Circulating fluidized bed boiler with process heat storage and variable load regulation method thereof

Abstract

The application discloses a circulating fluidized bed boiler with process heat storage and a variable load adjusting method thereof. The circulating fluidized bed boiler with process heat storage comprises a furnace and at least one set of external circulation units. The furnace is used for burning fuel and oxidants to obtain external circulation materials and internal circulation materials. An upper portion of the furnace is provided with a gas-solid product outlet. The external circulation materials are discharged through the gas-solid product outlet. The internal circulation materials are circulated in a dense phase zone at the bottom of the furnace. Each set of external circulation units comprises a separation and return device and a heat storage chamber. The separation and return device is connected with the gas-solid product outlet and is used for separating the gas-solid product to obtain the external circulation materials. The heat storage chamber is connected with the separation and return device and the dense phase zone at the bottom of the furnace. In the load reduction adjusting stage, the heat storage chamber is used for receiving and storing part of the external circulation materials from the separation and return device and part of the internal circulation materials from the dense phase zone.

Description

Technical Field

[0001] This invention belongs to the field of circulating fluidized bed technology, specifically relating to a circulating fluidized bed boiler with process heat storage and its variable load regulation method. Background Technology

[0002] Circulating fluidized bed (CFB) generator units are an important component of coal-fired power generation units. They are characterized by strong fuel adaptability and low initial emissions of gaseous pollutants, making them a widely used clean coal combustion technology. Under the dual-carbon goals, the large-scale grid integration of renewable energy necessitates ensuring the stability and security of the power grid, placing a greater burden on coal-fired power units for peak shaving. Renewable energy generation is characterized by intermittency, volatility, and randomness. To meet the demands of large-scale renewable energy grid integration, new requirements are placed on the rapid load response capabilities of coal-fired power units.

[0003] Circulating fluidized bed boilers have a huge amount of circulating ash and high thermal inertia. In addition, in order to prevent wear, circulating fluidized bed boilers use a large amount of anti-wear refractory material, which further increases the boiler's thermal inertia. Using conventional adjustment methods, it is difficult to achieve rapid load adjustment, making it difficult to meet the requirements for large-scale consumption of renewable energy. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] In view of this, the present invention provides a circulating fluidized bed boiler with process thermal storage and a method for adjusting the variable load thereon, so as to at least partially solve the above-mentioned technical problems.

[0006] One aspect of the present invention provides a circulating fluidized bed boiler with process thermal storage, comprising a furnace and at least one set of external circulation units.

[0007] The furnace is used to obtain external and internal circulating materials after the fuel and oxidant are burned in the furnace. The upper part of the furnace is provided with a gas-solid product outlet. The external circulating material is discharged through the gas-solid product outlet, and the internal circulating material circulates in the dense phase zone at the bottom of the furnace.

[0008] Each external circulation unit includes a separation and return device and a heat storage chamber. The separation and return device is connected to the gas-solid product outlet and is used to separate the gas-solid products to obtain external circulation material. The heat storage chamber is connected to both the separation and return device and the dense phase zone at the bottom of the furnace. The heat storage chamber is used to receive and store part of the external circulation material from the separation and return device and part of the internal circulation material from the dense phase zone during the load reduction adjustment phase.

[0009] According to an embodiment of the present invention, wherein:

[0010] The heat storage chamber is also used to return the heat storage material in the heat storage chamber to the dense phase zone at the bottom of the furnace in stages during the load adjustment phase. The heat storage material includes part of the external circulation material from the separation and return device and part of the internal circulation material from the dense phase zone.

[0011] According to an embodiment of the present invention, wherein:

[0012] The heat storage chamber is connected to the dense phase zone at the bottom of the furnace through a first one-way channel and a second one-way channel, wherein the first one-way channel runs from the dense phase zone to the heat storage chamber, and the second one-way channel runs from the heat storage chamber to the dense phase zone.

[0013] According to an embodiment of the present invention, wherein:

[0014] The upper middle part of the dense phase zone is provided with a first outlet, and the upper middle part of the thermal storage chamber is provided with a first inlet. The first outlet and the first inlet are connected by a first one-way channel, and the first outlet is higher than the first inlet.

[0015] The lower middle part of the dense phase zone is provided with a second inlet, and the lower middle part of the thermal storage chamber is provided with a second outlet. The second inlet and the second outlet are connected by a second one-way channel, and the second outlet is higher than the second inlet.

[0016] According to an embodiment of the present invention, wherein:

[0017] A ash control valve is installed in the first one-way channel;

[0018] A ventilation system is installed at the bottom of the heat storage chamber.

[0019] According to an embodiment of the present invention, wherein:

[0020] The thermal storage chamber is located outside the dense phase zone, and the thermal storage chamber and the dense phase zone share a partition wall. The partition wall includes a conical section and a straight section. The first one-way channel is located in the conical section, and the second one-way channel is located in the straight section. The first one-way channel is higher than the second one-way channel.

[0021] A ventilation system is installed at the bottom of the heat storage chamber.

[0022] According to an embodiment of the present invention, wherein:

[0023] The separation and return device is connected to the heat storage chamber through a third one-way channel, which leads from the separation and return device to the heat storage chamber.

[0024] According to an embodiment of the present invention, wherein:

[0025] The separation and return device includes a separator, a return feeder, and a return riser;

[0026] The return feeder includes a return inlet and a storage outlet;

[0027] A third inlet is located in the upper part of the heat storage chamber;

[0028] The bottom outlet of the return riser is connected to the return inlet;

[0029] The storage outlet and the third inlet are connected by a third one-way passage.

[0030] According to an embodiment of the present invention, wherein:

[0031] The return feeder also includes a return outlet;

[0032] The return material outlet is connected to the dense phase zone of the furnace, or the return material outlet is connected to the heat storage chamber.

