Ventilation systems and boilers

Abstract

A ventilation system and a boiler are provided that can reduce the impact on the surrounding environment when gaseous fuel leaks. [Solution] A ventilation system 200 for a boiler equipped with an air supply line 26 that conducts combustion air and a fuel supply line that conducts gaseous fuel to a burner, the ventilation system 200 having at least one enclosure 210 that surrounds a point in the fuel supply line where gaseous fuel may leak, and at least one communication section 220 that connects the enclosure 210 to an intake duct 25 (air supply line 26).

Description

[Technical Field]

[0001] The present disclosure relates to a ventilation system and a boiler. [Background technology]

[0002] BACKGROUND ART A boiler provided 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 fuels including, for example, pulverized fuel and gaseous fuel in a burner (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-112280 Summary of the Invention [Problem to be solved by the invention]

[0004] When gaseous fuel is used as fuel, there is a possibility that the gaseous fuel may leak from the fuel supply line. Gaseous fuel is flammable and may also have an odor or toxicity. If the gaseous fuel leaks, it will have a significant impact on the surrounding environment, so there is a need to reduce the impact of the leak.

[0005] The present disclosure has been made in consideration of these circumstances, and aims to provide a ventilation system and a boiler that can reduce the impact on the surrounding environment when gaseous fuel leaks. [Means for solving the problem]

[0006] In order to solve the above problems, the ventilation system and boiler of the present disclosure employ the following measures.

[0007] A ventilation system according to one embodiment of the present disclosure is a ventilation system for a boiler having an air supply line that conducts combustion air and a fuel supply line that conducts gaseous fuel to a burner, and includes at least one enclosure that surrounds a point in the fuel supply line where gaseous fuel may leak, and at least one communication portion that connects the enclosure and the air supply line.

[0008] A boiler according to one aspect of the present disclosure includes the ventilation system, the burner, the air supply line, and the fuel supply line. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to reduce the impact on the surrounding environment when gaseous fuel leaks. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic configuration diagram of a boiler according to an embodiment of the present disclosure. FIG. [Figure 2] 1 is a schematic configuration diagram of a ventilation system according to an embodiment of the present disclosure. [Figure 3] 1 is a diagram illustrating a steam system (water system) of a power plant provided with a boiler according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a ventilation system and a boiler according to an embodiment of the present disclosure will be described with reference to the drawings.

[0012] It should be noted that the present disclosure is not limited to the present embodiment. Furthermore, when there are multiple embodiments, examples, and modifications, they may be combined to form a configuration. Furthermore, "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.

[0013] [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 generates steam (superheated steam) by burning pulverized fuel made from pulverized solid fuel and / or gaseous fuel using multiple burners 21 and heating boiler feedwater and steam with the heat of the combustion gas generated by the combustion.

[0014] Examples of solid fuels include biomass fuels and coal. Examples of gaseous fuels include those that are either toxic or odorous (such as ammonia).

[0015] The boiler 10 of this embodiment includes a furnace 11, a combustion device 20, and a combustion gas passage 12.

[0016] The furnace 11 has a hollow rectangular pillar shape and is installed along the vertical direction. The furnace wall 101, which forms 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 by exchanging heat generated by the combustion of pulverized fuel and / or gaseous fuel with boiler feed water or steam flowing inside each heat transfer tube. The furnace wall 101 is also 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 (sometimes collectively referred to as "burners 21") attached to the furnace wall 101, and a wind box . 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 rows along the vertical direction. In the case of Figure 1, for example, four burners 21 are arranged in 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 21 included in one set, and each set is denoted by the 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 per stage, the arrangement of the burners 21, etc. are not limited to the above-mentioned embodiments.

[0019] Burners 21A, 21B, 21C, 21D, 21E, and 21F are connected to a plurality of mills 31A, 31B, 31C, 31D, 31E, and 31F (sometimes collectively referred to as "mills 31") via pulverized fuel supply pipes 22A, 22B, 22C, 22D, 22E, and 22F (sometimes collectively referred to as "pulverized fuel supply pipes 22").

[0020] As shown in FIGS. 1 and 2, the burners 21A, 21B, 21C, 21D, 21E, and 21F are connected via gas fuel supply pipes 160 to a gas fuel supply source (not shown). The gaseous fuel supply pipe 160 may include a main supply pipe 161 connected to a gaseous fuel supply source and branch supply pipes 162 connecting the main supply pipe 161 to each burner 21 . 2, the main supply pipe 161 itself may be branched into a plurality of pipes, and a plurality of branch supply pipes 162 may be connected to these pipes.

