JPH1161212A - Operation for injecting pulverized fine coal into blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an operational method of pulverized fine coal injection into a blast furnace which can restrain the heat variation in the blast furnace and the variation of pig iron producing speed in the case of using plural kinds of coal kinds as the pulverized fine coal injected from a blasting tuyere, particu larly, even at the time of changing the coal kind or when changing coke ratio. SOLUTION: The operational method of the blast furnace injects the pulverized fine coal together with hot blast from the blasting tuyere. In the case of using plural coal kinds as the pulverized fine coal, calorific value utilized in the blast furnace is pre-obtd. from the components in the pulverized fine coal, and the injecting quantity of the pulverized fine coal is changed so that the calorific value in the blast furnace before and after changing the coal kind or the coke ratio are equalized. At the same time, under consideration of the reaction efficiency in the furnace gas, oxygen enriching quantity is adjusted. By this method, the variations of the molten pig iron temp. and the production speed of the pig iron in the blast furnace can be minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of operating a blast furnace in which pulverized coal is blown together with hot air from a blowing tuyere, in the case of using a plurality of types of coal, particularly when changing the type of coal or changing the coke ratio. It relates to a pulverized coal injection operation method.

[0002]

2. Description of the Related Art Generally, in the operation of pulverized coal injection into a blast furnace, the calorific value of coal is measured by a calorimeter or Dulo.
The heat exchange rate was calculated from the calorific value calculated by the ng formula, and the amount of pulverized coal injected was determined.However, since carbon and hydrogen were not completely burned in the blast furnace, they were actually used in the blast furnace. The calorific value is lower than these calorific values, and if the conventional calorific value is used, the heat exchange rate cannot be accurately expressed. In addition, since the reaction efficiency of carbon and hydrogen in the furnace was not taken into consideration, it was not possible to evaluate the change in pig iron production rate due to the difference in coal type.

Conventionally, to solve such a problem, for example, Japanese Patent Application Laid-Open No. Hei 6-212217 discloses a method in which the calorific value and volatile content of pulverized coal are used as indices, and the relative replacement ratio of pulverized coal and relative To increase blast furnace gas generation,
A method of mixing and pulverizing pulverized coal has been proposed.

In Japanese Patent Application Laid-Open No. 6-240320, a difference in the amount of oxygen in each coal is determined in advance, and the amount of oxygen enrichment corresponding to the difference in the amount of oxygen is increased or decreased based on the difference in the amount of oxygen. A pulverized coal injection operation method has been proposed in which the production rate of pig iron is kept constant.

[0005]

However, in any of the above-described methods, an accurate heat exchange rate that is appropriate for the reaction in the blast furnace cannot be expressed in any case. When the ratio was changed, heat fluctuations and fluctuations in pig iron production rate occurred.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and is intended for use in a case where a plurality of types of coal are used as pulverized coal blown from a blowing tuyere, particularly when changing the type of coal or coke. It is an object of the present invention to provide a pulverized coal injection operation method for a blast furnace that can suppress fluctuations in heat and pig iron production rate in the blast furnace even when the ratio is changed.

[0007]

According to the method for injecting pulverized coal into a blast furnace according to the present invention, the amount of heat used in the blast furnace is determined in advance from the components of the pulverized coal, and the amount of coal used in the blast furnace before and after the change in the coal type and coke ratio is determined. The amount of pulverized coal injected is changed so that the calorific value of the furnace becomes equal, and at the same time, the amount of oxygen enrichment is adjusted in consideration of the reaction efficiency of the gas in the furnace. In this manner, when a plurality of types of coal are used, particularly when the type of coal is changed or when the coke ratio is changed, a change in heat and a change in pig iron production rate can be suppressed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, in order to solve the above-mentioned problems, the amount of pulverized coal to be blown and the blowing conditions (oxygen enrichment) are adjusted according to the following procedure to change the coal brand. In addition, it was decided to prevent heat fluctuations and fluctuations in pig iron production rate when changing the coke ratio.

