JP3769256B2 - RH degassing tank bottom, RH degassing tank, and refractory block manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a refractory building structure for a lower tank of an RH degassing facility used for steel refining.
[0002]
[Prior art]
The main part of the RH degassing facility consists of a vertically long tank and two dip tubes provided at the lower end thereof. When the molten steel is sucked up by evacuating the inside of the tank and argon gas is blown into the molten steel from the inner surface of one of the dip tubes, the molten steel rises as the gas floats and flows down from the other dip tube.
[0003]
The tank body can be divided into several parts, and the lowermost end to which the dip tube is connected is called the lower tank. At the bottom of the lower tank (also called a floor), there are two holes that penetrate the dip tube.
[0004]
The refractory used for the lining of the lower tank is not only highly stable under vacuum, but also wear resistance that resists flaking by flowing molten steel, corrosion resistance against slag entering from the ladle, and oxygen to the molten steel Corrosion resistance to high-temperature iron oxide generated when sprayed or blown is required.
[0005]
Conventionally, magnesia-chromic bricks have been used for the RH lower tank. However, in recent years, an RH lower tank in which an amorphous refractory kneaded with water is integrally poured to construct a refractory lining is also used. Since irregular refractories can be added and constructed, there is an advantage that there is little waste of refractories. In addition, the amorphous refractory is advantageous in that it does not have processes such as molding and firing at the time of manufacture, so that the manufacturing cost and price are low and the delivery time is short.
[0006]
In the case of using an amorphous refractory in the RH lower tank, a method of using a precast block and brick that has been cast and dried in advance is known (see Patent Document 1).
[0007]
On the other hand, when building a refractory lining of the RH lower tank using bricks or precast blocks, the bricks or blocks may be deformed by thermal expansion, leading to defects or levitation. In order to suppress this, various furnace constructions have been devised and proposed. For example, an example is known in which a jack arch structure made of a lower wide taper brick is incorporated in a portion sandwiched between both reflux pipe tuyere (see Patent Document 2).
[0008]
In addition, a structure has been proposed in which a joint is installed between the flow holes when an irregular refractory is poured into the refractory to suppress deterioration of the refractory (see Patent Document 3).
[0009]
In addition, a structure has been proposed in which the floating pipe tuyere bricks are spread upward to suppress floating by Nakanoshima lining bricks (see Patent Document 4).
[0010]
[Patent Document 1]
Japanese Patent Laid-Open No. 07-233410 [Patent Document 2]
Japanese Utility Model Publication No. 03-009249 [Patent Document 3]
Japanese Patent Laid-Open No. 11-029816 [Patent Document 4]
Japanese Patent Laid-Open No. 2000-160231
[Problems to be solved by the invention]
When an amorphous refractory is used, a drying step for removing the water used for kneading by evaporation is essential. The thickness of the refractory lining the RH lower tank is often more than 400 mm. In addition, since the entire tank is a vacuum vessel, there is no hole in the iron skin that can release steam. Drying is not easy. Using precast blocks can solve this problem. However, as described in Patent Document 1, even if a precast block or a brick is combined in a very simple manner, it is not possible to suppress defects and flying.
[0012]
The structure described in Patent Document 2 has an effect of suppressing the floating of the portion sandwiched between the reflux tube tuyere and the extended portion thereof, but cannot suppress the raising of the tuyere brick.
[0013]
The structure described in Patent Document 3 is effective for alleviating the thermal stress generated in the interior of an indeterminate refractory construction body that is integrally cast and usually has no joints. There are many joints and it is not a useful technology.
[0014]
Moreover, although the structure described in Patent Document 4 is an effective method for suppressing the loss of bricks constituting the reflux pipe tuyere, the structure is complicated and it is not easy to construct a furnace.
[0015]
The present invention provides a relatively simple and stable refractory building structure at the bottom of an RH degassing tank.
[0016]
[Means for Solving the Problems]
In order to solve these problems, the present invention was obtained by accumulating ingenuity.
(1) A refractory block for Nakanoshima sandwiched between two recirculation pipes, a refractory block for each of the recirculation pipe tuyere, and a refractory block for a laying part other than Nakanoshima and the recirculation pipe tuyere And an refractory building structure RH degassing tank bottom having an irregular refractory filled in the gap and / or surroundings of the refractory block, the refractory blocks constituting the Nakanoshima are both circularly flowed in a horizontal section. It is an inverted jack arch structure with a trapezoidal shape that spreads downward in a vertical cross section perpendicular to the line connecting the center of the pipe, and constitutes a part of a refractory block for a reflux pipe tuyere RH degassing tank bottom characterized by having a refractory building structure.
(2) A refractory block for Nakanoshima where the surface of the refractory block is the center of the tank bottom, and a refractory block for a recirculation pipe tuyere and a refractory for a part other than Nakanoshima and the recirculation pipe tuyere The RH degassing tank bottom according to (1), which is lower by 30 mm or more than the object block.
(3) The refractory block for Nakanoshima, the refractory block for each recirculation pipe tuyere, and the refractory block for the laying part other than Nakanoshima and the recirculation pipe tuyere , The bottom of the RH degassing tank according to (1) or (2), which is a molded block.
