Boiler plant, plant equipment, plant connection method, and plant operation method

Abstract

We provide a boiler plant that can achieve high energy efficiency while recovering CO2 contained in the boiler's exhaust gas. [Solution] The boiler plant comprises a boiler, a CO2 recovery device for recovering CO2 contained in the exhaust gas discharged from the boiler, an exhaust gas supply line configured to supply the exhaust gas discharged from the boiler to the CO2 recovery device, and a first heat exchanger provided in the exhaust gas supply line and configured to cool the exhaust gas by performing heat exchange between water supplied to the boiler and the exhaust gas discharged from the boiler.

Description

[Technical Field]

[0001] The present disclosure relates to a boiler plant, a plant facility, a plant connection method and a plant operation method. [Background Art]

[0002] Patent Document 1 discloses a boiler plant including: a waste heat recovery boiler; an absorption tower that recovers CO₂ contained in exhaust gas from the waste heat recovery boiler; and an exhaust gas heater that heats the exhaust gas by causing heat exchange between steam extracted from the waste heat recovery boiler and the exhaust gas that has passed through the absorption tower. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2022-20324 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] Incidentally, when CO₂ contained in exhaust gas discharged from a boiler is recovered by a CO₂ recovery device, the temperature of the boiler exhaust gas tends to be higher than the temperature suitable for CO₂ recovery in the CO₂ recovery device. In such a case, if the boiler exhaust gas is cooled, CO₂ in the exhaust gas can be efficiently recovered by the CO₂ recovery device, but the energy efficiency of the plant tends to decrease due to the energy consumed for cooling the exhaust gas (for example, the power of auxiliary equipment such as a pump when cooling the exhaust gas by sprinkling cooling water into the exhaust gas using a pump or the like).

[0005] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a boiler plant, a plant facility, a plant connection method and a plant operation method that can achieve high energy efficiency while recovering CO₂ contained in boiler exhaust gas. [Means for Solving the Problem]

[0006] To achieve the above objective, a boiler plant according to at least one embodiment of this disclosure is: Boiler and, A CO2 recovery device for recovering CO2 contained in the exhaust gas discharged from the boiler, An exhaust gas supply line configured to supply the exhaust gas discharged from the boiler to the CO2 recovery device, A first heat exchanger is provided in the exhaust gas supply line and is configured to cool the exhaust gas by performing heat exchange between water supplied to the boiler and the exhaust gas discharged from the boiler. It is equipped with. [Effects of the Invention]

[0007] According to at least one embodiment of this disclosure, a boiler plant, plant equipment, a plant connection method, and a plant operation method are provided that can achieve high energy efficiency while recovering CO2 contained in the boiler exhaust gas. [Brief explanation of the drawing]

[0008] [Figure 1] This figure schematically shows the general configuration of a boiler plant 2 according to one embodiment. [Figure 2] Figure 1 is a schematic diagram illustrating an example of the detailed configuration of the waste heat recovery boiler 6 and other components shown in Figure 1. [Figure 3] This diagram schematically shows an example of the configuration provided in the exhaust gas supply line 34, exhaust gas discharge line 42, and bypass line 44 of the boiler plant 2. [Figure 4] This figure schematically shows an example of the arrangement of the first heat exchanger 62 and the second heat exchanger 64 shown in Figure 3. [Figure 5] This figure shows a modified example of the embodiment shown in Figure 3. [Modes for carrying out the invention]

[0009] Hereinafter, several embodiments of this disclosure will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described or shown in the drawings as embodiments are not intended to limit the scope of the invention, but are merely illustrative examples. For example, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" should not only strictly describe such arrangements, but also describe states of relative displacement with tolerances or angles or distances that allow for the same function to be achieved. For example, expressions such as "identical," "equal," and "homogeneous" that describe things being in an equal state not only describe a state of being strictly equal, but also describe a state in which there is a tolerance or a difference that is sufficient to achieve the same function. For example, expressions describing shapes such as squares or cylinders shall not only represent geometrically precise shapes such as squares or cylinders, but also shapes that include protrusions, chamfers, etc., to the extent that the same effect can be achieved. On the other hand, expressions such as "to possess," "to be equipped with," "to have," "to include," or "to have" a single component are not exclusive expressions that exclude the existence of other components.

[0010] (Overall configuration of the boiler plant) Figure 1 is a schematic diagram showing the general configuration of a boiler plant 2 according to one embodiment. The boiler plant 2 illustrated in Figure 1 is a gas turbine combined cycle power plant (GTCC plant) equipped with a carbon dioxide capture and storage (CCS) function.

[0011] The boiler plant 2 shown in Figure 1 includes a gas turbine generator 4, a waste heat recovery boiler 6, a steam turbine generator 8, a condenser 10, a condensate pump 12, a CO2 recovery device 16, and a chimney 17, among other things.

[0012] The gas turbine generator 4 includes a compressor 20 that compresses air to produce compressed air, a combustor 22 that burns fuel gas using the compressed air produced by the compressor 20, a turbine 24 that rotates using the combustion gas produced by the combustor 22, and a generator 26 that generates electricity driven by the turbine 24. The exhaust gas from the turbine 24 (exhaust gas from the gas turbine generator 4) is supplied to the waste heat recovery boiler 6.

[0013] The heat recovery boiler 6 uses the heat from the exhaust gas of the turbine 24 to evaporate water and generate steam. The steam turbine generator 8 includes a steam turbine 28 that is rotated by the steam generated in the heat recovery boiler 6, and a generator 26 that is driven by the steam turbine 28 to generate electricity. In the illustrated exemplary embodiment, the gas turbine generator 4 and the steam turbine generator 8 share the generator 26, and the compressor 20, turbine 24, steam turbine 28, and generator 8 are connected coaxially. In other embodiments, the gas turbine generator 4 and the steam turbine generator 8 may be located on shafts independent of each other.

[0014] The condenser 10 cools and condenses the steam that has passed through the steam turbine 28. The condenser 10 and the heat recovery boiler 6 are connected by a feedwater line 32, which is configured to supply the water (condensate) produced by the condensation of steam in the condenser 10 to the heat recovery boiler 6. The condensate pump 12 is located in the feedwater line 32 and is configured to pressurize the water produced by the condensation of steam in the condenser 10 and supply it to the heat recovery boiler 6. The heat recovery boiler 6 uses the heat from the exhaust gas of the turbine 24 to evaporate the water (feedwater) supplied from the feedwater line 32 and generate steam.

[0015] The waste heat recovery boiler 6 and the CO2 recovery device 16 are connected by an exhaust gas supply line 34, which supplies the exhaust gas discharged from the waste heat recovery boiler 6 (exhaust gas from the turbine 24, which has been used to generate steam in the waste heat recovery boiler 6) to the CO2 recovery device 16.

