JP2005003360A - Tubular flame burner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tubular flame burner enabling high load combustion, having a wide regulation range for combustion quantity, being compact and generating only a small amount of harmful matter. <P>SOLUTION: This burner has a tubular combustion chamber 10 with one open end. A nozzle 11 for blowing in oxygen-containing gas is provided to the other end of the combustion chamber 10 toward the tangent line direction of the inner wall surface. A liquid fuel injection valve 12 is provided onto the same peripheral surface as the position whereon the nozzle is arranged. Since simple and stable flame is thus formed in a high speed turning flow, high load combustion can be realized. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an oil burner provided in a furnace or a combustor.

Conventional oil burners are roughly classified into a spray type and a pre-evaporation type. As a spray type burner, liquid fuel is pressurized and sprayed from the nozzle at high speed, atomized and burned, liquid fuel is sprayed with a stream of pressurized air, atomized and burned, etc. The fuel is injected downstream of the burner (see, for example, Patent Document 1). Further, the pre-evaporation type burner heats and gasifies the liquid fuel in advance and then mixes it with air and burns it. The fuel is injected in the burner. In these types of burners, the flame is formed in front of the burner.
JP 58-75612 A

  However, the conventional burner has several problems, and the main ones are as follows.

  Since a flame is formed in front of the tip of the burner, a large space for combustion must be secured in front of the burner, and the combustion equipment becomes large. Furthermore, when the adjustment range of the combustion amount is narrow and the combustion amount needs to be changed significantly, a plurality of burners must be installed, and the operation becomes complicated and the combustion facility becomes larger.

Also, depending on the combustion conditions, the production of harmful substances such as NO _x may increase, unburned components such as hydrocarbons may be discharged, soot may be generated, and this may become one of the sources of environmental pollution. Is done.

  An object of the present invention is to provide a tubular flame burner that is capable of high-load combustion, has a wide range of adjustment of the combustion amount, is miniaturized, and generates less harmful substances.

  In order to achieve the above object, in the first invention, a tubular combustion chamber having an open end is provided, and a nozzle that blows oxygen-containing gas into the other end of the combustion chamber is tangential to the inner wall surface. A liquid fuel injection valve is provided on the same peripheral surface as the position where the nozzle is disposed.

  In the second invention, a part of the combustion chamber is formed in a double tubular shape, a nozzle for injecting an oxygen-containing gas into the outer tube is provided toward the tangential direction of the inner wall surface, and the inner tube is provided in the tube axis direction. A plurality of slits formed along the same circumferential surface are provided, and an injection valve for spraying liquid fuel into the inner pipe is disposed.

  In 3rd invention, in 1st invention or 2nd invention, it consists of gaseous fuel and oxygen-containing gas upstream from the position where the nozzle which blows in oxygen-containing gas, and the injection valve of liquid fuel are arranged A nozzle for blowing a premixed gas or a nozzle for blowing gaseous fuel and a nozzle for blowing an oxygen-containing gas are provided.

  In the fourth invention, in the first invention or the second invention, the other end portion of the combustion chamber is provided with a spacer movable in the tube axis direction.

  In the fifth invention, in any one of the first to fourth inventions, a heater is disposed in an oxygen-containing gas supply line connected to a nozzle for blowing the oxygen-containing gas, and the oxygen-containing gas at the outlet of the heater is disposed. A device for adjusting the temperature is provided.

  In a sixth invention, in any one of the first to fifth inventions, a thermometer for measuring the inner wall temperature of the downstream end of the combustion chamber is provided, and based on the detected value of the thermometer, the liquid A control mechanism is provided that is configured to regulate the flow rate of the fuel and / or oxygen-containing gas.

  In the seventh invention, in any one of the first to sixth inventions, the downstream portion of the combustion chamber has a shape whose diameter is reduced toward the open end.

  In an eighth invention, in any one of the first to seventh inventions, at least a part of the inner wall of the combustion chamber is formed of a refractory.

  In a ninth invention, in any one of the first to seventh inventions, a cooling jacket is provided in at least a part of the combustion chamber.

  In a tenth aspect of the invention, in any one of the first to seventh aspects, a cooling jacket is provided on the exhaust gas exhaust side of the combustion chamber from the position where the liquid fuel injection valve is disposed. The part is formed in a double tube, and a nozzle for supplying an oxygen-containing gas serving as a cooling fluid to the outer tube of the part formed in the double tube is provided, and the combustion chamber is slit along the tube axis direction. A shape-like opening is provided, and oxygen-containing gas is blown into the combustion chamber from this opening.

