JPH04356603A - Burner and method of its operation - Google Patents

Abstract

PURPOSE:To miniaturize the construction of a burner without increasing the generation of NOx. CONSTITUTION:In a boiler provided with a plurality of pre-mixture flame burners 10 provided in the horizontal direction and vertical direction respectively and a flame holder 20 near the outlet of each burner 10, and for the area of the opening between the pre-mixture burner 10 and the flame holder 20 through which the pre-mixture gas is blown out the area of the opening that the flame holder 20 has in the vertical direction is set smaller than the area at which the premixture gas blown out from said opening has a speed at which it can not burn near there. The mutual distance between the pre-mixture flame burners 10 that are adjacent in the horizontal direction is set to be the distance in which the pre-mixture flames that are formed by the pre-mixture gas blown out from the burner do not interfere mutually.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustor having a plurality of premixed flame burners and a method of operating the same.

0002

BACKGROUND OF THE INVENTION Emission regulations for NOx, which causes photochemical smog, are becoming stricter year by year, and technology development for reducing NOx emissions is actively being carried out. Also,
BACKGROUND OF THE INVENTION Liquefied natural gas (LNG) is an example of boiler fuel with a low content of polluting components generated during combustion, and the usage of these fuels is on the rise. When such a gaseous fuel with a low nitrogen content is combusted, the NOx generated is thermal NOx that is generated when nitrogen in the combustion air is oxidized in a high-temperature atmosphere. Thermal NOx production is highly temperature dependent and increases as the flame temperature increases. The flame temperature varies depending on the mixture ratio of fuel and combustion air, so-called air ratio, and the flame temperature is highest when combustion is performed with just the right amount of air (theoretical air amount) to completely burn the fuel.

Diffusion combustion is often used in conventional combustors. This combustion method is a method in which fuel and combustion air are injected into the combustion chamber through separate nozzles, and a flame is formed by mixing the two within the combustion chamber, and is characterized by superior flame stability. . However, in this combustion method, in the fuel-air mixing process, there always exists a region where the air ratio is close to 1, and the flame temperature becomes high in this region.
NOx generation increases.

[0004] For this reason, combustion methods such as lean combustion, two-stage combustion, and exhaust gas recirculation methods have already been developed for the purpose of reducing the amount of NOx generated by reducing the flame temperature, and have been adopted in many combustion devices. . The two-stage combustion and exhaust gas recirculation method
Although it is excellent in the effect of reducing Ox, unburned substances are likely to be released. To prevent this, it is necessary to make the combustor larger.
This is an economically disadvantageous combustion method. In addition, the lean burn method is a method in which combustion is performed by increasing the air ratio. In this combustion method, excess air increases, which increases the amount of heat discharged from the boiler to the outside of the system by combustion gas, reducing the thermal efficiency of the boiler.

[0005] As an example of a combustion device employing a premixed flame, there is a method (Japanese Patent Publication No. 52-28251) in which combustion is performed by combining a diffusion flame lacking air and a premixed flame containing excess air. , there is a limit to NOx reduction because some diffusion combustion is adopted. Another example is the NOx generated from the premixed flame even when the air ratio is around 1.0.
In order to reduce this, multiple burners are formed, and a plate (flame stabilizer) is installed downstream of the burner nozzle so that it is not parallel to the mainstream direction of the premixture of fuel and air that is ejected. Therefore, before the premixture is combusted, a part of the low-temperature combustion gas is mixed into the premixture to lower the flame temperature or reduce the oxygen concentration, thereby reducing NOx (patent application). 1-339252). This combustion method is equipped with multiple burners for the premix flame so that it can follow boiler load fluctuations within the stable combustion range of the premix flame. Since the high temperature combustion gas remains during this time, the above cooling and dilution effects are lost, and the NOx value (O20% equivalent value) may become higher than, for example, 60 ppm, which is the Tokyo regulation value.

