CN112682779A - Flat burner - Google Patents

Abstract

The invention provides a flat burner long in the front-back direction, which is provided with a main flame port (63) at the upper end and a side flame port (64) at least at one side position of the main flame port (63) in the transverse direction, and uses hydrogen-containing fuel as fuel, and can prevent: tempering at the side flame port with the slower gas ejection speed. And is ejected from the main flame port (63): the mixed gas of fuel and air with the fuel concentration leaner than the theoretical air-fuel ratio is ejected from the side flame hole (64) only by the following steps: the gas of the fuel. The height of the upper end of the side flame hole (64) on the side of the main flame hole (63) is set as follows: lower than the height of the upper end of the main flame port (63).

Description

Flat burner

Technical Field

The present invention relates to a flat burner using a hydrogen-containing fuel as a fuel.

Background

Conventionally, as a flat burner long in the front-rear direction, a main flame port and a side flame port located at least at one side in the lateral direction of the main flame port are provided at the upper end, and a fuel containing a hydrocarbon such as methane or propane as a main component is used as the fuel. And, from the main flame port, squirts: the mixed gas (lean mixed gas) of fuel and air, the fuel concentration of which is leaner than the stoichiometric air-fuel ratio, is reduced by excess air contained in the lean mixed gas: the temperature of the main flame generated by the combustion of the light mixed gas reduces the amount of NOx generated. In addition, the side flame port ejects: a small amount of a mixed gas of fuel and air (rich mixed gas) having a fuel concentration richer than the stoichiometric air-fuel ratio is used to hold the main flame by a side fire generated by combustion of the rich mixed gas (for example, see patent document 1).

However, recently, proposals have been made to utilize renewable energy sources in order to cope with the global warming problem, and it is predicted that power generation facilities using wind power or solar energy will also increase, and a large amount of surplus power will be generated. Therefore, countermeasures against the surplus power need to be taken. As one of the countermeasures, the following countermeasures are conceivable: excess power is converted into hydrogen and stored, and the hydrogen is injected into the gas line, whereby fuel supply is performed as a hydrogen-containing fuel capable of reducing CO2 emission.

Here, in the flat burner, the following disadvantages occur in that a fuel containing hydrogen is used as the fuel. That is, the hydrogen-containing fuel burns at a very high speed, and is liable to cause backfire at a side flame port where the gas ejection speed is slow.

Patent document 1: japanese laid-open patent publication No. 10-288315

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide a flat burner that uses a hydrogen-containing fuel as a fuel and can prevent backfiring at a side flame port.

In order to solve the above-described problems, the present invention is a flat burner long in a front-rear direction, including a main flame port and a side flame port located at least on one side in a lateral direction of the main flame port at an upper end thereof, and using a hydrogen-containing fuel as a fuel, wherein: a mixed gas (lean mixed gas) of fuel and air, the fuel concentration of which is leaner than the stoichiometric air-fuel ratio, is ejected from the side flame ports only by: the gas of the fuel.

According to the present invention, since only the gas of the fuel is ejected from the side flame ports, the side flames formed in the side flame ports constitute diffusion flames. Further, the mixed gas of the theoretical air-fuel ratio (mixed gas in which the excess air in the light mixed gas jetted from the main flame ports and the fuel jetted from the side flame ports are mixed) having the fastest combustion speed and the highest temperature, which is present between the main flame and the side flame due to the combustion of the light mixed gas jetted from the main flame ports, can cause a combustion reaction, and the region in which the combustion reaction occurs can be made to be: a position considerably distant from the upper end of the side flame ports. As a result, the temperature rise at the upper end of the side flame ports can be suppressed, and the backfire can be prevented.

In the present invention, the height of the upper end of the side flame ports on the main flame port side is preferably set to: lower than the height of the upper end of the main flame ports. Accordingly, the excess air in the lean mixture gas discharged from the main flame ports is mixed with the fuel discharged from the side flame ports, and the mixing is started at a position away from the upper end of the side flame ports on the main flame port side, and away from: the distance corresponding to the height difference between the side flame ports and the main flame ports. Therefore, the region in which the mixture gas of the stoichiometric air-fuel ratio existing between the main flame and the side flame is burned can be made further away from the upper end of the side flame ports on the main flame port side, so that the reliability of preventing flashback is improved.

Drawings

Fig. 1 is a sectional side view of a combustion apparatus including a flat burner according to an embodiment of the present invention.

Fig. 2 is a perspective view of the flat burner of the embodiment.

Fig. 3 is a perspective view of the flat burner of the embodiment in an exploded state.

Fig. 4 is a sectional view taken along line IV-IV in fig. 2.

Description of the reference numerals

6 … flat burner, 63 … main flame ports, 64 … side flame ports.

