JP2010047812A - Method for operating sintering machine for blowing dilute gaseous fuel, and the same machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the production of a high strength sintered ore by improving the ventilation of the upper part of charging layer and the whole charging layer in an operation of the downward sucking type sintering machine for introducing dilute gaseous fuel into the charging layer, and to provide the sintering machine for this target. <P>SOLUTION: In the operation of the sintering machine having the type for sucking the dilute gaseous fuel and the air having combustion lower limit concentration or lower into the charging layer of sintering raw materials from the upper part of the sintering machine; the operational method of the sintering machine for blowing the dilute gaseous fuel, is performed by arranging a ventilation-promotive cavity composed of holes or grooves on the surface layer part in the charging layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method of operating a downward suction type DL sintering machine, and more particularly to a method of operating a sintering machine for injecting diluted gas fuel and a sintering machine for injecting diluted gas fuel.

  A sintered ore which is a main raw material of a blast furnace is generally manufactured through a process as shown in FIG. The raw materials for the production of sintered ore include iron ore powder, recovered powder in steelworks, sintered ore sieving powder, CaO-containing auxiliary materials such as limestone and dolomite, granulation aids such as quick lime, coke powder and anthracite Is included. These raw materials are cut out from each of the hoppers 1. The cut out raw material is mixed and granulated with a drum mixer 2 or the like after adding an appropriate amount of water, and becomes a sintered raw material made of pseudo particles having an average diameter of 3.0 to 6.0 mm. This sintering raw material is charged on an endless type sintering machine pallet 8 from a surge hopper 4 and 5 arranged on the sintering machine through a drum feeder 6 and a cutting chute 7, and is also called a sintering bed. A sintered raw material charging layer (hereinafter also simply referred to as a charging layer) 9 is formed. The thickness (height) of the charging layer is about 400 to 800 mm. Thereafter, the ignition furnace 10 installed above the charging layer 9 ignites the carbon material in the surface layer portion of the charging layer 9, and air is supplied by the wind box 11 disposed under the pallet 8. By sucking downward, the carbonaceous material in the charging layer is sequentially combusted from above, and the sintering raw material is heated and melted by the combustion heat generated at this time to generate a sintered cake. The obtained sintered cake is then crushed and sized and recovered as a product sintered ore consisting of agglomerates of 5.0 mm or more.

  In the process, first, the surface of the charging layer 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.

  FIG. 2 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. In this case, the pressure loss distribution is about 60% when it comes from the wet zone and about 40% when it comes from the combustion / melt zone.

FIG. 3 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 is maintained 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. For high productivity, to increase the movement speed of the pallet, the high temperature zone holding time t ₂ is shorter than the t ₁ when 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.

  FIG. 4A shows the progress of sintering in the charging layer on the sintering machine pallet, FIG. 4B 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. 4B, 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 decreases as shown in FIG. There has been a problem of causing a decline in sex.

  In view of these problems, conventionally, a method for increasing the temperature of the upper portion of the charging layer has been proposed. For example, Patent Document 1 discloses a technique for injecting gaseous fuel onto a charging layer after ignition of the charging layer. However, this technique uses a high-concentration gas even if it is propane gas (LPG) or natural gas (LNG), although the type of gaseous fuel (flammable gas) is unknown. 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 the flammable gas is injected immediately after the ignition furnace, there is a high risk of causing a fire due to the combustion of the flammable gas, and this is a technique with little practicality, and has not yet been put into practical use.

  Further, in Patent Document 2, a hood is provided 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 or coke oven gas is passed through the hood immediately after the ignition furnace. It is disclosed to blow in position. However, since this technology has a high temperature exceeding 1380 ° C. in the sintered layer, it cannot enjoy the effect of coke oven gas blowing, and there is a risk that a combustible mixed gas may ignite and cause a fire. It has not been converted.

  Furthermore, Patent Document 3 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 because the flammable gas is blown in a state where a flame remains on the surface, and the width of the sintered band cannot be made sufficiently thick (less than about 15 mm). The effect of injecting sex gas cannot be fully expressed. 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 for increasing the temperature of the upper layer of the charging layer has reached a practical level, and the development of a combustible gas blowing technique that can be carried out has been desired.
Japanese Patent Laid-Open No. 48-18102 JP-A-55-18585 Japanese Patent Laid-Open No. 5-311257

  By the way, the quality of the sintered ore is determined by the maximum temperature reached during combustion, the high temperature region holding time, and the like. Therefore, it is important to control the maximum temperature reached and the high temperature region holding time. In this regard, the method described in Patent Document 1 is a technique for increasing the temperature of the upper part of the charging layer in the first half of the sintering means by burning gaseous fuel on the surface of the charging layer. However, in this method, the concentration of gaseous fuel is high, so the amount of air (oxygen) that supports combustion is insufficient, and there is a risk of reducing the combustion of the carbonaceous material (coke) of the sintering raw material. There is a problem that improvement cannot be achieved.

  Further, in the method described in Patent Document 2, a hood is disposed on the charging layer in order to increase the temperature inside the charging layer of the sintering raw material, and air and coke oven gas are mixed through the hood. This is a technique for blowing gas at a position immediately after the ignition furnace. However, if the mixed gas is blown with the coke ratio as it is, the high temperature retention time is extended and the maximum temperature is increased, so that a lot of vitreous low-strength minerals are generated and the mixed gas blowing effect cannot be enjoyed. . In addition, there is a risk that a combustible mixed gas may ignite and cause a fire, and it has not been put into practical use.

  Furthermore, since the method described in Patent Document 3 increases the amount of air (oxygen) and mixes a low-melting-point melt or carbonaceous material, the burning rate of combustible gas and coke increases, but the low-melting-point Since the melt and powder are blown together, there is a problem that the air permeability of the combustion air is lowered.

