JP2015117867A - Boiler system and power generation plant with boiler system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat efficiency in a case of using a solid fuel such as carbon having a high water content as a fuel.SOLUTION: Provided is a boiler system 100 including: a coal mill 10 producing a pulverized fuel; a forced-ventilation fan 84 blowing primary air into the coal mill 10; a cyclone 30 separating a gas mixture containing the pulverized fuel produced by the coal mill 10 and the primary air into a high-concentration gas mixture and a low-concentration gas mixture; a boiler 20 firing the high-concentration gas mixture obtained by separation by the cyclone 30 and generating steam; and a condenser 50 implementing heat exchange between the low-concentration gas mixture obtained by separation by the cyclone 30 and water.

Description

  The present invention relates to a boiler system and a power plant including the same.

  In recent years, there has been a demand for practical use of a power plant using coal with a low degree of coalification such as lignite and subbituminous coal as an energy source. These coals have a high water content, and if burned as they are, heat loss occurs due to latent heat of evaporation. In order to avoid such heat loss, it is necessary to dry the coal in advance prior to combustion in the boiler (see, for example, Patent Document 1). Patent Document 1 discloses a technique for drying coal using combustion gas after passing through an air heater.

JP-A-10-281443

As disclosed in Patent Document 1, heat loss in the boiler can be avoided by drying coal having a high water content in advance.
However, if the moisture evaporated by drying the coal is supplied to the boiler together with the coal as it is, moisture that does not contribute to combustion is supplied to the boiler. Since the concentration of fuel containing moisture that does not contribute to combustion is low, the combustion efficiency deteriorates.
In addition, since the volume is increased by the steam generated by the evaporation of moisture, it is necessary to increase the pipe diameter and the boiler size so that the volume can be accommodated.

  This invention is made | formed in view of such a situation, and provides the boiler system which improved the thermal efficiency in the case of using solid fuels, such as coal with much moisture content, as a fuel, and a power plant provided with the same For the purpose.

In order to achieve the above object, the present invention employs the following means.
A boiler system according to the present invention includes a solid fuel pulverization unit that pulverizes a solid fuel and classifies the pulverized solid fuel to generate finely pulverized fuel having a particle size smaller than a predetermined particle size. A high-concentration mixed gas having a high content of the pulverized fuel and a low content of the pulverized fuel, a mixed gas containing the pulverized fuel and the primary air generated by the solid fuel pulverizing unit. A separation unit that separates into a low-concentration mixed gas, a boiler that generates steam by burning the high-concentration mixed gas separated by the separation unit, the low-concentration mixed gas separated by the separation unit, and another A heat exchanger for exchanging heat with the medium.

According to the boiler system according to the present invention, the mixed gas containing the pulverized fuel and the primary air generated by the solid fuel pulverization unit is a high-concentration mixed gas having a high pulverized fuel content and the pulverized fuel content by the separation unit Is separated into a low-concentration mixed gas having a low concentration. Since the high-concentration mixed gas containing a large amount of pulverized fuel is used for combustion in the boiler, the combustion efficiency of the boiler can be improved. In addition, heat exchange is performed between the low-concentration mixed gas containing a large amount of water evaporated from the solid fuel and the other medium by the heat exchanger, so that the amount of heat used for drying the solid fuel is appropriately recovered. be able to.
Therefore, the boiler system which improved the thermal efficiency in the case of using solid fuels, such as coal with much water content, as a fuel can be provided.

The boiler system according to the first aspect of the present invention includes an economizer that performs heat exchange between combustion gas generated by combustion of the high-concentration mixed gas by the boiler and water supplied from the outside, and the heat exchanger Is a condenser that performs heat exchange between the low-concentration mixed gas and water supplied to the economizer.
By doing in this way, since the water supplied to an economizer will be in the state heated previously, the thermal efficiency of a boiler system can be improved.

Further, the boiler system according to the second aspect of the present invention is configured to collect the pulverized fuel contained in the low-concentration mixed gas separated by the separation unit and supply the recovered pulverized fuel to the boiler. A dust collection unit for supplying a low concentration mixed gas to the heat exchanger is provided.
By doing in this way, it becomes possible to use the pulverized fuel contained in the low concentration mixed gas as the fuel of the boiler, and the thermal efficiency of the boiler system can be further improved.

