Ignition furnace, sintering machine, ignition furnace control method, sintered ore manufacturing method, and temperature measurement method for sintered ore bed in ignition furnace

Abstract

To provide a temperature measurement method of an ignition furnace, a sintering machine and a charging layer capable of measuring with precision a surface temperature of the charging layer inside the ignition furnace used for producing sintered ore.SOLUTION: An ignition furnace used for the production of sintered ore in which a sintered raw material containing charcoal material is charged on a pallet to form a charging layer, and then the charcoal material of the charging layer is burned to sinter the sintered raw material, comprises an ignition furnace burner that ignites the charcoal material on the surface of the charging layer, an ignition furnace cover covering the charging layer, a measurement window provided in the ignition furnace cover and arranged in a position where the surface in the ignition furnace can be seen directly, and a radiation thermometer provided outside the ignition furnace cover and measuring the surface temperature through the measurement window. A measurement wavelength of the radiation thermometer is a wavelength selected from a range of 0.5 μm or more to 4.0 μm or less, and the transmittance of the measurement wavelength in the measurement window is 50% or more.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an ignition furnace, a sintering machine, a method for controlling an ignition furnace, a method for producing sintered ore, and a method for measuring the temperature of a sintered ore bed in an ignition furnace. [Background technology]

[0002] Dwight Lloyd sintering machines are used in the iron ore sintering process. In these machines, powdered iron ore is mixed with water, limestone, and a carbonaceous material (solid fuel) such as coke breeze or anthracite, and the sinter raw material is granulated in a granulator. In the Dwight Lloyd sintering machine, the sinter raw material is loaded onto a pallet via a transport conveyor, a feed hopper, and a chute. In the Dwight Lloyd sintering machine, for example, 400 to 800 mm thick sinter raw material is loaded onto the pallet, and the loaded sinter raw material becomes the loading layer in the sintering machine.

[0003] The sintering machine is equipped with an ignition furnace equipped with combustion burners (ignition furnace burners) above the pallets, and a wind box (wind box) for air intake is installed below the pallets. When the carbonaceous material on the surface of the charging layer is ignited by the combustion burners in the ignition furnace, the carbonaceous material in the sintering raw material burns along the airflow from above to below created by the air intake by the wind box. The sintering reaction caused by this combustion gradually moves from the upper layer to the lower layer of the charging layer as the pallets move forward.

[0004] In the ignition furnace, multiple ignition furnace burners are arranged in the width direction of the pallet. The ignition furnace burners inject flames at approximately the same position in the width direction of the sintering bed. The flames injected from the ignition furnace burners ignite the carbonaceous material on the surface of the sintering bed. Then, limestone and some of the iron ore contained in the sintering bed melt into a molten liquid, which bonds the raw materials together to produce a sintered cake.

[0005] In the sintering process, it is necessary to appropriately control the maximum temperature and the holding time at high temperatures during the sintering reaction in the sintering bed. This results in the formation of calcium ferrite, which has high strength and relatively high reducibility, in the sintered ore. For example, if the ignition temperature of the sintering bed is too low, the molten liquid is not sufficiently generated in the sintering bed, weakening the bonds between the raw materials and reducing the strength of the sintered ore. In particular, the upper layer of the sintering bed is easily cooled after ignition due to the influence of airflow from the wind box. This cooling shortens the holding time at high temperatures and reduces the yield of sintered ore. On the other hand, if the ignition temperature of the sintering bed is too high, the calcium ferrite in the sintered ore may decompose into amorphous silicate and secondary hematite.

[0006] Amorphous silicates reduce the strength and reducibility of sintered ore, and secondary hematite makes it more susceptible to reduction and disintegration. Such low-strength sintered ore is re-sintered as return ore because it is finely divided when the sinter cake is crushed. In other words, if the ignition temperature of the sintering bed is too high, the strength of the sintered ore decreases, which reduces the yield of sintered ore and reduces the production efficiency of sintered ore.

[0007] For these reasons, technologies for controlling the ignition temperature of the charging bed have been developed. Patent Document 1 discloses a technology in which a radiation thermometer is placed downstream of the ignition furnace to measure the temperature distribution across the entire width of the charging bed, and the fuel flow rate of the ignition furnace burner is adjusted so that the surface temperature in the vicinity of the pallet side plates is higher than the temperature at the center of the pallet.

[0008] Patent Document 2 discloses a method for measuring the temperature distribution of a sintered bed in an ignition furnace by arranging surface temperature measuring devices for measuring the temperature distribution of a sintered bed in a width direction at at least two locations in the longitudinal direction immediately after ignition. In Patent Document 2, the amount of temperature drop of the surface temperature at each position in the width direction of the sintered bed is calculated using the measured temperature distribution, and the layer thickness distribution of the sintered bed in the width direction is controlled according to the calculated amount of temperature drop.

[0009] Furthermore, Patent Document 3 discloses a method in which a temperature detector equipped with a scanning mechanism is provided in an ignition furnace, and the temperature distribution in the direction of travel of the sintering bed is measured by scanning the temperature detector. In Patent Document 3, the heat retention index is calculated using the measured temperature distribution in the longitudinal direction of the sintering bed, and the fuel flow rate of the ignition furnace burner is adjusted according to the deviation from the set heat retention index. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 2-153027 [Patent Document 2] Japanese Patent Application Publication No. 62-20834 [Patent Document 3] Japanese Patent Publication No. 63-33527 Summary of the Invention [Problem to be solved by the invention]

[0011] The above-mentioned conventional techniques have the following problems. In Patent Document 1, the temperature of the charging bed is measured using a radiation thermometer located downstream of the ignition furnace. However, immediately after the surface of the charging bed is ignited by the ignition furnace burner, sintering progresses at least on the surface of the charging bed. In addition, the surface temperature of the charging bed decreases downstream of the ignition furnace. Therefore, even if the temperature of the charging bed is measured using a radiation thermometer downstream of the ignition furnace, information regarding the maximum temperature on the surface of the charging bed and the time it is held at high temperature cannot be obtained. Therefore, the technique disclosed in Patent Document 1 has the problem that it cannot solve the problem of increased return ore resulting in a decrease in sinter yield.

[0012] In Patent Document 2, a surface temperature measuring device for measuring the temperature distribution in the width direction of the ignition furnace is arranged inside the ignition furnace, and the temperature distribution of the ignition furnace is measured at at least two points in the longitudinal direction immediately after ignition. However, the inside of the ignition furnace is a high-temperature atmosphere, and arranging a sensor of the surface temperature measuring device inside the ignition furnace has problems in durability and maintainability. Therefore, there is a problem that it is difficult to steadily measure the surface temperature of the ignition furnace.

[0013] Furthermore, in the ignition furnace, water vapor is generated by the combustion of hydrogen, methane, and other fuels in the ignition furnace burner. Furthermore, dust is also generated by the combustion of the sintering bed. These disturbances interfere with temperature measurement using a radiation thermometer, resulting in a problem of low temperature measurement accuracy. In particular, near the position where the flame emitted from the ignition furnace burner impinges on the sintering bed surface, the flame from the ignition furnace burner also disturbs temperature measurement, further reducing the accuracy of temperature measurement in the sintering bed after ignition.

[0014] The technology described in Patent Document 3 is similar to that of Patent Document 2, and has problems with durability and maintainability in that a temperature detector equipped with a scanning mechanism is placed inside the ignition furnace. There is also the issue of reduced temperature measurement accuracy due to steam, dust, and flames from the ignition furnace burner inside the ignition furnace.

