration is changed during normal operation, if it is composed of a plurality of gas jet devices, the hydrogen is supplied throughout the furnace due to the position of the hydrogen or nitrogen supply port in the furnace and the accessories in the furnace. Uniform mixing with gas is unlikely to occur,
A concentration distribution occurs locally. Therefore, the concentration of the discharged gas in each gas jet device is not uniform, and may vary from device to device. Therefore, the heat transfer coefficient of each gas jet changes depending on time and place, and it is difficult to control the outlet temperature of the steel strip to be constant.

(3) When the hydrogen concentration is changed during normal operation, for example, when the thickness of a steel strip changes, there is an unsteady state in which the concentration changes to a predetermined hydrogen concentration. Causes delay. For example, furnace volume: 30
0 m ³ (4 m × 3 m × 25 m), furnace temperature: 500 ° C., when the hydrogen concentration in the furnace is changed from 5% by volume to 50% by volume, the hydrogen input amount Q = 300 Nm ³ / min.
There is an unsteady state for at least 15 seconds.

An object of the present invention is to solve the above-mentioned problems by controlling the hydrogen concentration in each gas jet to a predetermined concentration in a gas jet heating / cooling facility in a continuous annealing process, It is an object of the present invention to provide a gas jet heating / cooling gas supply device capable of easily controlling a steel strip temperature and a cooling rate.

[0008]

In order to solve the above problems and achieve the object, the present invention uses the following means. (1) The apparatus of the present invention is an apparatus for supplying gas to a gas jet apparatus constituting a gas jet heating / cooling zone of a steel strip continuous annealing furnace by using a gas pumping apparatus provided outside the furnace. Provided on the suction side of the device, a hydrogen concentration detector and a flow meter that respectively measure the hydrogen concentration in the furnace atmosphere and the circulating gas flow rate, and based on these measured values,
Means for supplying hydrogen gas from the hydrogen supply port and nitrogen gas from the nitrogen supply port to the gas pumping device in a predetermined amount so that the gas discharged from the gas jet device has a predetermined hydrogen concentration and a discharge gas flow rate. A gas supply device for heating / cooling a gas jet, comprising: (2) The apparatus of the present invention includes a plurality of gas jet apparatuses constituting a gas jet heating / cooling zone of a steel strip continuous annealing furnace,
In a device for supplying gas by a gas pumping device provided outside the furnace, a sealing device provided on an inlet side and an outlet side of each gas jet device and constituting an individual gas jet heating / cooling zone in the furnace, and each gas For each jet device, a hydrogen concentration detector and a flow meter are provided on the suction side of the gas pumping device and measure the hydrogen concentration and the circulating gas flow rate in the furnace atmosphere of each gas jet heating / cooling zone, respectively. A predetermined amount of hydrogen gas is supplied from the hydrogen supply port and a predetermined amount of nitrogen gas is supplied from the nitrogen supply port so that the gas discharged from the gas jet apparatus has a predetermined hydrogen concentration and a discharge gas flow rate based on the measured value of the gas jet apparatus. A gas supply device for heating / cooling the gas jet, comprising: means for supplying the gas to the device.

(3) In the apparatus according to the present invention, the hydrogen supply port and the nitrogen supply port are installed on the outlet side of the installation position of the hydrogen concentration detector and the flow meter in the gas pumping direction and on the suction side of the gas pumping apparatus. The gas supply device for heating / cooling a gas jet according to the above (1) or (2), characterized in that:

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, installed a hydrogen concentration detector and a flow meter on a gas pumping device (blower) suction side of a gas jet pumping pipe. It has been found that it is effective to supply each gas from the hydrogen supply port and the nitrogen supply port so that the discharge gas has a predetermined hydrogen concentration.

[0011] Based on this finding, the present inventors have provided for each gas jet device a suction side of a gas pressure-feeding device,
A hydrogen concentration detector and a flow meter that respectively measure the hydrogen concentration in the furnace atmosphere and the circulating gas flow rate, and based on these measured values, the gas discharged from the gas jet device has a predetermined hydrogen concentration and a discharge gas flow rate. In order to provide a means for supplying a predetermined amount of hydrogen and / or nitrogen gas to the gas pumping device from the hydrogen supply port and the nitrogen supply port, respectively, in the gas jet heating / cooling equipment of the continuous annealing process, By controlling the hydrogen concentration in each gas jet to be a predetermined concentration and finding a gas supply device in gas jet heating / cooling capable of easily controlling the steel strip temperature and the cooling rate, the present invention has been completed.

