Granule conveying device

Abstract

The utility model relates to a granule conveying device, which comprises a conveying pipeline connected with an outlet of a granulator, a granule flow meter arranged on the conveying pipeline, a granule buffer tank and a mixing bin, and is characterized in that the top of the granule buffer tank is provided with a feeding hopper communicated with the conveying pipeline, and the bottom of the granule buffer tank is provided with a conical discharge port; a tubular heat exchanger is arranged in the buffer tank in an integrated mode, the two sides of the tube pass of the tubular heat exchanger are connected with the feeding hopper and a discharging port flange respectively, the shell pass of the tubular heat exchanger is connected to a cooling medium, and a material level rotating valve is arranged at the bottom of the discharging port. And the mixing bin is connected with a discharge hole of the granule buffer tank.

Description

Technical Field

[0001] The utility model relates to the technical field of polyolefin granulation, in particular to a granule conveying device. Background Art

[0002] Polyolefin materials such as polyethylene and polypropylene are widely used in packaging, construction, automotive, and electronics due to their excellent physical properties, chemical stability, and processing adaptability. In the industrial production of polyolefins, granulation is a key post-processing step, and its process flow generally includes polymer melting, extrusion, cooling and shaping, pelletizing, and subsequent packaging. In the polyolefin granulation process, the granular products formed after the molten resin is extruded, pelletized, and initially cooled usually still carry residual heat. After granulation, the temperature of the polyolefin resin is still relatively high, for example, up to about 75°C. If it is directly fed into the downstream packaging process, it will cause the packaging material to deform due to heat, especially the film packaging bags to stick or shrink, resulting in unstable operation of the downstream packaging system and storage safety hazards. Utility Model Content

[0003] Therefore, the purpose of the present invention is to provide a pellet conveying device that can achieve efficient, energy-saving, and integrated re-cooling after the resin granulation is completed and before entering the packaging, so as to ensure the stable packaging operation of the downstream packaging system such as film packaging bags.

[0004] The pellet conveying device of the present invention includes a conveying pipeline connected to the granulator outlet, a pellet flowmeter arranged on the conveying pipeline, a pellet buffer tank and a blending silo, wherein the pellet buffer tank is provided with a feed hopper connected to the conveying pipeline on the top and a conical discharge port on the bottom, and a tubular heat exchanger is integrated in the buffer tank, the two sides of the tube side of the tubular heat exchanger are respectively connected to the feed hopper and the discharge port flange and the shell side of the tubular heat exchanger is connected to the cooling medium, a material level rotary valve is provided at the bottom of the discharge port, and the blending silo is connected to the discharge port of the pellet buffer tank.

[0005] Preferably, the tubular heat exchanger has a shell, in the interior of which a plurality of heat exchange tubes are arranged spaced apart and parallel to each other, the heat exchange tubes extending vertically or obliquely so that the pellets are transported through the tube side of the tubular heat exchanger under the action of gravity.

[0006] Preferably, along the flow direction of the pellets, a cooling medium outlet is provided on the upper portion of the outer wall of the shell of the tubular heat exchanger, and a cooling medium inlet is provided on the lower portion.

[0007] Preferably, a material level sensor is provided in the feed hopper of the pellet buffer tank, and the material level sensor is communicatively connected with a material level rotary valve provided at the bottom of the discharge port.

[0008] Preferably, a temperature sensor is provided at the discharge port.

[0009] Preferably, the cooling medium inlet is provided with a flow rate control valve, and the flow rate control valve is communicatively connected to the temperature sensor.

[0010] Preferably, the blending silo is provided with a blending pipe, the inlet of the blending pipe is connected to the bottom of the blending silo and the outlet is connected to the top of the blending silo.

[0011] The pellet conveying device provided by the present invention integrates a tubular heat exchanger into the pellet buffer tank, adds a heat exchange process to the pellet conveying process, and can cool the resin temperature after pelletizing from, for example, 75°C to about 60°C, thereby achieving efficient, energy-saving, and integrated re-cooling before the resin enters the packaging after the pelletizing is completed, thereby improving the stability of the film sealing temperature in the film packaging of the packaging system, meeting the requirements of the pellets conveyed upstream of the packaging under high load, and ensuring the stable operation of the pellet system and polymerization system of the upstream process. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a structural schematic diagram of a pellet conveying device according to one embodiment of the present utility model.

[0013] Figure 2 It is a structural schematic diagram of a pellet conveying device according to another embodiment of the present invention. DETAILED DESCRIPTION

[0014] The preferred embodiments of the present invention will be described in detail and clearly below in conjunction with the accompanying drawings of this application.

