JPS5986813A - Burner device - Google Patents

Abstract

PURPOSE:To enable miniaturization of a combustion chamber and reduction of creation of combustion noise, and to enable reduction of the pressure of blast and an increase in a stable combustion range, by selecting the structure of the combustion chamber and the supply condition of a secondary air. CONSTITUTION:Fuel-air premixture, fed from a mixture chamber 11, is supplied in a combustion chamber 16 through a burner port part 12. Meanwhile, a secondary air enters an air chamber 13, and a part thereof, controlled into a specified flow rate by control plates 15, enters an air chamber 14. The secondary air, entering the air chamber 14, is fed approximately parallel to the flow-out direction of air-fuel premixture from a part around the burner port 12 through air ports 18 to form a stable flame F'1. The remaining secondary air within an air chamber 13, after passing through air ports 17, is fed in the combustion chamber 16 in a direction extending at an inclining angle with the injection direction of the air-fuel premixture and is forcibly mixed with unburnt gas to form a flame F'2 having the short length of a flame. In which case, if the equivalent weight ratio of an air-fuel premixture flow is set to 1.5-3.0, the velocity of flow of a parallel secondary air to 0.3-2m/S. The velocity of flow of an inclining secondary air to 1.5-10m/S, and the area load of a burner port to 1.0-18kcal/mm.<2>, the device is prevented from restriction of vibrating combustion and backfire, resulting in reduction in creation of noise.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention is a method for reducing flame length in household combustion machines such as water heaters and space heaters by supplying forced air using a fan or the like to promote the combustion reaction. The present invention relates to a combustion device that reduces the size of the combustion section.

Conventional Structure and Problems There is a combustion apparatus of this type having a structure as shown in FIG. This is heat exchanger frame 1 and mixing chamber 2
and a burner 4 having a flame opening surface 3, a pair of throttle plates 5 provided in the heat exchanger frame 1, a pair of tertiary air chambers 6 adjacent to the flame on the downstream side of the throttle plates 6, and a pair of tertiary air chambers 6 adjacent to the flame on the downstream side of the throttle plates 6. It has a secondary air chamber 8 between the burner 4 upstream (lull) and the heat exchanger frame 1, and a throttle plate 6 that connects the combustion chamber between the upstream primary combustion chamber 9 and the downstream side. This combustion device has a partitioned structure into a secondary combustion chamber 1o.

The premixed gas ejected from the flame port surface 3 flows out from the secondary air chamber 8 and forms a stable flame F1 in the primary combustion chamber 9 by secondary air supplied from both sides of the flame port surface 3. Thereafter, the combustion gas, the unused gas, and a portion of the secondary air undergo contraction at the same time at the throttle plate 5, and then flow into the secondary combustion chamber 1o. The secondary air is supplied again from the tertiary air chamber 6 through the air jet lower at a relatively high speed and from a direction perpendicular to the flow of combustion gas, and the gas is forcibly mixed to form a flame F2 with a small flame length. . Therefore, the height of the combustion chamber can be configured to be low and the size of the combustion device can be reduced.

According to the experiments conducted by the inventors, as shown in Fig. 2, if the distance H from the flame outlet surface 3 to the air jet lower and the flow velocity v2 of the secondary air flow are the same, the smaller H is, the longer the flame length is. It was found that as H becomes larger, the flow velocity v2 needs to be increased in order to make the flame length smaller and the flame length the same. Therefore, in the conventional example shown in FIG. 1, since H is relatively large, the flame length will become large unless the flow velocity v2 is increased.

In this case, if the flow velocity ■2 is too large, the upstream stable flame F
1 may be disturbed, but the aperture plate 5 prevents this effect. However, by providing the aperture plate 5, the flame F1
Ineffective regions A that do not contribute to the promotion of combustion reaction are formed on both sides of the combustion chamber, which hinders miniaturization of the combustion chamber. Contraction effect due to trench aperture plate 5 and high secondary air flow velocity v
2, the upstream side of the flame F2 is greatly disturbed and there is a possibility that the combustion noise will be increased. Furthermore, the tip of the aperture plate 5 is a flame F1.
Heat resistance is a problem because it is close to the flow rate v2
It also has problems such as requiring a large fan to increase the size of the fan.

As explained above, in conventional combustion apparatuses, by forcibly supplying secondary air to the flame, the flame length can be reduced and the combustion chamber can be downsized, but on the other hand, there is still an ineffective area. There is a problem with heat resistance in some of the two members that cause a conflicting effect and increase combustion noise.

