JPH10300006A - Inlet structure of boiler flue - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the heat resistance and an corrosion resistance of an inlet structure of a boiler flue by mounting a mouth ring comprising ceramics on the inlet side of the boiler flue on which a hot gas generated in a combustion area is introduced into the boiler flue. SOLUTION: A furnace cylinder forming a cylindrical space is provided almost at the center area of a roughly cylindrical boiler shell 31 and a heating means is disposed in the furnace cylinder on one end side of the furnace cylinder. A mouth part smoke chamber 36 is provided to let an exhaust gas flow 42 as hot gas generated by the heating means enter once thereinto. A mouth ring 1 comprising ceramics is mounted at an inlet part 38 of a boiler flue at which the exhaust gas flow 42 is introduced into the boiler flue 33. The mouth ring 1 may be so arranged that a mouth ring flange part 13 corresponding to the tip face 33B of the boiler flue 33 and a mouth ring shell part 12 corresponding to an internal wall surface of the inlet part 38 are, for example, formed and combined individually. In this invention, the mouth ring 1 is built as one continued member. The mouth ring 1 is mounted to be fitted into the inlet part 28.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a boiler smoke tube of an industrial boiler. The present invention relates to a boiler smoke tube inlet structure of a furnace tube smoke tube boiler configured to apply water to water.

[0002]

2. Description of the Related Art Conventionally, various industrial boilers have been used as equipment for centralized cooling and heating in various factories, hospitals, large buildings and apartment houses. In this industrial boiler, for example, there is a furnace tube type boiler as shown in FIG. FIG. 3 is a schematic diagram showing the main structural concept of the main body of a conventionally used flue-tube type boiler, and the respective systems of an intake system, an exhaust system, and a steam system are appropriately omitted.

[0003] The furnace tube smoke tube type boiler 30 shown in FIG. 3 is provided with a furnace tube 32 (in some cases) forming a cylindrical space in a substantially central region of a substantially cylindrical boiler body.
At one end (left side in the figure) of the furnace tube 32, a heating means such as a gas burner 40 for generating a flame 41 in the furnace tube 32 is arranged, and at the other end (right side in the diagram), a flame 41 is provided. A rear smoke chamber 36 is provided, into which the generated exhaust gas stream 42, which is a hot gas, once enters.

The rear smoke chamber 36 has a plurality of (only two are shown in FIG. 3) inlet portions 33A of boiler smoke tubes 33.
Is provided so as to penetrate a partition wall 38 separating the rear smoke chamber 36 and a storage tank for the medium water 35.

Accordingly, the high-temperature exhaust gas 42 flowing out of the furnace tube 32 into the rear smoke chamber 36 is discharged to the front smoke chamber 34 through the boiler smoke tube 33, during which the medium water 35 is heated. The exhaust gas 42 that has flowed into the front smoke chamber 34 is discharged outside the boiler barrel 31 by an exhaust system (not shown).

[0006]

In the furnace tube type boiler 30 constructed as described above, the boiler tube 33 is
In consideration of heat exchange performance, manufacturability, and the like, metal-made ones have been adopted, and in particular, rolled steel for boilers has been used.

In this type of boiler (furnace smoke tube boiler 30), an extremely high temperature exhaust gas 42 passes through the boiler smoke tube 33 at a high speed. For example, the exhaust gas 42 passing through the boiler smoke tube 33 has a flow rate of 50 m / sec. It is exposed to extremely harsh conditions of use, such as passing by a degree.

Accordingly, there is a problem that the boiler smoke tube 33 is burned even when the outside of the boiler smoke tube is cooled by the medium water 35. Further, since the exhaust gas contains water, oxygen, SO _X or NO _X , chemical damage (erosion) such as oxidative damage has been recognized.

