JP2018031278A - Water collector for thermal power plant - Google Patents

Abstract

[PROBLEMS] To secure sufficient water required in a thermal power plant even when there is a restriction on the use of water resources in the location of the thermal power plant. In a water collecting apparatus 25 of a thermal power plant 10 that performs power generation using combustion gas generated by combustion of fossil fuel and collects water by collecting water vapor from exhaust gas after the combustion gas contributes to power generation. The exhaust gas cooling device 16 is installed on the upstream side of the exhaust gas toward the chimney 18 for exhausting air, and the water recovery device 17 is installed on the downstream side. The exhaust gas cooling device 16 sprays water on the exhaust gas. The water recovery device 17 is configured to directly cool the exhaust gas, and the water recovery device 17 attaches the moisture in the exhaust gas cooled by the exhaust gas cooling device to the surface of the recovery elements arranged along the flow direction of the exhaust gas, and separates and recovers it. The exhaust gas cooling device 16 or the water recovery device 17 is configured to cool the exhaust gas containing water vapor to a temperature below the dew point. [Selection] Figure 1

Description

  The present invention relates to a water collecting apparatus for a thermal power plant using fossil fuels such as liquefied natural gas (LNG), coal, and oil as fuel.

  For example, a LNG-only fired thermal power plant requires a large amount of pure water. In this thermal power plant, steam is generated by a boiler with the heat of combustion gas generated by burning LNG, and a steam turbine is driven by this steam to rotate a generator to generate electricity. In such a thermal power plant, as a steam turbine feed water, water for equipment cooling in the plant, domestic water in the plant, air conditioning water in the plant, etc. Of water.

  As these water sources, river water, industrial water, city water (clean water), etc. are treated and used as pure water. However, the cost of purchasing water is high when these water sources are used, and high cost is also required for pure water production. Furthermore, river water and industrial water have poor water quality, and advanced treatment is required as pure water treatment. In addition, city water (clean water) has relatively good water quality but is very expensive.

  In addition, the water intake itself may be restricted due to various regulations such as environmental regulations, and when the water shortages due to the weather, the water supply is restricted by the local government that is the supplier. If the water supply is restricted, the operation of the thermal power plant may be seriously hindered and the operation may be stopped. In the first place, there is a risk that construction of a thermal power plant itself may not be approved in an area where water is not abundant.

  In particular, in a thermal power plant that uses LNG as fuel, including LNG combustion, hydrocarbons (mostly methane) that are gas components burn, and a large amount of water vapor is generated along with the combustion gas. In the current thermal power plant, all the water vapor generated by this combustion is discharged together with carbon dioxide gas and nitrogen gas, and no device for recovering this water exists.

JP-A-8-260909 JP 2014-129731 A

  In the case where a thermal power plant is provided in an environment where it is difficult to take in industrial water or clean water as described in the background art above, water used in this thermal power plant may not be sufficiently secured. The problem is that there is no technology that can cope with it. By securing a new water source in the thermal power plant, it may be possible to construct and operate the thermal power plant even in locations where construction of the thermal power plant has been impossible in the past.

  The object of the present invention has been made in consideration of the above-mentioned circumstances, and even when there is a restriction on the use of water resources in the location of the thermal power plant, sufficient water required in the thermal power plant is ensured. An object of the present invention is to provide a water collector for a thermal power plant that can be used.

  A water collecting apparatus for a thermal power plant according to the present invention generates power using combustion gas generated by combustion of fossil fuel, collects water vapor from exhaust gas after the combustion gas contributes to power generation, and collects water A water collecting device for a thermal power plant, wherein an exhaust gas cooling device is installed on the upstream side of the exhaust gas toward an air discharge chimney, and a water recovery device is installed on the downstream side. The water recovery device is configured to directly cool the exhaust gas by spraying water on the surface, and the water recovery device is cooled by the exhaust gas cooling device on the surface of the recovery elements arranged along the flow direction of the exhaust gas. The exhaust gas cooling device or the water recovery device is configured to cool the exhaust gas containing water vapor to a temperature below the dew point. Is characterized in that made the.

  According to the present invention, the exhaust gas cooling device or the water recovery device cools the exhaust gas containing water vapor to a temperature below the dew point, thereby condensing the water vapor in the exhaust gas and generating water. As a result, since a water source can be secured in the thermal power plant, water required in the thermal power plant can be sufficiently secured even when there are restrictions on the use of water resources in the location of the thermal power plant.

