Heating method, heating system, and power generation plant

Abstract

To provide a heating method, a heating system and a power generation plant, enabling the reduction of the necessary maintenance frequency resulting from the sticking of dirt to the facility and the simplification and / or the downsizing of the structure of a steam condenser, in comparison with when the vaporizer is installed inside the steam condenser.SOLUTION: Fuel is heated by the feed water for heating, extracted from boiler feed water guided from a condenser 112 to a boiler 10. The fuel having been heated by the feed water for heating, is supplied to the boiler 10. The feed water for heating after exchanging heat with the fuel, is guided to inside of the condenser 112. The fuel having been heated by the feed water for heating, is heated by the steam for heating extracted from the steam being guided to the steam-turbine 111C.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a heating method, a heating system, and a power plant. [Background technology]

[0002] 2. Description of the Related Art A boiler installed in a power plant such as a thermal power plant is configured to generate steam by heating and superheating boiler feed water with combustion gas. The combustion gas can be generated by burning, for example, pulverized fuel or fuel containing ammonia in a burner of the boiler. In this case, the ammonia may be vaporized from a liquid state to a gas state before being supplied to the boiler. Systems for vaporizing liquid ammonia are disclosed, for example, in US Pat. No. 5,399,623 and US Pat. No. 5,499,633. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-200029 A [Patent Document 2] JP 2023-11172 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the system described in Patent Document 1, liquid ammonia is heated and vaporized using cooling water (seawater or river water) that has been heated in a condenser by heat exchange with steam discharged from a steam turbine. Moreover, in the system described in Patent Document 2, liquid ammonia is heated and vaporized inside the condenser by heat exchange with steam discharged from a steam turbine.

[0005] When liquid ammonia is heated using cooling water such as seawater or river water as in Patent Document 1, the heat transfer part of the vaporizer that vaporizes the liquid ammonia is prone to becoming dirty due to foreign matter contained in the seawater or river water, and it is therefore necessary to take measures to prevent dirt from adhering to the heat transfer part and to perform regular maintenance.

[0006] Furthermore, when liquid ammonia is heated inside the condenser as in Patent Document 2 (that is, when a vaporizer is installed inside the condenser), the structure of the condenser may become complicated and large.

[0007] The present disclosure has been made in consideration of the above circumstances, and aims to provide a heating method, heating system, and power generation plant that can reduce the adhesion of dirt to equipment and the frequency of maintenance required due to the adhesion of dirt, and that can simplify and / or reduce the size of the condenser structure compared to a case where an evaporator is installed inside the condenser. [Means for solving the problem]

[0008] In order to solve the above problems, the heating method, heating system, and power generation plant disclosed herein employ the following measures. That is, in a heating method according to one aspect of the present disclosure, fuel is heated with heating feedwater extracted from boiler feedwater guided from a condenser to a boiler.

[0009] Moreover, a heating system according to one aspect of the present disclosure includes a feedwater supply line and a preheater, the feedwater supply line conducting heating feedwater extracted from boiler feedwater conducted from a condenser to a boiler to the preheater, and the preheater heating fuel with the heating feedwater conducted by the feedwater supply line.

[0010] Furthermore, a power generation plant according to one embodiment of the present disclosure includes the above-mentioned heating system, a boiler to which fuel heated by the heating system is supplied, a steam turbine that is rotated by steam generated in the boiler, and the condenser to which steam discharged from the steam turbine is guided. Effect of the Invention

[0011] According to the present disclosure, it is possible to reduce the adhesion of dirt to equipment and the frequency of maintenance required due to the adhesion of dirt, and it is possible to simplify and / or reduce the size of the condenser structure compared to a case in which an evaporator is installed inside the condenser. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a schematic configuration diagram of a boiler provided in a power plant according to an embodiment of the present disclosure. [Diagram 2] FIG. 1 is a diagram illustrating a steam system (water system) of a power plant according to an embodiment of the present disclosure. [Diagram 3] FIG. 1 is a schematic configuration diagram of a heating system provided in a power plant according to an embodiment of the present disclosure. [Figure 4] FIG. 11 is a schematic configuration diagram of an evaporation device according to a second modified example of an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, a power plant operation method and a power plant according to an embodiment of the present disclosure will be described with reference to the drawings.

[0014] However, the present disclosure is not limited to this embodiment. Furthermore, when there are a plurality of embodiments or examples, the embodiments or examples may be combined together. Additionally, "up" and "above" refer to the top in the vertical direction, and "down" and "below" refer to the bottom in the vertical direction. However, the vertical direction may include an error.

[0015] [Power plant configuration] FIG. 1 is a schematic diagram showing the configuration of a boiler 10 provided in a power plant 1. As shown in FIG. The boiler 10 is a facility that burns pulverized fuel made from pulverized solid fuel and / or vaporized fuel using multiple burners 21, and generates steam (superheated steam) by heating and reheating the boiler feedwater and steam with the heat of the combustion gas generated by the combustion. Examples of solid fuels include biomass fuels and coal. The boiler 10 includes a furnace 11, a combustion device 20, and a combustion gas passage 12.

