JP6736501B2 - Marine power generation system, power generation method for marine power generation system, and power generation plant - Google Patents

Description

The present invention relates to a marine power generation system , a power generation method for a marine power generation system , and a power generation plant .

It has been conventionally known that a ship using a propulsion engine applies a system that recovers exhaust heat of exhaust gas discharged from the propulsion engine to generate steam and introduces the steam into a steam turbine or the like. There is. An example of such a ship is disclosed in Patent Document 1.
Patent Document 1 discloses a configuration in which an auxiliary boiler drum also serves as a high-pressure brackish water separator in an exhaust gas heat recovery apparatus for a marine engine, and steam of the high-pressure brackish water separator is sent to a steam turbine.

JP-A-57-49704

By the way, in recent years, adoption of a gas turbine combined cycle (GTCC), which is a power generation system exhibiting high power generation efficiency, into ships is also under study. However, since it is necessary to install various devices such as a steam turbine, an exhaust gas economizer, and a brackish water separator in the gas turbine combined cycle, securing an installation space has been a problem when installing the ship in a limited space. ..
In addition to power generation by the combustion gas of the gas turbine, the gas turbine combined cycle also generates power by recovering exhaust heat from the exhaust gas of the gas turbine and introducing the steam into the steam turbine to generate power. However, when the gas turbine is stopped due to maintenance or the like, exhaust gas is not generated from the gas turbine, so exhaust heat cannot be recovered and steam cannot be generated. Therefore, when the gas turbine is stopped, there is a problem that not only the power generation by the gas turbine but also the power generation by the steam turbine cannot be performed. Further, when the load on the gas turbine is reduced due to a trouble in the gas turbine or the like, exhaust heat of exhaust gas generated from the gas turbine is also reduced. As a result, the exhaust heat that can be recovered from the exhaust gas decreases, and the amount of steam and the steam temperature of the generated steam become insufficient. Therefore, when the load on the gas turbine decreases, the amount of power generated by the steam turbine also decreases accompanying the decrease in the load on the gas turbine, resulting in a significant decrease in the amount of power generated by the entire power generation system.

The present invention has been made in view of such circumstances, and when a power generation system is introduced into a ship, it is possible to realize space saving , a marine power generation system, a power generation method for the marine power generation system , and a power generation plant. The purpose is to provide.
A second object of the present invention is to suitably drive the steam turbine regardless of the operating state of the gas turbine, improve the operating rate of the entire power generation system, and cover the amount of power required by the ship. An object is to provide a marine power generation system, a power generation method for a marine power generation system , and a power generation plant .

In order to solve the above problems , the marine power generation system, the power generation method of the marine power generation system , and the power generation plant of the present invention employ the following means.
A marine power generation system according to an aspect of the present invention includes a gas turbine driven by combustion gas, a first generator driven by the gas turbine to generate power, and heat recovered from exhaust gas discharged from the gas turbine. An exhaust gas economizer for generating steam, a boiler having a furnace and a steam drum, a circulation passage connected so as to use the steam drum as a brackish water separator of the exhaust gas economizer, and a circulating water pump provided in the circulation passage. when a steam turbine driven by steam from said steam drum, and a second generator for generating electric power by being driven by the steam turbine, if not to generate steam in the boiler, activating the circulation water pump And a control unit having an operation mode for supplying water to the exhaust gas economizer .

In the above configuration, the gas turbine outputs the rotational force and drives the first generator to generate electricity. The exhaust heat of the exhaust gas discharged from the gas turbine is recovered by the exhaust gas economizer. The steam generated by the exhaust gas economizer is guided to the steam drum of the boiler through the circulation flow path. The steam drum is used as a brackish water separator to separate steam and water. The water separated by the steam drum is returned to the exhaust gas economizer through the circulation flow path. On the other hand, the steam separated by the steam drum is guided to the steam turbine to drive the steam turbine. When the steam turbine is driven, power is generated by the second generator. The marine power generation system having the above-described configuration generates power in this way.
By the way, a plurality of boilers that are used to generate onboard miscellaneous steam and the like that are required onboard a ship during navigation or while moored are installed in a ship. The inventors of the present invention have paid attention to this boiler as a result of extensive studies. When such a steam drum of a boiler is used as a brackish water separator of an exhaust gas economizer, steam and water can be separated without using a brackish water separator. Therefore, when such a boiler is used as the brackish water separator of the exhaust gas economizer, it is not necessary to separately install a brackish water separator for the exhaust gas economizer, and the cost for installing a separate brackish water separator can be reduced. Space saving can be realized. The boiler used as the brackish water separator may be a newly installed boiler or an existing boiler.
In addition, by using the exhaust gas generated from the boiler as the inert gas, it is not necessary to separately install a device that generates the inert gas, and it is possible to reduce the cost for installing the device that separately generates the inert gas and realize space saving. be able to.
Further, for example, when VOC or a gas having a low calorific value that cannot self-combust is generated, these gases can be appropriately burned by co-firing with oil in the boiler. The energy efficiency of the entire marine power generation system can be improved by appropriately burning the low calorific value gas that cannot self-combust. Moreover, exhaust gas that may affect the environment can be rendered harmless by burning it in the boiler.
The first generator and the second generator may be integrated into one generator.
Further, an exhaust gas economizer may be provided between the steam drum and the steam turbine, and the steam supplied from the steam drum to the steam turbine may be superheated by the exhaust gas economizer. The exhaust gas economizer provided between the steam drum and the steam turbine may also be used as the exhaust gas economizer that generates steam, or may be newly provided separately.

