KR100321027B1 - 3 step combustion burner of radiant tube - Google Patents

Abstract

PURPOSE: Complete mix of fuel gas and air is carried out to prevent incomplete burning, thereby preventing discharge of harmful gas. CONSTITUTION: A main burner(20) and a pilot burner(30) are installed in one end of a radiant tube. An air distributing plate(60) is provided in front of an air supplying portion(12) by forming a first, second, third air distributing portion(61,62,63). A rear air passing box(70) is fixed to the radiant tube and the air distributing plate. A front air passing box(80) is fixed to the air distributing plate, and is formed with a plurality of holes.

Description

Radiant tube three-stage combustion burner

The present invention relates to a combustion burner mounted on a radiant tube installed in an annealing furnace, and more particularly, incomplete combustion by distributing and combusting air supplied from the outside into primary, secondary and tertiary for mixing with fuel gas. It prevents external emissions of harmful elements and prevents damage to equipment such as burner body, heat exchanger, exhaust gas duct, radiant tube, etc. In addition, it relates to a three-stage combustion burner of radiant tube that can secure enough heat due to complete combustion to improve productivity.

In general, the annealing furnace in steelmaking facilities is the core facility for determining the metal material by heat-treating the cold rolled steel sheet using radiant heat. These annealing furnaces are used to heat the steel to recrystallize and grow the rolled structure to remove internal stresses and to make the structure with appropriate toughness, that is, to remove and soften the internal stresses of the steels. The heating time is maintained sufficiently according to the pre-set temperature according to the added element and then cooled to make the material of the metal desired by the demand.

In general, the structure of the annealing furnace, that is, the heat treatment sequence, includes a preheating part for removing the rolled oil and foreign substances from the strip surface, a direct fired furnace for rapidly increasing the temperature of the strip, a heating table for heating the strip, and a temperature of the heated strip. It is composed of a cracking zone to keep it clean, a slow cooling rod to gradually cool the strip, an overaging zone to prevent aging of the strip, and a quenching zone.

It is called RTS (Radiant Tube Section) in combination with heating zone and cracking zone.

The main equipment of RTS is the main burner which burns fuel gas (COG) and air to supply heat, the pilot burner which is an auxiliary burner to ignite the main burner, and the convection of waste gas burned by the main burner. It consists of radiant tubes that transfer heat to the strip by radiation.

Here, the main burner is ignited by a pilot burner, and the air / fuel gas supplied at the time of combustion is mixed around the main burner's flame gun, and the burned waste gas is set by the suction pressure set. The duct is released into the atmosphere and must be completely mixed to secure sufficient heat during on-line, but the base structure is a problem, causing incomplete combustion factors.

The main burner is ignited using the pilot burner as the ignition source, and heat is transferred to the advanced steel sheet by the heat generated by burning around the flame in the radiant tube. At this time, the air to be supplied is preheated to 350 ° C. at the atmospheric temperature while passing through a heat exchanger and supplied to the main burner, and the fuel gas is supplied with a proportional control in accordance with the air flow rate. The main burner flame which is used for natural gas is burned rapidly after air / fuel gas flows into the rear end of radiant tube and is burned rapidly before complete mixing of air / fuel gas. Secondary combustion of gas occurs in the duct, which causes the pipe to heat up, and the waste gas contains CO gas, which causes environmental pollution.

If the air / fuel gas of the main burner is incompletely mixed, it is impossible to control the furnace at an appropriate temperature, which causes problems of productivity deterioration due to material incompleteness and lack of calories, and instability of the burned flame and secondary combustion. It can cause damage to equipment and shorten life.