[0016] The furnace 11 has a hollow rectangular prism shape and is installed along the vertical direction. The furnace wall 101 constituting the inner wall surface of the furnace 11 has a plurality of heat transfer tubes and fins connecting the heat transfer tubes, and is configured to recover heat generated by the combustion of pulverized fuel and / or vaporized fuel by heat exchange with boiler feed water and steam flowing inside each heat transfer tube. The furnace wall 101 is sometimes called a "water-cooled wall."

[0017] The combustion device 20 is installed in the lower region of the furnace 11 . The combustion device 20 has a plurality of burners 21A, 21B, 21C, 21D, 21E, and 21F (which may be collectively referred to as "burners 21") attached to a furnace wall 101, and a wind box 23. The burners 21 are arranged in a set at equal intervals along the circumferential direction of the furnace 11, and the sets are arranged in multiple tiers along the vertical direction. In the case of Fig. 1, for example, four burners 21 are arranged at each corner of the rectangular furnace 11, and six such sets are arranged in the vertical direction.

[0018] For convenience of illustration, FIG. 1 shows only two of the burners included in one set, and each set is denoted by reference numerals 21A, 21B, 21C, 21D, 21E, and 21F. Furthermore, the shape of the furnace 11, the number of stages of the burners 21, the number of burners 21 in one stage, the arrangement of the burners 21, and the like are not limited to the above-mentioned embodiment.

[0019] Burners 21A, 21B, 21C, 21D, 21E, and 21F are respectively connected to a number of mills 31A, 31B, 31C, 31D, 31E, and 31F (which may be collectively referred to as "mills 31") via pulverized fuel supply pipes 22A, 22B, 22C, 22D, 22E, and 22F (which may be collectively referred to as "pulverized fuel supply pipes 22"). Further, the burners 21A, 21B, 21C, 21D, 21E, and 21F are each connected to the heating system 200 via a vaporized fuel supply pipe (not shown). Pulverized fuel and / or fuel containing ammonia (hereinafter referred to as "ammonia fuel") is supplied to each burner 21. That is, each burner 21 is a device capable of burning only pulverized fuel, only ammonia fuel, or a mixture of pulverized fuel and ammonia fuel.

[0020] The mill 31 is, for example, a vertical roller mill in which a grinding table (not shown) is supported inside 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 pulverizing roller and the pulverizing table is transported to a classifier (not shown) provided in the mill 31 by primary air (carrying gas, oxidizing gas) supplied to the mill 31. In the classifier, the fuel is classified into pulverized fuel having a particle size equal to or smaller than that suitable for combustion in the burner 21, and coarse pulverized fuel having a particle size larger than that. The pulverized fuel passes through the classifier and is supplied to the burner 21 together with the primary air through the pulverized fuel supply pipe 22. The coarse pulverized fuel that does not pass through the classifier falls onto the grinding table by its own weight inside the mill 31 and is ground again. The heating system 200 will be described in detail below.

[0021] An air register 23 is provided outside the furnace 11 at the mounting position of the burner 21, and one end of an air passage 24 (air duct) is connected to the air register 23. The other end of the air duct 24 is connected to a forced draft fan (FDF: Forced Draft Fan) 32 . The air supplied from the forced draft fan 32 is heated in an air preheater 42 installed in the air duct 24 (details will be described later), and is supplied to the burner 21 via the wind box 23 as secondary air (combustion air, oxidizing gas), and is introduced into the furnace 11.

[0022] 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, 102C (sometimes collectively referred to as "superheaters 102"), reheaters 103A, 103B (sometimes collectively referred to as "reheater 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 boiler feed water and steam flowing inside each heat exchanger. The arrangement and shape of each heat exchanger are not limited to the form shown in FIG.

[0023] A flue 13 is connected downstream of the combustion gas passage 12, through which the combustion gas from which heat has been recovered in each heat exchanger is discharged. An air preheater 42 (air heater) is provided in the flue 13, and configured so that heat exchange occurs between the air flowing through the air duct 24 and the combustion gas flowing through the flue 13. By heating the primary air supplied to the mill 31 and the secondary air supplied to the burner 21 using the air preheater 42, further heat recovery can be performed from the combustion gas after heat exchange with the boiler feed water and steam.

[0024] Further, a denitration device 43 may be provided in the flue 13 at a position upstream of the air preheater . The denitration device 43 supplies a reducing agent having the effect of reducing nitrogen oxides, such as ammonia for denitration or urea water, 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.

[0025] A gas duct 41 is connected to the flue 13 downstream of the air preheater 42 . The gas duct 41 is provided with environmental equipment such as a dust collector 44, such as an electrostatic precipitator, for removing ash and the like from the combustion gas, a desulfurization device 46 for removing sulfur oxides, and 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 in the environmental equipment is discharged to the outside of the system as exhaust gas.

[0026] In the boiler 10, when the multiple mills 31 are driven, pulverized and classified pulverized fuel is supplied to the burner 21 together with primary air via the pulverized fuel supply pipe 22. In addition, secondary air heated by the air preheater 42 is supplied to the burner 21 from the air duct 24 through the wind box 23. In addition, when co-firing pulverized fuel and ammonia fuel, gaseous ammonia fuel supplied from the heating system 200 is supplied to the burner 21 via a vaporized fuel supply pipe (not shown). The burner 21 injects a pulverized fuel mixture, which is a mixture of pulverized fuel and primary air, into the furnace 11, and also injects secondary air into the furnace 11. When co-combustion of pulverized fuel and ammonia fuel is performed, the burner 21 injects gaseous ammonia fuel into the furnace 11. The pulverized fuel mixture and / or ammonia fuel injected into the furnace 11 is ignited and reacts 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 within 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, and stable combustion in the furnace 11 can be achieved by adjusting the ratio of the amount of oxygen to the amount of fuel supplied within an appropriate range.

