JP2002323206A - Swirl combustion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a swirl combustion device, in which a higher space heat generation rate is achieved and the generation of NOx is low by applying an improvement to a swing combustion device. SOLUTION: An outer peripheral wall 2 and an inner peripheral wall 3 are cylindrical, and the inner peripheral wall 3 is concentrically arranged inside the outer peripheral wall 2. A plurality of burner holes 9 are provided on the inner peripheral wall 3. Thin (mixed) gas is jetted from the burner holes 9 to form a swirl flame. At the center of a bottom plate 4, burner holes 22 for high concentration gas are provided on la surface and an object 21 containing a low concentration gas jet pipe 26 is provided. High concentration (excessively high) gas, jetted to a combustion chamber 10 from the burner holes 22 for high concentration gas, is mixed with a the burnt gas to be completely burnt due to the swirling force of the burnt gas generated by the combustion of the thin (mixed) gas and the jetting force of low concentration gas from the jet pipe 26 for low concentration gas, so that the space heat generation rate is high. At this time, the high concentration (excessively high) gas is diluted by the burnt gas, so that the production of NOx is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustor, and more particularly to a swirl combustor for generating a swirling flow by injecting a mixed gas of air and fuel in advance into a combustion chamber. INDUSTRIAL APPLICABILITY The combustor of the present invention can be used for any device requiring a heat source, such as a water heater or a boiler.

[0002]

2. Description of the Related Art A swirl combustor is known as one of combustion means having a high space heat generation rate (Japanese Patent No. 28638).
No. 41). The swirling combustor uses a cylindrical combustion chamber, and injects a mixed gas of air and fuel into the combustion chamber to generate a swirling flow therein.

FIG. 12 is a conceptual diagram of a conventional swirl combustor. In the swirl combustor 101, a cylindrical combustion chamber 102
Is used to inject a gas mixture of air and fuel tangentially to the combustion chamber 102. This mixed gas forms a swirling flow in the combustion chamber 102. Inside the combustion chamber 102, a cylindrical swirling flame is generated. The burned gas is discharged to the outside from the opening 103 while turning.

[0004] The swirl combustor 101 exhibits a much higher spatial heat generation rate than a normal combustion system in which a mixed gas is directly injected into the atmosphere from the opening 103. Therefore, it is possible to reduce the size of a device such as a water heater. The swirl combustor 10
1 performs combustion using a strong swirling flow, so that fuel can be burned in a lean state. Therefore, the temperature of the flame can be reduced, and the NO
_x (nitrogen oxides) can be reduced. Further, there is an advantage that a combustion amount throttling ratio (TDR) can be made wider than that of a normal combustor.

[0005]

The swirling combustor 101 has the following features.
As described above, a significantly higher spatial heat generation rate is achieved as compared with a normal combustion method. However, in industry,
There are voices calling for even higher spatial heat rates. In addition, there is an industrial demand to further suppress the generation of NO _x due to combustion as compared with the current situation. Further, in order to constantly and completely burn the fuel and reduce NO _x , there is a need for combustion amount control means for regulating the concentration and flow rate of the fuel. The present invention, in order to meet these requirements, an improvement over the swirl combustor, exhibit higher spatial heat rate, it is an object of the present invention to provide a less swirl combustor generation of the NO _x is.

[0006]

As mentioned above SUMMARY OF THE INVENTION The generation of the NO _x in the industry, there is a demand for further suppressed than the current. Therefore, the present inventor conducted a study by returning to the principle of generating NO _x . NO _{x in the} combustion device
Occurs because nitrogen and oxygen in the air are combined through a combustion reaction in the flame. Here has been conventionally performed, measures to reduce the NO _x, the fuel is combusted in a lean state by lowering the temperature of the flame, NO _x
It suppresses the production reaction. As a result, the generation of NO _x was reduced, but the use of a thin gas mixture reduced the rate of heat generation due to the combustion reaction per unit space in the combustion chamber. There has been an adverse effect that the heat generation rate cannot be sufficiently exhibited.

That is, in the swirl combustor of the prior art, because the fuel concentration in the mixed gas is low, the combustion reaction accompanied by rapid heat generation is almost completed on the swirl flame surface, and heat is generated from the center of the swirl combustor. Has not occurred. Then, the present inventors considered generating heat from a portion near the center of the swirl combustor to improve the space heat generation rate. For also NO _x, it was decided to reduce based on a different principle from the conventional.

The invention according to claim 1, which is completed based on the above concept, comprises a combustion chamber having one end opened, and a first mixing chamber in which air and fuel are mixed at a predetermined ratio in the combustion chamber. Injecting the gas to generate a swirling flow of the mixed gas in the combustion chamber, and further mixing air and fuel at a position different from the inner wall of the combustion chamber at a different ratio from the first mixed gas.
A swirl combustor characterized in that a mixed gas and a low-concentration gas having a lower fuel concentration than the two types of mixed gas are injected.

The invention according to claim 2 is the swirl combustor according to claim 1, wherein the second mixed gas has a higher fuel concentration than the first mixed gas.

[0010] In the swirl combustor of the present invention, the second mixed gas is injected toward the center of the combustion chamber. Therefore, a flame is generated also in the central portion of the swirling flow and generates heat. Also, the second mixed gas is caught in the swirling flame and burns,
The mixed gas burns while being mixed with the burned gas components such as CO ₂ and H ₂ O. Therefore, in the combustion region of the second mixed gas, the flame temperature decreases due to dilution of the burned component. That is, in the swirl combustor of the present invention, by the effect of diluting the burned gas component contained in the swirl flame or the combustion gas,
Generation of the NO _x by the combustion reaction in the second mixed gas is significantly reduced. In other words, the EGR effect (Exhaust Gas Rec
irculation) can significantly reduce the amount of NO _x produced. Further, since the second mixed gas has a lower temperature than the burned gas generated by the combustion of the first mixed gas, its density is higher than that of the burned gas. The mixture of the two mixed gases and the burned gas is promoted, and the combustion is effectively performed.

