KR101008097B1 - Pulverized coal injection control Method by the amount of the blowing air into the blast furnace - Google Patents

Abstract

In accordance with the present invention, the amount of fine coal blown in accordance with the decrease in the amount of blown air in the blast furnace can prevent the problem of clogging of the pulverized coal injecting facility and the occurrence of equipment loss due to the combustion capacity decrease by interlocking control of the set amount of the blown air in the event of an emergency wind. It relates to a control method.

The present invention is a structural means for achieving the object, the upper limit of the normal air flow rate supplied during normal blast furnace operation, the amount of air flow at the time of switching from the constant air flow control to the constant wind pressure control to ensure the weight of the charge in the blast furnace blast operation A blast control section is set as a lower limit, the set blast control section is equally divided at intervals of a predetermined percentage from the normal wind volume, and the maximum pulverized coal corresponding to the upper limit of the breeze control section is configured for the maximum amount of fine coal that can be burned without load oxygen. After setting the blowing set value, 50% of the maximum pulverized coal blowing set value as the minimum pulverized coal blowing set value at the lower limit of the wind blowing control section, and between the maximum minimum pulverized coal blowing set value by the number of the wind blowing control section. Evenly divide and set the fine coal injection set value against the wind volume, and check whether abnormal wind is indicated. When the gust is instructed, the pulverized coal injection is controlled to the pulverized coal injection set value corresponding to the checked air volume in the set gust control section.

Blast furnace, pulverized coal, blowing amount, combustion zone, conveying air, pulverized coal injection

Description

Pulverized coal injection control method by the amount of the blowing air into the blast furnace}

1 is a pulverized coal injection system of a general blast furnace.

Fig. 2 (a) is a cross-sectional structural diagram of the blast furnace, (b) is an internal charge and molten state diagram during blast furnace operation.

3 is a graph illustrating the amount of fine coal injection compared to the air volume of the blast furnace according to the embodiment of the present invention.

4 is a control system diagram of the pulverized coal injection facility to which the pulverized coal injection control method according to the present invention is applied.

5 is a flowchart showing a method for controlling pulverized coal injection according to the present invention.

The present invention relates to the operation of blast furnace, and more specifically, to reduce the air flow rate of the blast furnace to prevent the deterioration of air permeability by preventing the permeability deterioration by interlocking control the amount of pulverized coal in accordance with the combustion capacity at the blower pressure decrease due to the air flow decrease in the blast furnace The present invention relates to a method for controlling fine coal injection.

Coke and pulverized coal used as fuel to increase the temperature in the blast furnace is supplied, Figure 1 is a schematic diagram of a facility for injecting pulverized coal into the blast furnace, 1 is a blast furnace, 102 is formed in the lower part of the blast furnace (1) hot air A blowing ring corrugation pipe for injecting the sintered pipe is shown, and 4 is a blowing lance for blowing pulverized coal into the blast furnace 1.

The dispenser 7 is connected to the blown lance 4, the dispenser 7 is connected to the pickup device 5, the pickup device 5 is a plurality of feeder hoppers 6-1, 6- 2, 6-3), to carry the pulverized coal discharged from any feeder hopper to the distributor (7) as conveying air.

2 (a) is a cross-sectional view showing the interior of the blast furnace 1, (b) is a detailed view showing the charging and melting state in the blast furnace (1).

Referring to (a) and (b) of FIG. 2, when pulverized coal is blown into the blast furnace 1, carbon is chemically represented by Chemical Formula 1 by the blast furnace amount of oxygen supplied to the blowing air and the load oxygen. It is reacted and consumed as reducing gas.

At this time, the combustion capacity of the carbon as an important factor for determining the operating speed and the heat in the blast furnace (1), as shown in the formula (1) changes the oxygen content of the blast furnace (1) with a sharp decrease.                         

