JP3473637B2 - Inner bed tube of pressurized fluidized bed boiler - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressurized fluidized bed boiler, and more particularly to an inner tube of a pressurized fluidized bed boiler.

[0002]

2. Description of the Related Art A pressurized fluidized bed combuster for fluidized combustion of coal under pressure is
The combined cycle combined with a gas turbine has a thermal efficiency of 40% or more, a high in-furnace desulfurization rate, and NO
Since it has features such as a small amount of x generation, it is currently under development as a new boiler replacing the conventional fine powder boiler.

Such a pressurized fluidized bed boiler has, for example, as shown in FIG. 8, a boiler main body 1, a cyclone 2, a bed material storage container 3 and the like stored in a pressure container 4, which is externally connected. The supplied coal C is burned in the boiler main body 1, the exhaust gas is sent to the cyclone 2, and the exhaust gas from which the ash has been removed by the cyclone 2 is supplied to an external gas turbine (not shown) for work (for example, a generator). Drive).

Further, a fluidized bed B in which bed material such as coal ash or sand is fluidized by air A supplied from below is formed in the boiler body 1, and in the fluidized bed B, steam is contained. The evaporator 5, the superheater 6, and the reheater 7 for generating are inserted. Due to the heat generated by the combustion of coal in the fluidized bed B, water is evaporated in the evaporator 5 to become steam, and the steam is further heated in the superheater 6 to become superheated steam, which is provided outside. The steam turbine (not shown) expands and does work. Further, the steam whose temperature has dropped in the steam turbine is reheated in the reheater 7 to become superheated steam, and the work is performed again in the external steam turbine.

[0005]

In such a pressurized fluidized bed boiler, the inside of the fluidized bed B is heated to a high temperature of, for example, 800 ° C. or more due to the combustion of coal, and the boiler body 1, the evaporator 5, the superheater 6, and The heat transfer pipes (hereinafter, referred to as in-layer pipes) arranged in the fluidized bed such as the reheater 7 respectively thermally expand. Therefore, in order to prevent the generation of thermal stress, it is not possible to directly fix the inner layer pipe to the boiler body. Conventionally, a support pipe (not shown) is hung from above the boiler body, and each layer is attached to this support pipe. It had an inner tube attached.

[0006] However, in such an inner-layer pipe, the intervals between the inner-layer pipes in the fluidized bed are apt to vary, and bubbles are greatly developed in a portion where the interval is large. There is a problem that the heat transfer characteristics between the bed material and the inner layer pipe deteriorate due to air bubbles, and on the contrary, the bed material is clogged in the portion where the interval is small, which hinders the thermal expansion of the inner layer tube, There is a problem that the heat transfer characteristics of the inner layer pipe are deteriorated.

That is, as schematically shown in FIG. 9 (A), the bubbles in the fluidized bed become larger due to the pressure drop and coalescence as they rise, and the rising speed of the bubbles is almost proportional to the size of the bubbles. There is a characteristic to do. Therefore, as shown in FIG. 9 (B), if the inner layer pipes 9 are densely and evenly arranged in the fluidized bed, the developed bubbles are divided by the inner layer pipes, so that the bubbles in the fluidized bed are relatively separated. It can be kept small, wear of the inner layer tube is small, and heat transfer characteristics can be kept high. However, if there is variation in the spacing of the inner layer tube, air bubbles are partially generated as shown in FIG. 9 (A). Develops greatly, and there is a problem that the wear of the inner-layer pipe becomes severe and the heat transfer characteristics deteriorate.

Further, in recent years, there has been a demand for increasing the capacity of such a pressurized fluidized bed boiler. Therefore, in a large capacity pressurized fluidized bed boiler, it is necessary to densely arrange a large number of inner pipes in the fluidized bed. Therefore, the above-mentioned problems become more prominent and the structure of the in-layer pipe becomes more complicated.

