A circulating fluidized bed boiler dense phase zone heat load regulation system

Abstract

The application discloses a circulating fluidized bed boiler dense phase area heat load adjusting system, which comprises a furnace body, a high-pressure fluidizing fan, a heat storage tank and a heat load adjusting device; the heat load adjusting device comprises a wind distribution plate, a double working medium air cap, a dense phase area buried pipe and a side wall heat exchange pipe; the wind distribution plate is connected with the high-pressure fluidizing fan; the double working medium air cap is provided with a wind medium channel and a water medium channel, the air inlet of the wind medium channel is communicated with a sandwich cavity; the water inlet and outlet of the water medium channel are connected with the heat storage tank through a first circulating water circuit; the water inlets and outlets of the dense phase area buried pipe are respectively connected on the front and back side walls of the furnace body and connected with the heat storage tank through a second circulating water circuit; a plurality of side wall heat exchange pipes are arranged on the left and right side walls of the furnace body and are uniformly and spacedly arranged along the front and back directions, and the water inlets and outlets of the side wall heat exchange pipes are connected with the heat storage tank through a third circulating water circuit. The application can realize the adjusting function of the dense phase area heat load and effectively improve the heat load change rate of the circulating fluidized bed boiler dense phase area.

Description

Technical Field

[0001] This invention belongs to the field of circulating fluidized bed boiler combustion technology, specifically relating to a heat load regulation system for the dense phase zone of a circulating fluidized bed boiler. Background Technology

[0002] Circulating fluidized bed boilers are a clean coal power generation technology that suspends a large number of solid particles in flowing air for combustion. They have the characteristics of low combustion pollutant generation, wide fuel adaptability, and high heat and mass transfer coefficients. They have a significant advantage, especially in the combustion of low-calorific-value and difficult-to-burn solid fuels, and have received widespread attention and application.

[0003] During combustion in a circulating fluidized bed boiler, a dense phase zone with high particle density, high particle concentration, and large average particle size is formed in the lower part of the combustion chamber. This zone is filled with hot material and serves as a stable ignition heat source. Due to particle abrasion and other factors, no heating surfaces are arranged in this zone, resulting in strong thermal inertia and slow changes in heat load.

[0004] However, during startup and load changes in circulating fluidized bed boilers, the strong thermal inertia of the dense phase region results in a slow heat load response, making it difficult to meet the requirements of operational flexibility and deep peak shaving for thermal power units. Therefore, how to effectively improve the rate of heat load change in the dense phase region of circulating fluidized bed boilers is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a circulating fluidized bed boiler dense phase zone heat load regulation system that can both realize the function of regulating the heat load in the dense phase zone and effectively improve the rate of change of heat load in the dense phase zone of the circulating fluidized bed boiler.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A heat load regulation system for the dense phase zone of a circulating fluidized bed boiler includes a boiler body, a high-pressure fluidizing blower, a heat storage tank, and a heat load regulation device. The heat load regulation device is arranged within the dense phase zone of the boiler body and includes an air distribution plate, dual-working-fluid air caps, dense phase zone embedded pipes, and sidewall heat exchange tubes. The air distribution plate has a sandwich cavity connected to the high-pressure fluidizing blower. Multiple dual-working-fluid air caps are arranged in a matrix on the air distribution plate. Each dual-working-fluid air cap has an air medium channel for fluidizing air and a water medium channel for working fluid water. The air medium channel inlet communicates with the sandwich cavity, and the air medium channel outlet is provided with… The dual-working-fluid air cap is placed on the bottom surface of the cap head; the inlet and outlet of the water medium channel are connected to the heat storage tank through the first circulating water channel; the dense phase zone buried pipes are evenly spaced on the air distribution plate, and a row of dual-working-fluid air caps are arranged between two adjacent dense phase zone buried pipes; the inlet and outlet of the dense phase zone buried pipes are respectively connected to the front and rear side walls of the furnace body and connected to the heat storage tank through the second circulating water channel; multiple side wall heat exchange pipes are evenly spaced along the front and rear direction on the left and right side walls of the furnace body, and the inlet and outlet of the side wall heat exchange pipes are connected to the heat storage tank through the third circulating water channel; water pumps are provided on the first, second, and third circulating water channels.

