DE112013004592T5 - blowpipe structure - Google Patents

Abstract

Provided is a blowpipe structure for a blast furnace plant configured to suppress the adhesion of slag by a simple structure even when using pulverized coal having an unadjusted softening temperature. The blowpipe structure is attached to a nozzle (22) in a blast furnace main body (20) which produces iron ore pig iron. The blowpipe structure blows auxiliary fuel pulverized coal (3) together with hot air (2) and has a constituent which melts due to the hot air (2) and / or combustion heat from the pulverized coal (3) to the slag of pulverized coal (3). The blowpipe structure has an inner / outer double tube structure with an inner tube (30b) extending and opening from a manifold (41) feeding the hot air (2) to the vicinity of the nozzle (22), the inner tube (30b) being in an outer tube (30a) extending from the manifold (41) to the nozzle (22). A pulverized coal outlet (31a) for an injection lance (31), into which the coal dust (3) is introduced, opens into the interior of the inner pipe (30b).

Description

Technical area

The present invention relates to a blowpipe structure for use in a blast furnace plant, and more particularly to a blowpipe structure which can be advantageously used to blow coal dust obtained by pulverizing ballast coal as an auxiliary fuel together with hot air into a furnace.

State of the art

A blast furnace equipment is used to feed iron ore pig iron by introducing raw material such as iron ore, limestone, coal and the like into the interior of a blast furnace main body from its tip and blowing hot air and pulverized coal (PCI coal) as an auxiliary fuel through a nozzle, which is located towards the bottom on one side of the furnace to produce.

In a blast furnace plant of this kind, when a ballast coal, which generally has a low ash melting point of 1100 to 1300 ° C, such as subbituminous coal or lignite, is used as the pulverized coal during the pulverized coal injection process, the oxygen used to blow in the pulverized coal the furnace is used in the approximately 1,200 ° C hot air, with a portion of the coal dust a combustion reaction. The heat of combustion generated thereby causes low melting point ash ("slag") in the injection lance or nozzle to melt.

The molten slag is rapidly cooled by contact with the nozzle, which is constantly cooled to protect it from the temperature of the blast furnace. As a result, solid slag adheres to the nozzle, resulting in blockage problems in the flow path of the blowpipe.

To solve this problem, the softening point (temperature) of the slag in the pulverized coal is set to a melting point equal to or higher than the temperature in the blast furnace when the slag has a low softening point, so that the slag is prevented from contacting the slag Adhere nozzles such as in the prior art, which is disclosed in the patent document 1 listed below.

The following Patent Document 2 discloses a configuration in which a distributor ring is provided in a hollow portion of a nozzle. The distributor ring provides a two-layered tube structure which divides the front end of the nozzle into a main channel in a central region and a secondary channel in an edge region, wherein gas supplied from a rear end of the nozzle is split into streams passing through the nozzle Main channel and the secondary channel are directed so that a beam is generated in the oven.

Bibliography

patent literature

• Patent Document 1: Untested Japanese Patent Application Publication No. H 05-156330
• Patent Document 2: Untested Japanese Patent Application Publication No. H06-235009

Brief description of the invention

Technical problem

However, the following two problems are pointed out in the method according to the method of Patent Document 1 as described above.

The first problem is that it is difficult to mix coal dust and additives (homogeneously), with the result that slag formation on parts where the additive content in the mixture is less than a predetermined value can not be prevented.

The second problem is that a new calcium oxide (CAA) source such as limestone or serpentinite is required, resulting in excessive costs.

On the other hand, in the conventional structure disclosed in Patent Document 2, there is a region in which no two-layer pipe is formed from the outlet of a lance to the distributor ring, resulting in at least a part of the pulverized coal inevitably not entering the distributor ring enters, but flows into the side channel in the edge region.

In view of these circumstances, there is a need for a blowpipe structure for use with blast furnace facilities that enables the suppression of slag adhesion using a simple structure without having to adjust the softening point.

The present invention has been conceived to solve the above-described problems, and has an object to provide a blast furnace structure for a blast furnace plant which enables the suppression of slag adhesion by a simple structure even when pulverized coal having an un-set softening point is used.

the solution of the problem

To solve the above-described problem, the present invention employs the following means.

A blowpipe structure according to one aspect of the present invention is a blowpipe structure attached to a nozzle for a blast furnace main body that produces iron ore pig iron, the blowpipe structure containing pulverized coal as an auxiliary fuel together with hot air and slag from the pulverized coal containing an ingredient blown by the hot air and / or heat from the combustion of the pulverized coal, the structure being an inner / outer double pipe structure in which an inner pipe extending from a hot air supply manifold into the vicinity of a nozzle and opens, is provided inside an outer tube extending from the manifold to the nozzle, and opens a pulverized coal outlet of an injection lance for introducing pulverized coal into the interior of the inner tube.

