JP2010133617A - Sintering machine and method of operating sintered ore - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing sintered ore for safely manufacturing the sintered ore having high strength and high quality with a high yield in a lower suction type sintering machine, and the sintering machine. <P>SOLUTION: The sintering machine includes: a material supply device for charging a sintering material including powder ore and a charcoal material on a pallet 8 circulated and moved to form a charge layer 9; an ignition furnace 10 for igniting the charcoal material of the charge layer 9; a window box 11 arranged below the pallet 8; and a gaseous fuel supply device 15 arranged on the downstream side of the ignition furnace 10, blowing out gaseous fuel in the atmosphere above the charge layer 9 and mixing the gaseous fuel with air to form diluent gaseous fuel with a combustion lower limit concentration or less. The gaseous fuel supply device 15 includes: a plurality of gaseous fuel supply pipe arrangements disposed within a gas supply hood 16 and supplying the gaseous fuel; a concentration abnormality detection part 52 arranged within the gas supply hood 16 and detecting a concentration abnormality of the diluent gaseous fuel; and an agitating mechanism 51 for agitating the diluent gaseous fuel within the gas supply hood based on the concentration abnormality detected by the concentration abnormality detection part 52. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a sintering machine for producing a high-strength, high-quality sintered ore by using a downward suction type dweroid (DL) sintering machine, and an operation method thereof.

  Sinter ore, which is the main raw material of the blast furnace ironmaking method, is generally manufactured through a process as shown in FIG. The raw materials are iron ore powder, iron mill recovered powder, sintered ore sieve powder (returning), CaO-containing auxiliary raw materials such as limestone and dolomite, granulation aids such as quick lime, coke powder and anthracite. These raw materials are cut out from each of the hoppers 1. The cut out raw material is added with an appropriate amount of water using a drum mixer 2 and the like, mixed and granulated to obtain a sintered raw material which is a pseudo particle having an average diameter of 3.0 to 6.0 mm. On the other hand, the sized coarse ore is cut out from the floor hopper 4 to form a floor layer on the great of the sintering machine pallet 8.

  The sintering raw material is charged on the floor layer on the endless moving type sintering machine pallet 8 through the drum feeder 6 and the cutting chute 7 from the surge hopper 5 arranged on the sintering machine, and sintered. A charge layer 9 of a sintering raw material, also called a binding bed, is formed. The thickness (height) of the charging layer is usually around 400 to 800 mm. Thereafter, the ignition furnace 10 installed above the charging layer 9 ignites the carbonaceous material in the surface layer of the charging layer 9 and air through a wind box 11 disposed under the pallet 8. Is sucked downward to sequentially burn the carbonaceous material in the charging layer, and the sintered raw material is burned and melted by the combustion heat generated at this time to obtain a sintered cake. The sintered cake thus obtained is then crushed and sized, and recovered as a product sintered ore comprising agglomerates of 5.0 mm or more.

  In the manufacturing process, first, the ignition layer 10 is ignited by the ignition furnace 10. The ignited carbon material in the charging layer continues to be burned by the air sucked from the upper layer portion to the lower layer portion of the charging layer by the windbox, and the combustion zone gradually moves to the lower layer and forward as the pallet 8 moves. Proceed (downstream). As the combustion progresses, the moisture contained in the sintering raw material particles in the charging layer is vaporized by the heat generated by the combustion of the carbonaceous material, sucked downward, and the lower layer where the temperature has not yet risen. Concentrate in the sintering raw material to form a wet zone. If the moisture concentration exceeds a certain level, moisture fills the gaps between the raw material particles, which are the flow paths of the suction gas, and the ventilation resistance is increased. Note that the melted portion necessary for the sintering reaction that occurs in the combustion zone is also a factor that increases the ventilation resistance.

The production amount (t / hr) of the sintering machine is generally determined by the sintering production rate (t / hr · m ² ) × sintering machine area (m ² ). That is, the production volume of the sintering machine includes the machine width and length of the sintering machine, the thickness of the raw material deposition layer (charge layer thickness), the bulk density of the sintering raw material, the sintering (combustion) time, the yield, etc. It depends on. In order to increase the production of sintered ore, the air permeability (pressure loss) of the charging layer is improved to shorten the sintering time, or the cold strength of the sintered cake before crushing is increased. It is considered effective to improve the retention.

FIG. 15 shows the inside of the charging layer when the combustion (flame) front moving through the charging layer having a thickness of 600 mm is at a position of about 400 mm (200 mm from the surface of the charging layer) on the pallet of the charging layer. This shows the pressure loss and temperature distribution. The pressure loss distribution at this time is about 60% in the wet zone and about 40% in the combustion / melt zone.
FIG. 16 shows the temperature distribution in the charging layer during high production and low production of sintered ore. The time during which the raw material particles begin to melt at a temperature of 1200 ° C. or higher (hereinafter referred to as “high temperature region holding time”) is t _{1 in} the case of low production, and in the case of high production with an emphasis on productivity. It is represented by t _2. In the case of high production, in order to increase the moving speed of the pallet, the high temperature region holding time t ₂ becomes shorter than t _{1 in the} case of low production. When the high temperature region holding time is shortened, firing becomes insufficient, resulting in a decrease in the cold strength of the sintered ore and a decrease in yield. Therefore, in order to increase the production amount of high-strength sintered ore, the yield strength is maintained and improved by increasing the strength of the sintered cake, that is, the cold strength of the sintered ore, even in the short-time sintering. It is necessary to take some measures that can be done. In general, SI (shutter index) and TI (tumbler index) are used as indices representing the cold strength of sintered ore.

  17A shows the progress of sintering in the charging layer on the sintering machine pallet, FIG. 17B shows the temperature distribution (heat pattern) in the sintering process in the charging layer, and FIG. ) Shows the yield distribution of the sintered cake. As can be seen from FIG. 17B, the temperature of the upper portion of the charging layer is less likely to rise than the lower layer portion, and the high temperature region holding time is also shortened. Therefore, in the upper part of the charging layer, the combustion melting reaction (sintering reaction) becomes insufficient and the strength of the sintered cake is lowered, so that the yield is low and the productivity is low as shown in FIG. It is a factor that causes a decline in

  In view of these problems, a method for imparting high temperature retention to the upper portion of the charging layer has been conventionally proposed. For example, Patent Document 1 discloses a technique for injecting gaseous fuel onto a charging layer after ignition of the charging layer. However, although the kind of gaseous fuel (flammable gas) is unknown in the above technique, even if it is propane gas (LPG) or natural gas (LNG), a high concentration gas is used. Moreover, since the amount of the carbon material is not reduced when the combustible gas is blown, the inside of the sintered layer becomes a high temperature exceeding 1380 ° C. For this reason, this technique has not been able to enjoy sufficient cold strength improvement and yield improvement effects. Moreover, when inflammable gas is injected immediately after the ignition furnace, there is a high risk of fire in the upper space of the sintering bed due to combustion of the combustible gas, and this is a technology that is not realistic and has not yet been put into practical use. .

  Patent Document 2 also discloses a technique of adding a combustible gas to the air sucked into the charging layer after the charging layer is ignited. It is said that about 1 to 10 minutes of supply after ignition is preferable, but the surface layer portion immediately after ignition in the ignition furnace has red-hot sintered ore remaining, and depending on the supply method, combustible gas There is a high risk of fire due to combustion, and there are few specific descriptions, but there is no effect even if combustible gas is burned in a sintered sintered zone. Since the air permeability is deteriorated due to thermal expansion, the productivity tends to be reduced, so that it has not been put into practical use.