In the conventional injection process of pulverized coal, in the system diagram of Fig. 1, the feeder hoppers 6-1 to 6-3 to the pickup device 5 increase the pressure in the feeder hoppers 6-1 to 6-3 to increase the pressure. The pulverized coal is discharged by the car, and the pick-up device 5 carries as many pipes as the number of blower pipes of the blast furnace 1 through the distributor 7 and the transport pipe 12 by compressed conveying air. And is blown into the furnace by the blow lance (4). At this time, in order to prevent the backflow of pulverized coal by the internal pressure of the blast furnace 1, the pressure of the distributor 7 is usually maintained higher than the blowing pressure, and the pressure of the feeder hoppers 6-1 to 6-3 ( P _f ) is calculated and set as in Equation 1 below, and depends on the pulverized coal injection amount set value Qsv and the blowing pressure Po.

Here, f (Qsv) is a reference differential pressure characteristic, A is a gain, and Qmv is a fine coal injection amount control output.

By the way, when the blast furnace 1 is operated, the amount of air blown is suddenly reduced due to a sudden accident, and the like, and the decrease in the amount of air caused by such a large blow is accompanied by a decrease in wind pressure, so that the feeder hopper 6-1 6-3) to reduce the pressure.

When the pressure of the feeder hoppers 6-1 to 6-3 decreases, if the blowing amount of the pulverized coal is not reduced quickly, the pulverized coal may accumulate in the blower pipe 103 and the pulverized coal injection system may be blocked and the operation may proceed as it is. If this happens, the blower pipe is damaged due to the burning heat. In addition, the primary slag lacking fluidity in the high melting point slag layer generated in the vicinity of the combustion zone 105, that is, SiO ₂ -Al ₂ O ₃ high melting point growth and in-house slag generation process shown in FIG. The characteristics of the bosch slag are added, and the furnace gas stream 101 becomes unstable, which causes deterioration of breathability and excessively lowers the combustion temperature at the tip of the tuyere.

In general, since the return time of the air volume is short within the range of about 10% of the normal air volume due to the temporary wind pressure increase or deterioration of breathability, it is common not to adjust the blowing amount of pulverized coal, in which case the above-described problems do not appear.

However, in the event of failure of closing of the exit port or equipment failure of the charging system at the top of the blast furnace, a significant damping is required, and in this case, the operation is usually switched to the static pressure operation to support the load of the charges loaded in the blast furnace (1). At this time, the marginal wind pressure is about 65% to 70% of the air volume in the normal operation, and the operation speed of the blast furnace is reduced in order to prevent the deterioration of the level of charges and deterioration of thermal charges in addition to the blast operation. At this time, since the blowing of the load oxygen is stopped, the reduction in blowing energy reduces the blast furnace combustion zone 105 and the melt movement, and the combustion capacity decreases due to insufficient oxygen supply. Therefore, in this case, the amount of pulverized coal blown should be reduced than in the normal case.

However, in the related art, the driver sets the blow amount in the pulverized coal injection system directly, and since the pulverized coal blown amount is not changed at the time of blasting, excessive pulverized coal injection continues, resulting in the above-mentioned problems.

The present invention has been proposed in order to solve the above-mentioned conventional problems, and its object is to blockage and equipment loss of the pulverized coal injection facility according to the combustion capacity decrease by interlocking control of the injection amount set value according to the depressurization in case of an emergency operation. It is to provide a method for controlling the pulverized coal injection according to the reduced air flow of the blast furnace to prevent occurrence problems.

As a constitutional means for achieving the object of the present invention described above, in the method for controlling the pulverized coal blowing amount according to the decrease in the amount of air blown in the blast furnace, the upper limit of the normal air flow supplied during the operation of the normal blast furnace, ensuring the weight of the charge in the blast furnace blast operation Setting a wind reduction control section having a lower limit on the amount of air flow at the time of switching from the constant air flow control to the constant wind pressure control; Dividing the set wind control section equally at intervals of a predetermined percentage with respect to the normal air volume; The maximum pulverized coal injection set value corresponding to the upper limit of the wind blowing control section is set to the maximum pulverized coal combustion amount that can be burned without load oxygen, and 50% of the maximum pulverized coal blowing set value is set to the minimum pulverized coal blowing at the lower limit of the wind blowing control section. Setting a value, and then dividing the maximum minimum pulverized coal blowing set value equally by the number of the wind blowing control section to designate the pulverized coal blowing set value relative to the wind blowing amount; Checking whether abnormal gusts are indicated in the blast furnace operation; And checking an air volume of the blast furnace when the abnormal wind blowing is indicated, and controlling the pulverized coal blowing into the pulverized coal blowing set value corresponding to the checked wind amount in the set wind blowing control section.

