Particle closed-loop conveying system and control method thereof

Abstract

The present invention provides a closed-loop particle conveying system and a control method thereof. The closed-loop particle conveying system includes: a buffer tank provided with a discharge pipe, the discharge pipe having an outer end portion located outside the buffer tank and an inner end portion located inside the buffer tank and adjacent to the bottom of the buffer tank; a pumping tank connected to the outer end portion of the discharge pipe via a feed pipe, the feed pipe being provided with a feed switching valve; and a reversing valve having an input port connected to the pumping tank via an exhaust pipe, a first output port connected to the atmosphere, and a second output port connected to the outer end portion of the discharge pipe via a return air pipe, the reversing valve being configured to connect the input port to either the first output port or the second output port; the exhaust pipe being provided with an air pump for discharging air from the pumping tank; and the return air pipe being provided with a cooling and drying unit for cooling and drying the air.

Description

Technical Field

[0001] The present invention relates to the technical field of particle production, and more particularly to a particle closed-loop conveying system and a control method thereof. Background Art

[0002] Thermoplastic rubber and elastomer pellets are common raw materials in the chemical industry. These pellets are often produced at high temperatures and dried after production. The dried pellets are then transferred to a cooling facility via pneumatic conveying or other means. After cooling in the cooling facility, they are then transferred to storage silos or packaging lines. However, existing pneumatic conveying processes transfer the hot air generated in the pre-drying process along with the pellets. This hot air, when cooled in the cooling facility, causes the water vapor contained in the air to condense into moisture. Moisture-sensitive pellets may absorb this moisture, forcing subsequent processing using these pellets to proceed only after they have been dried again. Furthermore, since the hot air is transferred along with the pellets, they remain at high temperatures during transfer. This can cause deformation and clumping of temperature-sensitive pellets during transfer, hindering subsequent processing using these pellets. Consequently, existing pneumatic conveying processes are unsatisfactory for transferring temperature-sensitive and moisture-sensitive pellets, particularly those that are both temperature-sensitive and moisture-sensitive.

[0003] Therefore, in this field, there is an urgent need for a technical solution that can transfer and cool particles in a low temperature and dry environment. Summary of the Invention

[0004] In order to solve the above-mentioned problems in the prior art, the present invention proposes an improved closed-loop particle conveying system, which includes: a buffer tank, the buffer tank is provided with a discharge pipe, the discharge pipe has an outer end portion outside the buffer tank and an inner end portion inside the buffer tank and adjacent to the bottom of the buffer tank; a suction tank connected to the outer end portion of the discharge pipe through a delivery pipe, the delivery pipe is provided with a delivery switching valve; and a reversing valve, the reversing valve has an input port connected to the suction tank through an exhaust pipe, a first output port connected to the atmosphere, and a second output port connected to the outer end portion of the discharge pipe through a return air pipe, and the reversing valve has a first valve position connecting the input port with the first output port and a second valve position connecting the input port with the second output port, and wherein the exhaust pipe is provided with an air pump for discharging air in the suction tank, and the return air pipe is provided with a cooling and drying unit for cooling and drying the air.

[0005] According to an optional embodiment of the present invention, the closed-loop particle conveying system further includes a cooling tank connected below the extraction tank and a discharge switching valve provided between the extraction tank and the cooling tank.

[0006] According to an optional embodiment of the present invention, the exhaust duct is further provided with an upstream air filter, and the upstream air filter is located between the extraction tank and the air pump.

[0007] According to an optional embodiment of the present invention, the return air duct is further provided with a downstream air filter, and the downstream air filter is located between the outer end of the discharge duct and the cooling and drying unit.

[0008] According to an optional embodiment of the present invention, the cooling and drying unit includes a cooler and a steam-water separator connected together.

[0009] According to an optional embodiment of the present invention, the discharge pipe extends from an outer end portion thereof through the top of the buffer tank to an inner end portion thereof.