Further, even in this technique, the amount of carbon material is not reduced when the combustible gas is blown, so that the inside of the sintered layer becomes a high temperature exceeding 1380 ° C. Therefore, it is not possible to enjoy a sufficient improvement in cold strength and a yield improvement effect. Furthermore, even if the obtained sintered ore is a sintered ore with poor reducibility.
In Patent Document 3, a hood is disposed on the charging layer in order to make the inside of the charging layer of the sintering raw material high temperature, and a mixed gas with air and coke oven gas is passed through the hood immediately after the ignition furnace. It is disclosed to blow in position. However, this technique also has a high temperature exceeding 1380 ° C. in the combustion melting zone in the sintered layer, so that the effect of coke oven gas blowing cannot be enjoyed, and the combustible mixed gas is ignited in the upper space of the sintering bed. There is a risk of fire and is not put into practical use.

  Further, Patent Document 4 discloses a method in which a low-melting-point solvent, a carbon material, and a combustible gas are simultaneously blown at a position immediately after the ignition furnace. However, this method also has a high risk of fire in the upper space of the sintering bed because the flammable gas is blown in a state where a flame remains on the surface, and the width of the sintering zone cannot be made sufficiently thick (approximately (Less than 15 mm), the effect of inflammable gas blowing cannot be fully exhibited. In addition, since there are many low-melting solvents, excessive melting phenomenon is caused in the upper layer portion, and the pores that become air flow paths are blocked, resulting in deterioration of air permeability and reduction of productivity. This technology has not been put into practical use until now.

As described above, none of the conventional techniques proposed so far has been put into practical use, and the development of a combustible gas blowing technique that can be implemented has been eagerly desired.
As a technique for solving the above-mentioned problems, the present applicant, in Patent Document 5, disclosed various gaseous fuels diluted below the lower combustion limit concentration from above the charging layer of the sintering raw material that was valued on the pallet of the sintering machine. A method is proposed in which either one or both of the maximum attained temperature and the high temperature region holding time in the charging layer are adjusted by supplying, introducing into the charging layer, and burning.
Japanese Patent Laid-Open No. 48-18102 Japanese Patent Publication No.46-27126 JP-A-55-18585 Japanese Patent Laid-Open No. 5-311257 WO2007-052776

  The technique of the above-mentioned patent document 5 is a downward suction type sintering machine that supplies (introduces) gaseous fuel diluted to a predetermined concentration into the charging layer and burns it at a target position in the charging layer. By supplying it, it is possible to appropriately control the maximum temperature reached during combustion of the sintered raw material and the holding time in the high temperature range, and as a result, the cold layer strength of the sintered ore tends to be low due to insufficient heat. Operation which raises the sinter intensity | strength not only in a part but in the arbitrary parts below a charging layer middle layer part can be performed.

  However, when performing the above gas fuel supply sintering operation, the high temperature part such as the cracked part of the sintering bed or the sintered cake becomes a fire, and the gas fuel is backfired. There is a risk of burning (ignition). If the sintering operation is continued in such a flammable state (aside from the explosion problem), not only the gaseous fuel cannot be supplied into the charging layer, but also the oxygen-deficient atmosphere in which oxygen is consumed by the combustion of the gaseous fuel. Is supplied (introduced) into the charging layer. As a result, not only can the maximum temperature and high temperature range holding time during combustion not be controlled, but also a lack of combustion, resulting in a decrease in strength of the sintered ore and a decrease in yield and productivity. It will have a serious adverse effect.

  Therefore, the present invention has been made paying attention to the problems of the above-described conventional example, and in a downward suction type sintering machine, a high-strength, high-quality sintered ore can be produced with high yield and safety. It aims at providing a sintering machine and its operating method.

  In order to achieve the above object, a sintering machine according to the present invention includes a raw material supply device for forming a charging layer by charging a sintered raw material containing fine ore and carbonaceous material onto a circulating pallet; An ignition furnace for igniting the charcoal of the charging layer; a wind box disposed below the pallet; and gaseous fuel disposed on the downstream side of the ignition furnace with an atmosphere above the charging layer A gaseous fuel supply device that is injected into the gas and mixed with air to form a diluted gaseous fuel having a lower combustion limit concentration or less, and the gaseous fuel supply device supplies a plurality of gaseous fuels arranged in a gas supply hood. A gas fuel supply pipe, a concentration abnormality detection unit for detecting a concentration abnormality of the diluted gas fuel disposed in the gas supply hood, and the gas supply hood based on the concentration abnormality detected by the concentration abnormality detection unit. A stirring mechanism for stirring the diluted gas fuel It is characterized in Rukoto.

The sintering machine according to claim 2 is characterized in that, in the invention according to claim 1, the concentration abnormality detecting section is disposed at least at a corner in the gas supply hood.
A sintering machine according to claim 3 is characterized in that, in the invention according to claim 1 or 2, the concentration of the diluted gas fuel is set to 1/3 or less of the lower limit combustion concentration.
According to a fourth aspect of the present invention, there is provided a sintering machine according to any one of the first to third aspects, wherein the stirring mechanism is disposed in the gas supply hood.

A sintering machine according to a fifth aspect is the invention according to any one of the first to third aspects, wherein the stirring mechanism is disposed outside the gas supply hood.
In the sintered ore operation method according to claim 6, a sintered raw material containing fine ore and a carbonaceous material is charged on a circulating pallet, and a charged layer of the sintered raw material is formed on the pallet. A charging step; an ignition step of igniting the charcoal material on the surface of the charging layer using an ignition furnace; and a gas supply hood that jets gaseous fuel into the air above the charging layer within a combustion lower limit concentration or less A gaseous fuel supply step for making the diluted gas fuel, and the diluted gas and air are sucked and introduced into the charging layer by a wind box disposed under the pallet, and the diluted gas fuel is introduced into the charging layer. And a sintering process for producing a sintered cake by burning a carbonaceous material, and a concentration abnormality detector in a portion where the diluted gas fuel in the gaseous fuel supply process is likely to have a high concentration When the concentration abnormality is detected by the concentration abnormality detection unit It is characterized by agitating the diluted gaseous fuel in the gas supply hood.

  According to the present invention, in the downward suction type sintering machine, a plurality of gaseous fuel supply pipes are laid in the gas supply hood, and gaseous fuel is ejected from the gaseous fuel supply pipes above the charging layer. When the gas abnormality is detected in the gas supply hood by the gas abnormality detection unit when the gaseous fuel is mixed with air and introduced into the charging layer as a diluted gaseous fuel having a concentration lower than the lower combustion limit, it is diluted by the stirring mechanism. The gas fuel can be agitated to make the distribution of the diluted gas fuel concentration in the gas supply hood uniform, and it is possible to reliably prevent the abnormal concentration state from continuing and perform safe operation.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing a sintering machine of the present invention. As described in the above-described conventional example, CaO-containing CaO such as iron ore powder, iron mill recovered powder, sintered ore sieving powder, limestone and dolomite System auxiliary materials, granulation aids such as quick lime, raw materials such as coke powder and anthracite are cut out from individual hoppers, mixed with an appropriate amount of water with a drum mixer, granulated, and 3.0 to 6.0 mm A sintered raw material that is a pseudo particle having an average diameter is stored in the surge hopper 5, and a fine-grained sintered ore is stored in the floor hopper 4.

