JP5041941B2 - Once-through exhaust heat recovery boiler - Google Patents

Description

 The present invention relates to a once-through exhaust heat recovery boiler installed in a combined cycle power generation facility, and more particularly to a once-through exhaust heat recovery boiler suitable for high capacity and high efficiency.

First, the plant configuration of a general combined cycle power generation facility will be described with reference to FIG.

 Electric power is generated by burning natural gas or the like in the gas turbine 1, and high-temperature exhaust gas discharged from the gas turbine 1 is sent to the exhaust heat recovery boiler 2. In the exhaust heat recovery boiler 2, the feed water is converted into steam by heat recovery from the exhaust gas, and the generated steam is sent to the steam turbine 3 to generate power by the generator 4.

 An example of the system configuration of a conventional once-through exhaust heat recovery boiler is shown in FIG. The exhaust gas from the gas turbine 1 is sent from the high-pressure superheater 5 that is the first heat exchange part to the low-pressure economizer 13 that is installed at the most downstream part in the exhaust gas flow direction, and heat recovery is performed therebetween.

 The feed water passes through the low pressure economizer 13, is pressurized by the high and medium pressure feed water pump 17, and is sent to the medium pressure economizer 11 and the high pressure economizer 9. The high-pressure feed water heated by the high-pressure economizer 9 is converted into steam by the high-pressure primary evaporator 8 and the high-pressure secondary evaporator 7, further superheated, and then supplied to the high-pressure superheater 5 via the high-pressure steam separator 14. The Between the high-pressure primary evaporator 8 and the high-pressure secondary evaporator 7, a high-pressure primary evaporator outlet connecting pipe 19, a high-pressure distributor 20, and a high-pressure secondary evaporator inlet connecting pipe 21 are installed.

 6 is a reheater, 10 is a medium pressure evaporator, 12 is a low pressure evaporator, 15 is a medium pressure drum, 12 is a low pressure drum, 18 is a low pressure economizer recirculation system, 22 is a high pressure drain tank, 23 Is a high pressure drain tank blow system, 24 is a high pressure secondary evaporator inlet bypass system, and 25 is a high pressure feed water control valve.

 Here, at the beginning of the start of the exhaust heat recovery boiler, after filling the economizer and evaporator, the gas turbine is ignited, exhaust gas is introduced into the exhaust heat recovery boiler, and evaporation starts in the evaporator. In the system, after evaporation starts in the high-pressure secondary evaporator 7 installed on the upstream side in the exhaust gas flow direction, evaporation starts in the high-pressure primary evaporator 8 installed on the downstream side in the exhaust gas flow direction.

 Therefore, the steam generated in the high-pressure secondary evaporator 7 is sent to the high-pressure steam separator 14, but the high-pressure primary evaporator 8 is in a state where no steam is generated yet, and the retained water in the high-pressure secondary evaporator 7 is The pressure gradually decreases, the inside of the high-pressure secondary evaporator 7 is not filled with fluid, the temperature of the high-pressure secondary evaporator tube rises locally, and in the worst case, the high-pressure secondary evaporator 7 is burned out. There was a fear.

 As a countermeasure, the exhaust heat recovery boiler performs minimum flow operation that forcibly supplies about 10% of the water during rated operation to the evaporator at the beginning of startup, but the once-through type has a large capacity like a drum. There is no water facility, and the blow system 23 blows to the outside of the system or a condenser (not shown) while checking the level with the drain tank 22 installed at the lower part of the brackish water separator 14, but the level fluctuation is Large blow amount.

In order to solve these problems, a bypass system 24 is installed as shown in FIG. 16, and the feed water of the high pressure economizer 9 is bypassed to the inlet of the high pressure secondary evaporator 7 by adjusting the feed water control valve 25 when the boiler is activated. This compensated for the decrease in the water retained in the high-pressure secondary evaporator 7. At the same time, by providing a space above the high pressure primary evaporator 8 without filling the high pressure primary evaporator 8 at the time of water filling before start-up, the sudden flow of the internal fluid into the high pressure secondary evaporator 7 is prevented, and the level fluctuation in the drain tank 22 is prevented. The amount of blow from the blow system 23 is suppressed.
Special table 2001-505645 gazette

 However, since the upper part of the high-pressure primary evaporator 8 is in an empty state where the heat of the exhaust gas is received in the state where no fluid is present in the interior at the initial stage of startup, it is necessary to take measures such as using a low alloy steel for the pipe material. Further, in order to provide a space in the upper part of the high-pressure primary evaporator 8, it is necessary to discharge the internal fluid, resulting in a loss of water supply including the retained heat.

 The purpose of the present invention is to prevent burnout of the evaporator pipe and prevent the brackish water separator from being blown without partial water filling of the primary evaporator in order to suppress level fluctuation and blow amount in the brackish water separator at the start of the exhaust heat recovery boiler. An object of the present invention is to provide a once-through exhaust heat recovery boiler capable of suppressing level fluctuation and improving reliability.

