CN2263655Y - Blast-furnace hearth furnace bottom lining structure - Google Patents

Abstract

The utility model relates to a hearth bottom lining structure of a blast furnace, which is particularly suitable for the hearth bottom lining of a 1000m blast furnace above grade ³ . The utility model integrates the heat conduction method and the refractory material method, and adopts a hot-pressed carbon brick-ceramic cup combined furnace hearth bottom lining structure. Hot-pressed carbon bricks are built in the surrounding area; the inner side of the hearth wall is made of brown corundum prefabricated blocks, and the outer side is composed of hot-pressed carbon bricks and large carbon bricks. Or more than 15 years, with significant economic benefits.

Description

Blast furnace hearth bottom Lining structure

The utility model belongs to a refractory inner lining structure of a hearth hearth of a blast furnace, and is particularly suitable for inner lining of a hearth hearth of a 1000m blast furnace above grade ³ .

At present, in order to prolong the life of blast furnace hearth, two solutions are popular in the world: heat conduction method and refractory method. The technical principles and measures of these two technical systems are not the same, but both are feasible measures to prolong the life of the blast furnace hearth bottom.

1. The hearth bottom lining structure of hot-pressed carbon bricks is the design scheme of the hearth bottom lining by heat conduction method. This structure was proposed by the US UCAR company and implemented in more than 300 blast furnaces in the world, and has achieved success. Its characteristics are: the hot-pressed small carbon bricks produced by the "hot-pressing method" in the "garlic-shaped" abnormal erosion area of the hearth, because the hot-pressed carbon bricks have high thermal conductivity, resistance to molten iron permeability, and chemical erosion resistance With the help of the cooling effect of the stave, the 1150°C isotherm (the solidification line of molten iron) can be pushed to the center of the hearth as much as possible, and a protective "slag skin" or "slag skin" can be formed on the hot surface of the carbon brick The "iron shell" protects the carbon brick from the penetration of molten iron, erosion, chemical erosion of alkali metals and thermal stress damage, so as to prolong its service life. However, due to the high requirements for the cooling system and the high thermal conductivity of the hot-pressed carbon brick, this structure will cause a large heat loss in the hearth when the heat balance is not reached (that is, when the slag skin or iron shell is not formed). In addition, the initially formed slag skin or iron shell is relatively unstable when the furnace condition fluctuates, and it is easy to fall off.

2. The hearth bottom lining structure of the ceramic cup is the design scheme of the hearth bottom lining of the refractory method. This structure was developed by French company SAVOIE, and it has been applied in more than 30 blast furnaces all over the world in the past 10 years and has achieved success. The characteristics of this structure are: the hearth bottom area of the blast furnace is built with microporous large carbon bricks, large brown corundum prefabricated blocks are built on the inner side of the ring-shaped carbon bricks on the hearth wall, and 2 to 3 layers are built on the hearth carbon bricks. Mullite bricks form a cup-shaped ceramic lining in this area, the so-called "ceramic cup". The main feature of the ceramic cup is to use low thermal conductivity ceramic material to block the 1150°C isotherm in the ceramic layer, so that the carbon brick can avoid the brittle fracture temperature range of 800-1100°C. Due to the existence of the ceramic cup, the molten iron does not directly contact the carbon brick, and the structural design alleviates the penetration, erosion and chemical erosion of the molten iron and alkali metal on the carbon brick. The mullite and corundum used are ceramic materials with low thermal conductivity, which have high resistance to molten iron penetration and mechanical erosion, and the hearth heat loss is small, which can increase the temperature of molten iron by 18-25 °C. However, since this structure uses large microporous carbon bricks, after the hearth ceramic cup disappears, the carbon bricks will still be in direct contact with the molten iron, and some defects of the microporous large carbon bricks will be exposed, and there will still be "garlic head" formation. "The hidden danger of abnormal erosion and hearth ring cracking.

For a modern large-scale blast furnace, its service life should reach more than 15 years. Therefore, using high-quality new refractory materials and improving the design structure of the hearth bottom lining are effective measures to prolong the service life of the blast furnace.

The purpose of this utility model is exactly to overcome the deficiency of above-mentioned prior art, thereby designs a kind of can satisfy blast furnace production requirement, and its life-span reaches or exceeds 15 years novel hearth furnace bottom lining structure.

