JP2019143958A - Combustion apparatus - Google Patents

Abstract

To provide a combustion apparatus capable of generating radiant heat effectively by performing sufficient secondary combustion.SOLUTION: A combustion apparatus 1 comprises: a combustion furnace 3 in which a primary flame region is formed by primary flame F1 formed by a burner 5; an opposed secondary air nozzle 7 to jet secondary air toward the primary flame region from an opposed position in a longitudinal axis L1 direction of the primary flame region; and upper circumferential secondary air nozzles 16 and lower circumferential secondary air nozzles 10 to jet secondary air to a circumferential region of the primary flame region. The circumferential secondary air nozzles 10, 16 jet secondary air in a circumferential direction of the circumferential region of the primary flame region.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a combustion apparatus.

  Counterflow combustion in which secondary combustion is performed by injecting secondary air as a counterflow from a nozzle provided at an opposing position in the longitudinal axis direction of the primary flame is known (Patent Documents 1 to 3).

JP-A-7-293856 Japanese Patent No. 4220083 Japanese Patent No. 5650812

  In Patent Documents 1 to 3, secondary air can be injected from the nozzle to perform good secondary combustion. However, it is desirable to further improve the combustion efficiency and sufficiently recover the radiant heat from the flame.

  This invention is made | formed in view of such a situation, Comprising: It aims at providing the combustion apparatus which can obtain radiant heat effectively by performing sufficient secondary combustion.

  A combustion apparatus according to an aspect of the present invention includes a combustion furnace in which a primary flame region is formed, and an opposed secondary that injects secondary air from the opposed position in the longitudinal axis direction of the primary flame region toward the primary flame region. A secondary air nozzle, and an outer peripheral secondary air nozzle that injects secondary air into the outer peripheral region of the primary flame region.

Near the tip of the primary flame region in the longitudinal axis direction by injecting secondary air from the opposed position in the longitudinal axis direction of the primary flame region formed inside the combustion furnace to the primary flame region side by the opposed secondary air nozzle To form a secondary combustion region. As a result, gas phase combustion occurs at a high temperature, and unburned components in the primary flame region are processed to generate radiant heat. Furthermore, a secondary combustion area | region is formed in the outer peripheral area | region of a primary flame area | region by injecting secondary air with respect to the outer peripheral area | region of a primary flame area | region by an outer periphery secondary air nozzle. As a result, gas phase combustion occurs at a high temperature, and unburned components in the primary flame region are processed to generate radiant heat.
As described above, since the secondary combustion region is formed not only in the vicinity of the front end portion of the primary flame region but also in the outer peripheral region, the secondary combustion region can be formed so as to cover substantially the entire primary flame region. By performing sufficient secondary combustion, radiant heat can be generated effectively.

  Furthermore, the combustion apparatus according to an aspect of the present invention includes a heat exchanger provided in the combustion furnace.

  By providing a heat exchanger in the combustion furnace, heat radiation generated by the flame formed in the combustion furnace can be effectively recovered. The heat recovered by the heat exchanger is used to generate steam, for example, and can be used for various heat sources, steam turbine power generation, and the like.

  Furthermore, in the combustion apparatus according to one aspect of the present invention, the outer peripheral secondary air nozzle injects secondary air toward the circumferential direction of the outer peripheral region of the primary flame region.

  By injecting secondary air toward the circumferential direction of the outer peripheral region of the primary flame region, a thin air layer can be formed in a substantially cylindrical shape in the outer peripheral region of the primary flame region. As a result, the secondary air reaches the primary flame region directly to prevent the flame temperature in the primary flame region from decreasing, and a desired secondary combustion region is formed in the outer peripheral region of the primary flame region. Can do.

  Furthermore, in the combustion apparatus according to an aspect of the present invention, the outer peripheral secondary air nozzle has a circumferential portion located in the outer peripheral region of the primary flame region.

Since the outer peripheral secondary air nozzle has a circumferential portion located in the outer peripheral region of the primary flame region, the secondary air can be suitably supplied to the outer peripheral region so as to surround the primary flame region.
The circumferential portion may have an annular shape or an arc shape.

  Furthermore, in the combustion apparatus according to one aspect of the present invention, the outer peripheral secondary air nozzle has a spiral shape extending in the longitudinal axis direction.

  By making the outer peripheral secondary air nozzle into a spiral shape extending in the longitudinal axis direction, secondary air can be evenly supplied to the outer peripheral region of the primary flame region. Further, by adopting a spiral shape, the secondary air injected from the outer peripheral secondary air nozzle can be swirled and flowed, and the straightness of the secondary air in the longitudinal axis direction can be improved. For example, when the spiral shape is positioned so that the axial direction is in the horizontal direction, it is possible to suppress the secondary air from being directed upward due to buoyancy by improving straightness.

