JP2008240133A - Method for switching combustion and exhaust of heat storage type combustion burner of continuous heating furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for switching a heat storage type burner of a continuous heating furnace capable of preventing the generation of black smoke. <P>SOLUTION: In the method for switching the combustion and exhaust of the heat storage type burners of the continuous heating furnaces which have blowing-in openings for fuel below blowing-in openings for air and are oppositely arranged with a plurality of pairs of the heat storage type burners to alternately switch the combustion and the exhaust on both sides of the side walls in the transverse direction of the heating chamber formed with an upper zone and a lower zone across a conveyance line of an object to be heated, the switching of the respective combustion and exhaust of the heat storage burners of the upper zone and the lower zone opposite thereto is simultaneously performed so that the combustion and the exhaust of the heat storage burners of the upper zone and the heat storage burners of the lower zone opposite thereto are made coincident. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for switching between combustion and exhaust in a regenerative combustion burner of a continuous heating furnace provided with a regenerative combustion burner.

  As a heating furnace for continuously heating a steel piece such as a slab, a continuous heating furnace provided with a regenerative combustion burner (hereinafter referred to as “regenerative burner”) is used.

  FIG. 7A is a plan view of a continuous heating furnace provided with a conventional regenerative burner, FIG. 7B is a side view thereof, and FIG. 7C is an AA cross-sectional view of FIG. FIG. 8 is a cross-sectional view showing the combustion and exhaust states of the regenerative burner, where (a) shows the state during combustion, and (b) shows the state during exhaust.

  In FIG. 7, the continuous heating furnace includes a plurality of regenerative burners (1-a), (1-b), (2-a) which are opposed to the left and right side walls 2a, 2b of the heating chamber 1 and are paired. And (2-b) are arranged in the upper zone 4 and the lower zone 5 with an interval across the conveying line of the steel slab 3. The charging door 6 is opened and the steel slab 3 is charged into the preheating chamber 7, transported by the walking beam 8, heated in the heating chamber 1, and the extraction door 9 is opened to be carried out. The remaining exhaust gas discharged from the regenerative burner is exhausted to the flue 10.

  In FIG. 8, the regenerative burner disposed on the side walls 2a and 2b is provided with an air flow path 12 that surrounds the fuel supply path 11 to which fuel is supplied and serves as an air supply path and an exhaust gas suction path. An air inlet 14 that is open to the furnace inside of the air flow path 12 is disposed on the fuel inlet 13 that is open to the inside of the furnace. A heat storage body 15 is arranged between the fuel supply path 11 and the air flow path 12.

  In the state at the time of combustion in FIG. 8A, fuel is supplied to the fuel supply path 11 and is blown from the fuel inlet 13, air is supplied to the air supply path 12, heated by the heat accumulator 15, and the air inlet 14. Infused from. When switching from combustion to exhaust, in the exhaust state (during heat storage) in FIG. 8B, the supply of fuel to the fuel injection path 11 is stopped, and high-temperature exhaust gas in the furnace is sucked from the air injection port 14. The heat storage body 15 stores heat. In order to reduce NOx, a regenerative burner of the type in which the fuel injection port 13 and the air injection port 14 are separated and burned slowly is generally used for the regenerative burner of the continuous heating furnace as shown in FIG. Yes.

  In a heating furnace equipped with a regenerative burner, in order to prevent leakage of flue gas to the outside of the furnace due to an increase in the furnace oxygen concentration and an increase in the furnace pressure, A method of shifting the timing of switching between combustion and exhaust of each regenerative burner is common so that there is always a regenerative burner during combustion when switching between combustion and exhaust (see, for example, Patent Document 1).

  FIG. 9 is a diagram showing the switching timing of combustion and exhaust of each regenerative burner in a continuous heating furnace equipped with a conventional regenerative burner, and FIGS. 10 (a) to 10 (d) are steps (1) to (d) of FIG. It is a figure which shows the combustion state of the thermal storage type burner in 4).

  In FIG. 9, in the upper zone, when one regenerative burner is combusting, the opposing regenerative burner is exhausting, and this combustion and exhaust operation are repeated alternately. The same applies to the heat storage burner on the left side of the lower zone and the heat storage burner on the right side.

