阅读说明：本技术 固体燃料燃烧器及固体燃料燃烧器用火焰稳定器 (Solid fuel burner and flame stabilizer for solid fuel burner ) 是由 多田隈聪 马场彰 仓增公治 有贺健 水户昌平 北风恒辅 岭聪彦 于 2018-12-18 设计创作，主要内容包括：通过固体燃料燃烧器(1),可确保火焰的稳定性、充分的循环流并且提高维护性,上述固体燃料燃烧器(1)具备：引导部件(34),配置于第一气体喷嘴(10)的前端外周部,并将在第二流路(11a)流动的流体向径向的外侧引导；及缩流形成部件(50),相对于第二流路(11a)的流动方向配置于引导部件(34)的上游侧,使第二流路(11a)的截面积变窄,引导部件(34)的外径(L2)形成得比第二气体喷嘴(11)的外周壁的内径(L1)小,第一气体喷嘴(10)、引导部件(34)及缩流形成部件(50)构成为能够沿着第一气体喷嘴(10)的轴向朝向炉外地一体地拆装。(A solid fuel burner (1) capable of ensuring flame stability, a sufficient circulating flow and improving maintainability, wherein the solid fuel burner (1) comprises a guide member (34) which is arranged on the outer peripheral part of the front end of a first gas nozzle (10) and guides the fluid flowing in a second flow path (11a) to the outside in the radial direction, and a contraction flow forming member (50) which is arranged on the upstream side of the guide member (34) relative to the flowing direction of the second flow path (11a) and narrows the cross-sectional area of the second flow path (11a), the outer diameter (L2) of the guide member (34) is formed to be smaller than the inner diameter (L1) of the outer peripheral wall of the second gas nozzle (11), and the first gas nozzle (10), the guide member (34) and the contraction flow forming member (50) are configured to be integrally detachable toward the outside of the furnace along the axial direction of the first gas nozzle (10).)

1. A solid fuel burner, comprising:

a first gas nozzle having a cylindrical flow path through which a mixed fluid of a solid fuel and a carrier gas for the solid fuel flows;

a second gas nozzle that forms a second flow path through which combustion gas of the solid fuel flows and that is formed on an outer peripheral side of the first gas nozzle;

a guide member disposed at a distal end outer peripheral portion of the first gas nozzle and guiding the fluid flowing through the second flow path radially outward; and

a flow constriction forming member disposed upstream of the guide member with respect to the flow direction of the second flow path to narrow the cross-sectional area of the second flow path,

the guide member has an outer diameter formed smaller than an inner diameter of an outer peripheral wall of the second gas nozzle,

the first gas nozzle, the guide member, and the contracted flow forming member are integrally attached to and detached from the furnace along an axial direction of the first gas nozzle.

2. The solid fuel burner of claim 1,

when the inner diameter of the outer peripheral wall of the second gas nozzle is L1, the outer diameter of the guide member is L2, and the inner diameter of the constriction forming member is L4, the relationship L1 > L2 > L4 is obtained.

3. The solid fuel burner of claim 1 or 2,

the solid fuel burner includes a fin member disposed between the contraction flow forming member and the guide member, and rectifies the secondary air flowing through the second flow path.

4. The solid fuel burner of claim 3,

the solid fuel burner is provided with the constricted flow forming members supported on the fin members.

5. A flame holder for a solid fuel burner, which is a flame holder provided at an opening end portion of a fuel nozzle of a solid fuel burner, is characterized in that,

the flame stabilizer includes, in a circumferential direction:

an annular contraction flow forming member that narrows a flow passage of the combustion gas flowing on an outer peripheral side of the flame stabilizer from an outer side to an inner side; and

a plurality of fin members extending in a direction along a flow of the combustion gas,

the flame stabilizer for a solid fuel burner is provided with a guide member that deflects the flow of combustion gas passing through the annular converging flow forming member outward,

the guide member has an outer diameter larger than an inner diameter of the annular flow-contracting forming member.

Technical Field

The present invention relates to a solid fuel burner and a flame stabilizer for a solid fuel burner, and more particularly to a structure of a solid fuel burner and a flame stabilizer for a solid fuel burner which are excellent in maintainability.

