JPH09263807A - Method for injecting pulverized coal into blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent ash content from being stuck to a combustion branched pipe at the tip part of a tuyere, to improve the combustion ratio of pulverized coal and to obtain the stable operation of a blast furnace by comparing the previously obtd. fusing temp. of the ash content in the pulverized coal and the combustion temp. of the pulverized coal and deciding the position of the tip part of a burner at the time of injecting the pulverized coal. SOLUTION: At the time of injecting the pulverized coal from the burner 6 passing through the side wall 1a of a blasting branched tube 1 and projecting inward, a first process for previously obtaining the fusing temp. of the ash content contained in the injected pulverized coal, a second process for obtaining the combustion temp. of the injected pulverized coal and a third process for comparison-calculating the fusing temp. and the combustion temp. of the pulverized coal are provided. The tip part of the burner 6 is advanced/retreated so that the result of arithmetic operation based on the third process becomes lower than the fusing temp. of the ash content. Then, as a combustion temp. detecting means 3 of the pulverized coal injected from the burner 6, an optical temp. measuring means is used, and a hydraulic driving means 8 is preferably used for the advance/retreat of the burner 6.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for blowing pulverized coal from tuyere of a blast furnace.

[0002]

2. Description of the Related Art Generally, in many blast furnaces, a large amount of pulverized coal, which is an alternative fuel for coke, is blown from the tuyere. The more the blow-in amount can be increased, the smaller the amount of coke used and the less the burden of the coke oven for producing coke. Further, considering the unit price difference between coke and pulverized coal, it is possible to significantly reduce the manufacturing cost. However, pulverized coal has a disadvantage that it has a lower combustibility than auxiliary fuels such as heavy oil and natural gas, and contains a large amount of ash that remains without being combusted. Therefore, unburned pulverized coal is generated at the tuyere, and the unburned pulverized coal is accumulated in the blast furnace, which hinders stable operation of the blast furnace. Further, the ash deposits contained in the pulverized coal adhere to and accumulate on the tuyere and the blast branch pipe, closing the blast branch pipe, which also contributes to the hindered stable operation of the blast furnace.

The pulverized coal is blown out from the tip of the blowing burner into the blast branch pipe and immediately heated by the ambient temperature.
It ignites when it reaches a certain temperature. It is known that after ignition, the combustion of volatile matter in coal proceeds at once, and at the same time, the combustion of solid carbon proceeds gradually. FIG. 2 shows the combustion test results obtained by measuring the combustion temperature distribution and the combustion efficiency of the pulverized coal blown from the tip of the burner using a test combustion furnace. It is understood that the combustion temperature of pulverized coal rapidly rises from a point of about 100 mm ejected from the tip of the burner, reaches the maximum in the vicinity of 400 to 600 mm, and the combustion rate also sharply increases in the vicinity of 100 mm. From the phenomenon of Fig. 2, when the pulverized coal is blown from the tip of the burner that penetrates the side wall of the hot air branch pipe that sends hot air to the blast furnace and projects inward, it depends on the position of the tip of the burner. It is presumed that the amount of unburned pulverized coal blown inside changes greatly.
As a known technique for reducing the amount of unburned pulverized coal, there is Japanese Patent Publication No. 60-53081. According to the method disclosed in this publication, there is disclosed a method in which the tip of the burner is positioned on the side of the blast branch pipe which is 100 to 350 mm or more upstream from the boundary between the blast branch pipe and the tuyere.

As described above, in order to maintain a good combustion state, it is desirable to keep the tip position of the burner as far away from the furnace of the blast furnace as possible so that the combustion of pulverized coal proceeds from the blow branch pipe to the tuyere. On the other hand, the ash content melted by the combustion temperature of the pulverized coal adheres and re-condenses on the tuyere and the inner wall of the blast branch pipe, but to prevent the ash content melted by the combustion of the pulverized coal from adhering to the tuyere and the blast branch pipe. The tip of the burner should be located inside the furnace as much as possible.

