JP2024166830A - Boiler system and method for operating the boiler system - Google Patents

Abstract

To properly vaporize liquid ammonia fuel without causing the flow-out of the ammonia fuel to the outside and the lowering of thermal efficiency.SOLUTION: There is provided a boiler system 100 which comprises: a boiler 10 for producing steam by combusting ammonia fuel containing ammonia by an ammonia combustion burner; a first fuel supply system 210 for supplying the ammonia fuel to the ammonia fuel burner; a steam turbine rotationally driven by the steam which is produced by the boiler 10; a water supply system driven by the steam extracted from the steam turbine, having a boiler water supply pump 123 for supplying boiler water to the boiler 10; a discharge system 250 for discharging the steam which has driven the boiler water supply pump 123 to the water supply system; and an ammonia vaporizer 251 for vaporizing the liquid ammonia fuel which circulates in the first fuel supply system 210 by a heat exchange with the steam which circulates in the discharge system.SELECTED DRAWING: Figure 3

Description

This disclosure relates to a boiler system and a method for operating a boiler system.

In recent years, a technology that uses ammonia fuel as fuel to generate steam to drive generators and the like has been proposed as an effective technology for decarbonization (see, for example, Patent Document 1). The power generation system disclosed in Patent Document 1 includes a condenser that condenses the steam discharged from the steam turbine through heat exchange with seawater, and a vaporizer that vaporizes liquid ammonia fuel through heat exchange with seawater heated by the condenser.

JP 2020-148357 A

In Patent Document 1, if a failure occurs in the vaporizer that exchanges heat between seawater and liquid ammonia fuel, the ammonia fuel may mix with the seawater and flow out, potentially affecting the environment. In addition, if the temperature of the seawater is low relative to the steam discharged from the steam turbine, it may be difficult to heat the ammonia fuel with the seawater to a temperature sufficient to vaporize it. In this case, if some of the steam used in the steam turbine is extracted and used to vaporize the ammonia in order to make up for the lack of heat required to vaporize the ammonia fuel, the thermal efficiency of the power generation system will decrease.

The present disclosure has been made in consideration of these circumstances, and aims to provide a boiler system and a method for operating a boiler system that can appropriately vaporize liquid ammonia fuel without causing the ammonia fuel to leak to the outside or reducing thermal efficiency.

In order to solve the above problems, the present disclosure employs the following solutions.
A boiler system according to the present disclosure includes a boiler that generates steam by burning ammonia fuel containing ammonia using a burner, an ammonia fuel supply system that supplies the ammonia fuel to the burner, a steam turbine that is rotationally driven by the steam generated in the boiler, a feedwater system that is driven by the steam extracted from the steam turbine and supplies boiler water to the boiler, a discharge system that discharges the steam that has driven the feedwater pump to the feedwater system, and an ammonia vaporizer that vaporizes the liquid ammonia fuel flowing through the ammonia fuel supply system by heat exchange with the steam flowing through the discharge system.

In the method of operating a boiler system according to the present disclosure, the boiler system includes a boiler that burns ammonia fuel containing ammonia using a burner to generate steam, an ammonia fuel supply system that supplies the ammonia fuel to the burner, a steam turbine that is driven to rotate by the steam generated in the boiler, a feedwater system that is driven by the steam extracted from the steam turbine and has a feedwater pump that supplies boiler water to the boiler, and an exhaust system that discharges the steam that has driven the feedwater pump to the feedwater system, and includes an ammonia vaporization process that exchanges heat between the steam flowing through the exhaust system and a liquid flowing through the ammonia fuel supply system, and vaporizes the ammonia fuel in the liquid flowing through the ammonia fuel supply system.

The present disclosure provides a boiler system and a method for operating a boiler system that can appropriately vaporize liquid ammonia fuel without causing the ammonia fuel to leak to the outside or reducing thermal efficiency.

FIG. 1 is a schematic configuration diagram showing a boiler according to a first embodiment of the present disclosure. 1 is a schematic diagram showing a boiler water circulation system in a boiler system according to a first embodiment of the present disclosure. FIG. 1 is a schematic configuration diagram showing a first fuel supply system and a discharge system in a boiler system according to a first embodiment of the present disclosure. FIG. FIG. 11 is a schematic configuration diagram showing a first fuel supply system and a discharge system in a boiler system according to a second embodiment of the present disclosure.

First Embodiment
Hereinafter, a boiler system according to a first embodiment of the present disclosure will be described with reference to the drawings. Note that the present disclosure is not limited to this embodiment, and when there are a plurality of embodiments, the present disclosure also includes a configuration in which each embodiment is combined. In the following description, up and above refer to the upper side in the vertical direction, and below and below refer to the lower side in the vertical direction, and the vertical direction is not precise and includes an error.

Figure 1 is a schematic diagram showing a boiler 10 according to a first embodiment of the present disclosure. The boiler 10 of this embodiment is a boiler that can burn pulverized fuel made by pulverizing solid fuel and ammonia fuel containing ammonia using a burner, and exchange the heat generated by this combustion with feed water or steam to generate superheated steam. Biomass fuel, coal, etc. are used as the solid fuel.

The boiler 10 has a furnace 11, a combustion device 20, and a combustion gas passage 12. The furnace 11 has a hollow rectangular cylinder shape and is installed vertically. The furnace wall 11a that constitutes the inner wall surface of the furnace 11 is composed of multiple heat transfer tubes and fins that connect the heat transfer tubes to each other, and recovers the heat generated by the combustion of pulverized fuel by heat exchange with water and steam flowing inside the heat transfer tubes, while suppressing the temperature rise of the furnace wall 11a.

