JPS58110905A - Combustion device - Google Patents

Abstract

PURPOSE:To realize a reduction in NOx (in particular NO2) generation desirable in heating device for domestic use by techniques of performing a complete premixture surfce combustion, preventing an air flow into a burning surface, providing a reductive catalyst in a combustion exhaust gas passage and maintaining the temperature of the catalyst at optimum values. CONSTITUTION:A burner 1 which performs the complete premixture surface combustion is used. A combustion chamber 7 of the burner 1 has a sealed structure which never permits a secondary air to enter the burning surface. At a terminal end of the combustion exhaust gas passage 8 in the downstream of the combustion chamber 7, the reductive catalyst 9 of a transition metal and the like is provided. The reductive catalyst 9 is maintained at optimum temperatures by a method wherein a part of the combustion exhaust gas having passed through the catalyst 9 is led by a duct 10 to the upstream of the catalyst 9 in the combustion exhaust gas passage 8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the cleaning ratio of exhaust gas in combustion devices, particularly indoor closed type heating appliances.

Conventional burners for household combustion appliances used Bunsen burners, which had the drawback of high NOx values. Therefore, in many appliances such as heating appliances that are used indoors for a long time, premix burners such as Schwank burners, which have low NOx combustion, have been used.

However, considering the airtightness of homes in recent years, it cannot be said that even the burners used in the past have achieved sufficiently low NOx levels, especially when it comes to the human body. Bad influence #NO2 that clearly affects money
However, the drawback was that the proportion of NOx in the exhaust gas was large. The reason for this is that V is not clearly achieved, but in burners that perform premixed surface combustion, such as those used in burners, secondary air is supplied to the combustion surface so that stable combustion can be obtained even when the oxygen concentration of the atmosphere is low. As measures were taken, the combustion gas was cooled by the airflow caused by the secondary air, and the point at which No. 2 in the combustion gas was oxidized by the No. 02 It is thought that the enlargement of the eyelids promotes acid production from NO2 to NO2.3 NOx fz, 771 as a means to improve the above drawbacks.
A method of decomposing the original into N2 and 02 has been considered, but it is reduced with harmful gases such as ammonia gas, -acid and arsenic, and it is necessary to process the harmful gases in order to use them in household combustion appliances. In addition, a catalyst that has the effect of reducing No2 to Shu has been considered, but a method for effectively applying it to combustion equipment has not been established, so it has been difficult to convert NO2 to No-5. On the other hand, in industrial combustion equipment, the combustion exhaust gas is recirculated to the combustion chamber to lower the combustion temperature and reduce the NO
x (Although methods to reduce NOx emissions have been put into practical use, it is still difficult to apply them to open indoor heating equipment for home use.)
The value was high.

The present invention aims to improve the above-mentioned conventional drawbacks and provide a low NOx, especially low N02 combustion device suitable for home heating appliances. In addition to aiming for low NOx using burners,
By adopting a sealed structure that prevents air from flowing into the combustion surface of the combustion chamber, the rate of acid conversion from phantom to NO2 is almost reduced, and
By providing a reduction catalyst such as a transition metal in the exhaust gas passage downstream of the combustion chamber, and by guiding combustion exhaust gas or preheated air upstream of the reduction catalyst downstream of the combustion chamber, the atmospheric temperature of the reduction catalyst can be reduced and , re-eel rrIll after reduction, 'i
The most effective way to prevent NOx
(This is aimed at low N02r.)

Hereinafter, an example of the present invention will be explained based on the drawings.

The first light is an example of the case where the all-gas stove 4c4 of the present invention is used. In the figure, 1 is a burner that performs completely premixed combustion, and the gas nozzle 2 is the mixing tube 3 of the burner 1.
The gas ejected from the gas nozzle 2 is guided as a mixture from the mixing tube 3 to the mixture chamber 4 along with the air necessary for combustion due to the ejector effect of the gas flow, and the pressure is equalized and the wire mesh Surface combustion is performed at the flame mouth. The outer cylinder 6 of the burner 1 is made of heat-resistant glass, and transmits and radiates the radiant heat of the red-hot wire mesh flame port 5. 7 is a combustion chamber, which has a sealed structure to prevent secondary air from flowing into the combustion surface. 8 is a combustion exhaust gas passage downstream of the combustion chamber 7;
A reduction catalyst 9 made of a transition metal or the like is provided at its terminal end, and part of the combustion exhaust gas after passing through the reduction catalyst 9 marked #J is passed through a conduit 1o to the reduction catalyst 9 of $8. The top is designed to lead you to your seat. In addition, the combustion exhaust gas passage 8
Since the pressure is negative due to the draft force of the combustion exhaust gas, there is a suction force, and it is possible to suck a part of the combustion exhaust gas after passing through the reduction catalyst 9, thereby effectively controlling the temperature of the reduction catalyst. You can set the temperature.