The incomplete combustion factor of the main burner is the flow rate of combustion air and fuel gas supplied in the radiant tube, that is, the inlet pressure varies depending on the working conditions. When the suction pressure of exhaust gas in the rear end of radiant tube is changed according to the change of working conditions or the suction pressure is increased to (+), the main flame burner's flame structure is diffused and burned. When the air-fuel ratio is poor due to the simultaneous injection of incoming air, the fuel supplied when the main burner in the same area is extinguished is supplied to the ignited burner in an arbitrary amount, exceeding the maximum flow rate. At low air load and at low load (when a small amount of air / combustion gas is supplied), the suction pressure is 1 As the pressure is fixed, the inlet air passes through the radiant tube and spreads to the bottom of the radiator, and the fuel gas rises to the upper part of the radiant tube and burns, making it impossible to mix air / fuel gas completely. This is due to the combustion in

Figure 1 schematically shows a configuration of a combustion burner for heating the conventional annealing furnace, which is installed on the frame 110 constituting the annealing furnace and located inside the annealing furnace, the U-shaped radiant tube 120 is one side thereof. The main burner 130 and the pilot burner 140 are mounted therein, and the air preheated to an appropriate temperature is supplied to the end side of the main burner 120 through the radiant tube 120, and the main burner ( 130 has an inflator 150 at its end which gradually enlarges its outer diameter as shown in FIG.

The end portion of the flame sprayer 150 is composed of a combustion gas discharge port 152 formed in a shape in which the inner diameter thereof is gradually enlarged and then reduced again.

The operation of the conventional combustion burner having such a configuration is that when the ignition of the pilot burner 140, which is the auxiliary burner, is ignited and ignited by the spark while the fuel is supplied, the fuel of the main burner 130 is ignited. As the automatic valve attached to the combustion gas pipe of the supply line is opened, the fuel gas discharged from the combustion gas discharge port 152 of the flame sprayer 150 is ignited and ignited as it meets the preheated air supplied directly to the discharge side.

In the fuel supply of the main burner 130, the air is supplied at a pressure set in the push blower and is preheated and supplied at a temperature of about 250 to 300 ° C. at an atmospheric temperature while passing through a heat exchanger through a pipe at a flow rate controlled by a flow valve. The fuel gas is supplied at a set ratio corresponding to the air flow rate controlled by the flow valve, and the combusted exhaust gas is discharged to the atmosphere to meet the suction pressure set by the exhaust gas blower.

At this time, the flame combusted by the flame gun 150 of the main burner 130 passes through the lower side of the flame gun 150 while the preheated supply air spreads to the bottom of the radiant tube 120 when the exhaust gas suction pressure is high. When the output is hunted while the output is hunted (when the flow rate of the flow flows in and out of the moment is short), air / fuel gas is not mixed at all around the sprayer 150 and the radiant tube 120 It may be mixed near the heat exchanger at the rear end and burned or secondary burned in the exhaust gas duct to cause premature corrosion of the equipment or to generate soot by incomplete mixing around the flame 150, thereby shortening the life of the pilot burner. , Incomplete combustion causes the local heating of the radiant tube 120 to cause damage to the radiant tube by holes and banding, unburned sediment is generated inside, Also provide a source of anger.

Therefore, in the conventional combustion burner for annealing furnace heating, the burner body portion, the heat exchanger, the exhaust gas duct, and the radiant tube due to the second and third combustion due to incomplete mixing in the flame sprayer 150 of the main burner 130. It causes damage to equipment and decreases the lifespan, and it causes a large amount of harmful components such as CO and NOx, which are impurities in the exhaust gas components, which increases air pollution, and it is not possible to secure sufficient calories due to incomplete combustion. You still have

The present invention is to solve such a conventional problem, by allowing complete mixing of the fuel gas and air to prevent incomplete combustion to prevent the external emissions of harmful elements, to prevent damage to the equipment and to improve the lifetime The aim is to provide a three-stage combustion burner with radiant tubes that ensures sufficient heat due to complete combustion.

1 is a schematic configuration diagram showing a combustion burner of a typical radiant tube

Figure 2 is a cross-sectional view showing in detail the flame retarder which is the main burner front end of the combustion burner according to the prior art

Figure 3 is a cross-sectional view showing a three-stage combustion burner of the radiant tube according to the present invention.