In addition, the pulverized coal injection control method according to the present invention checks whether the pulverized coal injection amount set in the pulverized coal injection control step is less than or equal to the control minimum value of the pulverized coal injection facility, and repeats the pulverized coal injection control process if it is less than the minimum value, Stopping the blowing and switching to a purge process that blows only the return air to the blast furnace; Checking the air flow rate of the blast furnace while the purge process is performed, and checking whether the air flow amount is equal to or lower than a lower limit of the wind reduction control section; And if the air volume of the blast furnace is greater than or equal to the lower limit of the blast control section, switching the purge process to the blowing process, and controlling the pulverized coal injection with the pulverized coal blowing set value relative to the wind volume in the blast control section. .

In addition, the pulverized coal injection control method according to the present invention is characterized in that the equally divided interval is set to 5% of the normal wind volume of the blast furnace operation in the step of designating the pulverized coal injection amount set value in the blast control section.

In addition, the pulverized coal injection control method according to the present invention is characterized in that in the pulverized coal injection control step, the pulverized coal injection ratio fluctuation error of ± 1.5 T / Hr on the basis of the set value of the pulverized coal to the air volume of the wind blowing control section.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the method for controlling the pulverized coal injection according to the reduced air flow amount of the blast furnace of the present invention.                     

In the fine coal injection control method according to the present invention, the fine coal injection control value in the fine coal injection control facility blown into the blast furnace 1 during the blast blast is reduced in proportion to the air volume of the blast furnace in the facility as shown in FIG.

At this time, the section in which the pulverized coal injection set value according to the present invention is variably adjusted is called a wind blowing control section, and the wind blowing control section is the upper limit of the normal wind flow to switch the constant wind volume and the constant wind pressure to support the weight of the in-blast furnace during the wind blowing operation. It becomes a wind volume reduction section which makes the reference wind volume at the time point a lower limit. In the above description, the reference air volume for switching from the constant air volume control of the blast furnace operation to the constant wind pressure control corresponds to about 70% of the normal air volume during the air blasting operation.

Then, after dividing the wind control section evenly at predetermined intervals, the pulverized coal injection amount setting value is specified for each section. At this time, the maximum pulverized coal injection amount set value corresponding to the upper limit of the wind drift control section is set to the pulverized coal injection amount which can burn without load oxygen, and the minimum pulverized coal injection amount set value corresponding to the lower limit is 50% of the maximum pulverized coal injection amount set value. And between the upper limit and the lower limit set values are equally divided so as to correspond to each of the damping control sections.

If the above-described blast control section and the corresponding pulverized coal injection amount set value are specified before the start of operation, the pulverized coal injection amount set value corresponding to the blast furnace air volume corresponding to the sensation control section after the blast furnace operation starts according to the designated value. To be variable.

Hereinafter, the process will be described in more detail with reference to one embodiment.                     

Set point Air flow of blast furnace
[Nm ³ / min] Pulverized coal injection
[T / Hr] Pulverized coal ratio
(kg / TP) N Normal wind volume 18 80 N + 1 95% of normal wind volume 16 71 N + 2 90% of normal wind 14 62 N + 3 85% of normal flow 12 53 N + 4 80% of normal wind 11 49 N + 5 75% of normal flow 10 44 N + 6 70% of normal wind 9 40

Table 1 shows an example of the pulverized coal injection amount set value compared to the air volume supplied to the blast furnace in the method for controlling the pulverized coal injection amount according to the present invention, the output of the blast furnace is 5,400 T / D, the air volume during normal operation Silver 4,000 Nm ³ / min, coke ratio is 420kg / TP, pulverized coal ratio is 100kg / TP application example.

