JPH08285466A - Sintering cake support stand and its cooling method - Google Patents

Abstract

PURPOSE: To obtain a sintering cake supporting stand and its cooling method, that is adapted for a sintering machine used in iron and steel industrial fields to extend its service life. CONSTITUTION: Plate-like or column-like sintering cake support stands 7 to support a sintering cake layer from below are installed on a sintering palette of a downward suction type sintering machine in parallel with the traveling direction of the palette. Cooling pipes 5 each having an air suction port 6 and an air intake 4 are arranged inside the sintering cake support stands 7, and the air intake 4 is located at a place where static pressure in the sintering machine is relatively higher than that at the place where the air suction port 6 is located. Thereby, generation of crack and wearing of the sintering cake support stands 7 is remarkably reduced and the service life is extended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sinter cake support stand for a sinter that is used in, for example, the fields of iron and steel and non-ferrous smelting using a sinter, and a cooling method thereof.

[0002]

2. Description of the Related Art A raw material charged on a downward suction type sintering pallet is ignited by a fixed fuel such as powder coke mixed with the raw material in an ignition furnace, and a solid fuel such as powder coke mixed with the raw material. A part or most of the raw material is melted by the heat of combustion and then solidified, so that the sintering raw material is sintered in bulk from above the raw material layer to form a sintered cake layer.

The region where the solid fuel is burned, that is, the combustion zone, is vulnerable to the load because a part of the sintering raw material is melted. The air flow resistance of the sintered layer increases due to the collapse of the voids that are the flow paths of air or gas in the combustion zone due to the weighting.

As a measure for improving the ventilation resistance, for example, Japanese Unexamined Patent Publication No. Hei 2
No. 293586 discloses a sintered cake support stand which is a support having a convex shape on the bottom surface or inner wall of the sintering pallet.

Parts exposed to high temperatures in the sinter pallet truck, such as the stand and the grate, cause cracks and deformation due to thermal stress and thermal shock. The material was devised such as the selection of highly resistant material, or the shape was devised by increasing the curvature radius of the notch to increase the thickness of the member and avoid concentration of thermal stress.

As a general protection measure for equipment exposed to high temperatures, a heat insulating material is placed on the equipment surface in contact with the high temperature portion. For example, in the case of a grate of a sinter truck, a bed mine is spread between the grate upper surface and the sintered layer for 30 to 50 mm. Also, the surface of the equipment exposed to high temperatures is cooled. For example, like a stave used to cool the furnace body of a blast furnace,
A method of flowing water through a built-in cooling pipe to cool it is also known.

[0007]

By the way, a stand installed to support the sintered cake layer attached to the bottom of the sintered pallet truck from below has a maximum surface temperature of 1200 ° C. or higher on the sintered strand. After sintering, the orbit that returns to the charging section on the endless orbit is exposed to the atmosphere and cooled to about room temperature. That is, a very large thermal history is repeated between 1200 ° C. or higher and room temperature.

In the case of a stand made of economical heat-resistant cast steel that can be industrially used, for example, an alloy steel containing chrome as the main alloying component, according to the results of the use test by the inventor, the use period is from 1 month to 6 months. In the meantime, the above-mentioned thermal history caused cracks, the severely damaged stand was broken, and a part of the stand was dropped. That is, since the life is extremely short, there was a practical problem.

[0009] As a measure to put a refractory material such as degenerate brick on the surface of the stand, in addition to the large repeated thermal history as described in the preceding paragraph, the machine for removing the sintered cake in the sinter machine mine section is used. Since the refractory material easily peels off and falls off due to the impact force, it is applied to protect the stand that is installed at the bottom of the sintering pallet trolley to support the caked layer from below. I can't.

A measure for forcibly circulating a cooling medium such as water through a built-in cooling pipe with a pump, like a stave for cooling a blast furnace body, is used when a pallet truck with a stand is moving. Piping of the cooling medium is difficult.

The present invention solves the above problems and is a simple sintered cake which is installed on the bottom of a sintering pallet truck for the purpose of extending the life of the stand and which supports the cake-like layer from the bottom after sintering is completed. A support stand and a cooling method thereof are provided.

[0012]

[Means for Solving the Problems]

(1) The present invention is a plate-shaped or columnar sintered cake support stand that supports a sintered cake layer installed in parallel with the pallet traveling direction on a sintering pallet of a lower suction type sintering machine, A cooling pipe is provided inside the sintering support stand, the cooling pipe has an air suction port and an air intake port, and the air intake port is installed at a site where the static pressure in the sintering machine is relatively higher than the air suction port. Is a stand for supporting a sintered cake.

