JPH0989460A - Shaft furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the thermal efficiency of a shaft furnace considerably, dispense with cooling water so as to simplify the apparatus, and reduce the work items in the maintenance by introducing a new structure for the grate which enables dispensing with a water-cooled steel-pipe grate and reducing heat-energy loss effectively. SOLUTION: A shaft furnace 10 is charged on a grate 16 placed inside with a material for melting 22 from above, fed from under the grate 16 with a high- temperature combustion gas produced at burners 26, which by being led upward through the grate 16 inside the furnace melts the material for melting 22 by heating. A heat-resistant ceramic 24 formed into a hollow pipe is in use for the grate 16.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to improvement of a shaft furnace, and in particular, burns a liquid fuel such as LNG in a burner, and melts raw materials for cast iron by the heat of combustion to produce molten cast iron or the like. In a shaft furnace, the present invention relates to a technique for effectively avoiding the heat energy loss and dramatically improving the heat energy efficiency.

[0002]

BACKGROUND ART Conventionally, various types of melting devices for heating and melting (melting) a predetermined melting material have been proposed, and one of them has been proposed as a melting device on a rostrul arranged in the furnace. While loading the melted material from the upper inside,
A high temperature combustion gas generated by a burner mechanism is supplied to the inside of the furnace from below the grate, and is introduced into the upper part of the furnace through the grate so that the melting gas is heated and melted by the combustion gas. The furnace is known.

Such a shaft furnace is disclosed in Japanese Patent Publication No. 51-2.
As disclosed in Japanese Patent No. 9481, it can be suitably used for producing a target cast iron molten metal by melting a raw material for cast iron such as scrap or iron scrap, and particularly LNG or the like, not coke. Since it uses a fluid fuel as a heat source, such as the gaseous fuel of the above, compared to the conventional cupola that uses coke, its combustion management is easier, it has less impact on the environment, carbon dioxide and monoxide. It has attracted attention as a new melting furnace because it has features such as the generation of harmful gases such as carbon, nitrogen oxides, sulfur oxides, etc. and the amount of dust generated are significantly reduced, and it is also excellent in terms of thermal efficiency. There is. Among them, in the production of the molten metal for spheroidal graphite cast iron, by using a gaseous fuel containing no sulfur such as LNG, the vulcanization of the combustion gas into the molten metal is not performed, so desulfurization treatment is not required. It also has features.

Further, in comparison with the electric induction furnace, regarding the melting efficiency, in the case of the electric induction furnace, although the melting efficiency by electricity which is the secondary energy is high, when considering from the primary energy of electric production, as a feature,
Since the power generation method is mainly thermal power generation, the melting efficiency of the electric induction furnace is low in total view. Therefore, the shaft furnace using a gaseous fuel such as LNG is a melting furnace for cast iron. As an advantage Moreover, the remarkable spread of the electric induction furnace due to the increase in the amount of cheap iron scrap produced in the past high growth period has slowed down for several reasons. That is, the increase in melting energy cost due to the increase in electricity price,
This is because various negative effects such as concern about destabilization of cast iron materials are beginning to appear. In particular, if iron scrap generated from each processing plant is separated by various kinds of treatment such as rust prevention treatment found on automobile steel sheets and addition of alloys for thinning, and it is not used as a casting iron source, for example, , Smoke pollution caused by combustion of rust preventive surface treatment agent, possibility of short circuit accident of electric furnace equipment due to its metal oxide, and impurity element in iron scrap contained for improving material There is a possibility that problems such as destabilization of the cast iron material due to mixing into the molten metal may occur.

Under these circumstances, the present invention is characterized by excellent melting efficiency, easiness of control, environmental aspects, etc. in comparison with the conventional melting furnace under the current situation of rapid change.
The melting furnace, which is the shaft furnace described above, is receiving attention.

[0006] However, in comparison with the conventional cupola using coke, in such a shaft furnace, the loss of strut, which exists as an inevitable structure, is a high temperature combustion gas generated by the burner. It secures the combustion chamber into which the air is blown, and supports the ceramic balls and the molten raw materials that are directly above it as the heat storage material, while also serving to transfer the combustion heat from the combustion chamber upward. In order to prevent melting loss, the rostrut is made of a hollow steel pipe and is cooled by flowing cooling water inside the pipe. However, the heat of combustion removes the combustion heat from the water cooling of the rostrul. Inevitably, this is one of the causes of the decrease in thermal efficiency.