  Furthermore, in the combustion apparatus according to one aspect of the present invention, the opposed secondary air nozzle has an annular portion having an annular shape in a plane orthogonal to the longitudinal axis.

The opposed secondary air nozzle has an annular part that forms an annular shape in a plane perpendicular to the longitudinal axis, so that the area that blocks flame radiation compared to the case where a nozzle head is provided on the longitudinal axis. Can be reduced. Thereby, more radiant heat can be collect | recovered.
The annular portion may be a single annular ring, or may be a multiple annular portion such as a double or triple having a common center.

  By providing an outer peripheral secondary air nozzle that injects secondary air in the outer peripheral region of the primary flame region, radiant heat can be effectively obtained by performing sufficient secondary combustion.

It is the longitudinal cross-sectional view which showed the combustion apparatus which concerns on one Embodiment of this invention. It is a cross-sectional view of the combustion apparatus of FIG. It is the side view which showed the outer periphery secondary air nozzle made into the helical form. It is the front view which showed the 1st modification of the opposing secondary air nozzle. It is the front view which showed the 2nd modification of the opposing secondary air nozzle. It is the longitudinal cross-sectional view which showed the combustion apparatus which concerns on a 1st modification. It is the longitudinal cross-sectional view which showed the combustion apparatus which concerns on a 2nd modification.

Embodiments according to the present invention will be described below with reference to the drawings.
FIG. 1 shows a combustion apparatus 1 according to this embodiment. The combustion apparatus 1 includes a combustion furnace 3 in a housing 1a installed on the floor BS. The combustion furnace 3 is a horizontal type extending in the horizontal direction. As shown in FIG. 2, the combustion furnace 3 has a substantially cylindrical shape having an opening at the top. A discharge port 3a is formed at the lower end of the combustion furnace 3 so that molten ash can be discharged.

  A burner 5 is provided on a side wall constituting the casing 1a of the combustion apparatus 1. The burner 5 is supplied with fuel such as pulverized coal and biomass and primary air. The burner 5 forms a primary flame F <b> 1 inside the combustion furnace 3. The primary flame F1 is formed to have a longitudinal axis L1 in the horizontal direction.

  As shown in FIG. 1, an opposed secondary air nozzle 7 that injects secondary air is provided at the opposed position of the primary flame F <b> 1 in the direction of the longitudinal axis L <b> 1, that is, on the opposite side of the burner 5 across the combustion furnace 3. Yes. The opposed secondary air nozzle 7 includes a single nozzle head 7a having a hemispherical shape. The nozzle head 7a is formed with a plurality of injection ports, and the diameter of each injection port is, for example, 3 mm. The secondary air injected from the nozzle head 7a of the opposed secondary air nozzle 7 is not injected so as to face the primary flame region where the primary flame F1 is formed, but is indicated by an arrow A1 in the figure. Thus, it sprays radially so that a thin air layer may be formed near the tip in the longitudinal axis L1 of the primary flame region. That is, the secondary air is injected from the opposed secondary air nozzle 7 so that the secondary air does not reach the primary flame region. For example, the reach distance of the secondary air injected from the injection port is 20 cm or more and 30 cm or less. Air is supplied to the opposing secondary air nozzle 7 from the blower 9.

  A lower outer peripheral secondary air nozzle (outer peripheral secondary air nozzle) 10 is provided along the inner periphery of the combustion furnace 3. As shown in FIG. 2, the lower outer peripheral secondary air nozzle 10 is a circular arc nozzle (circumferential portion) that is curved along the inner periphery of the combustion furnace 3 in the cross section of the combustion furnace 3. 10a. As shown in FIG. 1, a plurality of arc nozzles 10a are provided at predetermined intervals in the direction of the longitudinal axis L1. Each arc nozzle 10 a is connected to a common air supply pipe 12. A blower 14 is connected to the upstream side of the air supply pipe 12.

  The arc nozzle 10a is formed with a plurality of injection ports, and the diameter of each injection port is, for example, 3 mm. The secondary air injected from the arc nozzle 10a is injected in the direction of the longitudinal axis L1 (see arrow A2 in FIG. 1) and is injected in the circumferential direction (see arrow A3 in FIG. 2). The secondary air thus injected forms an air layer with a small thickness so as to surround the outer peripheral region of the primary flame region formed by the primary flame F1. Moreover, the secondary air injected from the lower outer peripheral secondary air nozzle 10 is injected so as not to reach the primary flame region. For example, the reach distance of the secondary air injected from the injection port is 20 cm or more and 30 cm or less.

