EP2882874A1

EP2882874A1 - Hot-blast lance

Info

Publication number: EP2882874A1
Application number: EP13737131.6A
Authority: EP
Inventors: Christian GÜNTHER; Michael Wahl
Original assignee: Saarstahl AG
Current assignee: Primetals Technologies Austria GmbH
Priority date: 2012-08-08
Filing date: 2013-06-20
Publication date: 2015-06-17
Anticipated expiration: 2033-06-20
Also published as: EP2882874B1; DE102012016143A1; WO2014023372A1

Abstract

The invention relates to a hot-blast lance for use in metallurgical processes, such as for example steel production, with which hot air can be blown in above a molten bath of a steel converter, which consists of an outer shell and at least one inner shell, and at least one intermediate space or cooling channel through which coolant flows is arranged between the outer shell and an inner shell. In order to achieve the effect here that a hot-blast lance can be further developed to the extent that hot air can be introduced into a reaction vessel, for example a steel converter, particularly effectively, that is to say with least possible thermal losses, and the lance is adapted better to this operating environment, it is proposed according to the invention that the inner shell (2) or the innermost shell (4) at least partially consists of a thermally insulating further shell (4), or a thermally insulating shell, or is provided with such a shell, or is coated with a thermally insulating layer.

Description

Hot blast lance

The invention relates to a hot blast lance for use in metallurgical processes, such as

Steel making, with which hot air is blown above a molten bath of a steel converter, which consists of an outer shell, and at least one inner shell, and between the outer and an inner shell at least one with coolant

is arranged through the intermediate space or cooling channel, according to the preamble of claim 1.

Steelmaking in reaction vessels, such as converters, uses both pig iron and scrap as a feedstock. In addition, however, also in the so-called direct reduction process produced sponge iron in the form of DRI (Direct Reduced Iron) or

HBI (Hot Briquetted Iron) can be used. An example of this is known from EP 1 920 075 B1.

Another method is known from DE 43 43 957 AI, in which in the operating phase of the converter fuels, oxygen-containing gases and

Iron raw materials, also scrap are introduced, and the reaction gases above the melt in the gas space of the

Converter with oxidizing gases are burned. The resulting heat is transferred to the melt transfer. In addition, oxygen and / or fuels are supplied via bottom nozzles.

So far, the combination of the bottom-side insufflation with oxygen and the inflating hot blast on the melt is known as such.

Hot air is understood as meaning an oxygen-containing gas heated to 1,200 ° C. (500-1,400 ° C.). The gas is typically composed of the main components oxygen, nitrogen and argon. Of the

Oxygen content is in the range of normal air (21%) and may be up to 35% or even 50% enriched with oxygen. In principle, a syngas could also be understood as hot blast, for example, from the exhaust gases of a combustion reaction of a fuel, such as, for example, blast furnace gas, coke gas,

Converter gas or natural gas or other gaseous or liquid hydrocarbon is obtained with air. The 02 content of the synthesis gas can be determined by the air ratio of the combustion and a possibly. Simultaneous enrichment of the combustion air with oxygen and / or the mixing of the combustion exhaust gases with pure

Set oxygen.

In contrast to normal hot blast, the hot blast produced in this case has contents of CO 2 and water as products of the combustion. The invention is therefore the object of a

Further development of the hot wind lance, that hot wind is particularly effective, ie with as little as possible

Temperature losses in a reaction vessel, for example, a steel converter can be introduced, and the lance better adapted to this environment of use.

The object is achieved in a hot blast lance of the generic type by the characterizing feature of claim 1.

Further advantageous embodiments are in the

dependent claims 1 to 13 indicated. A corresponding use of such a lance is specified in claim 14.

The core of the invention is that the inner jacket or the innermost jacket at least partially consists of a thermally insulating additional jacket, or a thermally insulating jacket, or is coated with a thermally insulating layer. This makes the hot blast lance considerably more robust and can be used in processes in which the reaction processes, for example, in the steelmaking process in the converter, are significantly influenced and optimized by the application of hot blast. As a result of the resulting afterburning and the transfer of the heat released in this way to the molten bath, the usable scrap rate becomes significantly higher.

