JP2004053144A - In-cylinder swirl combustor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an in-cylinder swirl combustor capable of maintaining a flame even when the fuel/air ratio is less than the lean flammable limit of a homogeneous premixed gas, and capable of complete combustion and low NOx combustion without regulating the amount of air flow. <P>SOLUTION: The in-cylinder swirl combustor is equipped with a cylindrical combustion chamber 11 with one end as a bottom surface 12, and inside it, a swirling flow 22 composed of air, fuel or mixed air/fuel flowing from a slot-like opening 18 in the tangential direction is formed around a central axis 20 and a cylindrical flame surface substantially symmetric in regard to the central axis 20 is maintained. On the upper side of the cylindrical combustion chamber 11, a pilot combustion chamber 11a having a smaller diameter than that of the cylindrical combustion chamber 11 is formed, and inside it, like the swirling flow 22, a pilot swirling flow 22a and a cylindrical pilot flame is formed, which spreads outward when flowing to the cylindrical combustion chamber 11 and surely becomes an ignition source even when the fuel/air ratio is smaller than the lean flammable limit. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a combustor for a continuous combustion device used for various applications, and particularly to a swirl combustor in a cylinder. The combustor according to the present invention can be used as a combustor for a gas turbine or various heating devices.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a combustor for gaseous fuel has been widely used in which a mixture of fuel and air flows out from an outlet having a round or slit shape substantially in the axial direction thereof. In this case, the flame is stabilized without increasing the flow velocity of the air-fuel mixture so as to ensure that the base of the flame is located at the outlet of the outlet. Since the flame and the outlet are almost in contact with each other, the outlet is susceptible to heat from the flame, and is likely to be deteriorated or deformed due to overheating. When the outflow speed of the air-fuel mixture is reduced due to deformation of the outlet, the combustion speed is increased due to the heating of the air-fuel mixture, and a problem called flashback, in which the flame returns from the outlet to the upstream, is likely to occur. On the other hand, if the outflow velocity of the air-fuel mixture is made sufficiently high, the above problem can be avoided, but the flame rises to a level where the velocity of the air-fuel mixture is attenuated and balanced with the combustion velocity. Such a flame holding method has problems such as a change in the spatial position of the flame and an increase in the length of the flame, so that it cannot be used except for special applications.
[0003]
In the cylindrical combustion chamber, when the air-fuel mixture flows in the circumferential direction along the wall surface from the axially long slot-shaped opening of the combustion chamber provided on the side wall, a swirling flow field around the central axis is formed. In the swirling flow field, a continuous cylindrical flame surface is formed that is substantially symmetric about the combustion chamber center axis and increases in diameter toward the combustion chamber outlet. A high-temperature, low-density burned gas region exists inside the cylindrical flame surface, and an unburned air-fuel mixture exists in the annular space between the outside and the cylindrical combustion chamber side wall surface. Is formed.
[0004]
The flame of the air-fuel mixture caused by swirling in the above-mentioned cylindrical combustion chamber is such that the high-temperature burned gas existing in the center and the air-fuel mixture come into contact with a large area, and the mixing surface perpendicular to the contact surface, that is, the flame surface It is known that because of the extremely low air velocity, it is possible to maintain a combustion flame up to a fuel / air ratio close to the combustion limit for a stationary mixture. The structure of the flame in which the burned gas having a low density exists inside the swirling flow field and the mixture having a high density exists outside the swirling flow field is extremely hydrodynamically stable. Further, the separation between the flame and the inlet of the air-fuel mixture caused by this structure is extremely effective in suppressing flashback, which is one of the problems inherent to premixed combustion.
[0005]
Since NOx emitted from the combustion apparatus has a bad effect on health and the global environment, various regulations are being imposed. However, it is necessary to further reduce the generation of NOx in large cities. Since the generation rate of NOx increases rapidly at high temperatures, lean premixed combustion, in which fuel and air are mixed and the fuel / air ratio is reduced to burn the fuel, makes the most sense. The characteristic of in-cylinder swirling combustion, which is excellent in flame stability under lean conditions and that flashback is unlikely to occur even when a premixed gas is supplied, suppresses the disadvantages caused by the essential characteristics of lean premixed combustion and maximizes the advantages It is considered to be very effective in maximizing the effect.
