JP2006312756A - Injection lance for gaseous reducing material, blast furnace and blast furnace operation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the dissolved loss of a lance and a blast pipe when injecting gaseous reducing material into a blast furnace. <P>SOLUTION: A injection lance 10 for gaseous reducing material has a triple-tube structure provided with an inner pipe 21, an intermediate pipe 22 and an outer pipe 23. The gaseous reducing material is injected from the inner pipe 21, and cooling liquid is caused to flow in a space between the inner pipe 21 and the intermediate pipe 22, and a space between the intermediate pipe 22 and the outer pipe 23. A distal end of the inner pipe 21 is protruded with respect to the intermediate pipe 22 and the outer pipe 23, and the protruded part is curved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention, for example, injects a gas reducing material such as natural gas, methane gas, coke oven gas, coal gasification gas, hydrogen gas, etc. into the blast furnace, and makes it possible to improve the productivity of the blast furnace. The present invention relates to a lance for blowing, a blast furnace provided with the lance, and a blast furnace operating method.

  Blast furnaces that produce pig iron are generally large facilities, and their construction requires a large amount of funds. If the productivity can be improved, the risk associated with the investment can be reduced. Therefore, the productivity improvement in the blast furnace has been desired.

  It is known that the method of blowing a gas reducing material from the blast furnace tuyere is effective for improving productivity. This is largely due to the following two reasons. One reason is that the gas reducing material does not contain ash. Since other reducing materials such as coke and pulverized coal contain ash, liquid slag is generated in the high temperature region at the bottom of the blast furnace. Since the slag fills the voids in the packed bed, the air permeability deteriorates, preventing the reduction gas necessary for the production of pig iron from being fed into the blast furnace, thereby lowering the upper limit of productivity.

The other is that the gas reducing material has a higher hydrogen content than the carbonaceous material. Gases that are effective for reducing iron oxide include H _{2 and} CO, but H ₂ has a lower gas viscosity and lower pressure loss when flowing through the same packed bed. For this reason, when the gas reducing material is used, the reducing gas can be easily fed into the blast furnace, and the productivity can be improved.

  However, since the gas reducing material generally has a high burning rate and starts burning immediately after being ejected from the lance, measures for preventing the lance from being melted are necessary.

In order to prevent melting damage, it has long been practiced that the lance has a water-cooled structure. For example, Patent Document 1 discloses a lance having a water-cooled triple pipe structure used for injecting pulverized fuel into a blast furnace tuyere. Is disclosed.
Japanese Patent Publication No. 60-402

  Although patent document 1 is a technique for injecting pulverized fuel effectively, the present inventors tried application to gas reducing material injection. When the combustion test of the gas reducing material was actually carried out using a test furnace, it was clarified that although the lance was sufficiently durable, the blow pipe was melted. Since the gas reducing material is ignited and combusted quickly, the combustion rapidly proceeds in the blower pipe, resulting in a very high temperature. When the lance was installed through the blower tube, the gas reducing material was sprayed on the side of the blower tube opposite to the lance, and the blower tube wall was melted on the extension of the lance shaft. Since the combustion rate of the pulverized fuel is generally slower than the combustion rate of the gas reducing material, the technique described in Patent Document 1 can be applied to the powder fuel, but not to the gas reducing material. It is done.

  An object of the present invention is to solve such problems of the prior art and to prevent melting of the lance and the blower pipe when the gas reducing material is blown into the blast furnace.

In order to solve the above problems, the present invention provides the following (1) to (7).
(1) A lance for blowing a gas reducing material, which is inserted through a pipe wall into a blower pipe of a blast furnace and blows a gas reducing material into a blast furnace tuyere,
A triple pipe structure including an inner pipe, an intermediate pipe, and an outer pipe, for blowing a gas reducing material from the inner pipe, and for cooling between the inner pipe, the intermediate pipe, and the intermediate pipe and the outer pipe Configured to circulate a liquid of
A lance for injecting a gas reducing material, wherein the distal end portion of the inner tube protrudes from the intermediate tube and the outer tube, and the protruding portion is curved.
(2) The length of the protruding portion is 2 × (d1−d2) or more and 160 mm or less [where d1: the outer diameter of the outer tube (mm), d2: the outer diameter of the inner tube (mm)]. The lance for blowing the gas reducing material according to the above (1).