A marine power generation system according to an aspect of the present invention includes a control unit that controls a burner provided in the furnace, and the control unit controls the burner according to a load of the gas turbine as an operation mode of the boiler. It may have a boiler operation mode for ignition.

In the above configuration, the control unit has a boiler operation mode in which the burner provided in the furnace is started according to the load of the gas turbine. By operating in this boiler operation mode, for example, when the load of the gas turbine is lower than a predetermined value and the exhaust gas economizer cannot generate sufficient steam, the burner provided in the furnace is ignited, and the boiler also generates steam. Sufficient steam can be supplied to the steam turbine by performing generation and heating. As a result, the steam turbine can compensate for the amount of power generation that has decreased due to the reduction in the load on the gas turbine. Therefore, stable power generation can be achieved as the entire marine power generation system, and the required power of the marine vessel can be appropriately covered.
Further, for example, even when the gas turbine is stopped due to maintenance of the gas turbine or the like, power can be generated by the steam generated in the boiler. Therefore, the downtime of the marine power generation system can be reduced.

A marine power generation system according to an aspect of the present invention includes a control unit that controls a burner provided in the furnace, and the control unit ignites the burner during a rated operation of the gas turbine as an operation mode of the boiler. It may have a boiler operation mode for

In the above configuration, the control unit has an operation mode in which the burner provided in the furnace is ignited during the rated operation of the gas turbine. Therefore, even when the gas turbine is in the rated operation state and the required electric power further increases, the boiler is started, the steam generated by the exhaust gas economizer is further heated by the boiler, and then supplied to the steam turbine. As a result, the amount of power generated by the steam turbine can be increased, and the increased required power can be covered.

The marine power generation system according to an aspect of the present invention, as an operation mode, by stopping the gas turbine, igniting a burner provided in the furnace, and introducing steam from the steam drum to the steam turbine, A first operation mode in which power is generated only by a second power generator, and the gas turbine is driven to introduce the steam generated by the exhaust gas economizer from the steam drum to the steam turbine, whereby the first power generator is generated. And a control unit having a second operation mode in which power is generated by the second generator, and the control unit may select the operation mode according to the required power of the ship.

In the above configuration, the operation mode is selected according to the amount of power required by the ship. As a result, it is possible to generate the amount of electric power according to the amount of electric power required by the ship.
For example, it is conceivable to operate the marine power generation system in the first operation mode when the power required by the marine vessel is relatively small. When the amount of power required by a ship is relatively small, it is difficult to use a gas turbine that generates a large amount of power, and there is a possibility of excessive power generation. However, if the operation is performed in the first operation mode, only the steam generated by the boiler is used to generate power, which makes it possible to generate less power than the minimum power generation of the gas turbine, thus reducing the required power consumption. Since it is also possible to cope with this, it is possible to generate the amount of electric power according to the required amount of electric power. In this way, since the range that can accommodate the required amount of power can be widened, the power generation efficiency of the marine power generation system as a whole can be improved.
Further, for example, it is conceivable to operate the marine power generation system in the second operation mode when the amount of power required by the marine vessel is relatively large. When the amount of power required by the ship is relatively large, the power required by the first generator is generated by the driving force of the gas turbine, and the power generated by the second generator is generated by the steam generated by the exhaust gas economizer. The amount of electric power can be generated according to the amount.
As described above, based on the required power generation amount, the efficient operation mode for generating the required power generation amount can be selected from the first operation mode and the second operation mode, so that the power generation of the entire marine power generation system is possible. The efficiency can be improved.

In the marine power generation system according to one aspect of the present invention, the control unit, as the operation mode, ignites the burner provided in the furnace, and introduces steam from the steam drum to the steam turbine. It may have a third operation mode in which power is generated by the first generator and the second generator.

In the above configuration, the control unit has, as an operation mode, a third operation mode in which steam is introduced from the steam drum into the steam turbine through the exhaust gas economizer and the furnace of the boiler. Thereby, for example, even when the required power amount of the ship exceeds the power amount that can be generated during the rated operation of the gas turbine, the amount of power generated by the steam turbine can be increased by starting the boiler. Therefore, it is possible to generate the amount of electric power according to the required amount of electric power. In this way, it is possible to generate a larger amount of electric power than the amount of electric power that can be generated during the rated operation of the gas turbine. Therefore, the installation cost of the gas turbine can be reduced.