(4) An RH degassing tank having the RH degassing tank bottom according to any one of (1) to (3).
(5) The refractory block for Nakanoshima according to any one of (1) to (3), the refractory block for each reflux pipe tuyere, and the laying of parts other than Nakanoshima and the reflux pipe tuyere It is a method of manufacturing a refractory block for a part, which corresponds to all or part of the bottom of the RH degassing tank to be constructed, and partitions the inside of the mold larger than the individual blocks with a plate, and into the partitioned part A method for producing a refractory block, comprising pouring and curing an amorphous refractory to produce two or more blocks from one mold.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The features of the furnace construction of the present invention will be described with reference to FIG.
[0018]
Referring to the plan view of the lower sill (bottom) of the RH degassing tank in FIG. 1, the refractory block constituting the reflux pipe tuyere 3 surrounding the reflux pipe 1 is divided substantially evenly in the circumferential direction. In FIG. 1, it is divided into six. A refractory block called Nakanoshima 2 sandwiched between two reflux tubes is also one of the refractory blocks constituting the reflux tube tuyere. Referring to the RH lower tank cross-sectional view (FIG. 1 (b)) showing the AA cross-sectional view of FIG. 1 (a), the refractory block constituting Nakanoshima 2 has a trapezoidal cross section, and both sides thereof The refractory 6 is covered from the left and right, that is, an inverted jack arch structure. That is, the refractory block of Nakanoshima 2 forms an inverted jack arch structure between the two reflux pipes and constitutes part of the reflux pipe tuyere as described in the invention according to (1).
[0019]
Thermal stress is concentrated on Nakanoshima 2, and if no measures are taken, the chipping and levitation occur. However, the reverse jack arch structure can effectively suppress the chipping and levitation, and the circulation. By also serving as a part of the tuyere, it is possible to suppress the loss and levitation of the circulating tuyere.
[0020]
When building a refractory lining using blocks, the gaps and / or surroundings of the blocks are filled with an irregular refractory in order to prevent leakage. Although it may be filled with mortar or a casting material, it is not always easy to dry the water used for kneading. Therefore, it is particularly preferable to construct a dry amorphous refractory such as a dry ramming material because there is no need for drying. Immediately after the start of operation, unsintered dry filler may be washed away and lost, so the part close to the operation surface should be moistened with some water, water glass, or other liquid binder. It is good to start from.
[0021]
Further, FIG. 1C is a cross-sectional view taken along the line BB in FIG. The refractory block constituting the Nakanoshima 2 has a vertical cross-sectional structure in the BB cross section.
[0022]
Further, according to the cross-sectional view of FIG. 1 (b), Nakanoshima 2 is lower than the surroundings, which corresponds to the invention according to (2). By making it low in this way, the stress due to thermal expansion generated on the surface of the refractory can be changed downward, and the rise and loss of the refractory block constituting Nakanoshima and the recirculation tuyere can be effectively suppressed. The difference in height from the surroundings is 30 mm or more. If it is less than 30 mm, the effect of suppressing refractory block levitation and chipping is poor. However, if this height difference is made too large, the thickness of the Nakanoshima 2 is insufficient and the life is shortened, so that it is preferably within 150 mm.
[0023]
The refractory block used in the present invention may be a precast block obtained by casting and drying an amorphous refractory in advance. The amorphous refractory has many advantages such as relatively inexpensive and quick delivery, can be added, and can be easily dried by using a precast block. This is the purpose of the invention according to (3) above. is there. However, refractory blocks other than precast blocks, such as unfired or fired bricks, can also be used.
[0024]
When producing a precast block, it may be cast separately into a mold. However, it costs more because many types of formwork are required. And when you change the shape of a block, you have to recreate many types. Therefore, as described in the invention according to the above (5), a mold form larger than each block corresponding to all or a part of the tank bottom is prepared, and the inside thereof is partitioned by a plate, and the partition portion is indefinite. Refractory logistics installation, curing and molding of two or more blocks. In this way, the number or types of molds can be greatly reduced. When a large mold corresponding to the entire tank bottom is used, only one is required per tank. In addition, the furnace construction and block shape can be changed as desired by changing the partitioning method. If the thickness of the plate is adjusted, the thickness of the gap 5 (joint) can be freely set. The plate may be flat or curved. In order to adjust the shape of the block, a spacer can be installed inside the mold.
[0026]
The material of the refractory is preferably alumina-spinel, alumina-magnesia, or basic if it is an irregular refractory for the RH degassing tank. During kneading and molding, refractory coarse particles such as alumina, mullite, and magnesia and various refractory lumps may be mixed. Organic fibers and metal fibers may be added. As usual, the kneading and pouring methods are carried out by adding a kneading liquid such as water, kneading with a mixer, and pouring into a mold. After pouring, a good quality construction body can be obtained by shaking with a vibrator. Alternatively, the block may be prepared by dry processing such as ramming or stamping or semi-dry construction with a slight addition of moisture. The refractory may be brick as described above.