  An upper outer peripheral secondary air nozzle (outer peripheral secondary air nozzle) 16 is provided above the combustion furnace 3 so as to face the upper opening of the combustion furnace 3. As shown in FIG. 2, the upper outer peripheral secondary air nozzle 16 is a circular arc nozzle (circumferential portion) that is curved so as to be convex upward and concave downward in the cross section of the combustion furnace 3. 16a. As shown in FIG. 1, a plurality of arc nozzles 16a are provided at predetermined intervals in the direction of the longitudinal axis L1. Each arc nozzle 16 a is connected to a common air supply pipe 18. A blower 9 is connected to the upstream side of the air supply pipe 18.

  The arc nozzle 16a is formed with a plurality of injection ports, and the diameter of each injection port is, for example, 3 mm. The secondary air injected from each arc nozzle 16a is injected obliquely downward. Specifically, the fuel is injected on both sides in the direction of the longitudinal axis L1 (see arrow A4 in FIG. 1) and below the arc nozzle 16a (see arrow A5 in FIG. 2). The secondary air thus injected forms an air layer with a small thickness so as to surround the outer peripheral region of the primary flame region formed by the primary flame F1. Moreover, the secondary air injected from the upper outer peripheral secondary air nozzle 16 is injected so as not to reach the primary flame region. For example, the reach distance of the secondary air injected from the injection port is 20 cm or more and 30 cm or less.

  As shown in FIG. 2, a water pipe 20 through which water flows is provided above the combustion furnace 3. The water pipe 20 is also provided on a wall portion (side wall or the like) constituting the casing 1a of the combustion apparatus 1, and is used as a heat exchanger that absorbs the radiant heat of the flame generated in the combustion furnace 3.

The combustion apparatus 1 mentioned above is used as follows.
By supplying fuel and primary air to the burner 5, a primary flame F <b> 1 is formed in the combustion furnace 3. Secondary air is jetted from the opposed secondary air nozzle 7 to the tip region in the direction of the longitudinal axis L1 of the primary flame region formed by the primary flame F1. The secondary air forms an air layer with a small thickness so as to cover the tip region of the primary flame region. In this thin air layer, gas phase combustion occurs at a high temperature, the unburned portion in the primary flame region is processed, and secondary combustion is performed.

  Secondary air is injected from the lower outer peripheral secondary air nozzle 10 and the upper outer peripheral secondary air nozzle 16 into the outer peripheral region of the primary flame region. The secondary air forms an air layer with a small thickness so as to cover the outer peripheral region of the primary flame region. In this thin air layer, gas phase combustion occurs at a high temperature, the unburned portion in the primary flame region is processed, and secondary combustion is performed.

  As described above, the radiant heat generated by the primary combustion and the secondary combustion is collected in the heat exchanger constituted by the water pipe 20, and steam is generated in the water pipe 20. The generated steam is used for various heat sources and steam turbine power generation.

According to this embodiment, there exist the following effects.
Since the secondary combustion region is formed not only in the vicinity of the front end portion of the primary flame region but also in the outer peripheral region by the outer peripheral secondary air nozzles 10 and 16, the secondary combustion region covers almost the entire primary flame region. Can be formed. Thereby, radiant heat can be effectively generated by performing sufficient secondary combustion.

  A thin air layer having a substantially cylindrical shape is formed in the outer peripheral region of the primary flame region by injecting secondary air in the circumferential direction of the outer peripheral region of the primary flame region using the outer peripheral secondary air nozzles 10 and 16. Can be formed. As a result, the secondary air reaches the primary flame region directly to prevent the flame temperature in the primary flame region from decreasing, and a desired secondary combustion region is formed in the outer peripheral region of the primary flame region. Can do.

  Since the outer peripheral secondary air nozzles 10 and 16 have the arc nozzles 10a and 16a located in the outer peripheral region of the primary flame region, the secondary air is suitably supplied to the outer peripheral region so as to surround the primary flame region. be able to.

  Instead of the peripheral secondary air nozzles 10 and 16, or together with the peripheral secondary air nozzles 10 and 16, as shown in FIG. 3, a spiral peripheral secondary air nozzle 22 may be used. Specifically, the outer peripheral secondary air nozzle 22 is disposed spirally along the inner periphery of the combustion furnace 3. Thereby, secondary air can be uniformly supplied with respect to the outer peripheral area | region of a primary flame area | region. In addition, by adopting a spiral shape, the secondary air injected from the outer peripheral secondary air nozzle can be swung around the longitudinal axis L1, and the straight air can be improved in the direction of the longitudinal axis L1. it can. By improving the straightness, the secondary air can be prevented from being directed upward by buoyancy, and secondary combustion can be performed satisfactorily.