In order to solve the above problems, the first means of the present invention includes a secondary evaporator, a primary evaporator installed downstream of the secondary evaporator in the exhaust gas flow direction, the primary evaporator, and the secondary evaporation. A through-flow comprising a connecting pipe connected in series, a brackish water separator for steam-separating steam generated in the secondary evaporator, and a low-pressure drum installed in a system having a lower pressure than the primary evaporator In the type exhaust heat recovery boiler,
A can water discharge system for discharging can water from the outlet side of the primary evaporator to the low pressure drum is installed.

The second means of the present invention comprises a secondary evaporator, a primary evaporator installed downstream of the secondary evaporator in the exhaust gas flow direction, and the primary evaporator and the secondary evaporator connected in series. A communication pipe, and a brackish water separator for bracking and separating steam generated in the secondary evaporator;
In the once-through exhaust heat recovery boiler equipped with a low-pressure system economizer installed in a system that is at a lower pressure than the primary evaporator,
A can water discharge system for discharging can water from the outlet side of the primary evaporator to the low pressure economizer is installed.

 According to a third means of the present invention, in the first or second means, a economizer of the same pressure system as the primary evaporator is installed downstream of the primary evaporator in the exhaust gas flow direction, and the same pressure system. A water supply control valve or a pressure control valve is provided on the outlet side of the economizer, and a bypass system is provided from the inlet side of the water supply control valve or the pressure control valve toward the inlet side of the secondary evaporator. To do.

The fourth means of the present invention includes a high-pressure secondary evaporator, a high-pressure primary evaporator installed downstream of the high-pressure secondary evaporator in the exhaust gas flow direction, the high-pressure primary evaporator, and the high-pressure secondary evaporator. A through-flow comprising a connecting pipe connected in series, a high-pressure steam separator for steam-separating the steam generated in the high-pressure secondary evaporator, and a low-pressure drum installed in a system having a lower pressure than the high-pressure primary evaporator In the type exhaust heat recovery boiler,
A can water discharge system for discharging can water from the outlet side of the high pressure primary evaporator to the low pressure drum is installed.

The fifth means of the present invention includes a high-pressure secondary evaporator, a high-pressure primary evaporator installed downstream of the high-pressure secondary evaporator in the exhaust gas flow direction, the high-pressure primary evaporator, and the high-pressure secondary evaporator. A connecting pipe connected in series, a high-pressure steam separator for steam-separating steam generated in the high-pressure secondary evaporator, and an intermediate-pressure drum installed in a system having a lower pressure than the high-pressure primary evaporator In the once-through exhaust heat recovery boiler,
A can water discharge system for discharging can water from the outlet side of the high pressure primary evaporator to the intermediate pressure drum is provided.

The sixth means of the present invention includes a high-pressure secondary evaporator, a high-pressure primary evaporator installed downstream of the high-pressure secondary evaporator in the exhaust gas flow direction, the high-pressure primary evaporator, and the high-pressure secondary evaporator. A connecting pipe connected in series, a high-pressure steam separator for steam-separating steam generated in the high-pressure secondary evaporator, and a medium-pressure economizer installed in a system having a lower pressure than the high-pressure primary evaporator In the once-through exhaust heat recovery boiler provided,
A can water discharge system for discharging can water from the outlet side of the high pressure primary evaporator to the medium pressure economizer is installed.

The seventh means of the present invention includes a high-pressure secondary evaporator, a high-pressure primary evaporator installed downstream of the high-pressure secondary evaporator in the exhaust gas flow direction, the high-pressure primary evaporator, and the high-pressure secondary evaporator. A through-flow type comprising a connecting pipe connected in series, a high-pressure steam separator for steam-separating steam generated in the high-pressure secondary evaporator, an intermediate-pressure drum having a lower pressure than the high-pressure primary evaporator, and a low-pressure drum In the exhaust heat recovery boiler,
A can water discharge system for discharging can water from the outlet side of the high pressure primary evaporator to the medium pressure drum and the low pressure drum is provided.

The eighth means of the present invention includes a high-pressure secondary evaporator, a high-pressure primary evaporator installed downstream of the high-pressure secondary evaporator in the exhaust gas flow direction, the high-pressure primary evaporator, and the high-pressure secondary evaporator. A connecting pipe connected in series, a high-pressure steam separator for steam-separating steam generated in the high-pressure secondary evaporator, an intermediate-pressure drum and a low-pressure economizer that have a lower pressure than the high-pressure primary evaporator In the once-through exhaust heat recovery boiler,
A can water discharge system for discharging can water from the outlet side of the high pressure primary evaporator to the intermediate pressure drum and the low pressure economizer is installed.