[0033] According to an embodiment of the present invention, wherein:

[0034] The separation and return device includes a separator, a return feeder, and a return riser;

[0035] The return feeder includes a return inlet;

[0036] A third inlet is located in the upper part of the heat storage chamber;

[0037] The bottom outlet of the return riser is connected to the return inlet;

[0038] The lower middle part of the return material riser is provided with a side material outlet. The side material outlet and the third inlet are connected through a third one-way channel. A side air duct is provided at the side material outlet.

[0039] According to an embodiment of the present invention, wherein:

[0040] The furnace is also equipped with a fuel inlet, which is used to introduce fuel into the furnace;

[0041] The circulating fluidized bed boiler with process thermal storage also includes a preheating unit, which is connected to the fuel inlet of the furnace, or the preheating unit is connected to the dense phase zone of the furnace. The preheating unit is used to preheat the fuel and then introduce it into the furnace through the fuel inlet.

[0042] According to an embodiment of the present invention, wherein:

[0043] The outer wall of the heat storage chamber is made of thermal insulation material.

[0044] Another aspect of the present invention provides a method for rapid load change regulation of a circulating fluidized bed boiler with process thermal storage. This method is a method for achieving rapid load change regulation and includes:

[0045] Fuel and oxidant are introduced into the furnace so that the fuel and oxidant are burned in the furnace to obtain external and internal circulating materials. The upper part of the furnace is provided with a gas-solid product outlet. The external circulating material is discharged through the gas-solid product outlet, and the internal circulating material circulates in the dense phase zone at the bottom of the furnace.

[0046] The external circulating material is fed into the separation and return device so that the gas-solid products can be separated by the separation and return device to obtain the external circulating material.

[0047] During the load reduction adjustment phase, a portion of the external circulating material originating from the separation and return device and a portion of the internal circulating material originating from the dense phase zone are introduced into the heat storage chamber to reduce the boiler's heat load. The heat storage chamber is connected to both the separation and return device and the dense phase zone at the bottom of the furnace.

[0048] According to an embodiment of the present invention, wherein:

[0049] The load reduction adjustment stage includes a first load reduction stage and a second load reduction stage. The first load reduction stage is the stage in which the boiler reduces from full load to a first predetermined load, and the second load reduction stage is the stage in which the boiler reduces from the first predetermined load to a second predetermined load.

[0050] During the load reduction adjustment phase, a portion of the external circulating material originating from the separation and return device and a portion of the internal circulating material originating from the dense phase zone are introduced into the heat storage chamber, including:

[0051] In the first load reduction phase, a portion of the external circulating material originating from the separation and return device is introduced into the heat storage chamber so that the boiler is reduced from full load to the first predetermined load.

[0052] In the second load reduction stage, a portion of the internal circulating material originating from the dense phase zone is introduced into the heat storage chamber, so that the boiler is reduced from the first predetermined load to the second predetermined load.

[0053] According to an embodiment of the present invention, it further includes:

[0054] During the load increase adjustment phase, the heat storage material in the heat storage chamber is returned to the dense phase zone at the bottom of the furnace in stages to increase the boiler heat load. The heat storage material includes part of the external circulation material from the separation and return device and part of the internal circulation material from the dense phase zone.

[0055] According to an embodiment of the present invention, it further includes:

[0056] During boiler startup, the fuel is preheated through a preheating unit before being introduced into the furnace.

[0057] According to embodiments of the present invention, due to the large thermal inertia of the boiler, it is difficult to achieve rapid load adjustment using conventional adjustment methods. The embodiments of this disclosure, by setting up a heat storage chamber connected to both the separation and return material device and the dense phase zone at the bottom of the furnace, allow the heat storage chamber to receive and store not only external circulating materials but, more importantly, internal circulating materials during the load reduction adjustment phase. In situations requiring rapid load reduction and deep peak shaving (e.g., reducing the boiler heat load to 20% or below), the concentration of circulating materials within the boiler can be rapidly changed within a wide load range of 20%-100% by altering the external and internal circulating ash amounts in the circulating fluidized bed. This rapidly changes the large thermal inertia caused by the large circulating ash amount in the circulating fluidized bed boiler, enabling rapid adjustment of heat exchange between the furnace water-cooled walls and the circulating materials. Ultimately, this achieves rapid increases and decreases in boiler load to meet the rapid response requirements of the grid for large-scale renewable energy consumption. Furthermore, by rapidly adjusting the boiler load through changes in the concentration of external and internal circulating materials in the circulating fluidized bed, the system structure is simple and the load adjustment is flexible. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the structure of a circulating fluidized bed boiler with process heat storage according to an embodiment of the present invention;

[0059] Figure 2 This is a schematic diagram of the structure of a circulating fluidized bed boiler with process heat storage according to another embodiment of the present invention;

[0060] Figure 3 This is a schematic diagram illustrating the connection relationship between the heat storage chamber and the furnace, and between the heat storage chamber and the return feeder, according to an embodiment of the present invention.

[0061] Figure 4 This is a schematic diagram of the structure of a circulating fluidized bed boiler with process heat storage according to another embodiment of the present invention;

[0062] Figure 5 This is a schematic diagram of the structure of a circulating fluidized bed boiler with process heat storage according to another embodiment of the present invention;

[0063] Figure 6 This is a schematic diagram of the structure of a circulating fluidized bed boiler with process heat storage according to another embodiment of the present invention;

[0064] Figure 7 This is a schematic diagram of the structure of a circulating fluidized bed boiler with process thermal storage according to another embodiment of the present invention.

