A biomass mill for a biomass pulverizing system
By integrating drying, crushing, grinding and screening functions, the biomass mill has solved the problems of high cost and poor reliability of biomass milling equipment, realizing efficient biomass milling and energy utilization, and reducing the cost of biomass co-generation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI CARBON THINK KRYPTON TECHNOLOGY ENGINEERING CO LTD
- Filing Date
- 2025-08-22
- Publication Date
- 2026-07-24
AI Technical Summary
Existing biomass pulverizing equipment suffers from high pulverizing costs, poor equipment reliability, and poor adaptability to materials. In particular, traditional coal pulverizing equipment is not suitable for the characteristics of biomass, resulting in high costs for biomass co-generation.
Design a biomass mill that integrates raw material drying, crushing, grinding, powder screening, and powder conveying functions. It dries straw with high-temperature flue gas and achieves efficient crushing and screening of straw using grinding and separation mechanisms. The hammer and fan blade structure improves crushing efficiency and particle size control.
This technology enables efficient grinding of biomass such as straw, reduces the cost of biomass co-generation, improves equipment reliability and material adaptability, and promotes the energy utilization of biomass and the reduction of carbon emissions.
Smart Images
Figure CN224541855U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of biomass milling equipment technology, and more specifically to a biomass mill for a biomass milling system. Background Technology
[0002] Biomass co-generation can be broadly categorized into three types: steam co-generation, indirect co-generation, and direct combustion co-generation. With current technology, direct combustion co-generation has the lowest operation and maintenance costs.
[0003] There are three process routes for direct combustion coupling. The first is coal mill coupling, where biomass is mixed with raw coal and fed into an existing coal pulverizing system. The biomass and raw coal are ground into powder together and then burned in the boiler via a burner. The second is burner coupling, where biomass is pulverized in a separate biomass pulverizing unit and then mixed with pulverized coal before entering the burner. The third is furnace coupling, where biomass is pulverized in a separate biomass pulverizing unit and then burned in the boiler via a separate biomass burner. Due to the incompatibility of coal mills with biomass, the biomass coupling ratio is very low, and coal mill coupling cannot achieve the goal of biomass coupling. Both burner coupling and furnace coupling require the biomass to be pulverized. Currently, there are two methods for biomass pulverization. The first method involves first briquetting or pelletizing the biomass to produce biomass fuel blocks or pellets, and then using pulverizing equipment to pulverize the biomass fuel blocks or pellets into biomass powder. The second method uses a multi-stage hammer mill to crush biomass into biomass powder with the required particle size. However, due to unreasonable milling processes and poor performance of milling equipment, biomass milling suffers from problems such as high milling costs, poor equipment reliability, and poor equipment adaptability to materials.
[0004] Although direct combustion co-firing is currently the lowest-cost method for biomass co-firing, the cost of biomass power generation is still higher than that of raw coal. This means that low-cost, specialized, and large-scale biomass pulverization technology and systems represent the current technological bottleneck for biomass co-firing power generation. Biomass is characterized by its high plant fiber content, high water content, and high volatile matter content. Plant fibers, under normal conditions, have strong toughness, especially when the water content is high, making biomass pulverization very difficult. Traditional coal pulverizing equipment and feed grinding equipment are not suitable for biomass pulverization.
[0005] Therefore, how to provide a biomass mill that integrates functions such as raw material drying, crushing, grinding, powder screening, and material conveying is a problem that urgently needs to be solved by those skilled in the art. Utility Model Content
[0006] In view of this, the present invention provides a biomass mill for a biomass milling system, which is suitable for biomass milling of straw, forestry waste, urban landscaping waste, waste wood, aquatic plants such as reeds, and energy plants such as sand willow. It integrates raw material drying, crushing, grinding, powder screening, and powder conveying functions, and is of great significance for the energy utilization of biomass such as straw and the reduction of carbon emissions.
[0007] To achieve the above objectives, the present invention adopts the following technical solution:
[0008] A biomass mill for a biomass milling system, comprising:
[0009] The shell has an inlet on one side wall for inputting straw and high-temperature flue gas, and an outlet at the top for conveying powder.
