JP2000193224A - Combustion device for exhaust gas including dust - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion device for an exhaust gas including dust capable of enhancing the mixture of air in a combustion chamber and avoiding a dust trouble or the like. SOLUTION: In a combustion device for an exhaust gas including dust, the exhaust gas to be burnt is introduced to a combustion chamber 2A in a tubular furnace body 1 to be burnt and an air nozzle 10 is provided in the furnace body 1 to generate a swirl flow in the circumferential direction in the combustion chamber. The air nozzle 10 is provided at such a position and in such a direction as to jet air on a trangential line to the circumferential configuration of an inner wall surface on an opening part 21 in the inner wall surface of the combustion chamber 2A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dust-containing exhaust gas combustion treatment apparatus.

[0002]

2. Description of the Related Art Exhaust gas generated when industrial waste or the like is incinerated in an incinerator contains flammable dust. This exhaust gas is subjected to a combustion treatment in a combustion treatment device. This apparatus is performed in a combustion furnace having a heating means such as an auxiliary burner, in which air for enhancing gas mixing in a combustion chamber in the furnace and for burning combustible substances in dust-containing exhaust gas is air. Supplied from nozzle.

The conventional combustion furnace of FIG. 5 of the accompanying drawings, which shows a cross section in a plane perpendicular to the furnace axis, has a cylindrical furnace body 51 and a swirl flow 53 in a combustion chamber 52. An air nozzle 54 for blowing air is provided to cause this. The air nozzle 54 is attached to the cylindrical pipe member at a finite angle θ with respect to a tangent T on the wall of the combustion chamber. Generally, this angle θ is about 30 to 45 °.
The swirling flow 53 generated by the air blown from the air nozzle 54 draws a circle whose radius is the distance a between the center line 55 of the air nozzle 54 and the furnace axis 56.

[0004] Thus, the exhaust gas is sufficiently mixed with the air by the swirling flow, and the combustion is improved.

[0005]

However, in the conventional apparatus shown in FIG. 5, the direction of air blowing 55 from the air nozzle 54 is at an angle θ with respect to a tangent T to the inner wall surface of the combustion chamber 52. Therefore, the following problems occur. The problem is more remarkable as the angle θ is larger.

[0006] Since the swirl radius a of the air is smaller than the radius of the combustion chamber, the rotational moment for swirling the air is reduced, and the mixing of the air is insufficient.

A stagnation region is generated at the opening of the air nozzle due to the generation of the vortex V, where dust in the exhaust gas is easily welded and solidified, and frequent cleaning must be performed.
This leads to a decrease in the operation rate of the apparatus, an increase in repair costs, and the like.

[0008] Due to the formation of the projections made of the solidified dust layer, drift occurs in the combustion chamber 52, and the stability of the flame in the combustion chamber is reduced, the stable range is narrowed, and a fire may occur. As a result, the concentration of harmful gases such as CO and dioxins in the exhaust gas increases, and the furnace pressure fluctuates during re-ignition.

In the stagnation region caused by the vortex V,
A local high-temperature region is easily formed, resulting in a high concentration of NOx and burning of furnace materials and burners.

[0010] Dust easily enters the air nozzle during low-load operation (when the operation is performed with a reduced air flow rate from the air nozzle).

When the concentration of combustible components in the exhaust gas to be treated is low, the air flow rate from the air nozzle decreases, and accordingly, the swirling flow in the furnace cannot be maintained.

An object of the present invention is to improve a dust-containing exhaust gas combustion treatment apparatus in consideration of these points.

[0013]

According to the present invention, an object of the present invention is to provide an apparatus for introducing exhaust gas to be burned into a combustion chamber inside a cylindrical furnace body for combustion, wherein the furnace body has an air nozzle. Wherein the air nozzle blows at a position tangent to the circumferential shape of the inner wall surface at the position of the opening in the inner wall surface of the combustion chamber. And direction.

According to the present invention having such a configuration, the blast from the air nozzle flows in contact with the inner wall surface of the combustion chamber immediately from the opening of the air nozzle. As a result, a swirling flow is generated in the combustion chamber without a vortex near the opening, and thus without a stagnation region. In addition, the turning radius is substantially equal to the radius of the inner wall surface and is large. As a result, the conventional problems caused by the occurrence of the stagnation region and the small turning radius can be solved at once.

According to the present invention, it is preferable that the air nozzle has a slit shape whose opening on the wall surface of the combustion chamber extends in the furnace axis direction. Even if the volume of air is limited, the swirl flow region also expands in the same direction by expanding the fume region in the furnace axis direction.

