JPH094816A - Fuel spray type combustion device - Google Patents

Abstract

PURPOSE: To provide a fuel spray type combustion device, supplying primary air stably into sprayed fuel and capable of stabilizing whirling stream for stabilizing combustion flame. CONSTITUTION: This fuel spray type combustion device is provided with a burner duct 4, through which combustion air is sent, a nozzle 5, whose tip end is inserted into the burner duct to inject fuel, an inner cylinder 7, provided so as to surround the nozzle, and a combustion tube 8, provided continuously to the inner tube so as to form a combustion space, while the inner tube is provided with a choked unit 7a, provided continuously to the inner tube to form a combustion space, while the inner tube is provided with a choked unit 7a, provided at the end of connecting side to a combustion tube and whose diameter is reduced toward the fore direction of the spraying direction of fuel, and the combustion tube is provided with a plurality of whirling vanes, formed so as to surround the connecting part and provided on the end surface of the connecting side to the inner tube.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel spray type combustion apparatus used in an oil water heater, an oil hot water boiler, or the like.

[0002]

2. Description of the Related Art Conventionally, an example of the structure of a fuel spray type combustion apparatus of this type (hereinafter referred to as a combustion apparatus) has been proposed in, for example, Japanese Utility Model Publication No. 62-18809.
This combustion device is provided with a burner duct into which combustion air is sent by a blower fan, a nozzle installed inside the burner duct to spray fuel, an inner cylinder surrounding the nozzle, and an inner cylinder provided continuously to the inner cylinder. And a combustion tube forming a combustion space forward of the fuel spray direction,
A flame holding plate is provided inside the inner cylinder so as to be opposed to the front of the nozzle.

In the inner cylinder and the combustion cylinder, the burner duct is divided into two in the radial direction to form two systems of air passages coaxially, and the passage on the axial center side is the primary air to the burner. For supply, the flow path in the outer peripheral portion is used for supplying secondary air. Further, the combustion cylinder is formed in a multi-stage shape so that the diameter gradually increases as it goes forward in the fuel spray direction, and on the outer peripheral surface thereof, secondary air flowing outside is radially directed to the combustion space. A large number of vent holes are formed along the inner surface of the combustion cylinder, and the secondary air is axially formed on the surface orthogonal to the axial direction that is the connecting portion between the large diameter portion and the small diameter portion. A large number of vent holes are formed to feed into.

In the conventional combustion device having such a structure, the combustion air sent into the burner duct is
The primary air flowing into the inner cylinder is divided into primary air flowing into the inner cylinder and secondary air flowing into the outer cylinder, and the primary air flowing through the center of the inner cylinder is sprayed from a nozzle installed in the inner cylinder. After being mixed with the fuel, the primary air flowing into the combustion space through the opening formed at a position facing the nozzle of the flame holding plate and flowing through the inner wall portion of the inner cylinder is A swirl flow is formed in front of the flame holding plate in the combustion space by being passed through a swirl vane provided in a position surrounding the opening of the flame holding plate installed in the front.

The combustion flame formed by igniting the fuel sprayed from the nozzle extends from the opening of the flame holding plate into the combustion space and swirls the primary air formed by the swirl vane. The negative pressure generated by the flow and the negative pressure generated by the secondary air that is axially fed along the inner surface of the combustion cylinder are attracted to hold a stable combustion flame for a short time, and at the same time, the combustion cylinder Stable combustion can be obtained by mixing the secondary air, which is sent in from the peripheral wall of the cylinder in the radial direction, with the combustion flame.

[0006]

By the way, in such a conventional combustion apparatus, as described above, after the primary air is supplied into the inner cylinder, a part of the primary air is mixed with the atomized fuel. The remaining flow is divided so as to be fed to the swirl vanes of the flame holding plate, but there is no means for clearly separating the two in this split flow, and the flow is split based on the flow path resistance difference between the swirl vane and the opening. Therefore, the supply amount of each becomes unstable and the air-fuel ratio fluctuates,
There is a risk that the swirl flow will become unstable, leading to a reduction in combustion efficiency and instability of the combustion flame.