The marine power generation system according to one aspect of the present invention may include a boiler exhaust gas pipe that guides exhaust gas from the boiler to the exhaust gas economizer.

In the above configuration, since the exhaust gas from the boiler is also introduced into the exhaust gas economizer, it is possible to recover heat from the exhaust gas from the boiler. Also, in order to recover heat from the exhaust gas of the boiler, the exhaust gas economizer for the gas turbine is used, and the exhaust gas economizer for the boiler is not installed separately, so the cost for installing the exhaust gas economizer for the boiler separately is reduced. Therefore, space saving can be realized.

A marine power generation system according to an aspect of the present invention is a boiler exhaust gas economizer that heats steam by recovering heat from exhaust gas discharged from the boiler, and guides the exhaust gas discharged from the boiler to the boiler exhaust gas economizer. A boiler exhaust gas pipe may be provided.

In the above configuration, since the exhaust gas from the boiler is also introduced into the boiler exhaust gas economizer, heat can be recovered from the exhaust gas from the boiler. Further, since the exhaust gas economizer for the gas turbine and the exhaust gas economizer for the boiler are separately provided, for example, even when the boiler and the gas turbine are simultaneously operated, the exhaust gas discharged from the gas turbine is The heat can be recovered without mixing with the exhaust gas discharged from the boiler.

A power generation method for a marine power generation system according to an aspect of the present invention includes a gas turbine driving step in which a gas turbine is driven by combustion gas, and a first power generation step in which power is generated by driving a first generator by the gas turbine. And a steam recovery process for recovering heat from exhaust gas discharged from the gas turbine in an exhaust gas economizer, and a steam drum of a boiler having a furnace and a steam drum for separating the steam obtained in the heat recovery process into brackish water. A separation step, a steam turbine driving step of driving a steam turbine with the steam obtained in the brackish water separation step, a second power generation step of driving a second generator by the steam turbine to generate electric power, and the boiler A water supply step of starting a circulating water pump to supply water to the exhaust gas economizer when steam is not generated .
A power plant according to an aspect of the present invention includes a gas turbine driven by combustion gas, a first generator driven by the gas turbine to generate electric power, and steam by recovering heat from exhaust gas discharged from the gas turbine. An exhaust gas economizer for producing a boiler, a boiler having a furnace and a steam drum, a circulation flow path connected so as to use the steam drum as a brackish water separator of the exhaust gas economizer, and steam driven by steam from the steam drum A turbine, a second generator that is driven by the steam turbine to generate electric power, and an operating mode that stops the gas turbine and ignites a burner provided in the furnace to generate steam from the steam drum to the steam turbine. By introducing the first operation mode in which power is generated only by the second generator, the gas turbine is driven without igniting the burner, and steam generated by the exhaust gas economizer is discharged from the steam drum. A controller having a second operation mode in which the first generator and the second generator generate power by introducing the steam turbine;
And the control unit selects the first operation mode at the first load when the power generation plant requires less power, and sets the second operation mode at the second load when the load is increased as compared to the first load. select.

According to the present invention, it is possible to save space when introducing a power generation system into a ship.
Further, according to the present invention, it is possible to improve the operating rate of the entire marine power generation system and suitably cover the required electric power of the marine vessel.

1 is a schematic configuration diagram showing a marine power generation system according to a first embodiment of the present invention. 3 is a graph showing an example of load sharing of the marine power generation system shown in FIG. 1. 3 is a graph showing an example of load sharing of the marine power generation system shown in FIG. 1. It is a schematic block diagram which shows the ship power generation system concerning 2nd Embodiment of this invention. 5 is a table showing the open/closed states of valves for each operation mode of the marine power generation system shown in FIG. 4. 5 is a graph showing the relationship between the efficiency of the marine power generation system shown in FIG. 4 and the plant load. It is a schematic block diagram which shows the ship power generation system concerning 3rd Embodiment of this invention. It is a schematic block diagram which shows the modification of the marine power generation system shown in FIG.

An embodiment of a marine power generation system , a power generation method for a marine power generation system , and a power generation plant according to the present invention will be described below with reference to the drawings.

[First Embodiment]
Hereinafter, the first embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 1, a power generation plant (marine power generation system) 1 installed on a ship such as an LNG ship is a so-called gas turbine combined cycle (GTCC), and is discharged from a gas turbine 2 and a gas turbine 2. An exhaust gas economizer 3 for recovering heat from exhaust gas, a boiler 4, a steam turbine 5 driven by steam from the boiler 4, and a control unit 6 for controlling the boiler 4 and the like are provided.

The gas turbine 2 combusts fuel in a combustor (not shown) and supplies combustion gas to the turbine to generate rotational power and exhaust high-temperature exhaust gas. The exhaust gas discharged from the gas turbine 2 flows through the exhaust gas pipe 11 and is guided to the exhaust gas economizer 3 as shown by the arrow in FIG. The rotating shaft of the gas turbine 2 is connected to the rotating shaft of the first generator 14, and the first generator 14 generates electric power by the rotating force of the gas turbine 2. The electric power generated by the first generator 14 is supplied to the inboard system and used as the power of the main engine of the ship and the inboard power.