The Heißluftnachverbrennung requires a special device for forwarding the hot blast from the hot blast source and for introducing the hot blast in the reaction vessel, via a corresponding, here

Hot blast lance configured according to the invention.

As a reaction vessel, a converter can be used, as it is known from steel production.

Basically, an afterburning can be done with Hot wind also operate in any other usual in metallurgy reaction vessel, it is irrelevant whether the walls of the vessel are completely, partially or not cooled with cooling water.

In the interior of a metallurgical reaction vessel, temperatures of more than 1 typically prevail. 000 ° C before, wherein in the gas phase, temperatures of up to 2. 000 ° C can be achieved. For permanent operation of an injection lance in the area of a

Reaction vessel, eg. For metallurgical reactions, above the liquid bath surface, it is essential to cool the injection lance, in this case so the hot blast lance intensively with water. The water cooling protects the hot wind lance from the upper space of the

Reaction vessel prevailing high gas temperatures. The high gas temperatures go to a considerable extent on the running in the reaction vessel (eg in a steel converter) and possibly. the injection lance usually maintain exothermic reactions. As such are

water-cooled lances known per se.

In a lance in pipe-web-tube construction, the water-cooled jacket of juxtaposed,

Cooling water leading tubes constructed, which are interconnected with narrow, solid webs. In general, two adjacent tubes are connected at one end to a manifold, the other two ends each with a flow and a

Return collectors are connected. As a special case of this embodiment is a pipe-on-pipe construction

introduced, in which the pipes without web directly

be welded together. In one embodiment of the lance in pipe-in-pipe design, three pipes are becoming ever smaller

Diameter concentric with each other. This creates between the outer and the middle tube, as well as between the middle and the inner tube each have a concentric space. If one connects the outer and the inner pipe at one end of the lance and shortens the middle pipe, the result is a geometry in which the two interspaces can be used as supply and return for the lance cooling water. In order to ensure a concentric positioning of the three tubes running into each other even with a large lance length, spacers are introduced between the tubes. Often these spacers are designed as welded in the longitudinal direction on the respective thinner pipe narrow webs.

Essential interpretive feature of an efficient

Water cooling is the highest possible heat transfer from the hot ambient atmosphere in the reaction vessel into the cooling water. Only so is a consistent

sufficiently low temperature level at the

Material surface of the water-cooled component ensured. To ensure these properties, water cooling systems are designed so that they flow through the cooling water at a flow rate of 2 m / s (1 to 3 m / s).

In the present technical task of continuing and introducing hot blast into a reaction vessel, the described water-cooled device is used with regard to protection of heat entry.

A special feature lies in the fact that hot wind is not a cold but a typical one 1200 ° C hot medium is. Furthermore, the hot-blast process is not always a continuous process, but is one in particular in the converter process

Batch process. Accordingly, this will be

provided system parts always phased with hot blast, whereby the system parts in the

Cool process breaks regularly. The result is an uneven load profile, which leads to a significant thermal cycling (TWB) of the applied equipment parts. This results in the

media-facing side of the hot blast lance a special requirement profile. This is with the present

Considered invention. The material surface of the innermost of the three tubes, through which hot air flows, is high thermal,

exposed to oxidative and abrasive stress. To protect the side facing the hot wind, this can be protected by a suitable coating against the aforementioned loads. In view of the considerable thermal load, it will generally be possible to work only with thin (<10 μm) layers, because thicker layers are due to the fact that, in comparison to the

Base material different thermal expansion tend to embrittlement and spalling. Suitable layer systems are ceramic layers, overlay layers or application layers which can be applied using the customary application methods, chemical vapor deposition, thermal spraying, build-up welding or application of SolGel systems, the layers possibly being replaced by a thermal step (by Curing, diffusion, crosslinking, etc.) can be improved in their functionality.

