JPH09143520A - Method for injecting pulverized fine coal into blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pulverized fine coal blowing means which improves the ventilation in a blast furnace and can stably blow the pulverized fine coal, by independently controlling pressure losses at a blasting tuyere part and a raceway part. SOLUTION: In the method for blowing the pulverized fine coal into the furnace from the blasting tuyere together with the hot blast flowed in a blow pipe by projecting a pulverized fine coal blowing nozzle in the blow pipe by penetrating the wall of the blow pipe for blowing the hot blast connected to the blasting tuyere, when the pressure loss in the blasting tuyere exceeds a reference value, the tip position of the nozzle for blowing the pulverized fine coal is shifted into the furnace inner side to lower the pressure loss at the blast tuyere part. When the pressure loss at the raceway part exceeds a reference value, the coke strength is increased to lower the pressure loss at the raceway part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for injecting pulverized coal into a blast furnace, and more particularly, to injecting pulverized coal into a blast furnace for improving blast furnace air permeability by appropriately controlling pressure loss at the tuyere level. Regarding the method.

[0002]

2. Description of the Related Art In recent years, due to the development of blast furnace technology, heavy oil has been blown from the tuyere into the blast furnace as an auxiliary fuel, and further reflecting the energy situation thereafter, it is economical and economical to replace heavy oil. A method of blowing pulverized coal into a blast furnace has been put into practical use.

As is well known, as a method for blowing pulverized coal into a blast furnace, a pulverized coal injection nozzle is projected into the blow pipe by penetrating through the wall of a hot air blowing blow pipe connected to the blowing tuyere of the blast furnace. Then, a method of blowing the blown air into the furnace together with the hot air flowing in the blow pipe is common.

In such a pulverized coal blowing method,
If the pulverized coal is not completely burned in the tuyere or raceway, the burning rate will deteriorate. As a countermeasure, for example, a method of moving the pulverized coal blowing position in the direction opposite to the tuyere (upstream side) to increase the distance between the tip position of the pulverized coal blowing nozzle and the tuyere to improve the combustion rate. It has been known. However, when the blowing position of the pulverized coal is moved to the upstream side, the ash content contained in the pulverized coal adheres to the inner surface of the blow pipe,
There is a problem that not only the accumulation becomes easy and stable blowing of pulverized coal becomes difficult, but also the blowing of hot air from the tuyere becomes unstable.

Therefore, for example, in Japanese Patent Publication No. 60-53081, the position of the pulverized coal blowing nozzle is set within a certain range to improve the burning rate of pulverized coal while preventing ash deposition and deposition. A method has been proposed.

[0006]

However, when the pulverized coal is completely burned in the front tuyere raceway in order to improve the burning rate of the pulverized coal, deterioration due to the solution loss gasification reaction of coke progresses and the lower part of the furnace is advanced. In addition to reducing the coke particle size of the coke, the consumption of coke in front of the tuyere decreases, so the coke supply speed to the front of the tuyere decreases, and the coke replacement time in the lower part of the blast furnace is extended. As a result, there is a problem that the deterioration of the coke staying in the blast furnace is promoted, the particle size of the coke in the lower part of the furnace is reduced, and the air permeability of the blast furnace is deteriorated.

The present invention has been made to solve the above-mentioned problem of deterioration of air permeability in a blast furnace, and improves the air permeability in the furnace by independently controlling the pressure loss in the tuyere portion and the raceway portion. , A method for injecting pulverized coal into a blast furnace capable of stably injecting pulverized coal is proposed.

[0008]

According to the present invention, a pulverized coal blowing nozzle is projected through the wall of a hot air blowing blow pipe connected to a blower tuyere, and flows through the blow pipe. In the method of blowing pulverized coal into the furnace from the blast tuyere with hot air, measuring the pressure loss of the blast tuyere and raceway part, if the blast tuyere pressure loss exceeds a preset reference value, When the tip position of the pulverized coal injection nozzle is moved to the inside of the furnace to reduce the pressure loss at the tuyere, and when the raceway pressure loss exceeds a preset reference value, the coke strength is increased to increase the race. The gist is a method of reducing the pressure loss in the way portion.

