JPS61147821A - Melting method of scrap, or the like - Google Patents

Abstract

PURPOSE:To utilize effectively sensible and latent heats of exhausted gas, by melting raw material by combustible gas generating reaction between carbon material and O2 containing gas, using the high temp. combustible gas to preheating of raw material, then burning said gas to melt the other raw material. CONSTITUTION:Carbon material is blown together with air into the first melting furnace 4 in which initial stage molten steel is formed by arc heating, combustible gas is generated by exothermic reaction, and charged material is melted by the generated high temp. heat. Thereat, arc heat is used only at initial molten steel formation stage. Generated high temp. combustible gas is introduced into a raw material preheater 5, precharged material scrap, etc., is preheated to about 500-800 deg.C, and charged into the furnace 4. Combustible gas after sensible heat recovery exhausted from the preheater 5 is compressed by a compressor 15, introduced to a combustion chamber 6 and burned. About 1,000-1,200 deg.C generated high temp. gas is introduced to the second melting furnace 7, precharged material, etc., is melted, generated molten steel is tapped out into a ladle 20, and a part thereof is introduced to the furnace 4 as initial molten steel.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for melting scrap, etc., and in particular, to a method for melting scrap, etc., which can achieve power saving and effective use of overt and latent heat of exhaust gas. Concerning a method of dissolving.

[Prior Art] Generally, a three-phase arc furnace that utilizes the arc heat of three-phase electrodes is already known as a device for melting solid iron such as scrap for reuse.

In this arc furnace, raw material scraps are placed in the arc furnace main body which is open at the top, a three-phase electrode is inserted into this, the top lid is placed on the top lid, and the raw material is melted by the arc heat. It is something.

The exhaust gas generated from the arc furnace body is mainly composed of air that has entered the furnace from the surrounding area, but it also contains some combustible components such as CO, so the exhaust gas is taken out from inside the furnace and burned. This combustion gas is used to preheat the raw material scrap to make effective use of heat.

[Problems to be solved by the invention] By the way, when melting raw materials such as scrap using arc heat as in the conventional melting method, a large amount of electricity is required, especially in countries like Japan where electricity costs are high. has been forced to increase operating costs.

In addition, although heat recovery is performed using the sensible heat of exhaust gas, the amount of combustible content in the exhaust gas components is small, so the exhaust gas temperature after burning this trace amount of combustible gas does not rise that much and is sufficient. Preheating was not possible.

Further, the exhaust gas introduced into the preheater still contains a large amount of oxygen as described above, which causes a decrease in yield due to oxidation of raw materials such as scrap in the preheater.

In particular, in today's world where scrap consumption m is expected to increase significantly in the future, an early solution to the above-mentioned problems is desired.

[Object of the Invention] The present invention focuses on the above-mentioned problems and has been devised to effectively solve the problems.

The purpose of the present invention is to recover sensible heat by first preheating the raw material using high-temperature combustible gas generated during melting by blowing carbonaceous materials, and then to burn the combustible gas to obtain high-temperature heat. To provide a method for melting scrap, etc., which can greatly reduce power consumption by melting other raw material scrap with gas and recovering latent heat.

[Summary of the Invention] The configuration of the present invention that achieves the above object is to melt raw materials using the heat of reaction by blowing carbonaceous materials together with oxygen into the furnace, and preheat the raw materials with the obtained high-temperature combustible gas. This combustible gas is burned to recover sensible heat, and the high temperature exhaust gas obtained by burning this combustible gas is used to melt other raw materials and recover latent heat.
The main point is that this significantly reduces power consumption.

[Example] The method of the present invention will be explained in detail below based on the accompanying drawings.

FIG. 1 is a block diagram for explaining the outline of the method of the present invention, and FIG. 2 is a plan view showing an example of equipment for melting scrap, etc., for explaining a specific embodiment of the method of the present invention.

As shown in the figure, the method of the present invention includes a raw material melting/high temperature combustible gas generation step 1, an obvious recovery step 2, and a latent heat recovery step 3.
It is mainly composed of. In the raw material melting/high temperature combustible gas generation step 1, carbonaceous material is blown into the melting furnace together with oxygen or air to cause a reaction to generate combustible gas such as C01112, and at the same time, the raw material is melted by the heat of this reaction. Then, in the sensible heat recovery process 2, the raw material such as scrap charged into the raw material preheater is heated by the high temperature combustible gas discharged from the above process to recover sensible heat, and then the latent heat recovery process 3 In this method, the combustible gas after sensible heat recovery is combusted, other raw materials are melted by this high-temperature exhaust gas, and latent heat is recovered.

This method will be specifically explained in detail based on FIG.

In the figure, 4 is the first melting furnace, 5 is the raw material preheater, 6 is the combustion chamber,
7 each indicate a second melting furnace.