 According to a ninth means of the present invention, in the fourth to eighth means, a water supply control valve or a pressure control valve is provided on the outlet side of the high-pressure economizer installed on the downstream side in the exhaust gas flow direction of the high-pressure primary evaporator. And a bypass system extending from the inlet side of the water supply control valve or pressure control valve toward the inlet side of the high-pressure secondary evaporator is provided.

The tenth means of the present invention includes a high-pressure secondary evaporator, a high-pressure primary evaporator installed downstream of the high-pressure secondary evaporator in the exhaust gas flow direction, the high-pressure primary evaporator, and the high-pressure secondary evaporator. A high-pressure system comprising: a high-pressure connecting pipe connected in series; and a high-pressure steam separator for steam-separating steam generated in the high-pressure secondary evaporator;
An intermediate pressure secondary evaporator installed downstream of the high pressure primary evaporator in the exhaust gas flow direction, an intermediate pressure primary evaporator installed downstream of the intermediate pressure secondary evaporator in the exhaust gas flow direction, and an intermediate pressure thereof An intermediate pressure communication pipe in which a primary evaporator and the intermediate pressure secondary evaporator are connected in series, an intermediate pressure brackish water separator that separates steam generated by the intermediate pressure secondary evaporator, and the intermediate pressure primary evaporator An intermediate pressure system having an intermediate pressure economizer installed downstream of the exhaust gas flow direction of
In a once-through exhaust heat recovery boiler equipped with a low-pressure drum installed in a system that is lower in pressure than the medium-pressure system,
A first can water discharge system for discharging can water from the outlet side of the high pressure primary evaporator to the medium pressure economizer;
A second can water discharge system for discharging can water from the outlet side of the intermediate pressure primary evaporator to the low pressure drum is installed.

The eleventh means of the present invention includes a high-pressure secondary evaporator, a high-pressure primary evaporator installed downstream of the high-pressure secondary evaporator in the exhaust gas flow direction, the high-pressure primary evaporator, and the high-pressure secondary evaporator. A high-pressure system comprising: a high-pressure connecting pipe connected in series; and a high-pressure steam separator for steam-separating steam generated in the high-pressure secondary evaporator;
An intermediate pressure secondary evaporator installed downstream of the high pressure primary evaporator in the exhaust gas flow direction, an intermediate pressure primary evaporator installed downstream of the intermediate pressure secondary evaporator in the exhaust gas flow direction, and an intermediate pressure thereof An intermediate pressure communication pipe in which a primary evaporator and the intermediate pressure secondary evaporator are connected in series, an intermediate pressure brackish water separator that separates steam generated by the intermediate pressure secondary evaporator, and the intermediate pressure primary evaporator An intermediate pressure system having an intermediate pressure economizer installed downstream of the exhaust gas flow direction of
In the once-through exhaust heat recovery boiler equipped with a low-pressure economizer installed in a system that is lower in pressure than the medium-pressure system,
A first can water discharge system for discharging can water from the outlet side of the high pressure primary evaporator to the medium pressure economizer;
A second can water discharge system for discharging can water from the outlet side of the intermediate pressure primary evaporator to the low pressure economizer is installed.

  The present invention is configured as described above, and without performing partial water filling of the primary evaporator in order to suppress level fluctuation and blow amount in the brackish water separator at the start of the exhaust heat recovery boiler, It is possible to provide a once-through exhaust heat recovery boiler that can prevent burnout and suppress fluctuations in the level of the brackish water separator and can improve reliability.

  According to the embodiments of the present invention described below, by installing a discharge system for outlet water of the high-pressure primary evaporator, a brackish water separator at startup without providing a space above the high-pressure primary evaporator before starting the boiler Level fluctuations and the amount of blow can be suppressed, and it is not necessary to take measures to blow the primary evaporator, and loss of water supply including retained heat can be prevented.

 In addition, by setting the outlet water of the high-pressure primary evaporator to the low-pressure drum or low-pressure economizer inlet, the time until the feed water temperature at the exhaust heat recovery boiler inlet is raised above the dew point temperature can be shortened. It becomes possible to more reliably prevent stress corrosion cracking.

 Furthermore, by setting the outlet water of the high-pressure primary evaporator to the medium pressure drum or medium pressure economizer system, the time for the fuel warming water to rise will be shortened, and the efficiency of the gas turbine will be reduced. Improvements can be made early.

(First embodiment)
Next, each embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a system diagram of a once-through exhaust heat recovery boiler according to the first embodiment.

  The exhaust gas from the gas turbine is sent from the high-pressure superheater 5 which is the first heat exchange part to the low-pressure economizer 13 installed at the most downstream part in the exhaust gas flow direction, and heat recovery is performed in the meantime.

