Positive pressure system powder feeding device and method

Abstract

The invention provides a positive pressure system powder feeding device and method. The positive pressure system powder feeding device comprises a feeding unit, a multi-stage feeding station, a metering unit, a conveyor, an ejector, a fine adjustment controller and an electric control system. The feeding unit is located on one side of the multi-stage feeding station, powder is conveyed to a discharging port of the multi-stage feeding station through the feeding unit, and the conveyor is installed at a discharging port of the multi-stage feeding station. The metering unit is arranged on the multi-stage feeding station and is connected with the electric control system; the fine tuning controller is arranged on the ejector and is connected with the electric control system; the electric control system is used for adjusting the discharging speed of the multi-stage feeding station according to the material pile density signal and adjusting the powder output amount according to the powder discharging signal. Through interlocking control of the metering unit, the multi-stage feeding station, the conveyor and the fine adjustment controller, manual weight control is reduced, accurate and stable overall feeding is guaranteed, meanwhile, material feeding quantity parameters can be counted, feeding of different materials is facilitated, and the time cost of manual accounting and trial production is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of powder material transportation, and in particular, to a powder feeding device and method for a positive pressure system. Background Art

[0002] During the transportation of powder and small particle materials, it is usually necessary to put the powder into a hopper and then transport it through a feeding device. In a fully enclosed positive pressure system, the reaction unit needs to feed continuously and stably. However, the following problems exist in the prior art:

[0003] 1. Nitrogen interference problem: To maintain the stability of the silo pressure, nitrogen needs to be continuously filled. However, nitrogen will enter the system with the material, changing the fluidization characteristics of the material and resulting in a decrease in the feeding stability. In addition, the mixing of nitrogen into the system may increase the change in the gas composition of the subsequent process and increase the unstable factors of the reaction.

[0004] 2. Defects in manual control: The weight and flow rate of feeding rely on manual adjustment, lacking an automatic closed-loop control mechanism, which is prone to introducing operation errors. At the same time, the system cannot statistically calculate the feeding parameters in real time, and a large amount of time is required for manual calculation and trial production adjustment, resulting in low efficiency.

[0005] 3. The unstable powder feeding amount of the ejector caused by the airflow fluctuation in the positive pressure system affects the blanking accuracy. Summary of the Invention

[0006] Aiming at the defects in the prior art, the purpose of the present invention is to provide a powder feeding device and method for a positive pressure system.

[0007] According to the powder feeding device for a positive pressure system provided by the present invention, it includes a feeding unit, a multi-stage feeding station, a metering unit, a conveyor, a fine-tuning controller, an ejector, and an electric control system;

[0008] The feeding unit is arranged on one side of the multi-stage feeding station. The powder is transported to the blanking port at the upper end of the multi-stage feeding station through the feeding unit. The conveyor is installed at the discharging port of the multi-stage feeding station and is used to output the powder;

[0009] The metering unit is installed on the multi-stage feeding station and is signal-connected to the electric control system, and is used to send the material bulk density signal inside the multi-stage feeding station to the electric control system;

[0010] The fine-tuning controller is installed on the ejector connected to the output end of the conveyor and is signal-connected to the electric control system, and is used to send the powder blanking signal to the electric control system;

[0011] The electric control system is used to adjust the blanking rate of the powder inside the multi-stage feeding station according to the material bulk density signal inside the multi-stage feeding station, and is used to adjust the powder output amount of the conveyor according to the powder blanking signal.

[0012] Preferably, the multi-stage feeding station includes a first-stage feeding station, a second-stage feeding station, and a buffer bin that are connected in sequence from top to bottom;

[0013] Pneumatic control valves are provided between the first-stage feeding station and the second-stage feeding station, and between the second-stage feeding station and the buffer bin. The metering unit is installed on one side of the second-stage feeding station to detect the bulk density of the material inside the second-stage feeding station;

[0014] The electric control system is signal-connected to the pneumatic control valve and is used to control the opening degree of the pneumatic control valve according to the bulk density of the material inside the second-stage feeding station.

