JP4068041B2 - Low NOx burner - Google Patents

Description

The present invention relates to a low NO _x burner. More specifically, in a combustion furnace, for example, an industrial combustion furnace, when it is burned at a high temperature, or when combustion air is preheated to a high temperature using a heat storage body or the like and burned, NO contained in the exhaust gas _{The present} invention relates to a low NO _x burner capable of reducing the amount of _x .

Conventionally, air pollution due to NO _x contained in exhaust gas discharged from industrial furnaces has become a serious situation, and as one of the countermeasures, NO such as two-stage combustion, concentration combustion, or exhaust gas recirculation combustion Various low NO _x burners with _x reduction methods have been developed. The main factors of the NO _x generation by notoriously combustion is the temperature, the higher the combustion furnace temperatures, NO _x in the exhaust gas is increased.

Also, in recent years, for the purpose of reducing the amount of CO ₂ discharged from industrial combustion furnaces, etc., the heat of combustion exhaust gas is recovered using a heat storage body, and the combustion air passes through the heated heat storage body In this way, a regenerative burner or the like is used in which combustion air is supplied into the combustion furnace in a preheated state and mixed with fuel for combustion. However, combustion air generally has a high temperature of about 1000 ° C. Therefore, the flame temperature is higher than the combustion with room temperature air, and as a result, the amount of NO _{x in} the exhaust gas tends to increase.

For this reason, an in-furnace combustion method and a heat storage combustion apparatus that reduce the amount of NO _x contained in the combustion exhaust gas while reducing the amount of CO ₂ have been proposed (see, for example, Patent Document 1 or 2).

In such a combustion method, the fuel and the combustion air are supplied in parallel with their supply positions separated from each other so that the fuel and the combustion air are not mixed immediately after being supplied into the combustion furnace. The amount of NO _{x in} the exhaust gas is reduced by suppressing the rapid mixing of the exhaust gas and by combusting the exhaust gas generated by the combustion into a mixed gas, thereby making it burn in a low oxygen concentration state. is there.
Japanese Patent Publication No. 7-26730 JP-A-8-49836

However, for example, in industrial furnaces where the furnace temperature is relatively high among industrial furnaces, even if a conventional low NO _x burner is used, the amount of NO _x cannot be sufficiently reduced, which is a problem. It was. In addition, in a combustion furnace using a regenerative burner equipped with a heat accumulator, even if the above-described method is used, the amount of NO _x cannot be sufficiently reduced, and the preheating temperature of combustion air is limited. it and must take measures such as to incidental denitration apparatus or the like, and that the combustion efficiency increases the consumption of fuel decreases, it takes a new energy to the NO _x removal, the desired CO ₂ There was a problem that the reduction could not be achieved sufficiently.

The present invention has been made in view of the above-described problems. In a combustion furnace, for example, an industrial combustion furnace, when combustion is performed at a high temperature, or by using a heat storage body or the like, the combustion air is preheated to a high temperature. An object of the present invention is to provide a low NO _x burner capable of reducing the amount of NO _x contained in exhaust gas when burning.

In order to achieve the above object, the present invention provides the following low NO _x burner.

[1] and the burner body, a low NO _x burner comprising a fuel nozzle for supplying a fuel, said burner body, on the front end surface, the front end surface of the fuel supplied from the fuel nozzle The fuel injected from the fuel supply hole at a position apart from the center of the front end surface where the fuel supply hole is located, and has a plurality of fuel supply holes injected from the center of the fuel toward the periphery of the front end surface a position not intersecting the jet, have a plurality of air supply holes for injecting air to the central axis parallel to the direction of the burner body, further, the outer periphery of the fuel nozzle, wherein the distal end of the burner body A low temperature combustion fuel nozzle for supplying the fuel for low temperature combustion disposed in a state of being drawn inward from the front end surface, and a tip portion on the outer peripheral side of the low temperature combustion fuel nozzle The burner body An auxiliary air nozzle for supplying auxiliary air arranged in a state of being drawn inward from the end surface, and the opening at the tip of the low temperature combustion fuel nozzle is the low temperature combustion fuel A low-temperature combustion fuel supply hole for injecting the fuel for low-temperature combustion supplied from the nozzle in a direction parallel to the central axis of the burner body, and an opening at the tip of the auxiliary air nozzle low NO _x burners auxiliary said supplied from the air nozzle becomes auxiliary air supply hole for injecting an auxiliary air, characterized in that capable of switching the supply of the fuel and the fuel nozzle and the low temperature combustion fuel nozzles .

[2] and the burner body, a low NO _x burner comprising a fuel nozzle for supplying a fuel, said burner body, on the front end surface, the front end surface of the fuel supplied from the fuel nozzle The fuel injected from the fuel supply hole at a position apart from the center of the front end surface where the fuel supply hole is located, and has a plurality of fuel supply holes injected from the center of the fuel toward the periphery of the front end surface A plurality of air supply holes for injecting air in a direction parallel to the central axis of the burner main body at a position not intersecting with the jet flow, and further disposed at the inner peripheral side of the fuel nozzle for low temperature combustion A fuel nozzle for low temperature combustion for supplying the fuel; and an auxiliary air nozzle for supplying auxiliary air disposed on an outer peripheral side of the fuel nozzle, wherein the burner body has the front end The low temperature combustion fuel Low temperature combustion fuel supply hole for injecting the fuel for low temperature combustion supplied from the nozzle in a direction parallel to the central axis of the burner body, and auxiliary for injecting the auxiliary air supplied from the auxiliary air nozzle A low NO , characterized in that the fuel supply can be switched between the fuel nozzle and the low-temperature combustion fuel nozzle at a predetermined temperature in a combustion atmosphere near the front end surface. _x Burner.

[3] Flame holding of a low-temperature combustion flame generated by the flow path of the fuel jet injected from the fuel supply hole and the fuel jet injected from the fuel supply hole for low-temperature combustion on the front end surface of the burner body low NO _x burner according to [2], further comprising a tubular flame stabilizing block and a flame holding space for performing.

[4] Low NO _x burner according to the shape is cylindrical said flame holding space [3] constituting the flame holding block.

[5] The ratio of the height of the flame holding space to the diameter of the flame holding space constituting the flame holding block in a cross section perpendicular to the central axis of the burner body is 1.5 to 2. 4] . The low NO _x burner described in 4] .

[6] A central axis of the burner body in a cross section perpendicular to the central axis of the burner body from a direction parallel to the central axis of the burner body or a direction parallel to the central axis of the burner body. low NO _x burner as claimed in any one of [1] to [5] for injecting circumferentially tangential direction of a circle centered in the direction inclined at an angle of 30 ° or less.

[7] The low NO _x burner according to any one of further comprising said heat storage body to the upstream side of the air supply hole [1] to [6].

[8] The fuel nozzle is arranged at the center of the front end surface of the burner body so that the tip end protrudes outward from the front end surface of the burner body, and the fuel supply hole is formed in the fuel nozzle. of the side wall of the tip, the low NO _x burner according to any one of the above is disposed through the central axis direction perpendicular burner body [1] to [7].

[9] The apparatus further includes an air nozzle for supplying the air, the air nozzle is disposed so as to protrude outward from the front end surface of the burner body, and an opening at a tip portion of the air nozzle is formed in the air nozzle. low NO _x burner according to any one of the above the air supply hole [1] to [8].

[ 10 ] Any one of the above [ 1 ] to [ 9 ], wherein the auxiliary air supply holes are dispersedly arranged on the front end surface of the burner body outside the low temperature combustion fuel supply holes. low NO _x burners of crab described.

[ 11 ] Any of [ 1 ] to [ 10 ], wherein a ratio of an interval between the air supply hole and the low temperature combustion fuel supply hole to an inner diameter of the low temperature combustion fuel supply hole is 15 to 20. low NO _x burners of crab described.

According to the low NO _x burner of the present invention, a combustion furnace, for example, in a combustion furnace for industrial, if burned in a high temperature, or when the preheated combustion air to a high temperature by using a heat storage body or the like is burned, The amount of NO _x contained in the exhaust gas can be reduced.