1 is a system diagram showing a combined cycle type thermal power plant to which a first embodiment of a water collecting apparatus for a thermal power plant according to the present invention is applied. FIG. Sectional drawing which shows the water collection | recovery apparatus of FIG. Sectional drawing which follows the III-III line | wire of FIG. 4A and 4B show the recovery unit of FIGS. 2 and 3, in which FIG. 4A is a longitudinal sectional view, and FIGS. 4B and 4C are sectional views taken along lines IVB-IVB and IVC-IVC in FIG. The longitudinal cross-sectional view which shows the other example of the water collection | recovery apparatus in FIG. Sectional drawing which follows the VI-VI line of FIG. The recovery pipe of FIG.5 and FIG.6 is shown, (A) is the longitudinal cross-sectional view, (B) is sectional drawing which follows the VIIB-VIIB line | wire of FIG. 7 (A). The systematic diagram which shows the combined cycle system thermal power plant to which 2nd Embodiment of the water collector of the thermal power plant which concerns on this invention was applied. The system diagram which shows the conventional combined cycle system thermal power plant. System diagram showing another conventional combined cycle thermal power plant.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
[A] First embodiment (FIGS. 1 to 7)
FIG. 1 is a system diagram showing a combined cycle type thermal power plant to which a first embodiment of a water collecting apparatus for a thermal power plant according to the present invention is applied. This thermal power plant 10 uses liquefied natural gas (LNG), fossil fuels such as coal and oil as fuel, and in particular, generates power by rotating the gas turbine 12 with combustion gas generated by the combustion of LNG. The combined cycle type thermal power generation in which steam is generated in the exhaust heat recovery boiler 14 using the heat of the exhaust gas from the gas turbine 12 and the steam turbine 15 is rotationally driven by this steam (driving steam). It is a plant.

  That is, LNG that is fossil fuel is stored in a liquid state in the storage tank, is vaporized, mixed with compressed air, and sent to the combustor 11. The combustor 11 combusts the vaporized LNG, generates a high-temperature combustion gas of, for example, 1000 ° C. or higher, and supplies the combustion gas to the gas turbine 12.

  The gas turbine 12 is rotationally driven by the combustion gas from the combustor 11, and rotates the connected generator 13 to generate electric power. The combustion gas that has finished its work in the gas turbine 12 becomes exhaust gas of about 500 ° C. to 600 ° C. and is sent to the exhaust heat recovery boiler 14.

  The exhaust heat recovery boiler 14 heats the supplied water (boiler water) by exchanging heat with exhaust gas while removing nitrogen oxide (NOx), for example, to generate superheated steam. The steam for driving is supplied to the steam turbine 15. The exhaust gas heat-exchanged with the boiler water in the exhaust heat recovery boiler 14 is discharged from the chimney 18 to the atmosphere through an exhaust gas cooling device 16 and a water recovery device 17 which will be described later.

  The steam turbine 15 is rotationally driven by the driving steam from the exhaust heat recovery boiler 14, and rotates the connected generator 19 to generate electric power. This generator 19 may be the same as that of the generator 13 or may be different. The steam (driving steam) that has finished work in the steam turbine 15 is fed to the condenser 20. This condenser 20 cools the supplied steam while condensing it, condenses it, and returns it to water, thereby increasing the pressure difference before and after the steam turbine 15, thereby generating power that is rotated by the steam turbine 15. The power generation output of the machine 19 is increased. The water generated in the condenser 20 is supplied as boiler water to the exhaust heat recovery boiler 14 via the heat exchanger 21.

  Here, as shown in FIG. 9, in the conventional thermal power plant 100, the boiler water from the condenser 20 is directly supplied to the exhaust heat recovery boiler 14, but the boiler water is cooled by the condenser 20. When the heat flows into the exhaust heat recovery boiler 14 at the low temperature, dew condensation occurs on the surface of a heat exchanger (not shown) in the exhaust heat recovery boiler 14 and the members including the heat exchanger are corroded. Become. In FIG. 9 and FIG. 10 to be described next, the same reference numerals are assigned to the same apparatuses and devices as in the present embodiment.

