JP5962611B2 - Blast furnace pulverized coal blowing method and blowing abnormality detection device - Google Patents

Description

  The present invention relates to a technique related to blast furnace operation in which pulverized coal is blown from a tuyere, and particularly to a technique for detecting a blowing abnormality when oxygen gas or other combustion-supporting gas is blown together with pulverized coal by a lance.

In recent years, global warming due to an increase in carbon dioxide emission has been a problem, and the suppression of emitted CO ₂ has become an important issue even in the steel industry. In blast furnace operation, pulverized coal blown from coke and tuyere is used as a reducing material, and using pulverized coal as much as possible than coke leads to suppression of exhausted CO ₂ and operation cost.
And as a pulverized coal blowing technique from the said tuyere, there exists a technique as described in patent documents 1-3, for example. These techniques are techniques in which a double pipe lance is used, pulverized coal is blown from the inner pipe of the double pipe lance, and oxygen gas is blown from a passage between the inner pipe and the outer pipe. By using such a double pipe lance, it becomes possible to increase the combustion efficiency as compared with the case where pulverized coal is blown with a single pipe lance.

Japanese Patent No. 4074467 Korean Patent Publication No. 2002-047359 Japanese Patent Application Laid-Open No. 6-10092

  The combustion-supporting gas passage formed between the inner tube and the outer tube of the double tube lance tends to have a high pressure loss because the gap between the inner tube and the outer tube is as narrow as several millimeters and the conveying path is long. It is in. If the pressure of oxygen gas blown out from the lance is lower than the pressure inside the furnace at the tip of the tuyere due to an abnormality such as clogging of the combustion-supporting gas passage, oxygen gas may not be sent into the furnace There is also a possibility that the hot air in the furnace flows backward to the lance side. For this reason, it is necessary to monitor whether oxygen gas is normally blown by the pressure of oxygen gas sent through the combustion-supporting gas passage.

However, it is difficult to accurately determine the pressure near the tuyere in the furnace. For this reason, it is desirable to be able to determine the abnormality of oxygen gas injection without using the detected value of the furnace pressure.
The present invention has been made by paying attention to the above points, and has an object to accurately determine an abnormality in injecting combustion-supporting gas without using the pressure in the furnace.

  In order to solve the above problems, the blast furnace pulverized coal blowing method according to one aspect of the present invention includes a blower pipe connected to the tuyere of the blast furnace and a pulverized coal passage through which the pulverized coal passes in the center. And a pulverized coal blowing lance in which a flammable gas passing passage through which the flammable gas passes is formed on the outer peripheral side of the pulverized coal passage and a tip portion is disposed in the blast pipe. In the blast furnace pulverized coal blowing method in which pulverized coal is blown into the blast furnace from the tuyere together with the combustion supporting gas by a blowing lance, the flow rate of the combustion supporting gas to the combustion supporting gas passage is Vo, the pulverized coal passing When the flow rate of the pulverized coal to the road is set to Vp, it is determined that the blowing is abnormal when the flow rate Vo is larger than the flow rate Vp and the flow rate Vp is equal to or lower than a preset flashback speed. .

When the blowing pressure to the blowing pipe is Pb, the pressure of the combustion-supporting gas to the combustion-supporting gas passage is Po, and the pressure of the pulverized coal to the pulverization-coal passage is Pp, the flow velocity Vp is the fine powder. It may be calculated from the pressure difference between the charcoal pressure Pp and the blowing pressure Pb, and the flow velocity Vo may be calculated from the pressure difference between the combustion supporting gas pressure Po and the blowing pressure Pb.
The blow abnormality detection device according to one aspect of the present invention includes a blower pipe connected to a tuyere of a blast furnace, and a pulverized coal passageway through which pulverized coal passes at the center, and an outer peripheral side of the pulverized coal passageway. A flammable gas passageway through which the flammable gas passes is formed, and a pulverized coal blowing lance whose tip is disposed in the blast pipe is used together with the flammable gas by the pulverized coal blowing lance. In the blast furnace operation in which pulverized coal is blown into the blast furnace from the tuyere, the apparatus detects an abnormality in blowing of the combustion-supporting gas, the blowing pressure detection unit for detecting the blowing pressure Pb to the blowing pipe, and the above A combustion-supporting gas pressure detection unit that detects the pressure Po of the combustion-supporting gas to the combustion-supporting gas passage, a pulverized coal pressure detection unit that detects the pulverized coal pressure Pp to the pulverization coal passage, and the detection Pressure Po and blown air A combustion-supporting gas flow rate acquisition unit for calculating a flow-supporting gas flow rate Vo to the combustion-supporting gas passage based on the force Pb, and the pulverized coal passage based on the detected pulverized coal pressure Pp and the blowing pressure Pb. A pulverized coal flow rate acquisition unit for calculating the flow rate Vp of pulverized coal to the mist, and an abnormality determination that determines that the blowing is abnormal when the flow rate Vo is greater than the flow rate Vp and the flow rate Vp is equal to or lower than a preset flashback rate. And a section.