[0016] The CO2 recovery device 16 is configured to recover CO2 contained in exhaust gas discharged from the waste heat recovery boiler 6 (exhaust gas supplied from the exhaust gas supply line 34). In the illustrated exemplary embodiment, the CO2 recovery device 16 includes an exhaust gas cooling tower 36, an absorption tower 38, and a regeneration tower 40.

[0017] The exhaust gas cooling tower 36 cools the exhaust gas supplied from the exhaust gas supply line 34 to a temperature suitable for absorbing CO2 into an amine solution (absorbent) in the absorption tower 38, for example, 40 to 60°C. The exhaust gas cooling tower 36 may be configured to cool the exhaust gas by sprinkling cooling water into the exhaust gas supplied from the exhaust gas supply line 34 using a pump or the like.

[0018] The absorption tower 38 is configured to cause the amine solution to absorb CO2 contained in the exhaust gas that has passed through the exhaust gas cooling tower 36 (the exhaust gas cooled and temperature-reduced in the exhaust gas cooling tower 36), thereby separating CO2 from the exhaust gas. The amine solution that has absorbed CO2 in the absorption tower 38 is supplied to the regeneration tower 40. The absorption tower 38 and the chimney 17 are connected by an exhaust gas discharge line 42. The exhaust gas discharge line 42 is configured to supply the exhaust gas discharged from the absorption tower 38 after CO2 is absorbed into the amine solution in the absorption tower 38 (that is, the exhaust gas from which CO2 has been recovered by the CO2 recovery device 16 and discharged from the CO2 recovery device 16) to the chimney 17, and discharge the exhaust gas into the atmosphere through the chimney 17. In the illustrated exemplary embodiment, the boiler plant 2 includes a bypass line 44, and the bypass line 44 connects the exhaust gas supply line 34 and the exhaust gas discharge line 42 so as to bypass the CO2 recovery device 16. The exhaust gas discharged from the waste heat recovery boiler 6 and flowing into the bypass line 44 is supplied to the chimney 17 bypassing the CO2 recovery device 16 (in the illustrated example, bypassing the exhaust gas cooling tower 36 and the absorption tower 38).

[0019] The regeneration tower 40 separates CO2 from the amine solution (amine solution that has absorbed CO2) supplied from the absorption tower 38 by heating it. The CO2 separated from the amine solution in the regeneration tower 40 is transferred from the regeneration tower 40 to another location, for example, stored underground. The amine solution that has released CO2 in the regeneration tower 40 is returned to the absorption tower 38.

[0020] (An example of a detailed configuration of a heat recovery boiler, etc.) Figure 2 is a schematic diagram showing an example of the detailed configuration of the waste heat recovery boiler 6 and other components shown in Figure 1. The waste heat recovery boiler 6 shown in Figure 2 includes an economizer 46, an evaporator 48, and a superheater 50. The economizer 46 is connected to the feedwater line 32 described above. The economizer 46 is an indirect contact type heat exchanger that heats the water supplied from the feedwater line 32 by exchanging heat with the exhaust gas from the turbine 24. In the exemplary configuration shown in Figure 2, the feedwater line 32 is connected to the recirculation line 54, the first heat exchanger inlet line 55, the first heat exchanger outlet line 56, and the second heat exchanger outlet line 58, which will be described later.

[0021] The economizer 46 and the evaporator 48 are connected by a connection line 52, and a portion of the water heated in the economizer 46 (boiler water) is supplied to the evaporator 48 through the connection line 52. The boiler plant 2 also includes a recirculation line 54 that branches off from the connection line 52 and is configured to connect to a feedwater line 32. The recirculation line 54 is configured to return a portion of the boiler water heated in the economizer 46 to the feedwater line 32. In a typical boiler plant 2, the recirculation line 54 is provided to maintain the feedwater temperature on the inlet side of the economizer 46 above the dew point temperature of the exhaust gas in order to suppress corrosion of the economizer 46 caused by the condensation of moisture contained in the exhaust gas. The recirculation line 54 is equipped with a recirculation pump 57, which is configured to pressurize a portion of the boiler water heated in the economizer 46 (the water flowing through the recirculation line 54) and supply it to the feedwater line 32. Furthermore, the boiler plant 2 is further equipped with a second heat exchanger inlet line 60, which will be described later, branching off from the recirculation line 54.

[0022] The evaporator 48 generates steam by exchanging heat between the water supplied from the connection line 52 (water heated in the economizer 46) and the exhaust gas from the turbine 24, thereby heating and evaporating the water.

[0023] The evaporator 48 and the superheater 50 are connected by a connecting line 53, and the steam generated in the evaporator 48 is supplied to the superheater 50 through the connecting line 53.

[0024] The superheater 50 generates superheated steam by exchanging heat between the steam supplied from the connection line 53 (steam generated in the evaporator 48) and the exhaust gas from the turbine 24. The superheated steam generated in the superheater 50 is supplied to the steam turbine 28 and used to generate electricity in the steam turbine generator 8.

[0025] (1st heat exchanger) Figure 3 is a schematic diagram showing an example of the configuration provided in the exhaust gas supply line 34, exhaust gas discharge line 42, and bypass line 44 of the boiler plant 2 described using Figures 1 and 2.

[0026] As shown in Figure 3, the boiler plant 2 includes an indirect contact type first heat exchanger 62 installed in the exhaust gas supply line 34. As shown in Figures 2 and 3, the first heat exchanger inlet line 55 connects the water inlet 62a of the first heat exchanger 62 to the feedwater line 32, and is configured to supply water flowing through the feedwater line 32 to the first heat exchanger 62. The first heat exchanger outlet line 56 connects the water outlet 62b of the first heat exchanger 62 to the feedwater line 32, and is configured to supply water heated in the first heat exchanger 62 to the feedwater line 32. The exhaust gas supply line 34 and the first heat exchanger 62 constitute the plant equipment 63.

[0027] The first heat exchanger 62 cools the exhaust gas discharged from the heat recovery boiler 6 by exchanging heat between the water supplied to the heat recovery boiler 6 (water flowing through the feedwater line 32) and the exhaust gas discharged from the heat recovery boiler 6 (exhaust gas flowing through the exhaust gas supply line 34). The first heat exchanger 62 may be, for example, a heat transfer tube installed inside the duct that constitutes the exhaust gas supply line 34. In this case, the exhaust gas flowing through the duct that constitutes the exhaust gas supply line 34 (exhaust gas discharged from the heat recovery boiler 6) and the water flowing through the heat transfer tube that constitutes the first heat exchanger 62 (water supplied to the heat recovery boiler 6) exchange heat via the heat transfer tube, thereby cooling the exhaust gas discharged from the heat recovery boiler 6 and heating the water supplied to the heat recovery boiler 6.

