JP2010133616A - 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 21 for supplying the gaseous fuel within a gas supply hood 16; gas abnormality detection parts 51-53 arranged in the gas supply hood 16 and detecting an abnormality of the diluent gaseous fuel; and a gaseous fuel supply control part 55 for restricting gaseous fuel supply amount with respect to each gaseous fuel supply pipe arrangement based on the gas abnormality detected by the gas abnormality detection parts. <P>COPYRIGHT: (C)2010,JPO&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. 17 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. 18 shows the temperature distribution in the charging layer at the time of 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.

  19A shows the progress of sintering in the charging layer on the sintering machine pallet, FIG. 19B 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. 19B, 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 and melting reaction (sintering reaction) becomes insufficient, and the strength of the sintered cake is lowered. Therefore, 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, there is a risk that the high temperature portion such as the cracked portion of the sintering bed or the sintered cake will become a fire, and the gas fuel may be backfired and the gas fuel may burn (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 the 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 abnormality detection unit for detecting an abnormality of the diluted gas fuel disposed in the gas supply hood, and a gas abnormality detection unit for each of the gas fuel supply pipes based on the gas abnormality detected by the gas abnormality detection unit. Gaseous fuel supply control to control gaseous fuel supply volume It is characterized by having and.

According to a second aspect of the present invention, there is provided the sintering machine according to the first aspect, wherein the gas abnormality detection unit is disposed at least at a corner in the gas supply hood, and the diluted gas fuel concentration, the diluted gas fuel is provided. It is configured to detect at least one of a specific component and a flame contained in.
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 a plurality of the gaseous fuel supply pipes are maintained at a predetermined interval in a direction orthogonal to the conveying direction of the pallet. A plurality of the gas abnormality detection units are arranged in a direction perpendicular to the hood corners in the gas supply hood and the conveyance direction of the pallet, and the gas fuel supply control unit detects a gas abnormality. The gas fuel supply pipe in the vicinity of the gas abnormality detection unit is configured to limit a gas fuel flow rate.

Further, the sintering machine according to claim 5 is the invention according to claim 4, wherein the gaseous fuel supply control unit supplies gas from the gaseous fuel supply pipe in the vicinity of the abnormal gas detector that detects an abnormal gas. It is characterized by being comprised so that it may stop.
A sintering machine according to claim 6 is the invention according to any one of claims 1 to 5, wherein the gas abnormality detector is at least a gas concentration detector, a gas specific component detector, or a flame detector. It is composed of one, when the gas concentration detector exceeds 1/3 of the lower limit concentration of combustion, when the specific gas detector detects a specific gas and when the flame detector detects a flame. It is characterized by determining that the operation is abnormal when detected.

According to a seventh aspect of the present invention, there is provided a method for operating a sintered ore, comprising charging a sintered raw material containing fine ore and a carbonaceous material on a circulating pallet to form a charged layer of the sintered raw material on the pallet. Charging process;
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 gaseous fuel is jetted into the air above the charging layer 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 gas abnormality detection unit is disposed at a portion where the diluted gas fuel in the gas fuel supply process is likely to have a high concentration, and the gas fuel supply in the gas fuel supply process is restricted when a gas abnormality is detected by the gas abnormality detection unit. It is characterized by doing.

  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. Gaseous fuel supply control when gas abnormality is detected in the gas supply hood by the gas abnormality detection unit when gaseous fuel is mixed with air and introduced into the charging layer as diluted gaseous fuel below the lower combustion limit concentration The gas fuel supply amount in the gas fuel supply pipe near the part where the gas abnormality is detected in the unit is limited, so the concentration of diluted gas in the gas supply hood increases, the specific components contained in the gas fuel increase, the occurrence of flame, etc. When the gas abnormality occurs, by restricting the gaseous fuel in the gaseous fuel supply pipe in the vicinity thereof, it is possible to reliably prevent the abnormal 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 is surrounded by a gas supply hood 16 that surrounds the upper portion of the sintering machine pallet 8 so that gaseous fuel does not leak outside the gas supply hood 16. . The gas supply hood 16 extends upward from the front and rear walls 17a extending perpendicularly to the conveying direction of the sintering machine pallet 8, the left and right sidewalls 17b along the conveying direction of the sintering machine pallet 8, and the upper ends of the walls 17a and 17b. The hood portion 17c has a truncated quadrangular pyramid shape that becomes narrower as it goes, and an opening 17d having a relatively large area is formed above the hood portion 17c.

