JPH0445724B2 - - Google Patents

Description

[Detailed Description of the Invention] 〓Field of Industrial Application〓 This invention relates to a combustion device in which air is forcibly supplied by a blower and high-load combustion is performed by a burner.
In particular, it is a forced air combustion system that has been improved to eliminate the oscillating combustion that occurs during operation.

〓Prior art and its problems〓 In forced air combustion devices such as instantaneous water heaters and space heaters, the setting range of hot water temperature or room temperature is wide, so it is necessary to vary the combustion amount over a wide range. At this time, the noise caused by combustion often becomes a problem. Among these noises, there is a phenomenon called oscillatory combustion due to the presence of combustion time delay t. The combustion time delay t is the time required for the fuel gas to undergo a complex combustion reaction such as thermal decomposition and finally change into heat after it is injected into the combustion chamber. The above-mentioned oscillatory combustion refers to vibrations caused by fluctuations in the flow rate of fuel gas or air supplied to the combustion chamber due to the combustion time delay t in conjunction with fluctuations in the pressure of the combustion chamber.

Figure 5 schematically shows the mechanism by which vibrations are excited. According to this figure, as shown in (a), as the pressure fluctuates in accordance with the natural vibration of the combustion chamber, the vibration occurs at the inlet of the combustion chamber. The differential pressure changes as shown in (b), and the fuel gas and air flow rates change accordingly as shown in (c).

This fluctuation in air flow rate does not have a completely opposite phase to the pressure fluctuation due to the flow rate response time delay s, but is slightly out of phase with the pressure fluctuation. Therefore, the fluctuation in the air flow rate is further shifted by the combustion time delay t, resulting in a fluctuation in the heat generation rate as shown in FIG. 5d, but pressure fluctuations occur due to the expansion of the gas.
When this pressure fluctuation becomes in phase with the original pressure fluctuation, the pressure fluctuation is amplified by resonance and becomes automatic vibration. The condition for this self-excited vibration to be established is when the sum of the combustion time delay t and the flow rate response time delay s becomes half of the vibration period. Therefore, in order to cut off self-excited vibration and eliminate oscillatory combustion, one measure is to set the time required for the fuel gas to finally change into heat through a chemical reaction, that is, the combustion time delay t, to deviate from half of the oscillation period. It is possible to do so.

As a combustor to prevent this resonance, JP-A-53-
Publication No. 11322 proposes the use of a burner with uneven flame openings.

However, the inventor found that a burner with uneven flame ports cannot achieve stable combustion if the amount of combustion in the burner is greatly changed. In other words, when the combustion amount is increased, the flow velocity becomes too fast at the flame opening with a large area,
Flame lift occurs, and when the combustion amount is reduced, backfire occurs at the small flame opening.

This invention was made in consideration of the above circumstances, and its purpose is to eliminate oscillating combustion and contribute to low-noise operation in forced air combustion devices such as instantaneous water heaters that increase the amount of combustion. It is an object of the present invention to provide a forced air combustion device which has excellent effects such as stable combustion.

〓Means for solving the problem〓 The present invention includes a plurality of burners each having a burner head and an inlet and arranged in parallel with each other, and air being forcibly supplied to the inlet of each burner. In a forced-air combustion system that changes the amount of combustion over a large range, it consists of a blower for blowing the flame, and a nozzle arranged in a row on a fuel gas supply pipe corresponding to the inlet of each burner. The technical means is that the ports have the same shape, the inlet ports have different areas, and the nozzle diameter of each nozzle is set according to the area of the inlet port.

In addition, in the forced air combustion device of the present invention, the area of the inlet is made different, and the nozzle diameter of each nozzle is set so that the air-fuel ratio is appropriate depending on the area of the inlet. Combustion is stable despite fluctuations within a wide range. In addition, by making the flame ports the same shape, the effective area serving as the flame port can be increased out of the total area of the combustion chamber. This is a technical measure that is advantageous in performing high-load combustion with a compact combustion device.

〓Action and effect of invention〓 According to this invention, there are the following effects.

