JP3059289B2 - Low nitrogen oxide boiler equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low nitrogen oxide boiler.

[0002]

2. Description of the Related Art There are various methods for reducing and burning nitrogen oxides (NOx), such as an exhaust gas recirculation combustion method, a two-stage combustion method, a two-stage fuel supply combustion method, a premixed combustion method, and a lean combustion method. There is a method. For example, as an example of an exhaust gas recirculation combustion method applied to a boiler device, Japanese Patent Application Laid-Open No.
There is one described in JP-A-6503 . This is a burning gas
Reciprocating up and down in the annular combustion chamber while turning
This is a typical example of the exhaust gas recirculation method performed by the above method.

[0003]

SUMMARY OF THE INVENTION Including such an example,
With conventional boiler equipment, the various nitrogen oxide reductions described above
Combustion methods are organically combined and performed.
Absent. The present invention has been made in view of the above points.
In other words, the premixed combustion method was developed in boiler equipment.
To ensure stable combustion of premixed gas and efficient transmission to water pipes.
For heat, two-stage combustion, two-stage fuel supply combustion, or lean-burn combustion
Is configured to be organically combined,
With the aim of reducing NOx through their synergistic action.
Things.

[0004]

[Means for Solving the Problems ] To solve the above-mentioned problems.
Therefore, the present invention provides a concentric inner water pipe group and an outer water pipe group.
When the water pipe groups are arranged to form an annular combustion chamber,
In the lower part of the annular combustion chamber, the annular combustion chamber is
On each cross section of the upper and lower stages to be cut, multiple nozzles,
The extension of the nozzle axis is in the tangential direction of the concentric circle.
From the multiple nozzles at the lower stage
As well as from the upper nozzles
Characterized by a structure that blows out any residual air
Things.

[0005] The present invention also provides an inner water tube group and an outer water tube group.
Arranged concentrically to form an annular combustion chamber between the water pipe groups
At the lower part of the annular combustion chamber.
On each cross section of the upper and lower stages across the firing chamber,
For the nozzle, the extension of the nozzle axis is the tangential direction of the concentric circle
From the lower nozzles.
Spouts the mixed gas, and from multiple nozzles at the top
Must be configured to eject the required residual fuel gas
It is characterized by the following.

[0006] The present invention also provides an inner water tube group and an outer water tube group.
Arranged concentrically to form an annular combustion chamber between the water pipe groups
At the lower part of the annular combustion chamber.
On each cross section of the upper and lower stages across the firing chamber,
For the nozzle, the extension of the nozzle axis is the tangential direction of the concentric circle
From the lower nozzles.
Spouts the mixed gas, and from multiple nozzles at the top
Must be configured to eject premixed gas rich in fuel
It is characterized by the following.

Further, according to the present invention, an inner water pipe group and an outer water pipe group are provided.
Are arranged concentrically, and the space between the water pipe groups is
At the lower part of the annular combustion chamber,
Each cross section of the upper and lower stages across the combustion chamber
The nozzle is oriented so that the extension of the nozzle axis is tangential to the concentric circle.
From the lower nozzles.
Premixed gas is blown out, and multiple nozzles
Are designed to eject fuel-lean premixed gas.
It is characterized by the following.

[0008]

[Function] Spouting from multiple nozzles arranged on the same cross section
The premixed gas flows between the inner tube group and the outer tube group.
A vortex is formed in the combustion chamber, ignited by this vortex,
A stable flame spreads throughout the body. Like this flame
Is ignited by the vortex and spreads over the entire cross section
This avoids local high temperatures. Also, all fuel
In the annular combustion chamber surrounded by the inner and outer water tubes
Therefore, part of the heat of combustion is transferred to the water tube group at the same time as combustion.
Heated, flame temperature decreases.

