JP2000146105A - Circulation fluidized bed combustion furnace and method of preventing wear of evaporation tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the depth of wear of evaporation tubes near the top surface of a lower refractory material in a circulation fluidized bed combustion furnace provided with the lower refractory material at a lower part of a wall surface thereof, on which a plurality of evaporation tubes are arranged. SOLUTION: A plurality of evaporation tubes 2 are arranged on the wall surface of this circulation fluidized bed boiler, and a lower refractory material is provided at a lower part of the wall surface. A nozzle 11 for blowing a gas toward the inside of a furnace is arranged between the adjacent generating tubes 2 above a stage 3' at the top surface part of the lower refractory material. Particles are concentrated on the evaporation tubes near the stage 3' by varying the accumulation height of the particles of fluidizing material by removing the particles accumulated on the stage 3' by a gas blown from the nozzle 11, thereby preventing a reduction in the thickness of the generating tubes 2 at specified points.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circulating fluidized bed combustion furnace, and more particularly to a circulating fluidized bed combustion furnace in which a plurality of evaporating tubes are arranged on a wall surface and a lower refractory material is provided at a lower portion of the wall surface. The present invention relates to a circulating fluidized bed combustion furnace capable of reducing the wear depth of an evaporator tube near the upper surface of a lower refractory material.

[0002]

2. Description of the Related Art FIG. 6 shows a structural example of a conventional circulating fluidized bed combustion furnace, for example, a circulating fluidized bed boiler in which a plurality of evaporating tubes 2 are arranged on a wall surface and a lower refractory material 3 is provided below the wall surface. It is shown in FIG. 6 and 7, reference numeral 1 denotes a circulating fluidized bed boiler main body, 4 denotes a fluidizing nozzle at the bottom, and 5 denotes a wind box. As shown in FIG. 7 on an enlarged scale, a stage 3 ′ is formed on the upper surface of the lower refractory material 3.

[0003] In the conventional circulating fluidized-bed boiler configured as described above, the fluidized material forms a fluidized bed in the furnace by the air blown into the furnace from the wind box 5 through the fluidizing nozzle 4. The behavior of the fluidized material in the circulating fluidized-bed boiler is such that many particles 6 ′ rise in the central part of the furnace, while particles 6 descending along the wall surface near the wall surface where the evaporating tube 2 is arranged are almost all. is there. Particles 6 descending along the evaporating pipe 2 near the wall surface accumulate on the stage 3 ′ on the upper surface of the lower refractory material 3 to form an inclined surface 9 based on the angle of repose θ ° as shown in FIG. . The angle of repose θ is constant as long as the particle size of the fluid, the operating conditions, and the like do not change.

Accordingly, as shown in FIG. 7 (B), after the particles are deposited on the stage 3 ', the evaporation tube 2
The particles 6 descending only to a portion 8 where the inclined surface 9 of the deposited particles intersects the antinode of the evaporating tube 2. In this case, the wall thickness was reduced, and the evaporating pipe 2 had to be repaired frequently.

Therefore, the angle of repose θ of the particles is
With the above inclination, the accumulation of fluid material particles is eliminated,
Since particles descending at the boundary between the inclined surface of the stage 3 ′ and the evaporating tube 2 are concentrated, the progress of the abrasion of the evaporating tube 2 at that portion cannot be stopped.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a circulating fluidized bed combustion furnace in which a plurality of evaporating tubes are disposed on a wall surface and a lower refractory material is provided at a lower portion of the wall surface, in the vicinity of the upper surface of the lower refractory material. It is an object of the present invention to provide a circulating fluidized bed combustion furnace capable of reducing the wear depth of the evaporator tube in the above-mentioned method, and an effective method for preventing abrasion of the evaporator tube using the same.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a circulating fluidized bed combustion furnace in which a plurality of evaporating tubes are arranged on a wall surface and a lower refractory material is provided at a lower portion of the wall surface. There is provided a circulating fluidized bed combustion furnace provided with a nozzle for blowing gas toward the inside of the furnace, above the upper surface of the lower refractory material and between the adjacent evaporating tubes.