This had drawbacks such as the need for a fan with high blowing pressure.

Purpose of the Invention The present invention solves these conventional problems, and achieves miniaturization of the combustion chamber and reduction of combustion noise, which were contradictory in the past, as well as reduction of blowing pressure and expansion of stable combustion range. With the goal.

Structure of the Invention As already explained in Fig. 2, the smaller the distance H between the flame port and the air port that supplies secondary air, the greater the effect of reducing the flame length. , combustion noise becomes louder, and the flame stability range becomes narrower. Therefore, the combustion apparatus of the present invention includes a means for supplying parallel secondary air that is supplied approximately in parallel to the premixed air flow jetted from the flame ports around a flame port formed by arranging a large number of flame ports; It has an inclined secondary air supply means that is supplied at an inclined angle to the premixed airflow provided at a distance of less than 20 mm from the flame outlet on the downstream side of the burner, and the equivalence ratio of the premixed airflow is set to 1.5. ~3.0, the flow velocity of the parallel secondary air is 0.3 to 2 m/s, and the flow velocity of the secondary air is 1.0 m/s.
5 to 10+n/s, and the flame area load is 1.0 to 18k.
The cal/h ratio is the same. With this combustion device configuration and secondary air supply conditions, the distance between the flame port and the inclined secondary air supply means is shortened, making it possible to reduce the flame length with a smaller secondary air flow velocity v2. Furthermore, since the secondary air is supplied at an angle of inclination, the influence on the flame base on the upstream side can be reduced. Furthermore, as the equivalence ratio becomes larger than 1, the combustion speed decreases, or the premixture ejected from the flame nozzle due to parallel secondary air supplied around the flame nozzle becomes secondary air due to diffusion and vortex action. By mixing, the equivalence ratio locally decreases and the combustion rate increases, making it possible to stabilize the flame base over a wide range of equivalence ratios. If the flame front is made to be continuous with the flame front formed by the parallel secondary air or the flame front formed by the inclined secondary air, the turbulence of the flame front will be reduced and the combustion noise will be reduced.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 3 to 6. In Fig. 3, the mixing chamber 11 and flame outlet 1 are in the center.
2 is provided, and a pair of inclined secondary air air chambers 13 are provided on both sides thereof.

A pair of air chambers 1 for parallel secondary air are provided on both sides of the flame port 120.
4 is in contact with the air chamber 13 via the control plate 15. The oblique and parallel secondary air chambers 13 , 14 are provided with respective air openings 17 , 18 opening into the combustion chamber 16 . Here, the air port 17 is provided on the downstream side of the burner port 1'I2, and is provided at an angle of inclination to the premixed air jetted from the burner port 12, and the air port 18 is provided approximately on the same plane as the burner port 12. are placed in parallel. The combustion chamber 16 is surrounded by a heat exchange drum 19 and is quadrupled by heat exchanger fins 20 on the downstream side.

To explain the operation in FIG. 3, the premixture supplied from the mixing chamber 11 is supplied into the combustion chamber 16 through the flame port 12. On the other hand, the secondary air first enters the air chamber 13, and a portion thereof is controlled to a predetermined flow rate by the control plate 16 and enters the air chamber 14.

The secondary air that has entered the air chamber 14 is sent to the flame port 1 through the air port 18.
The flame F1' is supplied from around 20 approximately parallel to the outflow direction of the premixture to form a stable flame F1'.

In addition, the remaining secondary air in the air chamber 13 passes through the air port 17 and enters the combustion chamber 16 at an inclination angle with respect to the injection direction of the premixture.
The gas is forcibly mixed with the unburned gas to form a flame F2' with a small flame length. The combustion gas that has completed the combustion reaction exchanges heat with the heat exchanger drum 19 and the fins 2o, and then is released into the outside air.

The characteristics of such a combustion method will be explained based on FIGS. 4 to 6.

In Figure 4, the horizontal axis shows the equivalence ratio φ, and the vertical axis shows the injection velocity V of the premixture.
The flame behavior is shown by taking m i x.

When the flow velocity v2 of the inclined secondary air is ■2-o, the flame stability region is only a narrow range of φ≦1.5, and the combustion amount variable width, that is, the variable width of Vm i x is the oscillating combustion region and the flashback region. Since the engine is constrained by upper and lower limits, TDR (throttle ratio = minimum combustion amount / maximum combustion amount) cannot be made large.