[0021] The main supply pipe 161 is provided with a supply source valve 164, a flow meter 165, a shutoff valve 166, and a flow rate adjustment valve 167 in this order from upstream in the flow direction of the gaseous fuel. The flow meter 165 is connected to the main supply pipe 161 via, for example, a flange joint. In addition, when the main supply pipe 161 itself is branched into a plurality of pipes, it is preferable that the branching occurs at a position downstream of the flow rate adjustment valve 167 .

[0022] A plurality of burner inlet valves 168 and flexible hoses 169 are provided in each branch supply pipe 162 in this order from the upstream side in the flow direction of the gaseous fuel. The burner inlet valve 168 and the flexible hose 169 are connected to the branch supply pipe 162 via, for example, a flange joint.

[0023] The gaseous fuel supply pipe 160 and the various valves and meters provided on the gaseous fuel supply pipe 160 may be collectively referred to as the "fuel supply line."

[0024] Each burner 21 is supplied with pulverized fuel and / or gaseous fuel. That is, each burner 21 is a device capable of firing either pulverized fuel exclusively, gaseous fuel exclusively, or a mixture of pulverized fuel and gaseous fuel. Each burner 21 may be configured such that a burner for pulverized fuel and a burner for gaseous fuel are separately installed.

[0025] As shown in FIG. 1, 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 plurality 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 (carrier gas, oxidizing gas) supplied to the mill 31. The classifier separates the pulverized fuel into pulverized fuel having a particle size 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 primary air via the pulverized fuel supply pipe 22. The coarse pulverized fuel that does not pass through the classifier falls onto the grinding table inside the mill 31 under its own weight and is ground again.

[0026] A wind box 23 is provided outside the furnace 11 at the mounting position of the burner 21, and one end of an air duct 24 is connected to this wind box 23. A forced draft fan 32 (FDF: Forced Draft Fan) is provided at the other end of the air duct 24. The other end of the air duct 24 is connected to the outlet of the forced draft fan 32. On the other hand, an intake duct 25 is connected to the intake port of the forced draft fan 32, so that air is taken in from the outside. In this embodiment, the air duct 24 and the intake duct 25 are regarded as a continuous line (air supply line 26). In other words, the air supply line 26 is provided with the forced draft fan 32, and the air supply line 26 upstream of the forced draft fan 32 is the intake duct 25, and the air supply line 26 downstream of the forced draft fan 32 is the air duct 24. 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 boiler 10 as secondary air (combustion air, oxidizing gas) via the wind box 23 and the burner 21, and is then injected into the furnace 11.

[0027] Above the mounting position of the burner 21, a plurality of additional air ports (AA ports) 25 for supplying additional air (AA) for combustion into the furnace 11 are provided. An end of an additional air duct (AA duct) 28 branching off from the air duct 24 is connected to the additional air port 27, and a portion of the combustion air supplied from the forced draft fan 32 can be supplied to the additional air port 27 via the additional air duct 28 as additional combustion air. In this embodiment, in addition to the air duct 24 and the suction duct 25, the additional air duct 28 is also considered to be the air supply line 26. In other words, the air supply line 26 is a line for guiding secondary air (including additional combustion air) to the boiler 10 (inside the furnace 11), and includes the air duct 24, the suction duct 25, and the additional air duct 28.

[0028] 1, there are two forced draft fans 32. In this case, the air ducts 24 connected to the respective forced draft fans 32 join together at a position upstream of the air preheater 42 in the flow direction of the secondary air. However, the number of forced draft fans 32 may be one, or three or more.

[0029] A communication part 220 of the ventilation system 200 is connected to the air supply line 26 . The ventilation system 200 will be described later.

[0030] The combustion gas passage 12 is connected to the upper part of the furnace 11 in the vertical direction. 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 "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 boiler feedwater or steam flowing inside each heat exchanger. The number, arrangement, and shape of the heat exchangers are not limited to those shown in FIG.

[0031] 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. The flue 13 is provided with an air preheater 42 (air heater), 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 using the air preheater 42 to heat the secondary air supplied to the burner 21 and the additional air port 27, further heat recovery can be performed from the combustion gas after heat exchange with the boiler feedwater and steam.