  According to the present invention, it is possible to easily and accurately determine an abnormality in injecting combustion-supporting gas from the tuyere without using the pressure in the furnace.

It is a conceptual diagram explaining the blast furnace operation which concerns on embodiment based on this invention. It is a conceptual diagram explaining the example of the piping structure to a ventilation pipe and a lance. It is a block diagram explaining the structure of an abnormality detection apparatus. It is a figure which shows an example of the relationship between the pressure Vb and Vo.

Next, embodiments of the present invention will be described with reference to the drawings.
In the present embodiment, oxygen gas will be described as an example of the combustion-supporting gas. The combustion-supporting gas is not limited to pure oxygen gas, and any other known combustion-supporting gas such as oxygen gas-enriched air is applicable.
FIG. 1 is an overall schematic diagram for explaining pulverized coal injection into a blast furnace 1 in blast furnace operation.
As shown in FIG. 1, a plurality of tuyere 3 are formed in the lower part of the blast furnace 1, and each tuyere 3 has a tip part of a blower pipe 2 for pumping hot air into the furnace. It is connected. In addition, a double-pipe lance 4 for blowing pulverized coal and combustion-supporting gas from the tuyere 3 into the furnace through the blower pipe 2 is provided. In this embodiment, the case where two double pipe lances 4 are provided for one air pipe 2 is illustrated, but one or three or more 2 are provided for one air pipe 2. A heavy pipe lance 4 may be provided. However, as the number of the lances 4 with respect to one blast pipe 2 increases, the amount of blow per lance can be set to be small.

Hot air from a hot air furnace (not shown) is supplied to the blower tube 2. As shown in FIG. 2, a flow rate adjusting valve (not shown) for adjusting the flow rate of hot air flowing through the blower tube 2, a pressure gauge 11 for detecting the pressure to the blower tube 2, and the blower tube 2 are provided on the blower tube 2. A flow meter 10 for detecting the flow rate of the flowing hot air is interposed. And the detection result of the pressure gauge 11 is output to the abnormality detection apparatus 20 mentioned later.
The double pipe lance 4 constitutes a pulverized coal blowing lance. As shown in FIG. 2, the double pipe lance 4 includes an inner pipe and an outer pipe arranged concentrically, and a space in the inner pipe forms a pulverized coal passage 4A, and the inner pipe and the outer pipe. A combustion-supporting gas passage 4B is formed in the space between the two.

  And the front-end | tip part of each double pipe | tube lance 4 penetrates the front-end | tip part (side near the tuyere 3 side) of the ventilation pipe 2, and is arrange | positioned in the said ventilation pipe 2 as shown in FIG. The axis of the tip of the double pipe lance 4 is arranged so as to approach the tuyere 3 toward the tip, so that pulverized coal and oxygen gas blow out from the tip of the lance toward the tuyere 3 side. It is possible. In addition, the double pipe lance 4 of this embodiment is set so that the front-end | tip part may be located in the tuyere 3 as shown in FIG.

Pulverized coal from a pulverized coal tank (not shown) is pumped into the pulverized coal passage 4A of the double pipe lance 4 and the pumped pulverized coal is injected from the tip of the pulverized coal passage 4A formed in the inner pipe. It is possible.
A pressure gauge 21 for detecting the pressure in the pulverized coal passage 4A is provided. The detection result of the pressure gauge 21 is output to an abnormality detection device 20 described later.

