JPS5838685B2 - burner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a burner capable of suppressing NOx generation and reducing emissions of unburned substances such as CO9HC.

Currently, from the viewpoint of preventing air pollution, strict regulations are required regarding the NOx emission concentration of various types of combustion equipment, and there is an urgent need to develop low NOx burners that can meet these demands.

As a typical example of a conventional burner, FIG. 1 shows a vertical cross-sectional view of a gas/heavy oil mixed combustion burner.

In the figure, 101 is gas, 102 is heavy oil, 103 is a spud gun type gas injection valve, 104 is a heavy oil injection valve, 105
is a wind box, 106 is a foreign exchanger, 107 is an inner cylinder, 1
08 is a regular FT, m, 109 hash register vane, 110 hash throat, 111 is secondary air, 112 is tertiary air, 11
3 is the inside of the furnace, and 114 is the burner front plate.

The conventional gas/heavy oil co-firing burner having such a configuration has the following problems.

(1) The burner shown in Figure 1 enables stable combustion in a wide range of air, but it uses two-stage combustion to reduce the burner air ratio to 1.
If it is less than that, the amount of CO in the exhaust gas will increase, and the mixture of fuel and air will not be sufficient even as a burner.

(2) Conventional combustion air and exhaust gas are stored in the wind box 105
Since the air is mixed uniformly in the upstream air duct, the first
The burner shown in the figure does not have a structure that performs so-called local exhaust gas mixing, in which exhaust gas is introduced singly near the fuel injection port.

However, since local exhaust gas mixing can mix more concentrated exhaust gas into the flame than conventional uniform exhaust gas mixing, the NOx reduction effect can be improved as long as the overall exhaust gas circulation amount is the same.

The present invention solves the above-mentioned drawbacks of conventional burners, and provides a burner that can suppress NOx generation and reduce emissions of unburned substances such as Co and HC. A water-cooled auxiliary combustion chamber is provided at the inlet of the burner tile, and a heavy oil injection valve with a tiff user is arranged at the center of the burner tile inlet. An air port, a combustion exhaust gas port, a fuel gas nozzle, and a secondary air port are each opened, and a tertiary air port is provided on the outer periphery of the outlet of the water-cooled sub-combustion chamber, and the heavy oil flow injected from the heavy oil injection valve or the fuel gas nozzle is Alternatively, the gas jet flow is made parallel to the primary air flow from the primary air port and the combustion exhaust gas flow from the combustion exhaust gas port, and intersects with the secondary air swirl flow from the air port having a stoichiometric air ratio or less, and the water cooling A circulating flow is formed in the water-cooled sub-combustion chamber by colliding with the wall of the sub-combustion chamber, and the tertiary air flow ejected from the tertiary air port is made to intersect with the burner center line in the furnace. There is a burner, which is said to be.

Next, the present invention will be explained with reference to the drawings.

FIG. 2 is a longitudinal sectional view of one embodiment of the present invention, FIG. 3 is a view taken along the line A-A in FIG. 2, FIG. 4 is an enlarged view of section B in FIG. 2, and FIG. It is a CC arrow view of FIG.

First, the burner configuration of the present invention will be described.

The burner of the present invention has an auxiliary combustion chamber 5 equipped with water cooling @ 5a in the burner tile 6 in the wind box 15, and a heavy oil injection valve 4 with a knife user 18 attached at the center of the burner tile 6. The primary air port 10b of the primary air pipe 10a, the combustion exhaust gas port 3a of the combustion exhaust gas pipe 3, and the fuel gas nozzle 1a of the gas fuel pipe 1 are arranged concentrically outward around the heavy oil injection valve 4. and secondary air pipe 202
It has a structure in which the secondary air ports 2a are opened respectively, and the direction of the heavy oil jet or gas jet injected from the heavy oil injection valve 4 residue or the fuel gas nozzle 1a is the same as that from the primary air port 10b and the combustion exhaust gas port 3a, respectively. It is parallel to the direction of the primary air flow and the combustion exhaust gas flow, and almost perpendicularly intersects with the direction of the secondary air swirl flow, which is narrowed down to a stoichiometric air ratio or less, ejected from the secondary air port 2a, and furthermore, the water cooling of the sub-combustion chamber 5. It collides with the inner wall of the wall 5a, thereby forming a circulating flow within the auxiliary combustion chamber 5.

Next, the operation of the burner of the present invention will be described.

That is, the fuel gas passes through the fuel gas introduction pipe 13 attached to the burner front plate 17 and is introduced into the gas fuel pipe 1.
The fuel gas is injected from the fuel gas nozzle 1a.

The combustion exhaust gas is introduced into the combustion exhaust gas pipe 3 through the combustion exhaust gas introduction pipe 14 and is ejected from the combustion exhaust gas slot 3a.

