JP3512487B2 - Waste heat recovery boiler - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust heat recovery boiler for recovering exhaust heat from the exhaust gas of a general water pipe type boiler apparatus or a gas turbine, for example, in a duct provided in this boiler. The present invention relates to an exhaust heat recovery boiler that can suppress air flow noise.

[0002]

2. Description of the Related Art A conventional exhaust heat recovery boiler is, for example,
It is configured as shown in FIGS. 13 and 14. A duct 1 for discharging hot gas is connected to a furnace 12 such as a gas turbine, and a ventilator 13 is provided near the outlet of the duct 1. Inside the duct 1, a heat exchanger tube group 3 for exchanging heat with the hot gas to recover the exhaust heat is provided. This heat exchanger tube group 3 is arranged orthogonal to the flow direction of the hot gas flowing in the duct 1, and this hot gas is
Heat is exchanged so as to traverse these heat exchanger tube groups 3. Further, the duct 1 is provided with an inlet diffuser 5 and an outlet diffuser 6, and inside the duct 1, a denitration element 7 is arranged between the heat exchanger tube groups 3. As a result, the hot gas generated in the furnace 12 is discharged into the ventilator 13
Is sucked by and passes through the inside of the duct 1,
Heat is exchanged by the heat exchanger tube group 3, denitrified by the denitration element 7, and then discharged. As a result, the exhaust heat of the hot gas is recovered.

When hot gas flows through the duct 1 having such a heat exchanger tube group 3, when the hot gas passes through the tube group 3, an air flow noise is generated. This air flow sound has an outstanding frequency that is approximately proportional to the flow rate of hot gas, and this relationship is represented by the Strouhal number (St). This Strouhal number is defined by the following equation. St = (fs · d) / Vmax where fs is the frequency of the air flow sound generated from the tube group, d
Is the diameter of the heat transfer tube, and Vmax is the maximum flow velocity of the gas passing between the tubes. The Strouhal number has a unique value depending on the arrangement of the heat exchanger tube group 3.

On the other hand, the duct 1 structurally functions as a Helmholtz resonance box, and the reflection of the sound waves between the wall surfaces of the duct 1 becomes a standing wave and the generated sound waves are overlapped with each other. It has the characteristic of amplifying sound.
This specific frequency is the resonance frequency.

When the wavelength of the sound generated from the heat exchanger tube group 3 due to the air flow and the resonance frequency of the duct 1 match, the air flow sound is amplified by self-excited vibration depending on the conditions to generate a loud sound. Such a phenomenon has been variously reported as an air column resonance phenomenon due to the heat exchanger tube group 3, and measures for preventing it have been taken.

FIG. 16 shows the conventionally known state of occurrence of the air column resonance phenomenon and the preventive measures by the baffle plate. The air column resonance phenomenon due to the heat exchanger tube group 3 is considered to generate a standing wave in the direction orthogonal to the tubes in the cross section of the duct 1 (that is, the width direction of the duct 1). The frequency (f (n)) of the air column resonance generated in the width direction of the duct 1 is expressed by the following equation. f (n) = (n · C) / (2 · L) where L is the width of the duct 1, C is the speed of sound, and n is the mode of resonance generation (n = 1, 2, 3 ...)
Is. In FIG. 16, the generation state of the standing wave 14 of the air flow sound generated in a part of the duct 1 and in the width direction of the duct 1 (however,
(when n = 1, 2) is shown.

Considering the sound wave by the velocity component of air, the characteristic of the standing wave 14 is that the positions of the antinode and the node of the sound do not change. Further, the wall surface on which the standing wave 14 is present must always be a node of sound.

As a measure for preventing this air column resonance phenomenon, a plurality of baffle plates 4 are provided between the heat transfer tubes 2 of the heat exchanger tube group 3 so as to divide the duct 1 in the width direction. As a result, a portion of the standing wave 14 that is not a node becomes the wall surface of the baffle plate 4, and the occurrence of the air column resonance phenomenon is suppressed. Measures for preventing such air column resonance phenomenon are widely and generally performed.

