Near-zero load deep tuning and fast start-stop circulating fluidized bed boiler

Abstract

This utility model relates to a circulating fluidized bed boiler, comprising: a furnace, a separator, and a return feeder; a heating surface is provided inside the furnace; at least one activation device, wherein an activator and fuel are adapted to be introduced into the activation chamber of the activation device, and the fuel entering the activation device is adapted to be activated in the activation chamber to generate gas-solid fuel; the rated heat capacity of a single activation device is 2%-15% of the rated heat capacity of the circulating fluidized bed boiler; fuel nozzles are provided on the rear wall of the furnace or on the rear wall and two side walls, located below the furnace screen-type heating surface. Based on the above technical solution, problems such as short boiler standby time, long start-up time, and difficulty in rapid and flexible peak regulation at full load can be solved or alleviated.

Description

Technical Field

[0001] The embodiments of this utility model relate to the field of circulating fluidized bed boiler technology, and in particular to a circulating fluidized bed boiler. Background Technology

[0002] Against the backdrop of continuous adjustments to the energy structure, the proportion of new energy sources in the power supply system is increasing. Circulating fluidized bed boilers, as a highly efficient and clean power generation device, have been widely used in power production and other fields, and their operating characteristics are crucial to the stable and efficient operation of the power system. However, circulating fluidized bed boilers currently face a series of severe technical challenges in actual operation.

[0003] Firstly, with the rapid development of a high proportion of renewable energy, coal-fired circulating fluidized bed boilers need to implement deep and flexible peak shaving, especially near-zero load shut-off peak shaving, to meet the requirements of a large proportion of renewable energy consumption. Due to the continuous cooling effect of the furnace water-cooled walls and heating surfaces, the bed temperature and steam temperature will drop rapidly. Traditional circulating fluidized bed boilers, without additional combustion-aiding measures, have extremely limited shut-off hot standby time. This is because as the bed temperature and steam temperature decrease, the combustion conditions in the furnace gradually deteriorate, and when the temperature drops to a certain level, even if fuel is added again, it is difficult to quickly restore stable combustion. With a high proportion of renewable energy connected to the grid, the electricity market has experienced long periods of zero electricity price, which requires boilers to have a longer shut-off hot standby capability to cope with this special market demand. Existing boiler shut-off hot standby technologies mainly use high bed temperature and high bed pressure or combustion-aiding measures to extend the boiler shut-off hot standby time. Currently, the longest shut-off hot standby time of boilers is less than 2 hours, which is far from meeting the needs of long periods of zero electricity price. As a result, during long periods of zero electricity price, boilers cannot flexibly maintain a hot standby state, increasing power generation costs and energy waste.

[0004] Secondly, coal-fired circulating fluidized bed boilers have strong thermal inertia, resulting in excessively long start-up times after the boiler has undergone a hot standby phase. Because the bed temperature is low after the hot standby phase, and circulating fluidized bed boilers inherently possess significant thermal inertia, rapidly raising the boiler from its low bed temperature to normal operating temperature and achieving stable combustion requires substantial time and energy. This not only reduces the unit's response speed but also, when rapid changes in grid load necessitate quick boiler startup, the current hot standby start-up time exceeds 2 hours, failing to meet timely power supply demands and impacting the stability and reliability of the power grid.

[0005] Furthermore, circulating fluidized bed boilers face significant challenges in achieving near-zero load deep regulation and full-load peak shaving due to the combined effects of low bed temperature and strong thermal inertia. Near-zero load deep regulation requires the boiler to maintain stable operation at extremely low loads and respond quickly to minute load changes. However, low bed temperatures slow down fuel combustion, making precise control of combustion intensity difficult and prone to combustion instability or even flameout at near-zero loads. Regarding full-load peak shaving, the presence of thermal inertia causes rapid load fluctuations, leading to significant variations in steam parameters. This poses a serious threat to boiler safety and steam quality, and also limits the boiler's ability to flexibly adjust loads across different load ranges. Currently, the deep regulation load for large circulating fluidized bed boilers is 30%, with some individual boiler units reaching 20%, which fails to meet the requirements of modern power systems for flexible peak shaving.