  The boiler system according to the third aspect of the present invention performs heat exchange between the combustion gas generated by the combustion of the high-concentration mixed gas by the boiler and air and is preheated by heat exchange with the combustion gas. An air preheater that supplies the air as secondary air for combustion to the boiler, and a primary air supply passage that supplies the air preheated by the air preheater to the blower.

  By doing in this way, the air of the state preheated by the air preheater is blown by the solid fuel crushing part as primary air. Therefore, the amount of heat contained in the low-concentration mixed gas that has passed through the heat exchanger can be reused to improve the drying efficiency of the solid fuel in the solid fuel pulverization unit.

In the above aspect, the air preheater may preheat the low-concentration mixed gas that has passed through the heat exchanger, and supply the premixed gas to the air blowing unit via the primary air supply path.
By doing in this way, the low concentration mixed gas whose temperature is higher than that of the outside air can be preheated and blown to the solid fuel pulverizing section as primary air. Therefore, it is possible to further improve the drying efficiency of the solid fuel in the solid fuel pulverizing section.

A power plant according to the present invention includes any one of the above-described boiler systems, a steam turbine driven by the steam generated by the boiler, and a power generation device that generates power using rotational power obtained by the steam turbine. .
According to the power plant according to the present invention, it is possible to improve the thermal efficiency when a solid fuel such as coal having a high water content is used as a fuel.

  ADVANTAGE OF THE INVENTION According to this invention, the boiler system which improved the thermal efficiency in the case of using solid fuels, such as coal with much moisture content, as a fuel, and a power plant provided with the same can be provided.

1 is a system diagram showing a boiler system according to a first embodiment of the present invention. It is a longitudinal cross-sectional view which shows the coal mill shown in FIG. It is a systematic diagram which shows the boiler system which concerns on 2nd Embodiment of this invention.

[First Embodiment]
Hereinafter, the boiler system 100 of 1st Embodiment of this invention is demonstrated with reference to drawings.
As shown in FIG. 1, the boiler system 100 of the present embodiment includes a coal mill 10 (solid fuel pulverization unit), a forced air blower 84 (blower unit), a cyclone 30 (separation unit), a boiler 20, and a condensation unit. And 50 (heat exchanger).

  The coal mill 10 pulverizes the coal and classifies the pulverized coal with a classifier (not shown) to generate finely pulverized fuel smaller than a predetermined particle size. The forced draft fan 84 blows primary air to the coal mill 10. The cyclone 30 separates the mixed gas containing the pulverized fuel and the primary air generated by the coal mill 10 into a high concentration gas having a high content of pulverized fuel and a low concentration gas having a low content of pulverized fuel. The boiler 20 generates steam by burning the high-concentration mixed gas separated by the cyclone 30. The condenser 50 exchanges heat between the low-concentration mixed gas separated by the cyclone 30 and water (other medium).

  The mixed gas containing fine fuel and primary air generated by the coal mill 10 is separated into a high concentration mixed gas and a low concentration mixed gas by the cyclone 30. Since the high-concentration mixed gas containing a large amount of fine fuel is used for combustion in the boiler 20, the combustion efficiency of the boiler 20 is improved. Moreover, since heat is exchanged between the low-concentration mixed gas containing a large amount of water evaporated from coal and water by the condenser 50, the amount of heat used for drying the coal can be recovered appropriately.

Hereinafter, the boiler system 100 of the present embodiment will be described in detail.
As shown in FIG. 2, the coal mill 10 includes a hollow housing 11 having a substantially cylindrical shape, and a rotary table 12 that is disposed at a lower portion in the housing 11 and is rotatably attached to an axis extending in the vertical direction. The roller 13 is pressed by the outer peripheral portion 12b of the rotary table 12 and crushes the solid fuel in cooperation with the rotary table 12, and the drive unit 14 rotates the rotary table 12. The drive unit 14 includes an electric motor and a speed reducer, and a speed reducer that reduces the rotational speed of the electric motor is connected to the central portion 12 a of the rotary table 12 via a rotary shaft 15.

  In addition, the coal mill 10 supplies the classification unit 16 disposed at the upper part in the housing 11 and the solid fuel that is attached so as to penetrate the upper end of the housing 11 and is supplied from the upper part to the central part 12 a of the rotary table 12. And a solid fuel input unit 17. The lower end portion of the housing 11 communicates with a flow path (not shown), and primary air flows from the flow path to the lower end portion of the housing 11. The housing 11 is fixed to the upper surface of a pair of rectangular parallelepiped concrete blocks 19 installed on the floor 18.

