JPH1038215A - Burner combustion method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a burner combustion method wherein there is accompanied by an oxidization heat production reaction where a heat production rate is enough low as compared with ordinary combustion, and a fire flame is formed stably in a wide space, and further a fire flame volume is very greatly stabilized and combusted. SOLUTION: There are brought into contact high temperature diluted air that is very lower than ordinary air at least before a combustion reaction and above combustion stabilization limit temperature of mixed air at that oxygen concentration or a corresponding oxidizing agent and a fuel in a furnace, which are therefore stably combusted under an oxidization heat production reaction at a very low speed. The combustion is securely achieved by adding a hydrocarbon fuel or hydrocarbon as a marker when the hydrocarbon fuel is used as a fuel or even when a fuel not including hydrocarbon is used, and keeping the combustion in the state where it is green colored.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved method for burning a burner. More specifically, the present invention relates to a burner combustion method for stably realizing high-temperature air combustion in which diffusion combustion is performed under sufficiently low-speed oxidative exothermic reaction with high-temperature and low-oxygen air.

[0002]

2. Description of the Related Art Generally, a diffusion combustion burner forms a short flame because fuel and air are quickly mixed and burned. And since all the sensible heat generated by the combustion gas is held in the flame portion, the peak of the heat flux of the flame is inevitably generated, and it is difficult to generate a large amount of NOx and obtain a uniform heat flux distribution. Met. In addition, even if an attempt is made to form a long flame by deteriorating the mixability between fuel and air, combustion becomes unstable, and incomplete combustion and flame blow-off are liable to occur. Therefore, in order to achieve a uniform heat flux, a conventional general diffusion combustion type burner is equipped with many burners, and the volume of the flame for each burner is reduced to achieve the maximum heat flux and the average heat flux. The difference has been reduced.

However, it is not a fundamental solution since it is impossible to prevent the flame volume from being reduced and the peak of the heat flux from occurring due to the vigorous oxidative exothermic reaction.

[0004] On the other hand, as one of the methods for forming a temperature field which is most preferable in terms of a heat transfer surface by reducing a difference in temperature of combustion gas in a heating system, an unburned air-fuel mixture is diluted to increase its mass. Thus, it is possible to eliminate the temperature difference. When this dilution is performed by exhaust gas circulation, in order to increase the gas circulation amount while suppressing the exhaust gas loss, it is conceivable to recirculate a part of the exhaust gas by mixing it with the combustion air. As a method of supplying a part of exhaust gas mixed with combustion air, there is a combustion method conventionally called an exhaust gas recirculation combustion method. This combustion method mixes part of the low-temperature exhaust gas with the combustion air to produce
The combustion is carried out using air having a low oxygen concentration of about 3% and warmed to about 50 ° C to 200 ° C.

[0005]

However, even with this exhaust gas recirculation combustion method, the maximum temperature of the flame can be slightly reduced to suppress the thermal NOx somewhat, and the temperature can be reduced in the heating system, for example, in the furnace. Could not sufficiently reduce the difference in combustion gas temperature. It is conceivable to further reduce the temperature difference by increasing the gas circulation amount.However, even if only the exhaust gas recirculation amount is increased, the oxygen concentration becomes low and it becomes difficult to burn, causing sudden instability of combustion. Become.

[0006] In addition, raising the temperature of the oxidizing agent alone,
For example, raising the temperature to about 1000 ° C. or higher requires that the maximum temperature of the flame be much higher than that in normal combustion unless a special combustion method such as light-and-dark combustion is adopted, or even if it is adopted. It was considered that this would cause combustion, and therefore, was hardly considered as generally available combustion.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of burning a burner in which a flame is generated which is accompanied by an oxidative exothermic reaction having a sufficiently low heat generation rate as compared with ordinary combustion and which stably burns in a wide space. And In other words, an object of the present invention is to provide a method for burning a burner in which the flame volume is very large and burns stably.

[0008]

In order to achieve the above object, the present inventors have conducted various studies. As a result, to recover the instability of combustion when the oxygen concentration is much lower than that of ordinary air, It has been found that it is essential that the air temperature itself be much higher than that used in the conventional exhaust gas recirculation combustion method.