The exhaust gas economizer 3 has a superheater 12 and a steam generator 13 arranged from the upstream side to the downstream side of the exhaust gas flow. The superheater 12 and the steam generator 13 are a heat transfer tube group installed in order from the bottom to the top in the flue. High-temperature exhaust gas introduced from the gas turbine 2 side flows in the flue, and after flowing in the flue, the exhaust gas passes through a chimney (not shown) connected to the downstream side to reach the atmosphere. Is released.

The boiler 4 includes a furnace 16, a steam drum 17 arranged above, and a water drum 18 arranged below. A heat transfer tube (not shown) arranged in the furnace 16 is provided between the steam drum 17 and the water drum 18. The furnace 16 includes a burner 19 and burns in the furnace 16. A boiler superheater 23 is provided in the boiler 4. Fuel is supplied to the burner 19 from a fuel supply unit 20 via a fuel supply pipe 21. A fuel supply valve 22 is provided in the fuel supply pipe 21, and the fuel supply and the fuel supply are stopped by opening and closing the fuel supply valve 22. The valve opening of the fuel supply valve 22 is controlled by the controller 6.
When the burner 19 is ignited in the furnace 16 and the feed water is heated in the boiler 4, the water rises from the lower water drum 18 to the upper steam drum 17, and the gas-liquid is separated by the steam drum 17. .. In this way, the boiler 4 is originally a natural circulation type boiler. However, when used as a brackish water separator of the exhaust gas economizer 3, it is not used as a natural circulation type boiler. A circulating water pipe 26 for supplying water to the upstream end of the steam generator 13 is connected to the steam drum 17. A circulating water pump 27 is provided in the circulating water pipe 26. The circulating water pump 27 is started and stopped by a command from the control unit 6. A brackish water mixing pipe 28 is provided between the downstream end of the steam generator 13 and the steam drum 17. The circulating water pipe 26 and the brackish water mixing pipe 28 described above form a circulating flow path 29 between the steam drum 17 and the steam generator 13, through which water and steam circulate.

The steam that has undergone brackish water separation in the steam drum 17 passes through the steam output pipe 31 and is supplied to the superheater 12 provided in the exhaust gas economizer 3. The steam supplied to the superheater 12 is superheated and introduced into the steam turbine 5 via the steam turbine input pipe 30.

The steam output pipe 31 is provided with a steam output pipe valve 32. A first boiler overheating pipe 33 is branched from an intermediate position on the upstream side of the steam output pipe valve 32 of the steam output pipe 31. The downstream end of the first boiler superheat pipe 33 is connected to the upstream end of the boiler superheater 23 provided in the furnace 16. An upstream end of the second boiler overheating pipe 34 is connected to a downstream end of the boiler superheater 23. The downstream end of the second boiler overheating pipe 34 is connected to an intermediate position on the downstream side of the steam output pipe valve 32 of the steam output pipe 31. Further, a boiler overheating valve 35 is provided in the second boiler overheating pipe 34.

The steam turbine 5 is driven by the steam supplied from the boiler 4. The rotary shaft of the steam turbine 5 is connected to the rotary shaft of the second power generator 37, and the second power generator 37 generates power by the rotational force of the steam turbine 5. The electric power generated by the second generator 37 is supplied to the inboard system and used as the power of the main engine of the ship or the inboard power. The steam supplied from the boiler 4 to the steam turbine 5 may be steam generated by heating water or the like in the boiler 4 or steam generated by the exhaust gas economizer 3 in the boiler 4. There are cases.
A condenser 38 is provided below the steam turbine 5. In the condenser 38, the steam that has passed through the steam turbine 5 is condensed to generate water, and the generated water is recovered as condensate.

The control unit 6 either uses the boiler 4 as an original natural circulation type boiler or stops the operation of the boiler 4 as a natural circulation type boiler depending on the operating condition of the gas turbine 2 to generate a steam drum. It is switched whether to use 17 as a brackish water separator of the steam generator 13. The control unit 6 includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program as an example, and the CPU reads the program into a RAM or the like to execute information processing/arithmetic processing. As a result, various functions are realized. The program is installed in a ROM or other storage medium in advance, provided in a state of being stored in a computer-readable storage medium, or delivered via wired or wireless communication means. Etc. may be applied. The computer-readable storage medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like.