[0006]

[Problems to be Solved by the Invention] In the conventional technology that uses a flame stabilizer to stabilize a premixed flame, in order to prevent an increase in the amount of NOx generated due to the increase in temperature due to flame interference, it is necessary to There is a problem in that it is necessary to provide large intervals, making it difficult to achieve miniaturization. In particular, as urban boilers have become popular these days, there is a desire for smaller boilers.

[0007] The present invention has been made by focusing on these conventional problems, and provides a combustor that can be downsized without increasing the amount of NOx generated.
The purpose is to provide combustion equipment and a method for operating a combustor.

[0008]

[Means for Solving the Problems] A combustor for achieving the above object includes a plurality of premixed flame burners, and a flame stabilizer is provided near the outlet of each of the premixed flame burners. , the area of the opening formed between the periphery of the ejection port of the premixed flame burner and the periphery of the flame stabilizer, which is the area of the opening formed between the periphery of the ejection port of the premixed flame burner and the periphery of the flame stabilizer, which is the area of the opening formed between the periphery of the ejection port of the premixed flame burner and the periphery of the flame stabilizer, which The area of the opening in the direction of the burner is set to be less than or equal to the area at which the premixed gas ejected from the opening has a flow velocity that cannot be combusted in the vicinity, or the opening has no area. It is. Further, in the case where a plurality of the premixed flame burners are provided in the vertical direction and the horizontal direction, the area of the opening formed between the ejection port periphery of the premixed flame burner and the periphery of the flame stabilizer, The area of the opening in one of the vertical and horizontal directions of the flame stabilizer is less than or equal to the area at which the premixed gas ejected from the opening has a flow velocity that cannot be combusted in the vicinity thereof. or the opening has no area, and the distance between adjacent premixed flame burners in the other direction, vertically or horizontally, is formed by the premixed gas ejected from each burner. The premixed flames are set at a distance so that they do not interfere with each other. Further, a method of operating a combustor to achieve the above object is a method of operating a combustor equipped with a plurality of premixed flame burners, in which ejection is emitted from one premixed flame burner after the adjacent premixed flame burners. It is characterized in that the air ratio of the premixed gas is higher than the stoichiometric air ratio, and the air ratio of the premixed gas jetted from the other premixed flame burner is lower than the stoichiometric air ratio. Here, the air ratio of the premixed gas ejected from the one premixed flame burner is from 0.5 to 0.9, and the air ratio of the premixed gas ejected from the other premixed flame burner is from 1.1 to 0.9. Preferably, the average air ratio of the premixed gases ejected from each premixed flame burner is adjusted to 1.0 to 1.5.

[0009] Furthermore, in the combustion equipment for realizing the above-described combustor operating method, in the adjacent premixed flame burners, the air ratio of the premixed gas ejected from one of the premixed flame burners is determined from the stoichiometric air ratio. The present invention is characterized in that it is equipped with an air ratio control means for setting the air ratio of the premixed gas ejected from the other premixed flame burner to be lower than the stoichiometric air ratio. Here, the air ratio control means specifically includes:
It can be configured with a flow rate regulating valve that regulates the flow rate of combustion air and fuel supplied to the premix flame burner, a controller that controls this, and the like.

0010

[Effect] To improve boiler efficiency, burn with an air amount close to the theoretical air amount (air ratio 1.0), reduce the amount of heat exhausted to the outside of the boiler system, and at the same time reduce the size of the combustion chamber. It is important to reduce heat dissipation. First, a premixed flame is used that can shorten the length of the flame in order to make the combustion chamber smaller. Conventionally, the mainstream technique for reducing NOx with a premixed flame has been to perform combustion with excess air, but as a result of extensive study, the inventors discovered that high-temperature combustion gas is placed in the center of a premixed fuel-air jet. It was revealed that NOx can be reduced if part of the combustion gas is mixed with the premixed gas before the premixed gas is combusted. The combustion gas introduced into the center of the jet ignites the premixed gas by heat transfer therefrom, thereby stabilizing the premixed flame. In addition, by providing a mechanism in which the combustion gas mixes with the premixed gas at the outer periphery of the jet, the high temperature region of the flame is reduced and thermal N
Generation of Ox is suppressed.

