JP3226817B2 - Hollow granule mold flux manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention prevents a part of the undried slurry from adhering to the inner surface of the drying tower wall when the raw material slurry is dried in the production of hollow granule mold flux used for continuous casting of steel. Device for

[0002]

2. Description of the Related Art For example, mold flux added to a mold during continuous casting of steel plays various roles. In other words, to keep the surface of the molten steel to be cast warm, to prevent oxidation of the molten steel surface in the mold and to quickly dissolve the floating inclusions, to control the lubrication between the mold and the slab,
Tasks such as controlling the optimal heat removal from the slab are imposed.

[0003] These effects of mold flux (hereinafter simply referred to as "flux") have the effect of eliminating the surface defects of the slab and forming a beautiful casting surface, and in particular, the stability of the casting operation in the continuous casting operation. This is indispensable for securing and improving the yield of slab casting.

The flux is usually in the form of powder or granules (including hollow granules), and its components are generally CaO, S
It is made of iO ₂ as a main component, and in addition to Al ₂ O ₃ , a compound of an alkaline earth metal and an alkali metal (oxide, carbonate, fluoride, etc.). Further, a flux composition is configured by adding carbon in order to adjust the melting rate. In the case of a granular form, an organic or inorganic binder or the like is used (for example,
Technology disclosed in JP-A-60-87960)
It has a certain shape.

[0005] In order to produce a hollow granular flux, a raw material flux containing the above composition is mixed with an appropriate amount of water to form an aqueous slurry, which is sprayed from a nozzle into a hot air drying tower (chamber). It is dried by exposure to hot air to obtain a product flux having an appropriate particle size.

As a known technique of such a method for producing a flux, Japanese Patent Publication No. 3-79100 is disclosed. The gist of this technology is that an aqueous slurry containing a carbonaceous powder and a flux component for metal casting is made, and the aqueous slurry is spray-dried to evaporate water. Generated, and the carbonaceous powder is dispersed and contained throughout the solid portion in the particle, and the ratio of the carbonaceous powder on the surface of the particle in the solid portion is larger than the ratio of the carbonaceous powder in the entire particle. It is characterized by having.

Although the publication does not specifically mention a production apparatus, according to the above-described method for producing a flux for metal casting, spray drying involves dispersing an aqueous slurry as atomized particles from a sprayer by a supply pump. Then, the dispersion is put on the hot air supplied from the air heating and lowered in the drying chamber, and during the descent, the particles are heated with the hot air to instantaneously evaporate the moisture in the particles to form voids in the particles. In addition, it is described that the particles are dried to obtain spherical particles having a porous structure, and the particles thus obtained are introduced into a cyclone together with hot air, where the product and the hot air are separated to obtain a desired flux.

[0008]

Problems to be Solved by the Invention Japanese Patent Publication No. 3-791
According to the flux production technology in Japanese Patent Publication No. 00, when viewed from the attached drawing, the supply of the raw material slurry of the flux to the hot air drying chamber and the supply of the hot air for drying are so-called co-current discharges in the same direction from above the drying chamber. Using a method, heat exchange is performed between the hot air for drying and the raw material slurry to dry the raw material slurry to obtain a flux. However, this publication discloses an unusual situation in which an undried slurry of a raw material slurry (hereinafter, simply referred to as a slurry) adheres to the inner surface of a wall of a hot-air drying tower (hereinafter, simply referred to as a drying tower). Not touched at all.

However, in the production of such a flux, when the slurry flowing and sent in the lance is jetted from the nozzle tip, a part of the slurry is not jetted to the nozzle tip for some reason. An abnormal situation occurs in which the particles adhere in a state and hinder the smooth injection of the slurry.
When such a state occurs, a phenomenon occurs in which the jetting speed of the slurry jetted from the vicinity increases, and the flying distance of the slurry becomes longer. In addition, even though the slurry is usually uniformly mixed, it is suspended and is conveyed in a pulsating manner in the transport pipe. Therefore, when the slurry is jetted from the nozzle, the jet speed changes suddenly. Can extend to unexpected long distances.

[0010] This phenomenon can occur as the amount of binder contained in the raw material increases even in a normal operation. When a part of the sprayed slurry causes the above-mentioned phenomenon, the drying tower mainly facing the slurry spraying direction is mainly used. An undesired situation occurs in which it collides with the inner surface of the wall in an undried state (liquid droplets) and directly adheres to the inner surface of the wall. These deposits are combined with the droplets of the slurry that subsequently fly and the deposits that are generated adjacently, and their growth is promoted, and when they are dried in the attached state, they become a coarse massive flux, and due to their own weight, It falls off the inner wall of the wall and falls into the normally manufactured product stored at the bottom of the drying tower.