It has been shown that by the water-cooled construction of the lance sufficiently long service life

Allow operation in high-temperature reaction vessels. Surprisingly, it has also been shown that by the water cooling also a considerable

Heat is discharged from the hot blast stream into the water-cooled wall of the hot blast lance. This effect is in particular reinforced by the fact that with regard to still structurally manageable external dimensions, the lance must be designed so that the hot wind inevitably flows through the lance at speeds of 100 to 300 m / s, preferably 150 m / s. With rising

Speed also increases the heat output from the hot blast stream in the hot blast stream facing wall of the innermost lance tube.

This is counteracted by the design according to the invention. The further advantageous embodiments therefore support the above statements in accordance with the invention.

In a further advantageous embodiment, it is stated that the inner shell or the innermost shell, at least on the inside with a protective layer or

Coating is provided.

At least on the inside of the inner shell, the lance advantageously still has a good resistance to abrasion and corrosion. This is important insofar as the flow rate of hot air because of the lower density of the hot air compared to air under normal conditions is significantly larger. The mechanical load of the inner shell of the lance due to the flow of hot air is thereby greater than is the case with an oxygen lance, in which the oxygen is conveyed substantially in a cold state and usually under high pressure through the lance.

Due to the thermally insulating effect of the material can be advantageous to implement that the outer jacket against the high ambient temperatures in

Converter operation is cooled. Nevertheless, it can be achieved that the hot air, by the inner

Sheath flows, if necessary cooled to a small extent. This has proven to be important in order to bring the hot air with the highest possible temperature in the converter can.

In this embodiment, it also proves to be advantageous that the cooling channel through which water flows is separated by two walls from the inner tube of the lance, through which the hot air flows. Due to the flowing hot air, the inner tube is mechanically, thermally and chemically stressed comparatively strong. This may cause cracks in the mantle of the jacket

Inner tube occur. By the described

Execution form with the intermediate coat is then

achieved advantageous that in case of damage to the inner tube by the flowing hot air not immediately coolant can reach the interior of the lance and is promoted from there with the flowing hot air into the converter. In the described embodiment, only hot air then passes into the region between the inner jacket and the intermediate jacket. Because the Hot air there can not continue to flow with the

comparatively large flow velocity, the intermediate coat is then no longer mechanically stressed. Furthermore, it is configured that the inner shell or the innermost shell consists of several layers, and that at least the innermost of these layers, namely layer of abrasions- and / or

corrosion-resistant material.

Furthermore, it is configured that the inner shell or the innermost shell consists of a ceramic material or is coated with the same.

Ceramic materials advantageously meet the requirements outlined above.

Therefore, it is advantageously provided that the abrasion and / or corrosion-resistant material or the ceramic material on the adhering to the inner or innermost shell side with a temperature-resistant

Adhesive or liner is provided.

In this case, the bonding agent or liner is so elastic that it is the difference of the expansion coefficient of the inner or innermost shell to the abrasion and / or corrosion resistant material or ceramic

Material compensates.

A particular specific embodiment is that the abrasion- and / or corrosion-resistant material or the ceramic material consists of a layer system in which the surface to which the hot wind flows consists of a dense ceramic material and the surface remote from the hot wind consists of a ceramic foam material. The ceramic foam material has a higher elasticity than the massively executed

Ceramic material.

It proves to be advantageous that the

Coating is comparatively thin. This makes it possible to keep the weight of the lance within limits. This proves to be advantageous because the lance in

current operation relative to the converter in the vertical direction must be moved. A small layer thickness also proves to be advantageous because of the thermal cycling of the hot air lance in the

Converter operation. This alternating stress is due to the fact that before the tapping of the converter, the lance

is driven out. This will be the promotion of

Hot air ended by the lance. The lance then cools until hot air is conveyed through the lance at the next converter operation. The lance is heated again accordingly.

A suitable material for a coating may for example consist of A1 ₂ 0 ₃ , Sic, SiSiC or a super-Alloy. This material can be applied for example by sputtering, electrochemical or electrolytic coating, flame spraying, paint comparable to a color or by applying a suspension in which the liquid evaporates and the solid particles surface the outer or inner

Cover surface of inner lance of the lance.