  On the other hand, in each other conventional power plant 110 shown in FIG. 10, a part of the superheated steam (driving steam) generated in the exhaust heat recovery boiler 14 is branched and led to the heat exchanger 111 to perform this heat exchange. In the vessel 111, the boiler water from the condenser 20 and a part of the superheated steam are mixed to increase the temperature of the boiler water. Thereby, generation | occurrence | production of the dew condensation in the exhaust heat recovery boiler 14 is prevented with the boiler water supplied to the exhaust heat recovery boiler 14, and it becomes possible to prevent corrosion of the members in the exhaust heat recovery boiler 14. However, in this thermal power plant 110, the boiler water supplied to the exhaust heat recovery boiler 14 is heated using a part of the superheated steam generated in the exhaust heat recovery boiler 14. The superheated steam (driving steam) supplied to the turbine 15 decreases, and the power generation output of the generator 19 connected to the steam turbine 15 decreases.

  In contrast, in the thermal power plant 10 of the present embodiment, the exhaust gas cooling device 16 is installed on the upstream side in the middle of the exhaust system of the exhaust gas flowing from the exhaust heat recovery boiler 14 to the chimney 18, and the water recovery device 17 is installed on the downstream side. The exhaust gas cooling device 16 and the water recovery device 17 cool the exhaust gas discharged from the exhaust heat recovery boiler 14, condenses and collects water vapor (moisture) from the exhaust gas, collects water, and collects the exhaust gas. 16 and the heat exchanger 21 raise the temperature of boiler water supplied to the exhaust heat recovery boiler 14 using water that has cooled the exhaust gas and absorbed heat.

  As described above, in the thermal power plant 10 of the present embodiment, a water source is secured in the thermal power plant 10 by condensing water vapor in the exhaust gas generated together with combustion gas by combustion of fossil fuel and collecting water. It becomes possible to do. Further, the boiler water fed to the exhaust heat recovery boiler 14 is heated by using the heat of the exhaust gas discharged from the exhaust heat recovery boiler 14, and thereby the generator 19 connected to the steam turbine 15 is used. It is possible to secure the power generation output and prevent the occurrence of corrosion in the exhaust heat recovery boiler 14.

  Hereinafter, the exhaust gas cooling device 16, the water recovery device 17 and the cooling device 21, and the recovered water tank 22 and the cooling device 23 that constitute the water collecting device 25 of the thermal power plant 10 will be described in detail. Here, the water collecting device 25 recovers water vapor generated together with the combustion gas by the combustion of fossil fuel from the exhaust gas after the combustion gas contributes to power generation, specifically, the exhaust gas discharged from the exhaust heat recovery boiler 14. In addition to collecting the water, the heat is recovered from the exhaust gas, and the temperature of the boiler water supplied to the exhaust heat recovery boiler 14 is raised.

  The exhaust gas cooling device 16 sprays water at 20 ° C. to 40 ° C. using the spray nozzle 26 on the exhaust gas at about 80 ° C. to 120 ° C. discharged from the exhaust heat recovery boiler 14, thereby directly cooling the exhaust gas. It is a type cooling tower, and the exhaust gas is cooled to about 30 ° C to 60 ° C. The water sprayed from the spray nozzle 26 rises in temperature by absorbing heat from the exhaust gas and further vaporizes. For this reason, the humidity of the exhaust gas is about several percent to several tens of percent at the outlet A of the exhaust heat recovery boiler 14, but becomes wet steam containing a lot of moisture at the outlet B of the exhaust gas cooling device 16. The exhaust gas that has become wet steam is sent to the water recovery device 17. Further, the water whose temperature has increased by absorbing the heat of the exhaust gas is sent to the heat exchanger 21.

  The spray nozzle 26 is installed in the upper part of the exhaust gas cooling device 16, and is configured to spray water mist of several μm to several tens of μm. The reason why the mist of water sprayed from the spray nozzle 26 is several μm to several tens of μm is that the finer the mist of water to be sprayed, the higher the heat exchange efficiency with the exhaust gas, and thus the amount of water to be sprayed can be suppressed. Since the driving force for transporting water to the height of the spray nozzle 26 can be reduced, and the solid water is not contained in the sprayed water, the heat transfer coefficient of the mist is high and the exhaust gas cooling device 16 itself is downsized. This is because it can.

  Further, in the exhaust gas cooling device 16, since nitrogen oxide (NOx) contained in the exhaust gas fed from the exhaust heat recovery boiler 14 is absorbed by water, neutralization facilities and desalination facilities are provided as necessary. It is done. Even when these facilities are provided, the exhaust gas cooling device 16 is configured to pass the exhaust gas with a low pressure loss in order to ensure the power generation output by the generator 13 driven by the gas turbine 10.