In general, the fuel cost required to make a ton of molten iron in the blast furnace 1 is called a fuel ratio (kg / T-P), which is calculated by FR = CR + PCR. In the above, CR is the coke ratio which is charged to the upper part of the blast furnace 1 with the charge, and PCR is the pulverized coal ratio blown into the combustion zone of the blast furnace 1 through the tuyere.

The method for injecting pulverized coal according to the present invention sets the normal air flow to an upper limit value, and the air flow rate (usually, 70% of the normal air flow rate) at the time of switching between the constant air flow rate and the constant wind pressure to ensure that it can support the weight of the charged material during a sudden decrease in airflow as the lower limit value. The air volume range is equally divided by a predetermined% interval of the normal air volume-5% in Table 1 above. That is, the normal air volume is referred to as the set point N, and increases by one every time the set interval (%) is decreased by up to 70% of the lower limit normal air volume, N, N + 1, N + 2, N Set the setpoint with +3, ..., N + 6.

In Table 1, the division interval is set to 5%, but this division interval is not fixed and may be variable according to the control system characteristics of the feeder hoppers 6-1 to 6-3 by the characteristics of the blast furnace operation.

 If the above setting is applied numerically to the actual blast furnace operation, the starting point of the control of the pulverized coal injection amount setting control according to the gust is given when the total amount of combustion that can be burned when no load oxygen is blown in the actual blast furnace operation is 80kg / TP. The maximum pulverized coal injection ratio at the set point N is 80 kg / TP, and the pulverized coal injection amount 18T / Hr at this time is set to the maximum pulverized coal injection amount at the start of the control according to the wind blowing, and the minimum control value of the pulverized coal injection facility is 9T /. Hr is the lower limit of pulverized coal injection, and the corresponding injection ratio 40 (kg / TP) is the minimum value of pulverized coal injection, wherein the pulverized coal injection ratio at each set point and the corresponding pulverized coal injection amount set value are as follows. It is calculated as in Equation 2.

The pulverized coal injection amount set value deviation between each set point is 5% compared to 18 T / Hr which is the maximum pulverized coal injection amount, and the upper and lower sections are equally divided.

In the state of setting the pulverized coal injection amount set value at the time of blast as described above, the operation state of the blast furnace is checked, and at the time of emergency blasting, the set value of the pulverized coal injection amount in preparation for the wind volume blown with the calculated pulverized coal injection amount set value To vary. Accordingly, the feed hoppers 6-1 to 6-2 are controlled in the process diagram of FIG. 1 by the pulverized coal injection control facility (not shown), and the pulverized coal is injected into the blast furnace 1 by the amount set in proportion to the air volume. Blow up.

As described above, the pulverized coal blowing amount is changed in proportion to the wind blowing amount, and the pulverized coal blowing is stopped when the air volume supplied to the blast furnace 1 is reduced to 70% of the normal wind, which is the lower limit. Then, a purge step of injecting only the return air is performed.

In this state, when the air volume starts to increase again, the pulverized coal is blown while increasing the set value of the pulverized coal injection amount in proportion to the increased air volume as shown in Table 1 above. do.

3 shows the change in the pulverized coal injection amount set value relative to the air volume of the blast furnace in the above embodiment, when the normal air flow amount 4000Nm ³ / min, the pulverized coal injection amount set value is maintained 18T / Hr, the air flow amount 4000Nm ^{In the range of 3} to 2800 Nm ³ / min corresponding to 70% of the normal air flow, the pulverized coal injection amount is varied in proportion to the air flow, and the fine pulverized coal injection amount is set to 0 at 2800 Nm ³ / min or less, and the pulverized coal injection is stopped.

Therefore, the fine coal injection amount is appropriately set in preparation for the air volume, so that the problem of blockage of pulverized coal at the time of decreasing the air volume or wind pressure can be solved.

4 is a block diagram schematically showing the control system configuration of the pulverized coal injection facility to which the method for controlling the pulverized coal injection amount according to the present invention is applied, and FIG. 5 is a procedure of the method for controlling the pulverized coal injection amount during the blast injection method according to the present invention. This is a flowchart showing.                     