[0015] Preferably, the bottom of the first-stage feeding station is connected to the top of the second-stage feeding station through a first buffer section, and the bottom of the second-stage feeding station is connected to the top of the buffer bin through a second buffer section;

[0016] A first pneumatic control valve and a second pneumatic control valve are respectively provided at the connection between the first buffer section and the first-stage feeding station, and at the connection between the first buffer section and the second-stage feeding station;

[0017] A third pneumatic control valve and a fourth pneumatic control valve are respectively provided at the connection between the second buffer section and the second-stage feeding station, and at the connection between the second buffer section and the buffer bin.

[0018] Preferably, a quick-opening gland is provided at the top of the first-stage feeding station as the powder feeding port. The quick-opening gland is lined with a sealing strip for locking and sealing after feeding;

[0019] Symmetrical sight glasses are installed on the side wall of the first-stage feeding station, and a stirrer is arranged inside the first-stage feeding station.

[0020] Preferably, symmetrical sight glasses are installed on the side wall of the second-stage feeding station, and a gravity feeder is arranged inside the second-stage feeding station;

[0021] Both the second-stage feeding station and the metering unit are installed on an independent support frame, and the metering unit is arranged at the support frame of the second-stage feeding station. The calculated bulk density is displayed on the control screen through the electric control system.

[0022] Preferably, symmetrical sight glasses are installed on the side wall of the buffer bin, and a vibrator is installed on the outer wall of the buffer bin.

[0023] Preferably, the conveyor is a multi-stage conveyor, including a first-stage conveyor and a second-stage conveyor that are connected in sequence;

[0024] The input port of the first-stage conveyor is connected to the output port of the multi-stage feeding station, the output port of the first-stage conveyor is connected to the input port of the second-stage conveyor, and the output port of the second-stage conveyor is connected to a fine-tuning controller and an injector.

[0025] Preferably, the output port of the first-level conveyor is connected to the input port of the second-level conveyor through a third buffer section;

[0026] An observation sight glass is installed at the output port of the second-level conveyor.

[0027] Preferably, a ventilation unit is further included, and the ventilation unit includes a first ventilation pipeline, a second ventilation pipeline, and a third ventilation pipeline;

[0028] Both ends of the first ventilation pipeline are respectively communicated with the first feeding station, the second feeding station, and the buffer bin. Both ends of the second ventilation pipeline are respectively communicated with the first feeding station and the multi-stage conveyor. Both ends of the third ventilation pipeline are respectively communicated with the material pipeline below the fine-tuning controller and the inlet of the external nitrogen replacement pipeline. Valves are installed on the first ventilation pipeline, the second ventilation pipeline, and the third ventilation pipeline, and the valves are connected to the electric control system.

[0029] According to the positive-pressure system powder feeding method provided by the present invention, using the positive-pressure system powder feeding device as described above, the following steps are included:

[0030] Step 1: Powder is discharged and enters the second feeding station after being stirred in the first feeding station;

[0031] Step 2: The metering unit monitors the material bulk density and the real-time material weight in the second feeding station in real time. If the density is greater than the preset value, the electric control system controls the third pneumatic control valve and the fourth pneumatic control valve at the outlet of the second feeding station to increase the opening degree to accelerate the powder flow; if the density is less than the preset value, the electric control system controls the third pneumatic control valve and the fourth pneumatic control valve at the outlet of the second feeding station to decrease the opening degree to slow down the powder flow;

[0032] Step 3: The powder enters the first-level conveyor after passing through the buffer bin;

[0033] Step 4: The fine-tuning controller monitors the powder flow rate at the output end of the second-level conveyor in real time. If the flow rate is greater than the preset value, the electric control system controls the fine-tuning controller to reduce the rotation speed and at the same time reduce the overall operating speed of the multi-stage conveyor; if the flow rate is less than the preset value: the electric control system controls the fine-tuning controller to increase the rotation speed and at the same time increase the overall operating speed of the multi-stage conveyor.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. Through the interlocking control of the metering unit, multi-stage feeding stations, conveyors, and fine-tuning controllers, and by using the automatic control system, the present invention greatly reduces manual weight control. While ensuring accurate and stable overall feeding, it can also statistically analyze the material feeding quantity parameters, which is beneficial for the use of different materials, reduces the time cost of manual accounting and trial production, and the overall feeding device is sealed and not affected by system pressure fluctuations, ensuring the stability of the powder feeding quantity in the positive pressure system.

