TW201915175A - Method for operating melting/refining furnace and melting/refining furnace - Google Patents

Abstract

It is an object to improve efficiency at the time of operation of a melting/refining furnace for a cold iron source using an oxygen burner lance, a method for operating a melting/refining furnace which has at least one through hole provided so as to penetrate a furnace wall and at least one burner provided in the through hole, and at least one lance provided in a combustion-supporting fluid supplying hole provided above the through hole for the burner, wherein an introduction amount of oxygen in a melting step is set in a range calculated using a volume of the furnace.

Description

 Melting, refining furnace operation method and melting, refining furnace  

The invention relates to a melting of a cold iron source by an oxygen burner and a spray gun, an operation method of the refining furnace, and a melting and refining furnace.

A burner system that combusts an oxygen-containing combustion-supporting fluid (oxygen, air, oxidizing air, etc.) with a fuel to heat the object to be heated is utilized in a wide variety of production processes. For example, in a steel making process in an electric furnace, when a raw material such as iron filings is heated and melted in an electric furnace, there is a low temperature portion where a so-called cold spot is generated in the raw material, and the raw material is in the portion. It is difficult to melt things. In this case, by using the burner disclosed in Patent Document 1, the heating efficiency of the raw material can be improved, the amount of electric power used for melting the raw material can be reduced, and the melting cost can be reduced.

Further, it is also possible to partially oxidize and melt a raw material by a combustion-supporting fluid to promote the cutting thereof, thereby further improving the heating efficiency of the raw material. Further, combustion of the unburned fluid (carbon monoxide or the like) can be promoted by the supply of the combustion-supporting fluid.

For example, Patent Document 2 discloses an invention in which oxygen is heated in advance to a high temperature in order to increase the heating efficiency in the secondary combustion by the combustion-supporting fluid.

 (previous technical literature)    (Patent Literature)  

Patent Document 1: Japanese Patent No. 4050195

Patent Document 2: Japanese Laid-Open Patent Publication No. 2000-337776

In such an operation, since the auxiliary melting of the raw material by the burner is aimed at reducing the melting cost, the consumption of the combustion-supporting fluid injected into the electric furnace is minimized, and it is also desired to suppress the raw material. Peroxidation to increase yield. The present invention has been made in view of the above circumstances, and its object is to improve the efficiency of melting of a cold iron source by a burner and a spray gun, operation of a refining furnace, or refining.

The melting and refining method of the present invention for solving the above problems is a method for melting and refining a cold iron source by an electric furnace, the method comprising: a melting step comprising: a first step of introducing cold from an upper portion of the electric furnace Iron source; in the second step, the electrode provided in the central portion of the electric furnace is energized to cause main cooling of the cold iron source; and in the third step, the cold iron source is assisted by a burner disposed on the furnace wall of the electric furnace And a fourth step of causing a combustion-supporting fluid (for example, oxygen or a combustion-supporting fluid containing at least oxygen) to be supplied from a lance provided in a combustion-supporting fluid discharge hole provided in the furnace wall above the burner Ejecting from below the horizontal direction, and reacting the combustion-supporting fluid with carbon monoxide, hydrogen, or a mixture of carbon monoxide and hydrogen generated during melting of the cold iron source; and a refining step of introducing oxygen to the foregoing The molten iron produced by the melting of the cold iron source removes impurities; the fourth step starts simultaneously with the beginning of the third step or immediately after the start of the third step and along with the refining step The beginning and end of the furnace to the volume V (m ³⁾ of oxygen to be introduced into Q (Nm ³ / h) is set in relation V / Q = the range of from 0.1 to 0.8.

Further, the melting and refining furnace of the present invention is a melting and refining furnace of a cold iron source, and is a furnace for carrying out the above-described melting refining method, wherein the furnace has an electric portion for introducing an opening of a cold iron source at an upper portion thereof. a furnace having: an electrode for melting a cold iron source at a central portion thereof; a burner for assisting melting of a cold iron source at a furnace wall; wherein the furnace wall is higher than the burner a position of a spray gun for introducing oxygen; and an oxygen flow rate adjusting mechanism for supplying a certain amount of oxygen to the spray gun; and the installation position of the burner and the spray gun mounted on the furnace wall satisfies the following conditions: The distance L ₁ from the molten metal surface to the front end of the burner is the distance L ₂ from the molten metal surface to the front end of the lance; the angle between the central axis of the burner and the horizontal plane α ≧ the central axis of the lance and the horizontal plane The angle β; the angle between the central axis of the burner and the horizontal plane is α>0°; the angle between the central axis of the spray gun and the horizontal plane is β≧0°.

In the melting and refining furnace of the cold iron source, the oxygen flow rate adjusting mechanism includes a flow rate adjusting valve, a flow rate indicator, a pressure gauge, and a pressure regulating valve.

