JPS6241300B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is an improvement in a method and apparatus for recovering sensible heat possessed by sintered ore (hereinafter referred to as sintered lump) on a sintering machine when fine ore is continuously sintered in a Dwight Lloyd type sintering machine. This is related to. A method for recovering sensible heat contained in a sintered mass on a conventional Dwight Lloyd sintering machine will be explained with reference to FIGS. 1 and 2. First, the main components of the device are, as shown in Fig. 1, a row of pallets P fitted in an endless strip between sprockets S on both the left and right sides, and a wind box B disposed opposite to the upper row of pallets P. column, duct d as a ventilation mechanism connected to this, damper D, main ducts 8 and 9, blower,
Booster 1', dust collector 2, stack 3, exhaust air supply hood H, and pallet P, bedding ore feeder 4 and raw material feeder 5 for supplying bedding ore and raw materials for sintering, respectively, and the surface layer of raw material layer 10. It consists of an ignition furnace 6 for igniting the sinter, an ore discharge section 7 for taking out the contents of the pallet P after the sintering reaction, that is, the sintered lumps, from the pallet P. Next, the operating process for this type of device is the same as the first step.
As shown in the figure and FIG. 2, first, the bedding ore feeder 4 and the raw material feeder 5 on the left side of the drawing feed the bedding ore 11 and its top into the moving pallet P (indicated by a broken line in FIG. 2). After the raw material is continuously supplied to the raw material layer 1, when passing directly under the ignition furnace 6, the raw material layer 1
0 is ignited on the surface, and while it moves further to the right,
Air X for combustion and cooling or high-temperature exhaust air Y, which is a mixed gas of air and exhaust gas from the sintering machine, is sucked from above the pallet P by the wind box row B and the ventilation mechanism connected thereto. Due to the downward ventilation, the raw material layer 10
The sintering reaction and cooling of the sintered mass are sequentially carried out in raw material layer 1.
0, reaches the bedding layer 11 on the grate in the pallet P, and after the exhaust air temperature has further decreased to a predetermined temperature, the pallet P is Expelled from within. By the way, in the final stage of sintering when the pallet P moves closer to the ore discharge area 7, as shown in FIG.
As shown in the lower half of Fig. 2, the temperature of the exhaust air discharged to the wind box B located below the pallet P to approach or reach the pallet P and the grate 12 increases significantly, and the maximum temperature is approximately 400℃. It also becomes ℃. In other words, the sensible heat held by the sintered mass is transferred to the gas passing through the layer, causing the exhaust air temperature to rise. Therefore, in the past, in order to recover the heat transferred from the sintered mass to the exhaust air, as shown in Figure 1,
The high-temperature exhaust air discharged from below the pallet P located after the second half of sintering process is transferred to the wind box B.
The sensible heat of the high-temperature exhaust air is collected in the main duct 9 via the duct d, and then guided to the exhaust air supply hood H by the booster 1' and supplied into the raw material layer 10 as a sintering gas. It is used for preheating. For this reason, the sensible heat possessed by the sintered mass is recovered in a manner that allows the amount of coke in the raw material to be reduced. In the sintering process in the conventional method for recovering the sensible heat of the sintered mass as described above, downward ventilation is performed throughout the entire process, so in the final stage of sintering, the raw material The sintering reaction zone in the layer 10 reaches the bedding layer 11, and the downward high temperature gas passing through the high temperature sintered mass and the sintering reaction zone causes the grate 12 and pallet frame 13 (not shown) to )
The progress is as shown in the figure, and the temperature is about 1000℃ and about 100℃, respectively.