[0065] Explanation of reference numerals in the attached figures:

[0066] 1. Furnace; 2. Separator; 3. Return feeder; 4. Heat storage chamber; 51. Preheating chamber; 52. Preheating chamber coal feeder; 53. Main combustion chamber coal feeder; 11. First outlet; 41. First inlet; 12. Second inlet; 42. Second outlet; 43. Third inlet; 31. Return material inlet; 32. Storage outlet; 33. Return material outlet; 34. Side material outlet;

[0067] L1, First unidirectional channel; L2, Second unidirectional channel; L3, Third unidirectional channel; L4, Fourth unidirectional channel. Detailed Implementation

[0068] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0069] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0070] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0071] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0072] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). Similarly, when using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0073] To meet the large-scale grid connection demands of renewable energy, new requirements have been placed on the rapid load response capabilities of coal-fired power generating units. Circulating fluidized bed (CFB) boilers, due to their large circulating ash content, exhibit high thermal inertia. Furthermore, the large amount of anti-wear refractory material used in CFB boilers further increases thermal inertia, making it difficult to achieve rapid load adjustment using conventional regulation methods, thus hindering the ability to meet the requirements of large-scale renewable energy consumption. Moreover, high-ash coal results in low bed and steam temperatures under low loads, failing to meet steam parameter requirements. Therefore, there is an urgent need for a CFB boiler capable of rapid load adjustment and deep peak-shaving operation under low load conditions.

[0074] In view of this, the present invention provides a circulating fluidized bed boiler with process thermal storage to at least partially solve the above-mentioned technical problems. The circulating fluidized bed boiler with process thermal storage includes a furnace and at least one set of external circulation units.

[0075] The furnace is used to obtain external and internal circulating materials after the fuel and oxidant are burned in the furnace. The upper part of the furnace is provided with a gas-solid product outlet. The external circulating material is discharged through the gas-solid product outlet, and the internal circulating material circulates in the dense phase zone at the bottom of the furnace.

[0076] Each external circulation unit includes a separation and return device and a heat storage chamber. The separation and return device is connected to the gas-solid product outlet and is used to separate the gas-solid products to obtain external circulation material. The heat storage chamber is connected to both the separation and return device and the dense phase zone at the bottom of the furnace. The heat storage chamber is used to receive and store part of the external circulation material from the separation and return device and part of the internal circulation material from the dense phase zone during the load reduction adjustment phase.

[0077] Figure 1 This is a schematic diagram of the structure of a circulating fluidized bed boiler with process thermal storage according to an embodiment of the present invention.

[0078] like Figure 1As shown, the circulating fluidized bed boiler includes a furnace 1 and a set of external circulation units. Each set of external circulation units includes a separation and return device and a heat storage chamber 4. The separation and return device includes a separator 2, a return feeder 3, and a return riser. The furnace 1, separator 2, and return feeder 3 are interconnected to form a circulating fluidized bed boiler.

[0079] According to an embodiment of the present invention, the material circulation in the circulating fluidized bed boiler includes internal circulation and external circulation. Fuel and oxidant are burned in the furnace 1 to obtain external circulation material and internal circulation material. The external circulation material is discharged through the gas-solid product outlet at the top of the furnace 1. After separation and return, some unburned ash is returned to the furnace 1 to continue to participate in combustion. The internal circulation material circulates only in the furnace 1 and does not participate in the external circulation.

[0080] In the separation and return material device, the inlet of separator 2 is connected to the gas-solid product outlet at the top of furnace 1. It is used to separate the gas and solid products to obtain external circulating material. After passing through separator 2, the gaseous product is discharged from the gas phase outlet of the separator, and the solid product is discharged from the solid phase outlet of the separator. The solid product is the external circulating material, containing unburned residual carbon. The external circulating material enters the return material unit 3 through the return material riser, and then returns to furnace 1 through the return material unit 3.

[0081] The heat storage chamber 4 is connected to the separation and return material device and the dense phase zone at the bottom of the furnace 1, so that during the load reduction adjustment stage, the heat storage chamber 4 can receive and store part of the external circulating material from the separation and return material device and part of the internal circulating material from the dense phase zone, so as to significantly reduce the concentration of circulating material in the external and internal circulation of the circulating fluidized bed, thereby reducing the heat exchange between the water-cooled wall of the furnace 1 and the circulating material, and realizing a rapid reduction of boiler load.

[0082] According to an embodiment of the present invention, the heat storage chamber 4 is an insulated structure, and its outer wall can be made of high-temperature resistant insulation material, which is convenient for heat storage and insulation of high-temperature materials, and no heating surface is arranged inside the heat storage chamber 4.

[0083] According to embodiments of the present invention, in order to meet the large-scale grid connection requirements of renewable energy, circulating fluidized bed boilers need to be able to rapidly change load and achieve deep peak shaving at ultra-low loads. Therefore, it is necessary to increase or decrease the heat load of the circulating fluidized bed boiler according to actual operational needs. According to embodiments of the present invention, the heat storage chamber 4 is used to receive circulating material particles from the circulation loop and the bottom of the boiler, and is used to store high-temperature circulating materials when the boiler reduces load, so as to reduce the boiler's thermal inertia and achieve rapid load reduction.

[0084] According to an embodiment of the present invention, the heat storage chamber 4 is further used to return the heat-storing material in the heat storage chamber 4 to the dense phase zone at the bottom of the furnace 1 in stages during the load increase adjustment phase. The heat-storing material includes a portion of the external circulating material from the separation and return device and a portion of the internal circulating material from the dense phase zone. That is, when the boiler needs to increase its load, high-temperature circulating material is released to the furnace 1 to supplement the furnace 1 with heat, increase the bed temperature, and increase the concentration of circulating material, thereby achieving rapid load increase and improving combustion stability.

