JPS6055564B2 - heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to heating and rolling of steel billets, particularly in the step of rolling heated steel billets in a rolling mill with a very large reduction rate such as a planetary rolling mill. The present invention relates to a heating furnace device that aims to effectively utilize thermal energy by directly connecting a heat retention furnace to the heating furnace main body to prevent heat dissipation and cooling of steel slabs.

FIG. 1 shows an equipment layout diagram for the heating and rolling process in the prior art.

The cold steel billets or warm steel billets 51 are carried to the charging side of the heating furnace by the charging roller table 13 and aligned, and then transferred into the furnace by the billet charging machine 12, where they are passed through the heating furnace 1. The movable skid drive devices 7 and 8 move the inside of the furnace from the pre-soaking zone 2 side to the soaking zone 3 side while alternately repositioning the skids on the movable skid 5 and fixed skid 6 in a drive cycle as shown in Fig. 7. It is heated while being transported to.

The heated steel billet 53 is carried out by the billet extractor 14 onto an extraction roller table 27 outside the furnace, and transferred by this roller table into a heat retention furnace 18 provided on the same line as the roller table. be done.

Since the temperature of this steel billet is about 1100 to 130C10C, a water-cooled in-furnace roller 28 is provided in the heat retention furnace to support the steel billet and at the same time feed it to the rolling mill. In the heating furnace 1, the combustion exhaust gas used for heating the steel billet is transferred from the high temperature soaking zone 3 to the low temperature preheating zone 2.
It flows to the side, heats the steel pieces in the furnace, releases energy, and is sucked into the flue gas outlet 4 (not shown).
It is then discharged from the chimney (shown in the figure).

The temperature of the exhaust gas in the flue is around 500-86°C due to heat exchange with the cold steel billets in the furnace, but this exhaust heat is further transferred to a heat exchanger (not shown) installed in the flue. vinegar)
It is recovered by preheating the combustion air.
On the other hand, in the heat retention furnace 18, the steel pieces in the furnace are almost uniformly 1250
Since the temperature is as high as 'C', the burner 11 is used to maintain a constant state so that the temperature does not drop during rolling.

The temperature of this exhaust gas is almost the same over the entire length of the furnace, and it is also extremely high temperature (1250-1300'C).The temperature is too high if it continues as it is, so it is directly heated by a heat exchanger like the one used in the heating furnace. It is not possible to recover waste heat, so either cold air is blown in to lower the temperature to around 800°C, and then the heat is exchanged and released, or it is released while still at a high temperature. In the conventional method, heat loss in the heat retention furnace is extremely large for the following reasons, and improvements are desired.

(a) A steel billet heated in a heating furnace is once taken out of the furnace and then placed in a heat retention furnace.

(b) The steel billets in the heat retention furnace are brought into rolling speed (a) with some of them being caught in the rolling mill 29. Since it is necessary to send out the materials at the same level (5 to 5 mImin), an in-furnace roller system is adopted.

Moreover, since the furnace temperature is as high as 1,300 to 1,350 C, these furnace rollers 28 are internally water-cooled and their outer surfaces are not insulated (if they are wrapped with insulating material, they will fall off during conveyance of the billet). , the heat loss from the roller surface is (
150-250) x 103 kca11 h, which is extremely large. (C) For heat retention furnaces, the billet temperature is 1200-1
Because it needs to be protected at around 250°C, the temperature of the gas inside the furnace is extremely high at 1250-1300°C, which is slightly higher than the steel slab (same level as the soaking zone in a heating furnace), so if it continues as it is, it will not be possible to recover waste heat. Therefore, it cannot pass through the heat exchanger, and the waste heat must be recovered after cooling it by blowing cold air to a level of 800°C, which is safe for a single heat exchanger.This deteriorates thermal efficiency and increases the size of the heat exchanger. This is leading to high costs. In a heat retention furnace, there is almost no need to heat up the steel billet and it is fine to keep it at that temperature. However, in the conventional method, there are many water-cooled rollers, so there is a large amount of water cooling loss, so it is difficult to maintain the temperature inside the furnace. A large amount of heat is lost in order to maintain the specified temperature,
The reality is that fuel is injected to compensate for this.

