JPS62151528A - Method for recovering sensible heat of metallic strip - Google Patents

Abstract

PURPOSE:To eliminate the need for cleaning of a metallic strip after recovery of the sensible heat thereof and to reduce an equipment cost and running cost by sing fluidized powder beds in place of using a fused salt tank to recover the sensible heat of the metallic strip. CONSTITUTION:The hot rolled metallic strip 1 of a high temp. in un-coiled and is fed with pinch rolls 3 and a leveler 4. The metallic strip is successively connected by a welding machine 5 and is introduced with bridle rolls 6a into fluidized powder bed device 7. The metallic strip 10 is repeatedly raised and lowered by plural turn rolls 11 and is thereby continuously passed in the plural fluidized beds having fluidizing gas circulating ducts 13. The metallic strip 10 contacts the powder 15 on a dispersion plate 8 which is kept fluidized by the fluidizing gas supplied from the lower part of the fluidized beds and the gas. The heat retained by the steel strip 10 transfers to the powder 15 and the gas and the water in steam generating pipes 16 built in the fluidized beds is heated and is recovered in the form of stem or by a heat exchanger disposed in the fluidizing gas circulation system.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for efficiently recovering the sensible heat contained in a hot metal strip, such as a hot rolled steel strip.

(Conventional technology) For example, steel strip coil after hot rolling.

The strip coil usually has a temperature of about 500 to 900°C, and is either water-cooled or air-cooled and shipped as is, or cooled to about 50°C and pickled before being sent to the cold rolling process. The sensible heat possessed by the strip coil was not utilized. In recent years, attempts have been made to recover the heat held by this hot-rolled coil and use the ILT.

However, as a sensible heat recovery method for this type of steel strip, a method using a molten salt bath is generally used. A representative example of this is known as Japanese Patent Application Laid-Open No. 57-18868:1, the contents of which are Melting 1'1! A strip is immersed in Japanese cypress, the IXJ heat of the slip is transferred to molten salt, and the sensible heat is recovered by a steam generating tube built into the molten salt tank.

(Problems to be Solved by the Invention) However, such a sensible heat recovery method using molten salt has the following drawbacks.

■Since molten salt adheres to the strip, the molten salt is carried outside, increasing running costs, and requires cleaning the strip, which requires high equipment costs and effluent treatment.

(2) Since the melting point of the molten salt is about 1406C, the molten salt solidifies when the strip is passed through the strip at a temperature close to room temperature. Also, is it necessary to heat the molten salt when starting the line after a long-term stoppage?

■Scale is generated by molten salt.

- Molten salt is highly corrosive, making equipment maintenance difficult or requiring the use of materials such as stainless steel, which increases costs.

The present invention is an excellent metal strip W that solves these problems.
The purpose is to provide a J heat recovery method.

(Means for Solving the Problems) The method of the present invention for achieving this object is configured as follows. That is, the hot-rolled coiled metal strip is unwound in a high-temperature state and sequentially connected using a welding machine, and then the high-temperature metal strip is connected to a heat exchanger with a built-in steam generating tube or within a fluidizing gas circulation system. This is a method for recovering sensible heat from a metal band, characterized in that the sensible heat held by the metal band is recovered by passing the metal band continuously through a powder fluidized bed arranged with a metal band.

The present invention will be explained below using a specific example of a sensible heat recovery device shown in the drawings.

In Fig. 1, ■ is a hot-rolled high-temperature metal strip coil, 2 is an unwinding machine for mounting and unwinding the coil I, and the chain unwinding machine 2 unwinds the metal strip into a line. supplied to 3 is a metal band 1 provided close to the chain unwinding machine 2;
Pinch roll to give thrust to 0, 4 is metal band 1
0 is a leveler for correcting the shape, 5 is a built-in welding machine that sequentially connects the metal strips IO that are fed,
It has a built-in shear and flash trimmer. 6a, 6
Reference numeral b denotes priddle rolls placed before and after the powder fluidized bed device, which will be described later, to apply tension to the metal strip in the line.

