JP5061481B2 - Dry preheating equipment for blast furnace raw materials - Google Patents

Description

  The present invention relates to a drying preheating apparatus for blast furnace charging materials such as iron ore and coke, and in particular, by drying and preheating the blast furnace raw material, charging of the blast furnace raw material is avoided and stable operation of the blast furnace is aimed at. Regarding technology.

  In a blast furnace, iron ore, coke, and a coagulant are charged into the furnace from the top of the furnace, and high temperature air or high temperature air enriched with oxygen is blown into the furnace from the bottom of the furnace to burn the coke. Hot metal is produced by reducing and melting iron ore using heat and CO gas generated by combustion. The raw material charged from the top of the furnace is adjusted to a granularity of several mm to several tens of mm and charged into the furnace, so the combustion gas generated by the combustion of coke at the lower part of the furnace is granular filled in the furnace. The gap between the raw materials will rise toward the furnace top.

  Since heat supply to the raw material is mainly performed by heat transfer from this combustion gas, if the flow of the combustion gas in the furnace is not in an appropriate state, the temperature rise of the raw material becomes unstable, resulting in reduction or melting of iron ore. It will cause trouble.

  Therefore, in order to make the gas flow in the furnace appropriate, the furnace top charging device for charging the raw material of the appropriate particle size to the appropriate position in the furnace when the raw material in the furnace top enters the furnace. And the development of furnace top charging methods are underway.

  However, even if such a raw material charging apparatus and method are elaborated, if powder is mixed into the raw material itself, charging of the powder raw material into the furnace cannot be avoided, and the above gas flow It becomes difficult to optimize.

  The raw materials used in the blast furnace are stored in an open-air storage area called a yard once manufactured and directly sent to the blast furnace raw material tank after grain size adjustment after being manufactured in a sintering machine or coke oven. After that, this material is collected again and sent to the blast furnace raw material tank, and some iron ore is stored in the yard in granular form after it arrives at the factory. Some raw materials are sent to the raw material tank. Among these raw materials, those that are sent to the blast furnace raw material tank after being stored in the yard are inevitably wet with rainwater when stored in the yard, and the moisture content becomes several mass%. Some raw materials have a water content exceeding 10 mass%.

  In such a raw material with a large amount of water, the powder raw material adheres to the raw material particles due to water, and thus the powder raw material may not be removed even if the particle size is adjusted by a sieve or the like. Moreover, since the powder raw material containing such moisture easily adheres to the sieve net itself, it causes clogging of the sieve, and as a result, there is a problem that sieving of the raw material becomes more difficult.

  The powder raw material that could not be removed from the granular raw material by the sieve is transported to the top of the furnace while being attached to the granular raw material, and when it is inserted into the furnace, it is dried by the heat in the furnace and detached from the surface of the granular raw material. In some cases, the raw material flows in the gap between the raw materials in the furnace, and in some cases, the granular raw material accumulates in the gap between the raw materials to inhibit the gas flow in the furnace.

  Therefore, it can be said that the technique of removing the powder raw material adhering to the blast furnace raw material is as important as the raw material charging technique in the blast furnace furnace.

Conventionally, from the viewpoint of preheating the blast furnace raw material, in Patent Document 1, before weighing the blast furnace raw material, atmospheric gas or exhaust gas discharged from a blast furnace dry pit, a metallurgical heating furnace or other hot air generating source is recovered, There has been proposed a constant-humidity warm charging method for a blast furnace raw material that gives the gas calorific value to the blast furnace raw material. The purpose of this is to remove the moisture adhering to the blast furnace raw material as much as possible by heating it before weighing it, to keep the moisture in the raw material constant, and to accurately weigh the blast furnace raw material.
JP-A-53-141117

  If the technology described in Patent Document 1 is used, the blast furnace raw material can be heated and dried before charging the blast furnace, and the amount of water introduced into the blast furnace furnace is reduced, so that the blast furnace operation is input into the furnace. It is possible to reduce the amount of heat generated. However, this technology aims to reduce the moisture content by drying the blast furnace raw material and accurately measure it. The adhering powder raw material is weighed together with the granular raw material and loaded into the blast furnace furnace. Therefore, it is considered impossible to prevent clogging due to the powder raw material in the blast furnace furnace. That is, it is possible to reduce the amount of heat input into the furnace in the blast furnace operation, but it is not effective for the purpose of reducing the powder raw material charged into the furnace.