It is desirable that the air nozzle be provided with an adjusting member for adjusting the degree of opening of the opening. By doing so, even when it is necessary to reduce the amount of air in the fumarole, the amount of air can be adjusted under the condition that the nozzle blowing speed is constant, and the fluctuation width of the swirl flow velocity during furnace operation can be narrowed. Yes, thereby maintaining combustion stability.

The adjusting member has, for example, a plate shape that can move directly in the slit-shaped space of the air nozzle, and slides on the adjusting member and the guide surface of the air nozzle that guides the adjusting member. A movable taper surface is formed, and the degree of opening of the opening can be adjusted by direct movement of the adjustment member.

[0018] The tapered surface is in the direction of linear movement of the adjusting member.
The adjusting member can be formed such that the thickness of the adjusting member is changed, or the adjusting member is changed in the axial direction of the furnace.

In order to automatically maintain the air amount of the air nozzle at an appropriate value, in addition to the adjusting member, a temperature detecting means for detecting the temperature of the inner wall surface of the combustion chamber, and an air amount from the air nozzle Control means for controlling the air flow rate so that the temperature detected by the temperature detection means is equal to or lower than the dust welding temperature and the air flow rate is an appropriate air flow rate for combustion. What is necessary is just to control the opening degree of an adjustment valve and the position of an adjustment member.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to FIG.
An embodiment of the present invention will be described based on the above. In FIG. 1, the furnace main body 1 of the dust-containing exhaust gas combustion treatment apparatus is made of a heat-resistant material and forms a vertical furnace. The furnace main body 1 has a combustion chamber 2 in which an internal space burns exhaust gas, and a dust discharge port 3 for dropping and discharging burned dust at a lower end.
However, an exhaust port 4 for exhaust is provided at the upper end.

The combustion chamber 2 is an upstream primary combustion chamber 2
A is divided so that A is located at the lower part and the secondary combustion chamber 2B at the downstream side is located at the upper part. A portion forming the lower end of the secondary combustion chamber 2B and serving as a boundary with the primary combustion chamber 2A is a throttle portion 2C having an inner diameter smaller than that of the other portion.

An exhaust gas inlet 5 for supplying exhaust gas to be burned into the primary combustion chamber 2A and a pilot burner 6 are attached to a lower portion of the furnace main body 1. The exhaust gas inlet 5 is provided to be inclined downward toward the lower end of the furnace body 1. The exhaust gas inlet 5 has a partially premixed air 7.
Is supplied to the exhaust gas 8. or,
The pilot burner 6 is provided at the bottom of a concave portion 6A that is sunk below the inner wall surface of the furnace body 1, so that the flame of the pilot burner 6 is always in the concave portion 6A.

In the primary combustion chamber 2A of the furnace body 1, a primary combustion burner 9 is provided above the pilot burner 6, and a primary air nozzle 10 is provided between the primary combustion burner 9 and the pilot burner 6. Is provided. In the present embodiment, the auxiliary burner 9 is installed toward the upstream side, that is, obliquely downward in the case of the vertical furnace of FIG.

A secondary air nozzle 11 is provided at a lower end 2C of the secondary combustion chamber 2B. Further, a secondary combustion supporting nozzle 12 is provided at an upper position thereof.
In the present embodiment, the secondary combustion burner 12 is installed toward the upstream side, that is, obliquely downward, like the primary combustion auxiliary burner 9 in the present embodiment.

In this embodiment, the primary air nozzle 10
And the secondary air nozzle 11 are provided tangentially to the circumferential wall surfaces of the primary combustion chamber 2A and the secondary combustion chamber B, respectively. In the present invention, it is sufficient if at least one of the primary air nozzle 10 and the secondary air nozzle 11 has such a form. In the present embodiment, since both air nozzles 10 and 11 are formed similarly, only the primary air nozzle 10 is shown in FIG.

FIG. 2 is a cross-sectional view at the position of the primary air nozzle 10 of the apparatus shown in FIG. In the present embodiment, the primary air nozzles 10 are provided on the furnace main body 1 at two locations in the circumferential direction and at symmetrical positions with respect to the core. In the present invention,
There is no limit on the number of air nozzles.

