JP2005249354A - Combustion control method for reduced iron manufacturing plant and its device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combustion control method and its device capable of carrying out stable mass product reducing operation by completely burning unburnt gas generated in a heating zone and a reducing zone while controlling a furnace temperature in the heating zone. <P>SOLUTION: In combustion control of a reduced iron manufacturing plant, mass products formed with metal oxide and reducing agent mixed and granulated are loaded into a rotary hearth furnace and heated and reduced by burners 4, 5 provided in the heating zone 2 and the reducing zone 3, respectively, and the reduced mass products are collected. A difference between the furnace temperature detected by a furnace temperature meter 6 installed in the heating zone 2 for controlling the furnace temperature in the heating zone 2 and a target set temperature in heating zone is computed, and in accordance with a computation result obtained by the computation, a fuel amount calculated by a fuel amount computing device 12 is increased/decreased to a fuel amount to be output at the furnace temperature detected by a furnace temperature meter 7 installed in the reducing zone 3 to control the fuel amount of the burner 4. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a combustion control method and a combustion control apparatus for reduced iron production equipment for reducing and recovering metal oxides in a rotary hearth furnace.

  In order to reuse the iron oxide contained in steelmaking dust and fine ore, etc., a binder and a reducing agent are mixed into the steelmaking dust and kneaded, and granulated to form an agglomerated material. A reduced agglomerate is produced by charging in a furnace and heating and reducing.

  FIG. 2 is a schematic view of a rotary hearth furnace. The rotary hearth furnace 1 includes a charging device 1a for charging the agglomerate into the furnace, a heating zone 2 for heating the agglomerated material, a reduction zone 3 for reducing the heated agglomerated material, and a reduction. And a discharge device 1b for discharging the agglomerated material out of the furnace. In the heating zone 2 and the reduction zone 3, burners 4 and 5 are installed on the side walls of the rotary hearth furnace 1, respectively, and the charged agglomerates are passed from the heating zone 2 to the reduction zone 3 by the rotation of the rotary hearth. Reduced iron is produced by heating and reducing.

  The agglomerated material charged in the heating zone 2 is burned with excess air with an air ratio of the burner 4 installed in the heating zone 2 of 1.0 or more, and moisture, unburned gas, etc. contained in the agglomerated material and the reduction zone The unburned gas generated in is burned simultaneously, heated to a predetermined temperature, and the burner installed in the reduction zone is burned at an air ratio of 1.0 or less to be reduced.

  In the rotary hearth furnace 1, since the heating zone 2 and the reduction zone 3 are in communication with each other in the furnace, the reducing gas generated in the reduction zone 3 is discharged through the heating zone 2 to the exhaust gas discharge port 2a. For this reason, in the heating zone 2, the reducing gas generated in the reduction zone 3 is combusted, and sufficient air is introduced to use the heat of combustion.

As a combustion control method for a rotary hearth furnace, Patent Document 1 discloses that the O ₂ concentration or CO concentration of the in-furnace gas in the heating zone is measured, and air is introduced into the heating zone in accordance with the measured concentration to generate in the reduction zone. A combustion method for burning a combustion gas in a heating zone is disclosed.

Patent Document 2 discloses a combustion gas supply means for supplying a combustion gas obtained by mixing a predetermined amount of fuel with an appropriate amount of primary combustion air, and a secondary combustion air supply means for supplying a predetermined amount of secondary combustion air. And a pellet input amount detecting means for detecting an input amount of pellets supplied onto the hearth, and a secondary combustion air flow rate adjusting means for adjusting a set amount of the secondary combustion air according to the pellet input amount. An apparatus for producing reduced iron is disclosed.
JP 11-248359 A JP 2001-115204 A

  However, as in Patent Document 1, in the method of adjusting the air amount according to the amount of unburned gas generated in the reduction zone in the heating zone, when the amount of unburned gas is large depending on the amount of unburned gas generated Has a problem that the furnace temperature in the heating zone rises because air is increased and combustion is actively performed, and the furnace temperature decreases when there is little unburned gas generated. Control is not possible.

  For this reason, when the furnace temperature in the heating zone is low, the agglomerate temperature is also low, so the reduction action of the agglomerate entering the reduction zone is delayed, and the reduction during one rotation of the rotary hearth furnace is reduced. There is also a problem that it cannot be done. In addition, if there is a large amount of unburned gas and air is blown into the heating zone and blown into the heating zone for active combustion, the furnace temperature in the heating zone rises, the temperature of the agglomerate rises, and agglomeration in an oxidizing atmosphere occurs. There is also a problem that the reducing agent volatilizes due to the heating of the chemical and enters the reduction zone as strong iron oxide, making it impossible to produce reduced iron.