Background

As a solid fuel burner for burning solid fuel particles such as pulverized coal obtained by pulverizing coal and installed on a wall surface of a furnace such as a boiler, there is known a burner using a structure in which a solid-gas two-phase flow of the solid fuel particles and a gas for transporting the solid fuel particles is jetted from a cylindrical fuel nozzle opening toward the furnace, and the gas for combustion is jetted toward the furnace from a gas nozzle for combustion formed in a coaxial cylindrical shape on an outer peripheral side of the fuel nozzle.

In such a burner, a flame stabilizer is often provided at a tip end portion of the fuel nozzle on the burner opening side as a member for promoting ignition and stabilizing flame. Further, the flame stabilizer is often structured to expand in a stepped or angled manner in the radial direction with respect to the fuel flow direction (the techniques described in patent documents 1 to 5 described below are well known).

The term of the transport gas is Primary Air (Primary Air) and the term of the combustion gas is Secondary Air (Secondary Air), and may be referred to as follows.

In addition, the term "Flame Stabilizer" refers to a Ring-shaped Flame Stabilizer as a Flame Stabilization Ring (Ring Stabilizer), or a Ring member that is a part of a Flame Stabilizer may be referred to as a Ring or a Ring member.

Inside the fuel nozzle, as a means for concentrating solid fuel particles toward the inner wall side of the fuel nozzle to ensure ignition quality and flame stability of the fuel even at low load, there are often provided components such as a fuel concentrator or a swirler for narrowing the flow path in the nozzle toward the radial outer side, as a constricted portion (venturi) for preventing flashback by increasing the flow velocity of the solid-gas two-phase flow.

Further, the flame stabilizer at the tip end of the nozzle is often formed with a guide member (guide plate) that expands the flow of the combustion gas (secondary air) ejected from the outer peripheral side outward from the nozzle center axis side. The guide plates sometimes use the name baffle.

The purpose of this is to promote ignition of fuel particles, improve flame stability, reduce the amount of NOx produced and reduce the amount of unburned fuel by separating the flow of the solid-gas two-phase flow and the flow of the combustion gas to form a large circulating flow on the furnace side of the flame stabilizer.

A typical example is a configuration in which a flow path of a combustion gas nozzle (secondary air nozzle) is formed so that the flow of combustion gas (secondary air) is reduced toward the outer peripheral side at the start end of a flame stabilizer as described in patent document 1 (ninth embodiment, fig. 10, wall thickness portion (303)) and patent document 2 (fig. 1; flame stabilizer base material (23a) and flame stabilizer sleeve (23 b)).

According to such a flow path structure, the flow velocity of the combustion gas flowing in the vicinity of the flame stabilizer and the guide member thereof is increased, so that the cooling of the flame stabilizer and the guide member thereof is promoted to suppress burning loss thereof, and the aforementioned circulating flow is amplified to stabilize ignition.

Disclosure of Invention

Problems to be solved by the invention

However, the components such as the content and the flame stabilizer provided in the fuel nozzle cannot avoid wear associated with use, and periodic inspection is required for maintenance such as repair and replacement.

In particular, the flame holder, its guide member, is exposed to radiation from the furnace, is exposed to a significantly high temperature, and therefore the necessity of maintenance is high.

On the other hand, in order to sufficiently exhibit the above-described functions and purposes, it is important for the flame stabilizer and the guide member thereof to reliably deflect the flow direction of the combustion gas (secondary air) having a velocity component increased in the nozzle axial direction by passing through the narrowed flow path radially outward so as to be separated from the flow of the solid-gas two-phase flow (primary air), thereby generating a large circulating flow on the furnace side of the flame stabilizer.

Therefore, in order to make the projection surface of the guide member viewed from the furnace opening side sufficiently large, the flow path thereof needs to be configured so that the flow of the combustion gas (secondary air) does not pass through the guide member from the nozzle upstream side to the furnace side.

Thus, the outermost diameter of the flame stabilizer and its guide member is larger than the inner diameter of the combustion gas nozzle (secondary air nozzle).