Detailed Description

Referring to fig. 1, reference numeral 1 denotes a combustion case constituting a combustion apparatus such as a heat source unit for hot water supply. The upper surface of the combustion casing 1 is open, and an object to be heated such as a heat exchanger not shown is disposed above the combustion casing 1. A partition plate 4 is provided in the combustion casing 1, and the partition plate 4 partitions a space in the combustion casing 1 into a combustion chamber 2 and an air supply chamber 3 below the combustion chamber. A fan outside the drawing is connected to the bottom surface of air supply chamber 3 via duct 5, and air is supplied from the fan to air supply chamber 3. The partition plate 4 has a plurality of distribution holes 4a, and the air supplied to the air supply chamber 3 is supplied as secondary air to the combustion chamber 2 through the distribution holes 4 a.

In the combustion chamber 2, a plurality of flat burners 6, which are long in the front-rear direction, are arranged in the lateral direction. A rising portion 41 is formed by bending the front edge of the partition plate 4, and a manifold 7 is attached to the front side of the rising portion 41 so as to close the lower front surface of the combustion casing 1. The manifold 7 is provided with: the gas nozzles 71 and 72 face the inflow ports 65a and 67a of the inflow duct portions 65 and 67 described later of the flat burners 6.

Referring to fig. 2 to 4, the flat burner 6 according to the embodiment of the present invention includes: a burner main body 61 that is long in the front-rear direction, and a burner cover 62 that covers the upper portion of the burner main body 61. The burner main body 61 is provided at its upper end with: a main flame port 63 opened at the upper side and having an elongated shape. Further, via the burner cover 62, there are provided: and side flame ports 64 located at both lateral sides of the main flame port 63.

The burner body 61 is formed of a pair of laterally opposed side plates 61a, 61 a. The both side plates 61a and 61a are formed by folding one plate in a closed state by a folding line which becomes a lower edge of the burner main body 61. Further, the burner main body 61 is formed with: an upper main flame port 63, a lower main flame inflow pipe portion 65, and a distribution chamber portion 66 for guiding gas from the inflow pipe portion 65 to the main flame port 63.

The main flame inflow pipe portion 65 extends rearward from an inflow port 65a located at the lower front end of the burner main body 61. The distribution chamber 66 extends upward while spreading forward from the rear end of the main flame inflow pipe 65. Further, a side flame inflow pipe portion 67 is formed in the front portion of the burner main body 61 so as to be positioned between the main flame inflow pipe portion 65 and the distribution chamber portion 66. The side fire inflow pipe portion 67 is formed to extend slightly rearward from an inflow port 67a located at the front end of the burner main body 61 and has a vent hole 67b opened in the rear end side surface thereof.

The combustor cover 62 has: a pair of side plates 62a, 62a that cover the outer sides of the pair of side plates 61a, 61a of the burner main body 61; and bridge portions 62b at a plurality of positions in the front-rear direction, which connect the side plates 62a, 62a at the upper edges of the side plates 62a, 62 a. Further, between the side plate 61a of the burner main body 61 and the side plate 62a of the burner cover 62, there are defined: the side flame ports 64 at the upper end, and a passage for guiding the gas flowing out from the side flame inflow pipe portion 67 to the outside of the burner main body 1 through the vent hole 67b to the side flame ports 64. Further, recesses 62c are formed at a plurality of positions in the front-rear direction corresponding to the bridge portions 62b of the side plate 62a of the burner cover 62, and the recesses 62c abut against the outer side surface of the side plate 61a of the burner main body 61 and partition the side flame ports 64 in the front-rear direction.

Further, a flow regulating member 68 is mounted in the main flame port 63, and the flow regulating member 68 includes: a plurality of rectifying plates 68a arranged in a lateral direction. In the rectifying member 68, contact portions 68b are formed at a plurality of positions in the front-rear direction that coincide with the bridge portions 62b of the burner cover 62, and the contact portions 68b cause the rectifying plates 68a to contact each other and partition the flame port flow path defined between the rectifying plates 68a in the front-rear direction. Further, at an upper portion of the side plate 61a of the burner main body 61, there are formed: and a recess 63a that is long in the front-rear direction and abuts against the outer surface of the rectifying member 68. Further, between the portion of the side plate 61a above the recess 63a and the flow straightening member 68, there are defined: blind slits 63b not ejecting gas; a part of the gas ejected from the main flame ports 63 flows back toward the blind slit 63 b.

Here, the flat burner 6 of the present embodiment uses a hydrogen-containing fuel as a fuel. However, the hydrogen-containing fuel burns at a very high rate, and is liable to cause backfire at the side flame ports 64 where the gas ejection speed is slow.

