KR20230163250A - Apparatus and method for preheating ladle using brown gas - Google Patents

Abstract

Provides a ladle preheating device and preheating method using Brown gas. The ladle preheating device includes: i) a body that forms an internal space, is open at both ends, and is supplied with air; ii) a pipe holder installed and sealed at the open first end of the body and passing through and fixing the Brown gas supply pipe and the natural gas supply pipe; iii) a first solenoid valve installed in the Brown gas supply pipe and operated to open and close; iv) a second solenoid valve installed in the natural gas supply pipe and operated to open and close; v) a distribution member connected to the open second end of the body and forming a plurality of air outlets through which air is discharged, a distribution outlet connected to the Brown gas supply pipe and a natural gas outlet connected to the natural gas supply pipe; and vi) a cover member coupled to the distribution member to form a Brown gas chamber connected to the distribution port between the distribution member and the cover member and a Brown gas discharge port connected to the Brown gas chamber, and through which a plurality of air outlets extend and penetrate to the inside of the ladle. Includes. The brown gas outlet and the natural gas outlet are connected at the bottom of the cover member, and a plurality of air outlets are spaced apart from each other to surround the brown gas outlet and the natural gas outlet.

Description

Ladle preheating device and preheating method using Brown gas {APPARATUS AND METHOD FOR PREHEATING LADLE USING BROWN GAS}

The present invention relates to a ladle preheating device and a preheating method, and more specifically, to a ladle preheating device and a preheating method that can prevent backfire when using Brown gas.

A ladle is a container that removes molten metal from a furnace and moves it to the next processing location. Since the top of the ladle is open, molten metal is supplied into the ladle through the top and stored. Before storing the molten metal in the ladle, it is necessary to improve the thermal insulation effect of the molten metal by the ladle by preheating the ladle to a preset temperature.

Meanwhile, Brown gas has high thermal efficiency. In addition, Brown gas consists only of hydrogen and oxygen, so no residues such as dust are generated during combustion. Therefore, Brown gas has the advantage of enabling environmentally friendly combustion. However, since the average and maximum explosion pressure increase rates of Brown gas are very high, it is necessary to prevent backfire due to high-temperature radiant heat.

The aim is to provide a ladle preheating device that can prevent backfire when using Brown gas. In addition, we would like to provide a ladle preheating method that can prevent backfire when using Brown gas.

A ladle preheating device according to an embodiment of the present invention includes: i) a body that forms an internal space, is open at both ends, and is supplied with air; ii) a pipe holder installed and sealed at the open first end of the body and passing through and fixing the Brown gas supply pipe and the natural gas supply pipe; iii) a first solenoid valve installed in the Brown gas supply pipe and operated to open and close; iv) a second solenoid valve installed in the natural gas supply pipe and operated to open and close; v) a distribution member connected to the open second end of the body and forming a plurality of air outlets through which air is discharged, a distribution outlet connected to the Brown gas supply pipe and a natural gas outlet connected to the natural gas supply pipe; vi) a cover member coupled to the distribution member and forming a Brown gas chamber connected to a distribution port between the distribution member and the cover member and a Brown gas discharge port connected to the Brown gas chamber, the plurality of air outlets extending through the cover member toward the inside of the ladle; vii) a first check valve installed in the Brown gas supply pipe inside the body, opened and operated at a first pressure, supplies Brown gas, and blocks backflow of Brown gas; viii) a Brown gas backfire discharge pipe connected to the Brown gas supply pipe between the first check valve and the distribution member and led to the outside of the body; ix) a first safety valve installed in the Brown gas backfire discharge pipe and operated to open at a second pressure greater than the first pressure to discharge backfire from the inside of the ladle during preheating inside the ladle; x) a second check valve installed in the natural gas supply pipe inside the body, opened and operated at a third pressure, supplies natural gas, and blocks the backflow of natural gas; xi) a natural gas backfire discharge pipe connected to the natural gas supply pipe between the second check valve and the distribution member and led to the outside of the body; and xii) a second safety valve installed in the natural gas flashback discharge pipe and operated to open at a fourth pressure greater than the third pressure to discharge the flashback. The brown gas outlet and the natural gas outlet are connected at the bottom of the cover member, and a plurality of air outlets are spaced apart from each other to surround the brown gas outlet and the natural gas outlet.

The natural gas outlet is provided at the center of the distribution member, and the Brown gas chamber is spaced apart from the natural gas outlet at a first gap (G1) and is formed in an annular shape with a first range (R1) in the radial direction, and the Brown gas outlet covers the It may surround the natural gas outlet while contacting the natural gas outlet at the bottom of the member. The Brown gas backfire discharge pipe includes a first discharge pipe and a second discharge pipe connected to the Brown gas supply pipe, and the first safety valve includes a first mechanical valve provided in the first discharge pipe and a second mechanical valve provided in the second discharge pipe. And, the natural gas backfire discharge pipe includes a third discharge pipe and a fourth discharge pipe connected to the natural gas supply pipe, and the second safety valve includes a third mechanical valve provided in the third discharge pipe and a fourth mechanical valve provided in the fourth discharge pipe. may include. The first discharge pipe is formed with a first diameter (D1) and is drawn out of the body at a first distance (L1), and the second discharge pipe is formed with a second diameter (D2) larger than the first diameter (D1) and extends to the outside of the body at a first distance (L1). It is drawn out of the body at a second distance (L2) larger than the distance (L1), and the third discharge pipe is formed with a third diameter (D3) and drawn out of the body at a third distance (L3), and the fourth discharge pipe is formed with a fourth diameter (D4) that is larger than the third diameter (D3) and can be drawn out of the body at a fourth distance (L4) that is larger than the third distance (L3).