[0032] Furthermore, 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, such as ammonia for denitration or urea water, which 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.

[0033] 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, that removes ash and the like from the combustion gas, a desulfurization device 46 that removes sulfur oxides, and an induced draft fan (IDF) 45 that guides 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 outside the system as exhaust gas.

[0034] 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 in the air preheater 42 is supplied to the burner 21 from the air duct 24 via the wind box 23. In addition, when performing single-fuel combustion of gaseous fuel or mixed combustion of pulverized fuel and gaseous fuel, the gaseous fuel is supplied to the burner 21 via the gaseous fuel supply pipe 160.

[0035] 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 performing single-fuel combustion of gaseous fuel or mixed combustion of pulverized fuel and gaseous fuel, the burner 21 injects gaseous fuel into the furnace 11. The pulverized fuel mixture and / or gaseous fuel injected into the furnace 11 is ignited and reacts with 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 can be achieved in the furnace 11 by adjusting the ratio of the amount of oxygen to the amount of fuel supplied within an appropriate range.

[0036] The combustion gas that has flowed 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 a denitration device 43, the gas exchanges heat with primary air and secondary air in an air preheater 42, and is then discharged into the gas duct 41, where ash and the like are removed in a dust collector 44, and sulfur oxides are removed in a desulfurization device 46, and the gas is then discharged to the outside of the system through a chimney 47. The arrangement of the heat exchangers in the combustion gas passage 12 and the devices from the flue 13 to the gas duct 41 does not necessarily have to be in the above order relative to the flow of combustion gas.

[0037] 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. 3 is a diagram showing the steam system (water system) of the power plant 1. Note that Figure 1 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 with respect to the combustion gas flow is not limited to that shown in Figure 1.

[0038] As shown in Figure 3, 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.

[0039] The steam turbine 111 includes, 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 to rotate. 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 the low-pressure turbine 111C to rotate.

[0040] A condenser 112 is connected to the low-pressure turbine 111C, and the steam that drives the low-pressure turbine 111C is condensed in this condenser 112 by heat exchange with cooling water (e.g., seawater, river water, or returned heating feedwater, which will be described later) to become condensed water (boiler feedwater). The condenser 112 is connected to the economizer 104 via a boiler feedwater line L1.

[0041] 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 . The low-pressure feedwater heater 122 and the high-pressure feedwater heater 124 are devices that heat the boiler feedwater supplied to the economizer 104 .

[0042] For example, when the boiler 10 is a once-through boiler, the economizer 104 is connected to the heat transfer tubes that form the furnace wall 101 . The boiler feedwater heated in the economizer 104 passes through the boiler feedwater line L1 and 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 then 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.

[0043] Furthermore, during startup or low-load operation of the once-through boiler, the boiler feedwater supplied from the economizer 104 may not all evaporate as it passes through the heat transfer tubes that make up 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 introduced to the steam separator drain tank 126 may be circulated and supplied from the economizer 104 to the heat transfer tubes that make up the furnace wall 101 by using a boiler circulation pump 127 (BCP) to merge with the boiler feedwater line L1 via a circulation line L7.

[0044] When the combustion gas flows through the combustion gas passage 12, heat of this combustion gas is recovered by the superheater 102, the reheater 103, and the economizer 104. Meanwhile, the boiler feedwater supplied from the boiler feedwater pump 123 (BFP) is preheated by the economizer 104, and then heated to become steam as it passes through the heat transfer tubes that make up the furnace wall 101. 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 resuperheated. 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 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, which is sent to the economizer 104 as boiler feed water via the boiler feed water line L1.

[0045] [About the ventilation system] The ventilation system 200 is a system for reducing the impact on the surrounding environment when gaseous fuel leaks from a location in the fuel supply line where there is a possibility of gaseous fuel leaking. Here, the locations where gaseous fuel may leak refer to, for example, connection locations in the gaseous fuel supply pipe 160 (locations connected by joints such as flanges or screws), various valves (gland seals, etc.) and various instruments (diaphragms of pressure gauges, etc.) provided in the gaseous fuel supply pipe 160, as shown in FIG. 2.

[0046] The ventilation system 200 includes an enclosure portion 210 and a communication portion 220 .