[0028] The exhaust gas cooled in the first heat exchanger 62 is supplied to the exhaust gas cooling tower 36 via the exhaust gas supply line 34, where it is further cooled. For example, if the temperature of the exhaust gas at the exhaust gas outlet of the waste heat recovery boiler 6 is about 80°C, the first heat exchanger 62 may cool the exhaust gas to about 60°C (e.g., 55°C to 65°C), and the exhaust gas cooling tower 36 may cool the exhaust gas to about 45°C (e.g., 40°C to 50°C). This allows CO2 to be efficiently absorbed into the amine solution in the absorption tower 38.

[0029] Here, we will explain the effects obtained by providing the first heat exchanger 62. According to the boiler plant 2 described above, the first heat exchanger 62 provided in the exhaust gas supply line 34 can cool the exhaust gas by exchanging heat between the water supplied to the heat recovery boiler 6 and the exhaust gas discharged from the heat recovery boiler 6. This allows the temperature of the exhaust gas to be brought closer to a temperature suitable for CO2 recovery in the CO2 recovery device 16 (in the above embodiment, a temperature suitable for efficiently absorbing CO2 into the amine solution in the absorption tower 38). As a result, the energy consumed to cool the exhaust gas in the exhaust gas cooling tower 36 (for example, the power of auxiliary equipment such as pumps when cooling water is sprayed onto the exhaust gas in the exhaust gas cooling tower using pumps, etc.) and the amount of cooling water used to cool the exhaust gas in the exhaust gas cooling tower 36 (makeup water amount and treated water amount) can be reduced. In addition, since the water heated by heat exchange with the exhaust gas in the first heat exchanger 62 is supplied to the heat recovery boiler 6, the energy required to evaporate the water in the heat recovery boiler 6 can be reduced. Therefore, it is possible to achieve high energy efficiency in the boiler plant 2 while recovering CO2 contained in the exhaust gas of the waste heat recovery boiler 6.

[0030] Furthermore, as shown in Figure 2, the point Pb where the first heat exchanger outlet line 56 and the feedwater line 32 connect is downstream of the point Pa where the first heat exchanger inlet line 55 and the feedwater line 32 connect. Therefore, it is possible to avoid the water heated in the first heat exchanger 62 flowing back into the first heat exchanger 62 through the first heat exchanger inlet line 55 after being supplied to the feedwater line 32 via the first heat exchanger outlet line 56. As a result, the exhaust gas can be efficiently cooled in the first heat exchanger 62.

[0031] Furthermore, as shown in Figure 2, the connection point Pa between the first heat exchanger inlet line 55 and the feedwater line 32 is downstream of the condensate pump 12 in the feedwater line 32. Therefore, water generated by the condensation of steam in the condenser 10 can be supplied to the first heat exchanger 62 using the condensate pump 12. As a result, a highly energy-efficient boiler plant 2 can be realized with a simple configuration.

[0032] (Second heat exchanger) Furthermore, as shown in Figure 3, the boiler plant 2 is equipped with an indirect contact type second heat exchanger 64 located in the exhaust gas discharge line 42. As shown in Figures 2 and 3, the second heat exchanger inlet line 60 branches off from the recirculation line 54 and connects to the water inlet 64a of the second heat exchanger 64, and is configured to supply the water flowing through the recirculation line 54 (boiler water heated in the economizer 46) to the second heat exchanger 64. In addition, the second heat exchanger outlet line 58 connects the water outlet 64b of the second heat exchanger 64 to the feedwater line 32, and is configured to supply the water cooled in the second heat exchanger 64 to the feedwater line 32.

[0033] The second heat exchanger 64 heats the exhaust gas discharged from the absorption tower 38 by exchanging heat between the boiler water of the waste heat recovery boiler 6 (boiler water discharged from the economizer 46) and the exhaust gas discharged from the absorption tower 38 (exhaust gas discharged from the CO2 recovery device 16 and flowing through the exhaust gas discharge line 42). The second heat exchanger 64 may be, for example, a heat transfer tube installed inside the duct that constitutes the exhaust gas discharge line 42. In this case, the exhaust gas flowing through the duct that constitutes the exhaust gas discharge line 42 (exhaust gas discharged from the absorption tower 38) and the water flowing through the heat transfer tube that constitutes the second heat exchanger 64 (boiler water heated in the economizer 46) exchange heat via the heat transfer tube, thereby heating the exhaust gas discharged from the absorption tower 38 and cooling the water supplied to the waste heat recovery boiler 6. The exhaust gas heated in the second heat exchanger 64 is supplied to the chimney 17 through the exhaust gas discharge line 42 and released into the atmosphere from the chimney 17.

[0034] Here, we will explain the effects obtained by providing the second heat exchanger 64. If the exhaust gas, cooled to a temperature suitable for CO2 recovery, is released directly into the atmosphere after CO2 recovery in the CO2 recovery device, there is a concern that visible smoke (white smoke) will be generated when the exhaust gas is released into the atmosphere from the chimney 17 due to condensation of water vapor in the exhaust gas. In this regard, according to the boiler plant 2 described above, by using the boiler water of the waste heat recovery boiler 6 (boiler water discharged from the economizer 46 in the above embodiment) in the second heat exchanger 64 to heat the exhaust gas to a temperature above (for example, 80°C or higher) that can suppress the generation of the white smoke. As a result, the generation of white smoke can be suppressed when the exhaust gas of the waste heat recovery boiler 6 is released into the atmosphere.

[0035] Furthermore, as shown in Figure 2, the point Pc where the second heat exchanger outlet line 58 and the feedwater line 32 connect is downstream of the point Pa where the first heat exchanger inlet line 55 and the feedwater line 32 connect. Therefore, it is possible to avoid the relatively high temperature water (for example, water above 80°C) that exits the second heat exchanger 64 flowing into the first heat exchanger 62 through the first heat exchanger inlet line 55 after being supplied to the feedwater line 32 via the second heat exchanger outlet line 58. As a result, the exhaust gas can be efficiently cooled in the first heat exchanger 62.

[0036] Furthermore, as shown in Figure 2, the connection point Pd between the second heat exchanger inlet line 60 and the recirculation line 54 is downstream of the recirculation pump 57 in the recirculation line 54. Therefore, boiler water from the waste heat recovery boiler 6 can be supplied to the second heat exchanger 64 using the recirculation pump 57. As a result, an energy-efficient boiler plant 2 can be realized with a simple configuration.