[0010] According to an optional embodiment of the present invention, the bottom of the buffer tank is in a conical shape that slopes downward as it approaches the center, and the inner end of the discharge pipe is adjacent to the center of the bottom of the buffer tank.

[0011] According to an optional embodiment of the present invention, the feed pipe leads to the interior of the suction tank through a side wall opening in the side wall of the suction tank, and the exhaust pipe leads to the interior of the suction tank through a top opening in the top of the suction tank.

[0012] According to an optional embodiment of the present invention, the side wall opening is adjacent to the bottom of the extraction tank.

[0013] According to an optional embodiment of the present invention, the side wall opening is spaced apart from the bottom of the extraction tank.

[0014] In order to solve the above-mentioned problems in the prior art, the present invention also proposes an improved control method for controlling the particle closed-loop conveying system as described herein, and comprising the following steps:

[0015] S100: closing the feed switch valve and placing the reversing valve in the first valve position;

[0016] S200: operating the air pump at a first power;

[0017] S300: Opening the feed switch valve and placing the reversing valve in the second valve position;

[0018] S400: operating the air pump at a second power, wherein the second power is less than the first power; and

[0019] S500: Return to step S100.

[0020] According to an optional embodiment of the present invention, the control method further comprises: executing step S200 until the vacuum degree in the extraction tank reaches a predetermined upper limit, or until a first predetermined time period is reached.

[0021] According to an optional embodiment of the present invention, the control method further comprises: executing step S400 until the vacuum degree in the extraction tank reaches a predetermined lower limit, or until a second predetermined time is reached, or until the amount of particles in the extraction tank reaches a predetermined amount.

[0022] According to an optional embodiment of the present invention, step S100 further comprises: closing the discharge switch valve; and the control method further comprises step S401 between steps S400 and S500: opening the discharge switch valve.

[0023] According to an optional implementation manner of the present invention, the second power is set to zero.

[0024] The present invention can be embodied as the exemplary embodiments in the accompanying drawings. However, it should be noted that the drawings are merely exemplary and any changes conceivable under the teachings of the present invention should be considered to be included within the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings illustrate exemplary embodiments of the present invention. These drawings should not be interpreted as necessarily limiting the scope of the present invention, in which:

[0026] Figure 1 is a schematic layout diagram of a closed-loop particle conveying system according to an optional embodiment of the present invention; and

[0027] Figure 2 is a schematic flow chart of a control method according to an optional embodiment of the present invention. DETAILED DESCRIPTION

[0028] Further features and advantages of the present invention will become more apparent from the following description with reference to the accompanying drawings. Exemplary embodiments of the present invention are shown in the accompanying drawings, and the various drawings are not necessarily drawn to actual scale. However, the present invention may be implemented in many different forms and should not be construed as necessarily being limited to the exemplary embodiments disclosed herein. On the contrary, these exemplary embodiments are merely provided to illustrate the present invention and to convey the spirit and essence of the present invention to those skilled in the art.

[0029] As mentioned above, temperature-sensitive particles may be squeezed, deformed, and clumped together due to being in a high-temperature environment, and moisture-sensitive particles may absorb moisture due to being in a humid environment. For example, some rubber elastomer particles still have unreacted functional groups in their molecular chains, and moisture can easily react with their functional groups to change the bulk structure and properties of the substance. Whether it is deformation, adhesion, agglomeration, or water absorption, it may cause the subsequent production and processing using these particles as raw materials to be unable to proceed smoothly, and even cause these production and processing to have to start after the particles are reshaped and dehumidified. The present invention aims to propose a particle closed-loop conveying system with a novel design for conveying particles. The novel design of the particle closed-loop conveying system according to the present invention enables it to reduce the temperature and humidity of the particle conveying gas during the process of conveying and storing particles. That is to say, the particle closed-loop conveying system according to the present invention can use a gas with a suitable temperature (even low temperature) and dryness to convey and store particles. Therefore, the closed-loop particle conveying system according to the present invention is particularly suitable for conveying temperature-sensitive particles, moisture-sensitive particles, and especially particles that are both temperature-sensitive and moisture-sensitive. This is because the closed-loop particle conveying system according to the present invention can effectively prevent these particles from deforming, absorbing water, or sticking together during the transportation and storage process, which helps to omit the steps of reshaping and dehumidifying these particles, thereby not only reducing the cost of subsequent production and processing, but also ensuring the smooth progress of subsequent production and processing.

