JP2019155256A - Drying system, operation method thereof, and boiler system - Google Patents

Abstract

To provide a drying system capable of easily discharging warm air when starting drying and residual gas after stopping the drying.SOLUTION: A drying system comprises: a combustion gas supply passage 62 connected to an exhaust gas duct 61 for making combustion gas discharged from a boiler 10 flow therethrough; a first flow control device 31 provided in the middle of the combustion gas supply passage 62; a drying device 20 connected to the combustion gas supply passage 31 and having an inside space 20A constituted so as to bring the combustion gas supplied from the combustion gas supply passage 31 into contact with treatment object water; an exhaust gas discharge passage 63 for discharging moisture-containing gas discharged from the drying device 20, the moisture-containing gas containing the treatment object water, vaporized by contact with the treatment object water; a second flow control device 41 provided in the middle of the discharge gas discharge passage 63; and a heated air supply passage 64 which is connected to an object flow passage formed between the first flow control device 31 and the second flow control device 41 and is used for supplying heated air.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a drying system, an operation method thereof, and a boiler system.

  A boiler is installed in a thermal power plant and the like, and combustion gas generated by combustion of fuel is discharged from the boiler. Since the combustion gas contains sulfur oxide, a desulfurization apparatus is used to remove the sulfur oxide in the combustion gas. Examples of the desulfurization apparatus include a wet desulfurization apparatus using lime water. In a wet type desulfurization apparatus using lime water, lime water as an absorbing liquid and combustion gas containing sulfur oxide are brought into contact. And by this contact, sulfur oxide is absorbed in lime water, and sulfur content derived from sulfur oxide is recovered and removed as gypsum.

  The drainage after collecting and removing gypsum (wash water discharged from the desulfurizer and after contact with the combustion gas) may contain chloride ions, heavy metal ions, and the like. Therefore, in order to discharge the wastewater to the outside, it is preferable to reduce the concentration of each component in the wastewater to a drainage standard value or less. However, since removal of each component is costly, attempts have been made to circulate it in the system without discharging the wastewater to the outside.

  Patent Document 1 describes that waste gas is vaporized by supplying a combustion gas to a drying apparatus and bringing the supplied combustion gas and waste water into contact with each other (refer to FIG. 5-2 in particular). Further, the combustion gas supplied to the drying device is generated by the combustion of fuel in the boiler (see particularly FIG. 1).

JP 2012-196638 A

  The combustion gas contains sulfur oxides generated by the combustion of fuel. Therefore, for example, if the combustion gas is supplied in a state where the temperature of the drying device is low, such as immediately after the start of drying in the drying device, sulfur oxides contained in the combustion gas may be condensed. And the wall surface of a drying apparatus may corrode by dew condensation of sulfur oxide. Similarly, sulfur oxides may be condensed on the wall surface of an exhaust duct or the like connected to the drying device.

  In addition, for example, when the solid matter accumulated inside the drying apparatus is taken out, drying in the drying apparatus may be stopped. In this case, when the supply of the combustion gas to the drying device is stopped and the drying in the drying device is stopped, the temperature of the drying device decreases. As a result, sulfur oxides contained in the combustion gas remaining in the internal space of the drying device may condense due to heat dissipation and condense. And as mentioned above, wall surfaces, such as a drying apparatus and an exhaust duct, may corrode by dew condensation of sulfur oxide.

  An object of at least one embodiment of the present invention is to provide a drying system, an operation method thereof, and a boiler system capable of easily discharging warm air at the start of drying and residual gas after stopping drying.

  (1) A drying system according to at least one embodiment of the present invention is a drying system for drying water to be treated by heat of combustion gas generated in a combustion gas generation source, and is discharged from the combustion gas generation source. A combustion gas supply path connected to an exhaust gas duct through which the combustion gas flows, a first flow rate adjusting device provided in the middle of the combustion gas supply path, and a combustion gas supply connected to the combustion gas supply path A drying device having an internal space configured to bring the combustion gas supplied from a passage into contact with the water to be treated; and an exhaust gas discharged from the drying device, wherein the combustion gas is brought into contact with the water to be treated. An exhaust gas discharge path for discharging exhaust gas containing the vaporized water to be treated, a second flow rate adjusting device provided in the middle of the exhaust gas discharge path, the first flow rate adjusting device and the front Is connected to the target flow path formed between the second flow control device, characterized in that it comprises a heated air supply passage for supplying the heated air.

  According to the configuration of (1), warming of the drying device can be easily performed before the drying is started, and purging of the drying device can be easily performed after the drying is stopped. Thereby, the dew condensation to the drying apparatus of sulfur oxide can be suppressed, and corrosion of a drying apparatus can be suppressed.

  (2) In some embodiments, in the configuration of (1), the temperature of the heated air is equal to or higher than the acid dew point temperature of the combustion gas.

  According to the configuration of (2) above, the temperature of the drying apparatus can be sufficiently increased before the start of drying. In addition, after the drying is stopped, the heated air having the acid dew point temperature or higher comes into contact with the combustion gas, so that the combustion gas can be prevented from being excessively cooled. By these, dew condensation of sulfur oxide can be more sufficiently suppressed.

  (3) In some embodiments, in the configuration of (1) or (2), at least one of the first flow rate adjustment device and the second flow rate adjustment device is a seal that seals a damper by air pressure. A damper is included, and a part of the sealing air supplied to the seal damper is configured to be supplied to the target flow path as the heated air.

  According to the configuration of (3) above, it is possible to warm and purge the drying device using the existing sealing air.

  (4) In some embodiments, in any one of the configurations (1) to (3), the exhaust gas discharge path is more exhausted than a connection point between the combustion gas supply path and the exhaust gas duct. It is connected to the exhaust gas duct on the downstream side of the duct, and the heated air supply path is connected to the combustion gas supply path downstream of the first flow rate adjusting device.

  According to the configuration of (4) above, the exhaust gas discharge path can be connected to the downstream exhaust gas duct that is at a lower pressure than the connection location between the combustion gas supply path and the exhaust gas duct. Thereby, since the exhaust gas discharge path is arranged on the low pressure side, the supplied heated air can easily flow through the exhaust gas duct due to the pressure difference. Further, the heated air supplied to the combustion gas supply passage can be easily flowed to the exhaust gas duct through the low-pressure side drying device and the exhaust gas discharge passage. For this reason, warming up and purging can be performed while suppressing energy applied from the outside in order to flow heated air.

