JPH02219902A - combustion device - Google Patents

Abstract

PURPOSE:To reduce the production of NOx by forming a plurality of primary burner ports of a burner for premixing and burning and a furnace and surrounding a vessel having a secondary burner port composed of a single opening part in the upper face while providing a coil composed of a transition metal between the primary burner ports and the secondary burner port. CONSTITUTION:Slit-like primary burner ports 4 provided in the upper face of a burner 2 are covered by a vessel 7 forming a furnace 5 and a secondary burner port 16 composed of a single opening part. A coil 8a composed of a transition metal is provided between the primary burner ports 4 and the secondary burner port 6 (just above the primary burner ports). In the case where a combustion quantity is large, the coil 8 forms two-stage combustion completely included in the secondary burner port. NOx in an exhaust gas is reduced by the NOx control effect of two-stage combustion and some reducing effect by the coil 8. Next, in the case where the combustion quantity is small, an ordinary Bunsen flame is formed in the coil 8 without two-stage combustion of a flame. The reducing effect of the coil is active and dominant and NOx is reduced positively.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention is a burner that performs premix combustion, which is often used in combustion heat source type indoor open hot air heaters, etc., which adds two-stage combustion and catalytic reduction. This invention relates to a combustion device that suppresses the generation of nitrogen oxides (hereinafter referred to as NOx).

Exhaust gas denitrification technology is one of the technologies for reducing NOx generated from conventional combustion equipment, and among these, the catalytic reduction method is a method that reduces NOx by adding reducing gas in the presence of an appropriate catalyst.
is reduced to N. NH3 is used as the reducing gas in selective reduction, but if the reaction temperature is too high, NO is produced by the oxidation reaction of NH3, reducing the denitrification rate and making temperature control difficult.On the other hand, in non-catalytic reduction, Co, C
Although H4 is used, 0. The problem is that the amount of reducing gas consumed increases in proportion to the concentration.

Moreover, when both of them are used in household combustion appliances, the use of reducing gas is fraught with many dangers. Therefore,
By using two-stage combustion and a transition metal catalyst, catalytic reduction is achieved without actively adding reducing gas, resulting in low N
Combustion devices that perform oX combustion have been developed.

Hereinafter, a conventional combustion device will be explained based on the drawings.

FIG. 3 is a front view of a conventional combustion device using two-stage combustion and catalytic reduction, with main parts cut away, and FIG. 4 is a vertical sectional view of the conventional combustion device. Nozzle 1 that spouts gaseous fuel is burner 2
The mixing tube 3a is provided at a position facing the population 3, and at that time, the amount of secondary air sucked by the jet of gaseous fuel ejected from the nozzle is set such that the excess air ratio m is 0.6 to 0.9. Adjust the diameter of mixing pipe number 3 using a damper, etc.

A primary flame hole 4 provided on the top surface of the bar 2 is connected to a combustion chamber 5 and a vessel 7 forming a secondary flame hole 6 consisting of a single opening.
It is covered to prevent outside air from entering except through the secondary flame hole 6, and a coil 8 made of a transition metal is provided within the two flames 10 generated in the secondary flame hole 6 so as to be completely contained within the secondary flame. be.

In the combustion apparatus configured as described above, the combustible gas in the mixing tube 3a flows out onto the primary flame hole 4 in a fuel rich state and is ignited to form the primary flame 9. The combustion gas released from the primary flame 9 contains NO as well as combustible gas that cannot be combusted due to lack of oxygen. The combustible gas diffuses and mixes with the surrounding air at the secondary flame hole 6, forming a secondary flame 10.
is formed to complete two-stage combustion.

CO in the combustible gas proceeds to react with N01NO8 using the transition metal coil 8 as a catalyst.

CO+NOx →cot+No (2) CO
+1/20! = COt (2)
2CO+2NO→2CO□10N! (3) Among the reactions in the above equation, the reaction of reducing Not to NO is the fastest,
Next, the CO oxidation reaction of formula (2) is fast.

The reduction reaction of No in equation (3) is reduced to 0 by the reaction in equation (2).
Proceeds after □ is consumed. Therefore, in order for NO to be reduced, there must be enough CO to carry out the reactions of equations (1) and (2). However, the remaining amount in the combustion gas is 0! The concentration is the excess air ratio m of 0.6
Because it is controlled to ~0.9, the amount of NO3 is extremely low (and as a result, almost no NO3 is generated.

Therefore, as a reaction, (3) 2 will proceed, with equivalent amounts of CO, CO! , N is oxidized and reduced to win.

As a result, the generation of NOx discharged from the combustion appliance is suppressed by two-stage combustion, and the negative part is reduced to N8 by catalytic reduction.