The combustion device 20 is installed in the lower region of the furnace 11. The combustion device 20 of this embodiment has a plurality of pulverized fuel burners (second burners) 21A, 21B, 21C (hereinafter, sometimes collectively referred to as "pulverized fuel burners 21") attached to the furnace wall 11a, and an ammonia fuel burner (first burner) 210A. The pulverized fuel burners 21 are arranged in a plurality of vertical stages (three stages in the example shown in FIG. 1), with each set consisting of those arranged at equal intervals along the circumferential direction of the furnace 11 (for example, four burners installed at each corner of the rectangular furnace 11). The ammonia fuel burners 210A are arranged in one stage or multiple stages (one stage in the example shown in FIG. 1), with each set consisting of those arranged at equal intervals along the circumferential direction of the furnace 11 (for example, four burners installed at each corner of the rectangular furnace 11).

In FIG. 1, only two of the set of pulverized fuel burners 21 are shown, and each set is designated by the reference numerals 21A, 21B, and 21C. The shape of the furnace 11, the number of burner stages, the number of burners in one stage, the arrangement of the burners, etc. are not limited to this embodiment.

The pulverized fuel burners 21A, 21B, and 21C are each connected to a plurality of pulverized fuel supply units 31A, 31B, and 31C (hereinafter, sometimes collectively referred to as "pulverized fuel supply units 31") via a plurality of pulverized fuel supply pipes 22A, 22B, and 22C (hereinafter, sometimes collectively referred to as "pulverized fuel supply pipes 22").

The pulverized fuel supply units 31A, 31B, and 31C are, for example, vertical roller mills in which a grinding table (not shown) is supported internally so that it can be driven and rotated, and a number of grinding rollers (not shown) are supported above the grinding table so that they can rotate in conjunction with the rotation of the grinding table. The solid fuel pulverized by the cooperation of the grinding rollers and the grinding table is transported to a classifier (not shown) provided in the pulverized fuel supply units 31A, 31B, and 31C by primary air (carrier gas, oxidizing gas) supplied to the pulverized fuel supply units 31A, 31B, and 31C.

The classifier separates the fuel into pulverized fuel with a particle size smaller than that suitable for combustion in the pulverized fuel burners 21A, 21B, and 21C, and coarse fuel with a larger particle size. The pulverized fuel passes through the classifier and is supplied to the pulverized fuel burners 21A, 21B, and 21C via the pulverized fuel supply pipes 22A, 22B, and 22C together with primary air. The coarse fuel that does not pass through the classifier falls by its own weight onto the grinding table inside the pulverized fuel supply units 31A, 31B, and 31C, where it is re-ground.

The first fuel supply system (ammonia fuel supply system) 210 is a device that supplies ammonia fuel containing ammonia to the ammonia fuel burner 210A. The ammonia fuel is supplied to the ammonia fuel burner 210A via a fuel supply pipe 210a. The supply of ammonia fuel including the first fuel supply system 210 will be described later.

In the boiler system 100 of this embodiment, the boiler 10 burns ammonia fuel (first fuel) using the ammonia fuel burner 210A (first burner) and burns pulverized fuel (second fuel) using the pulverized fuel burners (second burners) 21A, 21B, and 21C to generate steam. Note that the number and arrangement of the ammonia fuel burners (first burners) 210A and the pulverized fuel burners (second burners) 21 are not limited to the form shown in FIG. 1.

In the boiler system 100 of this embodiment, the first fuel supply system 210 is a system that supplies ammonia fuel to the ammonia fuel burner 210A. In addition, in the boiler system 100 of this embodiment, the pulverized fuel supply units 31A, 31B, 31C and the pulverized fuel supply pipes 22A, 22B, 22C are a system (second fuel supply system) that supplies pulverized fuel to the pulverized fuel burners 21A, 21B, 21C.

At the installation position of the pulverized fuel burner 21 and the ammonia fuel burner 210A, an air register 23 is provided outside the furnace 11, and one end of an air duct 24 is connected to the air register 23. A forced draft fan (FDF) 32 is connected to the other end of the air duct 24. The air supplied from the forced draft fan 32 is heated by an air preheater 42 installed in the air duct 24 (details will be described later), and is supplied to the pulverized fuel burner 21 via the air register 23 as secondary air (combustion air, oxidizing gas), and is introduced into the furnace 11.

The combustion gas passage 12 is connected to the vertical upper part of the furnace 11. The combustion gas passage 12 is provided with superheaters 102A, 102B, and 102C (hereinafter, sometimes collectively referred to as "superheaters 102"), reheaters 103A and 103B (hereinafter, sometimes collectively referred to as "reheaters 103"), and a coal economizer 104 as heat exchangers for recovering heat from the combustion gas, and heat is exchanged between the combustion gas generated in the furnace 11 and the feed water or steam flowing inside each heat exchanger. The arrangement and shape of each heat exchanger are not limited to the form shown in FIG. 1.

The downstream side of the combustion gas passage 12 is connected to the flue 13, through which the combustion gas whose heat has been recovered by the heat exchanger is discharged. An air preheater (air heater) 42 is provided between the flue 13 and the wind duct 24, and heat is exchanged between the air flowing through the wind duct 24 and the combustion gas flowing through the flue 13. By heating the primary air supplied to the pulverized fuel supply units 31A, 31B, and 31C and the secondary air supplied to the pulverized fuel burner 21 and the ammonia fuel burner 210A, further heat is recovered from the combustion gas after heat exchange with water and steam.

