JPH0652123B2 - Burner - Google Patents

Description

TECHNICAL FIELD The present invention relates to an industrial / commercial or household low NO _X burner.

2. Description of the Related Art Conventionally, a burner utilizing complete premixed combustion has been used as a low NO _X burner. For example, as shown in FIG.
The wire mesh 2 is attached to a part of the burner head 20 including the burner wall 21.
3 was provided and the fuel 22 supplied to the burner head was ignited on the surface of the wire mesh to form the flame 24.

Such burners burn the fuel with excess air, and further radiate the heat received from the flame from the wire net, thereby lowering the flame temperature and reducing NO _X emissions.

Problems to be Solved by the Invention However, when the combustion amount is large, or when the excess air ratio approaches 1, the wire mesh suddenly rises in temperature and a flashback often occurs, or the wire mesh is oxidized due to high temperature. do it,
There was a problem with durability. On the other hand, increase the amount of premixed air,
When the excess air ratio was increased or the amount of fuel was increased to increase the flow velocity of fuel, the flame became unstable, and unburned gas was often discharged or blown off. As a result, the variable range of the combustion amount and the air amount is small, which causes practical inconvenience.

In addition, heat is radiated from the wire mesh to the upstream side, that is, to the combustion chamber, and heats the fuel. As a result, the flame temperature was low and the NO _X was low.

Means for Solving the Problems The present invention provides a burner which emits a small amount of NO _X and has good flame stability and durability.

A combustion chamber is formed by the combustion chamber wall and the combustion chamber outlet. A plurality of flame hole groups arranged at a substantially constant distance are provided on the wall of the combustion chamber and face each other. The flame holes in the flame hole group are formed by continuously bending thin plates and combining them with flat plates. It is desirable that this flame hole be within the quenching distance. This group of flame holes is located at the outlet of the fuel supply passage provided on the wall of the combustion chamber. The fuel supply passage is provided outside the combustion chamber. A plurality of flame hole groups are arranged in the exit direction of the combustion chamber. It is preferable to burn the fuel in a region where the excess air ratio M is large.

Action In such a burner, excess air causes the flames to burn facing each other even if they are separated from the flame holes. Therefore, it is possible to burn in a region where the amount of air is large, and it is difficult to blow off even when the amount of combustion is large. In particular, the flame formed in the flame hole near the outlet of the combustion chamber is preheated by the high temperature exhaust gas in the upstream region and thus has good stability.

In addition to the ease of heat dissipation from the flame due to the dispersion of the flame, the heat dissipation from the combustion chamber wall and the fuel supply path as well as the thin plates forming the flame hole group make the flame holes near the flame red and radiate. The heat from the flame to the upstream through conduction through the NO _X
Is being reduced. Especially when the combustion amount is small, the flame approaches the flame hole and heats the flame hole.However, since the heat capacity of the flame hole is small and the heat conduction amount is small, the temperature at the upper end of the flame hole rises and the flame is maintained and excess air is generated. NO _X even where the rate is small
Can be reduced.

Embodiment FIG. 1 is a configuration diagram of an embodiment of the present invention, in which 1 is a vaporization chamber, 2 is a distribution pipe, 3 is a fuel supply passage, 4 is a flame hole group, 5 is a flame hole, and 6 is a flame hole plate. , 7 is a flame hole partition plate, 8 is a combustion chamber, 9 is a combustion chamber wall, 10 is a combustion chamber outlet, 11 is a cooling passage, and 12 is a blower pipe.

FIG. 2 is a vertical sectional view of FIG. 13 is a fuel nozzle, 14 is a blower, 15 is fuel, 16 is a mixture, and 17 is a heater.

The fuel 15 is introduced into the vaporization chamber 1 from the fuel nozzle 13. The vaporization chamber 1 is made of aluminum die cast and is a heater 1.
Since 7 is embedded and heated to 200 to 300 ° C., the fuel 15 supplied to the vaporization chamber 1 is vaporized. On the other hand, the combustion air is introduced into the vaporization chamber 1 from the blower 14 via the blower pipe 12, and is mixed with the vaporized fuel 15 to form the air-fuel mixture 16. The air-fuel mixture 16 is introduced into the combustion chamber 8 from the flame hole 5 at the light end through the distribution pipe 2 and a number of fuel supply passages 3 provided in the distribution pipe 2. The fuel supply passage 3 has an elongated cylindrical structure, and a flame hole group 4 having a large number of flame holes 5 is formed therein by a flame hole plate 6 and a flame hole partition plate 7 on the combustion chamber 8 side. When the mixture 16 introduced into the combustion chamber 8 through the flame holes 5 is ignited, a flame 18 is formed. When a gaseous fuel is used instead of the liquid fuel 15, the vaporization chamber 1 can be omitted to perform the same combustion.

The flame hole groups 4 are opposed to each other through the combustion chamber 8 to form a pair, and a large number of the flame hole groups 4 are arranged on the combustion chamber wall 9 at a substantially constant distance. The fuel supply passage 3 also corresponds to the flame hole group 4 and is arranged outside the combustion chamber wall 9. The fuel supply passages 3 are arranged in groups between the combustion chamber wall 9 and the distribution pipe 2 to form a cooling passage 11. Air passes through the cooling passage 11 to cool the combustion chamber wall 9 and the fuel supply passage 3. Further, the radiant heat from the combustion chamber wall 9 and the fuel supply passage 3 can be radiated to the outside.