[0009] By the above operation, NOx can be reduced.
And multiple nozzles in the lower stage of the multiple stages
Premixed gas with different air ratio from multiple nozzles in the upper stage
Air or fuel from multiple nozzles
By injecting fuel gas, it is possible to use
A two-stage feed-fuel combustion is performed,
NOx reduction is measured.

[0010]

Next, an embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a boiler main body.
Inside, an inner water pipe group 2 and an outer water pipe group 3 are arranged concentrically and an annular combustion chamber 4 is formed between the water pipe groups 2 and 3. In the lower part of the annular combustion chamber 4, the plurality of nozzles 5 are configured so that the extension line of the nozzle axis is in the tangential direction of a concentric circle on each of the upper and lower sections crossing the annular combustion chamber 4. In the embodiment, the plurality of nozzles 5 are configured in two stages , upper and lower.
And that although, in consideration of the air ratio or the like of each stage, can optionally be a three or more stages. In the drawing, reference numeral 6 denotes a steam outlet, 7 denotes an exhaust port, and 8 denotes a water inlet.

In the above configuration, a premixed gas rich in fuel is supplied to the plurality of lower nozzles 5 so that the air ratio becomes, for example, λ = 0.5 to 0.7, and the premixed gas is supplied into the annular combustion chamber 4. ,
That is, the fuel is ejected between the inner water pipe group 2 and the outer water pipe group 3 , and the remaining nozzles necessary for complete combustion are output from the plurality of nozzles 5 in the upper stage.
Surplus air, that is, secondary air is supplied and injected into the annular combustion chamber 4.
Let out. In other words, the entire nozzle is
It is necessary to set the air ratio to, for example, about 1.05 to 1.1.
Expel remaining air.

[0012] However, in the lower section on the same cross section,
Premixing gas ejected from the nozzle 5 in the tangential direction of the concentric circle
The vortex forms a vortex along the annular combustion chamber 4, and by igniting the vortex, a flame is formed which spreads along the AA section in the figure. On the other hand, a plurality of nozzles on the BB section in the upper diagram
The secondary air jetted into the annular combustion chamber 4 from 5
A vortex is formed in the annular combustion chamber 4 in the same manner as the premixed gas, and the vortex of the air mixes well with the unburned portion in the combustion by the vortex of the premixed gas to complete combustion of the unburned portion. Offered
You.

The combustion gas burned as described above rises while swirling in the annular combustion chamber 4, and when it reaches a certain height, flows into the inside of the inner water pipe group 2, further rises and is discharged from the exhaust port 7. Is done. As described above, since the combustion gas swirls through the annular combustion chamber 4, heat transfer to the inner water pipe group 2 by convection heat transfer is effectively performed.

In the combustion of the above premixed gas, the primary
Due to large eddy current in the combustion chamber for both combustion and secondary combustion
There are no local hot spots to form a flame.
The effective cooling of the flame is promoted by the enhanced radiation heat transfer.
Will be Therefore, so-called premixed two-stage cooling combustion is ideal
To effectively suppress the generation of NOx.

Next, in the present invention, in the above configuration,
Contrary to the above, the fuel-lean premixed gas is ejected from the lower nozzle 5 and the remaining fuel gas, that is, the secondary fuel, is ejected from the upper nozzle 5, whereby the two-stage fuel supply combustion method is performed. Can be executed stably. Also in this case, the combustion of the premixed gas ejected from the lower nozzle 5 is described above.
As in the case of
No high-temperature part is formed, and flame cooling by radiant heat transfer
Effectively performed and therefore combined with two-stage fuel combustion
Ox generation can be significantly suppressed.

Next, according to the present invention, in the above configuration, the fuel-lean premixed gas is jetted from the lower nozzle 5 and the fuel-rich premixed gas is jetted from the upper nozzle 5 .
Or, conversely, the fuel flow from the lower nozzle 5
A rich premixed gas is blown out, and the fuel is
By injecting lean premixed gas, rich and
Can be performed, so-called PROMPT NO and THER
The generation of MAL NO can be suppressed. Also in this case
Combustion of premixed gas ejected from lower and upper nozzles 5
As described above, the flame is held by eddy current
No high temperature part is formed, and flame
Cooling is effective and therefore combined with the lean burn
The occurrence of x can be greatly suppressed.

