JPS5858230A - Soaking pit - Google Patents

Abstract

PURPOSE:To make the temp. in a soaking pit of one-way firing in an upper part uniform and to reduce the unit of fuel in said furnace by providing plural pieces of suction ports for waste gases in a hearth part. CONSTITUTION:The combustion gases discharged from a main burner 22 in the upper part of the side wall of a soaking pit 21 are turned over from the position about half the furnace length in said furnace, and are sucked through plural pieces of the 1st suction ports 23 for waste gases provided in the hearth into a flue 25. Therefore, the combustion gases retain sufficient heat even when these gases flow into the ports 23 and can heat the parts around these parts substantially. An auxiliary burne 26 is provided below the burner 22. The burner 26 is installed in the 2nd suction port 27 for waste gases on the side wall of the furnace, and brick masonry parts 28 for partition are provided near the inlet of the port 27. Thus part of the combustion gases in the furnace 21 are conducted through the port 27 into the flue 25.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a soaking furnace, and particularly to a unidirectional firing soaking furnace in which the temperature inside the furnace is made uniform.

A soaking furnace is a furnace that uniformly heats a steel ingot, bloom, billet, or slab 4 to a predetermined temperature prior to blooming or hot rolling.There are several types of heating methods. The most common type is the so-called top one-way firing type, which heats by burning a burner installed on the upper part of the furnace side wall.

By the way, the gas flow inside the furnace of such an upper unidirectional firing soaking furnace has a unique U-shaped flow, so the upper part on the side opposite to the burner has the highest temperature, and the lower part on the burner side has the highest temperature. becomes lower. In other words, since it is an upper unidirectional firing soaking furnace, the gas flow in the furnace is from the burner outlet, along the opposite burner wall, reverses, and flows through the lower part on the opposite side to the burner. The exhaust gas passes through the exhaust gas inlet and into the flue, and is exhausted to the atmosphere. Therefore,
The temperature in the lower part of the burner side is the lowest in the furnace because the gas that has already released heat on the side opposite to the burner flows.

By the way, in the past, soaking furnaces mainly heated steel ingots, but as continuous casting progresses, existing soaking furnaces can be effectively used to soak blooms or slabs after continuous casting. Heating in a furnace became widely used. Therefore, in current soaking furnaces, steel ingots, blooms, or slabs are stacked in multiple stages as the material to be heated, and are charged into the furnace and heated. As a result, in the case of a one-way soaking furnace like the one mentioned above, together with the occurrence of a temperature difference inside the furnace due to mold in its structure,
It is becoming difficult to uniformly heat the charged material to be heated, which is the original function.

Conventional countermeasures have been to variously change the charging format of blooms or slabs in order to smoothen the flow of hot gas into the furnace for a week, or to install auxiliary burners near the exhaust gas suction port. We are doing this, but it is not a drastic measure. For example, for equipment where the temperature is particularly low near the lower part of the burner side, there is a method of installing an auxiliary burner at the existing exhaust gas inlet to forcibly eliminate the low temperature part (%
-41816).

However, because the auxiliary burner is installed near the exhaust gas inlet, only the area that is in contact with the auxiliary burner frame is heated, and therefore the heating efficiency is poor. It cannot be done.

Another method for reducing the temperature difference inside the soaking furnace is to detect the temperature on the burner side and the temperature on the side opposite to the burner, and change the length of the flame from which the burner ejects based on the temperature difference. (See patent No. 678454).

Furthermore, the process of forcibly circulating the combustion exhaust gas near the burner and resolving the insufficient temperature at the lower part of the burner side becomes unnecessarily complicated, and is considered to have little practical value.

Therefore, in order to raise the temperature at the bottom of the burner side, conventionally the set temperature inside the furnace was increased or the heating time was lengthened, which resulted in a decrease in fuel consumption. A decrease in the lifespan of the body was observed.

Thus, an object of the present invention is to significantly improve the flow of combustion exhaust gas in the furnace and to raise the temperature at the lower part of the burner side without increasing the set temperature in the furnace as in the conventional method.
Moreover, it is an object of the present invention to provide a unidirectional firing soaking furnace which can shorten the heating time and thereby greatly reduce the fuel consumption rate.