  As shown in FIG. 2, the inlet of the combustion-supporting gas passage 4B of the double pipe lance 4 is connected to a high-pressure oxygen gas tank 12, and oxygen gas is supplied from the high-pressure oxygen gas tank 12 to the combustion-supporting gas passage 4B. Pumped. From the high pressure oxygen gas tank 12 side (upstream side) to the high pressure oxygen gas tank 12 and the combustion-supporting gas passage 4B, the flow rate adjusting valve 14, the shutoff valve 15, the flow meter 16, the pressure gauge 17, and the reverse A stop valve 18 is interposed. The detection result of the pressure gauge 17 is output to the abnormality detection device 20.

  Here, a combustion space called a raceway 5 exists in the coke deposit layer in the hot air blowing direction ahead of the tuyere 3, and the reducing material is mainly combusted and gasified in this combustion space. The pulverized coal passing through the tuyere 3 from the lance 4 and blown into the raceway 5 is combusted with coke and its volatile matter and fixed carbon. The aggregate of carbon and ash, generally called char, that remains after the volatile matter has been released, is discharged from the raceway as unburned char. The hot air velocity in the hot air blowing direction ahead of the tuyere 3 is, for example, about 200 m / sec, and the region where the oxygen gas exists in the raceway 5 from the tip of the lance 4 is, for example, about 0.3 to 0.5 m. Yes. In addition, when pulverized coal is blown from the double pipe lance 4 and oxygen gas is blown from the outer periphery thereof, mixing of the pulverized coal and oxygen gas is promoted near the lance, and combustion of the pulverized coal starts earlier. It is conceivable that this further increases the combustion temperature near the lance.

Next, processing of the abnormality detection device 20 will be described.
The abnormality detection device 20 has an abnormality in blowing oxygen gas, which is a combustion-supporting gas, from the relationship between the flow velocity Vo of the combustion-supporting gas to the combustion-supporting gas passage 4B and the flow velocity Vp of the pulverized coal to the pulverized coal passage 4A. Is detected. In the abnormality detection device 20 of the present embodiment, the flow rate Vo of the combustion-supporting gas to the combustion-supporting gas passage 4B and the fine powder to the pulverized coal passage 4A based on the detection results of the pressure gauges 11, 17, and 21. The case where the abnormal flow of oxygen gas which is a combustion-supporting gas is detected by determining the flow velocity Vp of charcoal is illustrated.

  Here, Pb is the blowing pressure to the blowing pipe 2 detected by the pressure gauge 11, Po is the pressure of the combustion-supporting gas to the combustion-supporting gas passage 4B detected by the pressure gauge 17, and the pressure to the pulverized coal passage 4A is The pulverized coal pressure is Pp, the flow rate of the flammable gas to the flammable gas passage 4B is Vo, and the flow rate of the pulverized coal to the pulverized coal passage 4A is Vp. The flow velocities Vo and Vp may be obtained by differentiating the flow rate, but in the present embodiment, description will be made on the case of calculating from the pressure.

The abnormality detection device 20 includes a detection information input unit 20A, a combustion-supporting gas flow rate acquisition unit 20B, a pulverized coal flow rate acquisition unit 20C, and an abnormality determination unit 20D.
The detection information input unit 20A inputs detection results from the pressure gauges 11, 17, and 21 as described above. Specifically, the detected values of the blowing pressure Pb to the blowing pipe 2, the pressure Po of the combustion-supporting gas to the combustion-supporting gas passage 4B, and the pulverized coal pressure Pp to the pulverized coal passage 4A are set. input.

The combustion-supporting gas flow rate acquisition unit 20B calculates the combustion-supporting gas flow rate Vo to the combustion-supporting gas passage 4B based on the detected pressure Po and the blowing pressure Pb of the combustion-supporting gas. Specifically, it calculates | requires from the pressure difference of pulverized coal pressure Pp and ventilation pressure Pb based on a following formula.
Vo ² = ko × (Po−Pb)
Here, ko is a gain obtained in advance by experiments or the like.
The pulverized coal flow velocity acquisition unit 20C calculates the pulverized coal flow velocity Vp to the pulverized coal passage 4A based on the detected pulverized coal pressure Pp and the blowing pressure Pb. Specifically, it calculates | requires based on the pressure difference of the pressure Po of combustion-supporting gas, and the ventilation pressure Pb based on the following formula.
^{Vp 2 = kp × (Pp -Pb} )
Here, kp is a gain obtained in advance by experiments or the like.