In the conventional water-cooling type rostrut structure, about 80% of the total amount of cooling water is used as cooling water for preventing melting loss of the rostrut, and waste heat thereof. Is not reused, therefore, the amount of heat taken away by the endothermic end of the water-cooled roster is discarded, and the amount of heat and molten metal temperature, etc.
It has a number of implications.

[0008]

The present invention has been made in view of such circumstances, and its object is to provide thermal energy in a shaft furnace as described above without using a water-cooled steel pipe loss It is intended to significantly improve the thermal efficiency by adopting a new loss-tolerant structure that effectively reduces loss, and also simplifies the equipment by not using cooling water and reduces man-hours for maintenance. Is to try.

[0009]

In order to solve the above problems, the present invention charges a molten material from above the inside of a furnace onto a rostrut arranged in the furnace, and at the same time, raises the high temperature generated by a burner mechanism. By supplying the combustion gas of the inside of the furnace from the lower side of the grate, and guiding it to the upper side of the furnace through the gist,
In a shaft furnace configured to heat and melt the melting material with such combustion gas, the gist of the shaft furnace is characterized in that the rostrut is made of a hollow pipe-shaped heat-resistant ceramics body. is there.

As described above, in the shaft furnace according to the present invention, instead of the conventional water-cooled gist made of steel pipe, a gist made of a heat-resistant ceramic body having a hollow pipe shape is used. The problem of heat energy loss that was lost to the cooling water of the steel pipe loss
Since it can be advantageously eliminated, it is possible to dramatically improve the efficiency of the thermal energy provided by the high-temperature combustion gas generated by the burner mechanism. By not using the cooling water, simplification of the device in the shaft furnace is realized, and based on this, the man-hours for maintenance of the device can be effectively reduced.

In the shaft furnace according to the present invention as described above, the air in the hollow portion of the ceramic body forming the rostrut is preferably forcedly or by natural convection to be exchanged with the outside air. The ceramic body may be cooled to some extent, in particular when the air is forced to be exchanged, on the basis of which the thermal energy in the furnace is absorbed and Although it causes a loss, the heat loss due to such forced convection of air is incomparably lower than the heat energy loss that was lost to the cooling water of the conventional steel pipe loss tower, and therefore The improvement of the thermal efficiency in the invention can be sufficiently realized.

In summary, the present invention is directed to a shaft furnace for melting a molten material such as pig iron by utilizing the thermal energy of high temperature combustion gas generated by a burner mechanism,
By changing the steel tube structure from a steel tube structure to a ceramics structure to dramatically improve the thermal efficiency, the shaft supporting such melting materials is designed to have various performances in terms of actual operation. However, as a result of earnest research by the present inventors, the mechanical strength, heat resistance, and corrosion resistance of the hollow pipe-shaped ceramic body have been found to be compatible with the loss in such a shaft furnace. The invention was completed.

Incidentally, the static load acting on the upper part of the grate in the shaft furnace is calculated from the total weight of the heat storage bed consisting of the melting material such as pig iron and the commonly used ceramic spherical heat storage body. A shaft furnace with a diameter of 1.0 m, which is commonly used, has a total heat storage bed weight of 300 kg and a total melting material weight of 6 tons
Therefore, the total weight acting on the rustle is 6.3.
It becomes t. Therefore, the maximum bending stress in the case where the rostrul receives a distributed load and is regarded as a support beam with both ends having a length of 1.2 m is 1.6 kg / mm ² as a result of calculation from the bending moment and the cross-sectional modulus of the rostrul. Therefore, the bending strength of ceramic materials is generally 20 k.
Since it is g / mm ² or more, it is possible to sufficiently withstand such a bending stress without causing any problem.

Regarding the impact load, in consideration of the material charging, that is, the situation in which molten material such as pig iron, return No. 2 and iron scrap is charged into the furnace from the charging port at the upper part of the furnace, it falls freely. It can be imagined that the impact of these materials on the Rostrur is quite large, and in fact, in calculation, for example, when an iron block with a weight of 5 kg hits the Rostrur 6 m below, the impact force that the Rostrut receives is , About 104 kg / mm
Although the a ^2, a large impact force against such grate, in order exceeds the limits of the elastic range, ceramic grate results may be broken by the impact. Therefore, in the present invention, such as a ceramic spherical heat storage material that has been adopted in the conventional shaft furnace,
A heat storage bed composed of a spherical or lump-shaped heat storage body is provided on the rostrut, and is configured so that the melting material is charged on the heat storage bed, thereby dispersing the charging impact force of the melting material, As a result, the impact load on the ceramic grate is alleviated and the gable of the grate is effectively prevented.