[0009]

The measure for preventing the air column resonance phenomenon is intended for the standing wave generated in the width direction of the duct 1, and the baffle plate 4 is generated in the width direction of the duct 1. It is effective for standing waves. However, duct 1
A standing wave is also generated in the longitudinal direction, and the measures described above do not work effectively on the standing wave in the longitudinal direction. Therefore, conventionally, construction of a preventive measure against this standing wave in the longitudinal direction is desired.

The object of the present invention was made in view of the above-mentioned circumstances, and exhaust heat recovery capable of suppressing the air column resonance phenomenon occurring in the longitudinal direction of the duct provided with the heat exchanger tube group. To provide a boiler.

[0011]

In order to achieve this object, an exhaust heat recovery boiler according to claim 1 of the present invention is provided in a duct for guiding hot gas generated in a furnace or the like into the duct. An exhaust heat recovery boiler that recovers exhaust heat by exchanging heat with a heat exchanger tube group, wherein the inner wall of the duct is the inner wall of the portion where the flow passage cross-sectional area of the duct changes along the flow direction .
Flow toward the inside of the duct from the
A number of ridges extending along the direction are arranged in the circumferential direction of the duct.
It was set, suppressing the sound absorbing structure of the reflection of sound waves traveling in the longitudinal direction in the duct is characterized by being provided.

Further, the exhaust heat recovery boiler according to claim 2 is
An exhaust heat recovery boiler for guiding hot gas generated in a furnace or the like into a duct and exchanging heat with a heat exchanger tube group provided in the duct, wherein the duct is bent. From the inner wall of the duct to the inner wall of the part
Is characterized in that a large number of convex ridges projecting in the direction toward are arranged in parallel, and a sound absorbing structure for suppressing reflection of sound waves traveling in the longitudinal direction inside the duct is provided.

Further, the exhaust heat recovery boiler according to claim 3 guides the hot gas generated in the furnace or the like into the duct and exchanges heat with the heat exchanger tube group provided in the duct to recover the exhaust heat. In the exhaust heat recovery boiler, the duct is connected to the side wall of the chimney that discharges the hot gas, and the portion of the inner wall of the chimney where the duct is connected is
A ridge protruding from the inner wall toward the inside of the duct
Are arranged side by side along the circumferential direction of the chimney, and a sound absorbing structure for suppressing reflection of sound waves traveling in the longitudinal direction inside the duct is provided.

Further, the exhaust heat recovery boiler according to claim 4 guides the hot gas generated in the furnace or the like into the duct and exchanges heat with the heat exchanger tube group provided in the duct to generate the exhaust heat. In the exhaust heat recovery boiler for recovering the heat exchanger, the heat exchanger tube group in the duct is arranged in the inner wall portion where the flow passage cross-sectional area in the duct changes along the flow direction, in the inner wall portion where the duct is bent. In a portion not provided, a lattice-shaped baffle plate extending in the flow direction is provided, and the lattice-shaped baffle plate is
The length in the flow direction is formed non-uniformly, and the lattice-shaped baffle plate is also characterized in that the positions of the front end portion or the rear end portion in the flow direction are also formed non-uniformly.

Further, the exhaust heat recovery boiler according to claim 5 guides the hot gas generated in the furnace or the like into the duct and exchanges heat with the heat exchanger tube group provided in the duct, thereby exhausting the heat. In the exhaust heat recovery boiler for recovering the heat exchanger, a grid-shaped baffle plate extending in the flow direction is provided in the duct where the heat exchanger tube group is arranged. The lattice-shaped baffle plate is characterized in that the positions of the front end portion or the rear end portion in the flow direction are also formed unevenly.

Further, the exhaust heat recovery boiler according to claim 8 guides the hot gas generated in the furnace or the like into the duct,
Exhaust heat is recovered by exchanging heat with the heat exchanger tubes provided in the duct.
An exhaust heat recovery boiler that collects heat and denitrates the hot gas
Denitration elements for are disposed within the duct, the
At the front or rear end of the denitration element in the flow direction,
The wedges that extend downward and the wedges that extend laterally
It is characterized in that the parts arranged in parallel are formed so as to be alternately arranged .