[0005]

However, since the ash structure of the pulverized coal blown into the blast furnace changes depending on the brand of the pulverized coal blown in, it is extremely difficult to prevent this ash deposit. Further, it has been demanded that the pulverized coal is stably blown into the blast furnace for combustion, and that the combustion efficiency of the pulverized coal is maximized without adhering the burned ash to the tuyere tip and the combustion branch pipe of the blast furnace.

The present invention has been made in order to solve the above problems, and in particular, by identifying the burner tip position where the ash adheres even if the operating conditions of the blast furnace change, the ash adhesion can be prevented. It is an object of the present invention to provide a method for blowing pulverized coal into a blast furnace that eliminates pulverized coal and maximizes the combustion rate of pulverized coal.

[0007]

A method for blowing pulverized coal into a blast furnace according to the present invention is a method in which pulverized coal is blown from a burner which penetrates a side wall of a blast branch pipe for feeding hot air into the blast furnace and projects inside the wall. In the first step, the melting temperature of the ash contained in the pulverized coal blown into the blast furnace is determined in advance, the second step of determining the combustion temperature of the pulverized coal blown from the burner, and the ash content of the pulverized coal is determined. A third step of comparing and calculating a melting temperature and the combustion temperature, and a method of moving the tip of the burner forward and backward so that the calculation result of the third step is lower than the melting temperature of the ash.

More specifically, it is a method of using an optical temperature measuring means as a means for obtaining the combustion temperature of the pulverized coal blown from the burner.

More specifically, it is a method of moving the burner forward and backward by using hydraulic pressure.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the method for blowing pulverized coal into a blast furnace according to the present invention will be described below with reference to the drawings. A reference numeral 1 in FIG. 1 denotes a tubular blower branch pipe, and a burner 6 is provided by being inserted into a first hole 5 formed on a side surface of the blower branch pipe 1, and a second blower pipe is provided. The thermometer 3 is inserted into the hole 5a, and the thermometer 3
Of the air blower traverses the tuyere 2 of the blower branch pipe 1 to form a measurement range 4. A well-known optical temperature measuring means is used as the thermometer 3. The thermometer 3 is an optical radiation thermometer that measures the temperature from the energy of the light of the flame of the pulverized coal burned from the burner 6 of the first hole 5. The temperature measuring range of the thermometer 3 is arranged so that the extension line of the second hole 5a to the inside of the furnace overlaps the inner surface of the tuyere 2. In the measuring range 4, the light from the inside of the furnace is measured by the thermometer. It is arranged so that 3 is not caught. Further, the above-mentioned burner 6 is provided so as to be able to move in and out by the hydraulic cylinder 8 of the burner holding portion 7, and its tip can be freely moved in and out.

Next, the operation will be described. The result of measuring the combustion temperature of the pulverized coal with the thermometer 3 is compared with the melting temperature of the ash content of the pulverized coal currently blown into the blast furnace through the burner 6. In comparison, if the combustion temperature is high, the operation is performed so that the tip of the burner 6 enters the inside of the blower branch pipe 1. When the burner 6 is driven in and out, the hydraulic cylinder 8 provided in the burner holding portion 7 advances and retracts the burner 6 at a preset pitch, and when the burner 6 moves one pitch, the temperature is measured again by the thermometer 3 to optimize the operation. Determine the burner tip position.

[0012]

EXAMPLES Table 1 in Table 1 below shows the operating conditions measured and the physical properties of pulverized coal. Table 1 shows the physical property values of three types of pulverized coal of A, B, and C. The operating conditions of the blast furnace and the pulverized coal blowing ratio are 80 to 1 using the pulverized coal having different physical property values.
55 kg / t, air humidity 25-35 g / Nm ³ , oxygen enrichment rate 1.5-3.5%, hot air temperature 1160-1220 ° C.
The actual operation was performed under the following four conditions. At this time, the ash content adhering to the tuyere and the inner wall of the branch pipe was visually observed through a peephole behind the tuyere.