The present invention has been made in view of the above-mentioned conventional problems, and it is possible to stably supply the primary air to the atomized fuel and to stabilize the swirling flow for stabilizing the combustion flame. It is an object to provide a fuel spray type combustion device.

[0008]

In order to achieve the above-mentioned object, a fuel spray type combustion apparatus according to claim 1 of the present invention has a burner duct into which combustion air is fed, and a tip is inserted into this burner duct. A nozzle for injecting fuel, an inner cylinder surrounding the nozzle, and a combustion cylinder that is provided continuously with the inner cylinder to form a combustion space. The inner cylinder is connected to the combustion cylinder. Side end portion is formed with a throttle portion whose diameter decreases toward the front in the fuel spray direction, and a plurality of swirl vanes are formed in the combustion cylinder at an end surface on the side of connection with the inner cylinder so as to surround the connection portion. It has a configured structure.

Further, in a fuel spray type combustion apparatus according to a second aspect of the present invention, the combustion cylinder in the first aspect is expanded in multiple stages toward the front in the fuel spray direction, and A ventilation hole is formed in each of the peripheral surface and the end surface connecting the adjacent small diameter portion and large diameter portion.

Further, in a fuel spray type combustion apparatus according to a third aspect of the present invention, the combustion cylinder according to the second aspect is divided into a plurality of pieces in the lengthwise direction, and each of the divided portions is heat resistant. The structure is made of different materials.

[0011]

According to the fuel spray type combustion apparatus of the first aspect of the present invention, a part of the combustion air sent into the burner duct is introduced into the inner cylinder, and the downstream end portion thereof. A combustion cylinder continuously guided to the inner cylinder after being guided to the front of the nozzle installed in the inner cylinder by the throttle portion formed in the inner cylinder and mixed with fuel sprayed from the nozzle. It is sent to the combustion space formed inside.

Further, the other part of the combustion air is guided to the outer periphery of the inner cylinder and the combustion cylinder, and when a part of the part reaches the connecting portion between the inner cylinder and the combustion cylinder, It is guided by a recess formed by the outer surface of the throttle portion and the end surface of the combustion cylinder, guided toward the upstream end surface of the combustion cylinder, and then passed through the swirl vanes provided on this end surface. As a result, a swirling flow is formed in the combustion space near the upstream end of the combustion cylinder.

As a result, the throttle portion acts as a separating member for completely separating the primary air supplied to the nozzle tip from the primary air for generating the swirling flow, and also reliably guides it to the nozzle tip. Since it functions as a guide member, a stable air-fuel ratio can be obtained.

Further, since the depression formed between the inner cylinder and the combustion cylinder guides the combustion air flowing through the outer peripheral portion of the inner cylinder toward the swirl vane, the combustion air to the swirl vane is The supply is ensured and a stable swirl flow is generated in the combustion space.

Further, according to the fuel spray type combustion apparatus of the second aspect of the present invention, the vent hole formed in the end surface which is the connecting surface between the large diameter portion and the small diameter portion adjacent to each other in the combustion cylinder, Since it acts to send secondary air along the inner surface of the combustion cylinder, a negative pressure zone is formed in the vicinity of the inner surface of the combustion cylinder, and the combustion flame in the combustion space is attracted to the negative pressure zone to cause combustion flame. Is stabilized, and the secondary air is supplied to the combustion flame attracted to the vicinity of the inner surface of the combustion cylinder from the ventilation holes formed in the peripheral surface of the combustion cylinder. Is reliably supplied, and combustion efficiency can be improved.

Further, according to the fuel spray combustion apparatus of the third aspect of the present invention, when the capacity is changed stepwise, the calorific value due to the combustion flame changes and the formation position of the combustion flame. Changes along the direction of fuel spray,
The combustion cylinder is divided into a plurality along the fuel injection direction, and since each divided portion is formed of a material having different heat resistance, the combustion cylinder of the combustion flame corresponding to this position-changing combustion flame is Optimal heat resistance is obtained.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIGS. 1 and 2, reference numeral 1 denotes a fuel spray type combustion device according to this embodiment (abbreviated as a combustion device).
The blower duct 2, the blower fan 3 attached to the upstream end of the blower duct 2, and the downstream end of the blower duct 2 so as to be substantially orthogonal to the blower duct 2. A burner duct 4 connected in series, a fuel spray nozzle 5 installed from the base end of the burner duct 4 to the blower duct 2, an ignition plug 6 attached to the nozzle 5, and these nozzles 5 And an inner cylinder 7 surrounding the tip portion of the spark plug 6, and the inner cylinder 7
It is composed of a combustion cylinder 8 attached to the front side in the fuel spray direction and a fuel supply means 9 for supplying fuel to the nozzle 5.