With reference to FIG. 4 and FIG. 5, the pulverized coal injection amount control according to the air volume change at the time of blast furnace operation of this invention is demonstrated by operation procedure.

In step 501, the pulverized coal injection facility operates normally to blow the pulverized coal of the blown amount set in accordance with the blast furnace operation.

In Fig. 4, in the normal operation of the blast furnace, as in the prior art, a predetermined fine coal injection amount setting value is fixedly set in the first pulverized coal injection amount setting unit 403 on the basis of the target production amount in the blast furnace. The set value is input to the blowing amount adjusting unit 405. The blowing amount setting in the first pulverized coal injection amount setting unit 403 is manually set by the driver.

Then, the blow amount measurement value calculated from the unit time weight value change of the feed hopper 6 detected by the blow amount calculation unit 408 by the weight detector 220 is input to the blow amount adjusting unit 405, The PID control value corresponding to the deviation between the set value and the measured value is outputted so that the pulverized coal of the set amount is blown into the blast furnace, and the control value is inputted to the reference differential pressure setting part 409 and converted into a pressure set value, The adjusting unit 410 compares the pressure set value with the pressure detection value and adjusts the internal pressure of the feed hopper 6 through the first to third proportioners 411 to 413 to adjust the amount of pulverized coal. By the above, the feed hopper 6 discharges the pulverized coal of the set amount by the pressure difference through the process of joining, equalizing and back pressure.

In the situation where the operation of the blast furnace 1 is normally performed, the above process is repeated, so that a predetermined amount of pulverized coal injection is continuously performed.

When the pulverized coal blowing operation is normally performed as described above, if an abnormality occurs in the blast furnace operation and the air volume is reduced (502), the set value of the pulverized coal blowing amount is changed in accordance with the changed air volume. At this time, the decrease in the air volume can be made by checking whether the blast furnace operator indicates the emergency wind, and in the control system as shown in FIG. 4, the contact a of the relay R2 is turned on by turning on the emergency wind switching unit 401. The output of the second fine coal injection amount setting unit 44 is connected to the blowing amount adjusting unit 405.

In this case, the air volume change may be set manually by the driver, or may be automatically made without the driver's intervention (503).

First, in the case of manual operation, the driver operates the first pulverized coal injection amount setting unit 403 as in the prior art and arbitrarily sets the pulverized coal injection amount according to past operation experience (504).

In contrast, in the case of automatic operation, the pulverized coal injection amount set value is set in accordance with the present invention in a proportional to the wind rate reduction ratio as shown in Table 1 above (505).

The value of the pulverized coal injection amount compared to the air volume at the time of blast as shown in Table 1 is calculated in advance from the operating conditions of the blast furnace before the start of operation, and stored in the second pulverized coal injection amount setting unit 44, corresponding to the air volume of the blast furnace The pulverized coal injection amount set value is output and input to the blowing amount adjustment unit 405.

Thereafter, the wind pressure control of the feed hopper 6 is appropriately performed according to the variable pulverized coal injection amount set value as described above, so that an appropriate amount of pulverized coal injection is made in preparation for the blown air volume.

In step 506, it is determined whether the pulverized coal injection amount set value proportional to the blown air volume is less than the minimum allowable value of the pulverized coal injection control system. Repeat the value variable process (502 ~ 505).

If the pulverized coal injection amount set value is smaller than the controllable minimum value, the pulverized coal blast furnace is impossible to be injected, and thus the determination is performed for conversion from the blowing process to the purge process.

For example, in the embodiment shown in Table 1, the minimum value of fine coal injection is 9T / Hr, and the first fine coal injection amount setting unit 403 or the second fine coal injection amount is determined by the purge process determination unit 401 of FIG. When the pulverized coal injection amount set value outputted from the setting unit 404 is compared with a reference value (that is, the lowest possible injection value, for example, 9T / Hr), when lower than the reference value, the blowing process is stopped and the purge process starts. The purge process control signal is generated.

