Circulating fluidized bed boiler bed material adding system and working method

Abstract

This invention provides a circulating fluidized bed boiler bottom material addition system and its working method, comprising: multiple circulating fluidized bed boilers, a movable screw conveyor, and a hot slag direct delivery channel; a slag cooler and a chain bucket slag conveyor are arranged below the circulating fluidized bed boilers; a turning chamber is provided at the material discharge position of the chain bucket slag conveyor; the movable screw conveyor is telescopically arranged outside the turning chamber via guide rails and pneumatic push rods; the hot slag direct delivery channel includes a first screw conveyor, a bucket elevator, a second screw conveyor, a buffer tank, and a chute connected in sequence, the chute connecting the buffer tank and the biomass boiler; the discharge port of the movable screw conveyor is connected to the inlet of the first screw conveyor. This invention solves the problems of existing technologies that cannot fully utilize the waste heat of hot slag, flexibly schedule hot slag, and accurately control the addition of biomass boiler bottom material.

Description

Technical Field

[0001] This invention belongs to the field of fluidized bed boiler technology, specifically relating to a bottom material addition system and its working method for a circulating fluidized bed boiler. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Biomass boilers are key equipment for renewable energy utilization, and their stable operation is crucial. During boiler start-up or when burning low-calorific-value fuels, high-temperature ash needs to be added to the furnace to maintain fluidization and heat storage. Currently, replenishing ash for biomass boilers mainly relies on manual addition or traditional mechanical conveying systems, which are clearly insufficient. Existing technology involves cooling hot ash discharged from adjacent boilers to below 80°C using a ash cooler, and then transporting it over long distances to an ash bin for storage via a chain bucket conveyor and steep-angle belt conveyor. When the biomass boiler needs ash, the cooled ash is then transferred from the ash bin to the furnace for addition.

[0004] However, the existing technology follows a "cool first, store later, then transfer" approach. During this process, a large amount of sensible heat contained in the hot slag is forcibly cooled and lost. Furthermore, when the boiler needs bottom material, additional energy is required to heat the cold slag, resulting in a double waste of energy. This model requires a long transport path, has a slow response time for bottom material replenishment, lacks flexibility, cannot quickly utilize the hot slag resources discharged from adjacent furnaces, and struggles to meet the different operating conditions of replenishing bottom material during normal operation and adding large amounts of bed material before start-up, making it impossible to share resources among multiple furnaces. In addition, the existing technology mainly relies on manual addition, which is not only inefficient but also poses a risk of burns from the high-temperature slag. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a circulating fluidized bed boiler bottom material addition system and working method, which solves the problems of existing technologies being unable to fully utilize the waste heat of hot slag, flexibly schedule the hot slag, and precisely control the addition of biomass boiler bottom material.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides a circulating fluidized bed boiler bottom material addition system, comprising: multiple circulating fluidized bed boilers, a movable screw conveyor, and a hot slag direct delivery channel; a slag cooler and a chain bucket slag conveyor are provided below the circulating fluidized bed boilers; a turning chamber is provided at the material discharge station of the chain bucket slag conveyor; the movable screw conveyor is telescopically mounted on the outside of the turning chamber via guide rails and pneumatic push rods, and is pushed into the turning chamber by the pneumatic push rods to receive slag when bottom material replenishment is required, and withdraws when slag conveying stops; the upper feed port of the movable screw conveyor receives the slag falling from the turning chamber in the advancing state; The hot slag direct delivery channel includes a first screw conveyor, a bucket elevator, a second screw conveyor, a buffer tank, and a chute connected in sequence. The chute is used to connect the buffer tank and the biomass boiler. The discharge port of the movable screw conveyor is connected to the inlet of the first screw conveyor.

[0007] As a further implementation, a slag bin is also included, and an inclined conveyor belt is provided between the slag bin and the turning chamber. The inclination angle of the inclined conveyor belt is set according to the actual position between the slag bin and the turning chamber.

[0008] As a further implementation, there are multiple chutes, each equipped with a rotary feeder; the inlet end of the chute is connected to the buffer tank, and the outlet end of the chute is connected to the biomass boiler.