  The water recovery device 17 is connected to the exhaust gas cooling device 16 on the surface of the recovery elements 27 (laminated flat plate 27A shown in FIG. 4 or fiber mist separator 27B shown in FIG. 7) arranged along the flow of the exhaust gas. The water in the exhaust gas that has been cooled to become wet steam is attached as water droplets, separated from the exhaust gas, collected, and collected. Further, the water recovery device 17 is provided with a cooling function for cooling the exhaust gas of the wet steam including water vapor to a dew point (about 30 ° C.) or less as necessary.

  When the water recovery device 17 has a cooling function, the temperature of the exhaust gas led from the exhaust gas cooling device 16 is higher than the dew point. By the above-described cooling function of the water recovery device 17 or when the exhaust gas is cooled to the dew point by the exhaust gas cooling device 16, water vapor is recovered by condensing water vapor derived from fossil fuel (LNG in this embodiment) contained in the exhaust gas. It becomes possible to collect the liquid by adhering to the recovery element 27 of the device 17 as a water droplet. From the outlet C of the water recovery device 17, the exhaust gas from which water vapor has been removed and cooled to about 30 ° C. is discharged to the chimney 18 and discharged from the chimney 18 into the atmosphere. This embodiment demonstrates the case where the water collection | recovery apparatus 17 has a cooling function.

  That is, as shown in FIGS. 2 to 4, the water recovery apparatus 17 having the flat plate 27 </ b> A as the recovery element 27 includes a recovery unit 28 that accommodates the flat plate 27 </ b> A. As shown in FIG. 4, the recovery unit 28 is configured to be blocked from outside air, and a plurality of flat plates 27 </ b> A are stacked inside with a gap (not shown) therebetween, along the exhaust gas flow direction X. Arrange in parallel. Below the recovery unit 28, the exhaust gas flows between the flat plates 27A in the recovery unit, so that water droplets adhere to the surface of the flat plate 27A, and the water when the attached water droplets grow and fall due to the action of gravity. A water receiver 29 is formed. The water receiver 29 is connected to the recovery water tank 22 via the water supply tube 30, and water in the water receiver 29 is guided to the recovery water tank 22 through the water supply tube 30 by the action of gravity.

  As shown in FIGS. 2 and 3, a plurality of or one recovery unit 28 is installed in the casing 31 of the water recovery device 17 with an air passage 32 therebetween. An inlet duct 33 that guides exhaust gas from the exhaust gas cooling device 16 and a lead-out duct 34 that guides exhaust gas to the chimney 18 are connected to the recovery unit 28 in an airtight state. The casing 31 is formed with an air inlet 35 at the bottom and an air outlet 36 at the top, and a blower fan 37 is installed near the air outlet 36. By the rotation of the blower fan 37, outside air flows into the casing 31 from the air inlet 35, flows in the air passage 32 in the Y direction, and flows out of the air outlet 36. The exhaust gas flowing along the direction perpendicular to the Y direction is heat-exchanged with the outside air and cooled below the dew point.

  Moreover, as shown in FIGS. 5-7, the water collection | recovery apparatus 17 which has the fiber mist separator 27B as the collection | recovery element 27 is provided with the collection | recovery pipe 38 which accommodates the mist separator 27B. As shown in FIG. 7, the recovery pipe 38 is configured to be blocked from outside air, and has a plurality of mist separators 27 </ b> B arranged linearly along the exhaust gas flow direction X. The mist separator 27B may be stacked in the recovery pipe 38 with a gap therebetween via a spacer (not shown) or the like as indicated by a two-dot chain line. At the bottom of the recovery pipe 38, for example, a water supply tube 39 is connected to a downstream position of the most downstream mist separator 27B, and the water supply tube 39 is connected to the recovery water tank 22. As the exhaust gas flows along the mist separator 27 in the recovery pipe 38, water droplets adhere to the surface of these mist separators 27, and the adhered water droplets grow and fall by the action of gravity, and pass through the water supply tube 39. Guided to the recovered water tank 22.