In the present invention, as another means for improving the impact strength of the ceramic rostrtor, it is preferable to arrange the hollow pipe-shaped ceramic bodies constituting the rostrut in the furnace in a plurality of stages. Was adopted by the
In that case, the upper ceramics body can be made to function as a heat storage body. Further, in the present invention, air is forced to flow in the hollow portion of the lowermost one of the plurality of stages of the ceramic body forming such a loss, while the other stages of the ceramics are forced to flow. In the hollow portion of the body, a structure in which air is exchanged by natural convection is advantageously adopted.

Regarding the heat resistance, which is a characteristic of the ceramic material, it has been recognized that the temperature distribution of the Rostrur is analyzed by the finite element method and that the heat resistance is sufficient in the operating temperature range. The analysis method is as follows. First, the heat transfer coefficient or heat flow rate on the surface and inside of the grate pipe is calculated at each temperature, and then based on the calculated heat transfer coefficient and heat flow rate, the general-purpose finite element method program ANSYS The temperature distribution of the pipe was analyzed by. Then, in the calculation, assuming that the flame at 1600 ° C. hits the rostrut at a wind speed of 7.1 m / s, the calculation result shows that in the case of a rostrut made of an alumina pipe,
The temperature of the outer wall surface of the pipe when forced air cooling at 0 m / s was 1017 ° C, which was confirmed to be within the operating temperature range of alumina, and it was revealed that the pipe has sufficient heat resistance when used as a rustle. It became.

Further, with respect to corrosion resistance, ceramic materials are also excellent. For example, in a comparative test of corrosion performance with respect to molten cast iron containing slag, alumina-based ceramics, silicon carbide-based ceramics, etc. exhibit excellent corrosion resistance, and thus in a shaft furnace. It has become clear that it can be used sufficiently as a loss material.

By the way, in the conventional shaft furnace in which the steel pipe rostrut is water-cooled, the heat loss due to the water-cooled rostrur at a water temperature difference of 5 ° C. at the entrance and exit of the rostrut and a water amount of 60 m ³ / h is about 300,000 kcal / h. On the other hand, the heat loss when the inside of the ceramic rostrut according to the present invention is forcibly air-cooled at a wind speed of 10 m / s is about 3
It becomes 10,000 kcal / h, and the heat loss can be reduced to 1/10 as compared with the case of the conventional water cooling. Therefore, the heat quantity of 270,000 kcal / h corresponding to 90% of the conventional heat loss is Therefore, it greatly contributes to the improvement of the melting heat efficiency, and the melting heat efficiency is greatly improved.

In order to further improve the thermal efficiency of the shaft furnace according to the present invention, air which is forcedly or naturally convected in the hollow portion of the ceramic body constituting the roster is introduced into the burner mechanism in order to cool it. However, it is desirable to use it as combustion air in the burner mechanism, whereby the problem of heat loss due to the air cooling described above can be solved.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be more specifically clarified below based on typical examples of the present invention shown in the drawings.

First, FIG. 1 shows one specific example of the shaft furnace according to the present invention. Therein, 10 is a shaft furnace, and a furnace wall 14 whose inner surface is covered with a refractory material forms a furnace chamber 14 extending in a substantially vertical direction inside. Although not shown in the figure, the furnace wall 1
No. 2 is extended further upward to form a flue, while from the upper end opening, a scraping device such as scrap iron, pig iron, and return material is introduced into the furnace by a charging device such as a charging bucket. It can be thrown in.

In the furnace chamber 14 of the shaft furnace 10,
At a predetermined height from the furnace bottom, the furnace chamber 14 is partitioned into upper and lower parts, and a ceramics-made rostrut 16 as described in detail later is arranged. A large number of ceramic spherical heat storage bodies 18 similar to the conventional ones are placed at a predetermined height, whereby a heat storage bed 20 is formed. Then, from the upper end opening of the furnace wall 12,
On the heat storage bed 20, a melting material 22 such as scrap, pig iron, return material, etc. is charged and supported in the furnace.

