JPH04151410A - Low nitrogen oxide burner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a burner that generates low nitrogen oxides for use in small-sized combustion devices for household use, small-sized commercial use, and the like.

(Prior art) Nitrogen oxides (NOx) in the combustion gas of burners in various combustion devices are not only toxic in themselves, but are also considered to be one of the causes of acid rain and photochemical smog. Various measures have been developed and taken for burners used in the apparatus to reduce the amount of NOx generated.

(Problem to be solved by the invention) However, conventionally, these measures have mainly been taken for large-scale combustion equipment for industrial use, etc., which are subject to legal restrictions.
Small-sized combustion devices for home use and small-scale commercial use have problems such as noise, so it cannot be said that sufficient countermeasures are necessarily taken.

In other words, in large combustion equipment, the static pressure of the combustion fan can be increased, so it is easy to control the flow of combustion gas and air, there is a high degree of freedom in burner layout, and noise countermeasures are easy. Due to these advantages, the noise countermeasure conditions are not strict, and the combustion chamber can be made large, so it is easy to achieve complete combustion even if measures are taken to reduce NOx by so-called slow combustion. Combustion devices such as these do not have these advantages, and therefore it is difficult to take measures to reduce NOx in small combustion devices compared to large combustion devices.

The present invention aims to solve the above-mentioned conventional problems by rationally applying a NOx suppression method by combustion of a fuel-rich mixture and a NOx suppression method by so-called mixing promotion to an /Iλ type combustion device. This is the purpose.

(Means for Solving the Problems) Means for solving the above-mentioned problems will be explained with reference to drawings corresponding to embodiments. A second ejector body 3 extending in the length direction is installed on both sides of the lower part of the first ejector body 1 having a shaped side wall portion 2 and extending in the length direction, with a gap 4 interposed therebetween. A laminar flow jetting part 5 continuous in the length direction is provided at the center of the upper part of the body l, and a large number of jetting holes 6 are provided in the side wall parts 2 on both sides of the laminar flow jetting part 5, and the second jetting body 3 is provided with an ejection hole 7a corresponding to the inside of the gap 4, and the second ejector 3 is supplied with a fuel-rich mixture, and the first ejector 1 is supplied with air. It is structured as follows.

In the above configuration, the first ejection body 1 may be configured to be supplied with a lean fuel mixture instead of air.

Further, in addition to the ejection holes 7a corresponding to the inside of the gap 4, the second ejection body 3 can be provided with an ejection hole 7b at the upper end, and the ejection holes corresponding to the inside of the gap 4 can be provided. It is also possible to provide the ejection holes 7b only at the upper end instead of the ejection holes 7a. Further, an ejection hole 6 provided in the side wall portion 2 of the first ejection body 1 described above
can be configured as a slit in the width direction or as a number of holes.

The above-mentioned burner is constructed by arranging an appropriate number of first and second ejecting bodies 1 and 3 in series in the width direction.

(Function) In the above configuration, air is supplied to the first ejection body j,
When a fuel-rich mixture is supplied to the second ejector 3, the air flows into the central laminar flow ejector 5 at the upper part of the first ejector l.
At the same time, the fuel-rich mixture is ejected from the ejection hole 6 of the inclined side wall portion 2, and the fuel-rich mixture is ejected from the ejection hole 7a of the second ejection body 3.
It erupts into liiigIli4 and flows upward from there.

The fuel-rich mixture flows upward through the gap 4, burns with a low oxygen partial pressure, and rises. In this way, a fuel-rich mixture burns with a low oxygen partial pressure in the initial combustion region, so the NO
The amount of x generated is small.

