JPH0518006B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a pulse combustion device that is used as a heat source for industrial, commercial, or domestic water heaters, hot air fans, and the like.

Conventional configurations and their problems Pulse combustors have high heat exchange efficiency and can perform forced air supply and exhaust combustion on their own without the aid of a blower, making them useful as heat sources for energy-saving equipment. However, there were practical problems such as large noise and narrow variable range of combustion amount.

In order to solve these problems, attempts have been made to install multiple pulse combustors with low heat output in parallel and control their operation to widen the variable range of combustion amount and reduce noise. . However, since each pulse frequency is slightly different, a new problem has arisen: whirring noise.

Even at the same level of noise, noise accompanied by a growl can be extremely annoying, and a solution to this problem is desired.

Purpose of the Invention The present invention provides a low-noise pulse combustion device that synchronizes the combustion states of a plurality of pulse combustors to cause combustion to occur at the same pulse frequency, thereby preventing the generation of humming noise. With the goal.

Structure of the Invention The present invention includes a plurality of pulse combustors whose inputs are equally divided so that the sum of the inputs becomes the required input, and the tail pipes of the plurality of pulse combustors are mutually connected. By communicating with
This is a pulse combustion device that allows the operating states of these pulse combustors to interfere with each other and synchronizes the pulse combustion frequency.

DESCRIPTION OF THE EMBODIMENTS The figure shows a pulse combustion apparatus according to an embodiment of the present invention in which two pulse combustors are arranged in parallel. 1 indicates a first pulse combustor, and 2 indicates a second pulse combustor. 3 and 4 are combustion chambers, 5 and 6 are tail pipes, 7 and 8 are exhaust cushion chambers, 9 and 1
0 is a gas distributor, 11 and 12 are air passages, 13 and 14 are spark plugs, 15 and 16 are air valves, 17 and 18 are gas valves 19 is an air cushion chamber, 20 is a can body, 21 is water, 2
2 and 23 are exhaust pipes, 24 is combustion air, 2
5 and 26 are fuel gas, 27 and 28 are combustion waste gas,
29 is a communicating pipe, and 30 is a communicating flow.

Next, the operation will be explained. Combustion gas 25,2
The gas 6 passes through gas valves 17 and 18 and is supplied to the combustion chambers 3 and 4 from distributors 9 and 10 having a large number of nozzle holes.

Combustion air 24 is supplied from a blower (not shown) and is supplied to the combustion chambers 3 and 4 through an air cushion chamber 19, air valves 15 and 16, and air passages 11 and 12. The fuel gas and combustion air supplied to the combustion chambers 3 and 4 are mixed to form an air-fuel mixture, which explodes and burns due to discharge from the spark plugs 13 and 14. Due to the explosion, the pressure inside the combustion chambers 3 and 4 increases, causing air valves 15 and 16 and gas valve 1 to rise.
7 and 18 are closed, and the supply of fuel gases 25 and 26 and combustion air 24 is stopped. High temperature combustion waste gas 2
7 and 28 exchange heat with water 21 while passing through thin tail pulps 5 and 6, and flow into exhaust cushion chambers 7 and 8 while lowering the temperature. Combustion waste gas 2
7 and 28 are further discharged outside the vessel through exhaust pipes 22 and 23.

When the combustion waste gases 27 and 28 pass through the tail pipes 5 and 6, the pressure inside the combustion chambers 3 and 4 becomes negative pressure,
The air valves 15, 16 and the gas valves 17, 18 are opened, and combustion air 24 and fuel gas 25, 26 are sucked into the combustion chambers 3, 4. At that time, the high-temperature combustion waste gas in the combustion chamber causes the mixture with combustion air and combustion gas to explode. Then, similar explosions occur one after another, resulting in a pulse combustion state. Once the pulse combustion state is reached, the pulse combustion is automatically continued even if the blower and spark plugs 13 and 14 are stopped.

Although the pulse combustors 1 and 2 are made with the same specifications, differences in combustion amount and pulse frequency occur due to dimensional differences in manufacturing and assembly of parts. As a result, when two pulse combustors are burned without providing a pulse frequency synchronization function due to mutual interference, the combustion noise is accompanied by a whirring sound.
It becomes extremely annoying.

The description will now be made assuming that the first pulse combustor 1 has a larger combustion amount and a higher pulse frequency than the second pulse combustor 2. Therefore, the pressure generated in the combustion chamber 3 when the air-fuel mixture explodes is greater than the pressure generated in the combustion chamber 4. Therefore, the speed at which the discharge process propagates inside the tail pipe 5 is
It is faster than the speed at which it propagates inside, and the propagation time is also faster. For that reason, the connecting pipe 2 of the tail pipes 5 and 6
The flow velocity of the combustion waste gas 27 in the portions communicated by 9 becomes faster than the flow velocity of the combustion waste gas 28. Combustion waste gas 2 due to the effluent effect of the fast flow 27
A part of the combustor 8 passes through the communication pipe 29, becomes a rapid flow 30, and is sucked out toward the pulse combustor 1 in the direction of the arrow. As a result, the amount of combustion waste gas discharged from the combustion chamber 4 increases, the degree of negative pressure generated increases, and the discharge time becomes shorter. When the degree of negative pressure in the combustion chambers 3 and 4 increases and the suction process begins, the pulse combustor 1 enters the suction process earlier because the negative pressure in the combustion chamber 3 is initially larger. The flow is reversed, and part of the combustion waste gas 27 flows in the opposite direction to the arrow in FIG. 1 and flows toward the combustion chamber 3.
As the intake process progresses, a part of the counter-flowing combustion waste gas 28 is sucked into the pulse combustor 1 again through the communication pipe 29 due to the effluent effect of the strong flow of this counter-flowing combustion waste gas 27 . As a result, the amount of combustion waste gas 28 flowing back from the tail pipe 6 to the combustion chamber 4 due to the negative pressure in the combustion chamber 4 is reduced.
Instead, there are 18 gas pulps and 16 air valves.
The amount of air-fuel mixture flowing into the combustion chamber 4 through the combustion chamber 4 increases. Therefore, as the combustion amount of the pulse combustor 2 increases, the pulse frequency also increases, and the two pulse combustors burn in synchronization with the same pulse frequency, so that no humming noise is generated.

