JP6292149B2 - Gas seal device and gas seal method for rotary kiln - Google Patents

Description

  The present disclosure relates to a gas seal device and a gas seal method for a rotary kiln.

In the steel making process in the iron making process, a residue called steel slag is generated in each hot metal refining process. Since these steel slag contains valuable metals including phosphorus, a process of separating these valuable metals from the steel slag by reduction treatment or the like is performed. As a method for separating and recovering phosphorus from steel slag, a reduction roasting method using a rotary kiln is known.
In the separation and recovery method of phosphorus using the reduction roasting method, at least one of the steel slag generated during the hot metal dephosphorization process and the steel slag generated during the decarburization refining of the hot metal is charged into the rotary kiln. Roast in a reducing atmosphere inside. By reduction roasting, first, iron oxide contained is reduced from steel slag and recovered as reduced iron. And the reduction | restoration process of the steel slag in which content of the iron oxide fell reduces and removes the phosphorus oxide in steel slag by reduction | restoration to a gaseous phase. Steel slag having a reduced iron oxide and phosphorus content is recycled as a CaO source used in the refining process of the iron making process and the steel making process. The recovered reduced iron is recycled as an iron source in the iron making process and the steel making process.

Usually, a kiln for reduction treatment is required to be airtight in order to prevent leakage of gas in the furnace and inflow of air into the furnace. However, in the case of a rotary kiln that is a rotary heating furnace, a discharge port for an object to be processed at the end of the kiln main body is open, and a seal structure for improving airtightness at the discharge port is required.
As a mechanical structure sealing structure, generally, a double damper is provided with two valve bodies at the top and bottom, and mechanically opens and closes the upper and lower valve bodies alternately to discharge the processed material while performing upper and lower air sealing. The method is known.

Further, in Patent Document 1, as a technique for collecting a processed product while maintaining a reducing atmosphere in the furnace, a water tank is prepared at the processed product discharge port, the processed product is dropped into water, and the kiln discharge port is gas-sealed with water. A method is disclosed.
Furthermore, in Patent Document 2, as a method for preventing leakage of internal gas to the outside of the furnace, there is a method of providing an outside air introduction mechanism for introducing outside air in the seal space of the kiln discharge port and allowing the outside air introduced into the kiln to flow in. It is disclosed.

JP 2005-224802 A JP 2013-50274 A

However, since the raw material is processed at a high temperature of 1000 ° C. or higher in the reduction roasting method, the processed object to be processed becomes a high temperature exceeding 1000 ° C. For this reason, in the case of a double damper type seal structure, the temperature of the valve body that comes into contact with the high-temperature object to be processed rises and corresponding expansion occurs. For this reason, mechanical interference at the time of opening and closing occurs. If a gap is made between the valve body and the double damper main body to absorb this expansion, the airtightness is lowered.
Further, in the case of the method described in Patent Document 1, it is necessary to solid-liquid separate the processed material wetted from water and dry the processed material to a certain moisture content or less. For this reason, processing facilities and processing costs for separation and drying are generated.

Furthermore, in the case of the method described in Patent Document 2, since the outside air flows into the furnace, the reducing atmosphere in the furnace cannot be maintained. Further, since the discharge port is open, the gas seal cannot be completely performed and the airtightness is lowered.
Therefore, the present invention has been made paying attention to the above-mentioned problems, and maintains the airtightness in the rotary kiln and does not require the drying treatment of the workpiece taken out from the rotary kiln and the gas seal device and gas of the rotary kiln It aims to provide a sealing method.

According to one aspect of the present invention, there is provided a gas seal device provided at an end of a rotary kiln that rotates and feeds a raw material of an object to be processed while being rotated, on the downstream side in the raw material transport direction, and is discharged from the rotary kiln. A rotary kiln gas seal device is provided, which has a fluidized bed made of a fluidized material and a gas blowing section for blowing gas into the fluidized bed.
According to one aspect of the present invention, a fluidized bed made of a fluidized material is provided at a downstream end of a rotary kiln that rotates and conveys a raw material of an object to be processed while rotating, and a gas is generated in the fluidized bed. A rotary kiln gas sealing method is provided, in which an object to be processed after a chemical reaction process discharged from a rotary kiln is introduced into a fluidized bed in which gas is blown.