(3) A blast furnace provided with a blow pipe provided with a lance for blowing the gas reducing material according to (1) or (2).
(4) The blast furnace according to (3) above, wherein the lance is arranged so that a jet direction of the gas reducing material coincides with a direction of blast furnace blowing.

(5) A triple pipe structure including an inner pipe, an intermediate pipe, and an outer pipe, in which a gas reducing material is blown from the inner pipe, and between the inner pipe, the intermediate pipe, and the intermediate pipe and the outer pipe. Is configured to circulate a cooling liquid.
The tip of the inner pipe is protruded with respect to the intermediate pipe and the outer pipe, and a lance for injecting a gas reducing material having a curved projection is inserted into the blast furnace blast pipe through the pipe wall. And a blast furnace operating method characterized by blowing a gas reducing material into the blast furnace tuyere.
(6) The length of the protruding portion is 2 × (d1−d2) to 160 mm [where d1 is the outer diameter (mm) of the outer tube, and d2 is the outer diameter (mm) of the inner tube]. The method of operating a blast furnace as described in (5) above, wherein
(7) The blast furnace operating method according to the above (5) or (6), wherein the lance is arranged on a blower pipe so that a jet direction of the gas reducing material and a direction of blast furnace blown coincide with each other.

  In the present invention, the tip of the inner pipe is protruded with respect to the intermediate pipe and the outer pipe, and a curved portion is provided in the protruded inner pipe portion, preferably adjusted so that the jet direction of the gas reducing material coincides with the direction of the blast furnace blast. The reason for doing this is as follows. When the lance described in Patent Document 1 was used, the gas reducing material was ejected from the tip of the lance toward the blast furnace blast pipe, so that the temperature of the blast pipe wall on the extension of the lance shaft increased, resulting in melting damage. When the lance is bent so that the direction in which the gas reducing material is ejected coincides with the direction of the air blowing, the melt damage of the air blowing pipe wall is alleviated. However, it is extremely difficult to manufacture a lance having a curved triple pipe structure, and even if it can be manufactured, it is difficult to secure a uniform cooling water flow path width. If there is a portion where the coolant flow path is partially narrowed, there is a possibility that the portion of the lance may be damaged due to poor cooling. Therefore, only the inner tube portion projected from the tip of the lance of the triple tube structure is provided with a curve.

  Moreover, there exists a certain appropriate range for the protruding length of the inner tube. Since the protruding portion is not water-cooled, it is overheated by receiving radiant heat accompanying the combustion of the gas reducing material and convection heat transfer by blast furnace air (hot air), and the temperature increases toward the tip. If it is too long, the tip of the lance will melt. On the other hand, it was found that if the air flow is too short, the gas reducing material is vigorously stirred and intensively burned in the vicinity of the lance due to the vortex generated when the air flow is disturbed at the step portion between the outer tube and the inner tube. Therefore, it is preferable to adjust the protruding length of the inner tube to an appropriate range as will be described later in order to prevent melting damage.

  In a lance for injecting a gas reducing material having a triple pipe structure including an inner tube, an intermediate tube, and an outer tube, the tip of the inner tube protrudes from the intermediate tube and the outer tube, and the protruding portion Therefore, it is possible to prevent the blower pipe from being melted by the ejected gas reducing material, and to improve the productivity of the blast furnace.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view showing an outline of a blast furnace 1 provided with a gas reducing material blowing lance of the present invention. The blast furnace 1 has a furnace top part 2, a shaft part 3, a furnace belly part 4, and a furnace bottom part 5 in order from the top. The furnace top part 2 of the blast furnace 1 is provided with a charging device 6. A raw material 7 mainly composed of iron ore and coke is charged into the blast furnace 1 from the apparatus 6. A plurality of tuyere 8 for blowing hot air for generating a reaction in the furnace is provided in the furnace bottom portion 5 in a circumferential shape, and hot air is blown into the blast furnace 1 from the blower tube 9 through the tuyere 8. . A lance 10 for injecting a gas reducing material is inserted into the blower tube 9 through the tube wall.

  A raceway 11 is formed in a region blown from the tuyere 8. The raceway 11 is a space formed by the coke in front of the tuyere being pushed away by the energy of the gust of wind blown from the tuyere 8. Hot water and slag produced by the in-furnace reaction are present as a hot metal layer and a slag layer in the hot water reservoir 12 present in the furnace bottom 5, and the hot metal and slag are periodically discharged from a plurality of outlets 13. The In this case, the plurality of tap holes 13 alternately perform opening and closing. Reference numeral 14 denotes a furnace core.