  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 its front and rear walls 17 a and having a vertex upward is orthogonal to the conveying direction of the sintering machine pallet 8. 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 gas supply hood 16 surrounding the upper portion of the sintering machine pallet 8 is provided. The gas supply 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 gas supply hood 16 is more effective than a screen as a measure against cross wind. However, as described above, the gas supply hood 16 has an opening 16a above or has an appropriate transmittance (void ratio), and it is necessary to have a structure capable of taking in air from this portion. .

Thereby, the coke oven gas injected from the gaseous fuel injection nozzle 23 and the atmosphere are mixed inside the gas supply hood 16.
Further, as shown in FIG. 3, a cross wind attenuating fence 16c made of punch metal or the like having a transmittance of about 30% is provided at the upper ends of the left and right sidewalls 17b along the conveying direction of the sintering machine pallet 8 of the gas supply hood 16. Is preferably provided.

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

  For this reason, between the lower end of the left and right side walls 18 along the conveying direction of the sintering machine pallet 8 of the gas supply hood 16 and the pallet side wall 8a, the lower surface of the branch injection part 27 of the spray mechanism 23, and the charging layer 9 Between the upper surface, as schematically shown 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. A cover 42 is provided to cover from above. 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 ends of the front and rear plate portions 16b of the gas supply 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, as shown in FIG. It is preferable to form an air curtain 44 by arranging an air passage 43 along the sixteen front and rear walls 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, The surface layer portion of the charging layer 9 has no fire type and the probability of backfire (ignition) is low. As shown in FIG. 20A, the thickness of the sintered cake increases as the sintering machine pallet 8 moves downstream from the ignition furnace 10, so that the charging layer 9 of the sintered cake is increased. 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. 20 (b), the thermal history received in the sintering process in the sintered layer is different in the upper layer, the middle layer, and the lower layer, and in the upper layer to the lower layer, the high temperature region holding time (about 1200 ° C. or higher). 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. In addition, when the suction from the charging layer becomes non-uniform, the concentration of the diluted gas fuel changes, which may increase the concentration or 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, 13 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 in the vertical direction, 13 points are arranged in the central portion of the opening 16a of the gas supply hood 16 as shown in FIG. 8B, and left and right along the conveying direction of the sintering machine pallet 8 Measurement was performed by placing the methane concentration detector 50 at a position indicated by a circle with hatching on the side surface that is highly likely to be leaked to the outside air by crosswind.

In the state where a large number of methane concentration detectors 50 are arranged as described above, the shutoff valves 25 of all 13 gaseous fuel supply pipes 21 are opened, and the flow rate is 200 Nm ³ / h (6000 ppm) from each gaseous fuel injection nozzle 23. LNG was sprayed in the horizontal direction and introduced into the charging layer 9 for sintering. At this time, the concentration distribution of methane CH ₄ in the vertical direction in the central portion of the gas supply hood 16 during the sintering operation is methane CH ₄ at a position of about 185 mm from the surface of the charging layer 9 as shown in FIG. ₄ Concentration is about 0.38%, methane CH ₄ is the largest at about 315 mm from the surface of the charging layer 9 at about 0.58%, and methane CH ₄ is about 600 mm or more from the surface of the charging layer 9 ₄ A state where the concentration was 0.05% or less was observed. According to the measurement result of FIG. 9, the methane CH ₄ concentration is low at a position higher than the position of the gaseous fuel injection nozzle 23 in the gaseous fuel supply pipe 21, and between the gaseous fuel injection nozzle 23 and the surface of the charging layer 9. Since the methane CH ₄ concentration was high, there was no external methane outflow, and it was considered that the hood height and the shape and arrangement of the baffle plate 19 were 10 parts in the initial conditions.

