A cyclone separator for a biomass circulating fluidized bed boiler

Abstract

This utility model discloses a cyclone separator for a biomass circulating fluidized bed boiler, comprising a flue gas inlet section, a gas-solid two-phase separation section connected to the flue gas inlet section, a flue gas outlet section connected to the top and bottom of the gas-solid two-phase separation section respectively, and a solid return section. The solid return section includes multiple coaxially connected and fixedly connected solid return straight sections and multiple solid return conical sections, which are arranged at intervals in the vertical direction. Flue gas flows in from the flue gas inlet section, rotates along the inner wall of the gas-solid two-phase separation section, and achieves gas-solid two-phase separation through centrifugal force. The gas phase flows out through the flue gas outlet section, and the solid phase is returned from top to bottom through the solid return section. Through segmented and optimized solid return path and gas-solid separation flow field, the intermittent blockage problem caused by alkali metal adhesion in traditional cyclone separators is solved, avoiding forced boiler load reduction or shutdown. It is especially suitable for biomass combustion scenarios with complex fuel types and variable ash composition.

Description

Technical Field

[0001] This utility model relates to the technical field of biomass circulating fluidized bed boiler equipment, specifically to a cyclone separator for a biomass circulating fluidized bed boiler. Background Technology

[0002] The cyclone separators of existing biomass circulating fluidized bed boilers mostly refer to the appearance of traditional coal-fired boilers, adopting a single straight section and a single conical section, with their shape and angle also referencing traditional coal-fired circulating fluidized bed boilers.

[0003] When biomass fuel is relatively simple and stable, problems are not apparent in the short term, and continuous and stable operation can be maintained. However, when the content of alkali metal elements such as potassium and sodium in biomass fuel ash increases, traditional cyclone separators have limitations. Material accumulation easily forms in the cone section, causing poor circulation in the material circulation system. In severe cases, it can directly block the entire bottom of the separator, causing the material circulation system to fail and leading to boiler shutdown. Especially now that biomass fuels are complex and diverse, and the composition of fuel ash changes rapidly, the stability requirements for the boiler's material circulation system are very high. Continuous and stable operation of the cyclone separator is essential to ensure the normal operation of the boiler.

[0004] Because traditional cyclone separators suffer from intermittent and frequent failures and have poor stability, they can easily force biomass circulating fluidized bed boilers to reduce load or even shut down during operation, causing great trouble to the safe and continuous operation of biomass circulating fluidized bed boilers. Temporary shutdowns during special periods can also lead to huge economic losses. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of the aforementioned background technology and provide a cyclone separator with good stability that can maintain the continuous and stable operation of a biomass circulating fluidized bed boiler.

[0006] To achieve this objective, the biomass circulating fluidized bed boiler cyclone separator designed in this utility model includes a flue gas inlet section, a gas-solid two-phase separation section connected to the flue gas inlet section, a flue gas outlet section connected to the top and bottom of the gas-solid two-phase separation section respectively, and a solid return section. The solid return section includes multiple coaxially connected and fixedly connected solid return straight sections and multiple solid return conical sections, which are arranged at intervals in the vertical direction. Flue gas can flow in from the flue gas inlet section, rotate along the inner wall of the gas-solid two-phase separation section, and achieve gas-solid two-phase separation through centrifugal force. The gas phase flows out through the flue gas outlet section, and the solid phase is returned from top to bottom through the solid return section.

[0007] Furthermore, the inner diameter of the upper solid return material straight section is larger than the inner diameter of the lower solid return material straight section.

[0008] Furthermore, the inner diameter of the top of the solid return cone section is the same as the inner diameter of the solid return straight section connected above it, and the inner diameter of the bottom of the solid return cone section is the same as the inner diameter of the solid return straight section connected below it.

[0009] Furthermore, a return material riser is coaxially and fixedly connected to the bottom of the solid material return section, and the inner diameter of the return material riser is the same as the inner diameter of the smallest part of the bottom of the solid material return section.

[0010] Furthermore, the flue gas inlet section includes a horizontally arranged flue gas acceleration section with a uniformly reduced inner diameter and a flue gas inlet straight section that connects to the smallest inner diameter end of the flue gas acceleration section and guides the accelerated flue gas into the gas-solid two-phase separation section. The inner diameter of the flue gas inlet straight section is the same as the smallest inner diameter of the flue gas acceleration section.