Furthermore, the exhaust heat recovery boiler according to claim 9 guides the hot gas generated in the furnace or the like into the duct and exchanges heat with the heat exchanger tube group provided in the duct, thereby exhausting heat. In the exhaust heat recovery boiler for recovering, the denitration element for denitrifying hot gas is arranged in the duct, and the position of the front end or the rear end of the denitration element in the flow direction is unevenly arranged. Is characterized by.

[0018]

First, as a premise of the present invention, the air flow sound in the duct will be described with reference to FIG. This FIG.
[Fig. 4] is a schematic diagram showing a traveling direction of an air flow sound generated from a pipe. The sound generated from the heat transfer tube 2 propagates not only in the width direction of the duct but also in the longitudinal direction and the height direction, but the sound has directivity and the sound propagating in each direction is different. However, since sound has a characteristic of being reflected and diffracted, the sound source of air column resonance in the longitudinal direction of the duct, which is the object of the present invention, has a width and The sound in the height direction may change in the longitudinal direction due to reflection and diffraction. Further, a traveling wave is also generated in the longitudinal direction from the standing wave generated in the width direction of the duct. Further, as a sound source other than the heat exchanger tube group, a blower and a gas turbine sound source may be considered. As described above, FIGS.
The baffle plate 4 shown in is effective only for the standing wave generated in the width direction of FIG.

Sounds, such as diversions in the duct, cross-sectional area enlargement or reduction, or structures placed in the duct, cause reflections in either case. When the phase of the traveling sound wave and the phase of the reflected sound wave match, a standing wave is formed and an air column resonance phenomenon occurs.

Therefore, in the present invention, claims 1 to 3,
According to the eighth aspect , the reflection itself of the sound wave in the flow direction of the duct is suppressed, so that the standing wave in the longitudinal direction is prevented from occurring and the occurrence of the air column resonance phenomenon is prevented.

Further, in the present invention, claims 4 to 7 and
In claim 9 , the phase of the sound wave traveling in the longitudinal direction of the duct and the phase of the reflected sound wave are made different in the longitudinal direction of the duct to prevent the superposition of both sound waves, whereby the constant of the longitudinal direction is determined. The occurrence of standing waves is prevented and the occurrence of air column resonance phenomenon is prevented.

The operation of the present invention will be specifically described below.

According to the first, second and third aspects, at the inner wall portion where the flow passage cross-sectional area in the duct changes along the flow direction,
Alternatively, the sound absorbing structure is provided on the inner wall portion where the duct is bent. Further, a sound absorbing structure is provided on at least a portion of the inner wall of the chimney that is connected to the duct. Therefore, in such a portion, the sound wave traveling in the longitudinal direction of the duct is suppressed from being reflected by the sound absorbing structure. As a result, a standing wave is not generated in the longitudinal direction of the duct, and the airflow sound is attenuated in the duct or is emitted as it is from the chimney to the outside. Therefore, noise due to the air column resonance phenomenon is prevented.

According to the fourth and fifth aspects, the inner wall portion where the flow passage cross-sectional area in the duct changes along the flow direction, the inner wall portion where the duct is bent, or the heat inside the duct A lattice-shaped baffle plate extending in the flow direction is provided at a portion where the exchanger tube group is not arranged or at a portion where the heat exchanger tube group is arranged. Moreover, the lattice-shaped baffle plate has a non-uniform length in the flow direction,
Moreover, the positions of the front end portion or the rear end portion in the flow direction are also formed unevenly. Therefore, the sound wave traveling in the longitudinal direction of the duct is reflected by the lattice-shaped baffle plate, but the phase of the reflected sound wave and the phase of the sound wave traveling in the longitudinal direction are made different in the longitudinal direction of the duct. Sound waves are not superimposed. As a result, no standing wave is generated in the longitudinal direction of the duct, and noise due to the air column resonance phenomenon is prevented.