The ladle preheating method according to an embodiment of the present invention uses the ladle preheating device described above. The ladle preheating method includes the following steps: i) arranging the ladle preheating device to face the inside of the ladle, ii) opening the first solenoid valve to supply Brown gas through the Brown gas supply pipe, and opening the second solenoid valve to supply natural gas through the brown gas supply pipe. supplying natural gas through, iii) supplying air for combustion through a plurality of air outlets, iv) co-firing the brown gas and natural gas at the bottom of the cover member to preheat the inside of the ladle with a flame from the co-firing. Step, v) When the brown gas backfires, the first check valve installed in the brown gas supply pipe and opened at the first pressure is closed by the backflow of the brown gas, thereby blocking the backflow of the brown gas, vi) the brown gas. When blocking the backflow, the first safety valve connected to the Brown gas backfire discharge pipe between the first check valve and the Brown gas discharge interval is opened and operated at a second pressure greater than the first pressure to discharge the backfire of the Brown gas, vii) When natural gas backfires, a second check valve installed in the natural gas supply pipe and opened at a third pressure is closed by the backflowing natural gas to block the backflow of natural gas, and viii) blocking the backflow of natural gas. When, a second safety valve connected to a natural gas backfire discharge pipe between the second check valve and the natural gas discharge interval is opened and operated at a fourth pressure greater than the third pressure to discharge backfire of natural gas.

The Brownian gas flashback discharge pipe may include i) a first discharge pipe formed of a first diameter and a first distance, and ii) a second discharge pipe formed of a second diameter greater than the first diameter and a second distance greater than the first distance. You can. The first safety valve may include i) a first mechanical valve provided in the first discharge pipe, and ii) a second mechanical valve provided in the second discharge pipe and opened at the same pressure as the first mechanical valve. The natural gas flashback discharge pipe may include i) a third discharge pipe formed of a third diameter and a third distance, and ii) a fourth discharge pipe formed of a fourth diameter greater than the third diameter and a fourth distance greater than the third distance. You can. The second safety valve may include i) a third mechanical valve provided in the third discharge pipe, and ii) a fourth mechanical valve provided in the fourth discharge pipe and opened at the same pressure as the third mechanical valve. In the step of discharging the brown gas backfire, the brown gas backfire may be discharged through the first discharge pipe and the first mechanical valve, and may be discharged through the second discharge pipe and the second mechanical valve. In the step of discharging the backfire of natural gas, the backfire of natural gas may be discharged through the third discharge pipe and the third mechanical valve, and may be discharged through the fourth discharge pipe and the fourth mechanical valve.

The first solenoid valve may be closed in the step of discharging the backfire of the brown gas, and the second solenoid valve may be closed in the step of discharging the backfire of the natural gas. In the step of discharging the backfire of the Brown gas, the first pressure may be 0.1 bar to 0.2 bar, and the second pressure may be 3 bar to 5 bar. In the step of discharging the flashback of natural gas, the third pressure may be 0.1 bar to 0.2 bar, and the fourth pressure may be 3 bar to 5 bar. In the step of preheating the inside of the ladle, the amount of Brown gas in the co-firing gas may be 25 vol% to 35 vol%.

It is possible to prevent backfire of the ladle preheating device due to high temperature radiant heat inside the ladle. In addition, since the Brown gas backfire is guided to the Brown gas backfire discharge pipe and discharged to the outside of the body through the safety valve, it is possible to prevent the Brown gas backfire from proceeding further into the device through the Brown gas supply pipe. And by reducing the amount of natural gas used, the amount of carbon dioxide generated when natural gas is burned can be reduced.

1 is a schematic diagram of a state of use of a ladle preheating device according to a first embodiment of the present invention.
Figure 2 is a schematic cross-sectional view of the ladle preheating device of Figure 1.
Figure 3 is a schematic bottom view of the ladle preheating device of Figure 2;
FIG. 4 is a schematic operational state diagram of the ladle preheating device of FIG. 2 during backfire.
Figure 5 is a schematic bottom view of a ladle preheating device according to a second embodiment of the present invention.
Figure 6 is a schematic flowchart of a ladle preheating method according to the first embodiment of the present invention.
Figure 7 is a photograph of a ladle preheating device according to an experimental example of the present invention.
Figures 8 and 9 are photographs of ladle preheating according to an experimental example of the present invention and a comparative example of the prior art, respectively.

Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts not related to the description are omitted, and identical or similar components are given the same reference numerals throughout the specification.

Figure 1 schematically shows the use state of the ladle preheating device 100 according to the first embodiment of the present invention. The state of use of the ladle preheating device 100 in FIG. 1 is merely for illustrating the present invention, and the present invention is not limited thereto. Therefore, the use state of the ladle preheating device 100 can be modified into other forms.

As shown in FIG. 1, a ladle (L) and a ladle cover (C) are prepared for transport of molten metal. The ladle cover (C) can cover the ladle (L) to prevent foreign substances from penetrating into the ladle (L).

It is necessary to preheat the inside of the ladle (L) before transferring the molten metal. For this purpose, the ladle preheating device 100 is used. A ladle preheating hole (C10) is formed in the ladle cover (C). Therefore, after installing the ladle preheating device 100 on the ladle preheating hole C10, the inside of the ladle L can be preheated by introducing and burning brown gas, natural gas, and combustion air. Air is used for combustion and is supplied into the ladle (L) through the air inlet pipe 30 along the direction of the dotted arrow. The air for combustion is not cold air, but 1200℃ exhaust gas discharged from the ladle, which is heated to approximately 1000℃ through a heat storage body and heat exchanger. As a result, the temperature of the flame can be increased and energy can be saved. In addition, the brown gas and natural gas are combusted due to the oxygen contained in the air, and the flame (F) required for preheating the inside of the ladle can be maintained.

