JP2004084030A - Layout of heating furnace in hot-rolling facility and operating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a layout of a heating furnace in a hot-rolling facility and an operating method with which an energy loss for raising the temperature of a slab according to the generation of chance loss in a DHCR (Direct Hot Charging Rolling) or the generation of a returning slab with unfinish-rolling, can be reduced. <P>SOLUTION: In a route for conveying the slab from a continuous caster to a DHCR exclusive heating furnace 3 in a hot-rolling mill, a heat-holding pit 6 for temporarily keeping the slab and a loader 7 for transferring the slab from the route to the heat-holding pit or the reverse way, are arranged, and when the DHCR exclusive heating furnace is fully loaded, the slab on the route is transferred to the heat-holding pit with the loader and temporarily kept, and when this heating furnace has unoccupied space, the slab is returned to the route with the loader and charged into the heating furnace. On the route, it is desirable to transfer a part or the whole of slabs to be finish-rolled after being ejected from the DHCR exclusive heating furnace or the other heating furnace (HCR (Hot Charge Rolling) or CCR (Cold Charge Rolling)exclusive heating furnace 1, 2) besides the slab to be charged into the heating furnace transferred from the continuous caster. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a heating furnace layout and operation method of a hot rolling facility.
[0002]
[Prior art]
In order to reduce the energy of heating the slab in the heating furnace of the hot rolling equipment and save energy, it is very effective to load the slab supplied from the continuous casting equipment into the heating furnace at a temperature as high as possible. is there. For this reason, a DHCR (Direct Hot Charge Rolling) operation of directly charging a slab from a continuous casting facility into a heating furnace while keeping the slab in a slab yard at a temperature as high as possible has been performed. I have. Although the slab from the continuous casting facility is temporarily put in a slab yard, an HCR (Hot Charge Rolling) operation of charging the slab to the heating furnace at a temperature as high as possible is often performed. However, if the charging temperature level of the slab to be charged varies, the combustion control must be performed such that the low-temperature charging slab must be heated to the required heating temperature and the high-temperature charging slab must be overheated. It becomes difficult, and the overheating slab is made to stand by by a so-called oscillation operation of reciprocating operation on a transport route (rolling line) to a rolling mill and allowed to cool, which often leads to impairment of the rolling efficiency. . (Oscillation is often performed during rolling.) Therefore, for example, as shown in FIG. 5, a heating furnace (DHCR dedicated heating furnace 3) for DHCR of a high-temperature charging slab having a relatively high charging temperature, and a heating furnace. Separately from the heating furnace (HCR / CCR dedicated heating furnaces 1 and 2) for heating a low-temperature charging slab having a relatively low input temperature or a normal-temperature charging slab to HCR (Hot Charge Rolling) or CCR (Cold Charge Rolling). In some cases, a method is used. Here, in the DHCR, the slab to be charged has a high temperature of around 1000 ° C., so that the fuel required for heating and the heating time are less than those of the HCR and CCR whose charging temperature is 600 ° C. or less. Therefore, the heating furnace 3 for DHCR may be designed to have a shorter furnace length than the heating furnaces 1 and 2 for HCR / CCR (for example, see Japanese Patent No. 2590233).
[0003]
In FIG. 5, the slab transport route to the HCR / CCR dedicated heating furnaces 1 and 2 is the slab yard 4 → loader 23 or 24 or 25 → cart 40 → loader 22 → transport table 11. The transfer route of the slab to the DHCR-dedicated heating furnace 3 is the transfer table 17 → the carriage 30 with the transfer table → the transfer table 12.
In addition, for special cases such as emergency use, the slab yard 4 → loader 23 or 24 or 25 → trolley 40 → loader 21 → transfer table 12 → transfer in the DHCR heating furnace 3 is made possible. Things can be different.
[0004]
[Problems to be solved by the invention]
However, here, the DHCR dedicated heating furnace 3 having a short furnace length cannot store a large amount of slab in the furnace, and the amount of slab supplied from the continuous casting facility to the DHCR dedicated heating furnace 3 is limited by the slab extraction from the furnace. If you exceed the amount, it will be full soon. This is the same to some extent even if the DHCR heating furnace 3 is the same length as the other furnaces. When the slab is full, the slab from the continuous casting facility cannot be charged into the DHCR dedicated heating furnace 3 and, after passing through another route such as the transport table 13 or the like, is made to stand by in the slab yard 4 and then is placed in the HCR or CCR. A so-called DHCR chance loss occurs in which the slab must be inserted into the heating furnaces 1 and 2 dedicated to HCR or CCR. As a result, the charging temperature of the slab having the DHCR chance loss decreases from about 1000 ° C. to about 500 ° C., and since high-temperature to low-temperature slabs are mixed, the combustion control becomes difficult for the above-mentioned reason. There is a problem that energy loss increases.