[0015] The present invention has been made to solve the above-mentioned problems, and its object is to provide an ignition furnace, a sintering machine, and a temperature measurement method for a sintered ore bed, which are capable of accurately measuring the surface temperature of the sintered ore bed inside an ignition furnace used to produce sintered ore.Furthermore, another object of the present invention is to provide a control method for an ignition furnace that can improve the sintered ore yield, and a sintered ore production method that can produce sintered ore with a high yield. [Means for solving the problem]

[0016] The means for solving the above problems are as follows. [1] An ignition furnace used in the production of sintered ore, in which sintering raw materials including carbonaceous material are charged onto an endless movable pallet to form a charging bed, and then the carbonaceous material in the charging bed is burned to sinter the sintering raw materials, the ignition furnace comprising: an ignition furnace burner that ignites the carbonaceous material on the surface of the charging bed; an ignition furnace cover that covers the charging bed; a measurement window that is provided in the ignition furnace cover and positioned so that the surface inside the ignition furnace can be directly viewed; and a radiation thermometer that is provided on the outside of the ignition furnace cover and measures the temperature of the surface through the measurement window, wherein the measurement wavelength of the radiation thermometer is a wavelength selected from the range of 0.5 μm to 4.0 μm, and the transmittance of the measurement wavelength through the measurement window is 50% or more. [2] The ignition furnace according to [1], wherein the radiation thermometer measures the surface temperature of an ignition part that is ignited by a flame sprayed from the ignition furnace burner. [3] The ignition furnace according to [1] or [2], wherein the detection element of the radiation thermometer is any one of lead selenide (PbSe), lead sulfide (PbS), indium gallium arsenide (InGaAs), and silicon (Si). [4] The ignition furnace according to any one of [1] to [3], wherein the window material of the measurement window is quartz glass or borosilicate glass. [5] A sintering machine having an ignition furnace described in any one of [1] to [4], comprising: a sintering raw material charging device that charges the sintering raw material into the pallet; and a wind box that is provided below the pallet and that sucks air from inside the charging bed, and the pressure above the charging bed inside the ignition furnace is made negative by the suction of air. [6] A method for controlling an ignition furnace according to any one of [1] to [4], which controls the flow rate of fuel gas supplied to the ignition furnace burner so that the surface temperature of the charging bed measured by the radiation thermometer is within a predetermined temperature range. [7] A method for producing sintered ore, comprising producing sintered ore using the method for controlling an ignition furnace described in [6]. [8] A method for measuring the temperature of a charging bed in an ignition furnace used in the production of sintered ore, in which sintering raw materials including carbonaceous material are charged onto an endless movable pallet to form a charging bed, and then the carbonaceous material in the charging bed is burned to sinter the sintering raw materials, wherein the carbonaceous material on the surface of the charging bed is ignited by an ignition furnace burner, and the temperature of the surface on the inside of the ignition furnace cover is measured through a measurement window provided in an ignition furnace cover covering the charging bed using a radiation thermometer provided on the outside of the ignition furnace cover, and the measurement wavelength of the radiation thermometer is a wavelength selected from the range of 0.5 μm or more and 4.0 μm or less, and the transmittance of the measurement wavelength through the measurement window is 50% or more. [9] The method for measuring the temperature of a sintered body in an ignition furnace according to [8], wherein the pressure above the sintered body inside the ignition furnace is made negative. [Effects of the Invention]

[0017] The ignition furnace, sintering machine, and sintering bed temperature measurement method according to the present invention enable accurate measurement of the surface temperature of the sintering bed inside the ignition furnace. Furthermore, the ignition furnace control method and sintered ore production method according to the present invention enable sintered ore to be produced with a high yield. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram showing an example of a sintered ore manufacturing apparatus for manufacturing sintered ore. [Figure 2] FIG. 2 is a schematic side cross-sectional view of the sintering raw material charging device and the ignition furnace. [Figure 3] FIG. 3 is a schematic cross-sectional view of the ignition furnace. [Figure 4] FIG. 4 is a schematic diagram showing one of a plurality of burner nozzles that constitute the ignition furnace burner. [Figure 5] FIG. 5 is a schematic diagram showing an example of an ignition furnace having a measurement window provided on the side cover. [Figure 6] FIG. 6 is a graph showing the transmittance of light including the infrared wavelength band. [Figure 7] FIG. 7 is a schematic diagram showing the temperature measurement positions using a radiation thermometer. [Figure 8] FIG. 8 is a graph showing the intensity distribution of infrared rays emitted from a flame. [Figure 9] FIG. 9 is a graph showing the transmittance of light passing through carbon dioxide gas. [Figure 10] FIG. 10 is a graph showing the transmittance when lead selenide (PbSe) and lead sulfide (PbS) are selected as the detection element of the radiation thermometer and quartz glass is used as the window material for the measurement window. [Figure 11] FIG. 11 is a graph showing the transmittance of light through water vapor. [Figure 12] FIG. 12 is a graph showing the relationship between the flow rate of the fuel gas supplied to the ignition furnace burner and the surface temperature or heat retention index of the sintering bed S. [Figure 13] FIG. 13 is a graph showing the change in surface temperature in the sintering bed S over time from ignition. [Figure 14] FIG. 14 is a graph showing the relationship between the measurement results of the surface temperature of the sintering bed shown in FIG. 12 and the yield of sintered ore. [Figure 15] FIG. 15 is a diagram illustrating a configuration example of a control device. [Figure 16] FIG. 16 is a graph showing the results of measuring the temperature distribution in the width direction of the sintering bed. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments show preferred examples of the present invention, and the present invention is not limited to these examples.

[0020] FIG. 1 is a schematic diagram showing an example of a sinter ore manufacturing apparatus 120 for manufacturing sinter ore. The sinter ore manufacturing apparatus 120 includes a blending tank 10, a drum mixer 16, a sintering machine 30, a crusher 50, a cooler 52, a screening device 54, and a control device 100. The blending tank 10 is composed of a plurality of surge hoppers 12, which are storage tanks. Each of the plurality of surge hoppers 12 stores raw materials for sinter ore. In this embodiment, four surge hoppers 12 are provided, and each stores, for example, an iron-containing raw material, a CaO-containing raw material, an MgO-containing raw material, and a carbonaceous material.

[0021] The iron-containing raw materials used to produce sintered ore include various iron ores such as hematite and magnetite. The CaO-containing raw materials include limestone and quicklime. The MgO-containing raw materials include dolomite and refined nickel slag. The carbonaceous material is a solid fuel such as coke breeze and anthracite. The iron-containing raw materials may include dust generated in steelworks. The raw materials for sintered ore may also include return ore, which is fine sintered ore that does not meet the specified size.

[0022] A predetermined amount of each raw material stored in the blending tank 10 is cut out and transported to a drum mixer 16 by a blended raw material transport conveyor 14. An appropriate amount of water is added to each raw material transported to the drum mixer 16, and the raw materials are granulated into pseudo-particles with an average particle size of, for example, 3.0 to 6.0 mm.

[0023] The drum mixer 16 is an example of a granulating device that mixes the raw materials and granulates them to form the sintering raw material. Multiple granulating devices may be used, and a pelletizer may be used instead of the drum mixer 16. Also, multiple types of granulating devices may be used, for example, both a drum mixer and a pelletizer may be used. The sintering raw material 18 granulated by the drum mixer 16 is transported to the sintering machine 30 by the sintering raw material transport conveyor 20.