  On the other hand, the inventors have previously proposed a method for operating a sintering machine in which diluted gas fuel is injected into the sintering material charging layer in order to solve the above-described problems of the prior art (Japanese Patent Application No. 2006-295544). However, in this proposal, there is still a need for improvement in terms of a method of supplying heat to the upper part of the charged layer and an increase in the diluted gas fuel suction speed to the combustion zone in the charged layer.

  The object of the present invention is to improve the air permeability of the upper part of the charging layer and the entire charging layer in the operation of the lower suction type sintering machine that introduces the diluted gas fuel into the charging layer, and sinter with high strength. It is to be able to produce ore and to provide a sintering machine used for it.

  In order to achieve the above object, the present invention provides an operation of a sintering machine of the type in which diluted gas fuel and air having a lower combustion limit concentration or less are sucked into a charging layer of a sintering raw material from above the sintering machine. A method of operating a sintering machine for injecting diluted gas fuel is proposed, characterized in that a ventilation promoting depression made of a hole or a groove is provided in the surface layer portion of the charging layer.

  In the present invention, a charging step of charging a sintering raw material containing fine iron ore and carbonaceous material onto a circulating moving sintering machine pallet and forming a charging layer of the sintering raw material on the pallet; An ignition process in which an ignition furnace is used to ignite the carbon material on the surface of the bed, and a diluted gas fuel generation process in which a gaseous fuel is supplied into the air above the charging layer and diluted to obtain a diluted gaseous fuel having a concentration lower than the lower combustion limit concentration. The diluted gas fuel is sucked and introduced into the charging layer together with air by the suction force of the wind box disposed under the pallet, and the diluted gas fuel is combusted in the charging layer, and at the same time, the charging layer In the manufacturing method of the sintered ore through the combustion step of generating a sintered cake by burning the carbonaceous material in the charging layer by the air sucked and introduced together with the diluted gas fuel introduced into the inside It is a preferable solution to be applied .

  In the present invention, it is preferable that the ventilation promotion depression is provided on the surface of the sintered raw material charging layer by a depression device provided on the upstream side of the ignition furnace.

  The present invention also provides a pallet that circulates, a raw material supply device for forming a charging layer by charging a sintered raw material containing fine ore and carbonaceous material on the pallet, and charging the sintered raw material. In a sintering machine equipped with an ignition furnace for igniting the carbonaceous material in the layer and a window box below the pallet, a recessing device is arranged on the downstream side of the raw material supply device and on the upstream side of the ignition furnace This is a dilute gas fuel injection sintering machine.

  In the present invention, it is a preferable solving means that the indenting device comprises a disk in which a plurality of disks forming a plurality of grooves parallel to the method of progressing the sintering machine are arranged.

In the present invention, the diluted gas fuel is
(A) a combustible gas diluted to a concentration of 75% or less and 2% or more of the lower combustion limit concentration;
(B) The combustible gas diluted to a concentration of 60% or less and 2% or more of the lower combustion limit concentration,
(C) It is a combustible gas diluted to a concentration of 25% or less and 2% or more of the lower combustion limit concentration,
Is a preferred embodiment.

  The gaseous fuel in the method of the present invention is any one selected from blast furnace gas, coke oven gas, blast furnace / coke oven mixed gas, city gas, natural gas, methane gas, ethane gas, propane gas, and mixed gas thereof The flammable gas is used.

The gaseous fuel supply device installed in the sintering machine of the present invention,
(A) The combustible gas is introduced into the charging layer as a diluted gas fuel diluted to a concentration of 75% or less of the lower combustion limit concentration and 2% or more,
(B) The combustible gas is introduced into the charging layer as a diluted gas fuel diluted to a concentration of 60% or less of the lower combustion limit concentration and 2% or more,
(C) The combustible gas is introduced into the charging layer as a diluted gas fuel diluted to a concentration of 25% or less and 2% or more of the lower limit concentration of combustion,
It is characterized by.

  In the present invention, the gaseous fuel may be obtained by vaporizing a liquid fuel whose ignition temperature in a gaseous state is higher than the temperature of the surface layer of the sintered bed, and the liquid fuel includes alcohols, ethers, Petroleum and other hydrocarbon compounds are used.

  According to the present invention, in the operation of the downward suction type sintering machine, the gaseous fuel is discharged into the atmosphere above the charging layer and the diluted gaseous fuel diluted to a predetermined concentration is ventilated to the charging layer. By providing the depression, it becomes easy to introduce into the upper part of the charging layer and the inside of the charging layer, and it is possible to quickly burn at a target position in the charging layer. Therefore, due to insufficient combustion, not only the upper part of the charging layer where the cold strength of the sintered ore tends to be low, but also the combustion in the part below the middle part of the charging layer is assisted, thereby operating to increase the strength of the sinter. be able to. In addition, in the present invention, the reaction in the combustion / melting zone, for example, the thickness in the vertical direction of this zone can be increased without deteriorating the air permeability of the entire charging layer, and the resulting sintered cake Therefore, it is possible to manufacture a product sintered ore having a high cold strength while ensuring a high yield and high productivity. And if the sintering machine of this invention is used, the operation of such a sintering machine can be performed stably.

  The present invention is applied to a method for operating a sintering machine including a charging step, an ignition step, a diluted gas fuel generation step, and a combustion step. In this method, the charging step is a step of charging a sintered raw material containing fine ore and carbonaceous material onto a circulating pallet to form a charging layer of the sintered raw material on the pallet, The ignition step is a step of igniting the carbon material on the surface of the charging layer using an ignition furnace. The diluted gaseous fuel generation step is a step of supplying the diluted gaseous fuel into the air above the charging layer and diluting to obtain a diluted gaseous fuel below the lower combustion limit concentration, and the burning step is disposed under the pallet. The diluted gas fuel and air are sucked into the charging layer by the suction force of the generated wind box, and the diluted gas fuel is burned in the charging layer, and at the same time, by the air sucked into the charging layer, It is a step of burning the carbonaceous material in the charging layer, sintering the sintered raw material by the generated combustion heat, and generating a sintered cake, wherein the diluted gas fuel generation step and the combustion step are features in the present invention. It is.