  FIG. 2 is a perspective view of a main part schematically showing a lance for blowing the gas reducing material of the present invention, and FIG. 3 is a cross-sectional view. The lance 10 has a triple pipe structure, and includes an inner tube 21, an intermediate tube 22, and an outer tube 23, respectively. The inner tube 21 is a flow path for a gas reducing material. The gas reducing material may be a gaseous reducing material at the stage of passing through the lance 10 when being blown into the blast furnace 1, and for example, natural gas, methane gas, coke oven gas, coal gasification gas, hydrogen gas, or the like may be used. it can.

  The intermediate pipe 22 on the base end side of the lance 10 is provided with a cooling liquid intake 25. A cooling liquid such as cooling water is introduced from the cooling liquid intake 25, and the base of the outer pipe 23 is provided. The cooling liquid flows around the inner pipe 21 by discharging from the discharge port 26 provided on the end side. As the cooling liquid, for example, water, various aqueous solutions, oil, and the like can be used, but water or various aqueous solutions are generally used because of easy handling. As an example of the aqueous solution, a solution obtained by dissolving a chemical in a small amount of water for preventing corrosion in the cooling pipe and clogging of the pipe due to algae growth is used. Whether it is an aqueous solution or oil, it is necessary to avoid corrosive liquids. In addition, since the cooling capacity is suddenly lost when the liquid reaches the boiling point, the temperature of the drainage is always monitored, and if it is water, it is desirable to use it at 70 ° C. or less at maximum. For other liquids, it is desirable to manage the drainage temperature at about 70% of the boiling point (Celsius standard) or less.

  The tip side of the lance 10 has a portion (hereinafter referred to as “tip tip 24”) from which only the inner tube is projected. The tip 24 is curved with a predetermined curvature. This curvature may be applied to the entire tip end 24 (that is, the entire protruding portion) or to a part of the tip end 24.

  As shown in FIG. 4, the lance 10 provided with the tip tip 24 bent in this way is arranged in the blower tube 9, and as shown in FIG. 4, the blowing direction of the gas reducing material is the hot air flowing through the blower tube 9 of the blast furnace 1. Mounted in the same direction as the direction of travel. That is, it arrange | positions so that the injection direction of a gas reducing material and the direction of blast furnace ventilation may correspond. As a result, it is possible to prevent the blown-out gas reducing material from being burned in the vicinity of the blower tube 9, thereby preventing the wall 9 a of the blower tube 9 on the side facing the lance 10 from being melted. Due to such a melting damage prevention effect, the flow rate and flow rate of the gas reducing material blown by the lance 10 can be made larger than before, so that the productivity of the blast furnace can be improved. Here, “the direction in which the gas reducing material is ejected coincides with the direction in which the blast furnace air blows” specifically means that the direction in which the gas reducing material is ejected from the tip 24 of the lance 10 as shown in FIG. The extension line may be within the range of the outlet diameter of the tuyere 8 provided with a reduced diameter toward the furnace of the blast furnace 1. In such a direction, the gas reducing material ejected from the lance 10 can be smoothly introduced into the blast furnace 1 through the tuyere 8.

  The tip 24 may extend the inner tube 21 as it is, or after a lance having a triple tube structure is prepared, a single tube having the same diameter as the inner tube 21 and having a curvature is prepared separately. Alternatively, the inner tube 21 may be welded to the tip portion. The reason for this is that although the high-temperature durability of the welded portion generally decreases, in the case of the lance 10, the welded portion of the tip tip 24 and the inner tube 21 is a portion where the effect of water cooling can be sufficiently expected, so there is a concern that it will be exposed to high temperatures. It is because there is no.

  Next, the range of the length of the tip 24 (that is, the length of the protruding portion of the inner tube 21) will be described with reference to FIGS. The inventors manufactured prototypes in which the length L of the tip tip 24 of the lance 10 was variously changed, and actually conducted a blow test to investigate its durability. FIG. 5 shows an example in which the length L of the tip 24 is long, and FIG. 6 shows a short example. Specifically, in order to examine the relationship between the outer diameter d1 of the outer tube 23 of the lance 10, the outer diameter d2 of the inner tube 21, and the length L of the tip 24, the length L is changed to test for the presence or absence of melting. Was done.