Along with the movement of the endless moving sinter pallet 8, fine sinter ore is cut out from the floor hopper 4 to form a floor layer on the great of the sinter pallet 8, and the floor layer Sintering raw material is charged from the surge hopper 5 through the drum feeder 6 and the cutting chute 7 to form a charging layer 9 having a thickness (height) of about 400 to 800 mm, also called a sintering bed. .
An ignition furnace 10 is disposed on the downstream side of the cut chute 7 above the charging layer 9, and the carbon material in the surface layer of the charging layer 9 is ignited by the ignition furnace 10. The ignition furnace 10 is supplied with a coke oven gas called a so-called C gas generated in a coke oven in the ironworks. By burning this coke oven gas, the charcoal in the surface layer of the charging layer 9 is supplied. Ignite the material.

A secondary furnace 12 is disposed on the downstream side of the ignition furnace 10, a heat retaining furnace 13 is disposed on the downstream side of the secondary furnace 12, and a plurality of gaseous fuel supply devices are disposed on the downstream side of the heat retaining furnace 13. 15 is disposed.
As shown in FIG. 2, one or more gas fuel supply devices 15 are disposed downstream of the ignition furnace 10 and at any position in the pallet traveling direction in the process in which the combustion / melting zone proceeds in the charging layer 9. It is preferable that the gaseous fuel is supplied into the charging layer 9 at a position after ignition of the carbon material in the charging layer 9. One or more gaseous fuel injection devices 15 are disposed downstream of the ignition furnace 10 at an arbitrary position after the combustion front has traveled below the surface layer. From the viewpoint of improving the cold strength and reducibility, the size, position, and number of arrangements are determined as described later.

As shown in FIGS. 2 and 3, the gaseous fuel injection device 15 has a gas supply hood 16 having an open upper end surrounding the upper portion of the sintering machine pallet 8.
In the gas supply hood 16, a baffle plate 19 having a cross-sectional shape extending in the conveying direction of the sintering machine pallet 8 between the front and rear walls 17 and perpendicular to the conveying direction of the sintering machine pallet 8 is provided. Three baffle plate rows 20 having a configuration in which a predetermined number of baffle plates are arranged in parallel with a predetermined pitch p in the width direction are arranged in the vertical direction, and one baffle plate row is arranged between the baffle plate rows 20 adjacent in the vertical direction. The baffle plates 19 of the other baffle plate row 20 are disposed between the 20 baffle plates 19.

  Further, for example, seven gaseous fuels are supplied between the baffle plates 19 on the lower side of the lowermost baffle plate row 20 in the conveying direction of the sintering machine pallet 8 and maintaining a predetermined interval in the width direction orthogonal to the conveying direction. A pipe 21 is provided. As shown in FIG. 2, each of these gaseous fuel supply pipes 21 is connected to a gaseous fuel supply source pipe 22 at both ends in the transport direction of the sintering machine pallet 8, and gaseous fuel is supplied to these gaseous fuel supply source pipes 22. Have been supplied.

As this gaseous fuel, propane gas, hydrogen gas, methane gas, carbon monoxide gas (CO), coke oven gas (C gas), LNG, blast furnace gas (B gas), blast furnace / coke oven mixed gas (M gas), Either city gas or a mixture of these can be applied.
Each of these contains a combustion component, and any one of these gaseous fuels is discharged into the air at high speed, mixed with air and diluted to obtain a diluted gaseous fuel having a combustion lower limit concentration of about 75% or less. Supply (introduction) into the charging layer 9.

  Here, the properties of propane gas, hydrogen gas, methane gas, carbon dioxide gas, coke oven gas, LNG, and blast furnace gas in the gaseous fuel are shown in Table 1 below.

In this embodiment, LNG is applied as the gaseous fuel.
Among the gaseous fuel supply pipes 21, the gaseous fuel injection nozzles 23 are disposed inwardly with respect to the gaseous fuel supply pipes 21 at both ends in the width direction, and the adjacent gaseous fuel supply pipes 21 are disposed adjacent to each other. Discharged gas fuel jet nozzles 22 as jet nozzles for jetting a predetermined number of gaseous fuels in the horizontal direction at a predetermined pitch in the conveying direction of the sintering machine pallet 8 are disposed at symmetrical positions opposite to each other.

  Here, between the adjacent gas fuel supply pipes 21, as shown in FIG. 4, the gas fuel injection nozzle 22 of one gas fuel supply pipe 21 is in the center between the gas fuel injection nozzles 22 of the other gas fuel supply pipe 21. Gaseous fuel injection nozzles 22 are arranged in a staggered manner between adjacent gaseous fuel supply pipes 21 so as to be arranged at positions. For this reason, the gaseous fuels injected in the adjacent gaseous fuel supply pipes 21 are evenly dispersed without interfering with each other, injected onto the charging layer 9 and mixed with the air to form the diluted gaseous fuel 24. Then, using the suction force of a wind box (not shown) under the sintering machine pallet 8, the sintered cake generated on the surface layer of the charging layer 9 is introduced to the deep part (lower layer) of the charging layer. The

Each gaseous fuel supply pipe 21 is provided with a shut-off valve 25 at a connection portion with the gaseous fuel supply source pipe 22.
Further, the gaseous fuel supply device 15 causes the gaseous fuel to be discharged into the atmosphere at a high speed above the charging layer 9, thereby mixing with the surrounding air in a short time, and below the lower combustion limit concentration of the gaseous fuel. It is necessary to introduce the diluted gaseous fuel 24 into the charging layer.

In the present invention, the gaseous fuel supply device 15 causes the gaseous fuel to be discharged into the atmosphere at a high speed above the charging layer 9, thereby mixing with the surrounding air in a short time, and the gaseous fuel is The reason why it is necessary to dilute to a concentration below the lower combustion limit concentration and then introduce the diluted gaseous fuel into the charge layer is as follows.
As shown in FIG. 5 (a), a sintered pan having an inner diameter of 300 mmφ × a height of 400 mm is filled with a sintered cake, and a nozzle is embedded at a depth of 90 mm from the center of the sintered cake, Table 4 shows the results of measuring the methane gas concentration in the circumferential direction and the depth direction in the sintered cake by blowing 100% methane gas to 1 vol% against air. On the other hand, as shown in FIG. 5 (b), the distribution of the methane gas concentration was measured in the same manner as described above for the case where methane gas was supplied from a position 350 mm above the sintered cake using the same nozzle. 2 and Table 3. From these results, when methane gas was directly introduced into the sintered cake, the lateral diffusion of methane gas was insufficient, whereas when methane gas was supplied above the sintered cake, It can be seen that the methane gas concentration in the cake is almost uniform and diffuses sufficiently in the lateral direction. From the above results, it is understood that the gaseous fuel is preferably diluted uniformly before being introduced into the charging layer by supplying it into the air above the sintered cake.

