JP6349593B2 - Steam turbine plant - Google Patents

Description

  The present invention relates to a steam turbine plant.

  In a steam turbine plant, carbon steel or copper is often used as a material for piping constituting a water supply system or a condensate system. As carbon steel has a lower pH value in water, copper tends to undergo corrosion at pH 9.4 or higher in water. Therefore, in order to avoid the corrosion of the piping in the water supply system and the condensate system, for example, when the water supply system is configured with carbon steel piping, from the viewpoint of suppressing flow accelerated corrosion (FAC), It is desirable to adjust to pH 9.8 or higher. Specifically, ammonia or hydrazine is injected into the water supply to adjust the pH.

  In such a steam turbine plant, it is common to regularly supply water and blow (discharge) unnecessary water out of the system. For example, water is discharged out of the system to prevent swelling when the boiler is started. Moreover, since the water quality deteriorates when the impurity derived from the chemical injected into the water flowing through the system is generated, the water is discharged from the boiler or the like to prevent the impurity from being concentrated.

  As an example of such a technique, a boiler plant described in Patent Document 1 is known. In the boiler plant described in Patent Document 1, a flash tank is provided between the boiler and the condenser. The water discharged from the system is separated into steam and water in the flash tank, the separated steam is returned to the condenser, and the liquid phase components other than the steam are discharged out of the system as drainage through the drain pipe. ing.

JP-A-10-169907

  However, in the technique described in Patent Document 1, the wastewater discharged from the flash tank contains a concentrated component such as a salt generated from a chemical solution injected for pH adjustment. It is necessary to remove. Here, when there is much quantity of the waste_water | drain discharged | emitted from a flash tank, since a large sized waste-water-treatment apparatus is needed, an installation cost and its operation cost become high. Furthermore, in order to replenish the system with water discharged from the system, equipment costs and operation costs required for installing a large-scale pure water production apparatus are required. Therefore, in the conventional steam turbine plant, there is a problem that the equipment cost and the operation cost related to wastewater treatment and pure water supply increase.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a steam turbine plant in which facility costs and operation costs for wastewater treatment and pure water supply are suppressed.

In order to solve the above problems, the present invention employs the following means.
A steam turbine plant according to one aspect of the present invention includes a boiler that generates steam, a steam turbine that is driven by the steam generated in the boiler, and a condenser that returns steam discharged from the steam turbine to water. A water supply line for supplying water from the condenser to the boiler, a makeup water supply part for supplying water to the condenser, a chemical injection part for injecting ammonia into the water supply line, and a discharge from the boiler A recycle line for returning the blown water to the make-up water supply unit, and a dewarming water line for mixing the water in the make-up water supply unit into the recycle line .

According to the said structure, when the chemical | medical solution inject | poured into a water supply line by a chemical | medical solution injection | pouring part is ammonia, it can utilize as water supplied to a boiler, without performing a special process with respect to blow water. Therefore, in the above configuration, the blow water discharged from the boiler is returned to the makeup water supply unit by the recycle line. By supplying the water returned to the makeup water supply unit to the water supply line, it can be used again for the operation of the steam turbine plant.
Furthermore, the water in the makeup water supply unit can be mixed into the recycle line via the temperature-reducing water line.
A steam turbine plant according to one aspect of the present invention includes a boiler that generates steam, a steam turbine that is driven by the steam generated in the boiler, and a condenser that returns steam discharged from the steam turbine to water. A water supply line for supplying water from the condenser to the boiler, a makeup water supply part for supplying water to the condenser, a chemical injection part for injecting ammonia into the water supply line, and a discharge from the boiler A recycling line for returning the blown water to the makeup water supply section, and a cooling section for cooling the water in the makeup water supply section .
According to the said structure, when the chemical | medical solution inject | poured into a water supply line by a chemical | medical solution injection | pouring part is ammonia, it can utilize as water supplied to a boiler, without performing a special process with respect to blow water. Therefore, in the above configuration, the blow water discharged from the boiler is returned to the makeup water supply unit by the recycle line. By supplying the water returned to the makeup water supply unit to the water supply line, it can be used again for the operation of the steam turbine plant.
Furthermore, the water in the makeup water supply unit can be cooled.
Furthermore, the steam turbine plant according to one aspect of the present invention may include a temperature-reduction water line that mixes the water in the makeup water supply unit into the recycle line.
According to the said structure, the water in the said makeup water supply part can be mixed in a recycle line via a temperature reduction water line.