[0030] An alternative but non-limiting embodiment of the closed-loop particle conveying system according to the present invention will be described in detail below with reference to the accompanying drawings.

[0031] refer to Figure 1 , which shows a schematic layout diagram of a closed-loop particle conveying system according to an optional embodiment of the present invention. Figure 1As shown, the closed-loop pellet conveying system 10 includes a buffer tank 100 connected to a pellet production facility for storing pellets produced by the pellet production facility (not shown) and transported via a pipeline (not shown). For example, the buffer tank 100 may have an opening at its top for receiving pellets, which is connected to the pellet production facility located above the buffer tank 100 via a pipeline. The pellets produced by the pellet production facility can fall into the buffer tank 100 through the pipeline under the action of their own gravity and gradually accumulate upward from the bottom of the buffer tank 100. Generally, the production environment in the pellet production facility may involve high temperature and high humidity. Therefore, the pellets may enter the buffer tank 100 along with hot and humid air. This air may be stored in the buffer tank 100 along with the pellets, wherein the pellets are deposited at the bottom of the buffer tank 100, the majority of the air is located above the pellets, and a small portion of air is located in the spaces between the pellets. In other words, in the buffer tank 100, the pellets may be stored in a hot and humid gas.

[0032] In order to cool the pellets for subsequent packaging and sales or subsequent production and processing using these pellets as raw materials, such as Figure 1 As shown, the buffer tank 100 is provided with a discharge pipe L10, which extends from the outside of the buffer tank 100 (e.g., through the top of the buffer tank 100) to the inside of the buffer tank 100 and to near the bottom of the buffer tank 100. In other words, the discharge pipe L10 has an outer end L11 located outside the buffer tank 100 and an inner end L12 located inside the buffer tank 100, and the inner end L12 is adjacent to the bottom of the buffer tank 100. In this configuration, particles deposited at the bottom of the buffer tank 100 can be sucked into the discharge pipe L10 through the inner end L12 of the discharge pipe L10, then transported by the discharge pipe L10 to the outer end L11 thereof, and finally discharged from the discharge pipe L10 through the outer end L11. In short, the discharge pipe L10 can suck particles in the buffer tank 100 through its inner end L12 and then discharge the particles through its outer end L11.

[0033] The particle closed-loop conveying system 10 also includes a suction tank 200, a cooling tank 300 located below the suction tank 200 and connected to the suction tank 200, and a delivery pipe L20 connecting the suction tank 200 to the outer end L11 of the discharge pipe L10, wherein a delivery switch valve V10 is provided on the delivery pipe L20, and the delivery switch valve V10 is used to selectively open and close the delivery pipe L20. In this configuration, if the feed switching valve V10 is opened, the feed pipeline L20 will be opened, so that the particles discharged from the outer end L11 of the discharge pipeline L10 can be transported to the extraction tank 200 through the feed pipeline L20; if the feed switching valve V10 is closed, the feed pipeline L20 will be cut off, as described in more detail below, which enables back pressure or vacuum to be established in the extraction tank 200, and this back pressure or vacuum helps to draw the particles in the buffer tank 100 into the extraction tank 200 through the feed pipeline L20.