[0027] The combustion gas that flows into the combustion gas passage 12 exchanges heat with water and steam in a superheater 102, a reheater 103, and a coal 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, the combustion gas exchanges heat with primary air and secondary air in the air preheater 42, and is further discharged into the gas duct 41, where ash and the like are removed in the dust collector 44, and sulfur oxides are removed in the desulfurization device 46, and the combustion gas is then discharged to the outside of the system from a chimney 47. The heat exchangers in the combustion gas passage 12 and the devices from the flue 13 to the gas duct 41 do not necessarily have to be arranged in the above order with respect to the combustion gas flow.

[0028] Next, a detailed description will be given of the superheater 102, the reheater 103, and the economizer 104 provided as heat exchangers in the combustion gas passage 12. Fig. 2 is a diagram showing a steam system (water system) of the power plant 1. Note that FIG. 1 does not accurately show the positions of each heat exchanger (superheaters 102A, 102B, 102C, reheaters 103A, 103B, and economizer 104) in the combustion gas passage 12, and the arrangement order of each heat exchanger with respect to the combustion gas flow is not limited to that shown in FIG. 1.

[0029] As shown in FIG. 2, the power plant 1 includes heat exchangers 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.

[0030] The steam turbine 111 includes, for example, a high-pressure turbine 111A, an intermediate-pressure turbine 111B, and a low-pressure turbine 111C. Steam heated by the superheater 102 of the boiler 10 drives and rotates the high-pressure turbine 111A. The steam that has passed through the high-pressure turbine 111A is reheated in the reheater 103 of the boiler 10, and drives the intermediate-pressure turbine 111B to rotate. The steam that has passed through the intermediate-pressure turbine 111B drives and rotates the low-pressure turbine 111C.

[0031] A condenser 112 is connected to the low-pressure turbine 111C, and the steam that drives the low-pressure turbine 111C is condensed in the condenser 112 by heat exchange with cooling water (e.g., seawater, river water, or returned heating feed water described below) to become condensate (boiler feed water). The condenser 112 is connected to the economizer 104 via a boiler feedwater line L1.

[0032] The boiler feedwater line L1 is provided with, for example, a condensate pump 121 (CP), a low-pressure feedwater heater 122, a boiler feedwater pump 123 (BFP), and a high-pressure feedwater heater 124. The low pressure feed water heater 122 and the high pressure feed water heater 124 are devices that heat the boiler feed water supplied to the economizer 104 .

[0033] For example, when the boiler 10 is a once-through boiler, the economizer 104 is connected to the heat transfer tubes that constitute the furnace wall 101 . The boiler feedwater heated in the economizer 104 passes through the boiler feedwater line L1, is heated by radiation from the flame in the furnace 11 as it passes through the heat transfer tubes that make up the furnace wall 101, and is led to the steam separator 125. The steam separated in the steam separator 125 is supplied to the superheater 102. On the other hand, the drain water separated in the steam separator 125 flows into a steam separator drain tank 126 and is guided to the condenser 112 via a drain water line L2.

[0034] Furthermore, during start-up or low-load operation of the once-through boiler, the boiler feedwater supplied from the economizer 104 may not be fully evaporated as it passes through the heat transfer tubes constituting the furnace wall 101, resulting in an operating state (wet operating state) in which a water level exists in the steam separator 125. In this wet operating state, the drain water separated in the steam separator 125 and guided to the steam separator drain tank 126 may be circulated and supplied from the economizer 104 to the heat transfer tubes constituting the furnace wall 101 by merging it midway through the boiler feedwater line L1 using the boiler circulation pump 127 (BCP) via the circulation line L7.

[0035] When the combustion gas flows through the combustion gas passage 12, heat of the combustion gas is recovered by the superheater 102, the reheater 103, and the economizer 104. Meanwhile, the boiler feed water supplied from the boiler feed pump 123 (BFP) is preheated by the economizer 104, and then heated as it passes through the heat transfer tubes constituting the furnace wall 101 to become steam. The steam is then led to the steam separator 125. The steam separated in the steam separator 125 is introduced into the first superheater 102A, the second superheater 102B, and the third superheater 102C, and is superheated by the combustion gas. The superheated steam generated in the superheater 102 is supplied to the high-pressure turbine 111A via a steam line L3, and drives the high-pressure turbine 111A to rotate. The steam discharged from the high-pressure turbine 111A is introduced into the first reheater 103A and the second reheater 103B via a steam line L4 and is superheated again. The steam resuperheated in each reheater is supplied to the intermediate-pressure turbine 111B via a steam line L5, and drives the intermediate-pressure turbine 111B to rotate. The steam discharged from the intermediate-pressure turbine 111B is supplied to the low-pressure turbine 111C via a steam line L6, and drives the low-pressure turbine 111C to rotate. The rotating shaft of the steam turbine 111 rotates and drives a generator 113 to generate electricity. The steam discharged from the low-pressure turbine 111C is cooled in a condenser 112 to become condensed water, and is sent to the economizer 104 as boiler feed water via a boiler feed water line L1.