[0011] One means for realizing such a combustion method is a flame stabilizer. A flame holder is formed so that its downstream area suddenly decreases or its downstream area suddenly disappears. Such a flame stabilizer forms a circulating flow of high-temperature combustion gas on its downstream side, thereby ensuring the ignitability of the premixed gas. Another method is to arrange a given burner so that the combustion gas from the flame formed by the given burner flows into the center of the premixed gas jet. At this time, the predetermined burner should preferably be one with excellent flame stability, specifically a premixed flame burner or a diffusion flame burner equipped with a flame stabilizer.

[0012] Also, as one means for promoting the mixing of combustion gas from the outer periphery of the premixed gas jet, it is preferable to form the combustion chamber into a shape that rapidly expands from the premixed flame burner jet port. With this configuration, a circulating flow of combustion gas is formed on the outer peripheral side of the premixed gas jet, and mixing of the premixed gas and combustion gas is promoted.

By the way, in the combustion method explained above, when a flame is formed with a single premixed flame burner, low N
Ox combustion can be achieved, but when multiple premix burners are used to form a flame, if the spacing between the premix flame burners is reduced in order to downsize the combustor, the flames will interfere with each other and thermal NOx will increase. However, specifically, it may exceed the Tokyo metropolitan standard value of 60 ppm (O20% conversion).

Therefore, in the present invention, the area of the opening formed between the periphery of the ejection port of the premixed flame burner and the periphery of the flame stabilizer is the area of the opening formed in the direction of the premixed flame burner to be adjacent. The area is set to such an area that the flow velocity of the premixed gas jetted out from the opening is such that it cannot be combusted, or the area of the opening is eliminated. Therefore, no flame is formed in the direction of the premixed flame burners that are to be placed adjacent to each other, so even if the interval between the premixed flame burners is reduced in this direction, flame interference will not occur and thermal NOx will not increase. Note that if the mutual spacing is not made small for a certain premixed flame burner, it is necessary to set the mutual spacing at a distance where the premixed flames ejected from each burner do not interfere with each other. In this case, not only does flame interference not occur, but the combustion gas remains between the flames, promoting the flame cooling effect and the dilution effect of the premixed gas, thereby reducing NOx.

Furthermore, after adjacent premixed flame burners, the air ratio of the premixed gas ejected from one premixed flame burner is higher than the stoichiometric air ratio, and the air ratio of the premixed gas ejected from the other premixed flame burner is set higher than the stoichiometric air ratio. The object of the present invention can also be achieved by making the air ratio lower than the stoichiometric air ratio, that is, by performing concentrated combustion in adjacent premixed flame burners. Generally, the combustion temperature is highest when the stoichiometric air ratio, that is, the air ratio is 1, so the amount of thermal NOx generated is large.
When a premixed gas having an air ratio different from the stoichiometric air ratio is combusted, the amount of thermal NOx generated is small. Therefore, by burning a premixed gas having an air ratio different from the stoichiometric air ratio, the amount of thermal NOx generated can be reduced. However, if a premixed gas that differs from the stoichiometric air ratio is simply combusted, the combustion efficiency will deteriorate, so there is no practical effectiveness. Therefore, by burning the premixed gas with an air ratio higher than the stoichiometric air ratio and the premixed gas with an air ratio lower than the stoichiometric air ratio, the premixed gas with an air ratio lower than the stoichiometric air ratio can be burned. Combustion efficiency is also maintained by combusting the unburned matter produced by combustion with residual oxygen from combustion of premixed gas with an air ratio higher than the stoichiometric air ratio. Therefore, if such a system is used, the amount of NOx generated will not increase even if the distance between the premixed flame burners is further reduced.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of combustion equipment according to the present invention will be described below with reference to the drawings. Figure 1 for an example of combustion equipment
This will be explained using FIG. 8. The combustion equipment of this example is a natural circulation boiler equipment, as shown in FIG.