  The liquid fuel used in the present invention is preferably one that vaporizes at a relatively low temperature, such as kerosene, light oil, alcohol, and A heavy oil.

  In the present invention, the oxygen-containing gas refers to a gas that supplies oxygen for combustion, such as air, oxygen, oxygen-enriched air, oxygen / exhaust gas mixture.

  According to the present invention, since a simple and stable flame is formed in a high-speed swirling flow, high-load combustion is possible. In addition, since the combustion amount adjustment range is wide, a single burner can handle a wide range of combustion amounts. Further, since a flame is formed in the burner, a space for combustion is not required in front of the burner, and downsizing of the combustion facility is achieved.

Moreover, since the temperature variation of the combustion exhaust gas is small, the formation of a local high temperature region can be avoided, and the oxygen supply ratio can be lowered, so there is very little generation of harmful gases such as NO _x and almost no soot generation. As a result, there is almost no gas that is discharged unburned, and low pollution of exhaust gas is achieved.

  1 and 2 are views showing a first example according to the embodiment of the present invention. FIG. 1 is a side view with a part cut away, and FIG. 2 is a cross-sectional view taken along the line AA in FIG. is there. Reference numeral 10 denotes a tubular combustion chamber, one end of which is opened to serve as a discharge port for combustion exhaust gas. A slit that is long along the tube axis direction is formed at the other end, and a nozzle 11 that blows oxygen-containing gas is provided by connecting to the slit. The nozzle 11 is provided toward the tangential direction of the inner wall surface of the combustion chamber 10, and a swirling flow is formed in the combustion chamber 10 by blowing oxygen-containing gas. Further, the nozzle 11 has a flat tip portion and a reduced opening area so that an oxygen-containing gas is blown at a high speed. At this time, the oxygen-containing gas is supplied after being preheated.

  Further, a liquid fuel injection valve 12 is provided on the same peripheral surface as the position where the nozzle 11 is disposed, and the liquid fuel is injected during the swirling flow of the oxygen-containing gas. The injection valve 12 in this embodiment is one that atomizes liquid fuel together with a stream of pressurized air (a two-fluid injection valve), and a liquid fuel pipe and an air pipe are connected to the injection valve 12. . 13 is a spark plug.

  Further, a gaseous fuel nozzle 14 for blowing a premixed gas composed of gaseous fuel and air is provided upstream of the position where the nozzle 11 for blowing oxygen-containing gas and the injection valve 12 for liquid fuel are arranged. The gaseous fuel nozzle 14 is provided toward the tangential direction of the inner wall surface of the combustion chamber 10, and a swirling flow is formed in the combustion chamber 10 by blowing.

  In the burner configured as described above, when an oxygen-containing gas is blown from the nozzle 11 to form a swirling flow and liquid fuel is injected from the injection valve 12, the liquid fuel starts to evaporate, and the droplets are vaporized or dropped. Becomes even finer. When ignited in such a state, the injected liquid fuel burns in the same manner as gaseous fuel.

  In the combustion chamber 10, fluids are stratified by density differences, and layers of different densities are formed on both sides of the flame. That is, a high-temperature combustion gas exists on the shaft center side where the swirling speed is low, and an unburned gas or a gas containing unvaporized droplets exists on the inner wall side of the combustion chamber where the swirling speed is high. Further, in the vicinity of the inner wall, the turning speed exceeds the flame propagation speed, so that no flame is formed. For this reason, a flame is generated in a tubular shape in the combustion chamber 10. Reference numeral 50 denotes a tubular flame. The gas in the combustion chamber 10 flows to the downstream side while swirling, and during that time, the gas and droplets on the inner wall side sequentially burn and move to the axial center side and are discharged from the open end. In addition, since unburned gas exists in the vicinity of the inner wall of the combustion chamber, the wall surface of the combustion chamber 10 does not reach a high temperature due to direct heat transfer.

  Also, on the upstream side of the liquid fuel injection valve 12, the gaseous fuel blown from the nozzle 14 burns to generate a tubular flame. The gaseous fuel nozzle 14 serves as a pilot burner and also serves to promote evaporation when liquid fuel is being injected. Furthermore, when using liquid fuel with poor ignitability, it is possible to ignite reliably by injecting the liquid fuel after injecting the premixed gas fuel / air blown from the nozzle 14.

