Talcum powder pipeline conveying device

Abstract

The invention relates to the technical field of powder conveying, in particular to a talcum powder pipeline conveying device which is particularly suitable for solving the problem of accelerated abrasion of a bent pipe part caused by powder impact. A pit flow device is arranged on an upstream straight pipe section of the bent pipe and vertically sprays compressed air through a radial through hole with the diameter phi of 250 microns in an annular interlayer, so that powder forms a 35-degree diffusion angle; the ratio L of the full curvature radius of the pipe diameter of the bent pipe to the positioning distance of the pit flow device to the inlet of the bent pipe is equal to (3-5) d0, and a 50mu m tungsten carbide layer is sprayed on the inner wall of the straight pipe section. And intelligent control dynamically regulates the pressure through a formula P = P0 + alpha (v-v0) 2, and responds to the sudden change of the flow velocity within 0.2 second, so that the abrasion rate of the elbow pipe is remarkably reduced in the pneumatic transportation process of talcum powder.

Description

Technical Field

[0001] This invention relates to the field of powder conveying technology, specifically to an anti-wear device for conveying high-hardness talc powder through pipelines, which is particularly suitable for solving the problem of accelerated wear caused by powder impact at bends in pipes. Background Technology

[0002] In industrial production, talc powder is widely used in plastics, coatings, papermaking, and other industries due to its excellent physicochemical properties. However, a long-standing technical challenge in the pneumatic conveying of talc powder via pipelines is the susceptibility to abnormal wear and even perforation at the bends of the conveying pipes. Figure 1 As shown in the diagram. The root cause of this phenomenon lies in the unique physical properties of talc particles—despite their fine particle size, their crystal structure is hard and sharp. When the powder flows through a straight pipe section at a high velocity, the friction and wear between the particles and the pipe wall are still within a controllable range; however, once it enters the curved pipe area, the sudden change in the direction of movement causes the talc particles to violently impact the inner and outer walls of the curved pipe under centrifugal force. This significantly shortens the service life of the transport system and severely restricts the company's production efficiency.

[0003] The core of the aforementioned technical dilemma lies in the fact that existing solutions have not established a synergistic mechanism of "powder physical properties - structural parameters - dynamic control", and in particular, they lack the ability to quantify the response of talc powder. This is precisely the technical barrier that this invention aims to overcome. Summary of the Invention

[0004] This invention aims to solve the problem in traditional pneumatic pipeline talc powder transportation systems where the angle of the path changes, resulting in short service life and easy wear of the bends due to the impact and abrasion of talc powder. To achieve the above objective, this invention provides a talc powder pipeline conveying device, comprising:

[0005] A pit flow device is installed on the straight pipe section upstream of a bend. It includes an annular interlayer formed by an inner pipe and an outer pipe that are coaxially sleeved. The inner pipe has at least three radial through holes evenly distributed around its circumference. The interlayer is connected to a compressed air source.

[0006] The bend in the pipe connected to the flow-through device has a diameter d. b satisfy:

[0007] Where d0 is the reference pipe diameter of the straight pipe section, v0 is the reference powder flow velocity of the straight pipe section, ρ is the density of talc powder, k is the empirical coefficient of the curvature of the bend, which is taken as 0.15 to 0.25, and σ is the impact resistance of the bend material.

[0008] In one embodiment, the axis of the radial through hole is perpendicular to the axis of the inner tube, and the angle between adjacent radial through hole axes is 120°.

[0009] The ratio of the radial through-hole diameter to the average particle size of talc powder is in the range of 8 to 10:1.

[0010] In one embodiment, a pressure regulating valve is installed at the outlet end of the compressed air source;

[0011] A pressure sensor located within an annular interlayer;

[0012] The controller is electrically connected to the pressure sensor and the pressure regulating valve, and is configured to adjust the compressed air pressure P according to the real-time flow velocity v detected by the straight pipe section flow velocity sensor, satisfying P = P0 + α(v - v0). 2 Where P0 is the reference pressure and α is the flow rate compensation coefficient.