[0047] The surrounding portion 210 is a portion that surrounds a location where there is a possibility of gaseous fuel leaking. The enclosure 210 may collectively surround a plurality of locations from which the gaseous fuel may leak, may surround individual locations from which the gaseous fuel may leak, or may be a combination of these. In any case, the enclosure 210 surrounds a space in which the locations from which the gaseous fuel is likely to leak are located. This allows the leaked gaseous fuel to be contained within the space inside the enclosure 210 even if the gaseous fuel leaks from the fuel supply line.

[0048] Note that "enclosed" here does not mean forming a completely sealed space, but rather means being in communication with the outside to the extent that air for ventilation can be taken in from the outside.

[0049] The enclosure 210 may be, for example, a flexible sheet material such as a vinyl curtain or a fireproof sheet hung from the ceiling to the floor. In this case, the sheet material functions as the side surface of the enclosure 210, the ceiling functions as the top surface of the enclosure 210, and the floor functions as the bottom surface of the enclosure 210. The walls of existing equipment may be used as the side surfaces. Furthermore, if equipment is located in spaces vertically separated by floors, openings can be created in the floors or the floors can be replaced with floors with openings (e.g., gratings), allowing the upper and lower spaces to be treated as a single unit. Naturally, components that function as upper and lower surfaces may also be installed.

[0050] The shape of the enclosure 210 can be changed appropriately depending on the shape, size, arrangement, etc. of the object, and is not particularly limited. Furthermore, the material of the enclosure 210 is not limited to a flexible sheet material, and the enclosure 210 may be made of, for example, metal or resin.

[0051] The communication section 220 is a section that connects the enclosure section 210 and the air supply line 26, and communicates the space formed inside the enclosure section 210 with the space (flow path) formed inside the air supply line 26. A flow path is formed inside the communication portion 220 . One end of the communication part 220 is connected to the enclosure part 210, and the other end is connected to the air supply line 26. One end of the flow path formed inside the communication part 220 is connected to the space formed inside the enclosure part 210, and the other end is connected to the flow path formed inside the air supply line 26.

[0052] As described above, in the flow path inside the air supply line 26, a flow of secondary air (including additional air for combustion) toward the boiler 10 is formed by the forced draft fan 32. Therefore, the end of the flow path of the communication part 220 communicates with the flow path of the air supply line 26, so that gas in the space inside the enclosure part 210 is drawn into the flow path of the air supply line 26 via the flow path of the communication part 220. If gaseous fuel leaks into the space inside the enclosing portion 210, the gaseous fuel, together with the gas in the space inside the enclosing portion 210, is drawn into the flow path of the air supply line 26 via the flow path of the communication portion 220. In other words, the space formed inside the enclosing portion 210 is ventilated. The gaseous fuel drawn into the flow path of the air supply line 26 is supplied to the burner 21 (where combustion is performed using pulverized fuel and / or gaseous fuel) and the additional air port 27 together with secondary air, and is incinerated in the boiler 10.

[0053] From the viewpoint of efficiently drawing in the gaseous fuel, it is preferable that the communication part 220 is connected to the air supply line 26 (i.e., the suction duct 25) upstream of the forced draft fan 32 in the flow direction of the secondary air. This is because the flow path formed inside the suction duct 25 becomes a negative pressure region. Furthermore, by connecting the communication portion 220 to the intake duct 25, the enclosure portion 210 also functions as a part of the intake port for the forced draft fan 32. Therefore, the intake loss of the forced draft fan 32 can be reduced.

[0054] The forced draft fan 32 basically operates constantly during operation of the boiler 10. Therefore, the space formed inside the enclosure 210 is also constantly ventilated. This allows the internal space of the enclosure 210 to be treated as a highly ventilated area when defining an explosion-proof area (hazardous location) for gaseous fuel. In other words, depending on the explosiveness of the gaseous fuel, the internal space of the enclosure 210 can be excluded from the explosion-proof area.

[0055] The communication part 220 may be configured to prevent gas from leaking to the outside, and may be, for example, a duct, a pipe, a hose, or the like. The material of the communication portion 220 is not particularly limited as long as it is not corroded by the gaseous fuel.