[0036] [About the heating system] The heating system 200 is a system for heating and vaporizing ammonia fuel (fuel) supplied in a liquefied state, and supplying the gaseous ammonia fuel to the boiler 10. As shown in FIG. 3, the heating system 200 includes a control unit 250, an evaporation device 210, various lines, various valves provided on each line as necessary, and various instruments provided on each line as necessary.

[0037] The control unit 250 (Controller) includes, for example, a CPU (Central Processing Unit: Processor), a main memory, a secondary storage, etc. Furthermore, the control unit 250 may include a communication unit for transmitting and receiving information to and from other devices. Here, the other devices include, for example, each valve, a level gauge, a thermometer, a flow meter, etc. that are required for controlling each valve provided at each location. The main storage device is composed of writable memory such as cache memory and RAM (Random Access Memory), and is used as a working area for reading out programs executed by the CPU and writing data processed by the programs. The secondary storage device is a non-transitory computer readable storage medium, such as a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, or a semiconductor memory. A series of processes for realizing various functions is stored in a secondary storage device in the form of a program, for example, and various functions are realized by the CPU reading the program into the main storage device and executing information processing and arithmetic processing. The program may be installed in the secondary storage device in advance, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Examples of computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

[0038] <About the vaporizer> The vaporizer 210 is a device for heating and vaporizing ammonia fuel that is supplied in a liquefied state. The vaporizer 210 includes a preheater 211 and a heater 212 .

[0039] <<About the preheater>> The preheater 211 is a heat exchanger, and is configured to heat the liquefied ammonia fuel with heating feed water. Here, the heating feedwater refers to a portion of the boiler feedwater flowing through the boiler feedwater line L1. The temperature of the extracted heating feedwater is, for example, about 30°C to 40°C.

[0040] The preheater 211 is connected to a heating feedwater supply line L11 (hereinafter simply referred to as the "feedwater supply line L11") and a heating feedwater return line L12 (hereinafter simply referred to as the "feedwater return line L12") through which heating feedwater flows, as well as a liquefied fuel supply line L31 and a connection line L32 through which ammonia fuel flows.

[0041] The feedwater supply line L11 is a line (piping system) that guides heating feedwater from the boiler feedwater line L1 to the preheater 211. The feedwater supply line L11 has a first end connected to the boiler feedwater line L1 and a second end connected to a feedwater inlet of the preheater 211. A first end of the feedwater supply line L11 is preferably connected to a portion of the boiler feedwater line L1 between the condensate pump 121 and the low-pressure feedwater heater 122. This is because the temperature of the boiler feedwater before being heated by the low-pressure feedwater heater 122 is sufficient as the temperature required for the heating feedwater.

[0042] The feedwater return line L12 is a line that guides the heating feedwater that has completed heat exchange in the preheater 211 (the heating feedwater that has been heat exchanged with ammonia fuel in the preheater 211) from the preheater 211 to the condenser 112. The feedwater return line L12 has a first end connected to the feedwater outlet of the preheater 211 and a second end connected to the condenser 112. The heating feedwater after heat exchange, which is guided to the condenser 112 via the feedwater return line L12, may be sprayed inside the condenser 112. The temperature of the heating feedwater after heat exchange is lower than the temperature before the heat exchange, and spraying low-temperature heating feedwater into the inside of the condenser 112 makes it possible to cool the inside of the condenser 112, thereby efficiently improving the degree of vacuum of the condenser 112. It is considered that the temperature of the heating feedwater after heat exchange is preferably about 8°C, for example, but is not particularly limited to this temperature.

[0043] The liquefied fuel supply line L31 is a line that leads ammonia fuel to the preheater 211 from a storage facility (not shown) in which the liquefied ammonia fuel is stored. The liquefied fuel supply line L31 has a first end connected to the storage facility and a second end connected to the fuel inlet of the preheater 211. The temperature of the liquefied ammonia fuel before being heated by the preheater 211 is about -34°C.

[0044] The connection line L32 is a line that leads the ammonia fuel heated in the preheater 211 from the preheater 211 to the heater 212. The connection line L32 has a first end connected to the fuel outlet of the preheater 211 and a second end connected to the fuel inlet of the heater 212. When the ammonia fuel is heated in the preheater 211 until it becomes saturated, the temperature of the ammonia fuel becomes about −5° C. However, this temperature depends on the pressure and is not particularly limited to this temperature.

[0045] As described above, the liquefied ammonia fuel is heated in the preheater 211 by the heating feed water extracted from the boiler feed water (heating process by feed water). Furthermore, the heating feed water that has completed heat exchange in the preheater 211 is guided into the condenser 112 (feed water returning process).

[0046] <<About the heater>> The heater 212 is a heat exchanger, and is configured to heat, with heating steam, the ammonia fuel that has completed heat exchange in the preheater 211. Heating by the heater 212 is preferably performed until the temperature of the ammonia fuel reaches a temperature suitable for combustion in the burner 21 (for example, about 20°C to 50°C). Here, the heating steam refers to steam that is a part of the steam flowing through the steam line L6. The temperature of the heating steam that is extracted is, for example, about 180°C. The heater 212 is connected to a steam supply line L21 through which heating steam flows, a drain return line L22 through which condensed water produced by condensing the heating steam flows, as well as a connection line L32 through which ammonia fuel flows and a vaporized fuel supply line L33.