[0008] As a preferred embodiment of the present invention, the straight pipe section of the dual-working-medium wind cap has a double-layer structure, with the inner layer being the air medium channel and the outer layer being the water medium channel.

[0009] As a preferred embodiment of the present invention, the air outlet of the air medium channel is located on the bottom surface of the cap of the dual-working-medium air cap; the height of the straight pipe section of the dual-working-medium air cap is equal to the diameter of the buried pipe in the dense phase zone.

[0010] As a preferred embodiment of the present invention, the interior of the heat storage tank is provided with a heat storage unit capable of exchanging heat with the working fluid water flowing through the heat storage tank.

[0011] As a preferred embodiment of the present invention, the air distribution plate is provided with a plurality of anti-wear air vents evenly spaced along the front-back direction on the left and right sides, and the anti-wear air vents are connected to the interlayer cavity.

[0012] As a preferred embodiment of the present invention, the anti-wear air outlet is close to the side wall heat exchange tube and is arranged in a one-to-one correspondence with the side wall heat exchange tube.

[0013] As a preferred embodiment of the present invention, the sidewall heat exchange tube is vertically arranged and partially embedded in the sidewall of the furnace body.

[0014] As a preferred embodiment of the present invention, the height of the sidewall heat exchange tube is equal to the height of the vertical wall surface of the dense phase region of the furnace body.

[0015] As a preferred embodiment of the present invention, the air pressure and velocity of the high-pressure fluidizing blower are higher than the fluidizing air pressure and velocity in the dense phase region.

[0016] As a preferred embodiment of the present invention, the circulating fluidized bed boiler dense phase zone heat load regulation system further includes a three-way electric valve, an economizer, a water-cooled wall, a steam-water separator, and a superheater. The inlet of the economizer is connected to the working fluid feedwater end of the system. The outlet of the economizer is divided into a main path and a bypass path through the three-way electric valve. The main path is where the working fluid water from the economizer flows through the dual working fluid wind cap, dense phase zone buried pipe, and side wall heat exchange tube in the heat load regulation device, and is then sequentially sent to the water-cooled wall, steam-water separator, and superheater. The resulting high-temperature steam is then sent to the steam turbine. The bypass path is where the working fluid water from the economizer is sequentially sent to the water-cooled wall, steam-water separator, and superheater. The resulting high-temperature steam is then sent to the steam turbine.

[0017] The heat load regulation system for the dense phase zone of a circulating fluidized bed boiler provided by this invention has the following advantages compared with the prior art:

[0018] This invention addresses the issue of heat transfer surfaces in the dense phase zone of a circulating fluidized bed boiler. These surfaces, including dual-working-fluid air caps, dense-phase zone embedded tubes, and sidewall heat exchange tubes, form a circulating loop with a heat storage tank. This allows the working fluid water in these components to exchange heat with the heat storage unit as it flows through the heat storage tank, thus regulating the heat load in the dense phase zone. Specifically, when the heat load in the boiler's dense phase zone is high and needs to be reduced, or when the boiler is shut down, the working fluid water in these components carries away the heat from the dense phase zone, reducing the temperature in the boiler's dense phase zone. When the temperature of the working fluid is low, the temperature of the working fluid rises. When the high-temperature working fluid flows through the heat storage tank, the heat of the working fluid is transferred to the heat storage unit for storage, so that the heat in the dense phase zone is finally accumulated in the heat storage tank. When the heat load in the dense phase zone of the boiler is low and needs to be increased, or when the boiler is started, the heat accumulated in the heat storage unit is transferred to the lower-temperature water, forming high-temperature and high-pressure working fluid. This high-temperature and high-pressure working fluid is then transported to the three heating surfaces in the dense phase zone of the boiler: the double working fluid wind cap, the dense phase zone buried pipe, and the side wall heat exchange pipe. The high-temperature and high-pressure water transfers heat to the dense phase zone, thereby increasing the heat load in the dense phase zone.