  (5) In some embodiments, in any one of the configurations (1) to (4), for controlling an opening degree of at least one of the first flow rate adjusting device or the second flow rate adjusting device. The apparatus further includes a control device, wherein the control device is configured to control the opening degree in accordance with a supply amount of the heated air.

  According to the structure of said (5), it can suppress that the internal pressure of a drying apparatus rises excessively with supply of heated air. For this reason, the pressure | voltage resistant performance requested | required of a drying apparatus can be made small, and the installation cost of a drying apparatus can be reduced.

  (6) The operation method of the drying system according to at least one embodiment of the present invention is an operation method of the drying system for drying the water to be treated by the heat of the combustion gas generated in the combustion gas generation source, The drying system includes a combustion gas supply path connected to an exhaust gas duct through which the combustion gas discharged from the combustion gas generation source flows, a first flow rate adjusting device provided in the middle of the combustion gas supply path, and the combustion A drying apparatus connected to a gas supply path and having an internal space configured to bring the combustion gas supplied from the combustion gas supply path into contact with the water to be treated; and an exhaust gas discharged from the drying apparatus. An exhaust gas discharge path for discharging exhaust gas containing the treated water vaporized by contact with the treated water, and a second provided in the middle of the exhaust gas discharge path A drying apparatus comprising: a volume adjusting device; and a heating air supply path connected to a target flow channel formed between the first flow rate adjusting device and the second flow rate adjusting device, and for supplying heated air. The system operation method includes a purge step of discharging the combustion gas in the drying device by supplying the heated air from the heated air supply path to the target flow path, or the target flow from the heated air supply path. It includes at least one of a warming step of warming the drying device by supplying the heated air to the passage.

  According to the method (6), warming of the drying device can be performed before the start of drying, or the drying device can be purged after the drying is stopped. Thereby, the dew condensation to the drying apparatus of the sulfur oxide contained in combustion gas can be suppressed, and corrosion of a drying apparatus can be suppressed.

  (7) In some embodiments, in the method of (6) above, the purge step includes either one of the first flow rate adjustment device and the second flow rate adjustment device in an open state. The heated air is supplied to the target flow path on the side provided with the closed flow rate adjusting device.

  According to the method of (7) above, the heated air can be flowed in this order through the drying device and the flow rate adjustment device in the open state. As a result, the drying apparatus can be purged. As a result, the residual amount of sulfur oxide after stopping the drying can be reduced, and the condensation of sulfur oxide can be suppressed even when the drying device is cooled.

  (8) In some embodiments, in the method of (7), the purge step is at least selected from the group consisting of oxygen, carbon dioxide, sulfur dioxide, nitrogen monoxide and nitrogen dioxide in the target flow path. When the fluctuation of the concentration of one component across a predetermined threshold is detected, the supply of the heated air to the target flow path is stopped and the other flow rate adjusting device is closed.

  According to the method (8), it is possible to appropriately determine the purge completion timing and complete the purge at an appropriate timing. For this reason, it is possible to suppress an increase in operation cost due to excessive supply of heated air.

  (9) In some embodiments, in any one of the above methods (6) to (8), the warm-up step is a state of the first flow rate adjustment device and the second flow rate adjustment device in a closed state. One of the flow rate adjusting devices is opened, and the heated air is supplied to the target flow channel on the side including the flow rate adjusting device that is kept closed.

  According to the method of (9) above, the heated air can be flowed in this order through the drying device and the flow rate adjustment device in the open state. Thereby, warming of a drying apparatus can be performed. As a result, when a high-temperature combustion gas is supplied to the drying device, such as immediately after the start of drying, rapid cooling of the combustion gas due to contact with the low-temperature drying device can be suppressed. For this reason, the dew condensation to the drying apparatus of the sulfur oxide contained in combustion gas can be suppressed, and corrosion of a drying apparatus can be suppressed.

  (10) In some embodiments, in the method of (9), the warming step includes the heating air to the target channel when the temperature in the target channel exceeds a predetermined threshold value. Is stopped, and the other flow rate adjusting device is opened.

  According to the method (10), it is possible to appropriately determine the warm-up completion time and complete the warm-up at an appropriate time. For this reason, it is possible to suppress an increase in operation cost due to excessive supply of heated air.

  (11) A boiler system according to at least one embodiment of the present invention includes a boiler, a desulfurization apparatus for desulfurizing the exhaust gas by bringing the exhaust gas discharged from the boiler into contact with cleaning water, and (1 ) To (5), the boiler system comprising the drying system according to any one of the above, wherein the combustion gas generation source includes the boiler, and the combustion gas includes the exhaust gas.

  According to the configuration of (11) above, in the drying apparatus using the exhaust gas discharged from the boiler, it is possible to perform warming before starting drying or purging after stopping drying. Thereby, the dew condensation to the drying apparatus of the sulfur oxide contained in the exhaust gas discharged | emitted from a boiler can be suppressed, and corrosion of a drying apparatus can be suppressed.

  (12) In some embodiments, in the configuration of the above (11), the water to be treated includes the washed water after the contact discharged from the desulfurization apparatus.

  According to the structure of said (12), discharge | emission to the exterior of the wash water after the said contact discharged | emitted from the desulfurization apparatus can be suppressed. Thereby, the waste water treatment with respect to the cleaning water after contact becomes unnecessary, and the operating cost of the boiler system can be reduced.

  (13) In some embodiments, in the configuration of (11) or (12), the exhaust gas discharge path is downstream of the exhaust gas duct with respect to a connection point between the combustion gas supply path and the exhaust gas duct. And connected to the exhaust gas duct.

  According to the configuration of (13) above, the exhaust gas discharge path can be connected to the downstream exhaust gas duct that is at a lower pressure than the connection point between the combustion gas supply path and the exhaust gas duct. Thereby, since the exhaust gas discharge path is disposed on the low pressure side, it is possible to easily flow a gas such as a combustion gas, a water-containing gas, and heated air to the exhaust gas duct due to a pressure difference. For this reason, the energy given from the outside in order to flow these gases can be suppressed.

  According to at least one embodiment of the present invention, it is possible to provide a drying system, an operation method thereof, and a boiler system capable of easily discharging warm air at the start of drying and residual gas after stopping drying.