Reference numeral 7 denotes a powder fluidized bed device, which is used to recover sensible heat held by the introduced metal band 10. In the powder fluidized bed device 7, the metal strip is passed through a plurality of turn rolls [
It repeatedly ascends and descends by L and passes through a plurality of fluidized beds divided by outer walls. Figure 2 shows an example of the structure of one fluidized bed.

As shown in FIG. 2, the fluidized bed main body is formed into a vertically elongated shape by an outer wall 12, and a dispersion plate 8 having a large number of holes is provided horizontally above the lower turn roll llb, and the upper and lower parts are connected to a fluidizing gas circulation duct. Connect with 13.

A blower 9 is interposed and installed at the bottom of the fluidized bed at the lower end of the duct 13. Further, powder (for example, alumina, steel, iron sand with a grain size of 0.1 to 0.4 mm) 15 is sealed on the dispersion plate 8 inside the fluidized bed, and a steam generator 16 is placed therein.

Therefore, the blower 14 blows the fluidizing gas (for example, air) at 2
If a pressure of ~3 kgf/c+s2 is supplied from the bottom of the fluidized bed, the powder 15 on the dispersion plate 8 will be in a fluidized state, and the metal n'tlo passing through this will come into contact with this powder 15 and the gas, and its The retained wJ heat is transferred to these powders and gases. This transferred heat is then transferred to the steam generator 1.
6 is heated and recovered as steam.

In FIG. 1, a plurality of fluidized beds (six in series in the figure) are arranged to sufficiently recover sensible heat from the metal strip. Figure 3 shows the transition of metal zone temperature and steam temperature in this six-layer fluidized bed.
The temperature is reduced to 200°C, and the steam is obtained as a supersaturated thin gas at 200°C.

Although a steam generator is shown as a heat recovery device in FIG. 2, it goes without saying that in the present invention, a heat exchanger may be interposed in the fluidizing gas circulation system to perform heat recovery. In addition, a loop car and a winding machine may be arranged after the sensible heat recovery part shown in the figure, or a pickling tank, a loop car, and a winding machine may be arranged following the loop car, or a cold washing machine may be arranged following the pickling tank. A continuous annealing furnace may be provided in addition to the rolling mill.

(Effects of the Invention) According to the sensible heat recovery method of the present invention as described above, since a powder fluidized bed is used for sensible heat recovery of the gold band, the drawbacks seen in the conventional method using molten salt, That is, the necessity of cleaning after collection, high equipment costs, running costs and maintenance costs, etc., have been almost completely eliminated. Furthermore, the present invention can also pass through low-temperature metals. Therefore, it is ideal for WJ heat recovery work on high-temperature metal objects.

[Brief explanation of drawings]

Fig. 1 is an overall layout diagram showing an example of equipment for implementing the method of the present invention, Fig. 2 is a structural diagram showing a specific example of the powder fluidized bed in Fig. 1, and Fig. 3 is a metal band in the t & fluid bed. 2 is a graph showing changes in steam temperature. DESCRIPTION OF SYMBOLS 1... Metal band coil, 2... Rewinding machine, 3... Pinch roll, 4... Leveler, 5... Welding machine, 6...
... Bridle roll, 7... Powder fluidized bed device, 8.
...Distribution plate, 9...Blower-110...Metal band, 1
3...Duct, 15...Powder, 16...Steam generator.

Claims (1)

[Claims] After hot rolling, the coiled metal strip is unwound in a high temperature state and sequentially connected using a welding machine, and then this high-temperature metal strip is connected to a built-in steam generating tube or a heat exchanger in a fluidizing gas circulation system. A method for recovering sensible heat from a metal band, characterized in that the sensible heat held in the metal band is recovered by passing the metal band continuously through a powder fluidized bed.