  Further, as in Patent Document 2, in the case of adjusting the set amount of secondary combustion air according to the amount of agglomerated material charged in the furnace, if there is a large amount of agglomerated material being charged, It is assumed that the generation of unburned gas will increase. Therefore, in the present technology, only the properties of the agglomerated material charged into the rotary hearth furnace, that is, the amount of moisture contained in the agglomerated material, the amount of binder, and the amount of reducing agent are adjusted to a constant amount. Must be charged.

  However, in reality, there are variations in the properties of the agglomerated material to be charged, and unburned gas is not always generated in proportion to the amount of agglomerated material. For this reason, unburned gas cannot be completely burned only by adjusting the amount of air for secondary combustion according to the amount of agglomerated material to be charged.

  Therefore, in the reduced iron production facility, the present invention is to completely burn the unburned gas generated in the heating zone and the reduction zone while controlling the furnace temperature in the heating zone, thereby stabilizing the agglomerate reduction action. A combustion control method and a combustion control device that can be performed are provided.

  The combustion control method of the reduced iron production facility of the present invention comprises mixing a metal oxide and a reducing agent and granulating it into an agglomerate, and charging the agglomerate into a rotary hearth furnace. In the combustion control method of the reduced iron production facility for reducing and recovering the agglomerate by heating and reducing with a burner provided in the heating zone and the reduction zone, the furnace temperature of the heating zone installed in the heating zone The difference between the furnace temperature detected by the furnace thermometer that controls the heating zone and the target set temperature of the heating zone is calculated, and the fuel amount calculated by the fuel amount calculation device based on the calculation result obtained by this calculation is calculated as the reduction zone. The fuel amount of the burner is controlled by adjusting the fuel amount output by the furnace temperature detected by the furnace thermometer installed in the burner.

  Further, the combustion control device of the reduced iron production facility of the present invention is an agglomerated product obtained by mixing and granulating a metal oxide and a reducing agent, and charging the agglomerated product into a rotary hearth furnace. A reduced iron production facility for reducing and recovering the agglomerate by heating and reducing with a burner provided in a heating zone and a reduction zone of a floor furnace, and a furnace thermometer for controlling the furnace temperature in the heating zone A fuel quantity that is installed and that calculates a fuel quantity based on a calculation result obtained by calculating a difference between a furnace temperature detected by the furnace thermometer and a heating zone target set temperature An arithmetic unit and an arithmetic unit for adjusting the amount of fuel obtained by the arithmetic unit to a fuel amount output from a furnace temperature detected by a furnace thermometer installed in the reduction zone are provided.

  According to the present invention, it is possible to completely burn the unburned gas generated in the heating zone and the reduction zone while controlling the furnace temperature in the heating zone by controlling the fuel amount of the burner in the heating zone. The action can be performed stably.

  FIG. 1 is a flow showing combustion control of the present invention. In FIG. 1, the rotary hearth furnace 1 is schematically shown as a side view, and the charging device and the discharging device are omitted.

  The agglomerated material is charged into the heating zone 2 from a charging device (not shown). The heating zone 2 is provided with an exhaust port 2a for exhaust gas generated in the rotary hearth. The combustion exhaust gas of the burners 4 and 5 installed in the heating zone 2 and the reduction zone 3 is dissipated outside through the exhaust port 2a of the heating zone 2 and the exhaust gas treatment device.

  Furnace thermometers 6 and 7 are installed in the heating zone 2 and the reduction zone 3, respectively. In the heating zone 2, the target temperature SV is set in advance by the setting device 10 and sent to the calculator 9. Further, the detected temperature is sent to the calculator 9 by the temperature controller 8 detected by the furnace thermometer 6. Then, the difference Δt between the target temperature SV set by the calculator 9 and the detected actual temperature PV is calculated by Δt = SV−PV and sent to the calculator 12 which converts it into a fuel amount.

  The computing unit 12 selects a coefficient K corresponding to the temperature difference Δt calculated by the computing unit 9 from a preset correction coefficient table 11 and multiplies the temperature difference Δt by the correction coefficient K to obtain a corrected fuel amount ΔF as ΔF = Δt × K. Calculated by

  On the other hand, in the reduction zone 3, the furnace temperature in the reduction zone 3 is adjusted to a predetermined temperature by the temperature controller 14 using the furnace thermometer 7 installed in the reduction zone 3. The furnace temperature of the reduction zone 3 is adjusted to 1100 ° C to 1300 ° C. In the reduction zone 3, the sensitivity of the fuel flow control valve 19 is adjusted by the flow controller 15 so that the furnace temperature is reached.