[0056] As shown in FIG. 2, the enclosure 210 includes an overall enclosure 211 and / or at least one individual enclosure 212. The overall enclosing portion 211 is one form of the enclosing portion 210 that encloses all the locations where there is a possibility of leakage of gaseous fuel. In the case of Fig. 2, the overall enclosing portion 211 encloses the burner inlet valves 168 and flexible hoses 169 provided on the multiple branch supply pipes 162. The individual enclosing portions 212 are one form of the enclosing portion 210 that individually encloses locations where there is a possibility of gaseous fuel leakage. In the case of Fig. 2, the individual enclosing portions 212 separately enclose the flow meter 165 (including the connecting flange) provided in the main supply pipe 161, the gland portion of the shutoff valve 166, and the gland portion of the flow rate adjustment valve 167.

[0057] The communication portion 220 includes a common communication portion 221 and / or at least one branch communication portion 222. One end of the branch communication portion 222 is connected to each surrounding portion 210 (overall surrounding portion 211 and individual surrounding portion 212). On the other hand, the other end of the branch communication portion 222 is connected to the common communication portion 221. One end of the common communication part 221 is connected to the intake duct 25 (air supply line 26). As a result, the space inside each enclosure part 210 is connected to a flow path formed inside the intake duct 25 (air supply line 26) via the branch communication part 222 and the common communication part 221. In other words, the common communication part 221 functions as a header for the branch communication part 222. The other end of the common communication portion 221 is, for example, closed.

[0058] When there are a plurality of intake ducts 25 as shown in FIG. 2, the common communication portion 221 may be branched into a plurality of portions. However, when the common communication part 221 is branched into a plurality of parts, it is preferable that all of the branch communication parts 222 are branched at a position downstream of the joining position.

[0059] The common communication part 221 may be provided with a check damper 226 that has a function of preventing backflow. This makes it possible to prevent the secondary air from flowing back from the intake duct 25 into the enclosure 210 . When the common communication part 221 branches into a plurality of parts, it is preferable to provide a check damper 226 in each common communication part 221 .

[0060] [About the exhaust section] The ventilation system 200 may include an exhaust section 230 . The exhaust section 230 is a part that connects the communication section 220 with the outside of the ventilation system 200 (hereinafter referred to as "outside the system"), and connects the flow path formed inside the communication section 220 with the outside of the system. A flow path is formed inside the exhaust part 230 . One end of the exhaust section 230 is connected to the common communication section 221 (a position downstream of the position where all the branch communication sections 222 join together).

[0061] The exhaust section 230 is provided with an exhaust mechanism. The exhaust mechanism is a mechanism that generates a gas flow in a flow path formed inside the exhaust unit 230 toward the outside of the system. The exhaust mechanism is exemplified by an exhaust fan 231 provided at the other end (exhaust port) of the exhaust section 230.

[0062] As a result, even if the forced draft fan 32 installed in the air supply line 26 breaks down while gaseous fuel is leaking and it becomes impossible to guide the leaked gaseous fuel to the boiler 10 via the air supply line 26, the gaseous fuel can be discharged outside the system via the exhaust section 230.

[0063] The exhaust unit 230 may be configured to prevent gas from leaking to the outside, and may be, for example, a duct, a pipe, a hose, or the like. The material of the exhaust portion 230 is not particularly limited as long as it is not attacked by the gaseous fuel.

[0064] When the common communication part 221 branches into a plurality of parts, it is preferable that one end of the exhaust part 230 is connected to a position of the common communication part 221 before the branching.

[0065] The gaseous fuel is discharged to the outside of the system, for example, in the following cases. That is, when gaseous fuel is leaking and an abnormality occurs in the forced draft fan 32, the gaseous fuel is discharged via the exhaust part 230. Here, an abnormality in the forced draft fan 32 refers to, for example, a decrease in output due to a malfunction (including a stoppage due to a malfunction), and means a state in which the negative pressure in the intake duct 25 cannot be sufficiently secured.

[0066] Whether or not gaseous fuel is leaking is determined using, for example, the gas detector 251. The gas detector 251 is, for example, an instrument capable of measuring the concentration of one or more components contained in the gaseous fuel, and is capable of detecting the gaseous fuel. The gas detector 251 is provided, for example, at a location where it can detect the gaseous fuel present inside the communication part 220. The gas detector 251 is configured to be able to communicate with the control unit 250. Furthermore, the control unit 250 is configured to be able to communicate with the forced draft fan 32 and the exhaust fan 231. When the gas detector 251 detects gaseous fuel and detects an abnormality in the forced draft fan 32, the control unit 250 determines that gaseous fuel is leaking and that the forced draft fan 32 is in an abnormal state, and starts operating the exhaust fan 231 to discharge the gaseous fuel.

