DE2021360A1 - Method and device for monitoring a melt - Google Patents

Description

The invention relates to methods and devices for monitoring the condition of a melt

According to the invention, a method and an apparatus be created that make it possible to maintain the state e.g. the temperature or the composition of a melt despite the presence of an obstructive layer, e.g. one possibly on the surface of the melt Slag layer to monitor. Applicability of the invention is particularly, but not exclusively, when Measuring the temperature and composition of liquid steel in containers for making steel, in particular in the so-called LD and LDAC steel recovery tanks, to which oxygen is supplied via a lance.

The invention provides a method for the stated purpose to monitor the state of a melt before that Includes measures to immerse a head in the melt, the at least one channel or passage with an open end, so that this open end under the Surface of the melt is located to further a gas through the

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BATH ORIGINAL

Channel and its open end to direct it to allow penetration molten material is prevented in the channel, and through the channel through the state of the melt monitor near the bottom of the channel.

If the melt has a surface layer consisting, for example, of slag, it enables one to pass through Gas through the channel, the free end of the head so pass through this surface layer that it is in the actual melt is immersed without material from the slag layer or the melt entering the channel. Therefore, the channel below the surface of the melt is in direct communication with the melted one Material, ■

The invention further provides a device for monitoring the state of a melt, which comprises a head which has at least one channel with an open end through which a gas can be passed, it being possible in this way to introduce the head into the melt to be monitored immerse in that the open end of the channel is below the surface of the melt, and a device by means of which the channel can be monitored, the state of the melt near the open end '.

It is preferably ensured that a gas or water serving for cooling is passed through the head which during use can normally be part of a forms a lance cooled with gas or water.

The monitoring means can comprise a thawable thermocouple which is movable within the channel and can be brought into and out of contact with the melt.

In another arrangement, the monitoring means Sampling means comprise which can be moved through the mentioned channel in order to obtain a sample from the melt refer to.

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BATH ORIGINAL

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Alternatively, the monitoring means can comprise a device for receiving radiation emitted by the melt. For example, the monitoring means in the form of an optical pyrometer or at least in the form of the light-receiving part of an optical pyrometer be trained. Inside the lance or outside the head, a photoelectric cell can be placed cord »If this is the case, light transmission means are provided, to transmit the light to the photoelectric cell » Alternatively, the monitoring means can be a spectrometer or at least one light-receiving part of a spectrometer include.

If necessary, the head can have several channels of the aforementioned Have type in which similar or different monitoring means are arranged.

If a monitoring lance in connection with a Oxygen lance is used in a steelmaking tank, control means can be controlled by a device for Feeling the surface of the liquid metal with the help of the monitoring lance to be operated, so that the absolute distance between the nozzle of the oxygen lance and the surface of the liquid metal can be determined.

The invention and advantageous details of the invention are illustrated below with reference to schematic drawings explained in more detail using exemplary embodiments.

Fig. 1 is a longitudinal section through a monitoring head according to the invention.

Fig. 2 shows in a longitudinal section a sampling chamber, which can be used in connection with the measuring head according to FIG.

Figure J is a schematic representation of an apparatus to determine the distance between the nozzle of a Sauere-cofflaxLze and the surface of the liquid metal in

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BAD ORiGJNAL

- 4 a steel making tank.

Fig. 4 shows a preferred embodiment of the invention in a partial section.

Fig. 5 is a partial section through a further preferred one Embodiment of the invention.

Fig. 6 shows in a longitudinal section, its halves in comparison with the actual arrangement at an angle of 120 ° to each other, a preferred composite arrangement according to the invention.

In Fig. 1 can be seen a head for monitoring the state of the melt in a steelmaking tank, and this head comprises a water-cooled cylindrical outer housing 10 which can be easily and quickly removed from the adjacent end of a water-cooled lance not shown can be removed. The head includes two easily interchangeable end sections in the form of tubes 11 and 12, open at both ends, made of a metal-ceramic material (cermet) or the like material that can withstand high temperatures, each defining a channel 33 and 34, respectively. With the top ends of the Pipes 11 and 12 are connected to pipes 13 and 14, by means of which the head is supplied with a cleaning or flushing gas, e.g. air or a chemically neutral gas such as nitrogen can be supplied.