(2) Further, in the support stand described in the above item (1), a cooling pipe arranged in the sintered cake support stand has an air suction port opened to the windbox side by communicating with the sintering pallet, The cooling pipe is embedded in the side surface of the sintering pallet and has an air intake opening to the side surface of the sintering pallet.

(3) Further, in the support stand described in the above item (2), the spraying mechanism for spraying and supplying water is provided at the air inlet of the cooling pipe.

(4) The method of the present invention is a plate-shaped support for supporting from below a sintered cake layer installed parallel to the pallet traveling direction on the sintering pallet during the sintering operation by the downward suction type sintering machine. Alternatively, the air suction port side of the cooling pipe installed in the columnar sintered cake support stand is brought to a negative pressure by suction from the wind box below the sintering machine to introduce air into the cooling pipe from the air intake port. The method for cooling a sinter cake support stand is characterized by cooling the sinter cake support stand.

(5) In the method for cooling the support stand according to the above (4), the position of the sintered strand where the temperature of the sintered cake support stand is 400 ° C. or lower during the sintering operation by the downward suction type sintering machine. The air inlet is closed, and the air inlet is opened to introduce air into the cooling pipe at the position of the sintered strand where the temperature of the sintering support stand exceeds 400 ° C.

[0017]

The function of the sintered cake support stand will be described with reference to FIG.

In the downward suction type Dwightroid sintering machine, the sintering raw material is charged on the sintering pallet truck from the drum feeder 8 of the charging apparatus, and the pallet truck moves to move in the direction of arrow 9. Moving. Next, the surface of the raw material is ignited in the ignition furnace 10. Then, by making the wind box 1 installed below the grate surface negative pressure, air is sucked downward from above in the sintering raw material layer charged above the pallet truck grate surface and burned with this air. The carbonaceous material or solid fuel in the raw material is burned to sinter the raw material.

The combustion zone 14 is the range where the carbonizing agent or solid fuel is burning. The upper part of the combustion zone is a layer that has been sintered to form a sintered cake, and is referred to as a sintered cake layer 15.
Below the combustion zone 14 is the raw material layer 13. On the other hand, the pallet truck is slid along the endless track, and the sintered cake produced by sintering is discharged from the sintering machine discharge section 11. From here the sinter cake is discharged in direction 12.

The sinter cake support stand is installed as shown in FIG. 1, and in a section on the mine ore side from the point where the lower surface of the sinter cake layer 15 of FIG. The load of the sintered cake will be received by the support stand.

Therefore, in this section, the load of the sintered cake is not applied to the combustion zone 14, so that the voids of the combustion zone are prevented from being crushed by the load of the sintered cake, and the ventilation of the air passing through the combustion zone is prevented. The resistance is reduced and the amount of passing air is increased. Therefore, the production rate of sintering can be increased. The above is the purpose of installing the sintered cake support stand.

FIG. 1 is a perspective view schematically showing the parts necessary for explaining the sinter pallet truck, the support stand, the cooling pipes, etc. installed in the sinter, extracted from the sinter. The wind box 1 installed below the sintering pallet truck 2 is 500 to 2000 mmAq (4.
It is a negative pressure of 9 to 19.6 k-Pa).

On the other hand, in a cross section of the pallet truck taken along the vertical direction, the outer surfaces 3a, 3 other than the surface contacting the wind box 1
b and 3c are atmospheric pressure. Therefore, for example, as shown in FIG. 1, the air suction port 6 of the cooling pipe is provided open to the wind box 1 side,
When the air intake 4 of the cooling pipe is provided open to the outside air portion 3c and the pipe 5 passing through the inside of the stand is installed, the air flows from the air intake 4 through the cooling pipe 5 inside the stand to the air suction port 6. The sinter cake support stand 7 is cooled by this air flow.

In the above description, the cooling pipe having the air suction port and the air intake port of the cooling pipe opened to the wind box 1 and the outside air portion 3c has been described, but from the atmospheric pressure to the wind box suction pressure inside and outside the sinter pallet truck. Since the static pressure between the two is distributed, if the air suction port 6 is provided at a portion where the static pressure is relatively high, a flow of cooling air or combustion gas can be obtained in the cooling pipe.

The point is that the gas having a temperature lower than that of the outer surface of the support stand needs to flow in the cooling pipe, and the air suction port and the air intake port of the cooling pipe are not limited to the outside air surface and the wind box surface. .

FIG. 3 shows one method of closing the air suction port 6 of the cooling pipe.
For example, the air passing through the cooling pipe 5 is a wasteful leak that does not contribute to the sintering production, and increases the power consumption of the main exhaust fan. Iron alloy steel containing chrome or the like, which is economical, as a main alloy component, has a sharp decrease in strength at a temperature of 400 ° C to over 500 ° C. On the other hand, the economical alloy steel containing iron as a main component has a strength to withstand the thermal stress in the stand due to the thermal history at least at 400 ° C or lower.