Hereinafter, with reference to the drawings and described in detail the embodiments of the low NO _x burner of the present invention, the present invention is not intended to be construed as being limited thereto, without departing from the scope of the present invention However, various changes, modifications, and improvements can be added based on the knowledge of those skilled in the art.

First, the basic configuration of the low NO _x burner is described with reference to FIGS. 1 (a) and 1 (b). Figure 1 (a) and FIG. 1 (b), the low NO _x burners are explanatory views schematically showing FIG. 1 (a) is a cross-sectional view, FIG. 1 (b) is a plan view.

The low NO _x burner 1 comprises a burner body 6, a low-NO _x burners and a fuel nozzle 2 for supplying the fuel, the burner body 6, on the front end face 14, supplied from the fuel nozzle 2 Front end surface 14 of the burner body 6 having a plurality of fuel supply holes 3 for injecting the fuel 11 from the center of the front end surface 14 of the burner body 6 toward the periphery of the front end surface 14. at a position apart from the center of, a position that does not intersect the fuel jet injected from the fuel supply hole 3, that having a plurality of air supply holes 5 for injecting air 12 to the central axis parallel to the direction of the burner body 6 .

By configuring in this way, in a combustion furnace, for example, an industrial combustion furnace, when burning at a high temperature, or when preheating the combustion air to a high temperature using a heat storage body or the like and burning it, The amount of NO _x contained in can be reduced.

In addition, here, the fuel nozzle 2 for supplying the fuel 11 is arranged at the center of the front end face 14 of the burner body 6 so that the tip end protrudes outward from the front end face 14 of the burner body 6. , the fuel supply hole 3 will be described low NO _x burners 1 through the central axis direction perpendicular burner body 6 disposed on the side wall of the tip of the fuel nozzle 2, the shape of the fuel nozzle 2 It is not limited to this.

Moreover, further comprising an air nozzle 4 for supplying a air 12, air nozzles 4 are arranged so as to protrude outwardly from the front end face 14 of the burner body 6, the opening of the tip of the air nozzle 4 is an air supply Although described low nO _x burners 1 as the hole 5, the air nozzle 4 is not necessarily required, also, it does not shape the air nozzle 4 is also limited to this.

The low NO _x burner 1, the temperature or the combustion air temperature combustion furnace is sufficiently high temperature, and if the temperature of the mixture of fuel 11 and air 12 containing the combustion exhaust gas is equal to or higher than the self ignition temperature a low NO _x burner 1 can be used particularly preferably. The temperature of the air 12 at the time of supply does not necessarily need to be higher than the self-ignition temperature. Even if the air 12 at the time of supply is at a temperature from room temperature to less than the self-ignition temperature, if the inside of the combustion furnace is sufficiently high After being supplied into the combustion furnace, the temperature of the mixed gas becomes equal to or higher than the auto-ignition temperature, and combustion can be realized.

Also, here is a description of low NO _x burners 1 regenerative that upstream further comprising a regenerator 9 of the air supply holes 5, the low NO _x burner of the present invention, in particular, low NO this regenerative It is not limited to the _x burner 1 and may be a simple low NO _x burner 1 that does not include the heat storage body 9.

In this low-NO _x burners 1, the fuel nozzle 2 and the air nozzle 4, the heat resistance of the excellent fire bricks, which are fixed to the burner body 6 made of a material such as refractory castables, the burner body 6 to the burner casing 8 It is configured to be covered.

As the material of the fuel nozzle 2 and the air nozzle 4, it since it is excellent in heat resistance, stainless, heat-resistant alloys such as Ni-based alloy, or mullite, recrystallization SiC, be suitably used ceramics such as Si-SiC .

The fuel nozzle 2 serves as a flow path for the fuel 11 to be supplied, and injects the fuel 11 into the combustion furnace from the fuel supply hole 3 of the fuel nozzle 2 and supplies the fuel 11 to an LNG supply source line, an LPG cylinder, or the like. It is preferable to connect and use.

The air nozzle 4 serves as a flow path for the air 12 to be supplied, and injects and supplies the air 12 into the combustion furnace, and is preferably connected to a blower or the like. Further, in this low-NO _x burners, since the heat accumulator 9 is a low NO _x burner 1 regenerative provided with this air nozzle 4 is also used as an exhaust line. A switching valve or the like capable of switching between supply of air 12 and exhaust of combustion exhaust gas is installed at an air outflow inlet 13 communicating from the air nozzle 4, and the above-described blower or the like is connected to the supply side of the air 12, so that combustion exhaust He connects the exhaust fan or the like on the exhaust side of the gas, so that the pair of the combustion furnace to place two or more low-NO _x burners 1. When supplying the air from one of the low NO _x air nozzle 4 of the burner 1, was evacuated at the other of the low NO _x burner 1 of the air nozzle 4, these constant period, for example, 60 to 120 seconds Switch. At this time, the heat accumulator 9 disposed in the air nozzle 4 serving as an exhaust line is heated by the heat of the combustion exhaust gas. On the other hand, since the heat storage body 9 disposed in the air nozzle 4 on the side of supplying the air 12 is sufficiently heated when exhausting the combustion exhaust gas, the air 12 is preheated using the stored heat. And supply it to the combustion furnace. In this way, combustion with low NO _x burners 1 regenerative, by supplying to the combustion furnace air 12 for combustion from the preheating using the heat of the combustion exhaust gas, is needed for combustion Thermal energy can be reduced, the amount of fuel 11 used for combustion can be reduced, energy saving can be realized, and the total amount of CO ₂ discharged from the combustion furnace can be reduced. .

In order to burn the supplied fuel 11 completely, the required amount of air 12 is determined according to the amount and type of the supplied fuel 11. In general, a larger amount of air 12 is required compared to the amount of fuel 11 required for combustion, and specifically, depending on the type of fuel 11 supplied, for example, When the fuel 11 is methane (CH ₄ ), the amount of air 12 that is about 10 times the volume of the fuel 11 is required. For this reason, it is preferable that the sizes of the fuel supply hole 3 and the air supply hole 5 are appropriately determined according to the type of the fuel 11 used, the size of the combustion furnace, and the like.

Further, the material and structure of the heat storage body 9 are not particularly limited, but are disposed in the flow path of the supplied air 12 and combustion exhaust gas, so that the pressure loss is low, the heat capacity is large, Furthermore, it is preferable that it is excellent in heat resistance, for example, the honeycomb structure etc. which consist of ceramics and have several cells used as the flow path of a fluid can be mentioned as a suitable example. Such a honeycomb structure can satisfy the above-described characteristics, and can easily supply the air 12 and exhaust the combustion exhaust gas without specially increasing the performance of the blower and the exhaust fan. .

Here, the flow of the fuel 11 and the air 12 until the fuel is actually burned will be described. First, the fuel 11 is supplied by being injected from the center of the front end face 14 of the burner body 6 toward the periphery of the front end face 14 of the burner body 6. At this time, since the ambient atmosphere in which the fuel 11 actually flows is filled with combustion exhaust gas in which the burned oxygen is very lean, combustion hardly proceeds in this state, and the fuel 11 is partially It is diluted with the gas that has finished this combustion, accompanied by thermal decomposition. At this time, the supplied fuel 11 is heated up to the vicinity of the self-ignition temperature by the heat in the combustion furnace or the combustion exhaust gas that has been burnt at a high temperature. When the supplied fuel 11 reaches the outer periphery of the combustion furnace, the flow velocity is reduced and diffuses into the combustion furnace. Incidentally, in this low-NO _x burners, the side wall of the tip of the fuel nozzle 2, the fuel supply hole 3 penetrating the central axis direction perpendicular burner body 6 is in the disposed configuration, the fuel The supply hole 3 only needs to be disposed in a direction substantially perpendicular to the central axis of the burner body 6.