  According to one aspect of the present invention, there are provided a gas seal device and a gas seal method for a rotary kiln that keeps airtightness in the rotary kiln and that does not require drying of an object to be processed taken out of the rotary kiln.

It is a mimetic diagram showing the rotary kiln of one embodiment of the present invention. It is a schematic diagram which shows a gas seal apparatus.

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. However, it will be apparent that one or more embodiments may be practiced without such specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.
<Configuration of gas seal device>
First, with reference to FIG. 1 and FIG. 2, the structure of the rotary kiln 1 of one Embodiment of this invention is demonstrated. The rotary kiln 1 heats the steel slag A and the carbonaceous material B as raw materials, thereby reducing and roasting the steel slag A (chemical reaction treatment), and reducing the reduced iron and phosphorous content slag after the chemical reaction treatment. It is an apparatus that collects the material to be processed C. Iron and steel slag A is slag that is generated during the preliminary dephosphorization treatment and decarburization refining of hot metal in the steelmaking process, and contains phosphorous oxide. Further, the carbon material B is a reducing agent such as charcoal, coal, or coke. As shown in FIG. 1, the rotary kiln 1 includes a cylinder part 2, an upper hood part 3, a lower hood part 4, a charging part 5, a heating part 6, a gas seal device 7, a recovery part 8, and a gas And a recovery pipe 9.

  The cylinder part 2 has a cylindrical shape, and is provided extending in a direction in which the height direction is inclined at a predetermined angle in the horizontal direction. The cylinder part 2 conveys the steel slag A, the carbonaceous material B, and the to-be-processed object C which are to-be-conveyed objects in the cylindrical height direction, and a height object inclines by a predetermined angle to a horizontal direction, The end portion on the downstream side in the transport direction is provided so as to be lower in the vertical direction than the end portion on the upstream side in the transport direction. The inclination angle in the height direction of the cylindrical portion 2 with respect to the horizontal direction is about several degrees, but may be more than that. Further, the cylindrical portion 2 is provided with a pair of rotating gears 21a and 21b and a pair of driving gears 22a and 22b. The pair of rotation gears 21 a and 21 b are respectively provided along the outer periphery of both end portions in the height direction of the cylindrical portion 2. The pair of drive gears 22a and 22b are provided at both ends in the height direction of the cylindrical portion 2 so as to be connected to the pair of rotation gears 21a and 21b. Further, the pair of drive gears 22a and 22b are driven to rotate by receiving a driving force from a drive device such as a motor (not shown) so that the cylindrical portion 2 provided with the pair of connected rotation gears 21a and 21b is provided. Rotate in the circumferential direction.

The upper hood portion 3 is provided so as to cover an end portion of the cylindrical portion 2 on the upstream side in the conveyance direction of the conveyed object. Further, the upper hood portion 3 is formed with two openings at the side portions into which the charging portion 5 and the heating portion 6 are respectively inserted. The lower hood portion 4 is provided so as to cover an end portion of the cylindrical portion 2 on the downstream side in the conveyance direction of the object to be conveyed. Further, the lower hood portion 4 has a discharge port 41 connected to the gas seal device 7 formed in the lower portion and an opening portion connected to the gas recovery pipe 9 formed in the upper portion.
The charging unit 5 is a cylindrical chute inserted into the cylindrical part 2 through an opening formed in the side part of the upper hood part 3, and is connected to a raw material supply apparatus (not shown). The input unit 5 inputs the steel slag A and the carbonaceous material B supplied from the raw material supply device at a predetermined mixing ratio into the cylindrical unit 2.
The heating unit 6 is a heating device such as a burner, and heats the inside of the tube unit 2 to about 1200 ° C to 1500 ° C. Moreover, the heating part 6 is provided in the position which can heat the carbonaceous material B thrown in in the cylinder part 2 directly.

