JP2653521B2 - Pulse burner - Google Patents

Description

Description: Object of the Invention (Industrial application field) The present invention relates to a pulse burner for reducing harmful exhaust gas in exhaust gas.

(Prior Art) A pulse burner is usually configured as shown in FIG. That is, a combustion chamber 1 that pulsatively burns a mixed gas of fuel and combustion air, a tail pipe 2 that exhausts combustion gas, an air supply pipe 3 that supplies air to the combustion chamber 1, and an air supply pipe 3, a nozzle-shaped flow control valve 4 whose forward flow coefficient is larger than the reverse flow coefficient, a fuel supply pipe 5 for supplying fuel to the combustion chamber 1, and a fuel supply pipe 5. A fuel control valve 6 for limiting the amount of fuel flowing into the combustion chamber 1 is provided, for example, a forward flow coefficient is larger than a reverse flow coefficient, and an ignition igniter 7
An exhaust decoupler 8 connected to the downstream side of the tail pipe 2;
Muffler 9 connected further downstream of exhaust decoupler 8
And a fan 10 connected upstream of the flow control valve 4 and a cooling pipe 11 for cooling the combustion chamber 1 and the tail pipe 2.

As is well known, such a pulse burner can increase the load on the combustion chamber 1 and has advantages such as high thermal efficiency and low harmful emissions (low NOx). Also,
For relatively large combustors for industrial and commercial use, or even for home use, the proportion of the low temperature boundary layer formed near the wall in the combustion chamber is smaller than the volume of the combustion chamber, The amount of unburned components such as CO generated by quenching of the reaction generated there was no problem because it was very small with respect to the entire exhaust gas amount.

However, in small combustors such as those used for home heaters, the proportion of the volume occupying the entire low-temperature temperature boundary layer is large, and the proportion of unburned fuel in the exhaust gas is large. Therefore, there was a limit to the miniaturization of the pulse burner, and it could not be applied to small combustors for home use, etc., and its use was delayed.

(Problems to be Solved by the Invention) When a conventional pulse burner is used for a small-sized combustor or the like, the ratio of unburned components such as CO in exhaust gas increases, and the concentration of the unburned portion decreases. As a result, the size of the pulse burner is limited, so that it cannot be applied to a small-sized combustor for home use or the like.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pulse burner that can be used in a small-sized combustor and can be reduced in size.

[Means for Solving the Problems] To achieve the above object, a pulse burner according to the present invention comprises a cylindrical combustion chamber having one end closed, and a cylinder near the closed end of the combustion chamber. A pulse comprising: a supply pipe connected to the peripheral wall in a tangent direction to supply fuel and combustion air into the combustion chamber by swirling; and a tail pipe and a radiator connected downstream of the combustion chamber. In the burner, a cylindrical thermal resistor is arranged along the inner wall inside the combustion chamber, and a pulsed combustion is performed by forming a swirling mixed gas flow of the fuel and the combustion air in the space inside the thermal resistor, It is characterized in that the cooling of the combustion chamber space due to the improvement of the heat transfer coefficient of the combustion chamber wall is suppressed, and the heat absorption of the atmosphere outside the combustion chamber is suppressed.

(Operation) In the configuration described above, the thermal resistor is arranged along the inner wall inside the combustion chamber. With this configuration, when the fuel and the combustion air are swirled and mixed in the combustion chamber, even if the heat transfer coefficient of the inner surface of the combustion chamber (the surface of the heat resistance body) is improved by the swirling flow, the wall surface of the combustion chamber is transferred by the action of the heat resistor. Since the improvement of the rate is prevented, the inner surface of the inner wall of the combustion chamber is cooled at the outer surface (atmosphere) temperature of the outer wall of the combustion chamber, thereby preventing the temperature from lowering. As a result, it is possible to prevent the mixed gas from being cooled.