Thereafter, the fuel 11 whose flow velocity has been reduced is entrained from the outside into the flow of the air 12 supplied from the air supply hole 5 and mixed over a wide range in the combustion furnace. As described above, generally, in order to completely burn the fuel 11, a large amount of air 12 is supplied compared to the amount of the fuel 11 supplied to the combustion furnace. The flow of the air 12 dominates the gas flow in the combustion furnace, and the above-described fuel 11 with the reduced flow velocity is involved in the flow. At this time, since the fuel 11 and the air 12 are mixed and combusted, including the combustion exhaust gas in which the burned oxygen is very dilute, the partial pressure of oxygen in the mixed gas is reduced. ing. For this reason, very slow combustion is realized. That is, because the combustion becomes locally intensely hot does not occur, generation of resulting NO _x is to be greatly suppressed.

For in this low NO _x burners, the position of the fuel supply hole 3 is too close to the front end face 14 of the burner body 6, the fuel jet will stalled by shear stress from the front end face 14 of the burner body 6, The position of the fuel supply hole 3 is preferably about 10 to 30 mm away from the front end face 14 of the burner body 6.

The fuel supply hole 3 is not limited to the configuration described above . For example, an arbitrary opening may be provided at the tip of the fuel nozzle 2, a block having a fuel guide channel formed by a groove or a hole at the tip, and the final fuel supply hole 3 at the tip of the channel. Good.

The air supply hole 5 may have a configuration in which a through-hole is simply provided in the burner body 6, but avoids mixing and burning with the fuel jet immediately after the air supply hole 5 due to fluctuations in the injection direction of the fuel 11. Therefore, it is more preferable that the air nozzle 4 projects the air supply hole 5 from the front end face 14 of the burner body 6 by about 20 to 40 mm.

By configuring in this way, for example, in an industrial combustion furnace, it is included in the combustion exhaust gas when it is burned at a high temperature or when combustion air is preheated to a high temperature using a heat storage body or the like and burned. The amount of NO _x that is generated can be reduced.

Further, as the fuel 11 used in the low NO _x burner 1, it is possible to use the fuel 11 used in the conventional burner suitably, in particular, methane, be a gaseous fuel such as LNG and LPG preferable. Such gaseous fuel does not include most of impurities such as sulfur, also with comprise also can be easily desulfurized though they can reduce the SO _x and the like in the combustion exhaust gas, the combustion Since it is excellent in efficiency, CO ₂ to be discharged can be reduced.

Further, the low NO _x burner 1 shown in Figure 1, the periphery of the fuel nozzle 2, but the air nozzle 4 is in the four placement configurations, the number of air nozzles 4 is limited to the For example, as shown in FIG. 2, a low NO _x burner 1 having six air nozzles 4 arranged around the fuel nozzle 2 may be used, and two or more fuel nozzles 2 may be arranged around the fuel nozzle 2. The air nozzle 4 should just be arrange | positioned.

Next, another form state of low NO _x burners, is described with reference to FIGS. 3 (a) and 3 (b). The low NO _x burner 20 includes a burner body 6, a low NO _x burner 20 having a fuel nozzle 2 for supplying fuel 11, the front end surface 14 of the burner body 6, supplied from the fuel nozzle 2 Burner body 6 having a plurality of fuel supply holes 3 through which the fuel 11 is injected from the center of the front end face 14 of the burner body 6 toward the periphery of the front end face 14 of the burner body 6. A plurality of air supply holes 5 for injecting air 12 in a direction parallel to the central axis of the burner body 6 at a position away from the center of the front end surface 14 of the fuel tank and at a position not intersecting with the fuel jet injected from the fuel supply hole 3. that it has a. Similar to the low NO _x burner 1 shown in FIG. 1 (a), the fuel nozzle 2, the center of the front end face 14 of the burner body 6, the distal end is outwardly from the front end face 14 of the burner body 6 An air nozzle for supplying air 12 is disposed so as to protrude and a fuel supply hole 3 penetrating in a direction perpendicular to the central axis of the burner body 6 is disposed on the side wall of the tip of the fuel nozzle 2. 4 is disposed so as to protrude outward from the front end surface 14 of the burner body 6, and the opening at the tip of the air nozzle 4 is an air supply hole 5. Component elements configured in the same manner as the elements constituting the low NO _x burner 1 shown in FIG. 1 (a), is partially omitted with the same reference numerals as in FIG. 1 (a).

Further, in this low-NO _x burners, disposed on the outer peripheral side of the fuel nozzle 2, together with further comprising an auxiliary air nozzle 21 for supplying the auxiliary air 24, the front end surface of the burner body 6 of the auxiliary air nozzles 21 14 is further provided with a flame holding plate 23 having an auxiliary air supply hole 22 for jetting auxiliary air 24 at the front end surface 14 at the front end portion on the 14 side, and the fuel nozzle 2 and the flame holding plate 23 are integrated into the burner body 6. It is configured to be movable along the central axis.

The low NO _x burner 20 configured as described above, the same effect as low-NO _x burners 1 shown in FIG. 1 (a), which has the effect, low temperature of the combustion furnace, such as immediately after the start of combustion, When the temperature of the mixed gas of the fuel 11 and the air 12 is lower than the self-ignition temperature, as shown in FIG. 4A, the fuel nozzle 2 and the flame holding plate 23 are integrated with the central axis of the burner body 6. The fuel 11 supplied from the fuel supply hole 3 in the region formed by the inner wall of the auxiliary air nozzle 21 and the flame holding plate 23 is moved inwardly from the front end surface 14 of the burner body 6 along The auxiliary air 24 supplied from the auxiliary air supply hole 22 is mixed to cause a stable primary combustion 25 including excessive fuel 11 to generate a low-temperature combustion flame. Further, the primary combustion 25 including excessive fuel 11 is generated. In front of, burned by primary combustion 25 The remaining fuel 11 that cannot be burnt out and the air 12 supplied from the air nozzle 4 are mixed to cause secondary combustion 26. In this way, by combustion in two stages, and when the temperature in the combustion furnace is sufficiently increased, the heat storage in the heat storage medium 9 low NO _x burner 20 configuration with (see FIG. 3 (a)) When the body 9 (see FIG. 3A) is sufficiently heated, as shown in FIG. 4B, the supply of the auxiliary air 24 is stopped or the fuel nozzle 2 and the auxiliary air nozzle 21 are protected. By supplying only the minimum required amount and supplying all or most of the air 12 from the air nozzle 4, slow combustion similar to the low NO _x burner 1 shown in FIG. Can do.

Further, in this low-NO _x burners, the auxiliary air 24 supplied from the auxiliary air nozzle 21, parallel to the center axis direction of the burner body 6, or from the central axis parallel to the direction of the burner body 6, the burner body 6 It is preferable to inject in a direction inclined at an angle of 30 ° or less in the circumferential tangential direction of a circle centering on the central axis of the burner body 6 in a cross section perpendicular to the central axis. In particular, the auxiliary air 24 is not more than 30 ° in a circumferential tangential direction of a circle centering on the central axis of the burner body 6 in a cross section perpendicular to the central axis of the burner body 6 from a direction parallel to the central axis of the burner body 6. If the air is injected in the direction inclined by this angle, the auxiliary air 24 collides with the inner wall of the auxiliary air nozzle 21 and a swirling flow of the auxiliary air 24 is formed, so that more stable primary combustion can be realized. An angle of 30 ° or less from the direction parallel to the central axis of the burner body 6 to the auxiliary air 24 in a circumferential tangential direction of a circle centering on the central axis of the burner body 6 in a cross section perpendicular to the central axis of the burner body 6 In order to inject in the inclined direction, the auxiliary air supply hole 22 is formed in the flame holding plate 23 in the inclined direction as described above, as shown in FIGS. 6 (a) and 6 (b). Can be realized.

