JPH06193809A - Furnace wall support structure in fluidized bed boiler - Google Patents

Abstract

PURPOSE:To furnish a furnace wall support structure in a fluidized bed boiler which can follow the relative displacement of downcomers and a backstays and transfer smoothly to the backstays a pressure acting on a furnace wall which connects the downcomers. CONSTITUTION:A boiler main body 1 stored in a pressure vessel 4 is constructed of a plurality of downcomers 10 extending vertically at corner parts of a boiler, a flat-surface-shaped furnace wall 12 which has vertical water tubes 11a and fins 11b connecting the water tubes and connects the downcomers 10 being adjacent to each other and backstays 14 surrounding the furnace wall with a space between them. The downcomer 10 and the backstay 14 are connected through the intermediary of a first horizontal member 22 having vertical pins 21 at the opposite end parts and being parallel virtually to the furnace wall and, moreover, the intermediate positions of the furnace wall and the first horizontal member being near the corner part are connected through the intermediary of a second horizontal member 25 having vertical pins 24 at the opposite end parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a furnace wall support structure in a fluidized bed boiler, and more particularly to a furnace wall support structure in a hexagonal 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 is shown in FIG.
As shown in FIG. 1, the boiler main body 1, the cyclone 2, the bed material storage container 3, etc. are stored in the pressure container 4, and the coal C supplied from the outside is burned in the boiler main body 1, The exhaust gas is sent to the cyclone 2, and the exhaust gas from which ash has been removed by the cyclone 2 is supplied to an external gas turbine (not shown) for work (for example, driving a generator). Further, in the boiler body 1, a fluidized bed B in which bed material such as coal ash or sand is fluidized by the air A supplied from below is formed. In the fluidized bed B, steam is generated. Evaporator 5, superheater 6,
And the reheater 7 is 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.

[0003]

An ordinary fluidized bed boiler (normal pressure fluidized bed boiler whose operating pressure is close to atmospheric pressure) has an internal pressure so that exhaust gas, bed material, ash, etc. do not leak outside from the furnace. Is operated at a pressure (for example, about −600 mmAq) slightly lower than the external pressure (atmospheric pressure). On the other hand, a pressurized fluidized bed boiler is similarly operated with the internal pressure of the boiler main body lower than the external pressure (pressure inside the pressure vessel), but the pressure inside the pressure vessel is high (for example, 10 ata), and differential pressure control is generally used. It is difficult, and therefore, the differential pressure becomes large as compared with the atmospheric fluidized bed boiler (for example, about −6000 mmAq). Further, in the pressurized fluidized bed boiler, the internal pressure may become larger than the external pressure (for example, +8000 mmAq) during operation, for example, when the apparatus is stopped. Therefore, in the pressurized fluidized bed boiler, it is necessary to make the boiler main body more resistant to the differential pressure than the normal pressure fluidized bed boiler. for that reason,
In the case where the boiler main body is composed of a plurality of downcomers extending vertically at the corners of the boiler, a planar furnace wall connecting the adjacent downcomers, and a backstay surrounding the furnace wall with a space therebetween. In order to transfer the pressure acting on the furnace wall to the back stay, a small pitch (for example,
It was necessary to connect the furnace wall and the back stay at 300 to 400 mm).

On the other hand, in recent years, there has been a demand for increasing the capacity of such a pressurized fluidized bed boiler, and in order to satisfy this demand, a pressurized fluidized bed boiler having a large furnace wall for connecting downcomers and a large internal volume is researched and developed. Has been done. However, in this pressurized fluidized bed boiler, the relative position between the downcomer and the backstay changes due to the differential pressure and the thermal expansion, so that the furnace wall connecting the downcomer and the furnace wall are surrounded by a space. There was a problem in that the distance from the backstay was partially changed. In particular, at the corner of the boiler body where the backstay is located, the downcomer is displaced relatively outward from the furnace wall in the central part (hereinafter referred to as the central furnace wall) away from the corner, and When the furnace wall in the near part (hereinafter referred to as the corner furnace wall) is connected to the backstay at a small pitch, a large internal stress is generated in the joint part of the corner furnace wall,
There was a problem that caused the occurrence of cracks.

