Double-screw underwater pelletizing device for high-voltage cable insulation material production

Abstract

The invention discloses a double-screw underwater pelletizing device for production of a high-voltage cable insulating material, belongs to the field of cable equipment, and solves the problem of influence on cable insulativity caused by possible doping of impurities in a pelletizing process of an extra-high-voltage cable insulating material in the prior art. In the application, the device mainly comprises a double-screw extruder, a filter screen device, an underwater pelletizing system and the like. The double-screw extruder is used for mixing, plasticizing and conveying various raw materials; the filter screen device can filter impurities and unmelted particles in the materials, so that the product quality is ensured; and the underwater pelletizing system is used for cutting the extruded strip-shaped materials into uniform particles underwater. According to the double-screw underwater pelletizing device for production of the high-voltage cable insulation material, the purity and quality of products can be effectively improved, the automatic screen replacing function is achieved, the filter screen can be replaced under the condition that a machine is not stopped, and the production efficiency is improved.

Description

TECHNICAL FIELD

[0001] The application relates to a double-screw underwater pelletizing device for high-voltage cable insulation material production, and belongs to the cable equipment field. BACKGROUND

[0002] Commonly used high-voltage cable voltage grades are 35-110 kilovolts, 110 kilovolts-750 kilovolts belong to super-high-voltage cables, and 1000 kilovolts or above belong to extra-high-voltage cables. The super-high-voltage cable and the extra-high-voltage cable are necessary power transmission equipment for super-long-distance power transmission, have many advantages such as long power transmission distance, large capacity, high efficiency, low loss, low unit cost and small land occupation, and can effectively solve the transmission of super-long-distance and super-large-scale energy. In summary, it is super-power and super-long-distance power transmission, and the loss can be reduced to a very low level. Many problems can be effectively solved, and the laying cost will be higher, but the extra-high-voltage is in the seven fields of new infrastructure in China in 2020, so the construction of the extra-high-voltage is imperative. Because the resource endowment and load of China are inversely distributed at present, the extra-high-voltage is not only a new power transmission technology, but also a new resource allocation platform and a new low-carbon development road.

[0003] In the super-high-voltage cable insulation, even a small amount of impurities can cause a large decrease in product performance, and therefore ensuring the purity of the cable insulation material plays a crucial role in product quality. During the pelletizing and granulating process of the crosslinked polyethylene insulation material particles of the extra-high-voltage cable, impurities may be mixed in, so that the high-voltage resistance of the insulation material is reduced, thereby affecting the use performance of the high-voltage cable.

[0004] CONTENT

[0005] The application provides a double-screw underwater pelletizing device for high-voltage cable insulation material production, which effectively improves the purity and quality of crosslinked polyethylene insulation material particles.

[0006] The technical scheme adopted by the application is a double-screw underwater pelletizing device for high-voltage cable insulation material production, which comprises a screw extruder and an underwater pelletizing system, and the underwater pelletizing system is arranged at the extrusion end of the screw extruder.

[0007] The underwater pelletizing device further comprises a filter screen device, which is installed between the extrusion end of the screw extruder and the feeding end of the underwater pelletizing system, and the extrusion end of the screw extruder and the feeding end of the underwater pelletizing system are communicated through the filter screen device.

[0008] The filter screen device comprises a shell, the two ends of the shell are respectively provided with a feeding port and a discharging port, the shell is provided with an internal flow channel, the internal flow channel is located between the feeding port and the discharging port, and the two ends of the internal flow channel are respectively communicated with the feeding port and the discharging port; filter screen packages are arranged in the internal flow channel.

[0009] The filter screen device has a housing with a screen changing mechanism matched with the filter screen package.

[0010] The optimized double-screw underwater pelletizing device for high-voltage cable insulation material production has two groups of internal flow channels in the housing, which are located between the feeding port and the discharging port and are in communication with the feeding port and the discharging port at two ends, respectively.

[0011] The optimized double-screw underwater pelletizing device for high-voltage cable insulation material production has a filter screen device including a screen changing mechanism.

[0012] The screen changing mechanism includes two pistons, and the filter screen packages in the two groups of internal flow channels are arranged at the ends of the two pistons and are fixed opposite to the pistons, respectively.

[0013] The filter screen package has a replaceable filter screen, and the filter screen package and the piston have a blocking mechanism.

[0014] The optimized double-screw underwater pelletizing device for high-voltage cable insulation material production has two pressure sensing devices arranged in the two groups of internal flow channels, respectively, and the control output ends of the two pressure sensing devices are electrically connected to the control input ends of the hydraulic cylinder driving mechanisms of the two pistons.

[0015] The optimized double-screw underwater pelletizing device for high-voltage cable insulation material production has an underwater pelletizing system including a pelletizing unit, a downstream water processor, and a controller.

[0016] The pelletizing unit includes a pelletizing chamber and a pelletizing head, the pelletizing head is installed at the extrusion end of the screw extruder, the pelletizing mechanism is arranged in the pelletizing chamber, the feeding end of the pelletizing head is in communication with the extrusion end of the screw extruder, the discharging end of the pelletizing head is provided with a template, and the template is provided with a discharging die hole.