Explanation of symbols on the main parts of the drawings

10 ... radiant tubes

12 ... air inlet

20 ... main burner

30 ... pilot burner

50 ... guide

60 ... Air Distribution Plate

61,62,63 ... Air distribution hole

70 ... rear side air duct

72 ... hole

80 ... front side air duct

82 ... magnification

86 ... reduction

88,89 ... holes

As a technical configuration for achieving the above object, the present invention, the main burner and the pilot burner is installed side by side at one end of the radiant tube, the main burner is to ignite the pilot burner as the ignition source, In the combustion burner which allows the fuel gas to be supplied through the burner side and the preheated air is supplied to the front side of the main burner through the air supply port, the main burner and the radiant tube penetrate the central portion and different concentric circles. A disk-shaped air distribution plate provided on the front side of the air supply port so as to form a plurality of first, second and third air distribution holes on the substrate so as to cross in a direction perpendicular to the radiant tube; The rear side of the hollow cylinder shape which forms a plurality of air induction holes so that one end is fixed integrally between the concentric circle formed by the second air distribution hole and the third air distribution hole of the air distribution plate at the other end. Side air duct; And, integrally fixed between the concentric circles formed by the first air distribution hole and the second air distribution hole at the front side of the air distribution plate, and at the front of the inner end of the main burner, the diameter thereof is enlarged and decreased again. By extending the three-stage combustion burner of the radiant tube, characterized in that it comprises a ;;

Hereinafter, the present invention will be described in more detail.

3 is a cross-sectional view schematically illustrating a three-stage combustion burner of the radiant tube according to the present invention, wherein the main burner 20 and the pilot extend from the outside of one end side of the radiant tube 10 to a predetermined inner position. The burners 30 are installed side by side so that their end positions coincide with each other, and the main burners 20 are ignited using the pilot burners 30 as ignition sources, and fuel gas is supplied through the main burners 20 side. The approximate configuration of allowing the COG to be supplied and supplying preheated air to the front side of the main burner 20 at an appropriate temperature is similar to that of the prior art.

The three-stage combustion burner of the present invention includes an induction means 50 for guiding the flow of air supplied to the combustion part to a flow suitable for combustion, and the induction means 50 is an air distribution plate formed of a disc-shaped member. 60, integrally fixed to the rear side of the air supply plate (60) and integrally fixed to the front side of the air supply plate (60) and the rear side air induction pipe (70) formed of a hollow cylinder cylindrical member. It consists of a front side air guide passage 80 formed of an approximately hollow cylindrical member.

The air distribution plate 60 is a member whose outer diameter is set equal to the inner diameter of the radiant tube 10 so as to be located inside the radiant tube 10 so as to block the front and rear portions thereof so as to perform air distribution described later. As an air supply port 12 to receive preheated air between the end of the radiant tube 10 and the air distribution plate 60, the main burner 20 and the pilot penetrate through a central portion thereof. Allow the burner 30 to be mounted, and the first, second and third air distributions at positions from the outside of the main burner 20 and the radiant tube 30 to the inner surface of the radiant tube 10. The holes 61, 62 and 63 are formed, and the first, second and third air distribution holes 61, 62 and 63 are formed from each other from the center position of the air distribution plate 60. The first air supply hole 61 located on the other circumference and located on the circumference formed on the innermost side is winded. It is formed so as to be spaced apart at regular intervals in the circumferential direction, and the second air supply hole 62 located on the circumference formed at the center portion is preferably formed to be spaced apart at regular intervals in the circumferential direction. The third air supply hole 63 located on the circumference which is formed on the outermost side is also preferably formed to be spaced apart at regular intervals in the circumferential direction thereof.

Since the radiant tube 10 has a length corresponding to the length from the end of the radiant tube 10 to the air distribution plate 60, the inner space of the radiant tube 10 is divided into a main burner side space and an air supply port 12 side space. The rear side air induction pipe 70 to be separated forms a plurality of air induction holes 72 penetrating in the longitudinal direction and the circumferential direction, and these air induction holes 72 are respectively fixed in the longitudinal direction and the circumferential direction. It is preferable to form a spaced apart, such that the diameter of the rear side air duct 60 is formed between the second air distribution hole 62 and the third air distribution hole 63 of the air distribution plate 60. The air flows through the air supply port 12 so that the first and second air distribution holes 61 of the air distribution plate 60 are passed through the air induction hole 72 of the rear air induction pipe 70. 62, and through the air induction hole 72 of the rear air induction passage 70 If not so that it can be separated by flow directly through the third air distribution holes 63 of the air distribution plate 60.

