JPS62196310A - Method for adjusting quality of gas generated in melt reduction furnace - Google Patents

Abstract

PURPOSE:To adjust the temp. and reduction potential of the high-temp. produced gas subjected to secondary combustion in a melt reduction furnace for iron making so at to be made suitable for the progression of a preliminary reduction reaction by adding the gas obtd. by the heating cracking of a hydrocarbon to the produced gas. CONSTITUTION:A by-produced gas is subjected to secondary combustion in the melt reduction furnace 2 at the time of successively conveying said gas to a preliminary reduction furnace 1 and the furnace 2 and reducing iron ore. The gas formed in such a manner has no reducing power any longer but has a high temp. and much heat energy. Such gas is conducted into a reformer 9. For example, CH4 is not conducted directly to the reformer 9 at ordinary temp. state and the cracked gas (gaseous mixture composed of C, H2 and unreacted CH4, etc.) formed by heating and cracking the CH4 in a heating and cracking device 12 is conducted to the reformer. Then the above- mentioned cracking reaction is an endothermic reaction and therefore, the high-temp. gas from the furnace 2 is decreased to the suitable temp. by the heating temp. control of the device 12 and the reforming reaction is satisfactorily progressed. The gas of the temp. and reducing power suitable for the introduction into the furnace 1 is thus obtd.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is directed to evaluating the temperature and reduction potential of generated gas whose temperature has increased and reduction potential has decreased due to secondary combustion in a smelting reduction furnace. , relates to a method that can be adjusted to be suitable for preliminary reduction.

[Conventional technology] The so-called direct steel manufacturing method is attracting attention as a technology for manufacturing pig iron without using a blast furnace.
The IN Law, the Steel Works Law, the Sumitomo Metal Law, etc. have been developed. These methods attempt to reduce iron ore by sequentially transporting it through a preliminary reduction furnace 1 and a smelting reduction furnace 2 as shown in FIG. The introduced iron ore is preliminarily reduced by the reformed gas described below. The iron ore pre-reduced in the pre-reduction furnace 1 is
It is then guided to the melting reduction furnace 2 (arrow 5).
, the iron ore is blown into pulverized coal and oxygen (
It is further reduced by arrow 6) and extracted as pig iron (arrow 7). By the way, CO gas (however, CO2, H2
, H20 gas, etc.), but in order to effectively utilize the energy of the CO gas, H2 gas, etc., oxygen gas is blown in as shown by arrow 8.

In some cases, a so-called post-compassion process is performed to raise the temperature of the iron bath. When the post-compassion treatment is performed, the CO gas and H2 gas become CO2 and H20 gases, and although these gases have lost their reducing ability, they are at high temperature and rich in thermal energy. Thereupon, these are guided to the reformer 9 as indicated by arrow 4, reformed by contact with hydrocarbons and carbon to recover the reducing ability, and then recycled to the preliminary reduction furnace 1 (arrow 10).

By the way, the technology related to the above-mentioned reforming method is disclosed in Japanese Patent Application Laid-open No. 59
-222508 can be mentioned. That is, in the disclosed method, fossil fuels (coal, hydrocarbons, etc., hereinafter referred to as CH
4) is introduced and reacted as described in (1) and (2) below, thereby lowering the temperature of the Co2 gas etc. (about 850°C) and increasing the reduction potential. It is intended to be a quality gas.

CO2+ Cl14 =2GO+2)12-5'1lG
OKcafL/kg ・moJZe++20 +C)1
4 = CD + 3112 (2) The reformed gas reformed through such a process is led to the preliminary reduction furnace 1 (arrow 10) as described above, and is used as the preliminary reduction gas as described above.

[Problems to be Solved by the Invention] Since the above-mentioned reforming reactions [namely, the reactions (1) and (2)] are both endothermic reactions, the temperature of the reformer reaction system decreases as the above-mentioned reforming reactions progress. do.

On the other hand, since it is known that the pre-reduction reaction proceeds advantageously at about 850° C., the temperature reduction accompanying the endothermic reaction is itself favorable for the pre-reduction reaction. However, it has been found that the low temperature, which is preferable for the pre-reduction reaction, has a negative effect on the LiFohman reaction. That is, the reforming reaction in the reformer reaction system becomes significantly slow from around 950°C, and at around 900°C.
When the temperature drops below ℃, it almost stops. This means that
This means that an increase in reduction potential cannot be expected at temperatures below 900°C.

Therefore, if we mainly consider the progress of the reforming reaction, we cannot expect much from the temperature drop, but on the other hand, if we mainly consider the temperature drop, the progress of the reforming reaction will be insufficient. The reality is that the Reformer 9 has not been able to fully achieve its intended purpose. To make this point clearer, we set the inlet temperature of the reformer (temperature of the high-temperature generated gas) to 1600°C, the outlet temperature of the reformer (gas temperature after reforming) to 850°C, and the temperature of the CH4 gas for reforming. are fixed at room temperature, and the composition of the gas introduced into the reformer (high temperature generated gas) [(CO2 + 1120) / (
CO2+ 820 +GO+ H2)] (if necessary, the introduced gas and CH4
The reforming reaction was forced by changing the amount of gas, and it was investigated how the degree of oxidation changes between the reformer population side and the outlet side. The results are shown in Figure 3, where there is almost complete unity between the inlet side oxidation degree (η1) and the outlet side oxidation degree (η2).
A functional relationship was observed. The slope of this linear function can be read from the graph as being approximately equal, and it was found that the higher the degree of oxidation, the more difficult it is to obtain a gas correction of 1τ due to the temperature drop.

