JP2010190483A - Long flame lng burner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a long flame LNG (liquefied natural gas) burner using LNG contributing to reduction of CO<SB>2</SB>gas emission as a fuel and stably forming long flame in a furnace similarly as a conventional oil burner. <P>SOLUTION: This long flame LNG burner includes an outer cover 1 having a combustion air supply port, a cylindrical main pipe 2 for supplying LNG fixed to a central position of the outer cover, and a core pipe 3 disposed at an outer periphery of the main pipe 2. A ring-shaped air nozzle 11 is formed between an outer peripheral face of a tip section of the core pipe 3 and a tip of the outer cover 1. A plurality of through-holes 12 for blowing the combustion air into the core pipe 3 as swirl flow, are formed on a front sidewall of the core pipe 3. The combustion air blown as the swirl flow into the core pipe from the through-holes 12 is mixed with LNG supplied from the main pipe 2 to form the spun swirl flame. Further its outer periphery is surrounded with the cylindrical airflow jetted from the air nozzle 11 to form the stable long flame. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a long flame LNG burner suitable for installation in a tunnel furnace for firing insulators and other ceramic products and ceramic products.

  A large number of burners are installed on the side walls of the tunnel furnace for firing ceramic products and ceramic products to heat the products to be fired loaded on the cart. Since a tunnel furnace that mass-produces a relatively large product such as an insulator has a large width, a long flame burner is necessary to sufficiently fire a fired product loaded in the center of the carriage. Further, if there is no momentum even with a long flame, the tip of the flame faces upward, and the products to be fired loaded on the lower part of the carriage cannot be sufficiently fired.

  Therefore, conventionally, an oil burner using light oil or the like as fuel is used, and fuel oil is injected at high speed from a central oil gun at a small spray angle, and the primary air supplied from the outer periphery is swirled to give a direction of flame. The desired long flame was formed by improving the property. One example thereof is described in Patent Document 1.

JP-A-6-18809

However, in response to recent social demands to reduce CO ₂ gas emissions, fuel changes to replace the factory fuel from oil to LNG are in progress, and it is necessary to replace the burner fuel in the tunnel furnace from conventional light oil to LNG. ing. This makes it possible to reduce the CO ₂ gas emission from the factory by about 10%.

  However, LNG has a smaller calorific value per unit volume than oil, so a gas gun (main pipe) with a larger cross-sectional area than the oil burner oil gun is required to obtain the same calorific value as the oil burner. And However, due to the structure of the existing furnace body, it is difficult to enlarge the outer diameter of the entire burner. For this reason, the amount of combustion air supplied from the outer periphery of the gas gun is likely to be insufficient, and the ability to wrap the flame is reduced, so that the flame tends to spread above the conventional oil burner and rise upward, and at the bottom of the carriage There has been a problem that the stacked products to be fired cannot be sufficiently fired.

Accordingly, an object of the present invention is to provide a long flame LNG burner that uses LNG that contributes to CO ₂ gas emission reduction as a fuel and can stably form a long flame similar to that of a conventional oil burner in a furnace. It is to be. Another object of the present invention is to provide a long flame LNG burner that can greatly change the m value and perform both reduction combustion and oxidation combustion. Note that the m value means an excess air coefficient, where m = 1 is the theoretical air ratio.

  The long flame LNG burner of the present invention made in order to solve the above-mentioned problem is provided with a combustion air supply port at the base, a tapered outer tapered outer cover, and an LNG fixed at the center position of the outer cover. It consists of a cylindrical main pipe for supply and a core pipe provided on the outer periphery of the main pipe, and the outer peripheral surface of the tip of the core pipe is tapered and has a ring shape between the tip of the outer cover. An air nozzle is formed, and a plurality of through holes are formed in the front side wall of the core tube to blow combustion air into the core tube as a swirl flow. A mixing chamber for mixing the supplied LNG with the combustion air blown as a swirling flow is formed, and a swirling flame ejected from the tip of the core tube is formed into a cylindrical shape ejected from the ring-shaped air nozzle. Enveloped by air flow to form a long flame It is characterized in.

  As in claim 2, it is preferable that the core tube is disposed on the outer periphery of the main tube so as to be able to advance and retreat, and the area of the ring-shaped air nozzle formed between the outer cover and the tip of the outer cover can be adjusted. Further, as in claim 3, the core tube is disposed so as to be able to advance and retract on the outer periphery of the main tube, and when retracted, a plurality of through holes formed in the front side wall of the core tube are sequentially closed by the main tube, It is preferable to have a structure in which the amount of combustion air blown in as a swirl flow is reduced. Further, as in claim 4, it is preferable to make the pressure of the combustion air higher than the pressure of LNG.