As shown in FIGS. 1 and 3, this boiler 100 is equipped with six premixed flame burners 10, 10, . . . arranged in three stages in the vertical direction and in two rows in the horizontal direction. It is provided. The premixed flame burners 10, 10, ... are
The mutual spacing in the vertical direction is very similar, and the mutual spacing in the horizontal direction is such that the premixed flames formed by the burners 10, 10 do not interfere with each other. Near the outlet of these premixed flame burners 10, 10, ..., there is a flame stabilizer 20 that forms a circulating flow of combustion gas on the downstream side thereof.
, 20, . . . are provided, respectively. Further, a diffusion flame burner 30 is provided near the center of the plurality of premix flame burners 10, 10, . On the wall of the combustion chamber,
A plurality of water pipes 2 are arranged, which are connected to a steam drum 3 and a water drum 4.

As shown in FIGS. 1 and 3, the diffusion flame burner 30 includes a fuel nozzle 31 that spouts liquefied natural gas as a fuel, an air nozzle 32 arranged to cover the periphery of the fuel nozzle 31, and a burner throat. It is composed of: A water pipe is provided in the burner throat to prevent the burner 20 from burning out.

An air duct 17 for supplying combustion air into the burner 10 is provided upstream of the premix flame burner 10 . The premix flame burner 10 includes a fuel nozzle 11 that spouts liquefied natural gas as fuel into its interior, and a rectifier 12 that rectifies combustion air supplied into the premix chamber.
and a mixer 13 for promoting mixing of fuel and combustion gas. The rectifier 12 is a honeycomb structure in which a plurality of plates are combined in parallel to the flow path, and has a rectifying effect that forms a flow with a uniform velocity distribution, and at the same time improves the flow velocity by reducing the cross-sectional area of the flow path. , also acts to prevent flashback of premixed flame.

The ejection port of the premix flame burner 10 has a rectangular shape that is elongated in the vertical direction, as shown in FIGS. 1 and 3. A rectangular plate-shaped flame stabilizer 20 is installed slightly downstream of this jet port so as to be perpendicular to the main flow direction of the premixed gas jet. The premixed gas is ejected into the combustion chamber from the opening between the jet port of the premixed flame burner 10 and the flame stabilizer 20;
The flame stabilizer 20 is formed so that the flame stabilizer 20 in the vertical direction is smaller than the flame stabilizer 20 in the horizontal direction. As shown in FIGS. 4 and 5, the openings provided in the vertical direction of the flame stabilizer 20 are further narrowed at the upper and lower edges of the ejection port of the premixed flame burner 10, so that the premixed gas ejected from these openings is combusted. In order to increase the flow rate to a level where it is impossible to
A partition plate 14 is provided.

As shown in FIG. 6, a premixed flame burner 10
The air supply systems 40, 45 connected to the air duct 17 that supplies combustion air into the premix flame burners 10, 10, and the fuel supply systems 50, 55 connected to the fuel nozzle 11 are connected to the premix flame burners 10, 10, Series 40,50 for the first column of...
and series 45 and 55 for the second column. The air supply systems 40, 45 and the fuel supply systems 50, 55 include flow meters 41, 46, 51, 56 and flow control valves 42, 4, respectively.
7, 52, and 58 are provided. This flow control valve 4
2, 47, 52, and 58 are connected to a controller 60 that controls the valve opening degree. The controller 60 has a learning function and adjusts the flow rate control valves 42, 47, . . . according to the signals from the flowmeters 41, 46, .
Outputs a control signal to.