[0067] [Variations] Instead of the exhaust fan 231, the outlet of the exhaust unit 230 may be provided at a high position to generate a gas flow by utilizing the chimney effect. In this case, an on-off valve controlled by the control unit 250 may be provided in the exhaust unit 230 .

[0068] The exhaust section 230 may be provided with a check damper 236 . This prevents the effective intake of air from the enclosure 210 from being impaired by the forced draft fan 32 drawing in outside air through the exhaust fan 231 in preference to the intake of air from the enclosure 210 when the exhaust fan 231 is stopped.

[0069] The gas detector 251 may be provided at a location where it can detect the gaseous fuel present inside each enclosure 210, for example. Furthermore, the gas detector 251 may be provided at a plurality of locations where the gaseous fuel present inside the communication portion 220 and inside each of the surrounding portions 210 can be detected.

[0070] [Air volume control damper] The common communication part 221 may be provided with an air volume adjustment damper 227 in order to guide a predetermined amount of gas to the intake duct 25 (air supply line 26 ) regardless of the output of the forced draft fan 32 . The flow rate of gas introduced into air duct 24 is determined taking into consideration the amount of ventilation required for each enclosure 210. The amount of ventilation required for enclosure 210 is calculated as the amount of outside air (air) sufficient to ensure the degree of ventilation required to prevent the creation of an explosive atmosphere in that enclosure 210, based on, for example, officially recommended standards (such as the technical guidelines of the National Institute of Occupational Safety and Health).

[0071] The air volume adjustment damper 227 is preferably provided at a position downstream of the position where the exhaust section 230 joins. Furthermore, when the common communication part 221 branches into a plurality of parts, the air volume adjustment damper 227 is preferably provided at a position before the common communication part 221 branches.

[0072] In addition, in order to guide a predetermined amount of gas outside the system regardless of the output of the exhaust fan 231, an air volume adjustment damper 237 may be provided in the exhaust unit 230.

[0073] The opening degree of the air volume adjustment damper 227 and / or the opening degree of the air volume adjustment damper 237 may be fixed or may be controlled by the control unit 250.

[0074] [Variations] The gaseous fuel is not limited to ammonia, and may be, for example, CO (carbon monoxide), COG (coke oven gas), BFG (blast furnace gas), waste decomposition gas (methane gas generated from garbage and livestock manure, etc.), etc.

[0075] [effect] According to this embodiment, the following effects are achieved. The fuel supply line includes at least one surrounding portion 210 surrounding a location where gaseous fuel may leak, and at least one communication portion 220 communicating the interior of the surrounding portion 210 with a flow path formed in the air supply line 26. Even if gaseous fuel leaks from the fuel supply line, the leaked gaseous fuel can be trapped inside the surrounding portion 210 and guided to the air supply line 26 via the communication portion 220. This reduces the impact of gaseous fuel leakage on the surrounding environment. For example, it reduces the possibility of an explosive atmosphere occurring around a location where gaseous fuel may leak. It also reduces the degree of poisoning and unpleasant odors. Furthermore, the leaked gaseous fuel is supplied to the burner 21 together with secondary air via the air supply line 26, so that it can be safely incinerated in the boiler 10.

[0076] When a forced draft fan 32 is provided in the air supply line 26 and the communication section 220 is connected to the air supply line 26 (intake duct 25) upstream of the forced draft fan 32 in the flow direction of the secondary air, the flow path formed inside the intake duct 25 is a negative pressure area, so that leaked gaseous fuel can be efficiently guided to the air supply line 26. Furthermore, since air is taken into the enclosure 210 from the outside, the enclosure 210, which communicates with the flow path formed inside the intake duct 25 via the communication part 220, also functions as a part of the intake port for the forced draft fan 32. Therefore, the intake loss of the forced draft fan 32 can be reduced.

[0077] When there are multiple air ducts 24 and the enclosure 210 is connected to at least one of the air ducts 24, even if one of the forced draft fans 32 provided in the multiple air ducts 24 fails, the leaked gaseous fuel can be guided to the air duct 24 provided with the non-failed forced draft fan 32.

[0078] The enclosure 210 surrounds at least one of the valves, pipe connections, and meters through which the gaseous fuel flows, and therefore can reliably prevent leakage of the gaseous fuel from any location.