When using the device, the purge gas is continuously passed through the tubes 11 and '12, while the head is lowered towards the liquid metal in an LD or LDAC steelmaking tank so that the Interiors of the tubes 11 and 12 when approaching the metal and free of slag or splashes or the like when a slag layer floating on the metal is pierced stay. In addition, the upper part of the measuring head remains relatively cool. When the pipes are the liquid metal will reach the liquid metal through the gas streams

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prevented from entering the pipes by themselves when the pipes are below the melting level be immersed in the metal. At a low flow rate, the gas trickles through the melt up to the surface of the melt, whereby the liquid metal immediately surrounding the lower ends of the tubes is constantly exchanged or kept in motion.

This way it becomes an ideal or near-ideal Created measuring surface whose radiant light energy with the help, an optical pyrometer can be measured. The optical one Part of the pyrometer can differ from the corresponding part of pyrometers of known type in that the Light "according to Pig. 1 is collected by a lens 15 arranged at the upper end of the tube 12 and with the aid of a flexible Light guide 16, e.g. a fiber optic guide, to a photocell is routed, which is in the measuring head or the Hf..uptvertei4 lerleitung the lance can be arranged.

A thermocouple 17, which can be easily removed and is provided with a protective cover, is provided in the tube 11, which is connected to a piston 19 by a rod 18 which is slidably mounted in a gas bearing, for example, which works with air or nitrogen a double-acting gas or pressurized water cylinder 20 can cover. If a pressure medium is supplied to the cylinder 20, the protected thermocouple 17 is moved so that it protrudes downward from the tube 11 and is immersed in the liquid metal so that the thermocouple can measure the temperature of the melt. As soon as the measuring process is to be ended, the piston 19 is actuated again in order to pull the thermocouple 17 back into the tube 11. In this way it is possible to use the relatively complicated measuring element only during the minimum required. Time to immerse in the liquid metal, so that its leTbeas duration is extended * The protective cover = äea Thej'-uoclesst = -α -> - Κ <Εί;; however, if necessary see easily ■ &&& »Γοθϊι & 6, \ ?. η _β 'Ύο: ο. a®m "

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Thermocouples extend from electrical wires through a central bore of the rod 18, e.g. via a simple plug connection at the upper end of the protective cover of the Thermocouple, to a central conduit 21 in the measuring head, in the channel 21 are also the required gas and Housed water supply lines.

The protective sheath for the thermocouple can be replaced by a small chamber 22 (Fig. 2) for taking a sample of the liquid metal. This sampling chamber can comprise an outer tube and have an inlet 24 on one side and be provided with an upper closure wall 25 and a lower closure wall 26. A fast responding thermocouple 2? is arranged in the upper part of the chamber 22 so that it protrudes downward beyond the inlet 2b. .

The chamber 22 can be used to quickly take a metal sample and it can be withdrawn into the protected area of the tube 11. Measuring the temperature of the metal sample during its cooling makes it possible to determine the percent carbon content of the steel after the breakpoint method in which the breakpoint, that is, the temperature at which the cooling stops momentarily, or _s takes place at a considerably-reduced speed measured will show mm the carbon content. The chamber 22 is to me for single use only IMA Damer eo excluding © fancy t _s that they can be set down with as low as possible © »Kastea !! _o Since, maa chamber AIIF © iaiial Ibaiteti © ^, -teas _s Immi MSSL'zwai © dLer n # ir chambers 22 in ®im

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and use them at different times with the help of the Actuate the same double-acting cylinder or different cylinders.