[0006]
Japanese Patent Application Laid-Open No. 2001-280605 “Premixed swirling combustor” discloses a combustor of a mixture of air and fuel gas using in-cylinder swirling combustion. This combustor will be described with reference to FIG. 6 which is a conceptual diagram of the embodiment. This combustor has a problem that has occurred in the combustion of a swirl field using a straight cylinder, that is, when the flow rate of the air-fuel mixture becomes excessive with respect to the size of the combustor, the cylindrical flame surface 21 and the cylindrical side wall are caused. A step 61 is provided near the outlet of the combustion chamber 11 in order to solve the problem that the air-fuel mixture 17 escapes unburned from the gap between the combustion chamber 11 and the air-fuel mixture 17. The cylindrical flame 21 expands in the radial direction due to the sudden increase in the sectional flow area due to the step 61, and a recirculating flow is formed downstream of the step 61. Incompletely burned components such as unburned air-fuel mixtures and carbon monoxide were burned in the region of such recirculation flow. In addition, a heat retaining member 62 made of ceramics or the like is provided in the combustion chamber, so that flame holding can be performed even under dilute conditions. With the above configuration, flame stability near the lean limit and high inflow is improved, and leakage of unburned air-fuel mixture along the wall surface, which has been a problem of swirling combustion in cylinders, has been almost eliminated, and complete combustion has been achieved. The load range can be expanded.
[0007]
In a combustion device and an engine having the same, the heat release rate and the output are controlled by increasing or decreasing the fuel flow rate per unit time. In order to maintain NOx generation at an extremely low level regardless of the amount of heat generated or the output while maintaining a sufficiently high combustion efficiency, the amount of air mixed with the fuel must be controlled by controlling the temperature and pressure of air to the combustor. It must be as close as possible to the optimal value determined by this.
[0008]
As an example of controlling the air flow rate according to the output, a hot water supply with a premix burner that controls the air flow rate to the combustor to increase or decrease the fuel flow rate by variably controlling the rotation speed of the blower with an inverter motor There is a dexterous combustor. This combustor is provided with three burners. The fuel-air ratio of the burner is controlled to be in the range of about 1: 1.3 by the increase / decrease of the number of operating burners and the air flow rate. (The ratio of the maximum calorific value to the volume). In the prototype combustor according to the above-mentioned Japanese Patent Application Laid-Open No. 2001-280605 “Premixed swirl combustor”, it was found that if the air flow rate was precisely controlled in accordance with the fuel flow rate, even a single burner could achieve the same level of turndown. However, when it is put into practical use, there is a problem that the cost is extremely increased due to higher precision of the control device and additional safety devices. Further, in order to further reduce NOx, it is required that combustion can be performed even in a region where the fuel / air ratio is smaller, but it is extremely difficult because it is related to the essential characteristics of premixed combustion.
[0009]
In the case of gas turbines, on the other hand, the air flow cannot be adjusted, except for special exceptions.However, the flow used for combustion in the total air flow must be controlled by a valve or other mechanism in accordance with the fuel flow. And various forms have been proposed. The lack of reliability of the air flow control mechanism in a high-temperature and high-pressure atmosphere and the need for a larger driving force and a valve than the fuel flow control are obstacles to the spread of the air flow control method for combustion. I have.
[0010]
Without air flow control, it is difficult to achieve low NOx under complete combustion over most of the operating range normally required for gas turbines, even with the "premixed swirl combustor" disclosed in the above-mentioned publication. At present, the majority of burners are equipped with a plurality of burners, and the number of burners to be operated is increased or decreased and the output is controlled by controlling the flow rate. It is clear that the range of change of the fuel / air ratio in the operating range of the burner per line becomes smaller in inverse proportion to the number of burners, but cannot be kept constant.
