A powder spiral disc pipeline continuous drying system

Abstract

The present invention discloses a continuous drying system for powder spiral disc pipelines, comprising a dryer body, wherein the dryer body is composed of an upper cover at the top, a lower cover at the bottom, and a spiral fluid tube and a particle tube formed by the outer wall and inner wall of the upper cover and the lower cover; an air flow inlet is provided at the inlet end of the particle tube, and a powder inlet is connected to the top of the air flow inlet, and the powder inlet and the air flow inlet are respectively used to connect an external input device to input the powder to be dried and the hot air flow into the particle tube; a fluid inlet is provided on the surface of the dryer body for inputting a hot liquid medium into the fluid tube. The drying system of the present invention has a simple and reliable structure, successfully realizes the flow drying of wet particles of materials, and can meet the needs of continuous production; it has the flexible control characteristics of five variables with a wide range, and can meet the drying needs of different types of materials, materials with different humidity, and materials with different volatility characteristics.

Description

Technical Field

[0001] The present invention relates to the technical field of powder drying, and in particular to a powder spiral disc pipeline continuous drying system. Background Art

[0002] There are three main types of drying methods for powder particles in existing technical solutions, including:

[0003] The first type is centralized drying in a static oven, which is suitable for drying thin layers of powder. When the thickness of the powder particles is large, the drying uniformity is poor, and problems such as local over-drying and local insufficient drying occur, resulting in low drying efficiency. Only centralized drying is possible.

[0004] The second type, centralized fluidized bed drying, uses pipes to transfer hot air. The friction and turning points between the pipes and the cavity consume a large amount of airflow heat and kinetic energy. At the same time, the pipes and working cavity are not insulated, resulting in severe heat dissipation and low energy efficiency. Therefore, centralized drying is the only option. The equipment has a complex structure, large size, and high cost.

[0005] The third type is continuous drying equipment, which uses gas as power and auxiliary mechanical transmission devices (such as transmission belts and push screws) to fluidize the powder. It can meet the needs of continuous drying and improve energy efficiency. However, it is difficult to ensure first-in-first-out drying of materials. Some materials often cannot be discharged smoothly, resulting in over-drying. In addition, the equipment has a complex structure and high cost. Summary of the Invention

[0006] In order to solve the above-mentioned problems of continuous flow drying of powder materials, maintain the first-in-first-out of materials during the drying process, eliminate local accumulation of materials during the drying process, eliminate the problems of over-drying and under-drying, improve the drying uniformity of a batch of materials, simplify the dryer structure, improve the reliability of the drying device, and reduce the cost of the drying device, the present invention provides a powder spiral disc pipeline continuous drying system.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A continuous drying system for powders using a spiral disc pipeline comprises a dryer body, the dryer body comprising an upper cover at the top, a lower cover at the bottom, and a spiral fluid tube and a particle tube formed by the spirally wound outer and inner walls between the upper and lower covers; an air flow inlet is provided at the inlet end of the particle tube, and the top of the air flow inlet is connected to a powder inlet, the powder inlet and the air flow inlet are respectively used to connect to an external input device to input powder to be dried and a hot air flow into the particle tube; a fluid inlet is provided on the surface of the dryer body for inputting a hot liquid medium into the fluid tube; a fluid outlet and a powder outlet are provided in the central area of ​​the bottom of the lower cover of the dryer body, respectively connected to the outlet ends of the fluid tube and the particle tube.

[0009] Preferably, the upper cover, lower cover, outer wall and inner wall are seamlessly connected; the fluid tube and particle tube are both equidistant spiral pipelines, and the connections between the pipelines and the upper cover and the lower cover are all rounded edges, which is conducive to the smooth flow of fluid and powder inside the pipeline.

[0010] Preferably, the spiral pipeline inside the dryer body is constructed using an Archimedean equidistant spiral, and the inner wall and outer wall are formed by using the following mathematical functions (1) and (2) to describe their contour characteristics:

[0011] (1)

[0012] (2)

[0013] Wherein, a and b are design parameters, θ is the contour line position angle variable, the starting point of the spiral line of the inner wall is the spiral origin, and the starting point of the spiral line of the outer wall is a non-origin, and its distance from the origin is b, which is also the distance between the inner wall and the outer wall, that is, the width of the formed fluid tube; r1 is the curvature radius of the contour of the inner wall at any spatial position, and r2 is the curvature radius of the contour of the outer wall at any spatial position; with the spiral origin as the base point, the curvature radius of the spiral line of the inner wall after one rotation is r1=2πa, and the curvature radius of the spiral line of the outer wall after one rotation is r2=2πa+b.