[0085] Due to the large thermal inertia of boilers, it is difficult to achieve rapid load adjustment using conventional adjustment methods. The embodiments of this disclosure, by setting up a heat storage chamber 4, which is connected to both the separation and return material device and the dense phase zone at the bottom of the furnace 1, allow the heat storage chamber 4 to not only receive and store external circulating materials during the load reduction adjustment phase, but more importantly, it can also store internal circulating materials. In situations requiring rapid load reduction and deep peak shaving (e.g., reducing the boiler heat load to 20% or below), the concentration of circulating materials within the boiler can be rapidly changed within a wide load range of 20%-100% by altering the amount of external and internal circulating materials in the circulating fluidized bed. This rapidly changes the large thermal inertia caused by the large amount of circulating materials in the circulating fluidized bed boiler, enabling rapid adjustment of heat exchange between the water-cooled wall of the furnace 1 and the circulating materials. Ultimately, this achieves rapid increases and decreases in boiler load to meet the rapid response requirements of the grid for large-scale renewable energy consumption. Furthermore, by rapidly adjusting the boiler load through changes in the concentration of external and internal circulating materials in the circulating fluidized bed, the system structure is simple and the load adjustment is flexible.

[0086] Figure 2 This is a schematic diagram of the structure of a circulating fluidized bed boiler with process thermal storage according to another embodiment of the present invention.

[0087] Figure 2 The circulating fluidized bed boiler shown is Figure 1 The circulating fluidized bed boilers shown are largely the same in structure, with the only difference being... Figure 2 It is equipped with four sets of external circulation units.

[0088] According to embodiments of the present invention, one or more external circulation units can be set up according to the size of the boiler heat load. For example, when the boiler heat load is small, only one external circulation unit can be set up, and when the boiler heat load is large, multiple external circulation units can be set up.

[0089] According to embodiments of the present invention, the communication relationship between the heat storage chamber 4 and the furnace 1, and between the heat storage chamber 4 and the return feeder 3, can be achieved through various structural forms. For example, see reference to Figures 3-5 The structure shown in the embodiment. Figure 3 According to the embodiments of the present invention ( Figure 1 , Figure 2The diagram shows the connection relationship between the heat storage chamber 4 and the furnace 1, and between the heat storage chamber 4 and the return feeder 3 of the circulating fluidized bed boiler. Figure 4 , Figure 5 These are schematic diagrams of the structure of a circulating fluidized bed boiler with process thermal storage according to other different embodiments of the present invention.

[0090] like Figure 3 , 4 As shown in Figure 5, specifically, the heat storage chamber 4 is connected to the dense phase region at the bottom of the furnace 1 through a first one-way channel L1 and a second one-way channel L2, wherein the first one-way channel L1 runs from the dense phase region to the heat storage chamber 4, and the second one-way channel L2 runs from the heat storage chamber 4 to the dense phase region. The separation and return device is connected to the heat storage chamber 4 through a third one-way channel L3, which runs from the separation and return device to the heat storage chamber 4.

[0091] Figure 3 , Figure 4 In this design, the heat storage chamber 4 and the furnace 1 are connected by the same structural arrangement. A feed channel from the furnace to the heat storage chamber 4 and a discharge channel from the heat storage chamber 4 to the furnace are provided between the furnace and the heat storage chamber 4. Both channels are unidirectional, and the openings of both channels on one side of the furnace are located in the dense phase region of the furnace. For example... Figure 3 , 4 As shown, a first outlet 11 is provided in the upper middle part of the dense phase zone at the bottom of the furnace 1, and a first inlet 41 is provided in the upper middle part of the heat storage chamber 4. The first outlet 11 and the first inlet 41 are connected by a first one-way channel L1. The first outlet 11 is higher than the first inlet 41. The first one-way channel L1 is inclined towards the heat storage chamber 4, allowing the material to flow unidirectionally into the heat storage chamber 4. A second inlet 12 is provided in the lower middle part of the dense phase zone, and a second outlet 42 is provided in the lower middle part of the heat storage chamber 4. The second inlet 12 and the second outlet 42 are connected by a second one-way channel L2. The second outlet 42 is higher than the second inlet 12. The second one-way channel L2 is inclined towards the dense phase zone at the bottom of the furnace 1, allowing the material in the second one-way channel L2 to flow unidirectionally into the dense phase zone.

[0092] Furthermore, an ash control valve is installed in the first one-way channel L1; the amount of coarse ash circulating internally can be precisely adjusted by regulating the opening of the ash control valve. An air distribution device is installed at the bottom of the heat storage chamber 4, comprising an air distribution plate and an air chamber, used to fluidize the material in the heat storage chamber 4 and transport it to the furnace. For example, increasing the air volume can increase the amount of material returned from the heat storage chamber 4 to the bottom of the furnace 1; conversely, decreasing the air volume can correspondingly decrease the amount of material returned from the heat storage chamber 4 to the bottom of the furnace 1.

[0093] and Figure 3 , Figure 4 The embodiments shown are different. Figure 5 In this case, the connection between the heat storage chamber 4 and the furnace 1 adopts a different structural arrangement.

[0094] like Figure 5 As shown, the heat storage chamber 4 is integrated with the dense phase zone at the bottom of the furnace 1. The heat storage chamber 4 is located outside the dense phase zone and is arranged below the return feeder 3. The heat storage chamber 4 and the dense phase zone share a partition wall, which includes a conical section and a straight section. The first one-way channel L1 is located in the conical section, and the second one-way channel L2 is located in the straight section. The first one-way channel L1 is higher than the second one-way channel L2.