The combustion apparatus 1 is used by being attached to the heat exchange section 10a of the oil water heater 10, for example, as shown in FIG.

More specifically, as shown in FIGS. 1 and 4, the inner cylinder 7 has an end surface on the front side in the fuel spray direction,
As it goes toward the front, it is formed in a substantially truncated cone shape so as to have a gradually smaller diameter, forming a narrowed portion 7a, and an opening 7b is formed in the small diameter portion, that is, the top portion.
The nozzle 5 is opposed to b.

Further, the combustion cylinder 8 connected to the inner cylinder 7 is, in this embodiment, two combustion cylinders fitted to each other in the axial direction, as will be described in detail with reference to FIG. Construct 1
1 and 12, one of the combustion cylinder constituting bodies 11 is formed in a bottomed cylinder shape, and its bottom wall 11a
In the above, while being connected to the inner cylinder 7, they are communicated with each other through the opening 7b.

Further, a flange 11b extending outward in the radial direction is formed at the open end of the one combustion cylinder structure 11, and the first combustion cylinder structure 11 is formed at the outer peripheral end of the flange 11b. Support ring 1 protruding along the axial direction of
1c is integrally formed, and the second combustion cylinder structure 12 is fitted and fixed inside the support ring 11c.

Since the inner cylinder 7 is formed with the throttle portion 7a, the outer wall surface of the throttle portion 7a and the bottom wall 11 of the first combustion cylinder constituting body 11 constituting the combustion cylinder 8 are formed.
An annular recess D is formed between a and a.

Further, in the bottom wall 11a of the first combustion cylinder structure 11, the recess D and the first combustion cylinder structure 1 are formed.
A plurality of ventilation holes 11d communicating with the inside of the No. 1 are provided at predetermined intervals around the axis, and the combustion air passing through these ventilation holes 11d is swirled to positions corresponding to these ventilation holes 11d. A swirl vane 13 for providing a flow is provided, and, as shown in FIG. 5, ventilation holes 11e along the axial direction of the first combustion cylinder structure 11 are provided in the flange 11b at predetermined intervals in the circumferential direction. It is formed in large numbers.

The second combustion cylinder forming body 12 constituting the combustion cylinder 8 has a small diameter portion 12a fitted to the support ring 11c of the first combustion cylinder forming body 11 and a continuation of the small diameter portion 12a. And a continuous wall 12c connecting the small-diameter portion 12a and the large-diameter portion 12b to each other with respect to the axis of the second combustion cylinder structure 12. It is orthogonal.

Further, the small diameter portion 11a and the large diameter portion 12
As shown in FIG. 4, a large number of vent holes 12d are formed in the peripheral wall of b.
Is formed along the radial direction, and a plurality of ventilation holes 12e along the axial direction are formed in the continuous wall 12c at predetermined intervals around the axial line, as shown in FIG.

The combustion cylinder 8 constructed by fitting these combustion cylinder constituents 11 and 12 to each other is
As shown in FIGS. 1 and 4, the shape is such that the diameter is expanded in multiple stages toward the front in the fuel spray direction.

Further, on the flange at the inner end of the burner duct 4, there is provided a flame holding device 15 for preventing the combustion flame extending further inward from the combustion cylinder structure 12 from spreading to the front.
The flame holding device 15 can suppress the generation of soot at the time of ignition.

Next, the operation of this embodiment thus constructed will be described. First, when the blower fan 3 is started, the combustion air is sent toward the burner duct 4 through the blower duct 2.

The combustion air directed to the burner duct 4 is separated into the inside and the outside of the inner cylinder 7 installed therein, and the combustion air introduced into the inner cylinder 7 is After being fed into the narrowed portion 7a of the inner cylinder 7, it is guided by the inner wall surface of the narrowed portion 7a toward the axial center of the inner cylinder.