The primary air nozzle 10 is tangential to the inner wall surface of the combustion chamber 2A at the position of the opening 21 opening to the primary combustion chamber 2A. The internal space of the primary air nozzle 10 has a slit shape having a relatively narrow width b and a large height h in the direction of the furnace axis as seen in FIG. On one side wall surface of this slit-shaped internal space, the internal space is directed toward the combustion chamber 2A and the width gradually increases.
A tapered surface 22 is formed as a guide surface that narrows the guide surface.

A plate-shaped adjusting member 23 is disposed in the slit-shaped internal space of the primary air nozzle 10. The adjusting member 23 has a plate thickness t smaller than the width b of the slit (bc) and a height dimension substantially equal to the height h of the slit. This plate-shaped adjusting member 23
One surface is formed as a tapered surface 24 that matches the tapered surface 22 at the front part (combustion chamber 2A side).

A rod 23A for moving the adjusting member 23 back and forth is connected to the rear of the adjusting member 23. The adjusting member 23 is urged by means (not shown) so that the tapered surface 24 is always in contact with the tapered surface 22 as a guide surface facing the tapered surface 24.

In such an embodiment, the exhaust gas is burned in the following manner.

First, the exhaust gas 8 containing combustible substances generated in the incinerator is introduced into the primary combustion chamber 2A from the exhaust gas inlet 5 while being mixed with the partial premixing air 7.

Since a flame is always emitted from the pilot burner 6 in the recess 6A, and the high-temperature exhaust gas is supplied near the center of the furnace, the exhaust gas is ignited and the combustion is maintained. This exhaust gas is heated by the primary combustion burner 9 and supplied from the primary air nozzle 10 to promote its combustion. Dust after combustion falls and dust outlet 3
The discharged combustion gas rises on the upward swirling flow in which the flame of the primary auxiliary burner 9 is generated, and reaches the secondary combustion chamber 2A.

In the secondary combustion chamber 2B, the combustion gas is supplied with air from the secondary air nozzle 11 at a portion 2C, and is heated by the secondary combustion burner 12 when ascending to further promote combustion.

Then, the gas after combustion is exhausted from the exhaust port 4 to the outside of the furnace for processing.

From the primary air nozzle 10 and the secondary air nozzle 11, air is supplied from the primary combustion chamber 2A and the secondary combustion chamber 2B.
When the air is blown into the throttle portion 2C, the air is directed in the tangential direction of the inner peripheral walls of the combustion chambers 2A and 2B, so that the air flows completely in contact with the inner peripheral wall and has a diameter substantially equal to the diameter of the inner peripheral wall. Is formed. Therefore, no stagnation region occurs near the opening 21 of the primary air nozzle 10 and the secondary air nozzle 11.

The air amount and the air blowing speed from the primary air nozzle 10 and the secondary air nozzle 11 are adjusted according to the combustion state. By moving the adjusting member 23 in the front-rear direction and sliding between the tapered surfaces 22 and 24 to change the width c of the opening 1, the air blowing speed is adjusted. Further, the air flow rate is adjusted by operating a flow rate adjustment valve disposed upstream of the air nozzle.

In this case, even if the adjusting member does not have a tapered surface on the plate thickness surface, it can change the dimension in the height direction.
For example, as shown in FIG.
A tapered portion 25A is formed at the bottom edge extending in the front-rear direction, and the tapered portion 2 having the same inclination is also formed on the bottom surface of the corresponding slit.
By moving the adjusting member 25 back and forth (right and left in FIG. 4), the air blowing speed can be adjusted.

The type shown in FIG. 3 has the advantage that the blast gas spreads over a wide area in the direction of the furnace axis. The type shown in FIG. 4 has a very small slit width when the required air amount is small in the type shown in FIG. When it becomes narrow and air resistance increases,
It is valid.

Further, according to the present invention, the air amount and the air blowing speed can be automatically adjusted according to the combustion state. In addition to the adjusting member and the air flow adjusting valve as described above, a temperature detecting means for detecting the temperature of the inner wall surface is provided on the inner wall surface or the like of the combustion chamber, and this is connected to the control means. The control means controls the adjustment so that the temperature detected by the temperature detection means is equal to or lower than the welding temperature of dust and the air amount is in a proper range so that combustion is performed under preferable conditions. The position of the member and the opening of the air flow control valve are controlled. By doing so, it is possible to prevent dust from adhering to the wall surface of the combustion chamber and to protect the furnace material.