[0027]
2A to 2C are examples in which the method of dividing the refractory block is changed. In this case as well, in the case of FIG. 1, Nakanoshima sandwiched between the reflux pipes has a reverse jack arch structure, and Nakanoshima is a part of the reflux pipe tuyere, and the center of the tank bottom is lower than the surroundings. The features of the present invention such as
[0028]
【Example】
The bottom of the 300 tRH degassing tank was lined with the structure of FIG.
[0029]
Prepare a formwork (diameter of about 3 m) corresponding to the size of the entire floor, place a spacer on the part that will become the reflux tube, and make it a gap (thick line in FIG. 1 (reference numeral “5” is shown)) A plate with a thickness of 2 mm was installed in a portion (a thin line portion in FIG. 1) to be joined with a mortar without providing a gap. For the material, the lower surface at the time of construction was the upper surface at the time of material pouring, and a spacer was placed in a portion corresponding to the dent at the center of the tank bottom at the time of construction. The thickness of the block was about 400 mm, and the center of the tank bottom was 75 mm lower than the surroundings. The block of Nakanoshima was trapezoidal when viewed in the cross section of FIG. 1 (b), the height was 325 mm, the lower base was 800 mm, and the upper base was 600 mm.
[0030]
The material was an alumina-spinel casting material containing about 20% by weight of spinel. The material was kneaded by adding water, poured into a mold partitioned by a plate, and vibrated with a rod-like vibrator.
[0031]
After curing, the mold was removed and the removed block was dried in a dryer.
[0032]
The dried block was built in the lower tank of the RH degassing tank. First, a small amount of mortar kneaded with water was poured, and the block was put in place. Mortar was applied to the part where no gap was formed, and the blocks were joined together. The gap was filled with air rammer with a magnesia-spinel dry ramming material containing about 20% by weight of spinel. The working surface side 50 mm was filled with the same ramming material with a small amount of water glass added to complete the construction. After that, magnesia-chromic bricks were built on the side walls, and the construction of the refractory lining the lower tank was completed.
[0033]
After the tank was dried at 400 ° C., it was fastened to the upper tank and used after preheating. After use about 500 times, it was removed from the upper tank and the situation at the bottom of the tank was observed, and no block defect was found.
[0034]
【The invention's effect】
As described above, according to the present invention, it is possible to obtain a refractory lining that is easy to dry and has a relatively simple and stable structure. It can be used stably. As a result, the refractory cost can be reduced, the degassing process can be stabilized, and as a result, the steel manufacturing cost can be reduced.
[0035]
An amorphous refractory can be used as a precast block that can be easily dried, and a method with a relatively simple structure that does not cause block loss or levitation and a method for producing a precast block used therefor can be provided.
[Brief description of the drawings]
FIG. 1 (a) is a plan view showing a RH degassing tank lower tank bed (tank bottom), FIG. 1 (b) is an AA cross-sectional view of FIG. 1 (a), and FIG. ) Is a BB cross-sectional view of FIG.
FIG. 2 (a) is a plan view showing another RH degassing tank lower tank bed (tank bottom), FIG. 2 (b) is an AA cross-sectional view of FIG. 2 (a), FIG. (C) is BB sectional drawing of Fig.2 (a).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Recirculation pipe 2 ... Nakanoshima 3 ... Recirculation pipe tuyere 4 ... Side wall refractory 5 ... Gap 6 ... Laying part (other laying part)

Claims (5)

A refractory block for Nakanoshima sandwiched between two reflux pipes, a refractory block for each of the above-mentioned reflux pipe tuyere, and a refractory block for a portion other than Nakanoshima and the reflux pipe tuyere , At the bottom of the RH degassing tank of the refractory building structure comprising the refractory block gap and / or the amorphous refractory filled in the periphery,
The refractory block constituting the Nakanoshima is a reverse jack arch structure having a trapezoidal shape spreading downward in a vertical section perpendicular to a line segment connecting the centers of both reflux pipes in a horizontal section , and An RH degassing tank bottom characterized by having a refractory building structure that constitutes a part of a refractory block for a reflux pipe tuyere . From the refractory block for Nakanoshima where the surface of the refractory block is the center of the tank bottom , from the refractory block for the reflux pipe tuyere , and the refractory block for the laying part other than Nakanoshima and the reflux pipe tuyere The RH degassing tank bottom according to claim 1, wherein the bottom is 30 mm or more lower . A block in which the refractory block for Nakanoshima, the refractory block for each reflux pipe tuyere, and the refractory block for the laying part other than Nakanoshima and the reflux pipe tuyere are formed in advance of an irregular refractory The RH degassing tank bottom according to claim 1 or 2, wherein: The RH degassing tank which has the RH degassing tank bottom of any one of Claims 1-3. The refractory block for Nakanoshima according to any one of claims 1 to 3, the refractory block for each recirculation pipe tuyere, and the refractory for a portion other than Nakanoshima and the recirculation pipe tuyere A block manufacturing method, which corresponds to all or part of the bottom of the RH degassing tank to be constructed, partitions the inside of the mold larger than the individual blocks with a plate, and puts an indefinite refractory in the partitioned part A method for producing a refractory block, characterized by pouring, curing, and creating two or more blocks from one mold.

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