  Furthermore, the steam turbine plant according to one aspect of the present invention further includes a flash tank into which blow water discharged from the boiler flows, and the recycle line sends blow water from the boiler to the flash tank. And a recycle main line for sending blow water in the flash tank from the flash tank to the makeup water supply unit.

  According to the above configuration, part of the blow water is re-vaporized inside the flash tank. Since the blow water that is not re-steamed is supplied to the water supply line via the recycle line as described above, it can be used for the operation of the steam turbine plant. On the other hand, the re-vaporized steam is supplied to the condenser and returned to the water by the condenser.

  Furthermore, in the steam turbine plant according to one aspect of the present invention, a measurement unit that measures a pH value of water supplied from the condenser to the boiler, and a pH value measured by the measurement unit are determined in advance. A control unit that controls the amount of ammonia injected so as to be within the specified range.

  According to the said structure, the control part can control the injection quantity of ammonia based on the pH value of the water supplied to a boiler. Thereby, the pH value of the water used for the operation of the steam turbine plant can be maintained within a predetermined range.

  Furthermore, the steam turbine plant according to one aspect of the present invention includes a steam extraction line that supplies steam generated in the boiler to external equipment other than the steam turbine, and the recycling line. A water purifier for purifying water passing through the water.

  According to the above configuration, the steam taken out by the steam take-out line can be used in external equipment other than the steam turbine. In addition, even if the flow rate of water flowing through the water supply line increases due to the extraction of steam and the content of foreign substances such as salts in the water supply line increases, this should be removed by the water purifier in the recycle line. Can do.

  According to the steam turbine plant according to the present invention, it is possible to provide a steam turbine plant in which facility costs and operation costs related to wastewater treatment and pure water supply are suppressed.

1 is a system diagram of a steam turbine plant according to a first embodiment of the present invention. It is a systematic diagram of the steam turbine plant which concerns on 2nd embodiment of this invention.

[First embodiment]
Hereinafter, a steam turbine plant 1 according to a first embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the steam turbine plant 1 includes a boiler 2 that generates steam, a steam turbine 3 that is driven by the steam, a condenser 4 that returns the steam exhausted from the steam turbine 3 to water, A water supply line 5 that supplies water (supply water) from the condenser 4 to the boiler 2, a makeup water supply unit 6 that supplies water (makeup water) to the condenser 4, and a chemical injection that injects ammonia into the water supply line 5. Part 7. The steam turbine plant 1 further includes a recycle line 8 that returns blow water discharged (blowed) from the boiler 2 to the makeup water supply unit 6.

  The boiler 2 includes a economizer 21, a steam drum 22, and a superheater 23. The economizer 21 preheats the water supplied to the boiler 2. The steam drum 22 generates steam by heating the preheated feed water. The superheater 23 superheats the steam in the steam drum 22 and generates superheated steam having higher thermal energy. The superheated steam is supplied to a steam turbine 3 to be described later, and drives the steam turbine 3.

  The steam turbine 3 is connected to the boiler 2 by a steam supply line 24. Steam generated in the boiler 2 is supplied to the steam turbine 3 through the steam supply line 24. The steam turbine 3 includes a high pressure turbine, an intermediate pressure turbine, a low pressure turbine, and the like.

  Furthermore, the steam turbine 3 is provided with a generator 100 mechanically connected to the rotating shaft. As the rotating shaft of the steam turbine 3 rotates, the generator 100 is driven to generate electric power. This electric power is taken out to the outside and used for various power devices (not shown).

