JP3099322B2 - Blast furnace heat management method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blast furnace heat management method for suppressing fluctuations in molten iron components by performing stable operation of a blast furnace.

[0002]

2. Description of the Related Art The fuel ratio in a blast furnace is 500 kg / t.
-Pig (pig iron), but 100 kg by blowing pulverized coal with hot air added with oxygen from the tuyere.
Coke of about / t-pig can be replaced by pulverized coal, and operation can be performed at a low fuel ratio. However, in order to stably operate the furnace condition when pulverized coal is injected, it is important to properly maintain the heat balance in the furnace. Many methods have been proposed for adjusting the heat balance in a blast furnace.

For example, the heat balance of the entire blast furnace, that is,
Total balance using thermal accounting, which is the difference between the total enthalpy (heat input) of the charged materials (blast furnace charge, air volume) and the total enthalpy (heat output) of the discharged materials (amount of tappings and waste gas) model,
Partial balance model that divides the internal state of the blast furnace according to reaction or temperature and takes heat balance at each part, divides the blast furnace into minute parts in the axial direction, and considers the heat balance of the minute height element in consideration of the reaction speed inside the furnace. There is a differential balance model to be taken.

[0004] The amount of solution loss carbon and the amount of nitrogen in the top gas component are determined at predetermined time intervals,
Calculate a moving average of the obtained value in a predetermined time width,
An evaluation point is given by comparing a moving average value of each of the solution loss carbon amount and the nitrogen amount with a plurality of threshold values, and a method of predicting a blast furnace heat drop according to the comprehensive evaluation based on the evaluation points (particularly, Fairness 6-3560
No. 5) has been proposed.

[0005]

SUMMARY OF THE INVENTION The above Japanese Patent Publication No. Hei 6-356
Since the method disclosed in Japanese Patent Publication No. 05 only performs a blast furnace furnace heat reduction prediction, the heat-up action width at that time is based on the experience of the operator, and the individual difference due to the difference in experience is large. It is difficult to stabilize the situation.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art, to be able to predict a decrease and an increase in blast furnace heat at an early stage, and to present an operation action width at that time, thereby further stabilizing the blast furnace heat. It is an object of the present invention to provide a blast furnace heat management method that can be achieved.

[0007]

In order to achieve the above object, the present inventor has determined the furnace condition quickly and accurately and maintained an appropriate heat balance. Tests were conducted to establish a furnace heat management method applicable to the unstable state. As a result, as an index indicating the furnace heat state in the furnace, the calculated coke ratio calculated by dividing the coke consumption rate obtained from the furnace gas composition etc. by the pig iron generation rate, and the auxiliary fuel injection rate calculated using the pig iron generation rate The product of the value obtained by the division and the replacement rate is added to obtain the calculated fuel ratio, and the calculated fuel ratio is corrected by the blast temperature and blast humidity to obtain the calculated corrected fuel ratio. The inventors of the present invention have studied what can be well estimated and arrived at the present invention.

According to the blast furnace heat management method of the present invention, the amount of auxiliary fuel injected is divided by the pig iron generation rate to the calculated coke ratio obtained by dividing the coke consumption rate obtained from the furnace top gas component by the pig iron generation rate. The calculated fuel ratio is obtained by adding a value obtained by multiplying the calculated value by the replacement rate to obtain a calculated fuel ratio.The calculated corrected fuel ratio is obtained by correcting the calculated fuel ratio by the blast temperature and the blast humidity. Air humidity,
The heat balance in the furnace is controlled by adjusting the amount of pulverized coal blown, the air temperature and the charged coke ratio. As described above, the blast humidity, the pulverized coal injection amount, the blast temperature, and the charged coke ratio are adjusted so that the calculated corrected fuel ratio becomes a predetermined set value, and the heat balance in the furnace is managed, thereby increasing the ore increase. Even in an unsteady state such as time, the hot metal temperature can be kept almost constant, and the blast furnace condition can be stabilized.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The coke consumption rate in the present invention is calculated based on the following equation (1) from the furnace top (CO + CO ₂ ) discharge rate and the like obtained from the furnace gas component analysis value by gas chromatography. is there. Coke consumption rate (kg / min) = (ab + c + d) / e (1) where a: furnace top (CO + CO ₂ ) discharge rate, b
: C feed rate in auxiliary fuel, c: C disappearance rate by carburization, d: C discharge rate of furnace top dust, etc., e: C ratio in coke.

