JP2001241628A - Secondary combustion chamber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion chamber for preventing sulfuric acid corrosion (low-temperature corrosion) due to acid dew formation and at the same time preventing oxidation corrosion (high-temperature oxidation) due to high- temperature oxidation and the thermal damage of a refractory. SOLUTION: In a combustion chamber (10) having a body (14) comprising a cylindrical skin steel plate (11), and a fireproof brick (12) and a heat-insulating brick (13) that are subjected to inner lining to the inner surface of the skin steel plate (11), a porous plate (15) for thermal insulation is provided at the outer periphery of the skin steel plate (11), and a space (16) is included between the skin steel plate (11) and the porous plate (15).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary combustion chamber, for example, a secondary combustion chamber provided after a high-temperature melting rotary kiln for drying, incinerating and melting industrial waste, for secondary combustion of generated combustion gas. About.

[0002]

2. Description of the Related Art General waste, industrial waste, metal-containing waste, and the like are treated by drying, incineration, and melting treatment in a high-temperature melting rotary kiln, and then using combustion gas generated in the rotary kiln in a downstream stage of the rotary kiln. Combustion treatment is performed in the next combustion chamber.

[0003] The secondary combustion chamber used for this combustion treatment is:
As shown in FIG. 2, a cylindrical outer steel plate 21
Refractories (firebrick 22 and insulating brick 2) lined on the inner surface
3) In the furnace having the body 24 composed of the above, the combustion gas generated by the rotary kiln is led into the body 24 at about 1050 ° C. to perform the combustion treatment.

However, in the case of such a secondary combustion chamber 20 in which the outer steel plate 21 is exposed, heat is largely dissipated by being exposed to the wind and rain, and the outer surface of the body 24 is cooled, and sulfuric acid corrosion (low-temperature corrosion) due to acid condensation is caused. ) Is likely to occur. Further, the coating is easily damaged by the temperature fluctuation of the outer steel plate 21.

In order to prevent the sulfuric acid corrosion (low temperature corrosion) and the damage of the coating, a secondary combustion chamber shown in FIG. 3 has been conventionally used. The secondary combustion chamber 30 has a body 34 formed of a tubular outer steel plate 31 and a refractory (a refractory brick 32 and a heat-insulating brick 33) lined on the inner surface of the outer steel plate 31. Protective coating 3 via layer 36
5 furnace.

In FIGS. 2 and 3, a line D indicates the temperature distribution in the secondary combustion chambers 20 and 30. Secondary combustion chamber 2 in FIG.
In the case of 0, the temperature in the combustion chamber is 1050 ° C., and the temperature of the refractory brick 22 decreases gradually and linearly.
In the case of the outer steel plate 21, 174 drops sharply and linearly.
° C, and reaches room temperature outside the outer steel plate 21. In the case of the secondary combustion chamber 30 in FIG. 3, the temperature in the combustion chamber is 1050 ° C., the temperature gradually decreases linearly in the refractory brick 32, and sharply decreases linearly in the heat insulating brick 33. At 31, the temperature is 380 ° C., the temperature gradually decreases linearly in the heat insulation layer 36, and reaches room temperature outside the heat insulation layer 36.

[0007]

However, in such a secondary combustion chamber 30, the heat retention becomes too high, so that the temperature of the body 34 becomes higher than necessary (380 ° C.). Oxidation corrosion by high temperature oxidation (high temperature oxidation)
Easy to do. In addition, refractories (firebrick 32 and insulation brick 33)
Becomes hot and wears out, easily causing thermal damage (deterioration), etc.
Therefore, it is necessary to make the thickness of the insulating bricks 33 and the like about twice as large as that of the general secondary combustion chamber 20, which is disadvantageous in cost.

The present invention has been made intense research and development in view of the above problems, and has as its object to prevent sulfuric acid corrosion (low temperature corrosion) due to acid dew condensation, as well as oxidative corrosion (high temperature oxidation) by high temperature oxidation. An object of the present invention is to provide a combustion chamber that prevents thermal damage to refractories.

[0009]

According to a first aspect of the present invention, there is provided a secondary combustion chamber comprising: a cylindrical outer steel plate; and a refractory lined on an inner surface of the outer steel plate. In the secondary combustion chamber having the body, a perforated plate for keeping heat is provided on the outer periphery of the outer steel plate, and a space is interposed between the outer steel plate and the perforated plate.

In this secondary combustion chamber, heat dissipation from the outer steel plate is blocked by the space and the perforated plate. The space interposed between the outer steel plate and the perforated plate is used to adjust the amount of heat radiation by convection (circulating ventilation) of air through the opening of the perforated plate, and the radiant heat dissipated from the outer steel plate is reduced by the perforated plate. The outer steel plate is maintained at an appropriate temperature by being partially reflected. Therefore, the body is prevented from being cooled or heated more than necessary, thereby preventing sulfuric acid corrosion due to acid condensation (low temperature corrosion), oxidative corrosion due to high temperature oxidation (high temperature oxidation), and thermal damage to refractories. .