The present invention was devised to solve the above-mentioned problems. That is, the object of the present invention is to
The furnace wall and backstay can be connected at a small pitch, and the relative displacement between the downcomer and backstay can be tracked, so that the downcomer can be connected without causing large internal stress. It is an object of the present invention to provide a furnace wall support structure in a fluidized bed boiler capable of smoothly transmitting the pressure acting on the corner part furnace wall to the back stay.

[0006]

According to the present invention, in a fluidized bed boiler having a boiler body housed in a pressure vessel,
The boiler main body has a plurality of downcomers extending vertically through a corner of the boiler, a vertical water pipe and fins connecting the water pipes, and a planar furnace wall connecting the adjacent downcomers, A back stay surrounding the furnace wall at a distance, and the downcomer and the back stay are connected via a first horizontal member substantially parallel to the furnace wall having vertical pins at both ends, and A furnace wall support structure in a fluidized bed boiler, characterized in that the furnace wall near the corner and an intermediate position of the first horizontal member are connected via second horizontal members having vertical pins at both ends. Will be provided.
According to a preferred embodiment of the present invention, the furnace wall at the central portion apart from the corner portion and the back stay are connected through a pair of inclined connecting members having horizontal pins at both ends, and the upper and lower pairs are connected. A triangular truss is formed by the connecting members of, and the back stay further has at least three protrusions that extend radially outward in the horizontal direction.
It is slidably guided in the radial direction and the vertical direction on the inner surface of the pressure vessel.

[0007]

The relative position between the downcomer and the backstay changes due to differential pressure and thermal expansion. For example, when the downcomer is displaced relatively outward from the central furnace wall, the corners connected to the downcomer are changed. The partial furnace wall is also displaced outward relative to the central furnace wall. However, according to the configuration of the present invention described above, since the downcomer and the backstay are connected via the first horizontal member that is substantially parallel to the furnace wall having vertical pins at both ends, Follow the displacement first
The horizontal member swings around the vertical pin on the back stay side,
The first horizontal member is located approximately parallel to the corner furnace wall between the outwardly displaced back stay and the central furnace wall. Therefore,
Even if the downcomer is displaced relatively outward, the interval between the corner furnace wall and the first horizontal member is maintained substantially constant, and even if the space is connected by the second horizontal member, the corner part is maintained. No large internal stress is generated in the furnace wall. Further, the pressure acting on the corner wall of the corner can be smoothly transmitted to the back stay and the downcomer via the second horizontal member and the first horizontal member.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. 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 structure in which a boiler body 1, a cyclone 2, a bed material storage container 3, etc. are housed in a pressure container 4, as in FIG. 5, and is supplied from the outside. The coal is burned in the boiler body 1, the exhaust gas is sent to the cyclone 2 via the exhaust gas manifold 8, and the exhaust gas from which ash has been removed by the cyclone 2 is supplied to an external gas turbine (not shown) to perform work. It is supposed to do.

FIG. 2 is a horizontal sectional view taken along the line AA of FIG. In this figure, the boiler body 1 has a hexagonal interior in horizontal cross section, and comprises six vertical furnace walls 12 and a closed hexagonal back stay 14, and the furnace walls 12 are substantially the same. It consists of walls 12a and 12b. Further, the inside of the hexagon is divided into three spaces by three virtual alternate long and short dash lines separated from each other by 120 °. That is, the inside of the hexagon is composed of three spaces whose horizontal cross section has two parallel furnaces with two adjacent furnace walls 12a and 12b as two sides of the parallelogram. In each space, parallel to one furnace wall 12a,
A first inner layer tube group 16a having one end adjacent to the other furnace wall 12b and having vertical planes parallel to each other, and the other end of the first inner layer tube group 16a parallel to the one furnace wall 12a And a second inner layer tube group 16b whose one end is adjacent to each other and whose vertical planes are parallel to each other.