  Therefore, the present invention solves such problems of the prior art, enables drying and preheating of the blast furnace raw material by an inexpensive method, reduces the amount of heat input into the furnace during blast furnace operation, and An object of the present invention is to provide a blast furnace raw material drying preheating device that reduces the amount of powder raw material brought into the gas flow in the furnace and thereby achieves stable operation of the blast furnace.

The features of the present invention for solving such problems are as follows.
(1) A blast furnace raw material drying preheating device, a hopper for storing the raw material, a feeder for discharging the raw material installed below the hopper, and a sieve for screening the raw material discharged from the feeder Equipment, an air supply device that supplies heated gas into the hopper from four or more air supply ports provided at equal positions in the circumferential direction of the side wall of the hopper, and an exhaust that sucks and removes the gas in the hopper Having a device,
In order to measure the temperature distribution in the circumferential direction in the hopper, each temperature in the circumferential direction is the same level in the circumferential direction and is installed above and / or below the four or more air supply ports. Heating to be supplied to the air inlet corresponding to the installation direction of the thermometer according to the difference between the temperature that is the measurement value of the thermometer and the average value of the temperature that is the measurement value of each circumferential thermometer A blast furnace raw material drying preheating device comprising: a control device that controls an opening degree of a flow control valve that adjusts a gas amount in a direction that reduces a difference from the average value .
(2) The blast furnace raw material drying preheating apparatus according to (1), wherein a thermometer is installed below the air supply port.

  According to the present invention, it is easy to remove moisture from the blast furnace raw material, and it is possible to reliably remove the powder raw material by sieving, and to prevent the wet powder raw material from adhering to the sieve and causing clogging of the sieve. Therefore, there is an effect that the management of the sieve becomes easy.

  As a result, the amount of heat input into the blast furnace can be reduced, and the amount of powder raw material brought into the blast furnace is reduced, so that the gas flow in the furnace can be optimized and greatly contribute to the stable operation of the blast furnace. it can.

  One embodiment of a drying preheating apparatus for a blast furnace raw material according to the present invention is shown in FIG.

  A blast furnace raw material drying preheating apparatus includes a hopper for storing raw materials, a feeder for discharging raw materials installed below the hopper, a sieve facility for sieving the raw materials discharged from the feeders, and a plurality of provided on the side walls of the hopper A thermometer for measuring the temperature distribution in the circumferential direction of the hopper while having an air supply device for supplying heated gas from the air supply port into the hopper and an exhaust device for sucking and removing the gas in the hopper And a control device for controlling the amount of heated gas supplied to each air supply port according to the measured value of the thermometer. In FIG. 1, the storage tank 1 and the storage tank 2 correspond to the hopper which stores the raw material of the drying preheating apparatus of a blast furnace raw material. 3 is a feeder, 4 is a screen with sieve equipment, 8 is an air supply device, 15 is an exhaust device, and stores the ore to be supplied to the blast furnace for each ore brand, and a storage tank 1 and coke to be supplied to the blast furnace. The example which supplies heated gas to the storage tank 2 to perform is shown. The normal storage tank 1 and the storage tank 2 are each formed by a plurality of hoppers. In storage tank 1, sintered ore, raw ore (ores drilled as iron ore and adjusted in particle size by sieving, ores containing such ores in an appropriate ratio. The hopper is divided into sub-materials (such as limestone and serpentine materials), discharged from the hopper at a predetermined ratio, and charged into the blast furnace as a mixed raw material. In the storage tank 2, normally the same kind of coke is stored in a plurality of hoppers and discharged simultaneously from each hopper to measure a predetermined amount. In FIG. 1, a feeder 3 is provided below the hopper of the storage tank 2, and the coke discharged here is conveyed by a conveyor via a screen 4 and sent to a coke weighing hopper 5. The sieving powder on the screen is collected to a powder coke hopper 7 via a powder chute 6 and carried out of the system.