[0011] The secondary combustion chamber according to claim 2 of the present invention is characterized in that the perforated plate is arranged close to the protective coating side.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view showing the configuration of an embodiment of a combustion chamber according to the present invention.

The secondary combustion chamber 10 of the present embodiment has a body 14 composed of a cylindrical outer steel plate 11 and a refractory (a refractory brick 12 and a heat insulating brick 13) lined on the inner surface of the outer steel plate 11, The outer periphery of the body 14 is provided with a coating of a perforated plate 17. A hollow space 16 is provided between the outer steel plate 11 and the perforated plate 17.

The inner diameter of the outer steel plate 11 of the body 14 is, for example, about 4.5 mφ, and the thickness of the outer steel plate 11 is about 11 m.
mm. The thickness of the refractory brick is about 0.3m,
The thickness of the insulating brick is about 0.1 m. The width of the space 16 between the outer steel plate 11 and the perforated plate 17 is 50 to 100.
mm.

[0015] In the rotary kiln, the combustion gas generated when processing waste such as general waste, industrial waste, and metal-containing waste is heated to about 1050 ° C in the secondary combustion chamber 10 of the present embodiment. The body 14 is guided into the body 14 and burned.

According to the secondary combustion chamber 10 of the present embodiment, since the perforated plate 17 is provided on the outer periphery of the outer steel plate 11,
The perforated plate 17 and the space 16 block heat dissipation from the outer steel plate 11. Also, provided in the heat insulating layer 15,
That is, the air in the space 16 is convected (circulated) through the opening of the perforated plate 17 provided outside the outer steel plate 11 to adjust the amount of heat radiation, and the radiant heat dissipated from the outer steel plate 11 is reduced by the perforated plate 17. Partially reflected, the outer steel plate 11 is maintained at an appropriate temperature. The amount of heat radiation from the outer steel plate 11 can be arbitrarily adjusted by changing the aperture ratio of the perforated plate 17.

Thus, the body 14 is prevented from being cooled or heated more than necessary. Therefore, sulfuric acid corrosion due to acid condensation (low temperature corrosion), oxidation corrosion due to high temperature oxidation (high temperature oxidation) and refractory (fire brick) 12 and insulation brick 1
3) Thermal damage is prevented.

[0018]

The following Table 1 shows that the perforated plate of the embodiment of the present invention is provided when a general outer steel plate is exposed (case A), when a conventional outer steel plate is covered with a heat insulating layer (case B). FIG. 7 shows a comparison between the case of covering with a heat insulating layer (case C).

[0019]

[Table 1]

In the examples, the outer steel plate is exposed (case A), the outer steel plate is covered with a heat insulating layer (case B), and the outer steel plate is covered with a heat insulating layer provided with the perforated plate of the present invention (case C). In each case, the inner diameter of the body is set to 4.5 mφ, an outer steel plate, a refractory brick having a thermal conductivity of 6.3 Kj / m / h / ° C., and an insulating brick having a thermal conductivity of 0.84 Kj / m / h / ° C. , The thickness of the refractory brick is approximately equal to 0.23 m
3m, 0.3m and the thickness of the insulating brick are 0.1m, 0.2m
m and 0.1 m. The width of the heat insulating layer 36 of the case B (FIG. 3) is set to 15 mm, and the width of the heat insulating layer 16 of the case C (FIG. 1) of the present invention is set to the same 15 mm. Perforated plate 17
And a combustion treatment was performed.

As a result of the implementation, when the conventional outer skin steel sheet is exposed (case A), when the outer skin steel sheet is covered with the heat insulating layer (case B), when the conventional outer steel sheet is covered with the heat insulating layer provided with the perforated plate of the embodiment of the present invention. In (Case C), the temperature of the outer steel plate was 17
4 ° C, 380 ° C, 230 ° C, heat dissipation 4.3, 1.6,
3.7 Mj / h / m ² . When the temperature of the protective coating is the case where the outer steel plate 31 is covered with the heat insulating layer 36 (case B), the temperature is 100 ° C., and when the temperature is 100 ° C. when the outer steel plate 31 is covered with the heat insulating layer 16 provided with the perforated plate 17 of the present invention (case C). , About 130 ° C-17
The temperature reached 0 ° C. Table 2 shows the results of the cases A, B, and C.

In FIG. 1, line D indicates the temperature distribution in the secondary combustion chamber 10 of the present invention. Secondary combustion chamber 1 of the present invention
In the case of 0, the temperature in the combustion chamber is 1050 ° C., the temperature gradually decreases linearly in the refractory brick 12, decreases sharply linearly in the heat insulating brick 13, and reaches 230 ° C. in the outer steel plate 11. 16, the temperature gradually decreases linearly, and reaches about 130 ° C. to 170 ° C. in the protective coating 15.
Reach room temperature outside.