[0024] The sintering machine 30 is, for example, a downward suction-type Dwight Lloyd sintering machine. The sintering machine 30 has a sintering raw material charging device 32, an endless moving pallet 34, an ignition furnace 36, a gaseous fuel supply device 38, and a wind box 40. The sintering raw material charging device 32 charges the sintering raw materials 18 transported by the sintering raw material transport conveyor 20 into the pallet 34 to form a sintering bed S. The endless moving pallet 34 transports the sintering raw materials in one direction (hereinafter sometimes referred to as the traveling direction of the pallet 34). The ignition furnace 36 is installed above the pallet 34 and ignites (lights) the surface of the sintering bed S. The gaseous fuel supply device 38 supplies gaseous fuel from above the sintering bed S. The wind box 40 is installed below the pallet 34 and generates an airflow from above to below by sucking air inside the sintering bed S.

[0025] 2 is a schematic cross-sectional side view of the sintering raw material charging device 32 and the ignition furnace 36. The sintering raw material charging device 32 has a feed hopper 60, a drum feeder 62, a charging gate 64, and a chute 66. The sintering raw material 18 in the feed hopper 60 is cut out by the drum feeder 62, slides down on the chute 66, and charged onto the pallet 34. A charging layer S of sintering raw material is formed by the sintering raw material 18 charged onto the pallet 34.

[0026] The charging gate 64 is a plate-like member provided along the width direction of the chute 66. Generally, a plurality of charging gates 64 are provided along the width direction of the chute 66, and the opening of the charging gate 64 is adjusted by an opening adjustment device (not shown). By adjusting the opening of the charging gate 64, the charging speed and charging state of the sinter raw material 18 charged onto the pallet 34 are controlled. The thickness of the charging layer S formed by charging onto the pallet 34 is adjusted by a baffle 70 when it is transported to the ignition furnace 36.

[0027] The ignition furnace 36 is a device that ignites the surface of the charging bed S, the thickness of which is adjusted by the baffle 70, to cause a sintering reaction from the upper layer to the lower layer of the charging bed S. The ignition furnace 36 has an ignition furnace burner 72, an ignition furnace cover 74 (described later), and a measurement window.

[0028] The ignition furnace burner 72 injects a flame toward the surface of the charging bed S charged in the ignition furnace 36. This ignites the carbonaceous material on the surface of the charging bed S. Because the wind box 40 sucks the air inside the charging bed S downward, when the carbonaceous material on the surface of the charging bed S is ignited, the carbonaceous material inside the charging bed S burns sequentially downward. This combustion of the carbonaceous material forms a molten zone in the sintering raw material, and this molten zone moves downward in the charging bed S due to the combustion of the carbonaceous material. Since the charging bed S is continuously transported by the pallet 34, the flame of the ignition furnace burner 72 continuously ignites the surface of the charging bed S transported to the position of the ignition furnace burner. Then, as the pallet 34 moves, the sintering reaction progresses from the upper layer to the lower layer of the charging bed S, and the sintering raw material 18 is sintered to produce a sintered cake.

[0029] Referring again to FIG. 1, a wind box 40 is provided below the pallet 34 to suck air from inside the sintering bed S downward and generate an airflow moving from top to bottom in the thickness direction of the sintering bed S. The wind box 40 is connected to a main duct 42, and an exhaust fan 46 sucks the gas from the main duct 42, causing the wind box 40 to suck air from inside the sintering bed S downward and generating an airflow moving from top to bottom in the thickness direction of the sintering bed S. The exhaust fan 46 is, for example, a blower or a pump. A dust collector 44 is provided between the main duct 42 and the exhaust fan 46 to remove dust and other contaminants from the gas exhausted from the main duct 42. The exhaust fan 46 is connected to a chimney 48, and the gas exhausted from the main duct 42 is discharged from the chimney 48 after harmful substances have been removed.

[0030] By providing a wind box 40 below the pallets 34 passing through the ignition furnace 36, the sintering reaction of the sintering raw materials progresses from the upper layer to the lower layer of the sintering bed S, allowing for efficient production of a sintered cake. A gaseous fuel supply device 38 is provided downstream of the ignition furnace 36 in the traveling direction of the pallets 34. By supplying gaseous fuel from the gaseous fuel supply device 38 into a hood installed above the sintering bed S, the upper layer of the sintering bed S, which is difficult to maintain at a high temperature, can be maintained at a high temperature. However, the gaseous fuel supply device 38 does not necessarily have to be provided.

[0031] When a sinter cake is produced downstream of the ignition furnace 36, the sinter cake is crushed by a crusher 50 to become sintered ore. The sintered ore crushed by the crusher 50 is cooled by a cooler 52. The sintered ore cooled by the cooler 52 is sieved by a sieving device 54 having multiple sieves to separate the sintered ore 56 having a predetermined particle size or larger and return ore 58 having a particle size smaller than the predetermined particle size. The sintered ore 56 thus obtained is called sintered ore, and the yield of the sintered ore is the sintered ore yield. The sintered ore 56 is charged into the blast furnace as a blast furnace raw material, while the return ore 58 is transported to a blending tank 10 to be used again as a raw material for sintered ore.

[0032] Next, the ignition furnace 36 will be described. Fig. 3 is a cross-sectional schematic diagram of the ignition furnace 36. Fig. 3(a) is a cross-sectional view taken along a plane perpendicular to the traveling direction of the pallet 34, and Fig. 3(b) is a cross-sectional view taken along a plane parallel to the traveling direction of the pallet 34.

[0033] The length of the ignition furnace 36 (the distance in the pallet conveying direction) is 2 to 4 m. The thickness of the charging bed S is 400 to 800 mm. The width of the charging bed S is 3000 to 6000 mm. Pallet side plates 88 are provided on the side surfaces of the charging bed S. The pallet side plates 88 are provided to support the charging bed S from the sides and maintain the layer thickness distribution of the charging bed S.

[0034] The ignition furnace cover 74 of the ignition furnace 36 has a top cover 80 covered with castable refractory and an iron shell, and a side cover 82, and is provided to cover the charging bed S. The top cover 80 covers the upper part of the charging bed S, and the side cover 82 covers the side part of the charging bed S. Although a certain gap is generated between the side cover 82 and the pallet side plate 88, the size of the gap is configured to be kept relatively small. This restricts air leakage from the side, and the inside of the ignition furnace 36 is maintained airtight to a certain extent.

[0035] The inlet of the ignition furnace 36 is opened to allow the charging of the charging bed S into the ignition furnace 36, but is configured so that a narrow gap is maintained between the baffle 70 and the upper surface of the charging bed S. Similarly, the discharge outlet of the ignition furnace 36 is configured so that a narrow gap is maintained between the baffle 70 and the upper surface of the charging bed S. In this way, the gaps at both the charging inlet and the discharge outlet are kept narrow by the baffle 70, thereby maintaining a certain degree of airtightness inside the ignition furnace 36.

[0036] The ignition furnace burner 72 generates combustible gas by mixing fuel gas and combustion air and sprays a flame from the tip of the burner nozzle. The ignition furnace burner 72 has multiple burner nozzles in the width direction of the charging bed S. The number of burner nozzles arranged in the width direction of the charging bed S is within the range of 2 to 8.