  In the diluted gas fuel generation step, the gaseous fuel is discharged at high speed into the atmosphere on the upper side of the charging layer at the downstream side in the pallet traveling direction of the ignition furnace, and this is mixed with air to form a diluted gas having a lower combustion limit concentration or less. This is a step for sucking and introducing fuel into the charging layer, and the sintering machine of the present invention is characterized by having a gaseous fuel supply device for obtaining the diluted gaseous fuel.

  As the gaseous fuel supply device, for example, as shown in FIG. 5, a plurality of gaseous fuel supply pipes are arranged along the width direction of the pallet, and slits or openings for discharging gaseous fuel are provided in the pipes. Or having a structure in which nozzles are provided, or, as shown in FIG. 6, a plurality of gaseous fuel supply pipes are provided along the direction of travel of the pallet. However, it is preferable to have a structure in which a slit or an opening is provided or a nozzle is provided.

  Moreover, it is preferable that the said gaseous fuel supply apparatus can control supply_amount | feed_rate of gaseous fuel in a pallet width direction, for example by providing a flow control means in a gaseous fuel supply pipe, a nozzle, etc. In particular, in the vicinity of the side wall in the pallet width direction, there is a high risk that the gaseous fuel concentration will be dilute due to the influence of crosswinds and the supplied gaseous fuel will flow in the machine side direction or leak out of the machine. Therefore, it is preferable that a large amount of gaseous fuel can be supplied in the vicinity of the sidewall.

  Further, the gaseous fuel supply device causes the gaseous fuel to be discharged into the atmosphere at a high speed above the charging layer, thereby mixing with the surrounding air in a short time, and a concentration below the lower combustion limit concentration of the gaseous fuel. Then, the diluted gaseous fuel is introduced into the charging layer.

  The reason for diluting the gaseous fuel to a concentration below the lower combustion limit concentration is as follows. Table 1 shows the lower limit concentration of combustion, supply concentration, and the like of typical gaseous fuels used in the present invention. In order to prevent the occurrence of fire, the gas concentration when supplying gaseous fuel into the sintered raw material is safer as it is lower than the lower combustion limit concentration. In this respect, city gas has a lower combustion limit concentration that is similar to that of C gas (coke oven gas), but since the amount of heat is higher than that of C gas, the supply concentration can be lowered. Therefore, from the viewpoint of ensuring safety, city gas that can lower the supply concentration is superior to C gas. Moreover, as will be described later, city gas does not contain CO (carbon monoxide) harmful to the human body as a component, nor does it contain hydrogen.

  Table 2 shows the combustion components (hydrogen, CO, methane) contained in the gaseous fuel, the lower and upper combustion concentrations of these components, laminar flow, combustion speed during turbulent flow, and the like. In order to prevent the occurrence of fire during sintering, that is, to prevent the occurrence of fire due to gaseous fuel supplied during sintering, it is necessary to prevent backfire, but for that purpose, at least laminar combustion The gaseous fuel may be discharged at a speed higher than the speed, preferably higher than the turbulent combustion speed. For example, when methane, which is a main combustion component of city gas, is used as a gaseous fuel, there is no fear of backfire if it is discharged at a speed exceeding 3.7 m / s. On the other hand, since hydrogen gas has a higher turbulent combustion speed than CO and methane, it is necessary to discharge hydrogen gas at a higher speed in order to ensure safety. From this point, when comparing the gaseous fuel shown in Table 1, the city gas that does not contain the hydrogen component can slow down the discharge speed compared to the C gas containing 59 vol% of the hydrogen component. Is advantageous. Moreover, since city gas does not contain a CO component, it is safe without causing gas poisoning. Therefore, from the viewpoint of ensuring safety, it can be said that city gas has favorable characteristics when used as gaseous fuel. The same can be said for natural gas.

  Table 3 shows the results of evaluating the advantages and disadvantages of the type of supplying the gaseous fuel. In the table, direct top blowing means that gas fuel such as city gas or C gas is supplied (discharged) as it is, and is diluted to a predetermined concentration by entraining the surrounding atmosphere and sucked into the charging layer (introduced) The premixed blowing is a so-called pre-mixing method in which air and gaseous fuel are mixed in advance and diluted to a predetermined concentration and supplied to the charging layer and sucked (introduced) into the charging layer. Refers to the mix format. In the direct injection type, it is easy to prevent backfire if gaseous fuel is discharged at a speed higher than the turbulent combustion rate described above, but in the premixed injection type, when a concentration deviation occurs, backfire is caused. there is a possibility. On the other hand, in the direct-injection type, when the gaseous fuel is mixed with the surrounding atmosphere and diluted, concentration unevenness is likely to occur. Therefore, the possibility of abnormal combustion is greater than in the premixed injection type. However, in the case of comprehensive evaluation including equipment costs, direct injection of city gas is the most advantageous.

  In the present invention, the gaseous fuel supply device causes the gaseous fuel to be discharged into the atmosphere at a high speed above the charging layer, thereby mixing with the surrounding air in a short time, and the lower limit combustion concentration of the gaseous fuel. It is preferable to dilute to the following concentration and then introduce the diluted gaseous fuel into the charge layer. The reason is described below.

  As shown in FIG. 7 (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 position 90 mm deep from the top of 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. 7B, the results of measuring the distribution of methane gas concentration in the same manner as described above for the case where methane gas is supplied from the position 350 mm above the sintered cake using the same nozzle are shown. This is shown in FIG. 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.