The air in the wind box 15 is introduced into the secondary air pipe 2 via the secondary air introduction pipe 8 and the secondary air conditioning damper 9, is swirled by the secondary air swirler 12, and is ejected from the secondary air port 2a. .

The injection direction of the fuel is set at an acute angle to the burner center line and parallel to the primary air flow from the primary air port 10b and the combustion exhaust gas flow from the combustion exhaust gas port 3a, and the secondary air port 2
The air is injected almost perpendicularly to the secondary air swirl flow having a stoichiometric air ratio or less from a.

The combustion exhaust gas port 3a is arranged near the fuel gas nozzle 1a and the heavy oil injection valve 4, and is configured to mix the combustion exhaust gas into the fuel jet.

Therefore, while the fuel collides with the inner wall of the water-cooled wall 5a of the sub-combustion chamber 5, it mixes with these primary air, secondary air and combustion exhaust gas to some extent, but this is not caused by the swirling motion of the secondary air flow. , due to the circulation H promoted by the fuel jet, a reverse flow occurs in the center of the sub-combustion chamber 5 and a countercurrent flow near the inner wall of the water-cooled wall 5a, so that these mixtures are caused by the water-cooled wall 5a.
The fuel is further advanced along the inner wall of the combustion chamber 5, and primary combustion occurs within the sub-combustion chamber 5.

Note that an arbitrary number of openings may be provided in the water-cooled wall 5a to guide the air in the wind box 15 to the sub-combustion chamber 5.

Regarding the fuel gas nozzle 1a, small holes with different areas are arranged alternately around the center axis of the burner, and the shape of the small holes is approximately rectangular so as to increase the contact area between the fuel gas and the air, and the longitudinal direction thereof is The direction is made to match the direction of the secondary air flow at the secondary air port 2a.

As an example of the shape of the fuel gas nozzle 1a, as shown in FIG. 5, it is also possible to combine a rectangle and a square (joint shape of a rectangle and a circle) and arrange these alternately on the circumference. .

In this way, by selecting the fuel injection direction, fuel nozzle arrangement, and nozzle shape, the flow of fuel, air, combustion exhaust gas, and the above-mentioned circulation fJ can be controlled.
Actively mix JWt.

The water-cooled I5a of the sub-combustion chamber 5 is composed of, for example, a pipe, which lowers the temperature of the primary combustion flame formed along the inner wall of the water-cooled wall 5a and suppresses NOx generation. Its role is to keep the inner wall surface temperature within the heat-resistant temperature range.

In the burner of the present invention, a swirler 7 for tertiary air and a tertiary air chamber 7a are further provided on the outer periphery of the outlet portion of the sub-combustion chamber 5,
The tertiary air, which has been swirled by the secondary air swirler 7, passes through the tertiary air lower a and is ejected in a contracted flow in the direction intersecting the burner center axis and the furnace interior 16, thereby increasing the tertiary air flow. The flame at the outlet of the sub-combustion chamber 5 is penetrated well, and the primary combustion gas is further safely and completely secondary-combusted in the furnace, thereby suppressing the generation of unburned components such as CO and HC.

The tertiary air swirler 7 may be variable in its rotation like a conventional resistor vane, or may have a structure in which the tertiary air injection direction is variable.

The air in the wind box 15 may be mixed with flue gas in a conventional manner.

The tiff user 18 attached to the heavy oil injection valve 4 is configured to have a widening angle parallel to the outlet end of the primary air pipe 10a, and the injection angle of the heavy oil injected from the heavy oil injection valve 4. is the same angle as the tiff user 18 or a spread angle close to it.

Primary air is supplied from the wind box 15 through the primary air introduction pipe 1
0. The primary air pipe 10 passes through the primary air conditioning damper 11
a, and is ejected from the primary air port 10b toward the auxiliary combustion chamber 5.

FIG. 6 is an example of a song that can be played in the auxiliary combustion chamber.

That is, the heavy oil injection valve 4 is located at the center of the inlet of the sub-combustion chamber 50.
A primary air port 10b is arranged around it, an annular passage is provided on its outer periphery, and this annular passage is radially extended 4n (n is an integer,
In the figure, it is divided into n-2), with a secondary air port 2a and an exhaust gas port 3a.
, fuel gas nozzle 1a1 combustion exhaust gas hole 3a, secondary air port 2
As shown in a..., this is a structure in which exhaust gas ports are arranged on both sides of a fuel nozzle, and secondary air ports are arranged on both sides of the fuel nozzle in order on the circumference.

The effects of the present invention are as follows.