Next, the operation of this embodiment will be explained. In the premix combustion method employed in this embodiment, the flame can generally be made shorter than in the diffusion combustion method, so that the heat load applied per unit volume in the combustion furnace can be increased. Specifically, the length of the premixed flame is usually 5
0 cm or less, and the distance from the burner 10 spout to the opposing water pipe 2 is only about 1 m. In addition, in the diffusion combustion method, the heat load of 500,000 kcal/m3h can be reduced to 2
It can be made more than 1,000,000 kcal/m3h. In addition, the feature of the boiler as in this embodiment is that when increasing the boiler capacity, it is sufficient to extend the boiler vertically and widen the interval between the water drum 4 and the steam drum 3 to increase the heat transfer area. It is in. This is possible by using the burner 10 of this embodiment because the length of the flame hardly changes even if the burner capacity is increased. Naturally, it is also possible to increase the capacity by increasing the number of stages of the premix flame burner 10 upward. In this way, in this embodiment, in a boiler that is suitable for downsizing, the vertical distance between the premixed flame burners 10, 10, . . . is further reduced to achieve vertical downsizing. .

By the way, simply premixed flame burner 10,1
If the mutual spacing between burners 10 and 0 is made small,
, 10 interfere with each other, and a high temperature area is formed there, leading to the generation of a large amount of NOx. Therefore, in this embodiment, partition plates 14 and 14 are provided at the upper and lower edges of the spout of the premixed flame burner 10, and the vertical direction between the flame stabilizer 20 and the spout of the premixed flame burner 10 is The area of the opening was made smaller and the flow velocity of the premixed gas ejected from this area was increased to prevent combustion in this area. Therefore, flame interference does not occur between the upper and lower burners 10, 10, and the boiler can be downsized without increasing the amount of NOx generated.

The flame stabilizer 20 forms a circulating flow of combustion gas on its downstream side to ensure stable ignition of the premixed gas and to reduce NOx. Since the resistance to the jet flow is relatively large, it is preferable to reduce the resistance by forming the upstream side of the flame stabilizer 21 itself so that it gradually becomes larger toward the downstream side, as shown in FIG. Further, as shown in FIG. 10, the flame stabilizer 22 may be formed so that the peripheral shape of the flame stabilizer 22 in the direction perpendicular to the main premixed gas ejection direction P is uneven. By forming it in this way, it is possible to ensure a larger circulating flow of combustion gas on the downstream side thereof, and it is possible to improve ignition stability and the like. In addition, flame stabilizers were provided for each of the premixed flame burners 10, 10, . . . as described above, but as shown in FIGS. One flame stabilizer 23 may be provided for each flame stabilizer 23. In this way, each premixed flame burner 10,
Even if the flame stabilizers provided for each of the premixed flame burners 10, 10, etc. are integrated, flame interference between the upper and lower premixed flame burners 10, 10 can be prevented.

[0025] Here, we conducted a test on combustion in which a premixed gas with an air ratio higher than the stoichiometric air ratio and a premixed gas with an air ratio lower than the stoichiometric air ratio were mixed, that is, with regard to concentrated combustion. , will be explained using FIGS. 7 and 8. In this test, two premixed flame burners each having a vertically elongated rectangular ejection port were arranged horizontally and vertically, and the amount of NOx generated was measured by changing the degree of density for each burner. In the graph in the same figure, the vertical axis represents the amount of NOx (O2) generated from the two premixed flame burners.
0% conversion value), and the horizontal axis is the air ratio at the combustor outlet of the exhaust gas discharged from the two premix burners. Furthermore, liquefied natural gas is used as fuel, and the amount of gas is 120 Nm3/h per premixed flame burner.