A denitration device 43 may be provided in the flue 13 at a position upstream of the air preheater 42. The denitration device 43 supplies a reducing agent, such as ammonia or urea water, that has the effect of reducing nitrogen oxides to the combustion gas flowing through the flue 13, and promotes the reaction between the nitrogen oxides (NOx) in the combustion gas to which the reducing agent has been supplied and the reducing agent through the catalytic action of a denitration catalyst installed in the denitration device 43, thereby removing and reducing the nitrogen oxides in the combustion gas.

A gas duct 41 is connected downstream of the air preheater 42 of the flue 13. The gas duct 41 is provided with environmental equipment such as a dust collector 44, such as an electrostatic precipitator, which removes ash from the combustion gas, and a desulfurization device 46, which removes sulfur oxides, as well as an induced draft fan (IDF) 45 for directing the exhaust gas to these environmental equipment. The downstream end of the gas duct 41 is connected to a chimney 47, and the combustion gas treated by the environmental equipment is discharged outside the system as exhaust gas.

In the boiler 10, when the pulverized fuel supply units 31A, 31B, and 31C are driven, pulverized fuel is supplied to the pulverized fuel burners 21A, 21B, and 21C together with the primary air via the pulverized fuel supply pipes 22A, 22B, and 22C. Secondary air heated by the air preheater 42 is supplied to the pulverized fuel burners 21A, 21B, and 21C from the air duct 24 through the wind box 23. The pulverized fuel burners 21A, 21B, and 21C blow a pulverized fuel mixture, which is a mixture of fuel and primary air, into the furnace 11, and also blow secondary air into the furnace 11.

When ammonia fuel is used in the boiler 10, ammonia fuel is supplied from the first fuel supply system 210 to the ammonia fuel burner 210A via the fuel supply pipe 210a. Secondary air heated in the air preheater 42 is supplied to the ammonia fuel burner 210A from the air duct 24 via the wind box 23. The ammonia fuel burner 210A blows ammonia fuel into the furnace 11 and also blows secondary air into the furnace 11.

The pulverized fuel mixture and ammonia fuel injected into the furnace 11 ignite and react with the secondary air to form a flame. A flame is formed in the lower region of the furnace 11, and high-temperature combustion gas rises inside the furnace 11 and flows into the combustion gas passage 12. In this embodiment, air is used as the oxidizing gas (primary air, secondary air), but the oxidizing gas may have a higher or lower oxygen content than air. By adjusting the ratio of the amount of oxygen to the amount of fuel supplied to an appropriate range, stable combustion is achieved in the furnace 11.

The combustion gas that flows into the combustion gas passage 12 exchanges heat with water and steam in the superheater 102, reheater 103, and economizer 104 arranged inside the combustion gas passage 12, and is then discharged into the flue 13, where nitrogen oxides are removed in the denitration device 43, and the gas exchanges heat with primary air and secondary air in the air preheater 42, before being discharged into the gas duct 41, where ash and other particles are removed in the dust collector 44, and sulfur oxides are removed in the desulfurization device 46, before being discharged from the chimney 47 to the outside of the system. Note that the arrangement of each heat exchanger in the combustion gas passage 12 and each device from the flue 13 to the gas duct 41 does not necessarily have to be in the order described above with respect to the combustion gas flow.

Next, a configuration will be described in which boiler water is supplied to the boiler 10 in a boiler system 100 including the boiler 10, and steam is generated from the boiler water and supplied to the steam turbine 111. FIG. 2 is a schematic diagram showing a boiler water circulation system in the boiler system 100 according to the first embodiment of the present disclosure. Note that FIG. 2 does not accurately show the positions of each heat exchanger (superheaters 102A, 102B, 102C, reheaters 103A, 103B, economizer 104) in the combustion gas passage 12, and the arrangement order of each heat exchanger relative to the combustion gas flow is not limited to that shown in FIG. 2.

As shown in FIG. 2, the boiler system 100 of this embodiment includes a heat exchanger provided in the boiler 10, a steam turbine 111 that is rotationally driven by steam generated in the boiler 10, and a generator 113 that is connected to the steam turbine 111 and generates electricity using the rotational force of the steam turbine 111.

The steam turbine 111 is composed of, for example, a high-pressure turbine 111A, an intermediate-pressure turbine 111B, and a low-pressure turbine 111C. The steam heated by the superheater 102 of the boiler 10 drives the high-pressure turbine 111A, is then reheated by the reheater 103 of the boiler 10, and drives the intermediate-pressure turbine 111B and the low-pressure turbine 111C. A condenser 112 is connected to the low-pressure turbine 111C, and the steam that drives the low-pressure turbine 111C is condensed by heat exchange with cooling water (e.g., seawater or river water) in the condenser 112 to become condensed water.

The condenser 112 is connected to the economizer 104 via a water supply line L1. For example, a condensate pump 121, a low-pressure feedwater heater 122, a boiler feedwater pump 123, and a high-pressure feedwater heater 124 are provided on the water supply line L1. A portion of the steam that drives the steam turbine 111 is extracted and supplied to the low-pressure feedwater heater 122 and the high-pressure feedwater heater 124 via an extraction line (not shown) as a heat source, and the feedwater supplied to the economizer 104 is heated.

The boiler system 100 includes a feedwater line L1, a condensate pump 121, a low-pressure feedwater heater 122, and a boiler feedwater pump 123, which constitute a feedwater system 240 that supplies boiler water to the boiler 10. As shown in FIG. 2, the boiler feedwater pump 123 has a pump section 123a that supplies boiler water to the boiler 10, and a turbine section 123b that drives the pump section 123a. The turbine section 123b is driven to rotate by steam supplied from the outlet of the intermediate pressure turbine 111B via the extraction line L6. The pump section 123a operates by power transmitted from the turbine section 123b, and supplies the boiler water circulating through the feedwater line L1.