 The feed water passes through the low pressure economizer 13, is pressurized by the high and medium pressure feed water pump 17, and is sent to the medium pressure economizer 11 and the high pressure economizer 9. The high-pressure feed water heated by the high-pressure economizer 9 is converted into steam by the high-pressure primary evaporator 8 and the high-pressure secondary evaporator 7, further superheated, and then supplied to the high-pressure superheater 5 via the high-pressure steam separator 14. The Between the high-pressure primary evaporator 8 and the high-pressure secondary evaporator 7, a high-pressure primary evaporator outlet connecting pipe 19, a high-pressure distributor 20, and a high-pressure secondary evaporator inlet connecting pipe 21 are installed.

 In the present embodiment, a low-pressure drum discharge system 26 for discharging the internal fluid from the outlet of the high-pressure primary evaporator 8 to the low-pressure drum 16 is installed, and the low-pressure drum discharge system 26 is shown in FIG. Branching from the middle of the vessel outlet connecting pipe 19 is connected to the low pressure drum 16.

 At the start of the boiler, the minimum flow operation is performed with the high pressure primary evaporator 8 being full, and a certain amount of water is forcibly supplied from the high pressure economizer 9 to the high pressure primary evaporator 8. Prevents burning. At that time, by discharging a part of the outlet water of the high-pressure primary evaporator 8 to the low-pressure drum 16 by the low-pressure drum discharge system 26, it is possible to prevent a sudden flow of fluid into the high-pressure secondary evaporator 7. The level fluctuation of the high-pressure brack separator 14 and the amount of blow can be suppressed.

 The further effect of this embodiment is demonstrated using FIG. The figure has shown the inlet water supply temperature characteristic of the low pressure economizer 13 at the time of boiler starting.

 The inlet water supply temperature of the low-pressure economizer 13 is changed to the high-temperature water supply at the outlet of the low-pressure economizer 13 by the economizer recirculation pump 41 installed in the low-pressure economizer recirculation system 18. Recirculation to the pipe raises the feed water temperature at the inlet of the low-pressure economizer 13 and causes moisture in the exhaust gas to condense and corrode on the surface of the low-pressure economizer pipe installed in the exhaust gas flow path. Is to prevent.

 By the way, in the conventional exhaust heat recovery boiler, as shown in FIG. 16, there is no low pressure drum discharge system 26 for sending the fluid heated by the high pressure primary evaporator 8 to the low pressure drum 16, and the low pressure economizer 13 is the most downstream in the exhaust gas flow direction. Therefore, when the boiler is started, it takes time to increase the temperature at the outlet of the low-pressure economizer 13, that is, the above-described temperature increase using the low-pressure economizer recirculation system 18 (see the one-dot chain line in FIG. 2). ). Therefore, there is a problem that a time zone in which the exhaust water recovery boiler inlet water supply temperature is below the dew point exists for a long time at the start-up.

 On the other hand, in the present embodiment, the fluid heated by the high pressure primary evaporator 8 is sent to the low pressure evaporator 12 via the low pressure drum 16, so that the gas temperature downstream of the low pressure evaporator 12 in the exhaust gas flow direction is higher than that of the prior art. The outlet water supply temperature of the low-pressure economizer 13 rises early, and the temperature rise at the inlet of the low-pressure economizer 13 is also accelerated (see the solid line in FIG. 2). Therefore, the time during which the moisture in the exhaust gas is condensed on the pipe surface of the low-pressure economizer 13 at the beginning of the startup is shortened, and the concern about corrosion and stress corrosion cracking is reduced.

(Second Embodiment)
FIG. 3 is a system diagram of the once-through exhaust heat recovery boiler according to the second embodiment. In the present embodiment, a high-pressure secondary evaporator inlet bypass system for bypassing the feed water of the high-pressure economizer 9 to the inlet side of the high-pressure secondary evaporator 7 in the system of the once-through exhaust heat recovery boiler according to the first embodiment. By adding 24, it was decided to more reliably take measures against burning of the high-pressure secondary evaporator 7. That is, by installing the bypass system 24 and bypassing a part of the water supply of the high pressure economizer 9 to the inlet of the high pressure secondary evaporator 7 by adjusting the high pressure water supply control valve 25 when the boiler is started up, the high pressure secondary evaporator 7 To compensate for the decrease in the water held inside.

 Also in the present embodiment, as in the first embodiment, the level fluctuation of the high-pressure steam separator 14 and the blow amount can be suppressed, and the dew condensation time on the pipe surface of the low-pressure economizer 13 is shortened. The effect of suppressing water corrosion and stress corrosion cracking can also be obtained.

(Third embodiment)
FIG. 4 is a system diagram of the once-through exhaust heat recovery boiler according to the third embodiment. The present embodiment is different from the second embodiment in that a feed water adjustment valve 42 is provided between the high and medium pressure feed water pipe 17 and the high pressure economizer 9, and a pressure control valve 43 is provided on the outlet side of the high pressure economizer 9. This is the point.

