A pneumatic conveying device

Abstract

This utility model discloses a pneumatic conveying device, relating to the field of pneumatic conveying technology. It includes: a silo pump, a scraper, and a scraper drive assembly. The silo pump is connected to an inlet pipe, an exhaust pipe, and a powder output pipe. The bottom structure of the silo pump is a base plate assembly, configured to allow air circulation but not powder circulation. An air chamber is located below the base plate assembly and is connected to a compressed air pipe. A scraper is located on the upper surface of the base plate assembly, which has a large particle discharge port connecting both the upper and lower surfaces. The scraper drive assembly is configured to drive the scraper to scrape and convey large particles from the upper surface of the base plate assembly to the large particle discharge port, which discharges the large particles from the silo pump. The pneumatic conveying device provided by this utility model reduces the amount of large particles accumulating in the powder output pipe and within the silo pump, thereby reducing the failure rate.

Description

Technical Field

[0001] This utility model relates to the field of pneumatic conveying technology, and in particular to a pneumatic conveying device. Background Technology

[0002] Ordinary pneumatic conveying equipment can typically only transport small particles of powder (such as fly ash from power plants). When the powder clumps together to form large particles, or when the powder itself contains large particles, if compressed air cannot break them up, these large particles will accumulate at the bottom of the silo pump and are difficult to remove. Over time, this can clog the silo pump, eventually leading to the failure of the entire pneumatic conveying system. Utility Model Content

[0003] The purpose of this invention is to provide a pneumatic conveying device to solve the problems existing in the prior art and reduce the probability of malfunctions.

[0004] To achieve the above objectives, this utility model provides the following solution:

[0005] This utility model provides a pneumatic conveying device, including: a silo pump, a scraper, and a scraper drive assembly. The silo pump is connected to an inlet pipe, an exhaust pipe, and a powder output pipe. The bottom structure of the silo pump is a base plate assembly, which is configured to allow air passage but not powder passage. An air chamber is provided below the base plate assembly, and the air chamber is connected to a compressed air pipe. The scraper is provided on the upper surface of the base plate assembly. The base plate assembly has a large particle discharge port that extends through both the upper and lower surfaces. The scraper drive assembly is configured to drive the scraper to scrape the large particles on the upper surface of the base plate assembly to the large particle discharge port, which is used to discharge the large particles from the silo pump.

[0006] Preferably, the base plate assembly includes a perforated grinding disc and a first canvas layer, the upper surface of the first canvas layer being in contact with the perforated grinding disc, and the scraper being disposed on the upper surface of the perforated grinding disc.

[0007] Preferably, a support plate is provided below the canvas, the upper surface of the support plate is attached to the lower surface of the canvas, and a plurality of air holes are evenly provided on the support plate.

[0008] Preferably, the base plate assembly is circular, and the drive shaft of the scraper drive assembly passes through the center of the base plate assembly from bottom to top and is fixedly connected to the first end of the scraper. The second end of the scraper is located near the outer periphery of the base plate assembly. The side of the scraper used to scrape and feed materials is the scraping surface. The scraping surface is bent in the direction away from the rotation of the scraper and forms an accumulation area at the top of the bend. When the scraper drive assembly drives the scraper to rotate, the accumulation area moves around the first circumferential trajectory, and at least part of the large particle discharge outlet is located below the first circumferential trajectory.

[0009] Preferably, there are multiple scrapers, which are evenly distributed along the circumference.

[0010] Preferably, the compressed air pipeline includes several branches, and at least one of the branches is connected to the air chamber.

[0011] Preferably, the large particle outlet is connected to a large particle discharge pipeline.

[0012] Preferably, the large particle discharge pipeline includes a discharge pipe and a large particle discharge valve connected to the bottom of the discharge pipe. Part of the discharge pipe is located inside the air chamber, and at least part of the discharge pipe located inside the air chamber is configured to allow air to pass through but not to allow powder to pass through.

[0013] Preferably, a portion of the discharge tube has holes, and the portion of the discharge tube with holes is wrapped with a second canvas layer. The portion of the second canvas near the upper and lower edges is clamped and fixed to the discharge tube by a clamping mechanism.

[0014] Preferably, it further includes a sleeve and a rotary sealing assembly. The air chamber and the base plate assembly constitute an air chamber assembly. The sleeve extends through the upper and lower surfaces of the air chamber assembly and is used to pass through the drive shaft. The rotary sealing assembly includes a sealing shell, a bearing, and a sealing sleeve. The bottom of the sleeve protrudes from the lower surface of the air chamber assembly. The sealing shell is fixedly disposed at the bottom of the sleeve. The sealing sleeve and the bearing are fixedly disposed inside the sealing shell. The drive shaft passes through the sealing sleeve and the bearing, and the drive shaft and the sealing sleeve are in sliding contact.