[0006] Specifically, existing coal-fired circulating fluidized bed boilers have the following technical defects:

[0007] 1) Due to the cooling effect of the furnace water-cooled wall and the heating surface, the bed temperature and steam temperature of the coal-fired boiler are low when it is under fire-up and hot standby. The boiler has a short fire-up and hot standby time (<2h) without combustion support, which cannot meet the demand for long-term zero electricity price under the high proportion of new energy.

[0008] 2) Coal-fired circulating fluidized bed boilers have long start-up times (>2h) under low bed temperature conditions during closed-fire and hot standby, resulting in slow unit response and affecting the stability and reliability of the power grid.

[0009] 3) Coal-fired circulating fluidized bed boilers are difficult to achieve near-zero load deep regulation and full load peak regulation (minimum deep regulation load 30%) under low bed temperature and strong thermal inertia, which cannot meet the requirements of modern power systems for flexible peak regulation of units.

[0010] In summary, existing coal-fired circulating fluidized bed boiler technology has significant shortcomings in meeting the new operational requirements following the high proportion of new energy sources. There is an urgent need for an innovative technical solution to address issues such as short standby time, long start-up time, and difficulties in deep adjustment at near-zero load and peak shaving at full load. Summary of the Invention

[0011] In response to at least one aspect of the above-mentioned problems, the present invention proposes the following technical solution.

[0012] A circulating fluidized bed boiler, comprising:

[0013] The furnace includes a separator and a return feeder, with a heating surface installed inside the furnace.

[0014] At least one activation device, wherein the activator and fuel are adapted to be introduced into the activation chamber of the activation device, and the fuel entering the activation device is adapted to be activated in the activation chamber to generate gas-solid fuel, wherein the rated heat capacity of a single activation device is 2%-15% of the rated heat capacity of the circulating fluidized bed boiler.

[0015] Wherein: the rear wall of the furnace or the rear wall and the two side walls are provided with fuel nozzles located below the furnace heating surface.

[0016] Optionally, the fuel nozzle includes a rear wall fuel nozzle disposed on the rear wall of the furnace; the at least one activation device includes a rear wall activation device, wherein the gas-solid fuel outlet of the rear wall activation device is connected to the rear wall fuel nozzle.

[0017] Optionally, the at least one activation device includes two rear wall activation devices with the same heat load, and the total heat load of the two rear wall activation devices is 5% to 15% of the boiler's rated load.

[0018] Optionally, the fuel nozzles on the rear wall are arranged uniformly and symmetrically along the rear wall in the width direction of the furnace.

[0019] Optionally, the at least one activation device includes a left wall activation device and a right wall activation device with the same heat load, and a rear wall activation device; the side wall of the furnace is provided with a side wall fuel nozzle communicating with the gas-solid fuel outlet of the left wall activation device and the right wall activation device; the heat load of the rear wall activation device is 2% to 10% of the boiler's rated load, and the total heat load of the left wall activation device and the right wall activation device is 10% to 30% of the boiler's rated load.

[0020] Optionally, the fuel nozzles include sidewall fuel nozzles arranged on the left and right walls of the furnace, and the sidewall fuel nozzles are uniformly and symmetrically arranged along the sidewalls in the depth direction of the furnace.

[0021] Optionally, a single activation device can be connected to 2-4 fuel nozzles simultaneously.

[0022] Optionally, the boiler further includes a monitoring device and a control device, wherein the monitoring device is adapted to monitor in real time at least one of steam temperature, steam pressure, bed temperature in the furnace, and temperature and pressure of the activation device, and the control device is adapted to automatically adjust the fuel supply to the activation device.

[0023] Optionally, the activation device is in the form of a circulating fluidized bed.

[0024] Optionally, the boiler further includes a control device configured to: activate at least one activation device during boiler standby, or during the process of increasing the boiler load from the standby state to 15% of the boiler's rated load, or during the process of further increasing the boiler load from 15% of the boiler's rated load to 30% of the boiler's rated load, or during the process of further increasing the boiler load from 30% of the boiler's rated load to 100% of the boiler's rated load, or during the process of starting the boiler from the standby state, to introduce the gaseous fuel from the gaseous fuel outlet of the activation device into the fuel nozzle.