[0011]
[Problems to be solved by the invention]
As described above, in the combustor using the swirling of the air-fuel mixture in the cylinder, it is possible to maintain the flame even under the condition that the fuel / air ratio is extremely small, and to achieve the fuel capable of performing the low NOx combustion without controlling the air flow rate. There is a problem to be solved in expanding the range of the air / air ratio. If this problem is solved and the flame can be held and the high combustion efficiency can be obtained even under conditions where the fuel / air ratio is much smaller than before without controlling the air flow rate, NOx emission can be achieved over a wide operating range. Not only is significantly reduced, but also the operating range is significantly expanded, application to practical devices is facilitated, and spread can be promoted.
[0012]
SUMMARY OF THE INVENTION It is an object of the present invention to solve these problems of a swirl combustor in a cylinder, so that the flame can be maintained even when the fuel / air ratio is smaller than the lean side flammability limit of the premixed homogeneous mixture, and the air flow rate can be reduced. An object of the present invention is to provide a new in-cylinder swirl combustion type combustor that enables both complete combustion and low NOx combustion without control.
[0013]
[Means for Solving the Problems]
In order to solve the above-described problem, in the cylindrical swirling combustor, a swirling flow around a central axis of the cylindrical combustion chamber is formed inside a cylindrical combustion chamber having one end as a bottom surface, and the swirling flow is substantially formed with respect to the central axis. In the in-cylinder swirl combustor in which an axisymmetric cylindrical flame surface is held, the cylindrical combustion chamber has an inner diameter smaller than the inner diameter thereof, and a pilot swirl flow around the central axis is formed therein, and the center of the center is formed. It is characterized in that it is connected to an outlet of a cylindrical pilot combustion chamber in which a cylindrical pilot flame surface substantially symmetrical about an axis is formed.
[0014]
In addition, the swirling combustor in the cylinder has a cylindrical flame surface in which a swirling flow around a central axis of the cylindrical combustion chamber is formed inside a cylindrical combustion chamber having one end as a bottom surface and is substantially axisymmetric about the central axis. Is provided with a bottom fuel feeder for supplying fuel into the cylindrical combustion chamber at a peripheral portion of a bottom surface of the cylindrical combustion chamber.
[0015]
Here, the definition of “peripheral part” will be described with reference to FIG. In order to form a swirling flow 22 around the central axis 20 in the combustor, a slot-like opening 18 through which an air-fuel mixture (air when fuel is supplied from the side wall surface inside the combustion chamber) flows into the combustor. Translation along the central axis of the path 19 defines a virtual cylinder 57 coaxial with the combustion chamber circumscribing a virtual extension 56 in the cylindrical combustion chamber. The annular part 58 formed outside the projection part of the virtual cylinder 57 is the definition of the peripheral part in the present invention. Further, the position of the bottom surface fuel supply device on the bottom surface is defined as the center of gravity of the opening 59.
[0016]
In each of the above embodiments, as described above, the air-fuel mixture prepared upstream of the slot-shaped opening 18 of the cylindrical combustion chamber is supplied to the cylindrical combustion chamber from the slot-shaped opening 18 along the cylindrical side wall surface. It is general to introduce in the circumferential direction, but a side wall fuel supply device is arranged on the side wall, and the fuel injected therefrom and the air flowing in from the slot-shaped opening of the cylindrical side wall advance mixing while turning, A mixture may be formed. In this way, the problem of flashback is completely relieved.
[0017]
Similarly, a side wall fuel supply device is arranged on the side wall of the pilot combustion chamber, and the fuel injected therefrom and the air flowing in from the opening of the cylindrical side wall advance mixing while turning to form an air-fuel mixture. Is also good.
[0018]
Downstream of the cylindrical combustion chamber, through a connection portion, a swirling flow around the central axis is formed while having a diameter different from that of the cylindrical combustion chamber, and a cylindrical extended flame surface that is substantially axisymmetric is formed. One or more extended cylindrical combustion chambers can be connected. By connecting one or more extended cylindrical combustion chambers having a different diameter from the cylindrical combustion chamber and having a different diameter from the cylindrical combustion chamber downstream of the cylindrical combustion chamber to perform in-cylinder swirling combustion in series, a plurality of cylindrical combustion chambers can be obtained. The fuel / air ratio of the air-fuel mixture can be finely controlled in accordance with the calorific value and output of the combustion device and engine, as well as low NOx over a wide operating range by simply controlling the fuel flow rate without air flow rate control. Extremely high combustion efficiency can be realized at the same time.