A control valve 127 is disposed in the extraction line L6. The control valve 127 adjusts the flow rate of steam extracted from the outlet of the intermediate pressure turbine 111B via the extraction line L6 to the turbine section 123b of the boiler feedwater pump 123.

For example, the case where the boiler 10 is a once-through boiler will be described. The economizer 104 is connected to the heat transfer tubes that constitute the furnace wall 11a. The feed water heated by the economizer 104 is heated by radiation from the flame in the furnace 11 as it passes through the heat transfer tubes that constitute the furnace wall 11a, and is led to the steam separator 125. The steam separated by the steam separator 125 is supplied to the superheater 102, and the drain water separated by the steam separator 125 flows into the steam separator drain tank 126 and is led to the condenser 112 via the drain water line L2.

When the combustion gas flows through the combustion gas passage 12, the heat of this combustion gas is recovered by the superheater 102, the reheater 103, and the economizer 104. Meanwhile, the feed water supplied from the boiler feed pump 123 is preheated by the economizer 104, and then heated to steam as it passes through the heat transfer tubes that make up the furnace wall 11a, and is then led to the steam separator 125. The steam separated by the steam separator 125 is introduced into the superheaters 102A, 102B, and 102C, where it is superheated by the combustion gas.

The superheated steam generated by the superheater 102 is supplied to the high-pressure turbine 111A via the steam line L3, and drives the high-pressure turbine 111A. The steam discharged from the high-pressure turbine 111A is introduced to the reheater 103A and the reheater 103B via the steam line L4, and is superheated again. The resuperheated steam is supplied to the low-pressure turbine 111C via the intermediate-pressure turbine 111B via the steam line L5, and drives the intermediate-pressure turbine 111B and the low-pressure turbine 111C. The rotating shaft of the steam turbine 111 drives the generator 113 to generate electricity. The steam discharged from the low-pressure turbine 111C is cooled in the condenser 112 to become condensed water, and is sent again to the economizer 104 via the water supply line L1.

Next, a configuration for vaporizing liquid ammonia fuel using heat from the steam that drives the boiler feed water pump 123 and supplying it to the ammonia fuel burner 210A will be described with reference to Figures 2 and 3. Figure 3 is a schematic diagram showing the first fuel supply system 210 and the exhaust system 250 in the boiler system 100 according to the first embodiment of the present disclosure.

2 and 3, the boiler system 100 includes a discharge line L7, a discharge line (first discharge line) L8 branched off from the discharge line L7, and a discharge line (second discharge line) L9, which constitute a discharge system 250 that discharges the steam that drives the boiler feedwater pump 123 to the feedwater system 240. An ammonia vaporizer 251 and an ammonia preheater 252 are disposed in the discharge line L8 of the discharge system 250. A first adjustment valve 253 is disposed in the discharge line L8, and a second adjustment valve 254 is disposed in the discharge line L9.

The discharge line L8 is a pipe that guides a portion of the steam that drives the boiler feedwater pump 123 to the condenser 112 via the ammonia vaporizer 251 and the ammonia preheater 252. The discharge line L9 is a pipe that guides another portion of the steam that drives the boiler feedwater pump 123 directly to the condenser 112 without passing through the ammonia vaporizer 251 and the ammonia preheater 252. The ratio of the amount of steam supplied from the discharge line L7 to the discharge line L8 and the amount of steam supplied from the discharge line L7 to the discharge line L9 is adjusted by the opening of the first adjustment valve 253 and the second adjustment valve 254.

The ammonia vaporizer 251 is, for example, a shell-and-tube type heat exchanger. Steam that drives the boiler feed water pump 123 is supplied to the ammonia vaporizer 251 via the exhaust line L7 and the exhaust line L8. The temperature of the steam introduced into the ammonia vaporizer 251 is, for example, in the range of 40°C or higher and 80°C or lower.

The liquid ammonia fuel stored in the ammonia tank 260 is pumped by the feed pump 211 and flows through the fuel supply pipe 210a. The liquid ammonia fuel flowing through the fuel supply pipe 210a is led to the ammonia vaporizer 251. The ammonia vaporizer 251 vaporizes the liquid ammonia fuel flowing through the first fuel supply system 210 by heat exchange with steam flowing through the discharge line L8.

The ammonia fuel vaporized by the ammonia vaporizer 251 is supplied to the ammonia fuel burner 210A. A burner valve 210B switches between a supply state in which ammonia fuel is supplied from the first fuel supply system 210 to the ammonia fuel burner 210A and a cut-off state in which ammonia fuel is not supplied from the first fuel supply system 210 to the ammonia fuel burner 210A.

The ammonia preheater 252 is, for example, a shell-and-tube type heat exchanger. The steam that has passed through the ammonia vaporizer 251 is supplied to the ammonia preheater 252 via the discharge line L8. A feed pump 255 that feeds the steam that has passed through the ammonia vaporizer 251 to the ammonia preheater 252 is arranged in the discharge line L8. The liquid ammonia fuel flowing through the fuel supply pipe 210a is led to the ammonia preheater 252. The ammonia preheater 252 preheats the liquid ammonia fuel flowing through the first fuel supply system 210 by heat exchange with the steam that has passed through the ammonia vaporizer 251.

In the fuel supply pipe 210a in which the ammonia vaporizer 251 and the ammonia preheater 252 are arranged, a temperature sensor (detection unit) 281 and a pressure sensor (detection unit) 282 are arranged between the ammonia vaporizer 251 and the burner valve 210B. The temperature sensor 281 is a sensor that detects the temperature of the ammonia fuel that has passed through the ammonia vaporizer 251. The pressure sensor 282 is a sensor that detects the pressure of the ammonia fuel that has passed through the ammonia vaporizer 251.