[0019] Furthermore, a water pump is installed between the heating surface in the dense phase zone and the heat storage tank. By adjusting the flow rate and velocity of the working fluid through the water pump, the rate of change of heat load in the dense phase zone can be increased.

[0020] It should also be noted that when the heat load in the dense phase region increases, the heat stored in the heat storage tank is released in the heating surface of the dense phase region through the working fluid water. Compared with the common operation mode of increasing the amount of fuel, this saves fuel and also achieves the purpose of heat recovery when the heat load is high, thus improving energy utilization efficiency. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0022] Figure 1 This is a schematic diagram of the structure of the heat load regulation system in the dense phase zone of a circulating fluidized bed boiler provided in an embodiment of the present invention.

[0023] Figure 2 This is a front view of the heat load regulating device in an embodiment of the present invention;

[0024] Figure 3 This is a top view of the heat load regulating device in an embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of the structure of the dual-working-fluid wind cap in an embodiment of the present invention;

[0026] Figure 5 This is a system connection diagram when the present invention is applied to a hydroelectric generator unit.

[0027] Marked in the image:

[0028] 1. Furnace body; 2. High-pressure fluidizing blower; 3. Heat storage tank; 4. Heat load regulating device; 41. Air distribution plate; 411. Anti-wear air outlet; 42. Dual-working-fluid air cap; 421. Air medium channel; 422. Water medium channel; 43. Dense phase zone buried pipe; 44. Side wall heat exchange tube; 5. Water pump; 6. Three-way electric valve; 7. Economizer; 8. Water-cooled wall; 9. Steam-water separator; 10. Superheater. Detailed Implementation

[0029] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0030] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0031] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0032] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0033] Please refer to the following: Figures 1 to 5 The circulating fluidized bed boiler dense phase zone heat load regulation system provided in the embodiments of the present invention will now be described.

[0034] like Figures 1 to 4 As shown in the preferred embodiment of the present invention, a heat load regulation system for the dense phase zone of a circulating fluidized bed boiler includes a boiler body 1, a high-pressure fluidizing blower 2, a heat storage tank 3, and a heat load regulation device 4. The heat load regulation device 4 is arranged in the dense phase zone of the boiler body 1 and includes an air distribution plate 41, dual-working-fluid air caps 42, a dense phase zone buried pipe 43, and a side wall heat exchange pipe 44. The air distribution plate 41 has a sandwich cavity, which is connected to the high-pressure fluidizing blower 2. Multiple dual-working-fluid air caps 42 are arranged in a matrix on the air distribution plate 41. Each dual-working-fluid air cap 42 has an air medium channel 421 for fluidizing air to pass through and a water medium channel 422 for working-fluid water to pass through. The air inlet of the air medium channel 421 is connected to the sandwich cavity 44. The cavity is connected; the inlet and outlet of the water medium channel 422 are connected to the heat storage tank 3 through the first circulating water path; the dense phase zone buried pipes 43 are evenly spaced on the air distribution plate 41, and a row of dual working fluid air caps 42 are arranged between two adjacent dense phase zone buried pipes 43 to ensure the uniformity of the heat load in the dense phase zone; the inlet and outlet of the dense phase zone buried pipes 43 are respectively connected to the front and rear side walls of the furnace body 1 and connected to the heat storage tank 3 through the second circulating water path; multiple side wall heat exchange pipes 44 are evenly spaced along the front and rear direction on the left and right side walls of the furnace body 1, and the inlet and outlet of the side wall heat exchange pipes 44 are connected to the heat storage tank 3 through the third circulating water path; water pumps 5 are provided on the first, second, and third circulating water paths.