First, the test results using two premixed flame burners arranged horizontally will be explained with reference to FIG. No. 1 and NO. When premixed gas with the same air ratio is combusted in two burners (indicated by white circles in the graph), when the air ratio of the exhaust gas at the combustor outlet is approximately 1.11, 73 ppm of NOx is emitted. On the other hand, the air ratio of exhaust gas at the combustor outlet is about 1.11, and No. 1
Burner air ratio is 1.28, NO. When the air ratio of the two burners was 0.96 (indicated by a half-white circle in the graph), almost the same amount of NOx was emitted as when no concentrated/concentration combustion was performed. Also, NO. 1 and NO. When premixed gases with the same air ratio are combusted in two burners and the air ratio of the exhaust gas at the combustor outlet is approximately 1.17, 68 ppm of NOx is emitted. On the other hand, even if the exhaust gas air ratio at the combustor outlet is 1.17, No. The air ratio of 1 burner is 1.37, NO. When the air ratio of the two burners was set to 0.94 (indicated by a half-white circle in the graph), the amount of NOx emissions was 65 ppm, which was about 3 ppm lower than that without concentrated combustion. Also, the air ratio of exhaust gas at the combustor outlet is approximately 1.11.
So, No. The air ratio of 1 burner is 0.72, NO. When the air ratio of the two burners is 1.47 (indicated by the white circle in the graph), the NOx emission amount is 58 ppm, which is 15 ppm compared to the case where concentrated combustion is not performed.
PM was also reduced.

Next, the test results using two premixed flame burners arranged vertically will be explained with reference to FIG. The exhaust gas air ratio at the combustor outlet is approximately 1.05.
In the case of NO. 1 and NO. When premixed gas with the same air ratio was burned in two burners (indicated by white squares in the graph), 63 ppm of NOx was emitted, and No. The air ratio of 1 burner is 0.90, NO. Air ratio of 2 burners is 1.19
(indicated by a half-black square in the graph), 55 ppm of NOx is emitted, and when No. Air ratio of 1 burner is 0.77
, NO. When the air ratio of the two burners is 1.32 (indicated by the black square in the graph), 51 ppm of NOx is emitted,
Compared to a model that does not perform concentrated combustion, the maximum NOx
Emissions were reduced by 12ppm. Also, when the air ratio of exhaust gas at the combustor outlet is approximately 1.10, NO. 1 and NO. When premixed gas with the same air ratio is burned in two burners (indicated by white squares in the graph), 62 ppm NO
x is discharged and No. Air ratio of 1 burner is 0.94, N
O. When the air ratio of the two burners is 1.24 (in the graph,
), 55 ppm of NOx is emitted, and N
o. The air ratio of 1 burner is 0.74, NO. When the air ratio of the two burners is 1.44 (indicated by the black square in the graph),
47 ppm of NOx was emitted, which was a maximum reduction of 15 ppm compared to a model that did not perform concentrated combustion. Also, although the test results are not shown in the graph, the air ratio of the premixed gas with an air ratio higher than the theoretical air ratio is 1.
Between 1 and 1.5, the air ratio of the premixed gas with an air ratio lower than the stoichiometric air ratio is between 0.5 and 0.9, and the air ratio at the combustor outlet, which is the average air ratio, is 1. .0 to 1.
It has been confirmed that when adjusted between 5 and 5, there is a slight NOx reduction effect.

Based on the above test results, the operating method of the boiler equipment that was carried out will be explained. Boiler 100
At start-up, the centrally installed diffusion flame burner 30 is used, and as the boiler load increases, the premix flame burner 10 is used. The use of the diffusion flame burner 30 is stopped when the premixed flame produced by the premixed flame burner 10 becomes stable. Thereafter, until the boiler load reaches 50%, the three premixed flame burners 10, 10, 10 in the first row are used, and when the boiler load exceeds 50%, the burners 10, 10, 10 in the second row are used as the load increases. will be used one after another.

When the first row of premixed flame burners 10 and the second row of premixed flame burners 10 are used, the premixed gas ejected from the first row of premixed flame burners 10 is The flow control valves 42, 47, 52, and 58 of each series are opened so that the air ratio becomes 0.72 and the air ratio of the premixed gas ejected from the second row premix burner 10 becomes 1.47. Adjust the degree. This adjustment is performed by the flowmeters 41, 46, 51, 5 of each series.
The controller 60 receives the signal from the controller 6. Note that the air ratio of exhaust gas at the boiler outlet at this time is 1.
It is 11.