It is a systematic diagram of the boiler system which concerns on one Embodiment of this invention. It is a figure which shows the drying apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the operating method (warming step) of the drying system which concerns on one Embodiment of this invention. It is a flowchart which shows the operating method (purge step) of the drying system which concerns on one Embodiment of this invention. It is a systematic diagram of the boiler system which concerns on two embodiment of this invention. It is a flowchart which shows the operating method (warming step) of the drying system which concerns on two embodiment of this invention. It is a flowchart which shows the operating method (purge step) of the drying system which concerns on two embodiment of this invention. It is a systematic diagram of the boiler system which concerns on three embodiment of this invention.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the contents described in the following embodiments or the contents described in the drawings are merely examples, and can be arbitrarily changed and implemented without departing from the gist of the present invention. Moreover, each embodiment can be implemented in any combination of two or more.
In addition, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.
For example, expressions expressing relative or absolute arrangements such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly In addition to such an arrangement, it is also possible to represent a state of relative displacement with an angle or a distance such that tolerance or the same function can be obtained.
For example, an expression indicating that things such as “identical”, “equal”, and “homogeneous” are in an equal state not only represents an exactly equal state, but also has a tolerance or a difference that can provide the same function. It also represents the existing state.
For example, expressions representing shapes such as quadrangular shapes and cylindrical shapes represent not only geometrically strict shapes such as quadrangular shapes and cylindrical shapes, but also irregularities and chamfers as long as the same effects can be obtained. A shape including a part or the like is also expressed.
On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one constituent element are not exclusive expressions for excluding the existence of the other constituent elements.

  FIG. 1 is a system diagram of a boiler system 100 according to an embodiment of the present invention. The boiler system 100 is provided in a thermal power plant or the like (not shown) and includes a boiler 10. In the boiler system 100, sulfur oxides contained in the combustion gas (exhaust gas) from the boiler 10 are removed by a wet desulfurization apparatus 14 (described later). Then, the washing water used in the desulfurization device 14 is vaporized by the drying device 20 (described later) without being drained to the outside, and circulates in the boiler system 100.

  The boiler system 100 includes a boiler 10, a denitration device 11, an air heater 12, a dust collection device 13, a desulfurization device 14, a solid-liquid separation device 15, and a drying system 200. Among these, the boiler 10, the denitration device 11, the air heater 12, the dust collector 13, and the desulfurization device 14 are provided by an exhaust gas duct 61 that flows the combustion gas discharged from the boiler 10 (combustion gas generation source). Connected. However, the combustion gas generation source may be other than the boiler 10. Further, the drying system 200 dries the cleaning water (processed water described later) discharged from the solid-liquid separator 15 after contact with the heat of the combustion gas generated in the boiler 10, which will be described in detail later. Is for. The drying system 200 includes a drying device 20. Hereinafter, the boiler system 100 will be described focusing on the gas flow in the boiler system 100.

  In the boiler 10 supplied with fuel, various types of fuel (one type or two or more types) such as fossil fuel (coal, heavy oil, etc.), biomass fuel (alcohol, etc.), solid fuel (wood, charcoal, etc.), etc. Steam is generated by combustion. Then, a steam turbine (not shown) is driven by the steam generated by the boiler 10. At this time, the combustion of the fuel is performed using combustion air supplied from an air heater 12 described later. Then, power is generated by a generator (not shown) connected to the steam turbine by driving the steam turbine.

  The combustion of fuel in the boiler 10 generates combustion gas (exhaust gas) containing nitrogen oxides and sulfur oxides, including nitrogen oxides and sulfur oxides generated due to impurities. In particular, among the various fuels described above, the combustion gas generated by the combustion of fossil fuels contains a large amount of nitrogen oxides and sulfur oxides. Therefore, this combustion gas is supplied to the denitration device 11, and denitration is performed in the denitration device 11. Thereby, the nitrogen oxide in the combustion gas is removed. A part of the combustion gas after removal of nitrogen oxides is supplied to the drying device 20 included in the drying system 200 through a combustion gas supply path 62 connected to an exhaust gas duct 61 connecting the denitration device 11 and the air heater 12. The The remaining portion passes through the exhaust gas duct 61 and is supplied to the air heater 12.

  The air heater 12 is composed of, for example, a heat exchanger, and heats the combustion air supplied to the boiler 10 with the heat of the combustion gas. Thereby, the combustion air that has reached a high temperature is supplied to the boiler 10.

  The combustion gas radiated in the air heater 12 is supplied to the dust collector 13. And dust collection is performed in the dust collector 13. Dust ash generated by dust collection is discharged. On the other hand, the dust-collected combustion gas is supplied to the desulfurization device 14, and sulfur oxide is removed, that is, desulfurization is performed.

  The desulfurization device 14 is for desulfurization of the combustion gas by bringing the combustion gas discharged from the boiler 10 into contact with the cleaning water. The desulfurization device 14 is a wet desulfurization device in the boiler system 100. As washing water, for example, lime water (calcium carbonate aqueous solution slurry) can be used. By the desulfurization in the desulfurization apparatus 14, the sulfur oxide in the combustion gas is removed. Then, the combustion gas after the sulfur oxide is removed is exhausted to the outside. The combustion gas may include a gas other than so-called exhaust gas discharged from the boiler 10.

  On the other hand, the sulfur oxide contained in the combustion gas is recovered as a solid by contact with the cleaning water. Specifically, for example, when the above lime water is used as the washing water, the sulfur oxide is precipitated as calcium sulfate. Therefore, the washing water containing calcium sulfate is subjected to solid-liquid separation in the solid-liquid separation device 15. By solid-liquid separation, gypsum (calcium sulfate) is recovered as a solid content. The collected gypsum is shipped as an industrial product, for example.

  In addition, the filtrate after separating and recovering gypsum may contain chloride ions, heavy metal ions and the like as described above. Therefore, in the boiler system 100, the filtrate generated by the solid-liquid separator 15 is circulated in the boiler system 100 without draining to the outside. Specifically, the filtrate is supplied to the drying device 20 through the to-be-treated water supply path 65. And it dries in the drying apparatus 20, and to-be-processed water turns into gas and returns to the desulfurization apparatus 14 again.

  Here, the filtrate produced in the solid-liquid separation device 15 is washing water after contact with the combustion gas in the desulfurization device 14, and the washing water after contact discharged from the desulfurization device 14 (that is, Contact absorbing liquid). Therefore, this contact absorbing liquid is hereinafter referred to as treated water. The water to be treated may include water other than waste water, or other water.