[0034] The particle closed-loop conveying system 10 also includes a reversing valve V20 in the form of a two-position three-way valve, wherein the reversing valve V20 has an input port V21 and two output ports, namely a first output port V22 and a second output port V23, and wherein the input port V21 is connected to the extraction tank 200 through an exhaust pipe L30, the first output port V22 is connected to the outer end L11 of the discharge pipe L10 through a return air pipe L40, and the second output port V23 is connected to the atmosphere. The reversing valve V20 can switch between a first position and a second position. In the first position, the input port V21 communicates with the first output port V22, while the second output port V23 is blocked. This allows the exhaust duct L30 to communicate with the atmosphere through the first output port V22, but not with the return duct L40. In the second position, the input port V21 communicates with the second output port V23, while the first output port V22 is blocked. This allows the exhaust duct L30 to communicate with the return duct L40 through the second output port V23, but not with the atmosphere. Therefore, the reversing valve V20 can selectively connect the exhaust duct L30 to either the atmosphere or the return duct L40.

[0035] The closed-loop particle conveying system 10 further includes an air pump 400 disposed on the exhaust duct L30 and a cooling and drying unit 500 disposed on the return duct L40. The air pump 400 is configured to exhaust air from the extraction tank 200, and the cooling and drying unit 500 is configured to cool and dry the air flowing therethrough. Specifically, the cooling and drying unit 500 may include a cooler, such as a water-cooled type, located upstream and a steam-water separator located downstream, connected together.

[0036] During use, the particles in the buffer tank 100 can be transferred to the extraction tank 200 by alternately performing the vacuum establishment and vacuum breaking steps multiple times. Specifically, after a certain amount of particles is stored in the buffer tank 100, the vacuum establishment step is performed. In this step, the feed switching valve V10 is closed, and the reversing valve V20 is adjusted to the first valve position to cut off the feed pipeline L20 and connect the exhaust pipeline L30 to the atmosphere. Then, the air pump 400 is started to enable the air pump 400 to extract the air in the extraction tank 200 and discharge the air into the atmosphere, thereby establishing a vacuum in the extraction tank 200. After the vacuum degree in the extraction tank 200 reaches the required level, the step of breaking the vacuum is performed. In this step, the feed switching valve V10 is opened, and the reversing valve V20 is adjusted to the second valve position so that the feed pipeline L20 is opened, and the exhaust pipeline L30 is connected to the return air pipeline L40, and then the air pump 400 is slowed down or directly shut down, so that the particles in the buffer tank 100 are sucked into the extraction tank 200 through the discharge pipeline L10 and the feed pipeline L20 under the action of the vacuum in the extraction tank 200, and then fall into the cooling tank 300 under the action of their own gravity. It is worth mentioning that, during the step of breaking the vacuum, the air (which may be hot and humid) in the buffer tank 100 will enter the extraction tank 200 along with the particles. However, due to the presence of the return air duct L40, the air and particles will be separated in the extraction tank 200, and the particles will be retained in the extraction tank 200, while the air will enter the return air duct L40 through the exhaust duct L30, thereby being cooled and dried by the cooling and drying unit 500 when flowing through it. The cooled and dried air will return to the outer end L11 of the discharge duct L10, and then enter the extraction tank 200 along with the subsequent particles through the feed duct L20. In addition, in this process, as the number of particles entering the extraction tank 200 increases, the particles accumulated in the extraction tank 200 will squeeze the air into the exhaust duct L30, so the accumulated particles also help promote the above-mentioned cooling and drying of the air. Therefore, under the above configuration, as the steps of establishing vacuum and breaking vacuum are performed alternately, the particles in the buffer tank 100 will be intermittently or pulsedly sucked into the extraction tank 200 and then fall into the cooling tank 300, and the air in the extraction tank 200 will also be intermittently or pulsedly cooled and dried, especially through the feed pipe L20, the exhaust pipe L30 and the return air pipe L40 to form a closed loop for cooling and drying the air, so that the particles can be transported to the cooling tank 300 in low-temperature and dry gas and continue to be cooled in the cooling tank 300, thereby reliably preventing the particles from deforming, absorbing water or sticking together during the transfer and storage process, which not only ensures the smooth progress of subsequent production and processing, but also reduces production costs by omitting the steps of reshaping and dehumidification of the particles.