[0037] (Triple damper) As shown in Figure 3, if we define the position where the bypass line 44 and the exhaust gas supply line 34 connect as the first position P1, and the position where the bypass line 44 and the exhaust gas discharge line 42 connect as the second position P2, the boiler plant 2 further includes a first damper 65 provided on the bypass line 44, a second damper 66 provided downstream of the first position P1 on the exhaust gas supply line 34, and a third damper 67 provided upstream of the second position P2 on the exhaust gas discharge line 42.

[0038] In the embodiment shown in Figure 3, by closing the first damper 65 and opening the second damper 66 and the third damper 67, CO2 contained in the exhaust gas of the heat recovery boiler 6 can be recovered by the CO2 recovery device 16 before being released into the atmosphere, and high energy efficiency of the boiler plant 2 can be achieved while suppressing the white smoke mentioned above. Alternatively, by opening the first damper 65 and closing the second damper 66 and the third damper 67, the exhaust gas of the heat recovery boiler 6 can be released into the atmosphere without passing through the CO2 recovery device 16. In this way, by providing the first damper 65, the second damper 66 and the third damper 67, the operation of the boiler plant 2 can be continued even when the CO2 recovery device 16 is shut down for inspection or other reasons. Furthermore, the boiler plant 2 can be flexibly operated according to the need to recover CO2 from the exhaust gas of the heat recovery boiler 6.

[0039] Furthermore, in the embodiment shown in Figure 3, since the second damper 66 is located upstream of the first heat exchanger 62 in the exhaust gas supply line 34, when the second damper 66 is closed, exhaust gas is no longer supplied from the exhaust gas supply line 34 to the first heat exchanger 62. Therefore, when the boiler plant 2 is operated with the second damper 66 closed and the first damper 65 open, compared to the case where the second damper 66 is located downstream of the first heat exchanger 62 in the exhaust gas supply line 34, it is possible to avoid exhaust gas flowing into and accumulating in the first heat exchanger 62, thereby suppressing the occurrence of corrosion and other issues in the first heat exchanger 62.

[0040] Furthermore, in the embodiment shown in Figure 3, since the third damper 67 is located downstream of the second heat exchanger 64 in the exhaust gas discharge line 42, when the boiler plant 2 is operated with the third damper 67 closed and the first damper 65 open, compared to the case where the third damper 67 is located upstream of the second heat exchanger 64 in the exhaust gas discharge line 42, it is possible to avoid exhaust gas flowing into and accumulating in the second heat exchanger 64, thereby suppressing the occurrence of corrosion and other issues in the second heat exchanger 64.

[0041] Furthermore, in the embodiment shown in Figure 3, the boiler plant 2 further includes a water spraying device 68 configured to spray water onto the first heat exchanger 62 from the upstream side of the first heat exchanger 62 in the exhaust gas supply line 34. The water spraying device 68 may include a plurality of water spraying nozzles 69 (e.g., spray nozzles) provided on the upstream side of the first heat exchanger 62 in the exhaust gas supply line 34.

[0042] In this way, by spraying water onto the first heat exchanger 62 from the upstream side of the first heat exchanger 62 in the exhaust gas supply line 34, substances that cause corrosion (such as Cl) can be removed from the heat transfer surface of the first heat exchanger 62, and the heat transfer characteristics of the first heat exchanger 62 can be improved. The water spraying may be performed continuously or intermittently.

[0043] (An example of a configuration supporting the first and second heat exchangers) Figure 4 is a schematic diagram showing an example of the arrangement of the first heat exchanger 62 and the second heat exchanger 64 shown in Figure 3. In some embodiments, the boiler plant 2 may include a frame 70 for supporting a first heat exchanger 62 and a second heat exchanger 64. In the exemplary embodiment shown in Figure 4, the first heat exchanger 62 and the second heat exchanger 64 are supported by the same frame 70.

[0044] As shown in Figure 4, the frame 70 includes a plurality of columns 72 extending vertically and a plurality of beams 74 extending horizontally to connect the plurality of columns 72. In the exemplary configuration shown in Figure 4, the second heat exchanger 64 is located above the first heat exchanger 62. The plurality of beams 74 includes a plurality of beams 74a located at a first height h1 and a plurality of beams 74b located at a second height h2, which is higher than the first height h1. The heat transfer tubes constituting the first heat exchanger 62 are suspended by a plurality of suspension rods 76a from the plurality of beams 74a located at the first height h1, and the heat transfer tubes constituting the second heat exchanger 64 are suspended by a plurality of suspension rods 76b from a plurality of beams 74b located at the second height h2.

[0045] According to the embodiment shown in Figure 4, by placing the second heat exchanger 64, which is located downstream of the first heat exchanger 62 in the exhaust gas flow direction of the waste heat recovery boiler 6, above the first heat exchanger 62, the installation area can be reduced compared to when the first heat exchanger 62 and the second heat exchanger 64 are installed in parallel on the same plane (ground). In addition, the ducts (exhaust gas supply line 34, exhaust gas discharge line 42, bypass line 44) and dampers (first damper 65, second damper 66, third damper 67) connecting each device (waste heat recovery boiler 6, first heat exchanger 62, second heat exchanger 64, CO2 recovery device 16, chimney 17) can be efficiently arranged.

[0046] According to the embodiment shown in Figure 4, since the first heat exchanger 62 and the second heat exchanger 64 are supported by the same frame 70, the first heat exchanger 62 and the second heat exchanger 64 can be supported with a simple configuration. In addition, it is possible to support a portion of the ducts (exhaust gas supply line 34, exhaust gas discharge line 42, bypass line 44) connecting each device (exhaust heat recovery boiler 6, first heat exchanger 62, second heat exchanger 64, CO2 recovery device 16, chimney 17) with the same frame 70 (for example, the connection between the first heat exchanger 62 and the second heat exchanger 64), thereby reducing the number of necessary structures.

[0047] This disclosure is not limited to the embodiments described above, but also includes modified forms of the embodiments described above, as well as forms that combine these forms as appropriate.

[0048] For example, in the embodiment shown in Figure 1, a GTCC plant is given as an example of a boiler plant, but in other embodiments, the boiler plant may be a plant other than a GTCC plant, for example, a steam power plant (a power plant that generates steam by burning fuel in a boiler and uses that steam to generate electricity with a steam turbine generator), or an IGCC (Integrated Gasification Combined Cycle) power plant. Furthermore, it may even be a boiler plant for steam supply that does not generate electricity.