[0019]
A side wall fuel supply device is also provided on the side wall of the extended cylindrical combustion chamber, so that the fuel injected therefrom and the air flowing from the slot-shaped opening of the cylindrical side wall are mixed while swirling to form an air-fuel mixture. You may.
[0020]
Further, if a fuel supply device is provided on the wall surface of the connection portion in the circumferential direction, and fuel is injected into the upstream or downstream cylindrical combustion chamber according to the structure of the wall surface, the overall structure is improved. As a result, combustion can be performed to a small portion of the fuel / air, and by appropriately allocating the fuel, low NOx and high combustion efficiency can be obtained.
[0021]
Furthermore, by connecting an extension duct having a larger inscribed circle diameter than its inner diameter to the outlet portion of the cylindrical combustion chamber or the outlet portion of the extended cylindrical combustion chamber connected to the most downstream, the connection portion is formed. Downstream, a circulating flow of backflow vortices is created, where unburned components flowing out along the wall of the cylindrical combustion chamber can be burned.
[0022]
On the side wall of the extension duct, there is formed an inlet through which any of air, fuel, or a mixture of air and fuel flows substantially toward the center in the radial direction, and these are mixed with combustion gas from upstream. This makes it possible to reduce the swirling of the combustion gas, adjust the temperature of the combustion gas, and optimize the temperature distribution of the combustion gas at the outlet. Further, the inflow port is provided at an angle that produces a swirl in a direction opposite to the swirl direction in the cylindrical combustion chamber upstream thereof, and when air, fuel, or a mixture of air and fuel is injected therefrom, the swirl is caused. The weakening effect becomes stronger.
[0023]
The fuel that can be burned by the above-mentioned circular swirl combustor is not only gas fuel but also air and CO. ₂ Gas fuel mixed with a non-combustion gas such as, or mist-like liquid fuel is also included. Further, the fuel of each flame of the cylindrical combustion chamber and the pilot combustion chamber disposed upstream thereof may not necessarily be the same. Also, the mixture need not be completely homogeneous. Even when the mixture is supplied as an air-fuel mixture for swirling combustion in a cylinder, the mixture need not be homogeneous.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of a swirl combustor in a cylinder according to the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram of the first embodiment. FIG. 1A shows a cross section including a central axis of a cylindrical combustion chamber, and FIG. 1B shows an AA cross section perpendicular to the axis (viewed from an arrow). AA) is shown. In this swirl combustor inside a cylinder, a small cylindrical combustion chamber (pilot combustion chamber) 11a whose bottom surface 12a is completely closed is connected to an opening 13 in a bottom surface 12 of a cylindrical combustion chamber 11 having a large diameter. . On the side wall surface 16 of the cylindrical combustion chamber 11, two elongated slot-like openings 18 through which the air-fuel mixture 17 flows into the combustion chamber 11 are provided at intervals in the circumferential direction. The pilot combustion chamber 11a also has the side wall surface 16a. Are provided with two openings 18a having the same shape. The flow paths 19 and 19a connected to the openings 18 and 18a and the combustion chamber side walls 16 and 16a are positioned so that the mixture 17 and 17a flow out along the inner wall surfaces of the respective combustion chambers 11 and 11a with a circumferential velocity component. In the combustion chambers 11, 11a, swirling flows 22, 22a of the air-fuel mixture are formed. Downstream of the cylindrical combustion chamber 11, an extension duct 24 having a larger inscribed circle diameter than its inner diameter is connected.
[0025]
As the number of the slot-like openings 18 and 18a increases in the circumferential direction, a more stable cylindrical flame can be produced, but practically, about 2 to 4 are preferable. A plurality of the slot-like openings 18 and 18a may be arranged in the axial direction, or if they are arranged so as to be shifted in the circumferential direction, the combustion chamber 11 which becomes a problem when the combustion chamber wall surface is a thin plate. , 11a and the slot-shaped openings 18, 18a can be reduced. In the embodiment of FIG. 1, the cylinder forming the combustion chamber 11 is thin, so that the flow path 19 made of a thin plate is connected to the upstream of the slot-shaped opening 18. If it is thick enough, a slot-like opening can be formed in the wall. In this specification, the slot-shaped openings 18 and 18a are defined as gas flowing from the slots 18 and 18a into the cylindrical combustion chambers 11 and 11a, and generate a swirl around the central axis 20 in the cylindrical combustion chambers 11 and 11a. This is a term representing the inflow port in general, and includes, for example, a linear arrangement of a plurality of circular openings.
