WO2018083889A1

WO2018083889A1 - Boiler system

Info

Publication number: WO2018083889A1
Application number: PCT/JP2017/033136
Authority: WO
Inventors: 一芳伊藤; 建聖渡邊
Original assignee: 住友重機械工業株式会社
Priority date: 2016-11-04
Filing date: 2017-09-13
Publication date: 2018-05-11
Also published as: KR20190077315A; PH12019500909A1; JP6712534B2; MY194582A; JP2018071951A; KR102337478B1

Abstract

A boiler system, provided with: a furnace that heats a heat conduction medium by the burning of a fuel; a heat exchanger embedded in the heat conduction medium heated by the furnace, the heat exchanger channeling a fluid that exchanges heat with the heat conduction medium; and a removal part that, during an emergency stop when the flow of the fluid at least in the heat exchanger decreases or stops, controls a removal part and removes the heat conduction medium from around the heat exchanger.

Description

Boiler system

The present invention relates to a boiler system.

As a conventional boiler system, one that heats a heat transfer medium by burning fuel is known (see, for example, Patent Document 1). The heated heat transfer medium circulates in a circulation system in the system. In such a circulation system, there is a place where the heat transfer medium is stored. The boiler system includes a heat exchanger buried in the heat transfer medium at the location where the heat transfer medium is stored in this manner. A fluid flows inside the heat exchanger, and heat exchange is performed between the fluid and the heat transfer medium.

JP 2001-41415 A

Here, the boiler system as described above may be urgently stopped for a predetermined reason. At the time of emergency stop, the fluid flowing in the heat exchanger buried in the heat transfer medium decreases or the fluid does not flow in the heat exchanger. In the said state, the cooling function of a heat exchanger falls and the temperature of a heat exchanger may become high too much with the heat of the surrounding heat-transfer medium.

This invention aims at providing the boiler system which can protect appropriately the heat exchanger buried in the heat-transfer medium at the time of emergency stop.

A boiler system according to an embodiment of the present invention is embedded in a furnace that heats a heat transfer medium by combustion of fuel and a heat transfer medium heated in the furnace, and performs heat exchange with the heat transfer medium. A heat exchanger through which the fluid flows, and a removal unit that controls the removal unit and removes the heat transfer medium from the periphery of the heat exchanger at an emergency stop in which the flow of the fluid in the heat exchanger is reduced or stopped. Prepare.

The boiler system includes a heat exchanger through which a fluid that exchanges heat with the heat transfer medium flows. This heat exchanger is buried in a heat transfer medium heated in a furnace. The boiler system also includes a removal unit that controls the removal unit and removes the heat transfer medium from the periphery of the heat exchanger at the time of an emergency stop in which the flow of the fluid in the heat exchanger is reduced or stopped. Therefore, even if the flow of fluid in the heat exchanger decreases or stops during an emergency stop, the heat transfer medium is removed from the surroundings of the heat exchanger, so the temperature of the heat exchanger increases due to the heat of the heat transfer medium. It can suppress that it is too much. As described above, the heat exchanger buried in the heat transfer medium at the time of emergency stop can be appropriately protected.

The boiler system may further include a turbine that rotates with steam generated by combustion in the furnace, and the heat exchanger may be a reheater that superheats steam discharged from the turbine as a fluid. With this configuration, it is possible to appropriately protect the reheater buried in the heat transfer medium during an emergency stop.

The boiler system includes a circulation system that circulates the heat transfer medium, including at least a furnace, and the removal unit removes the heat transfer medium from the surroundings of the heat exchanger by discharging the heat transfer medium out of the circulation system. You can do it. With this configuration, the heat exchanger can be protected with a simple configuration in which the heat transfer medium is discharged out of the circulation system during an emergency stop.

In the boiler system, the evacuation unit has a control unit that controls the boiler system, and the control unit detects the flow state of the steam to the reheater and reduces or stops the flow of the steam to the reheater. When it detects, you may perform control which removes a heat-transfer medium from the circumference | surroundings of a reheater. With this configuration, it is possible to remove the heat transfer medium from the periphery of the reheater after confirming that the flow of steam to the reheater has actually decreased or stopped. Thereby, the reheater can be protected at an appropriate timing.

According to the present invention, the heat exchanger buried in the heat transfer medium is appropriately protected during an emergency stop.

It is a schematic structure figure of a boiler system concerning an embodiment of the present invention. It is a schematic block diagram which shows the structure of the turbine periphery of the boiler system shown in FIG. It is a schematic block diagram which shows the structure of the heat exchange chamber periphery of the boiler system shown in FIG. It is a schematic block diagram which shows the structure of the heat exchange chamber vicinity of the boiler system which concerns on a modification.