That is, the outside temperature of the sintered cake support stand is
It is not necessary to cool the sinter cake support stand in the section of 400 ° C or lower. Therefore, it is rational from the viewpoint of main exhaust fan power consumption reduction and stand protection to allow air to flow through the cooling pipe only in the sections exposed to temperatures above 400 ° C. and not to flow in other sections. Generally, the high temperature section in the sintered layer is the combustion zone 14 shown in FIG. 2 and its vicinity.

By preliminarily estimating or measuring the speed at which the combustion zone 14 in the sintered layer moves downward from the upper surface of the layer, it is possible to distinguish the section where the support stand is exposed to more than 400 ° C. from the section other than that. Is possible. It is sufficient to protect the stand if the cooling air is allowed to flow only in the region where the combustion zone has a high frequency of occurrence of cracks, that is, in the region corresponding to the section of 400 ° C. or higher, and the leakage of the air flowing through the cooling pipe 5 Can be reduced to an indispensable amount.

As a method of closing the cooling pipe in a section where cooling is unnecessary, for example, as shown in FIG. 3, a long flat plate is installed parallel to the moving direction of the pallet truck, and the air intake port is slidably contacted. Good.

In order to improve the contact between the flat plate and the air inlet, a double pipe is installed on the outer periphery of the cooling pipe near the air inlet so that the outer pipe can move while sliding with the inner pipe. It is desirable to have a structure in which the end face of the slidable outer pipe is constantly pressed against the flat plate to make contact with the flat plate by utilizing the force and gravity of the spring, for example.

FIG. 4 is a schematic diagram for explaining an air intake 4a for mixing water droplets into the air flowing through the support stand cooling pipe. FIG. 5 is a schematic view in which the vicinity of the air intake port 4a is enlarged in FIG.

When the sintering raw material is fired at a high temperature, that is, when the heat load of the stand is high, or when it is cheap, the alloy steel containing iron as a main component and chromium as a main alloy component is inexpensive. When a stand is made of a material having low heat resistance, it is not enough to flow a small amount of air into the cooling pipe to cool it.

If it is desired to cool with only air, a large amount of air needs to flow, so that a large amount of air leakage is caused by the cooling air and the power consumption of the main exhaust fan for sintering remarkably increases. Therefore, in order to increase the cooling effect with a small amount of air, it is economical to mix water droplets in the air and also add cooling by the latent heat of vaporization of water.

As a method of mixing water droplets into the cooling air flow, the cooling pipe air intake port 4a moves along with the movement of the sinter pallet truck, so that the water supply pipe cannot be connected to the air intake port. Therefore, it is rational to fill the gutter 20 installed near the sintering pallet truck with water, immerse the suction port 19 in the gutter, and move the air intake port 4a in the water tank in the gutter.

In this method, a method of flowing water into the cooling pipe is also possible, and it is possible to prevent wear of the support stand due to heat, but a large amount of water flows into the wind box 1 through the cooling pipe. , Causes water corrosion damage to the main flue.
In order to prevent water from flowing into the wind box 1, water droplets are sprayed and mixed into the air flow of the cooling air at a ratio of water to air of 0.01 to 1.0, and water droplets are inhaled. Is vaporized by a cooling pipe in the support stand and made to flow into the wind box 1.

As a method of mixing water droplets into the air flow in the cooling pipe, as shown in FIG. 5, a nozzle is installed in the air flow of the cooling pipe so that the air jet sucked from the suction port 21 ejects the nozzle. Since the dynamic pressure at the outlet 24 decreases according to Bernoulli's principle, the water 23 in the gutter is sucked upward and ejected from the nozzle 24 to form a water droplet. The water droplets are carried by the air current in the cooling pipe to the stand, and the water droplets evaporate at the portion where the heat load is high and the heat of the stand is taken away.

[0037]

[Example] In the case of a convex flat stand made of an alloy steel containing chrome as a main alloy component without installing a cooling pipe and having a height of about 200 mm from the grate surface, the upper end surface and the upper part are mainly used from one month after use. A crack was generated from the side surface, and after two months of use, about half of the stands attached to the pallet truck were chipped off, requiring replacement. In addition, even in the part that escaped chipping, there was a wear of about 18 mm after 6 months, which was a practical problem.