It has been found that this ceramic material has good thermal insulation properties (i.e., low thermal conductivity). The material is also sufficiently mechanically stable (in particular

against abrasion) and has a sufficient Shock resistance to the occurring temperature fluctuations.

It should be noted that the operation

is intermittent. That does not mean that

continuously hot air through the inner jacket

is encouraged. If the converter is emptied and prepared after emptying, for the next

Melting process, for example by removing slag from the converter, renewing or repairing the refractory lining of the steel converter. During this time, the hot wind source in the form of a pebble heater is re-fired to store heat for the production of hot air for the next

Melting process. During this time will be no

Conveying hot air through the lance so that the inner jacket of the lance cools. With the beginning of the next

Fusion process is in turn promoted hot air through the inner shell of the lance, so that the inner jacket is then exposed to correspondingly high temperatures.

For integrated coolant guide is indicated that between the inner shell and the outer shell, at least one intermediate jacket or gap

is arranged, and is flowed through with coolant.

But it may also be advantageous if the space between the outer jacket and the inner jacket is evacuated.

In a further advantageous embodiment, it is stated that a Temperierungskanal is disposed between the outer shell and the innermost shell, which in Blasbetrieb the hot blast is also flowed through with hot blast.

It may be possible for the inner jacket to be kept at a high temperature on its outside as well, due to the hot air flowing in the tempering channel. The hot air passing through the inner mantle

flows through, is introduced largely without cooling at a high temperature in the converter.

The hot air, which flows through the Temperierungskanal is cooled in this embodiment to some extent.

This hot air, which has flowed through the tempering channel, can be distributed via diffusely distributing outlet nozzles on the

Outlet side of the lance are placed in the space of the converter above the steel bath. In this case, it must be avoided by the design of the nozzles that this hot air, which has flowed through the tempering channel, is mixed with the hot air which has been conveyed through the inner shell. A mix of these two

Hot air then would result in a

Means lowering the hot air temperature for the process.

Alternatively to the introduction of the by the

Temperierungskanal streamed hot air into the gas space of the converter, it is also possible to design the Temperierungskanal so that the hot air in the

Temperierungskanal in a circuit from the upper end (inlet end of the hot air into the lance) to the lower end (lance head, exit end of the hot air from the lance into the converter) flows and from there in the

Temperierungskanal is returned, in the direction the upper end of the lance. From there, the hot air can then be led out of the lance and released to the environment. This is from the

Temperierungskanal outflowing hot air advantageously led out of the hall of the factory. In the converter then only the hot air is introduced, which was conveyed through the inner shell of the lance.

Especially in this embodiment of the lance, it is advantageously also possible, even before the actual melting process in the converter

Warm-up operation of the lines to realize, through which the hot air is to be promoted during the melting process. If the pebble heater is already heated, hot air is then conveyed from the pebble heater to the lance through the supply line of the hot air before the actual melting process. It is advantageous that the area can be shut off by a slide, in which the hot air is introduced through the inner shell of the lance in the converter in the melting process. In this Aufwärmbetrieb the hot air is then conveyed through the Temperierungskanal and then discharged. As a result, the lines are preheated by the advantageous in the melting process

Hot air is supplied to the converter. This advantageously prevents just at the beginning of the

Melting process, the temperature of the hot air is cooled, because the hot air in this phase initially emits heat back to the lines.

It is also advantageous if the innermost shell is floatingly mounted in the hot blast lance.

This proves to be advantageous because a heat exchange between the inner shell and the outer jacket or the intermediate jacket is avoided by mechanical fastening and contacting. Likewise, this achieves that the mechanical stresses within the lance are reduced. By the

intermittent operation, in which periods of the

Conversion operation hot air is conveyed through the lance and in stages of preparation of the next

Converter operation no hot air through the lance

is promoted, above all, the inner jacket of the lance is subject to strong temperature fluctuations. By cooling occur on the outer jacket only

comparatively low temperature fluctuations.

With regard to the mechanical stresses, it is therefore advantageous if the inner jacket is floatingly mounted in the lance. The length changes due to the temperature changes then only lead to a lower mechanical load of the lance, because of the

floating storage the change in length of the inner shell can be made largely independent of the change in length of the outer shell.