[0037] The ignition furnace burner 72 is attached to the top cover 80, and the burner nozzle of the ignition furnace burner 72 is disposed inside the ignition furnace 36. The ignition furnace burner 72 is connected to supply pipes for fuel gas and combustion air used for burner heating. The fuel gas and combustion air are supplied from supply devices provided outside the ignition furnace 36. The fuel gas supply pipe to the ignition furnace burner 72 is provided with a fuel gas flow rate adjustment valve 90 for adjusting the fuel gas flow rate and a fuel gas flow meter 92 for measuring the fuel gas flow rate. This allows the flow rate of the fuel gas combusted in the ignition furnace burner 72 to be controlled. In addition, the combustion air supply pipe to the ignition furnace burner 72 is provided with an air flow rate adjustment valve 94 for adjusting the combustion air flow rate and an air flow meter 96 for measuring the combustion air flow rate. This allows the air ratio during combustion of the ignition furnace burner 72 to be controlled.

[0038] FIG. 4 is a schematic diagram showing one of the multiple burner nozzles 76 constituting the ignition furnace burner 72. The ignition furnace burner 72 has multiple burner nozzles 76 that emit flames from the upper cover 80 toward the surface of the charging bed S along the width direction of the pallet 34. The burner nozzle 76 shown in FIG. 4 injects combustion air toward the gas flow into which the fuel gas is injected. This causes the fuel gas and combustion air to mix inside the ignition furnace 36, generating combustible gas and causing a combustion reaction. For this reason, the burner nozzle 76 injects the combustion air at a certain angle relative to the gas flow into which the fuel gas is injected so that the air is mixed with the fuel gas.

[0039] The fuel gas for the ignition furnace burner 72 may be any of coal gas, city gas, natural gas, methane gas, ethane gas, propane gas, and shale gas. A mixed gas containing two or more fuel gases selected from these may also be used as the fuel gas. The coal gas may be coke oven gas, blast furnace gas, converter gas, or electric furnace gas. These gases are by-product gases generated during the manufacturing process in steelworks, and can be reused as fuel gas by using them. Blast furnace gas is a by-product gas generated when iron ore is reduced in a blast furnace to produce pig iron. Coke oven gas is a by-product gas generated during high-temperature carbonization of coal to produce coke. Converter furnace gas is a by-product gas generated during the steelmaking process in a converter furnace. Electric furnace gas is a by-product gas generated by the incomplete combustion of auxiliary fuel (recarburizer) used in an electric furnace.

[0040] By-product gases have various component compositions depending on the process used to generate them. For example, a typical composition of blast furnace gas is 21-30 volume % of the combustible component carbon monoxide, 50-60 volume % of the non-combustible component nitrogen, and 10-22 volume % of carbon dioxide. A typical composition of coke oven gas is 46-60 volume % of hydrogen, 20-35 volume % of methane, 5-10 volume % of carbon monoxide, and 2-4 volume % of hydrocarbons such as ethylene. A typical composition of converter furnace gas is approximately 75 volume % of carbon monoxide and approximately 13 volume % of carbon dioxide, with trace amounts of oxygen, nitrogen, and hydrogen. A typical composition of electric furnace gas is approximately 10 volume % of carbon monoxide, approximately 22 volume % of carbon dioxide, approximately 5 volume % of oxygen, and approximately 56 volume % of nitrogen. As coal gas, it is preferable to use a gas (sometimes called M gas) that is an appropriate mixture of blast furnace gas, coke oven gas, converter furnace gas, and electric furnace gas. These gases have different calorific values, so by mixing these coal gases with different calorific values, the calorific value of the ignition furnace burner 72 can be adjusted.

[0041] The combustion conditions of the ignition furnace burner 72 are, for example, a fuel gas flow rate of 1200 Nm per 1 m of the width of the sintering bed S. 3 / (m hr), and combustion air is supplied so that the air to fuel gas ratio is about 0.9. This allows the surface temperature of the sintering bed S to be raised to about 1200°C.

[0042] The ignition furnace cover 74 is provided with a measurement window 86 that is arranged at a position where the upper surface of the charging bed S can be directly viewed. The position where the upper surface of the charging bed S can be directly viewed is a position where the upper surface of the charging bed S inside the ignition furnace cover 74 can be visually captured from the outside of the ignition furnace cover 74 through the measurement window 86.

[0043] FIG. 5 is a schematic diagram showing an example of an ignition furnace 36 in which a measurement window 86 is provided in the side cover 82. FIG. 5(a) is a schematic side view of the ignition furnace 36. As shown in FIG. 5(a), the measurement window 86 is disposed at a position higher than the upper surface of the charging bed S in the ignition furnace 36. One or more measurement windows 86 may be disposed in the traveling direction of the pallet 34. As shown in FIG. 5, by providing multiple measurement windows 86 in the ignition furnace 36, the surface temperature of the charging bed S can be measured at different positions in the traveling direction of the pallet 34.

[0044] 5(b) is a diagram schematically illustrating the field of view observed when the upper surface of the charging bed S is viewed directly through the measurement window 86. As shown in FIG. 5(b), the measurement window 86 is preferably provided at a position where the area where the flame 98 injected from the burner nozzle 76 collides with the upper surface of the charging bed S (hereinafter, this area will be referred to as an ignition part 99) can be viewed directly. By measuring the temperature of the ignition part 99, the maximum temperature on the surface of the charging bed S can be determined.

[0045] The measurement window 86 is not limited to being provided in the side cover 82 as long as it is located in a position that allows direct viewing of the top surface of the charging bed S. The measurement window 86 may be provided in the top cover 80 of the ignition furnace 36 in a position that allows visual observation of the top surface of the charging bed S. However, if the measurement window 86 is provided in the top cover 80, the field of view of the top surface of the charging bed S may be limited by supply pipes for the ignition furnace burner 72, fuel gas, etc. Furthermore, if a part of the top cover 80 is opened, the strength of the top cover 80 decreases, making it easier for firebricks, etc., to fall off. For this reason, it is preferable that the measurement window 86 be provided in the side cover 82.

[0046] Heat-resistant glass made of quartz glass or borosilicate glass is preferably used for the measurement window 86. Furthermore, the measurement window 86 is preferably made of a material that transmits infrared rays, such as barium fluoride, calcium fluoride, zinc sulfide, zinc selenide, or germanium.

[0047] Figure 6 is a graph showing the transmittance of light including the infrared wavelength band. The horizontal axis of Figure 6 represents wavelength (μm), and the vertical axis represents transmittance (%). As shown in Figure 6, although the transmittance of light varies depending on the material selected, it can be seen that by selecting the wavelength of light, light (radiated light) generated inside the ignition furnace cover 74 can be received outside the ignition furnace cover 74 through the measurement window 86.

[0048] The ignition furnace 36 according to this embodiment has a radiation thermometer 84 outside the measurement window 86, which measures the surface temperature of the sintering bed S through the measurement window 86. The radiation thermometer 84 uses a wavelength selected from the range of 0.5 μm or more and 4.0 μm or less as a measurement wavelength.

[0049] The installation position of the radiation thermometer 84 will be described with reference to FIG. 3 again. The radiation thermometer 84 is disposed so as to receive radiant light from the surface of the charging bed S inside the ignition furnace 36 through the measurement window 86. Since the measurement window 86 is provided at a position higher than the surface of the charging bed S, the radiation thermometer 84 is disposed so that its light-receiving portion faces downward. Meanwhile, the direction in which the light-receiving portion of the radiation thermometer 84 faces can be arbitrarily changed left and right with respect to the measurement window 86. Therefore, by adjusting the left and right position of the light-receiving portion of the radiation thermometer 84, the surface temperature of the charging bed S can be measured at any position with respect to the traveling direction of the pallet 34, such as the direction of the entrance or exit of the ignition furnace 36, or the direction of an ignition portion 99 where a flame 98 from the ignition furnace burner 72 collides with the charging bed S.