 The bypass system 24 is a system provided so that the high-pressure secondary evaporator 7 is not damaged. A valve attached in the middle of the bypass system 24 is an evaporator minimum flow valve (angle valve). It opens only at the beginning of boiler startup. Therefore, when the water supply control valve 25 is provided as shown in FIG. 3, the flow rate is controlled by the water supply control valve 25 to bring the bypass system 24 into a minimum flow state. On the other hand, when using the pressure control valve 43 as shown in FIG. 4, the differential pressure is applied to bring the bypass system 24 into a minimum flow state, and the pressure control valve 43 cannot control the flow rate. A water supply control valve 42 is provided between the high pressure economizer 9.

(Fourth embodiment)
FIG. 5 is a system diagram of the once-through exhaust heat recovery boiler according to the fourth embodiment. The present embodiment is different from the first embodiment in that an intermediate pressure drum discharge system 27 that discharges internal fluid from the outlet of the high pressure primary evaporator 8 to the intermediate pressure drum 15 is used instead of the low pressure drum discharge system 26. This is the point where it was installed.

  When the boiler is started, a minimum flow operation is performed with the high-pressure primary evaporator 8 being full, and a certain amount of water is forcibly supplied from the high-pressure economizer 9 to the high-pressure primary evaporator 8 to thereby supply the high-pressure secondary evaporator 7. Prevents burning in At that time, a part of water discharged from the high-pressure primary evaporator 8 is discharged to the intermediate-pressure drum 15 by the intermediate-pressure drum discharge system 2 7, thereby preventing a sudden flow of fluid into the high-pressure secondary evaporator 7. The level fluctuation of the brackish water separator 14 and the amount of blow can be suppressed.

 The further effect of this embodiment is demonstrated using FIG. The figure has shown the feed water temperature characteristic of the medium pressure economizer 10 at the time of boiler starting.

 Since the medium pressure system is installed downstream of the high pressure system in the exhaust gas flow direction, the heat inflow is delayed compared to the high pressure system when the boiler starts up. It takes time to increase the temperature of the water supply to the vessel 11.

 On the other hand, when this embodiment is adopted, heat is sent to the intermediate pressure evaporator 10 through the intermediate pressure drum 15, so that the gas temperature at the outlet of the intermediate pressure evaporator 10 is high, and therefore shown in FIG. Thus, the inlet / outlet water supply temperature of the medium pressure economizer 11 rises at an early stage.

 In order to improve the efficiency of the gas turbine, as shown in FIG. 5, the system in which the fuel gas heater 28 for heating the fuel gas for the gas turbine using the outlet heating water of the medium pressure economizer 11 is installed is a combined cycle. Used in power generation facilities. In the case of this system, if it takes time to increase the temperature of the feed water of the medium pressure economizer 11, it will hinder the startup characteristics and efficiency of the gas turbine. In this regard, if this embodiment is adopted, the time until the outlet side temperature of the medium pressure economizer 11 reaches the temperature required for heating the fuel gas when the boiler is started is shortened, and the startup characteristics of the gas turbine are stable. The efficiency can be improved at an early stage.

(Fifth embodiment)
FIG. 7 is a system diagram of the once-through exhaust heat recovery boiler according to the fifth embodiment. This embodiment is different from the third embodiment in that a high pressure secondary evaporator inlet bypass system 24 for bypassing the feed water of the high pressure economizer 9 to the inlet of the high pressure secondary evaporator 7 is provided. It is the point which decided to take the countermeasure against burning of the next evaporator 7 more reliably.

 Also in this embodiment, the level fluctuation of the brackish water separator 14 and the amount of blow can be suppressed, and the outlet side temperature of the medium pressure economizer 11 at the time of boiler startup reaches the temperature necessary for heating the fuel gas. This shortens the time, stabilizes the startup characteristics of the gas turbine, and improves the efficiency at an early stage.

 Also in this embodiment, instead of the high-pressure water supply control valve 25, a water supply control valve 42 and a pressure control valve 43 can be used as shown in FIG.

(Sixth embodiment)
FIG. 8 is a system diagram of the once-through exhaust heat recovery boiler according to the sixth embodiment. In the case of this embodiment, the low pressure drum discharge system 26 that discharges the internal fluid from the outlet of the high pressure primary evaporator 8 to the low pressure drum 16, and the medium pressure that discharges the internal fluid from the outlet of the high pressure primary evaporator 8 to the intermediate pressure drum 15. A drum discharge system 27 is juxtaposed.

(Seventh embodiment)
FIG. 9 is a system diagram of the once-through exhaust heat recovery boiler according to the seventh embodiment. The present embodiment is different from the fifth embodiment in that a high pressure secondary evaporator inlet bypass system 24 for bypassing the feed water of the high pressure economizer 9 to the inlet of the high pressure secondary evaporator 7 is provided. It is the point which decided to take the countermeasure against burning of the next evaporator 7 more reliably.