In order to allow the high thermal length expansions at said high temperatures without damage, it is further configured that at least the inner or the innermost shell along its longitudinal direction consists of several sections or sleeves, which at the

Touch points of the individual sections or sleeves are designed partially overlapping.

It proves to be advantageous if in

Flow direction of the hot air, the rear end of a section is widened to accommodate the end of the direction of flow of the hot air before it

Part serves. By this type of connection of the sections, the changes in length in the temperature fluctuations of the inner shell can be better absorbed.

An embodiment is particularly advantageous when the floating inner shell of the hot blast lance is provided with an insulating layer, such as rock wool, in relation to the water-cooled jacket area.

Reason is that the heat transfer through

Temperature radiation from the innermost shell in the water-cooled shell, especially in the temperature range above 800 ° C is particularly effectively hindered. Carry on a little further. Basically enough even a temperature radiation obstruction in the form of a thin layer as a kind of radiation shield so that the removal of energy from the hot wind into the cooling water is stronger prevented.

Furthermore, in an advantageous embodiment, it is provided that the innermost surface or coating surface, which is in direct contact with the hot blast, reduces flow resistance and / or adhesion

is structured or microstructured.

It is a use of a hot blast lance according to one of claims 1 to 13, for blowing hot blast above a steel bath and / or a scrap heap, and / or a heap in a steel converter provided.

The thermal insulation described above proves to be particularly advantageous in a process in which hot air is introduced into the converter during the melting process. In the widespread introduction of Pure oxygen in the melting of steel for refining does not depend on the temperature of the oxygen due to the process. In contrast, proves the

Application of one of the aforementioned embodiments of a lance but just in the introduction of hot air in the converter as advantageous.

Optionally, it can be at a lance after the

The above-described embodiments still be useful to provide the inner surface of the inner shell with a surface profile, so that the

To improve flow profile. This surface profile can be designed, for example, in the manner of a sharkskin. This surface profile can be replaced by a

appropriate processing of the surface can be produced or by an appropriate coating.

The invention is illustrated in an embodiment example and briefly described below

Figure 1 shows a hot blast source as a so-called Pebble Heater 30. The Pebble Heater is a special type of regenerator. Here, cold wind is passed through a previously heated with burner gas firing stocking of bulk material, and withdrawn as a heated hot blast.

The hot air outlet of the Pebble Heater 30 or

Regenerator does not lead into one here

shown hot blast line, which is connected to the Heiwindlanze or is connected in the inflating operating position with the hot blast line.

Since the converter operation is a batch operation, the hot blast only for the time of the batch operated To be available. Between the batches, the burner is then operated in the Pebble Heater, and this heats up the stocking of bulk material in this time again until hot wind is generated again by cold wind supply in the Pebble Heater for the next converter batch.

Figure 2 shows the hot blast lance 10 in the operating position in which it is retracted into a converter 20. In converter operation, the components listed above in the text are additionally added via the bottom nozzles and also oxygen is blown in on the bottom side. This presentation is the above already made statements again.

The process runs in the manner already described above.

FIG. 3 now shows that shown in FIG

Hot blast lance 10 in her invention

Layer structure.

The innermost tube is usually the

so-called actual blowgun dar. Figure 3 shows only one side of a short section a

Longitudinal section through the hot blast lance. The dashed line represents the central axis of the hot blast lance. The wall of the hot blast lance 10 is shown here for simplicity only on one side of the central axis. Nevertheless, the layer or sheath sequence becomes clear from outside to inside. The outer shell 1 forms here together with the inner shell 2 a composite with a gap 3. The intermediate space 3 is designed as a cooling jacket, which is flowed through by a coolant. This inner shell 2 can be coated with a thin layer 41, which serves as a transition layer to a another inner jacket 42 is used. This jacket 42 may already be a ceramic tube, or a ceramic coated tube. The innermost tube or the innermost jacket 45 may be provided as a floating tube, and at least on the innermost surface in turn be provided with a corrosion and / or abrasion resistant layer 46.