On the other hand, the distribution of methane CH ₄ concentration from the center of the gas supply hood 16 at the height of 155 mm from the surface of the charging layer 9 to the end in the width direction orthogonal to the conveying direction of the sintering machine pallet 8 is shown in FIG. As shown in FIG. 4, the number of gaseous fuel pipes 21 for supplying LNG is conveyed from the center of the gas supply hood 16 to the center of the gas supply hood 16 for each of four patterns of 3, 5, 7, and 13 closer to the center. The situation of gradually increasing toward the end in the width direction orthogonal to the direction is measured, and the methane CH ₄ concentration at the hood end increases as the sintering operation continues. According to the measurement result of FIG. 10, the center of the gas supply hood 16 is low between the lower side of the gaseous fuel injection nozzle 23 and the surface of the charging layer 9 (it is a set dilution concentration of the blown gaseous fuel). This is a phenomenon in which the concentration of methane CH ₄ increases on the wall side of the gas supply hood 16 that is the end in the width direction of the knot. Further, it was confirmed that this high concentration was particularly high at the four corners of the gas supply hood 16. In the sintering operation with 13 gas fuel supply pipes (with nozzles) in the width direction, it is confirmed that the methane CH ₄ concentration sometimes reaches 4% on the wall side of the gas supply hood 16 as shown in FIG. did it. 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. The gas supply hood 16 is an enclosure for preventing the diluted gaseous fuel from leaking to the outside. When the gas supply hood 16 reaches a concentration exceeding 75% of the lower combustion limit concentration of the gaseous fuel observed (monitored) in FIG. The fuel injection was stopped and the sintering machine was stopped to interrupt the sintering operation. For example, the lower combustion limit concentration of LNG is 4.8%, and 75% of the lower combustion limit concentration corresponds to 3.6%. In FIG. 10, the concentration distribution was obtained and measured in order to measure the concentration reached, but before the CH ₄ concentration as an example of this concentration reached 4%, the gas fuel injection was stopped and the sintering machine was stopped to sinter The operation had to be interrupted. 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 lower than 1/3 or less than 1/4 of the lower limit concentration of gaseous fuel in the hood is detected, the number of gaseous fuel supply pipes 21 that supply LNG is reduced. . As shown in FIG. 10, if the number of gas fuel supply pipes 21 is adjusted and the number of used gas is 13 → 7 → 5 → 3, the CH ₄ concentration is 4% for 13 used. However, by setting the number of use to 7, the CH ₄ concentration is 2.3% (48% of the lower limit of combustion), and when the number of use is 5, the CH ₄ concentration is 1.4% (lower limit of combustion). (29% of the concentration) By making the number of use three, it is possible to adjust the CH ₄ concentration to 0.7% (14.6% of the lower limit concentration of combustion). This adjustment to reduce the number of used lines may be a process of gradually reducing the number of used lines in stages. If the measured CH ₄ concentration is within the set concentration, the number of gaseous fuel supply pipes 21 used is increased and restored.

For this reason, in the CH ₄ concentration measurement of the present invention, as shown in FIGS. 11A and 11B, the gas supply hood 16 in each of the heat retaining furnace 12 and the gaseous fuel supply device 15 during the actual sintering operation is used. A methane CH ₄ analyzer 51 represented by a mark ● is arranged at four locations between the fuel injection nozzle 23 and the surface of the charging layer 9 at the four corners of the circle. For safety, a methane CH ₄ analyzer 51 serving as a gas concentration detector for measuring the methane CH ₄ concentration represented by the mark ● is arranged at a total of 8 locations on the upper side of the hood. The methane CH ₄ analyzer 51 on the upper side of the hood is a safety measure for leak detection. Further, as shown in FIG. 11 (a) and (b) 12 and, respectively in total 14 units leakage concentration of methane CH ₄ in the central portion of the four corners of the outer and the opening 16a of the gas fuel supply apparatus 15 For example, a leak detector 52 as a specific component detector configured by a methane CH ₄ detector that detects exceeding 50 ppm is disposed. Further, as shown in FIGS. 11A and 11B and FIG. 13, a total of 16 ignition detectors 53 are arranged in each of the heat insulation furnace 13 and each gaseous fuel supply device 15. As shown in FIG. 13, these ignition detectors 53 have a range in which the ignition detection range is a range in which a bell-shaped upper portion 55 is added to a fan-shaped portion 54 having an opening angle of approximately 90 degrees as shown by a broken line, and the length of the longest portion is 6 m. Therefore, the ignition detection range can cover the entire gas fuel hood 16 by arranging a total of four units at the downstream corners of the gas supply hood 16 and at both sides of the upstream side of the gas supply hood 16. Here, the methane CH ₄ analyzer 51, the leak detector 52, and the ignition detector 53 constitute a gas abnormality detector. The ignition detector 53 is for detecting whether or not the gaseous fuel injected from the gaseous fuel injection nozzle 23 of the gaseous fuel supply pipe 21 is ignited by backfire or the like.