The supply of the premixed gas to the nozzle is performed by fuel
And air are mixed in advance and each manifold is
In addition to supply, fuel and air are mixed in the nozzle and ejected
You may let it. In this case, the fuel and air in the nozzle
The means for mixing with can be of any conventional type.

In the present invention, the combustion described above is executed.
As a result, the amount of NOx generated can be reduced to as low as 10 to 30 ppm, which is a dramatic advance in view of the limit of about 60 ppm in the conventional apparatus. This is due to the unique configuration of the present invention.
Premixed gas, stable combustion and reduction of various NOx
Because the combustion methods are organically combined.
You.

[0019]

As described above, according to the present invention, the premixed gas is
Annular fuel between inner and outer water pipe groups arranged on concentric circles
Multiple nozzles in the tangential direction of concentric circles on the same cross section in the firing chamber
Whirls out of the vortex and ignites the vortex
Form a stable flame without the presence of more localized hot spots
It is possible to configure such a plurality of nozzles in multiple stages.
In addition to the above-mentioned premixed combustion, the two-stage combustion method,
Method that can be applied by organically combining the
As a result, the synergistic effect of these effects leads to significant NOx
Reduction can be measured.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of the present invention.

FIG. 2 is an explanatory cross-sectional view taken along lines AA and BB of FIG. 1;

FIG. 3 is an explanatory view taken along line CC of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boiler main body 2 Inner water pipe group 3 Outer water pipe group 4 Annular combustion chamber 5 Nozzle 6 Steam outlet 7 Exhaust port 8 Water inlet

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F23C 11/00 F22B 35/00

Claims (4)

(57) [Claims] An inner water pipe group and an outer water pipe group are arranged concentrically.
To form an annular combustion chamber between the water pipe groups,
Crosses the annular combustion chamber at the bottom of the annular combustion chamber
A plurality of nozzles are provided on each cross section of the upper and lower stages.
Constructed so that the extension line of the skewing axis is tangential to the concentric circle
And the premixed gas rich in fuel is
As well as multiple nozzles in the upper row
Nitrogen oxide low emission box configured to blow out residual air
Ira device 2. An inner water pipe group and an outer water pipe group are arranged concentrically.
To form an annular combustion chamber between the water pipe groups,
Crosses the annular combustion chamber at the bottom of the annular combustion chamber
A plurality of nozzles are provided on each cross section of the upper and lower stages.
Constructed so that the extension line of the skewing axis is tangential to the concentric circle
And fuel-lean premixed gas from the lower nozzles.
As well as multiple nozzles in the upper row
Low emission of nitrogen oxides configured to eject residual fuel gas
Raw boiler equipment 3. An inner water pipe group and an outer water pipe group are arranged concentrically.
To form an annular combustion chamber between the water pipe groups,
Crosses the annular combustion chamber at the bottom of the annular combustion chamber
A plurality of nozzles are provided on each cross section of the upper and lower stages.
Constructed so that the extension line of the skewing axis is tangential to the concentric circle
And fuel-lean premixed gas from the lower nozzles.
The fuel is ejected, and the fuel
Nitrogen oxide low emission configured to eject rich premixed gas
Raw boiler equipment 4. An inner water pipe group and an outer water pipe group are arranged concentrically.
To form an annular combustion chamber between the water pipe groups,
Crosses the annular combustion chamber at the bottom of the annular combustion chamber
A plurality of nozzles are provided on each cross section of the upper and lower stages.
Constructed so that the extension line of the skewing axis is tangential to the concentric circle
And the premixed gas rich in fuel is
The fuel is ejected, and fuel is diluted from the upper nozzles.
Nitrogen oxide low emission configured to eject thin premixed gas
Raw boiler equipment