The given between the innermost floating jacket or tube 45 space 5 can also with rock wool, or other thermally good

be filled with insulating materials.

A structure like this follows several provisos at the same time, namely on the one hand a good

Thermal insulation from inside to outside, so that the hot air does not cool in the hot blast lance, and on the other hand, the coating system causes a good corrosion and abrasion resistance. In particular, the floating storage of the innermost

Pipe or shell 46 allows for different thermally induced length expansions of different materials used. This can also be done with the coatings

be considered by, as described above, adhesion-promoting layers or liners at least

sections can absorb compensating thermal stresses. reference numeral

1 outer jacket

2 inner coat

3 space

4 Further inner coat

5 gap

41, 43, 44, 46 Coatings 42 Coat

45 innermost coat, floating

Claims

Patentanspräche;

Hot blast lance for use in metallurgical processes, such as steel making, with which hot air is blown above a molten bath of a steel converter, which consists of an outer shell (1), and at least one inner shell (2), and between the outer and an inner At least one coolant-flowed intermediate space (3) or cooling channel is arranged,

characterized,

that the inner shell (2) or the innermost shell (4) at least partially made of a thermally

insulating further jacket (4), or a thermally insulating jacket is or is provided with such, or is coated with a thermally insulating layer.

Hot blast lance according to claim 1,

characterized,

that the inner shell (2) or the innermost shell (4) at least on the inside with a

Protective layer (41) or (46) is provided.

Hot blast lance according to claim 1 or 2,

characterized,

in that the inner jacket (2) or the innermost jacket (4) consists of several layers (41, 42, 43, 44, 45, 46) and that at least the innermost of these layers, namely layer (46) or layer (43) consists of an abrasion and / or corrosion resistant material. Hot blast lance according to one of claims 1 to 3, characterized

that the inner jacket (2) or the innermost jacket (4) consists of or is coated with a ceramic material.

Hot blast lance according to claim 3 or 4,

characterized,

that the abrasion and / or corrosion-resistant material or the ceramic material is provided on the adhering to the inner or innermost shell side with a temperature-resistant adhesive or liner.

Hot blast lance according to claim 5,

characterized,

that the primer or liner is so elastic that it compensates for the difference in the

Expansion coefficients of the inner or innermost shell for abrasions- and / or

corrosion-resistant material or ceramic material compensates.

Hot blast lance according to one of claims 1 to 6, characterized in that the abrasions- and / or corrosion-resistant material or the ceramic material consists of a layer system in which the facing of the hot blast surface of a dense ceramic material and the surface facing away from the hot blast one

Ceramic foam material exists.

Hot blast lance according to one of claims 1 to 7, characterized

that between the inner shell (2) and the outer Sheath (1) at least one intermediate sheath or intermediate space (3) is arranged, and is flowed through with coolant.

, Hot blast lance according to claim 1 to 7,

characterized,

that the space (3) between the outer shell (1) and the inner shell (2) to ensure a protection against heat transmission through

Temperature radiation with a

Temeuraturstrahlungshemmer filled opder one of a thin temperature radiation inhibition layer is provided.

0. hot blast lance according to claim 1 to 7,

characterized,

that between the outer jacket (1) and the innermost jacket (46) a Temperierungskanal is arranged, which in the blowing operation of

Hot wind can also be flowed through with hot air.

1. hot blast lance after one of

Claims 1 to 10,

characterized,

that the innermost shell (45) is floatingly mounted in the hot blast lance.

2. hot blast lance according to one of

Claims 1 to 11,

characterized,

that at least the inner jacket (42) or the innermost jacket (45) along its longitudinal direction consists of several sections or sleeves, which at the points of contact of the individual sections or sleeves are designed partially overlapping.

13. hot blast lance according to one of

Claims 1 to 12,

characterized,

in that the innermost surface (46) or coating surface, which is directly in fluid communication with the hot blast, is structured or microstructured in a manner reduced in flow resistance and / or adhesion.

14. Use of a hot blast lance according to one of claims 1 to 13, for blowing hot blast above a steel bath and / or a

Scrap heap, and / or a heap in a steel converter.