JPH03263503A - Low nitrogen oxide burner - Google Patents

Abstract

PURPOSE:To suppress the generation of NOx by providing a plurality of first passages which discharge gas-rich mixture gas and a plurality of second passages which discharge air-rich mixture gas and burning completely the unburned gas in the flame of the mixture gas which is discharged from the first passages by the surplus air in the flame of the mixture gas discharged from the second passages. CONSTITUTION:From first flame holes 11 and second flame holes 12 gas-rich mixture gas and air-rich mixture gas are respectively discharged. And the rarefied combustion flames that are formed above the second flame holes 12 are directed towards the flames which are formed above the second flame holes 12 and short of oxygen by means of baffle plates 12 so as to burn completely the unburned gas that is contained in the flames, and at the same time the rarefied combustion flames raise the flame temperature gradually by the shift of the air-fuel ratio substantially to the gas-rich side and they can be completely burned. With this constitution a gas burner 2 is capable of suppressing the generation of NOx by the flames of the gas-rich mixture gas and the flames of the air-rich mixture gas.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is applicable to low-N systems that generate less air oxides, such as water heaters and heating devices that burn the gas and oil vaporized residue.
Regarding Ox burner. 1. Prior Art] In recent years, in order to prevent environmental pollution, techniques for suppressing the generation of N(')x have been used in large gas appliances such as large boilers. This technology suppresses the generation of harmful NOx by suppressing the temperature of the flame. Typical technologies include multi-stage combustion technology that burns gas in multiple stages, exhaust gas recirculation technology that returns part of the exhaust gas to the combustion chamber, and concentrated combustion technology that burns a near-rich mixture and a gas-rich mixture. There are also known technologies such as steam mixing technology, or steam mixing technology, which involves mixing water vapor into a mixture and combusting it. [Problem to be Solved by the Invention 1] However, the conventional technology has a complicated and large structure. The present invention has been made in view of the above circumstances, and its purpose is to provide a small, low nitrogen oxide burner that can suppress the generation of NOx. [Means for Solving the Problems] In order to achieve the above object, the low nitrogen oxide burner of the present invention employs the following technical means. The gas burner includes a plurality of first passages that discharge a gas-rich mixture (preferably an excess air ratio of 0.8 or less) in which gas serving as fuel and primary air for combustion are mixed, and the plurality of first passages. In some parts, gas as a fuel and 1 for combustion are used.
A second passageway is provided for discharging a near-rich (preferably an excess air ratio of 1.4 or more) air-fuel mixture mixed with air. An example of six preferred embodiments will be described in which unburned gas from the flame of the mixture discharged from the first passage is completely combusted by surplus air from the flame of the mixture discharged from the second passage. The low nitrogen oxide burner is equipped with a baffle plate that directs the near-rich air-fuel mixture blown out from the second passage toward the flame formed by the air-fuel mixture blown out from the first passage 6 [Function] The air-fuel mixture discharged from the first passage Since there is a lack of oxygen, the flame of the air-fuel mixture discharged from the first passage generates unburned gas. On the other hand, since the mixture discharged from the second passage contains excess air, the flame of the mixture discharged from the second passage contains excess air. The unburned gas then reacts with excess air and is completely combusted. The operation of the embodiment will be briefly described. A part of the near-rich mixture blown out from the second passage,
Or all of it is directed by the baffle plate to the flame blown out from the first passage. The near-rich air-fuel mixture directed toward the flame by the baffle plate is heated by the flame, increasing the combustion rate, and mixes with the combustion gas and unburned gas in the flame, causing some of the excess air to mix with the unburned gas. match. As a result, the ignitability of the near-rich air-fuel mixture is improved. [Effect of the invention] The flame generated by the gas-rich mixture has a low temperature and low NOx.
It is. Furthermore, a flame caused by a near-rich mixture also has a low temperature and low NOx. As a result, the gas burner of the present invention can suppress the amount of NOx generated. In addition, because it has a simple structure that includes a first passage for discharging a gas-rich mixture and a second passage for discharging a near-rich mixture, the low NOx gas burner does not become large, and the low NOx gas burner can be provided at low cost. As a result, a combustion appliance with low NOx can be provided in a compact and inexpensive manner. The effect of the embodiment is that by providing the baffle plate, it is possible to reliably burn the flame of a near-rich mixture that is difficult to ignite or easily extinguished. [Example] Next, a description will be given based on an example in which the low nitrogen oxide burner of the present invention is applied to a domestic gas water heater. (Configuration of Embodiment) FIGS. 1 and 2 show a first embodiment, in which FIG. 1 is a sectional view of a gas burner, and FIG. 2 is a schematic sectional view of a gas water heater. The gas water heater 1 heats water flowing through a heat exchanger 3 using the heat of a flame formed by a gas burner 2. Further, the gas burner 2 is of a premix type and includes an air blower 115 and a gas supply means 6. In the gas burner 2, a plurality of first burner tubes 7 constituting the first passage of the present invention and a plurality of second burner tubes 8 constituting the second passage of the present invention are joined every other one, that is, alternately. It is a collective body. The first burner tube 7 and the second burner tube 8 are
A first inflow 1, which is a flat passage formed by joining stainless steel plates, into which fuel gas and combustion air flow into the upper end.
'9 and a second inflow 010. The first burner tube and the second burner tube 8 have a first flame 1 which discharges a mixture of gas and air supplied inside to the upper ends thereof.
] and a second flame [ ]12. 1st bar tube 7 and 2nd bar tube L.-
Air mixtures with different excess air ratios are supplied to the valve 8. - To give an example, the first burner, sub 7, is supplied with a mixture with an air excess ratio of 0.6-, -0.7 (gas ridge mixture), and the remaining second burner, sub 8 There is a system that supplies a mixture with an air excess ratio of 14 to 1- (hereinafter referred to as 1\near-rich mixture). On the other hand, at the upper part of the second flame ['']2 of the second burner tube 8, a near-rich air-fuel mixture that emerges from the second flame 1j], 2 is formed in the first flame ['']11 on both sides. The upper part of the second flame 1] 12 (the first flame []
A baffle plate 13 is provided to generate a vortex A between the flames formed in the flames 11).