According to a third aspect of the present invention, the first mixed gas has an excess air ratio of 1 or more, and the second mixed gas has an excess air ratio of 0 or more and less than 1. 2
2. The swirl combustor according to 1.

In the swirl combustor of the present invention, the second mixed gas
The excess air ratio is 0 or more and less than 1. Where there is excess air
The rate indicates the proportion of air contained in the fuel gas.
You. If the excess air ratio is 1.0, the fuel tends to be in the gas.
It contains enough air to burn completely,
When less than 1.0, the amount of air contained in the gas is complete combustion
Less than needed to do. In addition, the excess air ratio is 1.
If it is greater than 0, it is more than the amount of air required for complete gas combustion
This is the case when air is contained. Therefore high concentration gas
Is the mixture of fuel itself or air shortage
Gas. According to the experiment of the inventor, the first mixed gas
Insufficient air in swirling flow of burned gas generated by combustion
When the second mixed gas in the state is injected, NO_xReduces the amount of
A little. The reason for this is that the second mixed gas burns and reduces
Atmosphere generated by the components and the reducing atmosphere formed by the reducing components
NO generated by swirling flame in air_xAnd NO _x
It is probable that the emission concentration was reduced.

According to a fourth aspect of the present invention, there is provided the swirl combustor according to any one of the first to third aspects, wherein the low-concentration gas contains no fuel.

The invention according to claim 5 is characterized in that the low-concentration gas is injected toward the center of the swirling flow, and the second mixed gas is injected from the periphery thereof. A swirl combustor as described in

Since the swirling force at the center of the swirling flow of the burned gas generated by the combustion of the first mixed gas is weak, the mixing of the second mixed gas and the burned gas is insufficient at the center of the swirling flow.
Fuel gas combustion tends to be incomplete. However, when the low-concentration gas is injected toward the center of the swirl flow, the mixing of the burned gas and the second mixed gas is promoted by the injection force of the low-concentration gas even at the center of the swirl flow having a weak swirl force, and Is completely burned. The low-concentration gas may contain no fuel, that is, may be air.

According to a sixth aspect of the present invention, an occupant occupying a part or the entirety of a negative pressure region generated by the swirling flow is provided at the center of the swirling flow, and the low-concentration gas is supplied to the top of the occupying material. The swirl combustor according to any one of claims 1 to 5, wherein the fuel is injected from the vicinity thereof.

[0017] By the invention described in claims 1 to 5 described above, at the same time increasing the heat generation rate at a constant space, it was possible to reduce the NO _x generation amount by the dilution effect of the burned gas. However, in the case where the swirling flow of the burned gas is strong, a backflow occurs due to the circulating flow from the downstream of the combustion chamber, and under the influence of the backflow, the diffusion flame formed by burning the second mixed gas is unstable. And the whole combustion field in the combustion chamber becomes unstable. The invention according to claim 6 addresses this problem, and an occupation material occupying a part or the entirety of the negative pressure region generated by the swirling flow is provided at the center of the swirling flow in the combustion chamber. The pressure gradient in the radial direction of the combustion chamber can be reduced, and the swirling flame surface is prevented from contracting under the influence of the pressure gradient in the radial direction in the combustion chamber, thereby preventing the backflow.
Swirl flame stabilizes.

Further, since the low-concentration gas is injected from the top of the occupation material or from the vicinity thereof, the low-concentration gas is injected near the center of the swirling flow of the burnt gas, and the mixture of the burnt gas and the second mixed gas is mixed. It is promoted and the fuel gas is completely burned. Also,
Occupation thereof vicinity is a high temperature, occupancy was purified by low concentration gas and reduction of increase and NO _x of the heat resistance of the occupation thereof for the vicinity thereof are cooled is achieved.

According to a seventh aspect of the present invention, the first mixed gas, the second mixed gas and the low-concentration gas have a constant amount of air and a constant distribution ratio of air, and the low-concentration gas and the first mixed gas or the low-concentration gas have a constant distribution ratio. The swirl combustor according to any one of claims 1 to 6, wherein the amount of fuel of one of the two mixed gases is constant, and the amount of the other fuel is changeable.

[0020] Since the fuel gas can be supplied at a concentration or flow rate according to the combustion amount required for combustion in the normal combustion range according Invite combustor present invention, constantly stable fuel completely burned, NO _x Emissions can be reduced.

[0021]

Embodiments of the present invention will be described below. (First Embodiment) FIG. 1 is a conceptual diagram of a swirl combustor according to the present embodiment. In FIG. 1, reference numeral 1 denotes a swirl combustor of the present embodiment. The swirl combustor 1 has a cylindrical outer peripheral wall 2,
A cylindrical inner peripheral wall 3 is installed therein, and a through hole is provided in a central portion of the bottom plate 4 of the outer peripheral wall 2 to form a high-concentration gas supply port 5. A pipe is inserted substantially concentrically with the high concentration gas supply port 5 to form a low concentration gas supply pipe 6.

The outer peripheral wall 2 and the inner peripheral wall 3 are both cylindrical, and the inner peripheral wall 3 is arranged concentrically inside the outer peripheral wall 2. Both ends are closed by a flange 7, and a mixed gas supply unit 8 is formed inside. As shown in FIG. 1, the inner peripheral wall 4 is provided with a plurality of flame holes 9 formed by cutting and raising the inner peripheral wall 3 at equal intervals in the generatrix direction and the circumferential direction. A bottom plate 4 is provided at an end of the inner peripheral wall 3 on the gas upstream side, and a combustion chamber 10 is formed by the inner peripheral wall 3 and the bottom plate 4. In addition, a through hole 11 is provided at the center of the bottom plate 4 concentrically with the outer peripheral wall 2 as shown in FIG. Further high-concentration gas inlet 5
A low-concentration gas supply pipe 6 having a smaller radius than the high-concentration gas inlet 5 and being substantially concentric therewith is inserted. However, as shown in FIG. 1C, a low-concentration gas supply pipe 6 having the same diameter as the through-hole 11 is inserted through the through-hole 11, and a plurality of high-concentration gas supply ports 5 are provided near the low-concentration gas supply pipe 6 on the bottom plate 4. The structure provided may be sufficient.