The abnormality determination unit 20D determines that the combustion-supporting gas is abnormally injected when the calculated flow velocity Vo is larger than the flow velocity Vp and the flow velocity Vp is equal to or lower than a preset flashback speed.
Backfire is a phenomenon in which the flame returns to the fuel supply side when the fuel is burned with an oxidizer (oxygen, etc.) and is determined by the balance between the fuel flow rate and the fuel flow rate. In the present invention, when the pulverized coal is transported in the lance as a gas, the pulverized coal flow rate at which the pulverized coal flow rate is equal to or lower than the combustion rate of the pulverized coal and the combustion-supporting gas is defined as the flashback rate.

The preset backfire speed is determined from the combustion speed with the pulverized coal flow speed and varies depending on the conditions, but in this embodiment, it is set to 14 to 15 m / sec.
Here, the reason for determining that the combustion-supporting gas is abnormally injected is, for example, a case where the combustion-supporting gas passage 4B becomes narrow and a pressure abnormality occurs in the combustion-supporting gas passage 4B.
If the abnormality determination unit 20D determines that the combustion-supporting gas has been injected abnormally, the abnormality notification process is performed to the operator, and for example, the shutoff valve provided in the combustion-supporting gas passage 4B is closed or the combustion-supporting gas is provided. Instead of this, a process such as temporarily supplying an inert gas is performed.
Here, in the abnormality determination, a combustion-supporting gas injection abnormality is determined for each combustion-supporting gas passage of each lance.

(Operation other)
FIG. 4 shows the blowing speed of oxygen gas calculated from the blowing pressure of the blowing pipe 2, the pressure to the combustion-supporting gas passage 4B, and the flow rate supplied to the combustion-supporting gas passage 4B in actual blast furnace operation. Time series data.
The data in FIG. 4 is data when it is estimated that there is no problem in the operation of the blast furnace and there is no abnormality in the injection of the combustion-supporting gas, but the blowing pressure on the hot air side that blows in the combustion-supporting gas is It may be higher than the pressure to the combustion-supporting gas passage 4B. For this reason, it is possible to easily determine whether or not there is an abnormality in the blowing of the combustion-supporting gas by simply comparing the blowing pressure Pb of the blowing pipe 2 and the pressure Po to the combustion-supporting gas passage 4B. Absent.

There is also a situation that the pressure near the tuyere 3 in the furnace cannot be easily obtained.
On the other hand, in the present embodiment, as described above, the combustion-supporting property is simply and accurately determined by the difference between the flow velocity Vo of the combustion-supporting gas and the flow velocity Vp of the pulverized coal and the value of the flow velocity Vp of the pulverized coal. It is possible to determine whether the combustion-supporting gas is abnormally injected due to an abnormality in the pressure of the gas passage 4B.
Specifically, when the flow velocity Vp of the pulverized coal to the pulverized coal passage 4A is equal to or lower than the preset flashback speed and the flow velocity Vo is larger than the flow velocity Vp, it is determined that the combustion support gas is abnormally injected. doing. That is, when the flow velocity Vo is larger than the flow velocity Vp, even though the increase in pressure loss is estimated by the flow velocity Vp being equal to or lower than the preset flashback velocity, the fine powder to the pulverized coal passage 4A The flow velocity Vp of charcoal is also small, and it can be determined that the combustion-supporting gas is blown abnormally.

In the present embodiment, the flow rate Vo of the combustion-supporting gas and the flow rate Vp of the pulverized coal are set to Pb and the pressure of the pressure-supporting gas passage 4 </ b> B detected by the pressure gauge 17. The pressure of gas is Po, and the pulverized coal pressure to the pulverized coal passage 4A is calculated from each pressure of Pp.
Here, if clogging occurs in the middle of the lance up to the tuyere 3, the flow velocity Vp of the pulverized coal in the lance may not be obtained with high accuracy. By determining the flow velocity Vp of the combustion-supporting gas, it is possible to accurately determine the combustion-supporting gas injection abnormality caused by the abnormality in the pressure of the combustion-supporting gas passage 4B.