[0035] According to an embodiment of the circulating fluidized bed boiler dense phase zone heat load regulation system, by arranging dual-working-fluid air caps 42, dense phase zone buried pipes 43, and side wall heat exchange pipes 44 in the dense phase zone of the circulating fluidized bed boiler, and forming a circulation loop with the heat storage tank 3, the working fluid water in the dual-working-fluid air caps 42, dense phase zone buried pipes 43, and side wall heat exchange pipes 44 exchanges heat with the heat storage unit when flowing through the heat storage tank 3, thereby realizing the function of regulating the heat load in the dense phase zone; that is, when the heat load in the dense phase zone of the boiler is high and needs to be reduced or when the boiler is shut down, the working fluid water in the dual-working-fluid air caps 42, dense phase zone buried pipes 43, and side wall heat exchange pipes 44... The heat from the dense phase zone is carried out, the temperature of the boiler's dense phase zone decreases, and the temperature of the working fluid water increases. When the high-temperature working fluid water flows through the heat storage tank 3, the heat of the working fluid water is transferred to the heat storage unit for storage, so that the heat of the dense phase zone is finally accumulated in the heat storage tank 3. When the heat load of the boiler's dense phase zone is low and needs to be increased, or when the boiler is started, the heat accumulated in the heat storage unit is transferred to the lower-temperature water, forming high-temperature and high-pressure working fluid water, which is transported to the three heating surfaces in the boiler's dense phase zone: the double working fluid wind cap 42, the dense phase zone buried pipe 43, and the side wall heat exchange pipe 44. The high-temperature and high-pressure water transfers heat to the dense phase zone, thereby increasing the heat load of the dense phase zone.

[0036] Furthermore, a water pump 5 is installed between the heating surface of the dense phase zone and the heat storage tank 3. By adjusting the flow rate and velocity of the working fluid water through the water pump 5, the rate of change of heat load in the dense phase zone can be improved.

[0037] It should also be noted that when the heat load in the dense phase region increases, the heat stored in the heat storage tank 3 is released in the heating surface of the dense phase region through the working fluid water. Compared with the common operation mode of increasing the amount of fuel, this saves fuel and also achieves the purpose of heat recovery when the heat load is high, thus improving energy utilization efficiency.

[0038] For example, such as Figure 4 As shown, in order to ensure the heat exchange efficiency between the air medium channel 421 and the water medium channel 422 in the dual-working-medium air cap 42, the straight pipe section of the dual-working-medium air cap 42 has a double-layer structure, with the inner layer being the air medium channel 421 and the outer layer being the water medium channel 422.

[0039] For example, such as Figure 2 As shown, the air outlet of the air medium channel 421 is located on the bottom surface of the cap of the dual-working-fluid air cap 42 to avoid the air outlet being blocked by particles in the dense phase zone. Furthermore, the height of the straight pipe section of the dual-working-fluid air cap 42 is equal to the diameter of the dense phase zone buried pipe 43, so that the fluidizing air can be blown towards itself and the dense phase zone buried pipe 43, thinning the dense phase zone particles around the dense phase zone buried pipe 43, reducing the wear of the buried pipe by the dense phase zone solid particles, and playing a certain protective role for the dense phase zone buried pipe 43, avoiding the problem of wear and bursting of the dense phase zone buried pipe 43.

[0040] For example, the heat storage tank 3 is equipped with a heat storage unit inside, which can exchange heat with the working fluid water flowing through the heat storage tank 3. In this embodiment, the heat storage tank 3 is a water tank with an insulation layer. If necessary, a heater can also be added inside the water tank to adapt to the low heat load in the dense phase zone of the boiler under low temperature conditions or when the boiler is started up; the heat storage unit is preferably a heat exchange coil.