When the tubes 11 and 12 are made of an electrically conductive material and one of the tubes opposite the head is electrically isolated, one can use a device for measuring provide for electrical conductivity between the pipes, so that it can be determined when the liquid metal is in contact with both tubes. Alternatively, you can detect the immersion of a pipe in the melt if a device is provided that enables the sharp pronounced transition from a high purge gas flow rate at a low pressure to a smaller flow rate to be detected at a higher pressure, which is the case when immersed of the pipe as a result of the high specific gravity of the liquid steel. In a different arrangement can to provide a device that enables the higher Determine the speed of the pressure increase as a function of the vertical distance covered downwards, after a tube 11 or 12 has come into contact with the liquid metal; in this procedure, the high specific gravity of liquid steel exploited. The gas flow rate and the pressure are preferably outside the Lance measured and regulated,

A head of the type described above can also only f comprise one pipe or more than two pipes, which are marked with ΐ Devices for measuring the temperature and for taking ' Samples are equipped. The supply of gas to the bores can preferably be regulated independently for each pipe

The various lines, e.g. for water »compressed air, Nitrogen or other chemically neutral gases as well as electrical ones Electricity, are expediently attached to the lance in a Tube housed

ORIGINAL INSPECTED

A direct measurement of the temperature of the molten steel and its carbon content is desirable in the manufacture of steel according to the LD or LDAC process, so that the heating can be ended as quickly as possible, the desired final temperature being reached so that the one achieved Carbon content corresponds to economical material consumption, and that you get a maximum yield of the process achieved; the device described above according to the Invention makes it possible to carry out such measurements.

If the standing height of the "liquid metal in one.

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Steel is determined by the LD or the LD4C method by measuring the electrical conductivity or the gas pressure or the gas flow rate in the manner described above, the information obtained in this way can also be used to absolutely determine the accuracy of the outside of the To determine the container indicated distance between the nozzle of the oxygen lance and the surface of the liquid metal, so that you can regulate this distance if necessary. The possibility of implementing such a regulation is of great importance. If the lining of the container wears off, or if it peels off, for example in a shell-like manner, the level of the melt changes in relation to a fixed point above the mouth of the container. Differences of a few inches in the distance between the nozzle of the oxygen ^{lance and the liquid metal can be:} "die ^ ere ^ e ^ d ^ JBigenechaften / vcu ^ toer.JiBr-" ~

heating "to affect the next. '_'_ " TO * """

It is now common practice to attach a metal rod of known length to the oxygen lance and the Measure the remaining length of the rod after it has been immersed in the hot melt, using the immersion depth corresponds to a certain indicated length of the oxygen lance. By comparing the "displayed" and the "Actual" countersinking depth can be indicated by a display device displayed depth can be corrected so that the

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INSPECTED

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can equate with the "actual" lowering depth.

Fig. 3 shows an arrangement with a temperature measuring and examination lance 28 and an oxygen lance 29 »Die both lances are attached to height sensing devices 3o and 31, their positions related to the same starid height are, and which generate electrical signals, which directly are proportional to the distances along which the Extend lances down below the reference level. the Reference height is set electrically or mechanically.

These signals are fed to a subtraction device 32, which is used for processing digital or analog Input signals is provided. In the device 32 is the Distance over which the oxygen lance 29 extends over the reference height extends out downward, drawn from the line, over which is the examination lance 28 from the same Reference height from extends downwards, so that the height difference is displayed between the lower ends of the lances *. -

A touch between the investigation lance and the The surface of the melt is determined by a change in the pressure of the gas flowing down through the examination lance or a change in the flow rate of this gas displayed. ·

The distance between the liquid metal and the Reference height_or: Reference plane is in Fig. 3 through the line A denotes. When the examination lance hits the surface of the Touches the melt, the oxygen lance 29 takes a position one where its lower end is a certain distance lower lies as the reference plane. As mentioned, the distance B 'is subtracted from the distance A, so that the distance C is obtained, which shows how high the lower end of the oxygen lance is is arranged above the surface of the liquid metal.