  The steam discharged from the steam turbine 3 is sent to the condenser 4. In the condenser 4, heat exchange is performed on the steam discharged from the steam turbine 3 using cooling water such as seawater. The heat exchanged steam is condensed and returned to the water. The water generated by the condenser 4 is supplied again to the boiler 2 by the water supply pump 5P through the water supply line 5.

  The makeup water supply unit 6 is a device for supplying water (makeup water) to the condenser 4. More specifically, the makeup water supply unit 6 includes a makeup water tank 61 in which makeup water is stored, and a purified water supply unit 62 that supplies purified water to the makeup water tank 61.

  The pure water supply unit 62 is a device that generates pure water by removing impurities from water supplied from a water source (not shown) by filtration or the like. The pure water generated by the pure water supply unit 62 is stored in the makeup water tank 61. The pure water stored in the makeup water tank 61 is supplied to the condenser 4 through the makeup water line 91 as makeup water.

  Further, the makeup water tank 61 is provided with a cooling unit 9 for cooling the pure water inside. The makeup water tank 61 is provided with a temperature-reducing water line 93. The temperature-reduced water line 93 connects the makeup water tank 61 and a recycle main line 82 described later.

  The chemical solution injection unit 7 is a device for injecting ammonia, which is a chemical solution, into the water supply line 5. Specifically, the chemical liquid injection unit 7 controls the chemical liquid tank 71 that stores ammonia, the chemical liquid injection pump 72 that injects ammonia in the chemical liquid tank 71 into the water supply line 5, and the discharge amount of the chemical liquid injection pump 72. And a measurement unit 74 that measures the pH of the feed water flowing through the feed water line 5.

  Ammonia is stored in the liquid phase in the chemical tank 71. This ammonia is injected into the water supply line 5 by the chemical solution injection pump 72. The chemical injection pump 72 is a metering pump, and the discharge amount is adjusted by the control unit 73. The control unit 73 is connected to the measurement unit 74 via a signal line. Thereby, the measured value of pH of the feed water flowing through the feed water line 5 is input to the control unit 73 as an electric signal.

  The control unit 73 stores a predetermined pH value range. The control unit 73 adjusts the discharge amount of the chemical solution injection pump 72 so that the pH value of the water supplied through the water supply line 5 is within the predetermined range. For example, when the pH value (actually measured value) measured by the measuring unit 74 is smaller than the pH value in a predetermined range, the control unit 73 adjusts the discharge amount of the chemical solution injection pump 72 to increase. On the other hand, when the pH value (actually measured value) is larger than the pH value in a predetermined range, the control unit 73 adjusts the discharge amount of the chemical solution injection pump 72 to decrease.

  Furthermore, the steam turbine plant 1 according to the present embodiment includes a flash tank FT into which blow water discharged from the boiler 2 flows, and a recycle line 8 that returns the blow water to the makeup water supply unit 6.

  The recycle line 8 includes a blow water line 81 for sending blow water from the steam drum 22 and a recycle main line 82 for sending the liquid phase components in the flash tank FT to the makeup water supply unit 6. In the flash tank FT, part of the blow water from the steam drum 22 is separated into re-vaporized blow steam and blow water (liquid phase component).

  Only the blown water of the liquid phase component in the flash tank FT flows to the makeup water tank 61 through the recycle main line 82. Blow water flowing through the recycle main line 82 is reduced in temperature by pure water mixed from the makeup water tank 61 through the temperature-reducing water line 93. Since the pure water stored in the makeup water tank 61 is cooled by the cooling unit 9, the cooling water cooled by the cooling unit 9 is mixed into the blow water flowing through the recycle main line 82.

  The flash tank FT is provided with a blow steam line 83 connected to the condenser 4. In the blow steam line 83, the blow steam re-vaporized in the flash tank FT flows to the condenser 4. The blow steam supplied to the condenser 4 through the blow steam line 83 is heat-exchanged and returned to water.

  Then, operation | movement of the steam turbine plant 1 comprised as mentioned above is demonstrated. First, steam generated in the boiler 2 is supplied to the steam turbine 3. The steam turbine 3 is rotated by the supplied steam and drives the generator 100 connected to the rotating shaft.