In order to achieve the design purpose, the utility model integrates the heat conduction method and the refractory material method, and adopts a hot-pressed carbon brick-ceramic cup combined furnace hearth bottom lining structure. The bottom of the furnace is covered with large carbon bricks, mullite bricks (ceramic mat) are built in the central area, and hot-pressed carbon bricks are built in the surrounding area; brown corundum prefabricated blocks (ceramic wall) are built on the inner side of the hearth wall, Build hot-pressed carbon bricks below the center line, and build ring-shaped large carbon bricks in the hearth above the center line of the iron mouth.

The hearth bottom lining is characterized by building hot-pressed small charcoal bricks in the "garlic tip-shaped" abnormal erosion area of the hearth, and laying mullite bricks on the upper part of the charcoal bricks at the bottom of the hearth. Brown corundum prefabricated blocks are built on the inside to form a combined lining structure of hot-pressed carbon bricks-ceramic cup hearth and bottom. This structure combines the technical advantages of hot-pressed carbon bricks and ceramic cups to maximize their strengths and avoid weaknesses, and give full play to their respective technical advantages. It can prevent the penetration of molten iron, reduce the mechanical erosion of molten iron, eliminate "garlic head" abnormal erosion and hearth ring cracks, and at the same time It can also reduce the heat loss of the hearth, increase the temperature of molten iron, and greatly prolong the life of the blast furnace.

The utility model will be described in detail below in conjunction with the accompanying drawings.

Taking a blast furnace with an effective volume of 2536m ³ as an example, the hearth diameter is 11560mm, the dead iron layer depth is 2200mm, and there are 3 tapholes. The bottom of the hearth of the blast furnace adopts a combined lining structure of hot-pressed carbon bricks-ceramic cups. The bottom lining of blast furnace hearth is mainly composed of six parts.

1. The 4 layers of the bottom of the furnace are covered with large carbon bricks;

2. Three layers of ceramic pads (mullite bricks) at the bottom of the furnace;

3. There are 5 layers of ceramic walls (brown corundum prefabricated blocks) on the inner side of the hearth wall;

4. Below the center line of the iron mouth on the outer side of the hearth wall, the junction of the hearth and the bottom of the hearth (that is, the "garlic head" abnormal erosion area) is close to the cooling wall, and a total of 26 layers of hot-pressed small carbon bricks are built;

5. A total of 6 layers of ring-shaped large carbon bricks are built above the center line of the iron hole outside the hearth wall;

6. High-alumina bricks (Al ₂ O ₃ ≥ 80%) shall be built on the ring-shaped carbon bricks of the hearth and the combination bricks above the ceramic wall and below the tuyere combination bricks.

As shown in Figure 1, on the carbonaceous leveling layer 14 at the bottom of the furnace, 4 layers of large carbon bricks 7 are fully paved, with a total thickness of 1768mm. 13 filling. The 4th layer is covered with charcoal bricks 7, and the central area of the furnace bottom is built with mullite bricks 4 as the 1st layer of ceramic pads. The bricks are built in a herringbone shape, and both sides of the bricks along the direction of the brick line are inclined-plane bite structures (see Figure 2) to enhance the stability of the masonry. Around the mullite brick 4, hot-pressed carbon bricks 8 are built close to the stave 12. The space between the mullite brick 4 and the hot-pressed carbon brick 8 is filled with carbonaceous tamping material to absorb the thermal expansion of the mullite brick 4 . The second layer of ceramic pads is mullite brick 3, and the masonry structure is the same as that of the first layer of ceramic pads (see Figure 3). Build hot-pressed carbon bricks 8 around the mullite bricks 3, leave a gap of 60mm between the mullite bricks 3 and the hot-pressed carbon bricks 8, and use carbonaceous ramming material 10 to fill, and its function is to absorb mullite 3, and the mullite brick 3 and the hot-pressed carbon brick 8 are in close contact through the carbonaceous ramming material 10, which is beneficial to heat conduction.