In the present invention, as a method for improving the in-furnace air permeability of the blast furnace, attention was paid to the pressure loss at the blast tuyere and the raceway portion because the pressure loss at the blast tuyere and the raceway portion and the inside of the furnace This is due to the finding that there is a correlation with breathability. That is, it was found that when the pressure loss at the tuyere and the raceway is high, the ventilation resistance in the furnace becomes low.

According to the present invention, when the pressure loss at the tuyere becomes higher than the reference value when the pulverized coal is injected, the tip position of the pulverized coal injection nozzle is moved to the inside of the furnace and the tuyere is obtained. Suppresses an increase in pressure loss in the raceway section, and when the pressure loss in the raceway section rises above the standard value, the charging coke strength (DI, CSR) is increased to cause coke turning in the raceway. This is the means to reduce the pressure loss in the raceway part by suppressing the pulverization.

Here, the pressure loss at the tuyere portion and the raceway portion are ΔPa [MPa] and ΔPb [MPa], respectively.
Then, the reference value (upper limit value) of ΔPa and ΔPb is Δ based on the relationship between the tuyere pressure loss and the raceway pressure loss.
The reference value of Pa can be set to 0.0031 [MPa], and the reference value of ΔPb can be set to 0.0245 [MPa].

That is, the tuyere pressure loss ΔPa is 0.0
When it exceeds 031 [MPa], the amount of blast decreases, or the blast power cost increases due to the increase in blast pressure, and the amount of pulverized coal injection decreases, while the pressure loss on the raceway part ΔPb.
When the value exceeds 0.0245 [MPa], abnormal furnace conditions due to blow-through, hanging on the shelf, slipping, etc. occur.
And the reference value (upper limit) of ΔPb are 0.0031 respectively.
[MPa] and 0.0245 [MPa] are desirable.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view showing an example of the construction of an apparatus for carrying out the method of the present invention. Nozzle, 5 is a pressure measuring lance, 6 is a pressure distribution measuring device, 7
Is a comparator, 8 is a nozzle position control device, 9 is a coke strength control system, and 10 is a raceway.

In the above apparatus, the pulverized coal is blown from the pulverized coal injection nozzle 4 which penetrates the wall of the hot air blowing blow pipe 3 connected to the blowing tuyere 2 of the blast furnace 1 and projects into the blow pipe. It is blown into the furnace from the blower tuyere 2 together with the hot air flowing in the pipe 3.

As a method for measuring the pressure loss in the blast tuyere 2 part and the raceway 10 part, for example, N ₂ purge is always performed from the tip of the pressure measuring lance 5 inserted from the blast tuyere 2 into the furnace. A method is used in which a part is recovered and the purge pressure and the recovery pressure are used.

That is, in the present invention, the pressure distribution measuring device 6 measures the pressure distribution in the blower tuyere 2 part and the raceway 10 part, and the tuyere pressure loss ΔPa and the raceway part pressure loss ΔPb are compared. Type in 7. In the comparator 7, the actually measured ΔPa and ΔPb, and the preset ΔP
a and the reference value (upper limit value) of ΔPb are respectively compared,
Tuyere pressure loss ΔPa is the standard value 0.0031 [MP
a] is exceeded, a control command is sent to the nozzle position control device 8 to move the pulverized coal injection nozzle 4 to the inside of the furnace, and the raceway portion pressure loss ΔPb is the reference value 0.0.
If it exceeds 245 [MPa], a control command is sent to the coke strength control system 9 to increase the coke strength. The amount of the pulverized coal blowing nozzle 4 moved to the inside of the furnace is appropriately set according to the tuyere pressure loss ΔPa value. Usually 50 mm
Before and after.