In the blast furnace, the utilization ratio of carbon monoxide [ηCO], the utilization ratio of hydrogen [ηH ₂ ], and the heat flow ratio [HFR = (solid heat capacity) /
(Gas heat capacity)] as an initial value, and the effective calorific value [Qef] in the blast furnace is obtained from the coke and coal components by the following equation (1).

[0010]

[Equation 1] Qef = (Q1 + Q2 × ηCO) × (% C) ÷ 100 + Q3 × ｛(%
H) × ηH ₂ − (% O) ÷ 8｝ ÷ 100 (kcal / kg) where C + (1/2) 0 ₂ = CO + Q1 CO + (1/2) 0 ₂ = CO ₂ + Q2 H ₂ + (1/2) 0 ₂ = H ₂ O + Q3 Q1: Heat value per unit mass of C Q2: Heat value per unit mass of C in CO Q3: Heat value per unit mass of H

Next, the effective calorific value of coke and pulverized coal [(Q
ef, COKE), (Qef, PC)] and the coke ratio [C / R] so that the sum of the heat loss [Heat Loss / R] of the furnace body and the furnace top (the sensible heat of the furnace gas) becomes equal. And the ratio of pulverized coal [PC / R] to
Determined by

[0012]

[Equation 2] (C / R) × (Qef, COKE) + (PC / R) × (Qef, PC) − (Heat
(Loss) / R = (C / R ') × (Qef', COKE) + (PC / R ') × (Qef', PC)
− (Heat Loss) / R 'where C / R', PC / R ', (Heat Loss) / R' and Qef 'are the coal brand, coke ratio before coke ratio change, pulverized coal ratio, furnace body It is the heat loss and effective calorific value of the furnace top (the sensible heat of the furnace gas).

[0013] The heat loss [H
eat Loss / R] is calculated from the heat flow ratio HFR by the following equation (3).

[0014]

(Heat Loss) / R = g + h × HFR (kcal / pt) where g: coefficient obtained from actual operating conditions h: coefficient obtained from actual operating conditions

[0015] Coke ratio and pulverized coal ratio and humidity control during blowing
From [BM / R], the carbon ratio [Carbon / R] and the hydrogen ratio [Hydrogen / R] are calculated by the following formulas 4 and 5.

[0016]

[Equation 4] Carbon / R = (C / R) × (% C) COKE ÷ 100 + (PC / R) × (%
C) PC ÷ 100 (kg / pt)

[0017]

[Equation 5] Hydrogen / R = (C / R) × (% H) COKE ÷ 100 + (PC / R) ×
(% H) PC ÷ 100 + (BM / R) × 2 ÷ 18 ÷ 1000 (kg / pt)

From Equations 4 and 5, ηCO and ηH ₂ O are newly obtained by Equations 6 and 7 below.

[0019]

ΗCO = a + b × (Carbon / R) + c × HFR where a: coefficient obtained from actual operating conditions b: coefficient obtained from actual operating conditions c: coefficient obtained from actual operating conditions

[0020]

ΗH ₂ O = d + e × (Hydrogen / R) + f × HFR where d: coefficient obtained from actual operating conditions e: coefficient obtained from actual operating conditions f: coefficient obtained from actual operating conditions

The oxygen content [WO] in the furnace top gas (CO, CO ₂ ) is calculated by the following equation (8).

[0022]

[Equation 8] WO = 4 ÷ 3 × (1 + ηCO) × ｛(Carbon / R) − (Dust /
R) × (% C) Dust ÷ 100−1000 × (% C) Pig ÷ 100｝ (kg / p
t) However, Dust / R: Basic unit of dust discharged from furnace top (% C) Dust: Carbon concentration in dust (% C) Pig: Carbon concentration in hot metal

The amount of oxygen (Oxygen / R) from the blast out of the oxygen in the furnace top gas is calculated by the following equation (9).