  In the drying device 20, the water to be treated is vaporized (evaporated) by the heat of the combustion gas supplied from the denitration device 11 as described above. This point will be described with reference to FIG.

  FIG. 2 is a diagram illustrating a drying device 20 according to an embodiment of the present invention. The drying device 20 is for vaporizing the water to be treated by the heat of the combustion gas. The drying apparatus 20 has an internal space 20A that is connected to a combustion gas supply path 62 (described later) and configured to bring the combustion gas supplied from the combustion gas supply path 62 into contact with the water to be treated. In the drying device 20, the water to be treated is vaporized in the internal space 20A.

  The drying device 20 includes a housing 21, a combustion gas supply port 26, a water supply unit 27, and an exhaust port 28. Among these, the combustion gas supply port 26 is connected to the combustion gas supply path 62 (see FIG. 1) and supplies combustion gas to the casing 21. The water supply unit 27 is connected to the treated water supply path 65 (see FIG. 1) and supplies treated water into the housing 21. The treated water supplied into the casing 21 comes into contact with the combustion gas in the internal space 20A and is vaporized by the heat of the combustion gas. The water supply unit 27 is, for example, a nozzle. Further, the exhaust port 28 is connected to an exhaust gas discharge path 63 (see FIG. 1) and discharges moisture-containing gas containing vaporized water to be treated to the outside of the casing 21.

  In the internal space 20 </ b> A of the drying device 20, for example, water to be treated is sprayed by a water supply unit 27 configured by nozzles. The spray of the water to be treated is performed from the top to the bottom. And combustion gas is supplied from the combustion gas supply port 26 so that it may flow in the same direction as the spray method of to-be-processed water. Therefore, the combustion gas also flows from the upper side to the lower side in the internal space 20 </ b> A of the drying device 20 as indicated by the white arrow in FIG. 2. Then, the sprayed water to be treated is vaporized (evaporated) by contacting the water to be treated while high-temperature (for example, about 100 ° C. to 200 ° C.) combustion gas flows downward. The combustion gas that has reached the bottom portion 22 is exhausted from the exhaust port 28 to the outside of the drying device 20 as a water-containing gas together with the vaporized water to be treated, as indicated by white arrows in FIG.

  In addition, heavy combustion ash, foreign matter, solid content, and the like contained in the combustion gas accumulate as deposits 23 at the bottom of the casing 21. The deposit 23 opens the valve 25 provided at the bottom of the casing 21 and is discharged to the outside of the casing 21 through the outlet 24 during maintenance.

  As described above, by drying the cleaning water discharged from the desulfurization apparatus 14 after contact with the combustion gas, that is, the water to be treated, discharge of the water to be treated to the outside can be suppressed. Thereby, the waste water treatment with respect to to-be-processed water becomes unnecessary, and the operating cost of the boiler system 100 can be reduced.

  Returning to FIG. 1, in addition to the drying apparatus 20 described with reference to FIG. 2, the drying system 200 includes a first flow rate adjustment device 31, a heating device 32, a blower 33, and a second flow rate adjustment device 41. A combustion gas supply path 62, an exhaust gas discharge path 63, and a heated air supply path 64. Hereinafter, the configuration of the drying system 200 will be described focusing on the gas flow in the drying system 200.

  The combustion gas supply path 62 connected to the exhaust gas duct 61 is connected to the combustion gas supply port 26 (see FIG. 2) of the drying device 20 as described above. Therefore, the combustion gas discharged from the boiler 10 and flowing through the exhaust gas duct 61 is supplied to the internal space 20 </ b> A (see FIG. 2) of the drying device 20 through the combustion gas supply path 62. Then, in the internal space 20A, the water to be treated is vaporized as described above. The water-containing gas containing the water to be treated is returned to the exhaust gas duct 61 through the exhaust gas discharge path 63. Accordingly, the exhaust gas discharge path 63 is a water-containing gas (exhaust gas) discharged from the drying device 20 and discharges a water-containing gas (exhaust gas) containing the water to be treated which is vaporized by contact with the water to be treated. Is to do.

  The exhaust gas discharge path 63 is connected to the exhaust gas duct 61 on the downstream side of the exhaust gas duct 61 from the connection point between the combustion gas supply path 62 and the exhaust gas duct 61. In this way, the exhaust gas discharge path 63 can be connected to the downstream exhaust gas duct 61 that is at a lower pressure than the connection point between the combustion gas supply path 62 and the exhaust gas duct 61.

  Here, since pressure loss occurs when the combustion gas passes through the air heater 12, the exhaust gas duct 61 on the downstream side of the air heater 12 has a lower pressure than the exhaust gas duct 61 on the upstream side of the air heater 12. For this reason, the exhaust gas discharge path 63 is connected to the exhaust gas duct 61 on the downstream side of the air heater 12, thereby connecting to the exhaust gas duct 61 on the low pressure side as described above. As a result, gas such as combustion gas, moisture-containing gas, and heated air can be easily flowed to the exhaust gas duct 61 due to a pressure difference. For this reason, the energy given from the outside in order to flow these gases can be suppressed.

  The drying system 200 includes a first flow rate adjustment device 31 provided in the middle of the combustion gas supply path 62. The first flow rate adjusting device 31 is for adjusting the flow rate of the combustion gas flowing through the combustion gas supply path 62, and is, for example, a damper or a valve. In addition, the drying system 200 includes a second flow rate adjustment device 41 provided in the middle of the exhaust gas discharge path 63. The second flow rate adjusting device 41 is for adjusting the flow rate of the moisture-containing gas flowing through the exhaust gas discharge path 63, and is, for example, a damper.

  The drying system 200 includes a heated air supply path 64 that is connected to a target flow path formed between the first flow rate adjustment device 31 and the second flow rate adjustment device 41 and supplies heated air. The target flow path here refers to a target flow path downstream of the first flow rate adjusting device 31 in the combustion gas supply path 62, an internal space 20 </ b> A of the drying apparatus 20, and a first flow path in the exhaust gas discharge path 63. 2 is a flow path including the upstream side of the flow rate adjusting device 41. Then, air (heated air) heated by the heating device 32 is supplied to the target flow path through the heated air supply path 64 by driving the blower 33. Thereby, the target flow path is warmed at the time of warm air. Further, at the time of purging, the combustion gas containing sulfur oxide remaining in the target flow channel is pushed out to the exhaust gas duct 61 by supplying heated air.