  Next, in the present invention, the discharge speed of the gaseous fuel from the slits and nozzles provided in the gaseous fuel supply pipe of the gaseous fuel supply apparatus needs to be discharged at a high speed from the viewpoint of preventing backfire. In this case, it is desirable to discharge at a speed that is at least twice the combustion speed of the gaseous fuel, more preferably at a speed that is at least twice the turbulent combustion speed of the gaseous fuel. That is, in the operation of the sintering machine of the present invention, there is a combustion / melting zone in the sintering pallet, or a sintered cake layer being formed, always in the state of having a fire type, above the charging layer, Gas fuel is supplied. 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 nozzle, opening or slit is 300 mmAq or more and less than 40000 mmAq with respect to the atmospheric pressure.

  Moreover, it is preferable that the magnitude | size of the opening part which discharges gaseous fuel from gaseous fuel piping shall be the range of 3-0.5 mmphi. The reason is that, as described above, in order to prevent backfire to the gaseous fuel, it is preferable to set the discharge speed of the gaseous fuel to a speed exceeding the combustion speed, but when the opening area of the discharge portion is large, This is because it is difficult to extinguish when ignited and there is a possibility of causing backfire, but it has been found that if the nozzle diameter is about 3 mmφ or less, no backfire will occur even if ignited. Preferably, it is 2 mmφ or less. On the other hand, from the viewpoint of preventing backfire, the smaller the hole diameter, the better. However, considering the prevention of clogging of the opening and workability, the lower limit of the hole diameter is preferably about 0.5 mmφ.

When the piping for discharging these gaseous fuels and the opening have the same shape, in general, the closer the fuel is to the supply source header, the easier the fuel comes out, and the farther the fuel becomes, the less likely it is to come 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.

  For the direction in which the gaseous fuel is discharged into the air, various forms can be adopted. For example, as shown in FIG. 8, the gaseous fuel is discharged downward (vertically downward) toward the charging layer. In this way, a part of it is reflected on the surface of the charging layer and diluted, and as shown in FIG. 9, gaseous fuel is introduced into the charging layer by discharging it parallel (horizontal direction) to the surface of the charging layer. A method for promoting the dilution by lengthening the path to the end, or a method for promoting the dilution by discharging and reflecting the gaseous fuel toward the baffle plate (reflecting plate) as shown in FIG. As shown in the figure, the direction of the gas discharge slit, opening or nozzle provided in the gaseous fuel supply pipe is directed to the charging layer surface and diluted in multiple directions within a range of ± 90 degrees with respect to the vertical direction. Adopt a method to promote Door can be. Furthermore, as a modification of the above FIG. 11, a structure can be adopted in which the gas fuel supply pipe can be rotated around the axis and the discharge direction can be swung.

  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. 12 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.

  Further, as described above, the faster the discharge speed is, the higher the speed of the gaseous fuel to be discharged, since the more easily mixing with the surrounding air occurs and the dilution is promoted. Furthermore, when the gaseous fuel supplied from the gaseous fuel supply device is ignited by some kind of fire, if the flow rate of the gaseous fuel discharged from the nozzle or the like is slow, backfire occurs, and the gaseous fuel supply device or the gaseous fuel supply pipe May cause explosion or combustion. In order to avoid this danger, it is preferable to discharge at a rate twice or more the combustion rate of the gaseous fuel used. More preferably, the speed is twice or more the turbulent combustion speed of the gaseous fuel. Incidentally, the laminar combustion speed of methane gas is about 0.4 m / s, and the turbulent combustion speed is about 4 m / s.

In the present invention, as the gaseous fuel, it is preferable to use the gaseous fuel diluted to 75% or less of the lower combustion limit concentration at normal temperature in the atmosphere, more preferably the lower combustion limit, as the gaseous fuel. Those diluted to a concentration of 60% or less of the concentration, more preferably 25% or less of the lower limit concentration of combustion are used. There are two reasons for using the combustible gas diluted to 75% or less below the lower combustion limit concentration.
(A) The supply of the combustible gas as it is to the upper part of the charging layer may sometimes cause explosive combustion, and at least at room temperature, it is necessary to make it not burnable even if there is a fire type.
(B) Even if it reaches an electric precipitator or the like downstream of the wind box without being completely burned in the charging layer, there is no need to be burned by the discharge of the electric precipitator. It is.

In addition, as will be described later, the concentration of the diluted gas fuel is such that the shortage of air (oxygen) necessary for the combustion of the total carbonaceous material (solid fuel + gas fuel) in the sintering raw material does not cause shortage of combustion. It is necessary to use a diluted product.
However, the diluted gas fuel preferably has a concentration of 2% or more of the lower combustion limit concentration. This is because when the concentration is less than 2%, the strength of the sintered ore and the yield cannot be improved even by heat generated by combustion. Moreover, it is preferable to adjust the density | concentration of diluted gas fuel according to the amount of carbonaceous materials (solid fuel). Furthermore, the diluted gas fuel can cause combustion at a predetermined position in the charging layer by adjusting the concentration.

In the method for producing sintered ore according to the present invention, the diluted gaseous fuel is supplied (introduced) into the charging layer after the carbon material in the charging layer is ignited. The reason for this is that even if the diluted gas fuel is supplied at a position immediately after ignition, it only burns on the surface layer of the charging layer and does not affect the sintered layer at all. Therefore, it is necessary to supply diluted gas fuel to the charging layer after the sintering raw material at the upper part of the charging layer is fired to form a sintered cake layer. The diluted gas fuel can be supplied at an arbitrary position until the sintering is completed as long as the sintered cake layer is formed on the surface of the charging layer. The reasons other than the above, in which the diluted gas fuel is supplied after the sintered cake layer is formed, are as follows.
(A) If the diluted gas fuel is supplied in a state where no sintered cake is formed on the top of the charging layer, there is a risk of causing explosive combustion on the charging layer.
(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.