Next, the operation of the power plant 1 having the above configuration will be described.
[In normal operation]
During normal operation of the gas turbine 2, that is, during rated operation, as shown in the graph of FIG. 2, only power generation by the gas turbine 2 and power generation by the steam turbine 5 driven by the steam generated by the exhaust gas economizer 3 are required. Since the electric power required by the power generation plant 1 is covered, it is not necessary to generate steam in the boiler 4. Therefore, the ignition of the burner 19 of the boiler 4 is stopped by the command of the control unit 6.
As described above, during normal operation of the gas turbine 2, the exhaust gas economizer 3 can generate steam. In this case, the steam drum 17 of the boiler 4 is switched to be used as a brackish water separator of the steam generator 13 according to a command from the control unit 6. Specifically, water is supplied from a water supply pipe (not shown) to the steam drum 17, and the circulating water pump 27 is started. As a result, steam is generated in the steam generator 13, steam is separated in the steam drum 17, and the steam is sent to the superheater 12. In the present embodiment, as shown in FIG. 2, the ratio of the power generation amount by the gas turbine 2 during normal operation and the power generation amount by the steam turbine 5 driven by the steam generated by the exhaust gas economizer 3 is 70%. However, this value is an example, and the power generation amount by the gas turbine 2 and the power generation amount by the steam turbine 5 driven by the steam generated by the exhaust gas economizer 3 may be different. Good.

[When gas turbine load is limited]
When the load of the gas turbine 2 is limited due to troubles of the gas turbine 2 or the like during the rated operation, the heat amount of the exhaust gas discharged from the gas turbine 2 is also limited, and a function of generating steam in the exhaust gas economizer 3 Also drops. Specifically, as shown in FIG. 2, when the load on the gas turbine 2 is lower than that during normal operation, the amount of power generation also decreases. Along with this, the amount of power generation by the steam turbine 5 driven by the steam generated by the exhaust gas economizer 3 also decreases. At this time, the boiler 4 is controlled to operate as a natural circulation type boiler by a command from the control unit 6 so as to cover the reduced power generation amount. Specifically, the burner 19 of the boiler 4 is ignited and the feed water is heated in the furnace 16 to generate steam. Further, when the load on the gas turbine 2 is limited due to a trouble or the like as compared with the rated operation, the overheating of the exhaust gas economizer 3 is not appropriately performed. Therefore, when it is desired to suitably superheat the steam and improve the power generation efficiency, the steam output piping valve 32 may be closed and the boiler overheating valve 35 may be opened. By the control unit 6 controlling in this way, the steam from the steam drum 17 is superheated in the boiler superheater 23 in the furnace 16 and the power generation efficiency can be increased. In the present embodiment, as shown in FIG. 2, when the load on the gas turbine 2 is limited, the power generation amount by the gas turbine 2, the power generation amount by the steam turbine 5 driven by the steam generated by the exhaust gas economizer 3, and the boiler 4 are shown. The ratios to the amount of power generated by the steam turbine 5 driven by the steam generated by are 60%, 20%, and 20%, respectively, but these values are examples, and the ratio of each amount of power generation is another ratio. May be

[When the gas turbine is stopped]
When the gas turbine 2 is stopped due to maintenance of the gas turbine 2 or the like, the exhaust gas economizer 3 does not generate steam. However, there may be a demand for electric power from the ship even during the maintenance of the gas turbine 2. Therefore, the boiler 4 is controlled by the instruction of the control unit 6 so as to operate as a natural circulation type boiler. Specifically, the burner 19 of the boiler 4 is ignited, and the feed water is heated in the furnace 16 to generate steam. Further, when the gas turbine 2 is stopped due to maintenance of the gas turbine 2 or the like, the exhaust gas economizer 3 is not overheated. Therefore, when it is desired to superheat the steam and improve the power generation efficiency, the steam output piping valve 32 may be closed and the boiler overheating valve 35 may be opened. By the control unit 6 controlling in this way, the steam from the steam drum 17 is superheated in the boiler superheater 23 in the furnace 16 and the power generation efficiency can be increased.

[When power plant load increases]
When the amount of electric power required for the power generation plant 1 further increases from the state of the gas turbine 2 during the rated operation due to demand from the ship (see FIG. 3 ), the increased required electric power amount is covered, The boiler 4 is controlled by a command from the control unit 6 so as to operate as a natural circulation type boiler. Specifically, the burner 19 of the boiler 4 is ignited and the feed water is heated in the furnace 16 to generate steam. In the present embodiment, as shown in FIG. 3, when the load on the power plant increases, the power generation amount by the gas turbine 2, the power generation amount by the steam turbine 5 driven by the steam generated by the exhaust gas economizer 3, and the boiler 4 are generated. The ratios with the power generation amount by the steam turbine 5 driven by the generated steam are 70%, 30%, and 20%, respectively, but these numerical values are examples, and the ratios of the respective power generation amounts are different ratios. May be.

