JP3667837B2 - Burner - Google Patents

Description

【００３８】
試験ボイラには、相当蒸発量７５０ｋｇ／ｈで火炉負荷が１８０万ｋｃａｌ／ｈ・ｍ³ の一般の蒸気ボイラを使用した。
この表１から明らかなように、何れの実施形態もＮＯｘ及びばいじんの排出の少ないバーナとなっていることが判る。
【００３９】
【発明の効果】
以上説明したように、請求項１及び２に係る発明によれば、１次空気で空気比の低い還元火炎が形成され、２次空気で空気比の高い酸化火炎が形成されてＮＯｘが低減され、特に、２次空気供給用の外筒が複数の流路に分割されることで分割火炎が形成され、火炎からの放熱が効率良く行われ、ＮＯｘ低減効果が高められる。
【００４０】
請求項３及び５に係る発明によれば、再循環ガスが効果的に供給でき、さらにＮＯｘ低減効果が高められる。
請求項４係る発明によれば、１次空気供給用の内筒に、燃焼用空気の一部を効果的に供給できる。
【図面の簡単な説明】
【図１】 請求項１に係る発明の一実施形態を示す正面図
【図２】 図１中Ａ−Ａ矢視断面図
【図３】 請求項２に係る発明の一実施形態を示す正面図
【図４】 図３中Ｂ−Ｂ矢視断面図
【符号の説明】
１ バーナ
２ バーナ本体
２ａ 内筒
２ｂ 外筒
３ 液体燃料噴射ノズル
４ イグナイタ
９ 新鮮空気流路
１０ 分割ガス流路
１０Ａ 内周流路
１０Ｂ 外周流路
１２ バッフル
１３ 再循環ガスの吸入口
１４ 再循環ガス流路
１５ バッフル
１６ 再循環ガスの吸入口[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a burner using liquid fuel for use in a combustion facility such as a boiler or a gas turbine, and more particularly to a so-called low NO _X burner that generates a small amount of nitrogen oxide (hereinafter referred to as NO _X ).
[0002]
[Prior art]
In recent years, from the viewpoint of environmental preservation, reduction of NO _x, carbon monoxide, hydrocarbons, etc. in exhaust generated from various combustion equipment such as boilers and gas turbines has been demanded.
The reduction of the NO _X in the combustion apparatus, NOx reduction combustion technology of the burner is enabled, as this technique, an exhaust gas recirculation system, split flame method, such two-stage combustion method is known from the prior art, various burner In practical use.
[0003]
In particular, the exhaust gas recirculation method described above is a method in which a part of the combustion exhaust gas discharged from the burner is recirculated and mixed with fresh air before combustion and burned. By mixing air
(1) Reduction in flame temperature due to increase in combustion air (2) NOx is reduced by reduction in oxygen partial pressure in combustion air.
[0004]
[Problems to be solved by the invention]
However, such a conventional exhaust gas recirculation system has the following problems.
That is, when the temperature of the circulated exhaust gas is as low as about 300 ° C., for example, the effect of reducing the flame temperature is large, but the effect of reducing the flame temperature becomes smaller as the exhaust gas temperature becomes higher.
[0005]
In addition, the NOx reduction effect increases as the exhaust gas circulation amount increases. However, if the exhaust gas amount increases excessively, the oxygen partial pressure in the combustion air decreases, combustion becomes unstable, and dust is generated in extreme cases.
On the other hand, the above-mentioned divided flame method is a method of dividing the flame to reduce the NOx by lowering the flame temperature by combining a reduced flame with a high fuel concentration and an oxidation flame with a low fuel concentration, and heat release from the flame. .
[0006]
In such a divided flame method, a large burner can make a divided flame relatively freely with multiple spray ports, but it is economical if a small gun type burner is used to create a divided flame by mounting multiple nozzles. Becomes worse. Moreover, since the divided flame has a large heat radiation and the flame temperature becomes low, soot generation occurs when the fuel spray is not sufficient when oil fuel is used.
[0007]
Furthermore, the above-described two-stage combustion method divides combustion air into two stages, creates a reduced flame with a high fuel concentration in the first stage, creates an oxidation flame in the second stage, and lowers the combustion temperature in each stage. And NOx is reduced by performing slow combustion as a whole.
