Circulating fluidized bed boiler with high-temperature separation function

Abstract

The utility model relates to the technical field of fluidized bed boilers, and discloses a circulating fluidized bed boiler with a high-temperature separation function, which comprises a hearth, a boiler barrel device, an air distribution device, a separator, a return feeder and a tail flue, the separator adopts a high-temperature cyclone separator design, an inlet of the separator is in an inclined and tapered form, a central barrel is arranged at the top of the separator, and the tail flue is arranged in the central barrel. An inlet is formed in the left side of the separator. According to the utility model, by optimizing the design of the high-temperature cyclone separator, the separation efficiency is improved to more than 99.5%, the fine ash share is increased, the flow rate of a flue gas inlet is effectively improved, the speed of external swirling air flow is increased, and the air flow field is optimized, so that the separation efficiency is obviously improved; according to the bell jar type coal-leakage-free air cap, through multi-dimensional innovation and optimization of the structure, the material, the air distribution performance, the maintainability and the like, the operation efficiency and stability of the boiler are remarkably improved, meanwhile, the maintenance requirement is reduced, and a guarantee is provided for safe and efficient operation of the circulating fluidized bed boiler.

Description

Technical Field

[0001] This utility model relates to the field of fluidized bed boiler technology, specifically a circulating fluidized bed boiler with high-temperature separation function. Background Technology

[0002] Circulating fluidized bed (CFB) combustion technology, as a highly efficient and low-pollution clean coal combustion technology, is characterized by a large amount of material contained in the boiler furnace. During combustion, the material is carried by the flue gas to the upper part of the furnace and undergoes gas-solid separation through a separator. The separated material is then returned to the furnace via a non-mechanical return valve for multiple cycles of combustion. This design gives CFB boilers significant advantages such as wide fuel adaptability, excellent environmental performance, a wide load adjustment range, and easy comprehensive utilization of ash and slag. However, the combustion system of a CFB boiler differs significantly from that of a traditional boiler. It mainly consists of a furnace, a separator, and a return feeder, with the separator being the core component, responsible for the crucial gas-solid separation function. Current CFB boilers require a high level of automation and have a complex system structure. They not only require specialized equipment such as separators and return feeders but also increase initial investment costs due to their large size. Furthermore, the high-speed flow of material causes severe erosion of the furnace heating surfaces, separators, and return feeders, leading to significant wear and tear, which substantially increases maintenance workload and operating costs.

[0003] Existing separators still have shortcomings in gas-solid separation efficiency, especially under high-temperature conditions, where the separation effect is difficult to meet the requirements of high-efficiency operation, thus affecting the overall performance of the boiler. At the same time, the design of the return feeder also faces problems such as uneven air distribution, easy coal leakage, and inconvenient maintenance, which further limits the stability and economy of boiler operation.

[0004] To address the aforementioned issues, a circulating fluidized bed boiler with high-temperature separation function is proposed. Utility Model Content

[0005] The purpose of this invention is to provide a circulating fluidized bed boiler with high-temperature separation function, which solves the problems of separation efficiency, combustion efficiency and operational stability of circulating fluidized bed boilers in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a circulating fluidized bed boiler with high-temperature separation function, including a furnace, a boiler drum device, an air distribution device, a separator, a return feeder, and a tail flue. The separator adopts a high-temperature cyclone separator design, with its inlet being inclined and gradually narrowing. A central cylinder is provided at the top of the separator.

[0007] By adopting the above technical solution, a flow meter, a pressure gauge, and an air volume regulating valve are installed on the inlet duct header, with an air volume regulation range of 0.5m. 3 / min to 5m3 / min, achieving precise airflow control. The air distribution plate of the return material is equipped with an ash discharge pipe with a diameter of 50mm to 80mm for easy ash and slag discharge.

[0008] As a further description of the above technical solution: the separator has an inlet on the left side, the angle of the inlet is in the range of 8° to 15°, the tapering ratio is 1:2 to 1:4, and the inlet flow velocity is increased to more than 25m / s.

[0009] By adopting the above technical solution, the separator and return feeder are designed with a shell and a multi-layer refractory lining. The inner wall is made of high-strength wear-resistant refractory castable with a thickness of 50mm to 80mm, directly bearing the erosion of materials; the middle layer is made of lightweight castable with a thickness of 30mm to 50mm, achieving thermal insulation; the outer layer is a composite thermal insulation barrier composed of insulating bricks and aluminum silicate fiber with a thickness of 20mm to 40mm, forming a progressively advanced thermal protection system.