Further, if the adhered state is maintained for a long time on the inner surface of the wall, the carbonaceous matter in the adhered substance is decomposed or combined with oxygen in the atmosphere to be oxidized and the surface becomes white. The adhered substance in such a state falls down in the same manner as described above, and is mixed into the product, resulting in a significantly deteriorated product in terms of quality, which is one of the major causes of flux production failure. Furthermore,
If these deposits do not fall from the inner surface of the drying tower wall and remain for a long period of time with the deposits, the deposits must be removed and the flux production operation must be periodically interrupted. Work had to be performed to peel off the kimono from the inner surface of the wall, which was a cause of lowering the productivity of flux production.

FIG. 1 shows an example of such a flux adhesion state. In this example, a so-called countercurrent method is used in which one slurry injection nozzle is provided at the center of the body of the drying tower, and the slurry is injected in the upward direction to supply hot drying air from above the drying tower. This type of drying tower exchanges heat between hot air and slurry.

In FIG. 1, the slurry 2 sprayed from the nozzle 1 is dried while flying to a predetermined distance depending on the spray angle from the nozzle, the spray pressure of the slurry and the amount, pressure and temperature of the dry hot air 5 in a normal state. Drying is also performed during the reversing and falling, and it becomes a flux product and is stored in the lower part of the drying tower. However, as described above, when an abnormal phenomenon of the slurry injection from the nozzle occurs for some reason, the droplets of the injected slurry are deposited on the inner surface of the wall of the drying tower 3 as deposits 4 and stay.

The hot air drying of such a slurry has the above-mentioned problems, and the present invention has been made to solve such problems. It is intended to provide a device.

[0015]

The present invention adopts the following means in order to solve the above problems. (1) In a device for spray-drying a raw material slurry of a mold flux in a hot air drying tower and separating and discharging a hollow granular mold flux and hot air exhaust from a lower portion of the drying tower, the raw material disposed in a straight body portion of the drying tower. A coating layer is formed on the inner surface of the drying zone constituting wall above the mounting position of the slurry injection lance nozzle and up to the hot air inlet at the top of the drying tower to suppress adhesion of droplets generated by spraying the raw slurry. Equipment for manufacturing hollow granule mold flux.

(2) In a device for spray-drying the raw material slurry of the mold flux in a hot air drying tower and separating and discharging the hollow granule mold flux and the hot air exhaust from the lower portion of the drying tower, the raw material slurry is applied to the entire inner surface of the drying tower wall. An apparatus for producing a hollow granule mold flux, wherein a coating layer for suppressing adhesion of droplets generated by spraying is formed.

(3) The apparatus for producing a hollow granule mold flux according to (1) or (2), wherein a sheet material made of heat-resistant synthetic resin is used as a coating layer. (4) The apparatus for producing a hollow granular mold flux according to (1) or (2), wherein the coating layer is formed by applying a synthetic resin aqueous solution having heat resistance.

(5) The apparatus for producing a hollow granular mold flux according to (1) or (2), wherein the coating layer is formed by coating a ceramic aqueous solution. (6) The apparatus for producing a hollow granular mold flux according to (1) or (2), wherein the coating layer is formed by baking an enamel.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One of the measures to prevent deposits on the inner surface of the drying tower wall is that one of the measures is to dry the slurry to a distance where the droplets of the slurry cannot reach even if an abnormality occurs during the slurry injection. If the inner wall of the tower is far away, the problem of adhesion does not occur. Therefore, in order to cope with such a situation, it is necessary to enlarge the equipment scale of the drying tower. However, this requires enormous equipment costs, resulting in an increase in the cost of flux production. Further, simply increasing the scale of the equipment increases the dead space in terms of slurry drying, but does not lead to an increase in productivity.

On the other hand, on the other hand, the equipment scale of the drying tower is kept as it is, and the flying distance of the jet slurry droplets is shortened. In this case, the injection amount of the injection slurry must be limited (reduced), resulting in a significant decrease in the productivity of flux production. Even if any of the above countermeasures are implemented, it is not preferable from the viewpoint of the operation of flux production.

The inventors of the present invention have also investigated where the droplets of the undried slurry adhere to the inner surface of the drying tower wall. As a matter of course, if the slurry is abnormally ejected, It has been found that the most occurs on the inner surface of the wall of the drying tower within the range where the water flies.

This indicates that it depends greatly on the directionality of the slurry when ejected from the nozzle. However, depending on the condition of the generation of deposits on the nozzle tip when the slurry ejection is abnormal, the normal ejection angle may be reduced. It is not appropriate to consider only the inner surface of the wall facing the drying tower within the slurry injection angle as a deposit-preventing area, since it may fly off. It is necessary to take countermeasures wider than the facing wall inside the area.