[0015] The present invention achieves the following technical advantages over the prior art:

[0016] In this invention, the compressed air pipeline can inject compressed gas from the bottom structure of the silo pump into the silo pump, which can create a fluidization effect in the powder inside the silo pump. As a result, larger particles will settle at the bottom, while the powder will float to the top, making it easier to transport the powder to the outside. The large particles at the bottom are discharged from the silo pump through the large particle outlet under the action of the scraper. Therefore, the pneumatic conveying device provided by this invention reduces the amount of powder output pipeline and large particles accumulated in the silo pump, thereby reducing the failure rate. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the pneumatic conveying device provided in an embodiment of this utility model;

[0019] Figure 2 for Figure 1 Schematic diagram of the structure of the central tank pump;

[0020] Figure 3 This is a schematic diagram of the structure of the silo pump in some optional embodiments;

[0021] Figure 4 This is a structural schematic diagram of the air chamber assembly, drive assembly, and large particle discharge pipeline;

[0022] Figure 5 A schematic diagram of the drive shaft and rotary seal assembly;

[0023] Figure 6 This is a structural diagram of the pallet;

[0024] Figure 7 This is a schematic diagram of the structure of the first canvas layer;

[0025] Figure 8 This is a schematic diagram of two scrapers scraping large particles of material.

[0026] Figure 9 This is a schematic diagram showing the movement of large particles by three scrapers.

[0027] Figure 10 A schematic diagram of a structure with two scrapers, each with two bends;

[0028] Figure 11 A schematic diagram of a perforated grinding disc with a circular hole;

[0029] Figure 12 A schematic diagram of a perforated grinding disc with strip-shaped holes;

[0030] Figure 13 A schematic diagram of a perforated grinding disc with strip-shaped holes arranged in a vortex pattern;

[0031] Figure 14 In order to be in Figure 13 The diagram shows the trajectory of large particles when they are suspended on a perforated grinding disc.

[0032] Figure 15 This is a schematic diagram of the gas chamber assembly and the large particle discharge pipeline.

[0033] Figure 16 This is a schematic diagram of the initial state before the silo pump is pressurized after the material has been discharged.

[0034] Figure 17This is a schematic diagram showing the state after the silo pump has finished discharging material and has been pressurized with air.

[0035] Figure 18 This is a schematic diagram illustrating the state of the powder conveying process;

[0036] Figure 19 This is a schematic diagram of the powder output principle.

[0037] Figure 20 This is a schematic diagram illustrating the principle that large particles cannot be blown away.

[0038] In the diagram: 1-Feed switch valve; 2-Blouse pump; 3-Blouse pump exhaust switch valve; 4-Level gauge; 5-Pressure transmitter; 6-Air chamber assembly; 7-Air chamber air supply valve group; 8-Blouse pump middle air supply valve group; 9-Blouse pump upper air supply valve group; 10-Blouse pump pressure reducing control valve group; 11-Powder discharge valve; 12-Large particle discharge valve; 13-Compressed air pipeline; 14-Exhaust pipeline; 15-Feed pipeline; 16-Powder output pipeline; 17-Large particle discharge pipeline; 201-Blouse pump discharge port; 202-Blouse pump exhaust port; 203-Blouse pump level gauge port; 204-Pressure measuring point port; 205-Blouse pump upper air inlet port; 206-Blouse pump middle air inlet port; 207-Discharge port; 208 - Air chamber interface; 209-Inspection hole; 210-Straight section of silo pump; 18-Rotary seal assembly; 19-Reducer bracket; 20-Reducer; 21-Drive motor; 22-Discharge pipe; 601-Air chamber; 23-Drive shaft; 24-Upper connecting flange of sealing assembly; 25-Sealing sleeve; 26-Bearing; 27-Lower connecting flange of sealing assembly; 28-Sealing shell; 29-Pressure block; 30-Pattern; 31-Opening for drive shaft sleeve; 32-Large particle discharge port; 33-Air passage hole; 34-Bolt through hole; 35-First canvas layer; 36-First circumferential trajectory; 37-Scraper; 38-Accumulation area; 39-Perforated grinding disc; 40-Air chamber inlet interface; 41-Second canvas layer; 42-Clamping clamp. Detailed Implementation

[0039] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0040] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] First, some technical terms involved in the embodiments of this application will be introduced.

[0042] Strongly bonded large particles: These are large particles formed when fine powder particles are bonded together under certain conditions. This bonding usually refers to a state of tight molecular bonding, such as "melting and cooling" or "solidification and bonding after dissolution." This "strongly bonded" state is not easily broken into smaller particles or fine powder under external stress.

[0043] The main difference between weakly bound and strongly bound large particles lies in the ease with which the particles are broken into powder under external stress. If the particles can be easily broken in equipment with minimal wear, they can be simply classified as weakly bound large particles. Conversely, they are considered strongly bound large particles.