[0009] Secondly, the present invention also provides a method for operating a circulating fluidized bed boiler bottom material addition system, comprising the following steps: S1. When bottom material needs to be replenished, the movable screw conveyor is pushed into the turning chamber by the pneumatic push rod, so that its feed port is located below the discharge position of the chain bucket slag conveyor. S2. Establish a direct delivery channel: Start the rotary feeder, the second screw conveyor, the bucket elevator, the first screw conveyor and the movable screw conveyor in sequence to form a continuous material channel from the turning chamber to the biomass boiler; S3. Start the chain bucket slag conveyor and cold slag conveyor of the adjacent furnace, so that the hot slag falls from the turning chamber into the movable screw conveyor, and is transported to the biomass boiler furnace through the hot slag direct conveying channel within a set time. Adjust the speed or opening of the rotary feeder on the chute to control the amount of bottom material entering the biomass boiler in real time and with precision. S4. When stopping the bottom material replenishment, shut down the cold slag machine, chain bucket slag conveyor, movable screw conveyor, first screw conveyor, bucket elevator, second screw conveyor and rotary feeder in sequence, and use the pneumatic push rod to remove the movable screw conveyor from the turning chamber.

[0010] As a further implementation, the rotary feeder, the second screw conveyor, the bucket elevator, the first screw conveyor and the movable screw conveyor in step S2 are started in a forward-delayed start-up manner in the opposite direction of material flow, and the start-up time interval between adjacent devices is set to a certain duration.

[0011] As a further implementation, in step S4, the equipment is stopped by sequential control and delayed shutdown in the direction of material flow. First, the cold slag machine is stopped, and then the chain bucket slag conveyor is stopped after the material in the chain bucket slag conveyor is emptied. Then, the movable screw conveyor, the first screw conveyor, the bucket elevator, the second screw conveyor and the rotary feeder are shut down in sequence, and the start-up time interval between adjacent equipment is set to a certain duration.

[0012] As a further implementation, the system can be applied to multiple circulating fluidized bed boilers simultaneously through the cooperation of the turning chamber and the chain bucket slag conveyor; the turning chamber of each circulating fluidized bed boiler is cooperated with the movable screw conveyor or is respectively equipped with a corresponding feed inlet.

[0013] As a further implementation, the system also includes an emergency stop safety circuit; when the emergency stop safety circuit triggers the emergency stop button, it only cuts off the power source of the newly added direct delivery channels, namely the first screw conveyor, bucket elevator, second screw conveyor, movable screw conveyor and rotary feeder, while the original slag cooler and chain bucket slag conveyor of the adjacent furnace remain in operation or stop according to the original procedure.

[0014] As a further implementation, the working method also includes an emergency handling step: when a fault occurs during system operation, the emergency stop button is immediately triggered. The emergency stop safety strategy, after the fault is cleared and reset, involves manually emptying the accumulated residue in the channel and then re-executing steps S1 to S4.

[0015] As a further implementation, the system control method includes PLC automatic control mode and manual debugging mode.

[0016] Compared with the prior art, the advantages and positive effects of this invention are: The circulating fluidized bed boiler of this invention is equipped with a slag cooler and a chain bucket slag conveyor below it; a turning chamber is provided at the material discharge position of the chain bucket slag conveyor; the movable screw conveyor has a drawer-type structure and is telescopically mounted on the outside of the turning chamber via guide rails and pneumatic push rods. When there are multiple circulating fluidized bed boilers, slag can be flexibly taken from any circulating fluidized bed boiler. When bottom material replenishment is required, it is pushed into the turning chamber by the pneumatic push rod to receive slag, and it exits when slag conveying stops, without changing the running trajectory of the chain bucket slag conveyor, thus realizing the exchange of hot slag between the original system and the new system. The system allows for flexible switching between systems, avoiding interference with the original slag conveying path. The upper feed inlet of the movable screw conveyor receives slag falling from the turning chamber during its advancing state. The hot slag direct delivery channel includes a first screw conveyor, a bucket elevator, a second screw conveyor, a buffer tank, and a chute connected in sequence. The chute connects the buffer tank and the biomass boiler. The discharge port of the movable screw conveyor connects to the feed inlet of the first screw conveyor, eliminating the need for manual handling and unloading of high-temperature slag, completely changing the outdated method of manually adding bottom material. The system can be started and stopped with a single button, allowing materials to be transferred from adjacent furnaces to the target boiler in a short time, improving the efficiency of bottom material replenishment and eliminating safety hazards associated with high-temperature operations. The buffer tank is equipped with an insulation layer to maintain the physical heat of the hot slag during its short-term storage, preventing rapid heat loss that could lead to condensation on the tank wall or cooling of the bottom material, ensuring thermal efficiency when entering the furnace.