The present invention was devised to solve such problems. That is, the object of the present invention is to cope with the thermal expansion of the inner-layer pipe, it is possible to arrange a large number of inner-layer pipes densely in the fluidized bed, and to keep the flow in the fluidized bed almost even. Therefore, it is an object of the present invention to provide an inner layer tube of a pressurized fluidized bed boiler which can make the size of bubbles and the heat transfer characteristics of the inner layer tube substantially uniform.

[0010]

According to the present invention, a support tube, which is a heat transfer tube in which a fluid is flown, constitutes a frame having two vertical portions suspended from above in a pressurized fluidized bed. A steam consisting of a reheating tube arranged in a horizontal zigzag shape between the vertical portions of the supporting tube, and an evaporation tube and a superheating tube arranged in a horizontal zigzag shape so as to project in the left and right directions on both front and rear sides of the supporting tube frame. In the in-layer pipe of a pressurized fluidized bed boiler in which a plurality of pipe units are arranged in the front-rear direction in a fluidized bed, dummy pipes are attached to the support pipe vertical portion so as to project to the left and right outside, and the dummy pipe is An inner layer tube of a pressurized fluidized bed boiler is provided, which is a hollow circular tube whose inside is sealed.

According to a preferred embodiment of the present invention, the tip portion of the dummy tube has a shape in which the portion between the vertical portions of the evaporation tube and the superheating tube is short in the horizontal direction and long in the vertical direction.

[0012]

According to the structure of the present invention, since the support pipe is suspended from above in the pressurized fluidized bed, and the evaporation pipe, the superheating pipe, and the reheating pipe are attached to this support pipe, each pipe is It can be thermally expanded freely with the support tube. In addition, since the dummy pipes are attached to the vertical portion of the support pipe so as to project to the outside on the left and right sides, the whole inner pipes including the dummy pipes can be densely and uniformly arranged in the fluidized bed, and the developed bubbles Is divided by the inner layer tube and the dummy tube, and the bubbles in the fluidized bed can be kept relatively small, so that the inner layer tube is less worn and the heat transfer characteristics can be kept high.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. In addition, in each figure, common portions are denoted by the same reference numerals and used. FIG. 1 is an overall configuration diagram of a pressurized fluidized bed boiler to which the present invention is applied. In this figure,
The pressurized fluidized bed boiler has a configuration in which the boiler body 1, the cyclone 2, the bed material storage container 3, and the like are stored in the pressure container 4 as in FIG. 6, and coal supplied from the outside is used in the boiler. Burned in the main body 1, the exhaust gas is sent to the cyclone 2 via the exhaust gas manifold 8, and the cyclone 2
The exhaust gas from which ash has been removed is supplied to an external gas turbine (not shown) for work.

FIG. 2 is a horizontal sectional view taken along line AA of FIG. In this figure, the boiler body 1 has a hexagonal interior in horizontal section, and has six vertical furnace walls 12a, 12b.
And a hexagonal closed back stay 14. The inside of the hexagon is 3 degrees apart from the center by 120 °.
It is divided into three spaces by the virtual dashed-dotted line of the book. That is, the inside of the hexagon has two adjacent furnace walls 12a, 12
The horizontal section with b as the two sides of the parallelogram is parallelogram 3
It consists of space. In each space, one furnace wall 12a
And a first inner layer tube group 16a which is adjacent to the other furnace wall 12b at one end and has vertical planes parallel to each other, and a first inner layer tube group 16a which is parallel to the one furnace wall 12a A second inner layer tube group 16b is arranged, one end of which is adjacent to the other end of 16a and whose vertical planes are parallel to each other.

FIG. 3 shows inner layer tube groups 16a and 1 in FIG.
6b is a side view of the in-layer tube 20 constituting 6b, and FIG.
It is explanatory drawing which isolate | separates and shows the in-layer pipe of. The inner layer tube 20 is
It is attached to a support pipe 18 suspended from above in the boiler body 1, and includes an evaporation pipe 21 for evaporating water, a superheating pipe 22 for heating steam to a high temperature, and a reheating pipe 23 for reheating low-temperature steam. Become. The inner tube 20 of the evaporation tube 21, the superheat tube 22, and the reheat tube 23 has a structure in which a plurality of horizontal tubes, which are vertically spaced apart from each other, are alternately connected at both ends as shown in the drawing, and are supported as a whole. It is constructed in the same vertical plane as the pipe 18.