As shown in FIG. 1, as a flame F is formed inside the ladle L, the inside of the ladle L is preheated by the radiant heat. Meanwhile, exhaust gas generated by co-firing of brown gas and natural gas may be discharged into the space between the ladle (L) and the ladle cover (C). Hereinafter, the structure of the ladle preheating device 100 will be described in detail through FIG. 2.

FIG. 2 schematically shows the cross-sectional structure of the ladle preheating device 100 of FIG. 1. That is, FIG. 2 shows a cross-sectional structure of the ladle preheating device 100 of FIG. 1 cut in the zx plane direction. The cross-sectional structure of the ladle preheating device 100 in FIG. 2 is merely for illustrating the present invention, and the present invention is not limited thereto. Therefore, the cross-sectional structure of the ladle preheating device 100 can be modified into other shapes. Meanwhile, FIG. 3 shows a schematic bottom structure of the ladle preheating device 100 of FIG. 2.

As shown in FIG. 2, the ladle preheating device 100 uses brown gas (BG) and natural gas (LG) to preheat the inside of the ladle (L). As natural gas (LG), liquefied natural gas (LNG) or liquefied propane gas (LPG) can be used.

The brown gas supply unit 110 generates brown gas and supplies brown gas (BG) to the brown gas outlet 11 through the brown gas supply pipe 10. The natural gas supply unit 120 supplies natural gas (LG) to the natural gas outlet 21 through the natural gas supply pipe 20. Brown gas (BG) and natural gas (LG) meet at the end 701 of the cover member 70 and are mixed together and burned.

At the end of the ladle preheating device 100, brown gas (BG) and natural gas (LG) are co-combusted to preheat the inside of the ladle. Brown gas (BG) and natural gas (LG) are continuously supplied to preheat the inside of the ladle. Meanwhile, although not shown in FIG. 2, air for combustion is also continuously supplied.

As shown in FIG. 2, the ladle preheating device 100 includes a body 40, a pipe holder 50, a first solenoid valve (SV1), a second solenoid valve (SV2), a distribution member 60, and a cover member. Includes (70). As shown in FIG. 2, the body 40 forms a space inside and is open at both ends.

The pipe holder 50 is installed at the open first end (top of Figure 2) of the body 40 to seal the first end, and the distribution member 60 is installed at the open second end of the body 40 (Figure 2). It is connected to the bottom of 2) and seals the second end. Accordingly, the pipe holder 50, body 40, distribution member 60, and cover member 70 form the torch T of the ladle preheating device 100. Combustion air is supplied to the body 40 and discharged through the air outlet 703.

The body 40 and the pipe holder 50 may be made of copper, iron, or stainless steel, and may be connected to each other by welding. The pipe holder 50 penetrates the Brown gas supply pipe 10 and the natural gas supply pipe 20 to form an airtight structure.

The first solenoid valve (SV1) is installed in the Brown gas supply pipe 10 and operates to open and close, so the Brown gas (BG) is directed to the inside of the ladle through the Brown gas supply pipe 10 to the Brown gas chamber 13 and the Brown gas outlet 11. ) can be supplied or blocked. Additionally, the first solenoid valve SV1 can control the flow rate of the incoming Brown gas (BG). The Brown gas supply unit 110 is connected to the Brown gas supply pipe 10.

The second solenoid valve (SV2) is installed in the natural gas supply pipe 20 and operates to open and close, so it flows through the natural gas supply pipe 20 and the natural gas outlet 21 to supply high-pressure natural gas (LG) toward the inside of the ladle. You can block it. And the second solenoid valve (SV2) can control the flow rate of natural gas (LG). The natural gas supply unit 120 is connected to the natural gas supply pipe 20.

The brown gas supply unit 110, the natural gas supply unit 120, the first solenoid valve (SV1), and the second solenoid valve (SV2) are operated in the preheating process by a control unit (not shown) that overall controls the ladle preheating device 100. properly controlled. Although not shown, the first solenoid valve (SV1) and the second solenoid valve (SV2) are replaced with a first manual valve and a second manual valve, respectively, for manual operation, or a first manual valve and a second manual valve, respectively, for both automatic and manual control. It may also be installed in parallel with the second manual valve.

As shown in FIG. 2, the distribution member 60 includes a distribution port 12 connected to the Brown gas supply pipe 10, a natural gas discharge port 21 connected to the natural gas supply pipe 20, and an air outlet 703. ) to form. The distribution member 60 may be made of copper, iron, or stainless steel, and may be connected to the body 40 by welding. The diameters of the Brown gas supply pipe 10, the distribution port 12, the natural gas supply pipe 20, and the natural gas outlet 21 may be set to different sizes depending on the depth and size of the ladle to be preheated.

The cover member 70 is screwed to the distribution member 60 to form a Brown gas chamber 13 connected to the distribution port 12 and a Brown gas discharge port 11 connected thereto. The cover member 70 forms an end 701 of the torch T that faces the inside of the ladle.

The Brown gas chamber 13 and the Brown gas outlet 11 are partitioned by a space between the outer surface of the screw-coupled distribution member 60 and the inner surface of the cover member 70. They are connected to each other in the direction of supply of Brown Gas (BG) and also in the direction of backfire. Therefore, the required capacity size of Brown's gas (BG) can be set according to the shape of the outer surface of the distribution member 60 and the inner surface of the cover member 70 that face each other. That is, the design of the torch T can be freely adjusted due to the distribution member 60 and the cover member 70 being coupled to each other.

