JP2631439B2 - Nozzle for injecting pulverized coal into furnace of iron making device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle for blowing pulverized coal into a furnace of an iron making apparatus and a method of manufacturing the nozzle.

[0002]

2. Description of the Related Art A nozzle for blowing pulverized coal into hot air is provided inside a tuyere for supplying hot air to a furnace in order to generate a heavy oil combustion flame in a furnace such as a blast furnace. This nozzle is usually a PCI (PULVERIZED COAL I
(NJECTION: pulverized coal injection) This is called a lance, and is used to supply pulverized coal by injecting pulverized coal passing through the tuyere into heavy oil combustion flame and hot air. This PC
The I lance is hot at the tip, ie 1100-1300 °
C lance base material (SU)
S 310S) undergo high-temperature oxidation and abrasion (metal softening due to high temperature) in a short period of time. For this reason, a mantle tube (air supply nozzle) is conventionally provided outside the pulverized coal discharge nozzle, compressed air is forcibly sent inside the mantle tube, and the nozzle body (PCI lance) is air-cooled. Protection is provided.

More specifically, referring to FIGS. 3 and 4, a PCI lance a is attached to a high-temperature hot air introduction pipe j for supplying high-temperature hot air to a blast furnace as shown in FIG. Charcoal f is supplied to the heavy oil supply pipe. In FIG. 4, k indicates a tuyere of the high-temperature hot air introduction pipe j, m indicates a water supply pipe for sending tuyere cooling water, and n indicates a heavy oil supply pipe.
The tuyere k of the high-temperature hot air introduction pipe j is provided on a furnace wall p formed of a refractory material, and a furnace body constituted by the furnace wall p contains hot metal iron q. Then, a combustion flame is radiated from the tuyere k into the furnace, and the hot metal is heated. As shown in FIG. 3, a PCI lance a generally used today is provided with an air supply nozzle c outside a pulverized coal discharge nozzle b and has a double pipe. Called heavy pipe lance. Specifically, the pulverized coal discharging nozzle b supplies the pulverized coal f to the heavy oil supply pipe, the air supply nozzle c sends the compressed air h sent from the air supply pipe g, and the heavy oil supply from the tip opening e. Release into tube. As described above, the air supply nozzle c cools the vicinity of the tip opening d of the pulverized coal discharging nozzle b exposed to a high temperature by the compressed air h.

[0004]

However, the use of compressed air h for cooling the nozzle body a when heating the hot metal in the furnace causes a decrease in the temperature inside the furnace in the converter and the blast furnace. Heat loss has become a problem that cannot be overlooked. In addition, as described above, in order to maintain the material of the PCI lance (nozzle main body a), the conventional method of cooling the PCI lance (nozzle main body a) using the compressed air h (usually the tip of the PCI lance) The operating temperature condition is around 1220 ° C.). During the high-temperature combustion, the tip of the PCI lance (nozzle body a) is oxidized, worn, and carbonized by the high-temperature hot air in a short period of time. A short-term exchange is required. For this reason, in order to stably supply the pulverized coal, heat resistance, oxidation resistance, and abrasion resistance of the PCI lance material are required, and the need for the cooling air is eliminated. On the other hand, proposals have been made as disclosed in JP-A-59-136473 and JP-A-01-062346. Each of these publications discloses a sprayed coating formed on a pulverized coal blowing nozzle. The invention disclosed in Japanese Patent Application Laid-Open No. Sho 59-136473 has a main object of improving abrasion resistance by forming a sprayed coating on a nozzle. It does not do. Therefore,
Despite some efforts such as fusing treatment, heat resistance was insufficient. For example, as a fusing treatment, after preheating to 900 ° C., the surface 1050 ° C.
Is described, but boron silicon is lifted by such a treatment. Therefore,
There is also a statement that it could be used for 5 years, but if this statement is followed, it is probable that the use temperature was lower than 1000 ° C. Japanese Unexamined Utility Model Publication No. 01-062346 discloses that the effect of extending the lance by improving the heat resistance by ceramic spraying is listed as an effect, but this type is also omitted from the publication and explicitly described. However, in practice, the lance is doubled and the life of the lance is longer than before, assuming that the lance is cooled by compressed air. Therefore, when any of the publications described above is used in an iron making apparatus that processes iron having a melting temperature exceeding 1400 ° C., it is necessary to double the nozzles and perform cooling by air as in the past. It is not intended to improve the energy loss in the furnace due to such cooling. As described above, in spite of the proposals in the above-mentioned publications, the pulverized coal injection nozzle has been a hindrance factor for improving the energy loss in the furnace of the iron making apparatus. An object of the present invention is to solve the above problems.