[0050] The radiation thermometer 84 may be a spot radiation thermometer that measures local temperature, a scanning radiation thermometer that can scan the field of view in one axial direction using a rotating mirror or the like, or a thermograph that can measure the in-plane temperature distribution. When a scanning radiation thermometer is used, it may be scanned in the traveling direction of the charging bed S or in the width direction.

[0051] FIG. 7 is a schematic diagram showing the temperature measurement position by the radiation thermometer 84. FIG. 7(a) is a diagram showing an example of measuring the temperature at a specific position on the surface of the charging bed S using a spot radiation thermometer. In the example shown in FIG. 7(a), the surface temperature of the charging bed S is measured at the center in the width direction (black circle in the figure) within the range of an ignition part 99 where a flame 98 from the ignition furnace burner 72 collides with the charging bed S. This makes it possible to measure the maximum temperature on the top surface of the charging bed S.

[0052] Fig. 7(b) is a diagram showing an example of measuring the surface temperature by scanning the measurement point in the width direction of the sintering bed S using a scanning radiation thermometer. In the example shown in Fig. 7(b), the average temperature in the width direction (black line in the figure) is measured within the range of an ignition part 99 where a flame 98 from the ignition furnace burner 72 collides with the sintering bed S. This makes it possible to measure the surface temperature distribution in the width direction of the sintering bed S.

[0053] Fig. 7(c) is a diagram showing an example in which the measurement range includes the entire width direction of the charging bed S and the surface temperature of a certain range in the longitudinal direction is measured using a thermograph. In the example shown in Fig. 7(c), the temperature is measured in a range including an ignition part 99 where a flame 98 from the ignition furnace burner 72 collides with the charging bed S (the range surrounded by the black line in the figure). This makes it possible to measure the surface temperature distribution of the charging bed S in the width direction and the longitudinal direction.

[0054] The measurement wavelength of the radiation thermometer is selected from the range of 0.5 μm to 4.0 μm. By using a measurement wavelength within this range, temperature measurement errors are reduced, allowing the surface temperature of the charging bed S to be measured with high accuracy. On the other hand, if the measurement wavelength of the radiation thermometer is less than 0.5 μm, the change in radiation energy is small in the temperature range of 600 to 1400 °C, resulting in large temperature measurement errors. If the measurement wavelength of the radiation thermometer is greater than 4.0 μm, temperature measurement errors are likely to occur due to the influence of the flame 98 from the ignition furnace burner 72. Furthermore, at positions away from the ignition unit 99, temperature measurement errors are likely to occur due to the influence of atmospheric gases, such as carbon dioxide, generated in the ignition furnace.

[0055] Figure 8 is a graph showing the intensity distribution of infrared rays emitted from a flame. The horizontal axis of Figure 8 is wavelength (μm), and the vertical axis is relative radiation intensity (%). The relative radiation intensity is a relative value of radiation intensity normalized using the maximum value of the measured radiation intensity. The flame shown in Figure 8 is a flame produced by burning coke oven gas.

[0056] Because coke oven gas contains a relatively high amount of hydrogen, a flame fueled by coke oven gas appears transparent under visible light. However, as shown in FIG. 8, the wavelength of infrared light emitted from the flame overlaps with the wavelength measured by the radiation thermometer, and the flame can disturb temperature measurement. For this reason, in the ignition furnace 36 according to this embodiment, the measurement wavelength of the radiation thermometer is set to 4.0 μm or less. This allows for conditions that are less susceptible to the influence of the flame, even when measuring the surface temperature of the charging bed S through the flame, thereby reducing errors in temperature measurement by the radiation thermometer 84. Note that if the combustion in the ignition furnace burner 72 is in an oxygen-deficient state, the flame color may turn yellow. To prevent this, combustion in the ignition furnace burner 72 is preferably performed under oxygen-rich conditions, in which the air ratio of the fuel gas to the theoretical air amount is 1 or greater.

[0057] FIG. 9 is a graph showing the transmittance of light passing through carbon dioxide gas. The horizontal axis of FIG. 9 represents wavelength (μm), and the vertical axis represents transmittance (%). As shown in FIG. 9, it can be seen that carbon dioxide (carbonate gas) generated by burning fuel gas in the ignition furnace burner also disturbs temperature measurement. For this reason, in the ignition furnace 36 according to this embodiment, the measurement wavelength of the radiation thermometer is set to 4.0 μm or less. This makes it possible to create conditions in which light transmission is less likely to be obstructed by carbon dioxide generated by the combustion of fuel gas, thereby reducing errors in temperature measurement by the radiation thermometer 84.

[0058] Furthermore, the detection element of radiation thermometer 84 is preferably a photoelectric type. Thermoelectric detection elements such as pyroelectric elements and thermopiles have a measurement wavelength of 8 to 13 μm, which is undesirable because the measurement wavelength is affected by flames and atmospheric gases. For example, it is preferable to use one of lead selenide (PbSe), lead sulfide (PbS), indium gallium arsenide (InGaAs), and silicon (Si) as the photoelectric detection element. Lead selenide has a measurement wavelength of 4 μm, lead sulfide has a measurement wavelength of 2 μm, indium gallium arsenide has a measurement wavelength of 1.55 μm, and silicon has a measurement wavelength of 0.9 μm. Regardless of which element is used, radiation thermometer 84 will have a measurement wavelength in the range of 0.5 μm to 4.0 μm.

[0059] Furthermore, the transmittance of the measurement window 86 at the measurement wavelength of the radiation thermometer 84 is 50% or more. FIG. 10 is a graph showing the transmittance when lead selenide (PbSe) and lead sulfide (PbS) are selected as the detection element of the radiation thermometer and quartz glass is used as the measurement window 86. Since the measurement wavelength of lead sulfide is 2 μm, the transmittance of quartz glass at the measurement wavelength is nearly 100%. Therefore, the radiation light with a wavelength of 2 μm emitted from the surface of the charging bed S in the ignition furnace 36 passes through the measurement window 86 without being attenuated by the flame or atmospheric gas in the ignition furnace. This shows that the surface temperature of the charging bed S can be measured with high accuracy using the radiation thermometer 84 installed outside the measurement window 86.

[0060] On the other hand, when lead selenide is used as the detection element of the radiation thermometer 84, the measurement wavelength is 4 μm, and therefore the transmittance of quartz glass for the measurement wavelength is about 70%. Therefore, although the radiation light with a wavelength of 4 μm emitted from the surface of the charging bed S in the ignition furnace 36 reaches the measurement window 86 without being attenuated by the flame or atmospheric gas in the ignition furnace, about 30% of the radiation light is blocked when passing through the measurement window 86. For this reason, the radiation thermometer 84 provided outside the measurement window 86 receives the radiation light with an intensity of 70% that passes through the measurement window 86 to measure the surface temperature of the charging bed S.

[0061] Therefore, in such a case, it is preferable to correct the temperature measured by the radiation thermometer 84 using the transmittance of the measurement window 86. This allows the surface temperature of the charging bed S to be measured with high accuracy even when a measurement window 86 with low transmittance at the measurement wavelength is used. However, if the measurement window 86 has a transmittance of less than 50% at the selected measurement wavelength, the measurement values ​​will vary greatly even if the transmittance is corrected, making it difficult to measure the temperature with high accuracy. Therefore, the transmittance of the measurement wavelength at the measurement window 86 needs to be 50% or more.