Therefore, the combustion of the mixed gas can be completed on the upstream side of the combustion chamber, the flame in the pulsating combustion direction of the pulse burner can be shortened, and a stable flame can be formed. This has the effect of reducing the size of the combustion chamber and providing a burner with less unburned components.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a side sectional view of a pulse burner according to an embodiment of the present invention, with a part cut away. In the figure, the same parts as those in FIG. 3 are denoted by the same reference numerals.

That is, the pulse burner includes a combustion chamber 1 that pulsatively burns a mixed gas of fuel and combustion air, a tail pipe 2 that exhausts combustion gas, and an air supply pipe 3 that supplies air to the combustion chamber 1. A nozzle-shaped flow control valve 4 provided in the air supply pipe 3, for example, a flow coefficient in a forward direction is larger than a flow coefficient in a reverse direction; a fuel supply pipe 5 for supplying fuel to the combustion chamber 1; A fuel control valve 6 provided in the fuel supply pipe 5 for limiting the amount of fuel flowing into the combustion chamber 1, for example, a forward flow coefficient is larger than a reverse flow coefficient, an ignition igniter 7, and a tail An exhaust decoupler 8 connected downstream of the pipe 2, a muffler 9 connected further downstream of the exhaust decoupler 8, a fan 10 connected upstream of the flow control valve 4, a combustion chamber 1 and a tail pipe A cooling pipe 11 which is a heat radiating part for cooling the cooling pipe 2; And a thermal resistor 12 provided on the inner wall of the combustion chamber 1. In the figure, reference numeral 13 denotes a frame sensor.

Next, the operation of the pulse burner configured as described above will be described.

First, when a start command is given, the fan 10 is rotated at a low speed. When the fan 10 is started, air flows into the combustion chamber 1 via the air supply pipe 3 and the flow control valve 4, and prepurge is performed by this air flow. Next, the operation of the igniter 7 is started, the fuel control valve 6 is opened, and fuel is injected into the combustion chamber 1 through the fuel supply pipe 5.

The interior of the combustion chamber 1 is filled with a mixed gas of air and fuel, and is ignited by an igniter 7. At this time, the flame sensor 13 detects whether the mixed gas in the combustion chamber 1 is burning.

When the flame sensor 13 detects that the mixed gas in the combustion chamber 1 is burning, the fan 10 is rotated at a high speed,
More air is supplied to the combustion chamber 1. Therefore, in the combustion chamber 1, a larger amount of air is supplied than before the start of combustion, and stable pulse combustion is performed.

Even if the outer wall of the combustion chamber 1 is cooled by the cooling pipe 11, the thermal resistance 12 is provided on the inner wall of the combustion chamber 1, so that the temperature gradient of the inner wall of the combustion chamber 1 becomes large, and the temperature boundary at which the combustion gas comes into contact. The temperature in the bed increases.

When the temperature in the temperature boundary layer rises to 700 to 800 ° C. or higher, the quenching of the reaction near the wall of the combustion chamber 1 becomes extremely small, and the generation of unburned components such as CO in exhaust gas is suppressed ( The concentration of unburned matter becomes lower). Therefore, the size of the pulse burner can be reduced.

The heat resistor 12 is generally made of a heat-resistant metal or a heat-resistant ceramic, but a material having a small thermal conductivity has a greater effect.

Next, a pulse burner according to another embodiment of the present invention will be described with reference to FIG. 2 which is a cross-sectional view of a combustion chamber of a pulse burner according to another embodiment of the present invention. In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals.

The pulse burner includes a combustion chamber 1 that burns a mixed gas of fuel and combustion air in a pulsed manner, a tail pipe 2 that exhausts combustion gas, and an air supply pipe 3 that supplies air to the combustion chamber 1.
A nozzle-shaped flow control valve 4 provided in the air supply pipe 3, for example, having a forward flow coefficient larger than a reverse flow coefficient, and a fuel supply pipe 5 for supplying fuel to the combustion chamber 1.
A fuel control valve 6 provided in the fuel supply pipe 5 for limiting the amount of fuel flowing into the combustion chamber 1, for example, a forward flow coefficient is larger than a reverse flow coefficient, and an ignition igniter 7. An exhaust decoupler 8 connected downstream of the tailpipe 2, a muffler 9 connected further downstream of the exhaust decoupler 8, and a fan connected upstream of the flow control valve 4.
The combustion chamber 1 includes a cooling pipe 11 for cooling the combustion chamber 1 and the tail pipe 2, and a thermal resistor 12 provided on an inner wall of the combustion chamber 1.