[0044] This utility model provides a pneumatic conveying device, such as Figures 1 to 20 As shown, it includes: a silo pump 2, a scraper 37, and a scraper drive assembly. The silo pump 2 is connected to a compressed air pipeline 13, a feed pipeline 15, an exhaust pipeline 14, and a powder output pipeline 16. The bottom structure of the silo pump 2 is a bottom plate assembly, which is configured to allow air circulation but not powder circulation. An air chamber 601 is provided below the bottom plate assembly, and the air chamber 601 is connected to a branch of the compressed air pipeline 13. A scraper 37 is provided on the upper surface of the bottom plate assembly. The bottom plate assembly has a large particle discharge port 32 that runs through the upper and lower surfaces. The scraper drive assembly is configured to drive the scraper 37 to scrape and convey the large particles of material on the upper surface of the bottom plate assembly to the large particle discharge port 32. The large particle discharge port 32 is used to discharge the large particles of material from the silo pump 2.

[0045] In this embodiment, the compressed air pipeline 13 can inject compressed gas from the bottom structure of the silo pump 2 into the silo pump 2, which can cause the powder in the silo pump 2 to form a fluidization effect. In this way, larger particles (large particles) will settle at the bottom, while powder or small particles will float to the top, so as to facilitate the transport of powder to the outside. The large particles that fall to the bottom are discharged from the silo pump 2 through the large particle discharge port 32 under the action of the scraper 37. Therefore, the pneumatic conveying device provided by this utility model reduces the amount of large particles accumulated in the powder output pipeline 16 and the silo pump 2, thereby reducing the failure rate.

[0046] Understandably, the fluidization effect of the powder in the silo pump 2 can be understood as screening large particles downwards onto the bottom plate assembly, so that they can be scraped and conveyed by the scraper 37 later.

[0047] In some embodiments, the base plate assembly includes a perforated grinding disc 39 and a first canvas layer 35. The upper surface of the first canvas layer 35 is in contact with the perforated grinding disc 39. A scraper 37 is disposed on the upper surface of the perforated grinding disc 39. The upper surface of the perforated grinding disc 39 is roughened so that powder can be ground from the large particles when the scraper 37 scrapes the large particles. In addition, the holes in the perforated grinding disc 39 also help to crush the large particles.

[0048] This embodiment utilizes the good air permeability and the fact that powder does not easily pass through the first canvas layer 35. When gas is filled into the first canvas layer 35 from one side (non-uniformly), the gas can be more evenly permeated out of the surface of the first canvas layer 35 from the other side (the thicker the first canvas layer 35, the better the uniformity of gas permeation, but the greater the resistance to gas permeation). At the same time, the small pore size of the canvas can prevent powder from leaking into the air chamber 601.

[0049] Understandably, the first canvas layer 35 can be replaced by any breathable fabric material with a certain thickness, or even some plastic or metal materials with micropores.

[0050] Note: Large particles are generally divided into weakly bound large particles and strongly bound large particles. The scraper 37 and the perforated grinding disc 39 can crush weakly bound large particles into powder. However, because the binding force of strongly bound large particles is strong, they are not easy to crush. Therefore, the strongly bound large particles will be scraped and sent to the large particle outlet for discharge under the action of the scraper 37.

[0051] In some embodiments, the perforated grinding disc 39 is a grinding disc with strip-shaped or circular holes of a certain width (available in various models). Its first function is to work in conjunction with the scraper 37 to cut and grind large particles into fine particles of a certain diameter. Its second function is to atomize and blow up the fine powder particles under the action of compressed air in the air chamber 601. Figures 11-13 This is a cross-sectional schematic diagram of the perforated grinding disc 39. There are no strict requirements for the opening pattern of the perforated grinding disc 39, but the diameter of the circular hole or the width of the strip hole needs to meet a certain diameter or width (within a certain width, fine particles with the same diameter as this width can be blown up, see the principle analysis below for details).

[0052] Because canvas is relatively soft, a support plate 30 is usually placed at the bottom of the canvas to support it and prevent it from warping downwards in the middle. The support plate 30 has a certain number of air holes 33 on its surface to allow air to pass through. The solid part of the support plate 30 is used to support the canvas. If the air chamber 601 is small (and the canvas warping is also small), this support plate 30 can be omitted.

[0053] Specifically, a support plate 30 is provided under the canvas, with its upper surface adhering to the lower surface of the canvas. Multiple air vents 33 are evenly distributed on the support plate 30. The structure of the support plate 30 is shown below. Figure 6 Of course, the air passage 33 is not limited to round holes; it can be a strip hole or other irregularly shaped passage.

[0054] In the above embodiments, the perforated grinding disc 39, the support plate 30, and the first canvas layer 35 constitute the base plate assembly.

