JP6983515B2 - Boiler and its driving method - Google Patents

Description

The present invention relates to a boiler such as an exhaust heat recovery boiler and a method for operating the boiler.

Ammonia injected to remove NOx in exhaust gas such as exhaust heat recovery boiler (HRSG: Heat Recovery Steam Generator) that recovers heat from exhaust gas such as combustion gas by a denitration device and sulfur oxides in exhaust gas (hereinafter referred to as "SOx"). Ammium hydrogensulfate is produced by a chemical reaction with) and may adhere to the surface of the heat transfer tube in the boiler. In addition, at the time of periodic inspection of this boiler, the boiler may be stopped for a long period of time due to repair / replacement of each equipment, maintenance of the inside of the furnace, etc. The heat transfer tube cools and condensation occurs due to the moisture in the atmosphere, and ammonium hydrogensulfate adhering to the surface of the heat transfer tube may absorb water, causing corrosion and rust on the surface of the heat transfer tube. Furthermore, there is a risk that rust or the like adhering when the can is stopped will peel off when the boiler is restarted, be wound up together with the combustion exhaust gas, and be discharged to the outside as scattered matter from the chimney.

A method of heating the internal atmosphere of a boiler is known in order to suppress corrosion due to dew condensation when the boiler is stopped (see Patent Documents 1 and 2).
Patent Document 1 discloses that when the gas turbine is stopped, the inside of the casing is heated by a warming heater to suppress dew condensation and rusting on the heat transfer tube.
In Patent Document 2, storage steam is supplied from the auxiliary boiler to the precipitation pipe of the low-pressure evaporator when the boiler is stopped, and the temperature of the low-pressure evaporator is maintained above the temperature required to prevent low-temperature corrosion due to sulfate dew condensation. It is stated that

Japanese Unexamined Patent Publication No. 2002-98301 Japanese Unexamined Patent Publication No. 11-287401

However, in the boiler described in Patent Document 1, since the inside of the boiler is heated by a warming heater using auxiliary steam when the gas turbine is stopped, it is necessary to install an auxiliary boiler. Further, since the internal flow is only due to natural convection, there is a problem that the heat transfer tube cannot be efficiently heated to the required temperature.
Since the boiler described in Patent Document 2 supplies storage steam from the auxiliary boiler to the precipitation pipe of the low-pressure evaporator to maintain the internal temperature of the boiler, it is necessary to install the auxiliary boiler. Further, there is a problem that the inside of the boiler cannot be efficiently heated to the required temperature because the internal flow is only due to natural convection.
As described above, it cannot be said that the boilers described in the above patent documents can efficiently suppress corrosion due to dew condensation during long-term boiler suspension.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a boiler capable of efficiently suppressing corrosion of a heat transfer tube due to dew condensation during long-term boiler suspension, and a method for operating the boiler. And.

In order to solve the above problems, the boiler of the present invention and its operation method adopt the following means.
That is, in the boiler according to the present invention, when the high temperature gas flows in the first direction along the axial direction of the main body in the boiler during operation, the heated medium flows inside and the longitudinal direction is the first direction. A plurality of heat transfer tubes arranged so as to be orthogonal to each other, a hot air supply unit that supplies hot air so as to flow outside the heat transfer tube, and a predetermined range higher than the temperature at which dew condensation occurs on the outer surface of the heat transfer tube. It is provided with a control unit that controls the hot air supply unit so that the hot air at the temperature inside is supplied.

The hot air supply unit supplies hot air so that it flows outside the heat transfer tube, and controls the temperature of the hot air so that the temperature is within a predetermined range higher than the temperature at which dew condensation occurs on the outer surface of the heat transfer tube. As a result, it is possible to prevent the temperature of the heat transfer tube from dropping and causing dew condensation, and it is possible to prevent corrosion and rust of the heat transfer tube due to dew condensation during the long-term suspension of the boiler.
As the warm air, air heated to a temperature within a predetermined range in which the temperature of the outer surface of the heat transfer tube can be maintained so as not to be lower than the temperature at which dew condensation occurs is used. By supplying high temperature air, the relative humidity near the surface of the heat transfer tube can be lowered to prevent dew condensation.
Examples of the boiler include an exhaust heat recovery steam generator (HRSG).

Further, in the boiler of the present invention, the hot air supply unit includes a fan and a heater, and the control unit controls the fan and the heater.