The rear side air induction pipe 80 integrally fixed to the front side of the air distribution plate 60 has a diameter of the rear end portion, which is a portion fixed to the air distribution plate 60, of the air distribution plate 60. The flow of air passing through the first and second air distribution holes 61 and 62 of the air distribution plate 60 by being formed between the first air distribution hole 61 and the second air distribution hole 62 is The rear air induction cylinder 80 is separated into the inside and the outside, respectively, and the rear air induction cylinder 80 maintains a constant diameter from the rear end to the proper position in the center, and then the main burner (the proper position in the center) ( 20) and an enlarged portion 82 which gradually increases in diameter from an end position of the pilot burner 30, and maintains the diameter of the expanded state from the enlarged portion 82 to a predetermined length. A length 84 is formed, and then gradually from the diameter holding portion 84 The diameter is reduced to form a reduction portion 86 which reduces to approximately the original diameter, and is formed to maintain a constant diameter from the reduction portion 86 at a certain length. Of course, the diameter of the diameter retaining portion 84 should be set so as to secure a space that can form an appropriate degree of air flow between the outer surface and the inner surface of the radiant tube 10 and In addition, the enlarged portion 82 forms a plurality of holes 88 and 89 so as to be spaced apart at regular intervals in a circumferential direction at positions having different circumferences from the center, and the holes 88 and 89 are oriented in the direction thereof. It is preferable to be formed horizontally to impart straightness to the flow of air passing therethrough, the inner and outer holes 88 and 89, the second and third air distribution holes of the air distribution plate 60 The air flowing through the (62) and (63) passes, and in particular, the holes 88 and 89 pass through the second air distribution hole 62 of the branch distribution plate 60 because the circumferences formed are different from each other. Most of the air passes through the inner hole 88 and the third air Most of the air passing through the dispensing hole 63 will pass through the outer hole 89. And, more preferably, the portion where the diameter maintaining portion 84 and the contraction portion 86 meet is preferably formed in an arc shape so that the flow of air can be made smoothly.

In addition, the present invention of such a configuration to ensure that a constant flow of air through the central portion of the main burner 20 is always made, which prevents the accident of damaging the facility by the flame back flow through the main burner (20) In addition, the air is continuously supplied while maintaining a constant pressure regardless of the fire ignition at the center of the main burner nozzle hole, so that the output of the burner is supplied at a low flow rate, and the flame stability is maintained. It is effective in preventing sediment formation.

That is, the preheated air supplied to the radiant tube 10 through the air supply port 12 by the induction means 50 of the present invention is separated into three stages of air to form a flow toward the front side of the main burner 20. The amount of fuel gas (COG) supplied by the main burner is determined according to the ratio of the air flow drawn in, and the amount of air is determined according to the output of the burner. Incomplete combustion, in which unstable or unstable fuels are mixed and combusted upon output change, is achieved.

The air supplied to the burner of the present invention is preheated to an appropriate temperature through a heat exchanger installed on the discharge side of the radiant tube 10 and then supplied into the radiant tube 10 via the air supply port 12. About 60% of the total preheated air is supplied to the air induction hole 72 of the rear air induction pipe 70, and the remaining about 40% is the third air distribution hole 63 of the air distribution plate 60. (Of course, this distribution of air can be set in advance by the size of the hole for the air flow formed in each, etc.), and through the air induction hole 72 of the rear air induction pipe 70 About one third of the incoming air (about 40% of the total preheated air) flows to the front side of the main burner 20 through the first air distribution hole 61 of the air distribution plate 60, so that the first combustion air If it is mixed with the fuel gas supplied from the main burner 20 as a role as It is performed for the primary combustion.

Then, 1/3 (about 20% of the total preheated air) of the air that enters through the air induction hole 72 of the rear air induction pipe 70 is the second air distribution hole of the air distribution plate 60. After passing through 62, most of them pass through the inner hole 88 of the front side air duct 80 and the remaining portion passes through the outer hole 89 to serve as a part of the secondary combustion air. Most of the half of the preheated air (20% of the total preheated air) passed through the third air distribution hole 63 of the air distribution plate 60 through 12) is mostly the outside of the front air induction pipe 80. Through the holes 89, the remainder passes through the inner hole 88, and takes charge of the rest of the secondary combustion air, so that the secondary combustion air is enlarged in the cross section of the rear side air induction pipe 80, that is, the combustion flame. Where it spreads, it meets the flame which is first burned and performs the second burn.