By the way, in the shaft furnace 10, the heat storage bed 20 and the roast 16 supporting the melting material 22 are hollow pipe-shaped heat-resistant ceramic bodies 24.
Of a plurality of are arranged in parallel with each other at a predetermined interval, and a ceramic material that gives such a hollow pipe-shaped ceramic body has heat resistance (fire resistance). It will be appropriately selected from among the known materials that have, generally, alumina-based ceramic materials, silicon carbide-based ceramic materials, zirconia-based ceramic materials, mullite-based ceramic materials,
A boron carbide material or the like is used, and among them, an alumina-based ceramic material and a silicon carbide-based ceramic material are preferably used. A desired hollow pipe-shaped ceramic body 24 is formed by molding such a ceramic material into a predetermined hollow pipe shape by a conventional method and firing it.
In addition, as the hollow pipe shape of the ceramic body 24, in addition to the round shape having a circular cross section, the rectangular shape having a rectangular cross section,
It will be adopted appropriately.

Further, the inside of the furnace chamber 14 located below the roaster 16 is used as a combustion chamber, in which the high temperature combustion gas generated in an appropriate number of burner devices 26 as a burner mechanism is burned. The gas is blown into the furnace through the ejection holes 28, and is guided upward from the lower portion of the furnace chamber 14 through the roster 16. It should be noted that each of the burner devices 26 is supplied with combustion air by an air supply pipe 32 branched from an air supply duct 30 and burns a predetermined fluid fuel such as LNG or heavy oil to generate a high temperature combustion gas. Although not shown here, the inside of the hollow portion of each ceramic body 24 constituting the rostrut 16 is generated as at least a part of the combustion air supplied to each such burner device 26. The air that is circulated is used. Then, the high temperature combustion gas thus generated is caused to pass therethrough, whereby the heat storage bed 20 and the melting material 22 are heated, whereby the melting material 22 is heated and melted. , And the heat storage bed 2
While being guided downward along the surface of the spherical heat storage body 18 constituting 0, and further heated by the heat storage body 18,
As a molten metal, it is made to fall below the rostrtor 16.

At the bottom of the furnace chamber 14, there is a molten metal reservoir 34
The molten metal that has been melted and dropped is stored in the molten metal reservoir 34, and is then taken out of the shaft furnace 10 from the tap 36 through the gutter 38. .

Therefore, when performing the melting operation using the shaft furnace 10 having such a structure, first, the heat storage body 18 is spread over the rostrut 16 to form the heat storage bed 20, and then the burner device 26 is used to form the furnace. Of the melted material 22 from the upper opening of the furnace.
Is charged into the furnace chamber 14, and heating and melting of the melting material 22 is started. As a result, the melting material 22 is heated and melted sequentially from the lower part thereof, and further heated by the heat storage bed 20 to be a molten metal, and the generated molten metal is dropped into the molten metal reservoir 34. Then, the water is appropriately taken out from the tap 36 through the gutter 38. In addition, during this operation, the melting material 22 becomes a molten metal and is dropped at an appropriate time interval by an amount corresponding to the amount of dropping downward.
It is possible to carry out a continuous dissolution operation by additionally charging the inside.

By the way, in such a melting operation, the rostrut 16 is constituted by a hollow pipe-shaped heat-resistant ceramic body 24, and air for cooling is naturally convected in the hollow portion of the ceramic body 24. Since it is not forced to be water-cooled like the conventional steel pipe rostrtor, it is simply forced to pass through, and is absorbed by the high temperature combustion gas through the rostrut 16 (ceramic body 24). Since the heat loss is avoided, the heat energy of the high temperature combustion gas blown into the furnace can be stored in the heat storage bed 20 and can be effectively used for melting the melting material 22. The thermal efficiency can be dramatically improved.

In addition, in this example, the air heated by flowing through the hollow portion of the ceramic body 24 constituting the roster 16 is used as the combustion air for the burner device 26. ,
The thermal energy taken out of the furnace by the air cooling of the rostrut 16 is also effectively reused, whereby the thermal efficiency can be further improved.

In the shaft furnace 10 illustrated in FIG. 1, the rostrut 16 is composed of a single stage of a cylindrical ceramic body 24. Overlay in various forms,
It is also possible to configure in two stages or a plurality of stages more than two stages, whereby the impact strength of the entire roster 16 can be effectively increased.