Next, the operation of the swirl combustor 1 of the present embodiment will be described. In the swirl combustor 1 of the present embodiment, three types of gases having different concentrations are used. That is, in the present embodiment, three types of gases are used: an over-concentrated (high-concentration) gas, a lean (mixed) gas, and a low-concentration gas (air). Here, the rich (highly concentrated) gas has an excess air ratio of 0 or more and less than 1, and particularly in the present embodiment, a gas whose air amount is less than a combustible range is used. In addition, the lean (mixed) gas has a higher air content than the rich (high concentration) gas, and the low concentration gas is a gas having an excess air ratio of at least 1 and does not particularly contain any fuel in the present embodiment. Air is used.

First, the lean (mixed) gas is supplied to the mixed gas supply section 8 and is spouted tangentially from a plurality of flame holes 9 provided on the inner peripheral wall 3 to generate a swirling flow. To form a swirling flame. The lean (mixed) gas burns as a swirling flame, and a swirling flow of high-temperature burned gas is generated inside the swirling flame surface. As a specific configuration and operation of the present embodiment, an excess (high concentration) gas with an excess air ratio of less than 1 is supplied from a high concentration gas supply port 5 provided in the bottom plate 4 of the combustion chamber 10, and a low concentration gas is supplied. Low-concentration gas (air) is injected into the combustion chamber 7 from the pipe 6. Here, the high concentration gas supply port 5 and the low concentration gas supply pipe 6 are connected to the bottom plate 4 of the combustion chamber 10.
Is provided at substantially the center of the swirl flame, and the rich (high concentration) gas and the low concentration gas (air) are injected in the axial direction substantially at the center of the swirling flame. In particular, the low concentration gas (air) is injected into the combustion chamber 10 at a position away from the bottom plate 4. In the present embodiment, the low-concentration gas supply pipe 6 protrudes from the bottom plate 4, and the low-concentration gas (air) is injected from the low-concentration gas supply pipe 6 into the center of the combustion chamber 10. This is because the rich (high concentration) gas is mixed with the low-concentration gas (air) prior to mixing with burnt gas, a large amount of the NO _x with a high-temperature flame is prevented from burning while discharging .

Since the temperature of the rich (highly concentrated) gas injected into the center of the swirling flame is low, its density is higher than that of the high-temperature burned gas in the swirling flow. Because of that, it is too concentrated (high concentration)
The gas diffuses due to the difference in density while swirling from the center of the combustion chamber 10 to the outer periphery. In the vicinity of the center of the swirling flow, the swirling force caused by the swirling flame is extremely weak, and the mixing of the burned gas and the rich (highly concentrated) gas is insufficient with the swirling flow alone. Since the low-concentration gas (air) is injected near the center of the swirling flow, the diffusion of the over-concentration (high-concentration) gas is promoted also in this vicinity. The over-concentrated (highly-concentrated) gas burns while rapidly mixing with the components of the burned gas by causing the diffusion effect due to the injection of the low-concentration gas (air) in addition to the diffusion effect due to the density difference.

Here, in the combustion of the rich (high concentration) gas, since a large amount of oxygen remains in the burned gas generated by burning the lean (mixture) gas, the concentration of the rich (high concentration) gas By properly controlling the flow rate and the flow rate, the rich (high concentration) gas is completely burned, and the generation of unburned components is very small. That is, in the swirl combustor 1 of the present embodiment, the rich (high concentration) gas is completely burned by the oxygen remaining in the burned gas generated from the lean (mixed) gas. FIG. 2 is a graph showing the emission limit of unburned components in the first embodiment and the conventional swirl combustor. The swirl combustor according to the present embodiment is more concentrated in the swirl combustor 1 than the conventional combustor. The emission limit area of unburned components is wide on the side (high concentration side) and on the lean side (mixed gas side). That is, the swirl combustor of the present embodiment generates much less unburned components than the conventional one, and the range of settable combustion conditions is wider. The swirl combustor 1 of the present embodiment can completely burn more fuel in a limited space of the combustion chamber 10 as compared with the conventional case in which no rich (high concentration) gas is injected, and By increasing the amount of heat generated per unit time and space, a combustor having the same amount of heat generated can be made more compact.

Further Experiments, swirl combustor 1 of the present embodiment has been found to be those generated amount of the NO _x is small. The reason is that in the swirl combustor 1 of the present embodiment, the rich (highly concentrated) gas is also mixed with the burned gas components CO ₂ and H ₂ O other than residual oxygen by the diffusion effect in the swirl flow. for burning while the generation of the NO _x by the combustion reaction by dilution effect of these burnt gas components are expected to is thereby inhibited. That is, the EG of the burned gas
It is considered that the amount of NO _x produced could be significantly reduced by the R effect. The turning combustor of this embodiment also, once expected NO _x generated in the swirling flame, that it would be being reduced to nitrogen and oxygen in the rich (high concentration) reducing atmosphere formed by the combustion of the gas Is done.

Further, in this embodiment, the enriched (highly concentrated) gas has a low air mixing ratio, and the mixed air amount is less than the combustible range. The reason why the concentration of the over-concentrated (high-concentration) gas is set high is to prevent flashback. That is, since the vicinity of the bottom plate 4 of the combustion chamber 10 is exposed to the high temperature burned gas and heated, when the flow rate of the rich (high concentration) gas is small, a flashback upstream is likely to occur. Therefore, in the present embodiment, the flashback is prevented by setting the excess air ratio of the rich (highly concentrated) gas to be smaller than the excess air ratio in the combustible range under normal conditions.