Embodiments of the present invention will be described with reference to the drawings. However, the following embodiments are merely examples for explaining the present invention and are not intended to limit the present invention to the following contents. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

The configuration of the boiler system 100 according to the present embodiment will be described with reference to FIG. The boiler system 100 is an external circulation type (circulating fluidized bed type) circulating fluidized bed boiler. The boiler system 100 includes a fluidized bed furnace 3 having a vertically long cylindrical shape. A fuel supply port 3a for supplying fuel is provided in the middle part of the furnace 3, and a gas outlet 3b for discharging combustion gas is provided in the upper part. The fuel supplied from the fuel supply device 5 to the furnace 3 is supplied into the furnace 3 through the fuel supply port 3a.

A cyclone 7 that functions as a solid-gas separator is connected to the gas outlet 3 b of the furnace 3. The discharge port 7a of the cyclone 7 is connected to a downstream gas processing system via a gas line. A return line 9 called a downcomer extends downward from the bottom outlet of the cyclone 7, and the lower end of the return line 9 is connected to the intermediate side surface of the furnace 3.

In the furnace 3, the solid material containing the fuel supplied from the fuel supply port 3a flows by the combustion / flowing air introduced from the lower air supply line 3c, and the fuel flows while the fuel flows, for example, about 800 to 900. Burn at ℃. A combustion gas generated in the furnace 3 is introduced into the cyclone 7 with accompanying solid particles. The cyclone 7 separates solid particles and gas by a centrifugal separation action, returns the solid particles separated via the return line 9 to the furnace 3, and removes the combustion gas from which the solid particles have been removed from the discharge port 7 a to the gas line. To the subsequent gas processing system.

In this furnace 3, a solid material called “in-furnace bed material” is generated and collected at the bottom, and the bed material is sintered and melted and solidified by the concentration of impurities (low melting point materials, etc.) in the in-furnace bed material, or It is necessary to suppress malfunctions caused by incombustible impurities. For this reason, in the furnace 3, the in-furnace bed material is discharged | emitted regularly or continuously outside from the discharge port 3d of the bottom part. The discharged bed material is supplied to the furnace 3 again after removing unsuitable materials such as metal and coarse particle diameter on a circulation line (not shown).

The gas treatment system includes a gas heat exchange device 13 connected to the discharge port 7a of the cyclone 7 via a gas line, and a dust collector 15 connected to the discharge port 13a of the gas heat exchange device 13 via a gas line. And. The gas heat exchanger 13 is provided with a boiler tube 13b that superheats steam so as to cross the exhaust gas flow path. When the high-temperature exhaust gas sent from the cyclone 7 comes into contact with the boiler tube 13b, the heat of the exhaust gas is recovered in the water in the tube, and the generated high-temperature steam is sent to the turbine for power generation through the boiler tube 13b. The dust collector 15 removes fine particles such as fly ash that are still accompanying the combustible gas. As the dust collector 15, for example, a bag filter or an electric dust collector is adopted. The clean gas discharged from the discharge port 15 a of the dust collector 15 is discharged to the outside through the gas line and the pump 17 from the chimney 19.

Solid particles generated in the furnace 3 circulate in the circulation system 21 including the furnace 3, the cyclone 7, and the return line 9. In the following description, the fluid of solid particles is referred to as a heat transfer medium. In the circulation system 21, a heat exchange chamber 20 is formed between the return line 9 and the bottom of the furnace 3. A heat transfer medium is stored in the heat exchange chamber 20 (see FIGS. 2 and 3). A heat exchanger 22 is provided in the heat exchange chamber 20. Detailed configurations of the heat exchange chamber 20 and the heat exchanger 22 will be described later.

The boiler system 100 includes a turbine that rotates with steam generated by the combustion of the furnace 3. The configuration around the turbine will be described with reference to FIG. As shown in FIG. 3, the boiler system 100 includes an evaporation pipe 31, a steam / water separator 32, a superheater 33,

turbines

50 and 51, a steam supply unit 37, and a reheat functioning as a heat exchanger 22. A vessel 34, a heat exchange chamber 20, a removal unit 24, and a control unit 30.

The evaporation pipe 31 generates steam by evaporating water using the heat of the boiler furnace. The evaporation pipe 31 evaporates the water supplied from the upstream side, and then supplies the steam, which is in the state of an air / water mixture, to the air / water separator 32. The steam separator 32 separates the steam from the steam / water mixture from the evaporation pipe 31. The steam separated by the steam separator 32 flows to the superheater 33 on the downstream side.