  As shown in FIG. 10A, in the step (1), the heat storage burner (1-a) on the left side of the upper zone 4 and the heat storage burner (2-b) on the right side of the lower zone 5 are burning. .

  As shown in FIG. 10B, in the lower zone 5 in the step (2), the right regenerative burner (2-b) is switched from combustion to exhaust and at the same time the left regenerative burner (2-a) is exhausted. When switching from to combustion, the regenerative burner (1-a) on the left side of the upper zone 4 is burned without being switched. Accordingly, in both the upper zone 4 and the lower zone 5, the left-side heat storage burners (1-a) and (2-a) are burning.

  As shown in FIG. 10 (c), in the upper zone 4 in step (3), the left regenerative burner (1-a) is switched from combustion to exhaust, and at the same time the right regenerative burner (1-b) is exhausted. When switching from to combustion, the regenerative burner (2-a) on the left side of the lower zone 5 is burned without switching.

  As shown in FIG. 10 (d), in the lower zone 5 in step (4), the left regenerative burner (2-a) is switched from combustion to exhaust, and at the same time the right regenerative burner (2-b) is exhausted. When switching from to combustion, the regenerative burner (1-b) on the right side of the upper zone 4 is burned without switching. Therefore, in the upper zone 4 and the lower zone 5, the right-side heat storage burners (1-b) and (2-b) are burning.

  In this way, by shifting the switching timing between combustion and exhaust in the upper zone 4 and the lower zone 5, the combustion heat storage burner is always present so as to suppress the furnace pressure fluctuation. There is time for the regenerative burner on the same side to burn simultaneously.

Also, in a continuous heating furnace in which a plurality of zones such as a heating zone and a soaking zone are arranged, switching of the regenerative burner is generally performed for each zone, but in order to suppress the furnace pressure fluctuation, A method of shifting the switching timing is generally performed. In this case, there is always a time for the regenerative burner on the same side of the upper zone and the lower zone to burn simultaneously.
Japanese Patent Laid-Open No. 2002-5434

  In the continuous heating furnace provided with the regenerative burner of the type in which the fuel inlet and the air inlet shown in FIG. 8 are arranged apart from each other and slowly burned, the switching timing of the upper zone and the lower zone shown in FIG. As shown in steps (2) and (4), the switching method for generating time for burning the regenerative burners on the same side of the upper zone and the lower zone at the same time has the following problems.

  FIG. 11 is a diagram showing the state of fuel and air flow in step (2) and step (4) of FIG.

  When the fuel inlet 13 and the air inlet 14 are arranged apart from each other, as shown in FIG. 11, since the flow velocity of the air flow is fast, from the regenerative burner (1-a) or (1-b) in the upper zone 4 The injected low-velocity fuel should be absorbed and burned by the upper air flow. However, the injected air flow from the regenerative burner (2-a) or (2-b) in the lower zone 5 Is also sucked and reaches the vicinity of the extraction door in an unburned state of fuel, and as a result, black smoke is ejected from the extraction door and contaminates the environment.

  Thus, at the timing when the upper zone 4 and the lower zone 5 burn simultaneously, the flow of fuel and air in the upper zone 4 and the lower zone 5 interferes, and there is a region where the mixing of fuel and air is not stabilized locally. Occurs and generates unburned components (black smoke) and uneven temperature distribution.

  Therefore, the present invention provides a method for switching a regenerative burner in a continuous heating furnace that can prevent the generation of black smoke.

  The present invention has a fuel inlet below the air inlet on both sides of the side wall in the width direction of the heating chamber in which the upper zone and the lower zone are formed across the conveying line of the object to be heated. In a method of switching between combustion and exhaust of a regenerative burner of a continuous heating furnace in which a plurality of regenerative burners that alternately switch exhausts are opposed to each other in a pair, a regenerative burner in an upper zone and a lower portion on the opposite side Switching between combustion and exhaust of each of the heat storage type burners in the zone at the same time to match the combustion and exhaust of each of the heat storage type burner in the upper zone and the heat storage type burner in the lower zone on the opposite side; To do.