[0095] Meanwhile, an air distribution device is installed at the bottom of the heat storage chamber 4. The air distribution device includes an air distribution plate and an air chamber, used to realize the fluidization and conveying control of the material in the heat storage chamber 4. For example, reducing the air distribution volume can increase the amount of material from the furnace 1 to the heat storage chamber 4 in the first one-way channel L1 and decrease the amount of material from the heat storage chamber 4 to the furnace 1 in the second one-way channel L2. Conversely, increasing the air distribution volume can decrease the amount of material from the furnace 1 to the heat storage chamber 4 in the first one-way channel L1 and increase the amount of material from the heat storage chamber 4 to the furnace 1 in the second one-way channel L2.

[0096] In this arrangement, the heat storage chamber 4 adopts an integrated design, which can significantly reduce the layout space of the heat storage chamber 4, reduce heat loss of the heat storage chamber 4, and improve heat storage efficiency.

[0097] like Figure 3 , 4 As shown in Figure 5, the separation and return device is connected to the heat storage chamber 4 through the third one-way channel L3, which runs from the separation and return device to the heat storage chamber 4.

[0098] Figure 3 , 4 The difference between the embodiments shown in 5 and 6 is that, Figure 3 , Figure 5 In the embodiment shown, the return feeder 3 adopts a one-in-two-out structure, and the height of the return feeder 3 is higher than that of the heat storage chamber 4. Figure 4 In the embodiment shown, the return feeder 3 adopts a one-in-one-out structure, and the height of the return feeder 3 is lower than that of the heat storage chamber 4.

[0099] like Figure 3 , Figure 5 As shown, the separation and return device includes a separator 2, a return feeder 3, and a return feeder riser; the return feeder 3 includes a return feeder inlet 31, a storage outlet 32, and a return feeder outlet 33; a third inlet 43 is provided in the upper part of the heat storage chamber 4; the bottom outlet of the return feeder riser is connected to the return feeder inlet 31; the storage outlet 32 ​​of the return feeder 3 and the third inlet 43 of the heat storage chamber 4 are connected through a third one-way channel L3, which facilitates the passage of material in the return feeder 3 to the heat storage chamber 4 through the third one-way channel L3.

[0100] Figure 3 , Figure 5 The difference between the embodiments shown is that, Figure 3In the middle, the return material outlet 33 is connected to the dense phase zone of the furnace 1. The material in the return material 3 can return to the bottom of the furnace 1 through the fourth one-way channel L4, and can be directed to the heat storage chamber 4 through the third one-way channel L3. Figure 5 In the middle, the return outlet 33 is connected to the heat storage chamber 4, and the material in the return feeder 3 is directed to the heat storage chamber 4 through the fourth one-way channel L4 and the third one-way channel L3.

[0101] Figure 4 In the illustrated embodiment, the return feeder 3 adopts a one-in-one-out structure, and the height of the return feeder 3 is lower than that of the heat storage chamber 4. Figure 4 As shown, the separation and return device includes a separator 2, a return feeder 3, and a return riser; the return feeder 3 includes a return inlet 31 and a return outlet 33. A third inlet 43 is provided in the upper part of the heat storage chamber 4; the bottom outlet of the return riser is connected to the return inlet 31. A side outlet 34 is provided in the lower part of the return riser, and the side outlet 34 and the third inlet 43 are connected through a third one-way channel L3, so that the return riser is connected to the upper part of the heat storage chamber 4. A side air duct is provided at the side outlet 34 in the lower part of the return riser, and the amount of external circulating material entering the heat storage chamber 4 is adjusted by regulating the side air volume.

[0102] This arrangement simplifies the structure of the return feeder 3, allows the heat storage chamber 4 to make full use of the space along the height of the return feeder riser, and enables the heat storage chamber 4 to flexibly achieve rapid storage and distribution of circulating materials.

[0103] Under high-load boiler conditions, the amount of fine external circulating material can be precisely adjusted by regulating the fluidizing air volume of return feeder 3 or the air volume of the lower side wall of the riser of return feeder 3. Through rapid and precise adjustment of the amount of external circulating material, the load can be quickly reduced under high-load conditions, solving the technical problem of large thermal inertia and difficulty in rapid load reduction caused by the large amount of external circulating material under high-load conditions.

[0104] According to an embodiment of the present invention, the separator 2 and the return feeder 3 of the circulating fluidized bed boiler can be two or more, and the heat storage chamber 4 can be one heat storage chamber 4 connected to one return feeder 3, or two or more return feeders 3 connected to one heat storage chamber 4; or one return feeder 3 can be connected to one, two or more heat storage chambers 4.

[0105] Figure 6 This is a schematic diagram of the structure of a circulating fluidized bed boiler with process thermal storage according to another embodiment of the present invention.

[0106] like Figure 6 As shown, in a further embodiment of the present invention, the circulating fluidized bed boiler can be combined with a preheating unit to further enhance the load regulation capability of the circulating fluidized bed boiler.

[0107] According to an embodiment of the present invention, the furnace 1 is further provided with a fuel inlet for introducing fuel into the furnace 1; the circulating fluidized bed boiler also includes a preheating unit, which is connected to the fuel inlet of the furnace 1 and is used to preheat the fuel before introducing it into the furnace 1 through the fuel inlet.

[0108] The preheating unit includes a preheating chamber 51, a preheating chamber feeder 52, and a main combustion chamber feeder 53. The preheating chamber 51 is an insulated or water-cooled circulating fluidized bed structure. Fuel is fed into the preheating chamber 51 through the preheating chamber feeder 52, where partial combustion occurs. The high-temperature exhaust and the ambient-temperature fuel from the main combustion chamber feeder 53 are further mixed and fed into the furnace 1. Alternatively, the high-temperature exhaust can be directly connected to the dense phase zone of the furnace. The preheating chamber 51 preheats the fuel to above its ignition point through a self-sustaining heating method of partial combustion, which can solve the problems of stable combustion, burnout, and rapid response to load changes under low load.