  Further, in the present invention, it is preferable to adjust either or both of the maximum reached temperature of the charging layer and the high temperature region holding time. For this purpose, the thickness of the combustion / melting zone is at least 15 mm or more, preferably 20 mm or more, more It is preferable to supply the diluted gas fuel in a state where the thickness is preferably 30 mm or more. If the thickness of the combustion / melting zone is less than 15 mm, the cooling effect by the air sucked through the sintered layer (sintered cake) and the diluted gaseous fuel will not be sufficient even if the gaseous fuel is burned. This is because the thickness of the melting zone cannot be increased. On the other hand, if the diluted gas fuel 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 region holding time is increased. It can be extended, and as a result, a sintered ore with high cold strength can be obtained.

  Further, the introduction of the diluted gas fuel into the charging layer is performed at a position where the combustion front is lowered below the surface layer and the combustion / melting zone is lowered by 100 mm or more, preferably 200 mm or more from the surface layer, that is, the middle or lower layer of the charging layer. It is preferable to carry out for the area. That is, the diluted gas fuel passes through the sintered cake region (sintered layer) generated in the surface layer of the charging layer without burning, and is supplied so as to burn when the combustion front moves 100 mm or more from the surface layer. Is preferred. 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 it is a position 200 mm or more lower than the surface layer, the influence of cooling by air is almost eliminated, and the thickness of the combustion / melting zone can be expanded to 30 mm or more. Further, it is more preferable to supply the diluted gas fuel in the vicinity of the sidewalls at both ends in the pallet width direction where the yield is greatly reduced.

In addition, although the diluted gaseous fuel production | generation apparatus changes with scales of a sintering machine, for example, gaseous fuel supply amount is 1000-5000m < ³ > (standard) / h, and a production amount is about 15,000 t / day, In a sintering machine having a length of 90 m, it is preferable that the sintering machine is disposed at a position about 5 m or less downstream of the ignition furnace.
In the manufacturing apparatus according to the present invention, the supply position of the diluted gas fuel (introduction position to the charging layer) is the ignition furnace exit side in the pallet traveling direction, and the so-called combustion front after the sintered cake is formed is below the surface layer. It is preferable to carry out at one or more arbitrary positions from the advanced position (for example, the position where combustion of gaseous fuel occurs below 100 mm, preferably about 200 mm or less below the surface layer) to the completion of sintering. This means that, as described above, the introduction of the gaseous fuel starts when the combustion front moves below the surface of the charging layer, and as a result, the combustion of the gaseous fuel is started in the charging layer. Since it occurs inside and gradually moves to the lower layer, it means that there is no risk of explosion and a safe sintering operation becomes possible.

  In the production method according to the present invention, the introduction of the diluted gas fuel 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.

  In the method for producing sintered ore according to the present invention, the supply of the diluted gaseous fuel from the upper part of the charged layer after ignition is such that at least a part of the introduced diluted gaseous fuel in the charged layer remains unburned. It is preferable to reach the combustion / melting zone and burn 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. In other words, if the supply of gaseous fuel is performed in the upper layer of the charging layer, which tends to be short of heat (insufficient holding time in the high temperature range), sufficient combustion heat will be provided. The quality can be improved, and if the supply of diluted gas fuel extends to the combustion / melting zone below the middle layer, the combustion / melting zone of the original charcoal material is recombusted with the diluted gas fuel.・ It is the same result as forming a melting zone, and it leads to expansion of the combustion and 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 reducing the moving speed. As a result, the quality of the sintered cake of the entire charged layer is improved (improving the cold strength), and consequently the quality (cold strength) and productivity of the product sintered ore are improved.

  In the present invention, it is important to determine the supply position of the diluted gas fuel from the viewpoint of where the operation / effect of the supply is exerted in the charging layer, and together with the supply of the fuel, It is also important to control how much the maximum temperature reached in the charging layer and the high temperature region holding time are controlled according to the amount of solid fuel under a constant heat amount standard.

  Therefore, in the present invention, when the diluted gas fuel is introduced (supplied) into the charging layer, not only the supply position is adjusted, but also the form of the combustion / melting zone itself is controlled, and thus It is preferable to control the maximum temperature reached in the melting zone and / or the high temperature region holding time.

  In general, in the charged layer after ignition, the combustion (flame) front gradually expands downward and forward (downstream) as the pallet moves, and the position of the combustion / melting zone is shown in FIG. ). And as shown in FIG.4 (b), the thermal history received in the sintering process in a sintered layer differs in an upper layer, a middle layer, and a lower layer, and it is high temperature range holding time (about 1200 degreeC or more with an upper layer-a lower layer). Time) is very different. As a result, the yield of sintered ore by position in the pallet 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, when the gaseous fuel is supplied according to the method of the present invention, the combustion / melting zone has an increased thickness in the vertical direction, a width in the pallet traveling direction, and the like, which are reflected in improving the quality of the product sintered ore. 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 gaseous fuel, it is possible to control 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, and reach the maximum. The temperature and the high temperature range holding time can be controlled. 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 into the charging layer is for controlling the cold strength of the entire product sintered ore. In other words, the original purpose of supplying diluted gaseous fuel is to improve the cold strength of the sintered cake, and thus the sintered ore. Through the control of the high temperature range holding time, which is the time to stay in, and the 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 Is to do.