[0055] In some embodiments, the base plate assembly is circular, and the scraper drive assembly includes a reducer 20 and a drive motor 21. The reducer 20 is fixed below the air chamber 601 by a reducer bracket 19. The drive shaft 23 of the drive motor 21 passes through the center of the base plate assembly from bottom to top and is fixedly connected to the first end of the scraper 37. The second end of the scraper 37 is located near the outer periphery of the base plate assembly. The side of the scraper 37 used for scraping and feeding materials is the scraping surface. The scraping surface is bent in the direction away from the rotation of the scraper 37 and forms an accumulation area 38 at the top of the bend. When the scraper drive assembly drives the scraper 37 to rotate, the accumulation area 38 moves around the first circumferential trajectory 36. At least part of the large particle discharge outlet 32 ​​is located below the first circumferential trajectory 36.

[0056] In this embodiment, the scraper drive assembly drives the scraper 37 to rotate, and the scraping surface bends to form two guide surfaces. When the scraper surface scrapes and feeds the material around the circumference, the material is guided to the accumulation area 38 by the guide surfaces. Then, when it passes through the large particle discharge port 32, the large particles fall to the large particle discharge port 32 under the action of gravity.

[0057] Considering that if only one scraper 37 is provided, it will cause the drive shaft 23 to be subjected to an eccentric stress, which is not conducive to the long-term use of the equipment, in some embodiments, multiple scrapers 37 are provided, and the multiple scrapers 37 are evenly distributed along the circumference, which can make the drive shaft 23 be subjected to uniform stress.

[0058] In some embodiments, the trajectory of large particles on the perforated grinding disc 39 (i.e., the first circumferential trajectory 36) may or may not have perforations. However, to reduce wear on the scraper 37 and the perforated grinding disc 39, perforations are normally not made on the trajectory of the large particles. Figures 11-13 As shown.

[0059] Figure 11 This is a standard circular hole arrangement method, which aims to achieve a larger opening ratio but has a longer processing cycle.

[0060] Figure 12 The arrangement of strip-shaped holes is a method with a slightly lower aperture ratio than the circular hole arrangement, but a shorter processing time.

[0061] Figure 13 The arrangement of the strip-shaped holes in a spiral pattern, with each hole forming a certain angle with the central axis, allows for rapid movement of large particles to the non-perforated area (along the particle accumulation path). This minimizes wear on the scraper 37 and the grinding disc. The principle behind the rapid movement of large particles is explained below. Figure 14 Under the combined action of centrifugal force, scraper 37 (the scraping surface forms a certain angle with the central axis passing through the center of the circle), and vortex-shaped strip holes (the strip holes form a certain angle with the central axis of the circle), large particles are rapidly moved to the non-pore area.

[0062] In some embodiments, the compressed air pipeline 13 includes several branches, at least one of which is connected to the air chamber 601. In other words, there must be an air path to fill the air chamber 601 with air. The gas in the air chamber 601 can enter the chamber pump 2 to provide high-pressure power for the conveying of powder. Therefore, in some embodiments of this invention, only one compressed air pipeline 13 or only one branch may be provided. Of course, to improve the conveying effect, two or more branches may be provided. In some examples, such as... Figure 1 As shown, the compressed air pipeline 13 includes three branches. The first branch is connected to the upper part of the chamber pump 2, the second branch is connected to the middle part of the chamber pump 2, and the third branch is connected to the air chamber 601.

[0063] In some embodiments, the large particle outlet 32 ​​is connected to a large particle discharge pipe 17, which includes a discharge pipe 22 and a large particle discharge valve 12 connected to the bottom of the discharge pipe 22.

[0064] In some embodiments, such as Figure 15 As shown, part of the discharge pipe 22 is located inside the air chamber 601, and the discharge pipe 22 located at least part of the air chamber 601 is configured to allow air to pass through but not to pass through the powder.

[0065] Specifically, some of the material drop tubes 22 have holes, and the part of the material drop tube 22 with holes is wrapped with a second canvas layer 41. The part of the second canvas layer 41 near the upper and lower edges is clamped and fixed to the material drop tube 22 by a clamping mechanism. The clamping mechanism can be a metal clamp 42 in the prior art.

[0066] This embodiment can prevent fine particles with a certain diameter from falling into the large particle discharge pipe 17.

[0067] In some embodiments, the present invention further includes a sleeve and a rotary sealing assembly 18. The air chamber 601 and the base plate assembly constitute the air chamber assembly 6. The sleeve penetrates the upper and lower surfaces of the air chamber assembly 6 and is used to pass through the drive shaft 23. The rotary sealing assembly 18 includes a sealing shell 28, a bearing 26 and a sealing sleeve 25. The bottom of the sleeve protrudes from the lower surface of the air chamber assembly 6. The sealing shell 28 is fixedly disposed at the bottom of the sleeve. The sealing sleeve 25 and the bearing 26 are fixedly disposed inside the sealing shell 28. The drive shaft 23 passes through the sealing sleeve 25 and the bearing 26, and the drive shaft 23 and the sealing sleeve 25 are in sliding contact.

[0068] This embodiment is designed to prevent powder from leaking out of the equipment from the outer periphery of the drive shaft 23 within the silo pump 2.

