JPH03241286A - Method and apparatus for melting cold iron material by burner - Google Patents

Abstract

PURPOSE:To eliminate the imbalance of a melting speed, by a method wherein both a fuel and an oxidiging agent are ejected from burners provided at the lower part of a furnace, at a speed of not more than 50m/s and not less than 10m/s, and with the specified relative speed difference between the fuel and the oxidizing agent, and the fuel is burned. CONSTITUTION:A melting furnace 1 is a vertical type circular furnace, and at the lower part thereof, two burners 2 are located in tangential direction to the wall of the furnace, and each of the burners 2 is formed so that a fuel is ejected from the central part of the burner and an oxidizing agent is whirled by a swirler and ejected from the peripheral part thereof. Both the fuel and the oxidizing agent are ejected from the burner 2, at a speed of not more than 50m/s and not less than 10m/s, and with the relative speed difference of 10m/s or higher, between the fuel and the oxidizing agent, and melt scrap and/or cold pig iron. In this way, the whole of the melted zone in the furnace becomes at a high temperature, and a melting speed stable can be obtained, and the yield rate of the scrap and/or cold pig iron is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method and apparatus for melting a cold iron source using a burner for melting iron sources such as scrap and cold pig iron into hot metal.

(Prior Art) As a method for producing hot metal by melting scrap, cold pig iron, etc., a method using a cupola or an electric furnace is generally used. However, in recent years, in order to reduce melting costs, melting methods using low-grade fuels such as natural gas are being implemented. As an example of this dissolution method, German patent D E3743
745, DE3733349 has been proposed. These proposals are a method in which a natural gas burner 22 is installed at the bottom of a melting furnace 21 shown in FIG. 4, and scrap 23 filled in the furnace is melted by combustion heat of the burner. In this method, the individual burners 22 are arranged toward the center of the furnace as shown in FIG. 5, and wide burners 22 are arranged as shown in FIG.
A large number of them are placed around the circumference of the furnace wall.

(Problems to be Solved by the Invention) In the burner arrangement state of the proposed melting method, the flame is injected toward the center of the furnace, so as shown in FIG. The temperature at the center of the furnace is relatively low, causing an imbalance in the melting rate of the cold iron source, making it difficult to smoothly melt and tap the cold iron source. Therefore, we have proposed a wide burner 22 as shown in Figure 6, but this still requires a large number of burners to cover the entire circumference of the furnace wall, and it does not solve the problem of temperature drop in the center of the furnace. It has not been.

(Means for Solving the Problems) Therefore, the present inventors have proposed a method and apparatus for efficiently heating and melting a cold iron source by raising the entire melting zone to a high temperature. The first invention is a vertical melting furnace in which fuel and an oxidizer are supplied from a burner provided at the lower part of the furnace at a speed of 10 m/s or more at 50 m/s or more.
m/s or less, and the relative velocity difference between the fuel and oxidizer is 10
This is a method of melting a cold iron source using a burner that burns fuel by injecting it at m/s or higher and then melts scrap and/or cold pig iron.

The second invention is a vertical melting furnace in which a cold iron source is melted by a burner that injects fuel from the center of the burner and injects an oxidizer from the outer periphery of the burner, which is arranged tangentially to the wall of the melting furnace. It is a device.

(effect) Hereinafter, the effects of the present invention will be explained.

First, the reason for limiting the injection speed of fuel and oxidizer will be explained.

If the fuel and oxidizer injection speed is less than 10 m/s, it will be difficult to form a stable flame, especially in the presence of a charge; if it exceeds 50 m/s, the combustion noise will be 85 dB (A ), which is not favorable for operation. Therefore, the injection speed of the fuel and oxidizer is limited to >0m/s and ~50m/s.

Furthermore, in order to form a stable flame, the relative speed difference between the fuel and the oxidizer needs to be 1Om/s or more.

However, the relative speed is the injection speed of the oxidizer.

Next, the reason for limiting the burner arrangement will be explained.

The reason for arranging the burners tangentially to the furnace wall is that by arranging the burners tangentially to the furnace wall, the flames can fully reach the furnace wall, and the center of the furnace can also be burned at high temperatures. This is because the exhaust gas is heated to a high temperature by the upward flow caused by the swirling flow.

(Example) Examples of the present invention will be described below.

