JPS6229810A - Combustion device - Google Patents

Abstract

PURPOSE:To reduce NOx and NO2 in a combustion unit for use in an indoor open type heater device by a method wherein an exhaust control cylinder is arranged within a combustion chamber to make a double structure, and a combustion exhaust gas is returned back to the lower part of an exhaust control cylinder to be mixed with the secondary air and then guided to a burner. CONSTITUTION:Combustion exhaust gas from a burner 2 rises from a combustion chamber 5, is mixed with air indicated by an arrow coming from within the room through the holes 10 of porous body 11 and then discharged at 20 into the room under an action of a blower 18. At this time, the discharged gas is routed through a clearance 15 from a discharging cylinder 14, mixed with a secondary air flowing in through the secondary air port 6, and then supplied to a location near the flame as the secondary air from the secondary air passage 16. Since this secondary air contains a large volume of CO2 and N2, combustion of secondary flame is restricted, a flame temperature is decreased and then a volume of NOX and NO2 is reduced. With such a construction as above, it is possible to reduce a volume of NOX and NO2.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to an improvement in a gas or petroleum fuel combustor, particularly a combustor for an indoor open type heating appliance, and is intended to purify exhaust gas.

Conventional technology Recently, this type of combustor uses low N to clean exhaust gas.
Oxification is being talked about. One way to do this is to lower the flame temperature, and methods such as surface combustion, two-stage combustion, and exhaust gas recirculation have been proposed.

Surface combustion type burners are used as low NOx burners in gas stoves and the like. However, this makes it difficult to adjust the combustion amount and requires a wide range of adjustment. The latter two are mainly used for large-capacity equipment, but they cause a large loss of equipment, including air blowers, making it difficult to use them for small-sized household equipment.

It is said that the negative effects of inventions are several times greater than the problems they are intended to solve. Moreover, with the surface combustion type, the NO2 ratio increases, sometimes reaching 60%.
Up to 90% of the amount is NO2, and there are concerns about its impact on the human body in closed spaces such as indoors.

The present invention meets such requirements and aims to reduce NOx and the NO2 ratio therein by a simple means.

Means for Solving the Problems In order to solve the above problems, the combustor of the present invention is provided with an exhaust control tube in the combustion chamber.

Function The present invention uses the above-described means to circulate a part of the exhaust gas generated by the burner, mix it with the secondary air, and supply it to the fire as secondary air for combustion, thereby lowering the temperature of the fire. .

Example An embodiment of the present invention will be described below with reference to the accompanying drawings.

In the figure, 1 is a casing of a hot air heater, 2 is a burner, and a flame 4 is formed on a burner surface 3.

Reference numeral 5 denotes a combustion chamber containing the burner 2, which is partitioned by a partition plate 7 having a plurality of secondary static ports 6 at the bottom, and has a combustion section at the top;
The lower part is a secondary air pressure chamber 8. 9 is an exhaust gas passage provided at the exit of the combustion chamber 5, and is a porous body made of heat-resistant ceramic, metal, etc., and having a large number of holes 10 containing a platinum catalyst etc. 11 are installed. The pressure equalization chamber 8 is provided with a secondary air inlet 12, and an air amount control means 13 such as a damper that adjusts the opening area of the secondary air inlet 12 to adjust the introduced air.
have.

Reference numeral 14 denotes an exhaust control cylinder formed to surround the burner 2 with a gap 15 between the wall of the combustion chamber 5, and a secondary air passage 16 formed at the lower end, and this passage 15 located below the burner surface 3. I'm letting you do it. Further, it is preferable that the upper end 17 of the control cylinder be located at a position that surrounds the flame 4. Further, the secondary air port 6 provided in the partition plate 7 is arranged below the upper end 17 of the control cylinder.

Reference numeral 18 denotes a blower, which blows out indoor air (broken line) sucked in from the suction port 19 as exhaust from the exhaust gas passage 9 (solid straight line → mixed with hot air sword 0 broken line) from the outlet 20.

Although this example has been explained using a top flame, the raw moisture does not change even with a horizontal flame.

In the above configuration, fuel and primary air (premixed air) are supplied to the burner 2 and ignited. At the time of combustion, the combustion exhaust gas rises from the combustion chamber 5 and mixes into the air flow from the blank through the holes 10 of the porous body 11. This mixed gas is discharged into the room as warm air from the blower outlet 20 by the blower 18 for heating.

At this time, in the conventional burner 2, the burner 2 forms a flame 4, and the flame reaches a temperature of several hundred degrees with the nearby high-temperature water.
Generates 0 ppm NOx (No and No2). For example, a surface combustion furnace burner also produces about 20 ppm of NOx, of which NO2 reaches as much as 10-odd ppm.

However, in the present invention, the generated exhaust gas is sent through the gap 15 by the exhaust control tube 14, mixed with the secondary air from the secondary air port 6, and is supplied as secondary air from the secondary air passage 16 to the vicinity of the flame. Ru. That is, due to the double configuration in the combustion chamber 5 by the exhaust control tube 14, the draft generated inside the control tube 14 makes the secondary air passage 16 section negative pressure, causing exhaust gas to flow through the outer peripheral gap 15 of the control tube 14. There is. The secondary air mixed with this exhaust gas has a lower oxygen concentration than the supplied indoor air and contains a large amount of inert gases such as Co2 and N2, so combustion of the secondary flame involving the secondary air is suppressed. Flame temperature decreases. This is because most of the No is formed in the secondary flame region, and moreover, the formation of No.

is cooled by secondary air! Considering this together with the fact that the secondary flame temperature is reduced and the secondary air supplied is preheated by mixing with the exhaust gas and the degree of cooling of the No. 7 is lowered, the above double effect can be expected.
This makes it possible to reduce Ox and No2 simultaneously.

This exhaust gas circulation process is effectively carried out with a simple configuration due to the positional relationship between the control tube 14, the secondary air port 6, and the secondary air passage 16.

Effects of the Invention As described above, according to the combustor of the present invention, a part of the exhaust gas is mixed into the secondary air in the combustion chamber, thereby reducing the generated NOx and NO2, and reducing the impact on the human body. This greatly improved the safety of exhaust gas.

[Brief explanation of the drawing]

The figure is a sectional side view of a combustor according to an embodiment of the present invention used in an open type heater. 2...Burner, 3...Burner surface, 5.
... Combustion chamber, 6 ... Secondary air port, 13.
...Air amount control means, 14...Exhaust control cylinder, 16...Secondary air passage, 17...
Exhaust control tube tip (upper end) / Agent's name Patent attorney Toshio Nakao and 1 other person 2 --- Burner 5 -- Kazuki Kazuki ZO/σ IZ

Claims (2)

[Claims] (1) An exhaust control tube is provided with a gap between the combustion chamber wall and the combustion chamber wall so as to surround the flame within the combustion chamber, and a secondary air passage is formed at the bottom or rear end of the control tube. The combustor is provided so as to be located closer to the air-fuel mixture than the burner surface to be formed, and the secondary air port to the secondary air passage is provided below or at the rear of the tip of the control cylinder. (2) The combustor according to claim 1, further comprising means for controlling the amount of air flowing into the secondary air port.