JPH08178226A - Gaseous fuel and oxygen burner - Google Patents

Abstract

PURPOSE: To make it possible to generate flames which increase brightness and provide a driving force. CONSTITUTION: In a gaseous fuel/oxygen burner, which discharges gaseous fuel from the central part and oxygen as a support fuel gas from its surrounding area, flow straightening pipes 3 formed with a bundle of thin-walled metal pipes 2 or honeycomb pipes are concentrically installed or deviatingly laid out near the tip of discharge nozzles 4 and 5 for either of gaseous fuel and oxygen or both or simply deviatingly and laid out. Furthermore, more than one burner of either type is installed to a furnace wall in parallel where the discharge directions of the gaseous fuel and oxygen are arranged to be parallel to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas fuel-oxygen burner used in a furnace mainly for radiation heat transfer such as a glass melting furnace.

[0002]

2. Description of the Related Art In a glass melting furnace, a burner that burns liquid fuel such as heavy oil or gaseous fuel such as natural gas with preheated air is used, and the melting method is mainly based on radiative heat transfer. .

When air is used as the combustion-supporting gas, nitrogen that does not contribute to combustion occupies most of the air, resulting in poor thermal efficiency. For this reason, the combustion air is usually preheated by using a heat storage chamber or a heat exchanger to improve the thermal efficiency, but this is not sufficient. In addition, the higher the temperature of the preheated air to improve the thermal efficiency, the more NOx is generated, which is a disadvantage. Furthermore, since the amount of combustion exhaust gas is large, a considerably large treatment facility is required for the treatment. From such a point, a burner using oxygen as a combustion-supporting gas has attracted attention and has been put into practical use.

[0004]

As described above, when oxygen is used as the combustion-supporting gas, the amount of combustion exhaust gas can be reduced, the thermal efficiency can be improved, NOx can be reduced, and the heat storage chamber can be eliminated. There are many problems, but there are problems to be solved before they can be used in melting furnaces that mainly use radiant heat transfer.

Generally, in oxyfuel combustion, the burning speed is high and a high temperature flame is generated. However, the brightness of the flame is usually low relative to the flame temperature, which is inconvenient for a melting furnace that mainly uses radiant heat transfer. The problem with such low brightness is
This becomes especially noticeable when using a gas fuel having a low carbon content such as natural gas. The term gaseous fuel as used herein means a gaseous fuel that contains carbon such as methane, ethane, propane, butane and natural gas and that can generate soot.

To increase the brightness of the flame, it is effective to use a laminar flow flame, as is well known. However, in order to satisfy the industrially practical combustion load and form a laminar flame, it is necessary to suppress the discharge speed from the nozzle to a low speed of several m / sec or less. In a flat furnace such as a glass melting furnace, a flame that extends in the horizontal direction is required, and at that time,
If the discharge speed from the nozzle is suppressed to a low speed of a few m / sec or less, the propulsive force of the flame becomes insufficient, the flame soars, and the roof of the furnace is damaged. Further, in order to increase the propulsive force of the flame, it is sufficient to increase the discharge speed from the nozzle, but the higher the discharge speed is, the more turbulent flame is generated and the brightness is lowered, which is a contradiction.

It is an object of the present invention to provide a gaseous fuel-oxygen burner which is capable of producing a high intensity, propulsive flame.

[0008]

In order to achieve the above object, the present invention provides a gas fuel-oxygen burner which discharges gas fuel from the center and oxygen from the surroundings as combustion-supporting gas. The present invention is characterized in that a rectifying tube composed of a plurality of tubular objects is provided in the vicinity of the tip of one or both of the discharge nozzles.

Further, according to the present invention, the gaseous fuel is fed from the central portion,
Gaseous fuel that discharges oxygen from its surroundings as combustion-supporting gas
In the oxygen burner, the gas fuel nozzle is eccentrically arranged with respect to the oxygen nozzle.

One or both of the eccentrically arranged oxygen nozzle and gas fuel nozzle is equipped with a straightening tube composed of a plurality of tubular objects near the nozzle tip.

In addition, a plurality of the above-mentioned burners are connected in parallel to the furnace wall so that the directions of discharge of the gaseous fuel and oxygen are substantially parallel.