[0011] Furthermore, the gas-solid two-phase separation section includes arc-shaped sidewalls at both ends that are fixedly connected to the horizontal sides of the ends of the flue gas inlet straight section, and includes multiple arc segments with different radii.

[0012] Furthermore, the radius of the arc segment that is fixedly connected to the horizontal side of the flue gas inlet straight section extending into the gas-solid two-phase separation section is greater than the radius of the arc segment that is fixedly connected to the horizontal side of the flue gas inlet straight section that does not extend into the gas-solid two-phase separation section.

[0013] Furthermore, the flue gas outlet section and the solid material return section are arranged coaxially or in parallel.

[0014] Furthermore, the flue gas outlet section includes a first flue gas outlet straight section located inside the gas-solid two-phase separation section and a second flue gas outlet straight section connected to the top of the gas-solid two-phase separation section and coaxially connected with the first flue gas outlet straight section.

[0015] Furthermore, a tapering structure is provided at the bottom of the first flue gas outlet straight section.

[0016] The beneficial effects of this utility model are:

[0017] 1. The solid material return section adopts a structure with multiple coaxially connected straight and conical sections arranged at intervals. Compared with the traditional single straight section + single conical section design, this segmented design changes the inner diameter and cone angle, reducing the sliding resistance of materials on the inner wall of the conical section. This reduces the accumulation problem caused by the strong adhesion of ash slag with high alkali metal content, ensuring continuous and smooth return of solid materials. The inner diameter of the upper solid material return section is larger than that of the lower straight section, forming a stepped contraction. Combined with the design that the inner diameters of the top and bottom of the conical section are aligned with the upper and lower straight sections respectively, the material gradually accelerates during its descent, avoiding eddies or stagnation caused by sudden contraction. This is especially suitable for scenarios with varying fuel ash compositions. The inner diameter of the return riser is consistent with the minimum inner diameter of the solid material return section, ensuring continuous material flow and preventing local blockages.

[0018] 2. The flue gas acceleration section is horizontally arranged with a uniformly reduced inner diameter, accelerating the flue gas entering the separator, enhancing the centrifugal force between the gas and solid phases, and improving separation efficiency. The flue gas inlet straight section introduces the accelerated flue gas into the gas-solid two-phase separation section at a stable flow rate. Combined with the multi-arc section design of the curved sidewalls, it guides the flue gas to form a more stable rotating flow field along the inner wall, reducing separation efficiency fluctuations caused by airflow disturbances. One side of the flue gas inlet straight section extends into the gas-solid two-phase separation section, creating different radii for the two arc sections (the extended side has a larger radius), forming an asymmetric flow field. This prolongs the rotation path of solid particles within the separation section, enhancing the centrifugal separation effect, while reducing the risk of gas-phase short-circuiting (i.e., insufficiently separated gas directly entering the flue gas outlet). This asymmetric structure can adapt to the complex gas-solid two-phase flow characteristics generated by biomass fuel combustion, and is particularly effective for separating flue gas with high ash content and high alkali metal content.

[0019] 3. The flue gas outlet section and the solid return section are arranged coaxially or parallel to each other, adapting to different boiler structure requirements and improving equipment installation compatibility. The first flue gas outlet straight section is located inside the separation section. Its bottom tapering structure (such as a tapered port) can suppress airflow turbulence in the outlet area, reducing the phenomenon of separated solid particles being re-entrained by the gas phase (secondary entrainment), further improving separation efficiency. The second flue gas outlet straight section is coaxially connected to the first straight section, ensuring a stable gas flow, reducing pressure loss, and improving system energy efficiency.

[0020] In summary, this invention solves the intermittent clogging problem caused by alkali metal adhesion in traditional cyclone separators through segmented optimized solid return paths and gas-solid separation flow fields, avoiding forced boiler load reduction or shutdown. It is particularly suitable for biomass combustion scenarios with complex fuel types and variable ash compositions. This reduces economic losses caused by temporary shutdowns during special periods, extends equipment operating cycles, lowers maintenance costs, and improves the safety, reliability, and commercial operation efficiency of biomass circulating fluidized bed boilers. This invention achieves the dual goals of "high-efficiency separation + smooth material return" through structural innovation, providing key technical support for the stable operation of biomass circulating fluidized bed boilers, and has significant engineering application value and market promotion significance. Attached Figure Description

[0021] Figure 1 This is a front view of the cyclone separator designed according to this utility model;

[0022] Figure 2 A top view of the cyclone separator designed according to this utility model;

[0023] Wherein, 1—flue gas inlet section (1.1—flue gas acceleration section, 1.2—flue gas inlet straight section), 2—first solid material return straight section, 3—first solid material return cone section, 4—second solid material return straight section, 5—second solid material return cone section, 6—return riser, 7—first flue gas outlet straight section, 8—second flue gas outlet straight section, 9—gas-solid two-phase separation section, 10—solid material return section. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. In the description of the present utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present utility model.

