JP2018132281A - Waste heat recovery boiler and scattering matter recovery method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste heat recovery boiler capable of recovery scattering matter so as to minimize influence on pressure loss of exhaust gas flow.SOLUTION: A waste heat recovery boiler includes an exhaust gas inlet duct 5 into which exhaust gas flows, a body part 3 provided on a downstream side of exhaust gas flow with respect to the exhaust gas inlet gas duct 5, and an exhaust gas outlet duct 7 provided on the downstream side of the exhaust gas flow with respect to the body part 3. The body part 3 has a heat transfer pipe group 10 where a plurality of heat transfer pipes are arrayed so that their longitudinal directions are orthogonal to the exhaust gas flow. The exhaust gas outlet duct 7 has an outlet opening 7a having a flow passage cross sectional area smaller than the body part 3, and connected to the outside of a system. The exhaust gas outlet duct 7 has, between the heat transfer pipe group 10 and the outlet opening 7a, filter members 16a, 16b for collecting scattering matter in exhaust gas. The filter members 16a, 16b can be developed in a direction orthogonal to the exhaust gas flow.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exhaust heat recovery boiler that recovers scattered matter that is detached from a heat transfer tube and scatters, and a method for recovering the scattered matter.

  A heat recovery steam generator (HRSG) that recovers heat from exhaust gas such as combustion gas is known (Patent Document 1). The exhaust heat recovery boiler includes a heat transfer tube group composed of a large number of heat transfer tubes, and the longitudinal axis direction of the heat transfer tubes of the heat transfer tube group is orthogonal to the direction of the exhaust gas flow flowing in the exhaust heat recovery boiler. Has been placed. The outlet of the exhaust heat recovery boiler is connected to the outside of the system, such as a chimney, and exhausts exhaust gas whose temperature has been reduced due to heat recovery.

  When exhaust gas passes through the exhaust heat recovery boiler, ammonium hydrogen sulfate is generated by a chemical reaction between ammonia injected to remove NOx by the denitration device and sulfur oxides in the exhaust gas (hereinafter referred to as “SOx”). Is done. This ammonium hydrogen sulfate adheres to and accumulates on the heat transfer tube group of the exhaust heat recovery boiler, and rust is generated on the surface of the heat transfer tube. Ammonium hydrogen sulfate adhering to and accumulating on heat transfer tubes, rust, heat transfer tube paint strips peeled off due to corrosion, or dust contained in the exhaust gas may be scattered and discharged from the chimney together with the exhaust gas was there.

In particular, when the exhaust heat recovery boiler is started, separation from the heat transfer tube group is facilitated due to a temperature difference between the equipment and the exhaust gas, and there is a possibility that a lot of scattered matter is generated.
In order to prevent this, Patent Document 1 discloses that a damper is installed inside the chimney and a metal net is installed on the upper part of the damper so that the scattered matter scattered inside the chimney is collected by the metal net and appropriately cleaned. ing.

Japanese Patent No. 4868924

  The outlet opening connected to the exhaust heat recovery boiler outside the system is designed to be relatively narrow. Therefore, in the vicinity of the outlet opening, there is a region where the flow velocity is locally high, and if there is a scattered matter in the exhaust heat recovery boiler, it may be caught and discharged to the chimney. In addition, when filters such as a wire mesh are installed inside the chimney as in the above-mentioned Patent Document 1, it is necessary to periodically clean or replace these filters. There is no choice but to do. Furthermore, since the flow rate of the exhaust gas flowing inside the chimney is faster than the flow rate in the exhaust heat recovery boiler, if the wire mesh installed inside the chimney is blocked, the pressure loss increases and the efficiency of the power generation equipment connected upstream is reduced. There is a risk of being connected. In particular, when a gas turbine is connected on the upstream side, the gas turbine may trip when the pressure loss of the exhaust gas passing through the exhaust heat recovery boiler fluctuates and the pressure rises.