[0079] If the system is provided with an exhaust section 230 connecting the inside of the communication section 220 with the outside of the system, and the exhaust section 230 is provided with an exhaust mechanism that generates a fluid flow toward the outside of the system, even if the forced draft fan 32 provided in the air duct 24 fails and it becomes impossible to guide the gaseous fuel to the air duct 24, the gaseous fuel can be discharged outside the system through the exhaust section 230.

[0080] The system is equipped with a gas detector 251 that detects gaseous fuel present inside the communication section 220 or inside the surrounding section 210, and a control section 250. When the gas detector 251 detects gaseous fuel and detects an abnormality in the forced draft fan 32, the control section 250 operates the exhaust fan 231. Therefore, when there is a leakage of gaseous fuel and the forced draft fan 32 is in an abnormal state, the gaseous fuel can be guided outside the system via the exhaust section 230.

[0081] [Note] The ventilation system and boiler according to the present embodiment described above can be understood, for example, as follows.

[0082] A ventilation system (200) according to a first aspect of the present disclosure is a ventilation system (200) for a boiler (10) having an air supply line (26) for guiding combustion air and a fuel supply line for guiding gaseous fuel to a burner (21), and includes at least one enclosure (210) surrounding a location in the fuel supply line where gaseous fuel may leak, and at least one communication part (220) connecting the enclosure (210) and the air supply line (26).

[0083] The fuel supply line includes at least one enclosure (210) surrounding a location where gaseous fuel may leak, and at least one communication section (220) connecting the enclosure (210) to the air supply line (26). Even if gaseous fuel leaks from the fuel supply line, the leaked gaseous fuel can be contained within the enclosure (210) and guided to the air supply line (26) via the communication section (220). This reduces the impact of gaseous fuel leakage on the surrounding environment. For example, it reduces the possibility of an explosive atmosphere occurring around the location where gaseous fuel may leak. It also reduces the degree of poisoning and unpleasant odors. Furthermore, the leaked gaseous fuel is supplied to the burner (21) and the additional air port (27) together with the combustion air through the air supply line (26), so that it can be safely incinerated in the boiler (10).

[0084] In the ventilation system (200) according to the second aspect of the present disclosure, in the first aspect, the air supply line (26) is provided with a forced draft fan (32) that generates a flow of combustion air toward a boiler (10), and the communication part (220) is connected to the air supply line (26) upstream of the forced draft fan (32) in the flow direction of the combustion air.

[0085] The air supply line (26) is provided with a forced draft fan (32) that generates a flow of combustion air toward the boiler (10), and the communication section (220) is connected to the air supply line (26) upstream of the forced draft fan (32) in the flow direction of the combustion air, so that leaked gaseous fuel can be efficiently guided to the air supply line (26). In addition, since air is taken into the enclosure (210) from the outside, the enclosure (210) communicates with the flow path formed inside the intake duct 25 via the communication part (220), and therefore functions as a part of the intake port for the forced draft fan (32). As a result, the intake loss of the forced draft fan (32) can be reduced.

[0086] In the ventilation system (200) according to the third aspect of the present disclosure, in the second aspect, the number of the air supply lines (26) is plural, and the enclosure (210) is connected to at least one of the air supply lines (26).

[0087] The number of air supply lines (26) is plural, and the enclosure portion (210) is connected to at least one of the air supply lines (26). Therefore, even if one of the push-in fans (32) provided in the plural air supply lines (26) breaks down, the leaked gaseous fuel can be guided to the air supply line (26) provided with the unbroken push-in fan (32).

[0088] A ventilation system (200) according to a fourth aspect of the present disclosure is any one of the first to third aspects, wherein the enclosure (210) surrounds at least one of a valve through which gaseous fuel flows, a piping connection point, and an instrument.

[0089] The enclosure (210) surrounds at least one of the valves, pipe connections, and meters through which the gaseous fuel flows, thereby providing reliable measures against locations where the gaseous fuel may leak.

[0090] A ventilation system (200) according to a fifth aspect of the present disclosure is any one of the second to fourth aspects, and includes an exhaust section (230) connecting the inside of the communication section (220) with the outside of the system, and the exhaust section (230) is provided with an exhaust mechanism that generates a flow of fluid toward the outside of the system.