[0010] As a further description of the above technical solution: the bottom of the separator is divided into a straight section and a conical section.

[0011] By adopting the above technical solution, the weight of the straight section, conical section, material leg, and return feeder of the separator is all supported by a steel frame. The return feeder is suspended from the lower part of the separator and fixed by auxiliary suspension rods suspended from the boiler steel frame. The weight of the furnace inlet section of the return feed pipe is jointly supported by the furnace water-cooled wall and the steel frame, which is coordinated with the overall suspension structure of the furnace.

[0012] As a further description of the above technical solution: an air distribution device is provided inside the bottom of the furnace.

[0013] By adopting the above technical solution, the air volume adjustment range is 0.5m. 3 / min to 5m 3 / min. The air distribution plate of the return feeder 5 is equipped with an ash discharge pipe with a diameter of 50mm to 80mm to facilitate ash and slag discharge.

[0014] As a further description of the above technical solution: a boiler drum device is fixedly connected to the top of the furnace, and a pipe is fixedly connected to the outer wall of the boiler drum device, and the pipe is fixed to the outer wall of the tail flue.

[0015] The water inside the pipe is heated by adopting the above technical solution.

[0016] As a further description of the above technical solution: the central cylinder adopts an offset layout; the bottom of the return feeder is equipped with a bell-shaped non-leaking air cap.

[0017] By adopting the above technical solution, the wind cap is made of high-temperature alloy steel, such as ZG4Cr26Ni4Mn3NRE or 0gr25ni20. This material has excellent wear resistance, oxidation resistance and corrosion resistance under 900℃ conditions, ensuring long-term stable operation. The wind cap and the connecting pipe are connected by thread or groove, which is convenient for replacement and maintenance without damaging the refractory material, saving maintenance time and cost. A bell-shaped non-leaking wind cap is used to transport high-pressure return material cold air.

[0018] As a further description of the above technical solution: the bottom of the straight section and the conical section of the separator are provided with separator material legs, and the separator material legs are located at the top of the return feeder, and the bottom of the return feeder is provided with return material legs.

[0019] By adopting the above technical solution, a return feeder 5 is equipped at the lower part of each separator leg 45. High-pressure cold air is used as the return air, which is sent into the return device 51 through a bell-shaped non-leaking air cap 53. The flow rate of the return air is precisely controlled by the flow meter, pressure gauge and air volume regulating valve on the inlet air duct header.

[0020] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0021] 1. The circulating fluidized bed boiler with high-temperature separation function provided by this utility model firstly improves the separation efficiency to over 99.5% by optimizing the design of the high-temperature cyclone separator, increasing the fine ash content, effectively improving the flue gas inlet velocity, increasing the external cyclone airflow velocity, and optimizing the airflow field, thereby achieving a significant improvement in separation efficiency.

[0022] 2. The circulating fluidized bed boiler with high-temperature separation function provided by this utility model significantly improves the operating efficiency and stability of the boiler through multi-dimensional innovation and optimization in structure, materials, air distribution performance and maintainability by using a bell-shaped non-leaking air cap. At the same time, it reduces maintenance requirements and provides a guarantee for the safe and efficient operation of the circulating fluidized bed boiler.

[0023] 3. The circulating fluidized bed boiler with high-temperature separation function provided by this utility model significantly improves the boiler's separation efficiency, combustion efficiency, and operational stability through the optimized design of the high-temperature cyclone separator and the bell-shaped non-leaking air cap. At the same time, it reduces coal consumption, electricity consumption, and wear, resulting in significant economic benefits and environmental value. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0025] Figure 2 This is a schematic diagram of the inclined and gradually narrowing flue gas inlet structure of the separator of this utility model.

[0026] Figure 3This is a schematic diagram of the separator material leg of this utility model.

[0027] In the diagram: 1. Furnace; 2. Boiler drum assembly; 3. Inlet; 4. Flue gas inlet; 5. Central cylinder; 6. Separator; 7. Straight and conical sections of the separator; 8. Tail flue; 9. Pipeline; 10. Separator material leg; 11. Return feeder; 12. Bell-shaped non-leaking vent cap; 13. Return feeder; 14. Air distribution device. Detailed Implementation

[0028] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0029] To further understand the contents of this utility model, a detailed description of this utility model will be provided with reference to the accompanying drawings.