[0024]

Oxygen / R = ｛WO-O (Ore) -O (PC) × (1-ηH
₂ O)｝ ÷ 32 × 22.4−O ₂ / R (Nm ³ / pt) where O (Ore): oxygen from ore (kg / pt) O (PC): oxygen from PC (kg / pt) O ₂ / R: Oxygen intensity (Nm ³ / pt)

Based on the blowing conditions (blowing amount, oxygen amount, humidity control amount), the basic unit of air blowing (BV / R) and the basic unit of furnace gas generation amount (BG
/ R) is calculated from Equations 10 and 11 below.

[0026]

BV / R = (Oxygen / R) ÷ (% O ₂ ) BV (Nm ³ / pt) where (% O ₂ ) BV is the volume ratio of oxygen in the blast air

[0027]

[Equation 11] BG / R = (BV / R) × (% N ₂ ) BV + (PC / R) + (% N) PC ÷ 2
8 × 22.4 + (Carbon / R) ÷ 12 × 22.4 + (Hydrogen / R) ÷ 2 × 2
2.4 (Nm ³ / pt) where (% N ₂ ) BV: nitrogen volume ratio in blast air (% N) PC: nitrogen concentration in pulverized coal

The heat flow ratio HFR is calculated from the ore ratio (Ore / R), the coke ratio, and the unit gas generation rate of the top using the following equation (12).

[0029]

HFR = ｛(C / R) × i + (Ore / R) × j｝ / (BG / R × k) where i to k are constant values

[0030] heat flow ratio HFR by the equation 12 is newly determined, newly determined ItaCO, the ItaH ₂ from Equation 6 described above. Then, ItaCO been determined, the ItaH ₂ are substituted into the equation 1, below, the convergence calculation until effective calorific value of coke and pulverized coal obtained by Equation 2 is equal before and after the change of coal type change or coke ratio Go, △ PC / R, △
The BV / R is obtained, and the pulverized coal injection amount and oxygen enrichment amount are adjusted based on this.

According to the present invention as described above, convergence calculation is performed until the effective calorific value of coke and pulverized coal becomes equal before and after the change of the coal type and the change of the coke ratio, and ΔPC / R, ΔBV / R
And the amount of pulverized coal injection and the amount of oxygen enrichment are adjusted based on this, so that even when the coal type is changed or the coke ratio is changed, it is possible to suppress heat fluctuations and fluctuations in pig iron production rate.

[0032]

EXAMPLES The results of experiments conducted to confirm the effects of the present invention will be described below. In a blast furnace having an inner volume of 2700 m ^3, the coal brand was changed as shown in FIG. 2. Due to fluctuations, stable operations could not be performed. The operation transition at this time is shown in FIG.

On the other hand, when the pulverized coal injection amount and the oxygen amount are adjusted using the effective calorific value in the blast furnace according to the present invention, as shown in FIG. 1, the hot metal temperature and the pig iron production rate fluctuate. It was possible to change the brand of coal without any change. 1 and 2 used in the experiment.
Each component of D is as shown in Table 1 below.

[0034]

[Table 1]

[0035]

As described above, according to the present invention,
When the coal type or coke ratio is changed, the amount of coal and coke that is effectively used in the blast furnace is changed based on the amount of pulverized coal injected, and the blowing conditions are adjusted. Fluctuations and the rate of pig iron formation can be minimized.

[Brief description of the drawings]

FIG. 1 is a diagram showing the transition of the operation of the method of the present invention when a coal brand is changed.

FIG. 2 is a diagram showing changes in the operation of the conventional method when changing the coal brand.

Claims (1)

[Claims] In a blast furnace operating method in which pulverized coal is blown together with hot air from a blowing tuyere, when a plurality of coal types are used for the pulverized coal, a calorie used in the blast furnace is determined in advance from components of the pulverized coal. Change the pulverized coal injection amount so that the calorific value in the blast furnace before and after the change in coal type and coke ratio is equal, and at the same time adjust the oxygen enrichment amount in consideration of the reaction efficiency of the gas in the furnace. Characterized by the pulverized coal injection method of the blast furnace.