  1 and 2, a two-fluid injection valve is used as the liquid fuel injection valve. However, the liquid fuel injection valve does not necessarily have to be a two-fluid injection valve. A pressure spray type may be used. However, since the combustibility is further improved when the liquid fuel droplets become finer, a more preferable injection valve is a two-fluid injection valve.

  1 and 2, in order to form a tubular flame upstream of the position where the liquid fuel injection valve 12 is disposed, a gaseous fuel nozzle 14 for blowing a premixed gas composed of gaseous fuel and air is used. However, what forms a tubular flame with gaseous fuel does not have to be premixed, and gaseous fuel and air may be blown from separate nozzles.

  The burner having the above configuration has the following advantages. Since combustion is completed in the combustion chamber 10 and no flame exists outside the combustion chamber 10 (outside the burner), it is not necessary to secure a combustion space in front of the burner.

  Further, since there is no flame outside the burner, even if a flow field is formed at the introduction destination of the combustion exhaust gas, it does not affect the flame in the burner and it is not necessary to provide a flame holder or the like.

  Even though the liquid fuel is blown together with the oxygen-containing gas at a high speed, the center portion in the combustion chamber 10 has a small swirl speed, and the flame is stabilized here. A stable flame is formed, and the fuel can be burned lean or rich. Further, since the flow field is formed so that all the supplied oxygen-containing gas and fuel pass through the flame zone, the raw gas is not directly mixed into the exhaust gas.

  And the following advantages are added by forming a stable and simple flame.

  The variation in the temperature of the exhaust gas discharged is small, and the temperature of each part in the introduction destination of the combustion exhaust gas is maintained in a state where there is no variation.

  Oxygen utilization efficiency can be increased, and in this connection, it is not necessary to supply extra air, so that high-temperature combustion gas can be generated. Further, since combustion can be performed even under conditions where the fuel gas component is very lean or rich, the stable combustion range of the burner itself can be widened, and the selection range of the combustion exhaust gas temperature can be widened.

Since the temperature variation of the combustion exhaust gas is small and no local high temperature part is generated during combustion, the production amount of harmful substances such as NO _x is small.

  Since the mixing property of fuel and oxygen is good and a local low temperature region is not formed, the residual amount of unburned hydrocarbons and the like is not very small, and soot is hardly generated.

  FIG. 3 is a diagram showing a second example according to the embodiment of the present invention, and FIG. 4 is a cross-sectional view taken along the line BB in FIG. 3 and 4, the parts described in FIGS. 1 and 2 are denoted by the same reference numerals and description thereof is omitted. In this embodiment, a part of the combustion chamber 10 is composed of an outer tube 15 and an inner tube 16 and is formed in a double tube shape. The portion formed in this double tube is a fuel blowing portion, and the outer tube 15 is provided with a nozzle 11 for blowing oxygen-containing gas toward the tangential direction of its inner wall surface.

  The inner pipe 16 is provided with a plurality of circumferential slits 17 formed along the pipe axis direction. The slits 17 serve as inlets for the gas blown from the nozzle 11 into the combustion chamber 10. It has become. The slits 17 are arranged at equal intervals with respect to the circumferential direction, or are arranged at symmetrical positions.

  The slit 17 is provided with the gas blowing direction toward the tangential direction of the inner wall surface of the inner tube 16, and the gas blown from the nozzle 11 to form a swirl flow inside the outer tube 15 is again slit 17. Therefore, a swirling flow is also formed in the inner pipe 16 by blowing in the tangential direction of the inner wall surface. Further, an injection valve 12 for spraying liquid fuel into the pipe is arranged in the inner pipe 16 so that the liquid fuel is injected into the oxygen-containing gas that is blown from the slit 17 and forms a swirling flow. It has become.

  In the burner configured as described above, the liquid fuel is injected into the swirling flow of the oxygen-containing gas blown from a plurality of locations in the inner pipe 16, so that the mixing of the liquid fuel and the oxygen-containing gas is promoted and the combustibility is improved. To do. Further, a nozzle 11 for blowing oxygen-containing gas into the outer tube 15 is provided, and the inner tube 16 is always covered with the blown oxygen-containing gas, so that the inner tube 16 is self-cooled. For this reason, even if it heats with the flame which exists in the inside, or the radiant heat of the hot gas of the axial center side, the temperature rise of the inner tube 16 is suppressed.