As shown in FIG. 3, the boiler system 100 of this embodiment includes a control unit 270 that controls each part of the boiler system 100, including the first regulating valve 253 and the second regulating valve 254. The temperature of the ammonia fuel detected by the temperature sensor 281 and the pressure of the ammonia fuel detected by the pressure sensor 282 are transmitted to the control unit 270.

The control unit 270 controls the opening of the first regulating valve 253 and the second regulating valve 254 so that the temperature of the ammonia fuel detected by the temperature sensor 281 is within a predetermined target temperature range (target value) and the pressure detected by the pressure sensor 282 is within a predetermined target pressure range (target value).

When the temperature of the ammonia fuel detected by the temperature sensor 281 falls below a predetermined target temperature range, the control unit 270 increases the ratio of the opening degree of the first adjustment valve 253 to the opening degree of the second adjustment valve 254 so as to increase the flow rate of steam supplied to the ammonia vaporizer 251 and the ammonia preheater 252. When the temperature of the ammonia fuel detected by the temperature sensor 281 exceeds the predetermined target temperature range, the control unit 270 decreases the ratio of the opening degree of the first adjustment valve 253 to the opening degree of the second adjustment valve 254 so as to decrease the flow rate of steam supplied to the ammonia vaporizer 251 and the ammonia preheater 252.

When the pressure of the ammonia fuel detected by the pressure sensor 282 falls below a predetermined target pressure range, the control unit 270 increases the ratio of the opening degree of the first adjustment valve 253 to the opening degree of the second adjustment valve 254 so as to increase the flow rate of steam supplied to the ammonia vaporizer 251 and the ammonia preheater 252. When the pressure of the ammonia fuel detected by the pressure sensor 282 exceeds the predetermined target pressure range, the control unit 270 decreases the ratio of the opening degree of the first adjustment valve 253 to the opening degree of the second adjustment valve 254 so as to decrease the flow rate of steam supplied to the ammonia vaporizer 251 and the ammonia preheater 252.

In the above, the control unit 270 controls the apertures of the first regulating valve 253 and the second regulating valve 254 so that the temperature of the ammonia fuel detected by the temperature sensor 281 is within a predetermined target temperature range (target value) and the pressure detected by the pressure sensor 282 is within a predetermined target pressure range (target value), but other configurations are also possible. For example, the control unit 270 may control the apertures of the first regulating valve 253 and the second regulating valve 254 so that the temperature of the ammonia fuel detected by the temperature sensor 281 is within a predetermined target temperature range (target value) or the pressure detected by the pressure sensor 282 is within a predetermined target pressure range (target value).

The boiler system 100 of this embodiment is equipped with a temperature sensor 281 and a pressure sensor 282, but may be equipped with only one of the temperature sensor 281 or the pressure sensor 282. When the boiler system 100 is equipped with only the temperature sensor 281, the control unit 270 controls the aperture of the first adjustment valve 253 and the second adjustment valve 254 so that the temperature of the ammonia fuel detected by the temperature sensor 281 is within a predetermined target temperature range (target value). When the boiler system 100 is equipped with only the pressure sensor 282, the control unit 270 controls the aperture of the first adjustment valve 253 and the second adjustment valve 254 so that the pressure of the ammonia fuel detected by the pressure sensor 282 is within a predetermined target pressure range (target value).

The actions and effects of the boiler system 100 of the present embodiment described above will be described.
According to the boiler system 100 of this embodiment, a boiler feedwater pump 123 that supplies boiler water to the boiler 10 is driven by steam extracted from a steam turbine 111 that is rotationally driven by steam generated in the boiler 10. The steam that has driven the boiler feedwater pump 123 is discharged to the condenser 112 by an exhaust system 250. The ammonia vaporizer 251 vaporizes liquid ammonia fuel flowing through the first fuel supply system 210 by heat exchange with the steam flowing through the exhaust system 250. The ammonia fuel vaporized in the ammonia vaporizer 251 is guided by the first fuel supply system 210 to an ammonia fuel burner 210A that burns the ammonia fuel to generate steam.

According to the boiler system 100 of this embodiment, steam that serves as a heat source for vaporizing ammonia fuel is extracted from the steam turbine 111, supplied to the boiler feedwater pump 123 (turbine section 123b), recovered from the exhaust system 250 to the condenser 112, and supplied again to the boiler 10 by the feedwater system 240. Since the steam that serves as a heat source for vaporizing ammonia fuel circulates within the boiler system 100, even if ammonia fuel is mixed with the steam in the ammonia vaporizer 251, the ammonia fuel will not flow out to the outside.

The steam that serves as the heat source for vaporizing the ammonia fuel is the steam that has been used as the power to drive the boiler feed water pump 123. Therefore, compared to when the steam that serves as the heat source for vaporizing the ammonia fuel is directly extracted from the steam turbine 111, the liquid ammonia fuel can be appropriately vaporized without causing a decrease in the thermal efficiency of the boiler system 100.

According to the boiler system 100 of this embodiment, the heat of the steam that has passed through the ammonia vaporizer 251 can be used to preheat the liquid ammonia fuel supplied to the ammonia vaporizer 251, thereby further improving the thermal efficiency of the boiler system 100.

According to the boiler system 100 of this embodiment, a portion of the steam that drives the boiler feedwater pump 123 can be guided to the ammonia vaporizer 251 and used as a heat source for vaporizing liquid ammonia fuel. In addition, another portion of the steam that drives the boiler feedwater pump 123 can be guided to the condenser 112, and the steam that is not used as a heat source for vaporizing ammonia fuel can be appropriately guided to the water supply system 240 via the condenser 112.