In the present invention, the production rate of pig iron (p
ig-t / min) is calculated by the following equation (2) from the amount of oxygen reduced in a unit time determined from the analysis value of the furnace gas components by gas chromatography. Pig iron production rate (t / min) = (amount of oxygen reduced in unit time) / (amount of oxygen to be reduced to produce 1 kg of pig iron) Equation (2)

In the present invention, the calculated coke ratio (kg /
(t-pig) is obtained by the following equation (3) from the coke consumption rate (kg / min) obtained by the above equation (1) and the pig iron production rate (t / min) obtained by the above equation (2). is there. Calculated coke ratio (kg / t-pig) = coke consumption rate (kg / min) / pig iron production rate (t / min) Equation (3)

The calculated fuel ratio in the present invention is the calculated coke ratio (kg / t-
pig) and a value obtained by dividing the auxiliary fuel injection amount (kg / min) by the pig iron production rate (pig-t / min), and multiplying the result by the replacement ratio, according to the following equation (4). Note that the replacement rate is obtained by dividing the calorific value of the auxiliary fuel by the calorific value of coke, but is ultimately obtained from actual results. Calculated fuel ratio = Calculated coke ratio (kg / t-pig) + [Auxiliary fuel injection amount (kg / min) / pig iron production rate (pig-t / min)] × replacement ratio (4)

The calculated corrected fuel ratio in the present invention is obtained by correcting the calculated fuel ratio obtained by the above equation (4) by the blast temperature and the blast humidity and by the following equation (5). Calculated corrected fuel ratio = calculated fuel ratio + A × (blast temperature−B) + C × (blast humidity−D) (5) where A, B, C, and D are constants. The actual values of the constants A and C in the equation (5) are obtained by the blast furnace mathematical model and corrected. Further, the constant B is obtained from the following equation and the constant A. Blast temperature ΔBT (° C.) = [Blow air humidity (1 g / Nm ³ ) × 1.677 Kcal / g)] / [0.335 Kcal / Nm ³ · ° C. (air specific heat at 1000 ° C.)] = 5 ° C./Blow air humidity 1 g / Nm ^Three

The calculation of the calculated fuel ratio and the calculated corrected fuel ratio is based on the measurement sampling time Δt of the blast temperature and the blast humidity.
Although it is performed every time, it is usually stored as one-minute data in the process computer, but the calculation is performed every ten minutes.

In the method of managing the heat of a blast furnace according to the present invention, the calculated corrected fuel ratio obtained by the above equation (5) fluctuates much earlier than the fluctuation of the hot metal temperature. Is changed, when the calculated correction fuel ratio starts to decrease or increase from a predetermined set value, for example, an average value up to eight hours before, the air blowing humidity and pulverized coal blowing are set to the predetermined set values. By adjusting the amount, the blast temperature, the charged coke ratio, and the like, fluctuations in the hot metal temperature can be suppressed, and variations in the hot metal components can be suppressed to stabilize the furnace condition.

The furnace heat management method for a blast furnace according to the present invention comprises:
The heat balance in the furnace is managed by adjusting the blowing air humidity, the amount of pulverized coal injected, the blowing air temperature, the charged coke ratio, etc., so that the calculated corrected fuel ratio obtained by the above equation (5) becomes a predetermined set value. . For example, when the calculated corrected fuel ratio becomes lower than a predetermined set value, the ventilation humidity is reduced to control the calculated corrected fuel ratio to a set value while suppressing the decrease. In this case, the blast humidity is calculated back and reduced so that the calculated corrected fuel ratio according to the formula (5) becomes the same value as the predetermined set value, so that the blast humidity reduction width can be obtained. As described above, the blowing conditions and the raw material charging conditions were changed by adjusting the blowing air humidity, the pulverized coal blowing amount, the blowing air temperature, the charging coke ratio, and the like so that the calculated correction fuel ratio became a predetermined set value. Even in such a case, the fluctuation of the hot metal temperature can be suppressed, and the variation of the hot metal component can be suppressed.