The flame holder and the guide member thereof are often formed of an integral casting and attached to the opening end of the fuel nozzle via an attachment member.

In this case, as in the structures described in patent documents 1 and 2, when the outer diameters of the flame stabilizer and the guide member are larger than the inner diameter of the outer peripheral wall of the secondary air nozzle, the portion including the fuel nozzle such as the flame stabilizer cannot be directly pulled out toward the outside of the furnace in the axial direction. Therefore, it is necessary to provide a footing or the like inside the boiler furnace and remove the flame stabilizer and its guide member, thereby improving maintainability.

The technical problem of the present invention is to realize a flame stabilizer for a solid fuel burner such as 1) to 3) below and a solid fuel burner provided with the flame stabilizer.

1) The performance requirements are as follows: by forming a large circulating flow on the burner side of the flame stabilizer, ignition promotion of fuel particles, improvement of flame stability, reduction of NOx generation amount and reduction of unburned amount due to enlargement of the reduction flame region, and the like are achieved.

2) Reliability: the cooling of the flame stabilizer and its guide member is promoted to suppress burning thereof.

3) Maintenance performance: the flame stabilizer and the guide member thereof are not removed from the fuel nozzle, but are pulled out outside the furnace integrally with the fuel nozzle.

Means for solving the problems

The above object of the present invention can be achieved by adopting the following configuration.

The invention described in claim 1 is a solid fuel burner, comprising: a first gas nozzle having a cylindrical flow path through which a mixed fluid of a solid fuel and a carrier gas for the solid fuel flows; a second gas nozzle that forms a second flow path through which the combustion gas of the solid fuel flows and that is formed on an outer peripheral side of the first gas nozzle; a guide member disposed at a distal end outer peripheral portion of the first gas nozzle and guiding the fluid flowing through the second flow path radially outward; and a contracted flow forming member disposed upstream of the guide member with respect to a flow direction of the second flow path, the second flow path having a reduced cross-sectional area, the guide member having an outer diameter smaller than an inner diameter of an outer peripheral wall of the second gas nozzle, the first gas nozzle, the guide member, and the contracted flow forming member being integrally detachable from the first gas nozzle in an axial direction of the first gas nozzle toward the outside of the furnace.

The invention described in claim 2 is the solid fuel burner described in claim 1, wherein when the inner diameter of the outer peripheral wall of the second gas nozzle is L1, the outer diameter of the guide member is L2, and the inner diameter of the contraction flow forming member is L4, a relationship of L1 > L2 > L4 is established.

The invention described in claim 3 is the solid fuel burner described in claim 1 or 2, further comprising a fin member that is disposed between the contraction flow forming member and the guide member and rectifies secondary air flowing through the second flow path.

The invention described in claim 4 is the solid fuel burner described in claim 3, further comprising the contraction flow forming member supported by the fin member.

The invention described in claim 5 is a flame holder for a solid fuel burner, which is provided at an opening end of a fuel nozzle of the solid fuel burner, and which is characterized by comprising, in a circumferential direction of the flame holder: an annular contraction flow forming member that narrows a flow passage of the combustion gas flowing on an outer peripheral side of the flame stabilizer from an outer side to an inner side; and a plurality of fin members extending in a direction along the flow of the combustion gas, wherein the flame stabilizer for a solid fuel burner is provided with a guide member that deflects the flow of the combustion gas passing through the annular contracted flow forming member outward, and an outer diameter of the guide member is larger than an inner diameter of the annular contracted flow forming member.

Effects of the invention

According to the invention described in claim 1, the outer diameter of the guide member is formed smaller than the inner diameter of the outer peripheral wall of the second gas nozzle, and the first gas nozzle can be pulled out of the furnace without hooking the guide member to the second gas nozzle. Therefore, it is not necessary to provide a foothold in the furnace, and maintenance can be improved. Further, since the fluid having passed through the contracted flow forming member in the second flow passage reaches the guide member and is guided to the outside in the radial direction in a state where the flow velocity thereof is high, the deviation in the radial direction becomes stronger as compared with the case where the contracted flow forming member is not provided, and the circulation flow can be reduced to be small even if the outer diameter of the guide member is smaller than the inner diameter of the outer peripheral wall of the second gas nozzle. Therefore, flame stability can be ensured, a sufficient circulating flow can be ensured, and low NOx performance can be ensured. Further, since the fluid reaches the guide member at a high speed, cooling of the guide member and the flame stabilizer is promoted, and burning loss is suppressed. Therefore, reliability can be improved. Therefore, according to the invention described in claim 1, the performance requirement, reliability, and maintainability can be achieved at the same time.