[0069] Specifically, two annular pressure blocks 29 are used to press and fix the sealing sleeve 25 in the gap between the sealing housing 28 and the drive shaft 23.

[0070] In some embodiments, the chamber pump 2 may employ, for example... Figure 2 The "straight-cone" type silo pump shown.

[0071] It mainly includes: 1. Pump legs for supporting the weight of the pump 2, the powder, and its accessories; 2. A cone section of the pump that withstands a certain conveying pressure and has a specific process purpose (if D2 = D1, that is, the diameter of the straight section 210 of the pump is equal to the diameter of the air chamber 601, the cone section can also be omitted); 3. A straight section 210 of the pump that withstands a certain conveying pressure and meets the single conveying volume of powder (mainly used to increase the volume, so if the volume enclosed by the cone section and the top end cap of the pump can meet the single conveying volume of powder, then the straight section 210 of the pump can be omitted); 4. A top end cap that withstands a certain conveying pressure.

[0072] The silo pump 2 is equipped with a silo pump discharge port 201, a silo pump exhaust port 202, a silo pump level gauge port 203, a pressure measuring point port 204, an upper air inlet port 205, a middle air inlet port 206, a discharge port 207, an air chamber port 208, and an inspection hole 209.

[0073] The silo pump discharge port 201 is used to connect with the feed pipeline 15.

[0074] The hopper pump exhaust port 202 is used to connect to the exhaust pipe 14.

[0075] The silo pump level gauge interface 203 is used for installing the level gauge.

[0076] Pressure measuring point interface 204 is used to install pressure transmitter 5.

[0077] The upper air inlet 205 and the middle air inlet 206 of the silo pump are both used to connect to a branch of the compressed air pipeline 13.

[0078] The air chamber interface 208 is used to connect to the air chamber assembly 6.

[0079] Inspection hole 209 is used for maintenance.

[0080] Silo Pump Description: The above describes a standard silo pump design. A silo pump is simply a container for storing powder, and its structure can vary. For example... Figure 3 The forms shown are examples.

[0081] The workflow and principles are as follows.

[0082] Note: The initial state of the pneumatic conveying device is that all manually controlled valves are open, all pressure reducing valves are adjusted to the appropriate pressure, and all program-controlled valves are closed. The check valve does not require adjustment.

[0083] Step 1: Material feeding into silo pump 2

[0084] Open the program-controlled vent valve 3 and the program-controlled feed valve 1. At this time, the powder falls from the top powder hopper of the silo pump 2 into the silo pump 2 under neutral pressure. Simultaneously, the air inside the silo pump 2 is discharged through the vent valve 3 to the unstacking section above the powder hopper. This allows for relatively smooth air discharge from the silo pump 2. Alternatively, the air inside the silo pump 2 can be discharged into other enclosed cavities, as long as it allows for smooth air release.

[0085] During the feeding process, when the level gauge 4 of the silo pump 2 detects that the powder in the silo pump 2 has reached a certain level (or the feeding time is controlled by the program timer for a certain period of time), the feed switch valve 1 controlled by the program is closed, and the silo pump exhaust switch valve 3 controlled by the program is closed.

[0086] This completes the material feeding process inside the silo pump.

[0087] Step 2: Pressurizing and inflating the chamber pump 2

[0088] Open the program-controlled air supply valve group in the pressure reducing control valve group 10 of the silo pump. At this time, compressed air will enter the silo pump 2 through the air supply valve groups at various positions on the silo pump 2 (air chamber air supply valve group 7, silo pump middle air supply valve group 8 and silo pump upper air supply valve group 9).

[0089] During the inflation and pressurization process, when the pressure measured by the pressure transmitter 5 on the chamber pump 2 is higher than a certain pressure.

[0090] This completes the pressurization process. (Note that at this point, it is not necessary to close the program-controlled air supply valve group in the pressure reducing control valve group 10 of the silo pump; instead, prepare to open the program-controlled powder discharge valve 11.)

[0091] There are two main purposes for pressurizing the silo pump 2.

[0092] Firstly, this is to provide the powder in the silo pump 2 with a faster initial velocity when it is discharged from the silo pump 2. This can effectively reduce the accumulation of powder in the powder output pipe 16, thereby preventing the powder from clogging in the powder output pipe 16.

[0093] Secondly, this is to allow large particles in the silo pump 2 to settle to the bottom (on the perforated grinding disc 39). When compressed air enters the air chamber 601 through the air chamber supply valve assembly 7, it forms a uniform upward airflow on the surface of the perforated grinding disc 39 (see the cross-sectional schematic diagram of the perforated grinding disc 39, the first canvas layer 35, and the support plate 30). This causes a fluidization effect in the powder within the silo pump 2. As a result, larger particles will settle at the bottom (on the perforated grinding disc 39), while smaller particles will float on top of the powder pile.

