A vacuum drying device and drying method for natural rubber

Abstract

The present application relates to a kind of vacuum drying device and drying method suitable for natural rubber, including support, shell and spiral lifting part.Support is used to erect shell.Shell is sealed cabin, including the feed inlet in the top of shell, vacuum port and the discharge outlet in the bottom of shell;Feed inlet and discharge outlet are provided with valve installation;Shell outer wall is provided with hollow sandwich, and the heating medium is introduced into hollow sandwich, and the material in shell can be heated.Spiral lifting part is vertically arranged and installed in shell, for lifting the material in shell from bottom to top.The drying method using the device can dry natural rubber material at relatively low temperature, avoid high temperature on the thermal oxidation and decomposition of rubber, maintain the quality and performance of rubber.At the same time, due to the strong adhesion of natural rubber, the material is lifted by spiral lifting part in the device and let it free fall to prevent material from hardening into block, better for material heating and drying, improve drying efficiency.

Description

Technical Field

[0001] This invention relates to the field of drying natural rubber, and in particular to a vacuum drying apparatus and method suitable for natural rubber. Background Technology

[0002] After harvesting, natural rubber requires primary processing, which generally includes the latex line, wet line, and dry line. The wet line process mainly includes a series of operations such as crushing, soaking, extrusion washing, creping, shredding, pelletizing, drying, weighing, packaging, and sampling for grading. Among these, drying is the key step in the primary processing of natural rubber. The tunnel-type hot air drying cabinet currently used in the industry is an essential piece of equipment for most primary processing plants at home and abroad. However, it has high energy consumption, large footprint, and low automation. Current drying equipment adopts a hot air deep bed drying mode. The wet rubber granules (moisture content ≤40%) formed by the shredder in the "wet line" are piled up to a height of more than 350mm after loading. In order to improve drying efficiency, a relatively high drying temperature (120±3℃) is generally used. However, because the temperature is difficult to control, it is easy to approach the critical temperature of 129℃ for molecular chain breakage. Therefore, the temperature and humidity of hot air drying are difficult to control, resulting in low drying efficiency. Moreover, natural rubber is easily affected by oxidation during the open drying process, leading to a decline in rubber quality. Because natural rubber is a poor conductor of heat and has strong self-adhesion during initial processing, hot air drying is inefficient and prone to quality problems such as stickiness, underdeveloped rubber, and thermal-oxidative degradation, which are detrimental to product performance. Drying has become a prominent problem restricting the development of the industry.

[0003] To improve the drying efficiency of natural raw rubber, enhance product quality, improve process stability, control costs, and reduce environmental pollution, it is necessary to study the drying process and key equipment for wet natural raw rubber granules in conjunction with energy utilization methods, and explore new drying modes that are easy to promote and apply industrially. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a vacuum drying apparatus and method suitable for natural rubber. The apparatus feeds the material into the vacuum drying unit for drying, simultaneously crushing and agitating the material during drying. This improves drying efficiency while preventing the material from becoming sticky, undercooked, or subject to thermo-oxidative degradation. Specifically, the objective of this invention is achieved as follows:

[0005] A vacuum drying apparatus suitable for natural rubber, comprising:

[0006] The support frame is used to support the casing.

[0007] A housing is mounted on the bracket. The housing is a sealed chamber. The housing includes a feed inlet and a vacuum port at the top of the housing and a discharge port at the bottom of the housing. Valves are installed at the feed inlet and the discharge port. A hollow interlayer is provided on the outer wall of the housing. A heat medium is introduced into the hollow interlayer to heat the material inside the housing.

[0008] The spiral lifting section is vertically installed inside the housing and is used to lift the material inside the housing from the bottom to the top.

[0009] Furthermore, the spiral lifting section includes a stirring shaft, spiral blades, a sleeve, and a motor; the stirring shaft is rotatably and vertically installed inside the housing, and the spiral blades are installed on the outer surface of the stirring shaft; the motor is installed at the top of the housing, and the output end of the motor is connected to the upper end of the stirring shaft, enabling the stirring shaft to rotate; the sleeve is fixedly installed at the top of the housing via several spaced connecting rods, and the sleeve body is fitted over the outer edge of the spiral blades; a separation section is installed inside the sleeve, which can separate materials that are stuck together when the material is lifted by the spiral blades.

[0010] Furthermore, the separation section includes a tearing section and a cutting section; the tearing section is toothed, with the tooth tips vertically downward and installed at the bottom of the cylinder; the cutting section includes a fixed blade installed on the inner wall of the upper end of the sleeve; the fixed blade includes a blade holder and a blade body; the blade holder is fixedly installed against the inner wall of the sleeve and is used to support the blade body; the blade body is plate-shaped, with a trapezoidal surface, and its lower bottom edge is connected to the blade holder and supported in the blade holder; the blade body is inclined in the direction of rotation of the stirring shaft and forms a certain angle with the horizontal plane; when the spiral blade lifts the material through the sleeve, the tearing section can tear the material, and the cutting section can cut the material.