[0005]
In addition, the DHCR chance loss is the same as the hot rolling chance of special steel, the timing is overlapped, it is impossible to mix and roll, or in the case of trouble such as mis-rolling, the rolling operation stops and the slab It can also occur when charging becomes impossible.
On the other hand, if there is a completely different problem, such as a problem such as a misroll or a need to return the slab immediately after extraction of the heating furnace, the rolling operation will be interrupted. May be returned. In this case, the slab heated to about 1200 ° C. will be returned to the slab yard 4, and the temperature will drop before reloading, and the slab will be heated again. There is also a problem that extra energy is needed for this.
[0006]
The present invention has been made in view of the above-described problems of the related art, and provides a heating furnace layout and an operating method of a hot rolling facility that can reduce energy loss of slab heating due to occurrence of DHCR chance loss or return slab incompletely rolled. With the goal.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention temporarily places a slab returned from a continuous casting facility or a slab returned from a heating furnace in a heat retaining pit, and then temporarily stores the slab as soon as conditions are established. The slab temporarily placed in the pit can be loaded into a DHCR heating furnace.
[0008]
That is, the present invention relates to a heat retaining pit for temporarily placing a slab on a route for transferring the slab from a continuous casting facility to a DHCR heating furnace of a hot rolling facility, and transferring the slab between the heat retaining pit and the route. 2 is a layout of a heating furnace of a hot rolling facility provided with a loader. The route is preferably connected to a slab transport route from the heating furnace to the rolling mill.
[0009]
The present invention is also a method of operating a hot rolling facility having the heating furnace layout, wherein the slab on the route is transferred to the heat retention pit by the loader and temporarily placed when the DHCR dedicated heating furnace is full. Operating the hot rolling equipment, wherein the slab is returned to the route by the loader and charged into the DHCR heating furnace as soon as the DHCR heating furnace becomes free. In the route, in addition to the slab not yet loaded with the heating furnace sent from the continuous casting facility, part or all of the slab which has not been rolled after being extracted from the DHCR dedicated heating furnace or another heating furnace is transferred. Is preferred.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
For example, as shown in FIG. 1 in which the conventional example of FIG. 5 is changed to an example of the present invention, in the present invention, a slab is transferred from a continuous casting facility (also referred to as a continuous casting machine) to a DHCR dedicated heating furnace 3 of a hot rolling facility. A heat retention pit 6 for temporarily placing a slab on a route (transport table 17 → cart 30 with transport table → transport table 12) for transporting the heat, and between the heat retention pit 6 and the route, the heat retention pit 6 A loader 7 for transferring the slab to the pit or vice versa was additionally provided. As shown in FIG. 2, the loader 7 suspends and transports the slab from one side of the heat retaining pit 6 and the carriage 30 with the transport table to the other or in the opposite direction. The heat retaining pit 6 has an inner wall formed by using a suitable heat insulating material. However, a heating means such as a burner may be provided in order to suppress any decrease in the temperature of the slab in the heat retaining pit.
[0011]
In this example, as a preferred embodiment in which the operation method (2) of the present invention described later can be easily carried out, the above-mentioned route provided with the heat retaining pit 6 and the loader 7 is heated through a carriage 30 with a transfer table. The slab is conveyed from the furnaces 1 to 3 to the rolling mill (transfer table 10).
According to the operation method (1) of the present invention, when the DHCR-dedicated heating furnace 3 is full, the DHCR slab without a heating furnace sent from the continuous casting facility is sent along the slab flow line 50 in FIG. Once temporarily placed in the heat retaining pit 6, as soon as the DHCR dedicated heating furnace 3 becomes vacant, it is taken out of the heat retaining pit 6 and charged into the DHCR dedicated heating furnace 3.
[0012]
Further, in the operation method (2) of the present invention, in addition to the slab with no heating furnace sent from the continuous casting facility and the DHCR dedicated to the route along the slab flow line 51 or 52 shown in FIG. A part or all of the slab which has not been rolled after being extracted from the heating furnace 3 or another heating furnace (heating furnace 1 or 2 dedicated to HCR / CCR) is also transferred. That is, conventionally, at least one of the slabs that are returned without completing the rolling due to a trouble or the like is temporarily placed in the heat retaining pit 6, and is loaded into the DHCR dedicated heating furnace 3 as soon as the conditions are satisfied, and the rolling is performed. . The slab returned here includes slabs that are baked out of a heating furnace and returned without being rolled (along the slab flow line 51), and have been sent to a hot rolling line when a misroll occurs. And has already passed through the initial rolling pass, but the length thereof has not yet exceeded the furnace width of the DHCR dedicated heating furnace 3 and can be charged or recharged into the furnace (to the slab flow line 52). Along) are also included.