[0094] Step 3: Conveying fine powder particles and allowing large particles to fall into the feed pipe 22

[0095] Open the program-controlled powder discharge valve 11. At this time, the silo pump 2 is under positive pressure, and the program-controlled air supply valve group in the silo pump pressure reducing control valve group 10 is also open. In this way, the air in the silo pump 2 carrying dust particles will continuously escape from the outlet of the program-controlled powder discharge valve 11 (the discharge port of the silo pump 2). At the same time, after opening the program-controlled powder discharge valve 11 (or after a period of time, after a portion of the fine particles have been sent out of the silo pump 2), the motor of the rotating scraper 37 can be turned on, allowing the scraper 37 to participate in the work for separating large particles.

[0096] Specifically, such as Figure 18 As shown: When compressed air is simultaneously injected into the silo pump 2 through the upper air inlet 205, the middle air inlet 206, and the air chamber inlet 40, small-diameter particles (also known as powder) are blown up and into the powder output pipeline 16, and then transported to the next equipment (process) along the powder output pipeline 16. Large particles are not blown up and are deposited at the bottom of the silo pump 2 (above the perforated grinding disc 39 on the air chamber 601).

[0097] The basic principle is that small particles are blown up, while large particles are not, as follows: Figure 20 The analysis is as follows.

[0098] 1. Assume the approximate diameter of the particulate matter is... (Most particulate matter is an irregularly shaped spherical object; the diameter value here is assumed to be the average, or it can be considered as a regular sphere.) 2. Assume the density of the particulate matter is ρ. 颗粒 (kg / m 3 3. Assume the acceleration due to gravity is g (m / s²).2 , is a constant, normally 9.8 m / s 2 4. Assume the density of compressed air is ρ. 空气 (kg / m 3 (At normal temperature, the air density is 1.29 kg / m³) 3 (The density of compressed air is much greater than this value). 5. Assume the upward velocity of the compressed air is v (m / s). 6. Assume the size coefficient of the particulate matter is μ. S (Constant) The shape factor is a shape parameter specific to an object. The size, shape, and surface regularity of an object all affect its shape factor. The value of shape factor * wind pressure * frontal area is the frontal drag F experienced by the object. w (N, i.e., kg·m / s) 2 ).

[0099] The wind pressure W can be calculated from the gas density and wind speed. p (Pa, i.e., N / m) 2 That is, kg / (s) 2 .m)), its formula is W p =0.5*ρ 空气 *v^2 (Bernoulli's equation). The windward area of ​​a particulate matter is its cross-sectional area, approximately π*(d / 2)^2. Based on this, the upward wind resistance F experienced by the particle can be obtained. w =μ S *(0.5*ρ 空气 *v^2)*(π*(d / 2)^2).

[0100] The diameter of the known particles The volume V(m) of the particulate matter can be obtained. 3 (Assuming it is a regular sphere), its formula is: (4 / 3)*π*(d / 2)^3. The gravitational force F acting on the particulate matter is... g (N, i.e., kg·m / s) 2 The formula is: F g =ρ 颗粒 *V*g. Based on this, we can obtain the gravitational force F acting on the particle. g =ρ 颗粒 *((4 / 3)*π*(d / 2)^3)*g.

[0101] Under certain operating conditions, the density ρ of compressed air 空气 If the upward velocity v of the compressed air is constant, then the upward wind resistance F experienced by the particles is... w It's about the diameter of the particles. Numerical values ​​that are related by a square power.

[0102] Under certain operating conditions, the density ρ of compressed particulate matter颗粒 (Under normal circumstances, the materials are one or more materials with similar densities), and the acceleration due to gravity is g, which is a constant value. Then, the gravitational force F acting on the particles is... g It's about the diameter of the particles. Numerical values ​​that are related by the power of cubic.

[0103] When particulate matter can be blown upwards, it means that the upward wind resistance experienced by the particulate matter is greater than its weight, i.e., μ. S *(0.5*ρ 空气 *v^2)*(π*(d / 2)^2)>ρ 颗粒 *((4 / 3)*π*(d / 2)^3)*g, we can get d<(3*μ S *ρ 空气 *v^2) / (4*ρ 颗粒 *g); When particulate matter cannot be blown upwards, it indicates that the upward wind resistance experienced by the particulate matter is less than its weight, i.e., μ S *(0.5*ρ 空气 *v^2)*(π*(d / 2)^2)<ρ 颗粒 *((4 / 3)*π*(d / 2)^3)*g, we can get d>(3*μ S *ρ 空气 *v^2) / (4*ρ 颗粒 *g). This leads to the conclusion that smaller particles are more easily blown up than larger particles.

[0104] like Figure 8 As shown, large particles fall into the large particle discharge pipe 17: As the scraper 37 moves, the large particles will slowly move to the large particle accumulation area of ​​the scraper 37 (the intersection of the two inclined planes). The large particle discharge port is located on the movement trajectory of the large particle accumulation area. When the scraper 37 rotates to the discharge port and the large particles have moved to the large particle accumulation area, then under the action of gravity, the large particles will fall into the discharge pipe 22 and land on the valve core of the discharge valve.