In particular, the inlet 33A, which is the tip of the boiler smoke tube 33, has an exhaust gas flowing from the rear smoke chamber 36 to the boiler smoke tube 3.
3, the exhaust gas flow 42 is relatively disturbed, and the fluid resistance increases. Furthermore, this entrance portion 33A
Cannot be in direct contact with the medium water 35, so that the cooling effect of the medium water 35 cannot be expected as much as other parts. Therefore, the damage to the inlet portion 33A progresses rapidly, and the life of the boiler smoke tube 33 has been extremely shortened at present.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has an inlet structure for a boiler smoke tube having excellent heat resistance and corrosion resistance in a boiler having a structure for introducing a hot gas into a boiler smoke tube from a predetermined smoke chamber. The purpose is to provide.

[0011]

SUMMARY OF THE INVENTION A boiler flue tube inlet structure according to the present invention is configured to introduce a hot gas generated in a combustion area and apply heat of the hot gas to water. In the inlet structure of (1), an annular ring made of ceramics is attached to an inlet side of the boiler smoke tube through which the hot gas is introduced into the boiler smoke tube (claim 1), thereby achieving the above object. can do.

In the inlet structure for a boiler smoke tube according to the present invention, it is preferable that: the mouth ring is continuous with a mouth ring flange portion covering a tip end surface of the boiler smoke tube and a mouth ring body portion covering an inner peripheral surface of the inlet portion. The inner surface of the ring flange of the ring is formed with a curve whose diameter gradually decreases toward the inside of the boiler smoke tube (claim 2); Item 3) ・ The rear end inner peripheral surface of the mouth ring body is formed as an inclined surface whose inner diameter gradually increases toward the downstream side of the flow of the hot gas (Claim 4). -The ring is made of at least one material selected from alumina, mullite, zirconia, sialon, silicon nitride, and silicon carbide (claim 5).

(Operation) As described above, according to the boiler smoke tube inlet structure of the present invention, a ceramic ring is provided at the inlet of the boiler smoke tube through which a high-temperature gas (exhaust gas) is introduced into the boiler smoke tube. Due to the mounted structure, this inlet portion is covered with ceramics, and does not come into direct contact with the hot gas, so that heat resistance and corrosion resistance are improved.

Still further, in the above-mentioned boiler smoke tube inlet structure according to the present invention, the mouth ring is formed by connecting a mouth ring flange portion corresponding to a tip end surface of the boiler smoke tube and a mouth ring body portion corresponding to the inlet portion. By constituting as one member, contact with the hot gas can be reliably avoided.

Further, in the boiler smoke tube inlet structure according to the present invention, the ring has a gradually decreasing diameter from the tip end side of the boiler smoke tube to the inner peripheral surface of the ring body corresponding to the inlet. With this configuration, the turbulence of the air flow when the high-temperature gas is introduced into the boiler flue can be suppressed, so that the high-temperature gas can flow into the boiler flue more smoothly.

In the inlet structure for a boiler smoke tube according to the present invention, the collar body has a rear end inner peripheral surface having an inner diameter gradually increasing toward a downstream side in a flow direction of the hot gas. With such a configuration, it is possible to eliminate a sudden step between the inner wall of the boiler smoke tube and the inner wall of the collar. As a result, it is possible to avoid the adverse effect (increase in fluid resistance) on the flow of the hot gas due to the step on the inner wall of the boiler smoke tube due to the provision of the ring.

Further, in the inlet structure of the boiler smoke tube according to the present invention, the ceramics used for the ring may include:
By using at least one selected from alumina, mullite, zirconia, sialon, silicon nitride, and silicon carbide, heat resistance and corrosion resistance can be fully exhibited.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of a boiler smoke tube inlet structure according to the present invention will be described in detail with reference to the accompanying drawings.