Immediately before the sintered lump is heated to 350°C and discharged from the ore discharge section 7, a temperature distribution 14 as shown in Fig. 3 is formed in the sintered lump layer 15, plate 12, and pallet frame 13, A large thermal stress is generated in the grate 12 and the pallet frame 13,
Serious defects such as deformation and crack formation frequently occur. In addition, an increase in the temperature of the grate 12 and pallet frame 13 means that the temperature of the exhaust air at the stage when it is discharged to the wind box B below is low, which also has the disadvantage of a low recovery rate of sensible heat. . Furthermore, although the high temperature exhaust air Y supplied from the surface layer of the raw material or sintered mass is approximately 250°C, it is a low temperature compared to the temperature of the sintering reaction rate in the raw material layer 10 (approximately 1400°C). Therefore, the upper part of the sintered lump layer 15 is rapidly cooled, and thermal distortion remains in the sintered mineral product, which causes low-temperature reduction and powdering, which is an undesirable phenomenon for blast furnace operation, when used in a blast furnace. There were also some flaws that could easily occur. The present invention is proposed in order to eliminate the above-mentioned drawbacks associated with the conventional method of recovering the sensible heat of the sintered mass on the Dwight Lloyd type sintering machine. In the Lloyd type sintering machine, the sintering reaction zone formed by ignition from the top surface of the raw material layer moves toward the grate at the bottom of the layer due to downward ventilation, and as it approaches the bedding layer, the waste gas discharged from the bottom surface of the layer moves toward the grate at the bottom of the layer. The air temperature starts to rise, and after a slight delay, the pallet frame temperature also starts to rise, but until sintering is completed, the inside of the exhaust air discharged downward from the bottom of the raw material layer or sintered lump layer , Collect all or part of the exhaust air from the sintering section from the time when the temperature of the exhaust air just before it starts to rise (e.g. 60℃) to the time when it reaches 140℃ or more (preferably about 170℃). Afterwards, this sintering method is characterized in that the exhaust air is introduced from below the raw material layer or the sintered lump layer in the final stage of sintering, that is, from the grate side toward the surface surface, and the exhaust air is recovered. The present invention relates to a method and apparatus for collecting sensible heat of concretions. The details of the present invention will be explained below with reference to an embodiment of the present invention shown in FIG. Incidentally, as for the constituent parts of the apparatus, the reference numbers and numbers shown in FIG. 1 are used for the same constituent members as those of the apparatus for carrying out the conventional method. The basic structure of the apparatus for carrying out the method of the present invention is almost the same as that of the conventional apparatus shown in FIG. To explain the difference here, in the conventional method, when the sintering reaction of the raw material layer and the cooling of the sintered lump layer are carried out by downward ventilation throughout the entire process from the early stage of sintering to the final stage of sintering, The high-temperature exhaust air discharged from below the pallet P, which is located only in the process of
However, in the present invention, sintering starts from the initial stage of sintering. Until it is completed,
Until the exhaust air temperature rises to 140°C or higher (preferably about 170°C) (below 140°C, it is disadvantageous for the use of sensible heat), the sintering reaction of the raw material layer and the cooling of the sintered lump layer are carried out by downward ventilation. Among the exhaust air discharged downward, all or part of the exhaust air from the sintering section whose temperature is above the temperature immediately before the exhaust air temperature starts to rise (for example, 60°C) is collected into the main duct 9a. ,
The booster 21 passes through the main duct 9b, damper D, duct d, and wind box B.