According to the boiler system 100 of this embodiment, the opening degree of the first adjustment valve 253 and the second adjustment valve 254 is controlled by the control unit 270 so that the temperature or pressure detected by the temperature sensor 281 or the pressure sensor 282 becomes a predetermined target value. Therefore, steam at a flow rate necessary for appropriately vaporizing the liquid ammonia fuel can be guided from the discharge line L8 to the ammonia vaporizer 251, and the other steam can be guided from the discharge line L9 to the condenser 112.

Second Embodiment
Hereinafter, a boiler system 100A according to a second embodiment of the present disclosure will be described with reference to the drawings. This embodiment is a modified example of the first embodiment, and is the same as the first embodiment except as otherwise specifically described below, and therefore the description below will be omitted.

The boiler system 100 of the first embodiment performs heat exchange between the steam that drives the boiler feedwater pump 123 and liquid ammonia fuel in the ammonia vaporizer 251, which is a single heat exchanger, and performs heat exchange between the steam that has passed through the ammonia vaporizer 251 and liquid ammonia fuel in the ammonia preheater 252, which is a single heat exchanger. In contrast, the boiler system 100A of the present embodiment performs heat exchange between the steam that drives the boiler feedwater pump 123 and liquid ammonia fuel in the ammonia vaporizer 251A, which is made up of multiple heat exchangers, and performs heat exchange between the steam that has passed through the ammonia vaporizer 251A and liquid ammonia fuel in the ammonia preheater 252A, which is made up of multiple heat exchangers.

Figure 4 is a schematic diagram showing the first fuel supply system 210 and the exhaust system 250 in the boiler system 100A according to the second embodiment of the present disclosure. As shown in Figure 4, the ammonia vaporizer 251A has a first heat exchange section 251Aa and a vaporization section 251Ab. The ammonia preheater 252A has a second heat exchange section 252Aa and a preheating section 252Ab.

The first heat exchanger 251Aa is, for example, a shell-and-tube type heat exchanger. The steam that drives the boiler feed water pump 123 is supplied to the first heat exchanger 251Aa via the exhaust line L7 and the exhaust line L8. The temperature of the steam introduced into the first heat exchanger 251Aa is, for example, in the range of 40°C or higher and 80°C or lower. The first heat exchanger 251Aa is supplied with a first heat medium (for example, water) circulated through the circulation line L10 by the circulation pump 251Ac. The first heat exchanger 251Aa exchanges heat between the steam circulating through the exhaust system 250 and the first heat medium.

The vaporization section 251Ab is, for example, a shell-and-tube type heat exchanger. The vaporization section 251Ab is supplied with a first heat medium circulating through the circulation line L10. The liquid ammonia fuel flowing through the fuel supply pipe 210a is led to the vaporization section 251Ab. The vaporization section 251Ab vaporizes the liquid ammonia fuel flowing through the first fuel supply system 210 by heat exchange with the first heat medium heated by the first heat exchange section 251Aa.

The second heat exchanger 252Aa is, for example, a shell-and-tube type heat exchanger. Steam that has passed through the first heat exchanger 251Aa is supplied to the second heat exchanger 252Aa via the exhaust line L8. The second heat exchanger 252Aa is supplied with a second heat medium (for example, water) circulated through the circulation line L11 by the circulation pump 252Ac. The second heat exchanger 252Aa exchanges heat between the steam circulating through the exhaust system 250 and the second heat medium.

The preheating section 252Ab is, for example, a shell-and-tube type heat exchanger. The preheating section 252Ab is supplied with a second heat medium circulating through the circulation line L11. The liquid ammonia fuel flowing through the fuel supply pipe 210a is led to the preheating section 252Ab. The preheating section 252Ab preheats the liquid ammonia fuel flowing through the first fuel supply system 210 by heat exchange with the second heat medium heated by the second heat exchange section 252Aa.

According to the boiler system 100A of this embodiment, the first heat medium is heated in the first heat exchange section 251Aa by the steam flowing through the exhaust system 250, and the liquid ammonia fuel is heated by the first heat medium in the vaporization section 251Ab. Heat exchange between the steam flowing through the exhaust system 250 and the liquid ammonia fuel is performed indirectly via the first heat medium. Therefore, even if the ammonia fuel is mixed with the first heat medium in the vaporization section 251Ab, the ammonia fuel mixed with the first heat medium will not be further mixed with the steam flowing through the exhaust system 250. Therefore, it is possible to reliably prevent the ammonia fuel from leaking out to the outside.

In addition, according to the boiler system 100A of this embodiment, the second heat medium is heated in the second heat exchange section 252Aa by the steam flowing through the exhaust system 250, and the liquid ammonia fuel is heated by the second heat medium in the preheating section 252Ab. Heat exchange between the steam that has passed through the second heat exchange section 252Aa and the liquid ammonia fuel is performed indirectly via the second heat medium. Therefore, even if the ammonia fuel is mixed with the second heat medium in the preheating section 252Ab, the ammonia fuel mixed with the second heat medium will not be further mixed with the steam flowing through the exhaust system 250. Therefore, it is possible to reliably prevent the ammonia fuel from leaking out to the outside.

The boiler system and the operating method of the boiler system described in each of the above-described embodiments can be understood, for example, as follows.
A boiler system (100) according to a first aspect of the present disclosure includes a boiler (10) that generates steam by burning ammonia fuel containing ammonia using a burner (210A), an ammonia fuel supply system (210) that supplies the ammonia fuel to the burner, a steam turbine (111) that is rotationally driven by the steam generated in the boiler, a feedwater system (240) that is driven by the steam extracted from the steam turbine and has a feedwater pump (123) that supplies boiler water to the boiler, an exhaust system (250) that exhausts the steam that has driven the feedwater pump, and an ammonia vaporizer (251) that vaporizes the liquid ammonia fuel circulating through the ammonia fuel supply system by heat exchange with the steam circulating through the exhaust system.