[0062] The correction method when the transmittance of the measurement wavelength through the measurement window 86 is less than 100% is as follows: The radiation thermometer 84 receives radiation from the object to be measured and converts it into temperature, and the self-luminous intensity of the loading layer to be measured is expressed by the following equation (1).

[0063]

number

[0064] In addition, when the radiation light is blocked by the measurement window 86, the received light intensity Er (W / m 3 ) is expressed by the following equation (2) using the spontaneous emission intensity E and transmittance ξ (%) in the above equation (1).

[0065] Er=ξE (2)

[0066] When the above formulas (1) and (2) are used for correction, the transmittance ξ of the window material of the measurement window is determined in advance by measuring the electromagnetic waves emitted from the blackbody furnace with a radiation thermometer through the window material used for measurement offline. Then, by using the transmittance ξ and the above formulas (1) and (2), the surface temperature T of the charging bed S can be calculated with high accuracy even if the transmittance of the measurement window 86 is not 100% for the selected measurement wavelength.

[0067] In the ignition furnace 36 according to the present embodiment, it is preferable to make the pressure above the charcoal charging bed S inside the ignition furnace 36 negative by suctioning air using a wind box 40 provided below the pallet 34. Here, the negative pressure means that the pressure inside the ignition furnace 36 is lower than that outside the furnace 36.

[0068] Referring again to FIG. 1 , the exhaust fan 46 is a device that sucks gas from the main duct 42, and is, for example, a blower or a pump. The exhaust fan 46 sucks gas from the main duct 42, thereby creating a negative pressure in the wind box 40 connected to the main duct 42. When the negative pressure is created in the wind box 40, the wind box 40 sucks air from the inside of the sintering bed S, and the pressure above the sintering bed S in the ignition furnace 36 becomes negative. Here, "above the sintering bed S" refers to the space above the sintering bed S, which is covered by the ignition furnace cover 74. However, the pressure above the sintering bed S may be represented by the pressure measured inside the ignition furnace cover 74. In this case, the pressure is preferably measured downstream of the ignition furnace 36, and more preferably near the center of the sintering bed 36 in the width direction.

[0069] In this way, the wind box 40 creates a negative pressure above the sintering bed S in the ignition furnace 36. The pressure above the sintering bed S in the ignition furnace 36 is preferably 2 to 10 kPa lower than the pressure outside the ignition furnace 36. By creating a negative pressure above the sintering bed S, water vapor generated by the combustion of fuel gas by the ignition furnace burner 72 is drawn into the sintering bed S from above the sintering bed S. In addition, dust generated by the ignition of the sintering bed S is prevented from floating above the sintering bed S. This allows the radiation emitted from the surface of the sintering bed S to pass through the measurement window 86 without being disturbed by water vapor or dust generated inside the ignition furnace 36. As a result, the surface temperature of the sintering bed S can be measured with even higher accuracy using the radiation thermometer 84.

[0070] Specifically, if the fuel gas used in the ignition furnace burner 72 contains hydrogen (H2) or methane (CH4), water vapor is generated by the combustion of this fuel gas. Figure 11 is a graph showing the transmittance of light passing through water vapor. The horizontal axis of Figure 11 represents wavelength (μm), and the vertical axis represents transmittance (%).

[0071] As shown in Fig. 11, water vapor reduces the transmittance of a part of the wavelength range of 0.5 µm or more and 4.0 µm or less (3 to 4 µm range) that is the measurement wavelength of the radiation thermometer 84. The water vapor in the ignition furnace 36 attenuates the radiation light emitted from the surface of the charging bed S, and therefore the light intensity received by the radiation thermometer 84 installed outside the measurement window 86 decreases. Therefore, by drawing the water vapor in the ignition furnace 36 into the charging bed S, the attenuation of the radiation light due to the water vapor is suppressed, and the surface temperature of the charging bed S can be measured with high accuracy by the radiation thermometer 84 installed outside the measurement window 86.

[0072] As described above, the temperature measurement method for the ignition furnace 36, the sintering machine 30, and the charging bed S according to this embodiment includes a radiation thermometer 84 that is provided outside the ignition furnace cover 74 and measures the surface temperature of the charging bed S through the measurement window 86. By providing the radiation thermometer 84 outside the ignition furnace cover 74 in this manner, deterioration in the durability and maintainability of the radiation thermometer 84 can be suppressed. Furthermore, the radiation thermometer 84 measures a wavelength selected from the range of 0.5 μm to 4.0 μm. This suppresses attenuation of the radiant light emitted from the charging bed S, even in the presence of the flame 98 sprayed from the ignition furnace burner 72 or carbon dioxide generated by the combustion of fuel gas. Furthermore, since the transmittance of the measurement wavelength through the measurement window 86 is 50% or more, attenuation of the radiant light passing through the measurement window 86 can be suppressed. Due to these effects, the temperature measurement method for the ignition furnace 36, the sintering machine 30, and the charging bed S according to this embodiment enables the surface temperature of the charging bed S to be measured with high accuracy.

[0073] Furthermore, in the temperature measurement method of the ignition furnace 36, the sintering machine 30, and the sintering bed S according to this embodiment, it is preferable to use the wind box 40 to create a negative pressure above the sintering bed S in the ignition furnace 36. This reduces the influence of water vapor and dust on the radiant light emitted from the sintering bed S. As a result, the surface temperature of the sintering bed S can be measured with even higher accuracy through the measurement window 86 using the radiation thermometer 84 provided outside the ignition furnace 36.

[0074] Next, a method for controlling the ignition furnace 36 according to this embodiment and a method for producing sintered ore 56 using the control method will be described. Fig. 12 is a graph showing the relationship between the flow rate of the fuel gas supplied to the ignition furnace burner 72 and the surface temperature or heat retention index of the sintering bed S.

[0075] In the example shown in Fig. 12, coke oven gas (C gas) was used as the fuel gas for the ignition furnace burner 72. The flow rate of the fuel gas on the horizontal axis is the flow rate of the fuel gas (Nm 3 / (h m)). The radiation thermometer 84 used to measure the surface temperature of the charging bed S is a thermograph capable of measuring the surface temperature distribution of the charging bed S. The measuring element is InGaAs, the measuring wavelength is 1.55 μm, and the measuring window 86 is quartz glass. Air was sucked in from the wind box 40, and the pressure inside the ignition furnace 36 was controlled to be 5 kPa lower than the outside pressure.

[0076] 12(a) is a graph showing an example in which the spot temperature at the widthwise center of the sintering bed S is measured as the surface temperature of the sintering bed S. The spot temperature at the widthwise center is measured using surface temperature data at a position 100 mm away from the ignition unit 99 in the ignition furnace 36 in the conveying direction of the pallet 34. In this way, the spot temperature at the widthwise center of the sintering bed S may be used as the surface temperature of the sintering bed S.

[0077] 12(b) is a graph showing an example in which the average temperature in the width direction of the sintering bed S is used as the surface temperature of the sintering bed S. The average temperature in the width direction of the sintering bed S was calculated from the surface temperature distribution data at a position 100 mm away from the ignition part 99 in the ignition furnace 36 in the conveying direction of the pallet 34. In this way, the average temperature in the width direction of the sintering bed S may be used as the surface temperature of the sintering bed S.

[0078] Fig. 12(c) is a graph showing an example in which the heat retention index of the sintering bed S is used as the surface temperature of the sintering bed S. The heat retention index is a value obtained by integrating the temperature at or above a preset lower limit temperature over the retention time, and in the example shown in Fig. 12(c), the heat retention index was calculated with the lower limit temperature set to 1000°C.