[0049] For example, in the embodiment shown in Figure 1, the CO2 recovery device 16 was configured to separate CO2 from the exhaust gas by absorbing CO2 into an amine solution. However, in other embodiments, the CO2 recovery device 16 may be a physical absorption type CO2 recovery device configured to physically absorb CO2 into a solvent such as methanol, or a membrane separation type CO2 recovery device configured to separate carbon dioxide from the exhaust gas using a separation membrane. Even when a physical absorption type CO2 recovery device is provided, the CO2 absorption capacity of the solvent in the CO2 recovery device can be increased while achieving high energy efficiency in the boiler plant by cooling the exhaust gas using the first heat exchanger described above. Similarly, even when a membrane separation type CO2 recovery device is provided, the CO2 can be recovered while recovering CO2 by allowing the separation membrane to exhibit appropriate membrane performance by cooling the exhaust gas using the first heat exchanger described above.

[0050] For example, in the embodiment shown in Figure 3, the second damper 66 was located upstream of the first heat exchanger 62 in the exhaust gas supply line 34. However, in other embodiments, for example, as shown in Figure 5, the second damper 66 may be located downstream of the first heat exchanger 62 in the exhaust gas supply line 34.

[0051] Furthermore, in the embodiment shown in Figure 3, the third damper 67 was located downstream of the second heat exchanger 64 in the exhaust gas discharge line 42. However, in other embodiments, for example, as shown in Figure 5, the third damper 67 may be located upstream of the second heat exchanger 64 in the exhaust gas discharge line 42.

[0052] Furthermore, in the embodiment shown in Figure 4, the heat transfer tubes constituting the first heat exchanger 62 are suspended by a plurality of suspension rods 76a from a plurality of beams 74a located at a first height h1, and the heat transfer tubes constituting the second heat exchanger 64 are suspended by a plurality of suspension rods 76b from a plurality of beams 74b located at a second height h2. However, in other embodiments, the heat transfer tubes constituting the first heat exchanger 62 and the heat transfer tubes constituting the second heat exchanger 64 may be suspended by a plurality of suspension rods from the same beam.

[0053] Furthermore, in some embodiments, when the boiler plant 2 described above is manufactured by connecting a CO2 recovery device to an existing boiler plant, the first heat exchanger 62 may be incorporated into the exhaust gas supply line 34 when manufacturing the exhaust gas supply line 34, and the second heat exchanger 64 may be incorporated into the exhaust gas discharge line 42 when manufacturing the exhaust gas discharge line 42.

[0054] The contents described in each of the above embodiments can be understood, for example, as follows:

[0055] [1] A boiler plant according to at least one embodiment of the present disclosure (e.g., boiler plant 2 described above) A boiler (for example, the waste heat recovery boiler 6 mentioned above), A CO2 recovery device (for example, the CO2 recovery device 16 described above) for recovering CO2 contained in the exhaust gas discharged from the boiler, An exhaust gas supply line (for example, the exhaust gas supply line 34 described above) configured to supply the exhaust gas discharged from the boiler to the CO2 recovery device, A first heat exchanger (for example, the first heat exchanger 62 described above) is provided in the exhaust gas supply line and is configured to cool the exhaust gas by performing heat exchange between the water supplied to the boiler and the exhaust gas discharged from the boiler. and, It is equipped with.

[0056] According to the boiler plant described in [1] above, the exhaust gas can be cooled by exchanging heat between the water supplied to the boiler and the exhaust gas discharged from the boiler in the first heat exchanger installed in the exhaust gas supply line, thereby bringing the temperature of the exhaust gas closer to a temperature suitable for CO2 recovery in the CO2 recovery device. In addition, since the water heated by heat exchange with the exhaust gas in the first heat exchanger is supplied to the boiler, the energy required to evaporate the water in the boiler can be reduced. As a result, high energy efficiency of the boiler plant can be achieved while recovering CO2 contained in the boiler's exhaust gas.

[0057] [2] In some embodiments, in the boiler plant described in [1] above, A water supply line (for example, the water supply line 32 described above) configured to supply the water to the boiler, A first heat exchanger outlet line (for example, the first heat exchanger outlet line 56 described above) is configured to connect the water outlet of the first heat exchanger to the water supply line and to supply the water heated in the first heat exchanger to the water supply line, It is further equipped with [this feature].

[0058] According to the boiler plant described in [2] above, the water heated by heat exchange with the exhaust gas in the first heat exchanger is supplied to the feedwater line via the outlet line of the first heat exchanger and then supplied to the boiler via the feedwater line. This reduces the energy required to evaporate the water in the boiler. As a result, high energy efficiency can be achieved in the boiler plant while recovering CO2 contained in the boiler's exhaust gas.

[0059] [3] In some embodiments, in the boiler plant described in [2] above, The first heat exchanger further comprises a first heat exchanger inlet line (for example, the first heat exchanger inlet line 55 described above) configured to connect the water inlet of the first heat exchanger to the water supply line and to supply the water flowing through the water supply line to the first heat exchanger, The location where the first heat exchanger outlet line and the feedwater line connect (for example, location Pb described above) is downstream of the location where the first heat exchanger inlet line and the feedwater line connect (for example, location Pa described above) in the feedwater line.

[0060] According to the boiler plant described in [3] above, the point where the outlet line of the first heat exchanger connects to the feedwater line is downstream of the point where the inlet line of the first heat exchanger connects to the feedwater line. Therefore, it is possible to avoid the water heated in the first heat exchanger flowing back into the first heat exchanger through the inlet line after being supplied to the feedwater line. As a result, the exhaust gas can be efficiently cooled in the first heat exchanger.

[0061] [4] In some embodiments, in the boiler plant described in [3] above, A steam turbine (for example, the steam turbine 28 described above) configured to rotate using steam generated in the boiler, A condenser (for example, the condenser 10 described above) for condensing the steam that has passed through the steam turbine, A condensate pump (for example, the condensate pump 12 described above) for supplying the water generated by the condensation of steam in the condenser to the boiler, Equipped with, The aforementioned water supply line is configured to connect the condenser and the boiler. The location where the first heat exchanger inlet line and the feedwater line connect (for example, the location Pa described above) is downstream of the condensate pump in the feedwater line.

[0062] According to the boiler plant described in [4] above, the connection point between the inlet line of the first heat exchanger and the feedwater line is downstream of the condensate pump in the feedwater line. Therefore, water generated by the condensation of steam in the condenser can be supplied to the first heat exchanger using the condensate pump. As a result, an energy-efficient boiler plant can be realized with a simple configuration.

[0063] [5] In some embodiments, in the boiler plant described in any of [1] to [4] above, The CO2 recovery device further includes an exhaust gas cooling tower (for example, the exhaust gas cooling tower 36 described above) for further cooling the exhaust gas cooled by the first heat exchanger.