According to the boiler system according to the first aspect of the present disclosure, a feedwater pump that supplies boiler water to the boiler is driven by steam extracted from a steam turbine that is driven by steam generated in the boiler. The steam that drives the feedwater pump is discharged to the feedwater system by the exhaust system. The ammonia vaporizer vaporizes liquid ammonia fuel flowing through the ammonia fuel supply system by heat exchange with the steam flowing through the exhaust system. The ammonia fuel vaporized by the ammonia vaporizer is guided by the ammonia fuel supply system to a burner that burns the ammonia fuel to generate steam.

According to the boiler system according to the first aspect of the present disclosure, steam serving as a heat source for vaporizing ammonia fuel is extracted from the steam turbine to the feedwater pump and discharged from the exhaust system to the feedwater system. Since the steam serving as a heat source for vaporizing ammonia fuel circulates within the boiler system, even if ammonia fuel is mixed with the steam in the ammonia vaporizer, the ammonia fuel does not flow out to the outside. In addition, the steam serving as a heat source for vaporizing ammonia fuel is steam after being used as power to drive the feedwater pump. Therefore, compared to the case where steam serving as a heat source for vaporizing ammonia fuel is directly extracted from the steam turbine, liquid ammonia fuel can be appropriately vaporized without causing a decrease in the thermal efficiency of the boiler system.

The boiler system according to the second aspect of the present disclosure further includes the following configuration in the first aspect: That is, the boiler system includes an ammonia preheater (252) that preheats the liquid ammonia fuel supplied to the ammonia vaporizer by heat exchange with the steam that has passed through the ammonia vaporizer.

According to the boiler system according to the second aspect of the present disclosure, the heat of the steam that has passed through the ammonia vaporizer can be used to preheat the liquid ammonia fuel that is supplied to the ammonia vaporizer, thereby further improving the thermal efficiency of the boiler system.

The boiler system according to the third aspect of the present disclosure is the first or second aspect, and further includes the following configuration. That is, the ammonia vaporizer has a first heat exchange section (251Aa) that exchanges heat between the steam flowing through the exhaust system and a first heat medium, and a vaporization section (251Ab) that vaporizes the liquid ammonia fuel flowing through the ammonia fuel supply system by heat exchange with the first heat medium heated by the first heat exchange section.

According to the boiler system according to the third aspect of the present disclosure, the first heat medium is heated in the first heat exchange section by the steam flowing through the exhaust system, and the liquid ammonia fuel is heated by the first heat medium in the vaporization section. Heat exchange between the steam flowing through the exhaust system and the liquid ammonia fuel is performed indirectly via the first heat medium. Therefore, even if the ammonia fuel is mixed with the first heat medium in the vaporization section, the ammonia fuel mixed with the first heat medium will not be further mixed with the steam flowing through the exhaust system. Therefore, it is possible to reliably prevent the ammonia fuel from leaking out to the outside.

The boiler system according to the fourth aspect of the present disclosure further includes the following configuration in the second aspect. That is, the ammonia preheater has a second heat exchange section (251Ba) that exchanges heat between the steam that has passed through the ammonia vaporizer and a second heat medium, and a preheating section (251Bb) that preheats the liquid ammonia fuel supplied to the ammonia vaporizer by heat exchange with the second heat medium heated by the second heat exchange section.

According to the boiler system according to the fourth aspect of the present disclosure, the second heat medium is heated in the second heat exchange section by the steam flowing through the exhaust system, and the liquid ammonia fuel is heated by the second heat medium in the preheating section. Heat exchange between the steam that has passed through the second heat exchange section and the liquid ammonia fuel is performed indirectly via the second heat medium. Therefore, even if the ammonia fuel is mixed into the second heat medium in the preheating section, the ammonia fuel mixed into the second heat medium will not be further mixed into the steam flowing through the exhaust system. Therefore, it is possible to reliably prevent the ammonia fuel from leaking out to the outside.

The boiler system according to the fifth aspect of the present disclosure, in the first or second aspect, further comprises the following configuration: a condenser (112) that condenses the steam that drives the steam turbine and supplies it to the feedwater system, and the exhaust system has a first exhaust line (L8) that guides a portion of the steam that drives the feedwater pump to the ammonia vaporizer, and a second exhaust line (L9) that guides another portion of the steam that drives the feedwater pump to the condenser.

According to the boiler system according to the fifth aspect of the present disclosure, a portion of the steam that drives the feedwater pump can be guided to an ammonia vaporizer and used as a heat source for vaporizing liquid ammonia fuel. In addition, another portion of the steam that drives the feedwater pump can be guided to a condenser, and the steam that is not used as a heat source for vaporizing ammonia fuel can be appropriately guided to the feedwater system via the condenser.

The boiler system according to the sixth aspect of the present disclosure is the fifth aspect, and further includes the following configuration: a first regulating valve (253) arranged in the first discharge line, a second regulating valve (254) arranged in the second discharge line, a detection unit (281, 282) that detects the temperature or pressure of the ammonia fuel that has passed through the ammonia vaporizer, and a control unit (270) that controls the opening of the first regulating valve and the second regulating valve so that the temperature or the pressure detected by the detection unit becomes a predetermined target value.