  In the present invention, this strength level is particularly determined in consideration of the concentration of the diluted gas fuel, the supply amount, the supply position, and the supply range of the carbonaceous material in the sintered raw material (under the condition that the input heat amount is constant). By adjusting 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 into the charging layer in the pallet traveling direction is a sintered ore in an arbitrary zone between the sintered cake formed in the charging layer and the wet zone. It is based on how to make the cold strength of. For this control, in the present invention, the scale (size), number, position (distance from the ignition furnace), gas concentration of the gaseous fuel supply 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. Controls the strength of the sintered cake formed in the charge layer.

  Therefore, as a more effective means, in the present invention, as shown in FIG. 13 (a), the surface layer portion of the charging layer 9 is formed with holes and grooves, in particular, longitudinal or laterally extending grooves. It is effective to provide the acceleration recess 13. By providing this ventilation promoting recess 13, the time for the above-described diluted gas fuel to reach the combustion / melting zone in the charging layer 9 becomes faster, and the presence of this recess 13 also helps to suck the wind box. Regardless, the diffusion of the diluted gas fuel in the lateral direction is promoted, which effectively contributes to the realization of uniform sintering.

  For the formation of the ventilation promoting recess 13, as shown in FIG. 13 (b), a recessing device 16 composed of a plurality of disks 15 attached at equal intervals to a rotating shaft 14 spanned in the machine width direction, It is carried out by installing the material supply device, that is, above the charging layer 9 between the cutting chute 7 and the ignition furnace 10.

  The interval between the disks 15 of the indenting device 16, that is, the groove-like indentation interval (L) and depth (D) is set to an appropriate size according to the application model, but is generally L: 40 to 400 mm, That is, in order to achieve the effect uniformly, at least the sintered ore particle size (40 mm) to be produced is set. On the other hand, if it is too wide, the effect of imparting dents is lost, so the thickness is 400 mm or less. Further, in order to exert the dent effect and propagate the effect inside the layer, at least 10 mm or more is necessary, and the depth (D) is considered to be 10 to 200 mm. If it exceeds 200 mm, it will be difficult to dent. When the ventilation promoting depression 13 having such a size is provided, the diluted gas fuel can be quickly introduced and diffused into the combustion / melting zone at the upper part of the charging layer and the middle part of the layer. In addition, in the upper part of the insertion layer, the expansion of the combustion / melting zone is caused by the introduction and diffusion of the diluted gas fuel, and the strength of the obtained sinter can be greatly improved. When protrusions are provided on the peripheral surface of the disk 15 at regular intervals and only the protrusions are pressed against the surface of the loading layer, a hole recess 13 can be formed. When the entire disk 15 is pressed, steps with different depths are formed. A recess 13 can be formed.

  In the operation of the present invention, the lowering speed of the combustion zone corresponding to the traveling speed of the combustion front accompanying the movement of the pallet in the sintering machine (the reciprocal is the sintering time) is the ventilation promotion provided in the upper layer portion of the charging layer 9 Due to the presence of the depression 13, the supply of the diluted gas fuel is accelerated, and the thickness width in the vertical direction of the combustion / melting zone is increased in the same manner as when coke is increased or when high-temperature air is blown. Can do. As described above, when the gas fuel to be diluted is blown by providing the ventilation promoting recess 13 in the surface layer portion of the sintered raw material charging layer 9, the effect of expanding the combustion / melting zone width is compared with the case of simply blowing the combustible gas. In addition, it does not cause a decrease in the descent speed of the combustion front as in the case of increasing the amount of coke, and proceeds at the same speed as in the case of atmospheric sintering.

  In the above operation method of the present invention, the gaseous fuel supplied into the charging layer is blast furnace gas, coke oven gas, blast furnace / coke oven mixed gas, city gas, natural gas or methane gas, ethane gas, propane gas, butane gas, or It is preferable to use one of these mixed gases. 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.

Table 6 below shows the lower combustion limit concentrations of various gaseous fuels used in the present invention and the upper blowing concentration of the gaseous fuel (75%, 60%, 25% of the lower combustion limit concentration).
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%

  Next, Table 7 shows the contents and heating values of hydrogen, CO, methane, ethane, and propane contained as combustion components in C gas, LNG, and B gas.

  Furthermore, in the present invention, as the gaseous fuel to be supplied into the charging layer, in addition to the gaseous fuel, the ignition temperature in the gaseous state is higher than the temperature of the surface layer of the sintered bed, alcohols, ethers, petroleums, etc. It is also possible to use a vaporized liquid fuel such as hydrocarbon compounds. Table 8 shows liquid fuels that can be used in the present invention and their characteristics. Since the gas fuel vaporized from such a liquid fuel has an ignition temperature higher than that of the gas fuel described above, it burns inside the charging layer, which is higher than the temperature of the sintered bed surface layer, It is effective for expanding the temperature of the burning / melting zone at the blowing position. In particular, the effect is large when the ignition temperature is close to 500 ° C. In addition, when using the gaseous fuel which vaporized liquid fuel, it is preferable to hold | maintain gas supply piping to the temperature more than the boiling point of this liquid fuel and less than ignition temperature so that the vaporized fuel may not re-liquefy.

  In addition, since waste oil etc. may contain the component which is easy to ignite, and the component with low ignition temperature, it is unpreferable for using by this invention. When liquid fuel such as waste oil containing components with low ignition temperature and flash point is vaporized in advance and supplied onto the sintering material bed, the upper part of the material bed surface before reaching the vicinity of the combustion zone in the material bed This is because it burns in the space or in the vicinity of the surface layer of the raw material bed, so that the effect of extending the high temperature holding time by burning in the vicinity of the combustion zone of the sintered raw material bed intended by the present invention cannot be obtained.

  In the present invention, among the gaseous fuels, it is preferable to use one having a CO content of 50 mass ppm or less. That is, CO gas is harmful to the human body, and if gaseous fuel supplied onto the charging layer is not introduced into the charging layer in its entirety, it may cause human injury if it leaks out of the machine. Because there is. Specifically, the use of city gas 13A or propane gas is preferable from the viewpoint of cost as well as safety.