[0041] For example, such as Figure 2 and Figure 3 As shown, the air distribution plate 41 has multiple anti-wear air inlets 411 evenly spaced along the front-back direction on its left and right sides, and the anti-wear air inlets 411 are connected to the interlayer cavity. In this embodiment, when the boiler is running, the high-pressure fluidizing fan 2 is turned on, and the fluidizing air coming out of the anti-wear air inlets 411 can form an air wall on one side of the sidewall heat exchange tube 44, separating the dense phase zone bed material from the sidewall heat exchange tube 44, effectively preventing severe wear on the sidewall heat exchange tube 44 during particle fluidization in the dense phase zone. Furthermore, in order to ensure the blocking ability of the air wall, the anti-wear air inlets 411 are close to the sidewall heat exchange tube 44 and are arranged in a one-to-one correspondence with the sidewall heat exchange tube 44; and the height of the sidewall heat exchange tube 44 is equal to the height of the vertical wall of the dense phase zone of the furnace body 1.

[0042] For example, such as Figure 2 and Figure 3 As shown, the sidewall heat exchange tube 44 is vertically arranged and partially embedded in the sidewall of the furnace body 1. This design reduces the exposed area of ​​the sidewall heat exchange tube 44, mitigating the risk of wear and tube rupture.

[0043] For example, in order to further reduce the wear on the heat-receiving surfaces of the dense phase zone, such as the dual-working-fluid wind cap 42, the dense phase zone buried pipe 43, and the side wall heat exchange pipe 44, during particle fluidization in the dense phase zone, the air pressure and velocity of the high-pressure fluidizing fan 2 are higher than the fluidizing air pressure and velocity in the dense phase zone.

[0044] For example, such as Figure 5As shown, when the circulating fluidized bed boiler dense phase zone heat load regulation system is applied to a thermal power unit, the circulating fluidized bed boiler dense phase zone heat load regulation system further includes a three-way electric valve 6, an economizer 7, a water-cooled wall 8, a steam-water separator 9, and a superheater 10. The inlet of the economizer 7 is connected to the working fluid water supply end of the system. The outlet of the economizer 7 is divided into a main path and a bypass path through the three-way electric valve 6. The main path is where the working fluid water from the economizer 7 flows through the dual working fluid wind cap 42, the dense phase zone buried pipe 43, and the side wall heat exchange pipe 44 in the heat load regulation device 4, and is then sequentially sent to the water-cooled wall 8, the steam-water separator 9, and the superheater 10. Finally, the obtained high-temperature steam is sent to the steam turbine. The bypass path is where the working fluid water from the economizer 7 is sequentially sent to the water-cooled wall 8, the steam-water separator 9, and the superheater 10. Finally, the obtained high-temperature steam is sent to the steam turbine.

[0045] When the thermal power unit is working, it can switch to main line operation through a three-way electric valve. The working water from the system working water feedwater end is heated by the economizer 7 and flows through the three dense phase heat exchange surfaces of the double working fluid wind cap 42, dense phase zone buried pipe 43 and side wall heat exchange tube 44. At this time, it is easier to quickly adjust the unit load through the heat storage tank 3, so that the temperature of the dense phase zone increases, heats the feedwater, improves the feedwater temperature parameters, and sends it to the water-cooled wall 8, steam-water separator 9, superheater 10 and other heat exchange surfaces with higher working temperatures. Finally, the high-temperature steam obtained is sent to the steam turbine, thereby improving the peak-shaving capacity of the thermal power unit.