  The present invention has been made in view of such circumstances, and it is possible to recover the scattered matter by reducing the influence on the pressure loss of the exhaust gas flow passing through the exhaust heat recovery boiler as much as possible. An object of the present invention is to provide a heat recovery boiler and a method for recovering the scattered matter.

In order to solve the above problems, the exhaust heat recovery boiler and the scattered matter recovery method of the present invention employ the following means.
That is, the exhaust heat recovery boiler according to the present invention includes an exhaust gas inlet portion into which exhaust gas flows, a main body portion provided downstream of the exhaust gas flow with respect to the exhaust gas inlet portion, and an exhaust gas flow with respect to the main body portion. An exhaust gas outlet provided on the downstream side, and the main body has a heat transfer tube group in which longitudinal directions of a plurality of heat transfer tubes are arranged orthogonal to the exhaust gas flow, and the exhaust gas outlet Has an outlet opening connected to the outside of the system having a smaller channel cross-sectional area than the main body part, and the exhaust gas outlet part is located between the heat transfer tube group and the outlet opening. It has a collection part which collects a scattered matter, and this collection part can be developed in the direction orthogonal to the exhaust gas flow.

  By installing a collection unit at the exhaust gas outlet of the exhaust heat recovery boiler, the scattered matter wound up in the exhaust gas at the time of start-up can be collected by the deployed collection unit and discharged outside the system. It is suppressed. Moreover, when there are few scattered matters at the time of rated operation etc., a collection part is suitably moved in the direction orthogonal to an exhaust gas flow, and generation | occurrence | production of the pressure loss with respect to an exhaust gas flow can be made low.

  Furthermore, in the exhaust heat recovery boiler according to the present invention, the collection unit can be deployed from one end side to the other end side in the width direction orthogonal to the exhaust gas flow at the exhaust gas outlet portion.

  By making the collection part expandable from one end side to the other end side of the exhaust gas outlet part, the collection part can be developed at an arbitrary position. Thereby, a collection part can be arrange | positioned in a suitable position according to the amount of scattering of a scattered matter.

  Furthermore, in the exhaust heat recovery boiler according to the present invention, it is possible to develop the plurality of collection parts so as to be in a superimposed state overlapping in the exhaust gas flow direction.

  Since it can expand | deploy so that a some collection part may be in the superimposition state which overlaps with an exhaust gas flow direction, collection efficiency can be improved more by deploying overlapping. On the other hand, when the amount of scattered matter is small, the occurrence of pressure loss can be reduced by avoiding overlapping.

  Furthermore, in the exhaust heat recovery boiler according to the present invention, the overlapping state is performed at a position where the outlet opening is blocked.

  Since the overlapping state is performed at a position where the exit opening is blocked, the scattered matter scattered toward the exit opening can be collected more effectively.

  Furthermore, in the exhaust heat recovery boiler according to the present invention, the superposition state is performed by superimposing the tip side of each of the collection parts.

  A superposition state is formed by superimposing the front end side of each collection part. Therefore, the amount of superimposition can be adjusted by advancing and retracting the tip of each collection unit in a direction orthogonal to the exhaust gas flow.

  Furthermore, in the exhaust heat recovery boiler according to the present invention, the collection part is formed of a mesh member.

  Since the collection part is formed of a net-like member, the scattered matter can be collected with a small pressure loss.

  Furthermore, in the exhaust heat recovery boiler according to the present invention, the collection unit is formed so that the center of each opening does not overlap when the mesh member is superimposed.

  Since the center of the opening of the mesh member is overlapped so as not to overlap, it becomes narrow to pass through the overlapped opening, and the passage of scattered objects can be further reduced.

  Furthermore, the exhaust heat recovery boiler of the present invention includes a dust meter installed outside the system, and a control device that deploys the collecting member based on the dust concentration measured by the dust meter. .

  When the dust collection concentration measured by the dust collector is higher than the predetermined value, the collection efficiency can be increased by developing the collection unit. Further, when the dust collection concentration is lower than the predetermined value, the amount of development of the collection unit can be reduced to reduce the occurrence of pressure loss.

