JPS60187333A - Process and apparatus for reducing material to be heated by heating in reducing atmosphere - Google Patents

Abstract

PURPOSE:To obtain a simple and widely applicable heat-reducing process in a reducing atmosphere by shielding a material to be heated with a curtain of a laminary flowing reducing gas in a furnace and transmitting heat generated at the outside of the curtain to the material to be heated through the curtain. CONSTITUTION:The reducing gas supplied from a nozzle 11 is ejected in the form of horizontal flow like a curtain from a slit 3 through a gas storage 2. The gas flows above a pit 1 contg. the material to be heated, enters a space before a counter wall 6, and passes through the space toward above. On one hand, oxygen or a previously prepd. combustion gaseous mixture comprising O2 and fuel gas is supplied from a burner port 4 to burn the reducing gas in the furnace 5, and the material to be heated in the pit 1 is heated by the generated radiant heat. By this apparatus, smelting of metal, production of nonoxide raw material, or heat-reduction of a material in a reducing atmosphere suited to heat treatment of a metal is achieved without resulting generation of a large amt. of slug or CO, nor consumption of a large amt. of electric energy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for thermally reducing a material to be heated in a reducing atmosphere for reducing an oxide-based raw material, and an apparatus for thermally reducing the same.

[Prior art]

Conventionally, reduction of oxide-based raw materials has been carried out using unique methods and equipment developed depending on the type of target substance.

However, when looking at the energy and materials consumed, the emissions produced by-products, and the costs of production equipment, it is difficult to say that conventional methods are necessarily optimal; in fact, many of them rely on too individual measures. Therefore, there was a problem in that the operating conditions were complicated or the energy consumption was increased.

[Purpose of the invention]

Therefore, the present invention solves the above-mentioned conventional problems and provides a simple and versatile thermal reduction method in a reducing atmosphere, which is suitable for metal smelting and production of carbide materials by reducing raw material oxides. and thermal reduction equipment, specifically, metal smelting and non-oxide materials that do not emit large amounts of slag, generate carbon monoxide, or consume large amounts of electricity. The purpose of this invention is to provide a method and apparatus for thermal reduction of a heated object in a reducing atmosphere suitable for manufacturing, heat treatment of metals, etc.

[Structure of the invention]

In order to achieve the above object, the present invention provides a novel and versatile thermal reduction method under a reducing atmosphere that sequentially and fully utilizes the reducing gas and combustion energy of the fuel gas in one furnace. This is what we discovered.

That is, in the furnace, the object to be heated is shielded by a curtain of reducing gas flowing in a layered manner, and the heat generated outside the curtain is transmitted to the object to be heated through the curtain. , the preheated reducing gas is introduced into the furnace as a horizontal curtain-like gas flow, and after passing this curtain-like gas flow so as to cover the top surface of the object to be heated, it is guided into the upper part of the furnace. This is a heating reduction method in which the thermal energy generated by the combustion is transmitted mainly in the form of radiant heat through a curtain-shaped gas flow to the heated object.

Therefore, in the thermal reduction equipment that implements this, the furnace space is basically divided into a reducing atmosphere chamber and a combustion chamber, which are partitioned by a curtain flow of reducing gas. A slit for the introduction of reactive gases, a guide mechanism for guiding the curtain flow into the combustion chamber, a supply port for oxygen or air for the combustion chamber and auxiliary fuel if necessary, an outlet for the combustion exhaust gas, and a reducing atmosphere for the heated object. It is constructed by being equipped with a loading and unloading mechanism for supplying the tank to the chamber and taking it out from there after heat treatment.

Further, the reducing gas used in the present invention may be -carbon oxide, hydrogen, hydrocarbon, or a mixed gas thereof, and the heat target may include an oxygen-containing substance,
Alternatively, it may be a mixture of an oxygen-containing substance and a carbon-containing substance.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a side sectional view of the burner port 1 portion of the experimental furnace used for heating the reducing atmosphere according to the present invention, and FIG. 2 is the same as that of FIG. FIG. 2 is a top cross-sectional view of the experimental reactor.

In Fig. 1, the reducing gas supplied from the nozzle 11 provided on the left side wall passes through the gas reservoir 2 and is ejected from the slit 3 as a horizontal curtain flow, runs over the pit 1 containing the object to be heated, and runs over the opposite wall. Enter the duct A and pass upward.

On the other hand, oxygen or
A pre-mixed combustion gas of oxygen and fuel gas is supplied to burn the reducing gas in the furnace 5, and the object to be heated in the pit 1 is heated with the generated radiant heat.

Here, zirconia refractories are used as the furnace material, and the gas reservoir 2
The width and height of the inside of the furnace excluding the members of the slit 6, the pit 1, and the opposing wall are both 15 CIIL.