  FIG. 5 is a view showing a third example according to the embodiment of the present invention, and is a side view with a part cut away. In FIG. 5, portions described in FIGS. 1 to 2 are denoted by the same reference numerals and description thereof is omitted. In this embodiment, a spacer 18 is inserted at the upstream end of the combustion chamber 10. The spacer 18 slides on the combustion chamber 10 and can move in the tube axis direction. Reference numeral 19 denotes a spacer driving device. For this reason, if the spacer 18 is moved to the downstream side, the combustion section in the combustion chamber 10 is shortened. When the spacer 18 is moved to a part of the position where the liquid fuel injection valve 12 is installed, if only the injection valve at that position is fully closed, the liquid fuel injection is hindered. There is nothing.

  According to the burner having such a configuration, even if the flame length is shortened when the combustion amount is reduced, the position where the flame is formed is adjusted by appropriately moving the spacer 18 to the downstream side, and the flame is reduced. The end can always be formed at the downstream end of the burner. For this reason, the generation | occurrence | production of the problem that the downstream end part of the combustion chamber 10 is exposed to high temperature and damaged is prevented.

  FIG. 6 is a diagram showing a fourth example according to the embodiment of the present invention. In FIG. 6, the parts described in FIGS. 1 and 2 are denoted by the same reference numerals and description thereof is omitted. In this embodiment, a heater 20 for preheating the oxygen-containing gas is provided in the oxygen-containing gas supply line connected to the nozzle 11 for blowing the oxygen-containing gas. A combustion exhaust gas is circulated through the heater 20 as a heating fluid, and heat recovery is performed. A temperature adjusting device 21 is provided to adjust the temperature of the heated oxygen-containing gas. The temperature control device 21 includes a thermometer 22 that detects the outlet temperature of the heater 20 and a flow rate control valve 23 for combustion exhaust gas, and is configured to preheat the oxygen-containing gas to a predetermined temperature.

  The heating fluid to be introduced into the heater 20 is not limited to combustion exhaust gas, and may be a high-temperature gas obtained by separately burning, and the ignitability of liquid fuel by raising the oxygen-containing gas to a higher temperature. It is desirable to improve. In addition, when adjusting the temperature of the oxygen-containing gas heated by the heater 20, a method of mixing cold air with the heated oxygen-containing gas is adopted instead of adjusting the flow rate of the heating fluid as described above. May be.

  However, the preheating temperature of the oxygen-containing gas needs to be about 600 ° C. as an upper limit. When an oxygen-containing gas of 600 ° C. or higher is blown into the combustion chamber 10, the liquid fuel is pyrolyzed and carbonized in or near the injection valve 12, and soot is likely to be generated.

  FIG. 7 is a diagram showing a fifth example according to the embodiment of the present invention. In FIG. 7, the parts described in FIGS. 1 and 2 are denoted by the same reference numerals and description thereof is omitted. In this embodiment, a thermometer 24 for measuring the inner wall temperature at the downstream end of the combustion chamber 10 is provided, and a signal of a value detected by the thermometer 24 is sent to the arithmetic / controller 25. It is supposed to be. The liquid fuel pipe connected to the injection valve 12 and the oxygen-containing gas pipe connected to the nozzle 11 are provided with flow rate controllers 26 and 27, respectively, which are detected by these flow rate controllers 26. A flow rate signal is sent to the calculation / control unit 25, and control signals are sent from the calculation / control unit 25 to the flow rate controller 26 and the flow rate controller 27.

  By the way, depending on the combustion conditions, the tubular flame tends to attenuate the swirling flow as it goes downstream, and the shape of the flame tends to collapse, the inner wall temperature at the downstream end becomes high, or unburned gas remains. In the burner configured as described above, on the basis of the control signal from the calculation / control unit 25, the liquid fuel is adjusted so that the inner wall temperature at the downstream end becomes a predetermined temperature. The flow rate of the gas and the flow rate of the oxygen-containing gas are adjusted, or the flow rates of the liquid fuel and the oxygen-containing gas are individually adjusted. For this reason, a tubular flame is always formed at the downstream end of the combustion chamber 10 and is maintained in such a length that the flame does not go out of the combustion chamber 10, so that the downstream end is exposed to high temperatures and damaged. Or the problem of unburned gas being discharged is prevented.

