DE1433435A1 - Process for the production of steel - Google Patents

Description

Iffiä BHIiISlI IHOjM AND STKbL .ώίϋϋΜΟΗ AStk Gate, London, S. W. 1., Great Britain

J ", 24 Buckingham

■ ^ 'Procedure for the production of Stalil "

The invention relates to a method for producing otahl and focuses in particular on steel production in stove fired by a fuel stove.

An object of the present invention is to provide one Steelmaking process using a fuel burner, ?: 'it α em completely cold-j i-ochof t> nchc.rgen , with very wide fluctuations in the proportions of ochrott and Aüheis can be melted and refined.

your expression "Baustoff — x> i ■ emnstüi'i '-. irei" iner ", υπ H.as In the course of the further description, only open the door aruck ".jronner" uses / eruen. ^ irU, vüi-üte "ht 'isu one

BATH ORIGINAL _? _ _

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Burner that runs on hydrocarbon fuel and oxygen is fed and provides an intimate and complete mixture of the fuel with the oxygen.

The hydrocarbon "fuel", which in the following will generally only be referred to as "fuel", can be present in a single form or a combination of forms, for example gas, light oil and / or heavy oil, while the oxygen is an oxygen-containing gas, for example with Oxygen enriched air, is fed, so the commonly used term ^{; Sau2rstoff;!} also includes gases that are not only made of pure permanent material. "During operation, additional oxygen sources are normally present," for example, enriched air "is present", and the total amount of oxygen, which includes all , including that for the burner, and the oxygen supply or the supplied oxygen, referred to to indicate that the oxygen is supplied directly to the burner.

.s. are already presctila e for the use of oxygen-fuel burners was made in the manufacture of steel, but this was done. Use generally on the '"/ eg one Additional warning during sneaking. Find such burners in addition, during the purification use will be invariably

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the fuel supply is switched off and the burner only supplies oxygen operated. The burner is therefore found in these cases as Oxygen lance usage. This way of working is based on separation copious red iron oxide smoke accompanies the formation from such smoke not only leads to noticeable losses Metal in the form of iuetalloxyd, but also requires use expensive and extensive A'b

The present invention provides a steel manufacturing method suggested that a furnace charge only by incineration an intimate mixture of hydrocarbon fuel and oxygen melted and purified ^; ird. In \ '. Pus. • training the i-irfindung is the combustion during the said Maintain the period of purification, so da ^ prm-tisch>, a Iron oxide smoke is produced.

For a better understanding, the invention is based on the following of the drawings; Herder explains.

The drawings pointers, in

Pig. 1 a device such as that used in the development inventive method used v; urue;

809810/061

2 shows a schematic representation of a suitable burner control system ; and in

3 shows another embodiment of a furnace for implementation of the method according to the invention

]? ig. 1 shows the general arrangement of furnace pan and burner. The furnace pan 1 was produced by redesigning a 50Q kg sheet metal arc furnace by removing the electrodes and hay walls from the ceiling 2 in monolithic, fire-resistant material with the formation of separate openings in the middle of the ceiling for the burner inlet and exhaust gas outlet. The furnace "retained the usual loading door 10, the tapping 11 and a tilting gear (not shown) to make it easier to remove visual marks and to facilitate tapping * The burner indicated at 3 is provided with oxygen and fuel supply lines 4 and 5, respectively. Gen 6 is available for the water cooling jacket, which extends over the entire length of the. -Renner * The existing device for raising and lowering the electrodes is used when raising and lowering the burner 1st, although you can of course also use an arrangement consisting of a cable and washers, as well as a winch,

BATH ORIGINAL

803810/0610

Above the exhaust outlet of the furnace, a chimney 8 was attached, which was equipped with a throttle valve 9, through which the draft and thus the pressure in the furnace and the amount of secondary air can be set

During the development of the method ^{according to the invention, a considerable number of heatings 11 were} carried out in the furnace described. For a better understanding of the present invention, such a typical process will be explained in more detail.