However, when this two-stage combustion method is performed with oil fuel, if the fuel spray is not sufficient, the combustibility in the reducing flame deteriorates and soot is generated. On the other hand, if the combustibility in the reducing flame becomes too good, the effect of reducing NOx will be reduced.
[0008]
In view of the problems of the conventional systems, for example, in the conventional technique disclosed in Japanese Patent Application Laid-Open No. 4-160709, combustion air and recirculation for performing a two-stage combustion with an oil burner and forming a divided flame A new gas supply method is provided to greatly reduce NOx.
That is, in this prior art, combustion air is supplied in two stages, the first stage is burned in a reducing atmosphere, and the second stage air is alternately arranged on the circumference with the self-recirculation gas. Supply and oxidize combustion region and reduction combustion region are alternately configured to form a split flame in the annular reduction combustion air flow expanding centrifugally, combustion is completed in the oxidation combustion region, and the remaining air is reduced NOx is reduced by diffusing into the combustion region and causing slow combustion in a situation where the oxygen partial pressure is low.
[0009]
Such a conventional burner can provide a large NOx reduction effect in a small-scale hot water boiler.
However, in recent years, downsizing and high output of boilers are progressing, and the mainstream is a compact and high furnace load such as a once-through boiler, and the furnace pressure is one order or more higher than that of a hot water boiler.
[0010]
The self-recirculation gas flow path in the prior art burner has a baffle installed in front of the recirculation gas suction port, the secondary air is squeezed to increase the flow velocity, and the recirculation gas is sucked from the suction port. The structure is such that air and recirculation gas are mixed and blown out, and the flow resistance in this portion is large.
Therefore, when such a burner is used for a once-through boiler having a high furnace pressure, exhaust gas recirculation in the self-recirculation gas passage becomes difficult, and the NOx reduction effect becomes small.
[0011]
Further, since the flow of the self-recirculation gas passage is stagnated, there is a problem that the exhaust gas is stagnated in this portion and coke and dust that are contained easily accumulate.
Therefore, in view of the above-described conventional problems, the present invention provides a burner that can obtain an effective NOx reduction effect even in a boiler with a high furnace load and high furnace pressure, such as a once-through boiler. This is the issue.
[0012]
[Means for Solving the Problems]
For this reason, the invention according to claim 1
A burner body comprising an inner and outer double cylindrical body portion of an inner cylinder for supplying primary air and an outer cylinder for supplying secondary air;
A liquid fuel injection nozzle disposed in the inner cylinder of the burner body, the tip injection hole facing outward from the inner cylinder tip opening; and
Comprising
The outer cylinder for supplying secondary air is divided into a fresh air passage for supplying only fresh air and a recirculated gas obtained by recirculating fresh air and combustion exhaust gas into an inner peripheral side and an outer peripheral side. It was set as the structure which arrange | positioned alternately the division | segmentation gas flow path supplied from a flow path.
[0013]
The invention according to claim 2
A burner body comprising an inner and outer double cylindrical body portion of an inner cylinder for supplying primary air and an outer cylinder for supplying secondary air;
A liquid fuel injection nozzle disposed in the inner cylinder of the burner body, the tip injection hole facing outward from the inner cylinder tip opening; and
Comprising
The outer cylinder for supplying secondary air is divided into a fresh air passage for supplying only fresh air and a recirculated gas obtained by recirculating fresh air and combustion exhaust gas into an inner peripheral side and an outer peripheral side. The split gas flow path that is supplied from the flow path and the recirculation gas flow path that supplies only the recirculation gas are alternately arranged.
[0014]
The invention according to claim 3 wherein the recirculation gas passage has a baffle that blocks the supply of secondary air, and sucks the recirculation gas from a recirculation gas inlet provided outside the recirculation gas passage. I tried to do it.
The invention according to claim 4
The primary cylinder for supplying primary air is provided with a plurality of air inlets for supplying a part of combustion air.
[0015]
The invention according to claim 5
The divided gas flow path is divided into an inner peripheral side and an outer peripheral side, and the secondary air is supplied to the inner peripheral side passage to increase the flow velocity, and is provided outside the divided gas flow path. The recirculation gas sucked from the recirculation gas inlet is configured to flow through the outer peripheral side passage.
[0016]
In the invention according to claim 1, the burner is divided into the inner cylinder and the outer cylinder, the combustion air is divided into two stages, the primary air is supplied to the inner cylinder, and the secondary air is supplied to the outer cylinder. The
In this case, a part of the combustion air is supplied to the inner cylinder from a plurality of air intake ports provided in the inner cylinder for supplying primary air (invention according to claim 4).