According to this blow pipe structure, there is provided an inner / outer double pipe structure in which an inner pipe extending and opening from a hot air supply manifold into the vicinity of a nozzle is provided in an outer pipe extending from the manifold to the nozzle. and opening a pulverized coal outlet of an injection lance for introducing pulverized coal into the interior of the inner pipe, so that the pulverized coal stream introduced by the blowing lance is completely separated from the wall of the outer pipe, i. H. the inner wall of the blowing tube, is separated on the upstream side of the nozzle. In addition, the pulverized coal may be passed through the nozzle at a distance from the surface of the nozzle. This inhibits the adhesion of pulverized coal slag to the surface of the nozzle or to the inner wall of the blowpipe.

In the invention described above, preferably, a flow path resistance element is provided at a position in the flow path formed between the outer tube and the inner tube and near the outlet of the inner tube.

Thereby, a larger flow rate is provided in the inner tube than in the outer tube. As a result, hot air flowing out of the outer tube flows toward the center of the flow path, so that the coal dust flow flowing into the inner tube toward the outer tube is inhibited.

In the invention described above, a nitrogen sparger tube is preferably provided for feeding nitrogen into the inner tube.

This enables the operating conditions of the inner tube and the outer tube to be changed. In this case, nitrogen may be blown into the inner tube to reduce the temperature of the hot air. As a result, the temperature of the hot air in the inner pipe can be adjusted so as to provide an environment in which the pulverized coal can not burn easily.

In the invention described above, an oxygen injection tube is preferably provided for supplying oxygen into the outer tube.

This enables the operating conditions of the inner tube and the outer tube to be changed. In this case, in spite of the environment which is not conducive to the combustion of the pulverized coal in the inner tube, oxygen may be blown into the outer tube to allow rapid combustion when the gases from the inner and outer tubes are mixed immediately before the nozzle ,

Advantageous Effects of the Invention

According to the above-described blowpipe structure of the present invention, there is provided an inner / outer double pipe structure in which an inner pipe is provided in an outer pipe extending from a hot air supply manifold to a nozzle, and a pulverized coal outlet of an injection lance for introducing pulverized coal opens into the interior of the inner tube, so that the adhesion of pulverized coal to the surface of the nozzle or the inner wall of the blowpipe is inhibited. This allows suppression of slag adhesion in the blowpipe structure by means of a simple double-tube structure, even if no softening point adjustment takes place.

As a result, even ballast carbons with low ash melting points of 1100 ° C to 1300 ° C, such as subbituminous coal or lignite, can be used as the pulverized coal forming the auxiliary fuel by being modified for use as feed carbon.

Brief description of the drawings

1 Fig. 12 is a longitudinal cross-sectional view of the axial direction of one embodiment of the blowpipe structure according to the present invention.

2 is a pictorial representation of an exemplary design for a blast furnace system, at the blowpipe structure of 1 is appropriate.

Description of embodiments

An embodiment of the blowpipe structure according to the present invention will now be described with reference to the drawings.

The blowpipe structure according to the embodiment is used with a blast furnace plant in which pulverized coal of the ballast coal constituting the raw material coal is injected together with hot air through a nozzle into a blast furnace.

For example, in a blast furnace plant like the one in 2 represented the starting material 1 made of iron ore, limestone and coal or the like, from a feeder 10 for measured starting material via a transport conveyor 11 in a funnel 21 at the stove top 21 led at the top of a blast furnace main body 20 is provided. Several nozzles 22 are in a lower sidewall of the blast furnace main body 20 provided in an approximately uniform distance in the circumferential direction. Each of the nozzles 22 is with a downstream end of a blowpipe 30 for supplying hot air 2 into the interior the blast furnace main body 20 connected. The upstream end of each of the blowpipes 30 is with a hot air feeder 40 connected, which forms the source of the hot air, the interior of the blast furnace main body 20 is supplied.

A coal dust making device 50 that performs pretreatment (modification) such as vaporization of moisture in the coal of the raw material coal (subbituminous coal, lignite or other ballast coal), followed by pulverization of the ballast coal to produce pulverized coal, is near the blast furnace main body 20 provided.