  The scattered matter recovery method of the exhaust heat recovery boiler of the present invention is the scattered matter recovery method of the exhaust heat recovery boiler that recovers the scattered matter caused by the exhaust gas flow in the exhaust heat recovery boiler having a heat transfer tube group therein. A step of expanding a collection unit installed in the vicinity of the exhaust gas flow outlet of the exhaust heat recovery boiler in a direction perpendicular to the exhaust gas flow, and a step of collecting the scattered matter by the developed collection unit. The step of preparing and deploying is performed in association with an amount of the scattered matter discharged from the exhaust heat recovery boiler to the outside of the system.

  By expanding the collection part in a direction orthogonal to the exhaust gas flow, the influence on the pressure loss of the exhaust gas flow can be reduced as much as possible to collect the scattered matter.

It is the longitudinal section showing the schematic structure of the exhaust heat recovery boiler concerning one embodiment of the present invention. It is the perspective view which showed the collection apparatus. It is the side view which showed the collection apparatus and showed the filter single state in which the filter member has not overlapped. It is the side view which showed the collection apparatus and showed the filter partial double state in which the filter member has overlapped partially. It is the side view which showed the collection apparatus and showed the filter full-duplex state in which the whole filter member has overlapped. It is the bottom view which looked at the filter member from the lower part. It is a side view of a collection device which showed modification 1. It is a perspective view of the collection device of FIG. It is a side view of the collection device which showed modification 2. It is the bottom view which showed the modification 3 and looked at the filter member from the downward direction. It is the longitudinal cross-sectional view which showed the waste heat recovery boiler of the comparative example.

Several embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a heat recovery steam generator (HRSG) 1. On the upstream side of the exhaust gas flow of the exhaust heat recovery boiler 1, there is provided a gas turbine (not shown) to which combustion gas combusted by a combustor (not shown) is guided. A generator (not shown) is connected to the gas turbine.

  The exhaust heat recovery boiler 1 has a vertically-arranged structure in the example of the present embodiment, and the exhaust gas flows from the lower side in the vertical direction to the upper side in the main body 3. In the following description, “upper” and “lower” indicate the upper side and the lower side in the vertical direction. A main body 3, an exhaust gas inlet duct (exhaust gas inlet part) 5 connected below the main body part 3, and an exhaust gas outlet duct (exhaust gas outlet part) 7 connected above the main body part 3 are provided.

The main body 3 is provided with a denitration device 9 and a heat transfer tube group 10 in order from the upstream side of the exhaust gas flow.
The denitration device 9 employs a system that treats nitrogen oxides (NOx) contained in exhaust gas discharged from a gas turbine or the like and denitrates using ammonia in a reductive denitration reaction.
The heat transfer tube group 10 is formed such that the longitudinal axis directions of the plurality of heat transfer tubes are arranged orthogonal to the exhaust gas flow, and is divided into predetermined blocks as necessary. Inside each heat transfer tube, for example, water or steam supplied to a boiler or a steam turbine flows to exchange heat with exhaust gas. Note that another heat transfer tube group may be provided on the upstream side (lower side) of the denitration device 9.
A plurality of support beams 11 for suspending the heat transfer tube group 10 are provided above the heat transfer tube group 10. The support beam 11 is a structural member having an I-shaped cross section, for example, and extends in the vertical direction on the paper surface. Each support beam 11 is fixed to the main body 3, and a suspension tool (not shown) is suspended downward from each support beam 11. The hanger supports a perforated plate (not shown) through which each heat transfer tube of the heat transfer tube group 10 is inserted, whereby the heat transfer tube group 10 is suspended from the support beam 11 and fixed. . The perforated plates extend in a plane direction perpendicular to the heat transfer tubes, and are arranged in parallel at a predetermined interval.

  The exhaust gas inlet duct 5 forms a flow path for introducing exhaust gas from a gas turbine or the like, and is connected to the lower end of the main body 3.

