A powder feeding device and method based on pulse ventilation

Abstract

The present invention discloses a powder feeding device and method based on pulse ventilation. The device includes a gas source, three pulse gas flow pipelines, a solenoid valve, a rectangular wave pulse power supply, and a silo system; the solenoid valve includes an inlet and three outlets, the gas source is communicated with the inlet, the first outlet is communicated with the first pulse gas flow pipeline, the second outlet is communicated with the second pulse gas flow pipeline, and the third outlet is communicated with the third pulse gas flow pipeline; the first pulse gas flow pipeline, the second pulse gas flow pipeline, and the third pulse gas flow pipeline are respectively communicated with the silo system; a valve rod is provided in the solenoid valve, and the rectangular wave pulse power supply is used to control the valve rod to realize the communication between the gas source and the first pulse gas flow pipeline, or the communication between the gas source and the second pulse gas flow pipeline, or the communication between the gas source and the third pulse gas flow pipeline. The powder feeding method of the present invention can, on the one hand, reduce the ventilation volume required for the powder feeding flow, and on the other hand, can greatly improve the powder feeding flow rate.

Description

Technical Field

[0001] The present invention relates to a powder feeding device and method based on pulse ventilation. Background Art

[0002] As a unit device for storing and processing powder and granular materials, a silo is widely used in industries such as energy, chemical industry, coal, construction, and food. To ensure the safe and stable operation of these processes, it is of great significance to ensure the high-throughput, stable, and controllable feeding of powder from the silo. However, for ultra-fine powders with small particle sizes and extremely strong adhesiveness, problems such as arching blockage and poor flowability are likely to occur when they are fed from the silo, seriously affecting industrial production and restricting the development of the process.

[0003] In view of the above problems, in the prior art, the flow is mostly promoted by optimizing the silo structure, vibration, or ventilation. In the optimization of the silo structure, in order to ensure smooth feeding, sometimes the design requirements for the silo structure are relatively harsh. For example, for fine particle powders, if designed according to the traditional mass flow silo, a large silo diameter and a steep outer wall of the silo are required, which is difficult to implement. In the method of promoting flow by vibration, improper vibration will cause the powder material to be compacted, making the feeding more difficult, and there are also problems such as high noise and damage to the equipment strength. Ventilation is a popular and important method for strengthening powder flow. Existing ventilation-promoted flow technologies are all based on a constant air flow. This method has a good effect on strengthening the flow of glass microspheres, pulverized coal, grains, etc. with larger particle sizes. However, for adhesive powders with smaller particle sizes, due to the strong inter-particle forces, sometimes even ventilation cannot achieve feeding, or a large ventilation volume is required to achieve arch-breaking flow.

[0004] Therefore, it is necessary to find a powder feeding device based on ventilation that can achieve powder feeding with a small ventilation volume and a fast powder feeding speed. Summary of the Invention

[0005] The present invention provides a powder feeding device and method based on pulse ventilation to solve the problems that the existing flow-promoting technologies are difficult to achieve smooth feeding for adhesive powders with smaller particle sizes, or the ventilation method of the powder feeding device is not flexible enough. On the one hand, the powder feeding method of the present invention can reduce the ventilation volume required for powder feeding flow, and on the other hand, it can greatly improve the powder feeding flow rate, and can achieve high-throughput and stable feeding of particle powders with smaller particle sizes. Moreover, the powder feeding device of the present invention has the advantages of simple structure and easy adjustment.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] The present invention provides a powder feeding device based on pulse ventilation, which comprises a gas source, three pulse gas flow pipelines, a solenoid valve, a rectangular wave pulse power supply and a bin system;

[0008] The solenoid valve comprises an inlet and three outlets. The gas source is communicated with the inlet, the first outlet is communicated with the first pulse gas flow pipeline, the second outlet is communicated with the second pulse gas flow pipeline, and the third outlet is communicated with the third pulse gas flow pipeline;

[0009] The first pulse gas flow pipeline, the second pulse gas flow pipeline and the third pulse gas flow pipeline are respectively communicated with the bin system;

[0010] A valve rod is arranged in the solenoid valve, and the rectangular wave pulse power supply is used to control the valve rod to realize the communication between the gas source and the first pulse gas flow pipeline, or the communication between the gas source and the second pulse gas flow pipeline, or the communication between the gas source and the third pulse gas flow pipeline.

