JPH06147427A - Hot water supply burner - Google Patents

Abstract

PURPOSE:To prevent pulsating combustion by protecting a combustion chamber, a heat exchanger or an exhaust air passage from a spontaneous pressure rise and to prevent pulsating combustion by changing the movement of combustion gas in an exhaustion cylinder. CONSTITUTION:There are provided a ventilation passage 5 for pre-mixed gas, a burner port section 8 where a large number of burner ports 6 are installed to the downstream of the ventilation passage 5, a combustion chamber 9 installed to the downstream of the burner port section 8, a heat exchanger 11 installed to the downstream of the combustion chamber 9 an exhaust passage 12 installed to the downstream of the heat exchanger 11 and an exhaust cylinder 13 installed to the dowstream of the exhaust passage 12. There are further installed a secondary air passage 15, a secondary fan or a secondary air passage 16 and a secondary fan 17 or a secondary air passage 18 and a secondary fan 19 which supply a secondary air to the combustion chamber 9 and the heat exchanger 11 or the exhaust air passage 12. Or an exhaust cylinder fan is installed to the exhaust cylinder 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot water supply combustor used for heating and hot water supply.

[0002]

2. Description of the Related Art All primary combustion is NO when burned with lean fuel.
_{Since it} emits a small amount of _X , it is used as a low NO _X combustor. However, in this type of burner, when premixed air is supplied by a blower and a combustion chamber and a heat exchanger are installed in the burner, oscillating combustion often occurs. Among them, Helmholtz type oscillatory combustion is often observed.

This will be described with reference to the block diagram of the hot water supply combustor according to the first embodiment of the present invention.

The air sent from the primary blower 1 and the fuel sent from the fuel supply path 2 are mixed in the mixing chamber 3,
Premixed gas is 4. The premixed air 4 passes through the ventilation passage 5 and reaches the flame hole portion 8 having a large number of flame holes 6. Igniter
When the premixed gas 4 is ignited by (not shown), a flame 7 is formed on the flame hole 6 and completely burns in the combustion chamber 9.

On the inlet side of the combustion chamber 9, the flame hole portion 8
However, the heat exchanger 11 is arranged on the outlet side, and the generated high-temperature combustion gas 10 is sent to the heat exchanger 11 provided on the output side of the combustion chamber 9, where the inside of the heat exchanger 11 is Heat exchange with the fluid passing through. Then, the combustion gas 10 that has been heat-exchanged and cooled is
From the exhaust passage 12 provided downstream of the heat exchanger 11, it passes through the exhaust pipe 13 and is discharged into the atmosphere.

Oscillating combustion often occurs in such a combustor. However, if an exhaust pipe 13 having a flame hole 6 smaller than the exhaust passage 12 is installed, it is downstream of the flame hole 6 called Helmholtz type oscillatory combustion in the oscillatory combustion. Oscillating combustion occurs with a rapid pressure increase in the side part.

Helmholtz oscillatory combustion is modeled as a combined volume and pipe element system. That is,
It vibrates due to the transfer of energy between the potential energy due to the rise in pressure in the volume element and the kinetic energy of the combustion gas flowing in the pipe element. here,
The combustion gas in the pipe element acts as a rigid body, and its periodic movement is called plug flow. In FIG. 1, the combustion chamber 9, the heat exchanger 11, and the exhaust passage 12 are volume elements,
The exhaust stack 13 serves as a pipe element. When the Helmholtz type vibration combustion occurs, it is as if the combustion chamber 9, the heat exchanger 11, the exhaust passage.
In-phase, as if 12 were volume elements with an integral structure,
The pressure rises at the same pressure. Since the area of the portion of the exhaust stack 13 is small, the pressure loss is large, so that the exhaust stack 13 behaves as a pipe element.

[0008]

In the above configuration, when Helmholtz type oscillatory combustion occurs, the pressure in the combustion chamber 9, the heat exchanger 11, and the exhaust passage 12 becomes several tens to several hundreds mmAq.
Therefore, high level noise is measured outside the combustion device. Further, the flame 7 may backfire due to a rapid increase in pressure, and the combustor for a water heater may not operate normally.

In view of the above points, the present invention has an object to prevent the occurrence of Helmholtz type oscillating combustion, and to prevent noise and rapid pressure increase.