(1) Fuel is sufficiently mixed with air at a ratio below the stoichiometric air ratio in the sub-combustion chamber to cause primary combustion, and then tertiary air is jetted out so as to penetrate into the primary combustion flame at the outlet of the sub-combustion chamber. Since complete secondary combustion is performed, the primary air ratio can be made sufficiently low, that is, the secondary combustion can be strengthened, and therefore, NOx generation can be effectively suppressed, and Co, HC, etc. can significantly reduce emissions of unburned matter.

(2) Local combustion exhaust gas mixing in the sub-combustion chamber makes effective use of the combustion exhaust gas, so the NOx reduction effect on the combustion exhaust gas mixture ratio can be increased.

(3) By water-cooling the auxiliary combustion chamber, the temperature of the primary combustion flame can be lowered, thereby reducing NOx.

(4) A strong circulation flow is formed in the sub-combustion chamber, and the combustion generated gas, which contains almost no air, flows backwards and is supplied to the primary combustion flame, resulting in the same effect as exhaust gas mixing. .

(5) Since the combustion device itself is capable of performing two-stage combustion, the conventional air port for two-stage combustion can be omitted.

(6) It is possible to co-combust heavy oil and gas, that is, by simultaneously burning heavy oil as the main fuel and gas as an auxiliary fuel, the heavy oil is gasified and combusted in the auxiliary combustion chamber, making it possible to strengthen two-stage combustion. NOx can be reduced.

As described above, the present invention provides primary combustion under the mixing of air and combustion exhaust gas below the stoichiometric air ratio, cooling of the primary combustion flame by the water cooling wall of the auxiliary combustion chamber, and cooling of the primary combustion flame by the tertiary air. The present invention provides a burner that enables two-stage combustion consisting of complete combustion of the secondary combustion flame, thereby suppressing NOx generation and reducing emissions of unburned substances such as CO and HC, which is extremely useful in terms of air pollution. .

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of an example of a conventional gas/heavy oil mixed combustion burner, FIG. 2 is a vertical cross-sectional view of an embodiment of the present invention, and FIG.
A-A arrow view in the figure, Figure 4 is an enlarged view of part B in Figure 2, and Figure 5
The figure is a view along the line C--C in FIG. 4, and FIG. 6 is a schematic diagram of an embodiment of the curve of the sub-combustion chamber of the present invention. In the figure, 1...gas fuel pipe, 1a...
...Fuel gas nozzle, 2...Secondary air pipe, 2a.
...Secondary air port, 3...Fuel exhaust gas pipe,
3a...Fuel exhaust gas port, 4...Heavy oil injection valve, 5...Water-cooled auxiliary combustion chamber, 5a...
Sub-combustion chamber water cooling wall, 6... Burner tile, 6a.
・・・・・・Vernatile throat part, 7・・・・・・3
Secondary air swirler, 7a...Third air port, 8...
...Secondary air introduction pipe, 9...Secondary air adjustment pattern, 10...Primary air introduction pipe, 10a.
...Primary air pipe, 10...Primary air port,
11...Primary air conditioning damper, 12...
・Secondary air swirler, 13... Fuel gas introduction pipe, 14... Exhaust gas introduction pipe, 15... Wind box 16... Furnace interior, 17・・・・・・
... Burner front plate, 18 ... Tiff user, 1
01...Gas, 102...Heavy oil, 10
3... Spud gun type gas injection valve, 104...
...Heavy oil injection valve, 105 ... Wind box, 106 ... Outer periphery, 107 ... Cabinet, 108 ... Ordinary am, 109 ... ... Register vane, 110 ... Throat, 111.
...Secondary air, 112...Tertiary air, 1
13...Furnace interior, 114...Burner front plate.

Claims (1)

[Claims] 1. A water-cooled auxiliary combustion chamber is provided at the burner tile inlet in the wind box, and a heavy oil injection valve with a tiff user attached is placed in the center of the burner tile inlet, and the fuel oil injection valve is sequentially concentrically outwardly arranged around the heavy oil injection valve. A primary air port, a combustion exhaust gas port, a fuel gas nozzle port, and a secondary air port are opened toward the fuel oil injection valve or the fuel gas nozzle, and a tertiary air port is provided on the outer periphery of the outlet of the water-cooled sub-combustion chamber. The heavy oil flow or gas jet injected from the nozzle is converted into primary air a from the primary air port.
h, parallel to the combustion exhaust gas flow from the combustion exhaust gas port, intersect with the secondary air swirl flow having a stoichiometric air ratio or less from the secondary air port, and collide with the wall of the water-cooled sub-combustion chamber to cool the water-cooled sub-combustion chamber. A burner characterized in that a circulating flow is formed within a combustion chamber, and the tertiary air flow ejected from the tertiary air port is made to intersect with a burner center line within the furnace.