[0064] According to the boiler plant described in [5] above, the exhaust gas can be cooled in the first heat exchanger using the water supplied to the boiler, thus reducing the energy consumed for cooling the exhaust gas in the exhaust gas cooling tower (for example, the power of auxiliary equipment such as pumps when cooling water is sprayed into the exhaust gas in the exhaust gas cooling tower using pumps, etc.), and enabling high energy efficiency for the boiler plant. In addition, the amount of cooling water used for cooling the exhaust gas in the exhaust gas cooling tower (makeup water amount and treated water amount) can be reduced.

[0065] [6] In some embodiments, in the boiler plant described in [5] above, The CO2 recovery device further includes an absorption tower (for example, the absorption tower 38 described above) configured to absorb the CO2 contained in the exhaust gas cooled by the exhaust gas cooling tower into an amine solution.

[0066] According to the boiler plant described in [6] above, by cooling the exhaust gas to a temperature suitable for CO2 absorption by amines using the first heat exchanger and the exhaust gas cooling tower, it is possible to recover CO2 contained in the boiler exhaust gas while achieving high energy efficiency for the boiler plant.

[0067] [7] In some embodiments, in a boiler plant described in any of [1] to [6] above, An exhaust gas discharge line (for example, the exhaust gas discharge line 42 described above) for releasing the exhaust gas, which has been recovered by the CO2 recovery device and discharged from the CO2 recovery device, into the atmosphere, A second heat exchanger (for example, the second heat exchanger 64 described above) is provided in the exhaust gas discharge line and is configured to heat the exhaust gas by performing heat exchange between the boiler water discharged from the boiler and the exhaust gas discharged from the CO2 recovery device, It is further equipped with [this feature].

[0068] If exhaust gas that has been cooled to a temperature suitable for CO2 recovery and from which CO2 has been recovered by a CO2 recovery device is released directly into the atmosphere, there is a concern that white smoke will be generated when the exhaust gas is released into the atmosphere. In this regard, according to the boiler plant described in [7] above, the exhaust gas can be heated in the second heat exchanger using the boiler water to heat the exhaust gas to a temperature (for example, 80°C or higher) that can suppress the generation of the above-mentioned white smoke. This makes it possible to suppress the generation of white smoke when the boiler exhaust gas is released into the atmosphere.

[0069] [8] In some embodiments, in the boiler plant described in [7] above, The boiler is equipped with an economizer (for example, the economizer 46 described above), The second heat exchanger is configured to perform heat exchange between the boiler water discharged from the economizer and the exhaust gas discharged from the CO2 recovery device.

[0070] According to the boiler plant described in [8] above, the exhaust gas discharged from the CO2 recovery device is heated using boiler water discharged from the economizer, thereby heating the exhaust gas temperature in the second heat exchanger to a temperature (for example, 80°C or higher) that can suppress the generation of the white smoke. This makes it possible to suppress the generation of white smoke when the boiler exhaust gas is released into the atmosphere.

[0071] [9] In some embodiments, in the boiler plant described in [8] above, The aforementioned boiler plant is A water supply line (for example, the water supply line 32 described above) configured to supply the water to the boiler, A recirculation line (for example, the recirculation line 54 described above) is configured to return the boiler water heated by the carbon saver back to the water supply line, A second heat exchanger inlet line (for example, the second heat exchanger inlet line 60 described above) is configured to branch off from the recirculation line and connect to the boiler water inlet of the second heat exchanger, and to supply the boiler water heated by the economizer to the second heat exchanger, It is further equipped with [this feature].

[0072] In a typical boiler plant, the above-mentioned recirculation line is provided to maintain the feedwater temperature at the inlet of the economizer above the dew point temperature of the exhaust gas in order to suppress corrosion of the economizer caused by the condensation of moisture contained in the exhaust gas. Therefore, by providing the second heat exchanger inlet line described in [9] above, boiler water heated in the economizer can be supplied to the second heat exchanger. This suppresses corrosion of the second heat exchanger and also heats the exhaust gas.

[0073]

[10] In some embodiments, in the boiler plant described in [9] above, The recirculation line is provided with a recirculation pump (for example, the recirculation pump 57 described above) for returning the boiler water heated by the economizer back to the water supply line. The location where the second heat exchanger inlet line and the recirculation line connect (for example, the location Pd described above) is downstream of the recirculation pump in the recirculation line.

[0074] In a typical boiler plant, the above-mentioned recirculation line and recirculation pump are provided to maintain the feedwater temperature on the inlet side of the economizer above the dew point temperature of water in order to suppress corrosion of the economizer caused by gas condensation. Therefore, as described in

[10] above, by setting the connection point between the inlet line of the second heat exchanger and the recirculation line downstream of the recirculation pump in the recirculation line, boiler water from the economizer can be supplied to the second heat exchanger using the recirculation pump. This makes it possible to realize an energy-efficient boiler plant with a simple configuration while suppressing the generation of white smoke when the boiler exhaust gas is released into the atmosphere.

[0075]

[11] In some embodiments, in the boiler plant described in any of [7] to

[10] above, The system further includes a bypass line (for example, the bypass line 44 described above) that connects the exhaust gas supply line and the exhaust gas discharge line so as to bypass the CO2 recovery device.

[0076] According to the boiler plant described in

[11] above, if it is not necessary to use a CO2 recovery device, the boiler exhaust gas can be released into the atmosphere without passing through a CO2 recovery device by flowing it through a bypass line.

[0077]

[12] In some embodiments, in the boiler plant described in

[11] above, If we define the position where the bypass line and the exhaust gas supply line are connected as the first position, and the position where the bypass line and the exhaust gas discharge line are connected as the second position, The boiler plant further comprises a first damper (for example, the first damper 65 described above) provided in the bypass line, a second damper (for example, the second damper 66 described above) provided downstream of the first position in the exhaust gas supply line, and a third damper (for example, the third damper 67 described above) provided upstream of the second position in the exhaust gas discharge line.

[0078] According to the boiler plant described in

[12] above, by closing the first damper and opening the second and third dampers, CO2 contained in the boiler exhaust gas can be recovered by a CO2 recovery device before being released into the atmosphere, and high energy efficiency of the boiler plant can be achieved while suppressing the white smoke mentioned above. Furthermore, by opening the first damper and closing the second and third dampers, the boiler exhaust gas can be released into the atmosphere without passing through the CO2 recovery device. In this way, by providing the first damper, second damper, and third damper, the boiler plant can continue to operate even when the CO2 recovery device is shut down for inspection or other reasons. In addition, the boiler plant can be operated flexibly according to the need to recover CO2 from the boiler exhaust gas.

[0079]

[13] In some embodiments, in the boiler plant described in

[12] above, The second damper is located upstream of the first heat exchanger in the exhaust gas supply line.