  The steam exhausted from the steam turbine 3 is sent to the condenser 4. In the condenser 4, the steam is condensed and returned to water by heat exchange. This water is supplied to the boiler 2 through the water supply line 5 as water supply. In the boiler 2, the feed water is heated to generate steam. Thus, by operating the steam turbine plant 1, the feed water flows from the condenser 4 to the boiler 2 through the feed water line 5.

  Here, in the steam turbine plant 1, since carbon steel is used for the piping of the feed water line 5, measures against corrosion due to the feed water are required. As such a measure, the chemical solution is injected by the chemical solution injection unit 7. As the chemical solution, ammonia is used to adjust the pH of the feed water. The feed water flowing through the feed water line 5 is maintained alkaline by ammonia.

  In the chemical liquid tank 71 in the chemical liquid injection unit 7, ammonia is stored in a liquid phase state. The chemical solution supplied from the chemical solution tank 71 is injected upstream of the boiler 2 in the water supply line 5 through the chemical solution injection pump 72. A measuring unit 74 is provided on the water supply line 5. The measuring unit 74 measures the pH of ammonia in the feed water flowing through the feed water line 5. In accordance with this pH value, the control unit 73 adjusts the discharge amount of the chemical solution injection pump 72. As a result, since the pH of the feed water is adjusted and managed by ammonia, corrosion inside the piping constituting the feed water line 5 can be suppressed. Moreover, in the boiler 2 to which this water supply is supplied, the pH of the drum water in the steam drum 22 can be appropriately managed.

  Thus, the ammonia injected into the feed water by the chemical solution injection pump 72 is vaporized from the drum water in the steam drum 22 of the boiler 2 and sent to the steam turbine 3 together with the steam. The vaporized ammonia is exhausted from the steam turbine 3 together with the steam and sent to the condenser 4. In the condenser 4, the vaporized ammonia is condensed by heat exchange and returns to the liquid phase. Here, the condenser 4 is always kept in a vacuum state by a vacuum pump (not shown). For this reason, a part of the vaporized ammonia sent to the condenser 4 is exhausted outside the condenser 4 by the vacuum pump. The chemical liquid injection unit 7 injects the ammonia discharged from the condenser 4 into the water supply line 5 so that the water supplied through the water supply line 5 falls within a predetermined pH range.

  In the steam turbine plant 1, unnecessary water is discharged from the steam drum 22. For example, water (blow water) is discharged from the steam drum 22 in order to prevent swelling when the boiler is activated and to deteriorate water quality due to substances mixed from outside the system. When the water is discharged in this way, the corresponding amount of makeup water is supplied from the makeup water supply unit 6. Even when make-up water is supplied from the make-up water supply unit 6, the chemical solution injection unit 7 injects ammonia into the water supply line 5 so that the water supplied through the water supply line 5 is within a predetermined pH value range.

  The makeup water tank 61 in the makeup water supply unit 6 stores the purified water (makeup water) supplied by the purified water supply unit 62. This makeup water is supplied to the condenser 4 through the makeup water line 91. When supplying makeup water, the makeup water supply unit 6 opens the makeup water valve 92 to supply makeup water. As the makeup water valve 92, a valve device that can adjust the flow rate by adjusting the opening degree is used.

  As described above, the makeup water is supplied by the makeup water supply unit 6, while the blow water is discharged according to the operating condition of the steam turbine plant 1 and the deterioration of the quality of the water supplied through the water supply line 5. Specifically, blow water is discharged from the steam drum 22 of the boiler 2 to the flash tank FT. A part of the blow water is re-vaporized in the flash tank FT. The re-vaporized blow steam flows into the condenser 4 through the blow steam line 83. By exchanging heat in the condenser 4, the blow steam is returned to the water again.

  On the other hand, the blow water that is not re-vaporized is returned from the flash tank FT to the makeup water tank 61 through the recycle main line 82. The blow water returned to the make-up water tank 61 is supplied again to the condenser 4 as make-up water, and then supplied from the condenser 4 to the water supply line 5 to be reused as water supply.