The oven was first preheated until with a gas-air burner the temperature of the refractory lining had reached a value of 800 to 900 ° C .. Then the oxygen-fuel burner used and with light oil in quantities of 90 l / hour, as well as with oxygen of approx. 170 mVh. fired. As soon as the When the furnace ceiling temperature had reached values from 1000 to 1100, the fuel supply was set to approx. 113 l / h. and the oxygen supply at approx. 200 m / h increased. The burner was lowered so far that it dipped approx. 90 cm into the furnace hearth, whereupon charging was started.

f The batch in this example was 300 kg of steel pipe scrap, 200 kg of cast iron and 18 kg of limestone and was fed into the blast furnace by hand through the loading door.

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As the batch increased in the furnace, the burner would belong, so that the distance between scrap and burner remained relatively constant. When the entire batch had been given up, the burner was pushed down through the batch as quickly as possible so that the exhaust gases migrated up through the batch before they left the furnace. This promotes good heat transfer. The burner was held about 30 to 75 cm away from the stove, in which position the bottom rope of the burner was surrounded by scrap. The oil supply was set to 113 l / h. and the oxygen supply to 210 m ^ / S ± a. held, which together with the penetrating air resulted in a slight excess of oxygen in the exhaust gases.

The burner was held in this position until a molten metal supply was visible in the center of the pan * had developed, after which the burner was slowly pushed upwards until the scrap that had previously surrounded the burner was now directly exposed to the flame. The burner was then left in this position.

During this meltdown, the fuel inlet became like this controlled that prevents a ceiling temperature above 1600 to 1650 ° became. In practice, the ceiling temperature reaches a value of 1600 ° after 18 minutes and the fuel supply works

809810/0616

then to 68 l / h. and the oxygen supply to 125 m ⁵ / h. throttled. In addition, the furnace pressure is regulated so that excessive "sting" is avoided and the amount of air entering is regulated.

Was the bath shallow, i.e. about 3/4 of the batch was after about 30 minutes melted, the bath was stirred, a sample was taken and the temperature was measured. Analysis of the sample showed one Carbon content IjIb to 1.3 #.

The oxygen supply was then increased to 168 m / 3td. increased to favor the boiling of the carbon. The rate of carbon removal was then controlled by changing the oxygen flow so that the metal temperature rose at such a rate that it is 10 to 20 ° below the tapping temperature when the desired carbon level is reached. Oa. 45 minutes after the start of charging, the carbon content was reduced to 0.22 Fe and the metal was at a temperature of 1580 °. At this stage the anti-oxidation was carried out by adding; caused by approx. 32 kg of ferrosilicon, which was followed by the addition of approx. 54 kg of ferrous quantities «

After these gusätze were swollen after about 3 to 4 minutes, the metal was peeled off ^{at a temperature of 1600 a.} Of the .

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Steel had the following composition: 0.27 $ C, 0.15 i ° Si, 0.83 i Mn, 0.025 1 ° P and 0.04 fi S.

After the experiments with the small stove, a Heine von Tests carried out in a 5 to oven. This system had the same construction as that of the Pig furnace. 1, each-. but the cover was removable for quick loading. Allowing the help of buckets.

A typical example of the experience with these larger furnaces showed that a 4 to batch of mixed heavy and light steel scrap with the addition of carburizing agents is melted in 70 minutes and drawn off in 90 minutes with a carbon content of 0.2 $> C can. The fuel consumption was 99 l / to of tapped steel, while the oxygen consumption was 182 nr / to · Ie. For this particular palle, the maximum fuel feed rate was 270 l / hr. limited as the vent was insufficient to evacuate the exhaust gases at higher fuel velocities. Audible fuel-off speeds are to be expected in order to reduce the time from charging to tapping.

When considering more general aspects of work in accordance with the present invention it is found that a wide variety of batches can be used. During the development

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working batches were used that were 70/50 scrap / cast iron, 70/30 scrap / cast iron, 50/50 scrap / cast iron, 80/20 scrap / Cast iron and $ 100 scrap with a lower amount of build-up

decarburizing agents. All types of scrap from heavy to

easily adhere proved to be "useful.