The Brown gas chamber 13 is formed with a volume larger than the volume of the Brown gas discharge port 11. The Brown gas outlet 11 has a cross-sectional area narrower than that of the Brown gas chamber 13 and is connected to the Brown gas chamber 13. The Brown gas chamber 13 evenly distributes the Brown gas (BG) flowing in from the distribution port 12 toward the Brown gas outlet 11, adjusts the injection amount, and injects it at a set speed. The air outlet 703 is formed extending from the distribution member 60 to the cover member 70.

In the torch T, the natural gas outlet 21 is provided at the center of the distribution member 60, and the distribution port 12 is provided on one side of the natural gas outlet 21. The Brown gas chamber 13 is spaced apart from the natural gas outlet 21 by a first gap G1. The Brown gas chamber 13 is formed in an annular shape having a first range R1 in the radial direction. The brown gas outlet 11 meets the natural gas outlet 21 at the bottom of the ladle preheating device 100 and mixes the brown gas and natural gas. The Brown gas outlet (11) is formed in an annular shape surrounding the natural gas outlet (21).

The annular Brown gas outlet (11) surrounds the natural gas outlet (21) and uniformly controls the amount of supplied Brown gas (BG). The brown gas outlet 11 can stably receive and discharge brown gas (BG) from the brown gas chamber 13.

The ladle preheating device 100 preheats the inside of the ladle. When the first solenoid valve (SV1) is operated to open the Brown gas supply pipe 10, the first check valve (CV1) is opened from a preset first pressure or higher due to the pressure of the Brown gas (BG). For example, when the pressure of Brown's gas (BG) is 0.3 bar to 0.5 bar, the first check valve (CV) opens at a lower first pressure of 0.1 bar to 0.2 bar. Therefore, when the first solenoid valve (SV1) is opened, the brown gas (BG) is normally supplied while opening the check valve (CV1) and is co-combusted with the natural gas (LG) to preheat the inside of the ladle.

And when the second solenoid valve (SV2) is operated to open the natural gas supply pipe 20, the second check valve (CV2) is opened above the preset second pressure. For example, when the pressure of natural gas (LG) is 0.3 bar to 0.5 bar, the second check valve (CV2) opens at a lower second pressure of 0.1 bar to 0.2 bar. Therefore, when the second solenoid valve (SV2) is opened, the natural gas (LG) is normally supplied while the check valve (CV2) is opened and is co-combusted with the Brown gas (BG) to preheat the inside of the ladle.

Meanwhile, a first safety valve 90 and a second safety valve 96 are provided to prepare for backfire of brown gas (BG) and natural gas (LG), respectively. That is, the Brown gas backfire discharge pipe 80 is connected to the Brown gas supply pipe 10 between the first check valve CV1 and the distribution member 60, and is drawn out to the outside of the body 40. The first safety valve 90 is provided in the Brown gas backfire discharge pipe 80 outside the body 40. Meanwhile, the natural gas backfire discharge pipe 86 is connected to the natural gas supply pipe 20 between the second check valve CV2 and the distribution member 60, and is drawn out to the outside of the body 40. The second safety valve 96 is provided in the natural gas backfire discharge pipe 86 outside the body 40.

Meanwhile, the flame may backfire into the ladle preheating device 100 due to the narrow space and radiant heat inside the ladle. If backfire occurs, the lower end of the ladle preheating device 100 may be damaged. To prevent this, the ladle preheating device 100 has a structure to prevent backfire of brown gas (BG) and natural gas (LG). That is, the ladle preheating device 100 further includes check valves CV1 and CV2, a Brown gas flashback discharge pipe 80, a natural gas flashback discharge pipe 86, and safety valves 90 and 96.

FIG. 4 schematically shows the backfire blocking state of Brown gas and natural gas in the ladle preheating device 100 of FIG. 2. The backfire blocking state of the ladle preheating device 100 in FIG. 4 is merely for illustrating the present invention, and the present invention is not limited thereto. Accordingly, the backfire blocking state of the ladle preheating device 100 can be modified differently.

As shown in FIG. 4, the first check valve (CV1) blocks flashback (FB) of the Brown gas (BG). That is, when the first solenoid valve SV1 is operated to open the Brown gas supply pipe 10, the first check valve CV1 is opened above the first pressure due to the pressure of the supplied Brown gas BG. (See Figure 2). And when the high-pressure Brown gas backfires, the first check valve (CV1) is closed to block the supply of Brown gas (BG).

The first safety valve 90 is designed to open and operate at a third pressure greater than the first pressure of 0.1 bar to 0.2 bar to discharge backfire (FB) inside the ladle during the preheating process. For example, the safety valve 90 is operated to open at a third pressure of 3 bar to 5 bar.

The safety valve 90 includes a housing 91, a snap ring 92, an elastic member 93, a support member 94, and a valve body 95. In addition, the safety valve 90 may further include other parts. The housing 91 is connected to the Brown gas flashback discharge pipe 80. The snap ring 92 is provided on the inner surface of the outlet side of the housing 91. The elastic member 93 is supported on the snap ring 92. The support member 94 is movably provided on the inlet side and supported by the elastic member 93. The valve body 95 is connected to the support member 94 to open and close the outlet. The Brown gas backfire (FB) flows into the inlet side of the housing 91 and operates as a third pressure on the valve body 95 to overcome the elastic force of the elastic member 93, thereby opening the outlet of the housing 91.