(Second Embodiment) The swirl combustor 1 of the first embodiment described above enriches (highly concentrated) gas toward the swirl flow space of burned gas generated by burning lean (mixed) gas. From the high-concentration gas supply port 5 and the low-concentration gas (air) from the low-concentration gas supply port 6 into the combustion chamber 10. Therefore, the above-mentioned swirling combustor sufficiently mixes the rich (high concentration) gas and the burned gas by the diffusion effect caused by the difference in density between the rich (high concentration) gas and the burned gas, and converts the low concentration gas (air) into a gas. is intended to suppress the occurrence of the unburned components by causing additional combustion is ejected, at the same time increasing the heat generation rate in the same volume space, it is to reduce the NO _x generation amount by the dilution effect of the burned gas did it.

However, under the condition of a large amount of combustion, the inflow of the rich (high concentration) gas supplied from the high concentration gas supply port 5 into the swirling flow of the burned gas also increases. If a large amount of rich (high concentration) gas is supplied at a time in the swirling flow, it becomes difficult to mix the rich (high concentration) gas into the burnt gas quickly due to the swirling force of the burnt gas. There was a problem that complete combustion was not possible and unburned components were likely to be generated. Further, when the swirling flow of the burned gas is strong, a backflow due to the circulating flow may occur from the downstream side of the combustion chamber 10. Under the influence of the backflow, the diffusion flame formed by burning the rich (highly concentrated) gas tends to become unstable, and the entire combustion field in the combustion chamber 10 becomes unstable. occured. Therefore, the second aspect of the present invention
The embodiment is improved to further promote the mixing of the rich (high concentration) gas and the burned gas, to prevent incomplete combustion, and at the same time, to prevent backflow due to circulating flow.

FIG. 3 is a longitudinal sectional view of a swirl combustor according to a second embodiment of the present invention. Reference numeral 20 in FIG. 3 denotes a swirl combustor according to the present embodiment. The swirl combustor 20 has substantially the same structure as the swirl combustor 1 according to the embodiment, and thus common parts are denoted by the same reference numerals as those described above. A detailed description of these will be omitted.

In this embodiment, a portion for supplying an over-concentrated (high-concentration) gas and a low-concentration gas (air) to the inside of the combustion chamber 10 is significantly different from the above-described embodiment. That is, in the present embodiment, the occupant 21 having a substantially conical shape and substantially concentric with the bottom plate 4 is provided. On the surface of the occupation object 21, a plurality of high-concentration gas flame holes 22 are provided at equal intervals in the generatrix direction and the circumferential direction of the plane cross section. Further, inside the occupation object 21, a low-concentration gas ejection pipe 26 which is substantially concentric with the occupation object 21 and whose both ends are open is provided. An end of the low-concentration gas supply pipe 26 on the combustion chamber 10 side and an end of the occupation material 21 on the downstream side of the gas are joined to form a high-concentration gas ejection section 27 whose upper end is closed, and a gas upstream side is a bottom plate. 4 and a high-concentration gas chamber 23 to be described later, and is connected to supply means (not shown). A high-concentration gas chamber 23 is joined to the bottom plate 4 under the occupation 21 of the bottom plate 4. Is provided with a high-concentration gas supply port 24 communicating with a high-concentration gas chamber immediately below the occupation object 21.

In this embodiment, the low concentration gas supply pipe 2
From 5, a low concentration gas (air) is injected into the combustion chamber 10. Further, the lean (mixed) gas is swirled into the combustion chamber 10 from the mixed gas supply unit 8 through the flame holes 9 provided in the inner peripheral wall 3. Further, the rich (high-concentration) gas is supplied from the high-concentration gas chamber 22 to the inside of the occupation object 21 through the high-concentration gas supply port 24, and injected into the combustion chamber 10 from the high-concentration gas flame 22.

As in the above embodiment, the difference between the density of the burned gas of the rich (high concentration) gas and the burned gas of the low concentration gas (air), and the swirl of the burned gas generated by burning the lean (mixed) gas. The force promotes the mixture of the rich (high concentration) gas and the burned gas and burns. Since the swirling force is weak at the center of the swirl, that is, at the center of the combustion chamber 10, the mixture of the rich (high concentration) gas and the burned gas is insufficient in this vicinity. However, when low-concentration gas (air) is supplied to the center of the combustion chamber 10 from the center of the occupation material 21, the mixture of the rich (high-concentration) gas and the burned gas is promoted even at the center of the swirl to burn. . Further, in the present embodiment, the rich gas (high concentration) is dispersed from the high concentration gas flame holes 22 provided on the surface of the occupation material 21 and injected into the swirling flow of the burned gas. Therefore, when the flow rate of the rich (high concentration) gas is large,
That is, even when the amount of combustion in the swirl combustor 20 is large, the rich (highly concentrated) gas and the burned gas are easily mixed to promote combustion. In the present embodiment, as described above, the rich (high concentration) gas and the burned gas are sufficiently mixed and completely burned, so that the generation of unburned components is very small as in the first embodiment. Therefore, the swirl combustor of the present embodiment generates less unburned components, and has a wider range of settable combustion conditions.

The rich (highly concentrated) gas is converted into a burned gas component CO other than residual oxygen by a diffusion effect in the swirling flow.
_Since it burns while being mixed with H ₂ O and the like, the generation of NO _x is small due to the dilution effect of these burned gas components. Further, the generation of NO _x is also suppressed by the temperature decrease in the combustion chamber 10 due to the supply of air.

As a specific configuration of the present embodiment, the occupant 21 is located at the center of the swirling flow, which is likely to be a negative pressure area.
Is provided. Therefore, the swirl combustor 2 of the present embodiment
At zero, the negative pressure region at the center of the swirl disappears or decreases. Therefore, the pressure drop in the central portion in the combustion chamber 10 is reduced, and the pressure gradient in the radial direction becomes almost flat. Therefore, the backflow of the flame is eliminated, and the flame is stably burned.