[0017]

【Example】

Example 1 In a blast furnace having an inner volume of 2700 m ³ , a tuyere number of 28 and a tap hole number of 2, a blowing amount of 4000 Nm ³ / min and an oxygen addition amount of 5
000Nm ³ / hr, blast temperature 1150 ° C, blast humidity 3
Blowing conditions of 0 g / Nm ³ , ore / coke ratio 3.70,
Charge coke ratio 430 kg / t-pig, tapping capacity 200
Under steady-state conditions of t-pig / hr and a slag amount of 60 t / hr, the furnace top waste gas component analysis by gas chromatography every three minutes, the blowing condition, the raw material charging condition, etc. were measured every minute. These average values were calculated every 10 minutes, and the calculated fuel ratio and the calculated corrected fuel ratio were calculated every 10 minutes by the formulas (4) and (5). The obtained calculated corrected fuel ratio is compared with a predetermined set value (520 kg / t-pig). When the calculated corrected fuel ratio starts to decrease below 520 kg / t-pig, no action is taken. When the temperature of the hot metal dropped from 1510 ° C. to 1475 ° C., the blast temperature was raised from 1150 ° C. to 1180 ° C., and the blast humidity was lowered from 30 g / Nm ³ to 25 g / Nm ³ . The air volume, air temperature,
FIG. 1 shows changes over time in the blast humidity, calculated fuel ratio, calculated corrected fuel ratio, and hot metal temperature. Further, the calculated corrected fuel ratio is compared with a predetermined set value (520 kg / t-pig), and when the calculated corrected fuel ratio starts to fall below 520 kg / t-pig, the calculated corrected fuel ratio is reduced. 520kg / t-
In order to maintain a constant pig, the blast humidity was sequentially reduced from 30 g / Nm ³ to 20 g / Nm ³ , and when the calculated corrected fuel ratio started to increase, the blast humidity was sequentially increased to 25 g / Nm ³ . FIG. 2 shows changes over time in the blown air amount, the blown air temperature, the blown air humidity, the calculated fuel ratio, the calculated corrected fuel ratio, and the hot metal temperature in this case.

As shown in FIG. 1, the hot metal temperature is 1510 ° C.
When the air temperature has dropped from
℃ from 1180 ℃, and the ventilation humidity is 30
In the case of the comparative example in which the temperature was reduced from 25 g / Nm ³ to 25 g / Nm ³ , the hot metal temperature decreased to 1460 ° C., and then recovered, but the fluctuation of the hot metal temperature was large. On the other hand, as shown in FIG. 2, the calculated corrected fuel ratio is 520 kg / tp.
ig, the calculated corrected fuel ratio becomes 520.
In order to keep it constant at kg / t-pig, the blast humidity was set at 30 g /
In the case of the example of the present invention in which the temperature of the hot metal was gradually reduced from Nm ³ to 20 g / Nm ³ , the hot metal temperature was slightly reduced, the hot metal temperature could be maintained at 1500 ° C., and the fluctuation of the hot metal temperature was slight.

Example 2 In the same blast furnace as in Example 1, the blowing rate was 4000 Nm ³ /
min, oxygen addition amount 5000 Nm ³ / hr, blowing temperature 1
Blowing conditions of 150 ° C, blowing humidity 35 g / Nm ³ , ore /
Coke ratio 3.56, charge coke ratio 450 kg / t-
pig, tapping amount 200t-pig / hr, tapping amount 60t
When the ore / coke ratio was increased from 3.56 to 3.70 from the operating conditions of / hr, the furnace top waste gas component analysis every 3 minutes by gas chromatography, the blowing condition, the raw material charging condition, etc. were changed for 1 minute. Each time, the average value was calculated every 10 minutes, and the calculated fuel ratio and the calculated corrected fuel ratio were calculated every 10 minutes. Charge coke ratio is 450kg / t-pi
g to 430 kg / t-pig, and then the pulverized coal injection amount was increased from 15 T / hr to 19.5 T / hr based on conventional experience. FIG. 3 shows the time-dependent changes in the blown air amount, charged coke ratio, blown air temperature, blown air humidity, pulverized coal injection amount, calculated fuel ratio, calculated corrected fuel ratio, and hot metal temperature in the case of this comparative example. Also, from the time when the ore / coke ratio was increased from 3.56 to 3.70, the calculated corrected fuel ratio was changed to 520 kg / t-pi before the charged coke ratio was reduced.
g, the pulverized coal injection rate was increased sequentially from 15 T / hr to 19.5 T / hr. FIG. 4 shows changes over time in the blown air amount, the charged coke ratio, the blown air temperature, the blown air humidity, the pulverized coal injection amount, the calculated fuel ratio, the calculated corrected fuel ratio, and the hot metal temperature in the case of the present invention.