The air-fuel mixture that has risen as described above is sucked in the direction of the side wall 2 by the negative pressure section formed by the jetting of air from the jet hole 6 of the inclined side wall 2 of the first jet body 1, and is combined with air. The mixture is quickly and thoroughly mixed, and the unburned portion is combusted. Since this combustion is carried out rapidly and in a well-mixed state, the formation of local high temperature regions is suppressed, and the overall combustion temperature is also lowered, thereby suppressing the generation of P○X. Further, this combustion is stably performed using a stable flame of a fuel-rich mixture above the second ejection body 3 as a pilot flame.

In this case, in the present invention, the side wall portion 2 provided with the air jet holes 6 is steeply sloped, and the area provided for the above-mentioned mixing and combustion is wider than that of a side wall portion 2 with a gentle slope. It is possible to suppress the ejection speed for a given amount of air supply, thereby suppressing excessive suction and excessive mixing of the fuel-rich mixture. Therefore, the fuel-rich mixture is subjected to the above-mentioned combustion while being evenly distributed in the side wall portion 2, and it is possible to prevent the combustion reaction from stopping due to overcooling.

In particular, when the amount of combustion is small, the flow velocity of the fuel-rich mixture ejected from the second ejection body 3 becomes slow. Since the lower part of the side wall 2 is sucked in and mixed with air and combusted, there is a problem that the combustion reaction is likely to stop due to rapid supercooling. As described above, this problem does not occur and the turndown ratio can be increased.

In addition to the above, in the present invention, above the first ejection body 1,
Since the air from the laminar flow jetting section 5 is jetted out in a laminar flow state, this air acts to block the propagation of turbulent flow caused by the air jetted from the jetting hole 6 and prevent the flame from vibrating. Combustion of excess air above one ejector l can be stabilized.

Therefore, the flame does not cause lift or vibration combustion, and noise generation due to this is suppressed.

The above operation is for the case where air is supplied to the first ejection body 1, but instead of air, a lean mixture of fuel can also be supplied, and in this case, the side wall of the first ejection body 1 The stability of combustion above section 2 can be further improved.

Furthermore, if the above-mentioned second ejection body 3 is provided with an ejection hole 7b at the upper end in addition to the ejection hole 7a corresponding to the inside of the gap 4, the jet of the fuel-rich mixture ejected from there can be The exhaust gas recirculation effect can be expected. Further, since the air-fuel mixture ejected from the upper end of the second ejector 3 is also sucked in the direction of the side wall 2, the ejection hole 7a corresponding to the inside of the gap 4 may be omitted in some cases. can.

(Example) Next, embodiments of the present invention will be described with reference to the drawings.

In the figure, reference numeral 1 denotes a first ejection body, and this first ejection body 1 has a steeply sloped mountain-shaped side wall portion 2 at its upper portion, and is configured to extend in the length direction. Reference numeral 3 denotes a second ejector extending in the length direction, and the second ejector 3 is installed on both sides of the first ejector 1 with a gap 4 interposed therebetween.

A laminar flow jetting part 5 continuous in the length direction is provided in the upper center of the first jetting body l, and a large number of jetting holes 6 are provided in the side wall parts 2 on both sides of the laminar flow jetting part 5, This spout hole 6
is configured as a slit in the width direction. This ejection hole 6 can be composed of not only a slit but also a large number of holes. In the configuration shown in FIG. 1, the second jet body 3 is provided with a jet hole 7a corresponding to the inside of the gap 4, and in the configuration shown in FIG. The ejection body 3 is provided with ejection holes 7b at the upper end in addition to the ejection holes 7a corresponding to the inside of the gap 4, and the ejection holes 7b are arranged between the respective slits as the ejection holes 6. It is configured as a slit at a certain position. The second ejection body 3 can also be provided with the ejection holes 7b only at the upper end.

Thus, the burner is configured so that a fuel-rich mixture is supplied to the second ejector 3, and air or a fuel-lean mixture is supplied to the first ejector 1. are doing. At this time, an appropriate number of the first and second ejection bodies 1.3 can be continuously arranged in one width direction to constitute a burner with a desired combustion amount.