Further, as shown in FIG. 4A, the fuel nozzle 2 and the flame holding plate 23 are integrally moved along the central axis of the burner body 6 from the front end surface 14 of the burner body 6 to the inside. as shown in FIG. 5 (a), the low NO _x burner 20, together with further comprising an auxiliary air nozzle 21 for supplying the auxiliary air 24 which is disposed on the outer peripheral side of the fuel nozzle 2, the auxiliary air nozzle 21 The burner body 6 further includes a flame holding plate 23 having an auxiliary air supply hole 22 for ejecting the auxiliary air 24 at the front end face 14 at the front end surface of the burner body 6, and the auxiliary air nozzle 21 is located at the center of the burner body 6. When the temperature in the combustion furnace is low just after the start of combustion and the temperature of the mixed gas of the fuel 11 and air 12 is lower than the auto-ignition temperature, the auxiliary air nozzle 21 is configured to be movable along the axis. The center of the burner body 6 , The fuel 11 supplied from the fuel supply hole 3 and the auxiliary in the region formed by the inner wall of the auxiliary air nozzle 21 and the flame holding plate 23. The auxiliary air 24 supplied from the air supply hole 22 may be mixed to cause a stable primary combustion 25 containing the fuel 11 excessively. When the temperature in the combustion furnace rises sufficiently, 9 If the regenerator 9 (which see FIG. 3 (a)) has been sufficiently heated in a low NO _x burner 20 configuration with (see FIG. 3 (a)), as shown in FIG. 5 (b) In addition, the supply of the auxiliary air 24 is stopped or only the minimum amount necessary for protecting the fuel nozzle 2 and the auxiliary air nozzle 21 is supplied, and all or most of the air 12 is supplied from the air nozzle 4. , similar to the low NO _x burner 1 shown in FIGS. 1 (a) It is possible to realize a slow combustion. Incidentally, FIG. 4 (a), in FIG. 4 (b), the FIGS. 5 (a) and 5 (b), the same configuration as the respective elements constituting the low NO _x burner 1 shown in FIGS. 1 (a) About the thing which attached | subjected the code | symbol same as Fig.1 (a), a part description is abbreviate | omitted.

With this configuration, even when the temperature in the combustion furnace is low just after the start of combustion and the temperature of the mixed gas of the fuel 11 and the air 12 is lower than the self-ignition temperature, it is easy to use the auxiliary air 24. Can be burned.

Further, even in a low NO _x burner 20 shown in FIG. 5 (a), the auxiliary air 24 supplied from the auxiliary air nozzle 21, parallel to the center axis direction of the burner body 6, or with the central axis of the burner body 6 parallel It is preferable to inject from a certain direction in a direction inclined at an angle of 30 ° or less in a circumferential tangential direction of a circle centering on the central axis of the burner body 6 in a cross section perpendicular to the central axis of the burner body 6. According to such a constitution, it is possible to obtain effects similar to those of low NO _x burners 20 shown in FIG. 4 (a), the effect.

Next, an embodiment of the low NO _x burner of the present invention. As shown in FIG. 7 (a) and 7 (b), the low NO _x burner 90 of the present embodiment, the low NO _x with the burner body 6, and a fuel nozzle 2 for supplying the fuel 11 A plurality of burners 90 that inject fuel 11 supplied from the fuel nozzle 2 onto the front end face 14 of the burner body 6 from the center of the front end face 14 of the burner body 6 toward the periphery of the front end face 14 of the burner body 6. The burner body is located at a position away from the center of the front end surface 14 of the burner body 6 where the fuel supply hole 3 is located and at a position not intersecting with the fuel jet injected from the fuel supply hole 3. 6 has a plurality of air supply holes 5 for injecting air 12 in a direction parallel to the central axis.

In the present embodiment, the low temperature combustion fuel nozzle 15 for supplying the low temperature combustion fuel 11 b disposed on the inner peripheral side of the fuel nozzle 2 and the outer peripheral side of the fuel nozzle 2 are disposed. And the auxiliary air nozzle 21 for supplying the auxiliary air 24, and the burner body 6 burns the low temperature combustion fuel 11 b supplied from the low temperature combustion fuel nozzle 15 onto the front end surface 14 of the burner body 6. Low temperature combustion fuel supply hole 16 that injects in a direction parallel to the central axis of main body 6 and auxiliary air supply hole 22 that injects auxiliary air 24 supplied from auxiliary air nozzle 21, in the vicinity of front end surface 14 at a given temperature in the combustion atmosphere of a low NO _x burner 90 switching supply which is capable of the fuel 11 in the fuel nozzle 2 and the low temperature combustion fuel nozzles 15. Further, the low NO _x burner 90 of the present embodiment further includes a heat storage body 9 on the upstream side of the air supply hole 5.

With such a configuration, similarly to the low NO _x burner 20 shown in FIG. 4 described above (a) and 5 (a), it is possible to reduce the amount of NO _x contained in the exhaust gas, Further, when the temperature in the combustion furnace immediately after the start of combustion is low and the temperature of the mixed gas of the fuel 11 and air 12 is lower than the auto-ignition temperature, the fuel 11b for low temperature combustion is used for low temperature combustion. In addition to supplying from the fuel nozzle 15, the auxiliary air 24 is supplied from the auxiliary air nozzle 21, and the fuel 11 b supplied from the low temperature combustion fuel nozzle 15 and the auxiliary air 24 are mixed to realize stable primary combustion. Can do. In conventional low NO _x burners, the temperature of the combustion furnace, for example, during a 600 ° C. or less, by incomplete combustion at low temperature, carbon monoxide (CO) that may occur several 100~1000ppm However, in the present embodiment, with the above-described configuration, a small amount and a constant amount of auxiliary air 24 can be used to achieve a minimum fuel capacity to maximum fuel capacity ratio (turndown) and a wide air ratio range. Stable primary combustion is possible, and the amount of CO generated during low-temperature combustion can be reduced.

Further, in the present embodiment, when the temperature in the combustion furnace is sufficiently increased by the stable primary combustion or when the heat storage body 9 is sufficiently heated, the supply of the fuel 11 is performed, for example, the fuel 11 and the switching valve 17 installed in the supply system 11, and the supply of the auxiliary air 24 is stopped or the minimum necessary for protecting the fuel nozzle 2, the low temperature combustion fuel nozzle 15 and the auxiliary air nozzle 21. only the supply amount of limit, the air 12 of all or most by supplying from the air nozzle 4, it is possible to implement the same slow combustion and low NO _x burner 1 shown in FIG. 1 (a). Note that the same in FIGS. 7 (a) and 7 (b), the one configured in the same manner as the elements constituting the low NO _x burner 1 shown in FIG. 1 (a), FIG. 1 (a) A part of the description is omitted.

As shown in FIG. 7 (a), if the configuration where the low NO _x burner 90 is provided with a regenerator 9, when the amount of air 12 and the auxiliary air 24 for normal combustion is constant, the auxiliary air 24 As the amount increases, the amount of air 12 passing through the heat storage body 9 decreases, and the heat recovery rate decreases. In the present embodiment, since stable primary combustion can be realized with a small amount of auxiliary air 24, the amount of auxiliary air 24 that does not pass through the heat accumulator 9 can be kept to a minimum, and the heat recovery rate is improved. Can be made.

Further, the low NO _x burner 90 of the present embodiment, the front end face 14 of the burner body 6, a flow path 19 of the fuel jet injected from the fuel supply hole 3, the injection from the low temperature combustion fuel supply hole 16 It is preferable to further include a cylindrical flame-holding block 18 having a flame-holding space 27 for holding a low-temperature combustion flame generated by the generated fuel jet. By generating in 18 flame holding spaces 27, more stable primary combustion can be realized.

Further, the shape of the flame holding space 27 constituting the flame holding block 18 is preferably a columnar shape. Furthermore, when the flame holding space 27 is a columnar shape, the flame holding space 27 of the burner body 6 The ratio of the height of the flame holding space 27 to the diameter in the cross section perpendicular to the central axis, that is, the length of the flame holding space 27 in the central axis direction of the burner body 6 is preferably 1.5-2. When the ratio of the height of the flame holding space 27 to the diameter of the flame holding space 27 in the cross section perpendicular to the central axis of the burner body 6 is less than 1.5, the flame holding space 27 has a flame holding effect. Since the recirculation of gases such as air and exhaust gas is difficult to be performed, the low temperature combustion flame may not be sufficiently retained, and if the above ratio exceeds 2, the flame retaining space 27 may not be recirculated. Intrusion of air in the combustion furnace may be suppressed, and the flame holding space 27 may become deficient in oxygen.