When heated air is supplied to the target flow path, the heated air is a flow path on the downstream side of the target flow path (the exhaust gas discharge path 63 and the downstream flow path of the second flow rate adjustment device 41). The exhaust gas duct 61 is passed through. Therefore, the flow path downstream of the target flow path is also warmed when warming up and purged when purging.
Further, the heated air does not need to be discharged to the exhaust gas duct 61, and an arbitrary discharge port may be formed in the target flow path and discharged to the outside through this discharge port. In this case, both the first flow rate adjusting device 31 and the second flow rate adjusting device 41 may be closed, or at least one of them may be opened while reducing the opening degree.
Furthermore, the heating air may be supplied in a predetermined amount, for example, may be supplied until a desired temperature is reached while measuring the temperature of the target flow path.

  In the boiler system 100 shown in FIG. 1, the heated air supply path 64 is connected to the combustion gas supply path 62 downstream of the first flow rate adjusting device 31. In this way, the exhaust gas discharge path 63 can be connected to the downstream exhaust gas duct 61 that is at a lower pressure than the connection point between the combustion gas supply path 62 and the exhaust gas duct 61. Thereby, since the exhaust gas discharge path 63 is disposed on the low pressure side, the supplied heated air can be easily flowed to the exhaust gas duct 61 due to a pressure difference. Further, the heated air supplied to the combustion gas supply path 62 can be easily flowed to the exhaust gas duct 61 through the low-pressure side drying device 20 and the exhaust gas discharge path 63. For this reason, warm air and purging (described later) can be easily performed while suppressing energy applied from the outside in order to flow heated air.

  The heated air supply path 64 may be connected to the internal space 20 </ b> A of the drying device 20, or may be connected to the upstream side of the second flow rate adjustment device 41 in the exhaust gas discharge path 63. Then, when warming up and purging, the first flow rate adjusting device 31 and the second flow rate adjusting device 41 may be controlled according to the connection position of the heated air supply path 64.

  The temperature of the heated air supplied through the heated air supply path 64 is equal to or higher than the acid dew point temperature of the combustion gas discharged from the boiler 10. Specifically, it is, for example, about 110 ° C to 180 ° C. By supplying heated air having an acid dew point temperature or higher, the temperature of the drying device 20 can be sufficiently increased before the drying is started. In addition, after the drying is stopped, the heated air having the acid dew point temperature or higher comes into contact with the combustion gas, so that the combustion gas can be prevented from being excessively cooled. By these, dew condensation (for example, sulfur trioxide) of sulfur oxide can be more sufficiently suppressed. The acid dew point can be calculated using, for example, the Muller equation.

  Further, the drying system 200 further includes a control device 50 connected to the electric signal line indicated by a broken line in FIG. 1 with respect to the first flow rate adjusting device 31, the second flow rate adjusting device 41, and the blower 33. The control device 50 is configured to control the opening degree of at least one of the first flow rate adjustment device 31 or the second flow rate adjustment device 41. The control device 50 is also configured to control the operation of the blower 33 in order to adjust the supply amount of heated air.

  The control device 50 controls the opening degree of at least one of the first flow rate adjustment device 31 and the second flow rate adjustment device 41 in accordance with the supply amount of heated air, as will be described later in detail. Specifically, for example, the opening degree of at least one of the first flow rate adjustment device 31 and the second flow rate adjustment device 41 is controlled so that the amount equivalent to the supply amount of heated air flows. Thereby, it can suppress that the internal pressure of the drying apparatus 20 rises excessively with supply of heated air. For this reason, the pressure | voltage resistant performance requested | required of the drying apparatus 20 can be made small, and the installation cost of the drying apparatus 20 can be reduced.

  Although not shown, the control device 50 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a HDD (Hard Disk Drive), an I / F (InterFace), and a control circuit. Etc., and a predetermined control program stored in the ROM is executed by the CPU.

  In the above-described drying system 200, a specific control method will be described later with reference to FIG. 3 and the like, but warming of the drying device 20 is performed before the drying is started, and purging of the drying device 20 is performed after the drying is stopped. Further, warming and purging are also performed on the combustion gas supply path 62 and the exhaust gas discharge path 63 (that is, the target flow path) connected to the drying device 20. Specifically, by opening at least one of the first flow rate adjusting device 31 and the second flow rate adjusting device 41 and allowing the heated air to flow through the target flow path, these warming and purging are easily performed. be able to. By warming up and purging, dew condensation on the drying device 20 of sulfur oxide can be suppressed, and corrosion of the drying device 20 can be suppressed.

  FIG. 3 is a flowchart showing an operation method (warm-up step) of the drying system 200. In the following description, for simplification of description, warm air and purge of the drying device 20 will be mainly described, and warm air and purge of the combustion gas supply path 62 and the exhaust gas discharge path 63 will not be referred to.

  In the drying system 200, the drying apparatus 20 is warmed up along the flow shown in FIG. 3 before the start of drying. Although details will be described later, after the drying is completed, the drying apparatus 20 is purged along the flow shown in FIG. However, only one of warm air and purge may be performed. Since warming and purging are performed by the control device 50 shown in FIG. 1, the description of FIG. 3 will be made with reference to FIG.

  Before the drying by the drying device 20 is started, the combustion gas is not supplied to the drying device 20. That is, both the first flow rate adjusting device 31 and the second flow rate adjusting device 41 are closed. Therefore, for warm air, the control device 50 includes a flow rate adjustment device that opens and closes one of the closed first flow rate adjustment device 31 and the second flow rate adjustment device 41. Heated air is supplied to the target flow path on the side (warm-up step).

  Specifically, first, the control device 50 opens the second flow rate adjustment device 41 (step S1, warm-up step). As described above, the connection point (downstream side of the air heater 12) of the exhaust gas duct 61 with the exhaust gas discharge path 63 is at a low pressure, so that the exhaust gas to the drying system 200 is opened even when the second flow rate adjustment device 41 is opened. Inflow is suppressed. Next, the control device 50 drives the blower 33 and supplies heated air through the heated air supply path 64 (step S2, warm-up step). Thus, the heated air flows into the exhaust gas duct 61 through the target flow path including the combustion gas supply path 62, the internal space 20A of the drying device 20 and the exhaust gas discharge path 63. Here, the heated air is heated by the heating device 32 and has a high temperature. Therefore, the drying device 20 is warmed by the flow of heated air, and the drying device 20 is warmed (step S3, warming step).