FIG. 2 shows an example of the rostrut 16 composed of such a plurality of stages of ceramic bodies. There, the rostrut 16 is a rectangular hollow pipe-shaped ceramic body 40a, 40b, 40 having a rectangular cross section.
It has a three-stage structure of c, and is formed by arranging two ceramic bodies 40a in parallel on both sides of one ceramic body 40a passing through the center of the furnace. A large number of parallel ceramic bodies 40b and 40c are arranged at a predetermined interval in a direction orthogonal to the ceramic body 40a to form middle and upper ceramic bodies, and the ceramic bodies are inserted. Dissolving material 22
The heat storage body 18 is supported so that they do not drop downward. And the bottom ceramics body 4
Air is forced to flow in the hollow portion of 0a for forced air cooling, while the air in the hollow portions of the middle and upper ceramic bodies 40b, 40c is subjected to natural convection. It is a natural air cooling system that replaces the outside air. Although not shown, the air that has passed through the hollow portions of the ceramic bodies 40a, 40b, 40c is supplied to the burner device 26 as combustion air, as in the example of FIG.

Such ceramic bodies 40a, 40
In the multi-stage rostrut 16 of b and 40c, the impact strength can be much higher than that of the one-stage structure, and of course the middle-stage ceramic body 40b,
Furthermore, it is possible to cause the upper ceramics body 40c to function as a heat storage body, and in that case,
It is effective to exchange air in the hollow portions of the ceramic bodies 40b and 40c by a natural convection method.

Further, by adopting such a multi-stage rostrut 16 such as the three-stage structure shown in FIG. 2,
Since it is possible to individually determine the replacement cycle of the ceramic body of each stage, partial replacement of the rostrut, in other words, by replacing the upper, middle and lower ceramic bodies individually, one-stage structure It is possible to prolong the service life of the rostrul 16.
For example, the replacement cycle of the lowermost ceramic body 40a:
12 months, middle ceramic body 40b replacement cycle:
6 months, upper ceramic body 40c replacement cycle: 3
It can be a month, and the one-stage structure has a replacement cycle of 3 months, in other words, a life of 3 months.
By adopting the three-stage structure as described above, the life can be extended by about 1.8 times.

In the shaft furnace 10 illustrated in FIG. 1, the spherical ceramic heat storage element 18 is provided on the rostrut 16.
The heat storage bed 20 is formed, which absorbs thermal energy from the high-temperature combustion gas that is guided upward in the furnace chamber 14 from below, and can effectively provide the molten material 22 with the thermal energy. In addition to the above, the impact load of the melted material 22 to be charged is dispersed to prevent the breakage of the roster 16 (ceramic body 24). However, such a heat storage bed 20 is not always necessary. Absent. If the impact load at the time of charging the melting material 22 is avoided and the thermal energy of the combustion gas can be effectively applied to the melting material 22, the melting material 22 can be directly loaded on the rostrut 16. It is also possible to charge and carry out the melting operation.

The shaft furnace according to the present invention can be preferably used for producing cast iron molten metal as illustrated, but the invention is not limited thereto, and a melting furnace for melting and solidifying incinerated ash or the like is used. Can also be adopted as.

As described above, the present invention can be carried out in a mode in which various changes, modifications, improvements, etc. are added based on the knowledge of those skilled in the art without departing from the spirit of the invention. It should be understood that all such embodiments are within the scope of the present invention.

[0036]

EXAMPLES Examples of the present invention will be shown below to clarify the characteristics of the present invention more specifically.

First, in order to examine the heat resistance of the hollow pipe-shaped ceramic body 24; 40a to 40c which gives the loss rostrum 16, its temperature distribution was analyzed by the finite element method. As the ceramic body, a round hollow alumina pipe having an outer diameter of 76 mm, an axial length of 1 m, and a wall thickness of 7 mm was used.
While the flame at ℃ hits 7.1 m / s while the inside of the pipe is forcibly cooled by the circulating air of 10 m / s, the calculation result is shown in FIG. 3. The maximum temperature was 1017 ° C., which was confirmed to be within the alumina working temperature range.

On the other hand, the heat distribution of the steel pipe loss in the conventional shaft furnace was analyzed by the finite element method, and the result is shown in FIG. In addition, there, 160
A 0 ° C gas flame hits the outside of the pipe and 0.8
It is calculated that the water is circulated at a flow rate of m / s and the water is forcedly cooled. As a result, it was analyzed that the outer surface of the steel pipe of the steel pipe rostrul used in the conventional gas shaft furnace was 63 ° C.