The carbon is usually added immediately with the Charge and a suitable carburizing agent for this purpose is anthracite, coke and petroleum coke, such as those used find use in electric arc furnaces.

In general, during the melting period the oxygen flow is to the burner is less than stoichiometric, wherein the content of oxygen approximately 80 to 90 ° / o or nominally 87 ° is / o, while the total oxygen addition during the melting process a slight excess over that value that is necessary for complete fuel combustion.

A particularly notable feature of the present invention is the control of the rate of carbon removal, which by the present invention takes place essentially independently of the temperature control.

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ORIGINAL INSPECTED 80 98 1 0 / 061G

This results from the fact that the rate of temperature rise of the bath, which is caused by oxidation of the carbon, material and other metalloids * .is caused by the Heat .from the combustion of the burner fuel is supplemented. The rate of metalloid removal is largely dependent on the oxygen, which is in excess over the Burning the fuel used oxygen is present. The additional heat depends on the speed of the fuel supply from so that by changing the fuel feed rate and the total oxygen supply, the temperature rise and the carbon drop are essentially independent can be regulated from each other.

When carrying out the method according to the invention, devices for regulating the oxygen and »· · Fuel supply, devices for automatic regulation of the fuel-oxygen ratio, an overflow temperature control for the fire-proof ceiling and a failure control the cooling water supply. These requirements are largely met by the tax system introduced in Pig. 2 'reproduced is.

According to S ¹ Ig.2, both the fuel supply and the oxygen supply are measured by cross-section measuring devices 20 and 21, respectively. The differential pressure output from the oxygen port

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goes directly to a mercury flow recorder in the oxygen control device 22 and the differential pressure from the fuel port is via a pneumatic Transmitter 25 is fed to a Bourdon tube recorder in fuel control device 24. The exits from the two Control devices are connected directly to the corresponding diaphragm control valves 25 and 26, which are located in the input lines to the burner. The valve controls are dependent of the output signals from the respective control devices.

"Eemosef" ratios are located in the control devices for controlled maintenance of a desired fuel Oxygen ratio.

The overflow temperature control takes place in response to a Thermocouple 27 in the furnace ceiling, the output of this thermocouple being given to the temperature controller whose Output in turn is given to the oxygen and fuel regulator, so that when the maximum desired temperature level is achieved the fuel and oxygen flow rates on the lining can be adjusted automatically and at the same time while maintaining the same ratio for so long remains until a change in this ratio is desired.

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The hazards arising from mixing oil and oxygen are "known and largely about the risk of explosions and the like reduce, an internal shut-off valve is provided, which sits at the tip of the burner, each in the drawing. is not reproduced. Check valves 29 and 30 are also provided in the inlet lines near the burner. These check valves prevent the oil from entering the oxygen line and vice versa.

To avoid the risk of a water failure in the torch cooling system, a safety device 31 'which works as a function of the water flow is switched into the cooling water pipe. This device can take the form of a switch which is set up for alarm operation in the event that the speed of the YiTass er flow is below a predetermined one The value falls, and in the alarm condition the switch operates the solenoid valves 32 and 33 in the fuel and oxygen circuits. The supply pressure to the control valves is adjusted accordingly relaxed and close the control valves, so that 'fuel and oxygen are shut off. The fuel is also off feed pump 34 in the fuel feed line the control valve 25 to a standstill in the event of such an alarm brought.

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The furnace pan, which is used for the present purposes, can come from a conventional arc furnace or from other furnace pans be rebuilt. It goes without saying, however, that a specially planned tub is preferable. The general shape of the tub matches those for electric arc furnaces, although a slightly larger height: diameter ratio is preferable. the The tub can be cylindrical, but preferably has sloping or partially sloping walls, so that the scrap better to fall into the path of the burner flame.

The furnace roof can be designed according to Fig. 1, i.e. have separate burner and exhaust gas openings, but also in one single opening can be united, liine another alternative consists in that the exhaust gas outlet sits in the upper part of a sloping furnace wall or more than one such openings lead to a common fireplace. The furnace can be tapped through a suitable tap opening in the furnace wall while the loading takes place from above or through a loading door in the furnace wall. Though up from When talking about a single burner, several such burners can be used in the case of a very long tank.