 Also in this embodiment, instead of the high-pressure water supply control valve 25, a water supply control valve 42 and a pressure control valve 43 can be used as shown in FIG.

(Eighth embodiment)
FIG. 10 is a system diagram of the once-through exhaust heat recovery boiler according to the eighth embodiment. The present embodiment is different from the seventh embodiment in that a medium pressure economizer recirculation system extending from the outlet side of the high pressure primary evaporator 8 to the medium pressure economizer 11 side instead of the low pressure drum discharge system 26. 30 is provided.

(Ninth embodiment)
FIG. 11 is a system diagram of a once-through exhaust heat recovery boiler according to the ninth embodiment. In the case of the present embodiment, in the exhaust heat recovery boiler adopting the once-through type for the high pressure system and the medium pressure system, the medium pressure economizer system recirculation extending from the outlet side of the high pressure primary evaporator 8 to the medium pressure economizer 11 side. A system 30 is provided, and an intermediate pressure primary evaporator outlet communication pipe 34 extending from the outlet side of the intermediate pressure primary evaporator 32 to the low pressure drum 16 side is provided.

  In the figure, 31 is an intermediate pressure secondary evaporator, 33 is an intermediate pressure steam separator, 35 is an intermediate pressure distributor, 36 is an intermediate pressure secondary evaporator inlet communication pipe, 37 is an intermediate pressure drain tank, and 38 is An intermediate pressure drain tank blow system, 39 is an intermediate pressure secondary evaporator inlet bypass system, and 40 is an intermediate pressure feed water control valve.

(10th Embodiment)
FIG. 12 is a system diagram of the once-through exhaust heat recovery boiler according to the tenth embodiment. The present embodiment is different from the ninth embodiment in that the low pressure economizer inlet extending from the outlet side of the intermediate pressure primary evaporator 32 to the inlet side of the low pressure economizer 13 is used instead of the low pressure drum discharge system 26. The circulation system 29 is provided, and the can water of the intermediate pressure primary evaporator 32 is discharged to the inlet side of the low pressure economizer 13.

(Eleventh embodiment)
FIG. 13 is a system diagram of the once-through exhaust heat recovery boiler according to the eleventh embodiment. In the case of the present embodiment, a low pressure economizer inlet recirculation system 29 extending from the outlet side of the primary evaporator 8 to the inlet side of the low pressure economizer 13 is provided, and the can water of the primary evaporator 8 is supplied to the low pressure economizer 13. It is discharged to the inlet side.

(Twelfth embodiment)
FIG. 14 is a system diagram of a once-through exhaust heat recovery boiler according to a twelfth embodiment. In the case of the present embodiment, a medium pressure economizer recirculation system 30 extending from the outlet side of the primary evaporator 8 to the medium pressure economizer 11 is provided, and the can water of the primary evaporator 8 is supplied to the medium pressure economizer 11. Recirculating to

  When the medium pressure economizer recirculation system 30 is connected to the medium pressure economizer 11 as in the present embodiment, a number of heat transfer panels constituting the medium pressure economizer 11 are connected to each other. Therefore, the pipe of the medium pressure economizer recirculation system 30 is connected to any one of the connecting pipes.

1 is a system diagram of a once-through exhaust heat recovery boiler according to a first embodiment of the present invention. It is a characteristic view which shows the inlet water supply temperature rise in the low pressure economizer of the once-through type heat recovery steam generator according to the first embodiment. It is a systematic diagram of the once-through-type exhaust heat recovery boiler which concerns on 2nd Embodiment of this invention. It is a systematic diagram of a once-through type exhaust heat recovery boiler according to a third embodiment of the present invention. It is a systematic diagram of the once-through type exhaust heat recovery boiler which concerns on 4th Embodiment of this invention. It is a characteristic view which shows the feed water temperature rise of the inlet_port | entrance and an exit in the medium pressure economizer in the once-through-type waste heat recovery boiler which concerns on the 4th Embodiment. It is a systematic diagram of the once-through type exhaust heat recovery boiler which concerns on 5th Embodiment of this invention. It is a systematic diagram of the once-through type exhaust heat recovery boiler which concerns on 6th Embodiment of this invention. It is a systematic diagram of the once-through type exhaust heat recovery boiler which concerns on 7th Embodiment of this invention. It is a systematic diagram of the once-through type exhaust heat recovery boiler which concerns on 8th Embodiment of this invention. It is a systematic diagram of a once-through type exhaust heat recovery boiler according to a ninth embodiment of the present invention. It is a systematic diagram of the once-through type exhaust heat recovery boiler which concerns on 10th Embodiment of this invention. It is a systematic diagram of the once-through type exhaust heat recovery boiler which concerns on 11th Embodiment of this invention. It is a systematic diagram of the once-through type exhaust heat recovery boiler which concerns on 12th Embodiment of this invention. It is a plant block diagram of a combined cycle power generation facility. It is a systematic diagram of the conventional once-through type exhaust heat recovery boiler.

