DE2150821C3 - Combined process for operating a blast furnace - Google Patents

Description

2 50 821

Fig.3 shows improved temperature distribution in the Shaft;

F i g. 4 shows the influence of the invention on the basis of other temperature distribution profiles in the longitudinal direction of the blast furnace for different oxygen concentration in the blast furnace wind;

Fig. 5 shows the change in the atomic ratio of oxygen to iron due to the invention Procedure;

F i g. Fig. 6 shows the change in atomic ratio caused by the blowing volume of the reducing gas;

F i g. Figure 7 shows a suitable range for the blowing volume of the production gas, which takes into account the oxygen content in the blast furnace wind

In Fig. 1 are the actual temperatures based on various oxygen concentrations in the blast furnace wind at eight measuring points from the tip to the nozzles of a conventional blast furnace, which has a production capacity of 20001 per day, plotted and with those of the ordinary The operation of this blast furnace compared. All of these temperature distribution profiles show one Reversal at the seventh measuring point, namely a noticeable increase in the temperature in the rest at higher Oxygen content. It could be shown that as a concomitant phenomenon with the above-mentioned changes the coke content and also the loss of carbon solution increase rapidly. Make these appearances It is clear that both of the preheating and the indirect reduction of the starting material conclude is softened and that then the increase in the directly reduced amount due to the low temperature and bringing in the unreduced ore directly reaching the elevated temperature area.

The process according to the invention is the same as for the known process mentioned at the outset a reducing gas or a non-oxidizing gas is blown into the blast furnace in a zone in which a Pressure drop occurs. It is now important that the blowing volume of the gas with regard to the oxygen concentration is determined in the blast furnace wind according to the invention, as illustrated in the figures is. In Fig. 1 are the temperature changes in the longitudinal direction of the furnace, which are related and have been determined on the basis of test results, shown and shown in FIG. 3 in one Scheme shown. The values are in a conventional blast furnace with a capacity of 1300 t per day has been determined under the following operating conditions for which the individual curves apply.

Curve A: Theoretical course of the amount of heat required to operate the blast furnace.

Curve 1: Course of the amount of heat that is consumed _{in standard operation with 21% O 2.}

Curve 2: Course of the amount of heat that was consumed.

1000 ° C is blown into the blast furnace at the same time as the operation described in curve 2.
Curve 3: Course of the amount of heat that is

drifted with 31% O, is consumed.

Curve 3 ': Course of the amount of heat, which in a

combined operation is consumed,

at the 890 m ³ reducing gas per ton

Pig iron below a temperature of

1200 ° C at the same time as that for curve 3

operation described is blown into the blast furnace.

From the curves shown in Fig. 2, which in the

Above operating conditions have been recorded, it can be seen that the consumed The amount of heat in the zone of indirect reduction is far lower, not only than that of standard operation, d. H. Curve 1 in Fig. 2, but also

ao is less than the theoretical value, ie curve A in Fig. 2, just as the oxygen concentration oes blast furnace wind increases. Compared to these, state-of-the-art curves, there is a merkliviic improvement in the

a5 digenden heat conditions when reducing gas is blown into the blast furnace, such as curves 2 'and 3' in FIG. 2 show. Even when operating at 31 ⁰ OO ₂ , which creates the most noticeable insufficiency in the amount of heat, it becomes the amount of heat required

easily ensured if a suitable reducing gas is blown in as set out above. Appearance in such a case that the temperature of the zone compensates for the indirect reduction is, in a scheme in FIG. 3 shown. The

means that the limit occurring in the processes according to the prior art is solely through the inventive method is broken.

F i g. 4 shows temperature distribution profiles in the longitudinal direction in the blast furnace, those in others

repeated experimental operations. These profiles correspond to an O ₂ concentration of 25 ⁰ Zo and 28%, which is based on the prior art and the method according to the invention, in comparison with the. Standard operation. the

The temperature and the volume of the injected reducing gas in the case of an O ₂ concentration in the blast furnace wind of 25 ° / o are around 125O ⁰ C and 490 Nm ³ per ton of pig iron and in the case of an O ₂ concentration of 28 ⁰ O correspondingly around

1300 ° C and 585 Nm ³ . The point above the rest was selected as the point of injection of the reducing gas into the blast furnace and the point below the shaft as the position of the rest. The data points consist of toe ^"1 holes, the nozzles included together. For F i g. 6, it is seen that Reduktionsgasblasverfahren to the invention has the decrease in the temperature, which was brought about by the process according to the prior art, compensated, and that the temperature distribution

profile, which is based on the method according to the invention, met with that of the standard operation

G
drive with 26 ¹ Vo O _{2 is} consumed.

Curve 2 ': Course of the amount of heat that is consumed in a combined operation in which 540 m ^{3 of} reducing gas per ton of pig iron is below a temperature of F i g. 5 and υ show that the atomic ratio of O to Fe increases with the increase in the oxygen concentration in the blast furnace and decreases with the decrease in the blowing volume of the reducing gas. On the basis of these test results it can be seen in which limits the blowing volume

Men of the reducing gas _{must be kept in view of the O 2} concentration in the blast furnace wind. The upper limit for the blast volume of the reducing gas is located at 1070 Nm ³ per ton of pig iron at a 0 ₂ concentration in the blast furnace wind of 21 ° / o and 1250Nm ³ at an O ₂ concentration of 40% and the lower limit 0 Nm ³ at an O ₂ concentration of 25% and 850 Nm ^s at 40% O ₂ .