Further, in order to investigate the impact resistance of the ceramic rostrut according to the present invention, 5 kg of a cold material (melting material) is dropped from 6 m above the charging port of the shaft furnace, while a hollow pipe constituting the ceramic rostrut. The impact stress was measured from the value of the strain gauge attached to the cylindrical ceramic body. The spherical ceramic heat storage body (18)
It was confirmed that when the heat storage bed (20) made of (4) was formed, such damage due to impact stress was not caused.

Furthermore, in order to investigate the corrosion resistance, the length of the ceramic material is 55 mm and the length is 7.5 m.
The refractory to which the m × 7.5 mm square ceramic test piece was attached was placed in a cylindrical crucible furnace having a diameter of 0.5 m and a length of 1.0 m, and the heat resistance of 15
It was processed by rotating at 120 rph together with a cast iron molten metal at 00 ° C. Then, after naturally cooling the crucible furnace by air, the corrosion resistance to the hot metal was observed, but no remarkable change was observed in the test pieces made of the alumina ceramic material or the silicon carbide ceramic material.

Based on the above results, the following actual operation was carried out in an actual shaft furnace as shown in FIG. First, for the Rostrul 16, a rectangular hollow pipe-shaped ceramic body (40a) manufactured by a normal pouring method using a material containing alumina as a main component is used because the production cost is relatively low and it is easily available. Using. The specifications of the material are as follows: density: 3.8 g / cm ³ , thermal conductivity: 25 W / (m · K), and the dimensions of the ceramic body (40 a) are: external surface dimension: 80 mm square, wall thickness: 8
Further, axial ribs were provided at three locations on the outer periphery in the horizontal direction and the downward direction in order to control the damage due to the drop impact when the material was charged and the drop due to the wear of the ceramic heat storage body 18. In addition, the shaft furnace 10 in which this roster is set has an inner diameter of 700 mm,
The pitch of the ceramic body (40a) of the loss 16 is
The dimensions were the same as those of the conventional steel pipe.

When burning the burner, first, the air-fuel ratio is 1.05 for both preheating and melting, and preheating is 20
The operation was carried out at 0,000 kcal for 60 minutes to sufficiently dry the inside of the furnace and raise the temperature. Air for cooling the grate is supplied at room temperature, and 10 m / s per ceramic body forming the grate.
Supplied at wind speed. After preheating, the heat storage bed 2
200 kg of a spherical ceramic heat storage material 18 was charged so that the height 0 was 250 mm. Regarding the charging of the heat storage body 18, it is better to charge the roastle 16 before preheating, but the strength is confirmed by charging at the time when the temperature rises. This was done for the purpose. The temperature of the surface of the rostrul at the time of such charging was 850 ° C., but no problem occurred with respect to the drop impact of the ceramic heat storage body 18. After that, the combustion chamber and the heat storage bed 2
It was confirmed that the temperature of the ceramic heat storage body 18 constituting No. 0 was sufficiently raised, and the introduction of the melting material 22 was started. In addition, pig iron, No. 2, steel scrap, and dolomite and silica were used as the melting material 22 and the forming material at the compounding ratios shown in the table below.

[0043]

[Table 1]

Further, the burner device 2 at the time of such melting
The combustion amount of No. 6 was 1.8 million kcal, the air-fuel ratio was 1.08, and the combustion air was supplied at room temperature. During dissolution
Oxygen enrichment was performed at 1%, and it was also observed to what extent it contributes to the wear of the Rostrul 16. Immediately before the material was charged, the surface of the Rostrul 16 reached 850 ° C., the temperature gradient of the cooling air was 60 ° C., and the flow rate was 1400 m ³ / h. Further, it was confirmed that the thermal energy carried out by the cooling air was about 1/10 of the energy carried out by the cooling water in the case of water cooling of the conventional steel pipe rostrul: about 300,000 kcal.

The above melting operation was repeated 5 times to obtain a total of about 40 t of molten metal. The average amount of tapping water was 4.2 t per hour, and the average tapping temperature was 1380 ° C.
After the completion of the melting operation, the ceramic lossr 16 (ceramic body 40a) was taken out from the shaft furnace 10 and observed. As a result, there was almost no damage due to the impact of the material, and it was sound. In addition, it was confirmed that melting damage due to slag was partially observed, and that a life similar to that of a conventional steel pipe loss can be secured.