Explanation of symbols

 1: gas turbine, 2: exhaust heat recovery boiler, 3: steam turbine, 4: generator, 5: high pressure superheater, 6: reheater, 7: high pressure secondary evaporator, 8: high pressure primary evaporator, 9 : High pressure economizer, 10: medium pressure evaporator, 11: medium pressure economizer, 12: low pressure evaporator, 13: low pressure economizer, 14: high pressure brackish water separator, 15: medium pressure drum, 16: low pressure Drum, 17: High and medium pressure feed pump, 18: Low pressure economizer recirculation system, 19: High pressure primary evaporator outlet communication pipe, 20: High pressure distributor, 21: High pressure secondary evaporator inlet communication pipe, 22: High pressure drain Tank: 23: High pressure drain tank blow system, 24: High pressure secondary evaporator inlet bypass system, 25: High pressure water supply control valve, 26: Low pressure drum discharge system, 27: Medium pressure drum discharge system, 28: Fuel gas heater, 29: Low pressure economizer inlet recirculation system, 30: Medium pressure economizer recirculation system 31: Medium pressure secondary evaporator, 32: Medium pressure primary economizer, 33: Medium pressure brackish water separator, 34: Medium pressure primary evaporator outlet connecting pipe, 35: Medium pressure distributor, 36: Medium pressure secondary Secondary evaporator inlet communication pipe, 37: Medium pressure drain tank, 38: Medium pressure drain tank blow system, 39: Medium pressure secondary evaporator inlet bypass system, 40: Medium pressure feed water control valve, 41: Recycler Pump, 42: water supply control valve, 43: pressure water control valve.

Claims (11)