[0013] In one embodiment, the radius of curvature R of the bend is related to the pipe diameter d. b ratio

[0014] In one embodiment, the pit flow device is installed at a distance of L = (3~5)d0 from the bend inlet.

[0015] In one embodiment, the inner wall of the bend is coated with a tungsten carbide layer with a thickness of ≥50μm.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] This invention injects 0.02MPa compressed air into the powder through micropores in the flow-through device, causing the talc powder to form a stable 35° diffusion angle, thus eliminating the impact hotspots of the bend pipe at the source. Combined with an optimized bend pipe diameter of 60mm and a 50μm tungsten carbide coating on the inner wall, this triple protection synergistically reduces the bend pipe wear depth from 150μm / 100h to 15μm / 100h, achieving a lifespan exceeding 3500 hours. The intelligent control system uses the formula P=P0+α(v-v0). 2 Dynamic pressure regulation, responding to sudden changes in flow rate within 0.2 seconds, significantly reduces the incidence of abnormal wear. Curvature ratio Flow field simulation verification reduced shear stress, and the positioning of the pit flow device L=(3~5)d0 ensured the uniformity of powder distribution. The two worked together to reduce pressure loss, ultimately achieving a reduction in blockage rate and energy consumption, forming a long-term closed loop of "disturbance prevention of agglomeration - structural impact resistance - intelligent energy consumption control". Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0019] Figure 1 This is a real-world example of damage occurring at bends in the pneumatic pipeline transport of talc powder in existing technologies.

[0020] Figure 2 This is a schematic diagram of the overall structure of the talc powder pipeline conveying device of the present invention;

[0021] Figure 3 This is a schematic diagram of the pit flow device of the present invention;

[0022] In the diagram, 1 is a bend; 2 is a straight section; 3 is an inner pipe; 4 is an outer pipe; 5 is an annular interlayer; 6 is an air inlet pipe; and 7 is a radial through hole. Detailed Implementation

[0023] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention.

[0024] This embodiment provides a talc powder pipeline conveying device. Through the coordinated design of a flow-inducing device and an impact-resistant bend 1, the impact of talc powder on the inner wall of the bend 1 during pneumatic transport is reduced, thus extending the service life of the talc powder pipeline conveying system. The conveying density is ρ = 0.65 g / cm³. 3 For example, the talc powder has a reference pipe diameter of d0 = 50 mm in straight pipe section 2, a powder flow velocity of v0 = 12 m / s in straight pipe section 2, and high chromium cast iron is selected as the material for bend 1.

[0025] Specifically, the inner tube 3 can be made of 304 stainless steel seamless pipe with specifications of φ50×3mm and inner diameter d0=50mm; the outer tube 4 is made of carbon steel sleeve with specifications of φ60×3mm, forming a 5mm annular sandwich 5 with the inner tube 3. The average particle size of talc powder is 25μm. To avoid clogging of the radial through-hole 7, its pore size needs to be precisely controlled. Specifically, through the radial through-hole 7 anti-clogging comparison test, under the same conveying density and flow rate, a high-speed camera was used to record and compare the talc powder diffusion angle and clogging rate when the ratio of the radial through-hole 7 diameter to the average particle size of talc powder was in the range of 8:1, 9:1, and 10:1. The comparison results are shown in Table 1 below:

[0026]

[0027] Table 1. Comparative Test Results of Radial Through-hole Anti-clogging

[0028] Therefore, the opening size of the radial through hole 7 was selected as φ250μm to balance the anti-clogging and diffusion effects. The radial through holes 7 are evenly distributed along the circumference of the inner tube 3, that is, the included angle between the axes of adjacent radial through holes 7 is 120°, and the error needs to be controlled within 0.5°.

[0029] Optionally, an intake pipe 6 extends outward from the outer pipe 4 and connects to the outlet pipe of the air compressor, allowing the air compressor to supply gas into the annular jacket 5 to achieve a reference pressure P0 of 0.02 MPa. The air compressor can be an Atlas Copco GA11VSD model. Furthermore, the air circuit between the air compressor and the annular jacket 5 is equipped with a proportional pressure regulating valve (e.g., manufacturer: SMC, model: ITV0010) to adjust the gas pressure in the annular jacket 5 in real time.