Further, according to claim 8, the front end portion or the rear end portion in the flow direction of the denitration element is formed in a wedge shape protruding in the front or rear direction. Therefore, the front end portion or the rear end portion of the wedge-shaped denitration element is the above-mentioned claim 1.
The sound wave propagating in the longitudinal direction of the duct has the same function as that of the sound absorbing structures 3 to 3, and its reflection is suppressed by the wedge shape. As a result, no standing wave is generated in the longitudinal direction of the duct, and noise due to the air column resonance phenomenon is prevented.

Further, according to the ninth aspect, the positions of the front end portion or the rear end portion in the flow direction of the denitration element are arranged unevenly. As a result, similarly to the case of claim 4 or 5, the sound wave traveling in the longitudinal direction of the duct is reflected by the non-uniform arrangement, but the phase of the reflected sound wave and the phase of the sound wave traveling in the longitudinal direction are Are varied in the longitudinal direction of the duct, so that both sound waves are not superposed. As a result, no standing wave is generated in the longitudinal direction of the duct, and noise due to the air column resonance phenomenon is prevented.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Exhaust heat recovery boilers according to embodiments of the present invention will be described below with reference to the drawings.

First, an exhaust heat recovery boiler according to the first embodiment of the present invention will be described with reference to FIGS. Figure 1
It is sectional drawing of the duct and chimney of the exhaust heat recovery boiler which concerns on 1st Example of this invention, FIG. 2 is a figure of the arrow [A] of FIG. 1, and FIG. FIG.

As shown in FIG. 1, a duct 1 for discharging hot gas is connected to a furnace 12 (see FIG. 12) such as a gas turbine, and a ventilator 13 ( (See FIG. 12). Inside the duct 1, a heat exchanger tube group 3 for exchanging heat with the hot gas to recover the exhaust heat is provided. This heat exchanger tube group 3 is arranged orthogonal to the flow direction of the hot gas flowing in the duct 1,
This hot gas is heat-exchanged so as to traverse these heat exchanger tube groups 3. Further, the duct 1 is provided with an inlet diffuser 5 and an outlet diffuser 6, and inside the duct 1, a denitration element 7 is arranged between the heat exchanger tube groups 3. Further, a chimney 8 is connected to the outlet diffuser 6 of the duct 1.

As a result, the hot gas generated in the furnace 12 is sucked by the ventilator 13 and passes through the inside of the duct 1. During this, heat is exchanged by the heat exchanger tube group 3 and by the denitration element 7. After being denitrated, it is discharged through the chimney 8. As a result, the exhaust heat of the hot gas is recovered.

A sound absorbing structure 21 is provided on the inner wall of the inlet diffuser 5, a sound absorbing structure 22 is also provided on the inner wall of the outlet diffuser 6, and the chimney 8 is further provided.
The sound absorbing structure 23 is provided on the inner wall of the portion corresponding to the connecting portion with the duct 1.

As shown in FIG. 2, the sound absorbing structures 21 and 22 are formed so as to expand or contract in diameter in the flow direction, and the inner walls of these sound absorbing structures 21 and 22 have a large number of projections 24 (or wedge shapes).
Is formed to be inclined. These ridges 24
Is formed of a material that can absorb sound waves without reflecting them.

Also, in the sound absorbing structure 23, as shown in FIG. 3, a large number of projections 25 (or wedge shapes) are provided in an annular shape along the inner wall of the chimney in a plurality of steps. This ridge 2
5 is also made of a material that can absorb sound waves without reflecting them. Furthermore, the sound absorbing structure 23 does not have to be provided over the entire circumference of the inner wall of the chimney 8, but may be provided at least at a part thereof.

Next, the operation according to the first embodiment will be described.

Sound waves are easily reflected when the cross-sectional shape of the duct changes, and normally, sound waves traveling in the longitudinal direction of the duct are reflected at the diffuser parts 5 and 6 and the joint with the chimney 8. , May form standing waves.
However, in the present embodiment, the sound absorbing structures 21, 22, and 23 having the protrusions 24 and 25 formed therein suppress the reflection of sound waves traveling in the longitudinal direction of the duct 1. As a result, a standing wave is not generated in the longitudinal direction of the duct 1, and the airflow sound is attenuated in the duct 1 or is emitted to the outside from the chimney 8 as it is. Therefore, noise due to the air column resonance phenomenon is prevented.