[0011] In the present invention, the gas source can be conventional in the art, generally compressed gas from an air compressor or a gas cylinder, and the gas of the gas source can be compressed air, nitrogen, carbon dioxide, etc.

[0012] In the present invention, preferably, a first energized coil and a second energized coil are arranged in the solenoid valve. After those skilled in the art understand the technical solution of the present invention, they will know that the action state of the valve rod can be controlled by changing the energized and de-energized states of the first energized coil and the second energized coil. The action state of the valve rod generally includes the position, residence time and action frequency of the valve rod. (1) When the first energized coil is in the energized state and the second energized coil is in the de-energized state, the valve rod moves to make the gas source communicate with the first pulse gas flow pipeline; when the first energized coil is in the de-energized state and the second energized coil is in the energized state, the valve rod moves to make the gas source communicate with the second pulse gas flow pipeline; when both the first energized coil and the second energized coil are in the de-energized state, the valve rod moves to make the gas source communicate with the third pulse gas flow pipeline; thus, the position movement of the valve rod is controlled to make the gas source communicate with different independent pulse gas flow pipelines. Since the gas can always be discharged through a certain pulse gas flow pipeline, the pressure surge upstream of the solenoid valve is effectively avoided, and the generated rectangular wave pulse gas flow waveform is stable. (2) The residence time of the valve rod at each position can be controlled by the duration of the energized and de-energized states of the first energized coil and the second energized coil. (3) The action frequency of the valve rod can be controlled by the frequency of the energized and de-energized states of the first energized coil and the second energized coil. (4) According to the performance characteristics of the solenoid valve, the pulse gas flows discharged from different independent pulse gas flow pipelines can generate rectangular waves with different waveform parameters, thereby optimizing the powder feeding mode.

[0013] In the present invention, those skilled in the art will understand after understanding the technical solution of the present invention that each outlet of the solenoid valve is respectively connected to a pulsed gas flow pipeline, so the number of outlets of the solenoid valve is equal to the number of pulsed gas flow pipelines.

[0014] Among them, the solenoid valve is preferably a high-frequency solenoid valve.

[0015] In the present invention, the rectangular wave pulse power supply can be conventional in the art, which refers to a pulse power supply whose output waveform is a rectangular wave.

[0016] Among them, preferably, a first gas flowmeter is provided between the gas source and the inlet, which is used to control and measure the size of the gas flow in the pulsed gas flow pipeline, and more preferably a gas mass flowmeter or a metal float flowmeter, etc.

[0017] In the present invention, the silo system can be a conventional silo system in the art, preferably including a conical hopper and a cylindrical silo; the conical hopper is arranged above the cylindrical silo.

[0018] Among them, preferably, several ventilation rings are provided on the side wall of the conical hopper, and different ventilation rings are at different distances from the bottom of the conical hopper. The first pulsed gas flow pipeline, the second pulsed gas flow pipeline and the third pulsed gas flow pipeline are respectively communicated with the ventilation rings, and the ventilation rings are used to introduce the rectangular wave pulsed gas generated by the first pulsed gas flow pipeline, the second pulsed gas flow pipeline or the third pulsed gas flow pipeline into the silo system.

[0019] Preferably, the axis of the ventilation ring is perpendicular to the axis of the conical hopper. The number of ventilation rings is preferably 1 to 4, and more preferably 3. The first pulsed gas flow pipeline, the second pulsed gas flow pipeline and the third pulsed gas flow pipeline are respectively communicated with 3 ventilation rings.

[0020] Preferably, each ventilation ring is provided with several ventilation holes evenly distributed in the radial direction. The number of ventilation holes on each ventilation ring is preferably 2 to 6, and more preferably 4. Preferably, a sintered porous metal plate is embedded inside the ventilation hole to prevent material leakage.

[0021] Among them, preferably, a butterfly valve is provided at the outlet of the cylindrical silo to control the discharging.