Furthermore, CO is also reduced because it is oxidized to COz during catalytic reduction.

Problems to be Solved by the Invention However, in the conventional configuration, the amount of combustion decreases to a certain extent, and in abnormal conditions such as dust clogging of the mixing tube, the excess air ratio m decreases to nearly 0, and the reaction region (secondary flame 10 ) is formed in the transition metal coil 8 provided in the secondary flame hole 6, the supply of secondary air necessary for combustion is obstructed by the coil 8, and the gas in the middle of reaction (combustion) is comes into contact with the coil 8, which is a cooling body, and causes incomplete combustion,
There was a risk of generating large amounts of CO, which is harmful to the human body.

Furthermore, when the amount of combustion decreases, two-stage combustion is not formed and the flame and the coil 8 are separated, resulting in a decrease in the effect of catalytic reduction. The present invention solves these conventional problems, and aims to provide a combustion device that achieves clean combustion and can be used in indoor open combustion hot air heaters and the like.

Means for Solving the Problems In order to achieve the above object, the combustion apparatus of the present invention includes a plurality of primary flame holes of a burner for premix combustion to form a combustion chamber,
and a configuration in which the container is provided with a secondary flame hole consisting of a single opening on the upper surface, and a coil made of latitudinal metal is provided between the secondary flame hole 6 and the primary flame hole. It is.

Operation The present invention has the above-described configuration, making it possible to maintain safety even in abnormal conditions without impairing the effect of reducing No. 1 and generation even when the combustion amount fluctuates.

Embodiment FIG. 1 is a front view of a combustion apparatus showing an embodiment of the present invention. FIG. 2 is a longitudinal sectional view of the device.

A nozzle 1 for ejecting gaseous fuel is provided at a position opposite to an inlet 3 of a mixing pipe 3a of a burner 2, and at this time, the amount of primary air sucked by the jet of gaseous fuel ejected from the nozzle is adjusted so that the excess air ratio m is 0. Adjust the diameter of the mixing tube 3 using a damper or the like so that the diameter is .6 to 0.9. A large number of slit-shaped primary flame holes 4 provided on the upper surface of the burner 2 are covered by a container 7 forming a combustion chamber 5 and a secondary flame hole 6 consisting of a single opening. A coil 8a made of a transition metal is provided between the primary flame hole 4 and the secondary flame hole 6 (directly above the primary flame hole 4).

The combustion principle in the above configuration is the same as that of the conventional example, so detailed explanation will be omitted. When the amount of combustion is large, the coil 8
The second flame is completely contained within the flame, forming two-stage combustion. As a result, as explained in the conventional example, the NOx suppression effect of the two-stage combustion and the reducing effect of the Meiboshi coil 8 reduce the NOx in the exhaust gas.
X is reduced.

Next, when the amount of combustion is small, the flame does not undergo two-stage combustion and a normal Bunsen flame is formed inside the coil 8. Since the reaction area is covered by the entire coil, the reduction effect of the coil becomes active and dominant. and NOx is actively reduced.

In addition, even if the amount of combustion is small and the primary air is extremely reduced due to some abnormality, the flame will extend due to the lack of primary air, and the coil 8 and the reaction area will be formed above the coil. Therefore, the coil does not obstruct the supply of secondary air necessary for complete combustion, and unburned gas does not come into contact with the coil, which serves as a cooling body, reducing the amount of CO that is harmful to the human body. It is possible to improve safety as there is no risk of occurrence.

Effects of the Invention As is clear from the above embodiments, according to the combustion apparatus of the present invention, the primary flame hole of the burner for premix combustion is separated from the combustion chamber.
Since it is covered with a container consisting of a primary flame hole and a secondary flame hole, and is made of transition metal between the primary flame hole and the secondary flame hole, even if the combustion amount changes, NOx and CO To provide a clean and highly safe combustion device that has the effect of reducing combustion and maintains safety even when the amount of combustion changes and the amount of primary air is extremely reduced due to some abnormality. Can be done.

[Brief explanation of the drawing]

FIG. 1 is a front view of a combustion device according to an embodiment of the present invention with main parts cut out, FIG. Figure 4 is a longitudinal sectional view of the same. 1...nozzle, 2...burner, 4...
...Primary flame hole, 5... Combustion chamber, 6...
...Secondary flame hole, 8...Coil (transition metal catalyst). Name of agent: Patent attorney Shigetaka Awano Haka12 Figure 10-11 Otsujien 3kyu

Claims (1)

[Claims] A plurality of primary flame holes of a burner that performs premix combustion are provided in a container having a combustion chamber and a secondary flame hole consisting of a single opening on the upper surface, and A combustion device characterized in that a coil made of a transition metal is provided between a secondary flame hole and the plurality of primary flame holes.