[0010] A grinding mechanism is rotatably connected within the housing; the grinding mechanism includes a mounting plate, a reinforcing plate, and blades; the mounting plate and the reinforcing plate are arranged opposite to each other; the number of blades is multiple, and their two ends are respectively fixed to the opposite side walls of the mounting plate and the reinforcing plate to divide the cavity between the mounting plate and the reinforcing plate into multiple sector-shaped areas; an air inlet is opened in the middle of the reinforcing plate and corresponds to the inlet, the air inlet communicating with the sector-shaped area;
[0011] A separation mechanism, wherein the air-powder inlet at the lower end of the separation mechanism is connected to the outlet for screening the powder.
[0012] The beneficial effects of this utility model are as follows: straw and high-temperature flue gas enter the shell through the inlet, and the high-temperature flue gas is used to dry the straw, removing moisture and making it brittle and easy to break; when the grinding mechanism rotates at high speed, air is drawn in from the air inlet, and then the high-temperature flue gas and straw are drawn into multiple fan-shaped areas between the mounting plate and the reinforcing plate. After the air passes through the fan-shaped areas, it forms a vortex in the shell, which can agitate the dried straw. During the agitation process, the straw enters the shell through the fan-shaped areas. During this process, the straw collides with the inner wall of the shell and the blades and is broken into straw powder; the straw powder enters the separation mechanism for screening. Larger particles re-enter the shell for secondary crushing, while smaller particles enter the powder conveying pipeline through the separation mechanism for direct combustion or storage.
[0013] Preferably, there is a gap between the circumferential direction of the grinding mechanism and the inner sidewall of the housing; the width of the gap gradually increases along the rotation direction of the grinding mechanism. The gradually increasing gap width can increase the ventilation volume inside the housing. After the air enters the fan-shaped area from the air inlet, it is turbulent inside the housing and finally discharged through the powder outlet of the separation mechanism. The change in gap can increase the ventilation volume, improve the air vortex efficiency, thereby accelerating the flow of straw and improving the crushing efficiency.
[0014] Preferably, the grinding mechanism further includes a fixed shaft and hammers; one end of the fixed shaft is vertically fixed to the surface of the mounting plate corresponding to the sector area; the number of hammers is multiple, with one end of each hammer hinged to the fixed shaft and the other end extending into the gap. During the high-speed rotation of the grinding mechanism, the hammers oscillate within the sector area, and a portion of the hammers located within the gap can further crush the straw, improving the grinding effect and quality.
[0015] Preferably, the inner wall of the housing is provided with a clearance groove corresponding to the gap with the smallest width. When the hammer is located at the gap with the smallest width, it prevents the hammer from colliding with the inner wall of the housing, and the clearance groove ensures the high-speed rotation of the grinding mechanism and the grinding effect.
[0016] Preferably, the separation mechanism includes an outer conical tube, an inner conical tube, a powder outlet pipe, and a powder return pipe; the inner conical tube is coaxially fixed inside the outer conical tube, and an air-powder flow channel connecting the air-powder inlet and the inner cavity of the inner conical tube is formed between the outer wall of the inner conical tube and the inner wall of the outer conical tube; the powder outlet pipe is vertically fixed to the top wall of the outer conical tube and its lower end connects to the inner cavity of the inner conical tube; one end of the powder return pipe is fixed to the lower end of the inner conical tube, and the other end points to the clearance groove. Air inside the housing carries the crushed powder into the air-powder flow channel, thereby entering the inner conical tube. Under the action of high-speed centrifugal force, larger particles enter the clearance groove through the powder return pipe for secondary crushing, while smaller particles are conveyed to the powder conveying pipeline through the powder outlet pipe.
[0017] Preferably, the inner top wall of the outer conical tube is hinged with multiple fan blades; a flow channel is formed between two adjacent fan blades, connecting the air-powder flow channel and the inner cavity of the inner conical tube. The fan blades are used to screen the particle size of the powder.
[0018] Preferably, the outer top wall of the outer conical tube is provided with a plurality of handles corresponding one-to-one with the fan blades to adjust the opening and closing degree of the fan blades. By adjusting the opening and closing angle of the fan blades through the handles, the particle size of the sieved powder can be adjusted.
[0019] Preferably, the system also includes a feed pipe, the inlet of which is connected to the mixer of the biomass milling system, and the outlet of which is connected to the inlet. The raw materials and high-temperature flue gas in the mixer are transported into the housing through the feed pipe.