[0040]

As described above, according to the present invention, since the air nozzle is provided at the tangent to the wall surface of the combustion chamber of the furnace, the swirling flow in the combustion chamber has a diameter substantially equal to the diameter of the combustion chamber. So that the air is thoroughly and homogeneously mixed throughout. Also, since the swirling flow is formed in contact with the inner wall surface,
The stagnation region is eliminated, and a local high temperature near the nozzle is avoided, and dust trouble is also reduced. As a result, the operation rate of the apparatus is improved, the burnout of the furnace is reduced, and the NOx is reduced. If the air nozzle is slit-shaped, a substantially uniform low-temperature boundary layer is formed on the wall of the combustion chamber over a wide range in the axial direction of the furnace, and dust is cooled near the inner wall, thereby avoiding dust trouble. , And re-synthesis of dioxins in dust.

Further, if the amount of air is controlled by using the control means so that the inner wall surface of the combustion chamber is maintained at a predetermined temperature, it is possible to protect the furnace material and to control the generation of NOx, CO and dioxins in the exhaust gas to reduce the amount. Pollution can be achieved. In addition, it is possible to improve the efficiency of air use, thereby conserving energy, reducing equipment costs and operating costs.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a schematic configuration of an apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of the device of FIG. 1 at a primary air nozzle position.

FIG. 3 is a sectional view taken along the line III-III in FIG. 3;

FIG. 4 is a longitudinal sectional view of a plate-shaped adjusting member and an air nozzle as another embodiment of the present invention in a plane perpendicular to the thickness direction of the adjusting member.

FIG. 5 is a sectional view of a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Furnace (furnace main body) 2 Combustion chamber 2A Primary combustion chamber 2B Secondary combustion chamber 10 Primary air nozzle 11 Secondary air nozzle 21 Opening 22 Tapered surface 23 Adjusting member 24 Tapered surface

Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) F23G 5/50 ZAB F23G 5/50 ZABH (72) Inventor Tsuyoshi Nakao 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Japan (72) Inventor Hidenobu Hiraoka 1-2-1, Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 3K061 AB01 AC19 BA05 CA01 DA18 DB16 3K062 AB01 AC19 3K065 AB01 AC19 BA05 DA01 EA16 GA03 GA08 GA12 GA14 GA22 GA23 GA34 GA53 HA03 3K078 AA05 BA03 CA02 CA12 CA18 CA24

Claims (7)

[Claims] An apparatus for introducing exhaust gas to be burned into a combustion chamber inside a cylindrical furnace body and burning the exhaust gas, wherein an air nozzle is provided in the furnace body to generate a circumferential swirling flow in the combustion chamber. The dust-containing apparatus according to claim 1, wherein the air nozzle is provided at a position and a direction in which the air nozzle blows at a position tangent to the circumferential shape of the inner wall surface at an opening position on the inner wall surface of the combustion chamber. Exhaust gas combustion treatment equipment. 2. The dust-containing exhaust gas combustion treatment device according to claim 1, wherein the air nozzle has a slit shape in which a cross section of an opening on a wall surface of the combustion chamber extends in a furnace axis direction. 3. The air nozzle according to claim 1, wherein an adjusting member for adjusting an opening degree of the opening is provided, and an adjusting valve for adjusting an air flow rate is provided upstream of the air nozzle. Item 3. A dust-containing exhaust gas combustion treatment apparatus according to Item 2. 4. The adjusting member has a plate shape which can move directly in the slit-shaped space of the air nozzle. The adjusting member and the guide surface of the air nozzle for guiding the adjusting member slide with each other during the linear movement. A possible taper surface is formed, and the degree of opening of the opening can be adjusted by direct movement of the adjusting member.
2. The dust-containing exhaust gas combustion treatment device according to item 1. 5. The exhaust gas combustion treatment apparatus according to claim 4, wherein the tapered surface is formed such that the thickness of the adjusting member changes in the direction of linear movement of the adjusting member. . 6. The dust-containing exhaust gas combustion treatment according to claim 4, wherein the tapered surface is formed such that the dimension of the adjusting member in the furnace axis direction changes in the direction of linear movement of the adjusting member. apparatus. And adjusting member 7. The method of claim 4, a temperature detecting means for detecting the temperature of the inner wall surface of the combustion chamber, and the O ₂ concentration detection means for detecting the O ₂ concentration in the exhaust gas of the furnace outlet, the air nozzles Control means for controlling the amount of air in the exhaust gas so that the temperature detected by the temperature detection means is equal to or lower than the dust welding temperature, and the O ₂ concentration in the exhaust gas is within a predetermined value range. A dust-containing exhaust gas combustion treatment apparatus that is set so as to control the adjustment member and the air amount adjustment valve so that