【ing. This baffle plate 13 is bent into a dogleg shape in cross section 7-1. A part of the opening is provided along the second flame 1']2. The blower 5 includes a first burner duplex 7 and a second parser f.
- Forcibly feed combustion air only into the node 8. Incidentally, the residue supplied into the first burner tube 7 and the second burner tube 8 is combusted only with the air supplied by the blower 5 (premix combustion). The gas supply means 6 includes a gas supply passage 14 for supplying gas into each first versatility 1-7 and each second burner fx-g 8. The gas supply passage 14 is provided with two electromagnetic on-off valves 15, ]6, a cabana valve 1'7, and an electromagnetic proportional valve 18 on the -L flow side. In addition, the waste supply passage 14
On the 1ζ flow side, there is a first nostle 19 that transports waste into the first bar 4-ch, ]-b 7 and second burner tube 8.
OJ, Hi 2nd. Nosle 20 is installed. Note that the first nozzle 19 has a large opening diameter so that the air-fuel mixture guided into the first burner nozzle and L-bub 7 becomes gas-rich; is the second
The diameter of the opening 1 is set small so that the air-fuel mixture guided into the burner tube 8 becomes near-rich. In addition,
A method may be used in which the nozzle diameter is the same and the amount of air flowing in is adjusted using a restriction plate. The electric devices such as the two electromagnetic on-off valves 15, [6], electromagnetic proportional valve [8], blower 5, and sparker 21 are controlled by a control device (not shown). The control device 2 is a well-known device, and includes operation switches (not shown) (operation switch, hot water temperature setting switch, etc.) and multiple sensors (water flow sensor, hot water temperature sensor, etc.). Detects the usage state of
, the sparker 21, etc. (Operation and effects of the embodiment) Next, the flame formed in the gas burner 2 will be explained. When hot water supply starts, a gas-rich mixture is supplied into the first burner 7. At the same time, the near-ridge mixture is supplied into the second burner stove 8. Then, the gas-ridge mixture and the near-ridge mixture are forced out from the first flame 1] and the second flame L112, respectively. Since the gas ridge mixture discharged from flame 1 has an excess air ratio of 0.6 = 0.7, the first flame []]
1) Oxygen-deficient combustion is performed in ]. As a result, the first flame “
] 11, an oxygen-deficient flame is formed. In addition, the near-ridge mixture discharged from the second flame 012 has an excess air ratio of 14 or more, and the lean combustion is 1j.
cormorant. Furthermore, the lean combustion flame formed at the second flame D ], 2 +- is caused by the baffle plate 134:''' to
The TL formed at 1 is directed to the oxygen queen flame, so that a part of the overstimulated air in the lean combustion flame reacts with the unburned gas in the oxygen-deficient combustion flame, resulting in the combustion of the unburnt gas. It is consumed. As a result, the unburned gas contained in the oxygen-deficient flame is completely combusted, and the air-fuel ratio of the 1A rich mixture is substantially transferred to the gas January Sochi side. , ]-γ Refrich gas increases the combustion speed, but in contrast, the air-fuel ratio gradually increases as the air-fuel ratio shifts to the gas-rich side, gradually raising the flame temperature and reducing the combustion rate in the lean combustion flame. The combustion gas can be completely combusted. On the other hand, a vortex A is generated downstream of the baffle plate 13 due to a jet of gas-rich mixture, a jet of a near-rich mixture, etc. It guides the gas to the base of each flame, mixes combustion gas into the flame, and works to reduce the combustion speed of the flame. (Effect of Example) The flame caused by the gas-rich mixture has a low temperature and low NOx. In addition, the flame caused by the near-rich mixture also has a low temperature and low NOx.Then, in the gas burner 2 of this embodiment, combustion is performed by the flame of this gas-rich mixture and the flame caused by the near-rich mixture. , the amount of NOx generated can be suppressed. By providing the baffle plate 1.3, the excess air ratio can be reduced to 14