According to this embodiment, the following operational effects are exhibited.
In the present embodiment, the control unit 6 controls the start and stop of the burner 19 provided in the furnace 16 according to the load of the gas turbine 2. As a result, even if the load on the gas turbine 2 is limited, the burner 19 provided in the furnace 16 is ignited, and the steam generation and heating in the boiler 4 are sufficient to the steam turbine 5. Steam can be supplied. Therefore, the steam turbine 5 can compensate for the amount of power generation that has decreased due to the reduction in the load on the gas turbine 2. Therefore, stable power generation can be performed as the entire power generation plant 1, and the required power of the ship can be appropriately covered.
Further, for example, even when the gas turbine 2 is stopped due to maintenance of the gas turbine 2 or the like, the boiler 4 can generate power. Therefore, the downtime of the power plant 1 can be reduced.
Further, even when the gas turbine 2 is in the rated operation state and the required electric power further increases, the boiler 4 is started to further heat the steam generated by the exhaust gas economizer 3 by the boiler 4, It can be supplied to the turbine 5. Moreover, since the amount of steam generated in the exhaust gas economizer 3 increases, the amount of steam supplied to the steam turbine 5 increases. Therefore, the amount of power generation by the steam turbine 5 is increased, and the required power generated can be covered.
Also, by using the exhaust gas generated from the boiler 4 as the inert gas, it is not necessary to separately install a device that generates the inert gas, and it is possible to reduce the cost for installing the device that separately generates the inert gas and realize space saving. can do.
Further, when a gas with a low calorific value that cannot self-combust such as VOC is generated, the gas with a low calorific value that cannot self-combust can be appropriately burned by co-firing with oil in the boiler 4. By appropriately combusting a low calorific value gas that cannot self-combust, the energy efficiency of the entire power generation plant 1 can be improved. Moreover, the exhaust gas that may affect the environment can be rendered harmless by burning it in the boiler 4.
Further, when an existing auxiliary boiler is used for the ship as the boiler 4, there is no need to separately install a brackish water separator for the exhaust gas economizer 3, and the cost for installing a separate brackish water separator can be reduced, Space saving can be realized. In addition, when the auxiliary boiler is used, a part of the steam from the auxiliary boiler is sent to a customer onboard the ship (for example, an oil heating device).

[Second Embodiment]
The second embodiment of the present invention will be described below with reference to FIG.
The present embodiment basically has the same structure as the first embodiment, but the structure of the pipe connecting the steam drum 17 and the steam turbine 5 is different. Therefore, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.
As shown in FIG. 4, the steam output pipe 51 connecting the steam drum 17 and the superheater 12 has a second valve B2 (the second valve B2 is located at the same position as the steam output pipe valve 32 of the first embodiment). However, the third valve is attached to the steam turbine input pipe 52 that connects the superheater 12 and the steam turbine 5 to each other because the use of the steam turbine input pipe 52 is different. B3 is provided. A bypass pipe 53 branches off from the upstream side of the second valve B2 of the steam output pipe 51. The bypass pipe 53 is provided with the first valve B1 and is connected to a connection point P1 located at an intermediate position of the steam turbine input pipe 52 and upstream of the third valve B3. A branch point P2 is provided between the connection point P1 of the steam turbine input pipe 52 and the third valve, and a boiler heating tube 54 branches from the branch point P2. The boiler superheater pipe 54 is provided with the boiler superheater 23 and the fourth valve B4 arranged in the furnace 16 in order from the upstream side of the above flow, and the downstream end thereof is connected to the third valve B3 of the steam turbine input pipe 52 and the steam. It is connected to an intermediate position between the turbine 5 and the turbine 5.

Next, the operation of the power plant 1 having the above configuration will be described.
[Operation mode when the load on the power plant is low (first operation mode)]
When the load on the power plant 1 is low, that is, when the amount of electric power required by the ship is small, the control unit 6 stops the gas turbine 2 and, as shown in FIG. 5, the first valve B1 and the fourth valve B1. The valve B4 is opened and the second valve B2 and the third valve B3 are closed. Further, according to a command from the control unit 6, the boiler 4 is controlled to operate as a natural circulation type boiler. Specifically, the burner 19 of the boiler 4 is ignited and the feed water is heated in the furnace 16 to generate steam. By controlling in this way, the steam generated in the boiler 4 is superheated through the boiler superheater 23 in the boiler 4, and the superheated steam drives the steam turbine 5. In this way, it is possible to generate electricity by operating the boiler 4 alone.

[Operation mode when the power plant has a medium load (second operation mode)]
When the load of the power generation plant 1 is higher than that when the load is low, that is, when the power generation plant has a medium load, the control unit 6 starts the gas turbine 2 and, as shown in FIG. 5, the second valve B2 and the third valve B2. B3 is opened and the first valve B1 and the fourth valve B4 are closed. Further, according to a command from the control unit 6, the boiler 4 is stopped and the steam drum 17 of the boiler 4 is switched to be used as a steam separator of the steam generator 13. Specifically, the ignition of the burner 19 of the boiler 4 is stopped, water is supplied from the water supply pipe to the steam drum 17, and the circulating water pump 27 is started.

[Operation mode at high load of power plant (third operation mode)]
When the power generation plant 1 has a high load, that is, the power generation amount that exceeds the total power generation amount that can be generated by the rated operation of the gas turbine 2 and the steam generated by the exhaust heat of the gas turbine is exceeded. If it is necessary, the control unit 6 opens the second valve B2 and the fourth valve B4 and closes the first valve B1 and the third valve B3, as shown in FIG. Further, the boiler 4 is activated again, and the boiler 4 is controlled to operate as a natural circulation type boiler. Specifically, the burner 19 of the boiler 4 is ignited, the feed water is heated in the furnace 16 to generate steam, and the steam introduced into the steam turbine 5 is superheated.