[0012]

According to the present invention, in a gas fuel-oxygen burner that discharges a gaseous fuel from the center and oxygen from the surroundings as a combustion-supporting gas, a plurality of tubular members are provided near the tip of one or both of the gaseous fuel and oxygen. Since the discharge flow from the nozzle is close to a laminar flow due to the presence of the flow straightening pipe, since it has a flow straightening pipe composed of a substance, the mixing of the gaseous fuel and oxygen becomes slow and the brightness of the flame can be increased. . At the same time, the propulsive force of the flow also increases, so the flame rises less. In the present invention, the term "a plurality of tubular objects" refers to a state in which a plurality of tubular objects such as circular or polygonal shapes made of metal or ceramic are bundled or configured in a honeycomb shape, and the fluid flow is close to a laminar flow. It is to be understood as meaning a group of tubular objects for rectifying to.

By supplying oxygen and fuel in an eccentric form instead of concentric circles, the mixing of the gaseous fuel and oxygen becomes slower, and the brightness of the flame can be increased.

Further, by connecting a plurality of the above-mentioned burners to the furnace wall in parallel with the discharge directions of the gaseous fuel and oxygen being substantially parallel, the middle portion of each burner is in a lower pressure state than the surroundings. Therefore, the discharge flow of the gaseous fuel and the discharge flow of oxygen discharged from each burner are close to each other at the tips, and merge with each other. Since this merge point is the inner part of the furnace, the gas is formed in the inner part of the furnace. The mixing of fuel and oxygen can be promoted, the brightness of the flame can be increased, high temperature combustion can be performed, the amount of radiant heat transfer to the object to be melted can be increased, and the thermal efficiency can be improved.

[0015]

1 is a vertical sectional side view of a first embodiment of a gas fuel-oxygen burner according to the present invention, FIG. 2 is a vertical sectional front view taken along the line AA of FIG. 1, and FIG. 3 is a second embodiment of the present invention. An example vertical front view, FIG. 4 is a plan view showing a third embodiment of the present invention, FIG. 5 is a vertical front view of a rectifying tube used in the present invention, and FIG. 6 is a nozzle according to the present invention and a conventional nozzle. It is a comparative diagram which shows the flow velocity distribution of discharge fluid.

According to the research conducted by the present inventors, in order to increase the brightness of the flame in this type of gas fuel-oxygen burner, it is necessary to slow down the combustion reaction and generate a large amount of soot in the flame. For that purpose, it has been proved that it is most effective to make the mixing of fuel and oxygen as slow as possible, and the rectifying tube is an effective means.

In order to confirm the above points, as shown in FIG. 5, a thin metal thin tube 2 is provided in a metal outer tube 1 having a cylindrical cross section.
The characteristics of the discharge flow from the nozzle 4 provided with the straightening tube 3 formed by closely arranging the above in a tube bundle shape and the nozzle without the straightening tube (not shown) were investigated. FIG. 6 shows the flow velocity distribution of the discharge flow at a certain distance from the nozzle 4, and the solid line a is the straightening pipe 3.
Shows the flow velocity distribution curve of the nozzle provided with, and the dotted line b shows the flow velocity distribution curve of the nozzle without the rectifying tube 3. This Figure 6
From this, it can be seen that the discharge flow from the nozzle 4 provided with the flow straightening tube 3 has a higher flow velocity in the central portion and the flow is concentrated in a narrower region. At this time, the initial velocity of the discharge from the nozzle is the same, but it is clear that the provision of the flow straightening tube 3 increases the propulsive force of the discharge flow, and conversely, at a position apart from the nozzle 4 by a certain distance. Since the discharge initial velocity can be made lower in order to make the flow velocity the same, the Reynolds number indicating the degree of turbulence of the flow becomes small, and the flow can be closer to a laminar flow. In addition, smoke was caused to flow into the flow, and the flow patterns were visually confirmed and compared. Rectifier tube 3
When there is, the smoke goes straight for a relatively long time, but when there is not, the smoke flow is turbulent and not clear, and a clear difference is recognized. The fact that the smoke travels straight for a relatively long time means that the mixing of the gas is slow, so that the stoichiometrically excessive fuel (oxygen deficient) region in the central region becomes large and soot easily occurs. Therefore, the brightness of the flame becomes high.