[0013]
【Example】
When the above-mentioned operation methods (1) and (2) were carried out in a hot rolling facility employing the heating furnace layout shown in FIG. 1, the heating furnace was temporarily placed in a heat retaining pit and then charged into a DHCR heating furnace. The slabs accounted for 8% of the total rolled material, and 27% together with the conventional DHCR practice of 19% could be processed in a DHCR heating furnace.
[0014]
Further, as shown in FIG. 4, for example, conventionally, when a slab having a DHCR chance loss is piled up in a slab yard, if a required time (track time) from cutting of the torch of the slab in the continuous casting equipment is 12 hours, Since the temperature was lowered to 500 ° C. or less, the furnace was charged in a heating furnace exclusively for HCR / CCR. However, if the furnace was temporarily placed in a heat retaining pit according to the operation method (1) of the present invention, even if the track time was 12 hours, 700 hours. C. or more, and it is possible to secure the lower limit of the charging temperature in the DHCR-dedicated heating furnace of the present embodiment (in this embodiment, the lowest charging temperature that can reach the required extraction temperature in 2 hours in the furnace). it can.
[0015]
As a result, the energy loss was significantly reduced.
The above example is just an example, and how many times the slab should be kept when the track time is reached depends on the insulation specifications of the heat retention pit and whether or not heating means is required. , The rolling pitch determined by the specific slab weight of the hot rolling equipment, product mix, etc., and the shortest furnace time that can occur during operation, which depends on the level of required extraction temperature determined by quality assurance or the upper limit of mill power, etc. May be appropriately determined in consideration of the above.
[0016]
【The invention's effect】
According to the present invention, a slab which had to be regarded as a DHCR chance loss due to a full DHCR heating furnace in the past, and a slab which had not been rolled after extraction of the heating furnace due to a rolling trouble (the length of the slab is equal to or less than the furnace width) ) Can be temporarily placed in a heat retention pit and charged into a DHCR-dedicated heating furnace in a timely manner, which has an excellent effect that the energy loss of the heating furnace can be greatly reduced.
[Brief description of the drawings]
FIG. 1 is a schematic plan view showing an example of a layout of a heating furnace and an operation method (1) of the present invention.
FIG. 2 is a schematic side view showing an example of a heat retention pit and a loader according to the present invention.
FIG. 3 is a schematic plan view showing an example of a heating furnace layout and an operation method (2) according to the present invention.
FIG. 4 is a slab temperature transition diagram showing a heat retaining effect of a heat retaining pit.
FIG. 5 is a schematic plan view showing a layout example of a conventional heating furnace.
[Explanation of symbols]
1, 2 HCR / CCR dedicated heating furnace 3 DHCR dedicated heating furnace 4 Slab yard 5 Continuous casting yard 6 Heat retention pit 7 Loader 10, 11, 12, 13, 14, 15, 16, 17 Transport tables 20, 21, 22, 23, 24, 25 Loader 30, 31 Trucks 40, 41 with transport table Trucks 50, 51, 52 Slab flow lines

Claims (4)

A heat transfer pit for temporarily placing the slab and a loader for transferring the slab between the heat transfer pit and the route are provided on a route for transferring the slab from the continuous casting equipment to the DHCR heating furnace of the hot rolling equipment. Furnace layout of hot rolling equipment. The heating furnace layout of the hot rolling equipment according to claim 1, wherein the route communicates with a slab conveyance route from the heating furnace to the rolling mill. 3. A method for operating a hot rolling facility having a heating furnace layout according to claim 1 or 2, wherein when the DHCR heating furnace is full, the slab on the route is moved to the heat retention pit by the loader and temporarily placed. The method for operating a hot rolling facility, wherein the slab is returned to the route by the loader and charged into the DHCR dedicated heating furnace as soon as the DHCR dedicated heating furnace becomes available. In addition to the slab not yet loaded with a heating furnace sent from the continuous casting facility, some or all of the slabs that have not been rolled after extraction from the DHCR heating furnace or other heating furnaces are transferred to the above route. The method for operating a hot rolling facility according to claim 3, wherein:

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