[0030] Compressed air in the annular interlayer 5 is injected into the powder flow through the radial through-hole 7, generating lateral momentum. This increases the powder flow diffusion angle from 5° to 35° and expands the impact area to three times its original size, effectively reducing the impact force of the powder flow on the unit area of ​​the bend wall 1.

[0031] Taking the empirical coefficient of curvature k = 0.2 for bend 1 and the material impact strength σ = 280 MPa as an example, calculate the critical diameter of bend 1:

[0032] The critical pipe diameter is 5.9 mm.

[0033] To balance transportation efficiency and safety redundancy, and to avoid powder sedimentation, d was actually selected. b =60mm.

[0034] To optimize streamline curvature and suppress secondary flow and local high-pressure zones in powder, simulations based on the discrete phase model of ANSYS Fluent revealed that: At times, such as The centrifugal effect on the outside of bend 1 causes a sharp increase in the powder concentration gradient, and the local shear stress can reach 4.2 times that at the inlet; while increasing the ratio to For example, d b When the radius of curvature is 60mm and the radius of curvature (R) is 270mm, flow field analysis shows that the centrifugal force distribution is more uniform and the maximum shear stress is significantly reduced. In practical engineering, this curvature can be achieved using lost foam casting, combined with laser scanning positioning to ensure the geometric accuracy of the bend.

[0035] Optionally, when talc powder flows through straight pipe section 2, a high-precision flow velocity sensor (such as Endress+Hauser FSV-200) installed in straight pipe section 2 continuously captures powder flow velocity data at a sampling frequency of 800 times per second, and transmits it to the Siemens S7-1200 controller in real time via a 20mA analog signal. The controller's built-in dedicated algorithm first compares the real-time flow velocity v with a preset reference value v0 = 12m / s;

[0036] If a deviation of |v-v0|≥0.3m / s is detected, the preset pressure compensation model P=P0+α(v-v0) is immediately invoked. 2Dynamic calculations were performed, where P0 = 0.02 MPa is the reference pressure and α = 0.0005 MPa·s. 2 / m 2 The compensation coefficient was calibrated through 250 sets of impact tests. For example, when the flow rate suddenly increases to 15 m / s, the controller completes the calculation within a 1 ms logic cycle, obtaining P = 0.0245 MPa. It then sends a PWM modulation command to the SMC ITV0010 proportional pressure regulating valve via the PROFINET industrial bus. This valve, based on the piezoelectric ceramic drive principle, linearly increases the compressed air pressure from 0.02 MPa to the target value within 0.2 s, with pressure fluctuations controlled within ±1.5% during the response. After execution, the Honeywell PSM-01L micro-pressure sensor installed in the annular interlayer 5 transmits the actual pressure value in real time. The controller compares the target value with the measured value using a PID algorithm. If the error exceeds ±2%, a secondary calibration is initiated until the pressure stabilizes within the set range.

[0037] Furthermore, too close a distance (L < 3d0) will cause interference between the compressed air flow field and the bend pipe flow field, generating eddies and exacerbating local wear; too far a distance (L > 5d0) will cause the powder to re-aggregate due to the attenuation of disturbance. Therefore, in order to balance the powder disturbance effect and the flow field stability, in the specific implementation, the flow field of the straight pipe section 2 was calibrated using a particle image velocimeter: when d0 = 50 mm, measurement sections were set at three locations: L = 3d0 = 150 mm, L = 4d0 = 200 mm, and L = 5d0 = 250 mm. The results showed that when L = 200 mm, the standard deviation of the powder transverse velocity reached a peak value of 0.28 m / s, and the turbulence intensity was controlled at 8%. Therefore, the flow trap device was installed 200 mm away from the inlet of bend 1.

[0038] Optionally, to further address the issue of tube wall scratches caused by high-speed impact from quartz impurities in the powder, a tungsten carbide layer can be sprayed onto the inner wall of the bend 1. Specifically, the inner wall of the bend is first roughened by sandblasting until it reaches Sa3.0 grade. Then, using propane-oxygen as fuel, WC-12Co powder with a particle size of 5-20μm is accelerated to 800m / s to impact the substrate of the bend 1 wall, forming a dense coating 50μm thick.