[0017] The system of this invention also includes a slag bin, and an inclined conveyor belt is provided between the slag bin and the turning chamber. The inclination angle of the inclined conveyor belt is set according to the actual position between the slag bin and the turning chamber. Hot slag is discharged from the adjacent furnace slag cooler. Part of it is connected to the direct conveying channel via a movable screw conveyor and enters the biomass boiler furnace. The other part, when it is not necessary to replenish the bottom material to the biomass boiler, is in a retracted state under the action of a pneumatic pusher, located outside the turning chamber. At this time, the hot slag discharged from the circulating fluidized bed boiler follows the original path: after being cooled by the slag cooler, it is transported to the turning chamber by a chain bucket slag conveyor, then falls onto the steeply inclined belt, and finally collects in the slag bin. Compared with existing bottom material addition equipment, directly conveying hot slag to the biomass boiler furnace significantly shortens the slag transfer path, reduces the heat radiation and convective heat loss of hot slag during the transportation process, achieves energy saving, and maintains the initial temperature of the bottom material. Attached Figure Description

[0018] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0019] Figure 1 This is a diagram of a radiant heating / cooling system with refrigerant state regulation function according to the present invention.

[0020] In the diagram: 1. Slag cooler; 2. Chain bucket slag conveyor; 3. Mobile screw conveyor; 4. Turning chamber; 5. Inclined conveyor belt; 6. First screw conveyor; 7. Bucket elevator; 8. Second screw conveyor; 9. Buffer tank; 10. Chute; 11. Rotary feeder; 12. Biomass boiler; 13. Slag bin; 14. Circulating fluidized bed boiler. Detailed Implementation

[0021] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. Circulating fluidized bed boiler: The circulating fluidized bed boiler adopts fluidized combustion and its main structure includes two parts: the combustion chamber (including dense phase zone and dilute phase zone) and the circulation loop (including high temperature gas-solid separator and return system).

[0023] Bottom material addition: Adding specific materials to the bottom of the furnace to optimize combustion efficiency, reduce slagging, or treat slag.

[0024] Slag cooler: A slag cooler (also known as a slag cooler) is an industrial device used in coal-fired boiler systems to process high-temperature slag.

[0025] Large angle belt: It is a special conveyor belt used for conveying materials at large angles (0°-90°). It consists of a base belt, corrugated sidewalls and cross diaphragms, which form a "bucket" structure to prevent materials from slipping.

[0026] Chain bucket conveyor: Buckets transport materials horizontally or inclined along a track (angle ≤ 60°). A spring-loaded helical tensioning device automatically adjusts the chain tension. Suitable for high-temperature, high-abrasion materials (such as cement clinker and coke).

[0027] Bucket elevator (chain bucket elevator): vertically conveys powdery / granular materials (height ≤ 60 meters), using Z-type or S-type buckets to adapt to different materials (e.g., Z-type for wet sand, S-type for coal lumps), with explosion-proof cylinder design.

[0028] A screw conveyor is a machine that uses a motor to drive a rotating screw to push materials to achieve the purpose of conveying. It can convey materials horizontally, inclined, or vertically, and has advantages such as simple structure, small cross-sectional area, good sealing, convenient operation, easy maintenance, and suitability for enclosed transportation. Screw conveyors are divided into two types in terms of conveying form: shafted screw conveyors and shaftless screw conveyors; and in terms of shape, they are divided into U-shaped screw conveyors and tubular screw conveyors.