[0091] The system is provided with an exhaust section (230) that connects the inside of the communication section (220) with the outside of the system, and the exhaust section (230) is provided with an exhaust mechanism that generates a fluid flow toward the outside of the system. Therefore, even if the forced draft fan (32) provided in the air supply line (26) breaks down and it becomes impossible to guide the gaseous fuel to the air supply line (26), the gaseous fuel can be discharged outside the system via the exhaust section (230).

[0092] The ventilation system (200) according to a sixth aspect of the present disclosure is the fifth aspect, and further includes a gas detector (251) for detecting gaseous fuel present in the communication part (220) and / or the enclosure part (210), and a control part (250). When the gas detector (251) detects gaseous fuel and detects an abnormality in the forced draft fan (32), the control part (250) operates the exhaust fan (231) as the exhaust mechanism.

[0093] The system includes a gas detector (251) that detects gaseous fuel present in the communication section (220) and / or the surrounding section (210), and a control section (250). The air supply line (26) is provided with a forced draft fan (32) that generates a flow of combustion air toward the plurality of burners (21). When the gas detector detects gaseous fuel and detects an abnormality in the forced draft fan (32), the control section (250) operates the exhaust fan (231) as an exhaust mechanism. Therefore, in a situation where there is a leakage of gaseous fuel and the forced draft fan (32) is in an abnormal state, the gaseous fuel can be guided out of the system via the exhaust section (230).

[0094] A ventilation system (200) according to a seventh aspect of the present disclosure is any one of the first to sixth aspects, wherein the gaseous fuel is a fuel having at least one of odor and toxicity.

[0095] A ventilation system (200) according to an eighth aspect of the present disclosure is the ventilation system (200) of any one of the first to seventh aspects, wherein the gaseous fuel is a fuel containing ammonia.

[0096] A boiler (10) according to a ninth aspect of the present disclosure includes the ventilation system (200) according to any one of the first to eighth aspects, a plurality of the burners (21), the air supply line (26), and the fuel supply line. [Explanation of symbols]

[0097] 1. Power Plant 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 Wind Box 24 Air Duct 25 Intake duct 26 Air supply line 27 Additional air port 28 Additional air duct 31 (31A~31F) Mill (crusher) 32 Forced draft fan (FDF, forced draft fan) 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 160 Gaseous fuel supply pipe 161 Main supply pipe 162 Branch supply pipe 164 Supply valve 165 Flow meter 166 Shut-off valve 167 Flow control valve 168 Burner inlet valve 169 Flexible Hose 200 Ventilation System 210 Encirclement 211 Overall Enclosure 212 Individual Enclosure 220 Communication part 221 Common communication section 222 Branch communication section 226 Check Damper 227 Air flow control damper 230 Exhaust section 231 Exhaust fan 236 Check Damper 237 Air flow control damper 250 control section 251 Gas detector

Claims

1. 1. A ventilation system for a boiler having an air supply line for conducting combustion air and a fuel supply line for conducting gaseous fuel to a burner, comprising: at least one enclosure surrounding a location in the fuel supply line where gaseous fuel may leak; At least one communication section connecting the surrounding section and the air supply line; Equipped with Ventilation system.

2. The air supply line is provided with a forced draft fan that generates a flow of combustion air toward the boiler, The communication portion is connected to the air supply line upstream of the forced draft fan in the flow direction of the combustion air. The ventilation system of claim 1 .

3. The number of the air supply lines is plural, The enclosure is connected to at least one of the air supply lines.

3. The ventilation system of claim 2.

4. The enclosure surrounds at least one of a valve through which the gaseous fuel flows, a piping connection point, and a meter. The ventilation system of claim 1 .

5. an exhaust part connecting the communication part to the outside of the system, The exhaust unit is provided with an exhaust mechanism that generates a flow of fluid toward the outside of the system.

3. The ventilation system of claim 2.

6. a gas detector that detects gaseous fuel present in the communication section and / or the surrounding section; A control unit; Equipped with The control unit operates an exhaust fan as the exhaust mechanism when the gas detector detects gaseous fuel and detects an abnormality in the forced draft fan.

6. The ventilation system of claim 5.

7. 7. The ventilation system according to claim 1, wherein the gaseous fuel is a fuel having one or more of toxicity and odor.

8. The gaseous fuel is considered to be a fuel containing ammonia. A ventilation system according to any one of claims 1 to 6.

9. The ventilation system of claim 1; the burner; the air supply line; the fuel supply line; Equipped with Boiler.

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