[0026]
As shown in the figure, the flame 21a of the pilot combustion chamber 11a rapidly expands in the radial direction at a rapid expansion portion located immediately downstream of the connection with the cylindrical combustion chamber 11, and the high-temperature burned gas also spreads therewith. They act as a reliable ignition source for the air-fuel mixture flowing from the slot-shaped opening 18 of the cylindrical combustion chamber 11, further enhancing the stability of the flame 21. As a result, it becomes possible to burn a leaner air-fuel mixture that could not be burned by an in-cylinder swirling combustor including only a single cylindrical combustion chamber. The sudden increase in the flow path area formed by the connection between the cylindrical combustion chamber 11 and the extension duct 24 forms a circulating flow downstream of the connection portion, whereby the flow between the flame 21 and the cylindrical side wall 16 is reduced. The fuel-air mixture can be almost completely burned.
[0027]
If the burned gas from the pilot combustion chamber 11a and the air-fuel mixture from the slot-shaped opening 18 of the cylindrical combustion chamber 11 are mixed, the temperature after mixing is designed to be sufficiently high for the reaction, for example, 1200 ° C. Even if the air-fuel mixture flowing into the cylindrical combustion chamber 11 is thin, it can be completely reacted. Adjustment of the heat release rate of the device and the output of the engine can be achieved only by controlling the flow rate of the fuel. As long as the air-fuel mixture from the slot-shaped opening 18 of the cylindrical combustion chamber 11 is sufficiently lean, there is almost no NOx generated by the reaction. Therefore, if the combustion in the pilot combustion chamber 11a is made lean, NOx generation as a whole will occur. Will be very low. In a simulation experiment examining application to a gas turbine combustor, a very low NOx concentration of 10 ppm or less was confirmed.
[0028]
It is advantageous to improve the stability of the flame 21 in the cylindrical combustion chamber 11 when the mixture directions of the mixture 17 and 17a in the pilot combustion chamber 11a and the cylindrical combustion chamber 11 are the same. Emissions can be maintained at lower levels. On the other hand, when it is desired to shorten the length of the cylindrical combustion chamber 11 or to weaken the turning at the outlet, the reverse turning is suitable.
[0029]
FIG. 2 is a view showing a second embodiment of the in-cylinder swirl combustor according to the present invention, and FIG. 2A is a cross-sectional view taken along a plane including the central axis of the cylindrical combustion chamber. (b) is a cross-sectional view taken along a line BB (an arrow BB) taken along a plane perpendicular to the central axis. The reference numerals in the drawings are common to all the drawings except for new ones. The mechanism for generating the swirling flow of the air-fuel mixture inside the cylindrical combustion chamber 11 is the same as that of the embodiment shown in FIG. The bottom surface 12 is provided with a fuel injector formed of a circular tube as a bottom surface fuel supply device 26 in a peripheral portion. When the fuel is a gas, such a simple one is sufficient, but when the fuel is a liquid, it is necessary to use an atomizing nozzle as a fuel supply, and in some cases, atomizing air is required. Also, in addition to pure fuel, fuel droplets and vapors mixed with air and transported, and CO gas such as gas generated from a coal gasifier ₂ Combustible gas containing air, oxygen, etc. can also be used as fuel.