The air supply pipe 3 is tangentially mounted on the upstream side of the cylindrical combustion chamber 1, and is connected to the thermal resistor 12 and the combustion chamber 1.
The air layer 14 is provided in a curve with the inner wall.

As described above, the air supply pipe 3 is attached to the upstream side of the cylindrical combustion chamber 1 so as to flow tangentially, so that the mixed gas of fuel and combustion air flows along the wall surface of the combustion chamber 1. And is more strongly affected by the temperature boundary layer. Therefore, the effect of the thermal resistor 12 appears more strongly. In addition, such a swirl type combustion chamber can improve the mixing property of air and fuel, and can stabilize a fire formed inside.

Further, an air layer 14 is provided between the thermal resistor 12 and the inner wall of the combustion chamber 1.
By providing, the thermal conductivity of air decreases,
Become a more effective thermal resistor. Therefore, the thermal resistor 12
Since the same effect can be obtained even if the thickness of
The size of the combustion chamber 1 can be made smaller.

4 and 5 are block diagrams of a pulse burner according to a modification of the present invention. The description of the same parts as those in the above-described embodiment will be omitted.

As shown in FIG. 4, a heat radiating portion for cooling the combustion chamber 1 and the tail pipe 2 of the pulse burner 20 is a cooling liquid 22 such as water in a container 21. Such a configuration may be employed. Further, as shown in FIG. 5, a heat radiating portion for cooling the combustion chamber 1 and the tail pipe 2 of the pulse burner 20 may be an air flow by the fan 23.

[Effects of the Invention] According to the present invention, even when the outer wall of the combustion chamber is cooled, the thermal resistor is provided on the inner wall of the combustion chamber.
Since a low-temperature boundary layer is not formed inside the combustion chamber and the generation of unburned components such as CO due to quenching of the reaction is suppressed, the pulse burner can be downsized.

[Brief description of the drawings]

FIG. 1 is a side cross-sectional view of a pulse burner according to one embodiment of the present invention, with a part cut away. FIG. 2 is a cross-sectional view of a pulse burner according to another embodiment of the present invention in a combustion chamber. FIG. 1 is a sectional side view of a conventional pulse burner with a part cut away, and FIGS. 4 and 5 are configuration diagrams of a pulse burner according to a modification of the present invention. DESCRIPTION OF SYMBOLS 1 ... Combustion chamber, 2 ... Tail pipe, 3 ... Air supply pipe, 4 ... Flow control valve, 5 ... Fuel supply pipe, 6 ... Fuel control valve, 7 ... Igniter, 8 ... Exhaust decoupler … 9… muffler, 10… fan, 11… cooling tube, 12… thermal resistor, 13… frame sensor, 14… air layer, 20… pulse burner, 21 …… container, 22 …… Coolant, 23 ... fan.

Claims (1)

(57) [Claims] A cylindrical combustion chamber having one end closed and a cylindrical peripheral wall near the closed end of the combustion chamber tangentially connected to supply a swirling fuel and combustion air into the combustion chamber. In each of the supply pipes, and a pulse burner composed of a tail pipe and a radiator connected downstream of the combustion chamber,
By arranging a cylindrical heat resistor along the inner wall inside the combustion chamber, and forming a swirling mixed gas flow of the fuel and the combustion air in the space inside the heat resistor to perform pulse combustion,
A pulse burner, which suppresses cooling of the combustion chamber space due to the improvement of the heat transfer coefficient of the combustion chamber wall, thereby suppressing heat absorption of the atmosphere outside the combustion chamber.