As shown in FIG. 2, the gas seal device 7 includes a first cylinder part 71, a second cylinder part 72, a gas blowing part 73, a fluidized bed 74, and a conveyor 75. The 1st cylinder part 71 has a bottomed cylindrical shape, and is provided so that the bottom part 711 may become a vertical direction upper side. Further, the first cylinder portion 71 has a charging port 712 connected to the discharge port 41 at the center of the bottom portion 711. The 2nd cylinder part 72 has a bottomed cylindrical shape, and is provided so that the bottom part 721 may become a vertical direction lower side. Moreover, the 2nd cylinder part 72 is a magnitude | size which can accommodate the 1st cylinder part 71, and accommodates the 1st cylinder part 71 in the state where a part of upper part of the 1st cylinder part 71 protruded upwards. A plurality of holes 722 are formed at the bottom of the second cylindrical portion 72. The gas blowing portion 73 is provided so as to be connected to the bottom portion 721 of the second cylindrical portion 72, and the gas G is supplied into the second cylindrical portion 72 and the first cylindrical portion 71 through the plurality of holes 722 of the bottom portion 721. Infuse. The gas G blown from the gas blower 73 is a component that does not hinder the chemical reaction process in the rotary kiln 1, and for example, a gas such as Ar, N ₂ , and CO is used. The fluidized bed 74 is made of a fluid material having a specific gravity lighter than that of the workpiece C after the chemical reaction treatment, and is accommodated in the second cylinder part 72 and the first cylinder part 71 accommodated in the second cylinder part 72. . The fluid substance is sand having a softening temperature of 1000 ° C. or more and a uniform particle size. The conveyor 54 is a net-like net conveyor, and is provided along the inner surface and the outer surface of the second cylindrical portion 72. The conveyor 75 is driven along the inner surface and the outer surface of the second cylindrical portion 72 by a driving device (not shown). In the gas seal device 7, the gas G is blown from the gas blowing portion 73 to the fluidized bed 74, and the fluidized bed 74 is fluidized by the gas G blown upward in the vertical direction. In addition, since the conveyor 75 is a net conveyor, the movement in the fluidized bed 74 of the gas G blown from the gas blowing part 73 is not prevented.

The recovery unit 8 has a box shape with an upper surface opened, and is provided below the gas seal device 7. The collection unit 8 collects and accommodates the workpiece C discharged from the gas seal device 7 as will be described later.
The gas recovery pipe 9 is provided in connection with the opening on the upper surface of the lower hood part 4. The generated gas containing phosphorus generated by the reduction process in the rotary kiln 1 is sent to a gas recovery facility (not shown) through the gas recovery pipe 9 and recovered.

<Gas sealing method>
Next, a gas sealing method of the rotary kiln 1 according to this embodiment will be described. First, the steel slag A and the carbonaceous material B which are raw materials are thrown into the cylinder part 2 from the throwing part 5. FIG. At this time, the atmospheric temperature in the cylinder part 2 is heated to about 1200 ° C. to 1500 ° C. by the heating part 6 being combusted and heated. The charged raw material is transported in the conveying direction in which the lower hood portion 4 is provided from the upstream side in the conveying direction in which the feeding portion 5 and the upper hood portion 3 are provided, as the cylindrical portion 2 is rotated by the pair of drive gears 22a and 22b. It is conveyed downstream.
Next, the charged carbonaceous material B is directly heated by the heating unit 6 to generate CO gas, and the inside of the cylinder unit 2 becomes a reducing atmosphere. Furthermore, iron oxide and phosphorous oxide in the steel slag are sequentially reduced in the inside of the cylindrical portion 2 in a reducing atmosphere. Thus, the to-be-processed object C which consists of reduced iron and slag with low phosphorus content is manufactured by a chemical reaction process of a raw material. The phosphorus in the steel slag is reduced and removed to the gas phase and recovered from the gas recovery pipe 9.