Since the control unit controls the rotation speed and start / stop of the fan, and the temperature and start / stop of the heater, the humidity can be appropriately maintained so that dew condensation does not occur on the heat transfer tube. Therefore, it is possible to suppress the power consumption when supplying warm air during the long-term suspension of the boiler.

Further, in the boiler of the present invention, a plurality of support plates for supporting the heat transfer tube are extended in parallel in the first direction in a state where the heat transfer tube is inserted and spreads in a plane direction orthogonal to the longitudinal direction of the heat transfer tube. Preparing for.

Since a plurality of support plates supporting the heat transfer tube extend in the first direction and are provided in parallel, the warm air blown from the upstream side in the first direction around the heat transfer tube has a flow in the first direction. It is maintained and passes undisturbed in the direction orthogonal to the first direction. Therefore, the ventilation efficiency for airflow circulation can be improved.

Further, it is provided with a first duct for flowing hot air into the space including the heat transfer tube when the hot air supply unit operates, and a damper provided in the first duct to close the space.

Since it was decided to provide a first duct for flowing hot air into the space including the heat transfer tube when the hot air supply unit operates, and a damper provided in the first duct to close the space, it is already installed. It is possible to effectively prevent dew condensation on the heat transfer tube by circulating warm air using the duct.

Further, a second duct for discharging hot air after passing through the heat transfer tube from the space including the heat transfer tube when the hot air supply unit operates, and a second duct provided in the second duct to close the space. It is equipped with a damper.

A second duct for discharging hot air after passing through the heat transfer tube from the space including the heat transfer tube when the hot air supply unit operates, and a damper provided in the second duct to close the space. Therefore, it is possible to effectively prevent dew condensation on the heat transfer tube by circulating warm air using the existing duct.

Further, the boiler of the present invention is provided with a denitration device on the upstream side of the heat transfer tube in the first direction, and includes a blow tube for blowing warm air from between the heat transfer tube and the denitration device.

Since it was decided to provide a blowing tube between the heat transfer tube and the denitration device on the upstream side in the first direction to blow warm air, the warm air can be efficiently supplied to the heat transfer tube. Further, if the curing sheet is installed on the downstream side in the first direction of the denitration device, the denitration device can be protected from the debris peeled from the heat transfer tube.

Further, the power generation facility according to the present invention includes a boiler, a steam turbine driven by the steam generated by the boiler, and a generator driven by the steam turbine.

Since the boiler is provided with the above-mentioned boiler, it is possible to provide a power generation facility capable of preventing corrosion and rust of the heat transfer tube even when the can is stopped for a long period of time.

Further, the boiler operating method according to the present invention is a boiler operating method including a heat transfer tube through which a heated medium flows, and is a temperature at which dew condensation occurs on the outer surface of the heat transfer tube during long-term suspension of canning. Warm air having a temperature within a predetermined range higher than that is supplied to the outside of the heat transfer tube.

Warm air is supplied so as to flow outside the heat transfer tube, and the temperature of the warm air is controlled so that the temperature is within a predetermined range higher than the temperature at which dew condensation occurs on the outer surface of the heat transfer tube. As a result, it is possible to prevent the temperature of the heat transfer tube from dropping and causing dew condensation, and it is possible to prevent corrosion and rust of the heat transfer tube due to dew condensation during the long-term suspension of the boiler.

Further, in the method of operating the boiler of the present invention, the curing sheet is installed on the downstream side of the first direction of the denitration device provided on the upstream side of the first direction of the heat transfer tube.

By installing the curing sheet on the downstream side in the first direction of the denitration device, the denitration device can be protected from falling objects that have fallen off from the heat transfer tube.

Corrosion of the heat transfer tube due to dew condensation during long-term boiler suspension can be effectively suppressed.

It is a vertical sectional view of the boiler which concerns on one Embodiment of this invention. It is a perspective view of the blowing pipe which blows warm air used for the boiler of FIG. It is a side view of the support plate which supports the heat transfer tube used for the boiler of FIG. It is a front view of the support plate which supports the heat transfer tube used for the boiler of FIG. It is a flowchart which showed from the stop to the restart of a plant using a boiler. It is a graph which shows the relationship between the time after the boiler is stopped and the temperature in the furnace. It is a vertical sectional view which shows the modification of a boiler.

Hereinafter, an embodiment of the boiler according to the present invention will be described with reference to the drawings.
FIG. 1 shows a first embodiment of the present invention.