Next, an exhaust heat recovery boiler according to a second embodiment of the present invention will be described with reference to FIGS. 4 to 6. Figure 4
It is sectional drawing of the duct and chimney of the exhaust heat recovery boiler which concerns on 2nd Example of this invention, FIG.5 (a) is arrow [C] of FIG.
5 (b) is a side view of the baffle plate of FIG. 5 (a), and FIG. 6 is a perspective view of the baffle plate shown in FIG.

As shown in FIG. 4, on the inner wall of the inlet diffuser 5, between the heat exchanger tube groups 3 on the relatively upstream side in the duct 1, on the relatively downstream side in the duct 1, and at the outlet diffuser 6. Lattice-shaped baffle plates 31, 3 on the inner walls of the
2, 33, 34 are provided. These baffle plates are, as shown in FIGS. 5 and 6 as an example of the baffle plate 33,
Two vertical plates 35, 36 are provided, and these vertical plates 35, 3
Two horizontal plates 37 and 38 are provided so as to intersect with 6,
As a result, the overall shape is configured in a lattice shape. Moreover, each of the vertical plates 35, 36 and the horizontal plates 37, 38 is formed in a polygonal shape, so that the length in the gas flow direction is variously changed to be non-uniform.
The positions of the front end portions and the rear end portions of the horizontal plates 5, 36 and the horizontal plates 37, 38 are also variously changed and made uneven.

Next, the principle of operation of the second embodiment will be described with reference to FIG. FIG. 7 shows a baffle plate B extending in the flow direction and having the same length in the flow direction, and the upstream baffle plate B and the downstream baffle plate B have the same distance. Has been done. In such cases,
Experiments by the present inventor have confirmed that a standing wave is generated in the flow direction (that is, the longitudinal direction of the duct) between the upstream baffle plate B and the downstream baffle plate B. That is, in the case of the experiment of FIG. 7, since the reflection of the traveling wave of the sound wave in the flow direction by the baffle plate B is constant in the cross section of the duct 1, the phase of the reflected sound wave and the phase of the sound wave of the traveling wave are different. Are the same, and standing waves are being generated.

On the other hand, in the baffle plates 31 to 34 according to the second embodiment, the vertical plates 35 and 36 and the horizontal plates 37 and 38.
The lengths in the flow direction are made uneven, and the positions of the front end portion and the rear end portion are also made uneven. for that reason,
The sound wave traveling in the longitudinal direction of the duct 1 is reflected by the lattice-shaped baffle plates 31 to 34, but if the phase of the reflected sound wave and the phase of the sound wave traveling in the longitudinal direction are different in the longitudinal direction of the duct 1. Both sound waves are not superposed. As a result, no standing wave is generated in the longitudinal direction of the duct 1, and noise due to the air column resonance phenomenon is prevented.

Next, a modification of the second embodiment will be described with reference to FIG. In the second embodiment, as shown in FIGS. 4 and 6, the lattice-shaped baffle plates 32 and 33 are arranged at positions where the heat exchanger tube group 3 is not provided in the gas flow direction. On the other hand, in this modification, the lattice-shaped baffle plates 32 and 33 are arranged at the same position as the position where the heat exchanger tube group 3 is provided in the gas flow direction. Also in this case, the vertical plates 35, 36 and the horizontal plates 37, 38
The lengths in the flow direction are made uneven, and the positions of the front end portion and the rear end portion are also made uneven. for that reason,
The sound wave traveling in the longitudinal direction of the duct 1 is reflected by the lattice-shaped baffle plates 31 to 34, but if the phase of the reflected sound wave and the phase of the sound wave traveling in the longitudinal direction are different in the longitudinal direction of the duct 1. Both sound waves are not superposed. As a result, no standing wave is generated in the longitudinal direction of the duct 1.

Next, an exhaust heat recovery boiler according to the third embodiment of the present invention will be described with reference to FIG. FIG. 9 is a perspective view of a denitration element provided in the exhaust heat recovery boiler according to the third embodiment of the present invention. In the present embodiment, the front end portion and the rear end portion in the flow direction of the denitration element 7 are formed in the wedge-shaped portions 41, 42 protruding in the front or rear direction. Wedge-shaped portion 41
Has a protruding ridge line extending in the vertical direction, and the wedge-shaped portion 42
Has its ridge extending laterally.