The support tube 18 is a heat transfer tube which is suspended from above in the pressurized fluidized bed to form a frame having two vertical portions and through which a fluid flows. The support pipe 18 is composed of a rectangular loop portion 18a having a mountain-shaped upper portion, a hanging portion 18b extending upward from the apex of the mountain shape, and a horizontal portion 18c extending from the lower end of the rectangular loop portion 18a to the lower side of the boiler body. The support tube 18 is formed of a hollow tube similar to the in-layer tube, steam is allowed to flow through the interior from the horizontal portion 18c to the hanging portion 18b, and forms a part of the heat transfer tube. . The upper end of the hanging portion 18b is pivotally attached to a fixed portion (not shown) in the boiler body, whereby the support pipe 18 is suspended in the boiler body from above. The horizontal portion 18c has a relatively long horizontal portion and is configured to be easily bent in the vertical direction. As a result, the support tube 18 can be freely thermally expanded in a state of being suspended from above.

The reheat pipe 23 is arranged in a horizontal zigzag pattern between the vertical portions of the support pipe. Most of it is provided inside the rectangular loop portion 18a in the vertical plane of the support tube 18, and steam can be made to flow from the lower end 23a to the upper end 23b to reheat the low-temperature steam. The reheat tube 23 is attached to the support tube 18 by a suitable tube clamp fitting (not shown).

The evaporation pipe 21 and the superheat pipe 22 are arranged in a horizontal zigzag pattern so as to project in the left and right directions on both front and rear sides of the support tube frame (both sides in the direction perpendicular to the paper surface in FIG. 3). Further, the evaporation pipe 21 and the superheater pipe 22 have lower ends 21a, 2 respectively.
Water and steam are allowed to flow from 2a to the upper ends 21b and 22b, respectively, so that evaporation and heating can be performed. Further, the evaporation pipe 21 and the superheat pipe 22 are also attached to the support pipe 18 by appropriate clamp metal fittings like the reheat pipe 23.

With this structure, the evaporation pipe 21 and the superheat pipe 2
2. A plurality of steam pipe units each including a reheat pipe 23 are arranged in the fluidized bed in the front-rear direction (perpendicular to the paper surface in FIG. 3), and all of the in-layer pipes 20 (evaporation pipe 21, superheat pipe 22, reheat pipe) 23) is attached to the support pipe 18 and is hung from above via the suspension portion 18b of the support pipe. Therefore, of the inner layer tubes, for example, if only the evaporation tube 21 is supported by an appropriate means in the boiler body 1, all the inner layer tubes 20 (evaporation tube 21, superheater tube 22, reheat tube 23) are supported. You can The upper end and the lower end of each of the in-layer pipes 20 (evaporation pipe 21, superheating pipe 22, reheating pipe 23) are connected to another pipe (not shown) so that water or steam can pass through the inside.

FIG. 5 is a schematic arrow view taken along line AA of FIG. 3, and FIG. 6 is a schematic arrow view taken along line BB of FIG. As shown in FIGS. 3 to 6, the in-layer pipe of the present invention is further extended to the left and right outside in the vertical portion of the support pipe so that the dummy pipe 26 is formed.
Is attached. The dummy tube 26 is a hollow circular tube whose inside is sealed, and has a shape in which a portion 26b between the evaporating tube 21 and the vertical portion of the superheater tube 22 at the tip thereof is crushed in a short horizontal direction and in a long vertical direction. Has become.