  The exhaust gas outlet duct 7 forms a flow path through which the exhaust gas that has passed through the main body portion 3 flows, and a chimney 12 is connected to the upper part on the downstream side by an outlet opening 7a. The cross-sectional area of the chimney 12 is smaller than the cross-sectional area of the main body 3. Therefore, the exhaust gas outlet duct 7 has a shape in which the flow passage cross-sectional area is gradually reduced from the upstream side to the downstream side (from the lower side to the upper side).

In the exhaust heat recovery boiler 1, ammonium hydrogen sulfate generated by a chemical reaction between ammonia injected by the denitration device 9 and SOx in the exhaust gas to remove NOx in the exhaust gas adheres to the heat transfer tube group 10 and the like. Some are deposited, peeled off from the heat transfer tube group 10 due to temperature changes at the time of start-up, etc. along with the rust and peeling coating film pieces of the heat transfer tube group 10. A part of the fallen part falls by gravity and accumulates in the exhaust heat recovery boiler 1, and may be scattered in the other part and scattered with the exhaust gas.
The exhaust gas outlet duct 7 is provided with a collection device 14 that collects scattered matter scattered together with the exhaust gas. The collection device 14 is fixed to the upper part of each support beam 11. The collection device 14 includes filter members (collection units) 16a and 16b that develop in a direction orthogonal to the exhaust gas flow.

Each of the filter members 16a and 16b is a net-like member having a predetermined aperture ratio, and two filter members 16a and 16b are provided so as to overlap each other with an interval that allows mutual movement. The aperture ratios of the upper and lower filter members 16a and 16b are preferably equal, but may be different.
As shown in FIG. 2, each filter member 16a, 16b is provided with a planar member so as to be rotatable with respect to each other via hinge portions 16a1, 16b1, and can be folded by these hinge portions 16a1, 16b1. Yes.

  As shown in FIG. 3, in the present embodiment, the collection device 14 includes an upper rail 17a and a lower rail 17b extending in the width direction orthogonal to the exhaust gas flow direction. A belt gear 18 is rotatably attached to both ends of the rails 17a and 17b, and an endless belt 19 is wound around both belt gears 18. An electric motor (not shown) is attached to one of the belt gears 18 so that the rotational drive is controlled by a command from a control unit (not shown).

  The upper rail 17a is provided with a plurality of wheels 20a so that it can run, and the lower rail 17b is provided with a plurality of wheels 20b so that it can run. An upper filter member 16a is connected to the axle of each wheel 20a of the upper rail 17a, and a lower filter member 16b is connected to the axle of each wheel 20b of the lower rail 17b.

  The distal end side (the right side in FIG. 3) of the upper filter member 16a is fixed to the belt 19 by the connecting member 22a. The base end side (left side in FIG. 3) of the upper filter member 16a is fixed to the upper rail 17a. Therefore, with the movement of the belt 19, the base end side of the upper filter member 16a remains at a fixed position, and the tip end side is moved to the center side in the width direction (right side in FIG. 3) so that the upper filter member 16a It is developed in an orthogonal direction (horizontal direction). That is, the upper filter member 16a is developed from the left wall side of the exhaust gas outlet duct 7 toward the center of the exhaust gas flow path.

  The tip side (the left side in FIG. 3) of the lower filter member 16b is fixed to the belt 19 by the connecting member 22b. The base end side (the right side in FIG. 3) of the lower filter member 16b is fixed to the lower rail 17b. Accordingly, with the movement of the belt 19, the base end side of the lower filter member 16b remains at a fixed position, and the distal end side is moved to the center side in the width direction (left side in FIG. 3) so that the lower filter member 16b is orthogonal to the exhaust gas flow. It is developed in the direction (horizontal direction). That is, the lower filter member 16b is developed from the right wall portion side of the exhaust gas outlet duct 7 toward the center of the exhaust gas passage.