Meanwhile, the second check valve (CV2) blocks backfire (FB) of natural gas (LG). That is, when the second solenoid valve SV2 is operated to open the natural gas supply pipe 20, the second check valve CV2 is opened from the fourth pressure or higher due to the pressure of the supplied natural gas LG. (See Figure 2). And when high-pressure natural gas backfires, the second check valve (CV2) is closed to block the supply of natural gas (LG).

The second safety valve 96 is designed to open and operate at a fourth pressure greater than the second pressure of 0.1 bar to 0.2 bar to discharge backfire (FB) inside the ladle during the preheating process. For example, the safety valve 96 is operated to open at a fourth pressure of 3 bar to 5 bar. Meanwhile, since the internal structure of the second safety valve 96 is the same as that of the first safety valve 90, detailed description thereof will be omitted.

When brown gas (BG) and natural gas (LG) preheat the inside of the ladle in a normal state, brown gas (BG) and natural gas (LG) are co-combusted to form a flame. As a result, the inside of the Brown gas backfire discharge pipe 80 and the inside of the natural gas backfire discharge pipe 86 instantly reach the maximum explosion pressure. The pressure amplified to the maximum explosion pressure closes the first check valve (CV1) and the second check valve (CV2). Therefore, the backfire (FB) is blocked by the first check valve (CV1) and the second check valve (CV2) and cannot penetrate into the Brown gas supply pipe 10 and the natural gas supply pipe 20. Furthermore, since the backfire (FB) does not reach the brown gas supply unit 110 and the natural gas supply unit 120, the brown gas supply unit 110 and the natural gas supply unit 120 can be safely protected.

Meanwhile, brown gas (BG) and natural gas (LG) flow back to the brown gas backfire discharge pipe 80 and the natural gas backfire discharge pipe 86, respectively, and open the first safety valve 90 and the second safety valve 96, respectively. Open it. And the amplified backfire (FB) is discharged to the outside of the first safety valve 90 and the second safety valve 96 in the form of a high-pressure flame. Since the first safety valve 90 and the second safety valve 96 are located inside the torch (T) rather than outside the torch (T), that is, the first safety valve 90 and the second safety valve 96 Since it is located between the pipe holder 50 and the distribution member 60, the backfire (FB) can be quickly blocked to quickly protect the Brown gas supply unit 110 and the natural gas supply unit 120. That is, since the first check valve (CV1), the second check valve (CV2), the first safety valve 90, and the second safety valve 96 are built into the torch (T), the Brown gas supply unit ( 110) and the natural gas supply unit 120 can be efficiently protected. On the contrary, when the first safety valve 90 and the second safety valve 96 are installed outside the torch (T), that is, near the Brown gas supply part 110 and the natural gas supply part 120, the backfire (FB) Rapid blocking is impossible. In this case, there is a high possibility that the Brown gas supply unit 110 and the natural gas supply unit 120 will be damaged.

Figure 5 schematically shows the bottom structure of the ladle preheating device 200 according to the second embodiment of the present invention. Since the structure of the ladle preheating device 200 of FIG. 5 is similar to the structure of the ladle preheating device 100 of FIG. 3, the description of the same parts will be omitted for convenience, and only the different parts will be described.

Referring to FIG. 5, the Brown gas backfire discharge pipe includes a first discharge pipe 861 and a second discharge pipe 862 connected to the Brown gas supply pipe 10. The safety valve includes a first mechanical valve 961 and a second mechanical valve 962. The first mechanical valve 961 is provided in the first discharge pipe 861, and the second mechanical valve 962 is provided in the second discharge pipe 862.

The first discharge pipe 861 is formed with a first diameter D1, is drawn out of the body at a first distance L1, and is connected to the first mechanical valve 961. The second discharge pipe 862 is formed with a second diameter (D2) larger than the first diameter (D1) and is drawn out of the body 40 at a second distance (L2) larger than the first distance (L1) to form a second discharge pipe (862). It is connected to a mechanical valve 962. The second discharge pipe 862 is connected to the Brown gas supply pipe 10 to avoid interference with the natural gas supply pipe 20 located in the center of the cooling chamber 43 (shown in FIG. 5). As the second distance L2 is formed longer than the first distance L1, the second diameter D2 is formed larger than the first diameter D1, so that the first mechanical valve 961 and the second mechanical valve 962 can be opened with the same pressure.

Meanwhile, the natural gas backfire discharge pipe includes a third discharge pipe 866 and a fourth discharge pipe 867 connected to the natural gas supply pipe 20. The safety valve includes a third mechanical valve 966 and a fourth mechanical valve 967. The third mechanical valve 966 is provided in the third discharge pipe 866, and the fourth mechanical valve 967 is provided in the fourth discharge pipe 867.

The third discharge pipe 866 is formed with a third diameter D3, is drawn out of the body at a third distance L3, and is connected to the third mechanical valve 966. The fourth discharge pipe 867 is formed with a fourth diameter D4 larger than the third diameter D3 and is drawn out of the body 40 at a fourth distance L4 larger than the third distance L3. It is connected to a mechanical valve (967). The fourth discharge pipe 867 is connected to the natural gas supply pipe 20 to avoid interference with the Brown gas supply pipe 10. As the fourth distance L4 is formed longer than the third distance L3, the fourth diameter D4 is formed larger than the third diameter D3, so that the third mechanical valve 966 and the fourth mechanical valve 967 can be opened with the same pressure.