During combustion, the volume of the entire gas in the combustion chamber 10 increases as the combustion reaction proceeds and the temperature rises with the progress of the combustion reaction. However, in the swirl combustor 1 of the present embodiment, the substantially conical occupation material 21 whose cross-sectional area decreases toward the downstream is provided at the center of the combustion chamber 10. The radial sectional area of the gas flow space excluding the object 21 increases toward the downstream. Therefore, in the swirl combustor 20 of the present embodiment, the increase in the gas volume is offset by the expansion of the gas flow path, and the linear velocity of the entire gas in the combustion chamber 10 approaches a constant value. Therefore, the flame surface is further stabilized.

(Third Embodiment) The swirl combustor according to the second embodiment described above discharges rich (highly concentrated) gas toward the space of the swirling flow of burned gas generated by burning lean (mixed) gas. High concentration gas flame holes 22 provided on the surface of occupation 21
The fuel is further dispersed and injected into the combustion chamber 10. Therefore, the above-mentioned swirling combustor is added after sufficiently mixing the rich (high concentration) gas and the burned gas by the diffusion effect caused by the density difference between the rich (high concentration) gas and the burned gas in the swirling flow of the burnt gas. is intended to suppress the occurrence of the unburned components by burning, at the same time increasing the heat generation rate in the same volume space, it was possible to reduce the NO _x generation amount by the dilution effect of the burned gas. Further, since the occupation object 21 has a substantially conical shape in which the cross-sectional area becomes smaller toward the downstream, the increase in the gas volume is offset by the expansion of the gas flow path, and the linear velocity of the entire gas in the combustion chamber 10 becomes a constant value. And the flame surface became more stable. However, since the combustion capacity of the swirl combustor 20 is improved, the amount of combustion increases, and the occupation object 21 disposed inside is exposed to a very high temperature atmosphere. Here, the tip portion of the occupation object 21 that is in direct contact with the air passage is sufficiently cooled, but the lower half of the occupation material 21 easily becomes red-hot and has a problem in durability. There has been a problem in that a complicated material must be used. Therefore, a third embodiment of the present invention
The improvement has been made so that the occupation object 21 disposed inside without further suppressing the combustion performance of the swirl combustor 20 is further cooled.

The swirl combustor of this embodiment is the same as that of the second embodiment except for the occupation material 11 installed inside the combustion chamber 10. Therefore, common parts are given the same reference numerals as those described above. Is omitted. FIG. 4A shows an occupation object 30 arranged inside the combustion chamber 10 in the present embodiment.
FIG. 4B is a cross-sectional view taken along line AA of FIG. 4A. The occupation object 30 is formed in a conical shape by joining the high-concentration gas passage 31 and an end of a connecting portion 32 having an arc shape in plan view. The high-concentration gas passage 31 has a substantially “D” shape in plan view, and has a smaller cross-sectional area toward the gas downstream side,
The top has a sealed shape. Further high-concentration gas passage 3
1 is provided with high concentration gas outflow holes 33 at equal intervals in the generatrix direction of the occupation object 30. The low-concentration gas passage 34 is an occupant 3 composed of the high-concentration gas passage 31 and the connecting portion 32.
0 inside.

The occupation object 30 of the present embodiment replaces the occupation material 21 of the swirl combustor 20 in the previous embodiment. In the following, the rich (high-concentration) gas flows through the high-concentration gas passage 31 and is ejected through the high-concentration gas outlet 33 into the swirling flow of the burned gas in the combustion chamber 10. The low-concentration gas (air) is jetted from the top of the occupation object 30 through the passage 34 to almost the center of the swirling flow of the burned gas.

In the occupation object 30 of the present embodiment, the connecting portion 3
Numeral 2 is directly cooled by low-temperature low-concentration gas (air) flowing inside the occupation object 30, and the high-concentration gas passage 31 is efficiently cooled because three surfaces face the low-concentration gas passage 34. Therefore, low concentration gas (air) flowing inside
As a result, the occupation object 30 is efficiently cooled as a whole, and does not reach a high temperature even if it is disposed inside the high-temperature combustion chamber 10, so that an expensive material having high heat resistance as in the related art does not need to be used.

The high-concentration gas outlet 33 is provided with a high-concentration gas.
A plurality of passages 31 are provided at equal intervals in the generatrix direction of the occupied object 30.
The flow rate of rich (highly concentrated) gas is
Spouted from the entire surface of the occupation 30 into the swirling flow of burned gas
It is. Therefore, rich (high concentration) gas
Easy to disperse, high flow rate of rich (high concentration) gas
If the combustion amount of the swirl combustor 20 is large,
Even though rich (high concentration) gas and burned gas are well mixed and complete
It is burned and generates very little unburned components. Also,
In the same manner as in the embodiment, the rich (high concentration) gas
NO _xIs suppressed.

Further, the occupation object 30 of the present embodiment is
As in the embodiment, the occupation object 30 is provided at the center of the swirling flow, which will be a negative pressure region. Therefore, the pressure gradient in the radial direction in the combustion chamber 10 becomes almost flat, so that the backflow of the flame is eliminated and the combustion is performed stably.

At the time of combustion, the volume of the entire gas in the combustion chamber 10 increases as it goes downstream.
In the present embodiment, a substantially conical occupant 30 whose cross-sectional area decreases toward the downstream is provided at the center of the combustion chamber 10, so that the gas flow path increases toward the downstream. Therefore, similarly to the second embodiment, the linear velocity of the entire gas in the combustion chamber 10 approaches a constant value, and the flame surface is further stabilized.

The occupation object 35 shown in FIG. 5 is a modified example of the occupation object 30 of the third embodiment shown in FIG. Occupation 3
5 is provided with a cylindrical low concentration gas ejection pipe 36 at the center. A high-concentration gas ejection pipe 37 is attached to the outer periphery of the low-concentration gas ejection pipe 36 by joining its end to the low-concentration gas ejection pipe 36. The high-concentration gas ejection pipe 37 is a hollow pipe having a U-shaped planar cross section, and the planar cross section is reduced toward the gas downstream and the top is closed.

The low-concentration gas (air) is supplied to the low-concentration gas ejection pipe 3
6 and is injected into the combustion chamber 10 from the open end on the downstream side of the gas. The rich (high concentration) gas flows inside the high concentration gas ejection pipe 37 and is ejected from the high concentration gas ejection port 38 into the combustion chamber 10.