The third layer of ceramic pad is mullite brick 2. Since the third layer of ceramic pad is in contact with molten iron, in order to prevent the leakage of molten iron and the uplift of mullite brick 2, this layer of ceramic pad is built by ring-shaped masonry (see Figure 5) , and between each ring is also a bevel bite structure in the radial direction. The center part of the third layer of ceramic pad is a conical central brick 5 composed of 2 brown corundum prefabricated blocks. There is a 50mm gap between the central brick 5 and the mullite brick 2, which is filled with ceramic tamping material 6 to prevent The molten iron leaks down the brick joints. Around the third layer of ceramic pad mullite brick 2, build the first layer of ceramic wall brown corundum prefabricated block 1, and use a slope between the third layer of ceramic pad mullite brick 2 and the first layer of ceramic wall brown corundum prefabricated block 1 Bite masonry to ensure close contact between the ceramic pad and the ceramic wall, prevent the leakage of molten iron and the floating of the ceramic pad, and enhance the overall stability of the masonry. Ceramic fiber 16 is inlaid between the top surface of the second layer of ceramic pad and the bottom surface of the first layer of ceramic wall.

The hearth ceramic wall has 5 layers in total. Two brown corundum prefabricated blocks 1 adjacent to each layer are staggered up and down. There are no joints in the horizontal direction of each layer. In order to enhance the overall stability of the masonry, on the cold surface of the ceramic wall, Two adjacent brown corundum prefabricated blocks 1 are connected by key bricks 19, as shown in Fig. 5 and Fig. 6 . At the junction of the hearth and the bottom, the ceramic wall transitions at an oblique angle, and the thickness increases to resist the mechanical erosion caused by the circulation of molten iron, as shown in Figure 1. The ceramic wall in the tap area has a convex structure (see Figure 7) to resist the violent erosion of molten iron during tapping. On the outer side of the ceramic wall, below the center line of the iron gate, build hot-pressed carbon bricks 8 close to the cooling wall; above the center line of the iron gate, build ring-shaped carbon bricks 9 in the furnace hearth, and fill the space between the ring-shaped carbon bricks 9 and the cooling wall 12 Ramping material 13. A 60mm expansion joint is left between the ceramic wall, the hot-pressed carbon brick and the ring-shaped carbon brick of the hearth, and the carbonaceous ramming material 10 is filled in it to absorb the radial thermal expansion of the ceramic wall and facilitate heat conduction. Ceramic fibers 17 are also inlaid between the ceramic wall and the high alumina brick 18 on the upper part of the hearth to absorb the interaxial thermal expansion of the ceramic wall, as shown in FIG. 1 .

In order to prevent the mechanical damage caused by the charge on the hot surface of the ceramic cup when the furnace is opened, and the thermal stress caused by the rapid temperature rise of the ceramic cup after the furnace is opened, a layer of clay bricks 11 is built on the hot surface of the ceramic cup as a protective brick. see picture 1.

The utility model integrates the heat conduction method and the refractory material method hearth bottom lining design system, and concentrates the technical advantages of hot-pressed carbon bricks and ceramic cups. The two complement each other and have many advantages:

1. Prevent the infiltration of molten iron. Due to the use of ceramic refractory materials with low thermal conductivity, the 1150°C isotherm is blocked in the ceramic layer. In addition, the special design structure of the ceramic cup and the thermal expansion of the material make the brick joints tighten and minimize the impact of molten iron. Osmotic erosion of carbon bricks.

2. To reduce the flow erosion of molten iron, ceramic cups must have a reasonable depth of dead iron layer, which is generally about 20% of the diameter of the hearth. The depth of the dead iron layer is reasonable, which can change the flow direction of molten iron in the hearth, so It can reduce the mechanical erosion of molten iron on the furnace bottom and hearth wall.

3. Improve the thermal stability of the hearth and reduce the heat loss of the hearth. After the ceramic cup is used, the temperature of the molten iron can be increased by 18-25°C, which can reduce the energy consumption of the process and create favorable conditions for steelmaking production.

4. Conducive to the operation of the blast furnace. The increased heat reserve of the hearth makes the blast furnace easy to operate, and provides good conditions for promoting the steady movement of the blast furnace, activating the hearth, re-airing operation to smelt low-silicon and low-sulfur pig iron, and reducing fuel consumption. , and can reduce hearth accumulation, tuyere slag filling and other accidents.