  In addition, a fuel inlet is provided below the air inlet on both sides of the heating chamber in which the upper zone and the lower zone are formed across the conveying line of the heated object and the side wall in the width direction of the soaking chamber. In a method for switching between combustion and exhaust of a regenerative burner of a continuous heating furnace in which a plurality of regenerative burners that alternately switch between combustion and exhaust are arranged facing each other, a regenerative burner in the upper zone, and The combustion and exhaust of the regenerative burner in the lower zone on the opposite side are switched simultaneously to switch the combustion and exhaust of the regenerative burner in the upper zone and the regenerative burner in the lower zone on the opposite side. In addition, it is characterized in that the switching between combustion and exhaust of the regenerative burner in the heating chamber and the switching between combustion and exhaust of the regenerative burner in the soaking chamber have a phase difference.

  The present invention provides a furnace by simultaneously switching between the upper zone regenerative burner and the lower zone regenerative burner so as to eliminate the time for the upper zone regenerative burner and the lower zone regenerative burner to burn simultaneously on one side. By stabilizing the exhaust gas flow in the furnace in the width direction, it is possible to stabilize the mixing of fuel and air, prevent the generation of unburned matter, and improve the temperature distribution. Moreover, the temperature distribution in the furnace width direction was also improved by stabilizing the exhaust gas flow in the furnace width direction.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing the switching timing of combustion and exhaust of each regenerative burner in a continuous heating furnace according to the present invention, and FIGS. 2 (a) to 2 (d) are regenerative equations in steps (1) to (4) of FIG. The figure which shows the combustion state of a burner, FIG. 3 is a figure which shows the fuel, air flow, and waste gas flow in this invention.

  In FIG. 1, the heat storage burner (1-a) on the left side of the upper zone 4 and the heat storage burner (1-b) on the right side are exhausted when one heat storage burner is burning. The combustion and exhaust operations are repeated alternately. The same applies to the heat storage burner (2-a) on the left side of the lower zone 5 and the heat storage burner (2-b) on the right side. The combustion of the regenerative burner in the upper zone 4 and the lower zone 5 and the switching of the exhaust are performed simultaneously.

  In step (1), as shown in FIG. 2 (a), the heat storage burner (1-a) on the left side of the upper zone 4 and the heat storage burner (2-b) on the right side of the lower zone facing this burn. The right-side regenerative burner (1-b) and the left-side regenerative burner (2-a) of the lower zone 5 facing this are exhausting.

  Also in the step (2), as shown in FIG. 2B, the regenerative burner in the upper zone 4 and the regenerative burner in the lower zone 5 continue without being switched between combustion and exhaust. As in 1), the heat storage burner (1-a) on the left side of the upper zone 4 and the heat storage burner (2-b) on the right side of the lower zone 5 facing this burn, and the heat storage burner (1- b) and the regenerative burner (2-a) on the left side of the lower zone facing this are exhausted.

  After step (2), combustion and exhaust of the regenerative burner in the upper zone 4 and the lower zone 5 are switched simultaneously. That is, as shown in FIG. 2 (c), the heat storage burner (1-a) on the left side of the upper zone 4 is switched from combustion to exhaust, and the heat storage burner (1-b) on the right is switched from exhaust to combustion. It is done. Simultaneously with the switching of the upper zone 4, the heat storage burner (2-b) on the right side of the lower zone 5 is also switched from combustion to exhaust, and the heat storage burner (2-a) on the left is switched from exhaust to combustion. In the step (3) after the regenerative burner of the upper zone 4 and the lower zone 5 is switched, the regenerative burner (1-b) on the right side of the upper zone 4 and the left side heat storage of the lower zone 5 opposite thereto. The type burner (2-a) burns, and the left side heat storage type burner (1-a) and the right side heat storage type burner (2-b) of the lower zone 5 opposed thereto exhaust.