[0022] In the present invention, the powder feeding device preferably further includes a stable air flow pipeline, and the air source is respectively connected to the inlet and the stable air flow pipeline; after the downstream of the stable air flow pipeline converges with the downstream of the first pulsed air flow pipeline, the second pulsed air flow pipeline or the third pulsed air flow pipeline into a single pipeline, it is connected to the silo system, so that pulsed air flow and stable air flow can be used jointly, thereby enabling rich adjustment of the amplitude of the pulsed air flow, and further optimizing the powder feeding method. At this time, the other two pulsed air flow pipelines are respectively connected to the silo system.

[0023] Preferably, a valve is provided on the stable air flow pipeline. Preferably, the valve is a ball valve for controlling the connection state of the stable air flow pipeline.

[0024] Preferably, a second gas flowmeter is provided on the stable air flow pipeline for controlling and measuring the size of the gas flow in the stable air flow pipeline, more preferably a gas mass flowmeter or a metal float flowmeter, etc.

[0025] In a preferred embodiment, the stable air flow pipeline is provided with the valve and the second gas flowmeter connected in sequence.

[0026] Among them, preferably, the air source is connected to a gas storage tank, and the gas storage tank serves to store and buffer gas. The gas storage tank includes at least two gas outlets. The first gas outlet is connected to the inlet, and the second gas outlet is connected to the stable air flow pipeline. Preferably, a first gas flowmeter is provided between the gas storage tank and the inlet.

[0027] The present invention also provides a powder feeding method based on pulsed ventilation, which is carried out by using the powder feeding device based on pulsed ventilation as described above, and its steps include:

[0028] Turn on the powder feeding device, ventilate the silo system through the air source and the pulsed air flow pipeline, and open the outlet for feeding in the silo system, and that's it.

[0029] Among them, the duty cycle of the rectangular wave pulsed air flow of the powder feeding device is 10-90%;

[0030] The frequency of the rectangular wave pulsed air flow is 0-200 Hz;

[0031] The instantaneous gas flow of the rectangular wave pulsed air flow is 0-160 L / min.

[0032] In the present invention, preferably, the method for adjusting the duty cycle of the rectangular wave pulsed air flow is to adjust the on-off interval time of the rectangular wave pulsed power supply and adjust the time when the first pulsed air flow pipeline, the second pulsed air flow pipeline or the third pulsed air flow pipeline is connected, and its rule conforms to:

[0033] D 1 = t 1 / T, D 2 = t 2 / T, D 3 = t 3 / T, T = t 1 + t 2 + t 3 ;

[0034] D 1 、D 2 、D 3 are respectively the duty cycles of the rectangular wave pulse airflows in the first pulse air flow pipeline, the second pulse air flow pipeline, and the third pulse air flow pipeline. T is the time of a single cycle, and t 1 is the time when the first pulse air flow pipeline is connected within a single cycle, that is, the time when the position of the valve stem maintains the opening of the first outlet; t 2 is the time when the second pulse air flow pipeline is connected within a single cycle; t 3 is the time when the third pulse air flow pipeline is connected within a single cycle.

[0035] In the present invention, preferably, the method for adjusting the frequency of the rectangular wave pulse air flow is to adjust the pulse frequency of the rectangular wave pulse power supply.

[0036] Those skilled in the art know that the valve stems of different solenoid valves have different maximum operating frequencies. When the pulse frequency of the rectangular wave pulse power supply is not higher than the maximum operating frequency of the valve stem, the frequency of the rectangular wave pulse air flow is equal to the frequency of the rectangular wave pulse power supply and is equal to the operating frequency of the valve stem; when the pulse frequency of the rectangular wave pulse power supply is higher than the maximum operating frequency of the valve stem, the frequency of the rectangular wave pulse air flow is equal to the maximum operating frequency of the valve stem. Among them, the operating frequency f of the valve stem = 1 / T.