[0029] Rotary feeder: A rotary feeder, also known as a rotary valve, star feeder, or airlock, is a device whose structure consists of a rotor with several blades rotating inside a cylindrical casing. Material falls from the upper hopper, filling the spaces between the blades, and is discharged as the blades rotate to the lower part. A pressure-equalizing exhaust port is located on the side of the machine to discharge the high-pressure gas brought in by the impeller's rotation, reducing gas backing and facilitating the smooth descent of the material. For pressure-feeding and suction-feeding pneumatic conveying systems, the rotary feeder is a key component. It can feed material into the feed pipe evenly and continuously. In the system's separation and dust collection sections, it also functions as a discharger and airlock.

[0030] Example 1 This embodiment provides a circulating fluidized bed boiler bottom material addition system, such as... Figure 1As shown, the system includes: multiple circulating fluidized bed boilers 14, a movable screw conveyor 3, and a hot slag direct delivery channel; a slag cooler 1 and a chain bucket slag conveyor 2 are installed below the circulating fluidized bed boilers 14; a turning chamber 4 is installed at the material discharge position of the chain bucket slag conveyor 2; the movable screw conveyor 3 has a drawer-type structure and is telescopically installed on the outside of the turning chamber 4 via guide rails and pneumatic push rods. When bottom material needs to be replenished, it is pushed into the turning chamber 4 by the pneumatic push rod to receive slag, and it exits when slag conveying stops, without changing the running trajectory of the chain bucket slag conveyor 2, realizing flexible switching of hot slag between the original system and the new system, and avoiding interference with the original slag conveying path; the upper feed port of the movable screw conveyor 3 receives the slag falling from the turning chamber 4 in the advancing state; The hot slag direct delivery channel includes a first screw conveyor 6, a bucket elevator 7, a second screw conveyor 8, a buffer tank 9, and a chute 10 connected in sequence. The chute 10 connects the buffer tank 9 and the biomass boiler 12. The discharge port of the movable screw conveyor 3 is connected to the inlet of the first screw conveyor 6. The buffer tank 9 is equipped with an insulation layer to maintain the physical heat of the hot slag during the short-term storage period, preventing rapid heat loss that could lead to condensation on the tank wall or cooling of the bottom material, thus ensuring thermal efficiency when entering the furnace.

[0031] As a further implementation, a slag bin 13 is also included, with an inclined conveyor belt 5 installed between the slag bin 13 and the turning chamber 4. The inclination angle of the inclined conveyor belt 5 is set according to the actual position between the slag bin 13 and the turning chamber 4. Hot slag is discharged from the adjacent furnace cold slag machine 1. Part of it is connected to the direct conveying channel via the movable screw conveyor 3 and enters the furnace of the biomass boiler 12, taking about 3-5 minutes. The other part is conveyed to the slag bin 13 via the inclined conveyor belt 5 for storage. Compared with the existing bottom material addition equipment, directly conveying the hot slag to the furnace of the biomass boiler 12 significantly shortens the slag transfer path, reduces the heat radiation and convective heat loss of the hot slag during the transportation process, achieves energy saving, and maintains the initial temperature of the bottom material.

[0032] As a further implementation, there are multiple chutes 10, each equipped with a rotary feeder 11; the inlet end of each chute 10 is connected to the buffer tank 9, and the outlet end of each chute 10 is connected to the biomass boiler 12. The purpose is to achieve quantitative and precise control of the addition of bed material to the biomass boiler 12 by controlling the rotational speed or opening degree of the rotary feeder 11, thus meeting the particle size distribution requirements of the bed material under different operating conditions.