  In FIG. 2, only one roller 13 is shown, but a plurality of rollers 13 are arranged at regular intervals in the outer circumferential direction so as to press the outer circumferential portion 12 b of the rotary table 12. For example, three rollers 13 are arranged on the outer peripheral portion 12b with an angular interval of 120 °. In this case, the portions where the three rollers 13 are in contact with the outer peripheral portion 12 b of the rotary table 12 (the portions to be pressed) are equidistant from the central portion 12 a of the rotary table 12.

  At a plurality of locations outside the turntable 12, air outlets 32 are provided to allow primary air flowing in from the forced draft fan 84 to flow out into the space above the turntable 12 in the housing 11. A vane 33 is installed above the air outlet 32, and the vane 33 gives a turning force to the primary air blown out from the air outlet 32. The primary air to which the turning force is given by the vane 33 becomes an air current as shown by an arrow in FIG. 2 and guides the solid fuel crushed on the rotary table 12 to the classification unit 16 above the housing 11. Of the pulverized solid fuel mixed in the primary air, the one having a large particle size falls without reaching the classification unit 16 and is returned to the rotary table 12 again.

  The classifying unit 16 includes a blade that rotates about the cylindrical axis of the substantially cylindrical housing 11. The pulverized product of the solid fuel that has reached the classification unit 16 flows into the blade only fine fuel having a particle size smaller than a predetermined particle size due to the relative balance between centrifugal force and centripetal force generated by the rotating blade and the flow of primary air. And flows out from the outlet 34. The pulverized fuel flowing out from the outlet 34 is guided to the cyclone 30 together with the primary air. The temperature of the mixed gas containing fine powder fuel and primary air guided to the cyclone 30 is about 60 to 100 ° C.

  The cyclone 30 is a device that separates the mixed gas generated by the coal mill 10 into a high concentration mixed gas and a low concentration mixed gas. The cyclone 30 supplies the boiler 20 with a high-concentration mixed gas produced by separating about 90% of the pulverized fuel in the mixed gas supplied from the coal mill 10 and includes the remaining about 10% of the pulverized fuel. The concentration mixed gas is supplied to the electric dust collector 40. The content of the pulverized fuel in the high concentration mixed gas is as high as about 90%, and the content of the pulverized fuel in the low concentration mixed gas is as low as about 10%.

  When pulverizing high-moisture coal such as lignite and subbituminous coal having a high water content in the coal mill 10, steam evaporated from the high-moisture coal is included in the mixed gas. Therefore, the volume ratio (Gas / Coal ratio) of the gas to the pulverized fuel in the mixed gas discharged from the coal mill 10 is, for example, about 4.0 to 6.0. This value is a remarkably large value when compared with about 1.5 to 2.5 in low moisture coal having a low water content.

  Here, the high moisture coal refers to, for example, coal having a ratio of moisture weight to coal weight of about 40% to 70%. Low moisture coal refers to coal having a ratio of moisture weight to coal weight of about 20% or less.

  The flow rate of the primary air mixed with about 95% pulverized fuel separated from the mixed gas is appropriately adjusted by the cyclone 30 so that the Gas / Coal ratio is about 1.5 to 2.5. By doing in this way, even if it uses high moisture coal as the fuel of the coal mill 10, the high concentration mixed gas of the same Gas / Coal ratio as the case where low moisture coal is used as fuel is supplied to the boiler 20. be able to.

  In addition, since a high-concentration mixed gas having a gas / coal ratio similar to that in the case of using low-moisture coal as the fuel is supplied to the boiler 20, a burner similar to that in the case of using low-moisture coal as the fuel should be adopted as the burner 25. Can do. Therefore, it is not necessary to redesign a special burner in order to use high moisture coal as fuel.

  The boiler 20 is a device that generates steam by burning the high-concentration mixed gas separated by the cyclone 30. The high-concentration mixed gas (about 60 to 100 ° C.) supplied to the boiler 20 is used as fuel for the burner 25. When the burner 25 burns the high-concentration mixed gas in the furnace of the boiler 20, a heat exchanger such as an evaporator, a superheater, or a reheater installed in the furnace is heated. These heat exchangers generate water by heating water flowing from the outside through the economizer 26.