  As shown in FIGS. 5 and 6, one or a plurality of recovery pipes 38 are arranged in the casing 41 of the water recovery apparatus 17. An inlet duct 43 that guides exhaust gas from the exhaust gas cooling device 16 and a lead-out duct 44 that guides exhaust gas to the chimney 18 are connected to the recovery pipe 38 in an airtight state. The casing 41 is formed with an air inlet 35 at the bottom and an air outlet 36 at the top, and a blower fan 37 is installed near the air outlet 36. By the rotation of the blower fan 37, the outside air flows into the casing 41 from the air inlet 35, flows in the Y direction in the casing 41, and flows out of the air outlet 36, so that the inside of the recovery pipe 38 is in the X direction (above The exhaust gas flowing along the direction perpendicular to the Y direction is heat-exchanged with the outside air and cooled below the dew point.

  In the water recovery apparatus 17 including the flat plate 27A or the mist separator 27B as described above, the flat plate 27A is arranged in the recovery unit 28 and the mist separator 27B is arranged in the recovery pipe 38 along the flow direction X of the exhaust gas. Furthermore, the flow path of the exhaust gas in each of the recovery unit 28 and the recovery pipe 38 has a flow path configuration in which expansion and contraction of the flow path cross-sectional area are small and excellent in straightness of the exhaust gas. The pressure loss of the exhaust gas flowing through each of the pipes 38 is reduced, and thereby the power generation output of the generator 13 driven by the gas turbine 12 is ensured. Further, the water droplets adhering to the flat plate 27A fall to the water receiver 29 by the action of gravity, and are further guided to the recovery water tank 22 through the water supply tube 30, and the water droplets attached to the mist separator 27B are fed by the action of gravity. By being guided to the recovery water tank 22 through the tube 39, power for recovering water in the water recovery device 17 and the recovery water tank 22 becomes unnecessary.

  As shown in FIG. 1, the recovered water recovered by the water recovery device 17 and guided to the recovery water tank 22 is purified as necessary, and a part of the makeup water supplied to the water sprayed by the exhaust gas cooling device 16. The remainder is supplied into the thermal power plant 10. The above-described recovered water is purified as follows.

  That is, since the recovered water led to the exhaust heat recovery boiler 14 becomes acidic water due to the dissolution of nitrogen oxides (NOx), for example, the pH is reduced by removing anions with an ion exchange resin or adding a neutralizing agent. Is neutral. As the neutralizing agent, slaked lime, sodium hydroxide, sodium bicarbonate, sodium carbonate or the like is used. If this neutralized recovered water is made pure water by performing a desalting process using a reverse osmosis membrane or ion exchange resin and removing particles using an ultrafiltration membrane, it can be used as boiler water. Become. The pure water can also be used as cleaning water after maintenance of the thermal power plant 10.

  The water whose temperature has increased by absorbing the heat of the exhaust gas in the exhaust gas cooling device 16 shown in FIG. 1 is guided to the heat exchanger 21. The heat exchanger 21 raises the temperature of boiler water fed from the condenser 20 to the exhaust heat recovery boiler 14 by exchanging heat with water that has absorbed heat by cooling the exhaust gas from the exhaust gas cooling device 16. 10 can replace the temperature rise of the boiler water for preventing corrosion of the internal member of the exhaust heat recovery boiler 14 performed by the heat exchanger 111 of FIG. 10, and the power generation of the generator 19 associated with the installation of the heat exchanger 111. A decrease in output can be suppressed. Furthermore, depending on the adjustment of the heat balance, the temperature rise of the boiler water by the heat exchanger 21 is made higher than the temperature of the boiler water risen by the heat exchanger 111, so that the thermal efficiency is improved and connected to the steam turbine 15. It is possible to increase the power generation output by the generated generator 19.

  The water cooled by raising the boiler water temperature by the heat exchanger 21 described above is guided to the cooling device 23 and further cooled by the cooling device 23 as necessary. This cooling device 23 uses a cooling tower (water-cooled cooling tower) that uses a large amount of water whose water quality is controlled in view of the fact that the thermal power plant 10 is located in an environment where it is difficult to take water such as clean water or industrial water. This is inappropriate, and an air cooling system or a cooling system using environmental water such as seawater is preferable. The water cooled as necessary by the cooling device 23 is guided to the exhaust gas cooling device 16 and sprayed from the spray nozzle 26 of the exhaust gas cooling device 16.