  In FIG. 1, the discharge system of the storage tank 1 is omitted for the sake of simplicity, but here again, the ore discharged by the feeder below the hopper is divided into coarse particles and powder through a screen, and the coarse particles are It is conveyed to the weighing hopper by the conveyor, and the powder is collected in the fine ore hopper.

  The air supply device 8 for supplying heated gas into the hopper has a pressure-up fan (introduction fan) 9 for increasing the pressure of the heated gas, and an air supply pipe 10 for supplying the heated gas into the hopper. The tip of the air supply pipe is connected to a hopper to form an air supply port 11. The dust discharge port 12 can also be installed in the outer part of the hopper of the air supply pipe. 13 is a hot air generating source, and 14 is a flow control valve. The heated gas generated by the hot air generation source 13 is pressurized by the introduction fan 9 and is supplied into the hopper from the air supply port 11 provided on the side wall of each of the storage tank 1 and the storage tank 2. As shown in FIG. 1, when a flow control valve 14 is installed for each air supply port 11, when heating gas is supplied simultaneously to the plurality of storage tanks 1 and the storage tanks 2 with one air supply device. Each air supply amount can be adjusted, which is preferable. Although only one air supply port 11 of each hopper is shown in FIG. 1, a plurality of air supply ports are provided in each hopper. If a flow control valve is provided for each air supply port, it is easy to uniformly adjust the flow of the heated gas in the hopper, which is preferable.

  The exhaust device 15 that sucks and removes the gas in the hopper has a suction pipe 16 that sucks the gas in the hopper, a dust collector 17, and a suction fan 18. The suction pipe 16 is connected to a hopper through an exhaust port 19. An exhaust port 19 is provided in the upper part of each hopper (the storage tank 1 and the storage tank 2), and is exhausted by the suction fan 18 through the dust collector 17. By doing in this way, the heated gas sent from the air inlet 11 of the hopper rises in the hopper and a gas flow discharged from the exhaust port 19 is formed, and ores in the hopper by the heated gas, Coke is easily heated and dried. Therefore, the position of the air supply port 11 through which the heated gas is supplied into the hopper is preferably provided in the lower part of the hopper side wall as much as possible. In the conventional storage tank 1 and the storage tank 2, the upper portion of the hopper is normally opened to charge the raw material into the hopper. In the present invention, the suction fan 18 is used to effectively suck the heated gas. As shown in FIG. 1, it is preferable to close the opening for charging the raw material with a simple lid 20 except when the raw material is charged into the hopper. However, since the dust blown from the upper part of the hopper by the heated gas rising from below by the suction fan 18 is prevented, the lid on the upper part of the hopper is not necessarily required.

  As the heated gas sent to the hopper, various heated gases generated in a factory can be used. In particular, exhaust gas that is discharged at a relatively low temperature of about 300 ° C. or less and difficult to recover heat can be used effectively. In the case of blast furnace storage tanks and storage tanks, a sintering machine is usually installed in the vicinity, so using the cooler exhaust gas from the sintering machine is optimal because the air supply path is short and heat dissipation is low. And particularly preferred. In addition, heating gas can be appropriately selected according to the location conditions of each factory such as blast furnace hot stove exhaust gas and rolling heating furnace exhaust gas. Of course, a combustion furnace, an electric furnace or the like may be installed for generating heated gas, and a dedicated hot air generation source may be used.

  The temperature of the heated gas only needs to be able to dry and preheat the blast furnace raw material. Therefore, the temperature of the heated gas is preferably 60 ° C. or higher, more preferably 80 ° C. or higher. However, if the temperature exceeds 300 ° C, it is necessary to install a booster fan (introduction fan) that can handle high-temperature gas, and the heat resistance of equipment around the hopper becomes a problem, which may increase the equipment cost. Therefore, it is preferable that the temperature is 300 ° C. or lower. Considering the purpose of drying preheating, 200 ° C. or less is sufficient.

  Install two or more air supply ports on the side of the hopper. This is because it is preferable to arrange a plurality of air supply ports in the circumferential direction of the hopper in order to dry and preheat the raw material in the hopper evenly. The plurality of air supply ports are preferably arranged at equal positions in the circumferential direction. Furthermore, it is preferable to supply the heated gas from the annular tube to the plurality of air supply ports.