A large number of flames 18 are formed in the combustion chamber 8, and the heat generated by the flames 18 heats the combustion chamber wall 9, the flame hole plate 6 and the flame hole partition plate 7 to heat the fuel supply passage 3 as well. Then, a part of the heat is radiated from the combustion chamber wall 9 and the fuel supply passage 3, and a part of the heat is heated to the flame hole plate 6 and the flame hole partition plate 7 to be radiated as radiant heat and heat is also given to the mixture. In this way, the flame temperature is reduced, and the NO _X contained in the exhaust gas 19 is reduced.

Combustion chamber wall 9, fuel supply passage 3, flame hole plate 6, flame hole partition plate 7
Uses a heat-resistant material such as stainless steel to facilitate heat radiation due to radiation at high temperatures.

The outside of the combustion chamber wall 9 heated by the flame 18 is a cooling passage 11, and cooling air passes therethrough to cool the combustion chamber wall 9 to indirectly cool the flame and to cool and mix the fuel supply passage 3. Prevents overheating of the air.

Further, when the flame holes are grouped in this way, the central portion tends to have a high temperature, but by forming the flame hole plate 6 and the flame hole partition plate 7 as a continuous thin plate, the heat transfer is smoothed and local heating is performed. Prevents stable combustion.

Further, by using a thin plate and making the depth of the flame hole 5 long, the temperature gradient becomes large and the flashback can be prevented. In this case, the ratio of plate thickness to length may be 100 or more. It goes without saying that the flame hole 5 is preferably as small as possible.

The present invention is characterized by forming an opposing flame, which will be described in detail below.

FIG. 3 shows the form of the opposing flame. 26 is unburned gas, 26
Is the end of the oncoming flame. A is the flame 18 'attached to the flame hole
Is. In B, the flame is forming an opposing flame 18 ″ away from the flame hole. In B, the opposing flames are not on the same axis, so that the opposing flame cannot be formed, or If one is removed, the flame will blow off and stable combustion will not be possible.If the outlet flow velocity V of the air-fuel mixture is S and the combustion speed is S, the opposing flame can be stably combusted in a large V / S region. When the 18 ″ is formed away from the flame hole 5, the end 27 of the opposing flame 18 ″
The unburned gas 26 is discharged from the. At this time, the distance between the end portion 27 and the flame hole 5 increases as V / S increases, and the amount of unburned gas 26 also increases. As shown in FIGS. 1 and 2, the unburned gas is oxidized by the flame downstream because a large number of flame hole groups 4 are arranged and are further shielded from the combustion chamber wall 9 and the outside. At this time, the flame near the downstream combustion chamber outlet 10 increases stability because the high temperature gas due to the upstream flame heats the mixture 16 and the flame hole group of the combustion chamber outlet 10, and V / S is remarkably higher than that on the upstream side. Get smaller.

When the adjacent flame hole groups 4 approach each other, the adjacent flames interfere with each other and the flame becomes unstable. Therefore, it is desirable that each flame hole group has at least one gap.

In FIG. 3A, the flame 18 ′ adheres to the flame hole 5 when V / S becomes smaller. In this case, the flame 18 'ends facing the flame front to be composed of a thin plate for heating the burner ports plate 6 and the burner port partition plate 7 is red hot, reducing the radiate radiant heat NO _X.

When V / S becomes smaller, the flame 18 'tries to enter the flame hole 5, but since the flame hole plate 6 and the flame hole partition plate are made of a material thin enough to prevent the movement of heat, the temperature The gradient is large on the combustion chamber 8 side and the fuel supply path 3 side, and the flame is cooled and there is no flashback. Further, since the fuel supply passage 3 is also arranged in the cooling passage 11, cooling by air can be expected sufficiently. Further, since the flame hole plate 6 is formed by a continuous thin plate, a local high temperature portion does not occur.

If the amount of combustion is further reduced, the flame is extinguished, but the heat capacity of the flame hole 5 is small, and the flame hole plate and the flame hole partition plate slightly heat the co-flowing mixture, so that the flame extinguishing region becomes small.

EFFECTS OF THE INVENTION The burner of the present invention is advantageous in that a large number of opposed flames are formed in the combustion chamber by the flame hole group formed of thin plates, and a plurality of them are arranged in the combustion chamber outlet direction.

(1) Greatly reduces NO _X. In particular, it has a large reduction effect at a low excess air ratio such that an adhered flame is formed in the flame holes.

(2) The flame stability region becomes wider, especially in the region where the amount of combustion is small.

(3) Since it is a thin plate that is bent in the longitudinal direction to form flame holes, it has a large resistance to high temperature oxidation and can be used for a long life.

[Brief description of drawings]

FIG. 1 is a perspective view of a burner according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view thereof, FIG. 3 is a flame conceptual diagram of the burner, and FIG. 4 is a configuration diagram of a conventional burner. 4 ... Flame hole group, 5 ... Flame hole, 6 ... Flame hole plate, 7 ... Flame hole partition plate, 8 ... Combustion chamber, 9 ... Combustion chamber wall.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuo Fujita 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-63-127005 (JP, A)

Claims (3)

[Claims] 1. A combustion chamber is formed by a combustion chamber wall and a combustion chamber outlet, and a plurality of fuel supply passages having a plurality of flame hole groups having a large number of flame holes are arranged in the combustion chamber wall through a cooling passage. The burner characterized in that the flame hole in the fuel supply passage is formed by combining a continuously bent thin plate and flat plate. 2. The burner according to claim 1, wherein the thin plate forming the flame holes has a ratio of plate thickness to length of 100 or more. 3. The burner according to claim 1, wherein the fuel supply passages containing the group of flame holes are mutually provided at least at intervals of the width of the flame holes.