That is, considering the combustion stability conditions,
The essential factors of high temperature air combustion combining air heating and gas recirculation can be seen as oxidant temperature and oxygen concentration. Therefore, it was experimentally examined how the combustible range of a diffusion flame using hydrocarbon gas as a fuel varies depending on the high-temperature dilution air temperature and its oxygen concentration. The experiment is shown in Figs.
As illustrated in FIG. 7, a flame formed in a cross flow system in which a high-temperature air is diluted with nitrogen in advance, and then a fuel jet flows into the high-temperature preheated air flow from a direction perpendicular to the high-temperature preheat air flow. The nozzle portion has a structure covered with a heat insulating material that is not exposed to a high-temperature flow. Fuel and _{LPG (C 3 H 8 97%} ) 0.053
m ³ / h (1.380 kW) was constant, and the high-temperature air flow rate was constant at 15 m ³ / h, the sum of the air amount and the nitrogen dilution amount. The temperature of the dilution air gradually decreased from 1100 ° C., but the condition was such that the combustion became unstable. FIG. 8 shows the tendency of the stable combustion range with respect to the dilution air temperature at that time when the nitrogen dilution ratio of air was changed. As a result of the observation of the combustion state, between the temperature of the air as the combustion oxidant and the heat recirculation amount, that is, the oxygen concentration of the dilution air, the gas recirculation amount can be increased as the temperature of the combustion oxidant increases. It has been found that there is a relationship, in other words, that if the temperature of the dilution air, which is the oxidizing agent for combustion, is high, combustion is established even if the oxygen concentration is reduced.

Further, based on this finding, the present inventors have conducted a study and found that the temperature of the combustion air was raised much higher than that used in the conventional exhaust gas recirculation combustion method without changing the air ratio. If the oxygen concentration as an oxidizing agent is made much lower than that of ordinary air, when it reaches a certain condition, the oxidation exothermic reaction is much slower than that of ordinary air, but it is stable. A phenomenon occurs in which the flame increases in the visible emission color of the flame, at which time the proportion of the combustion reaction intermediate product of the hydrocarbon-based fuel that emits a green spectrum component increases. Also came to know the phenomenon of greening (greening).

That is, as the temperature of the combustion air increases, the ratio of the green emission spectrum intensity to the blue emission spectrum intensity in the visible emission color of the flame tends to increase. It has been found that the increase phenomenon becomes remarkable. When the flame has a normal oxygen concentration (about 21%) and diffuses and combusts air and fuel at normal temperature (hereinafter, referred to as normal combustion), the flame has a blue color, so-called blue flame, and has a green color. It was not possible for the color to become dull, that is, for the green emission spectral components to appear so as to affect the flame color. According to the reaction chart of the hydrocarbon fuel during normal combustion, most of the reactions pass through a reaction path that generates CH radicals, which are blue emission spectrum components. However, when the temperature of the oxidizing agent is increased and the oxygen concentration is decreased, the rate of the reaction passing through the reaction path for generating C ₂ radicals, which is a green light-emitting component, increases, or the mainstream combustion reaction occurs. Presumed.

In addition, the combustion stability limit temperature of the air-fuel mixture at each oxygen concentration (when the combustion becomes unstable in normal combustion, near the limit, the flame blows out and disappears due to a slight change in the air ratio value or the air flow velocity, for example). However, when high-temperature air is diluted with an inert gas to reduce the oxygen concentration, the flame is not easily extinguished and does not blow out. At the temperature that causes such a phenomenon, that is, at a temperature lower than this, it becomes difficult to completely burn the exhaust gas even if it does not blow out. The temperature at which combustion becomes unstable due to the presence of components is referred to as the combustion stability limit temperature in this specification). Once in the combustible range Te, starts receiving of or spontaneously combust help of flame holding mechanism. Moreover, since the oxygen concentration is much lower than that of normal air and the volume of dilution air is considerably large, the heat generation rate is accompanied by an oxidative exothermic reaction whose heat generation rate is sufficiently lower than that of normal combustion. For this reason, the oxidation exothermic reaction is maintained over a wide area in the furnace, and stable combustion is continued. In the process of generating sensible heat, heat is deprived and the object to be heated in the furnace is heated. In addition, the flame volume is significantly increased by the low-oxygen-concentration and high-temperature dilution air, so that the hot gas flow rate increases,
Dramatically improve convective heat transfer.