Therefore, in the present embodiment, the main flame ports 63 eject: a mixed gas (lean mixed gas) of fuel and air whose fuel concentration is leaner than the stoichiometric air-fuel ratio, for example, a lean mixed gas whose air excess ratio is 2.0 or more, is ejected from the side flame ports 64 only: the gas of the fuel. Referring to fig. 1, the fuel injected from the main flame gas nozzle 71 facing the inlet 65a of the main flame inflow pipe portion 65 flows into the inlet 65a, the air flows into the inlet 65a, and the light mixed gas generated by mixing the fuel and the air is ejected from the main flame port 63. Further, a shielding cylinder 69a is provided so as to protrude from the baffle 69 that overlaps the front surface of the rising portion 41 at the front edge of the partition plate 4, and the front end portion of the side fire gas nozzle 72 is fitted into the shielding cylinder 69a so that air does not flow into the inlet 67a of the side fire inflow pipe portion 7. Therefore, only the fuel injected from the side flame gas nozzle 72 flows to the inlet 67a of the side flame inflow pipe portion 67, and only the gas of the fuel is injected from the side flame ports 64.

If the air excess ratio of the lean mixture gas is 2.0 or more, the flame (main flame) is formed at a position sufficiently distant from the upper end of the main flame ports 63 even for the hydrogen-containing fuel having a high combustion speed, and thus the temperature rise at the upper end of the main flame ports 63 can be suppressed, and the back fire at the main flame ports 63 can be prevented.

Further, since only the gas of the fuel is ejected from the side flame ports 64, the side flame formed in the side flame ports 64 is: the excess air in the light mixed gas discharged from the main flame ports 63 and the secondary air around the side flame ports 64 are mixed with the fuel discharged from the side flame ports 64, and the mixed gas is burned to form diffusion flames. Further, the mixed gas having the theoretical air-fuel ratio, which has the highest combustion speed and the highest temperature between the main flame and the side flame formed by burning the light mixed gas ejected from the main flame port 63, generates a combustion reaction, and the region where the combustion reaction occurs can be made to be: a position considerably distant from the upper end of the side flame ports 64. As a result, the temperature rise at the upper end of the side fire vents 64 can be suppressed, and backfire can be prevented.

In the present embodiment, the height of the upper end of the side flame ports 64 on the side of the main flame ports 63 (which corresponds to the height of the upper end of the side plate 61a of the burner main body 61) is set as follows: lower than the height of the upper end of the main flame ports 63 (corresponding to the height of the upper end of the rectifying member 68). Accordingly, the excess air in the lean mixture gas discharged from the main flame ports 63 is mixed with the fuel discharged from the side flame ports 64, and the mixing is started at a position away from the upper end of the side flame ports 64 on the side of the main flame ports 63, and away from: a distance corresponding to a difference in height between the side flame ports 64 and the main flame ports 63. Therefore, the region in which the mixture gas of the stoichiometric air-fuel ratio existing between the main flame and the side flame is burned can be further separated from the upper end of the side flame ports 64 on the main flame port 63 side, and the reliability of preventing flashback can be improved.

The embodiments of the present invention have been described above with reference to the drawings, but the present invention is not limited thereto. For example, in the above embodiment, the height of the upper end of the side flame ports 64 on the side opposite to the main flame ports 63 (which coincides with the height of the upper end of the side plate 62a of the burner cover 62) is set to: the height of the upper end of the side flame ports 64 on the side of the main flame ports 63 is higher than the height of the upper end of the main flame ports 63, and is slightly lower than the height of the upper end of the main flame ports 63. That is, the height of the upper end of the side flame ports 64 on the side opposite to the main flame ports 63 may be set as follows: the height of the upper end of the side flame ports 64 on the side of the main flame ports 63 is equal to or equal to the height of the upper end of the main flame ports 63. In short, the height of the upper end of the side flame ports 64 on the side opposite to the main flame ports 63 may be greater than or equal to the height of the upper end of the side flame ports 64 on the side of the main flame ports 63 and less than or equal to the height of the upper end of the main flame ports 63. Further, the flat burner 6 of the above embodiment is provided with the side flame ports 64 on both lateral sides of the main flame port 63, but may be provided with the side flame ports only on one lateral side of the main flame port. The hydrogen-containing fuel may or may not contain components other than hydrogen.

Claims (2)

1. A flat burner, which is a burner having a longitudinal direction in a front-rear direction, is provided with: a main flame hole, and a side flame hole located at least at one side position in the lateral direction of the main flame hole, and using a fuel containing hydrogen as a fuel,

and (3) spraying from a main flame port: the mixed gas of fuel and air whose fuel concentration is leaner than the theoretical air-fuel ratio is ejected from the side flame port only by: the gas of the fuel.

2. The flat burner as claimed in claim 1,

the height of the upper end of the main flame port side of the side flame port is set as follows: lower than the height of the upper end of the main flame ports.

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