[0025] This utility model proposes a boiler that can solve or alleviate the problems of short hot standby time under non-combustion conditions, long restart time after fire suppression, and inability to meet the full load peak regulation requirements of coal-fired circulating fluidized bed boilers. Attached Figure Description

[0026] The following description and accompanying drawings will better aid in understanding these and other features and advantages of the various embodiments disclosed herein, wherein the same reference numerals in the drawings always denote the same parts, wherein:

[0027] Figure 1 A front view of a circulating fluidized bed boiler according to an exemplary embodiment of the present invention;

[0028] Figure 2-8 This is a top view of a circulating fluidized bed boiler according to different exemplary embodiments of the present invention.

[0029] 1-Furnace chamber; 11-Front wall; 12-Rear wall; 13-Right side wall; 14-Left side wall; 15-Heating surface; 16-Coal feed pipe; 17-High-temperature fuel nozzle; 2-Cyclone separator; 3-Return feeder; 4-Activation chamber. a-Solid fuel 1; b-Solid fuel 2; c-Activator. Detailed Implementation

[0030] The technical solution of this utility model will be further described in detail below through embodiments and in conjunction with the accompanying drawings. The following description of the embodiments of this utility model with reference to the accompanying drawings is intended to explain the overall inventive concept of this utility model and should not be construed as a limitation thereof. These are only some embodiments of the invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model are within the protection scope of this utility model.

[0031] Figure 1 This is a front view of a circulating fluidized bed boiler according to an exemplary embodiment of the present invention. Figure 1As shown, the circulating fluidized bed boiler consists of a furnace 1, a cyclone separator 2, a return feeder 3, and an activation chamber 4. The furnace 1 consists of a front wall 11, a rear wall 12, a right side wall 13, a left side wall 14, an internal heating surface 15, a furnace fuel feeding device 16, and high-temperature fuel nozzles 17 for the activation chambers. The activation chambers are evenly and symmetrically arranged on the rear wall of the furnace, with 1-2 activation chambers on the rear wall. Each activation chamber has 2-4 high-temperature fuel nozzles at its upper outlet. These high-temperature fuel nozzles are evenly distributed along the width of the furnace to ensure uniform heat load and temperature distribution along the furnace width. Fuel b is fed into the activation chamber from the lower middle part, and activator c is fed into the activation chamber from the bottom. A high-temperature gas-solid fuel outlet is provided at the top of the activation chamber and is connected to the high-temperature gas-solid fuel nozzles 17 in the furnace. Fuel a is fed into the furnace from the lower dense phase zone. Fuel a is a carbon-based fuel such as coal, biomass, coal slime, or coal gangue; fuel b is a carbon-based fuel such as coal, biomass, or coal slime; fuel a and fuel b may be the same fuel or different fuels; activator c is air, O2, CO2, water vapor, or a mixture of two or more of these four activators.

[0032] exist Figures 1-5 In this case, the activation chamber or fuel nozzle is only located on the rear wall of the furnace.

[0033] exist Figures 6-8 In this system, the activation chamber or fuel nozzle is located on the rear wall of the furnace and on the two side walls of the furnace. For example... Figures 6-8 As shown, activation chambers are arranged on the rear wall and left and right side walls of the furnace. A single activation chamber is located on the rear wall, with one or two high-temperature fuel nozzles corresponding to its upper outlet. Of course, two or more activation chambers can also be arranged on the rear wall. Two activation chambers are symmetrically arranged on the left and right side walls, with each chamber corresponding to two high-temperature fuel nozzles. These two high-temperature fuel nozzles are evenly distributed along the furnace depth direction. Alternatively, they can be arranged asymmetrically along the furnace depth direction according to actual needs. Figures 6-8 The furnace and activation chamber in the proposed scheme contain fuel and activator in the activation chamber, respectively. Figures 1-5 middle.

[0034] The following exemplifies the full-load peak-shaving method of the boiler of this utility model when the entire activation chamber is arranged on the rear wall, which includes the following steps:

[0035] 1) Two activation devices are installed on the rear wall, and the total heat load of the two activation devices on the rear wall is 5% to 15% of the rated load of the boiler;

[0036] 2) When the boiler is in standby mode with the fire shut off, the boiler furnace is shut down for coal and air. At this time, a single rear wall activation device is put into operation.

[0037] 3) During the process of increasing the boiler load from the reduced-fire state to 15%, the boiler furnace is shut down for coal and air, and two rear wall activation devices are put into operation.