  Since the water supplied from the cooling device 23 to the exhaust gas cooling device 16 is sprayed and evaporated by the exhaust gas cooling device 16, it is appropriately supplemented from the recovered water tank 22. However, when the exhaust gas is cooled to the dew point (about 30 ° C.) by the exhaust gas cooling device 16, the exhaust gas cooling device 16 condenses the water vapor in the exhaust gas and collects a large amount of water as water. Therefore, in this case, since a large amount of water flows from the exhaust gas cooling device 16 to the cooling device 23 via the heat exchanger 21, a part of the water supplied from the cooling device 23 to the exhaust gas cooling device 16 is appropriately recovered. It is stored in the water tank 22.

With the configuration as described above, the following effects (1) and (2) are achieved according to the first embodiment.
(1) As shown in FIG. 1, the exhaust gas cooling device 16 or the water recovery device 17 cools the exhaust gas containing water vapor to a temperature below the dew point, thereby condensing the water vapor in the exhaust gas and generating water. As a result, since a water source is secured in the thermal power plant 10, even if it is difficult to take in water or industrial water at the location of the thermal power plant 10 and there are restrictions on the use of water resources, this thermal power plant The water required within 10 can be sufficiently secured.

  (2) The boiler water fed to the exhaust heat recovery boiler 14 is heated in the heat exchanger 21 by heat exchange with water that has absorbed heat by cooling the exhaust gas by the exhaust gas cooling device 16. For this reason, first, the low-temperature boiler water from the condenser 20 can flow into the exhaust heat recovery boiler 14 to prevent dew condensation generated in the exhaust heat recovery boiler 14, and therefore, the exhaust heat generated by this dew condensation can be prevented. Corrosion of members in the recovery boiler 14 can be prevented.

  Secondly, since the temperature of the boiler water is increased by using the heat absorbed by the exhaust gas cooling device 16 from the exhaust gas originally discharged from the chimney 18, the thermal efficiency can be improved. Further, since the temperature rise of the boiler water does not use a part of the superheated steam generated in the exhaust heat recovery boiler 14 and supplied to the steam turbine 15, the generator 19 driven by the steam turbine 15 A power generation output can be suitably secured.

[B] Second Embodiment (FIG. 8)
FIG. 8 is a system diagram showing a combined cycle thermal power plant to which the second embodiment of the water collecting apparatus for a thermal power plant according to the present invention is applied. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the description is simplified or omitted.

  The water collecting device 51 of the thermal power plant 50 in the second embodiment is different from the first embodiment in that a plurality of exhaust gas cooling devices 16 are connected in series to form a multistage structure, and the downstream side in the exhaust gas flow direction is configured. This is the point that water that has cooled the exhaust gas by the exhaust gas cooling device 16 and absorbed heat is sprayed by the exhaust gas cooling device 16 upstream in the flow direction of the exhaust gas.

  That is, for example, when three exhaust gas cooling devices 16A, 16B, and 16C are connected in series, the water cooled by the cooling device 23 is sprayed by the exhaust gas cooling device 16C on the most downstream side, and the exhaust gas cooling device 16C The water that has absorbed heat from the exhaust gas is guided to the upstream exhaust gas cooling device 16B and sprayed, and the water that has absorbed heat from the exhaust gas by the exhaust gas cooling device 16B is guided to the most upstream exhaust gas cooling device 16A. Spray. Accordingly, relatively cool water is sprayed on the downstream exhaust gas cooling device 16 (particularly, the most downstream exhaust gas cooling device 16C), and relatively hot water is sprayed on the upstream side (particularly, the most upstream exhaust gas cooling device 16A). Will be sprayed. As a result, the temperature of the water that has absorbed heat from the exhaust gas in the most upstream exhaust gas cooling device 16 (16A) absorbs heat from the exhaust gas when the exhaust gas cooling device 16 is in one stage (that is, only the exhaust gas cooling device 16C). The temperature of the discharged water becomes higher, and the heat of the exhaust gas from the exhaust heat recovery boiler 14 can be recovered more efficiently.

  Therefore, according to the second embodiment, in addition to the effects (1) and (2) of the first embodiment, the following effect (3) is obtained.