[0011] Furthermore, the housing includes an upper housing and a lower housing; the upper housing is cylindrical, the lower housing is frustum-shaped, the upper surface of the lower housing has the same diameter as the lower surface of the upper housing, and the upper housing and the lower housing are fixedly connected and installed.

[0012] Furthermore, a heat medium inlet is provided at the bottom of one side of the upper shell, and a heat medium outlet is provided at the top of the opposite side; a heat medium inlet is provided at the bottom of one side of the lower shell, and a heat medium outlet is provided at the top of the opposite side; the heat medium inlet and the heat medium outlet allow the heat medium to pass through the hollow interlayer of the upper shell and the lower shell.

[0013] Furthermore, the stirring shaft has a double-layer tube structure. The bottom of the inner tube has a connecting port that connects to the outer tube, the top of the inner tube has a heat medium inlet, and the top side of the outer tube has a heat medium outlet. Through the heat medium inlet and the heat medium outlet, the heat medium can enter from the inner tube of the stirring shaft, enter the outer tube, and then be discharged.

[0014] A drying method for natural rubber involves feeding the material into a vacuum chamber for drying; the chamber walls are hollow and can be circulated with a heat transfer medium to heat the material inside; during drying, the material is lifted from the bottom of the chamber to the top and then allowed to fall naturally, and this process is repeated.

[0015] Furthermore, the material is torn and cut during the drying process while being lifted.

[0016] Furthermore, the material is pretreated before drying, including evaporating surface water and raising the material temperature to between 60°C and 70°C.

[0017] Furthermore, the temperature of the heat medium introduced into the vacuum chamber wall during the drying process is less than or equal to 85°C.

[0018] When drying natural rubber using this device, the material is added into the shell 2 through the feed inlet 23 at the top of the shell 2, then the feed inlet 23 is closed, and the air inside the shell 2 is extracted through the vacuum port 25. Then, a heat medium is introduced into the hollow interlayer of the outer wall of the shell 2 to heat the material inside the shell 2. During heating and drying, the spiral lifting part 1 inside the shell 2 rotates to lift the material upwards; during the lifting process, the material is torn by the tearing part 131 at the lower opening of the sleeve 13, and cut by the fixed blade 132 at the upper opening of the sleeve 13. The inverted frustum-shaped lower shell 22 facilitates the material to concentrate at the bottom center under gravity and then be lifted upwards by the spiral lifting part 1. The stirring shaft 11 of the spiral lifting part 1 has a double-layer tube structure, allowing the heat medium to also be introduced into the stirring shaft 11 for heating and drying the material.

[0019] The beneficial effects of this invention are as follows:

[0020] (i) Compared with existing technologies, this device can dry natural rubber materials at relatively low temperatures, accelerating moisture evaporation and avoiding thermal oxidation and decomposition of the rubber at high temperatures, thus maintaining the quality and performance of the rubber. At the same time, due to the strong adhesiveness of natural rubber, the device uses a spiral lifting section to lift, tear, and cut the material to prevent it from caking into lumps, thus better heating and drying the material and improving drying efficiency.

[0021] (ii) Vacuum negative pressure drying can be carried out in a relatively closed environment, reducing the contact between oxygen and contaminants, thereby avoiding the oxidation and contamination of rubber. This helps to improve the quality and purity of rubber.

[0022] (iii) Compared with traditional hot air drying methods, negative pressure drying requires less energy. Because the boiling point of water is lowered in a negative pressure environment, drying can be carried out at a lower temperature, thereby reducing energy consumption. Attached Figure Description

[0023] Figure 1 This is a perspective view of the overall structure of the device described in this invention;

[0024] Figure 2 This is a perspective view of the internal structure of the device described in this invention;

[0025] Figure 3 This is a front cross-sectional view of the device described in this invention;

[0026] Figure 4 This is a front sectional view of the interior of the housing of the device described in this invention in its use state;

[0027] Figure 5 This is a schematic diagram of the fixed-blade structure according to an embodiment of the present invention;

[0028] In the picture:

[0029] 1—Spiral lifting section, 11—Stirring shaft, 12—Spiral blade, 13—Sleeve, 131—Tearing section, 132—Fixed blade, 1321—Blade holder, 1322—Blade body, 133—Connecting rod, 14—Motor;

[0030] 2—Shell, 21—Upper shell, 22—Lower shell, 23—Inlet, 24—Outlet, 25—Vacuum port;

[0031] 3—Support; 4—Heat medium inlet; 5—Heat medium outlet. Detailed Implementation

[0032] To make the technical means, inventive features, and objectives of this invention easier to understand, the technical solution of this invention will be further described below with reference to one embodiment of a vacuum drying device and drying method suitable for natural rubber and specific implementation methods.