FIG. 3 is an enlarged perspective view of portion B in FIG. In this figure, a boiler body 1 includes a plurality of downcomers 10 extending vertically in a corner portion of a boiler, a planar furnace wall 12 connecting adjacent downcomers 10, and a back wall surrounding the furnace walls at intervals. It consists of stay 14. The furnace wall 12 is composed of a vertical water pipe 11a and fins 11b connecting the water pipes 11a, and is configured to flex relatively freely in the radial direction.

The furnace wall 12 and the back stay 14 at the central portion apart from the corner portion are connected via a pair of vertically inclined connecting members 36 having horizontal pins 35 at both ends. The pair of upper and lower inclined connecting members 36 form a triangular truss, and the furnace walls 12a and 12b and the back stay 14 are integrated.

The backstay 14 is slidably held by upper and lower backstay holding metal fittings 30 fixed to the downcomer 10. With this configuration, the back stay 1
4 can be restrained from moving vertically with respect to the downcomer 10, and the backstay 14 can be freely displaced in the radial direction without being restrained by the displacement of the downcomer 10. The backstay gripping metal fitting 30 is held in contact with the protrusions 37 extending in the radial direction on the upper and lower surfaces of the backstay in contact with the upper and lower surfaces. With this configuration, it is possible to prevent the back stay 14 from rotating in the outward direction of the furnace wall surface. Further, the back stay 14 has at least three protrusions 14a extending radially outward in the horizontal direction, and the protrusions 14a can be slid on the inner surface of the pressure container 4 in the radial direction and the vertical direction by the sliding fittings 4a. Is being guided to. With such a configuration, vertical movement and radial movement of the backstay 14 can be permitted, and at the same time, horizontal movement and rotation of the backstay 14 can be prevented.

In FIG. 3, the downcomer 10 and the backstay 14 are connected via a first horizontal member 22 having vertical pins 21 at both ends and substantially parallel to the furnace wall 12. The first horizontal member 22 is preferably separated from the upper surface of the back stay 14 by an appropriate distance. In this case, it is preferable to fix the column member 23 perpendicular to the upper surface of the back stay 14 and connect the upper end of the column member 23 and one end of the first horizontal member 22 via the vertical pin 21.

Further, the furnace wall 12 near the corner (corner furnace wall) 12 and the intermediate position of the first horizontal member 22 are connected via a second horizontal member 25 having vertical pins 24 at both ends. There is. There may be a plurality of second horizontal members 25 for one first horizontal member 22. Although the first horizontal member 22 and the second horizontal member 25 are provided only on the upper side of the back stay 14 in FIG.
It is also preferable to similarly provide the lower side.

FIG. 4 is a partial plan view of portion C in FIG. In this figure, the case where the downcomer 10 is located relatively outward is indicated by a chain double-dashed line. With the configuration described above, the downcomer 10 is displaced relatively outward (1
0 '), the first horizontal member 22 oscillates around the vertical pin 21 on the back stay side following the displacement of the downcomer 10, and the first horizontal member 22 moves outwardly. Corner wall between the stay 10 'and the central wall (1
2 '). Therefore, the downcomer 10 is relatively displaced outward (10 ').
However, the space between the corner furnace wall and the first horizontal member 22 is
Even if it is maintained almost constant and the second horizontal member 25 connects between these, a large internal stress does not occur in the corner wall of the furnace. Further, the pressure acting on the corner furnace walls 12a and 12b can be smoothly transmitted to the back stay 14 and the downcomer 10 'via the second horizontal member and the first horizontal member.