  In addition, it is preferable to perform discharge of the gaseous fuel in the said gaseous fuel supply apparatus at the height of 300 mm or more above the charging layer surface. Fig. 6 shows the expansion of methane gas when methane gas (concentration: 100%) is discharged from two types of nozzles with a nozzle diameter of 2 mmφ and 1 mmφ in a flow rate range of 20 to 300 m / s and discharged vertically downward. This shows the spread at positions 0.2 m, 0.4 m, 0.6 m and 0.8 m from the nozzle tip. From these figures, the smaller the nozzle diameter and the higher the speed of the gaseous fuel to be discharged, the easier the mixing with the surrounding air occurs, and the dilution is promoted. It can be seen that the distance from the nozzle tip increases at 0.4 m. Therefore, the present invention considers this result and the rebound of the discharged gaseous fuel on the charged layer surface, and the gaseous fuel is supplied to the atmosphere at a height of 300 mm or more above the charged layer surface. To do.

  Next, in the present invention, the discharge speed of the gaseous fuel from the gaseous fuel injection nozzle 23 provided in the gaseous fuel supply pipe 21 of the gaseous fuel supply apparatus 15 needs to be discharged at a high speed from the viewpoint of preventing flashback. Specifically, it is desirable to discharge at a rate twice or more the combustion speed of the gaseous fuel, more preferably at a rate twice or more the turbulent combustion rate of the gaseous fuel. That is, in the sintering operation of the present invention, there is a sintered layer that forms or is forming a combustion / melting zone in the sintering pallet, and in the state that always has a fire type, above the charging layer 9. The discharge operation of the gaseous fuel is performed. The gaseous fuel is diluted by the stage of being sucked / introduced into the surface layer of the charging layer to be below the lower combustion limit concentration in the atmosphere, but the possibility of flashback always follows. Therefore, in order to prevent backfire even when the gas fuel is ignited, the discharge speed of the gas fuel is at least twice the combustion speed of the gas fuel, more preferably twice the turbulent combustion speed. It is desirable to discharge at the above speed.

In order to obtain the discharge speed of the gaseous fuel, it is preferable that the discharge pressure of the gaseous fuel from the gaseous fuel injection nozzle 23 is 300 mmAq or more and less than 40000 mmAq with respect to the atmospheric pressure.
In addition, when the piping for discharging the gaseous fuel and the opening have the same shape, generally, the closer the fuel is to the supply source header, the easier the fuel comes out, and the farther the fuel becomes, the more difficult it is to go out. Therefore, when using long piping,
(A) Use a tapered pipe with a gradually reduced cross-sectional area in the pipe. (B) Increase the opening cross-sectional area as it is farther from the fuel supply header. (C) Opener and nozzle as it is farther from the fuel supply header. Narrow the pitch and increase the sum of openings or nozzle cross-sectional area per unit pipe length.
By applying any one of these or combining them, fuel can be supplied evenly even when the pipe length is long.

Next, the countermeasure against the cross wind of the gaseous fuel supply apparatus of the present invention will be described.
In the present invention, as described above, the hood 16 surrounding the upper portion of the sintering machine pallet 8 is provided. The hood 16 suppresses the influence of the crosswind on the concentration distribution of the diluted gas fuel 29. That is, as a result of various studies by the inventors, it has been found that the installation of the hood 16 is more effective than a screen as a measure against cross wind.

Thereby, the coke oven gas injected from the gaseous fuel injection nozzle 23 and the atmosphere are mixed inside the hood 16.
Further, as shown in FIG. 7, the cross wind attenuation fence 16c made of punch metal having a transmittance of about 30% is provided at the upper ends of the left and right sidewalls 17 and 18 along the conveying direction of the sinter pallet 8 of the hood 16. Is preferably provided.

  In addition, a gap is inevitably generated between the lower side of the hood 16 and the surface of the sintered bed (the surface of the charging layer), but if the gap is not sufficiently sealed, for example, the transmittance is 20 to 20%. When it was 30%, it was found that air was entrained into the hood 16 from this portion, and the concentration distribution of the diluted gas fuel was increased. Therefore, it is important to prevent air from entering from the lower end of the hood 16.

  Therefore, between the lower ends of the left and right sidewalls 18 along the conveying direction of the sintering machine pallet 8 of the hood 16 and the pallet sidewalls 8a, the lower surface of the branch injection portion 27 of the spray mechanism 23, and the upper surface of the charging layer 9 As shown schematically in FIG. 3, a wiper seal 41 having a seal sheet interposed between wire brushes extending in the conveying direction of the sintering machine pallet 8 is installed, and the wiper seal 41 is covered on the outer side thereof. A cover 42 is provided. The seal material is not limited to the wiper seal 41, and seal materials such as a chain curtain, a seal brush, and a close seal can be applied. Moreover, it is preferable that the sealing material is heat resistant, flexible or has a high degree of freedom of deformation, and does not damage the surface of the charging layer 9.

On the other hand, between the lower end of the front and rear plate portions 16b of the hood 16 and the surface of the charging layer 9 on the upstream side and the downstream side in the conveying direction of the sintering machine pallet 8, the front and rear walls of the hood 16 as shown in FIG. It is preferable to form an air curtain 44 by disposing an air passage 43 along 19 and ejecting air from below the air passage 43.
Further, the installation position, size, and number of arrangements of the gaseous fuel injection device 15 are set as follows.

  That is, after the carbon material in the charging layer 9 is ignited, the diluted gas fuel 24 is supplied (introduced) onto the charging layer 9. The reason is that, even if the diluted gas fuel 24 is supplied at a position immediately after ignition, it only burns on the surface layer of the charging layer 9, and the diluted gas fuel 24 has no influence on the combustion layer. is there. Therefore, it is necessary to supply the diluted gas fuel 24 to the charging layer 9 after the sintered raw material above the charging layer 9 is fired to form a sintered cake layer. The diluted gas fuel 24 can be supplied at any position until the sintering is completed as long as a sintered cake layer is formed on the surface of the charging layer 9. The reasons other than the above for supplying the diluted gas fuel 24 after the sintered cake layer is formed are as follows.

(A) If the diluted gas fuel 24 is supplied in a state where no sintered cake (sintered layer) is formed on the top of the charging layer 9, there is a possibility that combustion will occur on the charging layer 9. .
(B) It is preferable to supply the diluted gas fuel to a portion where it is necessary to improve the yield of the sintered ore, that is, to supply combustion in a portion where the strength of the sintered ore is desired to be increased.
In order not to burn on the upper side of the charging layer 9 of the diluted gas fuel 24, after the surface layer portion of the charging layer 9 is ignited by the ignition furnace 10, after ignition and the sintered cake is generated on the surface, There is no fire type in the surface layer portion of the charging layer 9, and the probability of backfire (ignition) is low. As shown in FIG. 17A, the thickness of the sintered cake increases as the sintering machine pallet 8 moves from the ignition furnace 10 to the downstream side. When the thickness from the surface is 20 mm or more, the possibility of backfire is sufficiently low, and when the thickness of the sintered cake is 50 mm or more, backfire can be reliably prevented.

  Thus, the suitable blowing position of the diluted gas fuel in which the thickness of the sintered cake is 20 mm or more, preferably 50 mm or more is a position 5 to 6 m downstream from the ignition furnace 10, and the first gas is located at this position. A fuel supply device 15 is provided. In the case where a plurality of gaseous fuel supply devices 15 are arranged, since there is no fire on the surface of the charging layer 9 as long as it is downstream of the first gaseous fuel supply device 15, the gaseous fuel supply device is at an arbitrary position. In this embodiment, four gaseous fuel supply devices 15 are arranged in series along the conveying direction of the sintering machine pallet 8.