Another example is the application of the method according to the invention to a blast furnace wind with an oxygen enrichment of 10 _{%: With an O 2} concentration of 31%, a blast furnace designed for a capacity of 6000 l per day produced about 9000 l per day and the coke content was kept at 374 kg per ton of pig iron. The reason for the above-mentioned higher efficiency and this improvement in production capacity is that the limit based on the heat exchange surface has been broken and the lowering of the temperature in the shaft has been well compensated for. As a result, the preheating of the gout and the indirect reduction reaction for these gout were effectively achieved. Furthermore, a decrease in the amount of nitrogen and the volume of gas per ton of pig iron was brought about in the lower zone of the blast furnace. Consequently

ίο decreases the pressure resistance for the blast furnace wind, which leads to a limitation of the operation. In addition, the furnace gas can have a high energy content are withdrawn and used as a heat source for steam ovens or the like.

In the above-described method according to the invention, for. B. denatured Gas from heavy oil, or a non-oxidizing gas is used.

For this purpose 2 sheets of drawings

Claims (4)

increases rapidly. It should therefore be stated that the claims: limit of oxygen enrichment is at the value given above. 1. Combined method for operating a There are several improved methods proposed, chla blast furnace, at the oxygenated 5 gene and been related to the above Blast furnace wind blown in by blow molding to eliminate deficiency. It is Z. B. known that by is and at the same time an injection of heavy oil, steam or on the oxygen content of the blast furnace wind in terms of quantity and temperature through the nozzles, the increase in gas volume matched reducing gas is forced above mens. In such a procedure the blow molding is blown into a zone, in io the temperature in the area decreases which a pressure drop occurs, thereby causing the nozzles with the endothermic reaction, and it denotes that the amount of reduc- is the tendency to produce free carbon, tion gas with increasing oxygen concentration tion of the blast furnace wind is increased so that the blast furnace is undesirable. Another example is the profile of the temperature distribution in longitudinal 15 the CNRM method is known, which is a Überwinrichtung of the blast furnace almost with the profile of the heating surface's own boundary coincides, the purpose of the usual blast furnace wind that the blast furnace in a low shaft composition was changed without oxygenation furnace. However, it is determined what occurs. den that also the above-mentioned CNRM process 2. The method according to claim 1, characterized ge ao a limit of the oxygen concentration in the high, that the blown gas has a furnace wind, which is essentially at the above non-oxidizing gas is listed 25 to 26 ° 0 remains. Furthermore, this is 3. The method according to claim 1 or 2, characterized by the Raick method, a complex method of operation marked, "Let the oxygen concentration natural gas or heavy oil, have been suggested. at of the blast furnace wind is up to about 40%. he procedure is not a practical guide 4. The method according to claim 1, characterized in that the device has been shown, but only a simple one indicates that the temperature of the blown-in consideration, which is based on the total thermal equilibrium reducing gas about 1000 to 135O ⁰ C, has been given. It can therefore be determined amounts. that a usable process with acidic 30 blast furnace wind has not yet been found. The invention has for its object to be a How to show how the oxygen content of the blast furnace wind and thus the capacity of the blast furnace The invention relates to a combined method 35 which can be increased without the coke content increasing, for operating a blast furnace in which oxygen is used and, at the same time, a blast furnace wind enriched with oxygen-oxygen is blown into a zone through the blast furnace blast in terms of quantity and temperature, and at the same time a reducing gas adjusted to the oxygen content temperature is blown into a zone above the blast furnace wind in terms of quantity and temperature Bubble a pressure drop occurs. form is blown into a zone in which a pressure drop occurs during experimental work with processes. The purpose pursued with the invention for those oxygen-enriched blast furnaces is introduced into the blast furnace with such a method, is established 45 by the fact that the amount of reducing gas has been achieved, that the use of blast furnace wind with increasing oxygen concentration of the high oxygen enrichment of l ° / o an increase in furnace wind.: ·. 'is increased so that the profile causes the tapping amount of about 5%. However, Temperat «rv :, _t ; rig in the longitudinal direction of the high level has also shown that it coincides for the height of the furnace near- * '» _: λ.ι y; m profile, which with oxygen concentration in the blast furnace wind a usual HowiO '- .; There is a limit of 25 to 26 * / e without acidic knowledge. When storage accumulation occurs. the actual concentration above the above-mentioned When the maximum limit lies, undesirable influences occur. due to the oxygen content of the blast furnace wind The gnird for it lies in the growth of the war- is caused, correctly compensated and a free transition between gas and solid and the indirect reduction of iron ore Subsequent reduction in the reaction rate. Unreduced ore no longer penetrates into the speed due to low temperature in the rich high temperature, and the capacity of the Manhole. Because of this reduction in the temperature of the blast furnace, it can be increased by higher oxygen levels Increase the shaft and the resulting restraint in the blast furnace wind without affecting the coke the gas reduction of iron ore reaches 60 percent increases. Unreduced ore directs the zone of elevated tem- In the following the invention is exemplified temperature and the amount of directly reduced ore hand explained in the accompanying drawing:
increases noticeably. Attempts by the inventor have been shown. 1 represents the temperature profile in the blast furnace in shows that the decrease in temperature in the longitudinal direction represents that was reached through the oxygen concentration shaft about 100 ° C with an oxygen concentration 65 in the blast furnace wind;
tion of 26% achieved in the blast furnace wind. When the F i g. 2 show the improved heat conditions Concentration is above 26%, a sharp erosion occurs in the furnace, which is due to the depression according to the invention the temperature and the coke content are based on driving;