[0030] Reference Figures 1-3 This utility model discloses a circulating fluidized bed boiler with high-temperature separation function, comprising a furnace 1, a boiler drum 2, an air distribution device 3, a separator 6, a return feeder 11, and a tail flue 8. The separator 6 and the return feeder 11 are the core components. The separator 6 is used to achieve gas-solid separation, and the return feeder 11 is used to return the separated material to the furnace 1 for circulating combustion. The separator 6 adopts a high-temperature cyclone separator design, with an inclined, tapering inlet and an offset layout for the central cylinder 5. The return feeder 11 is equipped with a bell-shaped leak-proof air cap 12, and its structure, materials, and air distribution uniformity have all been optimized.

[0031] The separator 6 consists of a flue gas inlet 4, a straight section and a conical section 7, a central cylinder 5, a gas inlet 3, and a material leg 10. The flue gas inlet 4 features an inclined, tapered design with an inlet angle ranging from 8° to 15° and a tapering ratio of 1:2 to 1:4. Through these parameter optimizations, the flue gas inlet velocity is increased to over 25 m / s, allowing the circulating material to enter the separator 6 tangentially against the wall. The downward-sloping flue gas inlet design applies an oblique force to the material, promoting tighter adhesion to the separator's inner wall, thereby increasing the external swirling airflow velocity and reducing eddies and backflow. The central cylinder 6 employs an offset design, with an offset distance from the axis of 1 / 8 to 1 / 4 of its diameter, preventing short-circuiting of the central airflow. This design guides the airflow to a uniform distribution, reducing the likelihood of airflow passing directly through the central region without sufficient mixing and heat exchange, thus improving the overall system's separation efficiency. Tests have shown that separator 6 has a separation efficiency of over 99.5% and can capture particles larger than 30μm.

[0032] In actual operation, the flue gas in furnace 1, carrying a large amount of material, enters the separator flue gas inlet 4 from the furnace inlet. Within the separator 6, the material is thrown towards the outer wall by centrifugal force and flows downwards along the inner walls of the straight and conical sections 7 of the separator, ultimately entering the return feeder 11 through the separator material leg 10. The separated clean flue gas flows through the central cylinder 7 to the separator gas inlet 3 and then into the tail flue 8, completing the gas-solid separation process. The hot flue gas in the tail flue 8 heats the pipe 9 and is then recycled back into the boiler drum device 2. The optimized airflow field inside the separator 6 reduces eddies and backflow phenomena, ensuring airflow stability and further improving separation efficiency.

[0033] The return feeder 11 consists of a return device, return legs 10, and a bell-shaped leak-proof air cap 12. The bell-shaped leak-proof air cap 12 employs a unique structural design. The bottom of the air cap body tapers radially inward to form a positioning ring, the width of which is 1 / 10 to 1 / 8 of the air cap body diameter. This positioning ring connects to the flange on the connecting pipe via a slot. The top of the core tube is sealed and has multiple small holes with a diameter of 2mm to 5mm to ensure reasonable resistance and uniform airflow. The air cap openings are tilted downwards at 15° to prevent material from entering the air chamber and avoid coal leakage. The air cap is made of high-temperature alloy steel, such as ZG4Cr26Ni4Mn3NRE or 0gr25ni20. This material exhibits excellent wear resistance, oxidation resistance, and corrosion resistance at 900℃, ensuring long-term stable operation. The spacing between adjacent air caps is designed to be 1.5 to 2 times the diameter of the air cap to avoid head-on blowing and jet deflection, reduce wear, and ensure uniform airflow distribution within the boiler. Furthermore, the air caps are connected to the connecting pipes via threaded or grooved connections, facilitating replacement and maintenance without damaging the refractory material, thus saving maintenance time and costs.

[0034] In actual operation, each separator leg 10 is equipped with a return feeder 11 at its lower part, using high-pressure cold air as the return air, which is sent into the return device through a bell-shaped leak-proof air cap 12. The flow rate of the return air is precisely controlled by a flow meter, pressure gauge, and air volume regulating valve on the inlet duct header, with an air volume adjustment range of 0.5m³ / h. 3 / min to 5m 3 / min. The air distribution plate of the return feeder 5 is equipped with an ash discharge pipe with a diameter of 50mm to 80mm to facilitate ash and slag discharge. The return feeder 11 is suspended below the separator 6 and fixed to the boiler steel frame by auxiliary hanging rods. The weight of the part of the return feed pipe entering the furnace is supported by the furnace water-cooled wall and the steel frame, which is coordinated with the overall suspension structure of the furnace.