Modified coal dust (modified coal) 3 coming from the coal dust manufacturing device 50 is produced by a carrier gas 4 , such as nitrogen gas, to a cyclone separator 60 promoted. The coal dust 3 which is carried by the gas is passed through the cyclone separator 60 from the carrier gas 4 separated, after which the coal into a storage container 70 falls and is stored there. This modified coal dust 3 is used as coal for blast furnace blowing (PCI coal) for the blast furnace main body 20 used.

The coal dust 3 in the storage container 70 gets into an injection lance (hereafter "lance") 31 fed to the blow pipe described above. The coal dust 3 burns after feeding into the hot air passing through the blowpipe 30 flows, leaving a flame at the end of the blowpipe 30 generated and a career is formed. This causes the coal or the like that in the starting material 1 contained, for combustion in the blast furnace main body 20 is introduced. As a result, this will be in the starting material 1 reduced iron ore, to pig iron (molten iron) 5 converted and through a pig iron outlet 23 away.

Preferred properties of coal dust 3 , the blast furnace blown coal from the lance 31 in the blowpipe 30 Thus, the modified pulverized coal (auxiliary fuel) formed by modifying and pulverizing ballast coal is an oxygen atom content (dry basis) of 10 to 18 wt% and an average pore size of 10 to 50 nanometers (nm). A more preferred average pore size for the modified pulverized coal is 20 to 50 nanometers (nm).

In coal dust 3 With such properties, many tar-forming groups of oxygen-containing functional groups (carboxyl groups, aldehyde groups, ester groups, hydroxyl groups, etc.) are released and reduced, but splitting (reduction) of the main skeleton (the combustible ingredient mainly composed of carbon, hydrogen and oxygen ) strongly suppressed. So if the coal together with hot air 2 through the nozzles 22 into the blast furnace main body 20 is injected, allow the high oxygen atom content of the main skeleton and the large diameter of the pores not only a dispersion of the oxygen in the hot air 2 in the coal, but also significantly inhibit the production of tar, so that a complete combustion takes place almost without unburned coal (soot).

For the production (modification) of this coal dust 3 is a drying step of heating (at 110 to 200 ° C, 0.5 to 1 hour long) and drying the subbituminous coal, lignite or other ballast coal (dry basis oxygen atom content: greater than 18 wt .-%; average pore size: 3 to 4 nm), which is the raw material coal, in an oxygen-poor atmosphere having an oxygen concentration of 5% by volume or less in the pulverized coal producing apparatus 50 executed.

After removing moisture in the drying step described above, a dry distillation step is carried out in which the starting carbon (at 460 to 590 ° C, preferably 500 to 550 °, 0.5 to 1 hour long) in an oxygen-poor ambient atmosphere (oxygen concentration: 2 vol. % or less) is reheated. By the dry distillation of the raw material coal in this dry distillation step is generated Water, carbon dioxide and tar removed in the form of dry distillation gas or dry distillation oil.

The raw material coal is then subjected to a cooling step in which the coal is cooled (to 50 ° C or less) in an oxygen-lean atmosphere having an oxygen concentration of 2% by volume or less, and then pulverized in a pulverization step (particle diameter: 77 μm or less (80% passage)).

In the embodiment, such as in 1 was shown, the structure described below for a blowpipe 30 used that at a nozzle 22 a blast furnace main body 20 is attached to the production of pig iron and coal dust 3 as an auxiliary fuel together with hot air 2 and slag from the coal dust 3 that contains a component that is caused by the hot air 2 and / or the heat from the combustion of the pulverized coal 3 is melted, blown.

More precisely, the blowpipe 30 , which is shown in the drawing, an inner / outer double tube structure. This inner / outer double tube structure extends from a manifold 41 that with a hot air supply 40 connected and the nozzle 22 hot air 2 feeds, to the nozzle 22 and has an inner tube 30b on that in an outer tube 30a is provided.

Specifically, the outer tube branches 30a of the blowpipe 30 from the manifold 41 off and is with the nozzle 22 connected. In contrast, the inner tube branches 30b of the blowpipe 30 from the manifold 41 off, like the outer tube 30a , and further includes a downstream inner tube outlet 30c on, located near an inlet of the nozzle 22 opens.

The blowpipe 30 thus has an inner / outer double tube structure in which the inner tube 30b that is different from the hot air 2 feeding manifold 41 close to the nozzle 22 extends where there is a Innenrohrauslass 30c opens, in the outer tube 30a is provided, extending from the manifold 41 to the nozzle 22 extends.

