JP2023096456A - burner and combustion furnace - Google Patents

Abstract

To propose a structure which enables improvement of combustion efficiency of a gas fuel while inhibiting disturbance of a circular vortex and deterioration of combustion reaction in the circular vortex in a burner using the gas fuel as a supplementary fuel.SOLUTION: A burner includes: a first nozzle having a main fuel outlet which jets air-fuel mixture of a main fuel and primary combustion air and a flame holding plate disposed around the main fuel outlet; a second nozzle arranged coaxially with the first nozzle and having a secondary air outlet which blows out secondary combustion air at an outer periphery of the main fuel outlet; and multiple supplementary fuel injection nozzles extending along an outer surface of the first nozzle in parallel to a burner axis. The multiple supplementary fuel injection nozzles have multiple supplementary fuel outlets arranged along an outer peripheral edge of the flame holding plate or multiple supplementary fuel outlets disposed at the inner side of the outer peripheral edge and the outer side of an inner peripheral edge of the flame holding plate. The multiple supplementary fuel outlets jet a gas fuel serving as a supplementary fuel toward a border portion between flow of the air-fuel mixture and flow of the secondary combustion air.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to burners using gaseous fuel as auxiliary fuel and combustion furnaces equipped with such burners.

Due to the trend of carbon dioxide (CO ₂ ) reduction, the use of CO ₂ -free fuel that does not generate carbon dioxide in thermal boilers is required. Examples of such fuel include hydrogen (H ₂ ) and ammonia (NH ₃ ), which are hydrogen-rich gas fuels. For example, Patent Literature 1 discloses a burner capable of co-firing solid fuel and ammonia.

The burner of Patent Document 1 includes a fuel supply nozzle that ejects a mixture of a solid fuel such as pulverized coal and a carrier gas for the solid fuel, and is disposed outside the fuel supply nozzle to direct combustion air from the mixture in a radial direction. An air nozzle that separates and blows out to the outside, and an ammonia supply nozzle that blows ammonia gas from the downstream side of the outlet of the fuel supply nozzle are provided. The ammonia supply nozzle supplies ammonia gas toward a reduction zone (primary combustion zone) immediately downstream of the outlet of the fuel supply nozzle where oxygen is consumed by fuel combustion and has a low oxygen concentration.

JP 2019-203631 A

In the burner structure disclosed in US Pat. No. 5,200,000, the strongest high-temperature reduction region is formed forward between the outlet of the fuel supply nozzle and the outlet of the air nozzle, where the secondary A circulation vortex is formed by the flow of air and tertiary air. Since combustible components and heat are accumulated in the circulation vortex, the conditions for easy combustion are maintained, and it becomes a starting point of ignition, and a high-temperature reduction region is formed in the circulation vortex and downstream of the circulation vortex. Therefore, it is believed that jetting gaseous fuel such as ammonia toward the circulation vortex is more advantageous than jetting ammonia toward the primary combustion region as in Patent Document 1 in order to increase combustion efficiency. On the other hand, when the gas fuel is ejected toward the circulation vortex, if the flow rate of the gas fuel increases, the flow of the circulation vortex is disturbed by the jet of gas fuel, and the flow of the circulation vortex is disturbed by the inflow of unreacted gas fuel. There is concern that the combustion reaction in the circulating vortex will be suppressed due to the temperature drop.

The present disclosure has been made in view of the above circumstances. The purpose is to propose a structure that can improve the combustion efficiency of

In order to solve the above problems, a burner according to one aspect of the present disclosure includes:
a first nozzle having a cylindrical shape centered on the burner axis and having a main fuel outlet for ejecting a mixture of main fuel and primary combustion air, and a flame stabilizing plate disposed around the main fuel outlet;
a second nozzle disposed coaxially with the first nozzle and having a secondary air outlet for blowing out secondary combustion air at an outer periphery of the main fuel outlet;
a plurality of auxiliary fuel injection nozzles extending parallel to the burner axis along the outer surface of the first nozzle;
The plurality of auxiliary fuel injection nozzles include a plurality of auxiliary fuel outlets arranged along the outer peripheral edge of the flame stabilization plate, or a plurality of auxiliary fuel outlets arranged inside the outer peripheral edge of the flame stabilization plate and outside the inner peripheral edge of the flame stabilization plate. an outlet, wherein the plurality of auxiliary fuel outlets directs a flow of auxiliary fuel toward a boundary between a flow of the air-fuel mixture exiting the main fuel outlet and a flow of the secondary combustion air exiting the secondary air outlet; It is characterized by ejecting gas fuel.