  The burner of the present invention is formed at the distal end portion of the core tube by blowing combustion air supplied into the outer cover as a swirl flow into the core tube from a plurality of through holes formed in the front side wall of the core tube. Mix with LNG supplied from the main pipe in the mixing chamber. For this reason, LNG is sufficiently mixed with the combustion air and ejected as a swirling flame with a strong spin. In addition, since the LNG and the combustion air are mixed and ejected from the tip of the core tube, the ejection speed is further increased, and the speed of the spin flame is increased and the long flame can be stably formed. Further, since this swirling flame is enveloped by a cylindrical air flow ejected from a ring-shaped air nozzle and the spread of the flame is prevented, a long flame having a desired length can be stably formed.

  Further, as in the second aspect of the present invention, if the core pipe is disposed on the outer periphery of the main pipe so as to be able to advance and retreat and the area of the ring-shaped air nozzle can be adjusted, the amount of combustion air can be freely changed. The above-described m value can be changed to perform reduction combustion or oxidation combustion. Furthermore, if the structure is such that when the core tube is retracted, a plurality of through holes formed in the front side wall of the core tube are sequentially closed by the main tube as in the invention of claim 3, the core tube is retracted and burned. When the amount of air used is increased, the amount of air flowing into the mixing chamber from the through hole is decreased, and the LNG concentration of the mixture is increased. Thereby, the ignitability of the swirling flame ejected from the tip of the core tube can be enhanced, and the flame can be prevented from being blown out.

It is a center longitudinal cross-sectional view which shows embodiment of this invention. It is a top view of a core pipe. It is sectional drawing of a core pipe. It is a center longitudinal cross-sectional view which shows the state which retracted the core pipe. It is sectional drawing of the tunnel furnace which installed the burner of this invention.

  Embodiments of the present invention will be described below. As shown in FIG. 1, the long flame LNG burner of the present invention is a heat-resistant metal burner comprising an outer cover 1, a cylindrical main pipe 2 for supplying LNG, and a core pipe 3. The outer cover 1 has a substantially cylindrical shape as a whole, and is provided with a combustion air supply port 4 at a base portion thereof, and a distal end portion 5 thereof is narrowed in a tapered shape. The main pipe 2 is fixed on the central axis of the outer cover 1 and is entirely cylindrical, and its base is an LNG supply port 6. The length of the main pipe 2 is shorter than that of the outer cover 1. The pressure of LNG supplied from the LNG supply port 6 is 700 to 800 mm water column, and the pressure of combustion air supplied from the combustion air supply port 4 is higher than this, for example, 900 to 1000 mm water column.

  The core tube 3 is provided so as to be able to rotate and slide on the outer periphery of the main tube 2, and as shown in FIG. 2, the protrusion 7 a of the handle 7 is formed in the recess 3 a provided at the base end portion of the core tube 3. Is engaged. Therefore, the core tube 3 can be rotated from the outside of the outer cover 1 by rotating the handle 7. As shown in FIG. 2, a spiral groove 8 is formed in the vicinity of the base portion of the core tube 3, and a pin 9 protruding from the outer periphery of the main tube 2 is fitted into the spiral groove 8. For this reason, when the core tube 3 is rotated by the handle 7, the core tube 3 can move back and forth in the axial direction with respect to the main tube 2 by a small distance.

  The tip of the core tube 3 extends forward beyond the tip of the main tube 2. The outer peripheral surface 10 of the distal end portion is tapered, and a concentric ring-shaped air nozzle 11 is formed between the inner peripheral surface of the distal end portion 5 of the outer cover 1. As described above, since the core tube 3 can move back and forth in the axial direction with respect to the main tube 2 by a small distance, when the core tube 3 is moved forward, the cross-sectional area of the air nozzle 11 is reduced and the amount of combustion air is reduced. Conversely, when the core tube 3 is retracted, the cross-sectional area of the air nozzle 11 increases and the amount of combustion air increases. As a result, the m value can be greatly changed, and both reduction combustion and oxidation combustion can be performed. FIG. 4 shows a state in which the core tube 3 is retracted.

  A plurality of through holes 12 are formed in the front side wall of the core tube 3. As shown in FIG. 3, these through holes 12 are formed in a substantially tangential direction, and the combustion air supplied from the combustion air supply port 4 to the inside of the outer cover 1 is swirled in the core tube 3. It comes to be blown. As described above, the distal end portion of the core tube 3 extends forward beyond the distal end portion of the main tube 2, and the inside is a mixing chamber 13 of combustion air and LNG. For this reason, the combustion air that has flowed into the mixing chamber 13 from the through-hole 12 is uniformly stirred with LNG while swirling at a high speed, and is ejected as a swirling flame with a strong spin from the tip of the core tube 3. .