[0038] 4) During the process of increasing the boiler load from 15% to 30%, two rear wall activation devices are put into operation. The total load of the two rear wall activation devices is 15%, and the boiler load is 0-15%.

[0039] 5) During the process of increasing the boiler load from 30% to 100%, two rear wall activation devices are put into operation. The total load of the two rear wall activation devices is 15%, and the boiler load is 15-85%. The two rear wall activation devices can also be kept on standby without being put into operation.

[0040] In addition, when the boiler is started from the preheated standby state, both rear wall activation devices are fully engaged, and the high-temperature gas-solid binary active fuel burns rapidly in the furnace, releasing a large amount of heat and enabling the boiler unit to start up quickly.

[0041] The following exemplarily illustrates the full-load peak-shaving method for the boiler of this utility model when the activation chamber is arranged on the left and right side walls and the rear wall, which includes the following steps:

[0042] 1) An activation device is installed on the rear wall, and an activation device is installed on each of the left and right side walls;

[0043] 2) The heat load of the activation device on the rear wall is 2% to 10% of the rated load of the boiler, and the total heat load of the two activation devices on the left and right side walls is 10% to 30% of the rated load of the boiler;

[0044] 3) When the boiler is in standby mode, the boiler furnace is shut down and the coal and air are stopped. At this time, the single activation device on the rear wall is activated, while the activation devices on the left and right side walls are deactivated.

[0045] 4) When the boiler load increases from the reduced-fire state to 15%, the boiler furnace is shut down for coal and air, and the two activation devices on the left and right side walls are activated, while the activation device on the rear wall is deactivated.

[0046] 5) When the boiler load continues to increase from 15% to 30%, the two activation devices on the left and right side walls are put into operation. The load of the two activation devices is 15%, the boiler load is 0-15%, and the activation device on the rear wall is shut down.

[0047] 6) When the boiler load continues to increase from 30% to 100%, the two activation devices on the left and right side walls are put into operation. The load of the two activation devices is 15-30%, the boiler load is 15-70%, and the activation device on the rear wall is shut down.

[0048] In addition, when the boiler is started from the preheated standby state, the activation devices on the rear wall and the left and right side walls are put into operation at the same time. The high-temperature gas-solid binary active fuel burns rapidly in the furnace, releasing a large amount of heat and realizing the rapid start-up of the boiler unit.

[0049] In this invention, to address the problems of short standby time and long start-up time after standby in existing coal-fired circulating fluidized bed boilers without auxiliary heat sources, which prevent them from meeting the flexible peak-shaving requirements at full load, the following improvements are made:

[0050] In terms of fuel modification, a novel high-temperature activation modification technology has been introduced. Traditional circulating fluidized bed boilers directly feed ambient-temperature coal particles into the furnace for combustion. The coal particles require a certain amount of time to heat up and reach the ideal reaction state within the furnace, resulting in poor combustion reaction flexibility. This invention allows the coal particles to first undergo partial combustion in an activation chamber, generating temperatures of approximately 800℃ to 1000℃, transforming them into high-temperature gas-solid binary activated fuel before entering the boiler furnace for combustion. Through this high-temperature activation modification, the physical and chemical properties of the coal particles are significantly altered, and their reactivity is significantly enhanced. The specific surface area of ​​the high-temperature activated coal particles is approximately 20 times larger than that of ordinary coal particles, the number of active sites more than doubles, and the reaction rate increases by approximately 15 times. This achieves rapid combustion of the coal particles, greatly improving the combustion reaction rate, reaction flexibility, and load adjustment flexibility under low load and low bed temperature conditions.

[0051] In terms of hot standby under reduced combustion conditions, multiple activation devices are installed to supplement the heat required for the furnace heating surfaces to absorb heat during reduced combustion, maintaining high bed and steam temperatures and extending the hot standby time under zero electricity price. When the boiler is in hot standby under reduced combustion conditions, the furnace water-cooled walls, superheaters, and reheaters continuously absorb heat, causing a decrease in bed and steam temperatures. This invention utilizes activation devices to generate high-temperature gas-solid binary activated fuel. The heat generated by the combustion of this fuel in the furnace effectively supplements the heat required for the furnace water-cooled walls and heating surfaces to absorb heat, thereby maintaining high bed and steam temperatures and significantly extending the hot standby time. Previously, due to the rapid decrease in bed and steam temperatures, the boiler's hot standby time under reduced combustion conditions was short, failing to meet the requirements of long periods of zero electricity price under high renewable energy ratios. This invention, through this method, allows the boiler to maintain a long-term hot standby state without additional combustion equipment, meeting the market demand for boiler hot standby during long periods of zero electricity price.