For Brown gas, backfire is discharged to the outside of the first mechanical valve 961 and the second mechanical valve 962 in the form of a high-pressure flame via the first discharge pipe 861 and the second discharge pipe 862. Therefore, backfire is blocked at the first check valve (CV1) and does not reach the Brown gas supply pipe (10).

The first discharge pipe 861, the second discharge pipe 862, the first mechanical valve 961, and the second mechanical valve 962 can discharge the amplified backfire more quickly through the expanded passage. That is, the backfire does not reach the Brown gas supply unit 110 (shown in FIG. 4, the same applies hereinafter), so the Brown gas supply unit 110 can be protected more efficiently. In addition, since the first mechanical valve 961 and the second mechanical valve 962 can operate the other even if one of them is broken, the safety of the ladle preheating device 200 against backfire can be greatly improved. You can.

Meanwhile, for natural gas, backfire is discharged to the outside of the third mechanical valve 966 and the fourth mechanical valve 967 in the form of a high-pressure flame via the third discharge pipe 866 and the fourth discharge pipe 867. Therefore, backfire is blocked at the second check valve (CV2) and does not reach the natural gas supply pipe (20).

The third discharge pipe 866, the fourth discharge pipe 867, the third mechanical valve 966, and the fourth mechanical valve 967 can discharge the amplified backfire more quickly through the expanded passage. That is, the backfire does not reach the natural gas supply unit 120 (shown in FIG. 4, the same applies hereinafter), so the natural gas supply unit 120 can be protected more efficiently. In addition, the third mechanical valve 966 and the fourth mechanical valve 967 can operate the other even if one of them is broken, greatly improving the safety of the ladle preheating device 200 against backfire. You can.

Figure 6 schematically shows a flow chart of the ladle preheating method according to the first embodiment of the present invention. The ladle preheating method in FIG. 6 is merely for illustrating the present invention, and the present invention is not limited thereto.

As shown in FIG. 6, the ladle preheating method includes arranging the ladle preheating device to face the inside of the ladle (S10), opening the first solenoid valve and the second solenoid valve to supply brown gas and natural gas, respectively. (S20), preheating the inside of the ladle with a flame caused by co-firing of brown gas and natural gas (S30), closing the first and second check valves in case of backfire (S40), and first safety It includes opening the valve and the second safety valve (S50). In addition, the ladle preheating method may further include other steps.

First, in step S10, the ladle preheating device is arranged to face the inside of the ladle. That is, the ladle preheating device is arranged to preheat the inside of the ladle for efficient transport of the molten metal.

In step S20, the first solenoid valve and the second solenoid valve are opened, respectively, to supply Brown gas and natural gas. That is, the first solenoid valve is opened to supply Brown gas into the ladle preheating device. Additionally, the second solenoid valve is opened to supply natural gas into the ladle preheating device.

Next, in step S30, the inside of the ladle is preheated with a flame caused by co-firing of brown gas and natural gas. That is, brown gas and natural gas meet at the bottom of the cover member, mix, and burn. As a result, the inside of the ladle can be preheated by co-firing of Brown gas and natural gas.

In the ladle preheating method according to an embodiment of the present invention, natural gas or brown gas is not used individually, but is used in combination. When using a mixture of natural gas and Brown gas, preheating costs can be minimized while maximizing preheating efficiency. In addition, the use of brown gas can reduce the amount of natural gas used, making it economical. When natural gas and brown gas are mixed and burned, the ignition point of the co-fired gas is lowered due to the hydrogen contained in the brown gas. Therefore, complete combustion of natural gas is possible and no carbon dioxide is emitted. And since natural gas burns well through co-firing, the amount of NOx generated can be reduced by lowering the excess air ratio. In addition, co-firing increases the length of the flame, increasing the contact area with the ladle, thereby increasing the temperature raising effect.

More specifically, the flow rate of Brown gas may be 30% to 70% of the total flow rate of co-firing gas. If the flow rate of brown gas is too low, the amount of carbon dioxide generated due to the use of natural gas greatly increases. Therefore, it may also run counter to the carbon neutral policy that has recently become a hot topic. Conversely, if the flow rate of Brown gas is too high, the cost of preheating may increase significantly. Therefore, by adjusting the flow rate of the Brown gas within the above-mentioned range, it is possible to shorten the ladle temperature rise time and improve opportunity cost. More preferably, the flow rate of Brown gas in the co-firing gas may be 40% to 60%. More preferably, the flow rate of Brown gas in the co-firing gas may be 57%.

In step S40, when the brown gas and natural gas backfire, the first check valve and the second check valve are closed, respectively. For example, if the ladle preheating device is close to the bottom of the ladle or the temperature inside the ladle is too high, the lower end of the cover member may be melted and a backfire may occur inside the ladle preheating device, resulting in damage to the ladle preheating device. To prevent this, the first check valve and the second check valve are closed. In this case, the flame does not reach the natural gas supply part and the brown gas supply part, thereby preventing safety accidents.

And in step S50, the first safety valve and the second safety valve are opened. Even if the first check valve and the second check valve are closed, backfire may exist in the Brown gas supply pipe and the natural gas supply pipe. Therefore, the first safety valve and the second safety valve are each opened to discharge the backfire to the outside. Through this process, the ladle is preheated.

Hereinafter, the present invention will be described in detail through experimental examples. These experimental examples are only for illustrating the present invention, and the present invention is not limited thereto.

Figure 7 is a photograph showing a ladle preheating device according to an experimental example of the present invention. A ladle preheating experiment was conducted using the ladle preheating device of FIG. 7. Brown gas and natural gas were mixed and burned. LPG was used as natural gas. Since the detailed experimental process can be easily understood by those skilled in the art to which the present invention pertains, detailed description thereof will be omitted.