[0025] like Figure 1As shown in Figure 2, in some embodiments, the cyclone separator of a biomass circulating fluidized bed boiler includes a flue gas inlet section 1, a gas-solid two-phase separation section 9 connected to the flue gas inlet section 1, a flue gas outlet section and a solid return section 10 connected to the top and bottom of the gas-solid two-phase separation section 9, respectively. Flue gas can flow in from the flue gas inlet section 1, rotate along the inner wall of the gas-solid two-phase separation section 9, and achieve gas-solid two-phase separation through centrifugal force. The gas phase flows out through the flue gas outlet section, and the solid phase is returned to the solid return section 10 from top to bottom.

[0026] Example 1

[0027] A specific embodiment of the solid recycling section 10 is provided:

[0028] like Figure 1 As shown, the solid material return section 10 includes multiple straight solid material return sections and multiple conical solid material return sections that are coaxially connected and fixedly linked as a single unit. The straight and conical solid material return sections are arranged at intervals in the vertical direction. The inner diameter of the upper solid material return section is larger than that of the lower solid material return section. The inner diameter of the top of the conical solid material return section is the same as the inner diameter of the solid material return section connected above it, and the inner diameter of the bottom of the conical solid material return section is the same as the inner diameter of the solid material return section connected below it. A return pipe 6 is coaxially and fixedly connected to the bottom of the solid material return section 10, and the inner diameter of the return pipe 6 is the same as the minimum inner diameter at the bottom of the solid material return section 10.

[0029] This utility model is illustrated using two straight sections and two conical sections for solid material return as examples. Figure 1 As shown, the two solid material return sections include a first solid material return section 2 and a second solid material return section 4, and the two solid material return cone sections include a first solid material return cone section 3 and a second solid material return cone section 5. The bottom end of the second solid material return cone section 5 is coaxially connected to a return riser 6. The heights of the first solid material return section 2 and the second solid material return section 4 are different, i.e., H2 is not equal to H4. Similarly, the heights of the first solid material return cone section 3 and the second solid material return cone section 5 are also different, i.e., H3 is not equal to H5. This design facilitates the slow rotation and settling of particles without accumulation within the separator, achieving continuous and stable material circulation. The two straight sections each have a certain height, and the two cone sections have a certain inclination angle (70°~78°), which facilitates the free rotation and sliding of captured biomass particles, preventing accumulation. The dimensions of the gas-solid two-phase separation section 9 are related to the boiler's flue gas volume. The inner diameter of the return riser 6 is related to the boiler's capacity and fuel ash content, and can be adjusted according to actual conditions, generally ranging from 500 to 700 mm.

[0030] Example 2

[0031] A specific embodiment of the flue gas inlet section 1 is provided:

[0032] like Figure 2 As shown, the flue gas inlet section 1 includes a horizontally arranged flue gas acceleration section 1.1 with a uniformly reduced inner diameter and a flue gas guide straight section 1.2 connected to the smallest end of the inner diameter of the flue gas acceleration section 1.1, which guides the accelerated flue gas into the gas-solid two-phase separation section 9. The inner diameter of the flue gas guide straight section 1.2 is the same as the smallest inner diameter of the flue gas acceleration section 1.1.

[0033] Example 3

[0034] A specific embodiment of a gas-solid two-phase separation section 9 is provided:

[0035] like Figure 1 As shown in Figure 2, the gas-solid two-phase separation section 9 includes arc-shaped sidewalls at both ends that are fixedly connected to the horizontal sides of the ends of the flue gas inlet section 1.2. These sidewalls comprise multiple arc segments with different radii. One horizontal side of the flue gas inlet section 1.2 extends into the gas-solid two-phase separation section 9. The radius of the arc segment fixedly connected to the horizontal side of the flue gas inlet section 1.2 extending into the gas-solid two-phase separation section 9 is greater than the radius of the arc segment fixedly connected to the horizontal side of the flue gas inlet section 1.2 not extending into the gas-solid two-phase separation section 9, i.e., R2 > R1, and the difference between R2 and R1 is between 150 and 300 mm. This structural design offers higher separation efficiency than concentric circles.