  Also in the step (4), as shown in FIG. 2 (d), the regenerative burner in the upper zone 4 and the lower zone 5 continues as it is without switching between combustion and exhaust, and is the same as in the step (3). The right side regenerative burner (1-b) of the upper zone 4 and the left side regenerative burner (2-a) of the lower zone 5 are combusted, and the left side regenerative burner (1-a) and this The heat storage burner (2-b) on the right side of the lower zone 5 facing the exhaust evacuates.

  Therefore, in the present invention, the regenerative burner in the upper zone 4 and the regenerative burner in the lower zone 5 opposite to the burner always burn, and the regenerative burner above or below the burning regenerative burner exhausts. ing.

  As shown in FIG. 3, when the regenerative burner in the upper zone 4 burns and the regenerative burner in the lower zone 5 is exhaust, exhaust gas is sucked into the regenerative burner in the lower zone 5. On the other hand, the slow flow rate fuel blown from the fuel injection port 13 of the regenerative burner located in the upper zone 4 is not suitable for the flow of the exhaust gas having a low speed, and the air disposed above the fuel injection port. It is sucked and burned by an air flow having a high flow velocity blown from the blowing port 14. Further, since the exhaust gas flow 17 circulating in the furnace width direction is formed, the fuel blown from the blow-in port 13 in the upper zone 4 is sucked into the flow of air blown from the air suction port 14 disposed above. It becomes easy. As a result, it is possible to prevent the generation of unburned components (black smoke).

Using a continuous heating furnace equipped with an actual regenerative burner having the structure shown in FIG. 7, the steel material was heated by the conventional method and the method of the present invention for comparison test.
<Main test conditions>
Heating material: Slab after continuous casting Combustion conditions ・ Heating capacity: 80T / hr
・ Steel charging temperature: 20 ℃
・ Steel material extraction temperature: 1260 ℃
-Switching time: 60 seconds-Air ratio: 1.1-1.3

<Test results>
In the conventional technology, black smoke was ejected from the extraction door even when the air ratio was increased to 1.3. However, by adopting the technology of the present invention, the black smoke The outbreak is gone.

  By reducing the air ratio and reducing the generation of unburned fuel, the fuel consumption rate was improved by about 3%.

  This embodiment is an example in which the present invention is applied to a continuous heating furnace provided with a plurality of zones provided with a regenerative burner.

  4 (a) is a plan view of a continuous heating furnace provided with a regenerative burner, (b) is a side view thereof, (c) is a cross-sectional view taken along line AA of (b), and (d) is a cross-sectional view of (b). It is BB sectional drawing.

  In FIG. 4, the continuous heating furnace includes a preheating chamber 7, a heating chamber 1, and a soaking chamber 16 arranged in order via a partition wall 17. A plurality of paired regenerative burners facing the left and right side walls of the heating chamber 1 and the soaking chamber are arranged in the upper zone 4 and the lower zone 5 at intervals in the conveying direction of the steel pieces 3.

  The charging door 6 of the preheating chamber 7 is opened, and the steel slab 3 is inserted into the preheating chamber 7, transported by the walking beam 8, heated in the heating chamber 1, opened through the soaking chamber 16, and the extraction door 9 is opened and carried out. Is done. The remaining exhaust gas discharged from the regenerative burner is exhausted to the flue 10.

  FIG. 5 is a diagram showing the switching timing of combustion and exhaust of each regenerative burner in the continuous heating furnace of FIG. FIG. 6 is a diagram showing fuel, air flow and exhaust gas flow in the continuous heating furnace of FIG.

  In FIG. 5, combustion and exhaust switching of the regenerative burner in the upper zone and the lower zone of the heating chamber and the heating chamber are performed at the same time as in the first embodiment. The state of combustion and exhaust of the regenerative burner (1-a), (1-b), (2-a), (2-b) in each step (1) to (4) in the heating chamber shown in FIG. The combustion and exhaust states of the regenerative burner (3-a), (3-b), (4-a), (4-b) in each step (1) to (4) in the soaking chamber are as follows: 1 is the same as Example 1 shown in FIG. 1, and in both the heating chamber and the soaking chamber, the regenerative burner in the upper zone and the regenerative burner in the lower zone opposite to the burner are combusting and burning. The regenerative burner above or below the burner is exhausting. As a result, it is possible to prevent the generation of unburned components (black smoke).