  Further, the actual flow rate of the fuel is measured by flow meters 17 and 18 installed in the fuel pipe 20 and is instructed by the flow rate controller 15. Here, the corrected fuel amount ΔF calculated from the difference Δt between the target temperature SV of the heating zone 2 and the actual temperature PV is put into the calculator 13 installed between the flow rate control valve 15 and the flow rate control valve 19, and from the flow rate controller 15. The opening of the flow control valve 19 is set by correcting the flow rate instructed by the flow control valve 19. At the same time, the corrected fuel amount ΔF is also inputted to the calculator 16 installed between the flow meters 17 and 18 and the flow rate controller 15 for calculation, and the flow rate value after the calculation is indicated by the flow rate controller 15.

For example, assuming that the target furnace temperature SV in the heating zone 2 is 900 ° C. and the actual temperature PV detected by the furnace thermometer 6 is 800 ° C., the temperature difference Δt is 100 ° C. when the temperature difference Δt is calculated by the calculator 9. It is assumed that the corrected fuel when the temperature difference is 100 ° C. is calculated by the calculator 12 to obtain a fuel amount of 100 Nm ³ / H. The corrected fuel amount of 100 Nm ³ / H obtained by the calculator 12 is input to the calculator 13 and added to the fuel amount indicated by the flow rate controller 15 to set the opening degree of the flow rate control valve 19. On the other hand, the arithmetic unit 16 installed between the flow meters 17 and 18 that measure the actual flow rate and instruct the flow rate controller 15 and the flow rate controller 15 performs an operation to reduce the correction fuel ΔF, and the calculation result is adjusted to the flow rate. Instruct 15 in total.

  For the combustion air amount, the air ratio is set by the setting device 21 in accordance with the fuel amount, and the actual flow rate of the combustion air is measured by the flow meters 23 and 25 installed in the combustion air pipe 26, and the flow rate controller. 22 is automatically set and instructed to set the opening of the flow control valve 24.

It is a combustion control flow of the present invention. It is the schematic of a rotary hearth furnace.

Explanation of symbols

1: rotary hearth furnace 1a: charging device 1b: discharge device 2: heating zone 2a: exhaust gas discharge port 3: reduction zone 4: heating zone burner 5: reduction zone burner 6: furnace thermometer 7: furnace thermometer 8: Temperature controller 9: Calculator 10: Setter 11: Fuel correction table 12: Calculator 13: Calculator 14: Temperature controller 15: Flow controller 16: Calculator 17: Flow meter 18: Flow meter 19: Flow control Valve 20: Fuel piping 21: Setting device 22: Flow controller 23: Flow meter 24: Flow control valve 25: Flow meter 26: Combustion air piping

Claims (2)

A metal oxide and a reducing agent are mixed and granulated to form an agglomerated material. The agglomerated material is charged into a rotary hearth furnace and heated by a burner provided in the heating zone and the reduction zone of the rotary hearth furnace. In the combustion control method of the reduced iron production facility that reduces and recovers the agglomerates by reducing,
Calculate the difference between the furnace temperature detected by a furnace thermometer that controls the furnace temperature of the heating zone installed in the heating zone and the heating zone target set temperature, and based on the calculation result obtained by this calculation, the amount of fuel Reduced iron characterized by controlling the amount of fuel in the burner by adjusting the amount of fuel calculated by an arithmetic unit to the amount of fuel output by the furnace temperature detected by a furnace thermometer installed in the reduction zone Combustion control method for manufacturing equipment. A metal oxide and a reducing agent are mixed and granulated to form an agglomerated material. The agglomerated material is charged into a rotary hearth furnace and is heated by a burner provided in the heating zone and the reduction zone of the rotary hearth furnace. A reduced iron production facility that reduces and recovers the agglomerates by heating and reducing,
A furnace thermometer that controls the furnace temperature in the heating zone is installed, and an arithmetic device that calculates the difference between the furnace temperature detected by the furnace thermometer and the heating zone target set temperature is provided, and is obtained by the arithmetic device. The fuel amount calculation device for calculating the fuel amount based on the calculation result and the fuel amount obtained by the calculation device are adjusted to the fuel amount output from the furnace temperature detected by the furnace thermometer installed in the reduction zone. A combustion control device for reduced iron manufacturing equipment, characterized in that an arithmetic device is provided.

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