(First Embodiment) The first embodiment shown in FIG. 1 is an enlarged partial cross-sectional view near the entrance 33A of a boiler smoke tube 33. Therefore, in this embodiment, the entire structure of the furnace tube boiler is not shown, but the boiler to which the structure shown in FIG. 1 is applied as shown in FIG.
For example, a furnace tube 32 that forms a cylindrical space is provided in a substantially central region of a substantially cylindrical boiler body 31.
A heating means is disposed in the furnace tube 32 at one end side of the furnace 2 and a rear smoke chamber 36 into which an exhaust gas flow 42 which is a hot gas generated by the heating means once enters is provided.

As shown in FIG. 1, the rear smoke chamber 36 is provided with a partition wall 38 for separating the rear smoke chamber 36 and the storage tank for the medium water 35. A boiler smoke tube 33 (one shown) penetrates. In the boiler smoke tube 33, an inlet portion 33A through which an exhaust gas flow (high-temperature gas) 42 enters the smoke tube (in the present specification, the inlet portion is a portion of the boiler smoke tube held by the partition wall 38 and its vicinity). ) Is provided so that the tip portion is slightly exposed from the partition wall 38.

In the present embodiment, an annular ring 1 made of ceramics is attached to an inlet 38 of the boiler smoke tube through which the exhaust gas flow 2 is introduced into the boiler smoke tube 33.

The mouth ring 1 is provided at the tip end surface 33B of the boiler smoke tube 33.
The ring flange 13 and the ring body 12 corresponding to the inner wall surface of the inlet 38 may be formed separately and combined, for example, but in the present embodiment, one continuous member ( (A member having a shape also referred to as a flanged cylindrical tube). The ferrule 1 is mounted so as to fit into the inlet part 38.

Therefore, the end surface 33 of the boiler smoke tube 33
B and the inner wall surface of the inlet portion 38 are exhaust gas flow 2 which is a hot gas.
No direct contact with The boiler smoke tube 33
Is for heating the water medium 35 by passing the exhaust gas flow 42 through the boiler smoke tube 33.
In most cases, the heat transfer function to the medium water 35 is relatively low, and the heat transfer efficiency of the boiler smoke tube is hardly reduced.

Examples of the material for the ring 1 include alumina, mullite, zirconia, sialon, silicon nitride, and the like.
And at least one material selected from silicon and silicon carbide.

(Second Embodiment) FIG. 2 shows a second embodiment of the boiler smoke tube entrance structure according to the present invention. In FIG. 2, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

In the present embodiment, the ring 2 is an inner surface of the ring flange 23 (the surface on the side where the exhaust gas flow 42 flows in).
However, the diameter is gradually reduced toward the inside of the boiler smoke tube 33. The collar ring portion 23 can be appropriately formed into an R-shaped curve, or can be formed from a streamline curve as appropriate. With such a curved surface configuration of the flange portion 23, it is possible to suppress disturbance of the flow when the exhaust gas flow 42 is introduced into the boiler smoke tube 33, and to make the flow into the boiler smoke tube 33 smoother.

Further, as shown in FIG.
The rear end inner peripheral surface 22 </ b> B is formed as an inclined surface whose inner diameter gradually increases toward the downstream side in the flow direction of the exhaust gas flow 42. With the inclined surface structure of the rear end inner peripheral surface 22 </ b> B, the boiler smoke pipe 33 and the exhaust gas flow 42 suppress the disturbance of the flow when being introduced into the boiler smoke pipe 33,
The flow of the hot gas into the boiler smoke tube can be made smoother.

[0028]

【Example】

(Embodiment 1) As Embodiment 1 of the inlet structure of a boiler smoke tube according to the present invention, a ferrule having a shape shown in FIG. 1 was applied to a furnace tube smoke tube boiler (see FIG. 3) under the following conditions.

