EP1062370B1 - Blasting lance with a gas/liquid mixing chamber and a method for the expansion cooling thereof - Google Patents

Abstract

The invention relates to a method for cooling a lance provided for converting a medium into a molten mass and/or for measuring the properties of the molten mass. A gas/liquid mixture is fed as a cooling medium into a cooling circuit which is closed up to the lance end (2) situated on the melting side. The invention provides that the gas/liquid mixture or the components thereof is/are fed and permitted to expand under pressure up to the area of the lance end (2) situated on the melting side. The invention also relates to a lance which has a mixing chamber (5, 6) connected to the cooling circuit. The mixing chamber has the connections (3, 7) for a gas and liquid supply which is designed to produce the gas/liquid mixture, whereby the mixing chamber (5, 6) is connected via a pressure line (10) to at least one two-component nozzle (11) arranged in the area of the lance end (2) which is situated on the melting side.

Description

The invention relates to a method for cooling a Introducing a medium into a melt and / or for measuring lance provided by properties of the melt as well as a lance suitable for performing this method according to Preambles of claims 1 and 3.

Lances for blowing media (especially solids and / or gases) in the interior of metallurgical vessels such as Furnaces or converters and as a support for instruments for Measuring properties of the melt are known. you will be For example, to oxygenate a pig iron melt, for Blowing in media during steel treatment (e.g. coal for Foaming of the slag) and for measuring the temperature of the melt used.

The end region of such a lance facing the melt is subject to high thermal stress. Obviously Prior use, it is known to use tubular steel lances their melt-side end in operation continuously burns, the lance must be moved accordingly. Known are also cooled lances with closed water cooling circuits. The operation of these lances is dangerous because in the event of a leak in the cooling circuit, contact of the melt with Cooling water can lead to explosive reactions. Provided Water can be trapped by the melt then the water evaporates and expands Tear the melt apart explosively. Even the chemical one Decomposition of the water and a subsequent detonating gas reaction cannot be ruled out.

It has therefore already been proposed (DE 35 43 836 C2) to use two lances, which alternately in the operating position be driven. The one in the operating position The lance is cooled with a gas. Because a sufficient If the cooling effect is not achieved, the lance will certain operating time out of the oven and in this position far away from the melt with water recooled. During this time the second lance carries the Operation continues. Such an alternate operation with two Lances are expensive.

From WO-A-92/07965 a lance is known which one with a two-phase mixture-fed closed cooling circuit having.

The invention has for its object a method and to create a lance of the type mentioned in the introduction, the or that enable effective and safe lance cooling.

The method according to the invention is characterized in that that the gas / liquid mixture or its components under Pressure up to the area of the melt-side lance end is led and left to relax there.

The melt-side lance end denotes that end of the Lance that faces the melt during operation or, if applicable, in this dips. It is the thermally highly stressed Lance end. The cooling circuit is for the melt side Lance end closed. There is none in this area Coolant leakage takes place, the coolant is in instead returned to a region of the lance spaced from the melt and exits the lance there. The coolant circuit overall can either be completely closed but you can also use an open cooling circuit which is spaced from the melt-side end the heated cooling medium emerging from the lance is not reused becomes.

The gas content of the mixture used according to the invention is preferably air or an inert gas (for example nitrogen or argon), the liquid portion prefers water.

According to the invention, the gas / liquid mixture is under pressure to the area of the melt-side lance end. The term "region of the melt-side lance end" denotes one near the corresponding lance end lying area, which is already highly stressed during operation is. The conceptual pair of "leadership under pressure up to let area of this end and then relax " is to be understood that in the area mentioned sudden drop in pressure of the gas / liquid mixture takes place. The invention is therefore only implemented to a corresponding pressure difference, not to the absolute Heights of the respective pressures. Let it relax (preferably by leaving a corresponding one Nozzle into a room of lower pressure) causes the liquid phase of the mixture torn into fine droplets and / or is evaporated. Both effects significantly increase the cooling capacity, because on the one hand the evaporation considerable amounts of heat needed and on the other hand due to finely shredded droplets their large surface quickly and effectively (under evaporation) can dissipate further heat. The invention intended expansion of the coolant mixture in the area the melt-side lance end thus causes a clear Increase in cooling capacity compared to the prior art. On the other hand, it ensures a significant increase in security, because of the relaxation process in the area of this Lance end little or no liquid phase is present. At Malfunctions in this area melt through cannot include large amounts of water and so cause thermal explosions. Within the scope of the invention the two-phase mixture of gas and liquid can be spaced apart manufactured from the melt side lance end and as finished mixture under pressure fed to this end and there be relaxed. It is also possible to gas and Liquid separated under pressure up to the range of to lead the melt-side lance end and either to mix only shortly before the relaxation process or let it relax through separate jets, which are arranged so that the gas / liquid mixture during of the relaxation process arises in situ. One can For example, arrange separate nozzles so that liquid escapes sucked in by the relaxing gas and into one fine aerosol is torn.