According to the boiler system according to the sixth aspect of the present disclosure, the opening of the first and second regulating valves is controlled by the control unit so that the temperature or pressure detected by the detection unit becomes a predetermined target value. Therefore, steam at a flow rate required to properly vaporize the liquid ammonia fuel can be guided from the first discharge line to the ammonia vaporizer, and the other steam can be guided from the second discharge line to the condenser.

In the operating method of the boiler system according to the seventh aspect of the present disclosure, the boiler system includes a boiler (10) that burns ammonia fuel containing ammonia using a burner (210A) to generate steam, an ammonia fuel supply system (210) that supplies the ammonia fuel to the burner, a steam turbine (111) that is driven by the steam generated in the boiler, a feedwater system (240) that is driven by the steam extracted from the steam turbine and has a feedwater pump (123) that supplies boiler water to the boiler, and an exhaust system (250) that discharges the steam that drives the feedwater pump to the feedwater system, and includes an ammonia vaporization process that exchanges heat between the steam flowing through the exhaust system and a liquid flowing through the ammonia fuel supply system, and vaporizes the ammonia fuel in the liquid flowing through the ammonia fuel supply system.

According to the operating method of the boiler system according to the seventh aspect of the present disclosure, steam serving as a heat source for vaporizing ammonia fuel is extracted from the steam turbine to the feedwater pump and discharged from the exhaust system to the condenser. Since the steam serving as a heat source for vaporizing ammonia fuel circulates within the boiler system, even if ammonia fuel is mixed with the steam in the ammonia vaporizer, the ammonia fuel does not flow out to the outside. In addition, the steam serving as a heat source for vaporizing ammonia fuel is steam after being used as power to drive the feedwater pump. Therefore, compared to the case where steam serving as a heat source for vaporizing ammonia fuel is directly extracted from the steam turbine, liquid ammonia fuel can be appropriately vaporized without causing a decrease in the thermal efficiency of the boiler system.

10 Boiler 100, 100A Boiler system 111 Steam turbine 111A High pressure turbine 111B Intermediate pressure turbine 111C Low pressure turbine 112 Condenser 113 Generator 121 Condensate pump 123 Boiler feed water pump 123a Pump section 123b Turbine section 127 Control valve 210 First fuel supply system 210A Ammonia fuel burner 210B Burner valve 210a Fuel supply piping 211 Feed pump 240 Feed water system 250 Discharge system 251, 251A Ammonia vaporizer 251Aa First heat exchange section 251Ab Vaporization section 251Ac Circulation pump 252, 252A Ammonia preheater 252Aa Second heat exchange section 252Ab Preheating section 252Ac Circulation pump 253 First adjustment valve 254 Second adjustment valve 255 Feed pump 260 Ammonia tank 270 Control unit 281 Temperature sensor (detection unit)
282 Pressure sensor (detection unit)

Claims (7)

a boiler that burns ammonia-containing fuel by a burner to generate steam;
an ammonia fuel supply system for supplying the ammonia fuel to the burner;
a steam turbine that is rotationally driven by the steam generated in the boiler;
a feed water system including a feed water pump driven by the steam extracted from the steam turbine and supplying boiler water to the boiler;
a discharge system that discharges the steam that has driven the feed water pump to the feed water system;
an ammonia vaporizer that vaporizes the liquid ammonia fuel flowing through the ammonia fuel supply system by heat exchange with the steam flowing through the exhaust system. The boiler system according to claim 1, further comprising an ammonia preheater that preheats the liquid ammonia fuel supplied to the ammonia vaporizer by heat exchange with the steam that has passed through the ammonia vaporizer. The boiler system according to claim 1 or 2, wherein the ammonia vaporizer has a first heat exchange section that exchanges heat between the steam flowing through the exhaust system and a first heat medium, and a vaporization section that vaporizes the liquid ammonia fuel flowing through the ammonia fuel supply system by heat exchange with the first heat medium heated by the first heat exchange section. The boiler system according to claim 2, wherein the ammonia preheater has a second heat exchange section that exchanges heat between the steam that has passed through the ammonia vaporizer and a second heat medium, and a preheating section that preheats the liquid ammonia fuel supplied to the ammonia vaporizer by heat exchange with the second heat medium heated by the second heat exchange section. a condenser that condenses the steam that has rotationally driven the steam turbine and supplies the condensed steam to the water supply system;
3. The boiler system according to claim 1, wherein the exhaust system includes a first exhaust line that guides a portion of the steam that has driven the feedwater pump to the ammonia vaporizer, and a second exhaust line that guides another portion of the steam that has driven the feedwater pump to the condenser. A first regulator valve disposed in the first discharge line;
A second regulator valve disposed in the second discharge line;
A detection unit that detects a temperature or a pressure of the ammonia fuel that has passed through the ammonia vaporizer;
6. The boiler system according to claim 5, further comprising: a control unit that controls an opening degree of the first regulating valve and the second regulating valve so that the temperature or the pressure detected by the detection unit becomes a predetermined target value. 1. A method for operating a boiler system, comprising:
The boiler system includes:
a boiler that burns ammonia-containing fuel by a burner to generate steam;
an ammonia fuel supply system for supplying the ammonia fuel to the burner;
a steam turbine that is rotationally driven by the steam generated in the boiler;
a feed water system including a feed water pump driven by the steam extracted from the steam turbine and supplying boiler water to the boiler;
a discharge system that discharges the steam that has driven the feed water pump to the feed water system,
An operating method of a boiler system, comprising: an ammonia vaporization step of exchanging heat between the steam flowing through the exhaust system and a liquid flowing through the ammonia fuel supply system, and vaporizing the ammonia fuel in the liquid flowing through the ammonia fuel supply system.