[0079] FIG. 13 is a graph showing the change in surface temperature of the sintering bed S over time from ignition. The heat retention index is the area Sk of the sintering bed S where the surface temperature is maintained at 1000°C or higher, assuming that the lower limit temperature is 1000°C, in the graph showing the change in surface temperature over time from ignition shown in FIG. 13. The change in surface temperature of the sintering bed S over time was measured by thermography downstream of the ignition unit 99 in the ignition furnace 36 in the conveying direction of the pallets 34, and temperature data in the longitudinal direction at the center of the sintering bed S in the width direction was extracted from the surface temperature distribution data. The change in surface temperature over time is calculated from this temperature data and the conveying speed of the pallets 34, and the retention time for the temperature to be maintained at 1000°C or higher can be calculated from the change in surface temperature over time. In this way, the heat retention index obtained from the surface temperature may be used as the surface temperature of the sintering bed S.

[0080] Referring again to FIG. 12, as shown in FIGS. 12(a) to 12(c), increasing the flow rate of the fuel gas supplied to the ignition furnace burner 72 increased the spot temperature at the width direction center, the width direction average temperature, and the heat retention index. Therefore, for example, when the preset temperature range is 1200 to 1280°C, it can be seen that the spot temperature at the width direction center and the width direction average temperature can be controlled within the preset temperature range by controlling the flow rate of the fuel gas used in the ignition furnace burner 72. It can also be seen that, for example, when the preset heat retention index range is 1600 to 3400°C·s, the heat retention index of the sintering bed S can be controlled within the preset heat retention index range by controlling the flow rate of the fuel gas supplied to the ignition furnace burner.

[0081] Figure 14 is a graph showing the relationship between the measurement results of the surface temperature of the sintering bed shown in Figure 12 and the yield of sintered ore. Figure 14(a) is a graph showing the relationship between the spot temperature at the center of the width direction and the yield of sintered ore. Figure 14(b) is a graph showing the relationship between the average temperature in the width direction and the yield of sintered ore. Figure 14(c) is a graph showing the relationship between the heat retention index and the yield of sintered ore.

[0082] 14(a) to 14(c) show that the sintered ore yield is correlated with the spot temperature at the widthwise center of the sintering bed S, the widthwise average temperature, and the heat retention index, all of which are measured by the radiation thermometer 84 of the ignition furnace 36. Also, as shown in FIGS. 14(a) to 14(c), the sintered ore yield exhibited maximum values ​​for the spot temperature at the widthwise center, the widthwise average temperature, and the heat retention index. Therefore, the temperature ranges of the widthwise center spot temperature and the widthwise average temperature, and the heat retention index, at which the sintered ore yield exhibits maximum values, are preset, and the flow rate of the fuel gas supplied to the ignition furnace burner 72 is controlled so that these fall within the preset ranges. This demonstrates that sintered ore can be produced with a high yield using the sintered ore production apparatus 120.

[0083] Next, we will explain the control of the ignition furnace 36 by the control device 100. The control device 100 controls the operation of the sintered ore manufacturing apparatus 120, including the ignition furnace 36, in accordance with production instructions from a host computer (not shown) that provides production instructions to the sintered ore manufacturing apparatus 120.

[0084] 15 is a diagram schematically illustrating an example configuration of the control device 100. The control device 100 is, for example, a general-purpose computer such as a workstation or a personal computer. The control device 100 has a control unit 102, an input unit 104, an output unit 106, and a storage unit 108. The control unit 102 is, for example, a CPU, and executes various programs stored in the storage unit 108, causing the control unit 102 to function as a temperature acquisition unit 110 and a combustion control unit 112.

[0085] The input unit 104 is, for example, a keyboard, a touch panel integrated with a display, or the like. The output unit 106 is, for example, an LCD or CRT display, or the like. The storage unit 108 is, for example, an updatable flash memory, a built-in hard disk or a hard disk connected via a data communication terminal, an information recording medium such as a memory card, or a read / write device for the information recording medium. The storage unit 108 stores programs and data for realizing the production of sintered ore 56 by the sintered ore production apparatus 120. The storage unit 108 also stores, via the input unit 104, the temperature range of the widthwise center spot temperature, the widthwise average temperature, or the range of the heat retention index that can maximize the sintered ore yield.

[0086] The control device 100 is connected to the radiation thermometer 84 by wire or wirelessly. The temperature acquisition unit 110 acquires measurement data of the surface temperature of the sintering bed measured by the radiation thermometer 84 at predetermined intervals and outputs the acquired measurement data to the combustion control unit 112. The combustion control unit 112 calculates the spot temperature at the center of the width direction, the average temperature in the width direction, or the heat retention index from the acquired measurement data. The combustion control unit 112 reads the set temperature range or heat retention index range from the memory unit 108 and controls the flow rate of the fuel gas supplied to the ignition furnace burner 72 so that the temperature falls within the set range.

[0087] The combustion control unit 112 adjusts the aperture of the fuel gas flow rate control valve 90 to control the flow rate of fuel gas supplied to the ignition furnace burner 72. The combustion control unit 112 may adjust the aperture of the air flow rate control valve 94 in accordance with the adjustment of the aperture of the fuel gas flow rate control valve 90 to maintain a constant air ratio during combustion in the ignition furnace burner 72. As shown in FIGS. 12(a) to 12(c), the spot temperature at the width direction center, the average width direction temperature, and the heat retention index increase as the flow rate of the supplied fuel gas increases, and decrease as the flow rate of the fuel gas decreases. Therefore, the combustion control unit 112 increases the aperture of the fuel gas flow rate control valve 90 when the calculated spot temperature at the width direction center, the average width direction temperature, or the heat retention index is lower than a preset temperature range or heat retention index range, and decreases the aperture of the fuel gas flow rate control valve 90 when the calculated spot temperature at the width direction center, the average width direction temperature, or the heat retention index is higher than the preset temperature range or heat retention index range. This allows the combustion control unit 112 to control the spot temperature at the center of the width direction, the average temperature in the width direction, and the heat retention index within a preset range, thereby enabling the sintered ore 56 to be produced with a high yield using the sintered ore production apparatus 120.

[0088] As described above, by using the control method for the ignition furnace 36 according to this embodiment and the method for producing sintered ore 56 using this control method, the surface temperature of the charging bed S ignited in the ignition furnace 36 can be controlled within a temperature range that maximizes the yield of the sintered ore 56. This makes it possible to produce sintered ore 56 with a high yield using the sintered ore production apparatus 120. [Example]

[0089] As an example of the present invention, an example in which the temperature distribution in the width direction of the sintering bed S was measured using the ignition furnace 36 of the above embodiment will be described. In this example, the temperature distribution in the width direction of the sintering bed S transported by the pallet 34 was measured using the ignition furnace 36 shown in Figures 2 and 3. The temperature distribution in the width direction of the sintering bed S was measured at a position 100 mm downstream of the ignition part 99 where the flame 98 injected from the burner nozzle 76 collides.

[0090] The radiation thermometer 84 used for temperature measurement was a scanning radiation thermometer capable of scanning the field of view in one axial direction, and was positioned so as to scan in the width direction of the charging bed S. Quartz glass or borosilicate glass was used as the measurement window 86, and temperature measurements were performed using each. The measurement element used in the radiation thermometer 84 was a photoelectric detection element, and lead selenide (measurement wavelength: 4 μm), indium gallium arsenide (measurement wavelength: 1.55 μm), and silicon (measurement wavelength: 0.9 μm) were used. On the other hand, as a comparative example, a radiation thermometer having a thermoelectric detection element with a measurement wavelength of 8 to 13 μm was used. The pressure above the charging bed S was controlled to be 5 kPa lower than the pressure outside the ignition furnace 36.