The superheater 33 superheats the steam from the steam separator 32 and supplies the turbine 50 as superheated steam by further heating the saturated steam. The superheater 33 includes an introduction part 41 that introduces steam, a superheat part 42 that superheats the steam introduced from the introduction part 41, and a discharge part 43 that exhausts the steam superheated by the superheat part 42. .

The introduction part 41 is constituted by a line connecting the steam separator 32 and the superheat part 42. The overheating unit 42 includes

heat exchange units

44, 46, and 48 and

adjustment units

45 and 47. The

heat exchanging units

44, 46, and 48 superheat the steam by heat exchange. In the uppermost heat exchange section 44, the steam is heated to about 350 to 470 ° C. In the lowermost heat exchange section 48, the steam is heated to about 450 to 570 ° C. However, the temperature of the steam is appropriately changed depending on the plant and is not particularly limited. The adjusting

units

45 and 47 adjust the superheated steam to a target temperature by supplying water to the steam. The adjustment unit 45 is disposed between the heat exchange unit 44 and the heat exchange unit 46. The adjustment unit 47 is disposed between the heat exchange unit 46 and the heat exchange unit 48. However, the configuration of the superheater 42 is not limited to such a configuration. The discharge part 43 is configured by a line connecting the heat exchange part 48 and the turbine 50.

The turbine 50 rotates by being supplied with the steam discharged from the discharge part 43 of the superheater 33, and generates electricity. Further, the turbine 51 is provided at the rear stage of the turbine 50 and rotates by being supplied with the steam supplied from the reheater 34 to generate electricity. Therefore, the pressure and temperature of the steam discharged from the turbine 50 are lower than the steam in the discharge part 43 of the superheater 33. Although not particularly limited, the pressure of the steam supplied to the turbine 50 is about 10 to 17 MPa (gauge pressure), and the temperature is about 530 to 570 ° C. The pressure of the steam discharged from the turbine 50 is about 3 to 5 MPa (gauge pressure), and the temperature is about 350 to 400 ° C.

The steam supply unit 37 extracts steam from the discharge unit 43 of the superheater 33 and supplies the extracted steam to the reheater 34. The steam supply unit 37 includes a line 53 that bypasses the turbine 50 by directly connecting the discharge unit 43 of the superheater 33 and the line 61, and a valve 54 provided on the line 53. The valve 54 is an open / close valve that opens and closes based on a control signal from the control unit 30. The valve 54 includes a mechanism for pouring water into the passing steam, and can cool (and reduce pressure) the steam. The steam supply unit 37 is used to prevent the reheater 34 from being blown when the boiler system 100 is activated.

The reheater 34 reheats the steam discharged from the turbine 50. The turbine 50 and the reheater 34 are connected by a line 61 for supplying the steam discharged from the turbine 51 to the reheater 34. Further, the reheater 34 and the turbine 51 are connected by a line 62 for supplying steam reheated by the reheater 34 to the turbine 51. Therefore, the steam supplied to the reheater 34 via the line 61 is resuperheated by heat exchange in the reheater 34 and then supplied to the turbine 51 on the rear stage side via the line 62. Here, in the present embodiment, the reheater 34 functions as the heat exchanger 22 disposed in the heat exchange chamber 20.

Here, FIG. 3 is an enlarged view showing a schematic structure around the heat exchange chamber 20. The structure around the heat exchange chamber 20 will be described in detail with reference to FIG.

The heat exchange chamber 20 is provided below the return line 9. The return line 9 and the lower end portion of the furnace 3 are connected via a loop seal portion 23. The loop seal portion 23 is where the flow path of the heat transfer medium W is narrowed. Thereby, the heat transfer medium W flows in and is discharged in a state where a predetermined amount of the heat transfer medium W is stored in the heat exchange chamber 20. Further, the heat transfer medium W in the heat exchange chamber 20 is heated in the furnace 3 and is in a high temperature state, and is about 700 to 900 ° C. The heat exchanger 22 is provided in the heat exchange chamber 20. Therefore, during normal operation of the boiler system 100, the heat exchanger 22 is embedded in the heat transfer medium heated in the furnace 3.

The heat exchanger 22 constituted by the reheater 34 is constituted by a pipe through which a fluid that exchanges heat with the heat transfer medium W flows. Here, steam flows as a fluid in the heat exchanger 22. In the heat exchange chamber 20, the piping is stretched so as to meander in a predetermined direction (vertical direction in the figure). However, how the pipes are stretched is not particularly limited, and the pipes may meander in the horizontal direction or spirally.