  Note that the connection members 22a and 22b may be disconnected, and the connection and release may be selected depending on the positions of the top ends of the upper and lower filter members 16a and 16b. Accordingly, the upper and lower filter members 16a and 16b can be fixedly installed at arbitrary positions regardless of the movement of the belt 19. The connection members 22a and 22b can be disconnected by a command from the control unit or manually.

By moving the upper and lower filter members 16a and 16b of the collection device 14 forward and backward as described above, the upper and lower filter members 16a in the single filter state as shown in FIG. 3 and the central portion as shown in FIG. , 16b partially overlap each other in the overlapping state of the filter, and the filter full duplex state in which the upper and lower filter members 16a, 16b as shown in FIG. Can be combined as appropriate. FIG. 6 shows a case where the filter partial double state is used so as to form a double filter with respect to the exhaust gas flow directly directed to the chimney 12.
For example, the filter single state of FIG. 3 is used when the gas turbine connected to the exhaust heat recovery boiler 1 is in a rated state and the amount of scattered matter is relatively small, and the filter full duplex state of FIG. 4 is used in a state where there is a relatively large amount of scattered matter from the time of starting up to the rating, and the filter partial double state in FIG.
When the upper and lower filter members 16a and 16b overlap each other, the openings are positioned so that the opening centers of the mesh members do not overlap each other. Thereby, in order to pass through the overlapping opening part, an opening area becomes narrow and it can further reduce that a scattered material passes.

The exhaust heat recovery boiler 1 having the above-described configuration operates as follows.
The high-temperature exhaust gas that has finished work in the gas turbine is guided to the exhaust gas inlet duct 5 as indicated by an arrow A1 in FIG. The exhaust gas flowing in from the exhaust gas inlet duct 5 flows from below the main body 3 and passes through the heat transfer tube group 10 from below in the vertical direction after passing through the denitration device 9. As the high-temperature exhaust gas flows around the heat transfer tubes constituting the heat transfer tube group 10, the fluid (water, steam, etc.) flowing inside the heat transfer tubes is heated by exchanging heat with the exhaust gas. Thus, the amount of heat held by the exhaust gas is efficiently recovered and effectively used.
The exhaust gas that has passed through the heat transfer tube group 10 is directed upward, passes through the exhaust gas outlet duct 7, and is discharged from the chimney 12 to the outside of the system.

Due to the properties of the exhaust gas, deposits are generated on the outer periphery of each heat transfer tube constituting the heat transfer tube group 10. Typically, the deposit includes ammonium hydrogen sulfate (NH ₄ HSO ₄ ). As for ammonium hydrogen sulfate, a denitration device 9 using ammonia is installed on the upstream side of the exhaust gas flow of the heat transfer tube group 10, and the fuel is a fuel containing a relatively large amount of sulfur such as blast furnace gas, oils, and coal. Prominently produced in the case of combustion exhaust gas.
Ammonium hydrogen sulfate is a chemical reaction (NH) of ammonia (NH ₃ ) sprayed into exhaust gas as a reducing agent for a denitration catalyst that cannot be recovered without being used in the reductive denitration reaction and SOx in the exhaust gas. ₃ + H ₂ SO ₄ ). Although ammonium hydrogen sulfate depends on the concentration in the exhaust gas, precipitation is likely to occur at about 100 ° C. to 250 ° C.

  Such ammonium bisulfate adhering to the heat transfer tube group 10 or the like, and rust and coating film pieces mixed with the ammonium sulfate are detached due to a difference in thermal expansion caused by temperature change such as when the exhaust heat recovery boiler 1 is started. Some parts fall by gravity, and some of the other parts become scattered matter and are rolled up with exhaust gas. A collection device 14 is used to collect the scattered matter. That is, the exhaust gas that has passed through the heat transfer tube group 10 goes to the filter members 16a and 16b of the collection device 14 together with the scattered matter, while the exhaust gas passes through the filter members 16a and 16b, while the filter members 16a and 16b are connected to each other. Scattered objects larger than the opening of the filter cannot be passed through the filter members 16a and 16b and are collected and collected by the filter members 16a and 16b.