[0052] In terms of boiler startup, rapid startup is achieved by leveraging the rapid combustion characteristics of high-temperature gas-solid binary activated fuel. When a boiler is ignited from a preheated standby state, traditional methods result in a slow startup process due to low bed temperature and high thermal inertia. This invention utilizes high-temperature gas-solid binary activated fuel, which, due to its high reactivity, can burn rapidly at a relatively low bed temperature, quickly releasing a large amount of heat and thus rapidly increasing the furnace temperature, achieving rapid boiler startup. Compared to traditional startup methods, this significantly shortens startup time and improves the unit's response speed to changes in grid load.

[0053] For full-load peak shaving, flexible adjustment is achieved by optimizing the layout and activation strategy of the activation devices. Two activation devices, each accounting for 5-15% of the boiler's rated heat capacity, are symmetrically arranged on the left and right side walls of the furnace, while one activation device, accounting for 2-10% of the boiler's rated heat capacity, is arranged on the rear wall of the furnace. Different activation device activation strategies are adopted according to different load stages. When the boiler is in closed-fire standby mode, only the single activation device on the rear wall is activated, providing a small but stable amount of heat to maintain the furnace temperature. When the boiler load increases from closed-fire state to 15%, the activation devices on the left and right side walls are activated to appropriately increase the heat supply to meet the increased load demand. When the boiler load continues to increase from 15%, both activation devices on the left and right side walls are activated to further increase the heat supply, ensuring stable operation of the boiler in different load ranges. This flexible layout and activation strategy of multiple activation devices and high-temperature fuel nozzles enables the boiler to achieve flexible response, adjustment, and load-changing operation under different loads, effectively solving the problem that circulating fluidized bed boilers are difficult to achieve near-zero load deep adjustment and full-load peak shaving under low bed temperature and strong thermal inertia.

[0054] This utility model relates to a near-zero load deep adjustment, rapid start-up and shutdown boiler, and a boiler full-load peak shaving method and system, which involves an activation device, a furnace, and related flexible commissioning and control strategies.

[0055] The activation unit is a key piece of equipment for achieving high-temperature activation and modification of fuel. Two activation units are symmetrically arranged on the left and right side walls of the furnace. Each activation unit has a rated heat capacity accounting for 5-15% of the boiler's total capacity. These two symmetrically arranged activation units, through the uniform distribution of high-temperature fuel nozzles along the furnace depth, ensure that the activated fuel enters the furnace evenly, guaranteeing the uniformity of the temperature and combustion fields within the furnace. Simultaneously, an activation unit with a rated heat capacity accounting for 2-10% of the boiler's total capacity is arranged on the rear wall of the furnace. The rear wall activation unit is mainly used to provide stable base heat under ultra-low load conditions such as boiler shutdown and hot standby, maintaining the required bed temperature and steam temperature in the furnace.

[0056] The internal structure of the activation device must meet the high-temperature preheating requirements of the coal particles. After the coal particles enter the activation chamber through the feed inlet, the coal combustion portion can rapidly heat the coal particles to approximately 800℃~1000℃. The activation chamber can adopt a circulating fluidized bed method to ensure uniform heating of the coal particles during the heating process, ensuring that all coal particles have sufficient residence time to be fully activated and transformed into high-temperature gas-solid binary activated fuel.

[0057] When the boiler is in the preheating standby state, the activation device on the rear wall is the first to start operation. The activation device generates high-temperature gas-solid binary activated fuel, which is injected into the furnace through specially designed pipes and nozzles. The design angle and position of the nozzles allow the fuel to fully diffuse within the furnace and mix thoroughly with the remaining oxygen, achieving stable combustion. The heat generated by combustion replenishes the heat lost from the furnace's water-cooled walls and heating surfaces, maintaining a high bed temperature and high steam temperature, and extending the preheating standby time. During this process, temperature sensors monitor the bed temperature and steam temperature in the furnace in real time. The temperature sensors feed the monitoring data back to the control system, which automatically adjusts the fuel supply to the activation device according to the preset temperature range, ensuring that the bed temperature and steam temperature are always maintained within a suitable range.