According to the circulating fluidized bed combustion furnace of the present invention, particles deposited on the upper surface of the lower refractory material are blown out by blowing gas into the furnace from a nozzle disposed between adjacent evaporation tubes. Can be removed.

Accordingly, the height of the particles deposited on the upper surface of the lower refractory material is changed, and the particles concentrate on the evaporator tube at the intersection of the inclined surfaces of the deposited particles as in the prior art, so that the evaporator tube has A situation where the part is worn away is avoided.

In the circulating fluidized bed combustion furnace according to the present invention,
By arranging the gas to be blown out from the nozzle at regular intervals, it is possible to mechanically easily change the slope of the accumulation of particles on the upper surface of the lower refractory material.
Alternatively, by adopting a configuration in which the gas is blown out with a change in the flow rate from the nozzle, the inclined surface of the particles deposited on the upper surface of the lower refractory material can be changed as described above.

In order to solve the above-mentioned problem in a circulating fluidized bed combustion furnace in which a plurality of evaporating pipes are arranged on a wall surface and a lower refractory material is provided at a lower portion of the wall surface, the present invention provides Provided is a circulating fluidized bed combustion furnace provided with a plurality of shelves installed at a plurality of shelves having a surface inclined toward the inside of the furnace and deflecting the flow of the fluid material falling along the wall surface into the inside of the furnace.

According to this circulating fluidized bed combustion furnace, the particles falling along the wall surface are deflected into the furnace by the shelf, so that the amount of particles falling on the upper surface of the lower refractory provided at the lower portion of the wall surface is reduced. Thus, the amount of particles that act intensively on the evaporator tube near the lower refractory material is reduced, and the abrasion of the evaporator tube by particles can be reduced.

Further, in the circulating fluidized bed combustion furnace provided with the shelves as described above, the shelves are provided with a projecting portion projecting into the gap between the adjacent evaporating pipes, and the flow of the fluid material falling through the gap is determined by the furnace. When configured to deflect inward, particles descending the gap formed between the evaporator tubes on the back side of the shelf are received by the overhang and guided to the upper surface of the shelf, and are received by the shelf as described above. Deflected into the furnace with the particles.

Thus, the particles falling along the gap between the wall surface and the evaporating pipe are deflected into the furnace and further reduce the amount of particles falling on the upper surface of the lower refractory, thereby evaporating near the lower refractory. The amount of particles acting on the tube is significantly reduced, and wear on the evaporator tube can be reduced.

In the case where the overhanging portion is provided, the overhanging portion is provided on a plurality of shelves, and the overhanging length of the overhanging portion is gradually increased from the upper stage to the lower stage. If the flow of the flow material falling through the gap is gradually deflected into the furnace, the particles falling down the gap between the evaporator tubes will be gradually received by the overhangs with different lengths, It is preferable that the amount of particles acting on the evaporating tube is dispersed even in the gap between the evaporating tubes in the portion where the is provided, so that the action of the particles on the evaporating tube can be concentrated and a specific portion can be prevented from abrading.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to FIGS.
This will be specifically described based on the embodiment shown in FIG. In the following embodiments, the same components as those of the conventional apparatus shown in FIGS. 6 and 7 are denoted by the same reference numerals for simplification of description.

(First Embodiment) First, a first embodiment shown in FIGS. 1 to 3 will be described. 1 to 3 show FIGS.
It is a figure which shows an example at the time of applying this invention to a circulating fluidized-bed boiler similarly to FIG. 1 to 3, 1
Reference numeral 1 denotes a nozzle, which is disposed between the adjacent evaporating tubes 2 and above the stage 3 'of the lower refractory material 3 with its tip facing the inside of the furnace. Each nozzle 11 is connected to an air pipe 12,
The air pipe 12 is provided with a valve 10.