  FIG. 8 is a view showing a sixth example according to the embodiment of the present invention, and is a side view with a part cut away. In FIG. 8, the parts described in FIGS. In this embodiment, the downstream portion of the combustion chamber 10 is reduced in diameter toward the open end, and has a tapered shape.

  Thus, if the downstream part of the combustion chamber 10 is made thin, the turning speed at the downstream end part can be increased even if the blowing amount is reduced. For this reason, a normal tubular flame is formed also in the downstream end portion, and the problem that the inner wall of the downstream end portion becomes abnormally high in temperature and is damaged or the composition of the combustion exhaust gas deteriorates does not occur.

  FIG. 9 is a view showing a seventh example according to the embodiment of the present invention, and is a side view with a part cut away. 9, the parts described in FIGS. 1 and 2 are denoted by the same reference numerals and the description thereof is omitted. In this embodiment, the combustion chamber 10 is composed of two parts, the upstream part 10a is made of metal, and the downstream part 10b is made of refractory. The two parts are connected by a flange joint. And this combustion chamber 10 is flange-joined to the opening provided in the apparatus of the attachment destination. Reference numeral 40 denotes an iron skin of a device for attaching a burner, and 41 denotes a refractory lined on the iron skin.

  As described above, when at least the downstream portion of the combustion chamber 10 is formed of a refractory, the flame length is shortened due to the change in the mixing ratio of the liquid fuel and the oxygen-containing gas, and the swirl flow is attenuated to form a tubular shape. Even if the shape of the flame collapses and the downstream side of the combustion chamber 10 becomes high temperature or is heated by radiant heat from the flame or the high temperature gas on the axial center side, damage to the combustion chamber 10 is avoided.

  As a means for preventing damage to the combustion chamber 10 due to fluctuations in the combustion state, at least a downstream portion of the combustion chamber 10 may be a cooling structure in addition to the embodiment shown in FIG. And when selecting the cooling method, it is better to use the air cooling method than the water cooling method. In the case of the water cooling method, the inner wall is excessively cooled, and moisture in the combustion exhaust gas may be condensed on the inner wall surface.

  10, FIG. 11, and FIG. 12 are views showing an eighth example according to the embodiment of the present invention. FIG. 10 is a side view with a part cut away, and FIG. 12 is a cross-sectional view taken along the line DD in FIG. 10 to 12, the portions described in FIGS. 1 to 2 are denoted by the same reference numerals and description thereof is omitted. In this embodiment, a cooling jacket 28 is provided on the combustion exhaust gas outlet side of the combustion chamber 10 from the position where the liquid fuel injection valve 12 is disposed, and this portion is formed in a double tubular shape. ing. A nozzle 30 for supplying an oxygen-containing gas serving as a cooling fluid is provided in a portion of the outer tube 29 formed in the double tubular shape toward the tangential direction of the inner wall surface. In addition, a slit-like opening 31 is provided in the combustion chamber 10 which is an inner tube of a portion formed in a double tubular shape along the tube axis direction, and oxygen-containing gas is blown into the combustion chamber 10 from the opening 31. It is supposed to be. Further, the slit-like opening 31 provided in the combustion chamber 10 is provided toward the tangential direction of the inner wall surface.

  When the nozzle 30 for supplying the oxygen-containing gas is provided toward the tangential direction of the inner wall surface, the flow rate of the oxygen-containing gas flowing on the outer periphery of the combustion chamber 10 is increased, and heat transfer from the combustion chamber 10 is promoted. In addition, the temperature difference in the jacket 28 is reduced. Further, when the opening 31 is provided toward the tangential direction of the inner wall surface of the combustion chamber 10, the oxygen-containing gas blown into the combustion chamber 10 is mixed while swirling, and thus is formed by swirling flow. The phenomenon of disturbing the tubular flame does not occur.

  As described above, when the oxygen-containing gas is supplied as the cooling fluid to the cooling jacket 28, the combustion chamber 10 is cooled, and an abnormal temperature rise due to fluctuations in the combustion conditions as described above is prevented. The heat dissipated from 10 is recovered by the oxygen-containing gas. And since this oxygen-containing gas is blown into the combustion chamber 10 as secondary air, combustion exhaust gas becomes high temperature and generation | occurrence | production of noxious gases, such as CO, is suppressed. For this reason, according to said structure, the tubular flame burner which has the function of energy saving and low pollution can be obtained.