  FIG. 2 shows an embodiment in which an annular tube is provided around the hopper and heated gas is supplied from the annular tube to a plurality of air supply ports. An annular pipe 31 is provided around the hopper 30, and heated gas is supplied from the air supply port 11 through the hot air supply pipe 10. The annular pipe 31 serves as a reservoir, and the heated gas can be supplied from each air supply port 11 evenly.

  In the present invention, there is further provided a thermometer for measuring the temperature distribution in the circumferential direction in the hopper, and a control device for controlling the amount of heated gas supplied to each air supply port according to the measured value of the thermometer. Install. It is preferable to install thermometers at the same height level in the circumferential direction, and it is more preferable to install thermometers above and / or below the air supply ports. In FIG. 2, two thermometers 32 and 33 are installed in the circumferential direction of the side wall of the hopper 30 above and below the air supply port, respectively. By measuring the temperature of the raw material such as ore in the hopper with this thermometer, the balance between drying and preheating of the raw material in the hopper can be estimated. That is, if there is a part with a low temperature in the circumferential direction, increasing the heat input to the low temperature part by increasing the flow rate of the heated gas from the air supply port in that direction, the hopper in the entire circumferential direction The temperature balance can be made uniform. The flow rate of the heating gas can be adjusted by the flow control valve 14.

  FIG. 2 shows an example in which thermometers are provided at two locations in the horizontal direction with respect to the two air inlets 11. However, the present invention is not limited to this example, and thermometers may be provided at three or more locations in the horizontal direction. Good. Since the heated gas sent into the hopper flows upward because it is exhausted at the top of the hopper, there is a temperature gradient in the height direction of the hopper, so the thermometer used for temperature control is installed at the same horizontal level in the circumferential direction Although it is preferable, there is no problem in control even if there is a level difference of about 100 mm in the height direction.

  In FIG. 2, 34 is a control device that controls the amount of heated gas in accordance with the measured value of the thermometer. FIG. 2 shows a state in which a circumferential thermometer 32 at a level above the air inlet 11 and a circumferential thermometer 33 at a lower level are installed. It is only necessary to control the opening degree of the flow control valve 14 of the air supply port 11 by comparing the temperature measurement values at different levels. Although control is possible at either level, when a level above the air inlet is used (thermometer 32), if the height from the air inlet is too far away, the position where drying preheating has not been sufficiently performed yet Therefore, it is not preferable because it is necessary to confirm whether the drying preheating has been sufficiently achieved when it is finally discharged from the lower side of the hopper. It is desirable to install a thermometer at a level in the range of about 500 to 1000 mm from the air supply port.

  In the case where the thermometer is installed in the circumferential direction at a level below the air supply port (thermometer 33), it is more preferable because the temperature is measured almost at the position where the drying preheating is completed. In this case, in addition to the control for adjusting the balance of each thermometer in the circumferential direction, it is also possible to confirm the degree of drying preheating of the entire hopper by determining the temperature reached after the drying preheating is completed. Specifically, even if the measurement values of the respective thermometers in the circumferential direction are the same, if the ultimate temperature of the raw material is about 60 ° C., for example, it can be determined that the drying preheating as a whole is not sufficient, The operation of increasing the flow rate of the heated gas from the air supply port as a whole becomes possible. In order to vaporize the adhering moisture of the raw material and efficiently screen the adhering powder, it is preferable to raise the temperature of the raw material to about 80 ° C. or higher.

  Next, the control for adjusting the temperature balance in the hopper circumferential direction using the blast furnace raw material drying preheating apparatus of the present invention will be described.

  FIG. 3 shows an example in which four air supply ports are installed in the circumferential direction and thermometers are installed below the respective air supply ports. Side temperature values (T1 to T4) of the four thermometers in the circumferential direction are shown. Is a flow diagram showing a method for controlling the opening degree D1 to D4 of the flow control valve for adjusting the amount of heated gas from the air supply port corresponding to the installation direction of each thermometer. In FIG. 3, α is a threshold value for the difference from the average value of each temperature, and the flow valve opening is adjusted when the difference from the average value is greater than or equal to the threshold value α. α is usually controlled at about 5 ° C. β is an opening unit for changing the opening of the flow control valve by one adjustment. β is usually adjusted to about 2 to 5%.