The tuyere pressure loss ΔPa is a reference value of 0.0
When the pulverized coal injection nozzle 4 is moved to the inside of the furnace when the pressure exceeds 031 [MPa], the combustion frame at the tuyere moves into the raceway, and the pressure loss at the tuyere decreases. Further, if the coke strength is increased when the pressure loss ΔPb of the raceway portion exceeds the reference value 0.0245 [MPa], powdering due to coke turning in the raceway 10 is suppressed. Pressure loss decreases.

[0018]

[Example] In a blast furnace having an inner volume of 4800 m ³ , FIG.
Pressure loss at the tuyere when operating by blowing pulverized coal (volatile content 20 to 45% by weight) by the method shown in
[a], the pressure loss ΔPb [MPa] in the raceway and the relationship between the ventilation resistance in the furnace are shown in FIG. Table 1 shows the operating conditions in this example.

In the present embodiment, as shown in FIG. 1, a pressure measuring lance 5 is inserted from the blower tuyere 2 and N ₂ is constantly fed into the furnace.
Purging was performed, and the pressure distribution at the blast tuyere and raceway was measured using the purge pressure and the pressure of the recovered gas at that time. 2 shows that the ventilation resistance in the furnace is low (1130
Pressure loss ΔP at the tuyere at 0-11600 [l / m])
a [MPa] and pressure loss in raceway part ΔPb
When [MPa] is a black circle and the ventilation resistance in the furnace is high (120
00-12300 [l / m]) are plotted by white circles.

As is clear from the data of FIG. 2, the pressure loss ΔPa [MPa] at the tuyere is the reference value (0.0031).
When the pressure exceeds 500 MPa, it is possible to reduce the pressure loss at the tuyere by 0.00008 MPa by moving the tip position of the pulverized coal blowing nozzle 4 to the inside of the furnace by 50 mm, and the pressure loss at the raceway portion. When ΔPb [MPa] exceeds the reference value (0.0245 MPa, the coke strength is increased (CSR: 2.0 → 64.4, DI: 184.
0 → 84.5) reduces the pressure loss in the raceway part to 0.
It was possible to reduce the pressure by 0054 to 0.0073 MPa. As a result, the ventilation resistance in the furnace was improved by 400 to 1000 [l / m], and the pulverized coal could be blown in stably.

[0021]

[Table 1]

[0022]

As described above, according to the method of the present invention, the blast furnace air permeability can be improved by independently controlling the pressure loss in the blast tuyere and the raceway, so that the pulverized coal is always used. I can blow in stably,
It has a great effect on the pulverized coal blowing operation of the blast furnace.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of the configuration of an apparatus for carrying out the method of the present invention.

FIG. 2 is a pressure loss Δ at a tuyere in an embodiment of the present invention.
Pa [MPa], pressure loss in raceway part ΔPb [M
It is a figure which shows the result of having investigated the relationship between Pa] and ventilation resistance in a furnace.

[Explanation of symbols]

 1 Blast Furnace 2 Blow Tuyers 3 Blow Pipe for Hot Air Injection 4 Pulverized Coal Injection Nozzle 5 Lance for Pressure Measurement 6 Pressure Distribution Measurement Device 7 Comparator 8 Nozzle Position Control Device 9 Coke Strength Control System 10 Raceway

Claims (1)

[Claims] 1. A pulverized coal blowing nozzle is projected into the blow pipe through a wall of a hot air blowing blow pipe connected to the blowing tuyere, and the hot air flowing in the blow pipe is blown into the furnace from the blowing tuyere. In the method of blowing pulverized coal into, the pressure loss of the blast tuyere and raceway portion is measured, and if the blast tuyere pressure loss exceeds a preset reference value,
When the tip position of the pulverized coal injection nozzle is moved to the inside of the furnace to reduce the pressure loss at the tuyere, and when the raceway pressure loss exceeds a preset reference value, the coke strength is increased to increase the race. A method for injecting pulverized coal into a blast furnace, which is characterized by improving the air permeability of the blast furnace by reducing the pressure loss in the way section.