[0013]

[Table 1]

3, 4 and 5 show the tip of tuyere 2 and the tip of burner 6 when the pulverized coal A, B and C shown in Table 1 is blown from burner 6 into a blast furnace (not shown). The result of measuring the combustion temperature with the distance and the thermometer 3 is shown. In the operating condition (1) of FIG. 3 using the pulverized coal A, the distance where ash is not deposited is the position where the burner is retracted 640 mm from the tuyere, and the operating condition (4) is also the 580 mm point. For the pulverized coal brand B in FIG. 4, the operating condition (7) is 570.
It is shown that ash adhesion can be avoided if done inside mm, 670 under operating conditions (9) of pulverized coal brand C in FIG.
mm. Thus, by controlling the tip position of the burner 6 according to the ash melting point of the pulverized coal and the operating conditions, it is possible to prevent the molten ash from adhering to the tip of the tuyere 2 or the blower branch pipe 1. The method of blowing pulverized coal into the blast furnace is summarized as follows. That is, the side wall 1a of the blast branch pipe 1 for sending hot air into the blast furnace penetrates through the wall 1a.
In the method of blowing pulverized coal from the burner 6 which is projected to the inside of a, the first step of previously determining the melting temperature of the ash contained in the pulverized coal to be blown into the blast furnace, and the combustion of the pulverized coal blown from the burner The second step of obtaining the temperature, the third step of comparing and calculating the melting temperature of the ash of the pulverized coal and the combustion temperature, and the burner of the burner so that the calculation result of the third step is lower than the melting temperature of the ash. While moving the tip forward and backward, an optical temperature measuring means is used as a means for obtaining the combustion temperature of the pulverized coal blown from the burner 6, and the burner is moved forward and backward using hydraulic pressure.

[0015]

Since the method of blowing pulverized coal into the blast furnace according to the present invention is configured as described above, the following effects can be obtained. That is, conventionally, the burner tip position had to be excessively inside the blast furnace for ash deposition control, but since the burner tip position to which ash deposits can be accurately grasped by the present invention, the range in which deposition does not occur is prevented. Thus, the combustion amount of pulverized coal can be maximized.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an embodiment of a method for blowing pulverized coal into a blast furnace according to the present invention.

FIG. 2 is a diagram illustrating a combustion state of pulverized coal.

FIG. 3 is a diagram showing the relationship between the distance between the tuyere tip and the burner tip and the measured temperature.

FIG. 4 is a diagram showing the relationship between the distance between the tuyere tip and the burner tip and the measured temperature.

FIG. 5 is a diagram showing the relationship between the distance between the tuyere tip and the burner tip and the measured temperature.

[Explanation of symbols] 1 blower branch pipe 1a wall 2 tuyere 3 thermometer 4 measurement range 5 first hole 5a second hole 6 burner 7 burner holder 8 hydraulic cylinder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akiyoshi Sugano 11-1 Showa-cho, Kure City, Hiroshima Prefecture Nisshin Steel Co., Ltd. Kure Steel Works

Claims (3)

[Claims] 1. A method of blowing pulverized coal from a burner (6) which penetrates a side wall (1a) of a blast branch pipe (1) for feeding hot air into a blast furnace and projects inside the wall (1a). A first step of determining the melting temperature of the ash contained in the pulverized coal blown into the blast furnace, a second step of determining the combustion temperature of the pulverized coal blown from the burner, a melting temperature of the ash content of the pulverized coal and the above A method for injecting pulverized coal into a blast furnace, which comprises advancing and retracting a tip of the burner so that a calculation result of the combustion temperature is compared and a calculation result of the third step is lower than a melting temperature of the ash. 2. The method for injecting pulverized coal into a blast furnace according to claim 1, wherein an optical temperature measuring means is used as a means for obtaining a combustion temperature of the pulverized coal blown from the burner (6). 3. The method for injecting pulverized coal into a blast furnace according to claim 1, wherein the burner (6) is advanced and retracted using hydraulic pressure.