  Here, when the structure using sodium phosphate is adopted as the chemical solution to be injected for pH adjustment, sodium phosphate is concentrated in the steam drum 22 because it is not vaporized in the boiler 2. Then, the blow water discharged from the steam drum 22 and stored in the flash tank FT is re-vaporized. Thereby, sodium phosphate is further concentrated. Therefore, it is necessary to process the blow water in the flash tank FT at a wastewater treatment facility or the like, and the equipment cost and operation cost required for the wastewater treatment are increased.

  However, in this embodiment, since the chemical | medical solution inject | poured into the water supply line 5 by the chemical | medical solution injection | pouring part 7 is ammonia, a blow water is returned to the water supply line 5 without performing a special drainage process with respect to a blow water. Can do. That is, in this embodiment, since pH adjustment is performed only with ammonia that can be vaporized in the boiler 2, this blow water can be returned to the water supply line 5.

  Therefore, in the steam turbine plant 1 according to the present embodiment, the recycle line 8 (recycle main line 82) for returning the blow water from the flash tank FT to the make-up water supply unit 6 (make-up water tank 61) is provided, and the blow water is supplied to the feed water. Reuse as part. Thereby, the installation cost and operation cost which concern on the pure water supply of the steam turbine plant 1 can be held down. Furthermore, the output of a gas turbine can also be improved by injecting a part of blow water to reuse in the air which inhales in a gas turbine. By injecting the blow water, the intake air temperature decreases, so that the mass flow rate of the intake air of the gas turbine increases. Thereby, the output of a gas turbine improves.

  Furthermore, in the steam turbine plant 1 according to the present embodiment, a temperature-reducing water line 93 for reducing the temperature of blow water is connected to the recycle main line 82. In the recycle main line 82, the relatively hot blow water discharged from the steam drum 22 flows into the makeup water supply unit 6. If blow water in a warm water state exceeding 50 ° C. to 60 ° C. is stored in the make-up water supply unit 6, the equipment in the make-up water supply unit 6 may be deteriorated. Further, when the makeup water stored in the makeup water tank 61 is warmed by the high-temperature blow water, the temperature of the water (condensate) in the condenser 4 to which the makeup water is supplied may increase. is there. When the temperature of the condensate increases, the efficiency of the condenser 4 decreases, so the temperature of the condensate needs to be about 30 ° C. to 35 ° C. in consideration of the degree of vacuum. For this reason, the pure water of the makeup water tank 61 is mixed as temperature-reduced water via the temperature-reduced water line 93, so that the temperature of the blow water flowing to the recycle main line 82 can be reduced. In addition, by providing the replenishing water tank 61 with the cooling unit 9 and cooling the pure water stored by the cooling unit 9, the amount of pure water in the replenishing water tank 61 used as the temperature-reduced water can be reduced.

  The control unit 73 can control the amount of ammonia injected based on the pH value of the feed water supplied to the boiler 2. Thereby, the pH value of the water used for the operation of the steam turbine plant 1 can be kept within a predetermined range.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, each configuration in the above-described embodiment, a combination thereof, and the like are examples, and the addition of the configuration within the scope of the present invention, Omission, substitution, and other changes are possible.

In the above-described embodiment, the chemical liquid injected into the water supply line 5 has been described as ammonia, but ammonia and hydrazine may be used in combination.
For example, in the above-described embodiment, an example in which a pH meter is used as the measurement unit 74 has been described. The pH meter measures the nature of the water supply by measuring the conductivity of the water supply flowing through the water supply line 5, for example. However, the aspect of the measurement unit 74 is not limited to this, and any device may be used as long as the pH of water can be measured.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 2, the steam turbine plant 1 according to the present embodiment has different features in the following points as compared with the first embodiment described above. That is, in the steam turbine plant 1 according to the present embodiment, the steam extraction line 201 is provided on the steam supply line 24 that connects the boiler 2 and the steam turbine 3. Furthermore, an external facility 200 other than the steam turbine 3 that is driven by steam is connected to the steam extraction line 201. As a specific example of the external facility 200, a steam heating facility that operates using heat generated by steam can be considered.
Further, the steam turbine plant 1 according to the present embodiment is provided with a pure water purifier 202 on the recycle main line 82. The dewatering device 202 is, for example, a desalination device for removing salt contained in water.

