JPH1122901A - Hot gas piping - Google Patents

Abstract

[Problem] To provide a high-temperature gas pipe capable of suppressing abrasion of a pipe while keeping pressure loss low. In a high-temperature gas pipe through which exhaust gas discharged from a boiler flows, an inner wall of a bent portion of the pipe is provided at intervals in a circumferential direction and at intervals in a flow direction,
A plurality of protrusions for generating a vortex are arranged on the downstream side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe having a bent portion due to the flow of a fluid containing fine particles, and more particularly to a high-temperature gas pipe having a bent portion through which exhaust gas discharged from a boiler flows.

[0002]

2. Description of the Related Art With respect to a fluid piping structure having a bent portion through which a fluid flows, a wavy projecting region made of a wear-resistant material is provided on the outer peripheral side wall of the bent portion so that particles included in the flow are applied to the projecting region. Japanese Patent Application Laid-Open No. 50-59816 describes that the particles are prevented from coming into contact with other areas of the pipe due to the particles jumping after being applied.

In addition, the thickness of the outer peripheral side wall of the bent portion is increased to form a step-like projection region, and the flow rate of the fluid is reduced by the resistance of the projection to suppress erosion of the inner surface of the fluid. Japanese Patent Application Laid-Open No. 2-93195 describes that a projection is sacrificed by erosion to suppress a decrease in wall thickness of a tube.

[0004]

However, in high-temperature gas pipes in which boiler exhaust gas or the like flows, the flow is fast and there are many bent portions. Therefore, it is desired to suppress the pressure loss to a low level. However, there is no suggestion about suppressing the wear and the like of the pipe while keeping the pressure loss of the flow low.

Accordingly, an object of the present invention is to provide a high-temperature gas pipe capable of suppressing abrasion and the like of a pipe while keeping pressure loss low.

Another object of the present invention is to provide a combustion plant provided with a high-temperature gas pipe capable of suppressing abrasion of a pipe while keeping pressure loss low.

[0007]

In order to solve the above-mentioned object of the present invention, in a high-temperature gas pipe through which exhaust gas discharged from a boiler flows, a plurality of pipes are provided on an inner wall of a bent portion of the pipe at circumferential intervals. The projections are arranged.

[0008] Thus, while suppressing an increase in pressure loss, particles can be trapped in the vortex discharged from the structure to the main flow in the pipe and trapped in the vortex. This allows
The total amount of ash particles rubbing the wall surface of the bent portion of the pipe can be reduced, and the wear amount of the wall surface can be suppressed.

In the high-temperature gas pipe through which the exhaust gas discharged from the boiler flows, a plurality of projections are arranged on the inner wall of the bent portion of the pipe at intervals from the upstream side to the downstream side of the exhaust gas. .

[0010] Thus, while suppressing an increase in pressure loss, particles can be entrained in the vortex discharged from the structure to the main flow in the pipe, and the particles can be trapped in the vortex. This allows
In a wide range of the bent portion of the pipe, the total amount of ash particles rubbing the wall surface can be reduced, and the wear amount of the wall surface can be suppressed.

In the high-temperature gas pipe through which the exhaust gas discharged from the boiler flows, a projection having an angle of attack with respect to the axial direction of the pipe is disposed on the inner wall of the bent portion of the pipe.

Thus, while suppressing an increase in pressure loss, particles can be engulfed in the vortex discharged from the structure to the main flow in the pipe, and the particles can be satisfactorily collected in the vortex. This makes it possible to reduce the total amount of ash particles rubbing the wall surface in a wide range of the bent portion of the pipe, and to suppress the wear amount of the wall surface.

In order to solve another object of the present invention, in a combustion plant provided with a boiler and a high-temperature gas pipe through which exhaust gas discharged from the boiler flows, an inner wall of a bent portion of the pipe is formed as the distance from the inner wall increases. A plurality of protrusions formed so as to reduce the cross-sectional area are arranged at intervals in the circumferential direction.

Thus, while suppressing an increase in pressure loss, particles can be engulfed in the vortex discharged from the structure to the main flow in the pipe, and the particles can be satisfactorily collected in the vortex. This makes it possible to reduce the total amount of ash particles rubbing the wall surface in a wide range of the bent portion of the pipe, to suppress the abrasion amount of the wall surface, and to obtain a highly reliable and highly efficient combustion plant.