[0036] 2. In the present invention, the upper and lower parts of the secondary feeding station are connected to the remaining silos through buffer joints, and the secondary feeding station and the metering unit are installed on an independent support frame, so that the secondary feeding station and the metering unit are not disturbed by external vibrations, ensuring the measurement accuracy.

[0037] 3. The whole of the present invention is kept sealed, and the gas exchange between the inside of the multi-stage feeding station and between the multi-stage feeding station and the conveyor is realized through the ventilation unit. The gas replacement through the ventilation unit ensures the stability of the internal gas composition of the system, and at the same time ensures the tightness of toxic and harmful gases in the whole system.

[0038] 4. The present invention adopts a multi-stage conveyor. Through the fine-tuning controller, fine-tuning control can be realized for each section of the conveyor, ensuring continuity and stability, reducing the flow rate fluctuations caused by the influence of multi-stage silos, and at the same time can cope with more complex systems. Compared with the single-stage conveyor, it has higher accuracy, better stability and stronger adaptability to multiple materials, reducing the risk of blockage in the powder feeding system. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Other features, objects, and advantages of the present invention will become more apparent by reading the detailed description of the non-limiting embodiments with reference to the following drawings:

[0040] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0041] As shown in the figure:

[0042] Feeding unit 1 Ventilation unit 7

[0043] Primary feeding station 2-1 First pneumatic control valve 10-1

[0044] Secondary feeding station 2-2 Second pneumatic control valve 10-2

[0045] Buffer silo 2-3 Third pneumatic control valve 10-3

[0046] Metering unit 3 Fourth pneumatic control valve 10-4

[0047] Primary conveyor 4-1 First buffer joint 11-1

[0048] Secondary conveyor 4-2 Second buffer joint 11-2

[0049] Fine-tuning controller 5, Third buffer section 11-3

[0050] Injector 6, Shaker 12 Specific embodiments

[0051] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several changes and improvements can still be made. These all belong to the protection scope of the present invention.

[0052] The present invention discloses a positive pressure system powder feeding device and method. Through the interlocking control of a metering unit, a multi-stage feeding station, a conveyor, and a fine-tuning controller, and using an automatic control system, manual weight control is greatly reduced. While ensuring accurate and stable overall feeding, it can also count the material feeding quantity parameters, which is beneficial to the use of different materials and reduces the time cost of manual calculation and trial production.

[0053] Embodiment 1

[0054] This embodiment provides a positive pressure system powder feeding device, as Figure 1 shown, including a feeding unit 1, a multi-stage feeding station, a metering unit 3, a conveyor, a fine-tuning controller 6, and an electric control system; the feeding unit 1 is arranged on one side of the multi-stage feeding station, and the powder is transported to the feeding port at the upper end of the multi-stage feeding station through the feeding unit 1. The conveyor is installed at the discharging port of the multi-stage feeding station for outputting the powder;

[0055] The metering unit 3 is installed on the multi-stage feeding station and is signal-connected to the electric control system, and is used to send the weight signal of the material inside the multi-stage feeding station to the electric control system, and the electric control system completes the calculation of the material bulk density; the fine-tuning controller 5 is installed on the injector 6 connected to the output end of the multi-stage conveyor and is signal-connected to the electric control system, and is used to send the powder feeding signal to the electric control system; the electric control system is used to adjust the powder feeding rate inside the multi-stage feeding station according to the material bulk density signal inside the multi-stage feeding station, and is used to adjust the powder output of the conveyor according to the powder feeding signal.

[0056] This embodiment through the interlocking control of the metering unit 3, the multi-stage feeding station, the conveyor, and the fine-tuning controller 5, introducing an automatic control system, can adjust the feeding speed inside the feeding station and the output speed of the conveyor according to the real-time monitored powder accumulation and output speed, ensuring accurate and stable feeding while also being able to count the feeding parameters of the material, saving labor and time costs.