Next, switching between the above operation modes in the present embodiment will be described.
As shown in FIG. 6, switching from the operation mode M1 when the power plant has a low load to the operation mode M2 when the power plant has a medium load is performed by changing the power generation efficiency in the operation mode at the medium load to the power generation efficiency in the operation mode at the low load. Switching is performed at the switching point A1 which is higher than the above. In the present embodiment, as shown in FIG. 6, switching is performed when the power plant load is 25%. In addition, the switching point from the operation mode at the time of low load of the power generation plant to the operation mode at the time of medium load of the power generation plant is the scale of the gas turbine 2, the scale of the steam turbine 5, the scale of the boiler 4, the steam condition (steam pressure). And the steam temperature) and the like, and the switching point may be other than 25%.

According to this embodiment, the following operational effects are exhibited.
In this embodiment, the operation mode is selected according to the power plant load (necessary electric power of the ship). As a result, it is possible to generate the amount of electric power according to the amount of electric power required by the ship.
Specifically, when the amount of power required by the ship is relatively small, it is difficult for the gas turbine 2 that generates a large amount of power to handle it, and there is a possibility that power will be excessively generated. Moreover, when the amount of power generation is reduced to the required amount of power, inefficient operation may occur. However, if the power plant is operated in the low load operation mode, it is possible to generate electric power only with the steam generated by the boiler 4 that generates a smaller amount of electric power than the gas turbine 2. Amount of electricity can be generated. Further, even when the amount of electric power required for the ship exceeds the amount of electric power that can be generated during the rated operation of the gas turbine 2, if the operation is performed in the operation mode under high load of the power plant, the boiler 4 can be started. The amount of power generated by the steam turbine 5 can be increased, and the amount of power according to the required amount of power can be generated.
In this way, the range that can accommodate the required amount of power of the ship can be widened, so that the power generation efficiency of the power generation plant 1 as a whole can be improved.

[Third Embodiment]
The third embodiment of the present invention will be described below with reference to FIG.
The present embodiment basically has the same structure as the second embodiment, and is different in that some configurations are added. Therefore, the same components as those in the second embodiment are designated by the same reference numerals and the description thereof will be omitted.
As shown in FIG. 7, the power generation plant 1 of this embodiment includes a boiler exhaust gas pipe 61 that guides the exhaust gas from the boiler 4 to the exhaust gas economizer 3. With such a configuration, heat can be recovered from the exhaust gas of the boiler 4. Moreover, in order to recover heat from the exhaust gas of the boiler 4, the exhaust gas economizer 3 for the gas turbine 2 is used, and the exhaust gas economizer for the boiler 4 is not separately installed, so an exhaust gas economizer for the boiler 4 is installed separately. Therefore, the cost can be reduced, and the space can be saved. Further, since the temperatures of the exhaust gas from the gas turbine 2 and the exhaust gas from the boiler 4 are about the same, it is possible to share the exhaust gas economizer between the gas turbine 2 and the boiler 4 without providing a heat-resistant material or the like on the exhaust gas economizer 3. You can Further, in the exhaust gas economizer 3, only the exhaust gas from the boiler 4 flows when the load is low, and only the exhaust gas from the gas turbine 2 flows when the load is medium. Therefore, even if the exhaust gas economizer is shared, the exhaust gas from the gas turbine 2 and the exhaust gas from the boiler 4 do not mix at the time of low load and medium load.
As shown in FIG. 8, a boiler exhaust gas economizer 71 may be provided at an intermediate position of the steam output pipe 51, and a boiler exhaust gas pipe 72 may be provided to guide the exhaust gas from the boiler 4 to the boiler exhaust gas economizer 71. With such a configuration, even when the boiler 4 and the gas turbine 2 are simultaneously operated, the exhaust gas discharged from the gas turbine 2 and the exhaust gas discharged from the boiler 4 are mixed. Heat can be recovered without.

The present invention is not limited to the invention according to each of the above-described embodiments, and can be appropriately modified without departing from the scope of the invention. For example, in each of the above-described embodiments, the generator driven by the rotational force of the gas turbine 2 and the generator driven by the rotational force of the steam turbine 5 are separately provided as the first generator 14 and the second generator 37. However, the rotating shafts of the gas turbine 2 and the steam turbine 5 may be one shaft, or the rotating shafts may be connected by gears so that the first generator 14 and the second generator 37 may be combined into one generator. Good.
It is also possible to use the above-described embodiments in combination as appropriate. Specifically, the boiler exhaust gas pipe 61 shown in FIG. 7, the boiler exhaust gas pipe 72 and the boiler exhaust gas economizer 71 shown in FIG. 8 may be provided in the embodiment shown in FIG.

