JPH0367909A - Combustion device - Google Patents

Abstract

PURPOSE:To enable formation of stable, long flame free from CO and soot by providing a long combustion chamber communicating with a secondary air passage downstream of a burner port, and by causing a part of a secondary air passage to communicate with a tertiary air passage. CONSTITUTION:Fuel gas is forced into a premixing chamber 2 from a fuel nozzle 3 and at the same time nearly uniform air having passed through a perforated plate 5 under the action of a fan means 1 flows into a premixing chamber 2 to be mixed with the fuel gas, which flows toward a burner port 6. Other air passages through a perforated straightening plate 9 in a secondary air passage 8 and then through a contraction section 12 toward a combustion chamber 10 and flows from the secondary air passage 8 through a tertiary air admission port 16 to a tertiary air port 15. And a mixed gas of the fuel gas blowing off from the port 6 and the air is formed into flames 13 by means of an ignition means 14. At this time, the air from the passage 8 is forcibly fed to the outer periphery of the flames 13 by the action of the section 12 to accelerate combustion as secondary air. And further, the tertiary air is supplied to the center of the premixed air from the passage 15. A flame 16 is formed downstream of the center of the burner port along the stream of said tertiary air.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a combustion device for domestic use.

2. Description of the Related Art Conventionally, this type of combustion apparatus has an air swirling section 23 in a nozzle section 22 in a cylindrical combustion chamber 21, as shown in FIG. In many cases, combustion is performed using a pre-mixing type diffusion combustor, or air is premixed and ejected from a nozzle, and air for diffusion combustion is supplied around the premixed air. These have been designed with the aim of quickly mixing air and fuel and burning it. In other words, it is undesirable for the flame to be long;
If it were to last too long, it would generate soot.

In addition, rapid mixing of air and fuel resulted in flame instability, and when the mixing was weakened, the above-mentioned soot was generated.

Problems to be Solved by the Invention In the above configuration, the combustion load is high, and although combustion can be completed in a small combustion chamber, the combustion part becomes very hot.
The durability of the material becomes an issue. On the other hand, if the flame is made longer, its length will be limited by the problem of soot or CO. According to experiments, a length of 20 to 25 cm is the limit.

The present invention solves these conventional problems by producing a long, stable flame that produces no CO or soot, which was previously considered impossible, and obtaining a long heating surface with low combustion noise and little temperature difference. With the goal.

Means for Solving the Problems In order to solve the above problems, the combustion apparatus of the present invention includes a premixing chamber for mixing fuel and air downstream of the blowing means, and a fuel nozzle located upstream of the premixing chamber. A flame hole is provided on the downstream side of the premixing chamber, and a tertiary air passage extending from the premixing chamber through the center of the flame hole is provided so as to supply the secondary air to the downstream side of the flame hole. A long combustion chamber is provided in communication with the passage, and a part of the secondary air passage communicates with the tertiary air passage.

Effect of the present invention With the above-described configuration, fuel and air are mixed in the premixing chamber by the operation of the blowing means and the fuel nozzle, the premixture is ejected from the flame hole into the combustion chamber, and at the same time, the air from the secondary air passage is is supplied to the outer periphery of the flame, and a flame is formed by actuation of the ignition means. Furthermore, tertiary air is supplied from the tertiary air passage to the central part of the premixture that is difficult for secondary air to reach, and a flame is formed downstream of the central part of the flame hole along the flow of this tertiary air. By supplying air into and out of the premix in this manner, the contact area between the fuel and air is increased, a double combustion reaction zone is formed, and stable combustion without generation of CO or soot can be achieved.

In addition, by supplying a portion of the total amount of air from the tertiary air passage extending from the flame hole surface, the air flow velocity near the flame hole can be set to a small value, which prevents sudden and violent reactions at the flame hole. Without,
Combustion noise can be reduced.

Furthermore, the secondary air stretches the flow of the premixture in the combustion chamber and forms a long, stable flame within the combustion chamber, making it possible to maintain substantially thermal uniformity within the combustion chamber.