  According to such a procedure, heated air can be passed through the drying device 20. Thereby, the drying apparatus 20 can be warmed up. As a result, when a high-temperature combustion gas is supplied to the drying device 20 such as immediately after the start of drying, rapid cooling of the combustion gas due to contact with the low-temperature drying device 20 can be suppressed. For this reason, the dew condensation to the drying apparatus 20 of the sulfur oxide contained in combustion gas can be suppressed, and corrosion of the drying apparatus 20 can be suppressed.

  After the start of warming-up, the control device 50 monitors the temperature in the target flow path using a temperature sensor (not shown). And the control apparatus 50 judges that warming-up was completed when the temperature in the said object flow path exceeds the predetermined threshold value (Yes of step S4, warming-up step). On the other hand, when the temperature in the target flow path is equal to or lower than a predetermined threshold, it is determined that the warming is insufficient, and the warming is continued (No in step S4, warming step).

  In this way, by determining the completion of warm-up based on the temperature, it is possible to appropriately determine the completion time of warm-up and complete warm-up at an appropriate time. For this reason, it is possible to suppress an increase in operation cost due to excessive supply of heated air.

  When it is determined that the warm air is completed, the control device 50 stops the blower 33 and stops the supply of the heated air to the target flow path (step S5, warm air step). And the control apparatus 50 opens the 1st flow volume adjustment apparatus 31 (step S6, warming-up step). Thereby, warm air is completed, supply of the combustion gas to the drying apparatus 20 is started, and drying of to-be-processed water is started (step S7).

  FIG. 4 is a flowchart showing an operation method (purge step) of the drying system 200 according to an embodiment of the present invention. After the drying is stopped in the drying device 20, the drying device 20 is purged.

  During drying by the drying device 20, combustion gas is supplied to the drying device 20. Therefore, both the first flow rate adjusting device 31 and the second flow rate adjusting device 41 are open. Therefore, the control device 50 closes one of the first flow rate adjustment device 31 and the second flow rate adjustment device 41 in the open state, and closes the target flow channel on the side including the closed flow rate adjustment device. Supply heated air (purge step).

  Specifically, first, in order to stop drying, the control device 50 closes the first flow rate adjusting device 31 (step S11, purge step). Thereby, supply of combustion gas stops. Here, supply of the to-be-processed water to the drying apparatus 20 is also stopped, and drying is stopped. Then, the supply of heated air is performed in the same manner as the supply of heated air described with reference to FIG. 3 (step S2, purge step). Thereby, the combustion gas remaining in the internal space 20A of the drying device 20 is discharged, and the drying device 20 is purged (step S12, purge step).

  According to such a procedure, the heated air can be supplied to the drying device 20 and the second flow rate adjustment device 41 in the open state in this order. Thereby, the drying apparatus 20 can be purged. As a result, the residual amount of sulfur oxide after stopping drying can be reduced, and even when the drying device 20 is cooled, condensation of sulfur oxide can be suppressed.

  After starting the purge, the internal gas replacement rate is calculated based on the capacity of the drying device 20, the combustion gas supply passage 62 and the exhaust gas discharge passage 63, and the heated air supply amount. Completion of purge may be determined. Further, the control device 50 may monitor the concentration of at least one component selected from the group consisting of oxygen, carbon dioxide, sulfur dioxide, nitrogen monoxide and nitrogen dioxide in the target flow path with a concentration sensor (not shown). . At that time, the control device 50 determines that the purge is completed when it detects a fluctuation in which the concentration of the at least one component crosses a predetermined threshold (step S13, purge step).

  That is, in the combustion gas, each concentration of carbon dioxide, sulfur dioxide, nitrogen monoxide, and nitrogen dioxide (hereinafter referred to as carbon dioxide concentration) is high and the oxygen concentration is low compared to heated air. Therefore, if the purge proceeds, the concentration of carbon dioxide and the like in the target flow path decreases, while the oxygen concentration increases due to the supply of heated air. Therefore, it can be determined that the purge has been completed when a change across the threshold is detected, such as when the concentration of carbon dioxide or the like falls below the threshold, or when the oxygen concentration exceeds the threshold. On the other hand, until a change across the threshold is detected, it is determined that the purge is insufficient, and the purge is continued (No in step S13).

  Thus, by detecting the concentration variation and determining the completion of the purge, it is possible to appropriately determine the purge completion timing and complete the purge at an appropriate timing. For this reason, it is possible to suppress an increase in operation cost due to excessive supply of heated air.

  When it is determined that the purge is completed, the control device 50 stops the blower 33 and stops the supply of heated air to the target flow path (step S5, purge step). Then, the control device 50 closes the second flow rate adjustment device 41 (the other flow rate adjustment device) (step S14, purge step).

  By these procedures, the drying apparatus 20 is filled with heated air, and condensation of sulfur oxides after cooling is suppressed. Moreover, since the inside of the drying apparatus 20 is filled with heated air, the valve 25 (see FIG. 2) provided at the bottom of the drying apparatus 20 can be opened without the need for special processing. Therefore, maintenance such as taking out the deposit 23 through the discharge port 24 can be easily performed.

  According to the operation method shown in FIG. 3 and FIG. 4 above, it is possible to warm the drying device before starting drying and to purge the drying device after stopping drying. Thereby, dew condensation to the drying apparatus 20 of sulfur oxide can be suppressed, and corrosion of the drying apparatus 20 can be suppressed.

  FIG. 5 is a system diagram of the boiler system 101 according to the second embodiment of the present invention. In the following description, the same devices as those described with reference to FIG. 1 and the like are denoted by the same reference numerals, and description thereof is omitted for simplification of description.

  In the boiler system 101 shown in FIG. 5, a drying system 201 different from the drying system 200 provided in the boiler system 100 is provided. Specifically, the drying system 201 shown in FIG. 5 includes a first flow rate adjusting device 51 configured by, for example, a seal damper, instead of the first flow rate adjusting device 31 configured by, for example, a normal damper. . However, the second flow rate adjusting device 41 may be configured by a seal damper, and both the first flow rate adjusting device 31 and the second flow rate adjusting device 41 may be configured by a seal damper.

  As described above, the first flow rate adjusting device 51 is, for example, a seal damper, and seals with seal air sealed between two dampers. Specifically, the first flow rate adjusting device 51 is configured to include a first damper and a second damper, although none of them is shown. A sealed space is formed between the first damper and the second damper. And the air pressure in sealed space increases by supplying heated air (one form of air) to the said sealed space. Thereby, the said sealing space is sealed and the flow of the gas between an upstream side and a downstream side is interrupted | blocked. In addition, about the specific structure of a seal damper, the structure of the seal damper as described in Unexamined-Japanese-Patent No. 11-270838 is applicable, for example.