As shown in the figure, the exhaust heat recovery boiler (hereinafter referred to as “HRSG”; HRSG: Heat Recovery Steam Generator) 1 of the present embodiment has a main body 20 and an exhaust gas inlet duct 21 connected below the main body 20. And an exhaust gas outlet duct 22 connected above the main body 20. In the above description and the following description, "upper" and "lower" mean "upper side in the vertical direction" and "lower side in the vertical direction", respectively. Here, since the HRSG1 of the present embodiment has a vertically arranged structure, the axial direction of the main body portion coincides with the vertical direction, and the exhaust gas flows from the bottom to the top in the main body portion 20.
Further, on the upstream side of the exhaust gas flow of HRSG1, a gas turbine (not shown) is provided to which the combustion gas burned by the combustor (not shown) is guided. A generator (not shown) is connected to the gas turbine.

The exhaust gas inlet duct 21 forms a flow path for guiding the exhaust gas from the gas turbine, and is connected to the lower end of the main body 20.

The exhaust gas outlet duct 22 forms a flow path through which the exhaust gas that has passed through the main body 20 flows, and a chimney 23 is connected to the upper side on the downstream side. The chimney 23 is provided with a chimney damper 23a for opening and closing the flow path.

The main body 20 is provided with a denitration device 14, a blow pipe 15, and a heat transfer pipe group 11 in this order from the upstream side of the exhaust gas flow.

The denitration device 14 adopts a method of treating nitrogen oxides (NOx) contained in the exhaust gas discharged from the gas turbine and denitration by a reduction denitration reaction using ammonia.

The heat transfer tube group 11 is formed by arranging a plurality of heat transfer tubes in the longitudinal direction orthogonal to the exhaust gas flow, and is divided into predetermined blocks as needed. During the operation of the HRSG1, for example, water or steam supplied to a boiler or a steam turbine is flowed inside each heat transfer tube to exchange heat with the exhaust gas. In addition, another heat transfer tube group may be provided on the upstream side (lower side) of the denitration device 9.

While the operation of the HRSG1 is stopped, the blow pipe 15 blows out the warm air supplied from the hot air supply unit 2. As shown in FIG. 2, the blow pipe 15 has a configuration in which a plurality of branch pipes 17 are connected in parallel to the supply header 16. In each branch pipe 17, a large number of spouts 17a are formed upward at substantially equal intervals.

As shown in FIG. 1, the blow pipe 15 is connected to the hot air blower 3 via, for example, a supply-side bellows pipe 4a which is a flexible pipe. The use of flexible piping facilitates temporary installation and placement. Further, the pipe is not limited to the flexible pipe, and a rigid pipe or a combination of the rigid pipe and the flexible pipe may be freely used.
The hot air blower 3 includes a fan and a heater controlled by a control unit (not shown). As the heater, for example, an electric heater is used.

The supply-side bellows pipe 4a to which hot air is supplied from the hot air blower 3 is connected to, for example, near HRSG1 of a high-temperature duct 5 for mill drying for supplying exhaust gas as a drying gas to a mill for crushing coal as fuel. ing. The high temperature duct 5 for drying the mill is provided with a damper 5a for opening and closing the flow path on the mill side of the connection position with the bellows pipe 4a on the supply side.
The return-side bellows pipe 4b that returns warm air to the hot air blower 3 is connected to the vicinity of HRSG1 of the return duct 7 for mill drying, in which the gas used for drying in the mill is returned. The return duct 7 for drying the mill is provided with a damper 7a for opening and closing the flow path on the mill side of the connection position with the return side bellows pipe 4b. The return duct 7 for mill drying is connected to the main body 20 of the HRSG1 and is connected to the downstream side of the exhaust gas flow from the heat transfer tube group 11. The connection position between the supply side bellows pipe 4a and the return side bellows pipe 4b is not limited to the high temperature duct 5 for mill drying and the return duct 7 for mill drying, and is upstream of the exhaust gas flow with respect to the heat transfer tube group 11. It suffices if it is connected to each of the downstream side.

In the example of the present embodiment, in the vicinity of the position where the return duct 7 for drying the mill is connected to the main body 20, the mill for guiding the low temperature exhaust gas after the temperature is lowered by the heat transfer tube group 11 to the mill. A low temperature duct 6 for drying is connected. The low temperature duct 6 for drying the mill is provided with a damper 6a for opening and closing the flow path. The return-side bellows pipe 4b that returns warm air to the hot air blower 3 may be connected to the vicinity of HRSG1 of the low-temperature duct 6 for mill drying.