[0037] In the present invention, preferably, the method for adjusting the amplitude of the rectangular wave pulse air flow (the amplitude refers to the maximum value of the wave function of the rectangular wave pulse air flow deviating from the equilibrium position) is as follows:

[0038] When only the pulse air flow pipeline is connected, such that the average gas flow rate q of the pulse air flow pipeline 1 is 0 to 160 L / min (when a first gas flow meter is provided between the gas source and the inlet, it can be adjusted by adjusting the first gas flow meter); by adjusting the operating frequency f of the valve stem to 0 to 200 Hz, the instantaneous gas flow rate q of the rectangular wave pulse air flow and q 1 and the numerical relationship of f is q = q 1 / 2 + q 1sgn[sin(2πft)] / 2; where q 1 is the average gas flow rate of the pulsed gas pipeline, f is the action frequency of the valve stem, and t is time. According to the above function, the wave function of the pulsed gas generated by the pulsed gas pipeline oscillates within the range of 0 to q 1 with an amplitude of q 1 / 2;

[0039] When the gas source is connected to the inlet and the stable gas pipeline respectively, and the downstream of the stable gas pipeline converges with the downstream of the first pulsed gas pipeline, the second pulsed gas pipeline or the third pulsed gas pipeline into one path, the average gas flow rate q of the pulsed gas pipeline 1 is 0 to 160 L / min (when a first gas flowmeter is provided between the gas source and the inlet, it can be adjusted by adjusting the first gas flowmeter); by adjusting the action frequency f of the valve stem to 0 to 200 Hz; the gas flow rate q of the stable gas pipeline 2 is 0 to 160 L / min (when a second gas flowmeter is provided on the stable gas pipeline, it can be adjusted by adjusting the second gas flowmeter); the instantaneous gas flow rate q of the rectangular wave pulsed gas and q 1 、q 2 and f are numerically related as q = (q 1 / 2 + q 2 ) + q 1 sgn[sin(2πft)] / 2; where q 1 is the average gas flow rate of the pulsed gas pipeline, q 2 is the gas flow rate of the stable gas pipeline, f is the action frequency of the valve stem, and t is time. According to the above function, the wave function of the generated pulsed gas oscillates within the range of q 2 to q 1 + q 2 with an amplitude of q 1 / 2.

[0040] In the present invention, the powder feeding device is applicable to powder flow systems in different technological processes. The powder is preferably an adhesive powder such as pulverized coal, aluminum powder, alumina powder, calcium carbonate powder, etc.

[0041] In the present invention, preferably, the particle size range of the powder is preferably 0.1 - 200 μm, more preferably 0.1 - 50 μm, and even more preferably 0.1 - 10 μm. The powder feeding and flow promoting effect for the powder with a particle size range of 0.1 - 10 μm is particularly significant. The particle size referred to here is d 32 , that is, the Sauter mean diameter, which is calculated assuming that all particles of the sample have the same specific surface area.

[0042] On the basis of conforming to the common knowledge in the art, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0043] The positive effects of the present invention are as follows:

[0044] (1) The blanking device and method of the present invention use rectangular wave pulse airflow for blanking. On the one hand, it can reduce the amount of fluidizing gas required for powder blanking flow, and on the other hand, it can greatly improve the powder blanking flow rate. Compared with the constant airflow, the rectangular wave pulse airflow has a greater impact force and a stronger entrainment effect, which can improve the mass transfer and transmission efficiency. When the pulsed airflow enters the bed layer, it will produce an oscillating effect, thereby improving the arch-breaking efficiency. The disturbance of the pulsed airflow will also break the agglomeration structure between particles, reduce the intensity of the force between particles, and improve the fluidity of the powder. In the blanking device of the present invention, the pulsed ventilation branch and the corresponding pulsed airflow parameters can be selected as needed, realizing the flexible adjustment of various parameters in the blanking device.

[0045] (2) Moreover, the pulsed airflow can be pulsed ventilated from different positions of the silo, which can arrange the ventilation positions more flexibly, and can also be used in combination with the stable airflow to produce a better flow-promoting effect. Description of the Drawings

[0046] Figure 1 Schematic diagram of the pulsed ventilation silo blanking device for Example 1.

[0047] Figure 2 Results of pulsed ventilation powder blanking flow strengthening for Example 2.