  Moreover, when manufacturing a sintered ore by the operation method which concerns on this invention, the pallet 8 to circulate and the sintered raw material containing a fine ore and a carbon material are charged on the pallet 8, and the charging layer 9 is formed. In a sintering machine provided with raw material supply devices 6 and 7, an ignition furnace 10 for igniting the carbonaceous material in the sintering raw material, and a wind box 11 below the pallet 8, on the downstream side of the ignition furnace A gaseous fuel supply device 12 is provided for supplying gaseous fuel into the air above the charging layer and introducing it into the charging layer as a diluted gaseous fuel below the lower combustion limit concentration, and the ignition furnace 10 and the raw material It is effective to use a sintering machine provided with the above-described indentation device 16 between the supply device 7 and the supply device 7.

  The gaseous fuel supply device is preferably arranged so as to straddle both sidewalls 8a of the pallet 8 along the width direction of the sintering machine. The gaseous fuel supply device 12 has a plurality of pipes for supplying gaseous fuel, preferably 3 to 15 pipes, arranged in a direction parallel or perpendicular to the pallet traveling direction, or in a vertical direction, and each pipe. In this case, it is preferable that the gas fuel is configured by a plurality of slits, ejection holes, or nozzles for supplying gaseous fuel to the atmosphere at high speed.

  The gaseous fuel supply device is provided with one or more downstream positions of the ignition furnace and at any position in the pallet traveling direction in the process in which the combustion / melting zone proceeds in the charging layer. It is preferable that the gaseous fuel is supplied to the carbonized material at a position after ignition of the carbonaceous material in the charging layer. In other words, one or more devices are installed at any position after the combustion front advances below the surface layer on the downstream side of the ignition furnace. From the viewpoint of adjusting the strength, the size, position, and number are determined. The gaseous fuel supply device is disposed at a low yield position in the vicinity of both sidewalls 8a. The gaseous fuel is 75% or less and 2% or more of the lower combustion limit concentration, or 60% of the lower combustion limit concentration. It is preferable to use a combustible gas diluted to a concentration of 2% or more, or 25% or less of the lower combustion limit concentration and 2% or more.

  FIG. 14 shows an embodiment of a sintering machine according to the present invention, but the present invention is not limited to this exemplary form. In the example shown in FIG. 14, gaseous fuel such as a mixed gas (M gas) of blast furnace gas and coke oven gas is introduced into the atmosphere on the upper side of the charging layer 9 corresponding to the downstream side in the pallet traveling direction of the ignition furnace 10. This is an example in which a gaseous fuel supply device 12 for discharging and making a diluted gaseous fuel having a desired concentration is provided. The gaseous fuel supply device 12 is provided with a plurality of gaseous fuel supply pipes 12a along the width direction of the pallet, and a nozzle 12b that discharges gaseous fuel into the atmosphere at a high speed is directed downward in the pipe and the pallet width. A plurality of elements arranged in the direction are arranged so as to cover the charging layer 9 from above the sidewall 8a. The M gas supplied from the gaseous fuel supply device 12 is mixed with surrounding air to become a diluted gaseous fuel, and then is depressed using the suction force of a wind box (not shown) under the pallet 8. It is introduced from the upper part of the charging layer 9 through the ventilation promoting depression 13 provided in the surface layer portion by the attaching device 16, and further through the combustion / melting zone (middle layer) and the sintered cake generated in the layer, It is introduced to the deep part (lower layer). At this time, the presence of the above-described ventilation promoting recess 13 helps to introduce the diluted gas fuel into the charging layer.

(1) In order to confirm the operation and effect of the present invention, the propane gas diluted with the exhaust gas of the sintering machine cooler is used in the gaseous fuel supply device 12 shown in FIG. 8 and FIG. An experiment was conducted to blow into the charging material layer 9 of the sintering raw material using the shown denting device 16. The sintering raw material used in this experiment is a general one used by the applicant company, and the suction pressure is set at a constant 1200 mmAq. In this experiment, the propane gas to be blown was diluted to a concentration of 0.5 vol% and 2.5 vol%. In terms of the amount of heat input, 0.5 vol% propane gas blowing substantially corresponds to 1 mass% compounding of powder coke.

  In this embodiment, first of all, it was found that propane gas diluted to 2.5 vol%, which is close to the lower combustion limit concentration (theoretical value, against air) as a result of observing the form of the combustion zone when propane gas was injected. Then, it burned on the raw material charging layer immediately after blowing, and gaseous fuel did not enter the charging layer, and the effect of supplying gaseous fuel could not be obtained. On the other hand, when the propane gas dilution concentration is 0.5 vol% with respect to air, the propane gas enters the charging layer without burning at the upper part of the charging layer, and in the charging layer. Burned. As a result, the vertical width (thickness) of the combustion / melting zone when sintered under atmospheric conditions was about 60 mm, whereas the width of the combustion / melting zone when diluted propane gas was injected was 150 mm. And more than doubled. This is equivalent to extending the high temperature region holding time.

  Therefore, it has been found that the effect of increasing the thickness of the combustion zone is exhibited even at 0.5 vol%, which is 1/5 of the lower combustion limit concentration of propane. On the contrary, in the gas fuel injection technique according to the present invention, it can be seen that it is difficult to control the combustion in the charging layer unless the gas fuel is diluted.