If a heat retention furnace with very low heat loss were developed, fuel consumption could be significantly reduced. In order to solve the problems of the prior art, the present invention aims to improve the following points and effectively utilize thermal energy and save energy.

(a) A heat retention furnace is directly connected to the extraction side of the heating furnace, and heated steel pieces are transferred to the heat retention furnace without being taken out from the heating furnace.

(b) In order to minimize heat loss in heat retention furnaces, the method of conveying steel billets using rollers in water-cooled furnaces, which cannot be insulated, has been eliminated.
Adopts a water-cooled beam system whose surface is covered with a heat insulating material (c) A billet conveying device that also has a double walking mechanism that allows billets to be conveyed in accordance with the rolling speed without changing the level of billets in the heat retention furnace. (d) Sensible heat of the exhaust gas is effectively utilized by guiding the high-temperature exhaust gas generated in the heat retention furnace to the exhaust port of the preheating zone through the soaking zone of the heating furnace.

An example of the equipment layout for the heating and rolling process in the present invention is shown in FIG.

Further, details of each equipment according to the present invention are shown in FIGS. 3 to 6.

These will be explained below.

The process is the same as the conventional method until the cold steel billet or hot steel billet is carried by the charging roller table 13 and is conveyed while being heated to the extraction side of the heating furnace 1.

As shown in Fig. 3, the steel slabs that have been conveyed to the extraction side of the heating furnace are scooped up by the steel slab extractor 15 and are kept warm by moving the extractor 15 in the longitudinal direction of the heat retention furnace without being taken out of the furnace. It is carried into the furnace 18.

The state of the extractor when the steel billet is brought into the heat retention furnace is shown in the second diagram.
Indicated by a broken line in the figure.

To achieve this, the extractor 15 is mounted on a carrier 16 as shown in FIG. 5, and is designed to be able to move on rails 17 arranged in the longitudinal direction of the heat retention furnace. ing.

In addition, the extraction door 10 of the heating furnace and the door 30 of the heat retention furnace are divided into relatively short sections, and are opened only while the extraction machine is lifting and moving the steel piece, and are sequentially closed to open the opening. It is designed to save time as much as possible.

After completing the transfer of the steel pieces to the heat retention furnace, the extractor exits the heat retention furnace and returns to the extraction side of the heating furnace using the conveyor truck 16, as shown in FIG.

Two sets of moving beams as shown in FIGS. 5 and 6 are provided in the heat retention furnace, and these beams are driven by a drive device 23 having a generally known double walking mechanism.
, 25, the steel slabs are transferred toward the rolling mill while repeating the rectangular movements shown in FIG. 7, without changing their level.

The tip of the billet in the heat retainer is caught in the rolling mill, so the conveyance speed of the billet matches the rolling speed.
The moving beam of the heat retention furnace and its driving device are divided into two in the furnace length direction as shown in FIG. After finishing, the beams 19 and 20 on the heating furnace side and the drive device 23
, 25, the interlocking operation is disconnected, and the beam and drive device on the heating furnace side are temporarily stopped (those on the rolling mill side are in operation).

During this suspension, steel pieces are carried into the heat retention furnace from the extraction side of the heating furnace by the above-mentioned extractor 15. After the billet is brought in, the beams and drive devices on the rolling mill and heating furnace sides are synchronized and begin to transport the billet as one unit. The moving beams inside the heat retention furnace are arranged in multiple rows in the width direction of the furnace to conveniently bring the steel pieces into the furnace using an extractor.

This allows the contact position of the beam to the back surface of the steel piece to be randomly selected, and also reduces skid marks. These beams are composed of water-cooled steel vibrators, etc., but in order to minimize heat loss, their outer surfaces are thickly covered with heat insulation, and the heat loss per surface area is (5 to 12). ×1σKcalldh, compared to (150 to 250)×10c of the conventional furnace roller method.
Compared to a II h, the input can be significantly reduced.

It is necessary to maintain the internal temperature of the heat retention furnace at the same temperature as the billet temperature or slightly higher than it.For this purpose, burners 11 are installed on the side walls (or the ceiling) to control the amount of combustion. Temperature control is performed in the same manner as in a heating furnace.