[0047] The steam supply line L21 is a line that guides heating steam from the steam line L6 to the heater 212. The steam supply line L21 has a first end connected to the steam line L6 and a second end connected to a steam inlet of the heater 212. The steam supply line L21 is provided with a flow rate adjustment valve 231. The opening degree of the flow rate adjustment valve 231 is determined by the control unit 250 based on the internal pressure of the heater 212, for example.

[0048] The drain return line L22 is a line that guides the heating steam that has completed heat exchange in the heater 212 (heating steam after heat exchange with ammonia fuel in the heater 212. It includes condensed water (drain) formed when the heating steam is condensed by heat exchange. Hereinafter, it is also simply referred to as "drain") from the heater 212 to the feedwater supply line L11 or the condenser 112. The temperature of the drain is, for example, about 100°C, which is higher than the temperature of the heating feedwater. The drain return line L22 has a first end connected to the drain outlet of the heater 212 and a second end formed as a branching portion. At the branching portion, the drain return line L22 branches into a first drain return line L22a and a second drain return line L22b. An end of the first drain return line L22a is connected to the feedwater supply line L11, and an end of the second drain return line L22b is connected to the condenser 112. A drain return pump 232 is provided in the drain return line L22, and the drain is transported by the drain return pump 232. The first drain return line L22a is provided with an on-off valve 233. The second drain return line L22b is provided with an on-off valve 234. The state (open state / closed state) of the on-off valve 233 and the state of the on-off valve 234 are determined by the control unit 250 based on predetermined information. As a specific example of the control method, when the temperature of the heating feedwater flowing through the feedwater supply line L11 is low or the flow rate is low, the drain is guided to the feedwater supply line L11 (i.e., the on-off valve 233 is opened and the on-off valve 234 is closed), and otherwise the drain is guided to the condenser 112 (i.e., the on-off valve 233 is closed and the on-off valve 234 is opened). Note that this control method is an example, and for example, both the on-off valve 233 and the on-off valve 234 may be opened, or both the on-off valve 233 and the on-off valve 234 may be closed to discharge the drain outside the system.

[0049] As described above, the connection line L32 is a line that leads the ammonia fuel that has completed heat exchange in the preheater 211 from the preheater 211 to the heater 212.

[0050] The vaporized fuel supply line L33 is a line that leads the gaseous ammonia fuel that has completed heat exchange in the heater 212 from the heater 212 to the boiler 10. The temperature of the gaseous ammonia fuel is, for example, about 20°C to 50°C. The vaporized fuel supply line L33 has a first end connected to a fuel outlet of the heater 212 and a second end connected to each vaporized fuel supply pipe (not shown). The ammonia fuel guided to the vaporized fuel supply pipe is supplied to the burner 21 of the boiler 10.

[0051] As described above, the ammonia fuel that has completed the heat exchange in the preheater 211 is heated in the heater 212 by the heating steam extracted from the steam flowing to the low-pressure turbine 111C (heating process by steam). In addition, the gaseous ammonia fuel heated in the heater 212 is supplied to the burner 21 of the boiler 10 (fuel supply process). Furthermore, the drain that has completed the heat exchange in the heater 212 joins the heating feed water before it is subjected to heat exchange with the ammonia fuel in the preheater 211 (drain return process).

[0052] <Regarding Modification 1 of the Vaporizer> The vaporizer 210 includes a preheater 211 and a heater 212, and vaporizes the liquefied ammonia fuel by passing through the two heat exchangers. However, in the case where the liquefied ammonia fuel can be vaporized by heating only by the preheater 211, the heater 212 may be omitted or the ammonia fuel may be configured to bypass the heater 212. A case where the liquefied ammonia fuel can be vaporized only by heating with the preheater 211 is, for example, a case where the ratio of ammonia fuel decreases when pulverized fuel and ammonia fuel are mixed and the amount of ammonia fuel required in the boiler 10 is small. On the other hand, when the ratio of ammonia fuel increases when pulverized fuel and ammonia fuel are mixed and the amount of ammonia fuel required in the boiler 10 increases, the vaporization device 210 may be configured to pass through two heat exchangers (the preheater 211 and the heater 212).

[0053] As described above, in the case of the first modification, the ammonia fuel heated and vaporized in the preheater 211 is supplied to the burner 21 of the boiler 10 (fuel supplying step).

[0054] <Modification 2 of the vaporizer> The vaporizer 210 includes a preheater 211 and a heater 212, and changes the liquefied ammonia fuel into vaporized ammonia fuel by passing through the two heat exchangers. However, as shown in Fig. 4, a second preheater 213 may be provided in the liquefied fuel supply line L31. The second preheater 213 is a heat exchanger, and is configured to heat the ammonia fuel before it is heated by the preheater 211. The heat source of the second preheater 213 is a heat medium different from the heating feed water, and examples of the heat source include seawater and river water. In addition, the heat source may be warm wastewater used for cooling other components of the power plant 1.

[0055] As described above, in the case of the second modification, the ammonia fuel before heat exchange in the preheater 211 is heated in the second preheater 213 by a heat medium different from the heating feed water (heating process by another heat medium).