In the present embodiment, the auxiliary air 24 supplied from the auxiliary air nozzle 21 is moved from the direction parallel to the center axis of the burner body 6 or from the direction parallel to the center axis of the burner body 6 to the center axis of the burner body 6. It is preferable to inject in a direction inclined at an angle of 30 ° or less in the circumferential tangential direction of a circle centering on the central axis of the burner body 6 in a vertical cross section. The flame-holding space 27 is formed when sprayed in a direction inclined at an angle of 30 ° or less in the circumferential tangential direction of the circle centering on the central axis of the burner body 6 in a cross section perpendicular to the central axis of the burner body 6 Since the auxiliary air 24 collides with the inner wall of the flame block 18 and a swirling flow of the auxiliary air 24 is formed, more stable primary combustion can be realized. As shown in FIGS. 8A and 8B, in order to inject the auxiliary air 24 in the above-described direction, a flow path plate having auxiliary air supply holes 22 drilled at a predetermined angle is used. This can be realized by arranging at the tip of the auxiliary air nozzle 21.

Further, if the auxiliary air supply hole 22 and the low temperature combustion fuel supply hole 16 are too close to each other on the front end surface 14 of the burner body 6, the auxiliary air 24 may blow off a low temperature combustion flame caused by primary combustion. Therefore, as shown in FIGS. 9A and 9B, the auxiliary air supply hole 22 is located near the outer peripheral portion in the region facing the flame holding space 27 of the front end surface 14 of the burner body 6. That is, it is preferable that a plurality of dispersed fuel tanks are disposed on the outer side as far as possible from the low temperature combustion fuel supply hole 16. Further, as shown in FIGS. 10A and 10B, the annular auxiliary air supply hole 22 is provided in the vicinity of the outer peripheral portion in the region facing the flame holding space 27 of the front end surface 14 of the burner body 6. It is good also as the structure arrange | positioned.

Further, as shown in FIGS. 7A and 7B, the flame holding block 18 is injected from the center of the front end surface 14 of the burner body 6 toward the periphery of the front end surface 14 from the fuel supply hole 3. Since the fuel jet flow passage 19 is provided, the fuel 11 ejected from the fuel supply hole 3 is injected in a predetermined direction without being blocked by the flame holding block 18. The flame holding block 18 is preferably made of the same material as the burner body 6. Further, in the present embodiment, the flame holding block 18 having a plurality of grooves formed on the outer peripheral portion thereof is used, and the aforementioned groove in the connecting portion between the burner body 6 and the flame holding block 18 is the air supply hole. 5

In the present embodiment, the ratio of the distance between the air supply hole 5 and the low temperature combustion fuel supply hole 16 to the inner diameter of the low temperature combustion fuel supply hole 16 is preferably 15 to 20. When the ratio of the distance between the air supply hole 5 and the low temperature combustion fuel supply hole 16 to the inner diameter of the low temperature combustion fuel supply hole 16 is less than 15, the air supply hole 5 becomes low temperature combustion fuel supply hole 16. Therefore, the temperature of the low-temperature combustion flame is lowered and primary combustion may become unstable. When the above-mentioned ratio exceeds 20, when the amount of the low temperature combustion fuel 11 injected from the low temperature combustion fuel supply hole 16 is large, the oxygen concentration in the vicinity of the low temperature combustion fuel jet is low. The primary combustion may become unstable. Specific examples of the inner diameter of the low temperature combustion fuel supply hole 16 and the distance between the air supply hole 5 and the low temperature combustion fuel supply hole 16 include an inner diameter of the low temperature combustion fuel supply hole 16 of 4 mm. In this case, the distance between the air supply hole 5 and the low temperature combustion fuel supply hole 16 is preferably 60 to 80 mm. The distance between the air supply hole 5 and the low temperature combustion fuel supply hole 16 is the distance between the centers of the air supply hole 5 and the low temperature combustion fuel supply hole 16.

Further, in the present embodiment, as shown in FIGS. 11A and 11B, the tip of the fuel nozzle 2 is drawn inward from the front end surface 14 of the burner body 6 on the outer peripheral side. The low-temperature combustion fuel nozzle 15 for supplying the low-temperature combustion fuel 11b, which is disposed in a state of being cold, and the front end surface of the burner body 6 on the outer peripheral side of the low-temperature combustion fuel nozzle 15 And an auxiliary air nozzle 21 for supplying the auxiliary air 24, which is arranged in a state of being drawn inwardly from 14, the opening at the tip of the low temperature combustion fuel nozzle 15 being a low temperature combustion fuel. The low temperature combustion fuel 11b supplied from the nozzle 15 serves as a low temperature combustion fuel supply hole 16 for injecting the fuel 11b in the direction parallel to the central axis of the burner body 6, and the opening at the tip of the auxiliary air nozzle 21 is Auxiliary air nozzle 21 It may be a low NO _x burner 90 that is configured such that the auxiliary air supply hole 22 for injecting et supplied auxiliary air 24. Incidentally, in the low NO _x burner 90 shown in FIG. 11 (a), which further comprises a flame stabilizing plate 23 in the opening of the distal end portion of the auxiliary air nozzle 21, holes this formed in the flame stabilizing plate 23 A substantial auxiliary air supply hole 22 is formed. The low NO _x burner 90 of this embodiment has a switching valve 17 for switching supply of the fuel 11 in the fuel nozzle 2 and the low temperature combustion fuel nozzles 15. In the low NO _x burner 90 shown in FIG. 11 (a) and FIG. 11 (b), the the one configured in the same manner as the elements constituting the low-NO _x burners 90 shown in FIG. 7 (a), 7 The same reference numerals as those in FIG.

With such a configuration, similarly to the low NO _x burner 90 having a flame holding block 18 shown in FIG. 7 (a), even when the temperature in the furnace is not sufficiently increased, the low temperature The fuel 11b supplied from the hourly combustion fuel nozzle 15 and the auxiliary air 24 can be mixed in a space formed inside the front end face 14 of the burner body 6 to realize stable primary combustion. Furthermore, the low NO _x burners 90 shown in FIG. 11 (a), configuration of the front end face 14 of the burner body 6, but simple compared to low NO _x burners 90 shown in FIGS. 7 (a) For this reason, it is possible to reduce damage and deterioration of the front end face 14 that is in direct contact with the flame.

Further, the direction in which the auxiliary air 24 is injected in the low NO _x burner 90 shown in FIG. 11 (a) is preferably configured similarly to the low NO _x burner 90 shown in FIG. 7 (a). , to the inner diameter of the low temperature combustion fuel supply hole 16 in the low NO _x burner 90 shown in FIG. 11 (a), for also the ratio of distance between the air supply holes 5 and the low temperature combustion fuel supply hole 16, FIG. 7 ( it is preferably the same as the low-NO _x burners 90 shown in a). By configuring in this way, more stable primary combustion can be realized.

Furthermore, in the present embodiment, for example, as shown in FIGS. 12A and 12B, the front end surface 14 of the burner body 6 has a predetermined region centered on the fuel nozzle 2 as its bottom surface. And a concave portion 28 recessed inward of the front end surface 14, and radially disposed from the concave portion 28 of the front end surface 14 to the outside of the front end surface 14 along the direction in which the fuel 11 is injected from the fuel nozzle 2. The groove-shaped fuel guide channel 29 may be formed. With this configuration, the fuel 11 injected from the fuel nozzle 2 spreads toward the outer periphery of the front end face 14 via the fuel guide flow path 29, so that slow combustion can be effectively realized. In addition, the concave portion 28 of the front end face 14 becomes a space for mixing and burning the fuel 11b for low temperature combustion and the auxiliary air 24, and stable primary combustion can be realized. Note that the same in FIG. 12 (a) and 12 FIG. 12 (b), the the one configured in the same manner as the elements constituting the low-NO _x burners 90 shown in FIG. 11 (a), FIG. 11 (a) and The description will be omitted .