By using the bellows pipes 4a and 4b, the hot air blower 3 can be connected between the existing high temperature duct 5 for mill drying and the return duct 7 for mill drying at the time of regular inspection. When the dampers 5a, 6a, 7a, and 23a are closed, a flow path for hot air to circulate can be formed between the inside of the main body 20 and the hot air blower 3.

Above the heat transfer tube group 11, a plurality of support beams 13 for suspending the heat transfer tube group 11 are provided. The support beam 13 is, for example, a structural member having an I-shaped cross section, and extends in the vertical direction on the paper surface. Each support beam 13 is fixed to the main body 20.

As shown in FIGS. 3 and 4, the hanger 18 is suspended downward from the support beam 13. The hanger 18 supports a perforated plate (support plate) 12 through which each heat transfer tube of the heat transfer tube group 11 is inserted, whereby the heat transfer tube group 11 is suspended and fixed from, for example, the support beam 13. It has become like. Each of the perforated plates 12 extends in the vertical direction, extends in the plane direction orthogonal to the longitudinal direction of the heat transfer tube, and is arranged in parallel with a predetermined interval.

HRSG1 having the above configuration operates as follows.
The high-temperature exhaust gas that has finished its work in the gas turbine is guided to the exhaust gas inlet duct 21. The exhaust gas flowing from the exhaust gas inlet duct 21 flows from below the main body 20, passes through the denitration device 14, and then passes through the heat transfer tube group 11 from the lower side to the upper side in the vertical direction. As the high-temperature exhaust gas flows around each heat transfer tube constituting the heat transfer tube group 11, the fluid (water, steam, etc.) flowing inside the heat transfer tube exchanges heat with the exhaust gas and is heated. In this way, the amount of heat possessed by the exhaust gas is efficiently recovered and effectively used.
The exhaust gas that has passed through the heat transfer tube group 11 heads upward, passes through the exhaust gas outlet duct 22, and is discharged to the outside from the chimney 23.

Depending on the properties of the exhaust gas, deposits are formed on the outer periphery of each heat transfer tube constituting the heat transfer tube group 11. The deposits typically include ammonium hydrogensulfate. As for ammonium hydrogensulfate, a denitration device 14 that uses ammonia for the reduction denitration reaction is installed on the upstream side of the exhaust gas flow of the heat transfer tube group 11, and the fuel contains a relatively large amount of sulfur such as blast furnace gas, oils, and coal. It is remarkably generated in the combustion exhaust gas when fuel is used.
Ammonium bisulfate (NH ₄ HSO ₄ ) was not used in the reducing denitration reaction and could not be recovered _{from the ammonia (NH 3} ) sprayed in the exhaust gas as a reducing agent for the denitration catalyst, and SOx in the exhaust gas. It is generated by a chemical reaction with (NH ₃ + H ₂ SO _4). Ammonium bisulfate tends to precipitate at about 100 ° C to 250 ° C, although it depends on the concentration in the exhaust gas.

When such ammonium hydrogensulfate precipitates on the surface of the heat transfer tube, the ammonium hydrogensulfate adhering to the surface of the heat transfer tube absorbs water when the heat transfer tube cools during long-term suspension and condensation occurs due to moisture in the atmosphere. As a result, corrosion and rust may occur on the heat transfer tube and the like. Further, rust or the like adhering when the can is stopped may be peeled off when the boiler is restarted, rolled up together with the combustion exhaust gas, and discharged to the outside as scattered matter from the chimney.
Therefore, in the present embodiment, the following operations are performed when the can is stopped.

FIG. 5 shows the flow at the time of regular inspection.
When the plants such as the gas turbine and HRSG1 are stopped, the HRSG1 is cooled (step S1).
Then, the hot air supply unit 2 is temporarily installed (step S2). Specifically, the warm air blower 3 is connected between the high temperature duct 5 for mill drying and the return duct 7 for mill drying by using bellows pipes 4a and 4b.
Next, the dampers 5a, 6a, 7a, and 23a are closed, and warm air is circulated between the inside of the main body 20 and the hot air blower 3 (step S3). The warm air is flowed from the blow tube 15 toward the heat transfer tube group 11.
When inspecting or performing maintenance at each location in HRSG1, the warm air circulation is temporarily stopped (step S4). After inspection and maintenance, warm air circulation will be resumed until just before the plant is started.
In step S5, the warm air blower 3 and the bellows pipes 4a and 4b are removed.
After the removal of the hot air supply unit 2 is completed in step S5, the dampers 5a, 6a, 7a, 23a are opened to start the plants such as the gas turbine and HRSG1 (step S6).