[0017]
As a result, a reduced flame with a low air ratio is formed with primary air, and an oxidized flame with a high air ratio is formed with secondary air to reduce NOx.
In particular, the outer cylinder for supplying secondary air is divided into a plurality of flow paths, whereby a divided flame is formed, heat dissipation from the flame is efficiently performed, and the NOx reduction effect is enhanced.
The divided flow paths are composed of a fresh air flow path for supplying only fresh air and a divided gas flow path for supplying fresh air and recirculation gas, which are alternately arranged. .
[0018]
The divided gas flow path is divided into, for example, an inner peripheral side and an outer peripheral side, fresh secondary air flows through the inner peripheral flow path, and a plurality of exhaust gas suction ports are opened in the outer peripheral flow path (claims). Invention according to item 5).
At this time, since fresh air passes only through the inner circumferential flow path, the flow velocity is increased and supplied, and the recirculated gas is sucked from the exhaust gas suction port, and the outer circumferential flow path is Flowing.
[0019]
As a result, a part of the divided flame is formed in a mixed atmosphere of fresh secondary air and recirculation gas, so that the NOx reduction effect is further enhanced compared to the case where only fresh secondary air is divided. It is done.
Furthermore, in addition to the fresh air channel and the split gas channel, a recirculation gas channel through which only a mixed gas of the recirculation gas flows is provided, and these are alternately installed (invention according to claim 2).
[0020]
The recirculation gas flow path is provided with a baffle that prevents secondary air from flowing and an exhaust gas inlet, and the exhaust gas is attracted by air flowing through the fresh air flow path adjacent to the recirculation gas flow path. (Invention according to claim 3).
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
First, a first embodiment of the present invention will be described with reference to FIGS.
That is, in these drawings, the configuration of the burner will be schematically described. The burner 1 includes a burner body 2, a liquid fuel injection nozzle 3, a blower (not shown) as a blower for supplying combustion air, and an ignition unit. And an igniter 4 as the above.
[0022]
Here, the burner body 2 is composed of an inner / outer double cylinder body composed of an inner cylinder 2a for supplying primary air and an outer cylinder 2b for supplying secondary air arranged coaxially, The front end surface of the outer cylinder 2b is opened, and the rear end surface is closed.
The liquid fuel injection nozzle 3 includes a cylindrical rod-shaped nozzle adapter 3a and a nozzle forming member 3b connected to the tip of the nozzle adapter 3a. The nozzle hole 3c is formed at the tip of the nozzle forming member 3b. Has been established.
[0023]
The liquid fuel injection nozzle 3 is disposed in the inner cylinder 2a along the central axis thereof, and is positioned so that the tip injection hole 3c faces outward from the opening of the tip of the inner cylinder 2a.
The igniter 4 is fixedly attached to the outer periphery of the nozzle adapter 3 a of the fuel injection nozzle 3, and the tip ignition portion 4 a is located near the tip injection hole 3 c of the nozzle forming member 3 b of the fuel injection nozzle 3.
[0024]
A flame holding plate 5 is disposed at the front end opening of the inner cylinder 2a, and the flame holding plate 5 is supported by the fuel injection nozzle 3 via a stay (not shown).
A center opening 5b is formed in the flame holding plate 5, and a slit 5a provided at a predetermined angle in the circumferential direction is formed on the outer peripheral side of the center opening 5b.
[0025]
The slit 5a is formed by forming a kerf in the flame-holding plate 5 and raising the part surrounded by the kerf, and the raised part becomes the fin 5c.
Then, the nozzle hole 3 c of the nozzle 3 is exposed from the central opening 5 b of the flame holding plate 5.
[0026]
Further, the structure of the burner 1 will be described with its action. Reference numeral 6 denotes an oil supply line, reference numeral 7 denotes an oil supply return line, and fuel is supplied to the liquid fuel injection nozzle 3 through the oil supply line 6. Combustion air is supplied by the blower, and a part of the combustion air is sucked into the inner cylinder as primary air from a primary air suction port 8 provided in the peripheral wall of the inner cylinder 2a. And the liquid fuel sprayed from the liquid fuel injection nozzle 3 with respect to this primary air is ignited by the igniter 4, and combustion is started.