[0020] Preferably, the device further includes a drive mechanism, which comprises a fixed base, a motor, and a bearing housing; a rotor is fixed to the center of the mounting plate; the fixed base is fixed to the side wall of the housing away from the inlet; the motor and the bearing housing are fixed to the top surface of the fixed base; the output shaft of the motor is interference-fitted with a bearing in the bearing housing and passes through the outer wall of the housing, and is fixed to the rotor. The motor drives the mounting plate to rotate at high speed, thereby achieving the crushing and grinding of straw.
[0021] Preferably, the housing and the separation mechanism are connected by a connecting pipe.
[0022] As can be seen from the above technical solution, compared with the prior art, this utility model discloses a biomass mill for a biomass milling system. It performs straw drying, crushing, and grinding operations within the casing, and the crushed powder is screened within the separation mechanism, selecting powder with qualified particle size for storage or direct combustion. This utility model's biomass mill integrates raw material drying, crushing, grinding, powder screening, and powder conveying functions, which is of great significance for the energy utilization of straw and other biomass and the reduction of carbon emissions. Attached Figure Description
[0023] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0024] Figure 1 This is a schematic diagram of the biomass mill structure provided by this utility model;
[0025] Figure 2 A cross-sectional view of the biomass mill provided by this utility model;
[0026] Figure 3 A schematic diagram of the shell structure provided for this utility model;
[0027] Figure 4 A cross-sectional view of the housing provided for this utility model;
[0028] Figure 5 A schematic diagram of the clearance groove provided by this utility model;
[0029] Figure 6 A schematic diagram of the grinding mechanism provided by this utility model;
[0030] Figure 7 A schematic diagram of the air intake of the grinding mechanism provided by this utility model;
[0031] Figure 8 A cross-sectional view of the separation mechanism provided by this utility model;
[0032] Figure 9 This is a diagram showing the arrangement of the fan blades in the separation mechanism provided by this utility model.
[0033] Among them, 1-feed pipe; 11-feed inlet; 2-shell; 21-inlet; 22-outlet; 23-gap groove; 24-groove sidewall; 25-first inclined surface; 26-second inclined surface; 27-arc surface; 3-connecting pipe; 4-separation mechanism; 41-outer conical pipe; 42-inner conical pipe; 43-return powder pipe; 44-air-powder inlet; 45-powder outlet pipe; 46-fan blade; 47-handle; 48-air-powder flow channel; 5-grinding mechanism; 51-mounting plate; 52-rotor; 53-blade; 54-reinforcing plate; 55-hammer; 56-fixed shaft; 57-fan-shaped area; 58-air inlet; 6-drive mechanism; 61-fixed seat; 62-motor; 63-bearing box; 7-support leg; 8-gap. Detailed Implementation
[0034] 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.
[0035] See appendix Figures 1 to 8 According to an embodiment of the present invention, a biomass mill for a biomass milling system collects and utilizes qualified powder by drying, grinding, sieving, and conveying straw within the mill. The mill includes a shell 2, a grinding mechanism 5, and a separation mechanism 4. An inlet 21 is provided on one side wall of the shell 2 to input straw and high-temperature flue gas, and an outlet 22 is provided at the top to convey powder. The grinding mechanism 5 is rotatably connected inside the shell 2. A gap 8 exists between the circumference of the grinding mechanism 5 and the inner side wall of the shell 2. The width of the gap 8 gradually increases along the rotation direction of the grinding mechanism 5. The grinding mechanism 5 includes a mounting plate 51 and a reinforcing plate 5. 4 and blades 53; mounting plate 51 and reinforcing plate 54 are arranged opposite to each other; there are multiple blades 53, and their two ends are fixed to the opposite side walls of mounting plate 51 and reinforcing plate 54 to divide the cavity between mounting plate 51 and reinforcing plate 54 into multiple sector areas 57; the middle part of reinforcing plate 54 has an air inlet 58 and a corresponding inlet 21, and the air inlet 58 is connected to the sector area 57; the difference between the outer diameter of reinforcing plate 54 and the diameter of air inlet 58 is twice the height T of blade 53; the housing 2 and the separation mechanism 4 are connected by a connecting pipe 3; the air powder inlet 44 at the lower end of the separation mechanism 4 is connected to the outlet 22 to screen the powder.