Further, the combustion furnace according to one aspect of the present disclosure includes
a hot reduction zone with a reducing atmosphere, provided with at least one of said burners;
and a low-temperature oxidation zone having a lower temperature and an oxidizing atmosphere than the high-temperature reduction zone, into which the combustion gas generated in the high-temperature reduction zone flows.

According to one aspect of the present disclosure described above, in a burner that uses gas fuel as an auxiliary fuel, the combustion efficiency of the gas fuel is improved while suppressing disturbance of the circulation vortex and deterioration of the combustion reaction in the circulation vortex. We can propose a structure that can be enhanced.

FIG. 1 is a diagram showing a schematic configuration of a boiler equipped with a burner according to one embodiment of the present disclosure. 2 is a schematic cross-sectional view of a burner according to the present disclosure; FIG. 3 is an enlarged sectional view of the outlet of the burner shown in FIG. 2; FIG. FIG. 4 is a view of the outlet of the burner viewed from the front in the axial direction of the burner. FIG. 5 is a view of the outlet of the burner according to Modification 1 as viewed from the front in the axial direction of the burner. FIG. 6 is a view of the outlet of the burner according to Modification 2 as viewed from the front in the axial direction of the burner. FIG. 7 is a view of the outlet of the burner according to Modification 2 as viewed from the front in the axial direction of the burner. FIG. 8 is an enlarged cross-sectional view of a burner outlet according to Modification 2. FIG.

Embodiments of the present disclosure will be described below with reference to the drawings. First, a schematic configuration of a boiler 10 including a burner 5 according to an embodiment of the present disclosure will be described.

[Schematic configuration of boiler 10]
FIG. 1 is a diagram showing a schematic configuration of a boiler 10 including a burner 5 according to one embodiment of the present disclosure. The boiler 10 shown in FIG. 1 includes a combustion furnace 2 that burns fuel, and a boiler body 40 that uses the combustion heat to generate steam. The boiler 10 is a pulverized coal-fired thermal boiler, and uses powdered or granular fossil fuel (solid fuel) as main fuel. However, the boiler to which the burner 5 according to the present disclosure is applied is not limited to a pulverized coal-fired boiler, and may be a mixed combustion boiler using pulverized coal and biomass as the main fuel, a petroleum residue-fired boiler using petroleum residue as the main fuel, etc. may

A vertical combustion chamber 20 is formed inside the combustion furnace 2 . The combustion furnace 2 according to the present embodiment is an inverted vertical furnace. A throttle section 23 is provided between the reduction zone 21 and the low-temperature oxidation zone 22 . However, the combustion furnace 2 may be a vertical furnace in which the high temperature reduction zone 21 is formed in the lower part of the combustion chamber 20 and the low temperature oxidation zone 22 is formed in the upper part of the combustion chamber 20 . Alternatively, the combustion furnace 2 to which the burner 5 according to the present disclosure is applied may be a combustion furnace other than the vertical furnace.

A portion of the inner wall of the combustion furnace 2 that forms the high-temperature reduction zone 21 is covered with a refractory material 25 . The upper furnace wall of the combustion furnace 2 is provided with a plurality of burners 5 for blowing out fuel and first-stage combustion air to the high-temperature reduction zone 21 . A mixture of fuel and air is blown out from each burner 5 into the combustion chamber 20 to generate a flame. A plurality of burners 5 are provided on each of a pair of opposing furnace walls. Each furnace wall is provided with at least one burner stage in the vertical direction, and each burner stage is formed by a plurality of burners 5 arranged horizontally. The plurality of burners 5 facing each other in this way are arranged in a staggered manner so that the burner axes of the burners 5 do not cross each other.

The outlet of the high-temperature reduction zone 21 is connected to the inlet of the low-temperature oxidation zone 22 via a throttle 23 . The smallest horizontal cross-sectional area of the constricted portion 23 is about 20 to 50% of the horizontal cross-sectional area of the high temperature reduction zone 21 .