The method according to the invention requires considerably for cooling smaller amounts of liquid than that known in the prior art Water cooling. You set the gas / liquid flow like this a that the liquid content in the area of the thermal particularly loaded melt-side lance end as a result of Relaxation largely or completely evaporated. this has two advantages. On the one hand, you don't just use it for cooling the heat capacity of the liquid (water), but also the much greater heat of vaporization for the phase transition Liquid vapor and maintains even at proportionate low liquid flows a high cooling capacity. Unless there are malfunctions in the area of the melt side Eventually there is a leak in the coolant line the large surface area of the aerosol Gas / liquid mixture that it is in any case a very rapid evaporation of the liquid content comes before even the melt can include liquid drops.

As a rule, the liquid portion of the invention used cooling medium water. If you choose operating conditions, where the water content in the area of the melt side Part of the lance is largely or completely evaporated the cooling circuit is preferably fed with deionized water, for limescale deposits in the corresponding area of the Avoid cold room. Demineralized water is not available Available and must the cooling circuit with ordinary pipe or raw water are fed, you put the Gas / liquid flow is preferably such that a lower one Share of water in the area of the melt-side lance end evaporates, the rest remains as a finely divided aerosol. Unwanted limescale will be largely avoided.

The high flow rate due to the relaxation process of the two-phase mixture does not tear evaporated water with, so that there is no stationary in the area of the lance tip Water can accumulate in the event of a melt collapse could lead to an explosion hazard.

The gas / liquid mixture can be produced outside the lance and are already supplied as a mixture to the lance. However, it is preferred in the context of the invention that the lance has a mixing chamber connected to the cooling circuit, has the connections for a gas and liquid supply and designed to produce a gas / liquid mixture is. The mixing chamber is spaced from the melt side Lance end arranged. It is preferably located in the part of the lance protruding from the furnace or converter.

The gas / liquid mixture is preferred by the mixing chamber with a pressure of 2 to 6 bar, more preferably about 3 bar, through a pressure line to the melt end of the lance led out. In the area of this end is a two-component nozzle arranged, from which the mixture into one in the area the cooling chamber arranged at the tip of the lance relaxes. The term "Two-component nozzle" means any within the scope of the invention Devices that allow passage of a liquid / gas mixture allowed and a pressure difference between the supply and can maintain exit side so that a nozzle effect, d. H. a division of the fed Mixture in the area behind the nozzle lower pressure. When it comes out of the nozzle the liquid portion of the mixture is torn into fine droplets. The relaxed and heated mixture is replaced by a second line led away from the melt-side lance end and occurs at a preferably arranged outside the converter Connection out of the lance again. The pressure of the mixture after exiting the two-component nozzle (s) preferably slightly above atmospheric pressure. Unless the lance used in diving operations, it should be larger than the back pressure of the liquid surrounding the lance tip Melt. If there is a problem due to malfunctions Melting of the lance tip and a breakthrough of melt into the cold room is prevented by the excess pressure inside the further penetration of melt or slag if necessary.

The mixing chamber advantageously has two concentric, the lance tube surrounding ring chambers in their radial partition connecting holes or openings are arranged. The term lance tube means that for the introduction of gas and / or solid into the melt provided inner tube of the entire lance assembly. The inner one The annular chamber can, for example, with water from its end face are applied, the outer annular chamber becomes circumferential pressurized with compressed air. Through the holes in the radial partition, compressed air is mixed into the water. The resulting mixture is on the melt side end removed and removed from the mixing chamber.

The pressure line for connecting the mixing chambers and the two-fluid nozzle the lance tube is preferably concentric surrounding ring line. The return of the relaxed mixture preferably takes place from the melt-side lance end also through a ring line, which as a the pressure line concentrically surrounding second ring line is formed can be.

A second embodiment of a lance according to the invention has separate pressure lines for the supply of gas on the one hand and liquid on the other hand towards the melt-side lance end on. These pressure lines can be concentric as the lance tube surrounding ring lines can be formed. In the area the pressure lines end at the melt-side lance end in nozzle arrangements, from which gas on the one hand and liquid on the other hand, exit and in situ, d. H. while of the relaxation process, into a finely divided aerosol mix. The suction effect of the relaxing gas pulls out leaking liquid and divides it into fine droplets. The flow rate of the in situ The aerosol produced is so high that it is not worth mentioning Amounts of water in the area of the melt-side lance end remain. There is therefore no or only a slight security risk in case of melt breakthrough. The Operating pressures of this lance can be well below 3 bar lie. The necessary pressure in the gas line (Compressed air line) is, for example, 1 to 2 bar, preferably about 1.5 bar. The liquid (water) only needs one slight excess pressure of less than 1 bar, preferably about 0.5 bar to be supplied because they are in the aerosol formation of the relaxing compressed air is entrained and divided.