Then, as shown in FIG. 14, the detection signals of each methane CH ₄ analyzer 51, leak detector 52 and ignition detector 53 are input to a control device 55 as a gaseous fuel supply control unit composed of, for example, a microcomputer. ing. The control device 55 is connected at its output side to a shutoff valve 25 inserted in a connecting portion between the gaseous fuel supply pipe 21 and the gaseous fuel supply source pipe 22, and a shutoff valve control signal for controlling the shutoff valve 25 is received. Is output. As shown in FIG. 15, the control device 55 executes a gaseous fuel supply control process. In this gaseous fuel supply control process, first, in step S1, the detection signals of the methane CH ₄ analyzer 51, the leak detector 52, and the ignition detector 53 are read, and then the process proceeds to step S2 where the ignition detector 53 is read. It is determined whether any one of the detection signals detects an ignition state, and when the ignition state is detected, the process proceeds to step S3 and is disposed in the gaseous fuel hood 16 that has detected the ignition state. After the control signal SC in the on state for controlling all the shutoff valves 25 to the closed state is output, the gaseous fuel control process is terminated.

  On the other hand, when the determination result of step S2 shows that the ignition state is not detected by all the ignition detectors 53, the process proceeds to step S4, and it is determined whether any of the leakage detectors 52 detects the leakage state. When any one of the leak detectors 52 detects a leak state, the process proceeds to step S5, and all the shutoff valves 25 provided in the gas supply hood 16 in the vicinity of the leak detector 52 that has detected the leak state. The gaseous fuel control process is terminated after outputting the on-state control signal SC for controlling the closed state to the closed state.

Moreover, when the determination result of step S4 has not detected the leak state in all the leak detectors 52, the process proceeds to step S6, and the methane CH ₄ concentration in the detection signal of the methane CH ₄ analyzer 51 is the lower combustion limit concentration. Therefore, it is determined whether or not there is a detection signal exceeding 1/3 (in this embodiment, the set value is set to the combustion lower limit concentration 1/3), and the methane CH ₄ concentration is set to the combustion lower limit concentration 1/3. If there is an excess methane CH ₄ analyzer 51, the process proceeds to step S 7, and the shutoff valve 25 of the gas supply pipe 21 that supplies the LNG closest to the corresponding methane CH ₄ analyzer 51 is closed. After outputting the on-state control signal SC to be in a state, the process returns to step S1.

Further, when the determination result of step S6 indicates that the detection signal of each methane CH ₄ analyzer 51 indicates that the methane CH ₄ concentration is 1/3 or less of the lower combustion limit concentration, the process directly 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. 19C 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 the 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 leakage or ignition to the outside occurs. There is no.

For this reason, when the gaseous fuel supply control process of FIG. 15 is executed by the control device, the ignition state is not detected by the ignition detector 53, the leakage state is not detected by the leakage detector 52, and further, methane CH ₄ analysis is performed. Since the methane CH ₄ concentration detected by the total 51 is 1/3 or less of the lower combustion limit concentration, the shutoff valves 25 inserted in all the gas fuel supply pipes 21 of the heat insulation furnace 13 and each gas fuel supply device 15 are provided. LNG is injected from a gaseous fuel injection nozzle 23 provided in each gaseous fuel supply pipe 21 under the open state, and this is mixed with air to become a diluted gaseous fuel 24. The diluted gaseous fuel 24 is sucked into the wind box 11 Thus, it can be introduced into the charging layer 9 to widen the sintering / combustion zone and extend the holding time of the high temperature region.

  However, normally, the diluted gas fuel 24 is formed in a state where a sintered cake is formed on the surface layer portion of the charging layer 9 and the sintering / combustion zone is 30 mm, preferably 50 mm below the surface of the charging layer 9. Since it is introduced into the charging layer 9, there is no fire on the upper surface of the charging layer 9, and the diluted gas fuel 24 does not burn, but for some reason the diluted gas fuel 24 is located above the charging layer 9. This is detected by the ignition detector 53.