In other words, the blowpipe points 30 an inner / outer double tube structure in which an inner tube 30b for the introduction of coal dust 3 concentric in the outer tube 30a , which is the main body of the blowpipe is provided so that the flow paths are separated.

The outer tube 30a and the inner tube 30b of the blowpipe 30 preferably have a cross-sectional area ratio of about 1: 1. To give a specific example: For example, if the inner diameter of the nozzle 22 160 mm, the inner diameter of the outer tube is 30a 210 mm and the inner diameter of the inner tube 30b is 140 mm.

In addition, the lance runs 31 for introducing the pulverized coal 3 in the blowpipe 30 through the outer tube 30a and the inner tube 30b and has a pulverized coal outlet 31a on, extending to the interior of the inner tube 30b opens.

In a blowpipe 30 with an inner / outer double tube structure of this type becomes coal dust 3 through the lance 31 in the interior of the inner tube 30b introduced, so that the flow of coal dust 3 completely from the surface of the wall of the outer tube 30a on the upstream side of the nozzle 22 can be separated. That is, the stream of coal dust 3 is from the surface of the inner wall of the blowpipe 30 completely separated and the stream of coal dust 3 can at the nozzle 22 at a distance from the surface of the nozzle 22 be passed through.

Consequently, the amount of coal dust 3 passing over the surface of the nozzle 22 and the surface of the inner wall of the outer tube 30a which forms the main body of the blowpipe (ie, the surface of the inner wall of the blowpipe 30 ) compared to a conventional structure that does not have an inner tube 30b has, either eliminated or greatly reduced, so that a significant suppression of slag adhesion of coal dust 3 is possible.

In the blowpipe structure according to the above-described embodiment, a flow path resistance element is preferable 80 provided to the cross-sectional area of the flow path in an outer circumferential flow path 30d reduce, between the outer tube 30a and the inner tube 30b and at a position near the outlet of the inner tube 30b is trained. This flow path resistance element 80 allows a larger flow rate in the inner tube 30b in which the flow path resistance is low, as in the outer tube.

Consequently, hot air flows 2 coming from the outer tube 30a flows, in the direction of the axial center of the inner tube 30b , ie in the direction of the center of the flow path of the blower tube 30 so that the flow of coal dust 3 in the inner tube 30b is introduced, in the direction of the outer tube 30 , in which the slag adhesion is to be prevented, is inhibited.

The flow path resistance element described above 80 is an element of the Surface of the inner wall of the outer tube 30a or the outer wall of the inner tube 30b or alternatively from the surfaces of both the inner wall of the outer tube 30a as well as the outer wall of the inner tube 30b protrudes, so that the cross-sectional area of the flow path is reduced. The cross-sectional shape is not particularly limited. However, when a wedge-shaped protruding member such as a flow path resistance element 80 that has a beveled surface 81 which reduces the cross-sectional area of the flow path from the upstream side of the flow direction to the downstream side, on the inner wall surface of the outer tube 30a is provided, directs the beveled surface 81 hot air 2 passing through the outer circumferential flow path 30d flows, towards the center of the nozzle 22 and thereby diverts the flow of coal dust 3 towards the center of the nozzle 22 so that the slag adhesion of the coal dust 3 is further suppressed.

The blowpipe structure described above is preferably a nitrogen sparger 90 for feeding nitrogen into the interior of the inner tube 30b provided. This nitrogen blowing tube 90 is used to introduce nitrogen gas as needed into the through the inner tube 30b flowing hot air 2 used as a desired change in the operating conditions of the inner tube 30b and the outer tube 30a ,

Accordingly, the introduction of nitrogen into the inner tube reduces 30b the temperature of the hot air, so the temperature of the hot air 2 can be lowered to or below the slag melting point. In other words, the nitrogen sparger allows 90 in that the temperature of the hot air with the inner tube 30b can be adjusted and the oxygen concentration can be reduced by the injection of nitrogen, so as to allow an adaptation to an environment in which the coal dust 3 can not burn easily.

The blowpipe structure described above is preferably with an oxygen sparger tube 91 for supplying oxygen into the outer tube 30a that is, in the outer circumferential flow path 30d , provided. This oxygen blowing tube 91 is used to introduce oxygen as needed into through the outer tube 30a flowing hot air 2 used as a desired change in the operating conditions of the inner tube 30b and the outer tube 30a ,

Accordingly, hot air 2 , their oxygen concentration by blowing oxygen into the outer tube 30a was increased, with the coal dust 3 mixed in the inner tube 30b near the inlet of the nozzle 22 is introduced, allowing rapid combustion of the pulverized coal 3 is possible. Such acceleration of combustion increases the temperature of the hot air 2 so that the combustion of the coal dust 3 is further accelerated.