[0109] The preheating chamber 51 can be put into operation at 30% or less of the boiler load. The preheating chamber 51 is designed to have a heat input power of about 10%-30% of the heat input power under the rated load condition of the boiler. Moreover, the preheating chamber 51 is a circulating bed structure and can operate stably within the range of 30%-100% of its own designed power. Therefore, it will greatly expand the overall operating load range of the circulating fluidized bed boiler, and the boiler load adjustment range can be achieved from 10% to 100%.

[0110] Figure 7 This is a schematic diagram of the structure of a circulating fluidized bed boiler with process thermal storage according to another embodiment of the present invention.

[0111] The circulating fluidized bed boiler shown in this embodiment is... Figure 6 The structures shown are largely the same, the difference being that the dense phase zone at the bottom of furnace 1 and the heat storage chamber 4 adopt the same design. Figure 5 The integrated partition structure shown in the embodiment.

[0112] Based on the above-described circulating fluidized bed boiler, another aspect of the present invention provides a method for adjusting the variable load of a circulating fluidized bed boiler. This method is a method that can achieve rapid variable load adjustment and includes the following operations:

[0113] Operation S1: Fuel and oxidant are introduced into the furnace so that the fuel and oxidant are burned in the furnace to obtain external and internal circulating materials. The upper part of the furnace is provided with a gas-solid product outlet. The external circulating material is discharged through the gas-solid product outlet, and the internal circulating material circulates in the dense phase zone at the bottom of the furnace.

[0114] Operation S2: Pass the external circulating material into the separation and return device so that the gas-solid products can be separated by the separation and return device to obtain the external circulating material;

[0115] Operation S3: During the load reduction adjustment phase, a portion of the external circulating material originating from the separation and return device and a portion of the internal circulating material originating from the dense phase zone are introduced into the heat storage chamber to reduce the boiler heat load. The heat storage chamber is connected to the separation and return device and the dense phase zone at the bottom of the furnace, respectively.

[0116] According to an embodiment of the present invention, the above method further includes operation S4: during the load adjustment stage, the heat storage material in the heat storage chamber is returned to the dense phase zone at the bottom of the furnace in stages to increase the boiler heat load, wherein the heat storage material includes a portion of the external circulation material from the separation and return device and a portion of the internal circulation material from the dense phase zone.

[0117] According to embodiments of the present invention, in order to meet the large-scale grid connection requirements of renewable energy, it is necessary to increase or decrease the heat load of the circulating fluidized bed boiler according to the actual operational needs. Under actual deep peak-shaving operation conditions, there are operation stages from 100% rated load to 30% low load, and operation stages from 30% low load to 20% and below ultra-low load.

[0118] Specifically, the load reduction adjustment stage includes a first load reduction stage and a second load reduction stage. The first load reduction stage is the stage in which the boiler reduces from full load to a first predetermined load (from 100% rated load to 30% low load), and the second load reduction stage is the stage in which the boiler reduces from the first predetermined load to a second predetermined load (from 30% low load to 20% and below ultra-low load).

[0119] The specific adjustment method for reducing load is as follows:

[0120] 1. In the first load reduction stage from 100% rated load to 30% low load, a portion of the external circulating material from the separation and return device is introduced into the heat storage chamber to reduce the boiler load from full load to the first predetermined load. By adopting this method, the heat exchange between the furnace water-cooled wall and the circulating material is reduced by significantly reducing the concentration of circulating fine material in the circulating fluidized bed external circulation system, thereby achieving a rapid reduction in boiler load.

[0121] 2. In the second load reduction stage, from a low load of 30% to an ultra-low load of 20% or below, a portion of the internal circulating material originating from the dense phase zone is introduced into the heat storage chamber, thereby reducing the boiler load from the first predetermined load to the second predetermined load. This method significantly reduces the concentration of circulating material in the circulating fluidized bed system, thereby reducing heat exchange between the furnace water-cooled walls and the circulating material, and achieving a rapid reduction in boiler load.

[0122] For example, the aforementioned embodiments Figures 1-7 In the circulating fluidized bed boiler arrangement shown, under normal boiler operation, the external circulating fine material returns to the boiler furnace 1 through the return feeder 3 to supplement the circulating bed with heat and carry out a stable combustion and energy output process.

[0123] When the boiler is under high load and needs to participate in peak shaving or quickly reduce the load, the amount of fine ash in the external circulation is precisely adjusted by increasing the fluidizing air volume on the material outlet side of the return feeder 3 or increasing the air volume on the lower side wall of the return feeder 3 riser. Some of the high-temperature external circulation material is sent into the heat storage chamber 4 through the return feeder riser to significantly reduce the concentration of circulating fine material in the external circulation system of the circulating fluidized bed, thereby reducing the heat exchange between the water-cooled wall of the furnace 1 and the circulating material, and achieving a rapid reduction in boiler load until the boiler heat load drops from 100% rated load to 30% low load.

[0124] Furthermore, in the stage from a low load of 30% to an ultra-low load of 20% or below, simply changing the amount of fine material in the external circulation is insufficient to achieve a further rapid reduction in heat load. At this point, by introducing a portion of the internal circulation material in the dense phase zone at the bottom of furnace 1 into the heat storage chamber 4, the boiler heat load can be further reduced.

[0125] For example, the aforementioned embodiments Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 6 In the circulating fluidized bed boiler arrangement shown, by increasing the opening of the ash control valve in the first one-way channel L1, the amount of circulating material flowing from the dense phase zone at the bottom of the furnace 1 into the heat storage chamber 4 is increased. Simultaneously, by reducing the airflow at the bottom of the heat storage chamber 4, the amount of material returning from the heat storage chamber 4 to the bottom of the furnace 1 is reduced. By significantly reducing the concentration of circulating material in the circulating fluidized bed system, the heat exchange between the water-cooled wall of the furnace 1 and the circulating material is reduced, thereby achieving a rapid reduction in boiler load.