5. Significantly extend the service life of the blast furnace. The ceramic cup and the hot-pressed carbon brick are connected by carbonaceous tamping material, so that the two are in close contact. Under high temperature conditions, the ceramic cup is used to protect the hot-pressed carbon brick, so that it does not directly contact the molten iron, so that it can avoid the penetration, mechanical erosion and chemical erosion of molten iron and alkali metal. At the same time, the ceramic material with low thermal conductivity is used to make the 800-1100 ℃ isotherm (the brittle fracture reaction temperature of carbon brick) be blocked in the ceramic layer for a long time, so that the carbon brick can avoid the temperature range of brittle fracture. The thermal conductivity, resistance to molten iron permeability, chemical corrosion resistance and thermal stress resistance of hot-pressed carbon bricks are superior to those of microporous large-block carbon bricks and ordinary large-block carbon bricks, and the high thermal conductivity of hot-pressed carbon bricks can be used , to provide effective cooling for the ceramic mug, thereby prolonging the service life of the ceramic mug. Even after the ceramic cup is damaged or disappears, the hot-pressed carbon brick will directly contact the molten iron. Because the hot-pressed carbon brick has high thermal conductivity, resistance to molten iron penetration, and chemical corrosion resistance, it can still rely on effective cooling. Make its hot surface generate a protective slag skin or iron shell to maximize the life of the blast furnace.

6. Hearth and bottom hot-pressed carbon bricks—ceramic cup combined lining structure concentrates the essence of heat conduction method and refractory material design system. ) has introduced high-quality new refractory materials such as hot-pressed carbon bricks and ceramic cups that cannot be produced in China, while most of the hearth bottom area is made of domestic large carbon bricks, mullite bricks, high alumina bricks, and clay bricks. etc., saving a large amount of foreign exchange investment, which is in line with China's national conditions and the actual conditions of various enterprises.

7. Simplify the construction process, which is conducive to improving the quality of furnace construction. Due to the small shape of the hot-pressed carbon brick, it is convenient for furnace construction, while the ceramic wall corundum prefabricated block is a large structure, and special hoisting tools are used to simplify the construction process. , shorten the construction period. Moreover, the manufacturing precision of hot-pressed carbon bricks and ceramic cup materials is high, and the dimensional error is small, which is conducive to improving the quality of furnace construction.

The effect of the utility model is to greatly extend the life of the hearth bottom, slow down the erosion of the hearth bottom lining, increase the temperature of molten iron, reduce the heat loss of the hearth, reduce the energy consumption of the process, promote the smooth operation of the blast furnace, and facilitate the operation of the blast furnace , Its life expectancy can reach more than 15 years. For blast furnaces of 1000m above level ³ , it has high promotion and application value.

Additional Notes:

Figure 1 is the structure diagram of the hearth furnace bottom hot-pressed carbon brick-ceramic cup combination lining

Figure 2 Schematic diagram of the first layer of ceramic pad at the bottom of the furnace

Figure 3 is a schematic diagram of the second layer of ceramic pads at the bottom of the furnace

Figure 4 is a schematic diagram of the ceramic pad on the third layer of the furnace bottom

Figure 5 is a schematic diagram of ceramic wall masonry structure

Figure 6 is a connection structure diagram of ceramic wall key bricks

Figure 7 is a structural diagram of ceramic wall masonry in Tiekou District

in:

1 Brown fused alumina prefabricated block MONOCORAL

2 mullite bricks MS ₄

3 mullite brick MS ₄

4 mullite bricks

5 center bricks (brown corundum prefabricated block MONOCORAL)

6 ceramic ramming material CORAL

7 The bottom of the furnace is covered with charcoal bricks

8 Hot-pressed small carbon brick NMA

9 hearth ring large carbon brick

10 carbonaceous pounding material AMC66K

11 Clay Bricks

12 staves

13 carbonaceous ramming material

14 carbon leveling layer

15 carbonaceous pounding material RP ₄

16 ceramic fiber CARTOLANE

17 ceramic fiber CARTOLANE

18 high alumina brick

19 key bricks

Example

A blast furnace was put into operation on August 9, 1994. The bottom of the hearth adopts a combined lining structure of hot-pressed carbon bricks and ceramic cups.