Experiment example

The inside of the ladle was heated using 7.3Nm ³ /h of LPG and 10Nm ³ /h of Brown gas. The temperature inside the ladle before heating was 19.6°C when measured with a thermocouple. The time it took to raise the temperature inside the ladle to 1,201°C was measured. Detailed experimental procedures can be easily understood by those skilled in the art to which the present invention pertains, so they are omitted for convenience.

Comparative example

The inside of the ladle was heated using only LPG at 9.1Nm ³ /h. The temperature inside the ladle before heating was 55.2°C when measured with a thermocouple. The time it took to raise the temperature inside the ladle to 1,201°C was measured. The remaining experimental conditions were the same as the above-described experimental example.

Experiment result

The above-described experiment and its results are shown in Table 1 below.

division start
temperature
(℃) end
temperature
(℃) drive
hour gas
type flux
( ^Nm3 /h) gas usage
( ^Nm3 /h)/kW Calories input
(kcal/h) sum
(kcal/h) Experiment example 19.6 1201 5:15:00 LPG 7.3 30.05 661.137 731,656 air 191 B.G. 10 175.37 70.519 Comparative example 55.2 1201 4:07:00 LPG 9.1 47.78 1,051,050 air 238 1,051,050 B.G. 0

As shown in Table 1, the total calories used were 731,656 kcal/g in the experimental example and 1,051,050 kcal/g in the comparative example. Therefore, the energy consumption of the experimental example was only about 70% of the energy consumption of the comparative example, resulting in a significant reduction in energy consumption.

Target temperature arrival time experiment result

In the experimental example, it took 4 hours and 7 minutes, but in the comparative example, it took 5 hours and 15 minutes, so the experimental example took 1 hour and 8 minutes less time to reach the target temperature than the comparative example. That is, the temperature rise time of the experimental example was about 1.3 times faster than the comparative example.

Carbon dioxide consumption experiment results

Since carbon dioxide is not generated during combustion of brown gas, only the amount of carbon dioxide used due to LPG use was calculated. The amount of LPG used in the experimental example was 30.05Nm ³ (= 7.3Nm ³ /hx 4.117h), and the amount of LPG used in the comparative example was 47.78Nm ³ (= 9.1Nm ³ /hx 5.25h). Therefore, in the experimental example, the amount of carbon dioxide generated was reduced by 10.54 kg (= LPG (47.78-30.05) Nm ³ x 2.07 kg/Nm ³ x CO ₂ 3.012 kg/kg_LPG) by reducing the amount of LPG usage.

Combustion air usage experiment results

In terms of combustion air usage, the experimental example was able to save energy for heating nitrogen, which accounts for 79% of the air, by reducing the amount of combustion air by about 20% (=47Nm ³ ) compared to the comparative example. As a result, the temperature rise time inside the ladle became faster.

Flame test results

Figures 8 and 9 are pictures of ladle preheating according to an experimental example of the present invention and a comparative example of the prior art, respectively.

As shown in Figures 8 and 9, it can be seen that the length of the flame in the experimental example of the present invention is about 1.3 times longer than the comparative example of the prior art. Therefore, the contact area between the flame and the ladle is expanded, thereby increasing the temperature increase rate of the ladle.

Although an embodiment of the present invention has been described above, the present invention is not limited thereto, and can be implemented with various modifications within the scope of the claims, description of the invention, and accompanying drawings, and this is also part of the present invention. It is natural that it falls within the scope.

10: Brown gas supply pipe 11: Brown gas outlet
12: Distribution port 13: Brown gas chamber
20: natural gas supply pipe 21: natural gas outlet
30: air inlet pipe 40: body
50: Piping holder 60: Distribution member
70: Cover member 80: Gas backfire discharge pipe
90: safety valve 91: housing
92: Snap ring 93: Elastic member
94: support member 95: valve body
100, 200: Ladle preheating device 110: Brown gas supply unit
120: Natural gas supply section 701. End section
703. Air outlet 861: first discharge pipe
862: second discharge pipe 961: first mechanical valve
962: Second mechanical valve CV1, CV2: Check valve
D1, D2, D3, D4: Diameter FB: Brown gas flashback
G1: Spacing L1, L2, L3, L4: Distance
R1: Range SV1: 1st solenoid valve
SV2: Second solenoid valve T: Torch

Claims (10)