Generally, the theoretical air ratio, that is, the air ratio is 1
Since the combustion temperature is highest when
Generated in large quantities. Therefore, when a premixed gas having an air ratio different from the stoichiometric air ratio is combusted, the amount of thermal NOx generated is reduced. Therefore, in this embodiment, the amount of thermal NOx generated is reduced by combusting a premixed gas having an air ratio higher than the stoichiometric air ratio and a premixed gas having an air ratio lower than the stoichiometric air ratio. In particular, here, in the test described earlier, combustion was performed under the same conditions as the concentrated combustion, which had the greatest NOx reduction effect among the concentrated combustion in which two premixed flame burners were arranged horizontally. The NOx reduction effect is very large. In addition, by burning the premixed gas with an air ratio higher than the stoichiometric air ratio and the premixed gas with an air ratio lower than the stoichiometric air ratio, combustion of the premixed gas with an air ratio lower than the stoichiometric air ratio is possible. In order to maintain combustion efficiency, the unburned content produced by the combustion is combusted with residual oxygen from the combustion of premixed gas with an air ratio higher than the stoichiometric air ratio. Therefore, according to such a boiler equipment operating method, even if the mutual spacing between the premix flame burners is further reduced, the amount of NOx generated does not increase.

[0031] In this embodiment, concentrated combustion was performed between the horizontally adjacent premixed flame burners 10, 10, but the air supply systems 40, 45 and the fuel supply systems 50, 55 were changed. , vertically adjacent premixed flame burners 10
, 10 may be performed. Further, in this example, liquefied natural gas, which is a gaseous fuel, was used, but this does not limit the present invention, and it goes without saying that the present invention can also be applied to those using liquid fuel such as heavy oil.

[0032]

According to the present invention, even if the distance between the premix flame burners is narrowed, interference between adjacent premix flames can be eliminated, without increasing the amount of NOx generated.
The combustor can be made smaller.

[0033] Furthermore, since the combustion temperature can be suppressed even with concentrated combustion, the size of the engine can be reduced without increasing the amount of NOx generated.

[Brief explanation of the drawing]

FIG. 1 is an internal perspective view of a boiler according to an embodiment of the present invention.

FIG. 2 is an overall sectional view of a boiler according to an embodiment of the present invention.

FIG. 3 is a view taken along arrow III in FIG. 1;

FIG. 4 is a view taken along the IV arrow in FIG. 3;

FIG. 5 is a view taken along the V arrow in FIG. 3;

FIG. 6 is a system diagram of boiler equipment according to an embodiment of the present invention.

FIG. 7 is a graph showing the results of a concentration combustion test when premixed flame burners are placed next to each other in the horizontal direction.

FIG. 8 is a graph showing the results of a concentration combustion test when premixed flame burners are vertically adjacent to each other.

FIG. 9 is a perspective view of a modified example of the flame stabilizer according to the present invention.

FIG. 10 is a perspective view of another modification of the flame stabilizer according to the present invention.

FIG. 11 is a front view of still another modification of the flame stabilizer according to the present invention.

12 is a sectional view taken along the line XII in FIG. 11. FIG.

[Explanation of symbols]

10... Premixed flame burner, 12... Rectifier, 13... Mixer, 14... Partition plate, 20, 21, 22, 23... Flame stabilizer, 3
0... Diffusion flame burner, 40, 45... Air supply system, 50,
55...Fuel supply system, 42, 47, 52, 58...Flow control valve, 60...Controller.

Claims (13)