  As a result, when the length L exceeded 160 mm, a part of the tip portion was melted. While the length L is short, the tip 24 is also cooled by conduction heat transfer with the water cooling part, but as the length L increases, the temperature of the tip of the tip 24 increases and the length L Is considered to reach the limit at 160 mm. This upper limit of 160 mm did not depend much on the type and flow rate of the gas reducing material. Although the ignition and burning rate of the gas reducing material varies depending on the type of the reducing material, it is estimated that there is no difference that affects the melting damage of the tip 24. On the other hand, with respect to the flow rate of the gas reducing material, when the flow rate of the gas reducing material is increased, the amount of heat generated by the combustion of the gas reducing material increases, so that the thermal load on the tip tip 24 increases. However, since the gas reducing material is injected at a low temperature (normal temperature), it acts as a coolant for the tip, and as the flow rate increases, the cooling ability of the tip 24 also increases. As a result, it was estimated that the flow rate of the gas reducing material did not greatly affect the melting damage of the tip 24.

  On the other hand, it was found that when the value of the length L of the tip 24 is decreased, the tip 24 is partially melted at a certain length L. The reason for this is that, as schematically illustrated in FIG. 6, the hot air blown to the blast furnace at the step portion between the lance body and the tip end 24 generates vortex, and the mixing of the gas reducing material ejected from the tip end 24 and the hot air is It is considered that this is accelerated and ignition combustion occurs in the vicinity of the tip end 24 to increase the heat load on the tip end 24.

  The durability test results are shown in FIG. In this test, the outer diameter d1 of the outer tube 23 was 60.5 mm, and the outer diameter d2 of the inner tube 21 was 42.2 mm or 32.2 mm. This durability test was conducted using a test combustion furnace, and if it has a durability of 24 hours or more in this test combustion furnace, it has been confirmed that it has a durability of 4 months or more in actual equipment. It is. It is sufficient that the actual machine can be blown without melting for at least 4 months. The reason for this is that there is a major repair called resting wind every four months, and even if it melts down, it can be replaced at this opportunity. For this reason, in FIG. 7, 10 prototype lances were tested, and the percentage of those that were melted within 24 hours was shown.

  As shown in FIG. 7, it became clear that melting loss occurred when the length L was shorter than 2 × (d1−d2). Further, when the length L exceeded 160 mm, melting damage occurred regardless of the values of the outer diameter d1 and the outer diameter d2.

From the above test results, a desirable range of the length L of the tip 24 is summarized as follows.
2 × (d1-d2) ≦ L ≦ 160mm
[However, d1: the outer diameter (mm) of the outer tube, d2: the outer diameter (mm) of the inner tube]

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not restrict | limited by this. In Examples and Comparative Examples, a gas reducing material was blown in an actual blast furnace using the lance 10 of the present invention and a comparative lance. That is, a gas reducing material blowing lance was installed through the wall of the blast pipe 9 of the blast furnace 1 having the same configuration as that of FIG. 1 and having an internal volume of 3223 m ³ . In addition, in the Example, it was made for the jet direction of a gas reducing material and the direction of blast furnace ventilation to correspond.

In the examples and comparative examples, methane (CH ₄ ) gas was used as the blowing gas reducing material. Methane gas is the main component of natural gas, and since it is relatively easy to obtain as a gas for blast furnace injection, it was selected as the injection gas in the examples and comparative examples, but other examples include coke oven gas or coal. Any gas generated by gas or a gas that acts as a reducing material after entering the blast furnace, such as city gas or hydrogen gas, can be substituted.

  Table 1 describes changes in specifications of each blast furnace and changes in production amount in each example and comparative example under the conditions of constant air pressure and constant tuyere temperature. In order to increase the production volume, there are methods such as increasing the air flow rate (increasing the air pressure) or increasing the oxygen enrichment rate (resulting in an increase in the tuyere temperature). Since the pressure is maximum at 0.38 MPa and the oxygen enrichment rate is also about 2300 ° C. where the tuyere temperature is close to the upper limit, it can be considered that the production amount was maximum in each example.

  Example 1 shows the result when the gas reducing material is injected into the blast furnace at 20 kg / tp (meaning 20 kg per ton of hot metal; the same applies hereinafter) using the injection lance 10 of the present invention. ing. The production amount (slagging amount) was 7735 t / d, and it was possible to produce pig iron about 1.15 times the production amount when no gas reducing material was blown (Comparative Example 1).