[0056] <Flow rate of heating water supply> The flow rate of the heating feedwater flowing through the feedwater supply line L11, that is, the flow rate of the heating feedwater supplied to the preheater 211, is determined, for example, as follows. As shown in FIG. 3, the heating system 200 includes at least one of a level gauge 241, a temperature gauge 242, and a flow meter 243, a flow control valve 221 provided in the feedwater supply line L11, and a flow meter 222 provided in the feedwater supply line L11.

[0057] The level meter 241 is an instrument that measures the liquid level of the ammonia fuel inside the preheater 211 or the heater 212 , and is provided in the preheater 211 or the heater 212 . The thermometer 242 is a gauge that measures the temperature of the ammonia fuel after it has been heated by the heater 212, and is provided in the vaporized fuel supply line L33. The flow meter 243 is a meter that measures the flow rate of the ammonia fuel after it has been heated by the heater 212, and is provided on the vaporized fuel supply line L33.

[0058] The target value of the flow rate of the heating feedwater flowing through the feedwater supply line L11 is adjusted by the control unit 250 based on at least one measured value of the level meter 241, the thermometer 242, and the flow meter 243. Examples of specific adjustment methods include (1) feedback control based on the measurement value from the level meter 241, (2) feedback control based on the measurement value from the thermometer 242 and the measurement value from the flow meter 243, and (3) program control based on the measurement value from the flow meter 243, or a combination of these (1) to (3). Once the target value for the flow rate of the heating supply water has been determined by the control unit 250, the control unit 250 controls the opening degree of the flow rate control valve 221 based on information regarding the flow rate of the heating supply water flowing through the water supply line L11 obtained from the flow meter 222 and the target value of the flow rate.

[0059] In the case of the above-mentioned <Variation 1 of the vaporizer>, the thermometer 242 measures the temperature of the ammonia fuel after it has been heated by the preheater 211, and the flow meter 243 measures the flow rate of the ammonia fuel after it has been heated by the preheater 211.

[0060] According to this embodiment, the following effects are obtained. Since ammonia fuel is heated using heating feedwater extracted from the boiler feedwater, it is possible to reduce the adhesion of dirt to the equipment and the frequency of maintenance required due to the adhesion of dirt, compared to when fuel is heated using, for example, seawater or river water. Furthermore, the temperature of the boiler feed water is stable throughout the year compared to, for example, sea water or river water, which facilitates management related to stable heating of the fuel. In addition, even if ammonia fuel leaks into the heat medium in the heat transfer section of the heat exchanger, the ammonia leaking into the boiler feed water and / or heating feed water system can be contained, which means that the risk of ammonia leaking into the external environment can be reduced. Furthermore, compared to a case where heat exchange is performed inside the condenser 112 (that is, a case where an evaporator is installed inside the condenser 112), the structure of the condenser 112 can be simplified and / or made smaller. Also, from the viewpoint of using the existing condenser 112 as is, it is considered that implementation is easier and there is less of an impact on the performance of the steam turbine compared to the case where a vaporizer is installed inside the condenser 112.

[0061] In addition, since the heating feed water after heat exchange with the ammonia fuel is guided into the inside of the condenser 112, the inside of the condenser 112 can be cooled by the low-temperature heating feed water. This makes it possible to efficiently improve the degree of vacuum in the condenser 112. This is expected to be effective in cases where the degree of vacuum in the condenser decreases due to a rise in the temperature of seawater or river water used as cooling water for the condenser 112, particularly in summer, and the efficiency of the steam turbine decreases.

[0062] Furthermore, since the ammonia fuel that has been heated by the heating feed water is heated using the heating steam, even if the flow rate of the ammonia fuel is high, the ammonia fuel can be sufficiently heated and vaporized. The flow rate of ammonia fuel is high when, for example, the ratio of ammonia fuel increases during co-combustion of ammonia fuel and other fuel.

[0063] In addition, since the drain of the heating steam is merged with the heating feed water before it is heat exchanged with the ammonia fuel, the temperature of the heating feed water can be increased by the drain.

[0064] Furthermore, since the ammonia fuel before being heated is heated by a heat medium different from the heating feed water, the ammonia fuel before being heated can be preheated by the heating feed water.

[0065] The liquefied gas fuel heated in the preheater 211, the heater 212, and the second preheater 213, that is, the liquefied gas fuel supplied to the boiler 10, is not limited to ammonia fuel. Furthermore, the fuel heated in the preheater 211, the heater 212, and the second preheater 213 may be a fuel other than the liquefied gas fuel. Furthermore, the fuel mixed with ammonia fuel during co-combustion is not limited to solid fuel (pulverized fuel).

[0066] The heating method, the heating system, and the power generation plant according to the present embodiment described above can be understood, for example, as follows. In the heating method according to the first aspect of the present disclosure, fuel is heated with heating feedwater extracted from boiler feedwater guided from a condenser (112) to a boiler (10).