[0035] For the material separation and return system operating at approximately 900℃, the separator 6 and return feeder 11 employ a combined design of a shell and a multi-layered refractory lining. The inner wall uses high-strength, wear-resistant, refractory castable with a thickness of 50mm to 80mm to directly withstand material erosion; the middle layer uses lightweight castable with a thickness of 30mm to 50mm to provide thermal insulation; the outer layer consists of a composite thermal insulation barrier made of insulating bricks and aluminosilicate fibers with a thickness of 20mm to 40mm, forming a progressively layered thermal protection system. This multi-layered functional material combination alleviates thermal stress concentration through a gradient thermal resistance effect, ensuring long-term reliable operation of the equipment in high-temperature environments.

[0036] Working Principle: The high-temperature flue gas generated by the combustion of fuel in the furnace 2 carries a large amount of material and enters the separator flue gas inlet 4 from the furnace 1 inlet. Due to the inclined and tapered design of the separator flue gas inlet 4, the flue gas inlet velocity is significantly increased, and the material enters the separator 6 tangentially along the wall. The downward inclined flue gas inlet design applies an oblique force to the material, causing it to adhere more tightly to the inner wall of the separator 6, thereby increasing the velocity of the outer swirling airflow and reducing the occurrence of eddies and backflow. The offset design of the central cylinder 5 guides the airflow to be evenly distributed, avoiding the phenomenon of short-circuiting the central airflow and improving the overall separation efficiency of the system. After the airflow field inside the separator 6 is optimized, eddies and backflow phenomena are reduced, ensuring the stability of the airflow and further improving the separation efficiency. The material inside the separator 6 is thrown towards the outer wall under the action of centrifugal force and flows downward along the inner wall of the straight section and conical section 7 of the separator, and finally enters the return feeder 11 through the separator material leg 10. The separated clean flue gas flows through the central cylinder 5 to the separator gas inlet 3 and enters the tail flue 8 to complete the gas-solid separation process. The hot gas passes through the tail flue 8 and is heated by the pipe 9 on the outer wall. The heated water enters the boiler drum device 2. The return feeder 11 sends high-pressure cold air through the bell-shaped non-leaking air cap 12 to return the separated material to the furnace 1 for circulating combustion. The flow rate of the return air is precisely controlled by the flow meter, pressure gauge and air volume regulating valve on the inlet air duct header. The air distribution plate of the return feeder 11 is equipped with an ash discharge pipe. The return feeder 11 is suspended below the separator 6 and fixed to the boiler steel frame by auxiliary suspension rods. The weight of the part of the return pipe entering the furnace is supported by the furnace water-cooled wall and the steel frame, which is coordinated with the overall suspension structure of the furnace.

[0037] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0038] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can 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 with high temperature separation function, comprising a furnace (1), a boiler drum device (2), a wind distribution device (14), a separator (6), a return feeder (11) and a tail flue (8), characterized in that: The separator (6) adopts a high-temperature cyclone separator design, and its inlet is inclined and gradually narrowed. A central cylinder (5) is provided on the top of the separator (6).

2. The circulating fluidized bed boiler having a high-temperature separation function according to claim 1, characterized by: The separator (6) has an inlet (3) on its left side. The angle of the inlet (3) is between 8° and 15°, and the tapering ratio is between 1:2 and 1:

4. The flow rate of the inlet (3) is increased to more than 25 m / s.

3. The circulating fluidized bed boiler with high-temperature separation function according to claim 1, characterized in that: The bottom of the separator (6) is divided into a straight section and a conical section (7).

4. The circulating fluidized bed boiler with high-temperature separation function according to claim 1, characterized in that: An air distribution device (14) is installed inside the bottom of the furnace (1).

5. The circulating fluidized bed boiler with high-temperature separation function according to claim 1, characterized in that: The furnace (1) is fixedly connected to the top of the boiler drum device (2), and the outer wall of the boiler drum device (2) is fixedly connected to the pipe (9), and the pipe (9) is fixed to the outer wall of the tail flue (8).

6. The circulating fluidized bed boiler with high-temperature separation function according to claim 1, characterized in that: The central cylinder (5) adopts an offset layout; the bottom of the return feeder (11) is equipped with a bell-shaped non-leaking vent cap (12).

7. The circulating fluidized bed boiler with high-temperature separation function according to claim 3, characterized in that: The separator straight section and conical section (7) are provided with separator material legs (10) at the bottom, and the separator material legs (10) are provided at the top of the return feeder (11), and the return feeder (11) is provided with return material legs (13) at the bottom.

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