  (3) A plurality of exhaust gas cooling devices 16 (for example, exhaust gas cooling devices 16A, 16B, and 16C) are connected in series to form a multistage structure, and exhaust gas is cooled by the exhaust gas cooling device 16 on the downstream side in the exhaust gas flow direction. Since the water that has absorbed heat is sprayed by the exhaust gas cooling device upstream in the exhaust gas flow direction, the temperature of the water that has absorbed heat from the exhaust gas in the exhaust gas cooling device 16 that is most upstream in the exhaust gas flow direction is set. When the exhaust gas cooling device 16 is in a single stage, the temperature can be made higher than the temperature of water that has absorbed heat from the exhaust gas. As described above, the exhaust gas cooling device 16 is configured in a multi-stage structure as described above, so that the heat of the exhaust gas can be efficiently recovered. Therefore, the multi-stage exhaust gas cooling device 16 and the heat exchanger 21 can be used to recover the condenser 20. Therefore, the boiler water fed to the exhaust heat recovery boiler 14 can be set to a higher temperature, and the power generation output by the generator 19 connected to the steam turbine 15 can be improved.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. Is included in the scope and gist of the invention, and is included in the invention described in the claims and the equivalents thereof.

  For example, in the above-described embodiments, the present invention is applied to the combined cycle thermal power plant 10 including the gas turbine 12, the exhaust heat recovery boiler 14, and the steam turbine 15, but the fossil fuel is generated by burning. In a thermal power plant that generates power by driving a gas turbine with combustion gas, the present invention may be applied to exhaust gas discharged from the gas turbine. Furthermore, the present invention is applied to exhaust gas discharged from a boiler in a thermal power plant in which combustion gas generated by burning fossil fuel is guided to a boiler to generate steam, and a steam turbine is driven by the steam to generate power. You may apply.

  DESCRIPTION OF SYMBOLS 10 ... Thermal power plant, 12 ... Gas turbine, 13 ... Generator, 14 ... Exhaust heat recovery boiler, 16 ... Exhaust gas cooling device, 16A, 16B, 16C ... Exhaust gas cooling device, 17 ... Water recovery device, 18 ... Chimney, 19 DESCRIPTION OF SYMBOLS ... Generator, 21 ... Heat exchanger, 22 ... Recovery water tank, 25 ... Water collecting device, 26 ... Spray nozzle, 27 ... Recovery element, 27A ... Flat plate, 27B ... Mist separator, 50 ... Thermal power plant, 51 ... Water collection apparatus.

Claims (7)

A water collecting device for a thermal power plant that performs power generation using combustion gas generated by the combustion of fossil fuel, collects and collects water vapor from exhaust gas after the combustion gas contributes to power generation,
The exhaust gas cooling device is installed on the upstream side of the exhaust gas toward the chimney for air discharge, and the water recovery device is installed on the downstream side,
The exhaust gas cooling device is configured to directly cool the exhaust gas by spraying water on the exhaust gas,
The water recovery device is configured to attach and separate and recover the moisture in the exhaust gas cooled by the exhaust gas cooling device on the surface of the recovery elements arranged along the flow direction of the exhaust gas,
The water collecting apparatus for a thermal power plant, wherein the exhaust gas cooling device or the water recovery device is configured to cool the exhaust gas containing the water vapor to a temperature below a dew point. A boiler for supplying driving steam to the steam turbine for power generation;
The boiler water sent to the boiler is configured to be heated by heat exchange with a heat exchanger and water that has absorbed heat by cooling the exhaust gas with an exhaust gas cooling device. A water collector for a thermal power plant as described in 1. The water collected in the thermal power plant according to claim 2, wherein water cooled by raising the temperature of the boiler water by the heat exchanger is guided to the exhaust gas cooling device and sprayed. apparatus. The water collecting device for a thermal power plant according to any one of claims 1 to 3, wherein the recovery element of the water recovery device is a laminated flat plate or fiber mist separator. The exhaust gas cooling device has a multi-stage structure in which a plurality of units are connected in series, and water that has absorbed heat by cooling the exhaust gas by the exhaust gas cooling device on the downstream side is sprayed on the exhaust gas cooling device on the upstream side. The water collecting device for a thermal power plant according to any one of claims 1 to 4, wherein the water collecting device is configured as described above. 6. The thermal power plant collection according to claim 1, wherein the spray nozzle for spraying water by the exhaust gas cooling device is configured to spray mist of several μm to several tens of μm. Water equipment. The boiler is an exhaust heat recovery boiler that introduces exhaust gas from a gas turbine that is driven by combustion gas and rotates a generator, and heats the supplied water by heat exchange with the exhaust gas to produce driving steam. The water collecting apparatus for a thermal power plant according to any one of claims 2 to 6.

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