In response to the purge process control signal, the pulverized coal discharge from the feed hopper 6 is stopped in step 507, and only the return air shutoff valve 14 shown in FIG. 1 is opened, and then through the return air control valve 10. The purge process of supplying only conveying air to the blast furnace 1 is performed by adjusting only the flow volume of conveying air.

While the purge process is executed as described above, the pulverized coal injection control method according to the present invention continuously checks in step 508 whether the amount of air blown into the blast furnace 1 is increased above the operable air volume.

Usually, when the problem of the blast furnace 1 or the worsening of the blast furnace situation is solved, and the blast furnace operation is started, the air volume supplied to the blast furnace 1 will increase first.                     

Therefore, when the determination result of step 508 indicates that the air volume of the blast furnace 1 becomes the air volume that can be operated, that is, the minimum air volume that can be injected into the pulverized coal, the pulverized coal blowing set value is changed. It is indicated by the value corresponding to the air volume of the blast furnace 1 from the 2nd pulverized coal injection setting value 44. FIG. That is, since the air volume of the blast furnace 1 is increased in the blast furnace operation start section, the pulverized coal injection set value is gradually increased in proportion to the air volume, and thus, the pulverized coal amount blown into the blast furnace 1 also corresponds to the combustion capacity of the air volume. It is blown in an appropriate amount.

At the same time, it is checked at step 511 whether the air volume of the blast furnace 1 has reached the air volume during the normal operation, and the air volume during the normal operation is higher than that, and the first fine coal injection amount is set by the second fine coal injection amount setting unit 404. By switching to the setting unit 403, the pulverized coal injection process is controlled to a fixed pulverized coal injection amount set value in preparation for the output of the blast furnace 1.

As described above, the state of the blast furnace (1) in the case of changing the pulverized coal injection amount corresponding to the reduced amount of wind in the blast furnace (1) was checked, the following Table 2 is the pulverized coal injection as in the present invention for each operation change of the blast furnace This is a measurement of the balloon-ballast combustion temperature when the amount is varied.                     

Wind temperature Humidity Pulverized coal Air flow Oxygen Balloon ball burning temperature Normal operation 1130 20 20 4000 5000 2239 1130 15 18 4000 0 2192 Sensation 1130 15 16 3800 0 2206 1130 15 14 3600 0 2222 1130 15 12 3400 0 2240 1130 15 11 3200 0 2245 1130 15 10 3000 0 2250 Decompression operation 1130 15 9 2800 0 2256

The simulation results in Table 2 above are for the blast furnace production capacity '5400 tons / day'.

At this time, the air balloon burning temperature is' [{1559+ (0.839 × wind temperature)}-{(humidity / 1000) × 6033}-{((16666 × pulverized coal) / wind volume) × 3} + {(4913 / (wind volume × 60)) × Loaded Oxygen}], the blast furnace combustion temperature is 2239 ° C in normal operation for a blast furnace of 5400 tonnes per day.

In such a state, when an emergency gust is instructed due to deterioration of the blast furnace 1 or other problems, first, the injection of load oxygen is stopped. At this time, the load oxygen of the element for calculating the balloon-ball burning temperature is 0, in the conventional case, the balloon-ball burning temperature is lowered to 2165.42 ℃.

However, as shown in Table 2, in the case of the present invention, by reducing the pulverized coal blown at the start of the wind blowing to 18T / Hr, the balloon-ball combustion temperature is 2192 ℃, it can be seen that lower than the conventional case .

In general, in consideration of the prevention of deterioration of the heat during the dehumidification and the temperature of the hot air balloon, the humidity control amount is controlled by atmospheric humidity (stopping the humidity control and maintaining the pure atmospheric moisture content included in the air flow amount). In the case of atmospheric humidity, the humidity is reduced to 15 g.

If this goes on, a sense wind 5%, the air volume is gampung in 4000Nm ³ / min to 3800Nm ³ / min, coal injection amount according to the present invention is in proportion to the decrease flow rate, is reduced in the 18T / Hr to 16T / Hr. Therefore, the balloon-ball combustion temperature is 2206 ° C., whereby the combustion temperature in normal operation can be maintained almost.