[0058] When the boiler is started from a preheated standby state, all activation devices are simultaneously activated. High-temperature gas-solid binary active fuel burns rapidly in the furnace, releasing a large amount of heat. Due to the high reactivity of the activated fuel, it can ignite quickly and achieve stable and intense combustion even under the low bed temperature conditions after preheated standby, rapidly increasing the furnace temperature. As the furnace temperature rises, the various components of the boiler gradually heat up to their normal operating temperature, enabling rapid startup of the boiler unit. During startup, temperature and pressure sensors and other equipment monitor various parameters within the boiler in real time. The control system adjusts the fuel supply to the activation devices and the operating status of other auxiliary equipment based on these parameters to ensure a safe and stable startup process.

[0059] For full-load peak shaving of the boiler, the following flexible commissioning strategy is adopted. When the boiler is in a zero-load state (under reduced firing), only the rear wall activation device operates. The heat provided by the combustion of the activated fuel is just enough to maintain the basic furnace temperature, preventing excessive temperature drop. When the boiler begins to increase its load, from the reduced firing state to 15%, the activation devices on both the left and right walls are put into operation. At this time, the activated fuel produced by the two activation devices burns together, providing more heat to meet the energy demand of the increased load. During this process, by monitoring at least one of the following parameters—steam flow rate, pressure, steam temperature, bed temperature in the furnace, activation device temperature, and activation device pressure—the control system automatically adjusts the fuel supply of the two activation devices to ensure the stability of steam parameters. When the boiler load continues to increase from 15%, the rear wall activation device and the two activation devices on the left and right walls can all be put into operation. The three activation devices work together to provide a large amount of activated fuel for combustion, ensuring stable boiler operation under high load. As the load changes, the control system adjusts the fuel supply ratio and total amount of each activation device in real time, achieving precise regulation of the boiler load, meeting the load increase and decrease requirements of different load ranges, and realizing flexible full-load peak shaving of the boiler.

[0060] In summary, this utility model aims to solve the key technical problems existing in the current circulating fluidized bed boiler and improve the boiler's operating performance and adaptability by improving fuel handling, hot standby, start-up and full-load peak shaving in multiple aspects.

[0061] Based on the above technical solution, at least one of the following technical effects can be achieved:

[0062] 1) From the perspective of long-term boiler standby, the high-temperature gas-solid binary activated fuel generated by the activation device supplements the heat, effectively maintaining high furnace bed temperature and high steam temperature, and greatly extending the standby time. Zero-power output standby time can reach 4-6 hours, which is significant in the context of a high proportion of new energy sources being integrated into the grid. Previously, boilers without combustion had short standby times, making it difficult to adapt to long periods of zero electricity price. Now, they can maintain a long-term hot standby state, which not only allows power generation companies to participate more flexibly in electricity market regulation, rationally arrange power generation periods according to electricity price fluctuations, reduce power generation costs, and improve economic efficiency, but also reduces equipment wear caused by frequent boiler starts, extends the service life of boilers and related equipment, and further reduces operating costs.

[0063] 2) Regarding rapid start-up and shutdown of boiler units, the rapid combustion characteristics of high-temperature gas-solid binary activated fuel successfully solve the problem of low combustion reaction rate at low load and low bed temperature, significantly shortening the start-up time after boiler unit hot standby. The start-up time without combustion heat is less than 1 hour. Under traditional start-up methods, boilers often require a long time (>2 hours) to start from a compressed-fire hot standby state, while this new technology can significantly shorten the start-up time. This is crucial for the power grid to cope with sudden load changes, enabling the boiler to quickly respond to grid demands and provide timely power support, effectively improving the stability and reliability of the power grid. Rapid start-up also reduces energy consumption during the start-up process, meeting energy conservation and emission reduction requirements, and further improving power generation efficiency.

[0064] 3) A flexible arrangement of multiple activation devices and multiple high-temperature fuel nozzles is adopted on the rear wall of the boiler furnace or the rear wall and the left and right side walls. On the one hand, by arranging multiple high-temperature fuel nozzles along the width or depth of the furnace, the uniformity of gas-solid flow and heat load distribution in the furnace cross section is ensured, thereby improving the uniformity of temperature distribution and hydrodynamics in the large-scale furnace cross section, and ensuring the hydrodynamic safety and heating surface safety under deep boiler adjustment.