A plurality of air nozzles 26 are provided on the lower furnace wall of the combustion furnace 2 . Air for second stage combustion is blown from each air nozzle 26 into the low temperature oxidation zone 22 . In this embodiment, a plurality of stages of air nozzles are provided in the vertical direction, and each air nozzle stage is formed by a plurality of air nozzles 26 aligned in the horizontal direction. In the low-temperature oxidation zone 22 , a cooling section 24 is formed between the constricted section 23 and the plurality of air nozzles 26 . A furnace wall of the cooling unit 24 is a water-cooled wall in which water pipes (not shown) of the boiler body 40 are stretched.

The outlet 11 of the low temperature oxidation zone 22 is connected with the inlet of the flue 28 . A heat transfer tube 43 of a boiler body 40 is provided in the flue 28 . An exhaust gas treatment system 30 is connected to the outlet of the flue 28 .

In the boiler 10 configured as described above, the air ratio between the fuel supplied to the high-temperature reduction zone 21 and the air for the first-stage combustion is maintained at less than 1 (for example, about 0.7). In addition, the high temperature reduction zone 21 covered with the refractory material 25 is less susceptible to temperature drop in the furnace than the rest of the furnace. As a result, the high-temperature reduction zone 21 has a high-temperature reduction atmosphere of about 1500° C. on average (an air-deficient atmosphere in which the amount of air is lower than the theoretical amount of air), and the gasification of the fuel is promoted in the high-temperature reduction zone 21. .

In the high temperature reduction zone 21, the fuel is gasified to produce combustion gases. The resulting combustion gas flows through the throttle 23 into the low temperature oxidation zone 22 . The second stage combustion air supplied from the air nozzle 26 to the low temperature oxidation zone 22 maintains the air ratio of the low temperature oxidation zone 22 at 1 or more (for example, about 1.1). As a result, the low-temperature oxidation zone 22 has an oxidizing atmosphere, and the combustion of the combustion gas is promoted in the low-temperature oxidation zone 22 .

In the low-temperature oxidation zone 22, combustion of unburned components in the combustion gas is completed. Flue gas from the low temperature oxidation zone 22 exits through a flue 28 to an exhaust gas treatment system 30 . The heat of the flue gas is recovered by the flue 28 and the heat transfer tubes 43 provided on the furnace wall, and steam is generated in the boiler main body 40 . The generated steam is utilized, for example, in steam turbines of power plants.

[Burner 5]
The burner 5 provided in the boiler 10 configured as described above is a co-combustion burner that uses a solid fuel as a main fuel and a hydrogen-containing gaseous fuel as an auxiliary fuel. Solid fuels are fossil fuels in powder or granular form, for example pulverized coal. In this embodiment, ammonia gas containing hydrogen and nitrogen is used as the gas fuel. However, hydrogen gas or by-product gas generated in a plant may be used as the gas fuel.

FIG. 2 is a schematic cross-sectional view of a burner 5 according to the present disclosure, and FIG. 3 is an enlarged view near the exit of burner 5 of FIG. As shown in FIGS. 2 and 3, the burner 5 is provided with multiple nozzles consisting of a first nozzle 71, a second nozzle 72 and a third nozzle 73 arranged coaxially around a predetermined burner axis 70. FIG. The extending direction of the burner axis 70 is called "burner axis direction X".

The first nozzle 71 is supplied with powdery solid fuel and carrier air that carries the solid fuel. The carrier air becomes primary air (primary combustion air). A circumferentially continuous first flame stabilization plate 77 is provided at the downstream end of the first nozzle 71 . The first flame stabilization plate 77 expands in diameter like a trumpet toward the downstream end of the first nozzle 71 . A primary fuel outlet 71 a is formed at the downstream end of the first nozzle 71 by the first flame stabilization plate 77 . A mixture 51 of solid fuel and carrier air is ejected from the main fuel outlet 71a.

A turning adjustment plate 711 is provided inside the downstream end of the first nozzle 71 and upstream of the first flame stabilization plate 77 . A dispersion vane 713 is provided upstream of the swirl adjustment plate 711 within the first nozzle 71 .

A heavy oil burner 79 through which the burner axis 70 passes is inserted in the axial center of the first nozzle 71 . The downstream end of the heavy oil burner 79 is positioned near the downstream end of the first nozzle 71 . Therefore, the cross section of the flow passage at the downstream end of the first nozzle 71 has an annular shape centered on the burner axis 70 .