[0036] like Figure 4 and 7 As shown, the casing has a volute-like structure similar to that of a centrifugal fan. Gradually varying gaps ensure effective straw guidance and crushing; the distance between the inner wall of the casing and the circumference of the mounting plate increases sequentially along the rotation direction of the mounting plate. When straw and high-temperature flue gas enter the casing, the high-temperature flue gas dries the straw, making it brittle. The grinding mechanism rotates at high speed, and the reinforcing plate draws in air through the air inlet. The air enters the inner cavity of the casing from the fan-shaped area, forming a vortex that disturbs the straw within the casing. During this high-speed disturbance, the dried straw collides with the inner wall of the casing and the blades, thus crushing it into powder.
[0037] like Figure 1 and 3 As shown, the outlet at the upper end of the housing is square, and the air-powder inlet at the lower end of the separation mechanism is round. Therefore, the separation mechanism and the housing are connected by a connecting pipe with a square opening at the lower end and a round opening at the upper end.
[0038] In other specific embodiments, to improve the quality of straw milling, the milling mechanism 5 further includes a fixed shaft 56 and hammer blades 55; one end of the fixed shaft 56 is vertically fixed to the surface of the mounting plate 51 corresponding to the sector area 57; there are multiple hammer blades 55, one end of which is hinged to the fixed shaft 56, and the other end extends into the gap 8. Each sector area is fixed with a fixed shaft, and each fixed shaft is provided with 2 to 4 hammer blades. The hammer blades can swing within the sector area but will not move axially along the fixed shaft. The hammer blades extend into the gap, and during the high-speed rotation of the mounting plate, the swinging of the hammer blades can deeply crush the straw in the gap, ensuring the quality of milling.
[0039] To further optimize the above technical solution, a clearance groove 23 is provided on the inner wall of the housing 2 corresponding to the narrowest gap 8. Since the distance between the inner wall of the housing 2 and the circumferential surface of the mounting plate 51 gradually changes within the gap, when the hammer 53 rotates to the narrowest position of the gap, it will enter the clearance groove 23. By providing the clearance groove 23, the normal operation of the hammer 54 is ensured, preventing interference between the hammer 54 and the inner wall of the housing 2 at positions with smaller gaps. Figure 4 and 5 As shown, the clearance groove 23 includes two groove sidewalls 24. From top to bottom, the bottom wall of the clearance groove 23 consists of a first inclined surface 25, a second inclined surface 26, and an arc surface 27. The first inclined surface 25 extends to the upper end face of the housing 2. The second inclined surface 26 connects the first inclined surface 25 and the arc surface 27. The angle between the second inclined surface 26 and the horizontal plane is 22° to 25°. The lower end of the arc surface 27 connects to the transition arc surface of the inner bottom wall of the housing 2. The center of the arc surface 27 coincides with the rotation center of the mounting plate 51.
[0040] In this embodiment, the separation mechanism 4 includes an outer conical tube 41, an inner conical tube 42, a powder outlet pipe 45, and a powder return pipe 43. The inner conical tube 42 is coaxially fixed inside the outer conical tube 41. Multiple support plates are welded between the outer wall of the inner conical tube 42 and the inner wall of the outer conical tube 41, and the coaxial fixation between the inner conical tube 42 and the outer conical tube 41 is achieved through the multiple support plates. There is a powder flow channel 48 between the outer wall of the inner conical tube 42 and the inner wall of the outer conical tube 41, which connects the powder inlet 44 and the inner cavity of the inner conical tube 42. The powder outlet pipe 45 is vertically fixed to the top wall of the outer conical tube 41 and its lower end is connected to the inner cavity of the inner conical tube 42. One end of the powder return pipe 43 is fixed to the lower end of the inner conical tube 42, and the other end points to the relief groove 23.
[0041] To further optimize the above technical solution, multiple fan blades 46 are hinged to the inner top wall of the outer cone tube 41; a flow channel is formed between two adjacent fan blades 46 and connects the ventilation powder flow channel 48 and the inner cavity of the inner cone tube 42. The outer top wall of the outer cone tube 41 is provided with multiple handles 47 corresponding to the fan blades 46 to adjust the opening degree of the fan blades 46.