The occupant 40 shown in FIG. 6 is a further modified example of the occupant 30 of the third embodiment shown in FIG. The occupation object 40 includes a substantially conical hollow outer peripheral member 42 and a hollow core 41 installed inside the outer peripheral member 42. The core 41 has the same outer shape as the occupation object 35. More specifically, the outer peripheral surface of the core 41 has a substantially U-shaped cross section in the generatrix direction of the cone, and the flat cross section decreases toward the gas downstream and has a closed top portion 43.
Are provided in a plurality. The occupation object 40 has a shape in which the core 41 is installed inside the outer peripheral member 42 and the downstream end of the gas is closed, and a portion corresponding to the concave portion 44 of the core 41 of the outer peripheral member 42 High-concentration gas injection ports 45 are provided at intervals. A high-concentration gas passage 46 is formed by a gap formed by the core 41 and the outer peripheral member 42.

The low-concentration gas (air) flows inside the core 41 and is injected into the combustion chamber 10 from the open end on the downstream side of the gas. The rich (highly concentrated) gas flows inside the highly concentrated gas passage 46 and is ejected from the highly concentrated gas outlet 45 into the combustion chamber 10.

Even with the structure of the occupants 35 and 40 described above, since the entire occupants are cooled by the low-concentration gas (air) flowing inside the occupants 35 and 40, the occupants 3
Even if 5, 40 are placed in a hot combustion chamber,
5, 40 are not hot throughout. for that reason,
As the constituent material of the occupation material, it is not necessary to use an expensive material having high heat resistance as in the related art. Further, since a plurality of high-concentration gas ejection ports 38 and 45 are provided as in the above embodiment,
The rich (high concentration) gas is easily dispersed in the swirling flow, the rich (high concentration) gas and the burned gas are sufficiently mixed and completely burned, and the generation of unburned components is extremely small. In addition, NO _{x is} reduced due to the dilution effect of burned gas of rich (high concentration) gas.
Is also suppressed. Further, since the shape of the occupied object is substantially conical, the pressure gradient inside the combustion chamber 10 becomes almost flat as in the previous embodiment, so that there is no backflow of the flame. The linear velocity of the entire gas in the chamber 10 approaches a constant value, and the flame surface is stabilized.

Subsequently, the swirl combustor 2 of the second embodiment
0 as an example, the fuel gas concentration adjustment and the swirl combustor 2
Control of the swirl combustor by the method of supplying fuel to zero will be described. Hereinafter, the low-concentration gas is a gas containing no fuel, that is, air, as described above. FIG. 7 is a conceptual diagram showing a supply path of fuel and air to the swirl combustor 20. The means for supplying fuel and air is the swirl combustor 20.
It is arranged outside. The gas pipe 50 for supplying fuel is branched into a first gas branch pipe 51 and a second gas branch pipe 52. On the other hand, the air pipe 53 for supplying air is the first air branch pipe 5.
4. The air is branched into the second air branch pipe 55 and the third air branch pipe 56. The first air branch pipe 54 is connected to the low-concentration gas supply pipe 25.
, And the air second branch pipe 55 is connected to the gas pipe 50. The air third branch pipe 56 is connected to the gas second branch pipe 52.
Connected to. The first gas branch pipe 54 is provided in the high-concentration gas chamber 23.
, And the gas second branch pipe 55 is connected to the mixed gas supply unit 8.

Explaining the gas flow, the fuel is supplied by the gas pipe 50 and the gas first branch pipe 51 which is a branch pipe thereof.
The gas flows into the high-concentration gas chamber 23 or the mixed gas supply unit 8 through the second gas branch pipe 52. In addition, air is supplied through an air pipe 53.
And an air first branch pipe 54,
The gas flows into the low-concentration gas supply pipe 25, the high-concentration gas chamber 23, and the mixed gas supply section 8 through the branch pipe 55 and the third air branch pipe 56. More specifically, the rich (highly-concentrated) gas passes through the gas first branch pipe 54 after the air supplied from the air second branch pipe 55 connected to the gas pipe 50 is mixed with the fuel flowing through the gas pipe. the high concentration gas chamber 23 flows in the excess air ratio lambda _R. The lean (mixed) gas is mixed with fuel flowing through the gas second branch pipe 55 through the third air branch pipe 56 and supplied to the mixed gas supply unit 8 as a mixed gas having an excess air ratio λ _L. Here, the excess air ratio λ _L of the lean (mixed) gas is larger than the excess air ratio λ _{R of the} rich (high concentration) gas. Further, in this embodiment, since air containing no fuel is supplied as the low-concentration gas, the low-concentration gas is supplied to the air first branch pipe 5.
4 is supplied by being connected to the low concentration gas supply pipe 25.

FIG. 8 is a graph showing operating conditions of the swirl combustor 20 to which fuel is supplied by the above-described fuel supply method. In FIG. 8, the horizontal axis indicates the combustion amount indicating the total heat generation amount of the fuel supplied to the swirl combustor 20, and the vertical axis indicates the excess air ratio. λ _T is an apparent excess air ratio obtained from the total amount of fuel supplied from the gas pipe 50 and the total amount of air supplied from the air pipe 53, and the change of λ _T in each operation condition is set as an operation setting condition. Under certain operating conditions, if λ _T exceeds the excess air ratio at the upper limit of operation, the supplied fuel gas becomes lean, combustion becomes unstable, and the concentration of unburned components increases. On the other hand, if λ _T is below the lower limit of the excess air in the lower limit of operation, the concentration of the fuel gas becomes too high and flashback tends to occur.
O _x and the occurrence of unburned components increases rapidly. Therefore, the operation setting condition λ _T needs to be set within a range between the operation upper limit and the operation lower limit.