[0037] According to an optional embodiment of the present invention, Figure 1 As shown, the particle closed-loop conveying system 10 may further include an upstream air filter 610 disposed on the exhaust duct L30. The upstream air filter 610 is located between the air pump 400 and the extraction tank 200, that is, upstream of the air pump 400, and is used to filter the air entering the air pump 400 from the extraction tank 200, that is, to filter out particles, dust, etc. contained in the air, thereby preventing particles, dust, etc. in the extraction tank 200 from entering the air pump 400 along with the air. As the particles enter the extraction tank 200 along with the air, dust may be raised in the extraction tank 200. If this dust and the particles therein enter the air pump 400 and its downstream devices such as the reversing valve V20 and the cooling and drying unit 500, it may cause these devices to clog. If discharged into the atmosphere, it may pollute the environment. Therefore, the above configuration can reliably prevent particles, dust, etc. in the extraction tank 200 from entering the air pump 400 through the upstream air filter 610, thereby effectively preventing the occurrence of device clogging, environmental pollution, etc.

[0038] According to an optional embodiment of the present invention, Figure 1 As shown, the closed-loop particle conveying system 10 may further include a downstream air filter 620 disposed on the return air duct L40. The downstream air filter 620 is located between the outer end L11 of the discharge duct L10 and the cooling and drying unit 500, that is, downstream of the cooling and drying unit 500, to prevent particles, dust, etc. from entering the cooling and drying unit 500 through the discharge duct L10. During the vacuum establishment step, although the return air duct L40 is not connected to the exhaust duct L30, it is still connected to the discharge duct L10. If the pressure in the buffer tank 100 increases (for example, due to an increase in the internal pressure of the buffer tank 100 due to an increase in the number of particles discharged into the buffer tank 100), the particles, dust, etc. in the buffer tank 100 may enter the return air duct L40 through the discharge duct L10. Furthermore, during the vacuum release step, if the vacuum previously established in the extraction tank 200 is too high, the extraction tank 200 may draw particles from the buffer tank 100 through the return air duct L40, which may cause particles and dust from the buffer tank 100 to enter the return air duct L40. Therefore, the above configuration can reliably prevent particles and dust from entering the return air duct L40 via the downstream air filter 620, thereby effectively preventing equipment blockage and environmental pollution.

[0039] According to an optional embodiment of the present invention, Figure 1As shown, the particle closed-loop conveying system 10 may further include a discharge switch valve V30 disposed between the extraction tank 200 and the cooling tank 300, the discharge switch valve V30 being used to selectively connect and isolate the extraction tank 200 and the cooling tank 300. Before or during the step of establishing a vacuum, the discharge switch valve V30 may be closed to isolate the extraction tank 200 and the cooling tank 300 from each other, thereby making it easier to establish a desired vacuum degree in the extraction tank 200 and making it easier for particles to accumulate in the extraction tank 200 to the extent that the air is squeezed into the return air channel L40; and after switching to the step of breaking the vacuum, the discharge switch valve V30 may be kept closed until a predetermined amount of particles is sucked into the extraction tank 200, and then the discharge switch valve V30 may be opened to connect the extraction tank 200 and the cooling tank 300, thereby allowing the particles in the extraction tank 200 to fall into the cooling tank 300, and the discharge switch valve V30 may be closed again before or during the next step of establishing a vacuum. Therefore, under this configuration, it can be ensured that the above-mentioned particle transfer and the cooling and drying of the air can be carried out more smoothly.

[0040] According to an optional embodiment of the present invention, Figure 1 As shown, the bottom of the buffer tank 100 can be conical in shape, sloping downward as it approaches its center, and the inner end L12 of the discharge pipe L10 is located near the center of the bottom of the buffer tank 100, that is, adjacent to the center of the bottom of the buffer tank 100. Of course, a gap is left between the inner end L12 of the discharge pipe L10 and the bottom of the buffer tank 100 for particles to pass through. In this configuration, particles in the buffer tank 100 automatically gather toward the inner end L12 of the discharge pipe L10 under the action of their own gravity. This allows a single discharge pipe L10 to transfer nearly all of the particles in the buffer tank 100, thereby simplifying the structure of the buffer tank 100.