[0030]
What is important here is that the fuel supply position into the combustion chamber 11 must be a peripheral portion. When the fuel is supplied at the center or a position close to the center, the jet of the fuel is stabilized by the swirling flow in the combustion chamber 11, and the mixing with the air or the air-fuel mixture flowing from the slot-shaped opening 18 is extremely suppressed. . As a result, the flame of the fuel jet supplied from the bottom fuel supply device 26 becomes an elongated diffusion flame and burns in a state of insufficient air, so that soot is easily generated. Of course, it is suitable for a superheating furnace using radiant heat transfer, but has an adverse effect on NOx reduction. On the other hand, when fuel is supplied from the peripheral portion, interference with the flow of air or air-fuel mixture from the slot-shaped opening 18 occurs, and mixing proceeds at the peripheral portion, but the fuel concentration is high on the central axis near the bottom surface. An area is formed. This is extremely effective in extending the limit of the lean side at which flame holding is possible.
[0031]
In the embodiment shown in FIGS. 1 and 2, the fuel-air mixture 17 supplied from the slot-shaped opening 18 is a mixture of fuel and air at its upstream portion, but is a conceptual diagram of the third embodiment. As shown in FIG. 3, only air flows from the slot-like opening 18, and fuel is injected from a side wall fuel supply 25 provided on the side wall 16 of the cylindrical combustion chamber 11, and swirls in the combustion chamber 11. The method of advancing the mixing of the fuel and the air while forming the mixture can also form a substantially axisymmetric cylindrical flame 21 as in the case of supplying the air-fuel mixture. FIG. 3A is a cross-sectional view of a cylindrical combustion chamber according to a third embodiment of the present invention, taken along a plane including a central axis, and FIG. 3B is a cross-sectional view taken along a plane perpendicular to the central axis. (View CC). In this embodiment, at the time of low power, fuel is supplied only from the bottom fuel supply unit 26, and only air flows into the slot-shaped opening 18 to perform combustion. At the time of high output, fuel is injected from the side wall fuel supply unit 25. Then, the fuel and the air flowing from the slot-shaped opening 18 are swirled in the cylindrical combustion chamber 11 to be mixed and burned. The control of the output at the time of high output is performed only by controlling the fuel flow rate from the side wall fuel supply device 25. In this way, it is possible to operate the fuel / air ratio under a condition that is significantly smaller than that of a conventional swirl combustor in a cylinder. In order to minimize the emission of NOx, it is effective to narrow down the fuel flow rate from the bottom fuel supply unit 26 within a range where the burning efficiency does not decrease.
[0032]
FIG. 4 is a conceptual diagram showing a fourth embodiment according to the present invention as a longitudinal sectional view. The configuration of the upstream portion is basically the same as that of the first embodiment shown in FIG. A combustion chamber 11 b of an in-cylinder swirling type having a different inner diameter is connected to the downstream side through a connection portion 41. In this way, even when the air flow rate cannot be controlled, the heat rate of the combustion device and the output of the engine can be controlled by controlling the fuel flow rate in each stage. By increasing the number of stages, the degree of freedom in setting the fuel / air ratio in each stage is increased, so that more appropriate settings can be made. Thus, NOx reduction and complete combustion can be achieved over a wider range than in the first or second embodiment. Can be realized simultaneously.
[0033]
In this embodiment, the connection portion 41 further includes a connection portion fuel supply device 27 for supplying fuel into the combustion chamber 11b on the wall surface of the connection portion 41. The fuel supplied from the connection portion fuel supply device 27 is already in the second position. The same effect as the bottom fuel supply device 26 in the embodiment can be obtained, and the degree of freedom in setting the fuel / air ratio can be increased, so that more appropriate setting can be performed. NOx reduction and complete combustion can be simultaneously realized over a wider range than in the embodiment or the first embodiment in which two stages are effectively adopted.
[0034]
An extension duct 24b provided with an inflow port 23 through which dilution air flows is connected to the downstream side of the combustion chamber of the innermost cylinder swirling method. It is more effective to provide an extension guide 44 at the inlet 23 so that the dilution air flows out toward the center of the cross section of the combustor. The introduction of the dilution air is effective in weakening swirling components generated in the combustion chamber of the swirling type inside the cylinder. In particular, in gas turbines, it is necessary to avoid such swirling components because strong swirling components of the hot gas from the combustor adversely affect the efficiency of the downstream turbine. If an air-fuel mixture is used instead of air, the temperature of the combustion gas can be further increased.