As a result, the combustion air that has flowed into the inner cylinder 7 is poured as primary air toward the fuel sprayed from the nozzle 5 and is mixed with this fuel.
It flows into the combustion cylinder 8 through an opening 7a formed at the top of the throttle portion 7a.

Here, the primary air mixed with the fuel is separated from the other combustion air by the inner cylinder 7 and supplied, and the throttle portion 7a surely feeds the fuel spray path of the nozzle 5. By being guided, the primary air mixed with the fuel is stably supplied, and the fuel and the primary air are reliably mixed, so that a stable air-fuel ratio is obtained and the combustion efficiency is improved.

The combustion air separated to the outside of the inner cylinder 7 is moved along the outer periphery of the inner cylinder 7 toward the combustion cylinder 8, and a part of the combustion air is burned with the inner cylinder 7. The ventilation hole of the combustion cylinder 8 that is exposed to the recess D while flowing into the recess D formed between the cylinder 8 and the outer surface of the narrowed portion 7a of the inner cylinder 7 is guided. 11d
Sent to

The flow of the combustion air thus guided to the ventilation hole 11d of the combustion cylinder 8 is changed by the swirl vanes 13 in the tangential direction of the combustion cylinder 8 while passing through the ventilation hole 11d. As a result, a swirling flow is generated in the first combustion cylinder structure 11 that constitutes the combustion cylinder 8.

Here, since the combustion air sent to the swirl vanes 13 is guided by the independent flow path formed by the depression D, it is affected by the flow of the combustion air in other portions. Instead, the swirl flow is smoothly supplied to the swirl vanes 13, and thereby a stable swirl flow is generated.

Further, the combustion air other than the combustion air that has flowed into the recess D flows into the outer peripheral portion of the combustion cylinder 8 and is formed on the flange 11b and the continuous wall 12c that are provided orthogonally to the flow direction. From the ventilation holes 11e and 12e, which flow into the combustion cylinder 8 along the inner wall surface thereof,
Further, the remaining combustion air flows toward the center of the combustion cylinder 8 from the ventilation hole 12d formed in the peripheral wall of the combustion cylinder 8.

Prior to spraying the fuel from the nozzle 5, by energizing the spark plug 6, the fuel is ignited and a combustion flame is generated in the combustion cylinder 8. The flame is attracted to the inner wall side of the combustion cylinder 8 by the negative pressure generated with the swirling flow described above and the negative pressure generated with the flow of the secondary air flowing along the inner wall surface, thereby causing combustion. A short stable combustion flame is generated in the length direction of the cylinder 8.

Further, since the combustion air flowing from the peripheral wall toward the center of the combustion cylinder 8 is mixed with the combustion flame attracted to the peripheral wall side of the combustion cylinder 8, the secondary combustion flame is generated. Air is efficiently supplied, and combustion efficiency is further enhanced.

Further, when the required capacity of the combustion device 1 is adjusted in stages, the center position and size of the combustion flame differ depending on the capacity stage.

However, in this embodiment, since the combustion cylinder 8 has a shape in which the diameter is gradually increased,
The combustion cylinder 8 is held in an appropriate positional relationship in accordance with the changing size and position of the combustion flame, and also from this point, the combustion flame is stabilized.

The shapes, sizes, etc. of the respective constituent members shown in the above embodiment are merely examples, and can be variously changed based on design requirements and the like.

For example, although the example in which the combustion cylinder 8 is expanded in multiple stages in the above embodiment has been described, a combustion cylinder having a uniform inner diameter may be used. Further, although an example in which the combustion cylinder 8 is divided in the lengthwise direction is shown, it may have an integral structure, and each of the combustion cylinder constituents 11 and 12 of the divided combustion cylinder 8 has a heat resistance. They may be made of different materials. For example, the second combustion cylinder structure 12 is made of a material having a high heat resistance, and the first combustion cylinder structure 11 is made of a material having a heat resistance lower than that of the second combustion cylinder structure 12. Is also possible. With such a configuration, by using the expensive high heat-resistant material, the first combustion cylinder structure 11 made of a material having low heat resistance is opposed to the combustion flame when the required capacity is small. The amount is reduced, and the cost of the combustion device 1 is reduced.