The operation of this embodiment is basically the same as that of the first embodiment, and the reflection of the sound wave traveling in the longitudinal direction of the duct is suppressed by the wedge-shaped portions 41 and 42. As a result, standing waves are not generated in the longitudinal direction of the duct,
Noise due to the air column resonance phenomenon is prevented.

Next, an exhaust heat recovery boiler according to the fourth embodiment of the present invention will be described with reference to FIG. FIG. 10 is a perspective view of the denitration element provided in the exhaust heat recovery boiler according to the fourth embodiment of the present invention. In this embodiment, the elements 7 are variously displaced so that their positions are non-uniform in the flow direction. The operation of this embodiment is basically the same as that of the second embodiment, and the sound wave traveling in the longitudinal direction of the duct 1 is reflected by the non-uniform arrangement, but the phase of the reflected sound wave and the longitudinal direction The phase of the traveling sound wave is made different in the longitudinal direction of the duct 1, so that both sound waves are not superposed. As a result, no standing wave is generated in the longitudinal direction of the duct 1, and noise due to the air column resonance phenomenon is prevented.

Next, an exhaust heat recovery boiler according to the fifth embodiment of the present invention will be described with reference to FIG. FIG. 11 is a sectional view of a duct provided in the exhaust heat recovery boiler according to the fifth embodiment of the present invention. In this embodiment, sound absorbing structures 51 and 52 are arranged on the inner walls of the inlet diffuser 5 and the outlet diffuser 6 as in the first embodiment. In this embodiment, in particular, the wall surfaces of the sound absorbing structures 51 and 52 are made of a perforated plate, and the perforated plate sound absorbing wall in which a sound absorbing material is housed is formed.

The operation of this embodiment is basically the same as that of the first embodiment, and the sound absorbing structures 51 and 52 suppress the reflection of the sound waves traveling in the longitudinal direction of the duct. As a result, no standing wave is generated in the longitudinal direction of the duct, and noise due to the air column resonance phenomenon is prevented.

Next, an exhaust heat recovery boiler according to the sixth embodiment of the present invention will be described with reference to FIG. FIG. 12 is a sectional view of an exhaust heat recovery boiler according to the sixth embodiment of the present invention.
In this embodiment, the sound absorbing structures 61, 62, 63, 64 having the same structure as in the first embodiment are provided on the inner wall of each bent portion of the duct 1.
65 is provided. Further, between the heat exchanger tube group 3, a lattice-shaped baffle plate 71 having the same configuration as that of the second embodiment is provided.
Is provided.

Therefore, the sound generated when the duct changes direction, the cross-sectional area increases or decreases, or when a structure is arranged in the duct causes reflection in any case.
In this embodiment, the sound absorbing structures 61 to 65 suppress the reflection of sound waves traveling in the longitudinal direction of the duct.
As a result, no standing wave is generated in the longitudinal direction of the duct, and the sound wave traveling in the longitudinal direction of the duct 1 is reflected by the arrangement of the lattice-shaped baffle plate 71, but the phase of the reflected sound wave is reduced. And the phase of the sound wave traveling in the longitudinal direction is made different in the longitudinal direction of the duct 1, both sound waves are not superposed, and a standing wave is not generated in the longitudinal direction of the duct 1. As a result, the air column Noise due to the resonance phenomenon is prevented.

The present invention is not limited to the above-mentioned embodiments, and can be variously modified.

[0049]

As described above, according to the first, second and third aspects, the duct is bent at the inner wall portion where the flow passage cross-sectional area in the duct changes along the flow direction. A sound absorbing structure is provided on the inner wall portion. Further, a sound absorbing structure is provided on at least a portion of the inner wall of the chimney that is connected to the duct. Therefore, in such a portion, the sound wave traveling in the longitudinal direction of the duct is suppressed from being reflected by the sound absorbing structure. As a result, the standing wave is not generated in the longitudinal direction of the duct, and the airflow sound is attenuated in the duct or is emitted as it is from the chimney to the outside. Therefore, noise due to the air column resonance phenomenon is prevented.