[0035]
【The invention's effect】
As described above, in the in-cylinder swirl combustor according to claim 1, the in-cylinder swirl combustion chamber has a swirl flow around the central axis of the combustion chamber having an inner diameter smaller than the inner diameter. Since it is connected to the outlet of the cylindrical pilot combustion chamber in which the formed and substantially axisymmetric cylindrical flame surface is formed, the high-temperature combustion gas in the pilot combustion chamber is used to rotate the internal combustion type cylinder located downstream thereof. The combustion of the lean air-fuel mixture in the combustion chamber can be promoted, the operation on the leaner side becomes possible, and the reduction of NOx becomes possible. In addition, if the operation is performed such that only air flows into the combustion chamber of the in-cylinder swirling system on the downstream side, the combustible range on the lean side can be significantly increased as a whole combustor. As a result, it is possible to operate the combustion device and the engine while suppressing NOx emission over a wide range of the fuel / air ratio without complicated control of the air flow rate.
[0036]
Further, in the in-cylinder swirl combustor according to claim 2, a bottom surface fuel feeder is provided at a peripheral portion of a bottom surface of the in-cylinder swirl combustion chamber so that fuel can be supplied into the combustion chamber. The fuel and the air or air-fuel mixture from the slot-shaped openings are mixed appropriately, and a region with a high fuel concentration is formed near the center near the bottom surface, which is the air-fuel mixture flowing from the slot or the air flowing from the slot. The fuel from the side wall fuel supply device provided on the side wall of the combustion chamber mixes with the fuel in the combustion chamber. The range can be greatly expanded. As a result, it is possible to operate the combustion device and the engine while suppressing the emission of NOx over a wide range of the fuel / air ratio without complicated control of the air flow rate.
[0037]
In the in-cylinder swirl combustor according to claim 3, 4, or 7, since the mixture is formed inside the combustion chamber, the problem of flashback can be completely eliminated, and the device has high safety. Can be realized. In addition, there is an effect that a substance that easily ignites when it comes into contact with air can be safely burned.
[0038]
Further, in the in-cylinder swirling combustor according to claim 5 or 9, an extension duct having a diameter of an inscribed circle larger than its inner diameter is connected to an outlet of the in-cylinder swirling combustion chamber located at the most downstream side. Therefore, a step is formed at the connection part, and a circulating flow is formed downstream of the step, so that when unburned components and air-fuel mixture flow out along the wall surface, they can be burned. There is an important effect on.
[0039]
Further, in the in-cylinder swirl combustor according to claim 6, since the in-cylinder swirl combustion chambers having different inner diameters are connected, it is very easy to control the fuel / air ratio of the air-fuel mixture to each stage. Low NOx and complete combustion can be achieved over a wide range of fuel / air ratios. Just because it does not require complicated air flow control, a clean combustor or engine with excellent cost and durability can be realized.
[0040]
Furthermore, in the in-cylinder swirl combustor according to claim 8, a connection portion fuel supply device is provided on a wall surface of the connection portion in a circumferential direction, and an upstream or downstream combustion chamber is provided depending on the structure of the wall surface. The fuel is injected into the fuel cell, so that the fuel can be burned to a smaller fuel / air ratio as a whole, and a low NOx and high combustion efficiency can be obtained by appropriately allocating the fuel. There is.
[0041]
In the circular swirl combustor according to claim 10, an inflow port into which any of air, fuel, or a mixture of air and fuel flows in toward a substantially radial center is provided on a side wall of the extension duct, By mixing them with the combustion gas from upstream, it is possible to reduce the swirling of the combustion gas, adjust the combustion gas temperature, and optimize the temperature distribution of the combustion gas at the outlet.
[0042]
12. The in-cylinder swirl combustor according to claim 11, wherein the inflow port is provided at an angle that causes swirl in a direction opposite to the swirl upstream of the inflow cylinder, and air, fuel, and an air-fuel mixture are injected therefrom. Then, there is an effect that the effect of weakening the swirl becomes stronger, and when it is harmful that the combustion gas from the combustor has a strong swirl, it becomes an effective means of suppressing the swirl when applied to a gas turbine, for example.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of an in-cylinder swirl combustor according to a first embodiment of the present invention.