  Then, the to-be-processed object C by which the chemical reaction process was carried and it was conveyed to the edge part of the cylinder part 2 is carried out to the upper part of the fluidized bed 74 in the 1st cylinder part 71 through the discharge port 41 and the inlet 712 of the gas seal apparatus 7. It is thrown. At this time, the gas seal device 7 is in a state where the fluidized bed 74 is fluidized by the gas G being blown from the gas blowing portion 73. The to-be-processed object C thrown into the fluidized fluidized bed 74 settles in the fluidized bed 74 due to the difference in specific gravity with the fluidized material, moves below the first cylindrical part 71, and finally the second cylindrical part. The bottom part 721 of 72 is reached. And the to-be-processed object C which reached | attained the bottom part 721 moves to the side part of the 2nd cylinder part 72 further to the upper part along the inner surface of the 2nd cylinder part 72 with the conveyor 75, and is a fluidized bed from the upper opening surface. It is discharged out of 74. The discharged workpiece C is then moved along the outer surface of the side portion of the second cylindrical portion 72 and is recovered to the recovery portion 8 by being separated from the conveyor 75 below the second cylindrical portion 72. .

<Modification>
Although the present invention has been described above with reference to specific embodiments, it is not intended that the present invention be limited by these descriptions. From the description of the invention, other embodiments of the invention will be apparent to persons skilled in the art, along with various variations of the disclosed embodiments. Therefore, it is to be understood that the scope of the claims covers these modifications or embodiments included in the scope and gist of the present invention. For example, in the above embodiment, the heating unit 6 is upstream in the conveyance direction of the object to be conveyed. However, the present invention is not limited to such an example. For example, the heating unit 6 may be provided on the downstream side in the transport direction.
Moreover, in the said embodiment, although the cylinder part 2 was provided with a pair of rotation gear 21a, 21b and a pair of drive gear 22a, 22b, this invention is not limited to this example. Three or more rotation gears and drive gears may be provided in the cylinder part 2 according to the length.

Furthermore, in the said embodiment, when blowing in the gas G from the gas blowing part 73, you may make the temperature of the gas G blown low. By making the temperature of the gas G lower than that of the workpiece C, the fluidized bed 74 can be cooled, and the fluidized bed 74 can be prevented from being heated to a high temperature.
Furthermore, in the said embodiment, although sand was used for the fluid substance of the fluidized bed 74, this invention is not limited to this example. The fluid substance in the fluidized bed 74 may be another substance such as an oxide such as alumina or silica as long as it can withstand the temperature of the object to be treated and has a specific gravity smaller than that of the object to be treated. The fluid substance preferably has a uniform particle size.
Furthermore, in the said embodiment, when taking out the to-be-processed object C from the gas seal apparatus 7, it was set as the structure which uses the conveyor 75, However, This invention is not limited to this example. For example, the workpiece C that has settled down to the bottom of the fluidized bed 74 may be taken out using another take-out mechanism.

<Effect of embodiment>
(1) The gas seal device 7 of the rotary kiln according to the embodiment of the present invention is a gas provided at the downstream end of the rotary kiln 1 that rotates and feeds the raw material of the object to be processed while chemically rotating. The sealing device 7 includes a fluidized bed 74 made of a fluidized substance and a gas blowing unit 73 that blows the gas G into the fluidized bed 74 after the chemical reaction processing object C discharged from the rotary kiln 1 is introduced. Have.
According to the above configuration, the reducing atmosphere inside the rotary kiln 1 is sealed by the fluidized bed 74. In the case of the sealing method using the fluidized bed 74, mechanical interference does not occur compared to a mechanical seal structure such as a double damper system. Moreover, since it is not necessary to open the discharge | emission side of the rotary kiln 1 like patent document 2, the inflow of external air can be prevented. For this reason, the high airtightness of the rotary kiln 1 can be obtained. In addition, when taking out a high-temperature workpiece C by the double damper method, it is necessary to cool the bearing portion with water to prevent seizure, so that the initial cost and the maintenance cost of incidental equipment such as a cooling water circulation pump increase. Become. On the other hand, according to the above configuration, the workpiece C is recovered into the fluidized bed 74, and the high-temperature workpiece C and the mechanical part of the gas seal device 7 are not in direct contact with each other. There is no need to install additional facilities.