Here, the present invention provides a main burner device on the upper part of the furnace side wall, and a main burner device on the furnace side wall.
This is an upper one-way firing soaking furnace that is equipped with an auxiliary burner device at the lower part of the wall, and has at least one exhaust gas suction port in the hearth.

The auxiliary burner device may be installed at the exhaust gas inlet provided at the lower part of the furnace side wall, as is the case with conventional devices. In addition, it is sufficient to provide the exhaust gas suction port according to the present invention on the hearth, but if it is also provided on the furnace @ wall like in the conventional device, the exhaust gas suction port on the furnace side wall should be equipped with a damper device or Preferably, the furnace is provided with brick masonry for the partition, allowing the flow of combustion gases from the burner to be adjusted.Thus, according to the invention, the flow of combustion gases in the furnace is controlled by the burner outlet. If it travels straight, it reverses at about 50% of the y furnace length and is discharged from the exhaust gas suction port installed in the hearth.

In addition, even when an exhaust gas suction port is provided in the furnace side wall as in the conventional case, the combustion gas from the auxiliary burner is not immediately discharged through the exhaust gas suction port, but most of the combustion gas is circulated inside the furnace. is discharged from the exhaust gas inlet installed in the hearth. Therefore, the entire lower part of the material to be heated is heated at an average rate of 100%, which means that the heating time in the soaking furnace is shortened, and the set temperature inside the furnace can be lowered, resulting in a reduction in fuel consumption.
Becomes T-noh.

By the way, in existing soaking furnaces, an outlet for bricks, etc. after repair and a cinder hole are already provided in the hearth, so when implementing the present invention in such existing soaking furnaces, K. At the same time, such a cinder hole is used as a suction port for combustion exhaust gas and connected to the existing flue, and at the same time, an auxiliary burner device is installed at the conventional exhaust gas suction port provided below the burner side.
If necessary, it is only necessary to attach a damper device to this. The number and position of exhaust gas suction ports provided in the hearth are appropriately determined depending on the dimensions, capacity, and set heating temperature of the furnace. Preferably, for example, when a soaking furnace of 150 T/CH has a width of 4100 mm, a depth of 4550 m, and a length of 7700 m, and the set temperature inside the furnace is 1250 °C, a
r? It is sufficient to install two of them 2 m from the burner side.

The invention will now be further described in connection with the accompanying drawings.

FIG. 1 is a sectional view of a conventional soaking furnace 1, in which a main burner device 2 and an auxiliary burner casing 3 are arranged in a unidirectional firing relationship. Bloom 4 with heated material
are heated by the combustion gases of these burner devices. Waste waste discharged from the waste waste suction port 5 provided at the lower part of the furnace 11111m is discharged into the atmosphere from the chimney 8 through the downtake section 6↓ and the horizontal flue 7. The flow of combustion gas within the furnace becomes a U-shaped flow, as shown by the arrow in the figure. Therefore, insufficient heating occurs in the lower part of the bloom 4. The auxiliary burner device 8 is installed to solve this problem of insufficient heating, but because it is installed near the exhaust gas inlet, only the part of the auxiliary burner that is in contact with the combustion flame is heated. , 5 Akatsuki gas is also mostly immediately discharged from the exhaust gas inlet 5
It will be ejected from the tank.

FIG. 2 is a schematic cross-sectional view of the soaking P21 according to the present invention,
In the illustrated example, the combustion gas discharged from the main burner device 22 at the upper part of the furnace side wall flows through the furnace as shown by the arrow in the concave shell, and the furnace length is reversed from the electric potential of y cows and installed in the hearth. The exhaust gas is sucked into the plurality of exhaust gas suction ports 23 and flows through the exhaust gas guide path 24 to the flue 25 .

The gas does not turn around and return from the wall opposite to the burner, but at the furnace head it turns around from about 50% N, so it retains sufficient heat even when it reaches the above-mentioned exhaust gas suction port 28, for example. Therefore, the area around this area can be sufficiently heated.