By setting at least one of the burners to have a different combustion amount from the other burners, a) the combustion time delay t in the entire combustion process changes, and the phase shifts as described above, eliminating oscillatory combustion; It can contribute to low noise operation. In addition, the area of the inlet port is different and the nozzle diameter of each nozzle is set so that the air-fuel ratio is appropriate depending on the area of each inlet port. On the other hand, combustion becomes stable. Also, c) By making the flame ports the same shape, the effective area for the flame ports can be increased out of the total area of the combustion chamber. This is advantageous in a forced air combustion system that performs high-load combustion with a compact combustion system.

〓Example〓 An example of the present invention will be described below with reference to the drawings.

FIGS. 1 to 4 are diagrams showing an embodiment of a high-performance water heater characterized by a compact external shape.

In FIGS. 1 and 2, a plurality of burners 1 constituting a line-shaped gas burner are arranged in parallel at regular intervals, and a burner bottom plate 3 and a flame-holding plate 2, which serve as burner fixing means, are arranged in parallel. It is gripped and fixed between.

Burner 1 is pressed into a symmetrical shape.
Two metal plates are folded together along the center line of symmetry to form the burner head 11, and then adhered with high rigidity by welding, caulking, or screwing, and there are many stripes on the top surface. The burner head 11 has a long and narrow burner head 11 consisting of flame ports b arranged in parallel, and an inlet 13 for fuel gas and primary air is formed in the shape of a ring at the bottom. Reference numeral 14 denotes a gas introduction path that connects the gas and primary air inlet 13 and the burner head 11. Attached to both sides of the gas introduction path 14 are fin-shaped assembly members 15 for assembling the burner 1 in an aligned state as described above, and assembly protrusions 16 are formed on both sides of the bottom thereof.

A flame stabilizing plate 2 made of a rectangular metal plate is provided with holes 21 for insertion of the burner head 11 of the burner 1 and slit-shaped secondary air blowing holes 22 alternately spaced apart from each other at regular intervals.

The length of the secondary air blowing hole 22 is set to be approximately equal to the length of the burner 1 to the burner head 11.

The burner bottom plate 3 is made of metal and is formed into a flat box shape, and is provided with burner connection holes 31a to 31g for communicating the gas and primary air inlet 13 of the burner 1 in the longitudinal center thereof.
A group of 33 holes for blowing secondary air are bored on one side. 32a to 32g are burner connection holes 31a
This is a flange-shaped connecting ring for gripping the burner that is integrally formed on the inner peripheral edge of the burner. and,
Of these connecting rings 32a to 32g, every other connecting ring 32b, 32d, 32f is set so that its wall thickness increases toward the center, and its inner diameter decreases. There is. In addition, other connecting rings 32a, 32c, 32e,
The inner diameter size of 32g is set to be large enough to perform high-load combustion. Further, inside the burner bottom plate 3, pipes 100 for supplying fuel gas are disposed to face each other below the burner connection holes 31a to 31g. This pipe 100 has nozzles 100 corresponding to the connecting rings 32a to 32g.
A to 100g are erected in communication.
And connecting rings 31a, 31c, 31e, 31g
Nozzles 100a, 100c, 100 corresponding to
The inner diameters of nozzles 100b, 100d, and 100f corresponding to the other connecting rings 31b, 31d, and 31f are set within a relatively small range of 0.6 to 0.8 mm. There is.

Side wall plates 2a extending downward are integrally formed on two longitudinal sides of the flame stabilizing plate 2 by bending, and assembly protrusions 16 formed on the burner 1 are attached to the bottoms of these side wall plates 2a. An assembly hole 24 for fitting is provided. The inlet 13 is fitted and connected to the outer periphery of the connecting rings 32a to 32g, the burner 1 is held between the flame holding plate 2 and the burner bottom plate 3, and the bottom of the side wall plate 2a is connected to the burner by screws 17. By fixing it to the outer peripheral edge of the bottom plate 3, the line-shaped gas burner is assembled in the state shown in FIG. 4 is a piezoelectric igniter for igniting one burner located at one end of the burners 1 arranged in parallel, and 5 is a piezoelectric igniter for igniting one burner located at one end of the burners 1 arranged in parallel; This is a flame rod that serves as an ignition flame sensor to confirm that the flame has spread.