According to this embodiment, there exist the following effects.
By installing the collection device 14 in the exhaust gas outlet duct 7 of the exhaust heat recovery boiler 1, the scattered matter wound up in the exhaust gas at the time of startup or the like was developed in a direction (horizontal direction) orthogonal to the exhaust gas flow. Collection by the filter members 16a and 16b and discharge to the outside of the system are suppressed. In addition, when there are few scattered matters during rated operation or the like, the filter members 16a and 16b are appropriately moved in a direction orthogonal to the exhaust gas flow (for example, the filter single state in FIG. 3), and pressure loss generated with respect to the exhaust gas flow Can be lowered.
FIG. 11 shows a configuration in which the collection device 14 is not installed as a comparative example. As shown in the figure, if the collection device 14 is not provided, the scattered matter 30 is wound up by the exhaust gas, directly flows into the chimney 12 and is discharged out of the system.

By allowing the filter members 16a and 16b to be deployed in a direction (horizontal direction) perpendicular to the exhaust gas flow from one end side to the other end side of the exhaust gas outlet duct 7, the filter members 16a and 16b are deployed at arbitrary positions. (See FIGS. 3 to 5). Thereby, the collection apparatus 14 can be arrange | positioned in an appropriate position according to the amount of scattering of a scattered matter.
The deploying step may be performed in association with the amount of scattered matter discharged from the exhaust heat recovery boiler 1 to the outside of the system, that is, based on the dust concentration measured by the dust meter by installing the dust meter in the chimney 12. The control device may expand the filter members 16a and 16b. Thereby, when the dust concentration measured by the dust collector is higher than a predetermined value, the filter members 16a and 16b are expanded in the direction (horizontal direction) orthogonal to the exhaust gas flow to increase the collection efficiency. be able to. Further, when the dust collection concentration is lower than a predetermined value, the pressure loss generated by reducing the amount of expansion of the filter members 16a and 16b can be reduced.

  Since the upper and lower filter members 16a and 16b can be deployed in a superimposed state so as to overlap in the exhaust gas flow direction, the collection efficiency can be further improved by overlapping and deploying. On the other hand, when there are few scattered objects, as shown in FIG. 3, the pressure loss which generate | occur | produces in one layer so that it may not overlap can be made low.

  As shown in FIG. 6, since the upper and lower filter members 16a and 16b are overlapped with each other at a position where the outlet opening 7a is blocked, it is possible to more effectively collect the scattered matter scattered toward the outlet opening 7a. it can.

  A superposition state is formed by superimposing the tip ends of the filter members 16a and 16b. Therefore, the amount of superimposition can be adjusted by advancing and retracting the tip of each filter member 16a, 16b.

  Since each filter member 16a, 16b is formed of a mesh member, scattered objects can be collected with a small pressure loss.

  Since the opening centers of the mesh members of the filter members 16a and 16b are overlapped so as not to overlap, the opening area is narrowed to pass through the overlapped opening portions, and scattered objects can be further reduced.

[Modification 1]
7 and 8 show a modification of the present embodiment. In FIG. 3, the upper and lower filter members 16a and 16b are both folded upward, but as shown in FIGS. 7 and 8, the upper filter member 16a is folded upward while the lower filter members 16a and 16b are folded downward. The filter member 16b is folded downward. In FIG. 3, when folded, there may be a positional relationship in which the filter members 16a and 16b interfere with each other due to the folded and convex portions. 7 and 8, the upper and lower filter members 16a and 16b interfere with each other by increasing the degree of freedom in the positional relationship between the upper and lower filter members 16a and 16b when folded. There is no.