In a combined cycle plant comprising a fluidized bed boiler, a gas turbine driven by flue gas from the boiler, and a high temperature gas pipe for transporting flue gas from the fluidized bed boiler to the gas turbine, A protrusion having an angle of attack with respect to the axial direction of the pipe is arranged on the inner wall of the bent portion.

Thus, while suppressing an increase in pressure loss, particles can be engulfed in the vortex discharged from the structure into the main flow in the pipe, and the particles can be satisfactorily collected in the vortex. This makes it possible to reduce the total amount of ash particles rubbing the wall surface in a wide range of the bent portion of the pipe, to suppress the amount of abrasion of the wall surface, and to obtain a highly reliable and highly efficient combined cycle plant. .

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 3 shows a system diagram of a combined cycle plant using a fluidized-bed boiler. In the fluidized bed boiler 1,
The pulverized coal 4 is burned by the air 3 supplied from the air compressor 2. The high-temperature gas 5 generated by the combustion is transmitted to a heat transfer tube 6 installed in the boiler 1, and steam is generated in the heat transfer tube 6. The steam is led to a steam turbine 7,
The generator 8 is driven. The high-temperature gas 5 is a cyclone 9
After removing the ash particles, the ash particles are transported to the gas turbine 12 via the header 11 by the high-temperature pipe 10. At this time, in the high-temperature gas 5, 200 (μ)
mm) of ash particles 13 which cannot be completely removed even after passing through the cyclone 9 (μmm) may remain. Therefore, if the plant is operated for a long time,
The ash particles 13 may collide with the wall surface of the high-temperature pipe 10 innumerably, causing serious wear on the pipe wall surface. In particular, abrasion becomes remarkable in a bent portion of the high-temperature pipe 10.

FIG. 1 shows a first embodiment of a high-temperature pipe according to the present invention. FIG. 2 shows details of a structure for generating a vortex having an axis of rotation in the main flow direction of the hot pipe.

In FIG. 1, reference numeral 5 denotes a high-temperature gas, and 10 denotes the high-temperature pipe (an enlarged portion of a bent portion, for example, a high-temperature pipe located upstream of the cyclone 9. Alternatively, a high-temperature pipe located downstream of the cyclone is used. Ash particles 13)
4 is a vortex generator (protrusion) that generates a vortex on its downstream side, 1
Reference numeral 5 denotes a vortex generated by the vortex generator 14. In the present embodiment, the vortex generator 14 has a triangular pyramid shape, and is configured to be installed on the outer wall of a bent portion where wear is particularly remarkable.

In this case, the vortex generator 14 is spaced from the upstream side to the downstream side in the flow direction of the pipe.
Are installed. For example, the distance between the vortices generated by one vortex generator 14 and the ash particles 13 increases with the distance from the vortex generator 14.
The distance can be set so that another vortex generator is arranged at a position where the influence on the vortex generator is reduced. Due to the vortex generated by the projection, the ash particles 13 in the high-temperature gas 5 can be prevented from hitting the outer surface of the bent portion of the pipe while suppressing the increase in the pressure loss as a whole, and the wear on the wall surface can be reduced.

FIG. 2 shows an example of the vortex generator 14. The vortex generator 14 is formed, for example, such that the cross-sectional area decreases as the distance from the bottom surface increases. As an example, a triangular pyramid-shaped surface having three vertices 14a, 14b, and 14c (vertex 14a and sides 14b-14c (vertex 1
A line connecting the midpoints of the sides having both ends 4b and 14c) is fixed to the wall surface of the high-temperature pipe so that the angle of elevation becomes α with respect to the main flow direction in the pipe. If the main flow direction is difficult to define, for example, the main flow direction has an angle of attack with respect to the axial direction of the pipe. In the high-temperature pipe, a high-temperature gas 5 flows. At this time, the end of the vortex generator 14, which is a wing-shaped structure, at a portion away from the wall surface of the high-temperature pipe, that is, a protrusion (vertex 14d in FIG. 2).
Behind, a strong vortex 15 having a central axis of rotation in the main flow direction is generated. As the vortex travels downstream, the radius of rotation of the vortex 15 increases and the angular momentum also increases. Ash particles 13 contained in the high temperature gas 5 in the high temperature pipe are collected in the vortex. For this reason, the course of the ash particles 13 changes greatly, and it is possible to reduce the number of particles colliding with the wall surface while suppressing an increase in pressure loss with respect to the flow.