[0080] According to the boiler plant described in

[13] above, when the second damper is closed, exhaust gas is no longer supplied from the exhaust gas supply line to the first heat exchanger. Therefore, when the boiler plant is operated with the second damper closed and the first damper open, compared to the case where the second damper is located downstream of the first heat exchanger in the exhaust gas supply line, it is possible to avoid exhaust gas flowing into and accumulating in the first heat exchanger, thereby suppressing the occurrence of corrosion and other issues in the first heat exchanger.

[0081]

[14] In some embodiments, in the boiler plant described in

[12] above, The third damper is located downstream of the second heat exchanger in the exhaust gas discharge line.

[0082] According to the boiler plant described in

[14] above, when the boiler plant is operated with the third damper closed and the first damper open, compared to the case where the third damper is located upstream of the second heat exchanger in the exhaust gas discharge line, it is possible to avoid exhaust gas flowing into and accumulating in the second heat exchanger 64, thereby suppressing the occurrence of corrosion and the like in the second heat exchanger 64.

[0083]

[15] In some embodiments, in the boiler plant described in any of [1] to

[14] above, The system further includes a watering device (for example, the watering device 68 described above) configured to spray water onto the first heat exchanger from the upstream side of the first heat exchanger in the exhaust gas supply line.

[0084] According to the boiler plant described in

[15] above, by spraying water onto the first heat exchanger from the upstream side of the first heat exchanger in the exhaust gas supply line, corrosive substances (such as Cl) can be removed from the heat transfer surface of the first heat exchanger, and the heat transfer characteristics can be improved.

[0085]

[16] In some embodiments, in the boiler plant described in any of [7] to

[14] above, The second heat exchanger is installed above the first heat exchanger.

[0086] According to the boiler plant described in

[16] above, by placing the second heat exchanger, which is located downstream of the first heat exchanger in the direction of the boiler's exhaust gas flow, above the first heat exchanger, the installation area can be reduced compared to when the first and second heat exchangers are placed in parallel on the same plane (ground). In addition, ducts and dampers connecting each device (e.g., exhaust heat recovery boiler, first heat exchanger, second heat exchanger, CO2 recovery device, and chimney, etc.) can be efficiently arranged.

[0087]

[17] In some embodiments, in the boiler plant described in any of

[16] above, The first heat exchanger and the second heat exchanger are supported by the same frame (for example, the frame 70 described above).

[0088] According to the boiler plant described in

[17] above, the first and second heat exchangers can be supported with a simple configuration. Furthermore, a portion of the ducts connecting each device (e.g., the waste heat recovery boiler, the first heat exchanger, the second heat exchanger, the CO2 recovery device, and the chimney) (e.g., the connection between the first and second heat exchangers) can be supported by the same frame, thereby reducing the number of necessary structures.

[0089]

[18] A plant facility according to at least one embodiment of the present disclosure (e.g., the plant facility 63 described above) An exhaust gas supply line (for example, the exhaust gas supply line 34 described above) is configured to supply exhaust gas discharged from a boiler (for example, the exhaust heat recovery boiler 6 described above) to a CO2 recovery device (for example, the CO2 recovery device 16 described above) for recovering CO2 contained in the exhaust gas discharged from the boiler, A first heat exchanger (for example, the first heat exchanger 62 described above) is provided in the exhaust gas supply line and is configured to cool the exhaust gas by performing heat exchange between the water supplied to the boiler and the exhaust gas discharged from the boiler, It is equipped with.

[0090] According to the plant equipment described in

[18] above, the exhaust gas can be cooled by exchanging heat between the water supplied to the boiler and the exhaust gas discharged from the boiler in the first heat exchanger installed in the exhaust gas supply line, thereby bringing the temperature of the exhaust gas closer to a temperature suitable for CO2 recovery in the CO2 recovery device. In addition, since the water heated by heat exchange with the exhaust gas in the first heat exchanger is supplied to the boiler, the energy required to evaporate the water in the boiler can be reduced. As a result, high energy efficiency can be achieved in the boiler plant including the plant equipment while recovering CO2 contained in the boiler exhaust gas.

[0091]

[19] A plant connection method according to at least one embodiment of the present disclosure is A method for connecting a CO2 recovery device to a boiler plant for recovering CO2 contained in exhaust gas discharged from a boiler (for example, the aforementioned waste heat recovery boiler 6), The steps include manufacturing an exhaust gas supply line (for example, the exhaust gas supply line 34 described above) for supplying the exhaust gas discharged from the boiler to the CO2 recovery device (for example, the CO2 recovery device 16 described above), In the step of manufacturing the exhaust gas supply line, a first heat exchanger (for example, the first heat exchanger 62 described above) that cools the exhaust gas by performing heat exchange between water supplied to the boiler and the exhaust gas discharged from the boiler is incorporated into the exhaust gas supply line, It is equipped with.

[0092] According to the plant connection method described in

[19] above, the exhaust gas can be cooled by exchanging heat between the water supplied to the boiler and the exhaust gas discharged from the boiler in the first heat exchanger incorporated into the exhaust gas supply line, thereby bringing the temperature of the exhaust gas closer to a temperature suitable for CO2 recovery in the CO2 recovery device. In addition, since the water heated by heat exchange with the exhaust gas in the first heat exchanger is supplied to the boiler, the energy required to evaporate the water in the boiler can be reduced. As a result, high energy efficiency of the boiler plant can be achieved while recovering CO2 contained in the boiler's exhaust gas.

[0093]

[20] A plant operation method according to at least one embodiment of the present disclosure is The exhaust gas supply step involves supplying the exhaust gas discharged from the boiler (for example, the exhaust heat recovery boiler 6 described above) to a CO2 recovery device (for example, the CO2 recovery device 16 described above) for recovering CO2 contained in the exhaust gas discharged from the boiler, The exhaust gas supply step includes an exhaust gas cooling step in which the exhaust gas is cooled by performing a heat exchange between water supplied to the boiler and the exhaust gas discharged from the boiler.