On the other hand, the wind box 1 in FIG. 1 and the outer surface 3a,
Internal diameter 5m with air suction port and air intake port open to 3c
In the case of the stand of the present invention having a built-in m cooling tube, a small crack of about 5 mm from the upper end surface is generated even after 6 months of use, but the crack progresses and the crack merges. There is no chipping off, and it is possible to maintain a situation that can withstand sufficient use. In this case, the wear of the upper end surface is about 8 mm,
It is about half of the state before applying the present invention.

Further, three sinter support stands were installed at equal intervals in the width direction on each sinter pallet having a width of 5 m, and the air intake was provided at the sinter strand position where the temperature of the sinter cake support stand was 400 ° C. or lower. At the position of the sintered strand where the temperature of the sintering support stand exceeds 400 ° C, the air intake is opened and air is introduced into the cooling pipe. The rate increase is 0.2%
It was a little.

As described above, the sintered cake support stand of the present invention, which has the atomizing mechanism for atomizing and supplying water at the air inlet of the cooling pipe, has been used for about one year, and the crack and the abrasion amount have been measured. There are no cracks with a length of 1 cm or more, and the wear rate of the upper end is about 5 mm, which is about 1/6 or less of that without cooling.
/ It was a year.

[0041]

As described above, according to the sinter cake support stand and the cooling method of the present invention, the air suction port side of the cooling pipe installed in the sinter cake support stand that supports the sinter cake layer from below. To a negative pressure by suction from the wind box below the sintering machine, and a simple cooling device and cooling method that cools the sintering cake support stand by introducing air from the air inlet to generate cracks in the support stand. And wear is greatly reduced, making it possible to provide a long-life sinter cake support stand.

[Brief description of drawings]

FIG. 1 is a perspective view showing a sintering pallet in which a cooling pipe is arranged on a sintered cake support stand of the present invention.

FIG. 2 is a schematic side view showing a structure of a sintering process in a sintered layer and explaining a cooling required section of a sintered cake support stand.

FIG. 3 is a front view showing an example of a method for closing the cooling pipe suction port of the present invention.

FIG. 4 is a front view showing an example of a method of mixing water droplets into the cooling pipe.

5 is an enlarged cross-sectional view of the vicinity of the suction port of the water droplet mixing unit shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wind box 2 Sintering pallet 2a Sintering pallet wheel 2b Sintering pallet pusher roller 3a-3c Outside air part 4 and 4a Air intake of a cooling pipe 5 Cooling pipe in a support stand 6 Air suction port of a cooling pipe 7 Sintered cake Support stand 8 Drum feeder 9 Progression direction of sintering pallet truck 10 Ignition furnace 11 Sintering machine ore discharge part 12 Sintered cake discharge direction 13 Raw material layer 14 Combustion zone 15 Sintered cake layer 16 Fire point 17 Trajectory of upper end of support stand 18 Suction Port Blocking Plate 19 Cooling Pipe Suction Port 20 Gutter 21 Cooling Pipe Suction Port 22 Air Flow Direction 23 Water 24 Nozzle Tip

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masami Fujimoto 20-1 Shintomi, Futtsu City Nippon Steel Corporation Technical Development Division

Claims (5)

[Claims] 1. A plate-shaped or columnar sintered cake support stand for supporting from below a sintered cake layer installed on a sintering pallet of a downward suction type sintering machine in parallel with the pallet advancing direction. A cooling pipe is provided inside the support stand, the cooling pipe has an air suction port and an air intake port, and the air intake port is installed at a site where the static pressure in the sintering machine is relatively higher than the air suction port. And a sinter cake support stand. 2. A sintered pipe supporting stand is provided with a cooling pipe, an air suction port communicating with the sintering pallet and opened to the wind box side, and a cooling pipe embedded in the side direction of the sintering pallet for baking. The sinter cake support stand according to claim 1, further comprising an air intake opening on a side surface of the binding pallet. 3. The sinter cake support stand according to claim 2, wherein a spraying mechanism for spraying and supplying water is provided at the air inlet of the cooling pipe. 4. During the sintering operation by the downward suction type sintering machine,
The air suction port side of the cooling pipe installed in the plate-shaped or columnar sintered cake support stand that supports the sintered cake layer installed parallel to the pallet traveling direction on the sintering pallet from below the sintering machine. The method for cooling a sinter cake support stand, wherein air is introduced into the cooling pipe from the air inlet to cool the sinter cake support stand by suctioning the negative pressure from the wind box. 5. During the sintering operation by the downward suction type sintering machine,
The air intake is closed at the position of the sintering strand where the temperature of the sintering cake support stand is 400 ° C. or lower, and the air intake is opened at the position of the sintering strand where the temperature of the sintering support stand exceeds 400 ° C. The method for cooling a sintered cake support stand according to claim 4, wherein air is introduced into the cooling pipe.