[0065] 4) Regarding full-load peak shaving of the boiler, the flexible arrangement and corresponding operation strategies of multiple activation devices and high-temperature fuel nozzles in the furnace achieve flexible response, adjustment, and load variation. This allows the boiler to meet the load requirements of different load ranges from 2% to 100% during the boiler's load period, realizing flexible peak shaving across the entire load. During low-load periods, the fuel supply to the activation devices can be precisely controlled, ensuring stable boiler operation and avoiding problems such as flameout due to unstable combustion. During high-load periods, multiple activation devices work together to provide sufficient heat, ensuring efficient boiler operation. This flexible peak-shaving capability enables circulating fluidized bed boilers to better adapt to the complex and variable load demands of modern power systems, enhancing the overall flexibility and adaptability of the power generation system, helping to optimize the allocation of power resources, and improving the operating efficiency of the power system.

[0066] In summary, this utility model, through a series of technical improvements, enhances the flexibility of circulating fluidized bed boilers from multiple dimensions, providing strong technical support for flexible, efficient, stable, and economical operation of new power systems.

[0067] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that variations may be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A circulating fluidized bed boiler, comprising: Furnace chamber, separator, return feeder; the furnace chamber is equipped with a screen-type heating surface. Its characteristic is that it further includes: At least one activation device, wherein the activator and fuel are adapted to be introduced into the activation chamber of the activation device, and the fuel entering the activation device is adapted to be activated in the activation chamber to generate gas-solid fuel, wherein the rated heat capacity of a single activation device is 2%-15% of the rated heat capacity of the circulating fluidized bed boiler; The rear wall of the furnace, or the rear wall and the two side walls, are provided with fuel nozzles located below the furnace screen-type heating surface.

2. The boiler according to claim 1, characterized in that: The fuel nozzle includes a rear wall fuel nozzle located on the rear wall of the furnace. The at least one activation device includes a rear wall activation device, wherein the gas-solid fuel outlet of the rear wall activation device is connected to the rear wall fuel nozzle.

3. The boiler according to claim 2, characterized in that: The at least one activation device includes two rear wall activation devices with the same heat load, and the total heat load of the two rear wall activation devices is 5% to 15% of the boiler's rated load.

4. The boiler according to claim 2, characterized in that: The fuel nozzles on the rear wall are arranged symmetrically and uniformly along the width of the furnace.

5. The boiler according to claim 2, characterized in that: The at least one activation device includes a left wall activation device and a right wall activation device with the same heat load, and a rear wall activation device; The sidewall of the furnace is provided with a sidewall fuel nozzle that is connected to the gas-solid fuel outlet of the left and right wall activation devices; The heat load of the rear wall activation device is 2% to 10% of the boiler's rated load, and the total heat load of the left and right wall activation devices is 10% to 30% of the boiler's rated load.

6. The boiler according to claim 5, characterized in that: The fuel nozzles include sidewall fuel nozzles arranged on the left and right walls of the furnace, and the sidewall fuel nozzles are uniformly and symmetrically arranged along the sidewalls in the depth direction of the furnace.

7. The boiler according to claim 1, characterized in that: A single activation device is connected to 2-4 fuel nozzles simultaneously.

8. The boiler according to claim 1, characterized in that: The boiler also includes a monitoring device and a control device. The monitoring device is adapted to monitor at least one of the following in real time: steam temperature, steam pressure, bed temperature in the furnace, and temperature and pressure of the activation device. The control device is adapted to automatically adjust the fuel supply to the activation device.

9. The boiler according to claim 1, characterized in that: The activation device is a circulating fluidized bed.

10. The boiler according to claim 1, characterized in that: The boiler also includes a control device, which is configured to activate at least one activation device to introduce the gaseous fuel from the gaseous fuel outlet of the activation device into the fuel nozzle during the following processes: when the boiler is in a hot standby state, or during the process of increasing the boiler load from the hot standby state to 15% of the boiler's rated load, or during the process of increasing the boiler load from 15% of the boiler's rated load to 30% of the boiler's rated load, or during the process of increasing the boiler load from 30% of the boiler's rated load to 100% of the boiler's rated load, or during the boiler's start-up from the hot standby state.

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