The present invention is based on this finding, and the invention according to claim 1 is directed to a burner combustion method in which an oxidizing agent and a fuel are brought into contact in a furnace to diffuse and burn, and at least immediately before the combustion reaction. Diffusion combustion is performed using high-temperature diluted air having an oxygen concentration much lower than that of ordinary air and having a combustion stability limit temperature or higher at the oxygen concentration or an oxidizing agent corresponding thereto.

In this diffusion combustion, diffusion combustion takes place under a sufficiently low-speed oxidative exothermic reaction, and the oxidative exothermic reaction is constantly caused even during the flow of the hot gas to continue burning over a wide range. A flame that stably burns at a much larger volume than sometimes is formed. And
This large-volume flame sustains an oxidative exothermic reaction over a wide area without generating a heat flux peak.It is heated by convective heat transfer and radiation heat transfer while generating sensible heat in a wide area or almost the entire area of the furnace. Things can be heated.

Further, according to the present invention, when a hydrocarbon-based fuel or a fuel containing a hydrocarbon is used as the fuel under the above-described high-temperature air combustion, the visible light emission of the flame generated by the diffusion combustion. The ratio of the intensity of the green emission spectrum to the intensity of the blue emission spectrum in the color is remarkably increased compared to the case where air and fuel at normal temperature are diffused at normal oxygen concentration, and the flame is turned to green. To maintain.

According to a third aspect of the present invention, when a fuel containing no hydrocarbon is used as a fuel, the flame is turned green by adding a hydrocarbon-based fuel or a hydrocarbon as a marker to the fuel. It is possible to maintain combustion in a state.

The combustion reaction intermediate product of the hydrocarbon fuel under the high-temperature air combustion emits a unique radical luminescence for each combination of the oxidizing agent temperature and the oxygen concentration, even if the fuel composition and the equivalence ratio are constant. radical component generated, that is, contains the C ₂ radical component issuing the emission spectrum of the CH radical component and green issuing blue light spectrum.
Then, when it is recognized that the ratio of the green emission spectrum intensity to the blue emission spectrum intensity is significantly increased compared to the case of normal diffusion combustion and the flame is greened, at least immediately before the combustion reaction, The supplied air or the corresponding oxidant has a much lower oxygen concentration than ordinary air and a high temperature equal to or higher than the combustion stability limit temperature at that oxygen concentration, and has a heat generation rate higher than that of ordinary diffusion combustion. Combustion with a sufficiently slow oxidation exothermic reaction,
That is, high-temperature air combustion occurs stably and reliably.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail based on an example of an embodiment shown in the drawings.

First, considering the combustion stabilization conditions of high-temperature air combustion combining air high temperature and gas recirculation,
As mentioned above, the essential factors can be seen as the temperature of the oxidant and the oxygen concentration. As is apparent from the results of FIG. 8 in which the combustible range of a diffusion flame using hydrocarbon gas as a fuel changes depending on the high-temperature dilution air temperature and its oxygen concentration, as is clear from the results of FIG. The relationship between the temperature of the air as the oxidant and the heat recirculation amount, that is, the oxygen concentration of the dilution air, is such that the higher the temperature of the combustion oxidant, the greater the gas recirculation amount, in other words, the combustion oxidant. -It can be understood that if the temperature of the dilution air is high, there is a relationship that combustion is established even if the oxygen concentration is lowered.