That is, as shown in FIG. 6, the reheat pipes 23 are densely arranged inside the support pipe 18, but the support pipe 1
On the outside of 8, the region sandwiched between the evaporation pipe 21 and the superheat pipe 22 is wide open, and a dummy pipe 26 is attached to this portion, and the bubbles of the fluidized bed developed in this portion are divided by the dummy pipe 26. It is designed to make fine bubbles. As shown in FIGS. 3 and 4, it is preferable that a plurality of dummy tubes 26 be provided at intervals in the vertical direction.

FIG. 7 is an enlarged view (A) of the C portion of FIGS. 3 and 4, and a sectional view taken along the line AA (B) and a view on arrow B (C).
Is. As shown in FIG. 7 (A), the dummy tube 26 is a horizontal tube having one end 26a fixed to the outside of the support tube 18,
As shown in FIGS. 7B and 7C, the vicinity of the other end 26b is deformed into an elliptical shape that is short in the horizontal direction and long in the vertical direction. A closing plate 27 is welded to the other end face to seal the inside.

With this structure, the dummy tube 26
Bubbles developed in the area sandwiched between the evaporation pipe 21 and the superheater pipe 22 outside the support pipe 18 are divided by the dummy pipes, so that the bubbles in the fluidized bed can be kept relatively small and wear of the in-layer pipes can be prevented. It is possible to reduce the amount and keep the heat transfer characteristics high. It should be noted that the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[0024]

As described above, the inner layer tube of the pressurized fluidized bed boiler of the present invention can cope with the thermal expansion of the inner layer tube, and a large number of inner layer tubes are densely arranged in the fluidized bed. And has an excellent effect that the flow in the fluidized bed can be maintained substantially evenly, and thereby the size of the bubbles and the heat transfer characteristics of the inner tube can be made substantially uniform. .

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a pressurized fluidized bed boiler to which the present invention is applied.

FIG. 2 is a horizontal sectional view taken along line AA of FIG.

FIG. 3 is a side view of an inner layer tube 20 forming the inner layer tube groups 16a and 16b in FIG.

FIG. 4 is an explanatory view showing the inner layer tube of FIG. 3 separately.

5 is a schematic arrow view taken along the line AA of FIG.

6 is a schematic arrow view taken along line BB of FIG.

FIG. 7 is an enlarged view of a C portion of FIG.

FIG. 8 is an overall configuration diagram of a conventional pressurized fluidized bed boiler.

FIG. 9 is a diagram schematically showing the behavior of a fluidized bed.

[Explanation of symbols]

1 Boiler body 2 cyclone 3 bed material storage containers 4 Pressure vessel 5 evaporator 6 superheater 7 Reheater 8 exhaust gas manifold 9-layer inner tube 12a, 12b furnace wall 14 Back stay 16a First layer inner tube group 16b Second layer inner tube group 18 Support tube 20 layer inner tube 21 evaporation tube 22 Superheated tube 23 Reheat tube 26 dummy tubes 27 Closure plate A air B fluidized bed C coal

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Claims (2)

(57) [Claims] 1. A device suspended from above in a pressurized fluidized bed 2
A support tube that is a heat transfer tube in which a fluid flows inside, a reheat tube that is arranged in a horizontal zigzag pattern between the vertical parts of the support tube, and a front and rear side of the support tube frame. In the in-layer pipe of the pressurized fluidized bed boiler, in which a plurality of steam pipe units each consisting of an evaporation pipe and a superheating pipe arranged in a horizontal zigzag shape so as to project in the left-right direction are arranged in the fluidized bed side by side in the front-rear direction, An inner-layer pipe of a pressurized fluidized bed boiler, wherein a dummy pipe is attached to the vertical portion of the support pipe so as to project to the outside on the left and right sides, and the dummy pipe is a hollow circular pipe whose inside is sealed. 2. The pressurized fluidized bed boiler according to claim 1, wherein the tip portion of the dummy tube has a shape in which a portion between the vertical portions of the evaporation tube and the superheating tube is short in the horizontal direction and long in the vertical direction. Inner layer tube.