[0042] like Figure 8 As shown, the cross-sectional area of the air-powder flow between the inner and outer conical tubes is controlled by the design of their conical surfaces, ensuring sufficient airflow velocity. The air-powder mixture passes through the fan blades at the upper end of the outer conical tube and is discharged from the powder outlet pipe. As the airflow passes through the fan blades, the blades guide the airflow, generating a rotating flow field. Large particles in the air-powder mixture separate from the airflow under centrifugal force and fall into the inner conical tube. From there, they fall into the clearance groove through the return powder pipe for secondary crushing, while smaller particles are carried by the airflow through the powder outlet pipe into the powder conveying pipeline.
[0043] The angle of the fan blades can be adjusted via a handle connected to them, thus changing the intensity of the rotating flow field. Higher intensity flow results in smaller discharged powder particles. In this embodiment, the separation mechanism achieves the screening of powders of different particle sizes by adjusting the angle of the fan blades, ensuring the quality of the powder production.
[0044] In some other specific embodiments, a feed pipe 1 is also included, with its inlet 11 connected to the mixer of the biomass pulverizing system and its outlet connected to the inlet 21. A first pressure sensor is fixed on the pipe wall of the feed pipe 1 near the inlet 11.
[0045] To further optimize the above technical solution, a drive mechanism 6 is also included. The drive mechanism 6 includes a fixed base 61, a motor 62, and a bearing housing 63. A rotor 52 is fixed in the middle of the mounting plate 51. The fixed base 61 is fixed on the side wall of the housing 2 away from the inlet 21. The motor 62 and the bearing housing 63 are fixed on the top surface of the fixed base 61. The output shaft of the motor 62 is interference-fitted with the bearing in the bearing housing 63 and passes through the outer wall of the housing 2 and is fixed to the rotor 52.
[0046] To further optimize the above technical solution, a temperature sensor and a second pressure sensor are fixed to the outer wall of the powder outlet pipe.
[0047] Example 1
[0048] This utility model embodiment provides a biomass milling process using sugarcane leaves as raw material. It adopts the biomass mill in Embodiment 1. After the biomass mill is started, the high-speed rotation of the rotor causes the milling mechanism to draw air from the feed inlet at the feed pipe, enter the shell from the fan-shaped area and generate vortex, and finally exhaust the air from the powder outlet pipe.
[0049] After initial crushing, sugarcane leaves that meet the required size and high-temperature flue gas enter the mixer for preliminary drying. The pre-dried straw then enters the casing through the feed inlet. Inside the casing, the sugarcane leaves are carried by the grinding mechanism and rotated at high speed, where they are thoroughly mixed with the high-temperature flue gas and dried rapidly and completely, becoming brittle and fragile. The sugarcane leaves are then crushed by colliding with the blades and the inner wall of the casing.
[0050] After the high-temperature flue gas dries the sugarcane leaves, its temperature drops significantly, and it carries the powder into the powder distribution channel. The separation mechanism separates the coarse and fine powder. The flue gas carrying the fine powder exits through the powder outlet pipe, while a small portion of the substandard coarse powder returns to the lower casing through the air-powder distribution channel. Most of the substandard coarse powder returns to the clearance trough in the lower casing via the inner cone tube and return powder pipe. The hammer blades work in conjunction with the clearance trough to create a stronger crushing effect, further pulverizing the tougher plant fibers in the sugarcane leaves into fine powder within the clearance trough.
[0051] Experiments determined that sugarcane leaves achieve the best pulverization effect at a drying temperature of 140℃ to 150℃, so the outlet temperature was set between 140℃ and 150℃. Assuming a sugarcane leaf moisture content of 20% and a drying medium to biomass mass ratio of 2, heat balance calculations determined the high-temperature flue gas temperature used as the drying medium to be 388℃ to 405℃. When the moisture content of the sugarcane leaves changes, the temperature of the air-powder mixture at the outlet pipe also changes. Therefore, the temperature of the drying medium is adjusted accordingly to ensure the outlet temperature remains within the set range.
[0052] During the operation of a biomass mill, there is an optimal range for the filling rate of sugarcane leaves within the mill shell. Too low a filling rate results in low crushing efficiency and low mill output, while too high a filling rate can overload the main motor and even cause rotor jamming and mill blockage. The filling rate of sugarcane leaves within the mill shell is positively correlated with the resistance of the biomass mill; as the filling rate increases, the resistance also increases. First and second pressure sensors monitor the pressure at the inlet and outlet of the biomass mill in real time, generating resistance curves during operation. By utilizing the correlation between filling rate and resistance, as long as the resistance is controlled within a set range, the filling rate of the biomass mill can be ensured to be within the optimal range. For example, if the resistance is lower than the lower limit of the set range, it indicates that the filling rate is too low. In this case, increasing the feed rate will cause the filling rate to rise again, and the resistance will also increase accordingly, and vice versa.