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ORIGINAL INSPECTED

The ele tric corresponding to routes A, B and C. Signals can be used as input signals to a computer or a other control device are supplied. It is also possible to only display the distance G when the examination lance touches the surface of the liquid metal.

fig. 4 shows an arrangement generally similar to that according to FIG. In this modified arrangement, the base of a water-cooled lance 40, which delimits a chamber 42 containing a pressurized gas, is protected by a nozzle or head 35 made of a flexible material, one at both ends Open channel has ₀ In the channel 33 is a thermocouple protective sheath "from what is known under" the legally protected designation. ¹¹ Cermeteriii "or the like and attached to a tubular rod 18, the other end of which is connected by a (ielenkbolaen 36 to a double-acting compressed air cylinder 20. The rod 18 is supported at its upper end by the cylinder and further down by a gas bearing 37 In its retracted position shown in FIG. 4, the protective sheath 17 is pushed through the arrows surrounding it, the lance 40 and the nozzle head 35 its upper end merges into a plug 38 which fits into a receiving part built into the rod 18. After removing the outer covering, the thermocouple can therefore be borrowed and quickly replaced by a usable new thermocouple the base of the Umjiüilimg dej .Thermoelement s to _ge, s The upper attachment is subject to a slight spring tension, so that the cover made of i'omerde forms a layer between the hot soldering point

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The electrical connection between the receiving part on the movable rod 18 and a connecting block is through a extendable flexible compensation cable 39 is formed.

The nozzle passage 11 can constantly "by means of two gas * - flushed trömen .s-turn ,, is directed by denen..der eine.durch _Λ a pipe 48 directly to the channel, while the second gas flow from the pressurized chamber 42 flows through holes 41 in the wall of the tubular rod 18 into the interior of the rod, to continue to escape. below via similar holes ^r ffi £ * at the "lower end. This arrangement ensures a steady currents are gas without regard to the position of the A third, but practically negligible, gas flow escapes from the gas store 37 and is discharged via the nozzle channel 11.

The work cycle begins with the lowering of the lance through the hood and the container mouth, while all Gas flows flush the annulus passing through the base of the Thermocouple sheath and channel 11 is delimited. ,Everything Metal and any slag ejected from the container are rejected by the nozzle so that its Interior is kept clean. As soon as the slag layer is reached, the pressure that builds up prevents the Slag enters the channel, and the same applies to the F 11 that the nozzle reaches the liquid metal. Of the Pressure that is required * around the static pressure gradient of the slag and the metal at an immersion depth of approx 1CX) mm to balance in the metal, is about 2.15 atiL. When the lower end of the nozzle TOl3.frt8iLd.ig is inserted into the metal

'0098A 5/1 4 18

is immersed, you can interrupt the main purge gas flow, while some or all of the remaining secondary gas flow and storage gas through the metal pearls through it upwards. At any later point in time, the air cylinder can be operated remotely to the covering of the thermocouple from the protected area move them out and dip them directly into the metal bath. In this way it is prevented that the envelope is in constant contact with the oxidizing slag, and it is only then possible to put the coating in immersing the molten steel if necessary. Regardless of whether the lance should be raised, the thermocouple can be withdrawn at any time into the protective housing formed by the lance and the nozzle will.

After the end of the measuring period and before the new one Lifting the lance is done in the opposite direction, i.e. the casing is withdrawn and the main purge gas flow is carried out again to.

Fig. 5 shows an arrangement similar to that of FIG. 4, but in which the thermocouple assembly by a Sampling chamber 44 of the type (22) described with reference to FIG. 2, which can be operated according to the breakpoint method, is replaced. The chamber has an orifice 46 and a thermocouple 47 is located in the chamber. The chamber is opposite the Lance housing electrically insulated, but one side of the thermal el ementkreises with., One at the base of the sampling chamber attached probe 45 'connected. The way of working this arrangement corresponds essentially to that in the case of the temperature measurement described, apart from the fact that the probe 45 a physical barrier against ejection of the Forms melt and also acts as a sensor, by means of which the level of the liquid metal is determined. . . ". T

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ORIGINAL INSPECTED

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■■ ... '· ■■ After the lance has been lowered so far that known is that they are at a point above this zone "is located, two such probe assemblies are located in the same measuring lance at the same time by actuating two compressed air cylinders lowered to a not shown, temporarily effective Anachlag, so that 3ede probe over a Length of about 25 mm immersed in the slag. If one uses these probes as the probes of a "conductivity meter, while the lance continues to slowly advance downwards, the level of the liquid metal can be determined. As soon as the height of the metal has been determined - you can