  Therefore, in the gaseous fuel supply control process of the control device 55, the process moves from step S2 to step S3, and the inside of the gas supply hood 16 of the gaseous fuel supply device 15 in which the ignition detector 53 in which the ignition is detected is disposed. The control signal SC which closes the shut-off valves 25 provided in all the combustion supply pipes 21 is output, and all the shut-off valves 25 in the corresponding gas supply hood 16 are closed, so that the gas fuel The supply of LNG to the pipe 21 is stopped, and the injection of LNG from each gaseous fuel injection nozzle 23 is stopped. For this reason, the combustion of the diluted gas fuel 24 is immediately stopped.

Similarly, when diluted gas fuel leaks to the outside due to the influence of crosswind or the like, all of the insulated furnace 12 or each of the gaseous fuel supply devices 15 in which the leak has occurred are detected by the leak detector 52. The shutoff valve 25 provided in the gaseous fuel supply pipe 21 is controlled to be closed, and the leakage of diluted gaseous fuel and other components is immediately stopped.
Further, when the methane CH ₄ concentration detected by the methane CH ₄ analyzer 51 exceeds 1/3 of the lower combustion limit concentration, the process proceeds from step S6 to step S7 in the gaseous fuel supply control process of FIG. The shutoff valve 25 of the gaseous fuel supply pipe 21 to which the LMG closest to the methane CH ₄ analyzer 51 that has detected the methane CH ₄ concentration exceeding 1/3 of the lower combustion limit concentration is controlled to be closed.

Even when the supply of LNG to the closest gaseous fuel supply pipe 21 in the supply state of LNG is stopped in this way, if the methane CH ₄ concentration still exceeds 1/3 of the lower combustion limit concentration, again The process proceeds from step S6 to step S7, and the shutoff valve 25 of the gaseous fuel supply pipe 21 to which the LNG adjacent to the gaseous fuel supply pipe 21 to which the supply of LNG was previously stopped is supplied is controlled to be closed.

When the methane CH ₄ concentration detected by the methane CH ₄ analyzer 51 returns to 1/3 or less of the lower combustion limit concentration due to the LNG supply stoppage of the gaseous fuel supply piping 21, the LNG supply of the gaseous fuel supply piping 21 is further increased. The stop process is terminated.
Thus, according to the above embodiment, when the methane CH ₄ concentration by the injection of the diluted gas fuel 24 exceeds 1/3 of the lower combustion limit concentration, the supply of the gaseous fuel is stopped in order from the nearest gaseous fuel supply pipe 21. Therefore, the rise of the methane CH ₄ concentration exceeding 1/3 of the lower combustion limit concentration can be reliably suppressed, and a safe sintering operation can be ensured. Moreover, since the leak detector 52 is disposed, it is possible to reliably prevent the occurrence of gas poisoning (oxygen deficiency, CO poisoning, unpleasant feeling due to odor) in the heat retaining furnace 13 and the gaseous fuel supply device 15. Furthermore, since the ignition detector 53 is arranged in the gas supply hood 16, it is possible to reliably detect the occurrence of a flame at the gaseous fuel injection nozzle 23 and prevent the occurrence of a fire.

In the above embodiment, when the methane CH ₄ concentration exceeds 1/3 of the lower combustion limit concentration in the gaseous fuel supply control process, the closest gaseous fuel supply pipe is supplied with the gaseous fuel. However, the present invention is not limited to this, and the flow rate control valve is provided in the gaseous fuel supply pipe 21 to supply the gaseous fuel supply flow rate. Furthermore, if the number of the gaseous fuel supply pipes 21 for stopping the supply of the gaseous fuel is, for example, 13 gaseous fuel supply pipes 21, the number of the central part in the first stage is 7 If the methane CH ₄ concentration still exceeds 1/3 of the lower limit of combustion, the gaseous fuel is supplied only at the central five in the second stage. Three in the center as a stage However, if the methane CH ₄ concentration still exceeds 1/3 of the lower combustion limit concentration, the supply of the gaseous fuel to all the gaseous fuel supply pipes 21 may be stopped. .