[0023]

[Table 2]

Assuming that the amount of heat dissipated in a case where a general outer steel plate is exposed (case A) is 100%, case B
Is 37%, and Case C of the present invention is 87%. The case A and the case C have little heat damage to the outer steel plate, but the case B tends to cause the heat damage due to brick wear. This is because the temperature of the body 24 becomes higher than necessary.

In inspecting the inside of the fuselage for damage, the cases A and C are visible, but in the case B, damage to the brick is hard to be found. This is because there are a fireproof brick 32 and a heat insulation brick 33, particularly a thick heat insulation brick 33 which is not visible between the outer steel plate 31 and the fire brick 32.
This is because the degree of the damage of No. 3 is difficult to understand.

Regarding the prevention of burns, in case A, the skin steel plate 21 is exposed and a relatively high temperature (17
4 ° C.), which is insufficient, but case B
In the case C, since the protective coatings 35 and 15 are provided on the outer periphery of the outer steel plates 31 and 11 via the heat insulating layers 36 and 16, the temperature is relatively low (100 ° C. to 170 ° C. or less), and is substantially It is enough.

In case A, the skin steel plate 21 is exposed to the wind and rain, which is likely to cause low-temperature corrosion of the skin steel plate due to the external environment. It is unlikely to occur because it is not directly exposed to the elements. The damage of the coating applied to the outer surface of the steel sheet is easily caused by the temperature fluctuation of the outer steel sheet 21 in case A, but is provided outside the outer steel sheets 31 and 11 in case B and case C. Protective coating 3
It is unlikely to occur due to small temperature fluctuations of 5 and 15.
In the case C of the present invention, if stainless steel that does not easily corrode the protective coating is used, repainting becomes unnecessary.

Regarding the construction cost, the case A is the cheapest, because it has a simple structure in which the shell steel plate 21 is exposed, but the case B is a refractory (fire brick). 22 and the insulating bricks 23), especially the insulating bricks 23, are thick and disadvantageous. In the case C of the present invention, the structure is slightly complicated by providing the perforated plate 17 and the like, but the thickness of the refractory (the refractory brick 12 and the insulating brick 13) is the same as that of the case A. , Will be relatively cheap.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example,
In the example, the perforated plate was provided at a position closer to the protective coating side between the outer steel plate and the protective coating, but was closer to the approximate center or the outer steel plate side between the outer steel plate and the protective coating as necessary. It may be provided at a position. In addition, although the present invention is applied to a secondary combustion chamber of a high-temperature melting type rotary kiln, it can be used in various combustion chambers for burning general waste, industrial waste, metal-containing waste or other waste.

[0030]

As described above in detail, according to the present invention, heat dissipation from the outer steel plate is blocked by the heat insulating layer, the perforated plate and the protective coating provided on the outer periphery of the outer steel plate. That is, the air in the heat insulating layer convects through the perforated plate through the opening hole of the perforated plate provided in the heat insulating layer, and circulating ventilation is performed.

The temperature of the outer steel plate is appropriately maintained due to the fact that the radiant heat dissipated from the outer steel plate is partially reflected by the perforated plate. Therefore, the body is prevented from being cooled or heated more than necessary, and sulfuric acid corrosion (low temperature corrosion) due to acid condensation, oxidative corrosion (high temperature oxidation) due to high temperature oxidation, and thermal damage to refractories are prevented.

Further, according to the present invention, since the perforated plate is arranged close to the protective coating side, the influence from the outside of the protective coating can be more blocked. Therefore, the influence of cooling or the like from the outside of the protective coating is reduced, and the body is appropriately kept warm to avoid low-temperature corrosion, high-temperature oxidation, and thermal damage to refractories.

[Brief description of the drawings]

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

FIG. 2 is a configuration sectional view of a general secondary combustion chamber.

FIG. 3 is a configuration sectional view of a conventional secondary combustion chamber.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Outer steel plate 12 Refractory brick 13 Insulating brick 14 Body 15 Protective covering 16 Space 17 Perforated plate

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) F27D 1/00 F27D 1/00 A 17/00 104 17/00 104A F term (reference) 3K065 AA07 AB03 FA12 FB02 3K078 BA05 CA02 4K051 BA02 BB02 4K056 AA14 AA19 BB01 DB03 4K061 AA08 BA12 CA17

Claims (1)

[Claims] In a secondary combustion chamber having a body made of a cylindrical outer steel plate and a refractory lined on the inner surface of the outer steel plate, a perforated plate for keeping heat on the outer periphery of the outer steel plate is provided. A secondary combustion chamber, wherein a space is interposed between the plate and the plate.