[0067] According to the heating method of the present embodiment, the fuel is heated with heating feed water extracted from the boiler feed water, so that it is possible to reduce the adhesion of dirt to the equipment and the frequency of maintenance required due to the adhesion of dirt, compared to the case where the fuel is heated using, for example, seawater or river water. Furthermore, the temperature of the boiler feed water is stable throughout the year compared to, for example, sea water or river water, which facilitates management related to stable heating of the fuel. In addition, even if fuel leaks into the heat medium in the heat transfer section, the leaked fuel can be contained in the boiler feed water and / or heating feed water system, thereby reducing the risk of fuel leaking into the external environment. In addition, compared to a case where heat exchange is performed inside the condenser (112) (i.e., a case where an evaporator is installed inside the condenser (112)), the structure of the condenser (112) can be simplified and / or made smaller. In addition, from the viewpoint of using the existing condenser (112) as is, it is considered that implementation is easier and there is less impact on the performance of the steam turbine compared to the case where an evaporator is installed inside the condenser (112).

[0068] In the heating method according to a second aspect of the present disclosure, in the first aspect, fuel that has been heated by heating feedwater is supplied to the boiler (10).

[0069] According to the heating method of the present aspect, the fuel that has been heated by the heating feed water, that is, the fuel in the form of heating gas, can be supplied to the boiler (10).

[0070] According to a third aspect of the present disclosure, in the heating method of the first or second aspect, the heating feedwater that has exchanged heat with the fuel is guided into the condenser (112).

[0071] According to the heating method of this aspect, the heating feed water that has been subjected to heat exchange with the liquefied gas fuel is introduced into the condenser (112), so that the interior of the condenser (112) can be cooled by the low-temperature heating feed water. This makes it possible to efficiently improve the degree of vacuum in the condenser (112). This is expected to be particularly effective in cases such as summer, when the temperature of seawater or river water used as cooling water for the condenser (112) rises, reducing the degree of vacuum in the condenser and decreasing the efficiency of the steam turbine.

[0072] A heating method according to a fourth aspect of the present disclosure, in any one of the first to third aspects, heats fuel after being heated by heating feed water with heating steam extracted from steam guided to a steam turbine (111C).

[0073] According to the heating method of the present embodiment, the fuel that has been heated by the heating feed water is heated with heating steam extracted from the steam guided to the steam turbine (111C). Therefore, even when the fuel flow rate is high, the fuel can be sufficiently heated and vaporized. An example of a case where the fuel flow rate is high is when the ratio of ammonia fuel is increased during co-firing.

[0074] A heating method according to a fifth aspect of the present disclosure is the fourth aspect, in which drain of heating steam after heat exchange with fuel is joined to heating feedwater before heat exchange with the liquefied gas fuel.

[0075] According to the heating method of the present embodiment, the drain of the heating steam after heat exchange with the fuel is merged with the heating supply water before heat exchange with the fuel, so that the temperature of the heating supply water can be increased by the drain.

[0076] A heating method according to a sixth aspect of the present disclosure is based on any one of the first to fifth aspects, in which the fuel before being heated by the heating feedwater is heated by a heat medium different from the heating feedwater.

[0077] According to the heating method of the present embodiment, the fuel before being heated by the heating feed water is heated by a heat medium different from the heating feed water, so that the liquefied gas fuel before being heated by the heating feed water can be preheated. Examples of heat transfer media other than the heating water include seawater and river water.

[0078] A seventh aspect of the present disclosure relates to a heating method according to any one of the first to sixth aspects, wherein the fuel contains ammonia.

[0079] A heating system according to an eighth aspect of the present disclosure includes a feedwater supply line (L11) and a preheater (211). The feedwater supply line (L11) guides heating feedwater extracted from boiler feedwater guided from a condenser (112) to a boiler (10) to the preheater (211). The preheater (211) heats fuel with the heating feedwater guided by the feedwater supply line (L11).

[0080] A heating system according to a ninth aspect of the present disclosure is the eighth aspect, and is provided with a feedwater return line (L12), which guides the heating feedwater after heat exchange with fuel in the preheater (211) from the preheater (211) to the inside of the condenser (112).

[0081] A heating system according to a tenth aspect of the present disclosure, in the eighth or ninth aspect, includes a steam supply line (L21) and a heater (212), wherein the steam supply line (L21) guides to the heater (212) a drain of heating steam extracted from steam guided from a steam turbine (111C) to the condenser (112), and the heater (212) heats fuel with the drain of heating steam guided from the steam supply line (L21).

[0082] A heating system according to an eleventh aspect of the present disclosure is, in the tenth aspect, provided with a drain return line (L22), which guides drain of heating steam generated by heat exchange in the heater (212) from the heater (212) to the water supply line (L11).

[0083] A heating system according to a twelfth aspect of the present disclosure is, in any of the eighth to eleventh aspects, provided with at least one of a flow meter (243), a thermometer (242), and a level meter (241), and a control unit (250), wherein the flow meter (243) measures the flow rate of the fuel after it has been heated in the preheater (211), the thermometer (242) measures the temperature of the fuel after it has been heated in the preheater (211), and the level meter (241) measures the liquid level of the fuel inside the preheater (211), and the control unit (250) adjusts the flow rate of the heating feedwater flowing through the feedwater supply line (L11) based on a measurement value of at least one of the flow meter (243), the thermometer (242), and the level meter (241).

[0084] A heating system according to a thirteenth aspect of the present disclosure, in the tenth or eleventh aspect, includes at least one of a flow meter (243), a thermometer (242), and a level meter (241), and a control unit (250), wherein the flow meter (243) measures the flow rate of the fuel after it has been heated by the heater (212), the thermometer (242) measures the temperature of the fuel after it has been heated by the heater (212), and the level meter (241) measures the liquid level of the fuel inside the preheater (211) or the heater (212), and the control unit (250) adjusts the flow rate of the heating feedwater flowing through the feedwater supply line (L11) based on the measurement value of at least one of the flow meter (243), the thermometer (242), and the level meter (241).