A preferred field of application of the invention is treatment of or performing measurements on metallurgical Melting, e.g. pig iron or steel melting. The However, the invention is not for use in molten metals limited, but can be used for further melt flows high temperature (e.g. glass melting) can be used.

Fig. 1

einen Längsschnitt durch eine erfindungsgemäße Lanze;

Fig. 2

einen Querschnitt entlang der Ebene A-A der Fig. 1

Fig. 3

einen Längsschnitt durch eine zweite Ausführungsform einer erfindungsgemäßen Lanze;

Fig. 4

einen Querschnitt entlang der Ebene A-A der Fig. 3.

Embodiments of the invention are explained below with reference to the drawing. In it show:

Fig. 1

a longitudinal section through a lance according to the invention;

Fig. 2

2 shows a cross section along the plane AA of FIG. 1

Fig. 3

a longitudinal section through a second embodiment of a lance according to the invention;

Fig. 4

3 shows a cross section along the plane AA of FIG. 3.

The lance according to FIGS. 1 and 2 has a inner lance tube 1, through which solids and / or gases be fed to the melt. The exit of this media in the melt takes place at the lance end 2 on the melt side Lance tube 1 is from one described in more detail below Cooling device surrounded.

Through a connection piece 3 cooling water is the lance tube 1 surrounding annular chamber 4 supplied. The end faces the annular chamber 4 and the inner chamber 5 of the axially adjoining Mixing chamber are connected to each other so that this inner annular chamber 5 fed from the annular chamber 4 with water becomes. The inner annular chamber 5 is from an outer one Annular chamber 6 surrounded by a connector 7 with Compressed air is fed. Form the two annular chambers 5,6 together the mixing chamber. The radial partition 8 between the annular chambers 5 and 6 have connection holes indicated at 9 on. Compressed air and water mix together, the mixture is drawn axially into the interior Annular chamber 5 connecting ring line (pressure line) 10 to Lance end on the melt side. The pressure of the mixture in the pressure line 10 is approximately 3 bar.

The ring line 10 is in the region of the melt-side end 2 of the lance to six evenly over the lance circumference distributed two-component nozzles 11 formed. The water / air mixture relaxes when exiting the two-component nozzles into the annular cooling space 12. The water is through this relaxation process torn into very fine droplets. The high surface of the water supplied favors one rapid heat absorption and thus a high cooling capacity. The Forming the ring line 10 to six two-component nozzles 11 allowed the operation of the lance with tap or process water as part of the cooling medium. The clear width of the two-substance nozzles 11 enables the passage of, if necessary, in the process water contained impurities or particles. The lance should only be operated with deionized water can, the ring line 10 in the area of the cooling chamber the cooling chamber 12 to an annular gap with a clear Width of about 0.5 mm can be narrowed, making the lance tube 1 rotationally symmetrical surrounds. This annular gap forms a single one Dual-substance nozzle. The formation of several discrete two-component nozzles 11 is not required in this case.

The mixture emerging from the two-substance nozzles 11 hits on opposite (melt-side) end of the cooling chamber 12 on a curved cooling surface 13 through which it is in its Direction of movement deflected and the second ring line 14 trained coolant discharge line is supplied. The water content of the supplied mixture evaporates in the Cooling chamber 12 preferably completely. It comes with special Operating conditions at exceptionally high temperatures in the cooling chamber 12, the cooling effect may supported are caused by the strongly endothermic decay of part of the Water in molecular hydrogen and oxygen.

If the lance is in the area of the melt side in the event of malfunctions End 2 burns and the cooling chamber 12 to Melt opens out due to the use of the fine Aerosols as a cooling medium practically no danger that yet liquid water is enclosed by the melt and then evaporated explosively. In the cold room 12 preferably set an overpressure sufficient to Diving operation of the lance possibly into the cooling chamber 12 to push back through molten metal or slag and prevent further intrusion.

The cooling medium flowing back through the ring line 14 becomes via an annular chamber 15 and a connecting piece 16 from the Lance removed. It can either be rejected (more open Cooling circuit) or returned to the cooling circuit again become.

The annular chamber 15 has a second connection 17 which with a safety pressure relief valve, not shown in the drawing connected is.

The lance can also be used to introduce media into the melt also used to measure properties of the melt become. For this purpose, the melt side End 2 measuring instruments not shown in the drawing to be ordered. With a radiation pyrometer can For example, the temperature of the melt can be measured. At a Steel melt can, for example, by means of laser-induced emission spectroscopy a multi-element analysis can be carried out. In this way, for example, a steel finishing process can be measured be followed and ended at the desired stage.