  Further, in order to adjust either or both of the maximum reached temperature of the charging layer or the high temperature region holding time, the thickness of the combustion / melting zone is at least 15 mm or more, preferably 20 mm or more, more preferably 30 mm or more. The diluted gas fuel 24 is preferably supplied. When the thickness of the combustion / melting zone is less than 15 mm, the cooling effect by the air sucked through the sintered cake (sintered layer) and the diluted gas fuel 24 is insufficient even if the diluted gas fuel 24 is burned, This is because the thickness of the combustion / melting zone cannot be increased.

On the other hand, when the diluted gas fuel 24 is supplied at a stage where the thickness of the combustion / melting zone is 15 mm or more, preferably 20 mm or more, more preferably 30 mm or more, the thickness of the combustion / melting zone is greatly expanded, and the high temperature range holding time is increased. Thus, a sintered ore with high cold strength can be obtained.
The introduction of the diluted gas fuel 24 into the charging layer 9 is performed at a position where the combustion front is lowered below the surface layer and the combustion / melting zone is lowered from the surface layer by 100 mm or more, preferably 200 mm or more, that is, in the charging layer 9. -It is preferable to supply so that it may pass through the sintered cake area | region (sintered layer) produced | generated in the lower layer, without burning, and may burn in the stage which the combustion front moved 100 mm or more from the surface layer. The reason is that if the combustion front is at a position lower than the surface layer by 100 mm or more, the adverse effect of cooling by the air sucked through the sintered layer is reduced, and the thickness of the combustion / melting zone can be increased. . Furthermore, if the combustion / melting zone is at a position 200 mm or more lower than the surface layer, the influence of cooling by air is substantially eliminated, and the thickness of the combustion / melting zone can be increased to 30 mm or more. Further, it is more preferable that the diluted gas fuel 24 is supplied in the vicinity of the sidewalls of the both pallet width direction coal portions where the yield reduction is large.

The gaseous fuel supply device 15 differs depending on the size of the sintering machine. For example, in a sintering machine having a production amount of about 15,000 t / day and a length of 90 m, the ignition furnace 10 It is preferable to arrange at a position about 5 m or less downstream.
In the method for producing sintered ore according to the present invention, the introduction of the diluted gaseous fuel 24 into the charging layer also means that the reheating of the produced sintered cake is promoted. That is, this diluted gaseous fuel is originally supplied with a highly reactive gaseous fuel compared to the solid fuel to the portion where the cold strength of the sintered ore is low and the cold strength of the sintered ore is likely to be short of heat. This is because the heat of combustion in this portion that is likely to be deficient is compensated for, and the regeneration / expansion of the combustion / melting zone is assumed.

  Further, in the method for producing sintered ore according to the present invention, the supply of the diluted gaseous fuel 24 from the upper part of the charged layer after ignition is such that at least a part of the introduced diluted gaseous fuel 24 in the charged layer is unburned. It is preferable that the fuel reaches the combustion / melting zone and is burned at a target position where combustion heat is to be compensated. It is considered that it is more effective to supply the diluted gas fuel, that is, to introduce the effect into the charging layer not only to the upper part of the charging layer but also to the combustion / melting zone which is the central part in the thickness direction. Because. That is, if the supply of the diluted gas fuel 24 is performed in the upper layer portion of the charging layer that is likely to be insufficient in heat (insufficient holding time in the high temperature range), sufficient combustion heat is provided, and this portion is sintered. The quality of the cake can be improved, and further, if the supply operation of the diluted gas fuel 24 is extended to the zone below the middle layer, the recycle by the diluted gas fuel 24 is performed on the combustion / melting zone of the original carbon material. The result is equivalent to the formation of a combustion / melting zone, leading to a widening of the combustion / melting zone in the vertical direction, so it is possible to extend the holding time of the high temperature range without increasing the maximum temperature, so the pallet This is because sufficient sintering can be realized without lowering the moving speed of. As a result, the quality of the sintered cake of the charging layer 9 as a whole (improvement of cold strength) is brought about, leading to improvement of the quality (cold strength) and productivity of the product sintered ore.

In the present invention, when introducing (supplying) the diluted gas fuel 24 into the charging layer 9, not only adjusting the supply position but also controlling the form of the combustion / melting zone itself, It is preferable to control the maximum temperature reached and / or the high temperature region holding time in the combustion / melting zone.
In general, in the charged layer 9 after ignition, the combustion (flame) front gradually expands downward and forward (downstream) as the sintering machine pallet 8 moves, so that the position of the combustion / melting zone Changes as shown in FIG. And as shown in FIG.17 (b), the thermal history received in the sintering process in a sintered layer differs in an upper layer, an intermediate | middle layer, and a lower layer, and it is high temperature range holding time (about 1200 degreeC or more with an upper layer-lower layer). Time) is very different. As a result, the yield of sintered ore by position in the pallet 8 shows a distribution as shown in FIG. That is, the yield of the surface layer portion (upper layer portion) is low, and the yield distribution is high in the middle layer and the lower layer portion. Therefore, if the diluted gas fuel 24 is supplied according to the method of the present invention, the combustion / melting zone has an increased thickness in the vertical direction and a width in the pallet traveling direction, which is reflected in improving the quality of the product sintered ore. is there. And since the intermediate | middle layer part and lower layer part which become high yield distribution can control high temperature range holding time, it can raise a yield more.

  By adjusting the supply (introduction) position of the diluted gas fuel 24, the form of the combustion / melting zone, that is, the thickness in the height direction of the combustion / melting zone and / or the width in the pallet traveling direction can be controlled, It is possible to control the maximum temperature and the high temperature holding time. These controls make the effects of the present invention stand out more and are always sufficient through expansion of the vertical thickness of the combustion / melting zone and the width of the pallet traveling direction, and control of the maximum temperature reached and the high temperature range holding time. Performs firing and contributes effectively to improving the cold strength of the sintered product ore.

  In the present invention, it can also be said that the supply (introduction) of the diluted gas fuel 24 into the charging layer 9 is for controlling the cold strength of the entire sintered product ore. That is, the original purpose of supplying the diluted gas fuel 24 is to improve the cold strength of the sintered cake, and consequently the sintered ore, and in particular, the supply position control of the diluted gas fuel 24 and the sintering raw material are combusted. -Through control of the high temperature region holding time, which is the time to stay in the melting zone, and control of the maximum temperature, the cold strength (shutter index SI) of the sintered ore is about 75 to 85%, preferably 80% or more, more preferably 90% or more.

  In the present invention, this strength level is particularly determined in consideration of the concentration of carbon dioxide in the sintered raw material, the supply amount, the supply position, and the supply range of the diluted gas fuel 24 (under the condition that the amount of heat input is constant). ) By adjusting the above, it can be achieved inexpensively. On the other hand, the improvement of the cold strength of sintered ore may lead to an increase in ventilation resistance and a decrease in productivity. In the present invention, such problems are also controlled by controlling the maximum temperature and holding time in the high temperature range. In order to solve this problem, the cold strength of the sintered ore is improved. In addition, the cold strength SI value of the sintered ore manufactured by the real machine sintering machine shows a value 10-15% higher than the value obtained by a pan test.