  Example 2 has shown the result at the time of blowing a gas reducing material into a 60 kg / tp blast furnace using the blowing lance 10 of this invention. The production amount (the amount of brewing) was 8058 t / d, and it was possible to produce pig iron approximately 1.19 times the production amount when no gas reducing material was blown (Comparative Example 1).

  Example 3 shows the results when the gas reducing material was blown into a 12 kg / tp blast furnace using the blowing lance 10 of the present invention. The production amount (slagging amount) was 7574 t / d, and pig iron that was about 1.12 times the production amount when no gas reducing material was blown (Comparative Example 1) could be produced.

  Example 4 has shown the result at the time of blowing a gaseous reducing material into an 11kg / tp blast furnace using the blowing lance 10 of this invention. The production amount (slagging amount) was 7381 t / d, and pig iron that was about 1.09 times the production amount when no gas reducing material was blown (Comparative Example 1) could be produced.

  Comparative Example 1 shows an example of blast furnace operation in the case where the gas reducing material ratio is not injected. As shown above, the upper limit of the production amount is when the gas reducing material is injected. It became low compared.

  The comparative example 2 shows the case where the gas reducing material is blown by the lance 50 of the conventional water-cooled triple pipe structure which does not have the protrusion part (tip tip 24) of the inner pipe as shown in FIG. Yes. In this case, as shown in FIG. 8 (b), a temperature sensor 51 is attached in the vicinity of the intersection of the extension line of the gas blowing lance 50 and the blower pipe wall, and when the temperature of the blower pipe wall rises, in order to prevent melting damage The injection of the gas reducing material was stopped. As a result, the stop time of the gas reducing material was long, and only 0.2 kg / tp of the gas reducing material was injected on average per day. For this reason, the production volume improvement effect by gas reducing material injection was not able to be acquired.

Sectional drawing which shows the schematic structure of a blast furnace typically. The principal part perspective view of the lance for gas reducing material blowing. Sectional drawing which shows typically schematic structure of the lance for gas reducing material blowing. The figure explaining the state which mounted | wore the ventilation pipe | tube with the lance for gas reducing material blowing. The principal part sectional drawing of the lance for gas reducing material blowing. The principal part sectional drawing of the lance for gas reducing material blowing. The drawing explaining the relationship between the length of the tip and the melting rate. Drawing used for explanation of lance of prior art.

Explanation of symbols

10 Lance 21 Inner tube 22 Intermediate tube 23 Outer tube 24 Tip tip 25 Cooling liquid inlet 26 Discharge port

Claims (7)

A lance for blowing a gas reducing material, which is inserted through the pipe wall into the blast furnace pipe and blows the gas reducing material into the blast furnace tuyere,
A triple pipe structure including an inner pipe, an intermediate pipe, and an outer pipe, for blowing a gas reducing material from the inner pipe, and for cooling between the inner pipe, the intermediate pipe, and the intermediate pipe and the outer pipe Configured to circulate a liquid of
A lance for injecting a gas reducing material, wherein the tip of the inner tube protrudes from the intermediate tube and the outer tube, and the protrusion is curved.   The length of the protruding portion is 2 × (d1−d2) or more and 160 mm or less [where d1: the outer diameter (mm) of the outer tube, d2: the outer diameter (mm) of the inner tube]. The lance for blowing the gas reducing material according to claim 1.   A blast furnace provided with a blower pipe provided with the lance for injecting the gas reducing material according to claim 1 or 2.   4. The blast furnace according to claim 3, wherein the lance is arranged so that a jet direction of the gas reducing material coincides with a direction of blast furnace blowing. 5. A triple pipe structure including an inner pipe, an intermediate pipe, and an outer pipe, for blowing a gas reducing material from the inner pipe, and for cooling between the inner pipe, the intermediate pipe, and the intermediate pipe and the outer pipe Configured to circulate a liquid of
The tip of the inner pipe is protruded with respect to the intermediate pipe and the outer pipe, and a lance for injecting a gas reducing material having a curved projection is inserted into the blast furnace blast pipe through the pipe wall. And a blast furnace operating method characterized by blowing a gas reducing material into the blast furnace tuyere.   The length of the protruding portion is 2 × (d1−d2) or more and 160 mm or less [where d1: the outer diameter (mm) of the outer tube, d2: the outer diameter (mm) of the inner tube]. The blast furnace operating method according to claim 5. The blast furnace operating method according to claim 5 or 6, wherein the lance is arranged so that a jet direction of the gas reducing material coincides with a direction of blast furnace blowing.

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