Impact can be removed and the lance can be lowered further a short distance to ensure that it is fully immersed in the metal. ν:. : ^ Li ₁ -Γ ^: ·

A sampling chamber can then be automatically lowered into the melt, in which it remains for a predetermined time, after which it is withdrawn again upwards into the channel 11. These sample extraction chambers must be designed in such a way that the sample can be cooled while the sample is still in the melt, in order to prevent a stopping point from being reached while the chamber is being withdrawn. This let * take helps to reduce the overall response time to a minimum · ',' ■

The construction of such a sampling device can be simplified in various points because the device directly from the housing into the liquid steel is transferred, while it is necessary in the constructions customary up to now, to a receiving vessel tilt. The electrical connection does not need to come from the water-cooled zone, and therefore: _It must be voidly protected. - · .- .. ~ —r - "-——---

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It is also not necessary to provide the aluminum or mild steel cap, which has been used up to now, which protects the inlet opening, since no short-term protection is required due to the absence of slag. As a result, the sampling chambers fill up quickly and in the same way each time, and fairly rapid but even cooling is possible within a time which is typically 5 to 6 seconds. Furthermore, it should be borne in mind that the difficulty is reduced to a minimum that arise during cooling and the user of the "hold point method" as a result of vibrations.

Pig 6 shows, in longitudinal section, an assembled lance which is provided with arrangements according to FIGS. 4 and 5 and a thermocouple assembly 17 and at least two Sampling chambers 44 made of carbon, of which the latter only one can be seen in FIG. 6, so that the Stiraan is made of a heat-resistant material ■ ordering nozzle 35 would appear just like the one a conventional oxygen lance with three holes.

The spring for ensuring a good thermal aging between the sheaths of the thermocouple 17 is in Pig ,. 6 denoted by 49. At 50 you can see a hole for supplying gas to the bearings 57

The lance 40 have a hollow wall which is divided by a ¹ Irish wall into two concentric annular chambers 51 and 54, each of which forms a water jacket. Bas GaS ^- Wi-E ¹ Cl is fed to the chamber 42 via a bore 53 in order to set this chamber under pressure.

If the device according to the invention is a, c possible should, an al furnace working according to the LD process

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BATH ORIGINAL

To control them, the lances and the probes must be reliable work, they must be easy to use, and their parts, which are only intended for single use, must be replaced within the shortest possible time permit. Despite the apparent intricacy of the foregoing described arrangement can be practical inside the lance hardly any disturbances occur. The few moving parts inside the lance are pneumatically operated, but they are themselves when minor gas leaks develop should, this would normally not affect the serviceability of the air cylinders. Since the gas to the '' Uritef pushing the nozzle in -three "-different" ways of pulling- " operation can continue if the normal gas supply fails to prevent steel from entering the Nozzle channels enters. , ·· «,, _

The renewal of the inner thermocouple assembly would normally coincide with the renewal of the sheath and there would only be a delay of a few seconds. However, the sampling chambers do not need after each immersion renewed to be "This work will be performed on a disposed above the lance service station, but äube on one side of ^H smoke.extraction. At this station, all compressed air cylinders are operated to make the measuring elements accessible to Aachen. Sampling chambers are normally held in place by quick-release, spring-actuated clamps on the base of the rod.

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BAD OBlGiNAL

Claims (1)