  In the production method of the present invention, the introduction position of the diluted gas fuel 24 into the charging layer 9 in the pallet traveling direction is in an arbitrary zone between the sintered cake formed in the charging layer 9 and the wet zone. Based on how the cold strength of sintered ore is made. For this control, in the present invention, the scale (size), number, position (distance from the ignition furnace), gas concentration of the gaseous fuel injection device, preferably the amount of carbonaceous material (solid fuel) in the sintered raw material By adjusting according to the above, not only the size of the combustion / melting zone (the thickness in the vertical direction and the width in the pallet traveling direction) but also the high temperature reached temperature and the high temperature range holding time are controlled. The strength of the sintered cake formed in the charging layer 9 is controlled.

Table 4 below shows the lower limit concentration of combustion of various gaseous fuels and the upper limit concentration of injecting the gaseous fuel (75%, 60%, 25% of the lower limit concentration of combustion).
For example, since propane gas has a lower combustion limit concentration of 2.2 vol%, the gas concentration upper limit diluted to 75% is 1.7 vol%, and the gas concentration upper limit diluted to 60% is 1.3 vol%, diluted to 25%. The gas concentration used is 0.6 vol%. Accordingly, the preferred range is as follows. Note that the lower limit of the diluted gas concentration, that is, the lower limit concentration at which the effect of supplying gaseous fuel is manifested is 0.05 vol% in the case of propane gas.

Preferred range (1): 2.2 vol% to 0.05 vol%
Preferred range (2): 1.7 vol% to 0.05 vol%
Preferred range (3): 1.3 vol% to 0.05 vol%
Preferred range (4): 0.6 vol% to 0.05 vol%
In addition, since the lower limit concentration of combustion for C gas is 5.0 vol%, the upper limit of gas concentration diluted to 75% is 3.8 vol%, and the upper limit of gas concentration diluted to 60% is 3.0 vol%, diluted to 25%. The gas concentration used is 1.3 vol%. Accordingly, the preferred range is as follows. In the case of C gas, the lower limit concentration at which the effect of supplying gaseous fuel is manifested is 0.24 vol%.

Preferred range (1): 5.0 vol% to 0.24 vol%
Preferred range (2): 3.8 vol% to 0.24 vol%
Preferred range (3): 3.0 vol% to 0.24 vol%
Preferred range (4): 1.3 vol% to 0.24 vol%
LNG gas has a combustion lower limit concentration of 4.8 vol%, so the upper limit of gas concentration diluted to 75% is 3.6 vol%, and the upper limit of gas concentration diluted to 60% is 2.9 vol%, diluted to 25%. The gas concentration is 1.2 vol%. Accordingly, the preferred range is as follows. The lower limit concentration at which the effect of supplying the gaseous fuel of LNG gas is 0.1 vol%.

Preferred range (1): 4.8 vol% to 0.1 vol%
Preferred range (2): 3.6 vol% to 0.1 vol%
Preferred range (3): 2.9 vol% to 0.1 vol%
Preferred range (4): 1.2 vol% to 0.1 vol%
In addition, the blast furnace gas has a combustion lower limit concentration of 40.0 vol%, so the upper limit of gas concentration diluted to 75% is 30.0 vol%, and the upper limit of gas concentration diluted to 60% is 24.0 vol%, diluted to 25%. The gas concentration used is 10.0 vol%. Accordingly, the preferred range is as follows. Note that the lower limit concentration at which the effect of supplying the gaseous fuel of the blast furnace gas is 0.24 vol%.

Preferred range (1): 40.0 vol% to 1.25 vol%
Preferred range (2): 30.0 vol% to 1.25 vol%
Preferred range (3): 24.0 vol% to 1.25 vol%
Preferred range (4): 10.0 vol% to 1.25 vol%

  Also, in the vicinity of the sidewall 18 in the width direction perpendicular to the conveying direction of the sintering machine pallet 8, the gaseous fuel supplied from the gaseous fuel injection nozzle 23 is blown by the influence of the crosswind as described above. As a result, the concentration of the diluted gas fuel may increase or it may leak to the outside. Also, when the suction from the charging layer becomes non-uniform, the concentration of the diluted gas fuel may change, the concentration may increase, or it may leak outside.

For this reason, in this embodiment, LNG is adopted as the gaseous fuel, and the main component of the LNG is methane CH ₄ as shown in Table 1 described above. Therefore, the concentration of the methane CH ₄ is detected. The methane concentration detector 50 was placed in the gas supply hood 16 as appropriate, and the concentration diffusion distribution of methane CH ₄ was measured. In this case, seven gas fuel supply pipes 21 are arranged in parallel at a predetermined interval in the width direction orthogonal to the conveying direction of the sintering machine pallet 8 in the gas supply hood 16. These gaseous fuel supply pipes 21 are disposed at a height of 500 mm from the surface of the charging layer 9.

  The arrangement of the methane concentration detector 50 in this case is, for example, a height of 155 mm from the upper surface of the charging layer 9 of the gas supply hood 16 in the horizontal direction, as indicated by the ● marks in FIGS. 8A and 8B. Nine points are arranged diagonally at the position, and 13 points are arranged in the central portion of the gas supply hood 16 in the vertical direction as shown in FIG. The measurement was performed with the methane concentration detector 50 placed at the position indicated by the ○ where hatching is highly likely to leak to the outside air.

In a state where a large number of methane concentration detectors 50 are arranged as described above, the flow rates are 266 Nm ³ / h (8000 ppm) and 166 Nm ³ / h (4000 ppm) from each of the gaseous fuel injection nozzles 23 of the seven gaseous fuel supply pipes 21. Then, LNG was sprayed in the horizontal direction and introduced into the charging layer 9 for sintering. Distribution of methane CH ₄ concentration from the center of the gas supply hood 16 to the end portion in the width direction perpendicular to the transport direction of the sintering machine pallet 8 at the height position of 155mm from the surface of the sintering bed 9 at this time, FIG. As shown in FIG. 9, between the center of the hood and 1.5 m, the LNG flow rate is 266 Nm ³ / h (8000 ppm) and the flow rate is 133 Nm ³ / h (4000 ppm). A similar increasing tendency is shown toward the end in the width direction perpendicular to the conveyance direction of the machine pallet 8, but when the flow rate exceeds 1.5 m from the hood center, the flow rate is 270 Nm ³ / h and the flow rate is 135 Nm ³ / h. state that methane CH ₄ concentration compared steeply increases methane CH ₄ concentration in the case of was observed. According to the measurement result of FIG. 9, the distance from the middle of the gas supply hood 16 is far from the lower side of the gaseous fuel injection nozzle 23 to the surface of the charging layer 9, and the closer to the hood wall, the higher the methane CH ₄ concentration. It was confirmed that there were portions where the methane CH ₄ concentration was high (over the lower combustion limit concentration of 1/3) at the four corners.

It was also confirmed that the CH ₄ concentration sometimes reached 4% at the hood edge (inside the hood wall). The combustion lower limit concentration of LNG containing CH ₄ is 4.8%, which indicates that it is approaching the dangerous area.
In the gas fuel supply of the present invention, in order to ensure safety such as fire accidents, and to burn the gas fuel diluted in the charging layer during the sintering process, the gas fuel has a combustion lower limit concentration of 75% or less. A gaseous fuel diluted to a concentration is supplied to the charging layer. A preferred concentration is 1/3, preferably 1/4 or less, of the lower combustion limit concentration of gaseous fuel.