FIG. 6 shows the temperature inside the furnace from the plant shutdown / cooling (step S1) shown in FIG. 5 to the inspection and maintenance in step S4. In the figure, the horizontal axis represents time and the vertical axis represents the temperature inside the furnace (temperature inside HRSG1).
HRSG1 that was operated at a furnace temperature _{T 3} is Tomakan at time _{t 1.}
After that, in _{the period from time t 1} to t ₂ , the gas turbine is idled (GT spin) by a motor or the like and blown to HRSG 1 to promote cooling to the _{temperature T 2.}
During the period from time t ₂ to t ₃ , natural cooling is performed, for example, the temperature is lowered to _{about room temperature T 0} , which is an environment in which the operator can work inside HRSG 1.
Then, the warm air supply unit 2 is temporarily installed between the time t ₃ and the time t _{4 at the temperature T 0 (step S2).} Thereafter, the fan and the heater control of the fan heater 3 is started at time t ₄ as in step S3 and step S4, HRSG1 the temperature around the heat transfer tube group 11 temperature not lower than the target temperature T ₁ is maintained. The target temperature T ₁ is a temperature at which dew condensation occurs on the outer surface of the heat transfer tube of the heat transfer tube group 11. The hot air supplied from the hot air blower 3 is set to a temperature _{within a predetermined range higher than the target temperature T 1} (for example, within a range _{from a temperature several ° C higher than T 1} to a temperature several ten ° C higher). Here, in the above-mentioned predetermined range, the temperature of the outer surface of the heat transfer tube is maintained so as not to be lower than the temperature at which dew condensation occurs by supplying the hot air supplied from the hot air blower 3 to the hot air in this temperature range. The temperature range is as possible. By supplying warm air at this temperature, the relative humidity of the air near the surface of the heat transfer tube can be lowered to prevent dew condensation.
When it is difficult to grasp the temperature at which dew condensation occurs, as a guideline temperature at which dew condensation does not occur on the outer surface of the heat transfer tube of the heat transfer tube group 11, for example, near the surface of the heat transfer tube even when the relative humidity inside HRSG1 is 100%. A temperature may be set such that the relative humidity is 30% to 50% or less and no dew condensation is observed, and this reference temperature may be regarded as the temperature at which dew condensation occurs on the outer surface of the heat transfer tube. At this time, the fan and heater of the hot air blower 3 are intermittently on / off controlled or continuously output controlled, and are controlled so that the power consumption is as small as possible.
The predetermined range of the hot air temperature supplied from the hot air blower 3 is a temperature at which the lower limit is a temperature at which dew condensation does not occur even if the outer surface temperature of the heat transfer tube of the heat transfer tube group 11 is distributed, and the upper limit is. In anticipation of a decrease in the outside air temperature, the temperature is set so that dew condensation does not occur in the entire region where warm air circulates while reducing the consumption of heater power so as not to become excessive.

When inspecting and performing maintenance by starting blowing warm air as in steps S3 and S4, a curing sheet 19 is installed between the blowing pipe 15 and the denitration device 14 as shown in FIG. 7. As a result, the denitration device 14 can be protected when a fallen object falls off from the heat transfer tube.

According to this embodiment, the following effects are exhibited.
The hot air supply unit 2 supplies warm air so as to flow outside the heat transfer tube of the heat transfer tube group 11, and the temperature is within a predetermined range higher than the temperature at which dew condensation occurs on the outer surface of the heat transfer tube of the heat transfer tube group 11. By controlling the temperature of the hot air in this way, it is possible to prevent the temperature of the heat transfer tube from dropping and causing dew condensation, and the heat transfer tube is corroded and rusted due to dew condensation during the long-term suspension of the boiler 1. Can be prevented.

In addition, the control unit controls the rotation speed and / or start / stop of the fan, and the temperature and / or start / stop of the heater, so that the humidity can be appropriately and effectively maintained so that dew condensation does not occur on the heat transfer tube. , It is possible to suppress the power consumption when supplying warm air during the long-term suspension of the boiler 1.

Further, since the plurality of perforated plates 12 supporting the heat transfer tube extend in the vertical direction, which is the flow direction of the exhaust gas, and spread in the plane direction orthogonal to the longitudinal direction of the heat transfer tube, they are provided in parallel from below the heat transfer tube. The blown warm air is maintained in the vertical direction and rises without being disturbed in the horizontal direction. Therefore, the ventilation efficiency for airflow circulation can be improved.