[0048] Figure 3 Results of pulsed ventilation powder blanking flow strengthening for Example 3.

[0049] Figure 4 Results of pulsed ventilation powder blanking flow strengthening for Example 4.

[0050] Figure 5 Blanking flow strengthening effects for Examples 2 to 4.

[0051] Description of the Reference Numerals

[0052] Gas source 1

[0053] First pulsed airflow pipeline 2

[0054] Second pulsed airflow pipeline 3

[0055] Third pulsed airflow pipeline 4

[0056] Solenoid valve 5

[0057] Rectangular wave pulse power supply 6

[0058] Inlet 7

[0059] First outlet 8

[0060] Second outlet 9

[0061] Third outlet 10

[0062] Valve stem 11

[0063] First gas flowmeter 12

[0064] Stable air flow pipeline 13

[0065] Ball valve 14

[0066] Second gas flowmeter 15

[0067] Gas storage tank 16

[0068] Bunker system 17

[0069] Conical hopper 18

[0070] Vent hole 19

[0071] Cylindrical silo 20

[0072] Butterfly valve 21 Detailed implementation mode

[0073] The present invention will be further described below by way of embodiments, but the present invention is not limited to the scope of the described embodiments. For the experimental methods without specific conditions in the following embodiments, they are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0074] Embodiment 1

[0075] As Figure 1 shown, this embodiment provides a powder feeding device based on pulsed ventilation, which includes a gas source 1, three pulsed air flow pipelines, a solenoid valve 5, a rectangular wave pulse power supply 6 and a bunker system 17; the solenoid valve 5 includes an inlet 7 and three outlets, the gas source 1 is connected to the inlet 7, the first outlet 8 is connected to the first pulsed air flow pipeline 2, the second outlet 9 is connected to the second pulsed air flow pipeline 3, and the third outlet 10 is connected to the third pulsed air flow pipeline 4.

[0076] The powder feeding device further includes a stable air flow pipeline 13, and the gas source 1 is respectively connected to the inlet 7 and the stable air flow pipeline 13; after the downstream of the stable air flow pipeline 13 and the downstream of the third pulsed air flow pipeline 4 converge into one pipeline, they are connected to the bunker system 17, so that the pulsed air flow and the stable air flow can be used jointly, thereby being able to richly adjust the amplitude of the pulsed air flow, and further optimizing the powder feeding mode. At this time, the first pulsed air flow pipeline 2 and the second pulsed air flow pipeline 3 are directly connected to the bunker system 17.

[0077] The solenoid valve 5 is provided with a valve stem 11, and the rectangular wave pulse power supply 6 is used to control the valve stem 11 to realize the connection between the gas source 1 and the first pulsed gas flow pipeline 2, or the connection between the gas source 1 and the second pulsed gas flow pipeline 3, or the connection between the gas source 1 and the third pulsed gas flow pipeline 4.

[0078] The gas of the gas source 1 can be compressed air, nitrogen, carbon dioxide, etc.

[0079] The solenoid valve 5 is provided with a first energized coil and a second energized coil. By changing the on-off states of the first energized coil and the second energized coil, the action state of the valve stem 11 can be controlled. The action state of the valve stem 11 generally includes the position, residence time and action frequency of the valve stem 11. (1) When the first energized coil is in the energized state and the second energized coil is in the de-energized state, the valve stem 11 moves to connect the gas source 1 with the first pulsed gas flow pipeline 2; when the first energized coil is in the de-energized state and the second energized coil is in the energized state, the valve stem 11 moves to connect the gas source 1 with the second pulsed gas flow pipeline 3; when both the first energized coil and the second energized coil are in the de-energized state, the valve stem 11 moves to connect the gas source 1 with the third pulsed gas flow pipeline 4; thus, the position movement of the valve stem 11 is controlled to connect the gas source 1 with different independent pulsed gas flow pipelines. Since the gas can always be discharged through a certain pulsed gas flow pipeline, the pressure surge upstream of the solenoid valve 5 is effectively avoided, and the generated rectangular wave pulsed gas flow waveform is stable. (2) The on-off duration of the first energized coil and the second energized coil can control the residence time of the valve stem 11 at each position. (3) The on-off frequency of the first energized coil and the second energized coil can control the action frequency of the valve stem 11. (4) The pulsed gas flows discharged from different independent pulsed gas flow pipelines can generate rectangular waves with different waveform parameters according to the performance characteristics of the solenoid valve 5, thereby optimizing the powder feeding method.