For the raw material layer or sintered lump layer in the final stage of sintering, from below the layer toward its surface surface,
In other words, it has a structure that introduces it upward and collects it. That is, the present invention first collects hot exhaust air (average temperature of about 120°C) corresponding to the window box B where there is no number indicating the position in the conventional downward draft sintering process shown in FIG. I care. During this period, the temperature of the pallet frame only rose to a maximum of 170°C, and the temperature of the top surface of the grate only rose to a maximum of 650°C. Therefore, the collected hot exhaust air of approximately 120°C is directed from the grate direction into the raw material layer or sintered lump layer, toward the surface layer thereof, from the grate direction to the subsequent wind box at the final stage of sintering, that is, upward. 5, the grate and pallet frame are rather cooled by this heated exhaust air, and the temperature rise stops as shown in FIG. For this reason, first, the thermal stress on the grate and pallet frame is greatly reduced compared to the conventional method, and defects such as deformation cracks due to thermal stress are less likely to occur. In addition, the upper part of the sintered lump layer, which is rapidly cooled and contains thermal distortion, is annealed by the high-temperature exhaust air rising from below, so the thermal distortion in the sintered lump is removed, and the finished product is In addition to improving the strength of the steel, the low-temperature reduction powdering rate, which is an index of powdering property due to reduction in the blast furnace, decreases, resulting in an improvement in quality. In addition, since the temperature of the grate and pallet frame does not rise as much as in the conventional method, the hot exhaust air introduced from below the raw material or sintered mass layer can absorb the large sintered mass possessed by the high temperature sintered mass at the final stage of sintering. Sensible heat can be absorbed effectively, and since the exhaust air is already at about 120℃ and is introduced with a considerable amount of sensible heat, it is discharged from the surface of the sintered lump layer. At the sintering stage, the temperature reaches approximately 450°C or higher, which is higher than the temperature obtained in the conventional method. The amount of added coke can be further reduced compared to the conventional method. That is, in FIG. 4, the high-temperature exhaust air discharged from the surface of the sintered lump layer at the final stage of sintering is collected in the high-temperature exhaust air collection hood 22, and then sent to the exhaust air supply hood H by the booster 23. Thereafter, the material is introduced into the raw material or sintered mass layer from the upper part of the row of pallets P, which is in the process of sintering reaction. In addition, the high temperature of the exhaust air obtained at the final stage of sintering is approximately 450°C or higher, which means that it can be used not only for sintering as shown in Figure 4, but also for power generation, etc., making it suitable for high temperature exhaust air applications. Expanded benefits also arise. Furthermore, in Fig. 2, when the dry zone in the raw material layer approaches the grate below due to downward draft, that is, after the stage where the temperature of the exhaust air just starts to rise at the position of the wind box B number, the exhaust air is Since the concentration of SOx is also high, the present invention divides this section where the SOx concentration is high almost in half, and the exhaust air obtained from almost the first half of the section where the SOx concentration is high is used almost as it is in the section where the SOx concentration is high. Since it will be circulated almost to the latter half of the
In the end, SOx will be concentrated approximately twice as much in the high-temperature exhaust air obtained from the surface layer of the sintered lump layer at the end of sintering, which also has the advantage of facilitating the desulfurization treatment of the exhaust gas. In addition, in Fig. 4, in order to prevent a short circuit in the ventilation between adjacent wind boxes B having different ventilation directions, and to provide normal downward or upward ventilation to the contents of the pallet P passing through the upper part thereof. In addition, it is desirable to provide the dead plate _A3 at a position corresponding to the time when the temperature of the hot exhaust air discharged from below the grate due to downward ventilation reaches approximately 170°C. As shown in Figure 2, this period can be determined from information such as the above-mentioned exhaust air temperature, the pressure loss in the formation, the SOx concentration in the exhaust air, and the exhaust air volume. Next, Table 1 shows the comparison results in various respects between the method of the present invention and the conventional method.

[Table] The above is a method in which the sintered lump is cooled to 600 to 700℃ on a sintering machine, then discharged from the sintering machine, and cooled to a low temperature in a subsequent cooling machine. This is an example in which the method of the present invention is applied to this off-strand cooling sintering method, which is called the cooling method sintering method. The method of the present invention can be applied to the so-called on-strand cooling sintering method in which the sintering method is carried out in the same way as the off-strand cooling sintering method. FIG. 6 is an example of a device showing an embodiment in that case. In addition to the off-strand cooling type ventilation mechanism shown in FIG. 4, a separate upward ventilation mechanism, a blower 32, A main duct 30, a damper D, a duct B, a wind box B, and an air collection hood 31, etc. are attached as shown in the figure, facing the upper surface of the pallet P, and its function and effect are based on the off-strand cooling method. This is equivalent to the case of the method of the present invention adopted in . However, it is not limited to the above embodiments,
Of course, various changes can be made without departing from the spirit of the invention. As detailed above, according to the present invention, the exhaust air temperature is 140°C from the early stage of sintering to the first half of the second half of sintering.