  Moreover, according to the said structure, compared with the case where water sealing is carried out like patent document 1, the to-be-processed object C can be taken out without getting wet. This eliminates the need for a treatment for separating the workpiece C from the water and drying it. Further, in the case of the water sealing method, it is necessary to periodically process the water used for the sealing. However, in the above configuration, such water processing may not be performed. Therefore, compared with water sealing, it is possible to reduce the cost for separation / drying of the object C to be processed and the cost for water treatment. Furthermore, according to the said structure, unlike the case where a water seal is used, even if the to-be-processed object C is a water-free thing, it can apply.

(2) The fluidized bed 74 is fluidized by the gas G blown from the gas blowing unit 73.
(3) The fluid substance has a specific gravity smaller than that of the workpiece C.
According to the above configurations (2) and (3), the workpiece C can be reliably settled in the fluidized bed 74.
(4) The fluid substance is sand having a softening temperature of 1000 ° C. or higher.
According to the said structure, since a fluid substance can be used over a long period until sand pulverizes, the cost concerning a maintenance can be reduced.

(5) The gas blowing unit 73 blows in a gas G that does not hinder the chemical reaction process inside the rotary kiln 1.
According to the said structure, the reducing atmosphere in the rotary kiln 1 can be maintained reliably.
(6) The gas sealing method of the rotary kiln 1 according to the embodiment of the present invention is such that the rotary kiln 1 that rotates and conveys the raw material of the workpiece C while rotating is fluidized at the downstream end of the raw material conveyance direction. A fluidized bed 74 is provided, gas G is blown into the fluidized bed 74, and the processed material C after chemical reaction treatment discharged from the rotary kiln 1 is charged into the fluidized bed 74 in which the gas G is blown.
According to the said structure, the effect similar to the structure of said (1) can be acquired.

DESCRIPTION OF SYMBOLS 1 Rotary kiln 2 Tube part 21a, 21b Rotating gear 22a, 22b Drive gear 3 Upper hood part 4 Lower hood part 41 Discharge port 5 Input part 6 Heating part 7 Gas seal device 71 1st cylinder part 711 Bottom part 712 Input port 72 2nd cylinder Part 721 Bottom 722 Hole 73 Gas blowing part 74 Fluidized bed 75 Conveyor 8 Recovery part 9 Gas recovery piping A Steel slag B Carbon material C Processed object G Gas

Claims (5)

A gas seal device provided at the downstream end of the feed direction of the raw material of a rotary kiln that carries out a chemical reaction treatment and transport of the raw material of the workpiece while rotating,
A fluidized bed made of a fluidized material, into which the material to be treated after chemical reaction treatment discharged from the rotary kiln is charged;
A gas blowing section for blowing gas into the fluidized bed ;
A cylindrical portion having a bottomed cylindrical shape, containing the fluidized bed, and having a bottom portion connected to the gas blowing portion;
A conveyor that drives along the inner surface of the cylindrical portion and discharges the processed material that has been input from the fluidized bed;
A gas seal device for a rotary kiln characterized by comprising:   2. The rotary kiln gas seal device according to claim 1, wherein the fluidized bed is fluidized by a gas blown from the gas blowing portion.   The rotary kiln gas seal device according to claim 1 or 2, wherein the fluid substance has a specific gravity smaller than that of the workpiece.   The gas sealing device for a rotary kiln according to any one of claims 1 to 3, wherein the gas blowing section blows the gas that does not inhibit a chemical reaction process inside the rotary kiln. A fluidized bed made of a fluid substance is accommodated in a cylindrical portion having a bottomed cylindrical shape at the end of the rotary kiln that rotates and conveys the raw material of the object to be processed while being rotated, downstream of the raw material in the conveying direction. ,
Gas is blown into the fluidized bed from the bottom of the cylindrical portion ,
The fluidized bed in which the gas has been blown is charged with the material to be processed after the chemical reaction process discharged from the rotary kiln and charged using a conveyor that is driven along the inner surface of the cylindrical portion. A gas sealing method for a rotary kiln, characterized in that an object to be treated is discharged from the fluidized bed .

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