A ladle preheating device using Brown gas,
A body that forms an internal space, is open at both ends, and is supplied with air;
a pipe holder installed at the open first end of the body to seal it, and passing through and fixing the Brown gas supply pipe and the natural gas supply pipe;
A first solenoid valve installed in the Brown gas supply pipe and operated to open and close;
a second solenoid valve installed in the natural gas supply pipe and operated to open and close;
a distribution member connected to the open second end of the body and forming a plurality of air outlets through which the air is discharged, a distribution port connected to the Brown gas supply pipe, and a natural gas discharge port connected to the natural gas supply pipe;
It is coupled to the distribution member to form a Brown gas chamber connected to the distribution port between the distribution member and the cover member and a Brown gas discharge port connected to the Brown gas chamber, and the plurality of air outlets extend and penetrate into the ladle. a cover member facing toward;
a first check valve installed in the Brown gas supply pipe inside the body, operated to open at a first pressure, supplying the Brown gas, and blocking backflow of the Brown gas;
a Brown gas backfire discharge pipe connected to the Brown gas supply pipe between the first check valve and the distribution member and extended to the outside of the body;
a first safety valve installed in the Brown gas backfire discharge pipe and operated to open at a second pressure greater than the first pressure to discharge backfire from the inside of the ladle during preheating of the inside of the ladle;
a second check valve installed in the natural gas supply pipe inside the body, operated to open at a third pressure, supplying natural gas, and blocking backflow of the natural gas;
a natural gas backfire discharge pipe connected to the natural gas supply pipe between the second check valve and the distribution member and led to the outside of the body; and
A second safety valve installed in the natural gas backfire discharge pipe and operated to open at a fourth pressure greater than the third pressure to discharge the backfire.
Including,
The brown gas outlet and the natural gas outlet are connected at the bottom of the cover member, and the plurality of air outlets are spaced apart from each other to surround the brown gas outlet and the natural gas outlet. In paragraph 1:
The natural gas outlet is provided at the center of the distribution member,
The Brown gas chamber is spaced apart from the natural gas outlet at a first gap (G1) and is formed in an annular shape having a first range (R1) in the radial direction,
The brown gas outlet is in contact with the natural gas outlet at the bottom of the cover member and surrounds the natural gas outlet. In paragraph 1:
The Brown gas backfire discharge pipe includes a first discharge pipe and a second discharge pipe connected to the Brown gas supply pipe,
The first safety valve includes a first mechanical valve provided in the first discharge pipe and a second mechanical valve provided in the second discharge pipe,
The natural gas backfire discharge pipe includes a third discharge pipe and a fourth discharge pipe connected to the natural gas supply pipe,
The second safety valve is a ladle preheating device including a third mechanical valve provided in the third discharge pipe and a fourth mechanical valve provided in the fourth discharge pipe. In paragraph 3,
The first discharge pipe is formed to have a first diameter (D1) and is drawn out of the body at a first distance (L1),
The second discharge pipe is formed with a second diameter (D2) that is larger than the first diameter (D1) and is drawn out of the body at a second distance (L2) that is larger than the first distance (L1),
The third discharge pipe is formed with a third diameter (D3) and is drawn out of the body at a third distance (L3),
The fourth discharge pipe is formed with a fourth diameter (D4) that is larger than the third diameter (D3) and is drawn out of the body at a fourth distance (L4) that is larger than the third distance (L3). A ladle preheating method using the ladle preheating device according to claim 1, comprising:
Arranging the ladle preheating device to face the inside of the ladle,
Opening the first solenoid valve to supply the Brown gas through the Brown gas supply pipe, and opening the second solenoid valve to supply the natural gas through the natural gas supply pipe,
Supplying air for combustion through the plurality of air outlets,
Co-firing the brown gas and the natural gas at the bottom of the cover member and preheating the inside of the ladle with a flame from the co-firing,
When the Brown gas backfires, the first check valve installed in the Brown gas supply pipe and opened at a first pressure is closed by the Brown gas flowing back, thereby blocking the backflow of the Brown gas;
When blocking the backflow of the Brown gas, the first safety valve connected to the Brown gas backfire discharge pipe between the first check valve and the Brown gas discharge interval is opened and operated at a second pressure greater than the first pressure to open the Brown gas. discharging the backfire,
When the natural gas backfires, the second check valve installed in the natural gas supply pipe and opened at a third pressure is closed by the natural gas flowing back to block the backflow of the natural gas, and
When blocking the backflow of the natural gas, the second safety valve connected to the natural gas backfire discharge pipe between the second check valve and the natural gas discharge interval is opened and operated at a fourth pressure greater than the third pressure to release the natural gas. Stage of exhausting backfire
A ladle preheating method comprising. In paragraph 5,
The Brown gas backfire discharge pipe is
a first outlet pipe formed of a first diameter and a first distance, and
A second discharge pipe formed with a second diameter greater than the first diameter and a second distance greater than the first distance.
Includes,
The first safety valve is,
A first mechanical valve provided in the first discharge pipe, and
A second mechanical valve provided in the second discharge pipe and opened at the same pressure as the first mechanical valve.
Includes,
The natural gas backfire discharge pipe is
a third discharge pipe defined by a third diameter and a third distance, and
A fourth discharge pipe formed with a fourth diameter greater than the third diameter and a fourth distance greater than the third distance.
Including,
The second safety valve is,
A third mechanical valve provided in the third discharge pipe, and
A fourth mechanical valve provided in the fourth discharge pipe and opened at the same pressure as the third mechanical valve.
Includes,
In the step of discharging the brown gas backfire, the brown gas backfire is discharged through the first discharge pipe and the first mechanical valve, and discharged through the second discharge pipe and the second mechanical valve,
In the step of discharging the backfire of the natural gas, the backfire of the natural gas is discharged to the third discharge pipe and the third mechanical valve, and the ladle preheating method is discharged to the fourth discharge pipe and the fourth mechanical valve. In paragraph 5,
A ladle preheating method of closing the first solenoid valve in the step of discharging the backfire of the brown gas, and closing the second solenoid valve in the step of discharging the backfire of the natural gas. In paragraph 5,
In the step of discharging the backfire of the Brown gas, the first pressure is 0.1 bar to 0.2 bar, and the second pressure is 3 bar to 5 bar,
In the step of discharging the backfire of the natural gas, the third pressure is 0.1 bar to 0.2 bar, and the fourth pressure is 3 bar to 5 bar. In paragraph 5,
In the step of preheating the inside of the ladle, the flow rate of the Brown gas among the flow rates of the co-firing gas is 30% to 70%. In paragraph 9:
A ladle preheating method wherein the flow rate of the brown gas among the flow rates of the co-firing gas is 40% to 60%.

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