[0014] Preferably, the width b of the fluid tube is not less than 20 mm, and the width c of the particle tube is determined according to the following formula (3):

[0015] (3)

[0016] When determining the width c of the particle tube, c≥b≥20mm should be satisfied. In order to determine r1 and r2 in the actual use of the dryer body, r1 and r2 should be kept changing only with the angle θ. When determining the structure, the width b of the fluid tube and the width c of the particle tube should be determined first.

[0017] Preferably, the dryer body has a disc-like shape, and its thickness H ranges from 0.4 c to 1.0 c.

[0018] Preferably, the number of turns of the outer wall and the inner wall is N, which is determined according to the path length or drying time of the powder to be dried, and N is not less than 3. The length of the material drying path is calculated according to the following formula:

[0019] (4)

[0020] Where, and are the spiral lengths of the inner wall and outer wall respectively, and the calculation formulas are as follows (5) and (6):

[0021] (5)

[0022] (6)

[0023] Where, the relationship between θ and the number of turns N of the outer wall and the inner wall is: .

[0024] Preferably, two through holes are opened in the central area of ​​the dryer body, which are respectively used to connect the powder outlet and the fluid outlet. The two through holes connecting the powder outlet and the fluid outlet are a powder hole and a fluid hole, respectively, and their pore sizes are d1 and d2, respectively. The pore size of the powder hole is 0.4c to 0.8c, and the pore size of the fluid hole is 0.4b to 0.8b.

[0025] Preferably, the wall thickness of the upper cover, outer wall, inner wall and lower cover is 2-6 mm, and for the same dryer body, a uniform wall thickness value is adopted, and the outer edges of the upper cover and the lower cover are evenly distributed along the circumference with several ears for installing the dryer body.

[0026] Preferably, an isolation plate is provided between the fluid tube and the particle tube near the origin of the spiral, which is used to isolate the fluid tube and the particle tube from each other. When the powder and fluid flow from the outside to the starting point of the spiral line, they do not communicate with each other, but flow out from the powder outlet and the fluid outlet respectively.

[0027] Preferably, the dryer body is installed horizontally, the channel direction of the powder inlet is vertical, the channel direction of the air flow inlet is horizontal and tangent to the spiral line, the direction of the fluid inlet is horizontal and perpendicular to the spiral line, the direction of the powder outlet is vertical, and the direction of the fluid outlet is also vertical.

[0028] Compared with the prior art, the present invention has the following beneficial effects.

[0029] 1. The drying system of the present invention has a simple and reliable structure, successfully realizes the flow drying of wet particles of materials, and can meet the needs of continuous production;

[0030] 2. The present invention can maintain the first-in-first-out order of materials during the drying process, eliminate local accumulation of materials during the drying process, eliminate the problems of over-drying and under-drying, and improve the drying uniformity of a batch of materials;

[0031] 3. The present invention simplifies the dryer structure, improves the reliability of the drying device, and reduces the cost of the drying device;

[0032] 4. The present invention has the flexible control feature of five variables in a wide range, which can meet the drying requirements of different types of materials, materials with different humidity, and materials with different volatility characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of the three-dimensional structure of an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the main structure of an embodiment of the present invention;

[0035] Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure of AA;

[0036] Figure 4 for Figure 3 Schematic diagram of the enlarged structure at I in the middle;

[0037] Figure 5 This is a schematic diagram of the flow direction of solid, liquid and gas in the present invention.

[0038] In the figure: 1, air inlet, 2, powder inlet, 3, fluid inlet, 4, fluid outlet, 5, powder outlet, 6, dryer body, 601, upper cover, 602, lower cover, 603, ear seat, 604, outer wall, 605, inner wall, 606, fluid tube, 607, particle tube, 608, rounded edge, 609, spiral origin. DETAILED DESCRIPTION

[0039] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "top", "bottom", "inside", "outside", "vertical", "horizontal", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0041] like Figures 1 to 4As shown, the embodiment of the present invention includes a dryer body 6, which is composed of an upper cover 601 at the top, a lower cover 602 at the bottom, and a spiral outer wall 604 and an inner wall 605 between the upper cover 601 and the lower cover 602 to form a spiral fluid pipe 606 and a particle pipe 607; the upper cover 601, the lower cover 602, the outer wall 604 and the inner wall 605 are seamlessly connected; the fluid pipe 606 and the particle pipe 607 are both equidistant spiral pipes, and the connection between the pipes and the upper cover 601 and the lower cover 602 uses rounded edges 608, which is conducive to fluid The powder flows smoothly inside the pipeline; an air flow inlet 1 is provided at the inlet end of the particle tube 607, and the top of the air flow inlet 1 is connected to the powder inlet 2, the powder inlet 2 and the air flow inlet 1 are respectively used to connect an external input device to input the powder to be dried and the hot air flow into the particle tube 607; a fluid inlet 3 is provided on the surface of the dryer body 6, for inputting hot liquid medium into the fluid tube 606; a fluid outlet 4 and a powder outlet 5 are provided in the central area of ​​the bottom of the lower cover 602 of the dryer body 6, which are respectively connected to the outlet ends of the fluid tube 606 and the particle tube 607.