[0042]

As described above, according to the first aspect of the present invention.
According to the fuel spray combustion device of the present invention, the primary air supplied to the fuel sprayed from the nozzle is supplied separately from the other combustion air by the inner cylinder, and the primary air supplied to the fuel is sprayed by the throttle portion formed in the inner cylinder. The fuel can be surely supplied to the fuel spray path of the nozzle, whereby stable combustion can be performed and highly efficient combustion can be obtained.

Further, by forming the throttle portion in the inner cylinder, it is possible to form a recess having an inclined guide surface formed by the outer surface of the throttle portion of the inner cylinder between the inner cylinder and the combustion cylinder. As a result, a blower passage reaching the swirl vanes formed in the combustion cylinder is formed, the combustion air is reliably supplied to the swirl vane, and a stable swirl flow is generated in the combustion cylinder. can do.

Further, according to the fuel spray type combustion apparatus of the second aspect of the present invention, the vent hole formed in the end surface which is the connecting surface between the large diameter portion and the small diameter portion adjacent to each other in the combustion cylinder, Secondary air can be sent along the inner surface of the combustion cylinder, and by this secondary air, a negative pressure zone is formed in the vicinity of the inner surface of the combustion cylinder, and the negative pressure zone attracts the combustion flame in the combustion space. Therefore, the combustion flame can be stabilized, and the secondary air is supplied to the combustion flame attracted to the vicinity of the inner surface of the combustion cylinder by the vent hole formed in the peripheral surface of the combustion cylinder. By doing so, it is possible to reliably supply the secondary air and improve the combustion efficiency.

Furthermore, according to the fuel spray type combustion apparatus of the third aspect of the present invention, even when the capacity is changed stepwise, the combustion cylinder is divided into a plurality of sections along the fuel injection direction. In addition, each divided part is formed of materials with different heat resistance,
Optimal heat resistance can be given to the portion of the combustion cylinder in response to the combustion flame whose position changes and the amount of heat generation changes. Therefore, by using a combustion cylinder made of an inexpensive material having low heat resistance for the combustion flame at the time of low capacity, it is possible to reduce the amount of expensive high heat resistant material used and to reduce the cost.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention.

FIG. 2 is a side view showing an embodiment of the present invention.

FIG. 3 is an external perspective view showing an oil water heater to which an embodiment of the present invention is applied.

FIG. 4 shows an embodiment of the present invention and is an enlarged vertical sectional view of a main part.

FIG. 5 shows an embodiment of the present invention and is a side view of a main part.

[Explanation of symbols]

 1 Fuel Spray Combustor 2 Blower Duct 4 Burner Duct 5 Nozzle 7 Inner Cylinder 7a Throttle 7b Opening 8 Combustion Cylinder 11 First Combustion Cylinder Construct 11a Bottom Wall 11b Flange 11c Support Ring 11d / 11e Vent 12 Second Combustion Cylinder structure 13 Swirling blade 12a Small diameter part 12b Large diameter part 12c Continuous wall 12d ・ 12e Vent hole

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hidekazu Murata 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (3)

[Claims] 1. A burner duct into which combustion air is fed, a nozzle whose tip is inserted into the burner duct to inject fuel, an inner cylinder surrounding the nozzle, and an internal cylinder which is provided continuously to the inner cylinder. A combustion cylinder forming a space is provided, and the inner cylinder is formed with a throttle portion that is reduced in diameter toward the front in the fuel spray direction at the end portion on the side of connection with the combustion cylinder, and the combustion cylinder is provided with A fuel spray combustion device, wherein a plurality of swirl vanes are formed on an end surface of a side of connection with the inner cylinder so as to surround the connection part. 2. The combustion cylinder is expanded in diameter in multiple stages toward the front in the fuel spray direction, and the peripheral surface thereof and the end surface connecting the adjacent small diameter portion and large diameter portion are respectively provided. The fuel spray type combustion device according to claim 1, wherein a vent hole is formed. 3. The combustion cylinder is divided into a plurality of pieces in the lengthwise direction, and each of the divided parts is formed of a material having a different heat resistance.
The fuel spray type combustion device according to 1.