[0057] Specifically, the multi-stage feeding station includes a first-stage feeding station 2-1, a second-stage feeding station 2-2, and a buffer bin 2-3 that are connected in sequence from top to bottom; the bottom of the first-stage feeding station 2-1 is connected to the top of the second-stage feeding station 2-2 through a first buffer section 11-1, and the bottom of the second-stage feeding station 2-2 is connected to the top of the buffer bin 2-3 through a second buffer section 11-2; a first pneumatic control valve 10-1 and a second pneumatic control valve 10-2 are respectively arranged at the connection between the first buffer section 11-1 and the first-stage feeding station 2-1 and at the connection between the first buffer section 11-1 and the second-stage feeding station 2-2; a third pneumatic control valve 10-3 and a fourth pneumatic control valve 10-4 are respectively arranged at the connection between the second buffer section 11-2 and the second-stage feeding station 2-2 and at the connection between the second buffer section 11-2 and the buffer bin 2-3. The metering unit 3 is installed on one side of the second-stage feeding station 2-2 for detecting the bulk density of the material inside the second-stage feeding station 2-2; the electric control system is signal-connected to the pneumatic control valve and is used to control the opening degree of the pneumatic control valve according to the bulk density of the material inside the second-stage feeding station 2-2. By controlling the opening degree of the pneumatic control valve, the feeding speed of the powder can be adjusted.

[0058] A quick-opening gland is arranged at the top of the first-stage feeding station 2-1 as the feeding port for the powder. The quick-opening gland is lined with a sealing strip for locking and sealing after feeding to prevent the gas inside the feeding station from escaping; a stirrer is arranged inside the first-stage feeding station 2-1 for stirring the powder to achieve uniform feeding.

[0059] A gravity feeder is arranged inside the second-stage feeding station 2-2; both the second-stage feeding station 2-2 and the metering unit 3 are installed on independent support frames, and the metering unit 3 is arranged on one side of the sight glass for detecting the bulk density of the material inside the second-stage feeding station 2-2 through the sight glass. By connecting the second-stage feeding station 2-2 to the other bins through buffer sections both above and below, and installing the second-stage feeding station 2-2 and the metering unit 3 on independent support frames, the second-stage feeding station 2-2 and the metering unit can be free from external vibration interference, ensuring the measurement accuracy.

[0060] Sight glasses are installed symmetrically on the side walls of the second-stage feeding station 2-2, the first-stage feeding station 2-1, and the buffer bin 2-3. By observing the feeding situation inside the sight glasses, the opening degree of the pneumatic control valve can be adjusted manually. A vibrator 12 is installed on the outer wall of the buffer bin 2-3. By the action of the vibrator 12 on the outer wall of the buffer bin 2-3, stable feeding can be achieved.

[0061] Specifically, the conveyor is a multi-stage conveyor, including a primary conveyor 4-1 and a secondary conveyor 4-2 connected in sequence; the input port of the primary conveyor 4-1 is connected to the output port of the multi-stage feeding station, the output port of the primary conveyor 4-1 is connected to the input port of the secondary conveyor 4-2, and the output port of the secondary conveyor 4-2 is connected with a fine-tuning controller 5 and an injector 6. The output port of the primary conveyor 4-1 and the input port of the secondary conveyor 4-2 are connected through a third buffer section 11-3; an observation sight glass is installed at the output port of the secondary conveyor 4-2.

[0062] The multi-stage conveyor (including the primary conveyor 4-1 and the secondary conveyor 4-2) can achieve precise control and stable transportation of powder materials during the transportation process. Through multi-stage transportation, multi-stage control can be realized, the flow rate fluctuation caused by the influence of multi-stage bins can be reduced, and at the same time, more complex systems can be dealt with (multi-stage parameter adjustment can effectively cope with the material fluctuation influence caused by various materials and external factors). Compared with the primary conveyor, it has higher precision, better stability and stronger adaptability to various materials, reduces the risk of blockage in the powder feeding system, and through the combined use of "multi-stage screw conveyor + fine-tuning controller 5", by means of segmented control and fine-tuning control of each section of transportation, the continuity and stability can be effectively ensured.

[0063] In a preferred example, the powder particle size is ≥60 mesh and has fluidity. The powder material enters the positive pressure system. The pressure at the front end of the gas phase inlet of the injector 6 is 0.10 - 0.80 mpa, the back pressure at the outlet is 0.01 - 0.15 mpa, and when the pressure difference between the front and back of the injector 6 is 0.09 - 0.65 mpa and there is airflow fluctuation, the powder feeding device can still feed stably and can monitor the feeding amount and historical data in real time;

[0064] Example 2

[0065] This embodiment provides a method for feeding powder into a positive pressure system. Using interlock control, through the coordinated work of the electric control system, the metering unit 3, the pneumatic control valve and the fine-tuning controller 5, precise control of the powder feeding process is achieved. The following are the specific working steps of this method:

[0066] Step 1: The powder is fed. After being stirred in the primary feeding station 2-1, it enters the secondary feeding station 2-2. The stirring is uniform and stable, ensuring that the bulk density during the material pile feeding process is relatively stable.