[0033] like Figure 1-5 As shown, specific embodiments of the present invention are as follows:

[0034] A vacuum drying device for natural rubber includes a triangular support 3, a housing 2, and a spiral lifting unit 1. The triangular support 3 supports the housing 2. The housing 2 is mounted on the triangular support 3 and is a sealed chamber with a hollow interlayer on its outer wall. A heat medium is introduced into the hollow interlayer to heat the material inside the housing 2. The housing 2 includes an upper housing 21 and a lower housing 22; the upper housing 21 is cylindrical, and the lower housing 22 is an inverted frustum shape. The upper surface of the lower housing 22 has the same diameter as the lower surface of the upper housing 21. The upper housing 21 and the lower housing 22 are fixedly connected. The top of the upper housing 21 has a feed inlet 23 and a vacuum port 25; the bottom of the lower housing 22 has a discharge port 24. Pneumatic eccentric hemispherical valves are installed at the feed inlet 23 and the discharge port 24. A heat medium inlet 4 is provided at the bottom of one side of the upper shell 21, and a heat medium outlet 5 is provided at the top of the opposite side; a heat medium inlet 4 is provided at the bottom of one side of the lower shell 22, and a heat medium outlet 5 is provided at the top of the opposite side; the heat medium can pass through the hollow interlayer between the upper shell 21 and the lower shell 22 through the heat medium inlet 4 and the heat medium outlet 5.

[0035] The spiral lifting section 1 is vertically installed inside the housing 2 to lift materials from the bottom to the top of the housing 2. The spiral lifting section 1 includes a stirring shaft 11, spiral blades 12, a sleeve 13, and a motor 14. The stirring shaft 11 is rotatably and vertically installed inside the housing 2, coaxial with the upper and lower housings. The spiral blades 12 are installed on the outer surface of the stirring shaft 11. The motor 14 is installed on the top of the upper housing 21, and its output end is connected to the upper end of the stirring shaft 11, enabling the stirring shaft 11 to rotate. The stirring shaft 11 has a double-layer tube structure. The bottom of the inner tube has a connecting port that communicates with the outer tube. The top of the inner tube has a heat medium inlet 4, and the top side of the outer tube has a heat medium outlet 5. Through the heat medium inlet 4 and the heat medium outlet 5, the heat medium can enter from the inner tube of the stirring shaft 11, enter the outer tube, and then be discharged. The sleeve 13 is fixedly installed inside the top of the housing 2 by a number of spaced connecting rods 133. The sleeve 13 is sleeved on the outer edge of the spiral blade 12. A separation part is installed inside the sleeve 13. When the material is lifted by the spiral blade 12, the separation part can separate the materials that are stuck together.

[0036] The separation section includes a tearing section 131 and a cutting section. The tearing section 131 is toothed with the tooth tips pointing vertically downwards and installed at the bottom of the cylinder. The cutting section includes a fixed blade 132 installed on the inner wall of the upper end of the sleeve 13. The fixed blade 132 includes a blade holder 1321 and a blade body 1322. The blade holder 1321 is fixedly installed against the inner wall of the sleeve 13 and is used to support the blade body 1322. The blade body 1322 is plate-shaped with a trapezoidal surface and its lower bottom edge is connected to the blade holder 1321 and supported in the blade holder 1321. The blade body 1322 is inclined in the direction of rotation of the stirring shaft 11 and forms a certain angle with the horizontal plane. When the spiral blade 12 lifts the material through the sleeve 13, the tearing section 131 can tear the material, and the cutting section can cut the material.

[0037] A drying method using a vacuum drying apparatus for natural rubber involves pre-treating the material, including evaporating surface water and raising the material temperature to between 60°C and 70°C. The pre-treated material is then fed into a vacuum chamber for drying. Air is extracted from the interior of the housing 2 through a vacuum port 25. A heat medium at a temperature of 85°C or less is introduced into the walls of the vacuum chamber and the stirring shaft 11 of the spiral lifting section 1 to heat the material inside the chamber. During drying, the material is lifted from the bottom to the top of the chamber and then allowed to fall naturally, repeating this cycle. During the lifting process, the material entering the sleeve 13 is subjected to a toothed tearing section 131 at the bottom of the sleeve 13 of the spiral lifting section 1. As the material exits from the top of the sleeve 13, it is cut by a fixed blade 132 on the inner wall of the upper end of the sleeve 13. After the drying process is completed, the material is discharged by opening the pneumatic eccentric hemispherical valve at the discharge port 24 at the bottom of the lower housing 22.