The method of adjusting the oxygen concentration of the hot air 2 will now be described specifically by way of example.

The from the manifold 41 supplied hot air 2 For example, it is set to an oxygen concentration of 21% by volume. To a combustion after convergence with the coal dust 3 ensure oxygen is released from the oxygen sparger tube 91 in the outer tube 30a blown in order to enrich the oxygen concentration to 25 to 50% by volume, preferably 30 to 35 vol .-%.

Consequently, the burning rate of the pulverized coal becomes 3 in the inner tube 30b reduced, wherein the oxygen concentration is relatively lower than in the outer tube 30a is such that a slag adhesion in the inner tube 30b can be suppressed. The hot air 2 and the coal dust 3 in the inner tube 30b flow, then converge with the oxygen-enriched hot air 2 coming from the outer tube 30a flows in, so that the combustion rate of the pulverized coal 3 due to the increase in oxygen concentration increases and complete combustion of the pulverized coal 3 permitting the coal blown into the raceway into the runway main body.

In addition to this adjustment of the oxygen concentration can simultaneously nitrogen in the inner tube 30b are introduced to the temperature of the hot air in the inner tube 30b depending on the shape of the coal dust 3 on or below the ash melting point.

Therefore, according to the blowpipe structure of the above-described embodiment, there is provided an inner / outer double pipe structure in which the inner pipe 30b in the outer tube 30a is provided, extending from the manifold 41 up to the nozzle 22 extends, and the coal dust outlet 31a the lance 31 for the introduction of coal dust 3 in the interior of the inner tube 30b opens, so the stream of coal dust 3 from the surface of the nozzle 22 and the inner wall of the blower tube 30 is separated and the adhesion of slag from the coal dust 3 is inhibited.

This enables suppression of slag adhesion in the blowpipe structure using a simple inner / outer double tube structure even if the softening point of the pulverized coal 3 not set. Consequently, the maintenance interval of the blowpipe 30 for example, on the life of the nozzle 22 be extended.

The component contained in the slag caused by the coal dust described above 3 made and by the hot air 2 or the heat is melted, resulting from the combustion of the pulverized coal 3 that is, the low melting point slag ingredient has an ash melting point of about 1100 to 1300 ° C when hot air 2 of about 1200 ° C is used. A low melting point slag ingredient of this type is also contained in modified coal obtained by modifying ballast coal, such as sub-bituminous coal or lignite, as the starting coal for coal dust 3 is prepared by drying, dry distillation or the like, however, by using the blowpipe structure of the embodiment, pulverized coal 3 prepared by modifying a raw material ballast coal, used as an auxiliary fuel.

The present invention is not limited to the above-described embodiment, and various modifications may be made within the scope of the invention as occasion demands.

LIST OF REFERENCE NUMBERS

1

starting material

2

hot air

3

Coal dust (modified coal)

4

carrier gas

5

Pig iron (molten iron)

10

Feeder for measured starting material

20

Blast furnace main body

21

Funnel at stove tip

22

jet

30

blowpipe

30a

outer tube

30b

inner tube

30c

Innenrohrauslass

30d

Outer circumferential flow path

31

Injection lance

31a

Coal dust outlet

40

Heißluftzuführeinrichtung

41

manifold

50

Pulverized coal producing device

60

cyclone

70

storage containers

80

Flow resistance element

81

Beveled surface

90

nitrogen sparger

91

Sauerstoffeinblasrohr

Claims (4)

A blowpipe structure attached to a nozzle for a blast furnace main body that produces iron ore pig iron, the blowpipe structure containing pulverized coal as an auxiliary fuel together with hot air and slag from the pulverized coal containing a component caused by the hot air and / or heat the combustion of pulverized coal combustion heat is melted, blown; the structure being an inner / outer double tube structure in which an inner tube extending from a hot air supply manifold into the vicinity of a nozzle and opening is provided in an outer tube extending from the manifold to the nozzle , And a pulverized coal outlet of a blowing lance for introducing the pulverized coal into the interior of the inner tube opens. The blower tube structure according to claim 1, wherein a flow path resistance element is provided at a position in a flow path formed between the outer tube and the inner tube and near the outlet of the inner tube. A blower tube structure according to claim 1 or 2, wherein a nitrogen blowing tube is provided for feeding nitrogen into the inner tube. A blower tube structure according to any one of claims 1 to 3, wherein an oxygen blowing tube is provided for supplying oxygen into the outer tube.

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