[0010]

The first means of the present invention is to:
In a combustor having a premixed air vent, a flame hole having a large number of flame holes downstream of the air vent, and a combustion chamber having the flame hole on the inlet side and a heat exchanger on the outlet side. An exhaust passage provided downstream of the heat exchanger, and an exhaust pipe having a hole smaller than the exhaust passage downstream of the exhaust passage, and a secondary air passage communicating with a secondary blower is provided with the exhaust passage and the exhaust passage. It connects to a space formed between the combustion chamber and the combustion chamber.

A second means is a premixed air vent passage, a flame hole portion having a large number of flame holes downstream of the air vent passage, the flame hole portion on the inlet side, and the heat exchanger on the outlet side. In a combustor having a provided combustion chamber, an exhaust passage provided downstream of the heat exchanger and an exhaust pipe having a hole smaller than the exhaust passage downstream of the exhaust passage are provided, and the exhaust pipe blower is used as an exhaust pipe. To connect.

[0012]

According to the first aspect of the present invention, the combustion gas is discharged to the outside of the combustion device by supplying the secondary air to the space formed between the exhaust passage and the combustion chamber after the primary combustion is completed. Without doing so, the pressure in the combustion chamber is released from the secondary blower to prevent the pressure in the combustion chamber from rising, thereby preventing oscillatory combustion.

According to the second means of the present invention, by supplying the excess air to the exhaust stack, the movement of the plug flow in the exhaust stack is prevented without releasing the combustion gas to the outside of the combustion apparatus, and the oscillatory combustion is performed. Is to prevent.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram of a hot water supply combustor according to a first embodiment of the present invention. In addition to the constituent elements described in the prior art, the following constituent elements are newly added. In FIG. 1, reference numerals 14, 17 and 19 denote secondary blowers communicating with the secondary air passages 15, 16 and 18.

This is for the purpose of preventing the occurrence of the Helmholtz type oscillatory combustion, as shown in FIG. 1, the combustion chamber 9, the heat exchanger.
11 or a secondary blower that supplies secondary air to the exhaust path 12
14, 17, and 19 are provided. This prevents a rapid pressure increase in the portion corresponding to the volume element during oscillating combustion, and oscillating combustion ceases.

If the transfer of energy between the potential energy due to the increase in pressure in the volume element and the kinetic energy of the combustion gas flowing in the pipe element is obstructed,
Helmholtz type oscillatory combustion is prevented. Here, if the pressure increase in the portion corresponding to the volume element is prevented, the potential energy cannot be stored, and thus the energy transfer is hindered.

If a secondary air passage 15 for supplying secondary air to the combustion chamber 9 and a secondary blower 14 communicating with the secondary air passage 15 are provided, even if the pressure of the portion corresponding to the volume element suddenly rises,
Through the secondary blower 14, the expansion of the combustion gas in the combustion chamber 9 is released to the atmosphere, and the pressure increase in the portion corresponding to the volume element can be prevented.

Further, since the pressure is applied by the secondary blower 14, the combustion gas 10 is not discharged to the atmosphere through this. The secondary air is also used as combustion air,
Promotes complete combustion. The secondary blower 14 has a secondary air passage 15
Is connected, which serves to prevent the combustion gas 10 from flowing out of the secondary blower 14 when a pressure rise occurs in the combustion chamber 9.

If the heat exchanger 11 is provided with the secondary air passage 16 for supplying the secondary air and the secondary blower 17 communicating with the secondary air passage 16, the oscillatory combustion is prevented and the temperature rise of the heat exchanger 11 is prevented. It has the function of extending the life of the exchanger.

When the exhaust passage 12 is provided with a secondary air passage 18 for supplying secondary air and a secondary blower 19 communicating with the secondary air passage 18, the temperature of the exhaust gas is lowered, and the temperature of the exhaust gas flowing into the exhaust stack 13 is changed to atmospheric air. It approaches the temperature and becomes constant regardless of the combustion conditions. The Helmholtz frequency is determined by the speed of sound in the stack 13, which is a function of temperature. When the temperature of the exhaust gas passing through the exhaust pipe 13 becomes constant, the speed of sound also becomes constant. as a result,
Since the Helmholtz frequency becomes constant, it becomes easy to prevent oscillatory combustion.