To carry out such measurements, the lance with the attached measuring instrument in the area of the surface of the steel bath. Through the lance tube 1 is preferred Blown compressed air or an inert gas such as nitrogen, which on the one hand keeps the lance opening free and on the other hand removes slag from the steel bath surface.

The lance according to the invention is through an opening in the wall or cover inserted into the converter or furnace. The connections for supply and discharge of the cooling media and the mixing chamber are preferably located outside of the converter in a correspondingly cooler area.

3 and 4 show a second embodiment of the invention, with the gas and liquid separated to the melt side Lance end 2 and the gas / liquid mixture only in situ during the relaxation process arises. The same reference numbers designate functionally here identical components in comparison with the embodiment 1 and 2.

The main difference compared to the embodiment according to 1 and 2 is that around the inner lance tube 1 arranged around three concentric ring lines are. The inner ring line 18 leads to cooling water Lance end 2 on the melt side, it stands for this purpose the annular chamber 4 in connection. The middle ring line 19 is via the connection 7 and 9 with the connecting holes provided annular chamber 6 fed with compressed air. The outer Ring line 14 is used as in the first embodiment Return of the heated cooling medium to the annular chamber 15 and the associated connection 16.

Water and gaseous gas flow through the ring lines 18, 19 Medium (compressed air) separated from the lance end on the melt side 2. When the compressed air escapes into the annular chamber 12 and accompanying relaxation tears this also escaping Cooling water with it and breaks it down into a fine one Aersol. The two-phase mixture used according to the invention arises in situ.

Surprisingly, the operating pressure of this embodiment compared to the lance according to FIGS. 1 and 2 clearly can be reduced. So it is enough to achieve a finely divided Aerosols that flow through at high speed the annular chamber 12 passes through and is subsequently discharged will, from that water in the ring line 18 with an overpressure of 0.5 bar and the compressed air in the ring line 19 with a pressure of 1.5 bar.

Claims (10)

1. Process for cooling a lance provided for introducing a cooling means in a melted mass and/or for measuring the characteristics of the melted mass, whereby a gas/liquid mixture is made to flow as cooling means in a cooling loop closed towards the end of the lance (2) at the side of the melted mass, characterised in that the gas/liquid mixture or the components thereof is/are made to flow under pressure in the proximity of the end of the lance (2) at the side of the melted mass, and here is/are left to depressurise.
2. Process according to claim 1, characterised in that the gas/liquid mixture is produced in a mixing chambers (5, 6) of the lance, separated from the end of the lance (2) at the side of the melted mass.
3. Process according to claim 1 or 2, characterised in that the gas/liquid mixture is brought up to the end of the lance (2) at the side of the melted mass under a pressure of 2-6 bars, preferably roughly 3 bars.
4. Process according to claim 1, characterised in that gas and liquid are brought separately to the lance (2) at the side of the melted mass, and here are left to depressurise, whereby during the depressurisation procedure a gas/liquid mixture forms in situ.
5. Lance for carrying out the process according to claim 2 or 3 with a cooling loop closed towards the end of the lance (2) at the side of the melted mass, characterised by a mixing chamber (5,6) arranged at a distance from the end of the lance (2) at the side of the melted mass and connected to the cooling loop, such a chamber exhibiting connections (3, 7) for a gas and liquid feed and being structured so as to create a gas/liquid mixture, whereby the mixing chamber (5, 6) is connected through a pressure line (10) with at least one two-faced nozzle (11) arranged in the proximity of the end (2) of the lance at the side of the melted mass.
6. Lance according to claim 5, characterised in that the mixing chamber (5, 6) exhibits two concentric ring chambers (5, 6) surrounding the lance pipe, with connection holes (9) being arranged in the radial partition wall (8) thereof.
7. Lance according to claim 6 or 7, characterised in that the pressure line is a ring line (10) which concentrically surrounds the lance pipe (1).
8. Lance according to claim 7, characterised in that for bringing back the depressurised gas/liquid mixture from the end of the lance (2) at the side of the melted mass to the outlet (16) where the mixture comes out from the lance a second ring line (14) which concentrically surrounds the pressure line (10) is foreseen.
9. Lance for carrying out the process according to claim 4 with a cooling loop closed towards the end of the lance (2) at the side of the melted mass, characterised by two pressure lines (18, 19) connected with connections (3, 7) for a gas and liquid feed that are structured for the separate feeding of gas from one side and liquid from the other into the end of the lance (2) at the side of the melted mass and which end up with nozzle configurations in the proximity of the end of the lance (2) at the side of the melted mass through which a gas/liquid mixture forms in situ.
10. Lance according to claim 9, characterised in that the pressure lines are ring lines (18, 19) which concentrically surround the lance pipe (1).

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