A second nozzle 72 is provided on the outer circumference of the first nozzle 71 . Between the first nozzle 71 and the second nozzle 72, a second flow path 72f having an annular cross section is formed. Secondary air 52 (secondary combustion air) is supplied from the wind box to the second flow path 72f. The secondary air outlet 72a, which is the downstream end of the second flow path 72f, is positioned on the outer periphery of the main fuel outlet 71a and blows out the secondary air 52 to the outer peripheral side of the air-fuel mixture 51 jetted from the main fuel outlet 71a.

A third nozzle 73 is provided on the outer circumference of the second nozzle 72 . Between the third nozzle 73 and the second nozzle 72, a third channel 73f having a circular channel cross section is formed. Tertiary air 53 (tertiary combustion air) is supplied from the wind box to the third flow path 73f. The tertiary air outlet 73a, which is the downstream end of the third flow path 73f, is positioned on the outer peripheral side of the secondary air outlet 72a, and blows off the tertiary air 53 on the outer peripheral side of the secondary air 52 ejected from the secondary air outlet 72a.

The downstream end of the second nozzle 72 is provided with a second flame stabilizing plate 72b whose diameter increases like a trumpet as it goes downstream. Furthermore, an outer guide 73b is provided at the opening edge of the downstream end of the third nozzle 73, the diameter of which expands like a trumpet as it goes downstream. The secondary air 52 ejected from the secondary air outlet 72a is guided away from the air-fuel mixture 51 ejected from the first nozzle 71 by the first flame stabilization plate 77 and the second flame stabilization plate 72b. Further, the tertiary air 53 ejected from the third nozzle 73 is guided away from the secondary air 52 ejected from the second nozzle 72 by the second flame stabilizing plate 72b and the outer guide 73b.

FIG. 4 is a view of the outlet of the burner 5 viewed from the front in the axial direction X of the burner. As shown in FIGS. 2, 3 and 4, a plurality of auxiliary fuel injection nozzles 91 are arranged circumferentially on the outer surface of the first nozzle 71 . The diameter of the auxiliary fuel injection nozzle 91 is sufficiently smaller than the diameter of the first nozzle 71 . Each auxiliary fuel injection nozzle 91 extends in the burner axial direction X along the outer surface of the first nozzle 71 . In order not to block the flow of the secondary air 52 in the second flow path 72f, it is desirable that the auxiliary fuel injection nozzle 91 extend along the outer surface of the first nozzle 71. As shown in FIG. In this embodiment, each auxiliary fuel injection nozzle 91 is joined to the outer surface of the first nozzle 71 so that the plurality of auxiliary fuel injection nozzles 91 and the first nozzle 71 are integrated. The first nozzle 71 and the auxiliary fuel injection nozzle 91 may be chemically joined by welding, or may be mechanically joined by bolts or the like.

Gas fuel 90 is supplied from a gas fuel source to the first flow path 91f in the auxiliary fuel injection nozzle 91 . Gas fuel 90 is jetted out from an auxiliary fuel outlet 91 a that is the downstream end of the auxiliary fuel injection nozzle 91 . Also, the first flow path 91f may be configured to be supplied with combustion air in addition to the gas fuel 90 . In this case, the gas ejected from the auxiliary fuel outlet 91a may be switchable between gas fuel 90, combustion air, and a mixture of gas fuel 90 and combustion air.

A plurality of auxiliary fuel outlets 91a are positioned between the main fuel outlets 71a and the secondary air outlets 72a. The plurality of auxiliary fuel outlets 91 a are arranged in the circumferential direction along the outer peripheral edge of the first flame stabilization plate 77 provided at the downstream end of the first nozzle 71 . It is desirable that the plurality of auxiliary fuel outlets 91a be evenly arranged in the circumferential direction. In the example shown in FIG. 4, the plurality of auxiliary fuel injection nozzles 91 are in contact with the outer peripheral edge of the first flame stabilization plate 77, and the plurality of auxiliary fuel outlets 91a are slightly outside the outer peripheral edge of the first flame stabilization plate 77. is arranged along the outer peripheral edge of the first flame stabilization plate 77 at .

