JPS5812327B2 - Heating furnace for rolling steel materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has been developed in view of the current situation where the charging rate of hot material has been increasing recently, since conventional steel heating furnaces for rolling are designed for charging cold material. This article relates to a new type of heating furnace for rolling steel that can be used for both room-temperature materials and high-temperature materials, making it possible to maximize the sensible heat of the exhaust gas emitted from the rolling steel heating furnace and achieve economical effects. be.

Traditionally, heating furnaces for rolling have been classified into pusher type, walking beam type, rotary hearth type, roller hearth type, etc. based on their structure.

These rolling heating furnaces are equipped with extremely energy-saving measures.

In other words, typical examples of conventional methods for utilizing sensible heat from heating furnace exhaust gas include preheating combustion air as a heat source for waste heat boilers, and preheating combustion gas. Research and implementation.

However, the above method has the following drawbacks.

In other words, since the amount of preheated air is small compared to the total amount of exhaust gas discharged from the rolling heating furnace, the recovery rate of the exhaust gas to be used is low at 20 to 30% (relative to the total amount of exhaust gas). , there was a large waste in that 70-80% of the heat (relative to the total exhaust gas volume) was dissipated.

On the other hand, hot charging has been attracting attention as a measure to save energy, but technically speaking, the hot charging ratio is only about 30 to 50% for ordinary steel;
Currently, ~70% of the steel is charged at room temperature.

In other words, the rolling steel material charged into the rolling heating furnace is charged at high temperature,
In many cases, charging at room temperature is often replaced with charging at room temperature, so the design base for heating furnaces has traditionally been based on rolled steel material at room temperature. This has the disadvantage that not only is a very wasteful amount of heat used during heating, but it is also unfavorable from the standpoint of quality and yield.

When charging the high-temperature steel materials mentioned above, the temperature of the rolling steel material itself is high, so originally the furnace length should be shortened, but as mentioned above, the furnace length was changed to require the use of room-temperature rolling steel materials. The length of the reactor had to be long, and there were disadvantages in that the reactor length could not be set to an appropriate length, resulting in large horizontal losses in terms of equipment and large energy losses.

This invention is the result of extensive research by the inventor Nagisa in order to eliminate these blemishes. This system is designed to save energy by recovering sensible heat from exhaust gas with high efficiency and using the sensible heat to preheat rolling steel materials at room temperature.
The other purpose is to make the heating in the rolling heating furnace more efficient than before when rolling steel materials at room temperature or high temperature, or a mixture of these two, to achieve stable energy saving and to operate on the basis of rationalization. The purpose is to provide equipment.

Other objects and effects of the present invention will become more apparent from the following description.

The feature of the present invention is that the preheating zone of the heating furnace consisting of a soaking zone, a heating zone, and a preheating zone for heating rolling steel materials is divided into two, and the front soaking zone, heating zone, and preheating zone are divided into two. The hearth of the hearth is a mobile type (for example, a walking beam, a walking hearth), the charging port for hot steel material for rolling is provided on the side of the furnace body in the preheating zone of the mobile hearth, and the hearth in the rear preheating zone is a fixed type. None, a cold steel material charging port for rolling is provided at the rear end of the furnace housing the fixed hearth, and then a gas amount adjustment is made between the furnace with the movable hearth and the furnace with the fixed hearth. In order to do this, a partition wall that can be moved up and down has been installed, and in history, one or more charging ports for rolling steel were provided on the side of the furnace body in the preheating zone of a mobile hearth.

The present invention will be explained below based on examples and drawings.

FIG. 1 is a sectional view of a heating furnace for rolling steel according to the present invention.

This rolling steel reheating furnace has a reheating furnace A with a movable hearth (hereinafter referred to as mobile hearth type reheating furnace) and a preheating furnace with a fixed hearth (hereinafter referred to as fixed furnace), which is configured so that the rolled steel is advanced by a pusher. A device that has a partition wall 1 that can be moved up and down in order to adjust the amount of gas discharged from the movable hearth type heating furnace A at the boundary part a. has been established.

High-temperature steel materials for rolling are charged into the sliding hearth type heating furnace A. The high-temperature steel materials for rolling charged from the charging port 1 are moved forward by the operation of the moving hearth 2 while moving through the heating furnace A. The heated rolling steel material 3 is extracted from the extraction port 4 provided in the front side wall to the rolling line.