[0080] Each outlet of the solenoid valve 5 is respectively connected to a pulsed gas flow pipeline, so the number of outlets of the solenoid valve 5 is equal to the number of pulsed gas flow pipelines.

[0081] Among them, the solenoid valve 5 is a high-frequency solenoid valve 5.

[0082] The rectangular wave pulse power supply 6 refers to a pulse power supply whose output waveform is a rectangular wave.

[0083] Among them, a first gas flowmeter 12 is provided between the gas source 1 and the inlet 7, which is used to control and measure the size of the gas flow in the pulsed gas flow pipeline and is a gas mass flowmeter.

[0084] The bin system 17 includes a conical hopper 18 and a cylindrical silo 20; the conical hopper 18 is arranged above the cylindrical silo 20.

[0085] Among them, three ventilation rings are provided on the side wall of the conical hopper 18. The distances between different ventilation rings and the bottom of the conical hopper 18 are different. The axis of the ventilation ring is perpendicular to the axis of the conical hopper 18. The first pulse gas pipeline 2 is communicated with the uppermost ventilation ring, the second pulse gas pipeline 3 is communicated with the middle ventilation ring, and the third pulse gas pipeline 4 is communicated with the lowermost ventilation ring. Each ventilation ring is provided with four ventilation holes 19 evenly distributed in the radial direction. A sintered porous metal plate is embedded inside the ventilation hole 19 to prevent material leakage.

[0086] Among them, a butterfly valve 21 is provided at the outlet of the cylindrical silo 20 to control the discharging.

[0087] A ball valve 14 is provided on the stable gas pipeline 13 to control the connection state of the stable gas pipeline 13.

[0088] A second gas flowmeter 15 is provided on the stable gas pipeline 13 to control and measure the gas flow rate of the stable gas pipeline 13, which is a gas mass flowmeter.

[0089] The stable gas pipeline 13 is provided with a ball valve 14 and a second gas flowmeter 15 connected in sequence.

[0090] Among them, the gas source 1 is connected to the gas storage tank 16. The gas storage tank 16 plays a role in storing and buffering gas. The gas storage tank 16 includes at least two gas outlets. The first gas outlet is connected to the inlet 7, and the second gas outlet is connected to the stable gas pipeline 13. A first gas flowmeter 12 is provided between the gas storage tank 16 and the inlet 7.

[0091] Embodiment 2

[0092] In this embodiment, the powder material is pulverized coal with an average particle size of 15 μm, and a square-wave pulse gas flow is used for ventilation and discharging test. The discharging flow rate results at different average ventilation volumes and different pulse frequencies are obtained. As Figure 2 shown, by using the square-wave pulse ventilation method and only using the rectangular-wave pulse gas flow of the third pulse gas pipeline 4, when the pulse frequency is 50 Hz and the duty cycle = 50%, the gas volume required to trigger powder flow can be reduced from 2 L / min during stable ventilation to 0.75 L / min during pulse ventilation; the maximum discharging flow rate that can be achieved by pulse ventilation is about 180 g / s, which is about 20% higher than that of constant ventilation.

[0093] Embodiment 3

[0094] In this embodiment, the powder material is calcium carbonate powder with an average particle size of 5 μm, and a square-wave pulse gas flow is used for ventilation and discharging test. The discharging flow rate results at different average ventilation volumes and different pulse frequencies are obtained. As Figure 3As shown, the square-wave pulse ventilation method is adopted, and only the rectangular-wave pulse air flow of the third pulse air flow pipeline 4 is used. When the pulse frequency is 50 Hz and the duty cycle = 50%, the maximum blanking flow rate that can be achieved by pulse ventilation is about 140 g / s, which is about 15% higher than that of constant ventilation.