[0041] According to an optional embodiment of the present invention, Figure 1As shown, the feed pipe L20 can lead to the interior of the extraction tank 210 through the sidewall opening 210 in the sidewall of the extraction tank 200, while the exhaust pipe L30 can lead to the interior of the extraction tank 210 through the top opening 220 in the top of the extraction tank 200. In this configuration, particles transported by the feed pipe L20 will enter the extraction tank 200 through the sidewall opening 210. After the height of the particles accumulated in the extraction tank 200 is higher than the sidewall opening 210, the particles can accelerate the extrusion of air into the exhaust pipe L30, thereby facilitating subsequent cooling and drying of the air. In particular, the sidewall opening 210 can be positioned near the bottom of the extraction tank 200, that is, adjacent to the bottom of the extraction tank 200. In this configuration, the particles will accumulate more quickly to a height higher than the sidewall opening 210, thereby extruding air into the exhaust pipe L30 more quickly. Of course, the side wall opening 210 may also be positioned at a position spaced apart from the bottom of the extraction tank 200 , that is, at a certain distance from the bottom of the extraction tank 200 .

[0042] The above description, in conjunction with the accompanying drawings, describes several optional but non-limiting embodiments of the closed-loop particle conveying system according to the present invention. Although different features are described in different embodiments, these features can be combined to form new embodiments, and these new embodiments also fall within the scope of protection of the present invention. Furthermore, the present invention also aims to provide a control method for controlling the above-mentioned closed-loop particle conveying system to achieve particle delivery.

[0043] refer to Figure 2 , which shows a schematic flow chart of a control method according to an optional embodiment of the present invention. Figure 2 As shown, the control method includes the following steps:

[0044] S100: closing the material delivery switch valve V10 to cut off the material delivery pipeline L20, and placing the reversing valve V20 in the first valve position to connect the exhaust pipeline L30 to the atmosphere;

[0045] S200 : operating the air pump 400 at the first power P1 to discharge the air in the extraction tank 200 into the atmosphere, thereby establishing a vacuum in the extraction tank 200 ; therefore, steps S100 and S200 constitute the aforementioned step of establishing a vacuum.

[0046] S300: Open the material delivery switch valve V10 to connect the material delivery pipeline L20, and place the reversing valve V20 in the second valve position to connect the exhaust pipeline L30 with the return air pipeline L40;

[0047] S400: Operate the air pump 400 at a second power P2, wherein the second power P2 is less than the first power P1. As a result, under the action of the vacuum in the extraction tank 200, the particles in the buffer tank 100 are transferred to the extraction tank 200 through the discharge pipe L10 and the feed pipe L20, and at least a portion of the air in the extraction tank 200 is returned to the extraction tank 200 through the exhaust pipe L30, the return pipe L40, and the feed pipe L20. Therefore, steps S300 and S400 constitute the vacuum-breaking step described above. It is worth noting that by setting the second power P2 to be less than the first power P1, the air pressure in the return pipe L40 will not be too high in step S400, thereby preventing the particles in the buffer tank 100 from being drawn into the discharge pipe L10 due to excessive air pressure in the return pipe L40. In particular, the second power P2 can be set to zero, that is, the air pump 400 is shut down in step S400. Of course, the second power P2 may also be set to be greater than zero, so that in step S400 , the air in the extraction tank 200 is pumped into the return air duct L40 by the air pump 400 to promote cooling and drying of the air.

[0048] S500: Return to step S100. Thus, through step S500, the steps of establishing and breaking vacuum can be continuously and alternately performed to transfer particles in the buffer tank 100 to the extraction tank 200 in a pulsed manner, and to cool and dry the air in the extraction tank 200 in a pulsed manner.