[0036] Example 4

[0037] A specific embodiment of the flue gas outlet section is provided:

[0038] like Figure 1 As shown, the flue gas outlet section and the solid return section 10 are arranged coaxially or parallel. The flue gas outlet section includes a first flue gas outlet straight section 7 located inside the gas-solid two-phase separation section 9 and a second flue gas outlet straight section 8 connected to the top of the gas-solid two-phase separation section 9 and coaxially connected to the first flue gas outlet straight section 7. The bottom of the first flue gas outlet straight section 7 is provided with a tapering structure. The height of the second flue gas outlet straight section 8 depends on the height H1 of the flue gas inlet section 1, and there is a certain proportional relationship (0.4-0.5H1). The inner diameter R3 of the second flue gas outlet straight section 8 is related to the throat flue gas velocity, and it is necessary to ensure that the throat flue gas velocity is within the normal range (35-40 m / s). This velocity can affect the flue gas resistance of the overall separator.

[0039] In this utility model, such as Figure 1As shown in Figure 2, high-temperature flue gas exits the furnace and flows in through flue gas inlet section 1. The flue gas velocity here should not be too high, approximately 15-20 m / s is preferable to prevent premature wear at the furnace outlet. After entering the flue gas acceleration section 1.1, the flue gradually narrows from L1 to L2, and the flue gas gradually accelerates. After accelerating to approximately 25 m / s, the flue becomes a straight flue (i.e., flue gas inlet straight section 1.2). Flue gas inlet straight section 1.2 has a certain stroke, and after the flue gas accelerates and levels out in flue gas inlet straight section 1.2, it directly enters the gas-solid two-phase separation section 9. Under the action of the flue gas outlet section, the high-temperature hot flue gas undergoes gas-solid two-phase separation, with large particles being separated. The remaining flue gas flows out through the first flue gas outlet straight section 7 and the second flue gas outlet straight section 8. The flue gas outlet section can be located at the exact center of the separator or eccentrically. The eccentric setting is slightly more complex but has slightly higher separation efficiency. The bottom of the first flue gas outlet straight section 7 is tapered, with a slightly smaller bottom diameter and a slightly larger top diameter, which facilitates flue gas outflow. The separated coarse particles rotate and descend around the inner wall of the gas-solid two-phase separation section 9, passing through the first solid return straight section 2, the first solid return cone section 3, the second solid return straight section 4, and the second solid return cone section 5, before falling into the return riser 6. Finally, the solids recovered by the return riser 6 are recycled and sent back into the furnace for combustion. The main rotating and falling stages of the cyclone separator designed in this invention are in the gas-solid two-phase separation section 9, the first solid return straight section 2, and the first solid return cone section 3. The second solid return straight section 4 and the second solid return cone section 5 are established to prevent the accumulation of sticky particles from biomass fuel ash.

[0040] In summary, this invention solves the intermittent clogging problem caused by alkali metal adhesion in traditional cyclone separators through segmented optimized solid return paths and gas-solid separation flow fields, avoiding forced boiler load reduction or shutdown. It is particularly suitable for biomass combustion scenarios with complex fuel types and variable ash compositions. This reduces economic losses caused by temporary shutdowns during special periods, extends equipment operating cycles, lowers maintenance costs, and improves the safety, reliability, and commercial operation efficiency of biomass circulating fluidized bed boilers. This invention achieves the dual goals of "high-efficiency separation + smooth material return" through structural innovation, providing key technical support for the stable operation of biomass circulating fluidized bed boilers, and has significant engineering application value and market promotion significance.

[0041] It should be noted that the above description of the technical solutions is exemplary, and this specification may be embodied in different forms and should not be construed as limiting itself to the technical solutions set forth herein. Rather, providing these descriptions will make the disclosure of this utility model thorough and complete, and will fully convey the scope disclosed herein to those skilled in the art. Furthermore, the technical solutions of this utility model are defined only by the scope of the claims. The shapes, dimensions, ratios, angles, and figures disclosed in the description of various aspects of this specification and claims are merely examples, and therefore, this specification and claims are not limited to the details shown. In the following description, detailed descriptions of related known functions or configurations will be omitted where it is determined that such detailed descriptions would unnecessarily obscure the focus of this specification and claims. Where the terms “comprising,” “having,” and “including” are used as described in this specification, there may also be another part or other components, and the terms used are generally singular but may also represent plural forms. It should be noted that although various different components may appear and be described in this specification using terms such as “first,” “second,” “top,” “bottom,” “side,” “other side,” “one end,” “other end,” etc., these components and parts should not be limited by these terms. These terms are only used to distinguish one component and part from another component and part. For example, without departing from the scope of this specification, the first component may be referred to as the second component, and similarly, the second component may be referred to as the first component; the top and bottom components may be interchanged or converted in certain circumstances; and the components at one end and the other end may have the same or different performance.