High-temperature combustion exhaust gas in the heat retention furnace (1250-130)
) is sucked into the soaking zone 3 (Fig. 3) side of the heating furnace by the exhaust equipment of the heating furnace, flows through the heating furnace to the preheating zone side, provides heat to the steel pieces in the heating furnace, and then cools down to a relatively low temperature (800℃). degree Celsius) is discharged from the exhaust port 4 into a flue (not shown), and the exhaust heat is effectively utilized for preheating combustion air provided in the flue.

Since the heating furnace of the present invention has the above-described configuration, it exhibits the following excellent effects.

(a) The heat retention furnace and the heating furnace are directly connected, and when the heated steel billet is transferred from the heating furnace to the heat retention furnace, it is not taken out of the furnace at once, so cooling of the steel billet can be prevented.

(b) Since the heat retention furnace and the heating furnace are directly connected and the high temperature combustion gas in the heat retention furnace is discharged through the heating furnace, the exhaust heat of the combustion gas can be fully utilized.

(c) Since the steel slabs in the heat retention furnace can be of a moving beam type with less heat loss, the heat loss is extremely reduced and the heat utilization rate of the entire furnace is increased.

(d) Since the moving beams in the heat retention furnace are arranged in multiple rows in the width direction of the furnace, the locations where the beams hit the back surface of the steel billet can be randomly selected, making it possible to reduce skid marks.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the layout of billet heating and rolling equipment according to the conventional method, FIG. 2 is a diagram showing a layout example of billet heating and rolling equipment based on the present invention, and FIG. A-A cross section in Figure 2 (Extractor 1
5 is a sectional view taken along the line BB in FIG. 2, and FIG. 5 is a sectional view taken along the line C-C in FIG. 2. Figure 6 shows the second
A cross-sectional view taken along line CC in the figure (where the conveyance of the steel pieces into the heat retention furnace 18 has been completed and the extractor has come out of the furnace) and FIG. 7 are diagrams showing the drive cycle of the moving beam. 1: Billet heating furnace, 2: Preheating zone of the billet heating furnace, 3: Soaking zone of the billet heating furnace, 4: Exhaust gas outlet, 5: Moving skid of the billet heating furnace, 6: Billet heating furnace Fixed skid, 7: Moving skid drive device for billet heating furnace (vertical motion), 8: Moving skid drive device for billet heating furnace (horizontal motion), 9: Charging door of billet heating furnace, 10: Billet Heating furnace extraction door, 11: burner, 12: billet charging machine, 13: charging side roller table, 1
4: Steel billet extraction machine, 15: Steel billet extraction and conveyance machine, 16:
Transport truck, 17: Rail, 18: Steel piece heat retention furnace, 19:
First moving beam of billet heat retention furnace, 20: Second moving beam of steel billet heat retention furnace
Moving beam, 21: First moving beam of billet heat retention furnace, 22
: Second moving beam of the billet heat retention furnace, 23: Moving beam drive device of the billet heat retention furnace (opposite mill side), 24: Moving beam 7 drive device of the billet heat retention furnace (mill side), 25: Moving beam drive tuning device for billet heat retention furnace (anti-mill side), 26: Moving beam drive tuning device for billet heat retention furnace (mill side), 27: Extraction side roller table, 28: Heat retention furnace Furnace roller, 29: Mill, 30: Heat retention furnace door, S1: Steel billet on the loading roller table, S2: Steel billet charged to the charging side of the heating furnace, S3:
Steel billet heated in the heating furnace and transported to the extraction side, S4: Steel billet transferred to the heat retention furnace, S5: Steel caught in the rolling mill and being transported in the heat retention furnace in accordance with the rolling speed. Piece.

Claims (1)

[Claims] 1. In a heating furnace equipped with a walking-type conveyance device that transports materials in the furnace length direction, a heat retention furnace is directly connected to the side wall side of the material extraction section of the heating furnace, and a heat retention furnace is connected outside the furnace on the side wall of the material extraction section in the furnace length direction. A heating device characterized in that a cart carrying a material extracting device that can be moved forward and backward is provided, and the cart is movable in the width direction of a heating furnace.