[0046] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A system for regulating the heat load in the dense phase zone of a circulating fluidized bed boiler, characterized in that The application relates to a high-pressure fluidized bed boiler, which comprises a furnace body, a high-pressure fluidizing fan, a heat storage tank and a heat load regulating device; the heat load regulating device is arranged in a dense phase zone of the furnace body, and comprises a wind distribution plate, double-working-medium air caps, dense phase zone buried pipes and side wall heat exchange pipes; the wind distribution plate is provided with a sandwich cavity, the sandwich cavity is connected with the high-pressure fluidizing fan; the double-working-medium air caps are arranged in a matrix on the wind distribution plate, the double-working-medium air caps are provided with air medium channels for allowing fluidizing air to pass through and water medium channels for allowing working water to pass through, the air medium channels are communicated with the sandwich cavity, the water medium channels are connected with the heat storage tank through a first circulating water circuit, the dense phase zone buried pipes are uniformly and intervally laid on the wind distribution plate, a row of the double-working-medium air caps is arranged between two adjacent dense phase zone buried pipes, the water inlets and outlets of the dense phase zone buried pipes are connected with front and back side walls of the furnace body and connected with the heat storage tank through a second circulating water circuit, a plurality of side wall heat exchange pipes are arranged on left and right side walls of the furnace body and uniformly and intervally arranged along the front and back directions, the water inlets and outlets of the side wall heat exchange pipes are connected with the heat storage tank through a third circulating water circuit, and water pumps are arranged on the first, second and third circulating water circuits.

2. The dense zone heat flux regulating system for a circulating fluidized bed boiler of claim 1, wherein, The straight pipe section of the double-working-medium air cap is a double-layer structure, the inner layer is the air medium channel, and the outer layer is the water medium channel.

3. The dense bed zone heat flux regulating system for a circulating fluidized bed boiler of claim 1, wherein, The air outlets of the air medium channels are arranged on the bottom surface of the cap head of the double-working-medium air cap.

4. The dense bed zone heat flux regulating system for a circulating fluidized bed boiler of claim 1, wherein, The height of the straight pipe section of the double-working-medium air cap is equal to the diameter of the dense phase zone buried pipe.

5. The dense bed zone heat flux regulating system for a circulating fluidized bed boiler of claim 1, wherein, The heat storage tank is internally provided with a heat storage unit capable of exchanging heat with working water flowing through the heat storage tank.

6. The dense bed zone heat flux regulating system for a circulating fluidized bed boiler of claim 5, wherein, The left and right sides of the wind distribution plate are respectively provided with a plurality of anti-abrasion air inlets which are uniformly and intervally arranged along the front and back directions, and the anti-abrasion air inlets are communicated with the sandwich cavity.

7. The dense bed zone heat flux regulating system for a circulating fluidized bed boiler of claim 6, wherein, The anti-abrasion air inlets are arranged close to and correspond to the side wall heat exchange pipes.

8. The dense bed zone heat flux regulating system for a circulating fluidized bed boiler of claim 7, wherein, The side wall heat exchange pipes are vertically arranged and partially embedded in the side wall of the furnace body.

9. The dense bed zone heat flux regulating system for a circulating fluidized bed boiler of claim 1, wherein, The height of the side wall heat exchange pipe is equal to the height of the vertical wall surface of the dense phase zone of the furnace body.

10. The dense bed zone heat flux regulating system of any one of claims 1 to 9, wherein, The air pressure and air speed of the high-pressure fluidizing fan are higher than the fluidizing air pressure and air speed in the dense phase zone. The application further comprises a three-way electric valve, an economizer, a water cooling wall, a steam-water separator and a superheater, the water inlet of the economizer is connected with a working water supply end of a system, the water outlet of the economizer is divided into a main path and a bypass path through the three-way electric valve, the working water from the economizer passes through the double-working-medium air caps, the dense phase zone buried pipes and the side wall heat exchange pipes in the heat load regulating device in sequence in the main path, and is sequentially sent to the water cooling wall, the steam-water separator and the superheater, and finally high-temperature steam obtained is sent to a steam turbine, the working water from the economizer is sequentially sent to the water cooling wall, the steam-water separator and the superheater in the bypass path, and finally high-temperature steam obtained is sent to the steam turbine.

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