The slit 3 has a height of 0.2 crfL and a width of 4 CTL, and according to actual measurements, the flow rate required for the ejected gas flow to form a curtain flow up to the duct 6 is at least about 2.5 g/s.
It is ec.

FIG. 2 is a cross-sectional view of the furnace. Combustion gas in the furnace 5 passes through a passage 8 provided in a partition wall 7 in the center of the furnace and is exhausted from a flue 9 in the ceiling. 5. Observe the combustion state and measure the temperature using a high-temperature thermometer.

The experimental furnace shown in FIGS. 1 and 2 above has the same configuration and function as the thermal reduction apparatus to which the thermal reduction method according to the present invention is applied, and therefore, the shape and position of the slit A are set appropriately. Then, the gas jetted from there may be formed not only horizontally, but also in a fan-shaped, sloping, or vertical curtain flow.

However, how far this curtain flow extends depends mainly on the linear velocity of the gas jet flow from the slit 3.

Further, the temperature rise of the heated object placed in a reducing atmosphere due to the curtain flow is slowed down by the temperature of the gas ejected from the slit 3 as well as the combustion heat which depends on the amount of curtain gas.

Therefore, it is preferable to use a preheated reducing gas, and if the reducing gas is COO20, it is COO20 in a high temperature state generated by incomplete combustion of coal or coke, etc.
Direct use is preferable.

In addition, if it is difficult to cover the amount of heat necessary for processing the object to be heated by just burning the curtain flow, auxiliary fuel is separately supplied into the furnace 5 and burned so as not to disturb the curtain flow.

That is, the thermal reduction method of the present invention can be applied to various types of reducing heat treatments, and the object to be heated can be easily heated to a high temperature of 1500°C or higher in a reducing atmosphere.
If the pit 1 in the figure is made of graphite and granular iron oxide is supplied therein, a pure iron melt can be produced by heating at 1500°C or higher under a CO gas curtain without causing consumption of graphite due to oxidation.

In the current steelmaking process, iron ore and coke are charged into a blast furnace, which produces a large amount of slag and a large amount of blast furnace gas (CO).
However, in the method of the present invention, these by-products are not produced, iron oxide becomes metallic iron by CO reduction, and unconsumed CO is burned in the furnace 5 and becomes carbon dioxide gas. Just drain it.

As understood from this example, the present invention can be expected to be used in the smelting of various metals.

Further, although silicon carbide has conventionally been produced using a resistance electric furnace, it is also possible to produce silicon carbide if a stoichiometric mixture of silica and carbon is treated at a sufficiently high temperature by this method.

Next, in Experimental Example 1 showing the effect of gas curtain flow in the same thermal reduction device as in Figs. 1 and 2, pit 1
is made of graphite, and carbon monoxide is ejected from slit 3 at a rate of 5 m/s.
The gas is ejected at a flow rate of EC (gas consumption: 1.5 m8 Ar) to form a cascade flow.

On the other hand, when oxygen is sent from the burner port 4 and burned in the furnace 5, the curtain flow runs horizontally on the top surface of the pit 1,
The situation in which it passes through the duct 6 and burns inside the furnace 5 can be clearly observed.

Accelerate temperature rise; #[+, city gas (10'Kcaj?
/rfL8) was supplied to the pre-mix burner, and the amount and the required amount of oxygen were gradually increased, and the temperature inside the furnace reached 163.
When the temperature reaches 0°C (urban gas consumption at this time Q, 8
7718/'hr), the temperature inside the pit 1 (measured by thermocouple) was 1340°C, while the temperature of the curtain gas at the exit of the slit 6 was 550°C.

Therefore, it can be seen that even when covered with a low-temperature gas curtain, the inside of the pit 1 can be heated to a considerably high temperature by receiving radiant heat from the inside of the furnace 5.

Incidentally, when the combustion was stopped and argon gas was introduced through the slit 3 instead of COO20 to cool it under an inert gas, the graphite pit 1 did not show any wear due to oxidation and maintained its original shape.

However, when the same experiment was conducted using hydrogen gas or methane gas instead of -carbon oxide, it was confirmed that almost the same results were obtained.

Next, in order to explain the preheating effect of curtain gas and the reduction of iron oxide, a combustion experiment was conducted using the same equipment as in Example 1 under almost the same conditions except for the preheating of carbon monoxide.
I will explain about it.

For preheating, a Kanthal wire heating (2KW capacity) tubular preheater installed outside the furnace was used.

It was confirmed that as the temperature of the curtain gas at the exit of the slit 3 increased, the difference between the temperature inside the furnace 5 and the temperature inside the pit 1 decreased.