Then, one half of the air (about 20% of the total preheated air) that enters through the third air distribution hole 63 of the air distribution plate 60 is the outer surface and the radiant of the rear air induction pipe 80. The air is formed in the space between the inner surface of the tube 10 and moves to the front side of the front air induction pipe 80 to meet the flame which is secondary burned to perform the third burn.

This is more effective in the combustion of the air / fuel gas in the primary, secondary and tertiary to more complete combustion to reduce the environmental harmful components of the combustion gas and increase the amount of heat.

In addition, the secondary air supply in the combustion tube in the inner diameter of the front air induction pipe 80 is increased so that combustion is diffused combustion, and the end portion is composed of a venturi tube type so as to push the flame to the rear end of the radiant tube radiant tube It has the effect of making the temperature distribution of.

According to the burner according to the present invention as described above, by distributing the air supplied from the outside to the primary, secondary and tertiary for mixing with the fuel gas to prevent incomplete combustion to suppress the external emissions of harmful elements In addition, the complete mixing of air / fuel gas will not only damage the burner body, heat exchanger, exhaust gas duct, radiant tube, etc., but also improve the service life. It can have an excellent effect to improve the productivity.

Claims (7)

The main burner 20 and the pilot burner 30 are installed side by side at one end of the radiant tube 10, and the main burner 20 is ignited using the pilot burner 30 as an ignition source. In the combustion burner to allow the fuel gas (COG) to be supplied through the main burner 20 side, and the preheated air is supplied to the front side of the main burner 20 through the air supply port 12, The radiant tube is formed by passing the main burner 20 and the radiant tube 30 in the center and forming a plurality of first, second and third air distribution holes 61, 62 and 63 on different concentric circles. A disk-shaped air distribution plate 60 installed at the front side of the air supply port 12 so as to cross in a direction perpendicular to the direction 10; A plurality of air induction holes 72 are formed so that one end thereof is at the end of the radiant tube 10 and the other end thereof is the second air distribution hole 62 and the third air distribution hole 63 of the air distribution plate 60. Rear air induction pipe 70 of the hollow-cylindrical cylinder shape to be integrally fixed between the concentric circles formed by; And, It is fixed integrally between the concentric circles formed by the first air distribution hole 61 and the second air distribution hole 62 at the front side of the air distribution plate 60, and at the front of the inner end of the main burner 20. The diameter of the radiant tube three-stage combustion burner, characterized in that it comprises a; enlarged and reduced again, the front side air induction tube (80) formed a plurality of holes (88, 89) in the diameter enlarged portion. The method of claim 1, wherein the enlarged and reduced diameter of the front air induction tube 80 is enlarged portion 82 and the radiant tube 10 is continuous to the enlarged portion 82 so that the diameter is gradually enlarged It is characterized in that it consists of a diameter retaining portion 84 to maintain a predetermined interval between the) and the reduction portion 86 is continuous to the diameter holding portion 84 and gradually reduced in diameter to return to the original state Three stage burner of radiant tube. 3. The radiant tube of claim 2, wherein the connecting portion of the enlarged portion 82, the diameter maintaining portion 84, and the reduced portion 86 is formed in an arc shape so that the flow of air can be made smoothly. 3-stage combustion burner. The three-stage combustion burner of a radiant tube according to claim 1, wherein the holes (88) (89) of the front side air guiding tube (80) are located on different concentric circles. 5. The method of claim 1 or 4, wherein the direction through which the holes 88 and 89 of the front side air duct 80 pass is formed to be parallel to the longitudinal direction of the radiant tube 10 so that the air flow is straight. Three-stage combustion burner of the radiant tube, characterized in that to give. 2. The holes 88 of the first, second and third air distribution holes 61, 62, 63 and the air induction hole 72 and the front air induction pipe 80. (89) is a three-stage combustion burner of the radiant tube, characterized in that formed on the concentric circles each formed at regular intervals in the circumferential direction. The three-stage combustion burner of the radiant tube according to claim 1, wherein the fixed air is supplied through the main burner (20).

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