Therefore, when the CH ₄ concentration reaches a concentration exceeding 75% of the lower combustion limit concentration of the gaseous fuel before reaching 4%, the blowing of the gaseous fuel is stopped and the sintering machine is stopped to perform sintering. The operation was interrupted.
That is, the lower combustion limit concentration of LNG is 4.8%, and 75% of the lower combustion limit concentration corresponds to 3.6%. Before the CH ₄ concentration, which is an example of this concentration, reached 4%, it was necessary to stop blowing the gaseous fuel and stop the sintering machine to interrupt the sintering operation. In the present invention, the following method is carried out as means for continuing the sintering operation in order to cause unevenness due to the interruption of the sintering operation and the resumption of the sintering operation in the quality of the sintered ore obtained when the operation is interrupted frequently.

In the following description, the present invention will be described with reference to a diluted gas fuel supply example in which the upper limit is 1/3 or less of the lower limit concentration of gaseous fuel, or 1/4 or less.
First, when a concentration exceeding 1/3 of the lower limit of combustion of gaseous fuel in the hood or exceeding 1/4 is detected, the stagnant gas in the hood is agitated to eliminate CH ₄ concentration uneven distribution. is there. That is, the sintering operation is continued while stirring the atmosphere in the hood. If the measured CH ₄ concentration falls within the set concentration, the stirring is stopped and the diluted gas fuel supply sintering operation is performed.

Therefore, between the gas fuel supply pipe 21 and the baffle plate row 20 in the gas supply hood 16 so that the methane CH ₄ concentration in the high concentration portion becomes 1/3 or less of the lower limit combustion concentration (4.8%), As shown in FIG. 3, stirring fans 51 as stirring mechanisms are arranged in line symmetry from the center in the width direction, and the diluted gas fuel 24 is blown out toward the end in the width direction and stirred.
For this reason, as shown in FIG. 10, between the fuel injection nozzle 23 and the surface of the charging layer 9 at the four corners of the gas supply hood 16 in each of the heat insulation furnace 12 and the gas fuel supply device 15 during the actual sintering operation. The reference numeral 52a is arranged in the methane CH ₄ analyzer 52 as a concentration abnormality detection unit that measures at least the methane CH ₄ concentration represented by the mark ● at the four locations. Further, in order to further enhance safety, an analyzer 52b for measuring the methane CH ₄ concentration represented by the mark ● is preferably arranged at the middle part of the four corners.

The detection signals of the methane CH ₄ analyzer 52 is input as shown in FIG. 11, for example constituted a control device 55 by a microcomputer. The control device 55 is connected to a drive circuit 56 of the stirring fan 51 disposed in the gas supply hood 16 on the output side thereof. As shown in FIG. 12, the control device 55 executes a stirring control process. In this agitation control process, first, each detection signal of each methane CH ₄ analyzer 52 is read in step S 1, and then the process proceeds to step S 2, where the methane CH ₄ concentration in the detection signal of the methane CH ₄ analyzer 52 is read. there (in this embodiment, described in example in which 1/3 of the lower flammable limit concentration set value) 1/3 of lower flammable limit concentration determined whether the detection signal exceeding the exists, methane CH ₄ If there is a methane CH ₄ analyzer 52 having a concentration exceeding the lower combustion limit concentration of 1/3, the process proceeds to step S3, and the control signal SC for rotationally driving each stirring fan 51 is sent to the stirring fan drive circuit. Then, the process returns to step S1.

When the detection result of each methane CH ₄ analyzer 52 indicates that the methane CH ₄ concentration indicates 1/3 or less of the lower combustion limit concentration, the process proceeds to step S4 and the stirring fan 51 is detected. After the control signal SC for stopping the rotation of the motor is output to the stirring fan drive circuit 56, the process returns to step S1.

Next, the operation of the above embodiment will be described.
First, as shown in FIG. 1, the granulated ore from the floor hopper 4 is cut out to form a floor layer on the great of the sintering machine pallet 8, and the surge hopper 5 to the drum feeder are formed on the floor layer. The sintered raw material quantitatively cut out in 6 is charged to form a charging layer 9 of about 400 to 800 mm, which is also called a sintering bed.
Then, as the sintering machine pallet 8 is conveyed, the carbonaceous material in the surface layer of the charging layer 9 moved under the ignition furnace 10 is ignited.

  In the charged layer 9 after ignition, the combustion (flame) front gradually moves downward and forward (downstream) as the sintering machine pallet 8 moves with the heating in the secondary furnace 12 and the heat retaining furnace 13. While expanding, the position of the combustion / melting zone changes as shown in FIG. Then, when the position of the combustion / melting zone reaches about 20 mm from the surface layer that shifts from the upper layer to the middle layer, the sintering machine pallet 8 reaches the position of the first gaseous fuel supply device 15.

In this gaseous fuel supply device 15, LNG is injected by the gaseous fuel injection nozzle 23 in the hood 16 that covers the upper side of the sintering machine pallet 8.
At this time, as shown in FIG. 4, the gaseous fuel injection nozzle 23 is arranged with a half-pitch shift in the conveying direction of the sintering pallet 8 so that the adjacent spray mechanisms 23 do not face each other. Therefore, a uniform injection region is formed in the conveying direction of the sintering machine pallet 8 without the LNG injected from the gaseous fuel injection nozzles 23 in the adjacent set interfering with each other.

The injected gaseous fuel is mixed with air turbulently flowed by the baffle plate 19 and diluted below the lower combustion limit concentration at room temperature, and combustion above the charging layer 9 can be suppressed.
The diluted gaseous fuel 24 injected from the gaseous fuel injection nozzle 23 and diluted with air sucks the air downward through the wind box 11 disposed on the lower side of the sintering machine pallet 8, thereby mounting the diluted gaseous fuel 24. It is introduced into the entrance layer 9.

  The diluted gas fuel 29 introduced into the charging layer 9 passes through the sintered cake generated in the surface layer portion, reaches the combustion / melting zone 20 mm or more below the surface, and is burned in this combustion / molten layer. The For this reason, the high temperature region holding time is originally short and heat is likely to be insufficient, and the high temperature region holding time for maintaining the upper and middle layer regions where the cold strength of the sintered ore is low at a high temperature region of 1200 ° C. or higher can be increased. The cold strength of the ore can be improved. Accordingly, it is possible to improve the yield of the upper and middle layer portions with a low yield shown in FIG. 17C when the diluted gas fuel 24 is not injected.

  In this way, when the supply operation of the diluted gas fuel 24 is extended to the region below the middle layer, the recombustion / melting zone by the dilution gas fuel 24 is formed on the combustion / melting zone by the original carbon material. Results in equal expansion and expansion of the combustion / melting zone in the vertical direction, so that it is possible to extend the holding time of the high temperature region without increasing the maximum temperature, so the moving speed of the sintering machine pallet 8 is reduced. Sufficient sintering can be realized without this. As a result, the quality of the sintered cake of the charging layer 9 as a whole (improvement of cold strength) is brought about, leading to improvement of the quality (cold strength) and productivity of the sintered ore.

When this sintering operation state is a normal sintering operation state that is not affected by crosswind or the like, the gas injected from the gas fuel injection nozzle 23 in the gas supply hood 16 of the heat insulation furnace 13 and each gas fuel supply device 15 The fuel is mixed with air supplied through the baffle plates 19 of the baffle plate row 20 so that the methane CH ₄ concentration is controlled to 1/3 or less of the lower combustion limit concentration, and proper sintering operation is performed. Yes.