According to the invention described in claim 2, the relationship of L1 > L2 > L4 is satisfied, the first gas nozzle can be pulled out, and a sufficient circulating flow can be ensured.

According to the invention described in claim 3, in addition to the effect of the invention described in claim 1 or 2, the turbulent fluid at the time of the contraction flow is rectified by the fin members, so that the deflection in the radial direction can be enhanced, and the stability of the flame and the circulation flow can be ensured.

According to the invention described in claim 4, in addition to the effect of the invention described in claim 3, by supporting the contraction flow forming member on the fin member, it is not necessary to provide a separate supporting member for supporting the contraction flow forming member, and the number of components can be reduced.

According to the invention described in claim 5, the contracted flow forming member provided in the flame holder is provided with the plurality of fin members extending in the direction along the flow of the combustion gas in the circumferential direction of the flame holder, and the guide member for deflecting the flow of the combustion gas passing through the annular contracted flow forming member outward is provided, and the outer diameter of the guide member is larger than the inner diameter of the annular contracted flow forming member, so that the nozzle supporting the flame holder can be pulled out of the furnace together. Therefore, it is not necessary to provide a footing in the furnace, and maintenance can be improved. Further, since the fluid having passed through the contracted flow forming member reaches the guide member and is guided to the outside in the radial direction in a state where the flow velocity of the fluid becomes high, the deviation in the radial direction becomes stronger than that in a case where the contracted flow forming member is not provided. Therefore, flame stability can be ensured, a sufficient circulating flow can be ensured, and low NOx performance can be ensured. Further, since the fluid reaches the guide member at a high speed, cooling of the guide member and the flame stabilizer is promoted, and burning loss is suppressed. Therefore, reliability can be improved. Therefore, according to the invention described in claim 5, the performance requirement, reliability, and maintainability can be achieved at the same time.

Drawings

Fig. 1 is a side view (partial cross section) of a solid fuel burner according to an embodiment of the present invention, fig. 1a is an overall view, fig. 1B is an enlarged view of a front end portion, and fig. 1C is a view illustrating a positional relationship of each portion of the front end portion.

Fig. 2 is a sectional view taken along line II-II of the solid fuel burner of fig. 1 (B).

Fig. 3 is an explanatory view of a contracted flow forming member of the embodiment, fig. 3 (a) is an explanatory view of a contracted flow forming member of the embodiment 1, and fig. 3 (B) is an explanatory view of another form of a contracted flow forming member.

Fig. 4 is an explanatory diagram of a state in which a portion of the first gas nozzle is drawn out in the solid fuel burner of embodiment 1.

Fig. 5 is an explanatory view of a region of a circulating flow of a solid fuel burner, fig. 5 (a) is an explanatory view of a structure of example 1, fig. 5 (B) is an explanatory view of a structure of comparative example 1 (patent documents 3 to 5), fig. 5 (C) is an explanatory view of a structure of comparative example 2, fig. 5 (D) is an explanatory view of a structure of comparative example 3 (patent documents 1 and 2), fig. 5 (E) is an explanatory view of a flow velocity of secondary air in a cross section of a base end portion of a flame stabilizer, and fig. 5 (F) is an explanatory view of a size of a region of a circulating flow.

Fig. 6 is an explanatory view of a modified example of the contraction flow forming member, fig. 6 (a) is an explanatory view of modified example 1, fig. 6 (B) is an explanatory view of modified example 2, fig. 6 (C) is an explanatory view of modified example 3, fig. 6 (D) is an explanatory view of modified example 4, fig. 6 (E) is an explanatory view of modified example 5, and fig. 6 (F) is an explanatory view of modified example 6.

Detailed Description

Embodiments of the present invention are described below.