[0126] For example, the aforementioned embodiments Figure 5 , Figure 7 In the arrangement of the circulating fluidized bed boiler shown, by reducing the air volume at the bottom of the heat storage chamber 4, the amount of material from the furnace 1 to the heat storage chamber 4 in the first one-way channel L1 can be increased, and the amount of material from the heat storage chamber 4 to the furnace 1 in the second one-way channel L2 can be reduced, thereby significantly reducing the circulating ash concentration in the circulating system of the circulating fluidized bed.

[0127] According to embodiments of this disclosure, the specific method for adjusting the load increase is as follows:

[0128] 1. In the first load increase stage from ultra-low load of 20% and below to low load of 30%, some of the heat storage material in the heat storage chamber 4 is returned to the dense phase zone at the bottom of the furnace 1 to increase the concentration of circulating material in the furnace 1, thereby increasing the boiler heat load.

[0129] For example, the aforementioned embodiments Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 6 In the circulating fluidized bed boiler arrangement shown, by reducing the opening of the ash control valve in the first one-way channel L1, the amount of internal circulating material flowing from the dense phase zone at the bottom of the furnace 1 into the heat storage chamber 4 is reduced. Simultaneously, by increasing the airflow at the bottom of the heat storage chamber 4, the amount of material returning from the heat storage chamber 4 to the bottom of the furnace 1 is increased. For example, in the aforementioned embodiment... Figure 5 , Figure 7 In the circulating fluidized bed boiler arrangement shown, by increasing the air volume at the bottom of the heat storage chamber 4, the amount of material flowing from the furnace 1 to the heat storage chamber 4 in the first unidirectional channel L1 is reduced, while the amount of material flowing from the heat storage chamber 4 to the furnace 1 in the second unidirectional channel L2 is increased, thereby significantly increasing the amount of return material from the heat storage chamber 4 to the bottom of the furnace 1. By significantly increasing the concentration of circulating ash in the circulating system within the circulating fluidized bed, high-temperature material is supplied to the furnace 1, increasing the bed temperature of the furnace 1 to achieve stable and efficient combustion, thereby improving the heat exchange between the water-cooled wall of the furnace 1 and the circulating ash, and enabling a rapid increase in boiler load.

[0130] 2. During the second load increase phase, from 30% low load to 100% rated load, some high-temperature circulating ash and materials are continued to be added to the furnace 1 through the heat storage chamber 4 to increase the concentration of circulating materials outside the furnace 1, thereby enhancing the heat exchange between the water-cooled wall of the furnace 1 and the circulating materials and achieving rapid load increase.

[0131] According to an embodiment of the present invention, through the above-described adjustment method, when the boiler needs to rapidly increase its load, the one-way discharge port of the heat storage chamber 4 replenishes a portion of high-temperature circulating ash and materials into the furnace 1, supplementing the furnace 1 with a portion of heat, thereby increasing the bed temperature of the furnace 1 to achieve stable and efficient combustion. Simultaneously, by increasing the material concentration in both the internal and external circulation of the furnace 1, the heat exchange between the water-cooled wall of the furnace 1 and the circulating materials is enhanced, achieving rapid load increase. Under low-load conditions, the amount of circulating coarse ash in the dense phase zone of the furnace 1 is precisely adjusted through the ash control valve in the feed channel of the heat storage chamber 4. This rapid and precise adjustment of the internal circulating ash amount enables rapid load reduction under low-load conditions, solving the problem that the insufficient amount of external circulating material under low-load conditions prevents rapid adjustment of the boiler load.

[0132] According to an embodiment of the present invention, the method further includes, during the boiler start-up phase, preheating the fuel through a preheating unit so that the preheated fuel can be introduced into the furnace 1.

[0133] The method described in this embodiment can be utilized as follows: Figure 6 , Figure 7The circulating fluidized bed boiler shown in the embodiment achieves the following: Specifically, during the boiler startup phase, when the boiler is running from zero load to 30% low load, the preheating chamber 51 is started. By preheating the ambient temperature fuel (0-40℃) to a high temperature gas-solid fuel of 800-1000℃, and simultaneously adjusting the fuel particle size from 0-8mm to 0-1mm, the combustion reaction rate is accelerated through the combination of these two technical means, thereby achieving rapid load increase of the boiler. When the boiler is running from 30% low load to 100% rated load, the preheating chamber 51 is kept running normally, and the boiler load change can be adjusted by adjusting the air-fuel ratio.

[0134] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for rapid load adjustment of a circulating fluidized bed boiler with process thermal storage, comprising: Fuel and oxidant are introduced into the furnace so that the fuel and oxidant are burned in the furnace to obtain external circulating material and internal circulating material. The upper part of the furnace is provided with a gas-solid product outlet. The external circulating material is discharged through the gas-solid product outlet, and the internal circulating material circulates in the dense phase zone at the bottom of the furnace. The external circulating material is fed into the separation and return device so that the gas-solid products are separated into gas and solid by the separation and return device to obtain the external circulating material. In the first load reduction stage, when the boiler is reduced from full load to a first predetermined load, a portion of the external circulating material originating from the separation and return device is introduced into the heat storage chamber to reduce the boiler load from full load to the first predetermined load; in the second load reduction stage, when the boiler load is reduced from the first predetermined load to a second predetermined load, a portion of the internal circulating material originating from the dense phase zone is introduced into the heat storage chamber to reduce the boiler load from the first predetermined load to the second predetermined load, wherein the heat storage chamber is connected to the separation and return device and the dense phase zone at the bottom of the furnace, respectively; The heat storage chamber is connected to the dense phase region at the bottom of the furnace through a first one-way channel and a second one-way channel. The first one-way channel runs from the dense phase region to the heat storage chamber, and the second one-way channel runs from the heat storage chamber to the dense phase region. The upper middle part of the dense phase zone is provided with a first outlet, and the upper middle part of the thermal storage chamber is provided with a first inlet. The first outlet and the first inlet are connected through the first one-way channel, and the first outlet is higher than the first inlet. The lower middle part of the dense phase zone is provided with a second inlet, and the lower middle part of the thermal storage chamber is provided with a second outlet. The second inlet and the second outlet are connected through the second one-way channel, and the second outlet is higher than the second inlet.