In FIG. 8, the set value of the combustion condition of the outer flame is λ _L , and the set value of the combustion condition of the inner flame is λ _R.
The ratio between the amount of fuel in the lean (mixed) gas supplied to the outer flame and the amount of fuel in the rich (highly concentrated) gas supplied to the inner flame is always kept constant. λ _T is set within the normal combustion range according to the required combustion amount, and λ _L and λ _R are determined so that stable and complete combustion is possible and NO _X emissions are minimized.

FIG. 9 illustrates a fuel supply method different from the fuel supply method shown in FIG. As described above, the low concentration gas is hereinafter referred to as a gas containing no fuel, that is, air. In the fuel supply method shown in FIG. 8, it is necessary to control the flow rates of both air and fuel. However, in actual use, there is a problem that it is difficult to control both at once, and there is a problem that the cost is increased correspondingly in order to be able to control both.
Therefore, the fuel supply method shown in FIG. 9 shows a method of adjusting the gas flow rate and the gas concentration by adjusting the fuel flow rate.

In the fuel supply method shown in FIG. 9, the fuel and air supply means are arranged outside the swirl combustor 20. The fuel pipe 60 for supplying fuel is a fuel first branch pipe 61.
And a second gas branch pipe 62. On the other hand, the air pipe 63 for supplying air is branched into an air first branch pipe 64, an air second branch pipe 65, and an air third branch pipe 66. The first air branch pipe 64 is connected to the low-concentration gas supply pipe 25, and the second air branch pipe 65 is connected to the first fuel branch pipe 61. The third air branch pipe 66 is connected to the second fuel branch pipe 62, and the second fuel branch pipe 62 is connected to the mixed gas pipe 68. Further, the mixed gas pipe 68 is connected to the mixed gas supply unit 8. The fuel first branch pipe 61 is connected to the high-concentration gas pipe 67, and the high-concentration gas pipe 67 is connected to the high-concentration gas chamber 23.

Next, the gas flow will be described. The fuel is a fuel pipe and a fuel first branch pipe 6 which is a branch pipe thereof.
1. The fuel flows into the high concentration gas chamber 23 or the mixed gas supply unit 8 through the fuel second branch pipe 62. The air is supplied through the air pipe 63 and the first branch pipe 64, the second branch pipe 65, and the third branch pipe 66, which are the low-concentration gas supply pipe 25, the high-concentration gas chamber 33, and the mixed gas supply pipe. Part 8
Flow into More specifically, after the air supplied from the air second branch pipe 65 connected to the fuel first branch pipe 61 is mixed with the fuel flowing through the fuel first branch pipe 61, the high concentration gas chamber 23 through the high-concentration gas pipe 67 flows in the excess air ratio lambda _R. The lean (mixed) gas is mixed with the fuel flowing through the fuel second branch pipe 62 from the air third branch pipe 66 and becomes a mixed gas having an excess air ratio λ _L through the mixed gas pipe 68 through the mixed gas supply unit 8. Supplied to
Here, the excess air ratio λ _L of the lean (mixed) gas is larger than the excess air ratio λ _{R of the} rich (high concentration) gas. Further, in this embodiment, since air containing no fuel is supplied as the low concentration gas, the low concentration gas (air) is supplied by connecting the first air branch pipe 64 to the low concentration gas supply pipe 25. . A valve 69 is provided in the middle of the first fuel branch pipe 61 so that the flow rate can be adjusted.

In the above-described fuel supply method, the total amount of air supplied to the swirl combustor 20 and the distribution ratio of air supplied to lean (mixed) gas, low-concentration gas, and rich (high-concentration) gas are kept constant. I do. In addition, the amount of fuel supplied to the lean (mixed) gas is kept constant, and only the amount of fuel supplied to the rich (highly concentrated) gas is adjusted by the valve 69 so that the amount of combustion supplied to the swirl combustor 20 is reduced. Coordinate the change. The operating conditions at this time are shown in FIGS. FIG. 10 illustrates operating conditions when the amount of fuel supplied to the swirling flame, that is, the amount of fuel supplied to the mixed gas supply unit 8 is fixed. The line A in the figure indicates the combustion condition of the fixed swirling flame, and the excess air ratio is 1.0 or more. At this time, the excess air ratio of the rich (high concentration) gas injected from the high concentration gas flame hole 22 is set to a value smaller than the excess air ratio of the line A. Depending on the required combustion volume, the excess air ratio of the rich (highly concentrated) gas is below 1.0. FIG. 11 shows a case where the excess air ratio supplied to the swirling flame is less than 1.0 (line B in the figure). In this case, the excess air ratio of the gas injected from the high concentration gas flame hole 22 is larger than the excess air ratio at the point B.

According to the fuel supply method shown in FIG. 9, the amount of combustion can be adjusted only by changing the amount of fuel supplied to the high-concentration gas flame 22 according to the opening of the valve 69. Therefore, according to this method, it is not necessary to adjust the amount of air, it is easy to adjust the fuel concentration and the flow rate, and the fuel can be burned under the optimum combustion conditions. Generation of _x can also be suppressed. Further, even when it is difficult to control the fuel supply amount, the fuel concentration and flow rate can be controlled.

[0059]

As described above, the swirl combustor of the present invention can obtain a higher space heat rate than the conventional one. Also,
Emissions of the NO _x than the conventional According to swirl combustor of the present invention is reduced.

In the swirl combustor according to the second aspect, the second mixed gas supplied to the center of the combustion chamber has a higher fuel concentration than the first mixed gas, and the second mixed gas has already been generated by the combustion of the first mixed gas. Completely combusts when mixed with fuel gas. Therefore, generation of unburned components can be minimized.

In the swirl combustor according to the third aspect, the burned gas generated by the combustion of the mixed gas is mixed with the high-concentration gas, thereby achieving complete combustion of the supplied fuel gas, and further, NO _x Is also minimized.

In the swirl combustor according to the fourth aspect, since the low-concentration gas contains no fuel at all, there is no need to adjust the gas concentration, and the gas supply means can be simplified.