The secondary blowers 14, 17, and 19 may be installed in only one of the combustion chamber 9, the heat exchanger 11, and the exhaust passage 12, or two of them may be installed, or all three of them may be installed. It may be installed in. Further, one secondary blower 14 is provided, and one or two of the combustion chamber 9, the heat exchanger 11 and the exhaust passage 12 are provided by separately providing a flow path,
Furthermore, even if air is supplied to all three, the effect of the present invention is not impaired.

FIG. 2 is a block diagram of a hot water supply combustor according to a second embodiment of the present invention. As shown in FIG. 2, this is an exhaust pipe blower 20 for supplying excess air to the exhaust pipe 13. It is provided. As a result, the movement of the plug flow at the portion corresponding to the pipe element during oscillating combustion is impeded, and oscillating combustion is stopped.

If it is possible to prevent the transfer of energy between the potential energy due to the increase in pressure in the volume element and the kinetic energy of the combustion gas flowing in the pipe element,
Helmholtz type oscillatory combustion is prevented. During oscillation, when the potential energy increases, the movement of the plug flow moves in the direction of increasing the potential energy, that is, from the pipe element to the volume element. Here, if a force is externally forcibly applied to the portion corresponding to the pipe element to facilitate the movement of the plug flow of the internal fluid from the volume element to the pipe element, the energy from the kinetic energy to the potential energy is changed. Helmholtz type oscillating combustion is prevented because delivery is hindered.

At the time of Helmholtz type oscillatory combustion, the exhaust stack 13
Inside, the combustion gas operates as a plug flow. Exhaust stack 13
When the exhaust stack blower 20 for supplying excess air is provided in, the movement of the combustion gas 10 moving from the exhaust passage 12 toward the exhaust stack 13 is accelerated. Therefore, it becomes difficult to move from the exhaust pipe 13 to the exhaust passage 12. Therefore, the conversion of the portion corresponding to the volume element into potential energy is hindered, and oscillating combustion is prevented. Since the pressure is applied by the exhaust stack blower 20, the combustion gas 10 is not discharged to the outside through the exhaust stack blower 20.

Although each of the above embodiments has been described with respect to the hot water supply combustor, the same effect can be observed in the hot air heat exchanger and other heating heat exchangers.

[0027]

As described above, the hot water supply combustor of the present invention is capable of preventing oscillatory combustion by preventing a momentary pressure increase in the combustion chamber, the heat exchanger, or the exhaust passage. . In addition, the vibration combustion can be prevented by changing the movement of the combustion gas in the exhaust stack.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a hot water supply combustor according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a hot water supply combustor according to a second embodiment of the present invention.

[Explanation of symbols]

1 ... Primary blower, 2 ... Fuel flow supply path, 3 ... Mixing chamber,
4 ... Premixture, 5 ... Ventilation passage, 6 ... Flame hole, 7 ... Flame, 8 ... Flame hole portion, 9 ... Combustion chamber, 10 ... Combustion gas,
11 ... Heat exchanger, 12 ... Exhaust passage, 13 ... Exhaust pipe, 14, 1
7, 19… Secondary blower, 15, 16, 18… Secondary air passage, 20
… Exhaust stack blower.

Claims (2)

[Claims] 1. A combustion chamber having a premixed air vent passage, a flame hole portion having a large number of flame holes downstream of the air vent passage, the flame hole portion on the inlet side, and a heat exchanger on the outlet side. In a combustor having, an exhaust passage provided downstream of the heat exchanger, an exhaust pipe having a hole smaller than the exhaust passage downstream of the exhaust passage, and a secondary air passage communicating with a secondary blower, A hot-water supply combustor connected to a space defined between the exhaust passage and the combustion chamber. 2. A combustion chamber having a premixed air vent passage, a flame hole portion having a large number of flame holes downstream of the air vent passage, the flame hole portion on the inlet side, and a heat exchanger on the outlet side. A combustor having an exhaust passage provided downstream of the heat exchanger, and an exhaust pipe having a hole smaller than the exhaust passage downstream of the exhaust passage, and an exhaust pipe blower connected to the exhaust pipe. Combustor for hot water supply.