A secondary evaporator, a primary evaporator installed downstream in the exhaust gas flow direction of the secondary evaporator, a connecting pipe connecting the primary evaporator and the secondary evaporator in series, and the secondary evaporator In the once-through type exhaust heat recovery boiler equipped with a brackish water separator for bracking off the steam generated in, and a low-pressure drum installed in a system having a lower pressure than the primary evaporator,
A once-through exhaust heat recovery boiler having a can water discharge system for discharging can water from the outlet side of the primary evaporator to the low pressure drum. A secondary evaporator, a primary evaporator installed downstream in the exhaust gas flow direction of the secondary evaporator, a connecting pipe connecting the primary evaporator and the secondary evaporator in series, and the secondary evaporator In the once-through type heat recovery steam generator equipped with a brackish water separator for bracking off the steam generated in the above, and a low-pressure system economizer installed in a system having a lower pressure than the primary evaporator,
A once-through exhaust heat recovery boiler, wherein a can water discharge system for discharging can water from the outlet side of the primary evaporator to the low pressure economizer is installed.  3. The once-through exhaust heat recovery boiler according to claim 1, wherein a economizer of the same pressure system as the primary evaporator is installed downstream of the primary evaporator in the exhaust gas flow direction, and the economizer of the same pressure system is installed. A once-through type characterized in that a water supply control valve or a pressure control valve is provided on the outlet side of the evaporator, and a bypass system is provided from the inlet side of the water supply control valve or pressure control valve toward the inlet side of the secondary evaporator Waste heat recovery boiler. A high-pressure secondary evaporator, a high-pressure primary evaporator installed on the downstream side in the exhaust gas flow direction of the high-pressure secondary evaporator, a communication pipe connecting the high-pressure primary evaporator and the high-pressure secondary evaporator in series, In the once-through exhaust heat recovery boiler comprising a high-pressure steam separator for steam-separating steam generated in the high-pressure secondary evaporator, and a low-pressure drum installed in a system having a lower pressure than the high-pressure primary evaporator,
A once-through exhaust heat recovery boiler having a can water discharge system for discharging can water from the outlet side of the high pressure primary evaporator to the low pressure drum. A high-pressure secondary evaporator, a high-pressure primary evaporator installed on the downstream side in the exhaust gas flow direction of the high-pressure secondary evaporator, a communication pipe connecting the high-pressure primary evaporator and the high-pressure secondary evaporator in series, In the once-through exhaust heat recovery boiler provided with a high-pressure steam separator for steam-separating steam generated in the high-pressure secondary evaporator and a medium-pressure drum installed in a system having a lower pressure than the high-pressure primary evaporator,
A once-through exhaust heat recovery boiler, wherein a can water discharge system for discharging can water from the outlet side of the high pressure primary evaporator to the intermediate pressure drum is installed. A high-pressure secondary evaporator, a high-pressure primary evaporator installed on the downstream side in the exhaust gas flow direction of the high-pressure secondary evaporator, a communication pipe connecting the high-pressure primary evaporator and the high-pressure secondary evaporator in series, In a once-through type exhaust heat recovery boiler equipped with a high-pressure steam separator for steam-separating steam generated in the high-pressure secondary evaporator and a medium-pressure economizer installed in a system having a lower pressure than the high-pressure primary evaporator ,
A once-through exhaust heat recovery boiler, wherein a can water discharge system for discharging can water from the outlet side of the high pressure primary evaporator to the medium pressure economizer is installed. A high-pressure secondary evaporator, a high-pressure primary evaporator installed on the downstream side in the exhaust gas flow direction of the high-pressure secondary evaporator, a communication pipe connecting the high-pressure primary evaporator and the high-pressure secondary evaporator in series, In a once-through exhaust heat recovery boiler comprising a high-pressure steam separator for steam-separating steam generated in the high-pressure secondary evaporator, an intermediate-pressure drum having a lower pressure than the high-pressure primary evaporator, and a low-pressure drum,
A once-through exhaust heat recovery boiler having a can water discharge system for discharging can water from the outlet side of the high pressure primary evaporator to the intermediate pressure drum and the low pressure drum. A high-pressure secondary evaporator, a high-pressure primary evaporator installed on the downstream side in the exhaust gas flow direction of the high-pressure secondary evaporator, a communication pipe connecting the high-pressure primary evaporator and the high-pressure secondary evaporator in series, In a once-through exhaust heat recovery boiler equipped with a high-pressure steam separator for steam-separating steam generated in the high-pressure secondary evaporator, a medium-pressure drum and a low-pressure economizer that have a lower pressure than the high-pressure primary evaporator,
A once-through exhaust heat recovery boiler, wherein a can water discharge system for discharging can water from the outlet side of the high pressure primary evaporator to the intermediate pressure drum and the low pressure economizer is installed.  The once-through type exhaust heat recovery boiler according to any one of claims 4 to 8, wherein a feed water control valve or a pressure control is provided at an outlet side of a high pressure economizer installed downstream of the high pressure primary evaporator in an exhaust gas flow direction. A once-through exhaust heat recovery boiler comprising a valve and a bypass system extending from an inlet side of the water supply control valve or the pressure control valve toward an inlet side of the high-pressure secondary evaporator. A high-pressure secondary evaporator, a high-pressure primary evaporator installed downstream of the high-pressure secondary evaporator in the exhaust gas flow direction, a high-pressure connecting pipe connecting the high-pressure primary evaporator and the high-pressure secondary evaporator in series, A high-pressure system comprising a high-pressure steam separator for steam-separating steam generated in the high-pressure secondary evaporator;
An intermediate pressure secondary evaporator installed downstream of the high pressure primary evaporator in the exhaust gas flow direction, an intermediate pressure primary evaporator installed downstream of the intermediate pressure secondary evaporator in the exhaust gas flow direction, and an intermediate pressure thereof An intermediate pressure communication pipe in which a primary evaporator and the intermediate pressure secondary evaporator are connected in series, an intermediate pressure brackish water separator that separates steam generated by the intermediate pressure secondary evaporator, and the intermediate pressure primary evaporator An intermediate pressure system having an intermediate pressure economizer installed downstream of the exhaust gas flow direction of
In a once-through exhaust heat recovery boiler equipped with a low-pressure drum installed in a system that is lower in pressure than the medium-pressure system,
A first can water discharge system for discharging can water from the outlet side of the high pressure primary evaporator to the medium pressure economizer;
A once-through exhaust heat recovery boiler having a second can water discharge system for discharging can water from the outlet side of the intermediate pressure primary evaporator to the low pressure drum. A high-pressure secondary evaporator, a high-pressure primary evaporator installed downstream of the high-pressure secondary evaporator in the exhaust gas flow direction, a high-pressure connecting pipe connecting the high-pressure primary evaporator and the high-pressure secondary evaporator in series, A high-pressure system comprising a high-pressure steam separator for steam-separating steam generated in the high-pressure secondary evaporator;
An intermediate pressure secondary evaporator installed downstream of the high pressure primary evaporator in the exhaust gas flow direction, an intermediate pressure primary evaporator installed downstream of the intermediate pressure secondary evaporator in the exhaust gas flow direction, and an intermediate pressure thereof An intermediate pressure communication pipe in which a primary evaporator and the intermediate pressure secondary evaporator are connected in series, an intermediate pressure brackish water separator that separates steam generated by the intermediate pressure secondary evaporator, and the intermediate pressure primary evaporator An intermediate pressure system having an intermediate pressure economizer installed downstream of the exhaust gas flow direction of
In the once-through exhaust heat recovery boiler equipped with a low-pressure economizer installed in a system that is lower in pressure than the medium-pressure system,
A first can water discharge system for discharging can water from the outlet side of the high pressure primary evaporator to the medium pressure economizer;
A once-through exhaust heat recovery boiler, wherein a second can water discharge system for discharging can water from the outlet side of the intermediate pressure primary evaporator to the low pressure economizer is installed.

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