Further, in the present embodiment, the ash particles 13 are formed by setting the flow rate of the flow swirling around the main flow direction in the flow of the vortex 15 within the range of 3 to 5% of the total flow rate.
Can be sufficiently effectively collected. In order to perform such a flow distribution, the vortex generator 14 has an elevation angle α with respect to the main flow of 10 to 20 degrees and a height from a wall surface of the high-temperature pipe in a plane perpendicular to the main flow. What is necessary is just to make it into the range of 3-5% of an average inside diameter. When a plurality of vortex generators 14 are arranged in the circumferential direction, the intervals between the vortex generators 14 can be narrow outside the bend and widened inside the bend. Also, they can be arranged at equal intervals.

By arranging the pipes at a plurality of intervals in the circumferential direction, wear in a wider area can be suppressed. In this example, a triangular pyramid-shaped example is shown, but the present invention is not limited to this as long as it has an angle of attack with respect to the main flow direction of the pipe as described above.

As a comparative example, as shown in FIG. 5, a T-tube (T-shaped joint) 16 is provided at a bent portion to suppress wear.

In a pipe elbow as shown in FIG. 4, a centrifugal force acts on the hot gas 5 and the ash particles 13 flowing inside. Therefore, the ash particles are concentrated in a string shape outside the pipe at the bent portion. The concentrated ash particles collide with the pipe wall and cause wear. As a countermeasure, FIG.
When using a T-tube (T-shaped joint) 16 shown in FIG.
The ash particles 13 concentrate on the outside of the pipe at the bend as in the elbow. The concentrated ash particles collide with the flat portion of the T-tube 16 and change the trajectory of the ash particles as shown in the figure, thereby suppressing the collision with the bent pipe. In the case where the pipe has a plurality of bent portions, the collision at the flat portion of the T-shaped pipe is repeated many times, so that a portion that collides with the bent pipe is generated. In this case, wear occurs on the pipe wall surface at the collision location. In an actual plant, since a large number of bends are present in a high-temperature pipe, it is difficult to suppress wear and the pressure loss is large only by providing a bend by a T-tube. By adopting the structure as in the above-described embodiment, it is possible to suppress abrasion generated on the pipe wall surface while suppressing increase in pressure loss even in a complicated pipe system having a large number of bent portions.

FIG. 6 shows a second embodiment.

In FIG. 6, 5 is a high-temperature gas, 10 is a high-temperature pipe, 13 is ash particles, 14 is a wing-like structure (vortex generator), and 15 is a vortex generated from a wing-like structure plate 20.
In this embodiment, an arbitrary cross section of the high-temperature pipe 10, preferably installed at the bent portion entrance of the high-temperature pipe, is provided with a plurality of central axes of rotation in the mainstream direction over substantially the entire surface at intervals in the circumferential direction. The vortex generator 14 is provided. It should be noted that if a plurality of vortex generators 14 in FIG.
They need not necessarily be arranged on the same straight line. The radius of the vortex from one vortex generator 14 is about twice the height of the wing. Therefore, by installing (circumferential length of pipe cross section) / (wing height × 2) vortex generators 14, particles can be more effectively collected in the vortex, and an increase in pressure loss can be suppressed. Wear can be suppressed. Vortex generator 14
Is provided upstream of the middle of the bend. Further, even when a plurality of sections are arranged from the upstream side to the downstream side in the flow direction, at least one paragraph is provided upstream of the middle of the bent portion.

FIG. 7 shows a third embodiment.

In FIG. 7, 5 is a high-temperature gas, 10 is a high-temperature pipe, 13 is ash particles, 14 is a wing-like structure (vortex generator), and 15 is a vortex generated from a wing-like structure plate 20.
In the present embodiment, three triangular pyramid-shaped vortex generators 14a, 14b, 14c having an appropriate elevation angle with respect to the inner surface of the pipe are provided.
(The structure is the same as in FIG. 2). The height of the blades 14b and 14c in the horizontal direction in FIG.
/ 3 and the wing structure 14 in the longitudinal direction.
The height of “a” is set to 、, and the corner wing-like structures are arranged so that the tips of the wings form three vertices of an equilateral triangle. With this arrangement,
The circulation (the flow rate flowing as a vortex around the central axis) generated from the vortices 15a and 15c generated from the blades 14a and 14c is represented by Γ
And the circulation of the vortex 15b generated from the blade 14b is -Γ / 2
(The sign indicates that the rotation direction of the vortex is opposite.) The elevation angle is adjusted in the range of 10 to 20 degrees between the angular wings 14a to 14c. As a result, the central axes of the three vortices generated from each wing unite while drawing a spiral orbit to form one strong vortex.