  Furthermore, in this embodiment, the combustion / melting zone in the upper part of the charging layer was compared and examined in the case where the ventilation promoting depression 13 was provided and in the case where it was not provided. As a result, when the diluted gas fuel is simply supplied to the surface of the normal flat charging layer 9 without providing the ventilation promoting recess 13, the thickness of the combustion / melting zone below the surface layer is 10 to 15 mm, but 30 to 50 mm. However, when the diluted gas fuel is sprayed by providing the ventilation promoting recess 13 in the surface layer portion of the charging layer, the thickness of the combustion / melting zone is ensured to be 50 mm or more, and the diluted gas fuel is simply sprayed. Productivity and cold strength (SI) were improved. In particular, it was found that those operated by the method suitable for the present invention contribute to the improvement of the productivity and the cold strength of the upper layer part when the sintered charge layer is divided into the upper layer, the middle layer and the lower layer.

(2) Next, the operation method of the sintering machine according to the present invention was applied to a DL type sintering machine having a daily scale of 20,000 tons. The length of the DL sintering machine used was 90m from the ignition furnace to the discharge section, and the air flow parallel to the pallet moving direction was downstream of the sintering surface scraper in front of the sintering furnace. An indentation device for forming 48 accelerating dents in the pallet width direction (interval (L): 0.1 m, depth (D): 0.02 m) is disposed, and about 5 behind the ignition furnace. Nine gas fuel supply pipes having a length (pallet traveling direction) of 15 m are arranged in parallel along the pallet traveling direction at a height of 500 mm above the charging layer at positions up to 35 m, Has two gas fuel supply devices with 149 nozzles for jetting gaseous fuel that are horizontally oriented at a spacing of 100 mm (1341 in total) in the pallet traveling direction, and city gas is used as gaseous fuel from the nozzles. Discharged into the atmosphere at high speed Te, city gas concentration was fed onto the sintering bed as a diluted gaseous Fuel 0.8 vol%. The total thickness of the charging layer is 600 mm (however, the upper layer 400 mm is a sintered material containing 4.2 mass% of powdered coke), and the gaseous fuel is supplied at a combustion / melting zone of 200 to 300 mm. Corresponds when present at a position. The diluted gaseous fuel supplied as described above is sucked and introduced into the charging layer by suction negative pressure control of the wind box below the sintering machine pallet, and the combustion / melting zone existing at the above position through the sintered layer. Burned in. The amount of C gas used at this time was 3000 m ³ (standard state) / hr.

As a result of operation with this actual sintering machine, the tumbler strength (TI) of the obtained sintered ore is improved by about 3% as compared with the normal operation as a whole, and the reduced dusting property (RDI) is in the normal operation. The reduction rate (RI) was improved by about 4% from the normal operation. Moreover, the production rate increased by 0.03 t / hr · m ² , confirming the effect of the present invention.

  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 figure explaining a 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. It is a figure explaining the structural example of the gaseous fuel supply apparatus which concerns on this invention. It is a figure explaining the other structural example of the gaseous fuel supply apparatus which concerns on this invention. 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 explaining the example of the discharge method of the gaseous fuel which concerns on this invention. It is a figure explaining the other example of the discharge method of the gaseous fuel which concerns on this invention. It is a figure explaining the other example of the discharge method of the gaseous fuel which concerns on this invention. It is a figure explaining the other example of the discharge method of the gaseous fuel which concerns on this invention. It is a graph which shows the influence which the discharge speed of gaseous fuel and the nozzle diameter have on the concentration distribution of dilution gas. It is a figure explaining the sintering machine which has a charging layer provided with a ventilation promotion hollow, and a hollow apparatus. It is a figure explaining the example of the sintering machine which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw material hopper 2 Drum mixer 3 Rotary kiln 4, 5 Surge hopper 6 Drum feeder 7 Cutting chute 8 Pallet 8a Side wall 9 Charging layer 10 Ignition furnace 11 Wind box 12 Gaseous fuel supply device 12a Gaseous fuel supply pipe 12b Nozzle 13 Venting promotion depression 14 Support shaft 15 Disc 16 Recessing device

Claims (5)

In the operation of the sintering machine in which diluted gas fuel and air below the lower combustion limit concentration are sucked into the charging layer of the sintering raw material from above the sintering machine, the charging layer surface layer portion is formed with holes or grooves. A method for operating a dilute gas fuel blowing sintering machine, characterized in that a ventilation promoting depression is provided. A charging process in which a sintered raw material containing fine iron ore and carbonaceous material is charged onto a circulating sinter machine pallet to form a charged layer of the sintered raw material on the pallet, and the charcoal on the surface of the charged layer An ignition process in which an ignition furnace is used to ignite the material, a diluted gas fuel generation process in which gaseous fuel is supplied into the air above the charging layer and diluted to obtain a diluted gaseous fuel below the lower combustion limit concentration, and under the pallet The diluted gas fuel is sucked and introduced into the charging layer together with air by the suction force of the arranged window box, and the diluted gas fuel is burned in the charging layer and simultaneously introduced into the charging layer. The diluted gas according to claim 1, wherein the diluted gas is subjected to a combustion step of generating a sintered cake by burning the carbonaceous material in the charging layer with air sucked and introduced together with the diluted gas fuel. Operation method of sintering machine for fuel injection. The method for operating a dilute gas fuel blowing sintering machine according to claim 1 or 2, wherein the ventilation promotion depression is provided on the surface of the charging layer by a depression device provided on the upstream side of the ignition furnace. . A circulating pallet,
A raw material supply device for charging a sintered raw material containing fine ore and carbonaceous material on the pallet to form a charging layer;
An ignition furnace for igniting the carbonaceous material in the sintered raw material charging layer;
In a sintering machine provided with a wind box below the pallet,
A diluting gas fuel blowing sintering machine, characterized in that a depression device is arranged downstream of the raw material supply device and upstream of the ignition furnace. 5. The diluting gas fuel blowing sintering machine according to claim 4, wherein the indenting device is formed by arranging disks that form a plurality of grooves parallel to a method of proceeding with the sintering machine.

Images