[0053] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.
[0054] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A biomass mill for a biomass milling system, characterized in that, include: The shell (2) has an inlet (21) on one side wall for inputting straw and high-temperature flue gas, and an outlet (22) at the top for conveying powder. A grinding mechanism (5) is rotatably connected inside the housing (2); the grinding mechanism (5) includes a mounting plate (51), a reinforcing plate (54), and blades (53); the mounting plate (51) and the reinforcing plate (54) are arranged opposite to each other and their surfaces are arranged parallel to the side walls of the housing (2); there are multiple blades (53) and their two ends are respectively fixed to the opposite side walls of the mounting plate (51) and the reinforcing plate (54) to divide the cavity between the mounting plate (51) and the reinforcing plate (54) into multiple sector areas (57); the reinforcing plate (54) has an air inlet (58) in the middle and corresponds to the inlet (21), and the air inlet (58) communicates with the sector area (57); The separation mechanism (4) has a powder inlet (44) at its lower end and is connected to the outlet (22) to screen the powder.
2. A biomass mill for a biomass grinding system according to claim 1, characterized in that, There is a gap (8) between the circumferential direction of the grinding mechanism (5) and the inner sidewall of the housing (2); the width of the gap (8) gradually increases along the rotation direction of the grinding mechanism (5).
3. A biomass mill for a biomass milling system according to claim 2, characterized in that, The grinding mechanism (5) further includes a fixed shaft (56) and hammer blades (55); one end of the fixed shaft (56) is vertically fixed on the plate surface of the mounting plate (51) corresponding to the sector area (57); there are multiple hammer blades (55), one end of each hammer blade (55) is hinged to the fixed shaft (56), and the other end extends to the gap (8).
4. A biomass mill for a biomass grinding system according to claim 3, characterized in that, The housing (2) has a clearance groove (23) on its inner wall corresponding to the gap (8) with the smallest width.
5. A biomass mill for a biomass grinding system according to claim 4, characterized in that, The separation mechanism (4) includes an outer conical tube (41), an inner conical tube (42), a powder outlet tube (45), and a powder return tube (43); the inner conical tube (42) is coaxially fixed inside the outer conical tube (41), and there is a powder flow channel (48) between the outer wall of the inner conical tube (42) and the inner wall of the outer conical tube (41) connecting the powder inlet (44) and the inner cavity of the inner conical tube (42); the powder outlet tube (45) is vertically fixed to the top wall of the outer conical tube (41) and its lower end connects to the inner cavity of the inner conical tube (42); one end of the powder return tube (43) is fixed to the lower end of the inner conical tube (42), and the other end points to the relief groove (23).
6. A biomass mill for a biomass grinding system according to claim 5, characterized in that, The inner top wall of the outer cone tube (41) is hinged with a plurality of fan blades (46); a flow channel is formed between two adjacent fan blades (46) and connects the air-powder flow channel (48) and the inner cavity of the inner cone tube (42).
7. A biomass mill for a biomass milling system according to claim 6, characterized in that, The outer top wall of the outer cone tube (41) is provided with a plurality of handles (47) corresponding one-to-one with the fan blades (46) to adjust the opening degree of the fan blades (46).
8. A biomass mill for a biomass grinding system according to claim 1, characterized in that, It also includes a feed pipe (1), the feed port (11) of which is connected to the mixer of the biomass milling system, and the discharge port is connected to the inlet (21).
9. A biomass mill for a biomass milling system according to claim 1, characterized in that, It also includes a drive mechanism (6), which includes a fixed base (61), a motor (62) and a bearing housing (63); a rotor (52) is fixed in the middle of the mounting plate (51); the fixed base (61) is fixed on the side wall of the housing (2) away from the inlet (21); the motor (62) and the bearing housing (63) are fixed on the top surface of the fixed base (61); the output shaft of the motor (62) is interference-fitted with the bearing in the bearing housing (63) and passes through the outer wall of the housing (2) and is fixed to the rotor (52).
10. A biomass mill for a biomass milling system according to claim 1, characterized in that, The housing (2) and the separation mechanism (4) are connected by a connecting pipe (3).