FIG. 2 is a conceptual diagram of a swirl combustor in a cylinder according to a second embodiment of the present invention.
FIG. 3 is a conceptual diagram of a swirl combustor in a cylinder according to a third embodiment of the present invention.
FIG. 4 is a conceptual diagram of a swirl combustor in a cylinder according to a fourth embodiment of the present invention.
FIG. 5 is an explanatory diagram of a definition of a peripheral portion on a bottom surface of a cylindrical combustion chamber in the present specification.
FIG. 6 is a conceptual diagram of a conventional combustor employing a premixed in-cylinder swirling combustion system.
[Explanation of symbols]
11 Cylindrical combustion chamber 11a Pilot combustion chamber
12,12a Bottom 13,13a Opening
14 air 15 fuel
16, 16a Side wall surface of cylindrical combustion chamber 17, 17a Air-fuel mixture
18, 18a Slot-shaped opening 19 Flow path connected to slot-shaped opening
20 Central axis of cylindrical combustion chamber 21 Cylindrical flame
22, 22a Swirling flow 23 Inlet
24 Extension duct 25 Side wall fuel supply
26 Bottom fuel feeder 27 Connection fuel feeder
44 Guide 56 Virtual extension
57 virtual cylinder 58 annular part on bottom
59 Bottom fuel supply opening 61 Step
62 heat retaining member

Claims (11)

In a cylindrical swirling combustor in which a swirling flow around a central axis of the cylindrical combustion chamber is formed inside a cylindrical combustion chamber having one end as a bottom surface and a cylindrical flame surface substantially axisymmetric with respect to the central axis is held. A cylindrical combustion chamber having an inner diameter smaller than the inner diameter thereof, wherein a pilot swirling flow around the central axis is formed therein, and a cylindrical pilot flame surface substantially axisymmetric with respect to the central axis is formed therein. A swirl combustor in a cylinder, characterized in that it is connected to an outlet of a pilot combustion chamber. In a cylindrical swirling combustor in which a swirling flow around a central axis of the cylindrical combustion chamber is formed inside a cylindrical combustion chamber having one end as a bottom surface and a cylindrical flame surface substantially axisymmetric with respect to the central axis is held. A swirl combustor in a cylinder, wherein a bottom fuel supply for supplying fuel to the cylindrical combustion chamber is provided around a bottom surface of the cylindrical combustion chamber. The in-cylinder swirl combustor according to claim 1, wherein a side wall fuel supply device is disposed on a side wall of the pilot combustion chamber. The in-cylinder swirl combustor according to claim 1 or 2, wherein a side wall fuel supply device is disposed on a side wall of the cylindrical combustion chamber. The swirl combustor according to claim 1 or 2, wherein an extension duct having a diameter of an inscribed circle larger than an inner diameter thereof is connected to an outlet portion of the cylindrical combustion chamber. Downstream of the cylindrical combustion chamber, a swirling flow around the central axis is formed through the connection portion and having a diameter different from that of the cylindrical combustion chamber, and a substantially cylindrically extended flame surface is formed. The swirl combustor according to any one of claims 1 to 4, wherein at least one or more extended cylindrical combustion chambers are connected. The swirl combustor according to claim 6, wherein a side wall fuel injector is disposed on a side wall of the extended cylindrical combustion chamber. The swirl combustor according to claim 6 or 7, wherein a connecting portion fuel injector is disposed on a wall surface of the connecting portion in a circumferential direction. 9. An extension duct having a diameter of an inscribed circle larger than an inner diameter of the cylindrical combustion chamber is connected to an outlet of the extended cylindrical combustion chamber connected to the most downstream side. The swirl combustor according to claim 1. The side wall of the extension duct is formed with an inflow port through which any one of air, fuel, or a mixture of air and fuel flows toward the center is formed. In-cylinder swirl combustor. An inlet for allowing any of air, fuel, or a mixture of air and fuel to flow into the cylindrical combustion chamber in a direction that causes a turn in a direction opposite to the turn of the upstream cylindrical combustion chamber, at a side wall of the extension duct. 10. The in-cylinder swirl combustor according to claim 5, wherein? Is formed.

Images