Ring Dimension Ring Ring Flange Dimension (D2) ... 60mm Inner Dimension of Boiler Smoke Tube (D1) ... 35mm Ring Ring Thickness (t) ... 2mm

Exhaust gas flow velocity (v): about 50 m / s Exhaust gas temperature: about 1200 ° C. Exhaust gas component CO ₂ ... 10 to 11 _{% H 2 O ···· 10~15% N} 2 ····· 77% or more _{O 2 ····· 3~5% SO x ····} 200ppm NO x ···· 100ppm duct ..・ ・ 0.1g / Nm ³・ Judgment method ・ ・ ・ ・ ・ Visual observation of boiler smoke tube inlet

(Comparative Example 1) In Comparative Example 1, the same conditions as in Example 1 were used except that the structure was not provided with a ring.

As a result, in the boiler using the ring of the present embodiment, the boiler could be used for 20,000 hours. On the other hand, in the boiler of Comparative Example 1 which does not use the ferrule, the usable time of the boiler smoke tube is 5,000 hours. The life of the fire tube was quadrupled.

[0033]

As described above, according to the boiler smoke tube inlet structure of the present invention, a ceramic ring is mounted at the inlet of the boiler smoke tube through which the hot gas is introduced into the boiler smoke tube. With this configuration, the inlet of the boiler smoke tube, which is most easily damaged, is covered with ceramics, so that heat resistance and corrosion resistance can be improved, and the life of the boiler smoke tube can be significantly extended.

Further, in the inlet structure of the boiler stack according to the present invention, the ring has a curved line whose diameter gradually decreases from the tip end side of the boiler stack to the inner peripheral surface of the ring body corresponding to the inlet. In the case of the under-structure, since the turbulence of the air flow when the high-heat gas is introduced into the boiler smoke tube can be suppressed, the flow of the high-heat gas into the boiler smoke tube can be made smoother.

In the inlet structure of the boiler smoke tube according to the present invention, the inner peripheral surface of the rear end of the ring body is formed as an inclined surface whose inner diameter gradually increases toward the downstream side in the flow direction of the hot gas. In this case, the steep step between the inner wall of the boiler stack and the inner wall of the ring can be eliminated, so that the step of the inner wall of the boiler pipe due to the ring has an adverse effect on the flow of hot gas. And a good flow of hot gas can be maintained.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part of a first embodiment of a boiler smoke tube entrance structure according to the present invention.

FIG. 2 is an enlarged sectional view of a main part of a second embodiment in an inlet structure of a boiler smoke tube according to the present invention.

FIG. 3 is a schematic view showing an example of a conventional boiler having a boiler smoke tube entrance structure.

[Explanation of symbols]

 1, 2 Ring 12, 22 Ring body 13, 23 Ring flange 22 B Inner surface of rear end 31 Boiler barrel 33 Boiler smoke pipe 33 A Inlet 33 B Smoke pipe end face 35 Medium water 36 Rear smoke chamber 38 Partition wall 42 Exhaust gas flow ( (Hot gas)

Claims (5)

[Claims] 1. An inlet structure for a boiler smoke tube configured to introduce a hot gas generated in a combustion region and to apply heat of the hot gas to water, wherein the hot gas is introduced into the boiler smoke tube. An inlet structure for a boiler smoke tube, wherein an inlet ring made of ceramics is attached to an inlet portion of the boiler smoke tube. 2. The ring assembly according to claim 1, wherein the ring flange has a continuous structure with a ring flange covering a tip end face of the boiler smoke tube and a ring collar body covering an inner peripheral surface of the inlet. The inlet structure of the boiler smoke tube according to claim 1. 3. The boiler according to claim 2, wherein the inner surface of the ring flange of the ring is formed with a curve whose diameter gradually decreases toward the inside of the boiler smoke tube. Fire tube entrance structure. 4. The collar body has a rear end inner peripheral surface,
3. An inclined surface whose inner diameter gradually increases toward the downstream side of the flow of the hot gas.
Or the inlet structure of the boiler smoke pipe of 3. 5. The method according to claim 1, wherein the ring is made of at least one material selected from the group consisting of alumina, mullite, zirconia, sialon, silicon nitride, and silicon carbide. The inlet structure of the boiler smoke tube described.