Moreover, in the said embodiment, although the case where the cutoff valve was arrange | positioned in the connection part with the gaseous fuel supply source piping 22 of the gaseous fuel supply piping 21 was demonstrated, it is not limited to this, The gaseous fuel supply piping 21 A shutoff valve and a flow control valve may be arranged between the gas fuel injection nozzle 23 and the gas fuel injection nozzle 23, and these may be controlled by the control device 55.
Further, in the above embodiment, methane CH ₄ concentration was described for the case of maintaining the gaseous fuel supply number of the gaseous fuel supply pipe 21 in a condition that the following 1/3 of the lower flammable limit concentration, are limited to Instead, when the gaseous fuel stop process is performed, every time a predetermined time elapses, the gas fuel supply pipe 21 is stopped when the methane CH ₄ concentration continues to be 1/3 or less of the lower combustion limit concentration. The gaseous fuel supply may be started sequentially.

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 was set as the hood which formed the opening 16a in the upper part of the gas supply hood 16 of the gaseous fuel injection apparatus 15, it is not limited to this, An upper end is completely open | released It is also possible to apply the hood.
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.

In the embodiment described above, methane CH ₄ analyzer 51 has been described as being configured gas abnormality detector in leak detectors 52 and ignition detector 53, is not limited to this, at least the gaseous fuel It suffices if a concentration detector for detecting the concentration of the above is provided.

  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. Is a graph showing methane CH ₄ concentration distribution in the vertical direction of the hood center portion. From the hood center is a graph showing methane CH ₄ concentration distribution to the side edges. Actual methane CH ₄ spectrometer leak detectors, a diagram showing the disposition of an ignition detector, (a) is a plan view, (b) a side view. It is a schematic diagram which shows the arrangement | positioning condition of a leak detector. It is a schematic diagram which shows the arrangement | positioning condition and detection area | region of an ignition detector. It is a block diagram which shows a control apparatus. It is a flowchart which shows an example of the gaseous fuel supply control processing procedure performed with a control apparatus. 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 ... Gas supply hood 19 ... Baffle plate 20 ... Baffle plate row 21 ... Gas fuel pipe 22 ... Gas fuel supply source pipe 23 ... Gas fuel injection nozzle 25 ... Shut-off valve 51 ... Methane CH ₄ analyzer 52 ... Leak detector 53 ... Ignition detector 55 ... Control device

Claims (7)

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 gas fuel supply device includes a plurality of gas fuel supply pipes for supplying the gas fuel disposed in a gas supply hood, and a gas abnormality detection for detecting an abnormality in the diluted gas fuel disposed in the gas supply hood. And a gas fuel supply control unit that limits a gas fuel supply amount for each of the gas fuel supply pipes based on a gas abnormality detected by the gas abnormality detection unit.   The gas abnormality detection unit is disposed at least at a corner in the gas supply hood, and is configured to detect at least one of a diluted gas fuel concentration, a specific component contained in the diluted gas fuel, and a flame. The sintering machine according to claim 1, wherein:   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.   A plurality of the gaseous fuel supply pipes are disposed at a predetermined interval in a direction orthogonal to the conveying direction of the pallet, and the gas abnormality detecting unit includes a hood corner in the gas supplying hood and a conveying direction of the pallet. A plurality of gas fuel supply control units are arranged in a direction orthogonal to each other, and the gas fuel supply control unit is configured to limit the gas fuel flow rate of the gas fuel supply pipe in the vicinity of the gas abnormality detection unit that detects the gas abnormality. The sintering machine according to any one of claims 1 to 3, wherein:   The said gaseous fuel supply control part is comprised so that the gas supply from the said gaseous fuel supply piping of the vicinity of the said gas abnormality detector which detected gas abnormality may be stopped. Sintering machine.   The gas abnormality detector is composed of at least one of a gas concentration detector, a gas specific component detector, and a flame detector, and when the diluted gas concentration exceeds 1/3 of the lower combustion limit concentration in the gas concentration detector. 6. The operation abnormality is determined when a specific gas is detected by the gas specific component detector and when a flame is detected by the flame detector. 6. Sintering machine. 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 gaseous fuel is jetted into the air above the charging layer 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 gas abnormality detection unit is disposed at a portion where the diluted gas fuel in the gas fuel supply process is likely to have a high concentration, and the gas fuel supply in the gas fuel supply process is restricted when a gas abnormality is detected by the gas abnormality detection unit. A method for operating a sintered ore characterized by:

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