[0042] As a preference, Figure 4 As shown, the spiral pipeline inside the dryer body 6 is constructed using Archimedean equidistant spirals. The inner wall 605 and outer wall 604 are formed using the mathematical functions of formula (1) and formula (2) to describe their contour features: where θ is the contour position angle variable, a=21.74mm, and b=58mm. The starting point of the spiral line of the inner wall is the spiral origin 609, and the starting point of the spiral line of the outer wall is a non-origin, and its distance from the origin is b=58mm. This value is the distance between the inner wall 605 and the outer wall 604, that is, the width of the fluid tube 606 formed is b=58mm. r1 is the curvature radius of the inner wall 605 contour at any spatial position, and r2 is the curvature radius of the outer wall 604 contour at any spatial position. Taking the spiral origin 609 as the base point, the curvature radius of the inner wall 605 after one spiral rotation is r1=2πa=136.53 mm, and the curvature radius of the outer wall 604 after one spiral rotation is r2=2πa+b=194.53 mm.

[0043] The flow channel width c of the particle tube 607 can be determined according to formula (3): =78.59mm. The dryer body 6 is disc-shaped, and its thickness H=0.8c=62.87mm.

[0044] The number of turns of the outer wall 604 and the inner wall 605 is N=6. The length of the material drying path is calculated according to formula (4): =16566.64mm.

[0045] Where, and are the spiral lengths of the inner wall 605 and the outer wall 604, respectively. The calculation formulas are as follows based on (5) and (6):

[0046] =15485.45mm

[0047] =17647.82mm

[0048] Wherein, θ is the arc length unit in mm, and its relationship with the number of turns N (this embodiment adopts the dryer body 6 structure design with N=6) is: =37.68mm.

[0049] Preferably, two through holes are provided in the central area of ​​the dryer body 6, which are respectively used to connect the powder outlet 5 and the fluid outlet 4. The two through holes connecting the powder outlet 5 and the fluid outlet 4 are a powder hole and a fluid hole, respectively, and their aperture sizes are d1 and d2, respectively. The aperture size of the powder hole is 0.6c=47.16mm, and the aperture size of the fluid hole is 0.5b=29mm; the wall thickness of the upper cover 601, the outer wall 604, the inner wall 605 and the lower cover 602 are all 3mm, and for the same dryer body 6, a uniform wall thickness value is adopted, and the outer edges of the upper cover 601 and the lower cover 602 are evenly distributed along the circumference with a number of ear seats 603 for installing the dryer body 6.

[0050] Working principle: Before operation of this embodiment, the dryer body 6 is first fixed to a platform through the ear seat 603. The dryer body 6 is disc-shaped and arranged horizontally on the platform. The channel direction of the powder inlet 2 is vertical, the channel direction of the air flow inlet 1 is horizontal and tangent to the spiral line, the direction of the fluid inlet 3 is horizontal and perpendicular to the spiral line, the direction of the powder outlet 5 is vertical, and the direction of the fluid outlet 4 is also vertical.

[0051] like Figure 5As shown, air inlet 1 is connected to an external airflow generator. The airflow generator is internally equipped with an induced draft fan, a filter, a heater, and a dehumidifier. This device processes the indoor air through five steps: primary filtration, induced draft, intermediate filtration, dehumidification, heating, and high-efficiency filtration, producing a hot, clean, and dry airflow. The airflow passes through air inlet 1 and enters particle tube 607. While passing through air inlet 1, the temperature of the hot airflow is controlled between 60°C and 90°C, in this embodiment, 70°C. Powder inlet 2 is externally connected to the powder generator. Wet particles are continuously fed to powder inlet 2 via an external pipeline. The wet particles are transported to the upper end of powder inlet 2 and fall by gravity into air inlet 1. Fluid inlet 3 is connected to an external pipeline and is used to deliver a hot fluid to fluid tube 606. The hot fluid is a water medium. After being heated by an external heating device to a temperature of 60°C to 90°C, the hot fluid is then transported to the interior of dryer body 6, in this embodiment, 85°C.