[0049] According to an optional embodiment of the present invention, the control method further comprises: continuing to execute step S200 until the vacuum level in the extraction tank 200 reaches a predetermined upper limit VMAX, or until a first predetermined time duration PD1 is reached. Under this configuration, the vacuum is established in the extraction tank 200 until the predetermined upper limit VMAX or the first predetermined time duration PD1 is reached, and then steps S300 and S400 are executed to break the vacuum. In particular, the predetermined upper limit VMAX and the first predetermined time duration PD1 can be set according to the amount of particles in the buffer tank 100. For example, the higher the amount of particles in the buffer tank 100, the higher the predetermined upper limit VMAX and the first predetermined time duration PD1, so that the amount of particles transferred to the extraction tank 200 in each step of breaking the vacuum is higher. In other words, the predetermined upper limit VMAX and the first predetermined time duration PD1 can be positively correlated with the amount of particles to be transferred in the buffer tank 100.

[0050] According to an optional embodiment of the present invention, the control method further comprises: continuing to execute step S400 until the vacuum level in the extraction tank 200 reaches a predetermined lower limit VMIN, or until a second predetermined time duration PD2 is reached, or until the amount of particulate matter in the extraction tank 200 reaches a predetermined amount PM. In this configuration, step S500 is not executed until the vacuum in the extraction tank 200 reaches the predetermined lower limit VMIN due to being broken, or after the vacuum is broken for a second predetermined time duration PD2, or after the amount of particulate matter sucked from the extraction tank 200 reaches a predetermined amount PM, thereby returning to step S100 to re-establish a vacuum in the extraction tank 200.

[0051] According to an optional embodiment of the present invention, step S100 also includes: closing the unloading switch valve V30 to isolate the extraction tank 200 and the cooling tank 300 from each other to help establish a vacuum in the extraction tank 200. The control method also includes step S401 between steps S400 and S500: opening the unloading switch valve V30 to discharge the particles in the extraction tank 200 into the cooling tank 300.

[0052] As can be seen from the foregoing, the closed-loop particle conveying system and control method thereof according to the present invention can realize the transfer and storage of particles in a low-temperature and dry gas, thereby effectively preventing the particles from deforming, absorbing water or sticking together during the transfer and storage after production, and thus ensuring the smooth progress of subsequent production and processing using these particles as raw materials.

[0053] The above describes in detail, with the aid of the accompanying drawings, an optional but non-limiting embodiment of a closed-loop particle conveying system and control method thereof according to the present invention. It will be apparent to those skilled in the art that modifications and additions to the techniques and structures, as well as recombinations of features or steps in the various embodiments, without departing from the spirit and substance of the present disclosure, should be considered within the scope of the present invention. Therefore, all such modifications and additions that are conceivable under the teachings of the present invention should be considered part of the present invention. The scope of the present invention includes equivalent technologies known as of the filing date of the present invention and equivalent technologies that have not yet been foreseen.

Claims

1. A closed-loop particle conveying system comprising: A buffer tank (100), the buffer tank (100) being provided with a discharge pipe (L10), the discharge pipe (L10) having an outer end portion (L11) located outside the buffer tank (100) and an inner end portion (L12) located inside the buffer tank (100) and adjacent to the bottom of the buffer tank (100); a material extraction tank (200) connected to the outer end (L11) of the discharge pipe (L10) via a material delivery pipe (L20), wherein the material delivery pipe (L20) is provided with a material delivery switch valve (V10); and a reversing valve (V20), the reversing valve (V20) having an input port (V21) connected to the extraction tank (200) via an exhaust pipe (L30), a first output port (V22) connected to the atmosphere, and a second output port (V23) connected to the outer end (L11) of the discharge pipe (L10) via a return air pipe (L40), and the reversing valve (V20) having a first valve position connecting the input port (V21) to the first output port (V22) and a second valve position connecting the input port (V21) to the second output port (V23), The exhaust pipe (L30) is provided with an air pump (400) for discharging the air in the extraction tank (200), and the return air pipe (L40) is provided with a cooling and drying unit (500) for cooling and drying the air, and The feed switching valve (V10) is configured to cut off the feed pipeline (L20) when the reversing valve (V20) is in a first valve position to establish a vacuum in the extraction tank (200), and to open the feed pipeline (L20) when the reversing valve (V20) is in a second valve position to allow air to circulate between the extraction tank (200) and the cooling and drying unit (500).