According to this embodiment, since uniform premixed surface combustion is performed, it is possible to prevent the occurrence of localized high temperature areas, resulting in low NO
x (2) was achieved, and since the inflow of secondary air into the combustion chamber was prevented, it was possible to reduce the amount of acid from No. 2 to No. 2.

In addition, transition metal materials such as stainless steel, iron chromium steel, and molybdenum steel have the effect of promoting the reduction of NO2 in the high-temperature range from 200°C to 200°C. In the zone, it is mostly No, and then as the temperature decreases, the acid r progresses to NO2.

Furthermore, in this embodiment, since air is prevented from flowing into the combustion chamber 7, the temperature of the combustion exhaust gas is relatively high, so the ratio of NO in the combustion exhaust gas passage 8 is high. Combustion exhaust gas passage 8'
ff: When the acid (B) comes out and mixes with the indoor air, it progresses to NO2, so in order to use the reduction catalyst 9 most effectively, set the catalyst position at the lowest temperature where the reduction 7 effect can be expected. Lowest No2r including oxidation after passing through the catalyst
This means that H can be achieved. That is, the combustion exhaust gas passage 8 is provided with a reduction catalyst 9 that completely promotes the reduction of No. 2 to No. At the same time, the reduction catalyst atmosphere temperature is reduced to have a reducing effect, and the re-reduction of No. to NO. −(
By exclusively using the combustion exhaust gas as BK, it is possible to effectively reduce N02r.

FIG. 2 shows the case where the present invention is implemented in an open type hot air heater.

In the figure, the same numbers as in FIG. 1 indicate the same components.

In the figure, 6' is the outer cylinder of the burner 1 made of sheet metal,
1o' is a conduit that guides air upstream of the reduction catalyst 9 in the combustion exhaust gas passage 8, and a deflection plate 1 is placed opposite the opening at the tip of the conduit.
1 is uniformly distributed between air and combustion exhaust gas (
! - is provided for mixing. 12 is a blower, and reduction catalyst 9. A blower guide 13 is provided to prevent the blowing of air into the combustion chamber 77 from damaging the reduction effect and custom combustion. 14 is a hot air passage, 15 is a hot air outlet, and 16 is a main body casing of the hot air heater.

In this embodiment, the burner 1 is constructed of the outer cylinder 6' and sheet metal because the outer periphery of the outer cylinder 6' is @ the air passage 14, so there is no need to collect radiant heat, and because the radiant heat is reduced, low-load combustion is possible. Stable combustion is possible, resulting in even lower NoI (fE,
This is to make it possible.

The conduit 10' passes through the combustion chamber 7 and guides the air, so that the air is preheated in the combustion chamber 7, and when the air and combustion exhaust gas are mixed upstream of the reduction catalyst 9, the air is cold. , the purpose is to promote and prevent acid fE from No to NO2.

In this embodiment, air is guided upstream of the reduction catalyst 9, but it is of course better to introduce the combustion exhaust gas from the trowel that passes through the retarding catalyst 9.

In this example, there are some differences r,
However, the basic effects are the same.As explained in the above two embodiments, according to the present invention, the following effects can be achieved.
Burning and impregnation and prevention of air inflow to the combustion surface (+): As a result, low NOx and low NO2 are achieved.

■ A reduction catalyst is installed in the combustion exhaust gas passage, and the combustion exhaust gas or preheated air is passed upstream of the reduction catalyst so that the atmospheric temperature of the reduction catalyst becomes the optimum temperature V'c for reducing effects and preventing reduction oxidation. Because it is evenly mixed with the combustion exhaust gas of the combustion engine, an even lower No.

[Brief explanation of the drawing]

FIG. 1 is a front cross-sectional view showing the basic configuration of a combustion device that is an embodiment of the present invention, and FIG. 2 is a full view of a hot air heater implemented with the same combustion device. It is a 1-plane sectional view. 1... Burner, 7... Combustion chamber, 8...
... Combustion exhaust gas passage, 9 ... Reduction catalyst,
10... Conduit. Name of agent: Patent attorney Nakao (man) and 1 other person (1st)
Figure 2Figure 2

Claims (1)

[Claims] a burner that performs fully premixed surface combustion; a combustion chamber that has a sealed structure that prevents air from entering the combustion surface of the burner;
and a reduction catalyst provided in a combustion exhaust gas passage downstream of the combustion chamber, and means for supplying combustion exhaust gas or preheated air after passing through the first reduction catalyst to an area upstream of the reduction catalyst and downstream of the combustion chamber. A combustion device configured to provide a.