  The drying system 201 includes a blower 53 for supplying heated air to the first flow rate adjusting device 51 and a seal damper heating device 52 for producing heated air supplied to the first flow rate adjusting device 51. The heated air produced by the seal damper heating device 52 is supplied by the blower 53 to the first flow rate adjusting device 51 through the seal damper heated air supply path 66. In the first flow rate adjusting device 51, the gas flow between the upstream side and the downstream side of the combustion gas supply path 62 is blocked by the supplied heated air.

  In the drying system 201, a part of the heating air for sealing supplied to the first flow rate adjusting device 51 is supplied to the target flow path. Specifically, the heated air supply path 64 is connected to the heated air supply path 66 for the seal damper. And by the drive of the blower 33, a part of heating air which flows through the heating air supply path 66 for seal dampers branches, and flows through the heating air supply path 64, and heated air is supplied to the said target flow path. Thus, by using a part of the heating air for the seal damper, it is possible to warm and purge the drying device 20 using the existing heating air for the seal.

  FIG. 6 is a flowchart showing an operation method (warm-up step) of the drying system 201 according to the second embodiment of the present invention. In FIG. 6, the same steps as those described with reference to FIG. 3 are given the same step numbers, and redundant descriptions are omitted for the sake of simplicity.

  As described with reference to FIG. 3 above, the combustion gas is not supplied to the drying device 20 before the start of drying. Therefore, both the first flow rate adjustment device 51 and the second flow rate adjustment device 41 are closed. In particular, the first flow rate adjusting device 51 is supplied with the heating air for sealing as described above. Then, the gas flow between the upstream side and the downstream side of the combustion gas supply path 62 is blocked by the air pressure of the heating air for sealing.

  The control device 50 opens the second flow rate adjusting device 41 (step S1) in the same manner as the operation method described with reference to FIG. Supply of air is started (step S2). However, the supplied heated air is produced by the seal damper heating device 52 (see FIG. 5) as described above. Then, by supplying heated air, the drying device 20 is warmed up (step S3). If it is determined that the warming is completed (Yes in step S4), the blower 33 is stopped (step S5). Thereby, supply of the heating air to the said object flow path stops, and the warming of the drying apparatus 20 is completed.

  Next, the control device 50 stops driving the blower 53 and stops the supply of heated air to the first flow rate adjusting device 51 by the blower 53 (step S21, warm-up step). Thereby, the sealing in the first flow rate adjusting device 51 is released. Then, the control device 50 opens the first flow rate adjusting device 51 (step S22, warm-up step), and starts supplying combustion gas to the drying device 20 in the same manner as in step S7 described with reference to FIG. Then, drying of the water to be treated is started (step S7).

  FIG. 7 is a flowchart showing an operation method (purge step) of the drying system 201 according to the second embodiment of the present invention. In FIG. 7, the same steps as those described with reference to FIGS. 3 and 4 are given the same step numbers, and redundant description is omitted for the sake of simplicity.

  As described with reference to FIG. 4 above, combustion gas is supplied to the drying device 20 during drying. Therefore, both the first flow rate adjusting device 51 and the second flow rate adjusting device 41 are open. Therefore, the control device 50 first closes the first flow rate adjusting device 51 in order to stop the drying (step S31, purge step). Thereby, supply of the combustion gas to the drying apparatus 20 stops. Next, the control device 50 drives the blower 53 and starts supplying the heating air for sealing to the first flow rate adjusting device 51 (step S32, purge step). In the first flow control device 51 to which the heating air for sealing is supplied, the gas flow between the upstream side and the downstream side of the combustion gas supply path 62 is blocked by the air pressure of the heating air for sealing.

  Thereafter, the blower 33 is driven to supply heated air between the first flow rate adjusting device 51 and the second flow rate adjusting device 41 (step S2), and the drying device 20 is purged (step S12). Then, the control device 50 determines whether or not the purge is completed in the same manner as Step S13 described with reference to FIG. 4 (Step S13). When it is determined that the purge is completed (Yes in step S13), the control device 50 stops the blower 33 and stops the supply of heated air (step S5). And the control apparatus 50 closes the 2nd flow volume adjustment apparatus 41 (step S14). Thereby, the purge of the drying apparatus 20 is completed.

  According to the operation method shown in FIG. 6 and FIG. 7, warming of the drying device can be performed before the drying is started, and the drying device can be purged after the drying is stopped. Thereby, dew condensation to the drying apparatus 20 of sulfur oxide can be suppressed, and corrosion of the drying apparatus 20 can be suppressed.

  In addition, warm air and purge can be performed by using a part of the heated air produced by the seal damper heating device 52. For this reason, in particular, when the seal damper heating device 52 is already installed, it is possible to perform warming and purging only by increasing the equipment to increase the amount of heated air produced by the seal damper heating device 52. Become.

  FIG. 8 is a system diagram of the boiler system 102 according to the third embodiment of the present invention. Also in the boiler system 102, similarly to the boiler system 101 shown in FIG. 5 described above, the heated air produced in the seal damper heating device 52 is supplied to the first flow rate adjusting device 51 and the target flow path. That is, using the heated air, the first flow rate adjusting device 51 is sealed, and the target channel is warmed and purged. In the case of the boiler system 101, the supply of heated air to the first flow rate adjusting device 51 and the supply of heated air to the target flow path are performed by driving different blowers 33 and 53 (see FIG. 5). Is called.

  On the other hand, in the boiler system 102 shown in FIG. 8, unlike the boiler system 101, heated air is supplied to the first flow rate adjusting device 51 and the target flow path by driving one blower 53. That is, the boiler system 102 does not include the blower 33 described above, but includes only the blower 53. Further, on the downstream side of the blower 53, a heating air supply path 64 is formed by branching from the heating air supply path 66 for the seal damper. Therefore, heated air is supplied to the first flow rate adjusting device 51 and the target flow path through the heated air supply path 64 and the seal damper heated air supply path 66 branched from the blower 53 by driving the blower 53. .