[0067] Step 2: The metering unit 3 monitors the bulk density inside the secondary feeding station 2-2 in real time. If the density is greater than or less than the preset value, the opening and closing size of the pneumatic control valve at the outlet of the multi-stage bin is controlled. Specifically:

[0068] If the density > preset value: It indicates that there is excessive powder accumulation, which may cause blockage or unsmooth conveying. At this time, the electronic control system controls the third pneumatic control valve 10-3 and the fourth pneumatic control valve 10-4 at the outlet of the secondary feeding station 2-2 to increase the opening degree to accelerate the outflow of the powder; optionally, the electronic control system can also control the first pneumatic control valve 10-1 and the second pneumatic control valve 10-2 at the inlet of the secondary feeding station 2-2 to reduce the opening degree to slow down the inflow of the powder;

[0069] If the density < preset value: It indicates that there is insufficient powder accumulation, which may cause the conveying to be interrupted. At this time, the electronic control system controls the third pneumatic control valve 10-3 and the fourth pneumatic control valve 10-4 at the outlet of the secondary feeding station 2-2 to reduce the opening degree to slow down the outflow of the powder; optionally, the electronic control system can also control the first pneumatic control valve 10-1 and the second pneumatic control valve 10-2 at the inlet of the secondary feeding station 2-2 to increase the opening degree to accelerate the inflow of the powder, so as to control the powder accumulation amount in the secondary feeding station 2-2 within the preset value range (the above control accuracy can be observed through the sight glass on the feeding bin and corrected manually);

[0070] Step 3: The powder enters the multi-stage conveyor after passing through the buffer bin 2-3;

[0071] Step 4: The fine-tuning controller 5 monitors the powder output amount in real time. If the flow rate is greater than or less than the preset value, it controls the operating parameters of the conveyor. Specifically:

[0072] The fine-tuning controller 5 monitors the powder flow rate at the output end of the secondary conveyor 4-2;

[0073] If the flow rate > preset value: It indicates that the powder output is too fast, which may cause unstable system pressure and insufficient reaction. At this time, the fine-tuning controller 5 reduces the operating speed of the secondary conveyor 4-2 through the electronic control system to control the PLC given signal and reduces the motor frequency of the screw conveyor, thereby reducing the rotational speed;

[0074] If the flow rate < preset value: It indicates that the powder output is too slow, which may cause insufficient system feeding. At this time, the fine-tuning controller 5 increases the operating speed of the secondary conveyor 4-2 through the electronic control system to control the PLC given signal and increases the motor frequency of the screw conveyor, thereby increasing the rotational speed; Through the above, ensure that the powder output amount reaches the preset range.

[0075] Embodiment 3

[0076] In this embodiment, aiming at the situation in a conventional positive pressure system where a constant nitrogen pressure is used as a reference to keep the internal pressure of the silo constant, and the nitrogen in the silo enters the system through the feeder with the material, affecting the feeding stability and unable to avoid the leakage of harmful gases in the system, a powder feeding device for a positive pressure system is provided, and a ventilation unit 7 is added. Specifically, the ventilation unit 7 includes a first ventilation pipeline, a second ventilation pipeline, and a third ventilation pipeline; the first ventilation pipeline is used to connect the primary feeding station 2-1, the secondary feeding station 2-2, and the buffer silo 2-3, both ends of the second ventilation pipeline are respectively connected to the primary feeding station 2-1 and the conveyor, and both ends of the third ventilation pipeline are respectively connected to the material pipeline below the fine-tuning controller 5 and the outside; valves are installed on the first ventilation pipeline, the second ventilation pipeline, and the third ventilation pipeline, and the valves are connected to the electric control system.