Further, it is decided to provide a high temperature duct 5 for mill drying that supplies hot air to the heat transfer tube group 11 when the hot air supply unit 2 operates, and a damper 5a provided in the high temperature duct 5 for mill drying. Therefore, it is possible to effectively prevent dew condensation on the heat transfer tube by circulating warm air using the existing high temperature duct 5 for drying the mill.

Further, the mill drying return duct 7 for discharging the warm air after passing through the heat transfer tube group 11 when the hot air supply unit 2 operates, and the damper 7a provided in the mill drying return duct 7 are provided. Therefore, it is possible to effectively prevent dew condensation on the heat transfer tube by circulating warm air using the existing return duct 7 for drying the mill.

Since the blowing tube 15 is provided between the heat transfer tube group 11 and the denitration device 14 to blow warm air, the warm air can be efficiently supplied to the heat transfer tube group 11.

As described above, the temperature inside the HRSG1 can be maintained within a predetermined range higher than the temperature at which dew condensation occurs on the outer surface of the heat transfer tube, so that corrosion and rust of the heat transfer tube can occur even during long-term canning. It is possible to provide power generation equipment that can be prevented.

In the example of the present embodiment, the HRSG1 has a vertically arranged structure, and the exhaust gas is distributed from the lower side to the upper side in the vertical direction in the main body 20, but the present invention is not limited to this. For example, it has a horizontal arrangement structure, and the exhaust gas can be handled in the main body 20 in the same manner even if it is distributed in the horizontal direction.

1 HRSG (Exhaust Heat Recovery Boiler)
2 Hot air supply unit 3 Hot air blower 4a Supply side bellows pipe 4b Return side bellows pipe 5 Mill drying high temperature duct 5a Damper 6 Mill drying low temperature duct 6a Damper 7 Mill drying return duct 7a Damper 11 Heat transfer tube group 12 Perforated plate ( Support plate)
13 Support beam 14 Denitration device 15 Blow-in pipe 16 Supply header 17 Branch pipe 18 Hanger 19 Curing sheet 20 Main body 21 Exhaust gas inlet duct 22 Exhaust gas outlet duct 23 Chimney 23a Chimney damper

Claims (7)

When the exhaust gas flows in the first direction along the axial direction of the main body in the boiler during operation, the heated medium flows inside and a plurality of transmissions arranged so that the longitudinal direction is orthogonal to the first direction. With a heat pipe
A hot air supply unit that supplies hot air so as to flow in the first direction outside the plurality of heat transfer tubes.
A control unit that controls the hot air supply unit so that hot air having a temperature within a predetermined range higher than the temperature at which dew condensation occurs on the outer surface of the heat transfer tube is supplied.
Equipped with
A denitration device is provided on the upstream side of the heat transfer tube in the first direction.
A boiler provided with a blowing tube for blowing warm air supplied from the hot air supply unit from between the heat transfer tube and the denitration device. The hot air supply unit includes a fan and a heater, and has a fan and a heater.
The boiler according to claim 1, wherein the control unit controls the fan and the heater. 1 Or the boiler described in 2. A first duct that allows hot air to flow into the space including the heat transfer tube when the hot air supply unit operates,
A damper provided in the first duct to prevent warm air from flowing out from the space through the first duct.
The boiler according to any one of claims 1 to 3. A second duct that discharges warm air after passing through the heat transfer tube from the space including the heat transfer tube when the hot air supply unit operates, and
A damper provided in the second duct and closed to return the warm air flowing into the second duct to the space.
The boiler according to any one of claims 1 to 4. The boiler according to any one of claims 1 to 5 and the boiler
A steam turbine driven by the steam generated in the boiler,
A generator driven by the steam turbine and
Power generation equipment equipped with. When the exhaust gas flows in the first direction along the axial direction of the main body in the boiler during operation, the heat transfer tube through which the heated medium flows inside and the heat transfer tube provided on the upstream side in the first direction. It is a method of operating a boiler equipped with a denitration device.
During long-term canning, warm air with a temperature within a predetermined range higher than the temperature at which dew condensation occurs on the outer surface of the heat transfer tube is blown from between the heat transfer tube and the denitration device to the outside of the heat transfer tube by a blow tube. supply to Rubo Ira method of operation.

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