[0015] like Figure 1 As shown, the pellet conveying device of the present invention includes a conveying pipeline 1, a pellet flowmeter 2 provided on the conveying pipeline 1, a pellet buffer tank 3 and a blending silo 4.

[0016] Conveying pipeline 1 is connected to the outlet of the pelletizer to transport the preliminarily cooled pellets obtained from the pelletizer. A pellet flowmeter 2 is installed on conveying pipeline 1 before the pellet buffer tank 3. This allows for real-time monitoring and control of the pellet flow rate entering the pellet buffer tank 3 before the pellets enter the pellet buffer tank 3, dynamically balancing the production rhythm and ensuring the stability of the production process. For example, if the pelletizer is temporarily shut down due to a malfunction, the pellet flowmeter detects a sudden drop in flow and triggers downstream equipment to slow down or pause, preventing shutdown after the buffer tank is emptied. If the flow rate exceeds the maximum processing capacity of the buffer tank, the flowmeter can trigger an alarm or automatically adjust the pelletizer screw speed to prevent pellet accumulation and blockage in the buffer tank.

[0017] The pellet buffer tank 3 is a device for temporary storage and balancing the flow of pellets. It is usually located between the pelletizer and the downstream packaging to buffer production fluctuations and ensure production continuity and stability. The tank body of the pellet buffer tank can usually be a cylindrical or square container. A feed hopper 5 connected to the conveying pipeline 1 is provided at the top, a conical discharge port 6 is provided at the bottom, and a material level rotary valve 7 is provided at the bottom of the discharge port 6. In one embodiment, a tubular heat exchanger 8 is integrated in the buffer tank 3. The two sides of the tube side of the tubular heat exchanger are flange-connected to the feed hopper 5 and the discharge port 6 respectively, and the shell side of the tubular heat exchanger is connected to the cooling medium.

[0018] The tubular heat exchanger 8 comprises a housing 9, within which a plurality of heat exchange tubes 10 are arranged, spaced apart and parallel to one another. These tubes extend vertically or at an angle, allowing the pellets to be transported through the tubes of the tubular heat exchanger under gravity. The unique tube design, lacking horizontal areas within the tubular heat exchanger, effectively prevents unwanted pellet residue. A cooling medium outlet is located at the upper portion of the outer wall of the tubular heat exchanger, along with a cooling medium inlet at the lower portion, along the direction of pellet flow. The cooling medium is preferably cooling water.

[0019] In a preferred embodiment, a level sensor 11 is provided in the feed hopper 5 of the pellet buffer tank 3. This level sensor is in communication with a rotary level valve 7 located at the bottom of the discharge port. This level sensor is used to control the pelletizer's discharge rate to ensure that the buffer tank's feed hopper is always filled with pellets, ensuring that the heat exchange tubes are always filled with pellets during operation.

[0020] The pellets flow through the heat exchange tubes of the tubular heat exchanger under gravity until they reach the discharge port at the bottom of the buffer tank. After cooling, they are discharged through a rotary valve. In one preferred embodiment, a temperature sensor is installed at the discharge port. In another preferred embodiment, a flow rate control valve is installed at the cooling medium inlet of the tubular heat exchanger. This flow rate control valve is communicatively connected to the temperature sensor at the discharge port. This communication connection allows the cooling medium flow rate to be dynamically adjusted to achieve the desired pellet cooling temperature.

[0021] In another alternative embodiment, Figure 2As shown, the pellet buffer tank includes a main channel 1' and a bypass channel 2'. The tubular heat exchanger can be placed in the bypass channel of the buffer tank. A diverter valve 3' is installed downstream of the feed hopper to control the ratio of pellet flow into the buffer tank between the main channel and the bypass channel. In this embodiment, pellets are fed from the buffer tank feed hopper and are split into two streams by the diverter valve. One stream flows directly through the main channel to the outlet at the bottom of the buffer tank, while the other stream flows through the bypass channel through the tubular heat exchanger for cooling. The diverter ratio can be set based on the initial pellet temperature. In a preferred embodiment, temperature sensors are installed at the outlets of the main channel and the bypass channel to monitor the pellet temperature. In another preferred embodiment, the temperature sensors are connected to the diverter valve to dynamically adjust the diverter ratio based on temperature feedback. This bypass channel design allows the diverter valve to adjust the cooling intensity to meet the cooling requirements of different pellet types. It also prevents the pellets from being retained entirely within the buffer tank, cooling only the hottest portion, thereby reducing energy consumption.