  Here, in this embodiment, “a pulverized coal passage 4A through which pulverized coal passes is formed at the center and a flammable gas passage through which the flammable gas passes through the outer periphery of the pulverized coal passage 4A. Although the double-pipe lance 4 is exemplified as the pulverized-coal-injection lance in which 4B is formed and the tip portion is disposed in the blower tube 2, the pulverized-coal-injection lance may not be a double-pipe structure. . A lance structure in which a triple pipe structure may be used, or a combustion-supporting gas passage 4B is formed by another pipe arranged non-concentrically outside the pipe that becomes the pulverized coal passage 4A. It does not matter. In the present invention, the structure of the double tube lance 4 is not particularly limited.

DESCRIPTION OF SYMBOLS 1 Blast furnace 2 Air blower 3 Tuyere 3 Each tuyere 4 Double pipe lance 4A Pulverized coal passage 4B Combustion gas passage 11 Pressure gauge 17 Pressure gauge 18 Check valve 20 Abnormality detection apparatus 20A Detection information input part 20B Flammable gas flow rate acquisition unit 20C Pulverized coal flow rate acquisition unit 20D Abnormality determination unit 21 Pressure gauge

Claims (3)

A blow pipe connected to the tuyere of the blast furnace;
A pulverized coal passageway through which pulverized coal passes is formed at the center, and a flammable gas passageway through which the flammable gas passes is formed on the outer peripheral side of the pulverized coal passageway, and the tip portion is in the blast pipe. Using the arranged pulverized coal blowing lance,
In the blast furnace pulverized coal blowing method, the pulverized coal blowing lance is blown into the blast furnace from the tuyere with the supporting gas by the pulverized coal blowing lance.
When the flow velocity of the combustion-supporting gas to the combustion-supporting gas passage is Vo and the flow velocity of the pulverized coal to the pulverization coal passage is Vp,
A blast furnace pulverized coal blowing method, characterized in that when the flow velocity Vo is larger than the flow velocity Vp and the flow velocity Vp is equal to or lower than a preset flashback speed, it is determined that the blowing is abnormal. When the blowing pressure to the blowing pipe is Pb, the pressure of the combustion supporting gas to the combustion supporting gas passage is Po, and the pulverized coal pressure to the pulverizing coal passage is Pp,
2. The flow velocity Vp is calculated from a pressure difference between the pulverized coal pressure Pp and the blowing pressure Pb, and the flow velocity Vo is calculated from a pressure difference between the combustion supporting gas pressure Po and the blowing pressure Pb. Blast furnace pulverized coal injection method described in 1. A blow pipe connected to the tuyere of the blast furnace;
A pulverized coal passageway through which pulverized coal passes is formed at the center, and a flammable gas passageway through which the flammable gas passes is formed on the outer peripheral side of the pulverized coal passageway, and the tip portion is in the blast pipe. The pulverized coal injection lance is used, and the pulverized coal injection lance is used to prevent abnormal combustion of the combustion-supporting gas in the blast furnace operation in which pulverized coal is injected into the blast furnace from the tuyere together with the combustion-supporting gas. A device for detecting,
A blowing pressure detector for detecting a blowing pressure Pb to the blowing pipe;
A combustion-supporting gas pressure detection unit that detects a pressure Po of the combustion-supporting gas to the combustion-supporting gas passage;
A pulverized coal pressure detector for detecting the pulverized coal pressure Pp to the pulverized coal passage,
A combustion-supporting gas flow rate acquisition unit that calculates the flow-rate Vo of the combustion-supporting gas to the combustion-supporting gas passage based on the detected pressure Po of the combustion-supporting gas and the blowing pressure Pb;
A pulverized coal flow rate acquisition unit for calculating a flow rate Vp of the pulverized coal to the pulverized coal passage based on the detected pulverized coal pressure Pp and the blowing pressure Pb;
An abnormality determination unit that determines that the blowing is abnormal when the flow velocity Vo is greater than the flow velocity Vp and the flow velocity Vp is equal to or lower than a preset flashback speed;
A blowing abnormality detecting device comprising:

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