[0095] Example 4

[0096] In this example, the powder material is alumina powder with an average particle size of 5 μm, and a rectangular-wave pulse air flow with different duty cycles is used for ventilation blanking tests. The blanking flow rate results at different average ventilation volumes, different pulse frequencies, and duty cycles are obtained. As Figure 4 shown, the pulse ventilation method is adopted, and only the rectangular-wave pulse air flow of the third pulse air flow pipeline 4 is used. When the pulse frequency is 50 Hz, the maximum blanking flow rate that can be achieved by low-duty-cycle pulse ventilation is about 250 g / s, which is about 230% higher than that of constant ventilation.

[0097] As Figure 5 shown, based on the results of the above examples, the better effect of the pulse ventilation method proposed by the present invention compared with the traditional stable ventilation method is compared.

[0098] The powder blanking device and method proposed by the present invention can strengthen the powder flow with less gas consumption, effectively improve the powder blanking flow rate, and achieve high-throughput, stable, and controllable powder transportation. The technology proposed by the present invention can break through the gas volume requirements of some process environments, which provides a broader application prospect for the development of powder flow processes.

Claims

1. A powder feeding device based on pulse ventilation, characterized in that, it includes a gas source, three pulse gas pipelines, a solenoid valve, a rectangular wave pulse power supply and a silo system; The solenoid valve includes an inlet and three outlets. The gas source is connected to the inlet, the first outlet is connected to the first pulse gas pipeline, the second outlet is connected to the second pulse gas pipeline, and the third outlet is connected to the third pulse gas pipeline; The first pulse gas pipeline, the second pulse gas pipeline and the third pulse gas pipeline are respectively connected to the silo system; A valve rod is provided in the solenoid valve, and the rectangular wave pulse power supply is used to control the valve rod to realize the connection between the gas source and the first pulse gas pipeline, or the connection between the gas source and the second pulse gas pipeline, or the connection between the gas source and the third pulse gas pipeline; The powder feeding device further includes a stable gas pipeline. The gas source is respectively connected to the inlet and the stable gas pipeline; The downstream of the stable gas pipeline and the downstream of the third pulse gas pipeline converge into a pipeline and are connected to the silo system.

2. The powder feeding device based on pulse ventilation according to claim 1, characterized in that, The gas of the gas source is compressed air, nitrogen or carbon dioxide; and / or, a first energized coil and a second energized coil are provided in the solenoid valve; and / or, the solenoid valve is a high-frequency solenoid valve.

3. The powder feeding device based on pulse ventilation according to claim 1, characterized in that, A first gas flowmeter is provided between the gas source and the inlet.

4. The powder feeding device based on pulse ventilation according to claim 3, characterized in that, The first gas flowmeter is a gas mass flowmeter or a metal float flowmeter.

5. The powder feeding device based on pulse ventilation according to claim 3, characterized in that, A valve is provided on the stable gas pipeline; A second gas flowmeter is provided on the stable gas pipeline; and / or, the gas source is connected to a gas storage tank. The gas storage tank includes at least 2 gas outlets. The first gas outlet is connected to the inlet, and the second gas outlet is connected to the stable gas pipeline.

6. The powder feeding device based on pulse ventilation according to claim 5, characterized in that, The valve is a ball valve; and / or, the second gas flowmeter is a gas mass flowmeter or a metal float flowmeter; and / or, the stable gas pipeline is provided with the valve and the second gas flowmeter connected in sequence.

7. The powder feeding device based on pulse ventilation according to claim 5, characterized in that, The first gas flowmeter is provided between the gas storage tank and the inlet.

8. The powder feeding device based on pulse ventilation according to claim 1, characterized in that, The silo system includes a conical hopper and a cylindrical silo; The conical hopper is arranged above the cylindrical silo.

9. The powder feeding device based on pulse ventilation according to claim 8, characterized in that, A plurality of ventilation rings are provided on the side wall of the conical hopper. Different ventilation rings are at different distances from the bottom of the conical hopper. The first pulsed air flow pipeline, the second pulsed air flow pipeline, and the third pulsed air flow pipeline are respectively communicated with the ventilation rings. The ventilation rings are used to introduce the rectangular wave pulsed air flow generated by the first pulsed air flow pipeline, the second pulsed air flow pipeline, or the third pulsed air flow pipeline into the silo system.

