JPH04273906A - Combustion device - Google Patents

Abstract

PURPOSE:To reduce NOx generation of a household combustion device for a boiler, etc., by a method wherein a combustion part is provided over the whole length of a mixing pipes with rich-fuel gas chambers and has primary rich-fuel gas burner ports on the bottom, inclined plates having secondary lean- fuel gas burner ports are furnished on both sides of the primary rich-fuel gas burner ports, and lean-fuel gas chambers are formed behind the inclined plates. CONSTITUTION:A combustion part 2 is provided above the whole length of a mixing pipe 1. Fuel gas is blown from nozzles 3 and mixed with primary air in a rich-fuel gas chambers 4 and rich-fuel gas is produced and supplied to the combustion part 2 through flow paths 5. Primary burner ports 6 are provided on the bottom of the combustion part 2, and rich-fuel gas coming from the flow paths 5 is blown through the burner ports 6. Inclined plates, which face each other, tilt outward and are provided with secondary burner ports 8, are furnished on both sides of the primary burner ports 6 and lean-fuel gas chambers 7 are formed behind the inclined plates. Lean-fuel gas is spouted from the lean-fuel gas chambers 7 to the combustion part 2 through the secondary burner ports 8, mixed with rich-fuel gas and burned in two-stages.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion device for household combustion appliances such as water heaters, which reduces nitrogen oxides (hereinafter referred to as NOx) contained in combustion exhaust gas.

0002

[Prior Art] Conventional combustion devices for household combustion appliances such as water heaters are mainly based on Bunsen combustion, but this type of combustion generates a high temperature region in the flame and generates a large amount of NOx. There is a certain drawback. Additionally, all-primary air combustion systems have been put into practical use in some areas and have been shown to have a NOx reduction effect.
Since the air-fuel mixture becomes lean, there is a problem in that the combustion flame tends to lift.

[0003]Therefore, concentrating combustion is an effective combustion method that improves these problems, but conventional combustion devices using this concentrating combustion method are made of, for example, a flat ceramic plate with a large number of small flame holes. The plate has a partially formed rich gas combustion section, and when the combustion amount is reduced, the mixing of rich gas and light gas is poor, making it difficult to perform turndown and making the combustion equipment expensive. Ta.

0004

[Problems to be Solved by the Invention] The present invention solves the problem of difficulty in achieving turndown in conventional concentrated/concentration combustion, makes it possible to vary the amount of combustion over a wide range, and provides a combustion device that further reduces the generation of NOx. The purpose is to provide the following.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a combustion section over the entire length of the upper part of a mixing tube having a rich gas chamber for producing rich gas, and the combustion section is arranged below the mixing tube. A primary flame hole is provided at the bottom to eject and burn rich gas, and an inclined surface with a fresh gas chamber on the back side facing each other and producing light gas is provided on both sides of the flame hole, and a light gas chamber is provided on the upper part of the inclined surface of this combustion section. It is configured with a secondary flame hole for burning gas.

[0006]

[Operation] The rich gas generated in the mixing tube is burnt in a rich manner in the primary flame hole provided at the bottom of the combustion chamber. Slanted surfaces are placed facing each other on both sides of the primary flame hole, and the light gas is injected into the upper part of the primary flame hole. A secondary combustion hole is provided to perform air-excess combustion.

Therefore, the primary flame hole and the secondary flame hole perform concentrated combustion, and the lower primary flame hole and the secondary flame hole perform two-stage combustion, which improves the cooling of the flame and the mixability of the concentrated gas. This makes it possible to reduce NOx and widen the variable range of combustion amount, thereby achieving stable combustion.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a plan view of the main parts of the same embodiment.

Reference numeral 1 denotes a mixing tube, and a combustion section 2 is provided over the entire length of the mixing tube.A nozzle 3 faces the inlet of the mixing tube 1, and fuel gas and sucked primary air are formed inside. The mixture is mixed in the dense gas chamber 4 and then passed through the combustion section 2 through the communication port 5 provided at the top.
A plurality of burners are arranged in parallel via a secondary air distribution member 9 to form a gas burner.

The combustion section 2 is provided with a primary flame hole 6 at its bottom for ejecting and burning the dense gas from the flow port 5 at the top of the mixing tube 1.
On both sides, there is an erected inclined surface that faces each other and expands upward to form a fresh gas chamber 7 that generates fresh gas on the back side, and a secondary flame hole that blows out fresh gas and burns it at the top of this inclined surface. 8 is provided.

The light gas chamber 7 of the combustion section 2 communicates with the rich gas chamber 4 of the mixing tube 1 through a flow port 5, and secondary air supplied by a fan (not shown) or the like is introduced from below both sides of the mixing tube 1. The gas is mixed with the rich gas from the flow port 5 to produce light gas, which is ejected from the secondary flame hole 8 and burned.

The combustion section 2 is connected to the adjacent combustion section 2 via a secondary air distribution member 9, and introduces the secondary air supplied from between the adjacent mixing tubes 1 into the fresh gas chamber 7.

With the above configuration, the fuel gas ejected from the nozzle 3 and the sucked primary air are mixed in the rich gas chamber 4 of the mixing tube 1 to produce a rich gas with a small excess air ratio, and the primary flame hole 6 is
The gas is ejected from the tank and burns in a rich manner. Furthermore, the rich gas that has flowed into the fresh gas chamber 7 from the flow port 5 mixes with the secondary air introduced from below to produce fresh gas with a large excess air ratio, which is ejected from the secondary flame hole 8 to produce excess air. Perform combustion.

[0014] In this way, the primary flame hole 6 and the secondary flame hole 8 perform rich and lean combustion, and two-stage combustion is performed by combustion through the lower primary flame hole 6 and combustion through the upper secondary flame hole 8. Therefore, the flame in the primary flame hole 6 mixes with the light gas ejected from the secondary flame hole 8 and is cooled, preventing the generation of local high temperature areas and reducing the generation of NOx. The combustion amount can be varied over a wide range by improving the mixing properties of the fuel and the combustion amount can be varied over a wide range, and stable combustion can be achieved.

[0015]

Effects of the Invention As explained above, the combustion apparatus of the present invention has a primary flame hole for burning rich gas in the lower part and a secondary flame hole for burning light gas in the upper part. Staged combustion can be performed, which has the effect of reducing NOx and making it possible to vary the amount of combustion over a wide range.

Furthermore, since the combustion device can be formed from a sheet metal, there is an advantage that it can be manufactured at low cost.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention.

FIG. 2 is a plan view of the main parts of the same example.

[Explanation of symbols]

1 Mixing tube 2 Combustion part 4. Concentrated gas chamber 6 Primary flame hole 7. Light gas chamber 8 Secondary flame hole

Claims (1)

[Claims] Claim 1: A combustion part is provided over the entire length of the upper part of a mixing tube having a rich gas chamber for producing rich gas, and the combustion part is provided with a primary flame hole for burning the rich gas at the bottom of the mixing tube. Combustion characterized by having an erected inclined surface having a fresh gas chamber facing each other and generating fresh gas on the back side, and providing a secondary flame hole for burning fresh gas in the upper part of this combustion part inclined surface. Device.