[0105] Determining the value of the opening diameter (circular hole) or opening width (strip hole) d1 of the perforated grinding disc 39:

[0106] When the speed v between the holes of the grinding disc 孔间 A value greater than a certain threshold can guarantee the aerosolization of particles with a diameter smaller than d1. The velocity v between the holes... 孔间 The total area S of the openings in the grinding disc can be used as a reference. 磨盘开孔 (m 2 ) and the intake volume control Q of the regulating air chamber 601 气室 (m³ / s), its value is v 孔间 (m / s)=Q 气室 / S 磨盘开孔 .

[0107] Therefore μ S *(0.5*ρ 空气 *v 孔间 ^2)*(π*(d1 / 2)^2)>ρ 颗粒 *((4 / 3)*π*(d1 / 2)^3)*g(In the formula above, d is replaced by d1, and v is replaced by v) 孔间 (replace). This yields d1 < (3*μ). S *ρ 空气 *v 孔间 ^2) / (4*ρ 颗粒 *g). At this aperture, if the particle diameter is larger than this value, even if the particle is not blown up, it will not fall into the hole and block the grinding disc opening. However, if the particle diameter is smaller than this value, it will be blown up by the airflow between the 39 holes of the perforated grinding disc and will not block the grinding disc opening.

[0108] Separation of fine particles of a specific diameter (specific diameter mainly refers to fine particles with d between d1 and d2, i.e., d1≥d≥d2) and the opening area S of the side wall of the discharge pipe 22. 落料管 (m 2 The determination of )

[0109] Let v be the average velocity of the upward compressed air flow formed in air chamber 601 at the outlet circular cross-section of the pump. 出口 (m / s). Let the exit circular cross-section (see figure below) be... The cross-sectional area of ​​the circular section at point S is 出口 (m 2 ).

[0110] So v 出口 =Q 气室 / S 出口 Because v 孔间 (m / s)=Q 气室 / S 磨盘开孔 (See step 3 of the crushing process.)

[0111] If S 出口 >S 磨盘开孔 (This is the case for most types of chamber pumps), without increasing the air intake Q of chamber 601. 气室 In the case of v, we can obtain 孔间 >v 出口 .

[0112] And d2≈(3*μ) S *ρ 空气 *v 出口 ^2) / (4*ρ 颗粒 *g)(In the formula above, d is replaced by d2, and v is replaced by v 出口 (replace) d1≈(3*μS *ρ 空气 *v 孔间 ^2) / (4*ρ 颗粒 *g)(In the formula above, d is replaced by d1, and v is replaced by v 孔间 replace).

[0113] Because v 孔间 >v 出口 We can conclude that d1 > d2. Therefore, when the diameter d of the particles is between d1 and d2 (i.e., d1 ≥ d ≥ d2), these particles may not be blown into the powder output pipe 16. Therefore, it is necessary to separate particles with a diameter d ≥ d2 (including particles with a diameter between d1 ≥ d ≥ d2) into the discharge pipe 22.

[0114] Based on this, the opening area S on the side wall of the feeding pipe 22 can be determined. 落料管侧壁 Let the gas velocity at the outlet of the feed pipe 22 also be approximately equal to v. 出口 (or slightly less than v) 出口 This ensures that particles with a diameter d≥d2 will not be blown out of the discharge pipe 22 again after falling into it.

[0115] Because the thickness of the second canvas layer wrapped around the feed pipe 22 is basically the same as the thickness of the first canvas layer under the grinding disc (so the air permeability resistance of the canvas is also basically the same), and the opening ratio of the feed pipe 22 within the area wrapped by the second canvas layer is also consistent with the design of the grinding disc, it can be approximately assumed that the gas flow velocity through the holes of the grinding disc and the gas flow velocity through the openings in the side wall of the feed pipe 22 are the same, both being v. 孔间 .

[0116] Then we can obtain the following formula: v 孔间 *S 落料管侧壁 =v 出口 *S 落料管内截面 Find S 落料管 =v 出口 *S 落料管内截面 / v 孔间 .

[0117] In the formula, S 落料管内截面 The inner diameter of the feed tube 22 is the cross-section, and its value is π*(D4 / 2)^2.

[0118] Step 4: Conveying Completed

[0119] During the conveying of fine particles with a diameter of less than d2 (m) in step three, as the fine particles with a diameter of less than d2 (m) are conveyed along the powder output pipeline 16 to the next process equipment, the pressure measured by the pressure transmitter 5 will gradually decrease (the particles will form resistance in the powder output pipeline 16, and when the particles decrease, the resistance will naturally decrease).