Next, when v2 is increased, the yellow flame limit line becomes φ and Vm i x
It was confirmed through experiments that the flame stability region expands as v2 increases.

Therefore, as will be explained later, φ=3, which is considered to be the limit due to combustion noise constraints. It can be seen that if the equivalence ratio is set to 1.6≦φ≦3.0 at o f, there will be no restrictions on oscillatory combustion or flashback even if the TDR is made large. In addition, Fig. 4 shows the line of the same combustion amount, that is, the line of the same flame load, and the maximum value is 1.6≦
18k Cal at a value that does not cause blow-off at φ3.0
/h/III#, the minimum value is the value that does not cause flashback, including the transient region during combustion control, 1, 0kcal/h 7m4
It is. Figure 6 shows the ratio vmix/v2 between the premixture flow velocity and the inclined secondary air flow velocity on the vertical axis, and the inclined secondary air flow velocity v2 on the horizontal axis.
shows the rhombus-shaped actual usage area surrounded by the actual usage range of the flame port load mentioned above and the maximum and minimum air excess ratio range determined by the control accuracy of the supply air amount and gas amount during combustion control. It is something that

The figure also shows the yellow flame limit, which is a problem in practical use, and the partial blow-off limit, where part of the flame blows out. From this figure, in order to avoid problems in actual use, 1.6≦v2≦10m is required.
It can be seen that it is necessary to set the value to /sec.

Figure 6 shows the combustion noise reduction effect of parallel secondary air, where the vertical axis represents the combustion noise and the horizontal axis represents the parallel secondary air flow velocity v1.
This is what is shown. Equivalence ratio φ is 1.5 and 3
．． Although the case where φ is 0 is shown, the combustion noise becomes larger as φ becomes larger, and increases significantly when φ>3.0. This is the third
This is because the turbulence of the flame F2' shown in the figure becomes severe.

1.5≦φ3.0, v1f! As c increases, there is a point where the noise suddenly decreases, and then ■1 As c increases, it does not change much, but v1≧20αa/! At 1, the noise starts to rise again.

According to flame observation, as shown in FIG. 3, as vl increases, separate flames F1' and F2' formed near the respective air ports 18 and 17 become continuous. At this time, a sudden decrease in noise was observed. As shown in Fig. 6, in the range of 1.5≦φ≦3.0, 30≦v1≦
It can be seen that combustion noise is reduced when the speed is set to 200 cm/s.

Next, another embodiment of the present invention is shown in FIG. The difference in FIG. 7 from the previous embodiment is that the flame ports are provided in parallel, and therefore, there is another inclined secondary air air chamber 22 on the downstream side of the central premixing chamber 21. A pair of parallel air chambers 23 for secondary air are provided on both sides. According to this configuration, if the device has the same combustion amount, the longitudinal dimension is halved, and it is possible to take measures against air-fuel mixture distribution and to reduce the amount of thermal distortion in the longitudinal direction.

In addition, in the above embodiment, an explanatory diagram showing the area in which the air supply for parallel secondary air is distributed from the inclined secondary air air chamber, and FIG. 6 shows the influence of parallel air flow velocity on combustion noise. The explanatory diagram, FIG. 7, is a sectional view showing another embodiment of the present invention.

12...flame mouth part, 13...air chamber for inclined secondary air, 14...air chamber for parallel secondary air,
17... Inclined secondary air air port, 18...
...Air port for parallel secondary air.

Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Distance between flame outlet and T inlet 11-1 (-?yL) Figure 3 2θ Figure 4 Equivalent r φ Figure 5 Associate page slant 2; Figure parallel secondary air i speed Vt Cc Luli Figure 7

Claims (1)

[Claims] (1) A means for supplying parallel secondary air that is supplied to the periphery of a flame port formed by arranging a large number of flame ports in a manner substantially parallel to the premixed airflow ejected from the flame ports; A supply means for supplying inclined secondary air is provided downstream of the supply means and is supplied at an inclined angle with respect to the premixed airflow, and the equivalence ratio of the premixed airflow is set to 1.5 to 3.0, and the parallel secondary air A combustion device in which the flow velocity of the secondary air is 0.3 to 2 m/S, the flow velocity of the inclined secondary air is 1.5 to 10 m/S, and the flame opening area load is 1.0 to 18 kcal AIM. (Rumor) The combustion device according to claim 1, wherein the inclined secondary air supply means is provided within 20 minutes downstream of the flame port.