[0038] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A vacuum drying device for natural rubber, characterized by comprising: The utility model relates to a kind of material heating and separating device, including: Support (3) for erecting shell (2); Shell (2) is arranged on the support (3), the shell (2) is sealed cabin body, the shell (2) includes feed inlet (23) at the top of the shell (2), vacuum port (25) and discharge outlet (24) at the bottom of the shell (2);The feed inlet (23) and the discharge outlet (24) are provided with valve;The outer wall of the shell (2) is provided with hollow interlayer, and the material in the shell (2) can be heated by introducing heat medium into hollow interlayer; Spiral lifting part (1) is vertically arranged in the shell (2) and is used for lifting the material in the shell (2) from the bottom to the top; The spiral lifting part (1) includes stirring shaft (11), spiral blade (12), sleeve (13) and motor (14);The stirring shaft (11) is rotatably vertically arranged in the shell (2), and the spiral blade (12) is arranged on the outer surface of the stirring shaft (11);The motor (14) is arranged on the top of the shell (2), and the output end of the motor (14) is connected with the upper end of the stirring shaft (11), so that the stirring shaft (11) can be rotated;The sleeve (13) is fixedly arranged in the inner top of the shell (2) by a plurality of interval connecting rods (133), and the sleeve (13) is sleeved on the outer edge of the spiral blade (12);The sleeve (13) is provided with a separating part, which can separate the materials adhered together when the materials are lifted by the spiral blade (12); The separating part includes tearing part (131) and cutting part;The tearing part (131) is tooth-shaped, and the tooth tip is vertically arranged on the bottom of the sleeve (13);The cutting part includes a fixed knife (132) arranged on the inner wall of the upper end of the sleeve (13);The fixed knife (132) includes a knife seat (1321) and a blade body (1322);The knife seat (1321) is fixedly arranged on the inner wall of the sleeve (13) and is used for erecting the blade body (1322);The blade body (1322) is sheet-shaped, and the surface is trapezoidal, and the lower base is connected with the knife seat (1321) and is erected in the knife seat (1321);The blade body (1322) is inclined to the rotating direction of the stirring shaft (11) and forms a certain angle with the horizontal plane;The tearing part (131) can tear the materials when the materials are lifted by the spiral blade (12) through the sleeve (13), and the cutting part can cut the materials.

2. A vacuum drying apparatus for natural rubber as claimed in claim 1, wherein: The shell (2) includes upper shell (21) and lower shell (22);The upper shell (21) is cylindrical, and the lower shell (22) is inverted circular platform, and the upper surface of the lower shell (22) is the same diameter with the lower surface of the upper shell (21), and the upper shell (21) and the lower shell (22) are fixedly connected.

3. A vacuum drying apparatus for natural rubber as claimed in claim 2 wherein: The upper shell (21) is provided with a heat medium inlet (4) at one side of the bottom and a heat medium outlet (5) at the opposite side of the top; the lower shell (22) is provided with a heat medium inlet (4) at one side of the bottom and a heat medium outlet (5) at the opposite side of the top; the heat medium can pass through the hollow interlayer of the upper shell (21) and the lower shell (22) through the heat medium inlet (4) and the heat medium outlet (5).

4. A vacuum drying apparatus for natural rubber as claimed in claim 1, wherein: The stirring shaft (11) is a double-layer pipe structure, the inner pipe is provided with a communication port at the bottom for communication with the outer pipe, the inner pipe is provided with a heat medium inlet (4) at the top end, the outer pipe is provided with a heat medium outlet (5) at one side of the top, and the heat medium can pass through the inner pipe of the stirring shaft (11) and then enter the outer pipe and be discharged through the heat medium inlet (4) and the heat medium outlet (5).

5. A natural rubber drying method suitable for use in the drying apparatus of claim 1, characterized by: The material is sent into the vacuum cabin for drying; the wall of the vacuum cabin is hollow and can be provided with a heat medium for heating the material in the cabin; the material is lifted from the bottom of the cabin to the top of the cabin, then falls naturally and is repeatedly circulated.

6. A drying process for natural rubber as claimed in claim 5, characterized in that: The material is torn and cut during the lifting process during drying.

7. A drying method for natural rubber according to claim 5 or 6, characterized in that: The material is pretreated before drying, including evaporating the surface water of the material and raising the temperature of the material; the temperature of the material is raised to 60-70℃.

8. A drying method for natural rubber as claimed in claim 5, wherein: The temperature of the heat medium provided into the wall of the vacuum cabin during drying is less than or equal to 85℃.

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