First, starting with raw material melting/high-temperature combustible gas generation step 1, carbonaceous materials such as pulverized coal, char, coke, etc. are blown into the first melting furnace 4 through a nozzle 8 provided at the lower part thereof together with oxygen or air. In this melting furnace 4, initial molten steel is formed by arc heating or by leaving a small amount of molten steel produced in the previous step. The injected oxygen causes an exothermic reaction with carbon contained in the charged raw material, such as carbon in injected carbonaceous materials or pig iron, and generates combustible gases such as Co, H2, and hydrocarbons. The charged raw material is melted by the high heat generated at this time, so arc heating is used only during initial molten steel production and is not used at all thereafter.

After the generated high-temperature combustible gas is discharged from the exhaust port 9, it is introduced into the raw material preheater 5 through the passage 10, and moves to the explicit recovery step 2. That is, raw material scrap and the like are charged in advance into the raw material preheater 5, and by passing high-temperature combustible gas therethrough, the raw material is preheated to a predetermined temperature and the sensible heat of the high-temperature gas is recovered.

In addition, in this raw material preheater 5, the charged raw material is
It is desirable to preheat the raw material to about 800 degrees, and this preheated raw material is charged into the first melting furnace 4.

The relatively low-temperature combustible gas discharged from the exhaust port 11 of the raw material preheater 5 after being overtly recovered is introduced into the cyclone 13 via the passage 12, where suspended matter in the gas is removed, and then further It is pressurized by the compressor 15 through the passage 14 and introduced into the combustion chamber 6, and then moves to the latent heat recovery step 3. Combustion air or oxygen is supplied into this combustion chamber 6, and the low-temperature combustible gas introduced therein is combusted, and the generated high-temperature gas of about 1000 to 1200 degrees is sent into the second melting furnace 7. Introduce. Raw material scraps and the like are charged in advance into the second melting furnace 7, and the raw materials are melted by the introduced high-temperature gas. In addition, as the second melting furnace,
It is desirable to use a shaft-type melting furnace that can most effectively recover heat from high-temperature gas.

In addition, if the amount of heat is insufficient with the high-temperature gas alone, additional auxiliary fuel is used.

Then, 6 is discharged from the exhaust port 16 of the second melting furnace 7.
The exhaust gas having a temperature of about 0.000 to 900° is introduced into the air preheater 18 through the passage 17 to heat the combustion air introduced into the combustion chamber 6.

On the other hand, the molten steel produced in the second melting furnace 7 is taken out from the take-out nozzle 19 to the takeout w420 and made into a product as it is, or a part is introduced into the first melting furnace 4 and used as initial molten steel. be done. In this way, by using a part of the molten steel in the second melting furnace γ as the initial molten steel in the first melting furnace 4, arc heating for generating the initial molten steel is completely eliminated in the first melting furnace 4. It becomes possible to make it unnecessary.

As described above, in the method of the present invention, an exothermic reaction is caused between the carbonaceous material and oxygen in the first melting furnace 4, the raw material is melted by the heat of reaction, and the charged raw material is first melted with the obtained high temperature combustible gas. Sensible heat is recovered from the gas by preheating, and then the combustible gas that has become low temperature due to sensible recovery is combusted in the combustion chamber 6, and other raw materials are melted in the second melting furnace 7 using the obtained high temperature exhaust gas. Since the latent heat was recovered by
Electric power for melting raw materials can be completely eliminated, or even if arc heating is used, initial molten steel is only generated in the first melting furnace 4, so power consumption can be significantly reduced.

In addition, the high temperature gas introduced into the raw material preheater 5 is C0,1
Because of the reducing gas such as No. 2, the inside of the preheater is not oxidized and corroded, and its service life can be extended.

[Effects of the Invention] In summary, the method of the present invention can exhibit the following excellent effects.

7(1) Since the raw material is melted in the first melting furnace using the oxygen force and the reaction heat generated when the carbonaceous material undergoes a reaction to generate combustible gas, power consumption can be completely eliminated. Alternatively, only a small amount of electric power is required at the time of initial molten steel generation, making it possible to significantly reduce electric power consumption.

(2) Furthermore, since the charged raw material is heated by the generated combustible gas and then other raw materials are melted by this combustion exhaust gas, the manifest and latent heat of the combustible gas can be effectively recovered.

(3) Also, the high temperature gas introduced into the raw material preheater is C
Since it is a reducing gas such as O2H2, it does not oxidize the scrap in the preheater and improves the yield.

(4) The gas for preheating the charged raw material is the exhaust gas discharged from the first melting furnace, and since the temperature is not high enough to melt the raw material, a conventional preheater can be used.

[Brief explanation of drawings]

FIG. 1 is a block diagram for explaining the outline of the method of the present invention, and FIG. 2 is a plan view showing an example of equipment for melting scrap, etc., for explaining a specific embodiment of the method of the present invention. In the figure, 4 is a first melting furnace, 5 is a raw material preheater, 6 is a combustion chamber, and 7 is a second melting furnace.

Claims (1)

[Claims] When melting raw materials such as scrap, carbonaceous materials undergo a combustible gas generation reaction in the presence of oxygen-containing gas, the raw material is melted by the heat of this reaction, and the raw material before melting is preheated using the resulting high-temperature combustible gas. A method for melting scrap, etc., characterized in that heat is recovered, and then other raw materials are melted by the high temperature exhaust gas generated by burning the combustible gas after sensible heat recovery.