[0033] Example 2 This embodiment provides a method for operating a bottom material addition system for a circulating fluidized bed boiler 14, including the following steps: S1. When bottom material needs to be replenished, the movable screw conveyor 3 is pushed into the turning chamber 4 by the pneumatic push rod, so that its feed port is located below the material dropping position of the chain bucket slag conveyor 2. S2. Establish a direct delivery channel: Start the rotary feeder 11, the second screw conveyor 8, the bucket elevator 7, the first screw conveyor 6 and the movable screw conveyor 3 in sequence to form a continuous material channel from the turning chamber 4 to the biomass boiler 12. S3. Start the chain bucket slag conveyor 2 and cold slag conveyor 1 of the adjacent furnace, so that the hot slag falls from the turning chamber 4 into the movable screw conveyor 3, and is transported to the furnace of the biomass boiler 12 through the hot slag direct conveying channel within a set time. Adjust the speed or opening of the rotary feeder 11 on the chute 10 to control the amount of bottom material entering the biomass boiler 12 in real time and with precision. S4. When stopping the bottom material replenishment, shut down the cold slag machine 1, chain bucket slag conveyor 2, movable screw conveyor 3, first screw conveyor 6, bucket elevator 7, second screw conveyor 8 and rotary feeder 11 in sequence, and use the pneumatic push rod to remove the movable screw conveyor 3 from the turning chamber 4.

[0034] As a further implementation, in step S2, the rotary feeder 11, the second screw conveyor 8, the bucket elevator 7, the first screw conveyor 6, and the movable screw conveyor 3 are started using a forward-delayed start method in the opposite direction of material flow, with a set time interval between the start-up of adjacent equipment. This prevents material from accumulating or blocking inside the rotary feeder 11, the second screw conveyor 8, the bucket elevator 7, the first screw conveyor 6, and the movable screw conveyor 3 during the start-up process.

[0035] As a further implementation, in step S4, the equipment is stopped by sequential delayed shutdown in the direction of material flow. First, the slag cooler 1 is stopped, and then the chain bucket slag conveyor 2 is stopped after the material is emptied. Then, the movable screw conveyor 3, the first screw conveyor 6, the bucket elevator 7, the second screw conveyor 8, and the rotary feeder 11 are shut down in sequence. The start-up time interval between adjacent equipment is set to a certain duration. This ensures that the material in the conveying channel is completely emptied, avoiding equipment shutdown under load and material caking after cooling.

[0036] As a further implementation, the system can be applied to multiple circulating fluidized bed boilers 14 simultaneously through the cooperation of the turning chamber 4 and the chain bucket slag conveyor 2; the turning chamber 4 of each circulating fluidized bed boiler 14 is cooperated with the movable screw conveyor 3 or is respectively equipped with a corresponding feed inlet.

[0037] As a further implementation, the system also includes an emergency stop safety circuit; when the emergency stop safety circuit triggers the emergency stop button, it only cuts off the power source of the newly added direct delivery channels, namely the first screw conveyor 6, bucket elevator 7, second screw conveyor 8, movable screw conveyor 3 and rotary feeder 11, while the original slag cooler 1 and chain bucket slag conveyor 2 remain in operation or stop according to the original procedure, to prevent the original equipment from being forced to shut down due to the failure of the bottom material replenishment system.

[0038] As a further implementation, the working method also includes an emergency handling step: when a fault occurs during system operation, the emergency stop button is immediately triggered. The emergency stop safety strategy, after the fault is cleared and reset, involves manually emptying the accumulated residue in the channel and then re-executing steps S1 to S4.

[0039] As a further implementation, the system control method includes PLC automatic control mode and manual debugging mode, supporting two operation modes: one-button automatic start / stop and manual single-machine debugging.

[0040] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A circulating fluidized bed boiler bottom material addition system, characterized in that, include: The system includes multiple circulating fluidized bed boilers, a movable screw conveyor, and a hot slag direct delivery channel. A slag cooler and a chain bucket slag conveyor are located below the circulating fluidized bed boilers. A turning chamber is located at the material discharge station of the chain bucket slag conveyor. The movable screw conveyor is telescopically mounted outside the turning chamber via guide rails and pneumatic push rods. When bottom material replenishment is needed, it is pushed into the turning chamber by the pneumatic push rods to receive slag. When slag delivery stops, it retracts. The upper feed inlet of the movable screw conveyor receives the slag falling from the turning chamber during the advancing state. The hot slag direct delivery channel includes a first screw conveyor, a bucket elevator, a second screw conveyor, a buffer tank, and a chute connected in sequence. The chute is used to connect the buffer tank and the biomass boiler. The discharge port of the movable screw conveyor is connected to the inlet of the first screw conveyor.