According to the fourth and fifth aspects, the inner wall portion where the flow passage cross-sectional area in the duct changes along the flow direction, the inner wall portion where the duct is bent, or the heat inside the duct. A lattice-shaped baffle plate extending in the flow direction is provided at a portion where the exchanger tube group is not arranged or at a portion where the heat exchanger tube group is arranged. Moreover, the lattice-shaped baffle plate has a non-uniform length in the flow direction,
Moreover, the positions of the front end portion or the rear end portion in the flow direction are also formed unevenly. Therefore, the sound wave traveling in the longitudinal direction of the duct is reflected by the lattice-shaped baffle plate, but the phase of the reflected sound wave and the phase of the sound wave traveling in the longitudinal direction are made different in the longitudinal direction of the duct. Sound waves are not superimposed. As a result, no standing wave is generated in the longitudinal direction of the duct, and noise due to the air column resonance phenomenon is prevented.

Further, according to the eighth aspect, the front end portion or the rear end portion in the flow direction of the denitration element is formed in a wedge shape protruding in the front or rear direction. Therefore, the front end portion or the rear end portion of the wedge-shaped denitration element is the above-mentioned claim 1.
The sound wave propagating in the longitudinal direction of the duct has the same function as that of the sound absorbing structures 3 to 3, and its reflection is suppressed by the wedge shape. As a result, no standing wave is generated in the longitudinal direction of the duct, and noise due to the air column resonance phenomenon is prevented.

Further, according to the ninth aspect, the positions of the front end portion or the rear end portion in the flow direction of the denitration element are arranged unevenly. As a result, similarly to the case of claim 4 or 5, the sound wave traveling in the longitudinal direction of the duct is reflected by the non-uniform arrangement, but the phase of the reflected sound wave and the phase of the sound wave traveling in the longitudinal direction are Are varied in the longitudinal direction of the duct, so that both sound waves are not superposed. As a result, no standing wave is generated in the longitudinal direction of the duct, and noise due to the air column resonance phenomenon is prevented.

[Brief description of drawings]

FIG. 1 is a sectional view of a duct and a chimney of an exhaust heat recovery boiler according to a first embodiment of the present invention.

FIG. 2 is a view taken along the arrow [A] in FIG.

FIG. 3 is a view taken along the arrow [B] in FIG.

FIG. 4 is a sectional view of a duct and a chimney of an exhaust heat recovery boiler according to a second embodiment of the present invention.

5 (a) is a view taken along the arrow [C] of FIG.
FIG. 5B is a side view of the baffle plate of FIG.

6 is a perspective view of the baffle plate shown in FIG.

FIG. 7 is an explanatory diagram showing the generation of standing waves in the gas flow direction.

FIG. 8 is a perspective view of a baffle plate according to a modification of the second embodiment of the present invention.

FIG. 9 is a perspective view of a denitration element provided in an exhaust heat recovery boiler according to a third embodiment of the present invention.

FIG. 10 is a perspective view of a denitration element provided in an exhaust heat recovery boiler according to a fourth embodiment of the present invention.

FIG. 11 is a perspective view of a duct provided in an exhaust heat recovery boiler according to a fifth embodiment of the present invention.

FIG. 12 is a sectional view of an exhaust heat recovery boiler according to a sixth embodiment of the present invention.

FIG. 13 is a cross-sectional view of a duct of a conventional exhaust heat recovery boiler.

FIG. 14 is a cross-sectional view of a conventional exhaust heat recovery boiler.

FIG. 15 is a schematic diagram showing the direction of airflow sound generation.

FIG. 16 is a schematic plan view of a conventional duct structure for preventing air column sound resonance.