In the end, it has not been possible in the prior art to simultaneously improve the reduction potential through the progress of reforming and adjust the temperature to the optimum temperature after reforming.

The present invention has been made in consideration of these circumstances, and is capable of lowering the high-temperature generated gas subjected to potato compaction in the smelting reduction furnace to the optimum temperature for the progress of the preliminary reduction reaction, and simultaneously increasing the reduction potential. The purpose of this paper is to provide a quality adjustment method that can improve

[Means for solving the problem] The quality adjustment method of gas generated by a smelting reduction furnace according to the present invention is as follows:
This is a method of reforming high-temperature generated gas that is secondary-combusted in a smelting reduction furnace during the implementation of the smelting reduction ironmaking process into a gas suitable for preliminary reduction, in which the gas obtained by thermal decomposition of hydrocarbons is The gist of this is that by adding it to the generated gas, the gas is reformed to a temperature and reducing power suitable for introduction into the preliminary reduction furnace.

[Function] The greatest feature of the present invention is that the CH4 is not directly guided to the reformer at room temperature, but is guided to the reformer in a thermally decomposed state as shown in Fig. 1. . When CH4 gas is introduced into the heating device 12, CH4 undergoes a decomposition reaction as shown in (3) below.

[:)14-C+2H2-17780kcaJ2/kg
-moJ2e (3) Since this reaction is an endothermic reaction, there is a concern that the temperature of the gas introduced into the reformer will drop, but since there is also heat input for thermal decomposition, the heating temperature in the heating device 12 is adjusted. By doing so, the above concerns can be easily resolved. In this way, high-temperature C and H2 generated by the above reaction (3) are delivered to the reformer-9.
In addition, unreacted CH4 will be introduced. By this temperature adjustment, the reforming reactions (1) and (2) described above proceed smoothly in the refformer 9, and therefore the refformer 9
From 9 onwards, the co and H2 produced as a result of the progress of the reforming reactions in (1) and (2) above are combined with the C, H2, etc. produced in the above (3), and a reformed gas with an extremely high reduction potential is discharged. It will be done. The above actions and effects are C
The same applies not only to the thermal decomposition of H4 but also to the thermal decomposition of hydrocarbon gases such as c2H5.

[Example] Decomposition gas discharged from the thermal decomposition device 12 ((3) above)
C, H2゜ and unreacted CH produced by the reaction of formula
The thermal decomposition device 12 was controlled so that the temperature T of the mixed gas (e.g. No. 4) was 1.000° C. or higher. Then, the decomposed gas was guided to the reformer 9, and on the other hand, Co2, H20, etc. after post-passion were guided to the reformer 9. Next, the cracked gas temperature T was determined such that the degree of oxidation η1 on the artificial side to the reformer 9 such as Co2 and )(20) was set to 0 at the outlet.The results are shown in FIG. It can be seen that even with a low-reducing substance with a temperature of 40%, the exit side oxidation η2 could be reduced to 0 by adjusting the cracked gas temperature to around 1150°C. If a relational expression as shown in FIG. 3 is obtained in advance according to an arbitrary oxidation degree η2 value, it is possible to know the hydrocarbon pyrolysis gas temperature T for obtaining the above-mentioned arbitrary oxidation degree η2.Alternatively, If you set not only the inlet temperature of the reformer at 1600°C and the outlet temperature at 850°C but also any temperature and obtain the same relationship as shown in Fig. 3 above, the reformer outlet temperature can be determined by the inlet temperature and the cracked gas temperature T. It is also possible to regulate the degree of oxidation (corresponding to the reciprocal of the reduction potential) of the gas introduced into the preliminary reduction furnace.
This means that the temperature can be controlled freely.

[Effects of the Invention] Since the present invention is constructed as described above, the following excellent effects are exhibited.

(1) The temperature and reduction potential of the post-compassioned high-temperature generated gas can be optimized for the progress of the preliminary reduction reaction.

(2) It is possible to improve the efficiency of the pre-reduction reaction, which in turn can contribute to increasing the efficiency of smelting reduction iron manufacturing and lowering production costs.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram for showing one embodiment of the method of the present invention, Fig. 2
The figure is an explanatory diagram to show the conventional glue former method, and Figure 3 shows the oxidation degree η1 of the reformer artificial gas and the oxidation degree η of the outlet gas when the conventional glue former method is implemented.
FIG. 4 is a diagram showing the relationship between the inlet oxidation degree η1 of the reformer gas and the cracked gas temperature when the method of the present invention is implemented.

Claims (1)

[Claims] This is a method of reforming high-temperature generated gas that is secondary-combusted in a smelting reduction furnace during the implementation of the smelting reduction ironmaking process into a gas suitable for preliminary reduction, in which the gas obtained by thermal decomposition of hydrocarbons is A method for adjusting the quality of gas generated from a smelting reduction furnace, characterized in that the gas is reformed to a temperature and reducing power suitable for introduction into a pre-reduction furnace by adding the gas to the gas generated from a smelting reduction furnace.