In the burner 5 configured as described above, the mixed gas 51 of solid fuel and primary air supplied to the first nozzle 71 is ejected as a swirling flow from the main fuel outlet 71a by the action of the dispersing vane 713 and the swirl adjusting plate 711 . Further, on the outer peripheral side of the main fuel outlet 71a, the secondary air 52 is blown out from the secondary air outlet 72a, and the tertiary air 53 is blown out from the tertiary air outlet 73a. The secondary air 52 is blown out so as to expand radially outward around the burner axis 70 by the action of the first flame stabilization plate 77 and the second flame stabilization plate 72b. Similarly, the tertiary air 53 is blown out so as to expand radially outward due to the action of the second flame stabilization plate 72b and the outer guide 73b.

At the boundary between the air-fuel mixture 51 and the secondary air 52, a circulating vortex 55 is generated due to the pressure drop. High temperature combustion gas stays in the circulation vortex 55 . In this embodiment, as shown in FIG. 3, an outer circulation vortex 55a and an inner circulation vortex 55b closer to the burner axis 70 than the outer circulation vortex 55a are formed. Each of the outer circulating vortex 55a and the inner circulating vortex 55b is composed of a forward flow toward the downstream side and a reverse flow returning toward the upstream side. The swirl of the tertiary air 53 forms the circulation area 50 radially inside the circulation vortex 55 . In the circulation region 50, a circulation flow is generated in which the jet flow of the air-fuel mixture 51 emitted from the main fuel outlet 71a is returned to the main fuel outlet 71a, and the hot combustion gas and the unburned circulation gas are constantly exchanged. As a result, the volatile components of the solid fuel in the air-fuel mixture 51 are quickly combusted, and the circulation vortex 55 generates an outer peripheral ignition flame. Combustion occurs by mixing the combustion air and the air-fuel mixture 51 step by step in the order of the secondary air 52 and the tertiary air 53 .

The burner 5 can switch between solid fuel mono-firing, gas fuel mono-firing, and solid fuel and gas fuel co-firing. During the mono-combustion of the solid fuel, the combustion air is supplied to the first flow path 91f, or the supply of the gas fuel to the first flow path 91f is stopped. During mono-firing of gas fuel, combustion air is supplied to the first nozzle 71 and gas fuel is supplied to the first flow path 91f. During co-firing of the solid fuel and the gas fuel, the solid fuel and the combustion air are supplied to the first nozzle 71 and the gas fuel 90 is supplied to the first flow path 91f. In the burner 5 , such switching between mono-firing and mixed-firing can be performed without stopping the operation of the boiler 10 .

The flow of the gaseous fuel 90 ejected from the auxiliary fuel outlet 91a joins the outermost flow of the circulation vortex 55, that is, the forward flow directed downstream. As a result, the gas fuel 90 is taken into the circulation vortex 55, which is the starting point of ignition, so that the gas fuel 90 can be efficiently burned.

[Modification 1 of Burner 5]
FIG. 5 is a view of the outlet of the burner 5A according to Modification 1 as viewed from the front in the axial direction X of the burner. In the burner 5A according to Modification 1 shown in FIG. 5, the arrangement of the auxiliary fuel outlet 91a of the auxiliary fuel injection nozzle 91 is different from that of the burner 5 according to the above embodiment. In the burner 5A according to Modification 1, a plurality of notches are provided in the outer peripheral edge of the first flame stabilization plate 77, and the downstream end of the auxiliary fuel injection nozzle 91 passes through the notches. The cross section of the notch may have a shape in which a part or all of the cross section of the auxiliary fuel injection nozzle 91 is fitted. In this case, a portion of the auxiliary fuel outlet 91 a is arranged inside the outer peripheral edge of the first flame stabilization plate 77 , and the remaining portion is arranged outside the outer peripheral edge of the first flame stabilization plate 77 . In the burner 5A according to Modification 1, as a result of reducing the unevenness of the outer peripheral edge of the first flame stabilization plate 77, the auxiliary fuel outlet 91a reduces the flow of the secondary air 52 blown out from the secondary air outlet 72a and the flow of the main fuel. It is possible to suppress the influence on the flow of the air-fuel mixture 51 blown out from the outlet 71a.