An embodiment of the present invention will be described below. (First Embodiment) A gas supply device for gas jet heating / cooling according to a first embodiment of the present invention includes a gas jet device constituting a gas jet heating / cooling zone of a continuous annealing furnace for steel strip, In a device for supplying gas by a provided gas pumping device, a hydrogen concentration detector and a flow meter are provided on the suction side of the gas pumping device and measure the hydrogen concentration in the furnace atmosphere and the circulating gas flow rate, respectively. A predetermined amount of hydrogen and / or nitrogen gas is supplied from the hydrogen supply port and the nitrogen supply port so that the gas discharged from the gas jet apparatus has a predetermined hydrogen concentration and a discharge gas flow rate based on the measurement value of the gas jet apparatus. Means for supplying to the pumping device.

That is, in the gas jet heating / cooling equipment of the continuous annealing process, a hydrogen concentration detector and a flow meter are installed on the gas pumping device (blower) suction side of the gas jet pumping pipe so that the discharge gas has a predetermined hydrogen concentration. Therefore, when each gas is supplied from the hydrogen supply port and the nitrogen supply port, considering the mixture of the supplied hydrogen and the nitrogen gas with the circulating gas, the hydrogen supply port and the nitrogen supply port are arranged in the gas pumping direction. On the other hand, when installed on the outlet side of the position where the hydrogen concentration detector and the flow meter are installed and on the suction side of the gas pumping device (blower), stirring and mixing are better, and it is difficult to generate a non-uniform mixing state of the atmospheric gas. .

With the above configuration, it is possible to instantaneously set an arbitrary hydrogen concentration in each gas jet heating / cooling device, and to delay the steel strip temperature control due to an unsteady state when the hydrogen concentration changes. And heating and cooling under a certain hydrogen concentration.

Further, when the cooling zone is composed of a plurality of gas jet cooling devices (GJ), for general soft materials, "first stage GJ: slow cooling by low concentration hydrogen + second stage GJ: rapid cooling by high concentration hydrogen" For high-tensile steel, "GJ: rapid cooling with high concentration hydrogen + rear GJ: rapid cooling with high concentration hydrogen"
Can be used instantaneously.

FIG. 1 is an explanatory view showing a cooling zone in a continuous annealing process of a steel strip to which a gas supply device according to a first embodiment of the present invention is applied.
The heated and soaked steel strip X is conveyed to cooling zones Y1 and Y2 provided with sealing devices on the inlet side and the outlet side of the cooling zone, and cooled to a predetermined steel strip temperature. The cooling zones Y1 and Y2 are constituted by gas jet cooling devices G1 and G2, and G3 and G4 for cooling by cooling and circulating the atmosphere gas in the furnace. FIG. 2 is an enlarged view of the gas jet cooling device G1. The atmosphere gas sucked from the furnace is cooled to a predetermined gas temperature by a gas cooler. At this time, each value is measured by a hydrogen concentration detector and a flow meter installed on the blower suction side. An operation is performed on the measured value so as to obtain a predetermined hydrogen concentration and a discharge gas flow rate, and the supply amount of hydrogen or nitrogen is determined. At this time, the gas temperature may be measured as shown in FIG. The hydrogen concentration detector, flow meter, and thermometer installed on the blower suction side have no problem even after the cooler. In addition, an oxygen concentration detector is installed on the blower suction or discharge side, and when the oxygen concentration exceeds a specified value, the supply of hydrogen is shut off urgently and nitrogen is supplied in an emergency. (Second Embodiment) A gas supply device for gas jet heating / cooling according to a second embodiment of the present invention comprises a plurality of gas jet devices constituting a gas jet heating / cooling zone of a continuous annealing furnace for a steel strip. In a device for supplying gas by a gas pumping device provided outside, a sealing device provided on an inlet side and an outlet side of each gas jet device and constituting an individual gas jet heating / cooling zone in a furnace; For each device, a hydrogen concentration detector and a flow meter are provided on the suction side of the gas pumping device and measure the hydrogen concentration and the circulating gas flow rate in the furnace atmosphere of each gas jet heating / cooling zone, respectively. Based on the measured values, a predetermined amount of hydrogen and / or nitrogen are respectively supplied from the hydrogen supply port and the nitrogen supply port so that the gas discharged from the gas jet apparatus has a predetermined hydrogen concentration and a discharge gas flow rate. The gas is characterized in that a means for supplying a gas pumping device.

FIG. 4 shows a configuration of a gas supply device according to a second embodiment of the present invention. The gas supply device in FIG. 4 further includes a sealing device between the gas jet cooling devices G1 and G2 and the gas jet cooling devices G3 and G4 to which the gas supply device configuration according to the first embodiment illustrated in FIG. 1 is applied. This is an example in which a cooling zone having four cooling zones (Y1 to Y4) by gas jet cooling is configured.