[0120] When the pressure measured by pressure transmitter 5 falls below a certain value (pressure control method) (indicating that the powder in the silo pump has been basically transported clean), or when the powder discharge valve 11, controlled by the program in step three, has been open for a period of time (time control method), this round of powder conveying can be ended.

[0121] At this point, the motor and valves can be shut off in sequence. First, shut off the motor to stop the scraper 37 from rotating. Then, close the program-controlled air supply valve group in the pressure reducing control valve group 10 of the silo pump. After that, wait until the pressure measured by the pressure transmitter 5 is lower than a certain value (because there is no air intake source, and the compressed air escapes along the powder output pipeline 16 to the next process equipment, the pressure in the silo pump will drop rapidly) (pressure control method) or wait for a period of time (time control method) before closing the program-controlled powder discharge valve 11 (time control method).

[0122] Finally, open the program-controlled large particle discharge valve 12. Large particles are discharged due to gravity (a collection hopper can be placed below the large particle discharge valve 12 to collect the large particles). After the large particle discharge valve 12 has been open for a period of time, it can be closed.

[0123] This completes the current round of powder conveying. The next round of conveying can begin either when the powder hopper above the pump is full (using level control method controlled by level gauge 4) or after a certain period of time (using time control method).

[0124] This utility model uses specific examples to illustrate its principles and implementation methods. The above description of the embodiments is only for the purpose of helping to understand the method and core idea of ​​this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the idea of ​​this utility model. In summary, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A pneumatic conveying device, characterized by: include: The silo pump comprises a scraper, a scraper, and a scraper drive assembly. The silo pump is connected to a feed pipe, an exhaust pipe, and a powder output pipe. The bottom structure of the silo pump is a base plate assembly, which is configured to allow air circulation but not powder circulation. An air chamber is provided below the base plate assembly, and the air chamber is connected to a compressed air pipe. The scraper is provided on the upper surface of the base plate assembly. The base plate assembly has a large particle discharge port that extends through both the upper and lower surfaces. The scraper drive assembly is configured to drive the scraper to scrape the large particles on the upper surface of the base plate assembly to the large particle discharge port, which is used to discharge the large particles from the silo pump.

2. A pneumatic conveying apparatus according to claim 1, characterised in that: The base plate assembly includes a perforated grinding disc and a first canvas layer, the upper surface of the first canvas layer being in contact with the perforated grinding disc, and the scraper being disposed on the upper surface of the perforated grinding disc.

3. A pneumatic conveying apparatus according to claim 2, characterised in that: A tray is provided under the canvas, the upper surface of the tray is attached to the lower surface of the canvas, and multiple air holes are evenly provided on the tray.

4. The pneumatic conveying apparatus of claim 1, wherein: The base plate assembly is circular. The drive shaft of the scraper drive assembly passes through the center of the base plate assembly from bottom to top and is fixedly connected to the first end of the scraper. The second end of the scraper is located near the outer periphery of the base plate assembly. The side of the scraper used to scrape and feed materials is the scraping surface. The scraping surface is bent in the direction away from the rotation of the scraper and forms an accumulation area at the top of the bend. When the scraper drive assembly drives the scraper to rotate, the accumulation area moves around the first circumferential trajectory. At least part of the large particle discharge outlet is located below the first circumferential trajectory.

5. The pneumatic conveying device according to claim 1, characterized in that: The scraper is provided in multiple parts, and the multiple scrapers are evenly distributed along the circumference.

6. The pneumatic conveying device according to claim 1, characterized in that: The compressed air pipeline includes several branches, and at least one of the branches is connected to the air chamber.

7. The pneumatic conveying device according to claim 1, characterized in that: The large particle discharge port is connected to a large particle discharge pipeline.

8. The pneumatic conveying device according to claim 7, characterized in that: The large particle discharge pipeline includes a discharge pipe and a large particle discharge valve connected to the bottom of the discharge pipe. Part of the discharge pipe is located inside the air chamber, and at least part of the discharge pipe located inside the air chamber is configured to allow air to pass through but not to allow powder to pass through.

9. The pneumatic conveying device according to claim 8, characterized in that: A portion of the discharge tube has holes, and the portion of the discharge tube with holes is wrapped with a second canvas layer. The portion of the second canvas near the upper and lower edges is clamped and fixed to the discharge tube by a clamping mechanism.

10. The pneumatic conveying device according to claim 4, characterized in that: It also includes a sleeve and a rotary sealing assembly. The air chamber and the base plate assembly constitute an air chamber assembly. The sleeve extends through the upper and lower surfaces of the air chamber assembly and is used to pass through the drive shaft. The rotary sealing assembly includes a sealing shell, a bearing, and a sealing sleeve. The bottom of the sleeve protrudes from the lower surface of the air chamber assembly. The sealing shell is fixedly disposed at the bottom of the sleeve. The sealing sleeve and the bearing are fixedly disposed inside the sealing shell. The drive shaft passes through the sealing sleeve and the bearing, and the drive shaft and the sealing sleeve are in sliding contact.

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