According to the present invention, when the cold iron source is melted by the burner and the spray gun, the operation or refining of the refining furnace is performed, a proper and correct amount of the combustion-supporting fluid can be injected into the furnace from an appropriate and correct position, and The consumption of the combustion-supporting fluid is set to the minimum required, so that the melting efficiency can also be improved.

1‧‧‧melting, refining furnace (electric furnace)

2‧‧‧ furnace body

2A‧‧‧ furnace wall

2B‧‧‧ bottom

3‧‧‧Cover

4‧‧‧Electrode

5‧‧‧burner (burner/gun)

5A‧‧‧through hole

6‧‧‧ spray gun

6A‧‧‧Combustible fluid supply hole

10‧‧‧pressure regulating valve

11‧‧‧ pressure gauge

12‧‧‧Flow indicator

13‧‧‧Flow regulating valve

18, 20‧‧‧Combustible fluid supply pipe

19‧‧‧Fuel fluid supply tube

21‧‧‧Reflow type water-cooled jacket

Fig. 1 is a schematic view showing the use of the melting and refining furnace of the present invention.

Fig. 2 is a schematic view showing a state in which the upper cover of the melting and refining furnace of the present invention is removed and introduced into a cold iron source.

Fig. 3 is a schematic view showing the arrangement of a burner and a spray gun installed on the wall of the electric furnace.

Figure 4 is a schematic view showing the configuration of the burner viewed from the upper portion of the electric furnace.

Fig. 5 is a schematic view showing a burner (burner/gun) having a spray gun function in the embodiment.

Figure 6 is a schematic illustration of the flow control mechanism for oxygen supplied from the lance to the furnace.

Fig. 7 is a graph showing the relationship between the amount of generation of carbon oxide and hydrogen in the exhaust gas from the melting and refining furnace and the furnace volume V ₁ / the introduced oxygen amount Q.

Fig. 8 is a graph showing the relationship between the amount of generation of carbon oxide and hydrogen in the exhaust gas from the melting and refining furnace and the furnace volume V ₂ / the introduced oxygen amount Q.

An embodiment of the present invention will be described. The melting and refining furnace using the cold iron source of the present invention is shown in Fig. 1. The melting and refining furnace 1 shown in Fig. 1 (hereinafter also referred to as an electric furnace) is an electric furnace having electrodes 4 at its center. The electric furnace 1 has a cylindrical furnace body 2, and has an opening at the upper portion thereof and a furnace cover 3 that closes the opening. A furnace bottom 2B is provided at the lower portion. Although the electrode 4 may be one or three depending on each furnace, in the present embodiment, the display electrode is one.

When the cold iron source is put into the electric furnace 1, for example, as shown in Fig. 2, after the electrode 4 is removed and the furnace cover 3 is removed, a cold iron source is introduced from the opening of the upper portion of the furnace body 2.

In the electric furnace 1, the through hole 5A is provided so as to penetrate the furnace wall 2A of the furnace body 2, and the burner 5 is provided in the through hole 5A. In the furnace wall 2A, which is higher than the through hole 5A, the combustion-supporting fluid supply hole 6A is provided so as to penetrate the furnace wall 2A. In the combustion-supporting fluid supply hole 6A, a spray gun 6 is provided to introduce a combustion-supporting fluid (oxygen or a combustion-supporting fluid containing at least oxygen) into the furnace. The burner 5 is inserted and fixed from the through hole 5A toward the hearth 2B, and the lance 6 is inserted and fixed from the combustion-supporting fluid supply hole 6A toward the hearth 2B.

Fig. 3 is a view showing the arrangement of the burner 5 and the lance 6 provided in the furnace wall 2A of the electric furnace 1. The installation position of the spray gun 6 provided on the furnace wall 2A is set to be higher than the burner 5. That is, when the height position of the burner 5 (distance between the burner front end portion and the molten metal surface) is L ₁ and the height position of the lance 6 (the distance between the tip end portion of the lance and the molten metal surface) is set to L ₂ The burner 5 and the lance 6 are provided so as to become L ₁ < L ₂ (the left diagram of Fig. 3). Here, the molten metal surface refers to the upper surface of the molten metal formed by the molten steel after the cold iron source is melted.

When the angle formed by the central axis of the burner 5 and the horizontal direction is α, the direction in which the burner 5 is disposed is fixed to 90°>α>0° (the right diagram in Fig. 3). More preferably, it is set to 60 ° < α < 45 °. Further, when the angle formed by the central axis of the lance 6 and the horizontal direction is β, the direction in which the lance is installed is fixed to α ≧ β ≧ 0° (the right diagram in Fig. 3). That is, the discharge direction of the combustion-supporting fluid from the lance 6 is set to be equal to or higher than the direction in which the flame generated by the burner 5 is formed. By setting the direction of the lance 6 as described above, the combustion-supporting gas from the lance 6 can be used to efficiently burn the unburned gas (mainly carbon monoxide or hydrogen) when the burner 5 is burned.