Therefore, according to the present invention, as shown in the embodiment of FIGS. 1 and 2, the rectifying tube 3 for discharging the gaseous fuel to the central portion is used.
Is arranged, and the nozzles 5 for ejecting oxygen are arranged concentrically outside the nozzle 4 to form a gaseous fuel-oxygen burner.

The embodiment shown in FIG. 3 has a nozzle 5 for discharging oxygen.
And the nozzle 4 provided with the rectifying tube 3 for discharging the gaseous fuel is arranged in an eccentric form, not in a concentric shape.
When the gaseous fuel and oxygen are supplied by the burner of this embodiment,
Further, the area of excess fuel (lack of oxygen) can be increased.

The shape and installation position of the rectifying tube 3 were also examined and tested. As a result, the thin tube 2 forming the rectifying tube 3 does not need to be a circle, but the inner diameter of each thin tube 2 is 3 mm.
The following is preferable, and the length is 30 mm or more, preferably 100.
It was found that it was necessary to secure mm. Rectifier tube 3
The thinner the thin tube 2 constituting each element is, the better, but practically it is preferably 0.5 mm or less. Rectifier tube 3
It was also found that it is necessary to install the terminal end of the above in the vicinity of 0 to 100 mm from the discharge end of the nozzle 4.

By providing the rectifying tube 3 as described above, the discharge flow from the nozzle 4 becomes closer to the laminar flow.
The mixing of the gaseous fuel and oxygen becomes slow and the brightness of the flame can be increased. At the same time, the propulsive force of the flow also increases, so the flame rises less.

The burner of the first embodiment shown in FIGS. 1 and 2 has, for example, an outer diameter of 3 mm and a wall thickness of 0.5 mm at the center.
Rectifier tube 3 made of a bundle of heat-resistant steel thin tubes 2 with a length of 100 mm
The gas fuel flow path 6 having the above is formed, and the oxygen gas flow path 7 is formed concentrically around the gas fuel flow path 6.

This burner and the same burner except that the rectifying tube was used were used and the calorific value was 9000 Kc under the same combustion load.
When a gas of al / Nm ³ was combusted and compared, it was confirmed that the one having the rectifying tube 3 was obviously superior in both brightness and flame shape.

However, the combustion load is 600,000 Kcal / Hr.
When the amount is increased above, a decrease in brightness was recognized. In practice, a burner with a larger combustion capacity may be required, so that it is inconvenient.

Therefore, two burners according to the first embodiment were manufactured and, as shown in FIG. 4, the burners were tested adjacent to each other. The flame shape changes depending on how the two burners 8 and 9 are arranged on the furnace wall 10, but unless the two flames collide with each other, even if the combustion load is 600,000 Kcal / Hr or more as a whole, a flame with high brightness is generated. I was able to get it. The preferred flame shape depends on the application and cannot be determined uniformly, but it has been found that a burner equipped with a plurality of nozzles can handle a combustion load of 600,000 Kcal / Hr or more. In the case of the embodiment of FIG. 4 above, two burners 8, 9
Since the pressure in the middle part of the furnace is lower than that in the surroundings, mutual flames tend to approach each other at the tip part and merge, and this confluence point is the inner part of the furnace. It is possible to promote the mixing with and increase the brightness of the flame and to burn at high temperature.

Further, the gas fuel nozzle of the burner of the example was installed eccentric to the oxygen nozzle by 5 mm or 10 mm, and a combustion test was conducted. As the amount of eccentricity increased, the flame shape became non-axisymmetric, the reddish characteristic of incomplete combustion was partially recognized, and the color tone of the flame changed. Therefore, it was difficult to evaluate the brightness, but the amount of soot generated was increased, and it was found that the brightness was increased by increasing the oxygen flow rate.

Since oxygen is expensive, it is not preferable to consume much oxygen unnecessarily, but in some cases it is preferable to install the nozzle eccentrically. Normally, a plurality of burners are installed in the glass melting furnace and an exhaust gas flue is installed, so that the combustion gas flow of other burners also exists in the furnace. When a burner with a low discharge speed is used like the burner of the present invention, such a flow of combustion gas cannot be ignored, and oxygen on the outer periphery is particularly susceptible to the influence. In such cases, eccentricity may be more convenient.