[0027]
At this time, the primary air is smaller than the theoretical air amount, and in the primary air, slow combustion with excessive fuel is performed, and generation of NOx is suppressed. The liquid fuel remaining without being completely combusted in this portion spreads to the outer peripheral side and is combusted by the secondary air supplied to the outer cylinder 2b for supplying secondary air.
Here, the secondary cylinder 2b for supplying secondary air includes a fresh air passage 9 for supplying only fresh secondary air, and a recirculation gas obtained by recirculating fresh secondary air and combustion exhaust gas. The divided gas flow paths 10 supplied from the flow paths divided into the circumferential side and the outer circumferential side are arranged alternately in the circumferential direction.
[0028]
That is, a plurality (6 in the embodiment) of partition walls 11 extending in the radial direction are mounted between the outer cylinder 2b and the inner cylinder 2a with a predetermined angular interval. And the divided gas flow paths 10 are alternately formed.
Moreover, between the pair of partition walls 11 constituting the divided gas flow path 10, partition walls (baffles 12 to be described later) extending in the circumferential direction are respectively mounted. The baffle 12 and the inner peripheral flow path 10 </ b> A for fresh air and the recirculation gas are provided. The outer peripheral flow path 10B is formed in isolation.
[0029]
The partition wall that separates the inner circumferential channel 10A and the outer circumferential channel 10B is fixedly attached at one end to the inner circumferential surface of the outer cylinder 2b, and the other end at a substantially intermediate portion between the outer cylinder 2b and the inner cylinder 2a. It is comprised from the baffle 12 arrange | positioned so that it may extend in the air downstream direction.
By providing such a baffle 12, the fresh secondary air flow path 9 between the inner cylinder 2a and the outer cylinder 2b is throttled at a portion extending in the air downstream direction at the other end of the baffle 12, so that the fresh secondary air The air flow rate is increased.
[0030]
In addition, a recirculation gas suction port 13 is provided on the peripheral wall of the outer cylinder 2b located on the downstream side of the air at the fixed mounting portion at one end of the baffle 12, and the suction is performed by fresh secondary air flowing through the inner peripheral flow path 10A. The recirculated gas is attracted from the port 13 and flows into the outer peripheral flow path 10B.
Therefore, according to such a configuration, the fuel that has not been combusted by the primary air is fresh air (fresh air that passes through the fresh air flow path 9) blown out from the outer cylinder 2b, or fresh air and recirculated gas ( Combustion is caused by fresh air and recirculation gas passing through the divided gas flow path 10.
[0031]
In such combustion, NOx reduction is further effectively achieved by the effect that a divided flame is formed and heat is efficiently radiated from the flame, and that the combustion by the recirculation gas is obtained.
Next, a second embodiment of the present invention will be described based on FIG. 3 and FIG.
That is, in these figures, the outer cylinder 2b for supplying secondary air includes a fresh air passage 9 for supplying only fresh secondary air, and a recirculation for recirculating fresh secondary air and combustion exhaust gas. A configuration in which the divided gas flow paths 10 for supplying gas from the flow paths divided into the inner peripheral side and the outer peripheral side and the recirculation gas flow paths 14 for supplying only the recirculation gas are alternately arranged in the circumferential direction; It has become.
[0032]
That is, as in the previous embodiment, a plurality of partition walls 11 (6 in the embodiment) are mounted between the outer tube 2b and the inner tube 2a with a predetermined angular interval between the outer tube 2b and the inner tube 2a. Two partition walls 15 extending in the radial direction are mounted at predetermined angular intervals at positions between 11, respectively, and the fresh air flow path 9, the divided gas flow path 10, and the recirculation gas flow path 14 are alternately arranged in the circumferential direction. It is formed.
[0033]
Further, similarly to the previous embodiment, baffles 12 extending in the circumferential direction are respectively mounted between the pair of partition walls 11 constituting the divided gas flow path 10. And an outer peripheral flow path 10B for recirculation gas are formed in isolation, and a recirculation gas inlet 13 is provided on the peripheral wall of the outer cylinder 2b as in the previous embodiment.
[0034]
Further, a baffle 15 that shuts off the supply of fresh secondary air is attached to the recirculation gas flow path 14 on the air upstream end side.