The inventors of the present invention have conducted various studies on a new countermeasure in place of the above-described countermeasure for preventing the deposits, and as a result, have developed the present invention.

The drying tower is usually made of iron products, and the inner surface of the wall is in a state where droplets of the undried slurry easily adhere. Therefore, if a coating layer is formed on the inner surface of the wall between the inner surface of the drying tower and the droplets of the undried slurry with a weakly adherent substance, the droplets of the undried slurry adhere even if they reach the inner surface of the wall. Therefore, even if they adhere, the amount of adhesion can be significantly reduced.

The present inventors have conducted many tests on various substances in order to adopt a substance having low adhesion of droplets of the undried slurry, and it is most preferable to form a coating layer on the inner surface of the drying tower wall. It is a substance found.

As the material for forming the inner layer of the drying tower wall used in the present invention, there are various substances. For example, a synthetic resin having heat resistance can be used as one of them. Although the synthetic resin itself cannot withstand high temperatures, inside the drying tower targeted by the present invention, the atmosphere temperature is about 400 to 550 ° C. due to the sent dry hot air. Since the inside of the wall is in contact with the atmosphere, the drying tower radiates heat to the atmosphere from the drying tower. Therefore, the temperature of the wall is cooled to about 200 to 350 ° C., so that the wall can be sufficiently used.

Also, a substance selected as a substance which is difficult to adhere also from the aspect of adhesion of the undried slurry droplets is used. As an embodiment, about 2 to 20 mm made of a synthetic resin material such as Teflon is used. Using a sheet plate, where there is a large amount of deposits on the inner surface of the drying tower wall, for example, above the slurry injection lance nozzle mounting position, or only the inner surface of the drying area constituting wall up to the hot air inlet at the top of the drying tower, Alternatively, the formation of a coating layer over the entire inner surface of the drying tower wall can be appropriately selected as necessary or from the viewpoint of workability.

It is also possible to apply the above-mentioned Teflon resin or silicone resin to a portion of the inner surface of the drying tower similar to the portion where the coating layer is formed, in an amount of about 5 to 100 μm. Further, the same effect can be obtained by coating the same portion with the aqueous solution of the ceramic in the same manner as described above by about 5 to 100 μm.

For example, when a coating layer having an appropriate thickness is formed by spraying an aqueous solution of a silicone resin on the inner surface of a drying tower wall by spraying, only the tip nozzle of a slurry injection lance nozzle is suitable for spray coating. It is also possible to replace the nozzle and use the lance or other equipment as it is, or, if separately prepared as a spraying device, use the slurry injection lance insertion port provided on the side wall surface of the drying drum straight body. . In order to observe the application situation described above,
Since an appropriate number of observation windows for monitoring the state of slurry injection are provided in the straight section of the drying tower, use these observation windows to monitor the spraying state of the coating agent from the nozzle and apply the coating agent. Observe the situation.

FIG. 2 shows that, instead of the lance nozzle used for the slurry injection in FIG. 1, a synthetic resin solution as the coating agent 7 is injected toward the inner surface of the wall of the drying tower 3 by the injection nozzle 6 for the solution. This shows a situation in which the coating agent is coated. The spray nozzle uses a nozzle 6 designed to have a wider spray divergence angle than the slurry divergence angle. The pressure sufficient to reach the inner surface of the wall and exert the adhesive force is applied, so that the coating layer 9 can be completely formed. At the time of application, while constantly monitoring the injection status from the viewing window 8,
Adjust the injection pressure, etc.

The formation of the coating layer on the inner surface of the drying tower wall is not limited to the coating method shown in FIG. 2, but an operator can enter the drying tower and spray-coat by hand spray. It can also be done manually using means such as rollers, brushes and the like. Furthermore, when a synthetic resin sheet is used as the above-mentioned coating layer, the intended purpose is achieved by performing gluing on the inner surface of the tower wall with glue previously attached to the back surface of the sheet in the drying tower as described above. Can be reached.
In addition, the enamel may be baked at 5 to 100 μm. In this case, similar to the above-described ceramic, an excellent effect on the fire resistance can be obtained.

In terms of the heat resistance and the life of the wall inner surface coating layer for preventing the droplets of the jet slurry from adhering, it is necessary to operate in a state where the coating layer is maintained at the heat resistance or lower. In this regard, when ceramic, enamel, or the like is used as the wall inner surface coating layer, a large effect can be obtained because both have high heat resistance.

By using the apparatus of the present invention, the droplets of the slurry which collided with the inner surface of the drying tower wall in an undried state do not adhere to the inner surface because the inner surface is formed of the coating layer. Since the product is dried and becomes a normal product, there is no problem that foreign matter is mixed in the product due to spontaneous peeling of the attached matter. Also, even if it adheres, the amount is more than before,
Since the amount is significantly reduced, the time required for removing the deposits is reduced, and the operation rate of the drying tower can be significantly improved.