Figures 3 and 4 are a longitudinal cross-sectional view and a cross-sectional view of the high-load combustion water heater incorporating the linear gas burner of the above embodiment, in which the burner bottom plate 3 is used for blowing secondary air. The hole 33 etc. are slightly different. 6 is a blower for blowing combustion air, 7 is a heat exchanger for boiling water, 8 is a blower for blowing combustion air;
1 is a combustion duct, 9 is an exhaust grill, and 10 is a water heater casing.

Therefore, during combustion operation, that is, when using a water heater, the pipe 10 is driven by the blower 6.
Along with the fuel gas from the nozzles 100a to 100g of
The flame is blown up from the flame port b through the inlet 13 and the inlet path 14 of the burner 1 via 2a to 32g, and is ignited by the igniter 4. The ignition of this burner 1 spreads to other adjacent burners 1 one after another, and all burners 1 are ignited.

By the way, in the above combustion operation,
Among the connecting rings 32a to 32g, the connecting ring 32b,
32d, 32f are set to have a smaller diameter than the others, so these connecting rings 32b, 32d, 32f
Air passing through reduces its flow rate. Also, among the nozzles 100a to 100g, nozzle 100
Since the diameter dimensions of nozzles b, 100d, and 100f are set to be small, these nozzles 100b, 100f
The flow rate of the fuel gas discharged from d and 100f is reduced. Therefore, the connecting rings 32b, 32d, 32
f into the introduction section 13 and enters the introduction path 1 of the burner 1.
The velocity of the fuel gas and air rising along 4 becomes relatively slow and is preheated via the flame or burner 1, making the mixture of fuel gas and air chemically active with each other. Therefore, the above-mentioned mixed gas tends to burn quickly following the previous flame, and the flame continues without interruption, resulting in good flame stability. As the mixed gas is preheated in the process of ascending through the introduction path 14 of the burner 1 and is quickly combusted, the time required for the mixed gas to finally turn into heat, as described in the conventional explanation section, increases. It can be estimated that the combustion time delay t becomes small. Therefore, the combustion time delay t in the entire burner is shortened, and the oscillation period of pressure fluctuations accompanying flow rate fluctuations is prevented from being in the same phase as much as possible, preventing the occurrence of self-excited vibrations and suppressing oscillatory combustion. Contributes to the realization of noisy operation.

In the above embodiment, among the nozzles 100a to 100g, the nozzles 100b, 100d, 10
The inner diameter of 0f was set small, and the connecting rings 32b, 32d, and 32f among the connecting rings 32a to 32g were set small, so that three out of seven burners had a small combustion amount, which was different from the others. At least one of the nozzles and the connecting ring may have a smaller diameter so that the combustion amount is smaller than the others. In addition, contrary to the above, for example, at least one of the burners may have a large combustion amount (by making the nozzle diameter or connecting ring larger than the others), and the others may have different combustion amounts, and in this case, the combustion time delay t may be large. Changes to

Further, the number of burners 1 is not limited to seven as in the above embodiment, but may be set to a smaller number, such as three, in order to make the whole burner compact.

Various modifications may be made to other specific implementations of the heater, floor heating device, hot water heater, etc. without departing from the gist of the invention.

[Brief explanation of drawings]

Figures 1 to 4 are diagrams showing one embodiment of a high-load combustion water heater.
The figure is an external perspective view of a line-shaped gas burner incorporated into a water heater, Figure 2 is an exploded view thereof, Figure 3 is a vertical sectional view of the water heater, Figure 4 is a sectional view taken along line A--A in Figure 3, FIG. 5 is a graph for explaining the prior art. In the figure, 1... burner, 2... flame holding plate, 3... burner bottom plate, 4... igniter, 6... blower, 7...
Heat exchanger, 10... Water heater casing, 11...
... Burner head, 13 ... Gas and primary air inlet, 22 ... Secondary air outlet, b ... Burner port, 1
00a~100g...Nozzle, 32a~32g...
...connected ring.

Claims (1)

[Scope of Claims] 1. A plurality of burners each forming a burner head and an inlet and arranged in parallel with each other, a blower for forcibly supplying air to the inlet of each burner, and each burner. In a forced-air combustion device that changes the amount of combustion over a large range and consists of nozzles arranged in a row on a fuel gas supply pipe corresponding to the inlet of the burner, each burner has a flame port of the same shape, and A forced air combustion device characterized in that the ports have different areas, and each nozzle has a nozzle diameter set according to the area of the inlet.