As described so far, according to the low NO _x burner of the present embodiment, it is possible to reduce the amount of NO _x contained in the exhaust gas, to realize a stable primary combustion at low temperature combustion CO emissions can be reduced.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

( Reference Example 1)
Combustion capacity 15 kW, having low NO _x burner 31 having a shape as shown in FIG. 13 (a) and 13 (b), was placed into a rectangular parallelepiped of the combustion furnace 40 having a width 500 mm × height 500 mm × length 700mm . In this reference example , the fuel 41 used for combustion was methane, and was supplied from the fuel supply hole 33 of the fuel nozzle 32 at about 17 NL / min in order to maintain the temperature in the combustion furnace 40 at 1400 ° C. The combustion air 42 is preheated to 1200 ° C. using an electric furnace instead of the heat storage body 9 (see FIG. 1A), and is supplied into the combustion furnace 40 from the air supply hole 35 of the air nozzle 34. did. In this way, the fuel 41 and the air 42 supplied into the combustion furnace 40 were mixed and burned.

When obtained by combustion with low NO _x burner 31 of the present embodiment, the fuel supply hole 33 of the fuel nozzle 32 as a reference point to measure the temperature at various locations in the combustion furnace 40 during combustion. Figure 14 is a present embodiment of the low NO _x burner 31 the temperature in the combustion furnace 40 when burned (° C.), a graph showing the relationship between the distance (mm) from the reference point described above, the horizontal axis represents a central axis perpendicular to the direction of low NO _x burners 31 from the reference point described above distance (y direction in FIG. 13 (a)) (mm) , the vertical axis represents the measured temperature (℃) . Further, x in FIG. 14 indicates a distance (mm) in a direction (x direction in FIG. 13A) from the reference point to the center of the combustion furnace 40.

(Comparative Example 1)
An air / fuel simple direct injection type burner 51 having a combustion capacity of 15 kW and having a shape as shown in FIGS. 15 (a) and 15 (b) is manufactured, and is a rectangular parallelepiped having a width of 500 mm × a height of 500 mm × a length of 700 mm. It was installed in the combustion furnace 60. The fuel 61 used in the combustion and methane, at about 17NL / min to maintain the temperature in the combustion furnace 60 to 1400 ° C., was supplied from the fuel supply hole 53 of the fuel nozzle 52, for combustion in the same manner as in Reference Example 1 The air 62 was preheated to 1200 ° C. and supplied into the combustion furnace 60 from the air supply hole 55 of the air nozzle 54 of the burner 51, and the supplied fuel 61 and air 62 were mixed and burned.

When combustion was performed using the air / fuel simple direct injection burner 51 of this comparative example, the temperature was measured at various points in the combustion furnace 60 during combustion with the fuel supply hole 53 of the fuel nozzle 52 as a reference point. . FIG. 16 shows the relationship between the temperature (° C.) in the combustion furnace 60 when the air / fuel simple direct injection burner 51 of this comparative example is burned and the distance (mm) from the reference point described above. In the graph, the horizontal axis indicates the distance (mm) in the direction perpendicular to the central axis of the burner 51 from the reference point (y direction in FIG. 15A), and the vertical axis indicates the measured temperature (° C. ) Further, x in FIG. 16 indicates a distance (mm) in a direction (x direction in FIG. 15A) from the reference point to the center of the combustion furnace 60.

(Comparative Example 2)
A baffle flame holding burner 71 having a flame holding mechanism and having a combustion capacity of 15 kW and having a shape as shown in FIGS. 17A and 17B is manufactured, and has a width of 500 mm × a height of 500 mm × a length of 700 mm. It was installed in a rectangular parallelepiped combustion furnace 80. The fuel 81 used in the combustion and methane, at about 17NL / min to maintain the temperature in the combustion furnace 80 to 1400 ° C., was supplied from the fuel supply hole 73 of the fuel nozzle 72, for combustion in the same manner as in Reference Example 1 The air 82 was preheated to 1200 ° C. and supplied into the combustion furnace 80 from the air supply hole 75 of the air nozzle 74 of the burner 71, and the supplied fuel 81 and air 82 were mixed and burned.

When combustion is performed using the baffle flame holding type burner 71 having the flame holding mechanism of this comparative example, the temperature is set at various points in the combustion furnace 80 during combustion with the fuel supply hole 73 of the fuel nozzle 72 as a reference point. Was measured. FIG. 18 shows the relationship between the temperature (° C.) in the combustion furnace 80 when the baffle flame holding burner 71 having the flame holding mechanism of this comparative example is burned and the distance (mm) from the reference point described above. The horizontal axis indicates the distance (mm) in the direction perpendicular to the central axis of the burner 71 from the reference point (y direction in FIG. 17A), and the vertical axis indicates the measured temperature. (° C.) Further, x in FIG. 18 indicates a distance (mm) in a direction (x direction in FIG. 17A) from the reference point to the center of the combustion furnace 80.

The low NO _x burner 31 of Reference Example 1, the burner 71 of the burner 51 and Comparative Example 2 Comparative Example 1, a combustion furnace temperature 1400 ° C., in the conditions of air temperature 1200 ° C., exhaust for residual oxygen concentration (%) The concentration of NO _x contained in the gas (15% O ₂ equivalent value) was measured. The measurement results are shown in FIG. FIG. 19 is a graph showing the relationship between the residual oxygen concentration (%) and the NO _x concentration (15% O ₂ converted value). The horizontal axis shows the residual oxygen concentration (%), and the vertical axis shows NO _x. Concentration (15% O ₂ equivalent value) is shown. Further, the concentration of CO contained in the exhaust gas was all 100 ppm or less.

As shown in FIGS. 14, 16, 18, and 19, the low NO _x burner 31 of Reference Example 1 realized the slow combustion by supplying the fuel 41 so as not to block the flow of the air 42. In the temperature distribution measurement in the combustion furnace, the heat spot of the flame disappeared completely, and the amount of NO _x was reduced to about ３ compared with Comparative Example 1. Since the burner 51 of Comparative Example 1 injects fuel 61 and air 62 into the combustion furnace in parallel, slow combustion was realized, but the amount of NO _x exceeded 60 ppm at the maximum. The burner 71 of Comparative Example 2 had a high flame temperature because the fuel 81 and the high-temperature air 82 burned vigorously in the flame holding region, and the amount of NO _x exceeded 300 ppm.

( Reference Example 2)
20 (a) and 20 (b), a plurality of fuel supplies for injecting the fuel 11 supplied from the fuel nozzle 2 from the center of the front end face 14 of the burner body 6 toward the periphery of the front end face 14. It is parallel to the central axis of the burner body 6 at a position that has the hole 3 and is away from the center of the front end face 14 where the fuel supply hole 3 is located and does not intersect the fuel jet injected from the fuel supply hole 3. and produce a low NO _x burner 20 having a plurality of air supply holes 5 for injecting air 12 in the direction. Low NO _x burner 20 of the present embodiment, along with further comprising an auxiliary air nozzle 21 for supplying the auxiliary air 24 which is disposed on the outer peripheral side of the fuel nozzle 2, the front end surface of the burner body 6 of the auxiliary air nozzles 21 The front end surface 14 further includes a flame holding plate having an auxiliary air supply hole 22 for injecting auxiliary air 24 supplied from the auxiliary air nozzle 21 at the front end surface 14, and the auxiliary air nozzle 21 is provided on the burner body 6. It is movable along the central axis. In this reference example , in the case of initial combustion, that is, the temperature in the combustion furnace is in the range of room temperature to 200 ° C., the ratio of the distance H from which the front end face 14 of the auxiliary air nozzle 21 protrudes to the inner diameter D of the auxiliary air nozzle 21 (H / D) was set to 1.6.