[Modification 2 of Burner 5]
FIG. 6 is a view of the outlet of the burner 5B according to Modification 2 as viewed from the front in the axial direction X of the burner. As shown in FIG. 6, in the burner 5B according to Modification 2, a plurality of inner and outer auxiliary fuel outlets 91a are arranged at the same rotational position about the burner axis 70. As shown in FIG. In addition, the plurality of inner and outer auxiliary fuel outlets 91 a are arranged inside the outer peripheral edge of the first flame stabilization plate 77 and outside the inner peripheral edge of the first flame stabilization plate 77 . In the example shown in FIG. 6 , the downstream end of the auxiliary fuel injection nozzle 91 penetrates the first flame stabilization plate 77 . However, as shown in FIG. 7, a plurality of fan-shaped cutouts 77a may be provided in the outer peripheral edge of the first flame stabilization plate 77, and the downstream end of the auxiliary fuel injection nozzle 91 may pass through the cutouts 77a. .

FIG. 8 is an enlarged cross-sectional view of the outlet of the burner 5B according to Modification 2. As shown in FIG. As shown in FIG. 8, the flow of the gas fuel 90 ejected from the inner auxiliary fuel outlet 91a joins the forward flow toward the downstream side in the inner circulation vortex 55b. In other words, the position and direction of the inner auxiliary fuel outlet 91a are adjusted so that the flow of the gas fuel 90 ejected from the inner auxiliary fuel outlet 91a joins the forward flow toward the downstream side in the inner circulation vortex 55b. Further, the flow of the gaseous fuel 90 ejected from the outer auxiliary fuel outlet 91a joins the forward flow toward the downstream side in the outer circulation vortex 55a. In other words, the position and direction of the outer auxiliary fuel outlet 91a are adjusted so that the flow of the gaseous fuel 90 ejected from the outer auxiliary fuel outlet 91a joins the forward flow toward the downstream side in the outer circulation vortex 55a. In this manner, by supplying the gas fuel 90 to each of the outer circulation vortex 55a and the inner circulation vortex 55b, it is possible to increase the co-firing rate of the gas fuel 90 while suppressing the ejection flow velocity of the gas fuel 90 from each auxiliary fuel outlet 91a. can.

[Summary]
As described above, the burners 5, 5A, 5B according to the present disclosure are
A second burner having a cylindrical shape centered on the burner axis 70 and having a main fuel outlet 71a for ejecting a mixture 51 of main fuel and primary combustion air, and a flame stabilizing plate 77 arranged around the main fuel outlet 71a. 1 nozzle 71;
a second nozzle 72 arranged coaxially with the first nozzle 71 and having a secondary air outlet 72a for blowing the secondary combustion air 52 on the outer periphery of the main fuel outlet 71a;
and a plurality of auxiliary fuel injection nozzles 91 extending parallel to the burner axis 70 along the outer surface of the first nozzle 71 . and,
The plurality of auxiliary fuel injection nozzles 91 are a plurality of auxiliary fuel outlets 91a arranged along the outer peripheral edge of the flame stabilizing plate 77, or a plurality of auxiliary fuel outlets 91a arranged inside the outer peripheral edge of the flame stabilizing plate 77 and outside the inner peripheral edge. Auxiliary fuel outlets 91a are provided, and a plurality of auxiliary fuel outlets 91a are directed to the boundary between the flow of air-fuel mixture 51 from the main fuel outlet 71a and the flow of secondary air 52 from the secondary air outlet 72a as auxiliary fuel. of gas fuel 90 is ejected.

According to the burners 5, 5A, and 5B configured as described above, the gaseous fuel 90 emitted from the auxiliary fuel outlet 91a flows toward the circulation vortex 55 generated at the boundary between the flow of the air-fuel mixture 51 and the flow of the secondary air 52. As a result, the gas fuel 90 is taken into the circulation vortex 55, which is the starting point of ignition, and the gas fuel 90 can be efficiently burned. In addition, since the gas fuel 90 is dispersed and ejected from a plurality of auxiliary fuel outlets 91a, the injection flow velocity for supplying the same amount of gas fuel 90 can be suppressed lower than when there is a single auxiliary fuel outlet 91a. can be done. As a result, it is possible to prevent the circulation vortex 55 from being disturbed by the ejected gas fuel 90 and the combustion reaction in the circulation vortex 55 from slowing down due to the temperature drop of the circulation vortex 55 . From the viewpoint of keeping the injection flow velocity low, at least two auxiliary fuel outlets 91a are sufficient, but a large number is desirable.

In the burners 5 , 5</b>A, 5</b>B configured as described above, the plurality of auxiliary fuel injection nozzles 91 may be joined to the outer surface of the first nozzle 71 .