  This dewatering device 202 is provided for the following purposes. That is, in the steam turbine plant 1 according to the present embodiment, the steam in the steam supply line 24 is extracted by the steam extraction line 201 and supplied to the external facility 200. At this time, the amount of feed water or steam supplied to the boiler 2 is increased as compared with the case where the external equipment 200 is not provided.

  In order to complement the increase in steam consumption, the amount of makeup water supplied by the makeup water supply unit 6 is also increased compared to the first embodiment. When the supply amount of make-up water is increased, the amount of accumulated salts contained in the water supply flowing through the water supply line 5 is increased accordingly.

  Therefore, the steam turbine plant 1 according to the present embodiment is provided with the pure water purifier 202 that purifies the blow water flowing through the recycle main line as described above. Thereby, since salt is removed, the quality of the feed water flowing through the feed water line 5 can be maintained in a stable state. Thereby, while suppressing the operating cost of the steam turbine plant 1, this can be operated more stably.

DESCRIPTION OF SYMBOLS 1 ... Steam turbine plant 2 ... Boiler 3 ... Steam turbine 4 ... Condenser 5 ... Water supply line 6 ... Supply water supply part 7 ... Chemical liquid injection | pouring part 8 ... Recycle line 9 ... Cooling part 21 ... Eco-saving device 22 ... Steam drum 23 ... Superheater 24 ... Steam supply line 25 ... Condensation line 61 ... Supply water tank 62 ... Pure water supply part 71 ... Chemical liquid tank 72 ... Valve 73 ... Control part 74 ... Measurement part 81 ... Blow water line 82 ... Recycle main line 83 ... Blow steam line FT ... Flash tank 91 ... Supply water line 92 ... Supply water valve 93 ... Dewarmed water line 100 ... Generator 200 ... External equipment 201 ... Steam take-out line 202 ... Pure water purifier

Claims (6)

A boiler that generates steam;
A steam turbine driven by steam generated in the boiler;
A condenser for returning steam exhausted from the steam turbine to water;
A water supply line for supplying water from the condenser to the boiler;
A make-up water supply unit for supplying water to the condenser;
A chemical injection part for injecting ammonia into the water supply line;
A recycle line for returning blow water discharged from the boiler to the makeup water supply unit;
A temperature-reducing water line that mixes the water in the makeup water supply unit into the recycle line;
A steam turbine plant comprising: A boiler that generates steam;
A steam turbine driven by steam generated in the boiler;
A condenser for returning steam exhausted from the steam turbine to water;
A water supply line for supplying water from the condenser to the boiler;
A make-up water supply unit for supplying water to the condenser;
A chemical injection part for injecting ammonia into the water supply line;
A recycle line for returning blow water discharged from the boiler to the makeup water supply unit;
A cooling unit for cooling water in the makeup water supply unit;
A steam turbine plant comprising: Steam turbine plant according to the water in the makeup water supply unit, the 請 Motomeko 2 Ru with a reduced hot water line to be mixed into the recycle line. Further comprising a flash tank into which blow water discharged from the boiler flows,
The recycling line is
A blow water line for sending blow water from the boiler to the flash tank;
A recycle main line for sending blow water in the flash tank from the flash tank to the makeup water supply unit;
The steam turbine plant according to any one of claims 1 to 3, further comprising: A measuring unit for measuring the pH value of water supplied from the condenser to the boiler;
A control unit that controls the amount of ammonia injected so that the pH value measured by the measurement unit falls within a predetermined range;
The steam turbine plant according to any one of claims 1 to 4, further comprising: A steam extraction line for supplying steam generated in the boiler to external equipment other than the steam turbine;
A dewatering device that is provided on the recycle line and purifies water passing through the recycle line;
The steam turbine plant according to any one of claims 1 to 5, further comprising:

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