However, in the case of the prior art, sense when wind progress of 5%, the air volume is 4000Nm at ³ / min, but gampung to 3800Nm ³ / min, when the coal injection amount is thereby maintained at 20T / Hr, the combustion temperature of the tuyere line is normal operations as 2123 ℃ It is 6% lower than time.

Subsequently, even though the blast is made, the amount of pulverized coal blown is reduced stepwise to 16, 14, 12, 11, and 10 T / Hr in proportion to the amount of blast, so that the combustion temperature of the blowhole is approximately 2206 to 2250 ° C. Line temperature can be maintained.

In general, a predetermined deviation occurs in the control system in the control system, so that a deviation of ± 1.5 T / Hr is allowed in the set pulverized coal injection amount set value relative to the wind blowing amount in consideration of this deviation. For example, a blast furnace with a production volume of 5400 tons as described above allows for a change in the pulverized coal injection ratio of (1.5 × 24) / 5400 = 6.6 kg / TP. Therefore, although the pulverized coal injection ratio was previously set to 80 kg / TP in Table 1, by the above deviation, up to 73.4 to 86.6 kg / TP is allowed.

 As described above, the pulverized coal industry reduces the amount of pulverized coal blown in proportion to the amount of wind blown in the event of an abnormal emergency gust in the blast furnace operation, thereby preventing the reduction of combustion capacity due to the decrease in the amount of air blown compared to the amount of pulverized coal blown, to stabilize the yellowing In addition to this, an excellent effect of preventing the clogging of the pulverized coal blowing facility, the deterioration of breathability, and the generation of melted air in the blower pipe, which has occurred due to the decrease in the air volume relative to the pulverized coal blowing amount, is exhibited.

Claims (4)

Setting a declining control section having an upper limit on the amount of normal air supplied during a normal blast furnace operation, and a lower limit on the amount of air flow at the time of switching from the constant air flow control to the constant wind pressure control to ensure the weight of the charge during the blast-furnace operation; Dividing the set wind control section equally at a predetermined interval with respect to the normal air volume; The maximum pulverized coal injection set value corresponding to the upper limit of the wind blowing control section is set to the maximum pulverized coal combustion amount that can be burned without load oxygen, and 50% of the maximum pulverized coal blowing set value is set to the minimum pulverized coal blowing at the lower limit of the wind blowing control section. Setting a value, and then dividing the maximum minimum pulverized coal blowing set value equally by the number of the wind blowing control section to designate the pulverized coal blowing set value relative to the wind blowing amount; Checking whether abnormal gusts are indicated in the blast furnace operation; And And if the abnormal wind blowing is indicated, checking the air flow volume of the blast furnace, and controlling the pulverized coal blowing into the pulverized coal blowing set value corresponding to the checked wind flow in the set wind blowing control section. Method for controlling the amount of pulverized coal blown according to the decrease of the air flow rate. The method of claim 1 wherein the method is Check whether or not the fine coal injection amount set in the fine coal injection control step is less than the control minimum value of the fine coal injection facility, and if it is less than the minimum value, repeat the fine coal injection control process, and if the minimum value is less than the minimum value, stop the fine coal injection and blow air only into the blast furnace. Converting to a purge process; Checking the air flow rate of the blast furnace while the purge process is performed, and checking whether the air flow amount is equal to or lower than a lower limit of the wind reduction control section; And As a result of the check, if the amount of air in the blast furnace is equal to or lower than the lower limit of the gust control section, the step of switching the purge process to the blowing process, and controlling the pulverized coal injection to the pulverized coal injection setting value compared to the air volume in the gust control section, characterized in that it further comprises. A method for controlling the pulverized coal injection according to the reduced air flow of the blast furnace. The method of claim 1, wherein the predetermined interval is 5%. The method of claim 1 wherein the method is In the pulverized coal injection control step, the pulverized coal injection amount control method according to the decrease in the blowing amount of the blast furnace, characterized in that the allowable fluctuations in the pulverized coal injection ratio of ± 1.5 T / Hr based on the pulverized coal set value compared to the air volume of the wind blowing control section.

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