Fig. 4 is a view showing the configuration of the burner 5 as viewed from the upper portion of the electric furnace. Fig. 4 shows an example in which three burners 5 are provided. The flame forming direction of the burner 5 is directed toward a direction in which the vicinity of the central portion of the furnace wall 2A and the electrode 4 is heated, and the vicinity of the central portion of the furnace wall 2A and the electrode 4 belongs to the heating of the cold iron source by the electrode 4 in the furnace. Insufficient place. Further, in order not to cause damage to the electrode 4, the burner 5 is preferably disposed such that the flame does not directly contact the electrode 4.

A schematic cross-sectional view showing the configuration of the burner 5 in the present embodiment is shown in Fig. 5. The burner 5 described in Fig. 5 is a burner (burner/gun) having a spray gun function. In the center of the oxygen burner/lance 5 of the present embodiment, a combustion-supporting fluid supply pipe 18 for supplying a combustion-supporting fluid containing oxygen is provided, and a fuel fluid supply pipe 19 for supplying a fuel fluid is provided on the outer periphery thereof. The combustion-supporting fluid supply pipe 20 is provided concentrically on the outer circumference thereof. A reflux type water-cooling jacket 21 is provided on the outer circumference of the combustion-supporting fluid supply pipe 20.

Further, the flow-supporting fluid supply pipe 20 may be omitted, and the recirculating water-cooling jacket 21 may be provided outside the fuel fluid supply pipe 19, but in the case where the combustion-supporting fluid supply pipe 20 is provided, the combustion-supporting fluid may be adjusted. The oxygen flow ratio of the supply tubes 18, 20 is adjusted to adjust the flame length.

The combustion-supporting fluid supply pipe 18 is provided with a large-diameter portion 18a having a constant inner diameter from the proximal end side 18A to the distal end side 18B, and a throat portion 18b having an inner diameter smaller than the large-diameter portion 18a; the inner diameter is from the throat portion 18b toward The extension portion 18c whose front end side 18B is gradually enlarged; and the linear motion portion 18d having a substantially constant inner diameter.

As described above, in the upper portion of the furnace wall 2A in which the burner/lance (combustor 5) is provided in the present embodiment, a combustion-supporting fluid supply hole 6A for setting the oxygen for secondary combustion is provided. The combustion-supporting fluid is introduced into the lance 6 in the furnace.

Preferably, a recirculating water-cooling jacket is provided on the outer circumference of the combustion-supporting fluid supply hole 6A to which the combustion-supporting fluid containing oxygen is supplied. As long as a water-cooled jacket is provided around the lance 6, the refractory wall or the water-cooled wall can be set regardless of whether the furnace wall is.

Fig. 6 shows the configuration of an oxygen flow rate adjusting mechanism for supplying oxygen to the lance. The oxygen flow rate adjustment mechanism includes a pressure regulating valve 10, a pressure gauge 11, a flow rate indicator 12, and a flow rate adjusting valve 13 from the oxygen supply side.

A method of melting and refining a cold iron source by the melting and refining furnace 1 as described above is disclosed.

First, as shown in Fig. 2, a cold iron source is introduced from the upper opening of the furnace body 2 from which the electrode 4 and the furnace cover 3 have been removed (first step). Next, the electrode 4 is lowered to a predetermined position in the center portion of the melting and refining furnace 1, and the upper portion of the furnace body 2 is covered with the furnace cover 3. Then, the electrode 4 is energized to melt the cold iron source (second step).

After the melting of the cold iron source starts, and the molten metal starts to accumulate in the furnace bottom 2B, the cold iron source is assisted to be melted by a plurality of burners 5 disposed in the furnace wall 2A of the melting and refining furnace 1 (third step). .

Then, at the same time as the start of the third step or immediately after the start of the third step, oxygen is ejected from the lance 6 provided in the oxidizing fluid supply hole 6A provided in the furnace wall 2A, and the oxygen and the cold iron source are At the time of melting, one of carbon monoxide, hydrogen, or a mixture of carbon monoxide and hydrogen is generated to react (step 4).

The melting step is a step from the first step to the fourth step.

Here, the amount of oxygen supplied from the lance 6 in the fourth step can be determined by the volume of the melting and refining furnace 1. In other words, when the volume of the melting and refining furnace 1 is V (m ³ ), the introduction amount Q (Nm ³ /h) of oxygen in the fourth step is set to be in the range of V/Q = 0.1 to 0.8. . Here, the furnace volume V means the internal volume of the furnace body 2 before the cold iron source is supplied.