The amount of combustion gas from burners 8 and 8' provided at the front is adjusted by a partition wall 1 that can be moved up and down, and is discharged from a flue 5 through a fixed preheating furnace.

In addition, steel for rolling at room temperature is charged into the fixed hearth type preheating furnace B, and the steel for rolling at room temperature is placed on the fixed hearth 6 through the charging port 11 and advanced by the pusher 10. It is configured such that it is fed into the mobile heating furnace A while being preheated by the exhaust gas from the mobile hearth type heating furnace A.

Next, the operation of the device of the present invention will be explained.

High-temperature steel for rolling is charged through a charging port 1 provided on the side of the furnace body of the preheating zone A''' of the moving hearth type hearth 2 by a known appropriate method.

At this time, the partition wall 1 is moved up and down to the optimum state, which not only eliminates wasteful firing in the burners 8 and 8', but also eliminates unnecessary firing in the burners 8 and 8'. 1
Since the steel material 3' for rolling in the fixed hearth preheating furnace B is heated by the sensible heat of the discharged gas, it is possible to supplement the hot steel material and use the sensible heat effectively, so it is possible to design according to the desired temperature standard.
The furnace length is shorter than that of conventional rolling heating furnaces, which not only allows for an optimal design, but also allows for low-cost operation in terms of installation space, equipment costs, and energy costs.

Next, a description will be given of heating only the rolling steel material at room temperature or at a desired temperature or lower.

Steel materials for rolling are charged through the charging port 11 exclusively for cold steel materials,
It is sent one by one to the moving hearth type heating furnace at the pusher.

In this case, it is preferable that the fixed hearth at the boundary part a be tapered to separate the close contact of the steel pieces 3', for example as shown in FIG. If this is done, the fixed hearth top 3' can be more easily transferred to the movable hearth 2.

On the other hand, the excess heat that was conventionally dissipated is raised to the desired temperature of the rolling steel in the fixed hearth preheating furnace by opening and closing the partition wall 1 according to the amount of gas.

At this time, an auxiliary burner 9 is provided in the fixed hearth type preheating furnace B, and is used when the amount of heat in the preheating furnace B is insufficient to raise the temperature of the steel material for rolling to a predetermined temperature.

Next, a case will be described in which a steel material for rolling at room temperature is continuously charged after the above-mentioned high temperature steel material for rolling.

Steel for rolling at a desired temperature is charged from the charging port 7 as described above, but when there is a shortage of the steel for rolling or for some other reason, the steel for rolling at room temperature may be charged. In general, there are many things that must be done.

In such a case, it was usual to change the conventional heating standard and heat the rolling steel material at room temperature. However, in the apparatus of the present invention, the room temperature material is The rolled steel material 3 at room temperature is charged into the fixed hearth preheating furnace B through the inlet 11.
As mentioned above, by opening and closing the partition wall 1 to combine the amount of gas, the temperature is raised by the exhaust gas of the moving hearth type heating furnace A and/or the auxiliary burner 9, and this causes the preheating. The steel in the furnace is constantly preheated.

The steel material for rolling, which has been wetted in this manner and has reached a desired temperature, is pushed by a pusher 10 and transferred to a movable hearth.

A preferred example of application of the device of the present invention will be explained based on FIG.

High-temperature steel for rolling, which has been conveyed from a steel manufacturing or blooming factory, etc., passes through the heat insulation bed 12 on the roll gang 14, the high-speed conveyor 13, and then passes through the route e on the roll gang 15 to the moving hearth type heating furnace A. is charged.

On the other hand, when the steel material is not transported to the heat insulation bed 12, that is, the steel material that should become room temperature material passes through the path f of the roll gang 14 and is cooled on the cooling bed 16. When the material i is used, the room temperature steel material is charged. It is conveyed to a stand 11, sent to the bottom of the furnace via path g, and charged into a fixed hearth type preheating furnace B by a pusher 10.

Rolling steel material used: l20φxis. ooommX2
,OOOKy Fuel used: Kerosene + blast furnace gas (calorie ratio 43:57) 240T...Fixed hearth preheating furnace for high-temperature steel 80T...・・The preheating zone of a steel reheating furnace for room-temperature steel rolling is divided into two, and the front soaking zone, heating zone, and preheating zone are movable hearth type reheating furnaces, and the rear part is a butcher type fixed hearth preheating furnace. The reason is as follows.