[0094] According to the plant operation method described in

[20] above, the exhaust gas can be cooled by exchanging heat between the water supplied to the boiler and the exhaust gas discharged from the boiler, thereby bringing the temperature of the exhaust gas closer to a temperature suitable for CO2 recovery in the CO2 recovery device. In addition, since the water heated by the heat exchange with the exhaust gas is supplied to the boiler, the energy required to evaporate the water in the boiler can be reduced. As a result, high energy efficiency of the plant can be achieved while recovering CO2 contained in the boiler's exhaust gas. [Explanation of Symbols]

[0095] 2: Boiler plant 4: Gas turbine generator 6: Waste heat recovery boiler 8: Steam turbine generator 10: Condenser 12: Condensate pump 17: Chimney 20: Compressor 22: Combustor 24: Turbine 26: Generator 28: Steam Turbine 32: Water supply line 34: Exhaust gas supply line 36: Exhaust gas cooling tower 38: Absorption Tower 40: Regeneration Tower 42: Exhaust gas discharge line 44: Bypass Line 46: Economizer 48: Evaporator 50:Superheater 52: Connection line 53: Connection line 54: Recirculation Line 55: Line on the inlet side of the first heat exchanger 56: First heat exchanger outlet line 57: Recirculation pump 58: Second heat exchanger outlet line 60: Second heat exchanger inlet line 62: 1st heat exchanger 62a: Entrance 62b:Exit 63 Plant Equipment 64:Second heat exchanger 64a: Entrance 64b:Exit 65: First Dump 66: Second Dumper 67: Third Dump 68: Sprinkler system 70: Frame 72: Pillar 74: Beam 74a: Beam 74b: Beam 76a: Hanging rod 76b: Hanging rod

Claims

1. Boiler and, CO contained in the exhaust gas discharged from the boiler ２ CO2 for recovery ２ Recovery device and The exhaust gas discharged from the boiler is the CO ２ An exhaust gas supply line configured to supply to a recovery device, A first heat exchanger is provided in the exhaust gas supply line and is configured to cool the exhaust gas by performing heat exchange between water supplied to the boiler and the exhaust gas discharged from the boiler. A boiler plant equipped with [a specific feature / feature].

2. A water supply line configured to supply the water to the boiler, A first heat exchanger outlet line is configured to connect the water outlet of the first heat exchanger to the water supply line and to supply the water heated in the first heat exchanger to the water supply line, The boiler plant according to claim 1, further comprising the following:

3. The first heat exchanger further comprises a first heat exchanger inlet line configured to connect the water inlet of the first heat exchanger to the water supply line and to supply the water flowing through the water supply line to the first heat exchanger, The boiler plant according to claim 2, wherein the connection point between the first heat exchanger outlet line and the feedwater line is downstream of the connection point between the first heat exchanger inlet line and the feedwater line in the feedwater line.

4. A steam turbine configured to rotate using steam generated in the aforementioned boiler, A condenser for condensing the steam that has passed through the steam turbine, A condensate pump for supplying water generated by the condensation of steam in the condenser to the boiler, Equipped with, The aforementioned water supply line is configured to connect the condenser and the boiler. The boiler plant according to claim 3, wherein the connection point between the first heat exchanger inlet line and the feedwater line is downstream of the condensate pump in the feedwater line.

5. The aforementioned CO ２ The boiler plant according to claim 1, further comprising an exhaust gas cooling tower for further cooling the exhaust gas cooled in the first heat exchanger.

6. The aforementioned CO ２ The recovery device recovers CO2 contained in the exhaust gas cooled by the exhaust gas cooling tower. ２ The boiler plant according to claim 5, further comprising an absorption tower configured to absorb an amine solution.

7. The aforementioned CO ２ CO2 is recovered by the recovery device and the CO ２ An exhaust gas discharge line for releasing the exhaust gas discharged from the recovery device into the atmosphere, disposed in the exhaust gas discharge line, and configured to heat the exhaust gas by performing heat exchange between the boiler boiler water discharged from the boiler and the CO ２ the exhaust gas discharged from the recovery device; a second heat exchanger configured as described above. The boiler plant according to claim 1, further comprising the following:

8. The boiler is equipped with an economizer. The second heat exchanger uses the boiler water discharged from the economizer and the CO2 ２ The boiler plant according to claim 7, configured to perform heat exchange with the exhaust gas discharged from the recovery device.

9. The aforementioned boiler plant is A water supply line configured to supply the water to the boiler, A recirculation line configured to return the boiler water heated by the aforementioned economizer back to the water supply line, A second heat exchanger inlet line is configured to branch off from the recirculation line and connect to the boiler water inlet of the second heat exchanger, supplying the boiler water heated by the economizer to the second heat exchanger, The boiler plant according to claim 8, further comprising the following:

10. The recirculation line is provided with a recirculation pump for returning the boiler water heated by the economizer back to the water supply line. The boiler plant according to claim 9, wherein the connection point between the second heat exchanger inlet line and the recirculation line is downstream of the recirculation pump in the recirculation line.

11. The aforementioned CO ２ The boiler plant according to claim 7, further comprising a bypass line connecting the exhaust gas supply line and the exhaust gas discharge line so as to bypass the recovery device.

12. If we define the position where the bypass line and the exhaust gas supply line connect as the first position, and the position where the bypass line and the exhaust gas discharge line connect as the second position, The boiler plant according to claim 11, further comprising: a first damper provided in the bypass line; a second damper provided downstream of the first position in the exhaust gas supply line; and a third damper provided upstream of the second position in the exhaust gas discharge line.

13. The boiler plant according to claim 12, wherein the second damper is located upstream of the first heat exchanger in the exhaust gas supply line.

14. The boiler plant according to claim 12, wherein the third damper is located downstream of the second heat exchanger in the exhaust gas discharge line.

15. The boiler plant according to claim 1, further comprising a watering device configured to spray water onto the first heat exchanger from the upstream side of the first heat exchanger in the exhaust gas supply line.

16. The boiler plant according to claim 7, wherein the second heat exchanger is provided above the first heat exchanger.

17. The boiler plant according to claim 16, wherein the first heat exchanger and the second heat exchanger are supported by the same frame.

18. The exhaust gas discharged from the boiler contains CO2 ２ CO2 for recovery ２ An exhaust gas supply line configured to supply to a recovery device, A first heat exchanger is provided in the exhaust gas supply line and is configured to cool the exhaust gas by performing heat exchange between water supplied to the boiler and the exhaust gas discharged from the boiler. Plant facilities equipped with these features.

19. For boiler plants, CO2 contained in the exhaust gas emitted from the boiler. ２ CO2 for recovery ２ A method for connecting a recovery device, The exhaust gas discharged from the boiler is the CO ２ The steps include manufacturing an exhaust gas supply line for supplying to a recovery device, In the step of manufacturing the exhaust gas supply line, a first heat exchanger is incorporated into the exhaust gas supply line to cool the exhaust gas by performing heat exchange between water supplied to the boiler and the exhaust gas discharged from the boiler. A plant connection method having

20. The exhaust gas discharged from the boiler contains CO2 ２ CO2 for recovery ２ A step of supplying exhaust gas to the recovery device, A plant operation method comprising: an exhaust gas cooling step in which the exhaust gas supply step cools the exhaust gas by performing heat exchange between water supplied to the boiler and the exhaust gas discharged from the boiler.

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