In the swirling combustor according to the fifth aspect, since the low-concentration gas is injected into the center of the swirling flow of the burned gas, the high-concentration gas injected from around the burned gas and the low-concentration gas is swirled. Is well mixed even in the weak central part of Therefore, generation of unburned components discharged without burning by complete combustion is suppressed. In addition, NO is injected by low concentration gas injection.
The generation of _X is further suppressed.

In the swirling combustor according to the sixth aspect, the backflow of the burned gas can be prevented, and an effect of stabilizing the swirling flame is obtained. Further, the low-concentration gas injected from the top of the occupation material or the vicinity thereof promotes the mixing even in the central portion of the swirling flow where the combustion gas and the low-concentration gas are not sufficiently mixed.

According to the combustion amount control means of the present invention, the combustion amount can be easily adjusted only by adjusting the fuel supply amount to the internal flame. Therefore it is possible to complete combustion of the fuel, the emissions of unburned components and NO _x can be minimized. Further, the combustion amount control means is not limited to the swirl combustor and can be applied when adjustment of fuel concentration and flow rate is required.

[Brief description of the drawings]

FIG. 1A is a conceptual diagram of a swirl combustor according to a first embodiment of the present invention, and FIGS. 1B and 1C show a high-concentration gas supply port 5 and a low-concentration gas supply pipe 6 in FIG. It is a perspective view of.

FIG. 2 is a graph showing an emission limit of an unburned component in the swirl combustor according to the first embodiment of the present invention.

FIG. 3 is a conceptual diagram of a swirl combustor according to a second embodiment of the present invention.

FIGS. 4A and 4B show occupants incorporated in a swirl combustor according to a third embodiment of the present invention, wherein FIG. 4A is a conceptual diagram thereof, and FIG.
It is AA sectional drawing of.

FIG. 5 is a modified example of the occupation object built in the swirl combustor of the third embodiment of the present invention, (a) is a conceptual diagram thereof,
(B) is AA sectional drawing of (a).

FIGS. 6A and 6B show still another modified example of the occupation object built in the swirl combustor according to the third embodiment of the present invention, wherein FIG. 6A is a conceptual diagram thereof, and FIG. It is sectional drawing.

FIG. 7 is a conceptual diagram illustrating a fuel supply method of the present invention.

8 is a graph showing a relationship between a combustion amount and an excess air ratio in the swirl combustor 20 using the combustion amount control means in FIG.

FIG. 9 is a conceptual diagram showing still another fuel supply method of the present invention.

10 is a graph showing a relationship between the combustion amount and the excess air ratio when the combustion condition of the outer peripheral flame is fixed at 1.0 or more in the combustion amount control means in FIG. 9;

11 is a graph showing a relationship between the combustion amount and the excess air ratio when the combustion condition of the outer peripheral flame is fixed at 1.0 or less in the swirl combustor 20 using the combustion amount control means in FIG. 9; is there.

FIG. 12 is a conceptual diagram of a conventional swirl combustor.

[Explanation of symbols]

 Reference Signs List 1,20 Swirling combustor 2 Outer peripheral wall 3 Inner peripheral wall 4 Bottom plate 5 High concentration gas supply port 6 Low concentration gas supply port 7 Flange 8 Mixed gas supply section 9 Flame hole 10 Combustion chamber 11 Through hole 21, 30, 35, 40 Occupation Object 22 High-concentration gas flame hole 23 High-concentration gas chamber 24 High-concentration gas supply port 25 Low-concentration gas supply pipe 26 Low-concentration gas ejection pipe 27 High-concentration gas ejection section 31 High-concentration gas passage 32 Connection section 33 High-concentration gas outlet 34 Low-concentration gas passage 36 Low-concentration gas ejection pipe 37 High-concentration gas ejection pipe 38 High-concentration gas ejection port 41 Core 42 Outer peripheral member 43 Convex part 44 Concave part 45 High-concentration gas ejection port 46 High-concentration gas passage 50 Gas pipe 51 Gas First branch pipe 52 Gas second branch pipe 53 Air pipe 54 Air first branch pipe 55 Air second branch pipe 56 Air third branch pipe 60 Fuel pipe 61 Fuel first branch pipe 62 Charge the second branch pipe 63 the air pipe 64 air first branch pipe 65 the air second branch pipe 66 Air third branch pipe 67 a high-concentration gas pipe 68 the gas mixture pipe 69 valve

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) F23R 3/28 F23R 3/28 F 3/30 3/30 3/34 3/34 3/36 3/36

Claims (7)

[Claims] 1. A combustion chamber having an open end, wherein a first mixed gas in which air and fuel are mixed at a predetermined ratio is injected into the combustion chamber to generate a swirling flow of the mixed gas in the combustion chamber. Further, at a position away from the inner wall of the combustion chamber, a second mixed gas obtained by mixing air and fuel at a different ratio from the first mixed gas and a low-concentration gas having a lower fuel concentration than the two types of mixed gas are provided. A swirling combustor characterized by being injected. 2. The swirl combustor according to claim 1, wherein the second mixed gas has a higher fuel concentration than the first mixed gas. 3. The swirl combustor according to claim 1, wherein the first mixed gas has an excess air ratio of 1 or more, and the second mixed gas has an excess air ratio of 0 or more and less than 1. . 4. The swirl combustor according to claim 1, wherein the low-concentration gas contains no fuel. 5. The swirl combustor according to claim 1, wherein the low-concentration gas is injected toward a center of the swirling flow, and the second mixed gas is injected from a periphery thereof. . 6. A occupant occupying a part or all of a negative pressure region generated by the swirling flow is provided at a central portion of the swirling flow, and the low-concentration gas is injected from the top of the occupying material or from the vicinity thereof. The swirl combustor according to any one of claims 1 to 5, wherein: 7. The first mixed gas, the second mixed gas, and the low-concentration gas have a constant total amount of air and a constant air distribution ratio, a constant low-concentration gas fuel amount, and the first mixed gas or the low-concentration gas. The swirl combustor according to any one of claims 1 to 6, wherein the amount of fuel of one of the second mixed gases is constant, and the amount of the other fuel is changeable.