10. The powder feeding device based on pulsed ventilation according to claim 9, characterized in that, the axis of the ventilation ring is perpendicular to the axis of the conical hopper; the number of the ventilation rings is 1 to 4; each ventilation ring is provided with a plurality of ventilation holes evenly distributed in the radial direction; a butterfly valve is provided at the outlet of the cylindrical silo.

11. The powder feeding device based on pulsed ventilation according to claim 10, characterized in that, the number of the ventilation rings is 3, and the first pulsed air flow pipeline, the second pulsed air flow pipeline, and the third pulsed air flow pipeline are respectively communicated with 3 ventilation rings; and / or, the number of the ventilation holes on each ventilation ring is 2 to 6; and / or, a sintered porous metal plate is embedded inside the ventilation hole.

12. The powder feeding device based on pulsed ventilation according to claim 11, characterized in that, the number of the ventilation holes on each ventilation ring is 4.

13. A powder feeding method based on pulsed ventilation, characterized in that, it is carried out by using the powder feeding device based on pulsed ventilation described in any one of claims 1-12, and its steps include: Turn on the powder feeding device, ventilate the silo system through the air source and the pulsed air flow pipeline, and open the outlet for feeding in the silo system. Among them, the duty ratio of the rectangular wave pulsed air flow of the powder feeding device is 10 to 90%; the frequency of the rectangular wave pulsed air flow is 0 to 200 Hz; the instantaneous gas flow rate of the rectangular wave pulsed air flow is 0 to 160 L / min.

14. The powder feeding method based on pulsed ventilation according to claim 13, characterized in that, the method for adjusting the duty ratio of the rectangular wave pulsed air flow is to adjust the on-off interval time of the rectangular wave pulsed power supply and adjust the time when the first pulsed air flow pipeline, the second pulsed air flow pipeline, or the third pulsed air flow pipeline is communicated. Its rule conforms to: ； D 1 , D 2 , D 3 are the duty cycles of the rectangular wave pulse airflows in the first pulse airflow pipeline, the second pulse airflow pipeline, and the third pulse airflow pipeline respectively, T is the time of a single cycle, t 1 is the time when the first pulse airflow pipeline is connected within a single cycle; t 2 is the time when the second pulse airflow pipeline is connected within a single cycle; t 3 is the time when the third pulse airflow pipeline is connected within a single cycle.

15. The powder feeding method based on pulsed ventilation according to claim 13, characterized in that, the method for adjusting the frequency of the rectangular wave pulsed air flow is to adjust the pulse frequency of the rectangular wave pulsed power supply.

16. The powder feeding method based on pulsed ventilation according to claim 13, characterized in that, the method for adjusting the amplitude of the rectangular wave pulsed air flow is as follows: When only the pulsed air flow pipeline is connected, so that the average gas flow rate of the pulsed air flow pipeline q 1 is 0 - 160 L / min; by adjusting the action frequency of the valve stem f to be 0 - 200 Hz, the instantaneous gas flow rate of the rectangular wave pulsed air flow q and q 1 and f have a numerical relationship of ; where q 1 is the average gas flow rate of the pulsed air flow pipeline, f is the action frequency of the valve stem, t is time; When the gas source is connected to the inlet and the stable gas flow pipeline respectively, after the downstream of the stable gas flow pipeline and the downstream of the third pulsed gas flow pipeline converge into one path, the average gas flow rate of the pulsed gas flow pipeline q 1 is 0 - 160 L / min; by adjusting the action frequency of the valve stem f is 0 - 200 Hz; so that the gas flow rate of the stable gas flow pipeline q 2 is 0 - 160 L / min; the instantaneous gas flow rate of the rectangular wave pulsed gas flow q and q 1 、 q 2 and f The numerical relationship is ; where q 1 is the average gas flow rate of the pulsed gas flow pipeline, q 2 is the gas flow rate of the stable gas flow pipeline, f is the action frequency of the valve stem, t is time.

Images