[Claims] Claims: 1. A combustor comprising a plurality of premixed flame burners and a flame stabilizer provided near the outlet of each of the premixed flame burners, wherein the periphery of the ejection port of the premixed flame burner and the flame stabilizer are provided. The area of the opening formed between the periphery of the vessel and the area of the opening in the direction of at least one premixed flame burner among the adjacent premixed flame burners is the area of the opening formed between the periphery of the vessel and the premixed flame ejected from the opening. A combustor characterized in that the area of the opening is set to be less than or equal to a flow velocity at which gas cannot be combusted in the vicinity thereof, or there is no area of the opening. 2. A combustor comprising a plurality of premixed flame burners in the vertical direction and a horizontal direction, and a flame stabilizer is provided near the outlet of each of the premixed flame burners, wherein the premixed flame burners The area of the opening formed between the periphery of the jet nozzle and the periphery of the flame holder, and the area of the opening in one of the vertical and horizontal directions with respect to the flame holder. However, the area is set to be less than or equal to the flow velocity at which the premixed gas ejected from the opening cannot be combusted in the vicinity, or the area of the opening is not large,
The mutual spacing between premixed flame burners that are adjacent in the other direction, vertically or horizontally, is set to a distance that prevents the premixed flames formed by the premixed gas ejected from each burner from interfering with each other. A combustor characterized by: 3. When the ejection port shape of the premixed flame burner is rectangular and the length in the vertical direction is longer than the length in the horizontal direction, the one side is in the vertical direction and the other side is in the horizontal direction. A combustor according to claim 2, characterized in that: 4. The flame stabilizer is characterized in that a maximum area of the flame stabilizer in a direction perpendicular to the main direction of premixed gas jetting is smaller than an opening area of a jet port of the premixed flame burner. The combustor according to claim 1, 2 or 3. 5. The flame holder is characterized in that the peripheral shape of the flame holder in a direction perpendicular to the main direction of the premixed gas jetting is uneven. Or the combustor described in 4. 6. The flame holder has a shape in which, on its upstream side, the area of the flame holder in a direction perpendicular to the main direction of ejection of the premixed gas gradually increases toward the downstream side. The combustor according to claim 1, 2, 3, 4 or 5, characterized in that: 7. A rectifier comprising a plurality of plates arranged parallel to the gas flow path is provided upstream of the premix flame burner. 4
, 5 or 6 combustors. 8. In a combustion equipment equipped with a combustor having a plurality of premixed flame burners, in the adjacent premixed flame burners, the air ratio of the premixed gas ejected from one of the premixed flame burners is set to the theoretical air ratio. 1. A combustor equipment comprising an air ratio control means for setting an air ratio of premixed gas ejected from the other premixed flame burner to be higher than the stoichiometric air ratio and lower than the stoichiometric air ratio. 9. Premixed gas air ejected from one premixed flame burner in the adjacent premixed flame burners, comprising the combustor according to claim 1, 2, 3, 4, 5, 6, or 7. A combustor equipment comprising an air ratio control means for setting a ratio higher than a stoichiometric air ratio and setting an air ratio of a premixed gas ejected from the other premixed flame burner lower than a stoichiometric air ratio. 10. The air ratio control means controls the air ratio of the premixed gas ejected from the one premixed flame burner to 0.5.
to 0.9, the air ratio of the premixed gas ejected from the other premixed flame burner to 1.1 to 1.5, and the average air ratio of the premixed gas ejected from all premixed flame burners to 1. Claim 8 characterized in that it is adjusted from .0 to 1.5.
Or the combustion equipment described in 9. 11. A method for operating a combustor equipped with a plurality of premixed flame burners, wherein the air ratio of premixed gas ejected from one premixed flame burner after adjacent premixed flame burners is determined from the stoichiometric air ratio. A method for operating a combustor, characterized in that the air ratio of the premixed gas ejected from the other premixed flame burner is lower than the stoichiometric air ratio. 12. The air ratio of the premixed gas ejected from the one premixed flame burner is set to 0.5 to 0.9, and the air ratio of the premixed gas ejected from the other premixed flame burner is set to 1.5 to 0.9. 12. The method of operating a combustor according to claim 11, wherein the average air ratio of the premixed gas ejected from each premixed flame burner is adjusted from 1.0 to 1.5. 13. The premixed gas ejected from all the premixed flame burners is the premixed gas ejected from the one premixed flame burner or the premixed gas ejected from the other premixed flame burner. , and an average air ratio of the premixed gas ejected from all the premixed flame burners is from 1.0 to 1.5.
How to operate the combustor described.