As a result, the plurality of auxiliary fuel injection nozzles 91 and the first nozzles 71 can be handled integrally. In addition, since the plurality of auxiliary fuel injection nozzles 91 are arranged along the outer surface of the first nozzle 71, the influence of the plurality of auxiliary fuel injection nozzles 91 on the flow field of the secondary air 52 in the second flow path 72f can be suppressed. can be done.

In the burners 5A and 5B configured as described above, the downstream ends of the plurality of auxiliary fuel injection nozzles 91 may pass through the flame stabilization plate 77 .

This makes it possible to provide the auxiliary fuel outlet 91 a inside the outer peripheral edge of the flame stabilization plate 77 .

In the burner 5A configured as described above, the flame stabilization plate 77 has a plurality of notches on the outer peripheral edge, and the downstream ends of the plurality of auxiliary fuel injection nozzles 91 may pass through the notches.

This makes it possible to provide the auxiliary fuel outlet 91 a inside the outer peripheral edge of the flame stabilization plate 77 . In addition, unevenness of the outer peripheral edge of the flame stabilization plate 77 can be suppressed.

In the burners 5, 5A, and 5B having the above configuration, the plurality of auxiliary fuel outlets 91a direct gas toward the downstream side of the circulation vortex 55 generated at the boundary between the flow of the mixture 51 and the flow of the secondary air 52. It may be configured to eject fuel 90 .

If the fuel gas 90 blows out so as to come into contact with the upstream flow of the circulation vortex 55 , the circulation vortex 55 may be disturbed by the flow of the fuel gas 90 . On the other hand, in the burners 5, 5A, and 5B according to the present disclosure, the gas fuel 90 is ejected toward the forward flow toward the downstream side of the circulation vortex 55, so the gas fuel 90 circulates without disturbing the flow of the circulation vortex 55. Entrained in vortex 55 .

In the burner 5B configured as described above, the circulating vortex 55 includes an outer circulating vortex 55a and an inner circulating vortex 55b closer to the burner axis 70 than the outer circulating vortex 55a,
The plurality of auxiliary fuel outlets 91a includes an inner auxiliary fuel outlet 91a and an outer auxiliary fuel outlet 91a that are arranged at substantially the same rotational position about the burner axis 70, and the inner auxiliary fuel outlet 91a is for internal circulation. The gas fuel 90 is ejected toward the downstream side of the vortex 55b, and the outer auxiliary fuel outlet 91a is configured to eject the gas fuel 90 toward the downstream side of the outer circulation vortex 55a. good.

As a result, even when the flow rate of the gas fuel 90 is increased, the gas fuel 90 ejected from the plurality of auxiliary fuel outlets 91a is dispersedly supplied to the outer circulation vortex 55a and the inner circulation vortex 55b. 55 can be suppressed. In addition, it is possible to prevent the circulation vortex 55 from being disturbed by the ejected gas fuel 90 and the combustion reaction in the circulation vortex 55 from slowing down due to the temperature drop of the circulation vortex 55 .

In the burners 5, 5A, 5B described above, the plurality of auxiliary fuel outlets 91a may be switchable so as to blow combustion air instead of the gaseous fuel 90.

According to the burners 5, 5A, and 5B configured as described above, the burner 5 can be switched between combustion of only the main fuel and combustion of the main fuel and the auxiliary fuel. Although solid fuel is used as the main fuel in the above embodiment, the main fuel may be gas fuel or liquid fuel. Also, the main fuel and the auxiliary fuel may be the same type of fuel. Alternatively, in the burners 5, 5A, 5B configured as described above, the gas fuel 90 may be ammonia gas.

Further, the combustion furnace 2 according to the present disclosure includes a high temperature reduction zone 21 with a reducing atmosphere, provided with at least one of the above-described burners 5, 5A, 5B, and a high temperature reduction zone 21 into which the combustion gas generated in the high temperature reduction zone 21 flows. a low-temperature oxidation zone 22 having a lower temperature and an oxidizing atmosphere than the reduction zone 21 .