[0039] Actual operating data shows that, after optimizing the pipe diameter of the bend 1 and controlling the powder diffusion angle, the wear depth of the bend 1 is reduced from 150μm / 100h in the traditional solution to 15μm / 100h, a reduction of 90%. It can also effectively prevent quartz particles from embedding into the pipe wall, avoiding crack propagation caused by local stress concentration. Combined with the pit flow device and pipe diameter optimization design, the overall service life of the bend is extended from 800 hours to more than 3500 hours, while reducing maintenance costs caused by frequent downtime and replacement.

[0040] In summary, this embodiment achieves a talc powder bulk density of 0.65 g / cm³. 3 With an average particle size of 25μm, the powder flows through straight pipe section 2 at a target flow rate of 12m / s. The reference pipe diameter of straight pipe section 2 is 50mm. Under this condition, the flow-in-the-pit device vertically injects 0.02MPa compressed air through φ250μm micropores evenly distributed around the inner pipe 3, dispersing the powder to form a 35° diffusion angle. When the flow velocity sensor detects an abnormal change in flow velocity, the controller activates the flow control according to the formula P=P0+α(v-v0). 2 The target pressure is calculated in real time, and the proportional pressure regulating valve is driven to complete the pressurization within 1 second to avoid powder agglomeration. The diffused powder then enters a thickened bend 1 with a diameter of 60mm and a radius of curvature of 240mm, where the flow velocity is reduced to 1.2m / s and the kinetic energy is reduced to 1% of its original value. A 50μm tungsten carbide coating on the inner wall of the bend protects against scratches from impurities. This embodiment achieves a synergistic improvement in wear control and energy consumption optimization through closed-loop control of "flow velocity monitoring, dynamic pressure compensation, powder diffusion, bend speed reduction, and coating protection."

Claims

1. A talc powder pipeline conveying device, characterized in that, include: A pit flow device is provided on the straight pipe section (2) upstream of the bend (1), which includes an annular sandwich (5) formed by an inner pipe (3) and an outer pipe (4) coaxially sleeved, wherein at least three radial through holes (7) are evenly distributed around the inner pipe (3), and the annular sandwich (5) is connected to a compressed air source. The bend (1) connected to the pit flow device has a diameter d. b satisfy: Wherein, d0 is the reference pipe diameter of the straight pipe section (2), v0 is the reference powder flow velocity of the straight pipe section (2), ρ is the density of talc powder, k is the empirical coefficient of curvature of the bend (1), which is taken as 0.15~0.25, and σ is the impact resistance of the material of the bend (1).

2. The talc powder pipeline conveying device according to claim 1, characterized in that: The axis of the radial through hole (7) is perpendicular to the axis of the inner tube (3), and the included angle between the axes of adjacent radial through holes (7) is 120°. The ratio of the diameter of the radial through hole (7) to the average particle size of the talc powder is in the range of 8 to 10:

1.

3. The talc powder pipeline conveying device according to claim 1, characterized in that, Also includes: A pressure regulating valve installed at the outlet end of the compressed air source; A pressure sensor is installed in the annular interlayer (5); The controller is electrically connected to the pressure sensor and the pressure regulating valve, and is configured to adjust the compressed air pressure P according to the real-time flow velocity v detected by the flow velocity sensor of the straight pipe section (2) to satisfy P=P0+α(v-v0). 2 Where P0 is the reference pressure and α is the flow rate compensation coefficient.

4. The talc powder pipeline conveying device according to claim 1, characterized in that: The radius of curvature R of the bend (1) is related to the pipe diameter d. b ratio 5. The talc powder pipeline conveying device according to claim 1, characterized in that: The installation position of the pit flow device is L = (3~5)d0 from the inlet of the bend (1).

6. The talc powder pipeline conveying device according to claim 1, characterized in that: The inner wall of the bent pipe (1) is coated with a tungsten carbide layer with a thickness of ≥50μm.

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