  The heated air supply path 64 is provided with a valve 54 for opening and closing the flow path. The opening and closing of the valve 54 is controlled by the control device 50 through an electric signal line indicated by a broken line in FIG. For example, when supplying heated air only to the first flow rate adjusting device 51, the valve 54 is closed. On the other hand, when supplying heated air to both the first flow rate adjusting device 51 and the target flow path, the valve 54 is opened.

  In addition, when supplying heated air to an object flow path, the 1st flow volume adjustment apparatus 51 is sealed as mentioned above. Therefore, normally, heating air is supplied to and stopped from the target flow path in a state where the first flow rate adjustment device 51 is sealed, and therefore the valve 54 is provided only in the heating air supply path 64.

  Thus, the installation cost of the boiler system 102 can be reduced by making it possible to supply heated air to both the first flow control device 51 and the target flow path using one blower 53. Moreover, the power consumption of the boiler system 102 can be reduced and the operating cost can be reduced.

  The valve 54 may be a valve whose opening degree can be adjusted. By using the valve 54 whose opening degree can be adjusted, the supply amount of the heated air to each of the first flow rate adjusting device 51 and the target flow path can be adjusted. For this reason, the sealing in the first flow rate adjusting device 51 and the purging and warming in the target flow path can be performed more appropriately.

DESCRIPTION OF SYMBOLS 10 Boiler 11 Denitration apparatus 12 Air heater 13 Dust collector 14 Desulfurization apparatus 15 Solid-liquid separation apparatus 20 Drying apparatus 20A Internal space 21 Case 22 Bottom 23 Deposit 24 Discharge port 25, 54 Valve 26 Combustion gas supply port 27 Water supply unit 28 Exhaust Ports 31, 51 First flow rate adjustment device 32 Heating device 33, 53 Blower 41 Second flow rate adjustment device 50 Control device 52 Heater 61 for seal damper Exhaust gas duct 62 Combustion gas supply path 63 Exhaust gas discharge path 64 Heated air supply path 65 Water supply path 66 to be treated Heated air supply path 100, 101 for seal damper Boiler system 200, 201 Drying system

Claims (13)

A drying system for drying water to be treated by heat of combustion gas generated in a combustion gas generation source,
A combustion gas supply path connected to an exhaust gas duct for flowing the combustion gas discharged from the combustion gas generation source;
A first flow rate adjusting device provided in the middle of the combustion gas supply path;
A drying apparatus having an internal space connected to the combustion gas supply path and configured to bring the combustion gas supplied from the combustion gas supply path into contact with the water to be treated;
An exhaust gas exhaust path for exhausting exhaust gas exhausted from the drying device, the exhaust gas containing the treated water vaporized by contact with the treated water;
A second flow rate adjusting device provided in the middle of the exhaust gas discharge path;
A drying system comprising: a heated air supply path for supplying heated air, connected to a target flow path formed between the first flow rate adjusting apparatus and the second flow rate adjusting apparatus. . The drying system according to claim 1, wherein the temperature of the heated air is equal to or higher than an acid dew point temperature of the combustion gas. At least one of the first flow rate adjusting device or the second flow rate adjusting device includes a seal damper that seals the damper with air pressure,
The drying system according to claim 1 or 2, wherein a part of the sealing air supplied to the seal damper is supplied to the target flow path as the heated air. The exhaust gas discharge path is connected to the exhaust gas duct on the downstream side of the exhaust gas duct from the connection point between the combustion gas supply path and the exhaust gas duct,
The drying system according to any one of claims 1 to 3, wherein the heated air supply path is connected to the combustion gas supply path downstream of the first flow rate adjusting device. A control device for controlling an opening degree of at least one of the first flow rate adjusting device or the second flow rate adjusting device;
The drying system according to any one of claims 1 to 4, wherein the control device is configured to control the opening degree in accordance with a supply amount of the heated air. An operation method of a drying system for drying water to be treated by heat of combustion gas generated in a combustion gas generation source,
The drying system includes:
A combustion gas supply path connected to an exhaust gas duct for flowing the combustion gas discharged from the combustion gas generation source;
A first flow rate adjusting device provided in the middle of the combustion gas supply path;
A drying apparatus having an internal space connected to the combustion gas supply path and configured to bring the combustion gas supplied from the combustion gas supply path into contact with the water to be treated;
An exhaust gas exhaust path for exhausting exhaust gas exhausted from the drying device, the exhaust gas containing the treated water vaporized by contact with the treated water;
A second flow rate adjusting device provided in the middle of the exhaust gas discharge path;
A heated air supply path connected to a target flow path formed between the first flow rate adjustment device and the second flow rate adjustment device, and for supplying heated air;
The operation method of the drying system is:
A purge step of discharging the combustion gas in the drying device by supplying the heated air from the heated air supply channel to the target channel; or
A method for operating a drying system, comprising: at least one of a warming step of warming the drying device by supplying the heated air from the heated air supply channel to the target channel. The purge step closes one of the first flow rate adjustment device and the second flow rate adjustment device in the open state, and heats the target flow path on the side including the closed flow rate adjustment device. The method of operating a drying system according to claim 6, wherein air is supplied. When the purge step detects a change in the concentration of at least one component selected from the group consisting of oxygen, carbon dioxide, sulfur dioxide, nitrogen monoxide and nitrogen dioxide across a predetermined threshold in the target flow path. The operation method of the drying system according to claim 7, wherein the supply of the heated air to the target flow path is stopped and the other flow rate adjustment device is closed. In the warming step, one of the first flow rate adjustment device and the second flow rate adjustment device in the closed state is opened, and the target flow channel on the side including the flow rate adjustment device that is kept closed is opened. The method for operating a drying system according to any one of claims 6 to 8, wherein the heated air is supplied. In the warming step, when the temperature in the target flow path exceeds a predetermined threshold, the supply of the heated air to the target flow path is stopped and the other flow rate adjusting device is opened. A method for operating the drying system according to claim 9. With a boiler,
A desulfurization device for desulfurizing the exhaust gas by bringing the exhaust gas discharged from the boiler into contact with cleaning water;
A boiler system comprising the drying system according to any one of claims 1 to 5,
The combustion gas generation source includes the boiler,
The boiler system, wherein the combustion gas includes the exhaust gas. The boiler system according to claim 11, wherein the treated water includes the washed water after the contact discharged from the desulfurization apparatus. The exhaust gas discharge path is connected to the exhaust gas duct at a downstream side of the exhaust gas duct from a connection point between the combustion gas supply path and the exhaust gas duct. Boiler system.

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