[0042] Finally, it should be noted that the above embodiments are merely representative examples of this utility model. Obviously, this utility model is not limited to the above embodiments and can have many variations. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this utility model should be considered to fall within the protection scope of this utility model.

Claims

1. A cyclone separator for a biomass circulating fluidized bed boiler, characterized in that: It includes a flue gas inlet section (1), a gas-solid two-phase separation section (9) connected to the flue gas inlet section (1), a flue gas outlet section and a solid return section (10) connected to the top and bottom of the gas-solid two-phase separation section (9) respectively; The solid return section (10) includes multiple solid return straight sections and multiple solid return conical sections that are coaxially connected and fixedly connected as a single structure. The solid return straight sections and the solid return conical sections are arranged at intervals in the vertical direction. Flue gas can flow in from the flue gas inlet section (1), rotate along the inner wall of the gas-solid two-phase separation section (9) and achieve gas-solid two-phase separation by centrifugal force. The gas phase flows out through the flue gas outlet section, and the solid phase is returned from top to bottom through the solid return section (10).

2. The cyclone separator for a biomass circulating fluidized bed boiler as described in claim 1, characterized in that: The inner diameter of the upper solid return material straight section is larger than the inner diameter of the lower solid return material straight section.

3. The cyclone separator for a biomass circulating fluidized bed boiler as described in claim 2, characterized in that: The top inner diameter of the solid return cone section is the same as the inner diameter of the solid return straight section connected above it, and the bottom inner diameter of the solid return cone section is the same as the inner diameter of the solid return straight section connected below it.

4. The cyclone separator for a biomass circulating fluidized bed boiler as described in claim 1, characterized in that: The bottom of the solid return section (10) is coaxially and fixedly connected to a return riser (6), and the inner diameter of the return riser (6) is the same as the inner diameter of the smallest part of the bottom of the solid return section (10).

5. The cyclone separator for a biomass circulating fluidized bed boiler as described in claim 1, characterized in that: The flue gas inlet section (1) includes a horizontally arranged flue gas acceleration section (1.1) with a uniformly reduced inner diameter and a flue gas inlet straight section (1.2) connected to the smallest inner diameter end of the flue gas acceleration section (1.1) to guide the accelerated flue gas into the gas-solid two-phase separation section (9). The inner diameter of the flue gas inlet straight section (1.2) is the same as the smallest inner diameter of the flue gas acceleration section (1.1).

6. The cyclone separator for a biomass circulating fluidized bed boiler as described in claim 5, characterized in that: The gas-solid two-phase separation section (9) includes arc-shaped sidewalls that are fixedly connected at both ends to the horizontal sides of the ends of the flue gas inlet straight section (1.2), and includes multiple arc segments with different radii.

7. The cyclone separator for a biomass circulating fluidized bed boiler as described in claim 6, characterized in that: The horizontal side of the flue gas inlet section (1.2) extends into the gas-solid two-phase separation section (9), and the radius of the arc segment that is fixedly connected to the horizontal side of the flue gas inlet section (1.2) extending into the gas-solid two-phase separation section (9) is greater than the radius of the arc segment that is fixedly connected to the horizontal side of the flue gas inlet section (1.2) that does not extend into the gas-solid two-phase separation section (9).

8. The cyclone separator for a biomass circulating fluidized bed boiler as described in claim 1, 6, or 7, characterized in that: The flue gas outlet section and the solid return section (10) are arranged coaxially or in parallel.

9. The cyclone separator for a biomass circulating fluidized bed boiler as described in claim 8, characterized in that: The flue gas outlet section includes a first flue gas outlet straight section (7) located inside the gas-solid two-phase separation section (9) and a second flue gas outlet straight section (8) connected to the top of the gas-solid two-phase separation section (9) and coaxially connected with the first flue gas outlet straight section (7).

10. The cyclone separator for a biomass circulating fluidized bed boiler as described in claim 9, characterized in that: The bottom of the first flue gas outlet straight section (7) is provided with a tapering structure.

Images