The steam discharged from the boiler 20 via the superheater is supplied to a steam turbine (not shown). The steam turbine is driven by steam generated by the boiler 20 and generates rotational power. The rotational power obtained by the steam turbine is transmitted to the power generation device and used as power for power generation by the power generation device.
The power plant (not shown) of this embodiment is constituted by the boiler system 100 of this embodiment, a steam turbine, and a power generator.

  The electric dust collector 40 (dust collecting unit) provided in the boiler system 100 is a device that collects pulverized fuel contained in the low-concentration mixed gas separated by the cyclone 30 and supplies it to the burner 25 of the boiler 20. The electric dust collector 40 mixes the pulverized fuel recovered from the low concentration mixed gas into the high concentration mixed gas discharged from the cyclone 30. By doing in this way, the fine fuel which was not collect | recovered with the cyclone 30 can be supplied to the burner 25. FIG.

  The electric dust collector 40 supplies the low-concentration mixed gas from which the pulverized fuel is recovered to the condenser 50. The condenser 50 is supplied with the low-concentration mixed gas from which the pulverized fuel is recovered by the electric dust collector 40, so that the condenser 50 is prevented from being contaminated.

  The condenser 50 (heat exchanger) is heated between a high-temperature (about 60 to 100 ° C.) low-concentration mixed gas supplied from the electric dust collector 40 and water (other medium) at room temperature (about 20 ° C.). It is a device to be exchanged. As the condenser 50, various non-contact type heat exchangers such as a plate heat exchanger can be used. Water heated by heat exchange with the low-concentration mixed gas in the condenser 50 is supplied to the economizer 26 through the water supply pipe 27.

  A part of the steam contained in the low-concentration mixed gas that has been heat-exchanged with water at room temperature becomes drain water condensed in the condenser 50. The drain water is drained to the outside of the condenser 50.

  The economizer 26 is a heat exchanger that performs heat exchange between the combustion gas generated by the combustion of the high-concentration mixed gas by the burner 25 of the boiler 20 and the water supplied from the water supply pipe 27. The economizer 26 heats the water supplied from the water supply pipe 27 by the heat of the combustion gas generated in the furnace and supplies it to a heat exchanger (not shown) such as an evaporator, a superheater, or a reheater.

The low-concentration mixed gas discharged from the condenser 50 is guided to the chimney 90 by the induction fan 81 and discharged from the chimney 90 to the atmosphere.
The combustion gas discharged from the boiler 20 passes through the air preheater 60, is guided to the chimney 90 by the induction fan 82, and is discharged from the chimney 90 to the atmosphere.

  The low-concentration mixed gas discharged from the condenser 50 is about 40 to 60 ° C. The low-concentration mixed gas contains sulfur oxides such as sulfur trioxide released from coal. If the low-concentration mixed gas containing sulfur oxide falls below the dew point of sulfur oxide, the condenser 50 may corrode. In the present embodiment, sufficient primary air is contained in the mixed gas, and a large amount of sulfur oxide is adsorbed to the finely powdered fuel recovered by the electrostatic precipitator 40. Therefore, even if the low-concentration mixed gas is about 40 to 60 ° C., it is possible to prevent the occurrence of corrosion without lowering the dew point of the sulfur oxide.

  The air preheater 60 is a heat exchanger that performs heat exchange between high-temperature (about 300 to 400 ° C.) combustion gas generated by combustion of a high-concentration mixed gas by the boiler 20 and air at normal temperature in the atmosphere. The normal temperature air in the atmosphere is blown to the air preheater 60 by the forced air blower 83.

A part of the air heated by the heat exchange with the combustion gas in the air preheater 60 is supplied to the secondary air supply pipe 86, and the other part is supplied to the primary air supply pipes 87 and 88.
The air supplied to the secondary air supply pipe 86 is supplied to the burner 25 of the boiler 20 as secondary air for combustion. On the other hand, the air supplied to the primary air supply pipes 87 and 88 is supplied to the forced air blower 84 via the cyclone 70.

  A part of the combustion gas discharged from the boiler 20 is supplied to the air preheater 60 and the other part is supplied to the primary air supply pipe 88. Since a part of the high-temperature combustion gas is directly led from the boiler 20 to the primary air supply pipe 88, the primary air supplied to the coal mill 10 can be heated to a high temperature.

  A cyclone 70 is provided between the primary air supply pipe 88 and the forced draft fan 84. The cyclone 70 is a device that separates and collects particles such as dust contained in the combustion gas directly supplied from the boiler 20. The primary air from which particles such as dust are separated is supplied to the coal mill 10 by the forced air blower 84.