Next, an auxiliary burner device 2 is provided below the main burner 11t22.
6 is provided. In the illustrated example, since this auxiliary burner device [26 is installed in the second exhaust gas suction port 27 on the furnace side wall, there is a brick masonry portion 28 for the partition υ near the entrance of the second flue gas suction port 27. It is provided. Instead of the brickwork for the partition υ, an appropriate damping device may be provided at the second exhaust gas inlet to adjust the flow of combustion gas in the furnace. In that case, a portion of the combustion gas is discharged from the second exhaust gas inlet 27 through the flue 25 depending on the degree of opening and closing of the damper device.

That is, by adjusting the opening degree of this damper device, the flow of combustion exhaust gas within the furnace can be adjusted. Therefore, by detecting the burner side temperature and the opposite side temperature and adjusting the damper opening degree based on this temperature difference, it is possible to change the gas flow and thereby eliminate the temperature difference in the soaking furnace. can. As mentioned above, applying the present invention to an existing furnace is the same because it is possible to use the crotch meat of a competitor. A part of the cinder hole that has already been installed in the soaking hearth is used as a discharge port for the hearth material or scale (7-dah hole), and exhaust gas is extracted from this location and then transferred to the conventional dow/take section. It may also be connected to a viewing window (sight hole) to serve as a combustion exhaust gas conduit. Furthermore, an auxiliary burner and a damper device are provided at the conventional exhaust gas allowance port in the lower part of the burner side, and the flow of the combustion exhaust gas discharged through the cinder hole can be adjusted by this damper device.

Next, a specific example of applying the present invention to an existing furnace will be described.

Drain the cider hole installed in the hearth of the soaking furnace 21.
In addition to being utilized as the exhaust gas suction port 28, this cinder hole and the flue 26 are connected through the flue gas conduit 24 to serve as a passage for combustion exhaust gas.Furthermore, an auxiliary burner 26 and an auxiliary burner 26 are installed near the existing exhaust gas suction port 27. Approximately 160 pieces of bloom were charged into a one-way soaking furnace with a capacity of 160 t/CM and equipped with a shingle stacking section 28, and then ignited.

Even though the heating temperature in the furnace was set constant, the rise in the temperature at the bottom of the bloom was remarkable according to the present invention. That is, even though the temperature inside the furnace was set to 1250°C in both cases, according to the present invention, the bloom lower temperature rose to 1j1280'c after 8 hours of heating, whereas in the case of the conventional apparatus shown in FIG. Even after 10 hours, the temperature at the bottom of the plume (surface temperature) was 1000°C. At that time,
The difference from the temperature at the top of the bloom was 60°C in the example of the present invention and 80°C in the conventional example. As described above, according to the present invention, the heating time can be reduced to 8 hours, which is 2 hours shorter than the conventional method, and the fuel consumption rate is 174 x 10" Kcal/l, which is about 17%.
I was able to reduce it.

The results of this example are summarized in Table K below.

Fuel: Blast furnace gas + coke oven gas 2700 Ka4/
NJ Blue^ Lower temperature (Adjustment point is indicated by ↓ in the figure.

Bloom upper temperature: II O# @In addition, the temperature of the burner and the temperature of the side opposite to the burner are detected, and this temperature is used to control the damper device (1 not shown) for exhaust gas switching provided at the exhaust gas inlet 27. It is also possible to automatically change the gas flow within the furnace to improve temperature distribution within the furnace. Further, in this example, exhaust gas is sucked through one cinder hole, but several cinder holes may be used, or the exhaust gas I & exhaust port may be installed separately from the cinder hole.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional soaking furnace, and FIG. 2 is a schematic cross-sectional view of a soaking furnace according to the present invention: Soaking Furnace 25
: Akira Hirose, Patent Attorney, Patent Attorney for the applicant

Claims (1)

[Claims] An upper one-way firing soaking furnace in which a main burner device is provided in the upper part of the furnace side wall and an auxiliary burner device is provided in the lower part of the furnace W wall, characterized in that at least one or more exhaust gas suction ports are provided in the hearth part, Upper one-way firing soaking furnace.