From the results of these examples, it was confirmed that the rectangular hollow pipe-shaped ceramic body (40a) can be used as the rostrut 16 in the shaft furnace 10 in terms of heat resistance, impact resistance and corrosion resistance. Further, such a ceramic rostrut 16 (40a) does not require water cooling, and as a result of thermal settlement, heat loss can be reduced by as much as 90% as compared with the conventional water-cooled steel pipe rostrul, and the shaft furnace constant. It was found that the heat of solution heat at all times could be significantly improved. In addition, since cooling water for the grate is not required, it is possible to reduce the operating cost of the cooling tower.

[0047]

As is apparent from the above description, in the shaft furnace according to the present invention, since the rostrut is made of a hollow pipe-shaped heat-resistant ceramic body, the conventional steel pipe rostrut Compared with the above, it is not necessary to perform water cooling, so that it is possible to eliminate the heat energy loss taken by the cooling water and dramatically improve the thermal efficiency of combustion energy. Therefore, it is possible to obtain the advantage that the device can be simplified by not using, and that the number of man-hours for maintenance and management of such a device can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional explanatory view showing an example of a furnace body structure of a shaft furnace according to the present invention.

2A and 2B are views showing another example of the rostrur structure according to the present invention, in which FIG. 2A is an explanatory view of the arrangement of the rostrut in a vertical cross section of the furnace body, and FIG. 2B is a horizontal view of the furnace body. It is explanatory drawing which shows the arrangement form of the rostrtor in a cross section.

FIG. 3 is a diagram showing a heat distribution analysis result of a ceramic rostrut obtained in an example.

FIG. 4 is a diagram showing a heat distribution analysis result of a steel pipe rostrul obtained in an example.

FIG. 5 is a diagram showing an in-furnace heat pattern of a crucible furnace in a corrosion resistance test for molten cast iron carried out in Examples.

[Explanation of symbols]

 10 Shaft Furnace 12 Furnace Wall 14 Furnace Chamber 16 Rostru 18 Ceramic Spherical Heat Storage Body 20 Heat Storage Bed 22 Melting Material 24, 40a, 40b, 40c Ceramics Body 26 Burner Device 28 Gas Injection Hole 30 Air Supply Duct 32 Air Supply Pipe 34 Molten Metal Sump Part 36 Dewgate 38 Gutter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Susumu Yamada 19-18 Sakurada-cho, Atsuta-ku, Nagoya-shi, Aichi Toho Gas Co., Ltd. (72) Inventor Mitsuyasu Nakajima 19-sakurada-cho, Atsuta-ku, Nagoya-shi, Aichi No. 18 In Toho Gas Co., Ltd. (72) Inventor Isamu Kondo 9-14 Sotoi-cho, Atsuta-ku, Nagoya-shi, Aichi Prefecture

Claims (6)

[Claims] 1. A molten material is loaded into the furnace from above in the furnace while the high-temperature combustion gas generated by a burner mechanism is supplied into the furnace from below in the furnace. In a shaft furnace in which the molten material is heated and melted by the combustion gas by being guided to the upper side of the furnace through the rostrut, the rostrut is formed of a hollow pipe-shaped heat-resistant ceramic body. Shaft furnace to do. 2. The shaft furnace according to claim 1, wherein the air inside the hollow portion of the ceramic body is configured to be forcedly or by natural convection to be exchanged with the outside air. 3. The shaft furnace according to claim 1 or 2, wherein a heat storage bed constituted by a spherical or lump-shaped heat storage body is provided on the rostr, and the melting material is charged on the heat storage bed. . 4. The shaft furnace according to any one of claims 1 to 3, wherein the ceramic bodies are arranged in a plurality of stages in the furnace to form the roster. 5. The air is forced to flow in the hollow part of the lowermost one of the ceramic bodies of the plurality of stages constituting the rostrut, while natural convection is carried out in the hollow parts of the ceramic bodies of the other stages. 5. The shaft furnace according to claim 4, wherein the air is exchanged at. 6. The air that has passed through the hollow portion of the ceramic body that constitutes the rostrut is guided to the burner mechanism,
The shaft furnace according to any one of claims 1 to 5, which is used as combustion air in the burner mechanism.