[0052] At the entrance, when the wet particles fall into the air flow inlet 1, their initial temperature is 25℃ and their kinetic energy is 0. At this time, they come into contact with the hot air flow, and instantaneous kinetic energy exchange and thermal energy exchange occur at the entrance. The energy exchange process conforms to the law of conservation of energy. The initial kinetic energy obtained by the wet particles causes them to move tangentially along the inside of the particle tube. The initial velocity of the wet particles at the air flow inlet is At the same time, the instantaneous heat exchange makes its initial temperature =48°C. Initial velocity of particles It can be described by the following formula (7):

[0053] (7)

[0054] Where, is the airflow mass per unit time, which is 645 kg / h; is the mass of particles entering the inlet per unit time, which is 180 kg / h; is the initial velocity of the thermal airflow, which is 28.1 m / s; is the rate after the heat energy exchange, which is 27.8m / s. Equal to 7.81m / s.

[0055] At the inlet, the external hot fluid flows through the fluid inlet 3. Since it carries heat, the hot fluid transfers heat to the particle tube 607 through the fluid tube 606, and further transfers heat to the wet particles flowing through the particle tube 607 through the particle tube 607. Under the condition of instantaneous temperature rise, the moisture inside the wet particles begins to evaporate.

[0056] The powder outlet 5 is connected to an external vacuum pump, which is used to extract the internal gas in the dryer body 6, so that the interior thereof presents a negative pressure environment, maintaining a vacuum level of -60kPa, and increasing the conveying power for the wet particles. Through the operation of the vacuum generator, the wet particles undergo a one-way spiral motion in the particle tube 607, satisfying the full motion from the inlet to the outlet of the dryer body 6. At the same time, the fluid outlet 4 is connected to an external water pump, and the fluid inlet 3, the dryer body 6, and the fluid outlet 4 are connected through a pipeline to form a closed-loop fluid circulation working mode. A heating device is added to the circulation route to keep the temperature controlled in the range of 60°C-90°C, which is 85±2°C in this embodiment.

[0057] From the entrance, wet particles enter and gain initial kinetic energy and thermal energy under the push of hot air flow. The initial velocity of the particles is =31m / s, the initial temperature is =48℃, when the vacuum pump is started, the initial velocity of the wet particles will further increase to , in the particle tube 607, the entire flow is satisfied. From the inlet to the outlet, the particle flow distance is =16566.64mm, the friction force of the particle tube 607 must be overcome to do work, and the friction coefficient between the particle tube 607 and the particle is =0.3, and the full flow condition is as follows formula (8):

[0058] (8)

[0059] The total drying time is as follows: The average rate is used as the calculation method and is determined according to the following formula (9):

[0060] (9)

[0061] For the export rate according to be controlled, including , for the initial velocity of particles in the dryer body 6 and total drying time The control needs to achieve:

[0062] =9.92m / s

[0063] =3.04s

[0064] When the wet particles enter the inlet of the dryer body 6, the initial moisture content is =42%±2%, after drying through the particle tube 607, its moisture content is =4%±2%. In order to ensure the drying effect of the dryer body 6 on the wet particles, the moisture content of the wet particles should be reduced from =42%±2% Volatility decreased to =4%±2%. This embodiment has carried out a combination test of process parameters to determine the above optimal process parameters. Deviation control can be achieved in the following five process parameters:

[0065] ①. The temperature of the inlet hot air flow can be controlled within the range of 70±2℃;

[0066] ② The flow rate of the inlet hot air flow is controllable within the range of 28.1±2m / s;

[0067] ③. The temperature of the inlet hot fluid is controllable within the range of 85±2℃;

[0068] ④. The working negative pressure of the vacuum pump is controllable within the range of -60±2kPa;

[0069] ⑤. The length of the fluid pipe inside the dryer body is L=16566.64±10mm.

[0070] Finally, if Figure 5 As shown, at the outlet of the dryer body 6, the wet particles become dry particles. At this time, they are still mixed with the air flow. When the wet particles are sucked out by the vacuum pump, the particles and the gas enter the filter bag of the vacuum pump respectively. The filter bag is discharged through the gas, while the dry particles are adsorbed on the filter bag. Under the action of the backflush device included in the vacuum pump and its own gravity, they fall into the discharge bin to achieve discharge.