That is, on the premise that exhaust gas from a heating furnace for heating rolling steel materials is used, the configuration of the invention as described above can be roughly divided into the following methods.

(1) Fixed hearth type at the front, fixed hearth type at the back (butcher type) (2) Movable hearth type at the front, moving hearth type at the rear.

(3) The front is a fixed hearth type heating furnace, and the rear is a moving hearth type preheating furnace.

(4) As in the present invention, the moving hearth type at the front is a heating furnace, and the rear fixed hearth type is a preheating furnace.

etc.

Of these, (1) and (3) have the drawbacks of high equipment cost, large installation area, and difficulty in control methods.

(2) has the disadvantages of high equipment costs and a large installation area, while (4) eliminates these disadvantages by using a pusher type fixed hearth preheating furnace at the rear.

Furthermore, the reason for dividing the preheating zone into two can be easily deduced from the explanations given so far, but even if the heating zone or preheating zone is divided into two, not only will the above-mentioned effects not be obtained at all, but the role as a heating furnace will not be achieved. It also becomes unfulfilling.

Next, the main reason why the charging port for rolling steel material was set to be larger than the side surface of the preheating section of the mobile hearth is to change the charging port according to the temperature range% of the high temperature steel material for rolling. It is.

That is, for steel materials heated at 700° C., the charging port is changed to the front charging port, and for steel materials heated to 500° C., the charging port is changed to the rear charging port.

This allows the firing method to be rationally adjusted according to the temperature of the hot steel material to be charged, resulting in significant energy savings.

The present invention is constructed as described above, and since the flow of steel for rolling is linear, it is easy to switch from high-temperature steel to room-temperature steel, and from room-temperature steel to high-temperature steel, and to minimize heat loss. Not only is it possible to produce ink, but the waste gas from the mobile hearth type heating furnace can be recovered to the maximum extent, resulting in a large energy saving effect.

In addition, it is possible to provide a heating furnace for rolling steel that has high combustion efficiency and improved production capacity, resulting in highly efficient operation and high energy savings.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a heating furnace for rolling steel materials according to the present invention;
FIG. 2 is a vertical sectional view of the boundary between the powder hearth type heating furnace and the fixed hearth two preheating furnace, and FIG. 3 is a plan layout of an application example of the apparatus of the present invention. 1... Partition wall, 2... Mobile hearth, 3,
3'... Steel material for rolling, 4... Extraction port,
5... Flue, 6... Fixed hearth, ?・・・
...High temperature material charging port, 8, 8/...Burner, 9
...... Auxiliary burner, 10 ... Butcher, 11 ... Room temperature material charging inlet, 12 ... Heat insulation floor, 13 ... High speed conveyor, 14,15...
... Rollgang, 16 ... Cooling bed, 11 ... Charging stand, 18 ... Recubulator, 19 ... Flue, 20.・・・・・・
・Chimney, 21... Extraction rod, 22... Rolling mill, A... Mobile hearth type heating furnace, A'...
・・Soaking zone, A″・・・Heating zone, A″′・・・・
・・Preheating zone, B・・Fixed hearth type preheating furnace, a・・
...Boundary part, b...Taper, c, d, e
, f, g... Path of bent steel material.

Claims (1)

[Scope of Claims] 1. The preheating zone of a heating furnace consisting of a soaking zone, a heating zone, and a preheating zone for heating steel materials for rolling is divided into two, with a front soaking zone,
The hearth of the heating zone and pre-heating zone is movable, the charging port for hot steel material for rolling is provided on the side of the furnace body of the pre-heating zone of the movable hearth, and the hearth of the rear pre-heating zone is fixed, and rolling A cold steel material charging port is provided at the rear end of the furnace body having the fixed hearth, and then vertical operation is performed to adjust the gas amount between the furnace having the movable hearth and the furnace having the fixed hearth. A heating furnace for rolling steel material characterized by having a partition wall that can be freely moved. 2. The heating furnace for rolling steel materials according to claim 1, wherein at least one charging port for rolling steel materials is provided on the side surface of the furnace body in the pre-heating zone of the movable hearth.