The removing unit 24 removes the heat transfer medium W from the periphery of the heat exchanger 22. The removal unit 24 illustrated in FIG. 3 includes a discharge line 26 provided in the heat exchange chamber 20 and a switching valve 27 provided on the discharge line 26. In the present embodiment, the removing unit 24 discharges the heat transfer medium W out of the circulation system 21. Therefore, one end side of the discharge line 26 is connected to the heat exchange chamber 20, and the other end side is opened outside the system. Note that a tank 28 for receiving the discharged heat transfer medium W is provided on the other end side of the discharge line 26. When a certain amount or more of the heat transfer medium W is stored in the tank 28, the heat transfer medium W in the tank 28 may be returned to the circulation system 21. Alternatively, the tank 28 may not be provided and may be disposed when the heat transfer medium W is discharged from the discharge line 26. In the removal unit 24, the heat transfer medium W may be discharged from the heat exchange chamber 20 by gravity.

The switching valve 27 is a valve for switching opening and closing on the discharge line 26. The switching valve 27 is connected to the control unit 30 and switches between opening and closing based on a control signal from the control unit 30. When the switching valve 27 is closed, the heat transfer medium W in the heat exchange chamber 20 is held in the heat exchange chamber 20. When the switching valve 27 is opened, the heat transfer medium W in the heat exchange chamber 20 is discharged.

The control unit 30 is a device that can control the entire boiler system 100. The control unit 30 includes an ECU (electric / electronic control unit), a memory, and the like. The control unit 30 has a function of controlling the removal unit 24 to remove the heat transfer medium W from the surroundings of the heat exchanger 22 at least during an emergency stop in which the flow of fluid in the heat exchanger 22 is reduced or stopped. The functional module that performs the removal control process of the control unit 30 constitutes a part of the “removal unit” in the claims. That is, it can be said that the removing unit 24 includes the control unit 30 (part of the functional modules). Here, the emergency stop is a state in which the flow of the fluid in the heat exchanger 22 is reduced or stopped as compared with the normal operation by stopping the entire system or a part thereof for a predetermined cause. For example, the cause of the emergency stop may be a failure or abnormality of a component in the boiler system 100, or an all-in-house stop. In addition, all the station stops are the states which lost all the power supplies in a power plant. At the time of emergency stop, the circulation of the heat transfer medium W in the circulation system 21 may be stopped. Since power is not supplied to the control unit 30 during a power failure, the control unit 30 may be moved with an emergency battery or the like. Alternatively, the switching valve 27 may be a valve that automatically opens when power supply is lost.

In addition, when the controller 30 detects the flow state of the steam to the reheater 34 and detects a decrease or stop of the flow of the steam to the reheater 34, the control unit 30 starts the heat transfer medium from around the reheater 34. Control to remove. Specifically, the control unit 30 can detect the flow state of the steam in the reheater 34 by installing a sensor or the like at the position of the turbine 50 and the steam supply unit 37 and monitoring the flow rate of the steam. .

The control unit 30 can switch between opening and closing of the valve 54 by transmitting a control signal to the valve 54 of the steam supply unit 37. Here, when the boiler is started, the steam may not be high enough to rotate the turbine 50. In this case, in order to prevent the reheater 34 from being aired, the control unit 30 controls the steam supply unit 37 when starting the boiler, thereby bypassing the turbine 50 and supplying steam to the reheater 34. Can do.

Next, operations and effects of the boiler system 100 according to the present embodiment will be described.

First, as a boiler system according to a comparative example, a boiler system that does not have a removal unit is examined. In such a boiler system, the fluid does not flow to the heat exchanger embedded in the heat transfer medium W during an emergency stop. In this case, since the cooling function by the fluid cannot be obtained, there is a possibility that the tube of the heat exchanger is damaged due to the heat of the heat transfer medium W. In order to prevent damage to the heat exchanger tube, it is necessary to select a material having a high operating temperature as the material of the tube.

The boiler system 100 according to the present embodiment includes a heat exchanger 22 through which a fluid that exchanges heat with a heat transfer medium flows. The heat exchanger 22 is buried in the heat transfer medium W heated in the furnace 3. The boiler system 100 also includes a removal unit 24 that removes the heat transfer medium from the periphery of the heat exchanger 22 at least during an emergency stop in which the flow of fluid in the heat exchanger 22 decreases or stops. Therefore, even if the flow of fluid in the heat exchanger 22 decreases or stops during an emergency stop, the heat transfer medium W is removed from the surroundings of the heat exchanger 22, so the heat exchanger 22 is heated by the heat of the heat transfer medium W. It is possible to suppress the temperature of the tube from becoming too high. As described above, it is possible to appropriately protect the heat exchanger 22 buried in the heat transfer medium W during an emergency stop.