This effect becomes noticeable when the temperature of slit 3 exceeds approximately 900°C, and when the temperature inside the furnace 5 is 1700°C and the temperature W of slit 3 is 1150°C, the temperature inside pit 1 is 161°C.
It showed 0°C.

Preheating the curtain gas was thus confirmed to be extremely effective, and when granular iron oxide was placed in the graphite pit 1 in advance under these conditions, the pit 1 was not consumed at all after the experiment was completed. The pure iron produced by reduction was quantitatively recovered as a molten lump.

The experimental furnace according to the embodiment of the present invention shown in FIGS. 1 and 2 is a reducing method in which the object to be heated is placed in a reducing atmosphere by a curtain flow of reducing gas flowing in layers in the space inside the furnace 5. A slit 6 divides the reducing gas into a pit 1, which is an atmosphere chamber, and a combustion chamber, and sends the reducing gas introduced from the nozzle 11 from the gas reservoir 2 into the furnace 5 to form this curtain flow. A duct 6 which is a guide mechanism leading to the combustion chamber, a burner port 4 which is a supply port for introducing fuel gas such as oxygen or air or auxiliary fuel into the combustion chamber, a passage 8 which is an exhaust port for combustion exhaust gas, and smoke. The pipe 7 is further equipped with a loading and unloading mechanism for supplying the heated material (not shown) into the pit 1 and taking it out from there after heat treatment. It is not limited to experimental reactors, and devices with various shapes and configurations are possible.

〔Effect of the invention〕

Therefore, if the method for thermally reducing a heated object under a reducing atmosphere and the thermally reducing device thereof according to the present invention are adopted, by-products such as slag are not generated as in conventional methods, and power consumption is also reduced. There is.

Still, the reducing gas used in the present invention is - carbon oxide,
Hydrogen, hydrocarbons, or a mixture of these gases can be used, and these gases are completely combusted in the furnace and emitted as carbon dioxide gas or water vapor, so large amounts of carbon monoxide are not emitted as in the conventional blast furnace steelmaking process. Moreover, there is an advantage that the accompanying equipment for collecting and utilizing carbon monoxide can be omitted.

On the other hand, the material to be heated may be a raw material selected from a wide variety of materials, such as metals, oxides, and oxy-acid salts, depending on the purpose of heat treatment in a reducing atmosphere, and its form may be fixed or irregular. Regardless of whether it is a fixed shape, a solid or a liquid, a raw material or a mixture, such as a mixture of a metal oxide and carbon powder, we provide a versatile method and apparatus for heating and reducing the object under a reducing atmosphere. can be provided.

[Brief explanation of the drawing]

FIG. 1 is a side cross-sectional view of a burner port portion of a thermal reduction apparatus according to an embodiment of the present invention, and FIG. 2 is a top plan cross-sectional view of the apparatus shown in FIG. 1. 1... Pit, 2... Gas reservoir, 3... Slit, 4... Burner port, 5... Furnace interior, 6... Duct, 8 Figure 1 5

Claims (1)

[Claims] 1. In the furnace, the object to be heated is shielded by a curtain of reducing gas flowing in layers, and the heat generated outside the curtain is transmitted to the object to be heated through this curtain. A method for heating and reducing a heated object under a reducing atmosphere. 2. In the furnace, a curtain of reducing gas flowing in a layer that shields the object to be heated is passed through the furnace as a preheated horizontal gas stream so as to cover the top surface of the object to be heated, and then this A reducing atmosphere characterized in that a curtain-shaped gas flow is guided to the upper part of the furnace and combusted, and the thermal energy generated thereby is transmitted mainly in the form of radiant heat to the object to be heated through the curtain-shaped gas flow. A heating reduction method for heated objects. 3. In the furnace, the reducing gas flowing in a layered manner is exposed to a reducing atmosphere according to claims 1 and 2, in which the reducing gas is carbon monoxide, hydrogen, hydrocarbon, or a mixture thereof. Method for heating and reducing hot materials. 4. In the furnace, the object to be heated that is shielded by the reducing gas flowing in a layered manner is an oxygen-containing substance or a mixture of an oxygen-containing substance and a carbon-containing substance, or A method for heating and reducing a material to be heated in a reducing atmosphere according to item 3. 5. A slit for introducing reducing gas to form a curtain flow in the furnace, which is divided into a reducing atmosphere chamber and a combustion chamber by a curtain flow of reducing gas flowing in a layered manner in one furnace space, and a curtain flow. A guide mechanism for guiding the gas into the combustion chamber, a supply port for oxygen or air for the combustion chamber and, if necessary, an auxiliary fuel reservoir, a combustion exhaust gas discharge port, and for supplying the heated material to the reducing atmosphere chamber and removing it from there after heat treatment. import,
A heating reduction device for a heated object in a reducing atmosphere, characterized by being equipped with an ejection mechanism.