According to the combustion furnace 2 having the above configuration, the solid fuel and the nitrogen-rich gas fuel are co-combusted in the high-temperature reduction zone 21, so that NOx generated from the nitrogen contained in the solid fuel and the gas fuel is produced in the furnace. Denitrification is performed, and NOx emissions can be suppressed. Furthermore, the combustion efficiency can be improved because the water gasification reaction in which the water produced from the hydrogen contained in the solid fuel and/or the gas fuel is converted into active gas occurs. Here, if the gas fuel is ammonia gas, a large amount of water undergoing the water-gasification reaction is generated, so the combustion efficiency can be further improved.

The foregoing description of the disclosure has been presented for purposes of illustration and description, and is not intended to limit the disclosure in the form disclosed herein. For example, in the foregoing Detailed Description various features of the disclosure are grouped together in one embodiment for the purpose of streamlining the disclosure. However, multiple features contained in the present disclosure can be combined in alternative embodiments, configurations, or aspects other than those discussed above.

2: Combustion furnaces 5, 5A, 5B: Burners 21: High-temperature reduction zone 22: Low-temperature oxidation zone 51: Mixture (mixture of main fuel and primary combustion air)
52: Secondary air (secondary combustion air)
53: Tertiary air (tertiary combustion air)
55: circulation vortex 55a: outer circulation vortex 55b: inner circulation vortex 70: burner axis 71: first nozzle 71a: main fuel outlet 72: second nozzle 72a: secondary air outlet 72b: second flame stabilizer 72f: second Flow path 73 : Third nozzle 73a : Tertiary air outlet 73f : Third flow path 77 : First flame stabilization plate 90 : Gas fuel 91 : Auxiliary fuel injection nozzle 91a : Auxiliary fuel outlet 91f : First flow path

Claims (9)

a first nozzle having a cylindrical shape centered on the burner axis and having a main fuel outlet for ejecting a mixture of main fuel and primary combustion air, and a flame stabilizing plate disposed around the main fuel outlet;
a second nozzle disposed coaxially with the first nozzle and having a secondary air outlet for blowing out secondary combustion air at an outer periphery of the main fuel outlet;
a plurality of auxiliary fuel injection nozzles extending parallel to the burner axis along the outer surface of the first nozzle;
The plurality of auxiliary fuel injection nozzles include a plurality of auxiliary fuel outlets arranged along the outer peripheral edge of the flame stabilization plate, or a plurality of auxiliary fuel outlets arranged inside the outer peripheral edge of the flame stabilization plate and outside the inner peripheral edge of the flame stabilization plate. an outlet, wherein the plurality of auxiliary fuel outlets directs a flow of auxiliary fuel toward a boundary between a flow of the air-fuel mixture exiting the main fuel outlet and a flow of the secondary combustion air exiting the secondary air outlet; spewing gas fuel,
burner. the plurality of auxiliary fuel injection nozzles are joined to the outer surface of the first nozzle;
Burner according to claim 1. downstream ends of the plurality of auxiliary fuel injection nozzles are passed through the flame stabilization plate;
Burner according to claim 1 or 2. The flame stabilizing plate has a plurality of notches on the outer peripheral edge, and the downstream ends of the plurality of auxiliary fuel injection nozzles pass through the notches.
Burner according to claim 1 or 2. The plurality of auxiliary fuel outlets eject the gas fuel in a forward flow toward the downstream side of a circulating vortex generated at the boundary between the flow of the air-fuel mixture and the flow of the secondary combustion air.
Burner according to any one of claims 1-4. The circulating vortex includes an outer circulating vortex and an inner circulating vortex closer to the burner axis than the outer circulating vortex,
The plurality of auxiliary fuel outlets includes an inner auxiliary fuel outlet and an outer auxiliary fuel outlet positioned at substantially the same rotational position about the burner axis, wherein the inner auxiliary fuel outlet is located at the inner circulation vortex. and the outer auxiliary fuel outlet ejects the gas fuel in a forward flow toward the downstream side of the outer circulation vortex.
Burner according to claim 5. wherein said plurality of auxiliary fuel outlets are switchable to blow combustion air instead of said gaseous fuel;
Burner according to any one of claims 1-6. wherein the gas fuel is ammonia gas;
Burner according to any one of claims 1-7. a hot reduction zone with a reducing atmosphere, provided with at least one burner according to any one of claims 1 to 8;
a low-temperature oxidation zone having a lower temperature and an oxidizing atmosphere than the high-temperature reduction zone, into which the combustion gas generated in the high-temperature reduction zone flows;
combustion furnace.

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