As described above, by providing a plurality of structures that generate a vortex having a center of rotation in the main flow direction in the high-temperature pipe, and combining a plurality of vortices generated downstream of the plurality of structures, Ash particles can be more efficiently collected in the high-temperature pipe, the total amount of ash particles rubbing the wall surface of the bent portion of the pipe can be reduced, and the amount of wear on the wall surface can be more effectively suppressed. According to this, the particles can be more effectively collected while suppressing an increase in pressure loss due to the strong vortex formed in the high-temperature pipe.

As described above, in a bent portion of a high-temperature pipe, ash particles are concentrated and a large number of particles rub against the pipe wall surface, so that it is difficult to suppress abrasion generated on the pipe wall surface. This was remarkable in a piping system having many bent portions. According to the present invention, ash particles can be trapped by the vortex formed by the vortex generator installed in the pipe, and abrasion can be efficiently suppressed by suppressing particle collision with a wall surface.

In these embodiments, the combined cycle plant using the fluidized bed boiler has been described. However, the above structure may be applied to a combustion plant that transports exhaust gas from the boiler to another.

[0034]

According to the present invention, it is possible to provide a high-temperature gas pipe capable of suppressing abrasion of the pipe while keeping the pressure loss low.

Further, according to another aspect of the present invention, it is possible to provide a combustion plant including a high-temperature gas pipe capable of suppressing abrasion of a pipe while keeping pressure loss low.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a high-temperature pipe according to the present invention.

FIG. 2 is a detailed view of a vortex generator.

FIG. 3 is a system diagram of a pressurized flow boiler.

FIG. 4 is a schematic view showing occurrence of wear in an elbow portion.

FIG. 5 is a diagram showing a comparative example.

FIG. 6 is a view showing a second embodiment of the high-temperature pipe according to the present invention.

FIG. 7 is a view showing a third embodiment of the high-temperature pipe according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fluidized bed boiler, 2 ... Air compressor, 3 ... Air, 4 ...
Pulverized coal, 5 ... High temperature gas, 6 ... Heat transfer tube, 7 ... Steam turbine, 8 ... Generator, 9 ... Cyclone, 10 ... High temperature pipe, 1
DESCRIPTION OF SYMBOLS 1 ... Header, 12 ... Gas turbine, 13 ... Ash particles, 1
4 vortex generator, 15 vortex generated from vortex generator 14, 16 tee.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Narika Kobayashi 7-2-1, Omika-cho, Hitachi City, Ibaraki Pref. Hitachi, Ltd. Power & Electricity Development Division

Claims (5)

[Claims] 1. A high-temperature gas pipe, wherein a plurality of projections are arranged at intervals in a circumferential direction on an inner wall of a bent portion of the pipe in a high-temperature gas pipe through which exhaust gas discharged from a boiler flows. 2. A high-temperature gas pipe through which exhaust gas discharged from a boiler flows, wherein a plurality of protrusions are arranged on an inner wall of a bent portion of the pipe at intervals from an upstream side to a downstream side of the exhaust gas. Hot gas piping. 3. A high-temperature gas pipe through which exhaust gas discharged from a boiler flows, wherein a projection having an angle of attack with respect to the axial direction of the pipe is disposed on an inner wall of a bent portion of the pipe. Piping. 4. A combustion plant comprising a boiler and a high-temperature gas pipe through which exhaust gas discharged from the boiler flows, wherein a projection formed on an inner wall of a bent portion of the pipe so that a cross-sectional area decreases as the distance from the inner wall surface increases. A plurality of combustion plants are arranged at intervals in the circumferential direction. 5. A combined cycle plant comprising a fluidized-bed boiler, a gas turbine driven by exhaust gas from the boiler, and a high-temperature gas pipe for transporting exhaust gas from the fluidized-bed boiler to the gas turbine. Wherein a projection having an angle of attack with respect to the axial direction of the piping is disposed on the inner wall of the bent portion of the combined cycle plant.