2. The closed-loop particle conveying system according to claim 1, wherein: The particle closed-loop conveying system further includes a cooling tank (300) connected below the extraction tank (200) and a discharge switching valve (V30) arranged between the extraction tank (200) and the cooling tank (300).

3. The closed-loop particle conveying system according to claim 1 or 2, wherein: The exhaust pipe (L30) is further provided with an upstream air filter (610), and the upstream air filter (610) is located between the extraction tank (200) and the air pump (400).

4. The closed-loop particle conveying system according to claim 1 or 2, wherein: The return air duct (L40) is further provided with a downstream air filter (620), and the downstream air filter (620) is located between the outer end (L11) of the discharge duct (L10) and the cooling and drying unit (500).

5. The closed-loop particle conveying system according to claim 1 or 2, wherein: The cooling and drying unit (500) comprises a cooler and a steam-water separator connected together.

6. The closed-loop particle conveying system according to claim 1 or 2, wherein: The discharge pipe (L10) extends from its outer end (L11) through the top of the buffer tank (100) to its inner end (L12).

7. The closed-loop particle conveying system according to claim 1 or 2, wherein: The bottom of the buffer tank (100) is in a conical shape that slopes downward as it approaches the center, and the inner end (L12) of the discharge pipe (L10) is adjacent to the center of the bottom of the buffer tank (100).

8. The closed-loop particle conveying system according to claim 1 or 2, wherein: The material delivery pipe (L20) leads to the interior of the material extraction tank (200) through a side wall opening (210) in the side wall of the material extraction tank (200), and the exhaust pipe (L30) leads to the interior of the material extraction tank (200) through a top opening (220) in the top of the material extraction tank (200).

9. The closed-loop particle conveying system according to claim 8, wherein: The side wall opening (210) is adjacent to the bottom of the extraction tank (200).

10. The closed-loop particle conveying system according to claim 8, wherein: The side wall opening (210) is spaced apart from the bottom of the extraction tank (200).

11. A control method for controlling the closed-loop particle conveying system according to any one of claims 1 to 10, comprising the following steps: S100: closing the material delivery switch valve (V10) and placing the reversing valve (V20) in the first valve position; S200: operating the air pump (400) at a first power; S300: opening the feed switching valve (V10) and placing the reversing valve (V20) in the second valve position; S400: operating the air pump (400) at a second power, wherein the second power is lower than the first power; and S500: Return to step S100.

12. The control method according to claim 11, wherein: The control method further comprises: executing step S200 until the vacuum degree in the extraction tank (200) reaches a predetermined upper limit, or until a first predetermined time period is reached.

13. The control method according to claim 11 or 12, wherein: The control method further comprises: executing step S400 until the vacuum degree in the extraction tank (200) reaches a predetermined lower limit, or until a second predetermined time period is reached, or until the amount of particles in the extraction tank (200) reaches a predetermined amount.

14. The control method according to claim 11 or 12, wherein: The particle closed-loop conveying system further includes a cooling tank (300) connected below the extraction tank (200) and a discharge switch valve (V30) provided between the extraction tank (200) and the cooling tank (300). Step S100 also includes: closing the discharge switch valve (V30); and The control method further includes step S401 between steps S400 and S500: opening the discharge switch valve (V30).

15. The control method according to claim 11 or 12, wherein: The second power is set to zero.

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