Although one nozzle 11 is arranged between the evaporation tubes 2 in the drawing, a plurality of nozzles may be arranged. Other configurations are the same as those of the conventional circulating fluidized-bed boiler described above with reference to FIGS.

Since the nozzle 11 is arranged in the circulating fluidized bed boiler shown in FIGS. 1 to 3 as described above, the air is blown out from the nozzle 11 so as to be placed on the stage 3 'of the lower refractory material 3. Particles to be deposited are periodically broken, the point where the inclined surface of the deposited particles contacts the evaporating pipe 2 is changed over time, and the parts where the abrasion occurs in the evaporating pipe 2 are dispersed without specifying, thereby extending the life of the evaporating pipe 2. Can be longer.

FIG. 3 shows this state. The particles of the flowing material descending along the wall surface on which the evaporating pipe 2 is disposed are placed on the stage 3 'of the lower refractory material 3 as shown in FIG. are formed in a triangular shape of θ to form an inclined surface 9 based on the angle of repose θ. In such a state, by opening the valve 10 of the air pipe 12 and blowing out high-pressure air from the nozzle 11, the deposited particles on the stage 3 'are collapsed as shown in FIGS. After that, the flowing material gradually accumulates again due to the falling particles, and returns to the state shown in FIG.

Therefore, the sliding surface of the deposited particles goes up and down as shown by the arrow in FIG. 3C. By grasping this cycle, high-speed air is blown out from the nozzle 11 at time intervals corresponding to the period, so that the flow material is removed. The slope 7 is constantly changed,
The position of the inclined surface 7 where the particles act on the evaporating tube 2 can be constantly changed.

In the above description, the method of periodically blowing air from the nozzle 11 to break up the deposited particles has been described. However, the blowing of air from the nozzle 11 is performed continuously, and the flow rate of the injected air changes. The inclined surface 7 of the deposited particles may be constantly changed in such a manner as to attach. Also,
It goes without saying that the desired control may be performed in accordance with the state of accumulation of particles on the stage 3 'by combining the periodic start and stop of the air blowing and the change in the flow rate of the blowing air.

(Second Embodiment) Next, a second embodiment shown in FIGS. 4 and 5 will be described. 4 and 5, reference numeral 13 denotes an inclined shelf which is inclined toward the inside of the furnace. The inclined shelf 13 extends along the evaporating pipe 2 forming the wall surface of the furnace as shown in FIG. Stage 3 'above
It is arranged to cover.

The inclined shelves 13 are arranged in multiple stages with an interval in the vertical direction, and are supported on the evaporating pipe 2 by being mounted on or fixed to the inclined shelf support fittings 14. 1
Reference numeral 6 denotes a gap plate connecting between the evaporation tubes 2.

The inclined shelf 13 is an L-shaped bar having a triangular cross section made of a material having excellent wear resistance at high temperatures such as austenitic stainless steel and ceramics. A gap is formed between the surface of the inclined shelf 13 and the gap plate 16, and the projecting portion 13 ′ is provided on the back surface of the inclined shelf 13 in order to guide the flowing material particles falling through the gap to the inside of the furnace through the inclined shelf 13. Is provided, so that the descending flow of the flowing material particles descending in the gap between the back surface of the inclined shelf 13 and the gap plate 16 is scraped into the inside of the furnace.

The length of the overhang portion 13 'is different depending on the upper and lower inclined shelves 13, and the longer the lower portion is, the longer the overhang length is. Reference numeral 15 denotes a gap between the overhang 13 'and the evaporating tube 2. Other configurations of the circulating fluidized bed boiler shown in FIGS.
The fluidizing nozzle 4 and the wind box 5 are substantially the same as those of the first embodiment shown in FIGS.

In the circulating fluidized-bed boiler of FIGS. 4 and 5 configured as described above, the fluid material 6 that descends along the evaporating pipe 2 on the wall without the inclined shelf 13 has been described in the first embodiment. Thus, it is deposited on the stage 3 ′ of the lower refractory material 3,
When sliding down the inclined surface, the wall thickness of the evaporation pipe 2 is reduced.