[0005]

Therefore, the pulverized coal injection nozzle into the furnace of the iron making apparatus according to the first invention of the present application is arranged in a high-temperature hot air introduction pipe 100 for generating a combustion flame in the furnace of the iron making apparatus. It is provided to supply pulverized coal into high-temperature hot air, and has the following configuration. That is, at least the tip portion 10 of the cylindrical nozzle 1 is formed with the thermal spray coating 2 for heat insulation and oxidation prevention. Thermal spray coating 2
Is sprayed between a first layer formed by spraying a base on the surface of the nozzle 1 and a second layer formed thereon by spraying, and, if necessary, between the first layer and the second layer. And an intermediate layer formed. The first layer is formed as a base sprayed layer using a composition of a nickel chromium alloy or an alloy containing at least one of aluminum, yttrium, and titanium in the alloy. The second layer coats the first layer as a zirconia-based thermal spray coating containing at least one of yttria, magnesium, yttria, and ceria on the zirconia composite. The intermediate layer is formed as a buffer layer by mixing the material used for the first layer and the material used for the second layer at an appropriate ratio.
The method for producing a pulverized coal injection nozzle into a furnace of an iron making apparatus according to the second invention of the present application is a method for manufacturing pulverized coal in a high temperature hot air introduction pipe 100 which is disposed in a high temperature hot air introducing pipe 100 for generating a combustion flame in a furnace of the iron making apparatus. Is sprayed on at least the tip 10 of the cylindrical nozzle 1 for the pulverized coal blowing nozzle for supplying
The thermal spray coating 2 is formed for heat insulation and oxidation prevention, and has the following configuration. That is, the formation of the above-mentioned thermal spray coating 2 is performed by spraying the first layer on
The second layer is sprayed thereon, and the first layer and the second
This is performed by forming an intermediate layer by thermal spraying between the first and second layers. The first layer is formed as a base sprayed layer using a nickel chromium alloy composition or an alloy containing at least one of aluminum, yttrium, and titanium in the alloy. In the second layer, the zirconia composite is coated with a first zirconia-based thermal spray coating containing at least one of yttria, magnesium, yttria, and ceria.
Cover the layer. The intermediate layer is formed as a buffer layer by mixing the material used for the first layer and the material used for the second layer at an appropriate ratio.

[0006]

According to the first aspect of the present invention, the nozzle for blowing pulverized coal into the furnace of the iron making apparatus according to the first aspect of the present invention is used for forming the sprayed coating 2 on the first layer and the second layer, which are used for heat insulation, oxidation resistance and wear prevention. The most suitable material is adopted, and furthermore, since it is formed as a multi-layer sprayed layer, it has extremely excellent heat resistance, oxidation resistance and abrasion resistance compared to the conventional single sprayed layer. Has wear properties. Therefore, the nozzle 1 can be used for a long time without supplying compressed air for cooling to protect the nozzle 1. In particular, when an intermediate layer is provided as a buffer layer, the first layer and the second layer are less likely to be separated due to a difference in coefficient of thermal expansion and the like, which is more effective. Furthermore, a specific method for manufacturing the nozzle according to the first invention can be provided by the method for manufacturing a pulverized coal injection nozzle into the furnace of the iron making apparatus according to the second invention of the present application.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. 1 and 2 show an embodiment of the present invention. The nozzle for blowing pulverized coal into the furnace according to the present invention includes a cylindrical nozzle 1, a front flange portion 11 for fixing the nozzle 1 to the high-temperature hot air introducing pipe 100 by bolting, and the like. And a rear flange portion (12) connected to the charcoal supply pipe (13). Reference numeral 14 in FIG. 1 denotes a flange provided on the pulverized coal supply pipe 13 side. Reference numeral 15 in FIG. 1 denotes a handle that can be held when the nozzle 1 is carried for installation or the like. This handle 15
Can be implemented without being provided if unnecessary.