  The inner peripheral surface of the distal end portion of the core tube 3 is a core tube nozzle 15 having a shape that is once narrowed to the minimum diameter by the throat portion 14 and then expands toward the distal end again. The air-fuel mixture is ejected from the core tube nozzle 15 in a state where a strong spin is applied to form a swirling flame. However, as shown in FIG. 4, combustion air is ejected from the air nozzle 11 so as to wrap around the outer periphery thereof. , The outward spread is suppressed. For this reason, a stable long flame can be formed by the direction stabilizing effect by the spin and the wrapping effect by the combustion air. Moreover, since the pressure of the combustion air is higher than the pressure of the LNG as described above, the LNG is ejected while receiving the suction action by the high-speed combustion air ejected from the air nozzle 11, and a more stable long flame is produced. Can be formed.

  As described above, when the core tube 3 is moved backward, the plurality of through holes 12 formed in the front side wall of the core tube 3 are sequentially closed by the main tube, and the amount of combustion air blown into the core tube as a swirling flow Is squeezed. As described above, when the core tube 3 is retracted and the cross-sectional area of the air nozzle 11 is increased, the amount of combustion air flowing into the mixing chamber 13 is suppressed and a reducing flame excellent in ignitability is produced. This is to prevent the flame from blowing out.

  The burner of the present invention can change the m value to perform oxidation combustion and reduction combustion, but can form a long flame in any combustion state. The reason will be described below. In general, in combustion in the atmosphere, as the amount of gas increases relative to the amount of combustion air, the flame becomes longer. This is because although the flame propagation speed does not change, the gas ejection speed increases, so the proportion of gas that ignites at a position farther from the nozzle increases, and the mixing state of the gas and combustion air also deteriorates. This is because the ignition is delayed. That is, in the case of reductive combustion with a small m value, a long flame can be formed relatively easily. On the other hand, in the case of oxidation combustion with a large m value, it is difficult to form a long flame, but in the present invention, a stable long flame is formed by the above-described effect of stabilizing the direction by spin and the effect of wrapping by combustion air. be able to. Moreover, as described above, in the case of oxidative combustion, a part of the through hole 12 is closed to reduce the amount of air in the mixing chamber to form a reducing flame, and then the reducing flame is formed with air from the air nozzle 11. By burning while enveloping, it is possible to stably form a vigorous long flame.

  In addition, although it is necessary to manipulate the calorific value of a burner for temperature adjustment, if calorific value is increased during oxidative combustion, calorific value will increase. This tends to make the flame longer. In order to increase the amount of heat generated by the burner during the reduction combustion, the amount of combustion air may be increased.

As described above, the long flame LNG burner of the present invention uses LNG that can contribute to the reduction of CO ₂ gas emission as a fuel, while the outer periphery of the swirling flame subjected to strong spin is ring-shaped air. By enveloping with the combustion air flow ejected from the nozzle 11, a stable long flame similar to that of the oil burner can be formed. Therefore, if the long flame LNG burner of the present invention is installed on the side wall of the tunnel furnace 20 as shown in FIG. 5, the fired product loaded at the lower part of the carriage 21 can be obtained without the tip of the flame rising upward. Can be fired evenly. In addition, by rotating the handle 7, it is possible to change the m value to perform reduction combustion or to perform oxidation combustion.

DESCRIPTION OF SYMBOLS 1 Outer cover 2 Main pipe 3 Core pipe 4 Combustion air supply port 5 Tip part 6 LNG supply port 7 Handle 7a Protrusion 8 Spiral groove 9 Pin 10 Tip part outer peripheral surface 11 Air nozzle 12 Through-hole 13 Mixing chamber 14 Throat part 15 Core Pipe nozzle 20 Tunnel furnace 21 Bogie

Claims (4)

  A combustion air supply port is provided at the base, and an outer cover having a tapered tapered tip, a cylindrical main pipe for supplying LNG fixed at the center position of the outer cover, and an outer periphery of the main pipe. The outer peripheral surface of the distal end portion of the core tube is tapered, and a ring-shaped air nozzle is formed between the outer cover and the front side wall of the core tube. A plurality of through-holes are formed in the core tube as a swirling flow, and a mixing chamber for mixing the LNG supplied from the main tube with the combustion air blown as the swirling flow is formed at the tip of the core tube. A long flame LNG burner characterized in that a long flame is formed by wrapping a swirling flame ejected from a tip portion of a core tube with a cylindrical air flow ejected from the ring-shaped air nozzle. .   The long tube according to claim 1, wherein the core tube is disposed on the outer periphery of the main tube so as to be movable back and forth, and the area of a ring-shaped air nozzle formed between the outer tube and the tip of the outer cover can be adjusted. Flame LNG burner.   The core tube is disposed so as to be able to advance and retreat on the outer periphery of the main tube, and when it is retracted, a plurality of through holes formed in the front side wall of the core tube are sequentially closed by the main tube, and combustion is blown into the core tube as a swirling flow The long flame LNG burner according to claim 1, wherein the air quantity is reduced.   The long flame LNG burner according to claim 1, wherein the pressure of the combustion air is made higher than the pressure of the LNG.

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