(Example 1 )
A plurality of fuel supply holes for injecting the fuel supplied from the fuel nozzle 2 from the center of the front end surface 14 of the burner body 6 toward the periphery of the front end surface 14 as shown in FIGS. 21 (a) and 21 (b). 3 and at a position away from the center of the front end face 14 where the fuel supply hole 3 is located and in a position not intersecting with the fuel jet injected from the fuel supply hole 3, a direction parallel to the central axis of the burner body 6 and produce a low NO _x burner 90 having a plurality of air supply holes 5 for injecting air into. Low NO _x burner 90 of this embodiment, the low temperature combustion fuel nozzles 15 for supplying a fuel for low temperature combustion at the inner circumferential side of the fuel nozzle 2, distribution on the outer peripheral side of the fuel nozzle 2 And an auxiliary air nozzle 21 for supplying auxiliary air provided, and the burner body 6 burns the fuel for low temperature combustion supplied from the low temperature combustion fuel nozzle 15 to the front end surface 14 of the burner body 6. Low temperature combustion fuel supply hole 16 for injecting in a direction parallel to the central axis of the main body 6 and auxiliary air supply for injecting auxiliary air supplied from the auxiliary air nozzle 21 in a direction parallel to the central axis of the burner main body 6 And a hole 22. In addition, on the front end face 14 of the burner body 6, the flame-holding of the low-temperature combustion flame generated by the fuel-jet flow path 19 injected from the fuel supply hole 2 and the fuel jet injected from the low-temperature combustion fuel supply hole 16. It was set as the structure further equipped with the cylindrical flame-holding block 18 which has the flame-holding space 27 for performing. In the present embodiment, the ratio (H / D) of the height H of the flame holding space 27 to the diameter D in the cross section perpendicular to the central axis of the burner body 6 of the flame holding space 27 constituting the flame holding block 18. 1.6. In the present embodiment, a plurality of grooves are formed in the outer peripheral portion of the flame holding block 18, and the groove at the connection portion between the burner body 6 and the flame holding block 18 is used as the air supply hole 5.

(Example 2 )
The auxiliary air supply hole allows the auxiliary air supplied from the auxiliary air nozzle to be a circle of a circle centering on the central axis of the burner body in a cross section perpendicular to the central axis of the burner body from a direction parallel to the central axis of the burner body. Except for being configured to inject in a direction inclined at an angle of 30 ° or less in the circumferential tangential direction, it was configured in the same manner as the low NO _x burner 90 shown in FIGS. 21 (a) and 21 (b). A low NO _x burner was produced.

A low NO _x burner 20 of Reference Example 2 shown in FIG. 20 (a), the stability of the primary combustion in the low-temperature region of the low NO _x burner 90 of Examples 1 and 2 shown in FIG. 21 (a), That, CO emissions in the primary combustion of each low NO _x burners 20 and 90, and the measurement of misfire of the primary combustion was performed. Specifically, as the combustion condition, methane was used as the fuel 11 and combustion was performed with room temperature air in the combustion furnace, and the temperature in the combustion furnace was changed in the experiment, but was in the range of room temperature to about 200 ° C. The sum of the air 12 used for the secondary combustion and the auxiliary air 24, that is, the total air amount is fixed at 200 NL / min, and the auxiliary air 24 is fixedly supplied within a range of 10 to 60 NL / min. The fuel flow rate was varied between 1 and 14 NL / min. It was made to burn by each fuel condition, it was confirmed whether it would not misfire, and CO concentration (ppm) contained in combustion exhaust when not misfiring was measured. The relationship between the concentration of CO (ppm) for generating a flow rate (NL / min) of the fuel in the low NO _x burner of Reference Example 2 in Figure 22, the fuel in the low NO _x burner for Example 1 in FIG. 23 flow rate ( the relationship between the NL / min) and the concentration of CO generated (ppm), the relationship between the CO concentration (ppm) for generating a fuel flow (NL / min) in the low NO _x burner of the second embodiment in FIG. 24, respectively Show. In Reference Example 2, the flow rate of auxiliary air is measured for five types of 10, 20, 30, 40, and 60 NL / min. In Examples 1 and 2 , three types of 20, 25, and 30 NL / min are measured. Was measured.

As shown in FIG. 22, in Reference Example 2, the range of fuel flow that can be combusted with a fixed amount of auxiliary air is narrow, but the CO concentration is around 50 ppm when the ratio of the auxiliary air flow rate to the fuel flow rate is close to the equivalent ratio. It showed a low value. That is, by setting the auxiliary air flow rate close to the equivalence ratio according to the fuel flow rate, stable combustion was possible in a wide fuel flow range.

As shown in FIGS. 23 and 24, in Examples 1 and 2 , even when auxiliary air is fixed and supplied at a small amount of about 20 to 30 NL / min, combustion is possible in a very wide fuel flow range. there were. In particular, the low NO _x burner of the first embodiment, CO concentration in a wide fuel flow range was as low as before and after 100 ppm. The low NO _x burner of Example 2, although slightly CO concentration than the low NO _x burner in Example 1 was high, it was possible combustion in a wider range.

Further, in the low NO _x burner of Examples 1 and 2, although both the fuel flow rate resulted in CO concentration increases abruptly at 10 NL / min or more, when used for combustion in the actual combustion furnace When the fuel flow rate is less than 10 NL / min and the furnace temperature is raised to 700 ° C. or higher, CO generated by the reaction in the entire combustion furnace is completely burned at 700 ° C. or higher. Can be no problem.

As described above, the low NO _x burner of the present invention, a combustion furnace, for example, in a combustion furnace for industrial, if burned in a high temperature, or preheated combustion air to a high temperature by using a heat storage body such as a combustion In this case, the amount of NO _x contained in the exhaust gas can be reduced.

An explanatory view schematically showing a basic structure of a low NO _x burner for use in low NO _x burner of the present invention, FIG. 1 (a) is a cross-sectional view, FIG. 1 (b) shows a plan view. Oite to low NO _x burners, fuel nozzle is a plan view showing a case where it is installed six. Other forms state of low NO _x burners are explanatory views schematically showing FIG. 3 (a) is a cross-sectional view, FIG. 3 (b) shows a plan view. 4 (a) is a sectional view showing a state of combustion with a definitive auxiliary air to the low NO _x burners, FIG. 4 (b), stops the supply of the definitive auxiliary air to the low NO _x burners or It is sectional drawing which shows the state of the combustion at the time of reducing. 5 (a) is a sectional view showing a state of a combustion with definitive auxiliary air to the low NO _x burners, FIG. 5 (b), stops the supply of the definitive auxiliary air to the low NO _x burners or It is sectional drawing which shows the state of the combustion at the time of reducing. The definitive auxiliary air supply hole to the low NO _x burners are explanatory views schematically showing, FIGS. 6 (a) is a sectional view, FIG. 6 (b) is a plan view. It is explanatory drawing which shows typically one Embodiment of the low NOx burner of this invention, Comprising _: Fig.7 (a) shows sectional drawing, FIG.7 (b) shows a top view. The auxiliary air supply hole in another embodiment of the low NO _x burner of the present invention an explanatory view schematically showing Fig. 8 (a) cross-sectional view, FIG. 8 (b) is a plan view. The auxiliary air supply hole in another embodiment of the low NO _x burner of the present invention an explanatory view schematically showing, 9 (a) is a cross-sectional view, FIG. 9 (b) is a plan view. The auxiliary air supply hole in another embodiment of the low NO _x burner of the present invention an explanatory view schematically showing FIG. 10 (a) is a cross-sectional view, FIG. 10 (b) is a plan view. It is explanatory drawing which shows typically other embodiment of the low NOx burner of this invention, Comprising _: Fig.11 (a) shows sectional drawing, FIG.11 (b) shows a top view. It is explanatory drawing which shows typically other embodiment of the low NOx burner of this invention, Comprising _: Fig.12 (a) shows sectional drawing, FIG.12 (b) shows a top view. It is explanatory drawing which shows typically the low NOx burner of the reference example 1 of this invention, Comprising _: Fig.13 (a) shows sectional drawing, FIG.13 (b) shows a top view. And the temperature in the combustion furnace upon combustion of low NO _x burners of Reference Example 1 of the present invention (° C.), is a graph showing the relationship between the distance between the reference point described above (mm). It is explanatory drawing which shows typically the burner of the comparative example 1 of this invention, Comprising: Fig.15 (a) shows sectional drawing, FIG.15 (b) shows a top view. It is a graph which shows the relationship between the temperature (degreeC) in a combustion furnace at the time of burning the burner of the comparative example 1 of this invention, and the distance (mm) with the reference | standard point mentioned above. It is explanatory drawing which shows typically the low NOx burner of the comparative example 2 of this invention, Comprising _: Fig.17 (a) is sectional drawing, FIG.17 (b) shows a top view. It is a graph which shows the relationship between the temperature (degreeC) in a combustion furnace at the time of burning the burner of the comparative example 2 of this invention, and the distance (mm) with the reference | standard point mentioned above. It shows a low NO _x burner in Reference Example 1 of the present invention, the residual oxygen concentration upon combustion of burners of Comparative Examples 1 and 2 (%), the relationship between the concentration of NO _x (15% O ₂ conversion value) It is a graph. It is explanatory drawing which shows typically the low NOx burner of the reference example 2 of this invention, Comprising _: Fig.20 (a) shows sectional drawing, FIG.20 (b) shows a top view. It is explanatory drawing which shows typically the low NOx burner of Example 1 of this invention, Comprising _: Fig.21 (a) shows sectional drawing, FIG.21 (b) shows a top view. 6 is a graph showing the relationship between the fuel flow rate (NL / min) and the CO concentration (ppm) in the low NO _x burner of Reference Example 2 of the present invention. In the low NO _x burner in Example 1 of the present invention, it is a graph showing the relationship between fuel flow rate (NL / min) and CO concentration (ppm). In the low NO _x burner of the second embodiment of the present invention, it is a graph showing the relationship between fuel flow rate (NL / min) and CO concentration (ppm).