2. The adjustment method according to claim 1 further includes: During the load increase adjustment phase, the heat storage material in the heat storage chamber is returned to the dense phase zone at the bottom of the furnace in stages to increase the boiler heat load. The heat storage material includes a portion of the external circulation material from the separation and return device and a portion of the internal circulation material from the dense phase zone.

3. The adjustment method according to claim 2 further includes: During boiler startup, the fuel is preheated through a preheating unit so that the preheated fuel can be introduced into the furnace.

4. A circulating fluidized bed boiler with process thermal storage for implementing the regulating method according to any one of claims 1-3, comprising: A furnace is used to burn fuel and oxidant to obtain external and internal circulating materials. The upper part of the furnace is provided with a gas-solid product outlet. The external circulating material is discharged through the gas-solid product outlet, and the internal circulating material circulates in the dense phase zone at the bottom of the furnace. At least one set of outer loop units, each set of said outer loop units comprising: A separation and return device is connected to the outlet of the gas-solid product and is used to separate the gas-solid product into gas-solid components to obtain external circulating material. The heat storage chamber is connected to the separation and return material device and the dense phase zone at the bottom of the furnace, respectively. The heat storage chamber is used to receive and store a portion of the external circulating material from the separation and return material device and a portion of the internal circulating material from the dense phase zone during the load reduction adjustment phase.

5. The circulating fluidized bed boiler with process thermal storage according to claim 4, wherein: The heat storage chamber is also used to return the heat storage material in the heat storage chamber to the dense phase zone at the bottom of the furnace in stages during the load adjustment phase, wherein the heat storage material includes a portion of the external circulation material from the separation and return device and a portion of the internal circulation material from the dense phase zone.

6. The circulating fluidized bed boiler with process thermal storage according to claim 4, wherein: The heat storage chamber is connected to the dense phase region at the bottom of the furnace through a first one-way channel and a second one-way channel, wherein the first one-way channel runs from the dense phase region to the heat storage chamber, and the second one-way channel runs from the heat storage chamber to the dense phase region.

7. The circulating fluidized bed boiler with process thermal storage according to claim 6, wherein: The upper middle part of the dense phase zone is provided with a first outlet, and the upper middle part of the thermal storage chamber is provided with a first inlet. The first outlet and the first inlet are connected through the first one-way channel, and the first outlet is higher than the first inlet. The lower middle part of the dense phase zone is provided with a second inlet, and the lower middle part of the thermal storage chamber is provided with a second outlet. The second inlet and the second outlet are connected through the second one-way channel, and the second outlet is higher than the second inlet.

8. The circulating fluidized bed boiler with process thermal storage according to claim 7, wherein: The first unidirectional channel is equipped with an ash control valve; The bottom of the heat storage chamber is equipped with an air distribution device.

9. The circulating fluidized bed boiler with process thermal storage according to claim 6, wherein: The heat storage chamber is located outside the dense phase zone, and the heat storage chamber and the dense phase zone share a partition wall. The partition wall includes a conical section and a straight section. The first one-way channel is located in the conical section, and the second one-way channel is located in the straight section. The first one-way channel is higher than the second one-way channel. The bottom of the heat storage chamber is equipped with an air distribution device.

10. The circulating fluidized bed boiler with process thermal storage according to claim 4, wherein: The separation and return device is connected to the heat storage chamber through a third one-way channel, which runs from the separation and return device to the heat storage chamber.

11. The circulating fluidized bed boiler with process thermal storage according to claim 10, wherein: The separation and return device includes a separator, a return feeder, and a return riser. The return feeder includes a return inlet and a storage outlet; The heat storage chamber is provided with a third inlet in the upper part; The bottom outlet of the return riser is connected to the return inlet; The storage outlet and the third inlet are connected through the third one-way channel.

12. The circulating fluidized bed boiler with process thermal storage according to claim 11, wherein: The return feeder also includes a return outlet; The return material outlet is connected to the dense phase zone of the furnace, or the return material outlet is connected to the heat storage chamber.

13. The circulating fluidized bed boiler with process thermal storage according to claim 10, wherein: The separation and return device includes a separator, a return feeder, and a return riser. The return feeder includes a return inlet; The heat storage chamber is provided with a third inlet in the upper part; The bottom outlet of the return riser is connected to the return inlet; The lower middle part of the return material riser is provided with a side material outlet, and the side material outlet and the third inlet are connected through the third one-way channel. A side air duct is provided at the side material outlet.

14. The circulating fluidized bed boiler with process thermal storage according to claim 4, wherein: The furnace is also provided with a fuel inlet, which is used to introduce fuel into the furnace. The circulating fluidized bed boiler further includes a preheating unit, which is connected to the fuel inlet of the furnace or to the dense phase zone of the furnace. The preheating unit is used to preheat the fuel and then introduce it into the furnace through the fuel inlet.

15. The circulating fluidized bed boiler according to claim 4, wherein: The outer wall of the heat storage chamber is made of thermal insulation material.

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