[0017] The water circulation port of the downstream water processor is in communication with the inside of the pelletizing chamber of the pelletizing unit through a water pipe, and the controller is electrically connected to the control end of the downstream water processor.

[0018] The optimized double-screw underwater pelletizing device for high-voltage cable insulation material production has a double-screw extruder, and the output range of the screw extruder is 700-1000 kg / h.

[0019] The optimized double-screw underwater pelletizing device for high-voltage cable insulation material production has a downstream water processor including

[0020] The pipeline system and a centrifugal water pump, the centrifugal water pump is arranged in the middle of the pipeline system and provides circulating power for water in the pipeline system; the pipeline system is connected with the inside of the pelletizing chamber of the pelletizing unit; through the power of the centrifugal water pump, the water in the pelletizing chamber of the pelletizing unit circulates in the pipeline system;

[0021] A heat exchanger, the heat exchanger is a plate heat exchanger, the water inlet port and the water outlet port of the heat exchanger are connected with the pipeline system;

[0022] A filtering device, the water in the pipeline system passes through the filtering device, and the fine particle impurities generated in the process of pelletizing are removed from the circulating water;

[0023] A dewatering machine, the dewatering machine is connected with the pelletizing chamber of the pelletizing unit through the pipeline system, and the insulation material particles in the pelletizing chamber of the pelletizing unit and the circulating water are dewatered through the dewatering machine, so that the insulation material particles are separated from the circulating water;

[0024] A water tank, the water tank is connected with the pipeline system and stores the circulating water.

[0025] The optimized double-screw underwater pelletizing device for producing high-voltage cable insulation material includes a filtering net package, and a filtering net is arranged in the filtering net package.

[0026] The filtering net package is internally provided with a mounting groove for accommodating the filtering net, and a plurality of filtering nets are mounted in the mounting groove.

[0027] The optimized double-screw underwater pelletizing device for producing high-voltage cable insulation material, the mesh numbers of the two adjacent filtering nets are different, and a filtering flow channel penetrating through the filtering net package is arranged in the middle of the filtering net package.

[0028] The technical scheme has the advantages that the double-screw design can provide stronger mixing and plasticizing effects, so that the material mixing is more uniform; the filtering net device can effectively improve the purity and quality of the product; the underwater pelletizing method can make the particles cool rapidly, have regular shapes, and reduce the adhesion phenomenon; the automatic screen changing function can replace the filtering net without stopping the machine, thereby improving the production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The figure is a structural schematic diagram of the application;

[0030] Figure 2 The figure is a structural schematic diagram of the double-screw extruder of the application;

[0031] Figure 3 The figure is a structural schematic diagram of the underwater pelletizing system of the application;

[0032] Figure 4The internal flow path structure of the screw extruder and the filter screen device of the present application is shown in the figure.

[0033] Figure 5 The structure of the filter screen device of the present application is shown in the figure.

[0034] Figure 6 The internal structure of the filter screen device of the present application is shown in the figure.

[0035] Figure 7 The connection structure of the downstream water treatment device of the present application is shown in the figure.

[0036] Figure 8 The structure of the cutter head of the present application is shown in the figure.

[0037] Figure 9 The connection structure of the filter screen package of the present application is shown in the figure. DETAILED DESCRIPTION

[0038] The technical features of the present application are further described below in combination with the drawings and specific examples.

[0039] As shown in the figure, the present application is a double-screw underwater pelletizing device for high-voltage cable insulation material production, which comprises a screw extruder 1, an underwater pelletizing system 2, and a filter screen device 3. The underwater pelletizing system 2 is arranged at the extrusion end of the screw extruder 1. The filter screen device 3 is installed between the extrusion end of the screw extruder 1 and the feeding end of the underwater pelletizing system 2, and the extrusion end of the screw extruder 1 and the feeding end of the underwater pelletizing system 2 are connected through the filter screen device 3.

[0040] The double-screw extruder mixes, plasticizes, and conveys various raw materials; the filter screen device can filter out impurities and unmelted particles in the material, ensuring product quality; and the underwater pelletizing system cuts the extruded strip-shaped material into uniform particles underwater.

[0041] In the present application, the raw materials enter the double-screw extruder through the feeding port and are rubbed into a lump shape and roll forward along the screw groove under the action of the rotating screw. The shearing, compression, and stirring action of the screw makes the material further mixed and plasticized, and the temperature and pressure gradually increase, showing a viscous flow state. The material passes through the filter screen device during the extrusion process, and impurities are intercepted. Subsequently, the material is extruded from the head to form a strip and enters the underwater pelletizing system, which is cut into particles under the action of the high-speed rotating cutter.

[0042] Specifically, the double-screw underwater pelletizing device for producing high-voltage cable insulation material includes a screw extruder 1, an underwater pelletizing system 2, and a filter screen device 3. The underwater pelletizing system 2 is arranged at the extrusion end of the screw extruder 1, and the filter screen device 3 is installed between the extrusion end of the screw extruder 1 and the feeding end of the underwater pelletizing system 2. The filter screen device 3 is installed at the extrusion end of the screw extruder 1 and the feeding end of the underwater pelletizing system 2 and is connected through the filter screen device 3.