As shown in FIG. 3, when the calculated corrected fuel ratio starts to increase from 520 kg / t-pig before the mineral increase,
Based on past experience, pulverized coal injection rate was 15 T / h
In the case of the comparative example in which the amount was increased from r to 19.5 T / hr, the hot metal temperature was significantly higher than the set value, and the superheated state was established. On the other hand, as shown in FIG. 4, after the ore / coke ratio was increased from 3.56 to 3.70, pulverized coal injection was performed to maintain the calculated corrected fuel ratio at 520 kg / t-pig before the ore increase. 19.5T in order from 15T / hr
In the case of the present invention example where the amount was increased to / hr, the hot metal temperature could be kept constant at approximately 1500 ° C.

[0021]

According to the present invention, a fuel gas analysis is performed by measuring furnace waste gas component analysis by gas chromatography, blowing condition, raw material charging condition, etc. every one minute, and calculating an average value thereof every ten minutes. The ratio and the calculated corrected fuel ratio are calculated every 10 minutes, and the blast humidity, the amount of pulverized coal blown, the blast temperature, the charged coke ratio, etc. are adjusted so that the calculated corrected fuel ratio becomes constant, thereby changing the hot metal temperature. Can be suppressed, and the variation of the hot metal component can be suppressed, and stable operation of the blast furnace can be achieved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a conventional example of a blower amount, a blower temperature,
The graph shows the time change of the blast humidity, the calculated fuel ratio, the calculated corrected fuel ratio, and the hot metal temperature, and FIG.
(B) the time-dependent change of the blast temperature, (c) the time-dependent change of the humidified air, (d) the time-dependent change of the calculated fuel ratio, (e) the time-dependent change of the calculated corrected fuel ratio, (f) The figure shows the change over time of the hot metal temperature.

FIGS. 2A and 2B are graphs showing a change over time in a blown air amount, a blown air temperature, a blown air humidity, a calculated fuel ratio, a calculated corrected fuel ratio, and a hot metal temperature in Example 1 of the present invention, and FIG. And (b) the change over time of the blast temperature, (c) the change over time of the humidity of the blast, (d) the change over time of the calculated fuel ratio,
(E) shows the change over time of the calculated corrected fuel ratio, and (f) shows the change over time of the hot metal temperature.

FIG. 3 is a graph showing a change over time of a blown air amount, a charged coke ratio, a blown air temperature, a blown air humidity, a pulverized coal injection amount, a calculated fuel ratio, a calculated corrected fuel ratio, and a hot metal temperature of the conventional example in Example 2, (A) the time-dependent change in the amount of blown air, (b) the time-dependent change in the charged coke ratio, (c) the time-dependent change in the blowing temperature and the humidity, and (d) the time-dependent change in the amount of pulverized coal injected. Change, (e)
The figure shows the change over time of the calculated fuel ratio, the figure (f) shows the change over time of the calculated corrected fuel ratio, and the figure (g) shows the change over time of the hot metal temperature.

FIG. 4 is a graph showing the change over time of the blown air amount, charged coke ratio, blown air temperature, blown air humidity, pulverized coal injection amount, calculated fuel ratio, calculated corrected fuel ratio, and hot metal temperature in Example 2 of the present invention. (A) Fig. (A) shows the change over time of the blowing amount, (b) shows the change over time of the charged coke ratio, (c) shows the change over time of the blowing temperature and the blowing humidity, and (d) shows the change over the pulverized coal blowing amount. change over time,
(E) shows the change over time of the calculated fuel ratio, (f) shows the change over time of the corrected fuel ratio, and (g) shows the change over time of the hot metal temperature.

Claims (1)

(57) [Claims] In the method for managing heat in a furnace during operation of a blast furnace, the amount of auxiliary fuel injected is calculated based on a calculated coke ratio obtained by dividing a coke consumption rate obtained from a furnace gas composition or the like by a pig iron generation rate. The calculated fuel ratio is obtained by adding a value obtained by dividing the calculated fuel ratio by the replacement rate to obtain a calculated fuel ratio, and a calculated corrected fuel ratio obtained by correcting the calculated fuel ratio by the blowing temperature and the blowing humidity is obtained. A heat management method for a blast furnace, wherein a heat balance in a furnace is controlled by adjusting a blast humidity, a pulverized coal blowing amount, a blast temperature, and a charged coke ratio so as to have a set value.