Since the blast furnace was opened for more than a year, the production has steadily increased. The effective volume utilization factor of the blast furnace has stabilized at about 2.2t/(m ³ .d), the coke ratio into the furnace is 410kg/t, the coal ratio is 90kg/t, and the fuel ratio is 500kg/t. The hearth of the blast furnace is in very normal working condition, and no accidents such as hearth accumulation and tuyere filling with slag have occurred. The heat load of the hearth is about 3500-4000W/m ² , and the actual temperature changes of the thermocouples at each part of the hearth bottom are stable. The blast furnace hearth is active, has ample heat reserves, is easy to operate, and has low fuel consumption. Under the condition of the same content of molten iron [Si], the temperature of molten iron in this blast furnace is 15-25°C higher than that of other blast furnaces, which creates favorable conditions for steelmaking production. The production practice proves that the application of hot-pressed carbon brick-ceramic cup hearth hearth bottom combined lining technology has achieved the following preliminary results:

1 The heat of the hearth is abundant, the hearth works evenly and actively, the heat loss of the hearth is reduced, and the temperature of molten iron is 15-25°C higher than that of other blast furnaces. Since the blast furnace was opened, there have been no accidents such as hearth accumulation and tuyere filling, and the number of tuyere losses is only about half of that of other blast furnaces;

2 Because the hearth works evenly and actively, the heat is abundant, and the fuel ratio is reduced, creating favorable conditions for increasing the amount of coal injection. In November 1995, the coke ratio into the blast furnace was 415kg/t, but the coal ratio was 96kg/t, the coke ratio was 5kg/t, the fuel ratio was 516kg/t, and the injection rate was 18.6%. However, due to the low wind temperature (the annual average is only 950°C), the influence of unfavorable factors such as the lack of oxygen enrichment in the blast and the deterioration of raw fuel conditions, the further increase in the amount of coal injection is limited;

3 It is beneficial to the smelting of low-silicon and low-sulfur pig iron. Due to the abundant physical heat in the hearth, conditions are created for smelting low-silicon and low-sulfur pig iron. From January to November 1995, the molten iron contained 0.428% [Si] and 0.02% [S], while under the same raw material conditions, another blast furnace with the same volume as this blast furnace contained 0.49% [Si] and [S] ] is 0.0018%.

4 Shorten the re-airing time of the blast furnace. After the blast furnace is shut down, due to the high heat reserve in the hearth, the blast furnace is re-aired quickly, and it is easy to return to the normal furnace condition, and the temperature drop of slag and iron after re-airing is small, and there is no slag and iron discharge after re-airing difficult phenomenon.

5 The physical heat of slag and iron is improved, the fluidity is improved, and the phenomenon of slag sticking grooves is greatly reduced, which reduces the labor intensity of workers in front of the furnace and improves working conditions.

6 The temperature of the furnace hearth and furnace bottom thermocouples changes steadily, and the daily average temperature change is ±0-10°C. After more than a year since the furnace was started, the average temperature rise rate on the thermoelectric side is only 0.7-1.5°C/month. According to computer simulation calculations, the 1150°C isotherm of the blast furnace is located near the hot surface of the ceramic cup, and there is no obvious erosion of the ceramic cup.

The main technical parameters

Blast furnace effective volume 2536m ³

Hearth diameter 11560mm

Hearth height 4200mm

Depth of dead iron layer 2200mm

The number of iron ports 3

Furnace Bottom Thickness 2800mm

Bottom ceramic pad thickness 1032mm

The thickness of the furnace bottom is covered with charcoal bricks 1768mm

The thickness ratio of ceramic layer and carbon brick layer at the bottom of the furnace is 1:1.7

Hearth ceramic wall vertical section thickness 400mm

Ceramic wall thickness in iron mouth area 840mm

Hearth hot-pressed carbon brick vertical section thickness 1237mm

Ceramic wall outer diameter 12060mm

Inner diameter of ceramic wall 11260mm

Ceramic wall height 4950mm

Height of hot-pressed carbon bricks 3013.4mm

Claims (1)

1. A blast furnace hearth bottom lining composite structure, which is made of large carbon bricks, hot-pressed carbon bricks, mullite bricks, brown corundum prefabricated blocks, etc., and is characterized in that the bottom of the furnace is covered with large blocks of carbon For bricks, mullite bricks (ceramic mat) are built in the upper central area, and hot-pressed carbon bricks are built in the surrounding area; brown corundum prefabricated blocks (ceramic wall) are built on the inner side of the hearth wall, and hot-pressed carbon bricks are built below the center line of the outer iron mouth , above the center line of the iron mouth, build a ring-shaped large block of carbon bricks in the hearth.

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