Here, in order to perform stable combustion with an extremely large flame volume, that is, to make the oxidation exothermic reaction sufficiently slow, the oxygen concentration should be lower than that of ordinary air as much as possible, and the temperature of the combustion oxidizer should be kept low. It needs to be as high as possible. For example, it is about 15% or less, more preferably about 10% or less, and most preferably about 5 to 3%. Further, the temperature of the dilution air is at least the combustion stability limit temperature of the air-fuel mixture at the oxygen concentration, and preferably the auto-ignition temperature of the air-fuel mixture at the oxygen concentration. Incidentally, the self-ignition temperature of the air-fuel mixture varies depending on the oxygen concentration of the oxidizing agent for combustion and the type of fuel. For example, in the case of LPG (C ₃ H ₈ 97%), as shown in FIG. The temperature is about 850 ° C. or more at about 15%, about 880 ° C. at about 10% oxygen concentration, and about 1000 ° C. at about 3% oxygen concentration. Further, at least the temperature of the diluted air immediately before the combustion reaction is higher than the combustion stability limit temperature at each oxygen concentration, but a temperature that requires a flame holding mechanism, for example, a temperature of 600 ° C. or more at an oxygen concentration of 15% or less and an oxygen concentration of 10% or less. % Or less and 800 ° C. or more. Also in this case, it was recognized that the ratio of the increase in the green emission spectrum component to the blue emission spectrum component in visible light emission was small, but larger than that in normal combustion.

The high-temperature air and the flue gas are mixed before being brought into contact with the fuel in the furnace, and supplied as high-temperature diluted air at a predetermined temperature and a predetermined oxygen concentration. Here, it is economical and practical to use dilution air in which the oxygen concentration of the combustion air having an oxygen concentration of 21% is diluted by exhaust gas strongly circulating in the furnace. In addition, the air nozzle and the fuel nozzle are arranged so that air and fuel are separately injected directly into the furnace, and diffused and mixed in the furnace. Since the air injected from the air nozzle into the furnace has a high temperature, the capacity thereof is much larger than that of the conventional one, and the air is injected at a high speed of, for example, 60 to 100 m.
/ S or higher. Therefore, it is desired that the exhaust gas in the furnace is involved in the air jet to adjust to a predetermined oxygen concentration. It should be noted that the air as the oxidizing agent is used so that the total amount of the oxidizing agent completely burns even immediately before the combustion reaction, even if the oxygen concentration is much lower than that of the normal air, for example, about 5 to 3%. The ratio is set.

FIG. 1 to FIG. 6 show the results of observation of combustion states in which the oxygen concentration of air and the preheating temperature are different. 2 to 4 show the same fuel (LP) using a combustion oxidizer having an oxygen concentration of 10%.
G) shows a case where diffusion combustion is performed at different temperatures.
According to these observation results, the temperature at 960 ° C. (see FIG. 3) was 10% higher than that at 880 ° C. (see FIG. 4).
In the case of 00 ° C. (see FIG. 2), a combustion reaction intermediate product having a larger flame volume and emitting more green emission spectrum components was observed, and as a result, a greenish flame was observed. Was done. That is, as the dilution air temperature increases, the ratio of the combustion reaction intermediate product of the hydrocarbon fuel that emits a green emission spectrum component to the combustion reaction intermediate product that emits a blue emission spectrum component increases, and during the visible light emission, The influence of the occupied green emission spectrum is relatively large so that it can be visually recognized, and the tendency of the flame to turn green is strengthened.