  A part of the air blown by the forced air blower 83 is supplied to the air preheater 60, and the other part is guided to the primary air supply pipe 88 via the bypass pipe 85. The bypass pipe 85 is provided in order to avoid pressure loss due to the air preheater 60 and to supply primary air with high wind pressure to the primary air supply pipe 88. By increasing the wind pressure of the primary air in the primary air supply pipe 88, the wind pressure of the primary air supplied to the coal mill 10 can be increased, and the pulverized coal can be sufficiently classified.

The operation and effect of the boiler system 100 of the present embodiment described above will be described.
According to the boiler system 100 of the present embodiment, the mixed gas containing the pulverized fuel and the primary air generated by the coal mill 10 is separated into the high concentration mixed gas and the low concentration mixed gas by the cyclone 30. Since the high-concentration mixed gas containing a large amount of pulverized fuel is used for combustion in the boiler 20, the combustion efficiency of the boiler 20 can be improved.

Moreover, since heat is exchanged between the low-concentration mixed gas containing a large amount of water evaporated from coal and water by the condenser 50, the amount of heat used for drying the coal can be recovered appropriately.
Therefore, the boiler system 100 which improved the thermal efficiency in the case of using high-moisture coal, such as lignite having a high moisture content, as fuel can be provided.

  For example, when the weight of moisture contained in the high moisture coal is 60% with respect to the weight of the high moisture coal pulverized by the coal mill 10, the total amount of the mixed gas discharged from the coal mill 10 is supplied to the boiler 20. Compare with the example that supplies. In the case of this comparative example, about 20% of the latent heat contained in the vapor evaporated from the high moisture coal is discharged into the atmosphere without being recovered.

  According to the boiler system 100 of this embodiment, the efficiency of the boiler 20 can be improved by about 10% by recovering, for example, 50% of the latent heat that is discharged into the atmosphere in the comparative example by the condenser 50. Further, by improving the efficiency of the boiler 20 by about 10%, the thermal efficiency of the entire power plant can be improved by about 3%.

  According to the boiler system 100 of the present embodiment, a part of the steam whose volume is increased by the evaporation of moisture is guided to a different path from the boiler 20. By doing in this way, it is not necessary to enlarge a pipe diameter or a boiler size so that it can respond to the volume increased by evaporation of moisture. Further, the heat contained in the low-concentration mixed gas led to a different path from the boiler 20 can be recovered and reused.

Moreover, the boiler system 100 of this embodiment is provided with the economizer 26 which performs heat exchange with the combustion gas produced | generated by combustion of the high concentration mixed gas by the boiler 100, and the water supplied from the outside. Further, the condenser 50 performs heat exchange between the low-concentration mixed gas and water supplied to the economizer 26.
By doing in this way, since the water supplied to the economizer 26 will be in the state heated previously, the thermal efficiency of the boiler system 100 can be improved.

Moreover, the boiler system 100 of this embodiment collect | recovers the pulverized fuel contained in the low concentration mixed gas isolate | separated by the cyclone 30, supplies it to the boiler 20, and condenses the low concentration mixed gas from which the pulverized fuel was collect | recovered. An electric dust collector 40 for supplying to 50 is provided.
By doing in this way, it becomes possible to use the pulverized fuel contained in the low concentration mixed gas as the fuel of the boiler 20, and the thermal efficiency of the boiler system 100 can be further improved.

  In addition, the boiler system 100 of the present embodiment performs heat exchange between the combustion gas generated by the combustion of the high-concentration mixed gas by the boiler 20 and air, and also uses the air preheated by heat exchange with the combustion gas for combustion. An air preheater 60 that supplies the boiler 20 as secondary air and a primary air supply pipe 88 that supplies the air preheated by the air preheater 60 to the forced air blower 84 are provided.

  By doing in this way, the air of the state preheated by the air preheater 60 is sent to the coal mill 10 as primary air. Therefore, the drying efficiency of coal in the coal mill 10 can be improved.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to the drawings.
The second embodiment is a modification of the first embodiment, and is the same as the first embodiment except for a case described below, and the description thereof is omitted.

  In the boiler system 100 of the first embodiment, the low-concentration mixed gas that has passed through the condenser 50 is blown by the induction fan 81 and discharged from the chimney 90. In contrast, the boiler system 200 of the second embodiment blows the low-concentration mixed gas that has passed through the condenser 50 by the induction fan 81 and guides it to the air preheater 60.