[0008] At least the front end portion A of the cylindrical nozzle 1 is sprayed to form a sprayed coating 2 for heat insulation, oxidation and wear prevention. The tip A is connected to the high-temperature hot air introduction pipe 10.
0 and exposed to high-temperature hot air.
This is the part that receives the most heat. This sprayed part is not limited to the position of the tip A shown in the figure,
It can be changed as needed, for example, it is also possible to form a thermal spray coating 2 by performing thermal spraying from the front end of the nozzle 1 to the front flange portion 11 or from the front end to the rear flange portion 12. It is also possible to form a thermal spray coating 2 by performing thermal spraying on the entirety 1. In particular, thermal spray coating 2
Is more effective if it is formed not only on the surface of the tip A but also on the inner peripheral surface of the tip A of the nozzle 1. Normally, the pulverized coal blows through the inside of the nozzle 1, so that the temperature rise does not occur as much as the outside of the nozzle 1, but this is because the effect of extending the life of the nozzle 1 is obtained in terms of preventing oxidation and wear. As described above, when the thermal spray coating 2 is also formed on the inner peripheral surface of the distal end portion A of the nozzle 1, the thermal spraying is performed over the same range as the surface of the distal end portion A of the nozzle 1 (width along the front-rear direction of the nozzle 1). Although the coating 2 may be formed, the above-described effect can be obtained even if the thermal spray coating 2 is formed only at a portion slightly entering from the tip of the nozzle 1. Of course, if it is not necessary, the thermal spray coating 2 may be formed only on the surface of the tip A.

A preferred example of the formation of the above-mentioned thermal spray coating will be described in detail below. At the tip of the nozzle 1, gas spraying or plasma spraying or gas high-speed spraying is used.
The thermal spray coating 2 is formed. The thermal spray coating 2 includes a first layer serving as a base, a second layer formed on the first layer, and a first layer.
Desirably, it comprises a layer and an intermediate layer located between the second layers (not shown). That is, the first layer is formed by thermal spraying, the intermediate layer is formed thereon by thermal spraying, and the second layer is further formed on the intermediate layer by thermal spraying.

The first layer is made of a nickel-chromium alloy (Ni
(Cr alloy, Ni / Cr: 80/20% to 20/80%)
Is formed as an underlayer sprayed layer using an alloy containing aluminum (Al), yttrium (Y), titanium (Ti), or the like in the alloy or its alloy.

The second layer is formed by adding yttria (yttrium oxide) or magnesium (M
g) Alternatively, the first layer is coated as a zirconia-based thermal spray coating to which yttria, ceria (cerium oxide) or the like is added.

The intermediate layer is made of a material used for the first layer and the second layer.
The material used for the layer is mixed in an appropriate ratio to form a buffer layer. The mixing ratio of the material used for the first layer and the material used for the second layer may be appropriately changed as needed.

Further, the intermediate layer is provided as needed, and if not required, it can be implemented without being provided.

FIG. 2 shows a state in which the nozzle 1 formed as described above is installed in the high-temperature hot air introduction pipe 100. As shown in FIG. 2, a high-temperature hot air introduction pipe 100 generally called a blowpipe is provided on a furnace wall 101 of an iron making apparatus made of a refractory, and sends high-temperature hot air into a furnace body 102. Reference numeral 103 denotes a high-temperature hot air introduction pipe receiving installation portion of the furnace wall 101. The tuyere 104 of the high-temperature hot air introduction pipe 100 projects from the high-temperature hot air introduction pipe receiving installation portion 103 into the furnace body 102. High-temperature air sent from the high-temperature hot air introduction pipe 100 (usually about 1000 to 1230 ° C)
Is sent from the tuyere 104 into the furnace body 102.

The high-temperature hot air introduction pipe 100 has a nozzle accommodating section 105 for accommodating the pulverized coal blowing nozzle 1 near the tuyere 104. This nozzle housing section 105
Is a hollow portion communicating from the outside to the inside of the high-temperature hot air introduction pipe 100, into which the nozzle 1 is inserted. The nozzle accommodating section 105 is configured such that the tip of the inserted nozzle 1 is
04 is formed.