Both the above-mentioned near-rich mixture and the gas-rich mixture of 08 or less can be reliably combusted. In addition, since the exhaust gas is circulated by the vortex A formed downstream of the buckle plate 13, the temperature rise rate of the flame of the gas-rich mixture and the flame of the near-rich mixture can be further slowed down, and NOx can further reduce the amount of generation. Since the gas burner 2 has a simple structure in which a plurality of passages are provided by joining the first burner tube 7 and the second burner tube 8, the low NOx gas burner 2 does not become large in size, and the low NOx gas burner 2 can be Can be provided at low cost. As a result, the gas water heater 1 with low NOx can be provided compactly and at low cost. FIG. 3 shows a sectional view of the main parts of the gas burner 2 of the second embodiment. In this embodiment, in the first burner tube 7 and the second burner tube 8, the first burner port 11 is provided at a lower position than the second burner port 12. The upper end of the second burner tube 8 is formed into a mountain shape, and the second burner ports 12 are provided on both slopes of the upper end of the second burner tube 8, respectively. The lean combustion flame formed by the second burner port 12 is directed above the oxygen-deficient flame formed at the first burner port 11 . Then, the excess oxygen in the lean combustion flame and the unburned gas in the oxygen-deficient flame react, the temperature of the entire flame rises, and the unburnt gas in the lean combustion flame is also completely combusted. As a result, even in this embodiment in which the baffle plate (see the first embodiment) is eliminated, a near-rich mixture with a high excess air ratio and a gas-rich mixture with a low excess air ratio can be reliably combusted. (Modified Example) In this example, multiple burner tubes are joined to form multiple passages, but the burner body may be constructed using other structures, such as forming multiple passages by providing multiple partition walls within the case. It may be provided. Although an example in which the present invention is applied to a gas water heater has been shown, the present invention may also be applied to a gas burner of other gas combustion devices such as a gas heating device or a cooking appliance. Alternatively, the present invention may be applied to a burner that uses petroleum as fuel and burns the petroleum by vaporizing (gasifying) it.

[Brief explanation of drawings]

1 and 2 show a first embodiment, in which FIG. 1 is a sectional view of a gas burner, and FIG. 2 is a schematic sectional view of a gas water heater. FIG. 3 is a sectional view of a gas burner showing a second embodiment. In the diagram 1... Gas water heater 2... Gas burner 7.
...First burner tube (first passage) 8...Second burner tube (second passage) 13...Baffle plate

Claims (1)

[Scope of Claims] 1) (a) A plurality of first passages that discharge a gas-rich mixture of fuel gas and primary air for combustion, and (b) the plurality of first passages. a second passage for discharging an air-rich mixture in which fuel gas and primary air for combustion are mixed in a portion adjacent to the first passage; A low nitrogen oxide burner that completely burns the mixture by the surplus air of the flame of the air-fuel mixture discharged from the second passage. 2) The low nitrogen oxide burner according to claim 1, further comprising a baffle plate that directs the air-rich air-fuel mixture blown out from the second passage toward a flame formed by being blown out from the first passage.