By the way, it is thought that the larger the cross-sectional area of the communication pipe 29, the greater the synchronization effect, but the assisting force exerted on the pulse combustor 2 by the pulse combustor 1 becomes too large, and the original operation of the pulse combustor 2 is interrupted. As a result, the cycle is suddenly disturbed, resulting in poor ignition performance at the start of operation and unstable combustion. When the combustor 2 becomes malfunctioning, the effect is conversely exerted on the combustor 1, causing combustion to become unstable or a misfire to occur. The cross-sectional area of the communication pipe 29 is defined as the tail pipe 5,
By making the cross-sectional area approximately 1/3 or less of the cross-sectional area of No. 6, the synchronizing force becomes appropriate and this problem is solved. On the other hand, if the cross-sectional area of the communication tube 29 becomes too small, the synchronizing force will become weak, and the whirring noise will again occur irregularly. This problem could also be solved by making the cross-sectional area of the communicating pipe 29 approximately 1/20 or less of the cross-sectional area of the tail pipes 5 and 6. Therefore, by setting the cross-sectional area of the communicating pipe 29 to 1/3 to 1/20 of the cross-sectional area of the tie pipes 5 and 6, good synchronizing force for pulse combustion, good ignition performance, and stable combustion performance can be achieved. can be provided.

Next, we will explain why noise, which is the biggest drawback of a pulse combustion device that has beneficial features, can be reduced by arranging a plurality of pulse combustors in parallel and firing them consecutively.

Now, assuming that a pulse combustor with a combustion rate of 50,000 Kcal/H is required, if this is made with one pulse combustor, the combustion noise will be approximately 114 dB(A).
Assuming that two combustors with a capacity of 25,000 Kcal/H have a capacity of 50,000 Kcal/H, the noise of one combustor with a capacity of 25,000 Kcal/H is approximately 108 dB(A), and the noise of two combustors at the same time is approximately 108 dB(A). When burned, it becomes 111dB(A) and 50,000Kcal/
It can be expected to be 3 dB lower than when using only one H. Actually, when two 25,000 Kcal/H combustors are used, the noise level is approximately 109 dB(A), which is a 5 dB reduction effect compared to one 50,000 Kcal/H combustor. This 2dB increase in reduction effect is due to the additional effect of reducing the sound radiated from the wall by increasing the wall strength of the combustor structure by dividing the combustor into two combustors and installing them side by side. it is conceivable that.

Furthermore, if we consider the case where five combustors with a capacity of 10,000 Kcal/H are installed in parallel, the noise of one 10,000 Kcal/H combustor will be 100 dB(A), so five combustors will be fired in succession. and 107dB(A), so a reduction effect of 7dB can be expected. The more divided sheets there are, the greater the reduction effect will be, but the cost will be higher, and considering the relative effect on cost, it seems actually better to divide into 2 or 3 pieces.

Effects of the Invention As is clear from the description of the embodiments above, the pulse combustion device of the present invention has a plurality of tail pipes arranged in parallel communicating with each other through a communication pipe, so that the combustor with a large amount of combustion This prevents the interference effect from becoming too large or too small even in combustors with small volumes, adjusts the interference force to an appropriate level, makes the combustion sound of multiple combustors almost the same, and reduces the combustion frequency. It is something that can be synchronized and matched. As a result, it is possible to eliminate the "whining sound" which is an interference phenomenon between the combustors of a plurality of pulse combustors, and to make the combustion sound with a constant amplitude, making it possible to reduce noise and achieve energy savings.

[Brief explanation of the drawing]

The figure is a block diagram of the main parts of a pulse combustion device according to an embodiment of the present invention. 3, 4... Combustion chamber, 5, 6... Tail pipe,
27, 28... Combustion waste gas, 29... Communication pipe, 30
...A continuous flow.

Claims (1)

[Scope of Claims] 1. A combustion chamber, a fuel supply means and an air supply means connected to the upstream part of the combustion chamber, a tail pipe connected to the downstream part of the combustion chamber, and a buffer chamber connected to the downstream part of the tail pipe. A pulse combustion device includes a plurality of pulse combustors arranged in parallel, and the tail pipes of the plurality of tail pipes are communicated with each other through a communication pipe. 2 Set the cross-sectional area of the communication pipe to 1/1 of the cross-sectional area of the tail pipe.
2. The pulse combustion apparatus according to claim 1, wherein the pulse combustion apparatus has a combustion rate of 3 to 1/20.