[0091] Figure 16 is a graph showing the results of measuring the temperature distribution in the width direction of the sintering bed. The horizontal axis of Figure 16 represents the position (mm) in the width direction of the pallet, and the vertical axis represents the temperature (°C). The measured values ​​shown in this graph are an example of direct temperature conversion from the radiation light received by the radiation thermometer, and are temperatures that have not been corrected for the transmittance of the measurement window 86 using the above equations (1) and (2). The contact thermometer plot shown in the figure is the result of measuring the surface temperature of the sintering bed S using a contact thermometer after temporarily opening the measurement window 86 on the surface of the sintering bed S that was measured with a scanning radiation thermometer.

[0092] Figure 16(a) is a graph showing the measurement results when quartz glass was used as the measurement window 86. As shown in Figure 16(a), when photoelectric detection elements of indium gallium arsenide (1.55 μm) and silicon (0.9 μm) were used as the measurement element of the radiation thermometer, the temperature measured by the radiation thermometer and the temperature measured by the contact thermometer agreed, confirming that the surface temperature of the charging bed S could be measured with high accuracy. As shown in Figure 6, quartz glass has a transmittance of 92% at measurement wavelengths of 3.2 μm or less, so it is thought that the surface temperature of the charging bed could be measured with high accuracy using a radiation thermometer installed outside the measurement window 86. In contrast, when lead selenide (4 μm) was used as the measurement element of the radiation thermometer, the transmittance of quartz glass was 70%, so when the radiation received by the radiation thermometer was directly converted to temperature, the temperature was about 10% lower than when indium gallium arsenide or silicon was used. However, since the transmittance of quartz glass is 70%, which is greater than 50%, by correcting using the above formulas (1) and (2), the corrected surface temperature matched the measurement result using the contact thermometer. On the other hand, when a detection element with a measurement wavelength of 8 to 13 μm was used as a comparative example, the quartz glass blocked the radiant light from the charging bed S, and the surface temperature of the charging bed S could not be measured.

[0093] Figure 16(b) is a graph showing the measurement results when borosilicate glass was used as the measurement window. As shown in Figure 16(b), when photoelectric detection elements of indium gallium arsenide (1.55 μm) and silicon (0.9 μm) were used as the radiation thermometer's measurement element, the temperature measured by the radiation thermometer and the temperature measured by the contact thermometer were consistent, confirming that the surface temperature of the charging bed S could be measured with high accuracy. As shown in Figure 6, borosilicate glass has a transmittance of 92% at measurement wavelengths of 2.0 μm or less. This is thought to be why the surface temperature of the charging bed S could be measured with high accuracy using a radiation thermometer installed outside the measurement window 86. In contrast, when lead selenide (4 μm) was used as the radiation thermometer's measurement element or when a detection element with a measurement wavelength of 8 to 13 μm was used, the transmittance of borosilicate glass was close to 0%, so the borosilicate glass blocked the radiated light from the charging bed S, making it impossible to measure the surface temperature of the charging bed S. [Explanation of symbols]

[0094] 10 Blending tank 12 Surge Hopper 14. Mixed material conveyor 16 Drum Mixer 18 Sintering raw materials 20 Sintering material transport conveyor 30 Sintering machine 32 Sintering raw material charging device 34 palettes 36 Ignition Furnace 38 Gaseous fuel supply device 40 Wind Box 42 Main Duct 44 Dust collector 46 Exhaust fan 48 Chimney 60 Feeding Hopper 62 Drum Feeder 64 Charging gate 66 shots 70 Baffle 72 Ignition furnace burner 74 Ignition furnace cover 76 Burner nozzle 80 Top cover 82 Side cover 84 Radiation thermometer 86 Measuring window 88 Pallet side panel 90 Fuel gas flow control valve 92 Fuel gas flow meter 94 Air flow control valve 96 Air flow meter 98 Flame 99 Ignition part 100 control device 102 Control section 104 Input section 106 Output section 108 Storage section 110 Temperature acquisition section 112 Combustion control unit 120 Sintered ore manufacturing equipment

Claims

1. An ignition furnace used in the production of sintered ore, which comprises charging raw materials for sintering including a carbonaceous material onto an endless moving pallet to form a charging bed, and then burning the carbonaceous material in the charging bed to sinter the raw materials for sintering, an ignition furnace burner for igniting the carbonaceous material on the surface of the sintering bed; an ignition furnace cover covering the charging bed; a measurement window provided in the ignition furnace cover and positioned so that the surface inside the ignition furnace can be directly viewed; a radiation thermometer provided on the outside of the ignition furnace cover and configured to measure the temperature of the surface through the measurement window; an ignition furnace, wherein the measurement wavelength of the radiation thermometer is a wavelength selected from the range of 0.5 μm or more and 4.0 μm or less, and the transmittance of the measurement wavelength through the measurement window is 50% or more.

2. The ignition furnace according to claim 1 , wherein the radiation thermometer measures a surface temperature of an ignition part ignited by a flame jetted from the ignition furnace burner.

3. 2. The ignition furnace according to claim 1, wherein the detecting element of the radiation thermometer is made of any one of lead selenide (PbSe), lead sulfide (PbS), indium gallium arsenide (InGaAs), and silicon (Si).

4. 3. The ignition furnace according to claim 2, wherein the detecting element of the radiation thermometer is made of any one of lead selenide (PbSe), lead sulfide (PbS), indium gallium arsenide (InGaAs), and silicon (Si).

5. 2. The ignition furnace according to claim 1, wherein the window material of the measurement window is quartz glass.

6. 3. The ignition furnace according to claim 2, wherein the window material of the measurement window is quartz glass.

7. 4. The ignition furnace according to claim 3, wherein the window material of the measurement window is quartz glass.

8. 5. The ignition furnace according to claim 4, wherein the window material of the measurement window is quartz glass.

9. A sintering machine having the ignition furnace according to any one of claims 1 to 8, a sintering raw material charging device that charges the sintering raw material onto the pallet; a wind box provided below the pallet for sucking air from inside the charging bed; The sintering machine creates a negative pressure above the sintering bed inside the ignition furnace by suctioning the air.

10. A method for controlling an ignition furnace according to any one of claims 1 to 8, comprising: a control method for an ignition furnace, the method comprising controlling a flow rate of fuel gas supplied to the ignition furnace burner so that the surface temperature of the ignition furnace measured by the radiation thermometer is within a predetermined temperature range.

11. A method for producing sintered ore, comprising producing sintered ore using the method for controlling an ignition furnace according to claim 10.

12. A method for measuring the temperature of a charging bed in an ignition furnace used in the production of sintered ore, in which sintering raw materials including carbonaceous materials are charged into an endless moving pallet to form a charging bed, and then the carbonaceous materials in the charging bed are combusted to sinter the sintering raw materials, The carbonaceous material on the surface of the sintering bed is ignited by an ignition furnace burner, The temperature of the surface inside the ignition furnace cover is measured through a measurement window provided in the ignition furnace cover covering the charging bed using a radiation thermometer provided outside the ignition furnace cover; a measurement wavelength of the radiation thermometer selected from the range of 0.5 μm or more and 4.0 μm or less, and a transmittance of the measurement wavelength through the measurement window of 50% or more.

13. The method for measuring the temperature of a sintered bed in an ignition furnace according to claim 12, wherein a pressure above the sintered bed inside the ignition furnace is made negative.

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