Therefore, in the second embodiment, an inclined shelf 13 having an inclined surface for receiving the particles 6 of the flowing material descending along the wall surface is provided at each corner of the circulating fluidized bed boiler having a particularly large wall thickness reduction. Thus, the falling direction of the particles is changed to the inside of the furnace, and the amount of the particles of the fluidized material deposited on the stage 3 'is reduced, thereby reducing the wall thickness of the evaporating tube 2.

The inclined shelf 13 installed over a plurality of stages
Since the length of the protruding portion 13 ′ that protrudes into the gap between the evaporating tubes 2 from the upper stage to the lower stage is increased,
The fluid material 6 descending through the gap between the evaporating tubes 2 is gradually scraped into the furnace.

If there is no change in the overhang length of the overhang portion 13 'in the plurality of inclined shelves 13, all the fluidized material 6 descending between the evaporating tubes 2 is scraped into the furnace by the one inclined shelf. In this way, when the evaporating tube 2 is received by the fluidized material on the stage 3 ', the same effect of concentrated particles
It will be received at the inclined shelf of the step, and it will not be a measure to reduce the wall thickness of the evaporation tube.

The projecting portion 13 'of the inclined stage 13 and the evaporating pipe 2
And a gap 15 is provided between
When the fluid material particles caught on 3 'slide down into the furnace, they are prevented from rubbing against the wall surface. Note that the inclined shelf 1
The inclination angle of 3 is larger than the angle of repose of the fluid material particles, and the fluid material does not accumulate on the inclined shelf 13.

In the second embodiment described above, in addition to the installation of the plurality of inclined shelves 13, each inclined shelf 13 is provided with an overhang portion 13 ′ for the gap between the evaporating tubes 2. Is not indispensable, and even if only the inclined shelf 13 is installed, a remarkable thinning effect of the evaporating tube can be achieved.

[0033]

As described above in detail, the present invention relates to a circulating fluidized bed combustion furnace in which a plurality of evaporating tubes are arranged on a wall surface and a lower refractory material is provided at a lower portion of the wall surface.
There is provided a circulating fluidized bed combustion furnace provided with a nozzle for blowing gas toward the inside of the furnace, above the upper surface of the lower refractory material and between the adjacent evaporating tubes.

According to the circulating fluidized bed combustion furnace of the present invention,
Particles deposited on the upper surface of the lower refractory can be removed by blowing gas toward the inside of the furnace from a nozzle disposed between adjacent evaporation tubes, so that particles on the upper surface of the lower refractory can be removed. This prevents the situation in which the particles are concentrated on only a specific portion of the evaporator tube at a portion where the inclined surfaces of the sediment particles intersect with each other, and the portion of the evaporator tube is worn.

According to another aspect of the present invention, in a circulating fluidized bed combustion furnace in which a plurality of evaporating tubes are arranged on a wall surface and a lower refractory material is provided at a lower portion of the wall surface, a furnace is provided above the lower refractory material. A plurality of shelves having a surface inclined toward the inside and deflecting the flow of the flowing material falling along the wall surface into the furnace are installed.

According to this circulating fluidized bed combustion furnace, particles falling along the wall surface are deflected by the shelf into the furnace,
A reduction in the amount of particles falling on the upper surface of the lower refractory provided at the lower wall surface, and therefore, a reduction in the amount of particles acting on the evaporator tube in the vicinity of the lower refractory, thereby reducing abrasion of the evaporator tube by the particles. Can be.

In addition to the above-described structure in which shelves are provided, the shelves are provided with protrusions that project into gaps between adjacent evaporating tubes, and deflect the flow of the fluid material falling through the gaps into the furnace. With such a configuration, particles falling through the gap formed between the evaporation tubes on the back side of the shelf are received by the overhang portion, guided to the upper surface of the shelf, and together with the particles received by the shelf as described above. The amount of particles deflected to the inside of the furnace and falling on the upper surface of the lower refractory material can be further reduced, and the thinning of the evaporation tube can be prevented well.