[0016]

As described above, the relative position between the downcomer and the backstay changes due to the differential pressure and the thermal expansion, and, for example, when the downcomer is displaced outward relative to the central furnace wall, The corner furnace wall connected to the downcomer is also displaced outward relative to the central furnace wall. However, according to the configuration of the present invention described above, since the downcomer and the backstay are connected via the first horizontal member substantially parallel to the furnace wall having the vertical pins at both ends, Following the displacement, the first horizontal member swings about the vertical pin on the backstay side, and the first horizontal member is substantially parallel to the corner furnace wall between the backstay displaced outward and the central furnace wall. Located in. Therefore, even if the downcomer is relatively displaced outward, the distance between the corner furnace wall and the first horizontal member is maintained substantially constant, and even if the second horizontal member is used to connect the spaces, No large internal stress is generated on the corner wall. Further, the pressure acting on the corner wall of the corner can be smoothly transmitted to the back stay and the downcomer via the second horizontal member and the first horizontal member.

Therefore, with the furnace wall support structure in the fluidized bed boiler of the present invention, the furnace wall and the back stay can be connected at a small pitch, and the relative displacement between the downcomer and the backstay can be followed. As a result, the pressure acting on the corner wall connecting the downcomers can be smoothly transmitted to the backstay without generating a large internal stress.

[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 an enlarged perspective view of a B part in FIG.

FIG. 4 is a partial plan view of a C portion of FIG.

FIG. 5 is an overall configuration diagram of a conventional pressurized fluidized bed boiler.

[Explanation of symbols]

 1 Boiler main body 2 Cyclone 3 Bed material storage container 4 Pressure container 5 Evaporator 6 Superheater 7 Reheater 8 Exhaust gas manifold 10 Downcomer 11a Water pipe 11b Fins 12a, 12b Furnace wall 14 Backstay 14a Projection 16a First layer inner pipe Group 16b Second layer inner tube group 21 Vertical pin 22 First horizontal member 23 Column member 24 Vertical pin 25 Second horizontal member 30 Backstay gripping metal fitting 35 Horizontal pin 36 Connecting member 37 Projection A Air B Fluidized bed C Coal

Claims (4)

[Claims] 1. A fluidized bed boiler having a boiler body housed in a pressure vessel, wherein the boiler body includes a plurality of downcomers extending vertically at a corner of the boiler, and a vertical water pipe and fins connecting the water pipe. And a back stay that surrounds the furnace wall with a space and that connects the adjacent downcomers, and the downcomer and the backstay have vertical pins at both ends. A second horizontal member that is connected through a first horizontal member that is substantially parallel to the furnace wall, and the furnace wall near the corner and the intermediate position of the first horizontal member have vertical pins at both ends. A furnace wall support structure in a fluidized bed boiler, wherein the furnace wall support structure is connected via 2. The central furnace wall apart from the corner portion and the back stay are connected via a pair of vertically inclined connecting members having horizontal pins at both ends, and the pair of upper and lower connecting members form a triangular shape. -Shaped truss is configured, and further, the back stay has at least three protrusions that extend radially outward in the horizontal direction, and the protrusions are slidable in the radial direction and the vertical direction on the inner surface of the pressure vessel. The furnace wall support structure in the fluidized bed boiler according to claim 1, wherein the furnace wall support structure is provided in the fluidized bed boiler. 3. The boiler body according to claim 1, wherein the boiler main body has a hexagonal horizontal cross section, and includes six vertical furnace walls and a hexagonal closed backstay. Wall support structure in a fluidized bed boiler in Japan. 4. The inside of the hexagon is a parallelogram 3 whose horizontal cross section has two adjacent furnace walls as two sides of the parallelogram.
Each of the spaces is composed of a first group of in-layer tubes parallel to one furnace wall and one end of which is adjacent to the other furnace wall and parallel to each other in the vertical plane, and parallel to one furnace wall. 4. The flow according to claim 3, further comprising: a second inner layer tube group whose one end is adjacent to the other end of the first inner layer tube group and whose vertical planes are parallel to each other. Support structure for inner layer pipe in single layer boiler.