FIG. 5 is a diagram showing a sample No. by the gas supply device of FIG. It is a figure showing a cooling pattern in a cooling zone which has four cooling zones (Y1-Y4) of 1-4. Using the apparatus of FIG. By controlling the cooling patterns of the cooling zones 1 to 4 (Y1 to Y4), it becomes possible to heat-treat a general soft material or high-tensile steel as shown in FIG. That is, in the case of a general soft material, No. 1 and No. 1 In the cooling zone (Y1, Y2) of No. 2, slow cooling was performed with the discharge gas having a low hydrogen concentration. In the cooling zone (Y3) of No. 3, rapid cooling was performed by using a discharge gas having a high hydrogen concentration. In the cooling zone No. 4 (Y4), slow cooling is performed with a discharge gas having a low hydrogen concentration to cool to a predetermined steel strip temperature.

In the case of high tensile strength steel, In the cooling zones No. 1 to No. 3 (Y1 to Y3), rapid cooling was performed by using a discharge gas having a high hydrogen concentration. In the cooling zone No. 4, slow cooling is performed with a discharge gas having a low hydrogen concentration to cool to a predetermined steel strip temperature.

In the present invention, as shown in FIG. 6, a hydrogen concentration detector, a flow meter, and the like are further installed on the blower discharge side of the above-described gas supply device, and the difference from the calculated target value is measured. Then, feedback control may be performed.

[0021]

As described above, according to the present invention, in the gas jet heating / cooling equipment of the continuous annealing process, the hydrogen concentration detector and the flow meter are installed on the suction side of the gas pumping device (blower) provided outside the furnace. By installing and supplying each gas from the hydrogen supply port and the nitrogen supply port so that the discharge gas has a predetermined hydrogen concentration, (1) Instantaneous hydrogen concentration can be set to an arbitrary hydrogen concentration by each gas jet heating / cooling device. To prevent delay in steel strip temperature control due to unsteady state when hydrogen concentration changes,
It can be cooled under a constant hydrogen concentration.

(2) A plurality of gas jet cooling devices (G
J), the general soft material is referred to as “front G
J: Slow cooling with low-concentration hydrogen + second-stage GJ: rapid cooling with high-concentration hydrogen ”, and for high-tensile steel, instantly switch to“ front-stage GJ: rapid cooling with high-concentration hydrogen + rear-stage GJ: rapid cooling with high-concentration hydrogen ”. Will be able to do it.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a cooling zone configuration according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged view of the gas jet cooling device according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional cooling zone.

FIG. 4 is a diagram illustrating an example of a cooling zone configuration according to a second embodiment of the present invention.

FIG. 5 is a view showing an example of a cooling pattern according to a second embodiment of the present invention.

FIG. 6 is a diagram showing an example of a cooling zone configuration according to another embodiment of the present invention.

Claims (3)

[Claims] 1. A gas jet heater for a continuous annealing furnace for steel strip.
In a device for supplying gas to a gas jet device constituting a cooling zone by a gas pumping device provided outside the furnace, the device is provided on a suction side of the gas pumping device, and controls a hydrogen concentration in a furnace atmosphere and a circulating gas flow rate. A hydrogen concentration detector and a flow meter to be respectively measured, and based on these measured values, hydrogen gas is supplied from a hydrogen supply port so that a gas discharged from the gas jet device has a predetermined hydrogen concentration and a discharge gas flow rate. Means for supplying a predetermined amount of nitrogen gas from the nitrogen supply port to the gas pumping device, wherein the gas supply device in the gas jet heating and cooling. 2. A gas jet heater for a continuous annealing furnace for steel strip.
In a device for supplying gas to a plurality of gas jet devices constituting a cooling zone by a gas pumping device provided outside the furnace, individual gas jet heating is provided in the furnace provided on the inlet side and the outlet side of each gas jet device. A sealing device constituting a cooling zone;
For each gas jet device, a hydrogen concentration detector and a flow meter are provided on the suction side of the gas pumping device and respectively measure the hydrogen concentration and the circulating gas flow rate in the furnace atmosphere of each gas jet heating / cooling zone. , Based on these measurements,
Means for supplying hydrogen gas from the hydrogen supply port and nitrogen gas from the nitrogen supply port to the gas pumping device in a predetermined amount so that the gas discharged from the gas jet device has a predetermined hydrogen concentration and a discharge gas flow rate. A gas supply device for heating and cooling a gas jet, comprising: 3. The hydrogen supply port and the nitrogen supply port are installed on the outlet side of the hydrogen concentration detector and the flow meter installation position in the gas pumping direction and on the gas pumping device suction side. 3. A gas supply device in gas jet heating / cooling according to 1 or 2.