  Further, the timing of switching between combustion and exhaust in the heating chamber and the timing of switching between combustion and exhaust in the soaking chamber are shifted to give a phase difference. By shifting the switching timing, the regenerative burner in the soaking chamber continues to burn when switching between combustion and exhaust in the heating chamber, and the regenerative burner in the heating chamber continues to burn when switching between soaking and exhaust in the soaking chamber As a result, fluctuations in the furnace pressure can be suppressed.

FIG. 1 is a diagram showing the switching timing of combustion and exhaust of each regenerative burner in the continuous heating furnace according to the present invention. FIGS. 2A to 2D are views showing the combustion state of the regenerative burner in steps (1) to (4) of FIG. It is a figure which shows the fuel, air flow, and waste gas flow in this invention. (A) is a plan view of a continuous heating furnace provided with a regenerative burner, (b) is a side view thereof, (c) is a cross-sectional view along line AA in (b), and (d) is a cross-sectional view along B- in (b). It is B sectional drawing. It is a figure which shows the switching timing of combustion and exhaust_gas | exhaustion of each thermal storage type burner in the continuous heating furnace of FIG. It is a figure which shows the fuel, air flow, and waste gas flow in the continuous heating furnace of FIG. (A) is a top view of the continuous heating furnace provided with the conventional thermal storage type burner, (b) is the same side view, (c) is AA sectional drawing of (b). It is sectional drawing which shows the state of combustion and exhaust_gas | exhaustion of a thermal storage type burner, (a) is a state at the time of combustion, (b) is a figure which shows the state at the time of exhaust. It is a figure which shows the switching timing of combustion and exhaust_gas | exhaustion of each heat storage type burner in the continuous heating furnace provided with the conventional heat storage type burner. FIGS. 10A to 10D are diagrams showing the combustion state of the regenerative burner in steps (1) to (4) of FIG. It is a figure which shows the state of the fuel and air flow in the process (2) and process (4) of FIG.

Explanation of symbols

1: Heating chamber 2a, 2b: Side wall 3: Steel slab 4: Upper zone 5: Lower zone 6: Loading door 7: Preheating chamber 8: Walking beam 9: Extraction door 10: Flue 11: Fuel supply path 12: Air Supply path 13: Fuel inlet 14: Air inlet 15: Heat storage body 16: Soaking chamber 17: Exhaust gas flow in the furnace

Claims (2)

On both sides of the side wall in the width direction of the heating chamber where the upper zone and lower zone are formed across the conveying line of the object to be heated, there is a fuel inlet below the air inlet, and combustion and exhaust are alternately performed In a method of switching between combustion and exhaust of a regenerative burner of a continuous heating furnace in which a plurality of regenerative burners to be switched are arranged to face each other in pairs,
Switching between combustion and exhaust of the regenerative burner in the upper zone and the regenerative burner in the lower zone on the opposite side is performed simultaneously, so that the regenerative burner in the upper zone and the lower zone on the opposite side are switched. A method for switching between combustion and exhaust of a regenerative burner in a continuous heating furnace, characterized in that each combustion and exhaust of the regenerative burner are matched. A fuel inlet is provided below the air inlet on both sides of the side wall in the width direction of the heating chamber in which the upper zone and the lower zone are formed across the conveying line of the article to be heated and the soaking chamber. In the method for switching between combustion and exhaust of a regenerative burner of a continuous heating furnace in which a plurality of regenerative burners that alternately switch between combustion and exhaust are opposed to each other in pairs,
Switching between combustion and exhaust of the regenerative burner in the upper zone and the regenerative burner in the lower zone on the opposite side is performed simultaneously, so that the regenerative burner in the upper zone and the lower zone on the opposite side are switched. The combustion and exhaust of the regenerative burner are made to coincide with each other, and a phase difference is provided between the combustion and exhaust of the heat storage burner in the heating chamber and the combustion and exhaust of the heat storage burner in the soaking chamber. How to switch between combustion and exhaust of a regenerative burner in a continuous heating furnace.

Images