  In the above-described embodiment, the oxygen-containing gas supplied to the jacket 28 is heated and then blown into the combustion chamber 10. The heated oxygen-containing gas is used as a liquid fuel. May be supplied to the blowing nozzle 11 as primary air for burning the gas.

It is a figure which shows the 1st example which concerns on embodiment of this invention. It is sectional drawing of the AA arrow in FIG. It is a figure which shows the 2nd example which concerns on embodiment of this invention. It is sectional drawing of the BB arrow in FIG. It is a figure which shows the 3rd example which concerns on embodiment of this invention. It is a figure which shows the 4th example which concerns on embodiment of this invention. It is a figure which shows the 5th example which concerns on embodiment of this invention. It is a figure which shows the 6th example which concerns on embodiment of this invention. It is a figure which shows the 7th example which concerns on embodiment of this invention. It is a figure which shows the 8th example which concerns on embodiment of this invention. It is sectional drawing of CC in FIG. It is sectional drawing of the DD arrow in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Combustion chamber 10a Upstream part of combustion chamber 10b Downstream part of combustion chamber 11 Nozzle for injecting oxygen-containing gas 12 Liquid fuel injection valve 13 Spark plug 14 Gas fuel nozzle 15 Fuel injection formed in a double tube Outer pipe of the part 16 Inner pipe of the fuel blowing part formed in a double tube 17 Slit provided in the inner pipe 18 Spacer 19 Spacer driving device 20 Heater 21 Temperature control device 22 Thermometer 23 Flow control valve 24 Temperature Total 25 Calculation / control unit 26 Flow controller 27 Flow controller 28 Cooling jacket 29 Outer pipe of cooling jacket 30 Nozzle for supplying oxygen-containing gas to the cooling jacket 31 Opening 40 provided in the combustion chamber inside the cooling jacket 40 Burner Iron shell of the equipment to be installed 41

Claims (10)

  A tubular combustion chamber having an open end is provided, and a nozzle for blowing an oxygen-containing gas at the other end of the combustion chamber is provided in the tangential direction of the inner wall surface, and the same position as the nozzle is disposed A tubular flame burner characterized in that a liquid fuel injection valve is provided on the peripheral surface of the tube.   A part of the combustion chamber is formed in a double tubular shape, and a nozzle for blowing oxygen-containing gas into the outer tube is provided in the tangential direction of the inner wall surface, and the inner tube has a slit formed along the tube axis direction. A tubular flame burner provided with a plurality of injection valves for spraying liquid fuel into an inner pipe while being provided in plural on the same peripheral surface.   A nozzle for blowing a premixed gas composed of gaseous fuel and oxygen-containing gas or a nozzle for blowing gaseous fuel and an oxygen-containing gas are blown upstream of the position where the nozzle for blowing oxygen-containing gas and the injection valve for liquid fuel are arranged. The tubular flame burner according to claim 1 or 2, wherein a nozzle is provided.    The tubular flame burner according to claim 1 or 2, wherein a spacer that is movable in the tube axis direction is provided at the other end of the combustion chamber.    A heater is disposed in an oxygen-containing gas supply line connected to a nozzle for blowing the oxygen-containing gas, and a device for adjusting the temperature of the oxygen-containing gas at the outlet of the heater is provided. Item 5. The tubular flame burner according to any one of Items 4 to 5.   A thermometer for measuring the inner wall temperature at the downstream end of the combustion chamber, and a control configured to adjust the flow rate of the liquid fuel and / or oxygen-containing gas based on the detected value of the thermometer The tubular flame burner according to any one of claims 1 to 5, wherein a mechanism is provided.   The tubular flame burner according to any one of claims 1 to 6, wherein a downstream portion of the combustion chamber has a shape whose diameter is reduced toward an open end.    The tubular flame burner according to any one of claims 1 to 7, wherein at least a part of an inner wall of the combustion chamber is formed of a refractory material.    The tubular flame burner according to any one of claims 1 to 7, wherein a cooling jacket is provided in at least a part of the combustion chamber.   A cooling jacket is provided on the combustion exhaust gas outlet side of the combustion chamber from the position where the liquid fuel injection valve is arranged, and this portion is formed into a double tubular shape. The outer tube is provided with a nozzle for supplying an oxygen-containing gas serving as a cooling fluid, and the combustion chamber is provided with a slit-shaped opening along the tube axis direction, and the oxygen-containing gas is blown into the combustion chamber from this opening. The tubular flame burner according to any one of claims 1 to 7, wherein the tubular flame burner is configured.

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