Further, the overhang length of the overhang portion is gradually increased from the upper stage to the lower stage so that the flow of the fluid material falling through the gap of the evaporating tube is gradually deflected into the furnace. Since the particles falling in the gap between the evaporating tubes are gradually received by the overhanging portions having different lengths, the particles acting on the evaporating tubes are further dispersed, and the effect of preventing wall thinning of the evaporating tubes can be enhanced. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a circulating fluidized-bed boiler according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a portion A in FIG.

FIG. 3 is a sectional view taken along line AA in FIG.
(C) shows a change in the accumulation state of the fluid material particles on the stage of the lower refractory material.

FIG. 4 is a cross-sectional view of a circulating fluidized-bed boiler according to a second embodiment of the present invention.

5 is an enlarged sectional view of a portion C in FIG. 4, (A) is a transverse sectional view, and (B) is a longitudinal sectional view along the line BB of (A).

6A and 6B are drawings showing a conventional circulating fluidized bed combustion furnace, wherein FIG. 6A is a longitudinal sectional view, and FIG. 6B is a transverse sectional view taken along line CC of FIG.

FIG. 7 is an enlarged sectional view showing a portion B in FIG. 6B, and FIG.
Is a cross-sectional view, and (B) is a longitudinal cross-sectional view along the line DD in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Circulating fluidized-bed boiler main body 2 Evaporation tube 3 Lower refractory material 3 'Stage 4 Fluidizing nozzle 5 Wind box 6 Falling particles 6' Ascending particles 7 Inclined surface 8 Portion of evaporating tube crossing inclined surface of deposited particles 9 Rest Angled inclined surface 10 Valve 11 Nozzle 12 Air piping 13 Inclined shelf 13 'Overhanging portion 14 Inclined shelf support bracket 15 Gap between overhanging portion and evaporating tube 16 Gap plate

Claims (6)

[Claims] 1. A circulating fluidized bed combustion furnace in which a plurality of evaporating tubes are arranged on a wall surface and a lower refractory material is provided at a lower portion of the wall surface, wherein the lower refractory material is adjacent to an upper surface portion of the lower refractory material. A circulating fluidized bed combustion furnace, comprising a nozzle for blowing gas into the furnace between the evaporation tubes. 2. The circulating fluidized bed combustion furnace according to claim 1, wherein
A method for preventing abrasion of an evaporator tube in a circulating fluidized bed combustion furnace, wherein a gas is blown out from the nozzle at regular intervals. 3. The circulating fluidized bed combustion furnace according to claim 1,
A method for preventing abrasion of an evaporator tube in a circulating fluidized bed combustion furnace, wherein a gas is blown out while changing the flow rate from the nozzle. 4. In a circulating fluidized bed combustion furnace in which a plurality of evaporating tubes are arranged on a wall surface and a lower refractory material is provided at a lower portion of the wall surface, the furnace is inclined toward the inside of the furnace above the lower refractory material. A circulating fluidized bed combustion furnace comprising a plurality of shelves, each having a plurality of shelves for deflecting a flow of a fluid material having a surface and descending along a wall surface into the furnace. 5. The circulation system according to claim 1, wherein the shelf is provided with a projecting portion projecting into a gap between the adjacent evaporating pipes, so as to deflect the flow of the fluid material falling down the gap into the furnace. Fluidized bed combustion furnace. 6. The overhanging portion is provided over a plurality of stages of the shelf, the overhanging length of the overhanging portion is gradually increased from an upper stage to a lower stage, and the flow of the fluid material descending through the gap of the evaporating tube is gradually increased. The circulating fluidized bed combustion furnace according to claim 5, wherein the circulating fluidized bed combustion furnace is configured to be deflected to the inside of the furnace.