Until the temperature rises above this level, the sintering reaction of the raw material layer and the cooling of the sintered lump layer are performed by downward ventilation. All or part of the exhaust air from the sintering section is collected in a separate system, and then directed toward the subsequent raw material layer or sintered lump layer at the final stage of sintering from below the same layer toward its surface. In other words, by introducing the sintered ore upward and collecting it, it not only effectively prevents burnout and deformation of the grate and pallet frame due to thermal stress, but also improves the quality of the sintered ore and reduces waste heat. Significant effects such as diversification of uses due to the improved temperature level of recovery and recovered waste heat and increased efficiency of desulfurization treatment of exhaust gas can be obtained, and it is also possible to reduce the operation and maintenance costs of the sintering machine. There are great things to contribute to industry.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the conventional sensible heat recovery method of the sintered mass in off-strand cooling sintering. Figure 2 is an explanatory diagram of the sintering process in the conventional off-strand cooling sintering method. Figure 3 is a cross-sectional view of the pallet P section in the sintering machine, Figure 4 is an example of an apparatus for applying the method of the present invention to the off-strand cooling type sintering method, and Figure 5 is a cross-sectional view of the pallet P section in the sintering machine. An example of the sintering process when the method of the present invention is applied to the off-strand cooling method sintering method, FIG. 6 shows an example of the sintering process when the method of the present invention is applied to the on-strand cooling method sintering method. 1A and 1B are schematic diagrams each showing an embodiment of the apparatus; FIG. 1: Blower, 1': Booster, 2: Dust collector,
3: Stack, 4: Bed ore feeder, 5: Raw material feeder, 6: Ignition furnace, 7: Ore discharge section, 8, 9, 9a, 9
b: Main duct, 10: Raw material layer, 11: Bedding layer, 12: Grate, 13: Pallet frame,
15: Sintered lump layer, 20: Dust collector, 21: Booster, 22: High temperature exhaust air collection hood, 23: Booster, 24: Discharge duct, 25, 26: Damper, 3
0: Main duct, 31: Air collection hood, 32: Blower, _A1-3 : Dead plate, B: Wind box, d: Duct, D: Damper, H: Exhaust air supply hood, P: Pallet, S: Sprocket.

Claims (1)

[Claims] 1. A Dwight Lloyd sintering machine with off-strand cooling method or on-strand cooling method for producing sintered ore by sintering raw materials consisting of fine ore, flux, solid fuel, etc. , from the sintering start point where the surface layer of the raw material charged into the pallet is ignited to the completion of sintering of the raw material, the temperature of the exhaust air directly below the pallet reaches 140°C.
Sintering and cooling of the sintered mass are performed by downward ventilation until the temperature rises above ℃, and within this downward ventilation section, the temperature of the exhaust air immediately below the pallet is at least the temperature immediately before it starts to rise, or A part of the exhaust air is collected in a separate system, and this hot exhaust air is introduced upward to the raw materials and sintered mass in the pallet in the subsequent section, and the high-temperature exhaust air is collected on the top surface of the pallet. A method for recovering sensible heat from a sintered mass. 2 Pallets fed by an ore feeder to a wind box row installed in close opposition to a pallet row connected and transferred in an off-strand cooling method or an off-strand cooling method Dwight Lloyd sintering machine. From the sintering start point when the raw material inside is ignited in the ignition furnace until the sintering of the raw material is completed, the contents of the pallet will be The pallet is equipped with a ventilation mechanism that generates downward ventilation, and within the downward ventilation, all or part of the exhaust air from the wind box whose temperature is higher than the temperature immediately before the exhaust air temperature immediately below the pallet starts to rise is used. It has a selective collection mechanism,
Furthermore, an air guide mechanism is installed directly below the pallet that can introduce the collected hot exhaust air upward into the contents at the final stage of sintering, and a mechanism that collects the high-temperature exhaust air that has passed through the contents. A device for recovering sensible heat from a sintered mass, characterized in that the sintered mass sensible heat recovery device is provided with the following elements facing each other on the upper surface of the pallet.