Next, the hot air drying method for the slurry to be used in the present invention is either the above-described cocurrent method in which the contact direction of the slurry and the hot air is in the same direction, or the countercurrent method in which the contact is made in the opposite direction. The direction of slurry injection may be upward or downward, regardless of the direction. Similarly, it is the number of lance nozzles used for slurry injection, but even if it is a single nozzle type located at the center of the drying tower, a multi-type type in which multiple nozzles are provided at equal intervals in the drying tower In any case, there is no significant difference in the effects. The reason for this is that no matter what form is taken, if an abnormality occurs in the slurry sprayed from the nozzle, the phenomenon described above will be caused, and the countermeasures must be taken in the same manner.

Hereinafter, embodiments of the present invention will be described. One was to apply a 5 mm thick Teflon synthetic resin sheet plate over the entire inner surface of the wall of the drying tower having a diameter of 7 m and a height of 20 m to form one coating layer. In another embodiment, a silicon synthetic resin was sprayed and applied to the inner surface of a wall of a drying tower having the same scale in the same manner as shown in FIG. The thickness of the applied silicone resin was 20 μm on average, and a coating layer was formed on the inner surface of the upper wall of the drying tower and on the inner surface of the wall of the straight body.

By both of these treatments, the abnormal ejection from the slurry nozzle significantly reduces the adhesion of the undried slurry droplets as droplets on the inner surface of the drying tower wall. In this example, it was about 0.1%, in the case of attaching the former Teflon synthetic resin sheet, 0.01%, and in the case of applying the latter silicon synthetic resin, 0.02%, both of which were defective. The occurrence of has greatly decreased.

The number of deposits is ² per m ^{2 in the} case where no conventional treatment is applied to the inner surface of the drying tower wall.
Although 00 occurrences were observed, in this example, the number of occurrences was 10 per m ^{2 in the} former processing, and 20 in the latter processing, and the number of occurrences was clearly reduced. Further, in the case where the apparatus of the present invention was not used, it took about 10 hours to remove the deposits adhering to the inside of the drying tower. The time to do it has become extremely short.

[0038]

According to the present invention, it is possible to prevent undried slurry droplets from adhering to the inner surface of the drying tower wall due to abnormal slurry jetting, or to reduce the amount of adhering even if they are adhered to the inside of the drying tower. Since the incorporation of defective products can be extremely reduced, the drying tower can be operated under favorable conditions, which greatly contributes to the improvement of productivity during flux production.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of a slurry injection situation in a drying tower.

FIG. 2 is a schematic view showing an example of a spray state of a coating agent for forming a coating layer in a drying tower.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Slurry injection nozzle 2 Injection slurry 3 Drying tower 4 Deposit 5 Dry hot air 6 Coating agent injection nozzle 7 Injection coating agent 8 Viewing window 9 Coating layer

Continuation of the front page (56) References JP-A-6-23257 (JP, A) JP-A-3-52637 (JP, A) JP-A-48-23941 (JP, A) JP-A-6-126403 (JP, A) JP-A-52-123330 (JP, A) JP-A-9-57407 (JP, A) JP-A-60-87960 (JP, A) JP-A-4-63129 (JP, A) 57-111301 (JP, U) JP 3-79100 (JP, B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) B22D 11/108 B22D 11/07 C21C 7/076 B01J 2 / 04

Claims (6)

(57) [Claims] 1. An apparatus for spray-drying a raw material slurry of a mold flux in a hot-air drying tower and separating and discharging a hollow granular mold flux and hot-air exhaust from a lower portion of the drying tower. A coating layer that suppresses the adhesion of droplets generated by spraying the raw slurry is formed on the inner surface of the drying zone constituting wall above the mounting position of the lance nozzle for spraying the raw slurry and up to the hot air inlet at the top of the drying tower. Equipment for manufacturing hollow granule mold flux. 2. An apparatus for spray-drying a raw material slurry of a mold flux in a hot air drying tower and separating and discharging a hollow granular mold flux and hot air exhaust from a lower portion of the drying tower. An apparatus for producing a hollow granular mold flux, comprising a coating layer for suppressing adhesion of droplets generated by the method. 3. The apparatus for producing a hollow granular mold flux according to claim 1, wherein a sheet material made of heat-resistant synthetic resin is used as the coating layer. 4. The apparatus for producing a hollow granular mold flux according to claim 1, wherein the coating layer is formed by applying a synthetic resin aqueous solution having heat resistance. 5. A coating layer formed by coating a ceramic aqueous solution.
Or the manufacturing apparatus of the hollow granule mold flux of Claim 2. 6. A coating layer formed by baking an enamel.
An apparatus for producing the hollow granular mold flux according to the above.