[Modification 2]
As shown in FIG. 9, the filter members 16a and 16b may be wound up using the winding devices 24a and 24b without folding the filter members 16a and 16b. In this case, a flexible material is used for the upper and lower filter members 16a and 16b. The winding devices 24a and 24b include springs and springs that bias in the winding direction, and the belt 19 is driven to overcome the biasing force in the winding direction when the upper and lower filter members 16a and 16b are deployed. The Further, when the upper and lower filter members 16a and 16b are wound up, the filter members 16a and 16b are wound by an urging force, and the regions where the filter members 16a and 16b are deployed are always maintained in a state of being stretched with a predetermined force. In order to prevent the 16b from being greatly bent, it is not necessary to increase the rigidity more than necessary.

[Modification 3]
As shown in FIG. 10, a third filter member 16c and further a fourth filter member 16d may be provided so as to further overlap the two filter members 16a and 16b. The third filter member 16c and the fourth filter member 16d advance and retreat in a direction orthogonal to the filter members 16a and 16b. Accordingly, the filter members can be superimposed not only in a double manner but also in a triple or quadruple manner, and a wide range can be dealt with according to the amount of scattered matter.

1 Exhaust heat recovery boiler 3 Main body 5 Exhaust gas inlet duct (exhaust gas inlet)
7 Exhaust gas outlet duct (exhaust gas outlet)
9 Denitration device 10 Heat transfer tube group 11 Support beam 12 Chimney 14 Collection device 16a Upper filter member (collection part)
16a1 Hinge part 16b Lower filter member (collecting part)
16b1 Hinge portion 17a Upper rail 17b Lower rail 18 Belt gear 19 Belt 20a, 20b Wheel 22a, 22b Connecting member 24a, 24b Winding device 30 Scattered matter

Claims (9)

An exhaust gas inlet into which exhaust gas flows,
A main body provided downstream of the exhaust gas flow with respect to the exhaust gas inlet,
An exhaust gas outlet provided on the downstream side of the exhaust gas flow with respect to the main body,
With
The main body has a heat transfer tube group in which longitudinal directions of a plurality of heat transfer tubes are arranged orthogonal to the exhaust gas flow,
The exhaust gas outlet portion has an outlet opening connected to the outside of the system having a smaller channel cross-sectional area than the main body portion,
The exhaust gas outlet part has a collection part for collecting scattered matter in the exhaust gas between the heat transfer tube group and the outlet opening,
The exhaust heat recovery boiler, wherein the collection unit can be deployed in a direction orthogonal to the exhaust gas flow.   2. The exhaust heat recovery boiler according to claim 1, wherein the collection unit can be deployed from one end side to the other end side in a direction orthogonal to the exhaust gas flow at the exhaust gas outlet portion.   3. The exhaust heat recovery boiler according to claim 1, wherein a plurality of the collecting portions can be deployed so as to be overlapped with each other in the exhaust gas flow direction.   The exhaust heat recovery boiler according to claim 3, wherein the superposition state is performed at a position where the outlet opening is blocked.   5. The exhaust heat recovery boiler according to claim 3, wherein the superposition state is performed by superimposing leading ends of the collection parts.   The exhaust heat recovery boiler according to any one of claims 1 to 5, wherein the collection part is formed of a net-like member.   The exhaust heat recovery boiler according to claim 6, wherein the collection unit is formed so that the center of each opening does not overlap when the mesh member is superimposed. A dust meter installed outside the system;
Based on the dust concentration measured by the dust meter, a control device that deploys the collection unit,
The exhaust heat recovery boiler according to any one of claims 1 to 7, further comprising: In the waste heat recovery boiler that has the heat transfer tube group inside, in the scattered matter recovery method of the exhaust heat recovery boiler that recovers the scattered matter accompanying the exhaust gas flow,
A step of deploying a collection unit installed in the vicinity of the exhaust gas flow outlet of the exhaust heat recovery boiler in a direction orthogonal to the exhaust gas flow;
A step of collecting the scattered matter by the deployed collecting unit;
With
The expanding step is performed in association with an amount of the scattered matter discharged from the exhaust heat recovery boiler to the outside of the system.

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