  In addition to the flow shown in FIG. 3, when each temperature reaches a value equal to or higher than a predetermined value, adjustments such as lowering the opening degree of the entire flow control valve can be added as appropriate.

Among 20 storage tanks installed in a blast furnace with an internal volume of 5150 m ³ , 4 tanks for storing sintered ore and 4 storage tanks for storing raw ore are the same as those shown in FIGS. The raw material drying preheating equipment was installed. The capacity of the sintered ore tank is a maximum cutout amount of 70 t / H, and the capacity of the raw ore tank is a maximum cutout amount of 100 t / H.

Since the moisture of sintered ore was about 2 mass% at the maximum, in order to reduce this to 0 mass%, 40000m ³ (standard state) / H hot air was blown, and the raw ore moisture was Since it was 5 mass% at the maximum, it was set as the equipment which can blow 140000m < ³ > (standard state) / H. A part of the cooler exhaust gas of the adjacent sintering machine was used as a hot air generation source, and this was pressurized with an introduction fan and supplied to each tank as a heated gas. The temperature of the heated gas was 150 ° C. at the air inlet of each tank.

  Four air inlets for each raw material drying preheater are installed at symmetrical positions in the circumferential direction at the bottom of the hopper, and thermocouples are installed at positions 300 mm below the lower end level of the four air inlets to continuously measure temperature. Went. The measured value of this thermometer was taken into the personal computer, and the opening degree of the flow control valve provided in the four air supply ports was controlled by the control flow shown in FIG. The temperature deviation threshold value α was 5 ° C., and the adjustment of the flow control valve opening degree was adjusted by 5%. In addition, this opening degree control was managed with the personal computer so that it might be performed once every 20 minutes.

  As a result, the deviation of the four thermometers (a value obtained by subtracting the minimum value from the maximum value) was 14 ° C at 1 hour after the start of the heating gas blowing, but decreased to 6 ° C after 6 hours. did.

  In addition, as long as the sinter discharged from the lower part of the hopper is visually observed, the dried sinter was mixed with the sinter with moisture partially attached at one hour after the start of the blow. After 1 hour, it was uniformly dried as a whole.

Schematic which shows one Embodiment of the drying preheating apparatus of the blast furnace raw material which concerns on this invention. BRIEF DESCRIPTION OF THE DRAWINGS Schematic which is one Embodiment of the blast furnace raw material drying preheating apparatus which concerns on this invention, and shows a temperature control part. The flowchart which shows the method of controlling the amount of heating gas using this invention apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Storage tank 2 Storage tank 3 Feeder 4 Screen 5 Weighing hopper 6 Powder chute 7 Powder coke hopper 8 Air supply device 9 Booster fan (introduction fan)
DESCRIPTION OF SYMBOLS 10 Air supply piping 11 Air supply port 12 Dust discharge port 13 Hot air generation source 14 Flow control valve 15 Exhaust device 16 Suction piping 17 Dust collector 18 Suction fan 19 Exhaust port 20 Lid 30 Hopper 31 Annular pipe 32 Thermometer 33 Thermometer 34 Control device

Claims (2)

A blast furnace raw material drying preheating device, a hopper for storing the raw material, a feeder for discharging the raw material installed below the hopper, and a sieve facility for sieving the raw material discharged from the feeder, An air supply device that supplies heated gas into the hopper from four or more air supply ports provided at equal positions in the circumferential direction of the side wall of the hopper, and an exhaust device that sucks and removes dust from the hopper And having
In order to measure the temperature distribution in the circumferential direction in the hopper, each temperature in the circumferential direction is the same level in the circumferential direction and is installed above and / or below the four or more air supply ports. Heating to be supplied to the air inlet corresponding to the installation direction of the thermometer according to the difference between the temperature that is the measurement value of the thermometer and the average value of the temperature that is the measurement value of each circumferential thermometer A blast furnace raw material drying preheating device comprising: a control device that controls an opening degree of a flow control valve that adjusts a gas amount in a direction that reduces a difference from the average value .   2. The blast furnace raw material drying preheating apparatus according to claim 1, wherein the thermometer is installed below the air supply port.

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