[0077] In this embodiment, the "operation logic of the ventilation unit 7" is designed separately. The ventilation unit 7 is composed of multiple groups of gas source pipes and valves. The opening and closing actions of each group of valves control the gas flow in the gas source pipeline, and are respectively connected to the multi-stage feeding station, the multi-stage conveyor, the intermediate buffer section, and the fine-tuning controller 5. By controlling the opening or closing of the connecting pipe valves at different feeding stages, the gaseous balance during the feeding process is ensured.

[0078] I. The nitrogen ventilation principle is as follows:

[0079] 1. First ventilation pipeline: When the material is transported from the primary feeding station 2-1 → secondary feeding station 2-2 → buffer silo 2-3, the first ventilation pipeline allows the gas phase to enter the primary feeding station 2-1 from the buffer silo 2-3 and the secondary feeding station 2-2.

[0080] 2. Second ventilation pipeline: When the material enters the multi-stage conveyor from the buffer silo 2-3, and the powder material passes through the primary conveyor 4-1 → secondary conveyor 4-2 and then enters the fine-tuning controller 5, the second ventilation pipeline feeds the gas phase back from the fine-tuning controller 5 and the multi-stage conveyor to the primary feeding station 2-1.

[0081] The opening and closing control of the ventilation pipeline valve is measured by a double-flange differential pressure sensor, and the signal is transmitted to the PLC control module and the electric control system, and the pressure difference value is set. The electric control system controls the opening and closing angle of the ventilation pipeline valve according to the size of the pressure difference, so as to ensure the gaseous balance of the feeding system.

[0082] II. The principle of sealing harmful gases in the system is as follows:

[0083] A pressure transmitter is installed on the pipeline at the lower end of the fine-tuning controller 5, and the signal is transmitted to the PLC electric control unit, and a control value is preset. When the outlet pressure (negative pressure) of the ejector 3 decreases and it is unable to maintain the negative pressure state of the fine-tuning controller 5 or the pressure ≥ the set value. The electric control system opens the valve on the third ventilation pipeline, fills nitrogen from the outside into the material pipeline below the fine-tuning controller 5, and uses airtight sealing to maintain the tightness of the system.

[0084] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0085] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Without conflict, the embodiments of the present application and the features in the embodiments can be arbitrarily combined with each other.

Claims

1. A positive pressure system powder feeding device, characterized in that: It comprises a feeding unit (1), a multi-stage feeding station, a metering unit (3), a conveyor, a fine-tuning controller (6), an ejector (6) and an electronic control system; The loading unit (1) is arranged at one side of the multi-stage feeding station, and the powder is transported to the unloading port at the upper end of the multi-stage feeding station through the loading unit (1). The conveyor is installed at the discharge port of the multi-stage feeding station for discharging the powder; The metering unit (3) is installed on the multi-stage feeding station and is connected to the electronic control system signal, and is used to send the material bulk density signal inside the multi-stage feeding station to the electronic control system; The fine-tuning controller (5) is installed on the ejector (6) connected to the output end of the conveyor and is connected to the electronic control system signal to send a powder discharge signal to the electronic control system; The electric control system is used to adjust the powder feeding rate inside the multi-stage feeding station according to the material bulk density signal inside the multi-stage feeding station, and is used to adjust the powder output of the conveyor according to the powder feeding signal.

2. The positive pressure system powder feeding device according to claim 1, characterized in that: The multi-stage feeding station comprises a primary feeding station (2-1), a secondary feeding station (2-2) and a buffer silo (2-3) which are sequentially connected from top to bottom; Pneumatic control valves are provided between the primary feeding station (2-1) and the secondary feeding station (2-2), and between the secondary feeding station (2-2) and the buffer silo (2-3); the metering unit (3) is installed on one side of the secondary feeding station (2-2) and is used to detect the real-time weight of the material inside the secondary feeding station (2-2) and complete the bulk density calculation; The electric control system is connected to the pneumatic control valve signal and is used to control the opening of the pneumatic control valve according to the material stacking density inside the secondary feeding station (2-2).

3. The positive pressure system powder feeding device according to claim 2, characterized in that: The bottom of the primary feeding station (2-1) is connected to the top of the secondary feeding station (2-2) via a first buffer joint (11-1), and the bottom of the secondary feeding station (2-2) is connected to the top of the buffer silo (2-3) via a second buffer joint (11-2); A first pneumatic control valve (10-1) and a second pneumatic control valve (10-2) are respectively provided at the connection between the first buffer section (11-1) and the first-level feeding station (2-1), and at the connection between the first buffer section (11-1) and the second-level feeding station (2-2); A third pneumatic control valve (10-3) and a fourth pneumatic control valve (10-4) are respectively provided at the connection between the second buffer section (11-2) and the secondary feeding station (2-2), and at the connection between the second buffer section (11-2) and the buffer silo (2-3).