FIG. 1 schematically shows a melting furnace according to the present invention. 1 in the diagram
2 is a melting furnace, 2 is a burner, 3 is cold pig iron, 4 is coke, 5 is a component regulator, 6 is a skimmer, and 7 is a tap port. The melting furnace 1 is a vertical circular furnace, and two burners 2 are installed in the lower part of the furnace in a tangential direction to the furnace wall. As described above, the burner 2 has a structure in which the fuel is injected from the center, and the oxidizer is injected from the outer periphery while being swirled by a swirler having a swirling angle of 30 degrees. There is a hot water tap lower at the bottom of the furnace for hot water tap. A skimmer 6 is provided to separate the slag and the slag.

During melting, a total of 35Nm of natural gas was used as fuel.
'/hr, pressure 4000mm1 (,0, injection speed 20m
/S, and the oxidizing agent was a mixture of air and oxygen with an oxygen concentration of 44% at an injection speed of 30 m/S, and the air ratio was 1.
．． It was burned under 0 conditions. Thereafter, in order to maintain the air permeability of the burner flame, coke 4 and component regulators (CaO, fluorspar, etc.) 5 were charged into the lowest layer of the furnace, and then 950 kg of cold pig iron 3 was charged.

The burner burns stably even after the raw materials are charged, and because the burner is arranged tangentially, the flame spreads even near the furnace wall, and the center of the furnace is also affected by the upward flow caused by the swirling flow of high-temperature combustion exhaust gas. The temperature was high enough to uniformly melt the cold pig iron. The hot metal descended through the coke layer, passed through 6 skimmers, and was stably discharged from the tap lower at a melting rate of 12 kg/11 inch.

Although natural gas was used as the fuel in the embodiment, it is also possible to use gaseous fuel such as coke oven gas, liquid fuel such as heavy oil, or solid fuel such as coal. Also, the oxidizing agent is oxygen or air or a mixture thereof.

Next, Modified Embodiment 1 to explain a modified embodiment of the present invention In the above embodiment, two burners were arranged in the tangential direction, but depending on the size of the furnace, multiple burners may be arranged as shown in FIG. May be placed. Even in this case, the number of burners can be reduced compared to the conventional technology Modification Embodiment 2 In the melting method according to the present invention, coke is charged in the lowest layer of the furnace, so unburned CO1H2 gas etc. are generated in the upper part of the furnace. A secondary air blowing port 8 as shown in FIG. 3 is provided in the furnace wall at the upper part of the furnace to blow air to completely burn the unburned gas and preheat the charged cold iron source.

(Effects of the Invention) As explained above, the present invention can cover the entire area around the furnace wall with flame, and since an upward flow of high-temperature combustion exhaust gas is formed in the center of the furnace, the entire melting zone in the furnace can be covered with flame. Since the temperature can be high, a stable dissolution rate can be obtained and the yield can also be improved. Furthermore, since the injection speeds of the fuel and oxidizer are limited, a stable flame can be maintained and combustion noise can be reduced.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic diagram of a melting furnace according to the present invention. FIG. 2 is a schematic diagram showing a modified example of the burner arrangement, and FIG. 3 is a schematic diagram showing a modified example of the melting furnace. FIG. 4 is a diagram showing a schematic diagram of a conventional melting furnace. FIG. 5 is a schematic diagram showing the burner arrangement and flame situation of the prior art. FIG. 6 is a diagram showing the appearance of a conventional burner. 1-melting furnace, 2-burner, 3-cold pig iron, 4-coke, 5
- Component regulator, 6 - Skinmer, 7 - Tap hole, 8 - Secondary air blowing port, 21 - Melting furnace, 22 Burner, 23 - Scrap, 24 - Flame, 25 - Furnace wall portion not exposed to flame.

Claims (2)

[Claims] (1) In a vertical melting furnace, fuel and oxidizer are injected from a burner installed at the bottom of the furnace at a speed of 10 m/s or more and 50 m/s or less, and a relative velocity difference between the fuel and oxidizer of 10 m/s or more. A method for melting a source of cold iron using a burner, characterized in that scrap and/or cold pig iron are melted by burning fuel using a burner. (2) Cold iron using a burner in a vertical melting furnace, characterized in that the burner injects fuel from the center of the burner and the oxidizer from the outer periphery is arranged tangentially to the furnace wall of the melting furnace. source melting equipment.