1. Procedure for monitoring the condition of a melt, thereby g e k e η η ζ e i chnet that a head is immersed in the melt, the at least one channel with an open end, so that the open end under the surface of the melt is that a gas is passed through this channel and its open end to the To prevent molten material from entering the channel and to prevent the state of the melt from passing through the channel is monitored near its open end. 2. Method according to claim 1, characterized draws that the state of the melt is monitored through at least one channel in such a way that Monitoring means are used, the receiving means arranged in the head for receiving radiation from the melt include. 5. The method according to claim 1 or 2, characterized that the monitoring means from min- at least one channel pushed out and in contact with the Melt brought and then withdrawn back into the channel. 4. The method according to claim 3, characterized in that g e k e η η ζ e i c h η e t that as a monitoring means temperature measuring. medium can be used. 009845 / U 18 ORlGiNAL INSPECTED . ■■■■■■ - 17 - 5. The method according to claim 3 or k, characterized ge ke η η ~ .zeichen that the melt consists of steel, and that sampling means comprehensive monitoring means are advanced from at least one channel out into the melt in order to take a sample from the melt that the sampling means are then withdrawn together with the sample into the channel, and that the cooling rate of the sample in the channel is then measured. : 6. The method according to claim 3 or k, characterized geke nn draws t that the melt is a steel melt and the monitoring means is advanced with at least one device for removing a sample from at least one channel out into the melt in order to remove a sample, whereupon the cooling rate of the sample is measured and then the device is withdrawn back into the channel, 7. The method according to one of claims 1 to 6, characterized in that indicates that the head has at least two channels comprises monitoring means out of the two channels advanced and brought into contact with the melt and then be withdrawn again into the canals, and that the monitoring means are components of "an electrical Form circuit that is closed upon contact between the monitoring means and the melt to to determine the level of the melt. '. 8. The method according to any one of claims 1 to 6, characterized g ek e η η ζ ei c h η e t that at least twelve of the head Channels are at least partially formed in two bores extending downwards from the head, and that these pipes form part of an electrical circuit * caused by contact between the tubes and the melt is closed to determine the level of the melt. 00 9845/1 k 18 ORIGINAL INSPECTED 9. The method according to any one of claims 1 to 6, characterized indicated that a change in pressure of the gas or its flow rate or throughput rate or the rate of change of pressure or To determine the level of the melt. 10. The method according to any one of claims 7 to 9, characterized characterized in that the melt is steel, and that the determination of the level of the melt serves to keep an oxygen lance in the correct position in relation to the molten steel. 11. Device for monitoring a melt, marked through a head with at least one channel, (33, 3 * 0 with an open end, through which a gas is passed can be, wherein the head is immersed in the melt that the open end of the channel is below the surface the melt is located, and by monitoring means that make it possible to monitor the state of the melt through the channel monitor near the end of the channel. 12. The device according to claim 11, characterized in that g e k e η η - ζ eic h η e t that the monitoring means are arranged in the head Exceptional means (15) for absorbing radiation from the melt through at least one channel (3 * 0 through- " grasp. 13. Apparatus according to claim 11 or 12, characterized by actuating means (2o, I9, 18; 2o, 36, 18) for moving monitoring means out of at least one channel (33) and for withdrawing the monitoring means into the canal. 1 * Κ Device according to one of claims 11 to 13, characterized in that the überiuachungsaiibb ?! Temperature tower oil means (17; ¹ W) comprise. 00 904 5 / UI 3 BATH ORIGINAL -202136O 15. The apparatus of claim 13 or 14, characterized g e k en η ζ e i c h η e t that the monitoring means one Sampling container (22; * t4) for receiving a sample from the melt and measuring means (27; 4?) to determine the cooling rate include the sample. 16. Device according to one of claims 11 to 15, characterized gekennzeich η et that the head at least two Has channels (33V 3Ό, which contain electrical probes (17), which are pushed out of the channels, in contact with brought the melt and then withdrawn again into the channels, and that the electrical probes Form components of an electrical circuit that is involved in contact of the probes with the melt is closed, so that the level of the melt can be determined. 17. Device according to one of claims Ii to 15, characterized geke η η ζ eich η et that the head has at least two channels (33, 3 ¹ * -), which are at least partially through two, from the head to pipes (11, 12) extending below are delimited, and that the pipes form components of an electrical circuit which is closed when the pipes and the melt come into contact, so that the level of the melt can be determined. '· : J " 18. Device according to one of claims 11 to 15, g e k e η η ζ e ic h η e t by sensing means (* O) for sensing a change in pressure or flow rate. or the throughput or the rate of change of the The pressure or the flow rate of the supplied gas, by means of which the level of the melt can be determined can.- 19 «Device according to one of claims 16 to 18, ge Ic e η η ζ calibrate η et by a device (31, 3o, 32) for setting an oxygen lance (29) with respect to the melt depending on the determined level of the melt. ■■■■ .: ^r 009845 / U18 BATH ORIGINAL Vo Blank page