Further, comparing the case of 3% oxygen concentration in FIG. 1 with the oxygen concentration of 10% in FIG.
It is clear that even at 0 ° C. and 1000 ° C.), the lower the oxygen concentration, the greater the flame volume. Also in this case, the oxygen concentration is lower, that is, the oxygen concentration is 3%.
The ratio of the combustion reaction intermediate product that emits a green emission spectrum component to the combustion reaction intermediate product of hydrocarbon fuel that emits a blue emission spectrum component increases, and the green emission spectrum occupies the visible emission. It was recognized that the influence of was relatively large enough to be visually recognized, and the tendency of the flame to turn green was strengthened. On the other hand, when the oxygen concentration was 21%, which is the same as that of ordinary air, at the same oxidizing agent temperature, the flame volume was small as shown in FIG. Furthermore, the same fuel (LPG) is used with an oxygen concentration of 21%,
When diffusion combustion is performed using combustion air at a temperature of 50 ° C. (see FIG. 6), a combustion intermediate reaction product that emits a blue emission spectrum component (430 to 460 nm) in the visible emission color of the flame is used. Since the proportion of the combustion reaction intermediate product that emits a green emission spectrum component is overwhelmingly small, the flame color has a so-called blue flame. Then, as shown in FIG. 7, the same fuel is diffused and burned using combustion air having an oxygen concentration of 21% and a temperature of 50 ° C. (flame indicated by a solid line), and a high temperature of an oxygen concentration of 3% and a temperature of 1010 ° C. In the case of diffusion combustion using the dilution air (flame indicated by a virtual line), the difference in the flame volume was roughly 20 times or more. Moreover, in the visible emission color of the flame having a large volume, a relatively large amount of a combustion reaction intermediate product of the hydrocarbon fuel which emits a green emission spectrum component was recognized, and as a result, the color of the flame became greenish. From this, it was found that when the oxygen concentration was lowered, the above-described phenomenon of the relative increase in the green emission spectrum component became remarkable.

This is clear from the results of flame spectroscopy shown in FIGS. 9 and 10. For example, air is diluted with nitrogen gas to 5.1% O ₂ , and LPG is used as a fuel.
The result of FIG. 9 was obtained by measuring the flame emission spectrum when the temperature was changed to ° C. Visual observation of the flame showed that the color changed from blue to blue-green as the dilution air temperature increased, but it could be quantitatively grasped by spectrum measurement. However, spectroscope and C
Since the sensitivity of the CD has not been corrected, a relative comparison is made for each condition. Further, a CH radical (431.5 nm) as a blue emission spectrum component and one C ₂ radical (516.5) in a C ₂ swan band as a green emission spectrum component
nm), the change with respect to the dilution air temperature at 5.1% O ₂ and 21% O ₂ was examined. According to FIG. 10, it can be seen that the C ₂ radical emission intensity increases as compared with the CH radical due to the dilution air temperature.

From this, it can be seen that while the temperature of the combustion air is much higher than that used in the conventional exhaust gas recirculation combustion method, the oxygen concentration as the combustion oxidizing agent is higher than that of ordinary air without changing the air ratio. If the temperature is reduced far below, when a certain condition is reached, a phenomenon occurs in which the oxidative exothermic reaction burns stably despite the fact that it is very slow as compared with the case where normal air is used. It can be understood that as a result of obtaining a combustion reaction intermediate product of the hydrocarbon fuel which emits a green spectral component in the visible light emission color, a flame which is greener (greener) than blue during normal combustion is generated.

As one of the methods for economically and easily supplying high-temperature diluted air and an oxidizing agent diluted to a predetermined temperature and a predetermined oxygen concentration, a high-temperature air having an oxygen concentration of 21% is supplied to a furnace at a high speed. A method may be considered in which the exhaust gas is injected into the furnace to dilute the furnace exhaust gas to a predetermined oxygen concentration at least before contact with the fuel. However, it is impossible to predict or calculate how much exhaust gas is caught in the high-speed air jet, and it is difficult to set the oxygen concentration and the temperature of the dilution air immediately before the combustion reaction to predetermined values. Moreover,
Conventionally, there is no means for measuring the oxygen concentration and the temperature of the diluted air in the diffusion state immediately before the combustion reaction.

However, the proportion of the combustion reaction intermediate product of the hydrocarbon fuel which emits a green emission spectrum component in the flame with respect to the combustion reaction intermediate product of the blue emission spectrum component increases sharply, and is increased in the visible emission color. As a result, when a greenish flame is formed, at least immediately before the combustion reaction, a predetermined dilution having a much lower oxygen concentration than ordinary air and a temperature higher than the combustion stability limit temperature at the oxygen concentration. It can be presumed that air and fuel are mixed and diffused to cause diffusion combustion (high-temperature air combustion) under a sufficiently low-speed oxidative heat generation reaction. That is, high-temperature air combustion can be stably realized by controlling the preheating temperature of the air, the recirculation amount of the gas in the furnace, and the like, so long as a flame that is greener than a so-called blue flame during normal combustion is continuously produced.