[0085] A power plant according to a fourteenth aspect of the present disclosure includes a heating system (200) described in any one of the eighth to thirteenth aspects, a boiler to which fuel heated by the heating system is supplied, a steam turbine that is rotated by steam generated in the boiler, and a condenser to which steam discharged from the steam turbine is guided. [Explanation of symbols]

[0086] 1. Power plants 10. Boiler 11 Furnace 12 Combustion gas passage 13 Flue 20 Combustion equipment 21(21A~21F) Burner 22(22A~22F) Fine fuel supply pipe 23 Air register 24 Air duct 31 (31A~31F) Mill (grinder) 32 Forced draft fan (FDF) 41 Gas Duct 42 Air preheater 43 Denitration equipment 44 Dust collection device 45 Induced Draft Fan (IDF) 46 Desulfurization equipment 47 Chimney 101 Furnace wall 102 Superheater 102A 1st superheater 102B 2nd superheater 102C 3rd superheater 103 Reheater 103A 1st reheater 103B 2nd reheater 104 Economizer 111 Steam Turbine 111A High Pressure Turbine 111B Intermediate Pressure Turbine 111C Low Pressure Turbine 112 Condenser 113 Generator 121 Condensate pump (CP) 122 Low pressure water heater 123 Boiler Feed Pump (BFP) 124 High pressure water heater 125 Brackish water separator 126 Steam separator drain tank 127 Boiler Circulation Pump (BCP) 200 Heating System 210 Vaporizer 211 Preheater 212 Heater 213 Second preheater 221 Flow control valve (heating water supply line) 222 Flow meter (heating water supply line) 231 Flow control valve (steam supply line) 232 Drain return pump (Drain return line) 233 On-off valve 234 On-off valve 241 Level Gauge 242 Thermometer 243 Flow meter 250 Control section L1 Boiler feed water line L2 Drain water line L3~L6 Steam lines L7 Circulation Line L11 Heating water supply line (water supply line) L12 Heating water supply return line (water supply return line) L21 Steam supply line L22 Drain return line L22a First drain return line (to heating water supply line) L22b Second drain return line (to condenser) L31 Liquefied fuel supply line L32 connection line L33 Fuel vapor supply line

Claims

1. The fuel is heated with heating feed water taken from the boiler feed water led from the condenser to the boiler. Heating method.

2. The fuel is heated by the heating water and then supplied to the boiler. The heating method according to claim 1 .

3. The heating feed water after heat exchange with the fuel is guided into the condenser. The heating method according to claim 1 .

4. Heating steam extracted from the steam leading to the steam turbine is used to heat the fuel after it has been heated by the heating feed water. The heating method according to claim 1 .

5. The drain of the heating steam after heat exchange with the fuel is merged with the heating feed water before heat exchange with the fuel. The heating method according to claim 4.

6. The fuel before being heated by the heating water is heated by a heat medium different from the heating water. The heating method according to claim 1 .

7. The fuel contains ammonia. The heating method according to any one of claims 1 to 6.

8. A water supply line; A preheater; Equipped with The feedwater supply line guides heating feedwater extracted from boiler feedwater guided from a condenser to a boiler to the preheater, The preheater heats the fuel with the heating feed water guided by the feed water supply line. Heating system.

9. Equipped with a water supply return line, The feedwater return line guides the heating feedwater that has been heat exchanged with the fuel in the preheater from the preheater to the inside of the condenser. The heating system of claim 8.

10. A steam supply line; A heater; Equipped with the steam supply line guides drain of heating steam extracted from steam guided from a steam turbine to the condenser to the heater; The heater heats the fuel with the drain of the heating steam guided from the steam supply line. The heating system of claim 8.

11. Equipped with a drain return line, The drain return line guides drain of the heating steam generated by heat exchange in the heater from the heater to the feedwater supply line. The heating system of claim 10.

12. At least one of a flow meter, a temperature meter, and a level meter; A control unit; Equipped with the flow meter measures a flow rate of the fuel after it has been heated by the preheater, The thermometer measures a temperature of the fuel after it has been heated by the preheater, the level meter measures a liquid level of the fuel inside the preheater, The control unit adjusts the flow rate of the heating feedwater flowing through the feedwater supply line based on a measurement value of at least one of the flow meter, the thermometer, and the level meter. The heating system of claim 8.

13. At least one of a flow meter, a temperature meter, and a level meter; A control unit; Equipped with the flow meter measures a flow rate of the fuel after it has been heated by the heater, The thermometer measures a temperature of the fuel after it has been heated by the heater, the level meter measures a liquid level of the fuel inside the preheater or the heater, The control unit adjusts the flow rate of the heating feedwater flowing through the feedwater supply line based on a measurement value of at least one of the flow meter, the thermometer, and the level meter. The heating system of claim 10.

14. A heating system according to claim 8; the boiler to which fuel heated by the heating system is supplied; a steam turbine that is rotationally driven by steam generated in the boiler; the condenser to which steam discharged from the steam turbine is guided; Equipped with Power generating plant.

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