  As shown in FIG. 3, the low-concentration mixed gas that has passed through the condenser 50 is blown by the induction fan 81 and guided to the air preheater 60. The temperature of the low-concentration mixed gas guided to the air preheater 60 is lowered to about 40 to 60 ° C. due to heat exchange in the condenser 50, but the temperature is higher than air in the atmosphere. High-temperature (about 300 to 400 ° C.) combustion gas is guided to the air preheater 60. Therefore, the low concentration mixed gas is heated and guided to the primary air supply pipe 87.

Thus, the boiler system 200 of this embodiment guides the low concentration mixed gas whose temperature is higher than air in the atmosphere to the air preheater 60, preheats it, and supplies it to the coal mill 10 as primary air.
Therefore, the amount of heat contained in the low-concentration mixed gas that has passed through the condenser 50 can be reused, and the coal drying efficiency in the coal mill 10 can be further improved.

Other Embodiment
In the first embodiment, the pulverized fuel recovered by the electric dust collector 40 is supplied to the burner 25 of the boiler 20 after being mixed in the high-concentration mixed gas discharged from the cyclone 30. There may be.
For example, the pulverized fuel collected by the electrostatic precipitator 40 may be supplied to the burner 25 via a separate supply path without being mixed in the high-concentration mixed gas discharged from the cyclone 30. In this case, for example, pulverized fuel collected by the electric dust collector 40 may be mixed in the tertiary air used for combustion in the burner 25.

In the first embodiment, the electrostatic precipitator 40 is used to recover the pulverized fuel contained in the low-concentration mixed gas discharged from the cyclone 30, but other modes may be used.
For example, you may use other types of dust collectors, such as a bag fill and a ceramic filter which have a filter for filtering low concentration gas.

10 Coal mill (solid fuel grinding section)
DESCRIPTION OF SYMBOLS 11 Housing 12 Rotary table 20 Boiler 25 Burner 26 Economizer 30 Cyclone (separation part)
40 Electric dust collector (dust collector)
50 Condenser (heat exchanger)
60 Air preheater 70 Cyclone 81, 82 Induction fan 83, 84 Intrusion fan (blower)
86 Secondary air supply pipe 87,88 Primary air supply pipe (primary air supply path)
90 Chimney 100, 200 Boiler system

Claims (6)

A solid fuel pulverization unit that pulverizes the solid fuel and classifies the pulverized solid fuel to produce a finely divided fuel smaller than a predetermined particle size;
A blower for blowing primary air to the solid fuel crusher;
The mixed gas containing the fine fuel and the primary air generated by the solid fuel pulverization unit is separated into a high concentration mixed gas having a high content of the fine fuel and a low concentration mixed gas having a low content of the fine fuel. Separating part to be
A boiler that generates steam by burning the high-concentration mixed gas separated by the separation unit;
A boiler system comprising a heat exchanger that exchanges heat between the low-concentration mixed gas separated by the separation unit and another medium. An economizer that performs heat exchange between combustion gas generated by combustion of the high-concentration mixed gas by the boiler and water supplied from the outside;
The boiler system according to claim 1, wherein the heat exchanger is a condenser that performs heat exchange between the low-concentration mixed gas and water supplied to the economizer.   The pulverized fuel contained in the low-concentration mixed gas separated by the separation unit is recovered and supplied to the boiler, and the low-concentration mixed gas from which the pulverized fuel is recovered is supplied to the heat exchanger. The boiler system of Claim 1 or Claim 2 provided with a dust part. While performing heat exchange with the combustion gas produced | generated by the combustion of the said high concentration mixed gas by the said boiler, the said air preheated by the heat exchange with the said combustion gas is used as the secondary air for combustion to the said boiler An air preheater to supply,
The boiler system of any one of Claims 1-3 provided with the primary air supply path which supplies the said air preheated by the said air preheater to the said ventilation part.   The boiler system according to claim 4, wherein the air preheater preheats the low-concentration mixed gas that has passed through the heat exchanger, and supplies the low-concentration mixed gas to the blower unit through the primary air supply path. The boiler system according to any one of claims 1 to 5,
A steam turbine driven by the steam generated by the boiler;
A power generation plant comprising: a power generation device that generates power using rotational power obtained by the steam turbine.

Images