Explanation of symbols

1 ... low-NO _x burners, 2 ... fuel nozzle, 3 ... fuel supply hole, 4 ... air nozzle, 5 ... air supply hole, 6 ... burner body, 8 ... the burner casing, 9 ... regenerator, 11, 11b ... fuel, DESCRIPTION OF SYMBOLS 12 ... Air, 13 ... Air outflow inlet, 14 ... Front end surface, 15 ... Low temperature combustion fuel nozzle, 16 ... Low temperature combustion fuel supply hole, 17 ... Switching valve, 18 ... Flame holding block, 19 ... Flow path, 20 ... low NO _x burners, 21 ... auxiliary air nozzle, 22 ... auxiliary air supply hole, 23 ... flame holding plate, 24 ... auxiliary air, 25 ... primary combustion, 26 ... secondary combustion, 27 ... flame holding space, 28 ... recess, 29: fuel guide passage, 31 ... low-NO _x burners, 32 ... fuel nozzle, 33 ... fuel supply hole 34 ... air nozzle, 35 ... air supply hole 40 ... combustion furnace, 41 ... fuel, 42 ... air , 51 ... burner, 52 ... fuel nozzle, 53 ... fuel supply hole, 4 ... Air nozzle, 55 ... Air supply hole, 60 ... Combustion furnace, 61 ... Fuel, 62 ... Air, 71 ... Burner, 72 ... Fuel nozzle, 73 ... Fuel supply hole, 74 ... Air nozzle, 75 ... Air supply hole, 80 ... combustion furnace, 81: fuel, 82 ... air, 90 ... low-NO _x burners.

Claims (11)

A low NO _x burner comprising a burner body and a fuel nozzle for supplying fuel,
The burner body has, on its front end surface, a plurality of fuel supply holes for injecting the fuel supplied from the fuel nozzle from the center of the front end surface toward the periphery of the front end surface, and the fuel supply holes A plurality of air supply holes for injecting air in a direction parallel to the central axis of the burner body at a position away from the center of the front end surface where the fuel is injected and at a position not intersecting with the fuel jet injected from the fuel supply hole I have a,
Further, the fuel nozzle is disposed on the outer peripheral side of the fuel nozzle in a state in which a tip portion thereof is drawn inward from the front end surface of the burner body, and the fuel for low-temperature combustion is supplied to supply the fuel for low-temperature combustion. An auxiliary air nozzle for supplying auxiliary air, arranged on the outer peripheral side of the fuel nozzle and the fuel nozzle for low temperature combustion in a state in which a tip end portion thereof is drawn inward from the front end surface of the burner body And
Low temperature combustion in which the opening at the tip of the low temperature combustion fuel nozzle injects the low temperature combustion fuel supplied from the low temperature combustion fuel nozzle in a direction parallel to the central axis of the burner body And the opening of the tip of the auxiliary air nozzle serves as an auxiliary air supply hole for injecting the auxiliary air supplied from the auxiliary air nozzle, and the fuel nozzle and the fuel for low temperature combustion low NO _x burners, characterized in that capable of switching the supply of the fuel at the nozzle. A low NO _x burner comprising a burner body and a fuel nozzle for supplying fuel ,
The burner body has, on its front end surface, a plurality of fuel supply holes for injecting the fuel supplied from the fuel nozzle from the center of the front end surface toward the periphery of the front end surface, and the fuel supply holes A plurality of air supply holes for injecting air in a direction parallel to the central axis of the burner body at a position away from the center of the front end surface where the fuel is injected and at a position not intersecting with the fuel jet injected from the fuel supply hole Have
Further, a low temperature combustion fuel nozzle for supplying the fuel for low temperature combustion disposed on the inner peripheral side of the fuel nozzle and an auxiliary air disposed on the outer peripheral side of the fuel nozzle are supplied. An auxiliary air nozzle for
Low temperature combustion fuel supply hole for injecting the fuel for low temperature combustion supplied from the low temperature combustion fuel nozzle to the front end face of the burner main body in a direction parallel to the central axis of the burner main body. And an auxiliary air supply hole for injecting the auxiliary air supplied from the auxiliary air nozzle, and at a predetermined temperature in a combustion atmosphere near the front end surface, the fuel nozzle and the fuel nozzle for low temperature combustion The low NO _x burner is characterized in that the fuel supply can be switched . In order to hold the low-temperature combustion flame generated by the fuel jet flow injected from the fuel supply hole and the fuel jet injected from the low-temperature combustion fuel supply hole on the front end surface of the burner body The low NO _x burner according to claim 2 , further comprising a cylindrical flame holding block having a flame holding space . Low NO _x burner as claimed in claim 3 the shape of the flame holding space is a cylindrical constituting the flame holding block. The ratio of the height of the flame holding space to the diameter in a cross section perpendicular to the central axis of the burner body of the flame holding space constituting the flame holding block is 1.5 to 2. 5 . Low NO _x burner. The auxiliary air is centered on the central axis of the burner body in a cross section perpendicular to the central axis of the burner body from a direction parallel to the central axis of the burner body or a direction parallel to the central axis of the burner body. low NO _x burner as claimed in any one of claims 1 to 5 for injecting the circumferential tangential direction of a circle in a direction inclined at an angle of 30 ° or less. Low NO _x burner according to yet claim 1 having a heat storage body to the upstream side of the air supply hole. The fuel nozzle is arranged at the center of the front end surface of the burner body such that the tip end protrudes outward from the front end surface of the burner body, and the fuel supply hole is the tip end portion of the fuel nozzle. on the side wall of the low NO _x burner as claimed in any one of claims 1 to 7, through the central axis perpendicular direction of the burner body is disposed. The air nozzle for supplying the air is further provided, and the air nozzle is disposed so as to protrude outward from the front end surface of the burner body. low NO _x burner as claimed in claim 1 comprising a. The low NO according to any one of claims 1 to 9, wherein a plurality of the auxiliary air supply holes are dispersedly disposed on the front end surface of the burner body, outside the low temperature combustion fuel supply holes. _x Burner. The ratio of the space | interval of the said air supply hole and the said low temperature combustion fuel supply hole with respect to the internal diameter of the said low temperature combustion fuel supply hole is 15-20, Low NO in any one of Claims 1-10 _x Burner.

Images