A recirculation gas suction port 16 is formed in the peripheral wall of the outer cylinder 2b located on the air downstream side of the baffle 15 of the recirculation gas flow path 14, and flows through the fresh air flow path 9 adjacent to the recirculation gas flow path 14. The recirculated gas is attracted from the suction port 16 by the fresh secondary air and flows into the recirculated gas flow path 14.
[0035]
Therefore, according to this configuration, the fuel that has not been combusted by the primary air is combusted by fresh air or recirculation gas blown out from the outer cylinder 2b.
In such combustion, NOx reduction is further effectively reduced by the effect that a divided flame is formed and heat is efficiently dissipated from the flame and the effect that combustion by recirculation gas is obtained.
[0036]
Table 1 shows the combustion characteristics of the burners according to the first and second embodiments described above.
[0037]
[Table 1]

[0038]
As the test boiler, a general steam boiler having an equivalent evaporation amount of 750 kg / h and a furnace load of 1.8 million kcal / h · m ³ was used.
As is apparent from Table 1, it can be seen that all of the embodiments are burners that emit less NOx and dust.
[0039]
【The invention's effect】
As described above, according to the first and second aspects of the present invention, a reduced flame with a low air ratio is formed with primary air, and an oxidized flame with a high air ratio is formed with secondary air to reduce NOx. In particular, the outer cylinder for supplying secondary air is divided into a plurality of flow paths, whereby a divided flame is formed, heat dissipation from the flame is efficiently performed, and the NOx reduction effect is enhanced.
[0040]
According to the invention which concerns on Claim 3 and 5, recirculation gas can be supplied effectively and NOx reduction effect is heightened further.
According to the invention which concerns on Claim 4, a part of combustion air can be effectively supplied to the inner cylinder for primary air supply.
[Brief description of the drawings]
1 is a front view showing an embodiment of the invention according to claim 1. FIG. 2 is a cross-sectional view taken along arrow AA in FIG. 1. FIG. 3 is a front view showing an embodiment of the invention according to claim 2. 4 is a cross-sectional view taken along the line BB in FIG.
DESCRIPTION OF SYMBOLS 1 Burner 2 Burner main body 2a Inner cylinder 2b Outer cylinder 3 Liquid fuel injection nozzle 4 Igniter 9 Fresh air flow path 10 Divided gas flow path 10A Inner peripheral flow path 10B Outer peripheral flow path 12 Baffle 13 Recirculation gas inlet 14 Recirculation gas flow path 15 Baffle 16 Recirculation gas inlet

Claims (5)

A burner body comprising an inner and outer double cylindrical body portion of an inner cylinder for supplying primary air and an outer cylinder for supplying secondary air;
A liquid fuel injection nozzle disposed in the inner cylinder of the burner body, the tip injection hole facing outward from the inner cylinder tip opening; and
Comprising
The outer cylinder for supplying secondary air is divided into a fresh air passage for supplying only fresh air and a recirculated gas obtained by recirculating fresh air and combustion exhaust gas into an inner peripheral side and an outer peripheral side. A burner characterized in that divided gas flow paths supplied from the flow paths are alternately arranged. A burner body comprising an inner and outer double cylindrical body portion of an inner cylinder for supplying primary air and an outer cylinder for supplying secondary air;
A liquid fuel injection nozzle disposed in the inner cylinder of the burner body, the tip injection hole facing outward from the inner cylinder tip opening; and
Comprising
The outer cylinder for supplying secondary air is divided into a fresh air flow path for supplying only fresh air and a recirculated gas obtained by recirculating fresh air and combustion exhaust gas into an inner peripheral side and an outer peripheral side. A burner characterized in that a divided gas flow path supplied from a flow path and a recirculation gas flow path for supplying only recirculation gas are alternately arranged. The recirculation gas passage has a baffle that blocks the supply of secondary air, and sucks the recirculation gas from a recirculation gas inlet provided outside the recirculation gas passage. Item 3. The burner according to item 2. The plurality of air inlets for supplying a part of combustion air are provided in the primary cylinder for supplying primary air, according to any one of claims 1 to 3. Burner. The divided gas flow path is divided into an inner peripheral side and an outer peripheral side, and the secondary air is supplied to the inner peripheral side passage to increase the flow velocity, and is provided outside the divided gas flow path. The burner according to any one of claims 1 to 4, wherein the recirculation gas sucked from the recirculation gas suction port is configured to flow through the outer peripheral passage.

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