Example Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 1, ■ indicates a blowing means such as an axial fan, and the broken line arrow indicates air. 2 is a substantially cylindrical premixing chamber;
The fuel (gas) from the fuel pipe 4 is fed into the premixing chamber 2 on the upstream side.
The fuel nozzle 3 that spouts inward is shown. Solid arrows indicate gas. 5 is a perforated plate provided in the premixing chamber 2;
The flow rate of air supplied to the premixing chamber 2 is made uniform. 6
1 is a flame hole made of a punched plate or a wire mesh, and 7 is a flame holding part formed around the flame hole 6 to fix the flame hole 6 to the premixing chamber 2. 8 is a secondary air passage provided concentrically around the outer periphery of the premixing chamber 2. Reference numeral 9 denotes a porous rectifier plate provided in the secondary air passage 8, which equalizes the flow velocity of the secondary air. 9a is a cylindrical burner case provided around the outer periphery of the secondary air passage 8.

10 is a long combustion chamber that communicates with the secondary air passage 8 and is provided on the downstream side of the flame hole 6, and 11 is a water-cooled wall formed around the combustion chamber 10. Reference numeral 12 denotes a constriction portion provided to the secondary air passage 8 on the downstream side of the flame hole 6. 13 is a flame formed downstream of the flame hole 6, and 14 is an ignition means. A tertiary air passage 15 passes through the center of the flame hole 6, one end extends toward the combustion chamber 10, and the other end is a tertiary air inlet provided approximately in the middle of the premixing chamber 2. 16 and communicates with the secondary air passage 8.

In the above configuration, the fuel gas is ejected from the fuel nozzle 3 into the premixing chamber 2, and at the same time, by the operation of the blowing means, the almost uniform air passes through the perforated plate 5 and enters the premixing chamber 2, and the fuel gas and flows to flame hole 5 (jl, +l).

Other air passes through the porous baffle plate 9 in the secondary air passage B, passes through the throttle section 12, and flows toward the combustion chamber 10 side. Further, the air flows from the secondary air passage 8 to the tertiary air port 15 via the tertiary air inlet 16. Now, the mixture of fuel gas and air ejected from the flame hole 6 becomes a flame 13 by the ignition means 14. At this time, the air from the secondary air passage 8 is forcibly supplied to the outer periphery of the flame 13 by the throttle part 12, and can promote combustion as secondary air. Furthermore, tertiary air is supplied from the tertiary air passage 15 to the central part of the premixture, and along the flow of this tertiary air, a flame 1 is supplied to the downstream side of the central part of the flame hole.
form 6. By supplying air into and out of the premix in this manner, the contact area between the fuel and air is increased, and stable combustion without generation of CO or soot can be achieved.

The secondary air stretches the flow of the premix in the combustion chamber 10 and creates an air layer near the inner wall of the combustion chamber 10, so even if the flame 13 becomes long, no soot is generated due to lack of air, resulting in stable combustion. be able to. Further, since a long flame 13 is formed within the combustion chamber 10, the inside of the combustion chamber 10 can be kept thermally almost uniform. The flame length is determined by the amount of air supplied to the combustion chamber 2 or the tertiary air passage 1.
It can be adjusted by increasing or decreasing the amount of air from 5.

In addition, by supplying a portion of the total amount of air into the preliminary air from the tertiary air passage 15 extending from the flame hole 6, the secondary air flow velocity near the flame hole 6 can be set to a small value. flame hole 6
There is no sudden reaction near .

In addition, even if the amount of air is relatively large, flame 1 due to secondary air
3. It is possible to perform low-noise combustion with less turbulence.

Effects of the Invention As described above, according to the combustion apparatus of the present invention, the following effects can be obtained.

(1) C○, it is possible to form a stable long flame without soot, and it is possible to obtain a columnar combustion device with a long heating surface with small temperature difference, which has a wide range of uses such as heating, hot water supply, and drying. .

(2) Since air is supplied separately from the inside and outside to the air-fuel mixture, there is no turbulence in the flame and combustion can be performed with low noise.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of a combustion device according to an embodiment of the present invention, and FIG. 2 is a schematic sectional view of a burner portion of a conventional combustion device. 1...Air blowing means, 2...Premixing chamber, 3.
... combustion nozzle, 6 ... flame hole, 8 ... secondary air passage, 10 ... combustion chamber, 15 ... tertiary air passage.

Claims (1)

[Claims] A premixing chamber for mixing fuel and air is provided downstream of the blowing means, a fuel nozzle faces upstream of the premixing chamber, a flame hole is provided downstream of the premixing chamber, and a A tertiary air passage extending through the center of the flame hole is provided, a secondary air passage is provided concentrically around the outer periphery of the premixing chamber, and the secondary air passage is connected to the downstream side of the flame hole. A combustion device in which a long communicating combustion chamber is provided, and a part of the secondary air passage and a tertiary air passage are communicated with each other.