1 Power plant (marine power generation system)
2 Gas Turbine 3 Exhaust Gas Economizer 4 Boiler 5 Steam Turbine 6 Control Unit 14 First Generator 16 Furnace 17 Steam Drum 19 Burner 29 Circulation Flow Path 37 Second Generator 61 Boiler Exhaust Gas Pipe 71 Boiler Exhaust Gas Economizer 72 Boiler Exhaust Gas Pipe B1 First valve B2 Second valve B3 Third valve B4 Fourth valve

Claims (13)

A gas turbine driven by combustion gas,
A first generator that is driven by the gas turbine to generate electric power; and an exhaust gas economizer that generates steam by recovering heat from the exhaust gas discharged from the gas turbine,
A boiler having a furnace and a steam drum,
A circulation flow path connected to use the steam drum as a brackish water separator of the exhaust gas economizer,
A circulating water pump provided in the circulation passage,
A steam turbine driven by steam from the steam drum,
A second generator driven by the steam turbine to generate electricity;
A control unit having an operation mode of starting the circulating water pump to supply water to the exhaust gas economizer when steam is not generated in the boiler . A control unit for controlling a burner provided in the furnace,
The marine power generation system according to claim 1, wherein the control unit has, as an operation mode of the boiler, a boiler operation mode in which the burner is ignited according to a load of the gas turbine. A control unit for controlling a burner provided in the furnace,
The marine power generation system according to claim 1 or 2, wherein the control unit has, as an operation mode of the boiler, a boiler operation mode in which the gas turbine ignites the burner during a rated operation. In the operation mode, the gas turbine is stopped, the burner provided in the furnace is ignited, and steam is introduced into the steam turbine from the steam drum to generate power only by the second generator. Mode, by driving the gas turbine without igniting the burner and introducing the steam generated by the exhaust gas economizer from the steam drum to the steam turbine, the first generator and the second generator A control unit having a second operation mode in which power is generated by the generator,
The marine power generation system according to claim 1, wherein the control unit selects the operation mode according to the required power of the marine vessel. The control unit selects the first operation mode at a first load when the power required by the ship is small, and selects the second operation mode at a second load when the load is larger than that at the first load. Item 4. The marine power generation system according to Item 4. In the operation mode, the control unit ignites the burner provided in the furnace and introduces steam from the steam drum into the steam turbine, so that the first generator and the second generator are operated. The marine power generation system according to claim 4, which has a third operation mode in which power is generated. In the operation mode, the control unit ignites the burner provided in the furnace and introduces steam from the steam drum into the steam turbine, so that the first generator and the second generator are operated. The marine power generation system according to claim 5, which has a third operation mode in which power is generated. The marine power generation system according to claim 7, wherein the control unit selects the third operation mode at a third load when the load is higher than at the second load. The marine power generation system according to claim 4, further comprising a boiler exhaust gas pipe that guides exhaust gas from the boiler to the exhaust gas economizer. An exhaust gas economizer for a boiler that heats steam by recovering heat from the exhaust gas discharged from the boiler,
The marine power generation system according to any one of claims 4 to 8, further comprising: a boiler exhaust gas pipe that guides exhaust gas discharged from the boiler to the boiler exhaust gas economizer. A boiler superheat pipe that connects the steam drum and the steam turbine, and guides the steam discharged from the steam drum to the steam turbine,
A boiler superheater provided in the boiler superheat pipe,
The marine power generation system according to any one of claims 1 to 10, wherein the boiler superheater is arranged in the furnace. A gas turbine driving process in which the gas turbine is driven by the combustion gas,
A first power generation step of generating power by driving a first power generator by the gas turbine;
A heat recovery step of recovering heat in the exhaust gas economizer from the exhaust gas discharged from the gas turbine;
By the steam drum of a boiler having a furnace and a steam drum, a brackish water separation step of separating the steam obtained in the heat recovery step into brackish water,
A steam turbine driving step of driving a steam turbine with the steam obtained in the brackish water separation step,
A second power generation step of driving a second power generator by the steam turbine to generate power ;
A water supply step of activating a circulating water pump to supply water to the exhaust gas economizer when steam is not generated in the boiler . A gas turbine driven by combustion gas,
A first generator driven by the gas turbine to generate electricity;
An exhaust gas economizer that generates steam by recovering heat from the exhaust gas discharged from the gas turbine,
A boiler having a furnace and a steam drum,
A circulation flow path connected to use the steam drum as a brackish water separator of the exhaust gas economizer,
A steam turbine driven by steam from the steam drum,
A second generator driven by the steam turbine to generate electricity;
In the operation mode, the gas turbine is stopped, the burner provided in the furnace is ignited, and steam is introduced into the steam turbine from the steam drum to generate power only by the second generator. Mode, by driving the gas turbine without igniting the burner and introducing the steam generated by the exhaust gas economizer from the steam drum to the steam turbine, the first generator and the second generator A control unit having a second operation mode in which power is generated by a generator;
Equipped with
A power plant in which the control unit selects the first operation mode when the first load requires less power and selects the second operation mode when the second load is greater than the first load .

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