Behind the nozzle accommodating portion 105, a hollow nozzle rear accommodating tube 106 which projects to the outside of the high-temperature hot air introducing tube 100 and accommodates the rear portion of the nozzle 1 is formed. A flange 107 is formed at the rear end of the nozzle rear housing pipe 106, and a front flange 109 of the check valve installation pipe 108 is provided.
And by bolting or the like. The flange 107 of the nozzle rear housing pipe 106 and the check valve installation pipe 1
The front flange 11 of the nozzle 1 is sandwiched between the front flange 109 of the nozzle 08 and the nozzle 1 in the nozzle housing 105, the nozzle rear housing 106, and the check valve installation tube 108 by the above bolting. Is fixed. The check valve installation pipe 108 is for installing the check valve 111, is hollow like the nozzle rear housing pipe 106, and houses the rear part of the nozzle 1 inside. A rear flange 110 is formed at the rear of the check valve installation pipe 108. The rear flange 110 is joined to the fastening member holding flange 112 by bolting or the like. The fastening member holding flange 112 is for fixing the fastening member 113. The tightening member 113 has a handle 114, and maintains (adjusts) the airtightness inside the check valve installation pipe 108 by rotating the handle 114.

The inventors conducted a test on the effect obtained by forming the thermal spray coating 2. About this test,
A brief description including the evaluation will be given below. First, a thermal spray coating was formed on the tip of the conventional SUS nozzle shown in FIG. 3 by using several types of thermal spraying methods in order to obtain heat resistance and abrasion resistance. First, in a state where this nozzle was actually used, a follow-up survey was conducted on heat resistance, acid resistance, and abrasion resistance without sending compressed air for cooling. In this case, the thermal spray coating is formed on the outer peripheral surface of the tip of the pulverized coal discharging nozzle b of the nozzle of the type shown in FIG. A thermal spray coating is formed on a portion of the tip portion that slightly enters the inside of the nozzle (the inner circumference of the nozzle b) (in this test, the thermal spray was not applied to the air supply nozzle c serving as the outer tube).

After one month, the sprayed coatings subjected to various thermal spraying processes
After 3 months and 6 months, the follow-up was performed, and there was no abnormality in the film and no abrasion. Therefore, even without cooling with compressed air, it was found that the thermal spray coating sufficiently protected the tip portion of the nozzle formed of the SUS base material and exhibited heat resistance, oxidation resistance, and abrasion resistance. .

Further, even in the case of the nozzle shown in FIG. 1 which does not have the structure for sending compressed air, the sprayed coating on the tip of the nozzle was investigated in a state where the nozzle was actually used.
The sprayed coatings subjected to various thermal spraying were traced after one month, three months, and six months, respectively, in the same manner as the above-described conventional nozzles. However, the coatings were free from swelling, cracking, peeling, and abrasion. The thermal spray coating sufficiently protected the tip of the nozzle formed of the SUS base material.

On the other hand, in the laboratory, an electric furnace (muffle furnace) was used at 1000 ° C., 1200 ° C., and 1300 ° C.
C, and subjected to a heat shock test for evaluating the heat resistance of the SUS base material and the sprayed coating and the adhesion between the sprayed coating and the base material.

In this thermal shock test, each temperature condition (10
(00 ° C, 1200 ° C, 1300 ° C), the operation of heating the thermal sprayed test piece and immediately inserting it into water was repeated 30 times. However, there was no separation between the thermal sprayed coating and the base material of the nozzle tip, and the crack was not generated. No swelling occurred.

A nozzle having no structure for supplying compressed air shown in FIG. 1, that is, a nozzle for discharging pulverized coal only and having no air supply nozzle (a single pipe lance shown in FIG. 1) is different from a conventional nozzle. The result of comparison of the workability with the double pipe lance shown in FIG. 3 will be briefly described. The weight of the nozzle (single pipe lance) shown in FIG. 1 is almost 40% lighter than that of the nozzle (double pipe lance) shown in FIG. is there. Also, the life of the nozzle shown in FIG. 1 is about 10 months, which is about 2 months longer than the nozzle shown in FIG. 3 about 8 months. Also, the nozzle shown in FIG. 1 costs about 70% of the nozzle shown in FIG.