4. The positive pressure system powder feeding device according to claim 2, characterized in that: A quick-opening gland is provided on the top of the first-level feeding station (2-1) as a feeding port for powders, and a sealing strip is lined inside the quick-opening gland for locking and sealing after feeding; A symmetrical sight glass is installed on the side wall of the first-level feeding station (2-1), and a stirrer is arranged inside the first-level feeding station (2-1).

5. The positive pressure system powder feeding device according to claim 2, characterized in that: A symmetrical mirror is installed on the side wall of the secondary feeding station (2-2), and a gravity feeder is arranged inside the secondary feeding station (2-2); The secondary feeding station (2-2) and the metering unit (3) are both installed on an independent support frame, and the metering unit (3) is arranged at the support frame of the secondary feeding station (2-2). The bulk density is calculated by the electric control system and displayed on the control screen.

6. The positive pressure system powder feeding device according to claim 2, characterized in that: A symmetrical sight glass is installed on the side wall of the buffer silo (2-3), and a rapper (12) is installed on the outer wall of the buffer silo (2-3).

7. The positive pressure system powder feeding device according to claim 1, characterized in that: The conveyor is a multi-stage conveyor, comprising a primary conveyor (4-1) and a secondary conveyor (4-2) connected in sequence; The input port of the primary conveyor (4-1) is connected to the output port of the multi-stage feeding station, the output port of the primary conveyor (4-1) is connected to the input port of the secondary conveyor (4-2), and the output port of the secondary conveyor (4-2) is connected to a fine-tuning controller (5) and an ejector (6).

8. The positive pressure system powder feeding device according to claim 7, characterized in that: The output port of the primary conveyor (4-1) and the input port of the secondary conveyor (4-2) are connected via a third buffer joint (11-3); The output port of the secondary conveyor (4-2) is equipped with an observation mirror.

9. The positive pressure system powder feeding device according to claim 2, characterized in that: It also includes a ventilation unit (7), wherein the ventilation unit (7) includes a first ventilation pipeline, a second ventilation pipeline, and a third ventilation pipeline; The first ventilation pipeline is used to connect the primary feeding station (2-1), the secondary feeding station (2-2) and the buffer silo (2-3); the two ends of the second ventilation pipeline are respectively connected to the primary feeding station (2-1) and the conveyor; the two ends of the third ventilation pipeline are respectively connected to the material pipeline below the fine-tuning controller (5) and the outside world; valves are installed on the first ventilation pipeline, the second ventilation pipeline and the third ventilation pipeline, and the valves are connected to the electronic control system.

10. A positive pressure system powder feeding method, characterized in that: The positive pressure system powder feeding device according to any one of claims 1 to 9 comprises the following steps: Step 1: The powder is fed into the primary feeding station (2-1) and stirred before entering the secondary feeding station (2-2); Step 2: The metering unit (3) monitors the bulk density of the material in the secondary feeding station (2-2) in real time. If the density is greater than a preset value, the electronic control system controls the third pneumatic control valve (10-3) and the fourth pneumatic control valve (10-4) at the outlet of the secondary feeding station (2-2) to increase the opening and accelerate the flow of the powder; if the density is less than the preset value, the electronic control system controls the third pneumatic control valve (10-3) and the fourth pneumatic control valve (10-4) at the outlet of the secondary feeding station (2-2) to decrease the opening and slow down the flow of the powder; Step 3: The powder passes through the buffer silo (2-3) and enters the primary conveyor (4-1); Step 4: The fine-tuning controller (5) monitors the powder flow rate at the output end of the secondary conveyor (4-2) in real time. If the flow rate is greater than a preset value, the electronic control system controls the fine-tuning controller (5) to reduce the operating speed of the secondary conveyor (4-2); if the flow rate is less than the preset value: the electronic control system controls the fine-tuning controller (5) to increase the operating speed of the secondary conveyor (4-2).

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