For this reason, when the gaseous fuel supply control process of FIG. 12 is executed by the control device, the methane CH ₄ concentration detected by the methane CH ₄ analyzer 52 is 1/3 or less of the lower combustion limit concentration. The control signal SC for stopping the stirring fan 51 is output to the driving circuit 56 of each stirring fan by shifting from step S2 to step S4 in the stirring control process of FIG. The stirring fan 51 provided in the hood 16 is stopped from rotating, and the stirring function is stopped.

However, when the methane CH ₄ concentration detected by any of the methane CH ₄ analyzers 52 exceeds 1/3 of the lower combustion limit concentration, the process proceeds from step S2 to step S3 in the gaseous fuel supply control process of FIG. Then, by outputting a control signal SC for rotationally driving each stirring fan 51 of the corresponding gaseous fuel supply device 15 to the drive circuit 56, the diluted gaseous fuel 24 in the gas supply hood 16 is stirred, so that methane Disperse the dilute gaseous fuel in the high CH ₄ concentration region.

Therefore, it can be solved that the diluted gas fuel 24 in the gas supply hood 16 is uniformly dispersed and a high concentration region is generated, and safe operation can be ensured.
In the above embodiment, the case where the stirring fan 51 is provided in the gas supply hood 16 has been described. However, the present invention is not limited to this, and as shown in FIG. A plurality of agitation fans 51 having a wind speed of about 5 m / s are disposed in the gas supply hood 16 so that the discharge flow of the agitation fans 51 is introduced into the gas supply hood 16. 24 may be stirred.

In the above embodiment has been described for the case of operating in more than 1/3 of the lower flammable limit concentration of methane CH ₄ concentration, it is not limited thereto, methane CH ₄ concentration safety during operation Any density can be set as long as it can be taken into consideration.
Moreover, in the said embodiment, although the case where the heat retention furnace 13 was arrange | positioned downstream of the ignition furnace 10 and the secondary furnace 12 was demonstrated, it is not limited to this, the heat insulation furnace 13 is abbreviate | omitted, The present invention can also be applied to the case where the gaseous fuel supply device 15 is disposed at a predetermined distance on the downstream side of the furnace 10.

Moreover, in the said embodiment, although the case where it had the food | hood structure open | released in the upper part of the gas supply hood 16 of the gaseous fuel injection apparatus 15, it was not limited to this, The opening 17 was formed in the upper part It can also be set as the food | hood structure which has a roof part.
Further, in the above embodiment, the case where LNG is applied as the gaseous fuel has been described. However, the present invention is not limited to this, and other propane gas, hydrogen gas, methane gas, carbon monoxide gas (CO), coke oven, etc. Any of gas (C gas), blast furnace gas (B gas), blast furnace / coke oven mixed gas (M gas), city gas, or a mixed gas thereof can be applied. In this case, a densitometer corresponding to the gas fuel to be applied may be applied. When carbon dioxide, coke oven gas, or blast furnace gas is applied, carbon monoxide is included, so a CO detector is used as the leak detector 52. It is preferable to apply.

  The technique of the present invention is useful as a technique for producing sintered ore used as a raw material for iron making, particularly as a blast furnace, but can also be used as another ore agglomeration technique.

It is a schematic structure figure showing one embodiment of the present invention. It is a schematic block diagram of a gaseous fuel supply apparatus. It is sectional drawing of the direction orthogonal to the conveyance direction of a gaseous fuel supply apparatus. It is explanatory drawing which shows the gaseous fuel injection state of a gaseous fuel supply apparatus. It is a graph which shows the influence which the discharge speed of gaseous fuel and the nozzle diameter exert on the concentration distribution of diluted gaseous fuel. It is a figure explaining the experiment which investigates the influence of the gaseous fuel supply position to a sintering cake. It is a figure which shows the sealing mechanism of the sintering machine pallet conveyance direction of a gas supply hood. It is a diagram showing the arrangement of a density meter for measuring methane CH ₄ concentration distribution of the gas supply hood. From the hood center is a graph showing methane CH ₄ concentration distribution to the side edges. It is a schematic view showing the actual arrangement of methane CH ₄ analyzer. It is a block diagram which shows a control apparatus. It is a flowchart which shows an example of the stirring control processing procedure performed with a control apparatus. It is a schematic block diagram which shows other embodiment which has arrange | positioned the fan for stirring outside. It is a figure explaining the conventional sintering process. It is a figure explaining the pressure loss and temperature distribution in a sintered layer. It is explanatory drawing which compared the temperature distribution at the time of high production and low production. It is a graph of the temperature distribution and yield distribution in a sintering machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Raw material hopper 2 ... Drum mixer 3 ... Rotary kiln 4 ... Surge hopper 5 ... Floor hopper 6 ... Drum feeder 7 ... Cutting chute 8 ... Sinter pallet 9 ... Charging layer 10 ... Ignition furnace 11 ... Wind box 15 ... Gas fuel Injection device 16 ... hood,
19 ... baffle 20 ... baffle columns 21 ... gaseous fuel pipe 22 ... gas fuel supply source pipe 23 ... gas fuel injection nozzle 51 ... stirring fan 52 ... methane CH ₄ analyzer 55 ... controller 56 ... stirring fan drive circuit

Claims (6)

A raw material supply device for charging a sintered raw material containing fine ore and carbonaceous material on a circulating pallet to form a charging layer;
An ignition furnace for igniting the charcoal of the charging layer;
A wind box disposed below the pallet;
A gaseous fuel supply device disposed on the downstream side of the ignition furnace, injecting gaseous fuel into the atmosphere above the charging layer and mixing it with air to produce a diluted gaseous fuel having a lower combustion limit concentration or less. ,
The gaseous fuel supply device includes a plurality of gaseous fuel supply pipes that supply the gaseous fuel disposed in a gaseous supply hood, and a concentration abnormality that detects an abnormal concentration of diluted gaseous fuel disposed in the gaseous supply hood. A sintering machine comprising: a detection unit; and a stirring mechanism that stirs the diluted gas fuel in the gas supply hood based on the concentration abnormality detected by the concentration abnormality detection unit.   The sintering machine according to claim 1, wherein the concentration abnormality detection unit is disposed at least at a corner in the gas supply hood.   The sintering machine according to claim 1 or 2, wherein the concentration of the diluted gas fuel is set to 1/3 or less of the lower limit concentration of combustion.   The sintering machine according to any one of claims 1 to 3, wherein the stirring mechanism is disposed in the gas supply hood.   The sintering machine according to any one of claims 1 to 3, wherein the stirring mechanism is disposed outside the gas supply hood. A charging step of charging a sintered raw material including powdered ore and carbonaceous material on a circulating pallet and forming a charging layer of the sintered raw material on the pallet;
An ignition step of igniting the charcoal material on the surface of the charging layer using an ignition furnace;
A gaseous fuel supply step in which a gaseous fuel is jetted into the air above the charging layer in the gas supply hood to form a diluted gaseous fuel having a lower combustion limit concentration or less;
The diluted gas and air are sucked in a wind box arranged under the pallet and introduced into the charging layer, and the diluted gas fuel and the carbon material are burned in the charging layer to produce a sintered cake. A method of operating a sintered ore having a sintering step,
A concentration abnormality detection unit is disposed at a portion where the diluted gas fuel is likely to have a high concentration in the gas fuel supply step, and the dilution gas fuel in the gas supply hood is stirred when the concentration abnormality detection unit detects the concentration abnormality. A method for operating sintered ore.

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