[0023]

In the first invention of the present application, the multiplexing of the sprayed layer with an appropriate sprayed material is carried out without changing the material of the PCI lance itself from the conventional one, thereby achieving the conventional one. In comparison, it has become possible to provide a PCI lance which is extremely excellent in heat resistance, oxidation resistance and abrasion resistance. As a result, there is no need for a configuration for supplying compressed air, and by omitting such a compressed air supply means, it is possible to reduce the cost and achieve a much smaller P
A CI lance could be provided. Such a reduction in size makes it possible to significantly reduce the weight of the PC, such as when the blast furnace is shut off, when a trouble such as lance clogging occurs, or when the lance is replaced.
When the work of pulling out and inserting the I lance is required, the weight is large as in the conventional double pipe lance, and moreover, the weight is further added by connecting a hose for supplying compressed air. The work became extremely comfortable. The comfort and labor saving of this work have been improved not only because of the above-mentioned weight reduction, but also because there is no work of removing and connecting a hose for supplying compressed air. In particular, a significant improvement in heat loss has been realized by eliminating the need for cooling using compressed air. Still further, the PCI lance does not require a configuration for supplying compressed air, and is implemented without the mantle tube.
It is possible to observe the part (nozzle) for supplying pulverized coal,
It is also effective in improving efficiency during inspections. In the second invention of the present application, the pulverized coal injection nozzle according to the first invention can be provided, and the supply can be realized at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a use state of the embodiment.

FIG. 3 is a schematic vertical sectional view showing a conventional example.

FIG. 4 is an explanatory diagram showing a use state of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle 2 Thermal spray coating 100 High-temperature hot air introduction pipe

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Mizoguchi 2-9-1 A-205, Shinsenri-minami-cho, Toyonaka-shi (56) References JP-A-59-136473 (JP, A) (JP, U)

Claims (2)

(57) [Claims] 1. A pulverized coal injection nozzle, which is disposed in a high-temperature hot air introduction pipe (100) for generating a combustion flame in a furnace of a steel making apparatus and supplies pulverized coal into the high-temperature hot air, into a pulverized coal blowing nozzle into the furnace. At least the tip (10) of the cylindrical nozzle (1) is provided with a thermal spray coating (2) for heat insulation and oxidation prevention, and the thermal spray coating (2) is used for spraying a base on the nozzle (1) surface. A first layer formed by spraying, a second layer formed thereon by spraying, and an intermediate layer formed by spraying between the first layer and the second layer as necessary. The first layer is formed as a base sprayed layer by a composition of a nickel-chromium alloy or an alloy containing at least one of aluminum, yttrium, and titanium in the alloy, and the second layer is Zirconia composite, yttria, magnesium, The first layer is coated as a zirconia-based thermal spray coating containing at least one of tritium and ceria, and the intermediate layer is formed by appropriately using the material used for the first layer and the material used for the second layer. A nozzle for blowing pulverized coal into a furnace of an iron making apparatus, wherein the nozzle is mixed as a mixture and formed as a buffer layer. 2. A pulverized coal blowing nozzle, which is provided in a high-temperature hot air introduction pipe (100) for generating a combustion flame in a furnace of an iron making apparatus and supplies pulverized coal into high-temperature hot air, is compared with a cylindrical nozzle (1). ), Wherein at least the tip portion (10) is sprayed to form a sprayed coating (2) for heat insulation and oxidation prevention. In the above, the thermal spray coating (2) is formed by spraying a first layer by spraying a base on the surface of the nozzle (1), a second layer by spraying the first layer, and a first layer and a second layer as necessary. The intermediate layer is formed by thermal spraying between the first layer and the first layer, the composition of the nickel-chromium alloy or its alloy, aluminum, yttrium, an alloy containing at least one of titanium Formed as a base sprayed layer, the second layer The zirconia composite is coated with a first layer as a zirconia-based thermal spray coating containing at least one of yttria, magnesium, yttria, and ceria. A method for producing a pulverized coal injection nozzle into a furnace of an iron making apparatus, comprising mixing a material used for two layers in an appropriate ratio and forming a buffer layer.