The above-mentioned first ejector 1, and if necessary, the second ejector 3
Although not shown in the figure, the configuration for supplying the air-fuel mixture to the fuel gas is, for example, similar to a conventional Bunsen burner, by ejecting fuel gas into the throat of the mixing section and sucking in the surrounding air to mix it. , a configuration in which a mixture of fuel gas and primary air is ejected from each ejection hole, etc. may be used as appropriate. As mentioned above, by adjusting these mixing parts, the configuration is such that a fuel-rich mixture can be supplied to the second jetting body 3 and a fuel-lean mixture can be supplied to the first jetting body 1. can do. Here, the air ratio of the mixture supplied to the second ejection body 3 is, for example, when λ is approximately 0.4, assuming that the theoretical air amount λ=1.
When supplying a fuel-lean mixture to the first ejector 1, the fuel mixture is supplied so that, for example, λ is about 1.5 to 2.5.

(Effects of the Invention) As described above, the present invention provides nitrogen reduction by combustion of a fuel-rich mixture.
By rationally coexisting the effect of reducing the amount of Ox generated and the effect of reducing the amount of NOx generated by combustion in a rapid and good mixing state, the flame in the latter combustion is performed stably and noise is reduced. In addition to suppressing the occurrence of the former, it is possible to prevent the occurrence of incomplete combustion in the combustion of the former, and in this way, in small combustion equipment where measures against noise are strict,
This has the effect that measures can be taken to reduce NOx without increasing noise. In particular, in the present invention, since the side wall of the first ejection body that performs the latter combustion is formed into a steeply sloped mountain shape, even when the amount of combustion is small, combustion in this part can be performed stably. This has the effect that the turndown ratio can be greatly reduced, and the stability of the flame can be further improved by the laminar flow jet section provided in the first jet body.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are an explanatory longitudinal cross-sectional view and an explanatory plan view, respectively, showing a first implementation example 1 of the present invention, and FIGS. 2(a) and (b) are an explanatory longitudinal sectional view and an explanatory plan view, respectively. They are an explanatory longitudinal sectional view and an explanatory plan view, respectively, showing other embodiments of the present invention. Reference numeral 1: first ejecting body, 2: side wall portion, 3: second ejecting body, 4: gap, 5: laminar flow ejecting portion, 6, 7a,
7b...Blowout hole.

Claims (7)

[Claims] (1) A second jet body extending in the length direction is installed on both sides of the lower part of the first jet body which has a steeply sloped mountain-shaped side wall portion at the upper part and extends in the length direction, with a gap between the second jet body, and A laminar flow jetting part continuous in the length direction is provided at the center of the upper part of the first jetting body, and a large number of jetting holes are provided in the side walls on both sides of the laminar flow jetting part, and the second jetting body is characterized in that an ejection hole is provided correspondingly within the gap, a fuel-rich mixture is supplied to the second ejector, and air is supplied to the first ejector. Burner with low nitrogen oxide generation (2) A low nitrogen oxide generation burner characterized in that the first ejection body according to claim 1 is configured to supply a lean fuel mixture instead of air. (3) The second ejection body according to claim 1 is a low nitrogen oxide generation burner, characterized in that the second ejection body is provided with an ejection hole at the upper end in addition to the ejection hole corresponding to the inside of the gap. (4) The second ejection body according to claim 1 is a low nitrogen oxide generation burner characterized in that the ejection hole is provided only at the upper end instead of the ejection hole corresponding to the inside of the gap. (5) A low nitrogen oxide generation burner according to claim 1, wherein the ejection holes provided in the side wall of the first ejection body are configured as widthwise slits. (6) The low nitrogen oxide generation burner according to claim 2 or 3, characterized in that the ejection holes provided at the upper end of the second ejection body are configured as widthwise slits. (7) A low nitrogen oxide generation burner characterized in that the first and second ejecting bodies according to claim 1 are constructed by continuously arranging an appropriate number of them in the width direction.