In the melting step, after the cold iron source is substantially melted and the molten molten steel is accumulated as molten metal in the furnace bottom, the fuel supply to the burner/gun (burner 5) is stopped and switched to the spray gun mode, and oxygen is introduced to The impurities are removed by melting the metal. This becomes the refining step.

 [Examples]  

In the melting and refining furnace in which the internal volume of the furnace body is V ₁ (m ³ ), the above-described melting step (first step to fourth step) is carried out. An exhaust gas analysis device and an exhaust gas flow rate measuring device (not shown) are provided in the exhaust gas outlet of the melting and refining furnace, and in the third step, when oxygen is introduced from the spray gun into the furnace The content of one of carbon monoxide (CO) and hydrogen (H ₂ ) in the exhaust gas was measured.

In the third step, the oxygen flow rate adjusting means changes the amount of oxygen Q (Nm ³ /h) introduced into the furnace from the lance 6, and measures the content of carbon monoxide and hydrogen in the exhaust gas from the melting and refining furnace. The result is shown in Fig. 7.

The horizontal axis of Fig. 7 is V ₁ /Q. The amount of carbon oxide and hydrogen (CO, H ₂ ) produced per ¹ t of iron obtained by melting the cold iron source is (Nm ³ /t).

When V ₁ /Q is from 0.1 to 0.8, it is confirmed that the amount of CO and H ₂ produced decreases as the amount of oxygen introduced increases. However, when V ₁ /Q becomes 0.8 or more, the concentrations of CO and H ₂ are hardly changed. That is, it was revealed that the amount of oxygen introduced was insufficient, and it was found that the secondary combustion was not sufficiently performed. Further, it was confirmed that, under 0.1 or less, even if the introduction amount of oxygen is increased, the amount of CO and H ₂ generated does not largely change.

The same test was carried out in a melting and refining furnace (the internal volume V _{2 of the} furnace body) different from the above. The results are shown in Figure 8. When V ₂ /Q is from 0.1 to 0.8, the effect of reducing carbon monoxide and hydrogen corresponding to the amount of oxygen introduced from the lance 6 can be observed. That is, an appropriate introduction amount of oxygen without waste is when V ₂ /Q is in the range of 0.1 to 0.8.

 (industrial availability)  

The melting method of the present invention, the method of operating the refining furnace, and the melting and refining furnaces have the possibility of utilizing the melting of the cold iron source in the electric furnace.

Claims (3)

A method for melting and refining a cold iron source, which is a method for melting and refining a cold iron source by using a melting and refining furnace, the method comprising: a melting step comprising: a first step of introducing cold from the upper portion of the melting and refining furnace In the second step, the electrode provided in the center of the melting and refining furnace is energized to cause main melting of the cold iron source; and in the third step, the burner is disposed in the furnace wall of the melting and refining furnace. And assisting the cold iron source to be melted; and in the fourth step, using the spray gun, the combustion-supporting fluid is sprayed out from the combustion chamber fluid disposed above the furnace wall to cause the combustion-supporting fluid to be ejected lower than the horizontal direction, and And reacting the combustion-supporting fluid with carbon monoxide, hydrogen, or a mixture of carbon monoxide and hydrogen generated during melting of the cold iron source; and a refining step of introducing oxygen into the melting by melting of the cold iron source Removing impurities from the ore; the aforementioned fourth step begins simultaneously with the beginning of the third step or immediately after the start of the third step, and ends with the beginning of the refining step, when When the volume of the furnace body of the furnace is V (m ³ ), the oxygen introduction amount Q (Nm ³ /h) when the combustion-supporting fluid in the fourth step is oxygen is set in the range of V/Q = 0.1 to 0.8. . A melting and refining furnace for a cold iron source, which is used for melting and refining a cold iron source, the furnace having an electric furnace for introducing an opening of a cold iron source at an upper portion, the electric furnace having: An electrode for melting a cold iron source at a central portion thereof; a burner for assisting melting of a cold iron source at a furnace wall thereof; and a spray gun for introducing oxygen to the upper portion of the furnace wall at a position higher than the burner And an oxygen flow rate adjusting mechanism for supplying a certain amount of oxygen to the spray gun; and the mounting position of the burner and the spray gun mounted on the furnace wall satisfies the following conditions: from a molten metal surface to a burner front end portion until the distance L ₁ <from the molten metal surface to the distance of the lance tip end portion L _2; the central axis of the horizontal burner of formed by the angle α ≧ central spray gun axis and a horizontal plane of an angle beta]; the center of the burner of the shaft The angle α with the horizontal plane is 90°>α>0°; the angle between the central axis of the spray gun and the horizontal plane is β≧0°.  The cold iron source melting and refining furnace according to claim 2, wherein the oxygen flow rate adjusting mechanism includes a flow rate adjusting valve, a flow rate indicator, a pressure gauge, and a pressure regulating valve.