Further, a burner (not shown) in which the rectifying tube 3 was added to the oxygen flow path 7 of the burner of the above-mentioned embodiment was also manufactured and a combustion test was conducted. The rectifying tube 3 in this case has the same outer diameter of 3 mm as that used for the gas fuel flow path 6,
A heat-resistant steel thin tube bundle having a wall thickness of 0.5 mm and a length of 100 mm was used. In this case, improvement in both brightness and flame shape was observed.
Although each of the above embodiments exemplifies the case where the circular thin tube 2 is used as the rectifying tube 3, other tube bundle shapes, for example, an elliptical shape, a quadrangular shape, a hexagonal shape, or any other suitable shape, or , May be used in combination, and may have a honeycomb shape.

[0029]

According to the first aspect of the present invention, since the discharge flow from the nozzle is close to the laminar flow due to the presence of the flow straightening tube, the mixing of the gaseous fuel and oxygen becomes slow, and the brightness of the flame can be increased. Therefore, it is expected that the energy efficiency will be improved in a furnace mainly for radiant heat transfer such as a glass melting furnace. At the same time, the propulsive force of the flow also increases, so that the flame does not rise so much and the damage to the roof of the furnace is reduced, so that the effect of extending the life of the furnace can be expected.

Further, according to the inventions of claims 2 and 3, the oxygen and the fuel are supplied in an eccentric form instead of being concentric.
Furthermore, the mixing of the gaseous fuel and oxygen becomes slower, and the brightness of the flame can be further increased.

Further, according to the invention of claim 4, a plurality of the above-mentioned burners are connected in parallel to the furnace wall with the jet directions of the gaseous fuel and oxygen substantially parallel to each other, and the intermediate portion of each burner is compared with the surroundings. Since it becomes a low pressure state, the jet flows of the gaseous fuel and oxygen jetted from each burner come close to each other at the tip parts and join, and this joining point becomes the inner part of the furnace. In the inner part of the furnace, it is possible to promote the mixing of gaseous fuel and oxygen, to increase the brightness of the flame, and to perform high temperature combustion, which can increase the amount of radiant heat transfer to the melted object and improve the thermal efficiency. .

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a first embodiment of a gas fuel-oxygen burner according to the present invention.

FIG. 2 is a vertical sectional front view taken along the line AA of FIG.

FIG. 3 is a vertical sectional front view of a second embodiment of the present invention.

FIG. 4 is a plan view showing a third embodiment of the present invention.

FIG. 5 is a vertical sectional front view of a rectifying tube used in the present invention.

FIG. 6 is a comparative diagram showing a flow velocity distribution of a discharge fluid between a nozzle according to the present invention and a conventional nozzle.

[Explanation of symbols]

 1 Metal Outer Tube 2 Metal Thin Tube 3 Rectifier Tube 4 Gas Fuel Discharge Nozzle 5 Oxygen Discharge Nozzle 6 Gas Fuel Flow Path 7 Oxygen Gas Flow Path 8, 9 Burner 10 Furnace Wall

Claims (4)

[Claims] 1. A gas fuel-oxygen burner which discharges a gas fuel from the center and oxygen as a combustion-supporting gas from the periphery of the gas fuel-oxygen burner. A gaseous fuel-oxygen burner, characterized in that it comprises a rectifying tube constructed. 2. A gas fuel-oxygen burner for discharging a gas fuel from the center and oxygen from the periphery as a combustion-supporting gas, wherein the gas fuel nozzle is eccentrically arranged with respect to the oxygen nozzle. Fuel-oxygen burner. 3. The gaseous fuel according to claim 2, wherein one or both of the oxygen nozzle and the gaseous fuel nozzle is provided with a rectifying tube composed of a plurality of tubular objects in the vicinity of the tip of the nozzle. -Oxygen burner. 4. The gaseous fuel-oxygen according to any one of claims 1 to 3, wherein a plurality of burners are connected in parallel to the furnace wall with the discharge directions of the gaseous fuel and oxygen substantially parallel. burner.