[Explanation of symbols]

1 duct 3 heat exchanger tube group 5 entrance diffuser 6 Exit diffuser 7 Denitration element 8 chimney 21,22,23 sound absorbing structure 31, 32, 33, 34 Lattice baffle plate 41,42 wedge-shaped part 51,52 sound absorbing structure 61,62,63,64,65 Sound absorbing structure 71 Lattice baffle plate

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Claims (10)

(57) [Claims] 1. An exhaust heat recovery boiler that guides hot gas generated in a furnace or the like into a duct and exchanges heat with a heat exchanger tube group provided in the duct to recover exhaust heat. The inner wall of the portion where the flow passage cross-sectional area of the duct changes along the flow direction, in the direction from the inner wall of the duct to the inside of the duct.
The ridges that project along the flow direction while projecting
An exhaust heat recovery boiler is provided with a plurality of sound absorbing structures which are arranged in parallel in a circumferential direction of the housing and which suppress reflection of sound waves traveling in the longitudinal direction in the duct. 2. An exhaust heat recovery boiler that guides hot gas generated in a furnace or the like into a duct and exchanges heat with a heat exchanger tube group provided in the duct to recover exhaust heat. On the inner wall of the bent portion, in the direction from the inner wall of the duct to the inside of the duct.
An exhaust heat recovery boiler comprising a large number of protruding ridges arranged in parallel, and a sound absorbing structure for suppressing reflection of sound waves traveling in the longitudinal direction inside the duct. 3. An exhaust heat recovery boiler that guides hot gas generated in a furnace or the like into a duct and exchanges heat with a heat exchanger tube group provided in the duct to recover exhaust heat. The duct is connected to a side wall of a chimney that discharges gas, and a portion of the inner wall of the chimney where the duct is connected is projected in a direction from the inner wall of the chimney toward the inside of the duct.
The protruding ridges are arranged side by side along the circumferential direction of the chimney,
An exhaust heat recovery boiler is provided with a sound absorbing structure that suppresses reflection of sound waves traveling in the longitudinal direction within the duct. 4. An exhaust heat recovery boiler for recovering exhaust heat by guiding hot gas generated in a furnace or the like into a duct and exchanging heat with a heat exchanger tube group provided in the duct. A grid extending in the flow direction at the inner wall portion where the flow passage cross-sectional area of the duct changes along the flow direction, at the inner wall portion where the duct is bent, or at the portion where the heat exchanger tube group is not arranged in the duct. -Shaped baffle plate is provided, the lattice-shaped baffle plate is formed to have an uneven length in the flow direction, and the lattice-shaped baffle plate also has an uneven position in the front end portion or the rear end portion in the flow direction. Exhaust heat recovery boiler characterized in that it is formed in. 5. An exhaust heat recovery boiler that guides hot gas generated in a furnace or the like into a duct and exchanges heat with a heat exchanger tube group provided in the duct to recover exhaust heat in the duct. A baffle plate in the form of a grid extending in the flow direction is provided in the area where the heat exchanger tube group of is arranged. The baffle plate in the form of a grid is formed to have an uneven length in the flow direction. The baffle plate of (1) is also characterized in that the front end portion or the rear end portion in the flow direction is also formed unevenly. 6. The exhaust heat recovery boiler according to claim 4, wherein the lattice-shaped baffle plate extends parallel to the inner wall of the duct. 7. The exhaust heat recovery boiler according to claim 4, wherein the lattice-shaped baffle plate extends non-parallel to the inner wall of the duct. 8. An exhaust heat recovery boiler that guides hot gas generated in a furnace or the like into a duct and exchanges heat with a heat exchanger tube group provided in the duct to recover exhaust heat. A denitration element for denitrifying the gas is arranged in the duct, and a front end portion or a rear end portion in the flow direction of the denitration element is provided with a portion in which vertically extending wedges are arranged in parallel with a laterally extending wedge. An exhaust heat recovery boiler, wherein the installed parts are formed so as to be alternately arranged. 9. An exhaust heat recovery boiler for recovering exhaust heat by guiding hot gas generated in a furnace or the like into the duct and exchanging heat with a heat exchanger tube group provided in the duct. The exhaust heat recovery boiler is characterized in that a denitration element for denitrifying hot gas is disposed at the front end portion or the rear end portion in the flow direction of the denitration element. 10. The exhaust heat recovery boiler according to claim 4, wherein the lattice-shaped baffle plate also has a sound absorbing function.