The boiler system 100 according to the present embodiment further includes a turbine 50 that rotates with steam generated by combustion in a furnace, and the heat exchanger 22 is a reheater 34 that superheats steam discharged from the turbine 50 as a fluid. It may be. With this configuration, the reheater 34 buried in the heat transfer medium W at the time of an emergency stop can be appropriately protected.

The boiler system 100 according to the present embodiment includes at least the furnace 3 and includes a circulation system 21 that circulates the heat transfer medium W, and the removal unit 24 discharges the heat transfer medium W out of the circulation system. The heat transfer medium W may be removed from the periphery of the heat exchanger 22. With this configuration, the heat exchanger 22 can be protected with a simple configuration in which the heat transfer medium W is simply discharged out of the circulation system 21 during an emergency stop.

In the boiler system 100 according to the present implementation site, the removal unit 24 includes a control unit 30 that controls the boiler system 100, and the control unit 30 detects the flow state of the steam to the reheater 34 and performs reheating. When the decrease or stop of the steam flow to the heater is detected, control for removing the heat transfer medium W from the periphery of the reheater 34 may be performed. With this configuration, it is possible to remove the heat transfer medium from the periphery of the reheater 34 after confirming that steam does not actually flow through the reheater 34. Thereby, the reheater can be protected at an appropriate timing.

The present invention is not limited to the above embodiment.

For example, the configuration for removing the heat transfer medium W from the heat exchange chamber 20 is not limited. For example, although the above-described removing unit 24 moves the heat transfer medium W by weight, the heat transfer medium W may be moved using a device such as a blower. Or as shown in FIG. 4, the removal part 73 provided with the connection pipe 71 which connected the heat exchange chamber 20 and the furnace 3, and the switching valve 72 provided in the connection pipe 71 may be employ | adopted. The removing unit 73 can directly supply the heat transfer medium W in the heat exchange chamber 20 to the furnace 3. The connection part between the heat exchange chamber 20 and the connection pipe 71 is located higher than the connection part between the furnace 3 and the connection pipe 71 so that the heat transfer medium W can move by gravity. Or the removal part 84 provided with the connection pipe 81, the switching valve 82, and the conveyance means 83 may be employ | adopted. The conveying means 83 may be configured by a screw conveyor or the like. The transport means 83 may transport the heat transfer medium W supplied from the connection pipe 81 to a cooler or the like. Thereby, the heat transfer medium W can be cooled. In addition, the conveyance means and the cooler may be moved by electric power such as an emergency battery in the event of a power failure.

Further, although the reheater is illustrated as the heat exchanger 22 buried in the heat transfer medium W, any heat exchanger in the boiler system may be buried in the heat transfer medium W to provide a removal unit. For example, the inner pipe existing in the furnace 3 may be buried in the heat transfer medium W as the heat exchanger 22. Further, a part of the superheater arranged on the upstream side of the turbine may be embedded in the heat transfer medium W as the heat exchanger 22. Further, an evaporation pipe that generates steam by the heat of the furnace 3 may be buried in the heat transfer medium W as the heat exchanger 22.

3 ... Furnace, 21 ... Circulation system, 22 ... Heat exchanger, 24 ... Removal part, 30 ... Control part, 34 ... Reheater, 50 ... Turbine, 100 ... Boiler system.

Claims

A furnace that heats the heat transfer medium by burning fuel;
A heat exchanger that is buried in a heat transfer medium heated in the furnace and in which a fluid that exchanges heat with the heat transfer medium flows;
A boiler system comprising: a removal unit that removes the heat transfer medium from the periphery of the heat exchanger at an emergency stop in which the flow of the fluid in the heat exchanger is reduced or stopped.
A turbine that rotates with steam generated by the combustion of the furnace;
The boiler system according to claim 1, wherein the heat exchanger is a reheater that superheats steam discharged from the turbine as the fluid.
Including at least the furnace, comprising a circulation system for circulating the heat transfer medium,
The boiler system according to claim 1 or 2, wherein the removing unit removes the heat transfer medium from the periphery of the heat exchanger by discharging the heat transfer medium out of the circulation system.
The removal unit has a control unit for controlling the boiler system,
The controller detects the flow state of the steam to the reheater, and when detecting a decrease or stop of the flow of the steam to the reheater, the heat transfer from the periphery of the reheater. The boiler system of Claim 2 which performs control which removes a medium.