Pig. Figure 3 of the drawings shows in section a suitable embodiment such a blast furnace, having different characteristics

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of this furnace reproduced in the general remarks above are, with the exception of two exhaust extractors, which have a better distribution support the combustion products within the blast furnace.

From the above description it can be seen that the present Invention, a steelmaking process is created using only an oxygen-fuel burner, through which a completely cold batch without significant smoke formation by maintaining the flow of fuel during can be melted and refined during the full refining period.

The charge can consist of scrap and cast iron, but also completely of scrap with the addition of suitable carburizing agents, whereby all forms of heavy to light scrap have proven to be useful. Carbon and low alloy steels of conventional compositions have been produced with metal yields in excess of 90 % .

A feature of the invention is effective independent control the rates of temperature rise and the carbon elimination through adequate regulation of oxygen and Fuel supply to the burner.

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809810/0616

The amounts of fuel and oxygen used are " As has been shown from individual batches of up to 5 tons, approximately 100 liters of fuel and 180 to 185 m of gas per ton finished steel. Obviously, however, these values can be reduced significantly with continuous operation. Also can Carry out the heating in a further 1 l / l hour from charging to tapping with appropriate firing speeds. Under these circumstances, the method according to the invention apparently works more cheaply than an electric arc furnace equivalent output,

The process according to the invention can also be used with basic oxygen furnaces to consume the scrap that is not used as a coolant can be used in converters and is also an independent steelmaking process for steelworks that are not part of the group.

Claims

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Claims (9)

Claims 1. A method for the production of steel, characterized that the furnace charge is produced solely by burning an intimate mixture of hydrocarbon fuel and oxygen is melted and purified. 2. The method according to claim 1, characterized that the combustion of the intimate mixture of hydrocarbon fuel and oxygen becomes practical complete avoidance of the formation of ferric oxide during the period of purification is maintained. 3. The method according to claim 1 or 2 ", characterized in that that in the combustion of hydrocarbon fuel and oxygen and oxygen-containing Gas is melted a completely cold furnace charge, with the proportion of total oxygen added to the fuel during the Melting is not more than the stoichlometric ratio and then the molten batch by the like Combustion, but at least stoichiometric Ratio is refined, the fuel burn rate is set so that batch and oven temperature and the proportion of total oxygen is regulated - 17 8098 10/06 1 G _ 17 - the stoichiometric ratio _{t is} adjusted to control the rate of carbon removal from the batch. 4. · The method according to claim 3, characterized in that the oxygen supply is in the range of 80 to 90 y> the stoichiometric ratio during the Schinelzens and additional oxygen is supplied at least as trapped air. 5. The method according to one or more of the preceding claims , characterized in that the exit of the exhaust gases from your furnace interior to maintain the pressure in the furnace is controlled so that only the desired amount of air can penetrate. 6. Oven for performing the method according to one or more of the preceding claims with a substantially closed tiltable furnace pan, with a ceiling provided with openings, one or more oxygen-fuel burners for burning an intimate mixture of hydrocarbon fuel and oxygen, devices for lowering the burner or the burner into the furnace interior through the ceiling and for lifting the burner (s) out of the furnace interior, and - 18 - 8098 10 / 061G with a pipe connected to the furnace for the exhaust gas outlet from inside the furnace, which is provided with a regulator or other device for regulating the draft. 7. Apparatus according to claim 6, characterized in that that the furnace pan is cylindrical in shape or extends outward entirely or partially from the ceiling to the floor he bulging walls, as well as a height: width ratio of about 1 or more. 8. Oven according to claim 6 or 7, characterized that the furnace roof has a central opening for inserting the burner and at least one separate one Has opening for connection to the forge. 9. Oven according to claim 6 or 7, characterized that the furnace roof has a number of openings for the insertion of several burners and at least has a separate opening for connection to the forge. 809 8 10/06 1 G ORIG.NAL INSPECTED