Therefore, for example, by adjusting the injection angle of a nozzle for injecting the combustion air, the amount of the in-furnace gas involved before the collision with the fuel jet is changed to change the oxygen concentration of the dilution air immediately before the combustion reaction. By adjusting the oxygen concentration or adjusting the oxygen concentration by injecting a weak oxidizing gas or an inert gas before jetting into the furnace, the combustion is maintained so that the flame turns green. The flame when the preferred high-temperature air combustion as shown in FIG. 1 is realized, that is, the ratio of the green emission spectrum intensity to the blue emission spectrum intensity in the visible emission color is significantly increased as compared with the normal combustion. The flame that is recognized as having
The color was greenish enough to be clearly distinguished visually from blue (blue flame) generated during normal combustion.

The above embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, as the oxidizing agent for combustion, it is practical to use, for example, one obtained by diluting the oxygen concentration in the combustion air by exhaust gas recirculation in a furnace, but is not particularly limited thereto. A gas other than air containing a certain amount of oxygen or more may be used by diluting it with another different gas, or air diluted with a diluent gas such as an inert gas. In the case of a burner system using an oxidizing agent for combustion using exhaust gas, although not shown, for example, a part of the combustion gas is returned to the burner side through a circulation path outside the furnace and the remaining is discharged. Combustion that uses the sensible heat of the combustion gas to preheat the combustion air with a heat exchanger such as a regenerator and mixes the preheated combustion air with the recirculated combustion gas to produce a green emission spectrum component The high-temperature dilution air having the oxygen concentration and the temperature at which the reaction intermediate product is obtained is supplied at a volume that does not change the air ratio required for complete combustion.

In this embodiment, the combustion of a fuel containing a hydrocarbon such as a hydrocarbon fuel and a city gas is mainly described. However, the present invention is not particularly limited to this, and the fuel containing no hydrocarbon such as a hydrogen fuel is used. It can also be applied to combustion using.
In this case, by adding a hydrocarbon-based fuel or hydrocarbon as a marker to the fuel, a combustion intermediate product having a blue emission spectrum and a green emission spectrum in the visible emission color of the flame generated by diffusion combustion is obtained. It can also be implemented to maintain the combustion in a state that causes the flame to turn green.

[0031]

As is clear from the above description, according to the burner combustion method of the present invention, the oxygen concentration is much lower than that of ordinary air at least immediately before the combustion reaction, and the Since the mixture is diffused and burned with high-temperature diluted air having a temperature equal to or higher than the combustion stability limit temperature of the air-fuel mixture or an oxidizing agent corresponding thereto, stable combustion can be performed while significantly increasing the flame volume under a sufficiently low-speed oxidative heat generation reaction. Therefore, without creating a heat flux peak,
An object to be heated can be heated by convective heat transfer and radiant heat transfer while generating sensible heat in almost the entire area of the furnace. In addition, there occurs a phenomenon that the oxidation exothermic reaction is stably burned although it is very slow as compared with the normal combustion. And
Combustion gas, which has a high flow velocity and continues to burn over a wide area, has a significantly higher flow velocity in the furnace than ever before to improve convective heat transfer, and continues to burn continuously while flowing in a wide area within the furnace. Heat is deprived in the process of generating heat, and the object to be heated is heated. In addition, the gas flow becomes more intense than during normal combustion, which promotes mixing of the gas in the furnace and increases the amount of convective heat transfer, thereby further eliminating the local temperature difference.

According to the first aspect of the present invention, since the maximum flame temperature is greatly reduced, the generation of NOx can be largely suppressed (about 100 to 10 ppm) and the average heat flux can be increased close to the maximum heat flux. Heating efficiency (heat transfer efficiency) is significantly improved. Further, since the oxidation exothermic reaction is sufficiently slow, combustion noise and vibration combustion can be suppressed.
If the temperature field is flattened and the heat transfer rate is increased, the heat transfer performance can be significantly improved, such as downsizing the furnace or shortening the heating time.