[0071] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A powder spiral disc pipeline continuous drying system, characterized by: The dryer comprises a main body, which is composed of an upper cover at the top, a lower cover at the bottom, and a spiral fluid tube and a particle tube formed by the spirally wound outer wall and inner wall between the upper cover and the lower cover; an air flow inlet is provided at the inlet end of the particle tube, and the top of the air flow inlet is connected to a powder inlet, and the powder inlet and the air flow inlet are respectively used to connect an external input device to input the powder to be dried and the hot air flow into the particle tube; a fluid inlet is provided on the surface of the dryer body for inputting a hot liquid medium into the fluid tube; a fluid outlet and a powder outlet are provided in the central area of ​​the bottom of the lower cover of the dryer body, which are respectively connected to the outlet ends of the fluid tube and the particle tube.

2. The powder spiral disc pipeline continuous drying system according to claim 1, characterized in that: The upper cover, lower cover, outer wall and inner wall are seamlessly connected; the fluid tube and particle tube are both equidistant spiral pipelines, and the connections between the pipelines and the upper cover and the lower cover are all rounded edges, which is conducive to the smooth flow of fluid and powder inside the pipeline.

3. The powder spiral disc pipeline continuous drying system according to claim 2, characterized in that: The spiral pipeline inside the dryer body is constructed using Archimedean equidistant spirals, and the inner wall and outer wall are formed using the following mathematical functions (1) and (2) to describe their contour features: r1=aθ (1) r2=aθ+b (2) Wherein, a and b are design parameters, θ is the contour line position angle variable, the starting point of the spiral line of the inner wall is the spiral origin, and the starting point of the spiral line of the outer wall is a non-origin, and its distance from the origin is b, which is also the distance between the inner wall and the outer wall, that is, the width of the formed fluid tube; r1 is the curvature radius of the contour of the inner wall at any spatial position, and r2 is the curvature radius of the contour of the outer wall at any spatial position; with the spiral origin as the base point, the curvature radius of the spiral line of the inner wall after one rotation is r1=2πa, and the curvature radius of the spiral line of the outer wall after one rotation is r2=2πa+b.

4. The powder spiral disc pipeline continuous drying system according to claim 3, characterized in that: The width b of the fluid tube is not less than 20 mm, and the width c of the particle tube is determined according to the following formula (3): c=2πa-b (3) When determining the width c of the particle tube, c≥b≥20mm should be satisfied. In order to determine r1 and r2 in the actual use of the dryer body, r1 and r2 should be kept changing only with the angle θ. When determining the structure, the width b of the fluid tube and the width c of the particle tube should be determined first.

5. The powder spiral disc pipeline continuous drying system according to claim 4, characterized in that: The dryer body has a disc-like shape, and its thickness H ranges from 0.4 to 1.0 cm.

6. The powder spiral disc pipeline continuous drying system according to claim 5, characterized in that: The number of turns of the outer wall and the inner wall is N, which is determined according to the path length of the powder to be dried or the drying time. N is not less than 3. The length of the material drying path is calculated according to the following formula: ； Wherein, L1 and L2 are the spiral lengths of the inner wall and outer wall respectively, and the calculation formulas thereof are as follows (5) and (6): ； ； Wherein, the relationship between θ and the number of turns N of the outer wall and the inner wall is: θ = 2πN.

7. The powder spiral disc pipeline continuous drying system according to claim 6, characterized in that: Two through holes are provided in the central area of ​​the dryer body, which are respectively used to connect the powder outlet and the fluid outlet. The two through holes connecting the powder outlet and the fluid outlet are the powder hole and the fluid hole, respectively, and their pore sizes are d1 and d2, respectively. The pore size of the powder hole is 0.4 c to 0.8 c, and the pore size of the fluid hole is 0.4 b to 0.8 b.

8. A powder spiral disc pipeline continuous drying system according to claim 1 or 7, characterized in that: The wall thickness of the upper cover, outer wall, inner wall and lower cover is 2-6 mm, and for the same dryer body, a uniform wall thickness value is adopted. The outer edges of the upper cover and the lower cover are evenly distributed along the circumference with a number of ear seats for installing the dryer body.

9. The powder spiral disc pipeline continuous drying system according to claim 8, characterized in that: The fluid tube and the particle tube are provided with an isolation plate near the origin of the spiral, which is used to isolate the fluid tube and the particle tube from each other. When the powder and fluid flow from the outside to the starting point of the spiral line, they do not communicate with each other, but flow out from the powder outlet and the fluid outlet respectively.

10. The powder spiral disc pipeline continuous drying system according to claim 9, characterized in that: The dryer body is installed horizontally, the channel direction of the powder inlet is vertical, the channel direction of the air flow inlet is horizontal and tangent to the spiral line, the direction of the fluid inlet is horizontal and perpendicular to the spiral line, the direction of the powder outlet is vertical, and the direction of the fluid outlet is also vertical.

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