[0022] The pellets discharged from the discharge port 6 of the pellet buffer tank 3 reach the blending silo 4 through the conveying pipe 1. The blending silo 4 can be used to mix pellets of different batches or add other ingredients, for example, by physically mixing pellets produced in different time periods to ensure that the pellets of different batches or formulas have uniform ingredients and consistent performance, thereby improving product quality stability and meeting downstream processing requirements. The blending silo is equipped with a blending pipe 12, the inlet of the blending pipe is connected to the bottom of the blending silo and the outlet is connected to the top of the blending silo. As an example, when the pellets from the pellet buffer tank 3 enter the blending silo 4 from the top, the temperature of the pellets that enter the top of the blending silo 4 later is higher, while the temperature of the pellets that enter the bottom of the blending silo 4 earlier is lower. By back-mixing the pellets at the top and bottom of the blending silo, the temperature uniformity of the pellets in the blending silo can be improved.

[0023] The pellet conveying device provided by the present invention can be applied to the production of polyolefins, such as polyethylene and polypropylene pellets. The pellet conveying device is connected between a polyolefin pelletizer and a downstream packaging system. By adding a heat exchange process to the polyolefin pelletizing resin conveying process, the pellet cooling time during the conveying process can be reduced, thereby improving production efficiency. In the downstream packaging system, the heat sealing temperature of the packaging film is guaranteed, and the opening of the heat-sealing film caused by the excessively high temperature of the resin conveyed to the packaging system is reduced; the operation of the packaging machine and the film replacement and adjustment operations are reduced, thereby ensuring the stable operation of the packaging system, improving the stable connection of the upstream and downstream processes of the polyolefin and packaging system, and the stable operation of the device. At the same time, due to the reduction in the temperature of the polyolefin resin, the packaging film packaging operation is stable, reducing the shutdown of the packaging system, and also reducing the situation where the load of the upstream polymerization and pelletizing system is forced to be reduced due to the influence of the packaging system, thereby saving the overall energy consumption and material consumption of the device.

[0024] The above is a detailed description of the preferred embodiment of the present invention, which is not intended to limit the scope of protection of the present invention. For those skilled in the art, various changes and modifications can be made to the present invention, and any equivalent changes or modifications made are within the scope of protection of the present invention.

Claims

1. A pellet conveying device, comprising a conveying pipe connected to the granulator outlet, a pellet flow meter arranged on the conveying pipe, a pellet buffer tank and a blending silo, characterized in that: A feed hopper connected to the conveying pipeline is provided on the top of the pellet buffer tank, and a conical discharge port is provided at the bottom. A tubular heat exchanger is integrated in the buffer tank. The two sides of the tube side of the tubular heat exchanger are respectively connected to the feed hopper and the discharge port flange, and the shell side of the tubular heat exchanger is connected to the cooling medium. A material level rotary valve is provided at the bottom of the discharge port, and the mixing silo is connected to the discharge port of the pellet buffer tank.

2. The pellet conveying device according to claim 1, characterized in that: The tubular heat exchanger has a shell, in the interior space of which a plurality of heat exchange tubes are arranged in parallel at intervals. The heat exchange tubes extend vertically or obliquely so that the pellets are transported through the tube side of the tubular heat exchanger under the action of gravity.

3. The pellet conveying device according to claim 1, characterized in that: Along the flow direction of the granular material, a cooling medium outlet is provided on the upper portion of the outer wall of the shell of the tubular heat exchanger, and a cooling medium inlet is provided on the lower portion.

4. The pellet conveying device according to claim 1, characterized in that: A material level sensor is provided in the feed hopper of the pellet buffer tank, and the material level sensor is communicatively connected with a material level rotary valve provided at the bottom of the discharge port.

5. The pellet conveying device according to claim 1, characterized in that: The buffer tank includes a main channel and a bypass channel. The tubular heat exchanger is arranged in the bypass channel of the buffer tank. A diversion regulating valve is provided downstream of the feed hopper to control the ratio of the main channel and the bypass channel of the pellets flowing into the buffer tank.

6. The pellet conveying device according to claim 3, characterized in that: A temperature sensor is provided at the discharge port.

7. The pellet conveying device according to claim 6, characterized in that: The cooling medium inlet is provided with a flow rate control valve, and the flow rate control valve is communicatively connected with the temperature sensor.

8. The pellet conveying device according to claim 1, characterized in that: The blending silo is provided with a blending pipe, the inlet of the blending pipe is connected to the bottom of the blending silo and the outlet is connected to the top of the blending silo.

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