According to the second aspect of the present invention, by maintaining the combustion in a state where the flame turns green, at least the combustion reaction is performed regardless of the supply state of the air used for combustion or the oxidizing agent corresponding thereto. Immediately before, while the oxygen concentration is much lower than that of ordinary air and the temperature is higher than the combustion stability limit temperature at that oxygen concentration, the oxidation exothermic reaction has a sufficiently low heat generation rate compared to normal combustion. A stable combustion state can be reliably realized.

According to the third aspect of the present invention, even if the fuel does not emit a green emission spectrum component in the flame, the flame is added by the hydrocarbon-based fuel added as a marker or the combustion reaction intermediate product generated from the hydrocarbon. Can be made green, so that a stable combustion state can be reliably realized despite the oxidative exothermic reaction having a sufficiently low heat generation rate as compared with normal combustion.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a state of a flame when an oxidizing agent for combustion having an oxygen concentration of 3% and a temperature of 1010 ° C. is used.

FIG. 2 is an explanatory diagram showing a state of a flame when an oxidizing agent for combustion having an oxygen concentration of 10% and a temperature of 1000 ° C. is used.

FIG. 3 is an explanatory diagram showing a state of a flame when an oxidizing agent for combustion having an oxygen concentration of 10% and a temperature of 960 ° C. is used.

FIG. 4 is an explanatory diagram showing a state of a flame when an oxidizing agent for combustion having an oxygen concentration of 10% and a temperature of 880 ° C. is used.

FIG. 5 is an explanatory diagram showing a state of a flame when an oxidizing agent for combustion having an oxygen concentration of 21.0% and a temperature of 1000 ° C. is used.

FIG. 6 is an explanatory diagram showing a state of a flame when an oxidizing agent for combustion having an oxygen concentration of 21.0% and a temperature of 50 ° C. is used.

FIG. 7 shows a state of a flame when an oxidizing agent for combustion having an oxygen concentration of 3% and a temperature of 1010 ° C. is used, and a state of a flame when an oxidizing agent for combustion having an oxygen concentration of 21.0% and a temperature of 50 ° C. is used. It is explanatory drawing which compares.

FIG. 8 is a graph showing the influence of the temperature and oxygen concentration of a combustion oxidizer on combustion stability.

FIG. 9 is a graph showing a relationship between an air temperature and a flame emission spectrum.

FIG. 10 is a graph showing changes in CH / C ₂ radical emission intensity in air temperature.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Susumu Mochida 2-1-153 Shirite, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside Japan Furness Industrial Co., Ltd. (72) Inventor Hirokazu Katsushima 2-1-1 Shirite, Tsurumi-ku, Yokohama-shi, Kanagawa No. 53 Inside Japan Furnace Industry Co., Ltd.

Claims (3)

[Claims] In a burner combustion method in which an oxidant and a fuel are brought into contact in a furnace to diffuse and burn in a furnace, at least immediately before the combustion reaction, the oxygen concentration is much lower than ordinary air, and A burner combustion method characterized by diffusing and burning with a high-temperature dilution air having a combustion stability limit temperature or higher or an oxidizing agent corresponding thereto under a sufficiently low-speed oxidative exothermic reaction. 2. A ratio of a green emission spectrum intensity to a blue emission spectrum intensity in a visible emission color of a flame generated by diffusion combustion when a hydrocarbon-based fuel or a fuel containing a hydrocarbon is used as the fuel. 2. The burner combustion method according to claim 1, wherein the combustion is maintained at a state in which the flame is turned green by increasing the air and fuel at a normal oxygen concentration and at a normal temperature by diffusion combustion. . 3. In the case where a fuel containing no hydrocarbon is used as the fuel, a visible light emission color of a flame generated by diffusion combustion is supplied by adding a hydrocarbon-based fuel or a hydrocarbon as a marker to the fuel and supplying the fuel. The ratio of the green emission spectrum intensity to the blue emission spectrum intensity in the inside is significantly increased compared to the case of diffusing and burning air and fuel at normal oxygen concentration and normal temperature, and the combustion is turned to a state in which the flame turns green. The burner combustion method according to claim 1, wherein the burner combustion is maintained.