  Further, as shown in FIG. 4, an annular nozzle 24 having an annular part 24 a may be used in place of the opposed secondary air nozzle 7. An air supply pipe 24b for supplying air is connected to the annular portion 24a. The annular portion 24a of the annular nozzle 24 is disposed so as to form an annular shape in a plane orthogonal to the longitudinal axis L1. The annular nozzle 24 can reduce the area that blocks the flame radiation as compared with the case where the nozzle head 7a is provided at the center as shown in FIG. Thereby, more radiant heat can be collect | recovered.

In addition, as shown in FIG. 5, it is good also as the annular nozzle 26 which provided two annular parts 26a1 and 26a2 and was made double. Both the annular portions 26a1, 26a2 have a common center, and include an annular portion 26a1 having a small radius and a large annular portion 26a2 having a large radius. An air supply pipe 26b is connected to the large ring part 26a2, and a plurality of connection pipes 26c extending in the radial direction are connected between the large ring part 26a2 and the small ring part 26a1. Yes. As a result, air is supplied to both annular portions 26a1, 26a2.
Thus, since it was set as the annular nozzle 26 which has the double annular part 26a1, 26a2, secondary air can be supplied over a larger area. Further, three or more annular portions 26a may be provided to form a triple or more annular nozzle.

  Further, in the present embodiment, the combustion apparatus 1 in which the combustion furnace 3 is a horizontal type as shown in FIG. 1 has been described. However, as shown in FIG. 6, the combustion apparatus 1 in which the combustion furnace is a vertical type. 'May be. In the combustion apparatus 1 ′ shown in FIG. 6, an opposed secondary air nozzle 7 ′ having a hemispherical nozzle head 7 a ′ and a spiral outer peripheral secondary air nozzle 22 ′ are provided. The outer peripheral secondary air nozzle 22 'has a spiral shape formed around the vertical axis. The nozzles 7 ′ and 22 ′ are connected to a common blower 30.

  Further, as shown in FIG. 7, a nozzle 32 that serves as both a counter secondary air nozzle and an outer peripheral secondary air nozzle may be used. The combustion apparatus 1 ″ shown in the figure is a vertical combustion furnace. The nozzle 32 is connected to the upper nozzle 32a located above and to both sides of the upper nozzle 32a, along the inner wall of the combustion furnace. The upper nozzle 32a and the side nozzle 32b have a common air flow path, and the upper nozzle 32a functions as an opposed secondary air nozzle. The side nozzle 32b has a function as an outer peripheral secondary air nozzle, and a blower 34 is connected to the upstream side of the nozzle 32.

  In the above-described embodiment, pulverized coal and biomass have been described as examples of fuel. However, the present invention is not limited to this, and also for combustion of food waste, chicken manure, and other flame-retardant substances. Can be used.

1, 1 ', 1 "Combustion device 1a Housing 3 Combustion furnace 3a Discharge port 5 Burner 7, 7' Opposed secondary air nozzle 7a, 7a 'Nozzle head 9 Blower 10 Lower outer peripheral secondary air nozzle (outer peripheral secondary air nozzle )
10a Circular nozzle (circumferential part)
12 Air supply pipe 14 Blower 16 Upper outer peripheral secondary air nozzle (outer peripheral secondary air nozzle)
16a Circular nozzle (circumferential part)
18 Air supply pipe 20 Water pipe (heat exchanger)
22 peripheral secondary air nozzles 24, 26 annular nozzles 24a, 26a annular part 24b air supply pipe 26a1 small annular part 26a2 large annular part 26b air supply pipe 26c connection pipe 30 blower 32 nozzle 34 blower BS floor F1 primary flame L1 Long axis

Claims (6)

A combustion furnace in which a primary flame region is formed;
An opposed secondary air nozzle that injects secondary air from the opposed position in the longitudinal axis direction of the primary flame region to the primary flame region;
An outer peripheral secondary air nozzle for injecting secondary air into an outer peripheral region of the primary flame region;
Combustion device equipped with.   The combustion apparatus of Claim 1 provided with the heat exchanger provided in the said combustion furnace.   The combustion apparatus according to claim 1 or 2, wherein the outer peripheral secondary air nozzle injects secondary air toward a circumferential direction of the outer peripheral area of the primary flame area.   The combustion apparatus according to any one of claims 1 to 3, wherein the outer peripheral secondary air nozzle has a circumferential portion located in the outer peripheral area of the primary flame area.   The combustion apparatus according to any one of claims 1 to 3, wherein the outer peripheral secondary air nozzle has a spiral shape extending in the longitudinal axis direction.   The combustion apparatus according to any one of claims 1 to 5, wherein the opposed secondary air nozzle has an annular portion having an annular shape in a plane orthogonal to the longitudinal axis.

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