2. The circulating fluidized bed boiler bottom material addition system as described in claim 1, characterized in that, It also includes a slag bin, and an inclined conveyor belt is provided between the slag bin and the turning chamber. The inclination angle of the inclined conveyor belt is set according to the actual position between the slag bin and the turning chamber.

3. The circulating fluidized bed boiler bottom material addition system as described in claim 1, characterized in that, There are multiple chutes, and each chute is equipped with a rotary feeder; the inlet end of the chute is connected to the buffer tank, and the outlet end of the chute is connected to the biomass boiler.

4. A method for operating the bottom feed addition system of a circulating fluidized bed boiler according to any one of claims 1-3, characterized in that, Includes the following steps: S1. When bottom material needs to be replenished, the movable screw conveyor is pushed into the turning chamber by the pneumatic push rod, so that its feed port is located below the discharge position of the chain bucket slag conveyor. S2. Establish a direct delivery channel: Start the rotary feeder, the second screw conveyor, the bucket elevator, the first screw conveyor and the movable screw conveyor in sequence to form a continuous material channel from the turning chamber to the biomass boiler; S3. Start the chain bucket slag conveyor and cold slag conveyor of the adjacent furnace, so that the hot slag falls from the turning chamber into the movable screw conveyor, and is transported to the biomass boiler furnace through the hot slag direct conveying channel within a set time. Adjust the speed or opening of the rotary feeder on the chute to control the amount of bottom material entering the biomass boiler in real time and with precision. S4. When stopping the bottom material replenishment, shut down the cold slag machine, chain bucket slag conveyor, movable screw conveyor, first screw conveyor, bucket elevator, second screw conveyor and rotary feeder in sequence, and use the pneumatic push rod to remove the movable screw conveyor from the turning chamber.

5. The working method as described in claim 4, characterized in that, In step S2, the rotary feeder, the second screw conveyor, the bucket elevator, the first screw conveyor, and the movable screw conveyor are started using a forward-delayed start method in the opposite direction of the material flow, and the start time interval between adjacent devices is set to a certain duration.

6. The working method as described in claim 4, characterized in that, In step S4, the equipment is stopped by sequential control and delayed shutdown in the direction of material flow. First, the cold slag machine is stopped, and then the chain bucket slag conveyor is stopped after the material in the chain bucket slag conveyor is emptied. Then, the movable screw conveyor, the first screw conveyor, the bucket elevator, the second screw conveyor and the rotary feeder are shut down in sequence. The start-up time interval between adjacent equipment is set to a certain duration.

7. The working method as described in claim 5, characterized in that, The system, through the cooperation of the turning chamber and the chain bucket slag conveyor, can be applied to multiple circulating fluidized bed boilers simultaneously; the turning chamber of each circulating fluidized bed boiler is cooperated with the movable screw conveyor or is respectively equipped with a corresponding feed inlet.

8. The working method as described in claim 5, characterized in that, The system also includes an emergency stop safety circuit; when the emergency stop safety circuit triggers the emergency stop button, it only cuts off the power source of the newly added direct delivery channels, namely the first screw conveyor, bucket elevator, second screw conveyor, movable screw conveyor and rotary feeder, while the original slag cooler and chain bucket slag conveyor of the adjacent furnace remain in operation or stop according to the original procedure.

9. The working method as described in claim 8, characterized in that, The working method also includes an emergency handling step: when a fault occurs during system operation, the emergency stop button is immediately triggered. The emergency stop safety strategy, after the fault is cleared and reset, involves manually emptying the accumulated residue in the channel and then re-executing steps S1 to S4.

10. The working method as described in claim 5, characterized in that, The system control methods include PLC automatic control mode and manual debugging mode.

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