[0043] In one embodiment of the present application, the screw extruder 1 can be a double-screw extruder, which can adopt the form of a screw extruder commonly used in the prior art and is composed of a screw, a motor, a transmission device, a water cooling device, and a temperature control system. In this embodiment, the output range of the screw extruder 1 is selected to be 700-1000 kg / h.

[0044] As shown in the figure, in one embodiment of the present application, the underwater pelletizing system 2 includes a pelletizing unit 201, a downstream water processor 202, and a controller 203.

[0045] The pelletizing unit 201 includes a pelletizing chamber and a pelletizing head. The pelletizing head is installed at the extrusion end of the screw extruder 1, and the pelletizing mechanism is arranged in the pelletizing chamber. The feeding end of the pelletizing head is connected to the extrusion end of the screw extruder 1, and the discharging end of the pelletizing head is provided with a die plate, and the die plate is provided with discharging die holes. A cutter holder is arranged on the die plate.

[0046] The water circulation port of the downstream water processor 202 is connected to the inside of the pelletizing chamber of the pelletizing unit 201 through a water pipe, and the controller 203 is electrically connected to the control end of the downstream water processor 202.

[0047] After the molten material of the extruder is stabilized, the equipment starts to operate. After the pelletizing motor is turned on, the water starts to circulate, the cutter holder moves to the die plate, and the valve is started. The entire pelletizing process starts. The polymer melt flows to the pelletizing head, passes through the die plate, enters the pelletizing chamber, and is cut into particles in the flowing water. The water transports the particles to the water separator, then dries them, and finally transfers them to the storage chamber through the injector.

[0048] During the operation of the underwater pelletizing system 2, water is transported from the water tank 208 by the pump, passes through the pelletizing chamber to the water separator, and finally flows back to the water tank 208. The process water is purified by fine filtration and cooled by the heat exchanger 204. The water level of the water tank 208 is maintained stable by the electromagnetic valve.

[0049] In one embodiment of the present application, the downstream water processor 202 includes a pipeline system, a centrifugal water pump 207, a heat exchanger 204, a filter device 206, a dewatering machine 205, and a water tank 208.

[0050] Centrifugal water pump 207 is arranged in the middle of the pipeline system and provides the circulating power of the water in the pipeline system, which is in communication with the cutting chamber of the cutting unit 201. Through the power of the centrifugal water pump 207, the water in the cutting chamber of the cutting unit 201 circulates in the pipeline system.

[0051] The heat exchanger 204 is a plate heat exchanger, which can take away the heat of the molten insulation material to ensure the solidification and forming of the particles. The water inlet and outlet ports of the heat exchanger 204 are connected to the pipeline system.

[0052] The water in the pipeline system passes through the filtering device 206 to remove the fine particle impurities generated during cutting.

[0053] The dehydrator 205 is connected to the cutting chamber of the cutting unit 201 through the pipeline system. After the insulation material particles and circulating water in the cutting chamber of the cutting unit 201 pass through the dehydrator 205, the insulation material particles are separated from the circulating water.

[0054] The water tank 208 stores circulating water to balance the water quantity of the system and sometimes serves as a water supplement point.

[0055] The underwater cutting machine realizes efficient water temperature stability, regular particle shape and low adhesion effect through precise control system. In terms of water temperature control, it is equipped with a closed-loop water circulation system and a plate heat exchanger, as well as a thermal insulation template and special materials, which can greatly reduce the migration of melt heat to process water, not only reducing energy consumption by 70%, but also strictly controlling water temperature fluctuations within ±0.5℃, and without bypass pipeline, simplifying the operation process. The regularity of particle shape is realized through double protection: the thermal insulation template can avoid mold hole condensation and ensure uniform melt temperature; the adjustable gap tungsten / ceramic alloy dynamic knife combination can accurately match the extrusion flow and cutter speed, making the particle size uniformity reach ±0.02mm. The adhesion problem is from cutting to post-processing. The design of the water guide hole 5 and the radial water channel 6 of the cutter head can eliminate the central vortex and enhance the backwater pressure. The subsequent centrifugal spin-drying + hot air drying double process reduces the moisture content to below 0.1%, and the pre-positioned large material catcher automatically separates the agglomerates, which can prevent particle adhesion in all directions.

[0056] The role of the water guide hole 5: the water guide hole 5 is arranged on the cutter head in the circumferential direction, and the water of the water guide hole 5 is provided by a downstream water processor and continuously circulated in the pipeline system 201 by the power of the centrifugal water pump 207. The water guide hole 5 provides shear force to destroy the viscous structure, and the essence of the central vortex is that the water flow carries the cut particles to rotate. The high-speed jet of the water guide hole 5 injects a huge radial shear force into this area. This force directly acts on the structure of the vortex, disperses it, and destroys the flow field that makes the particles gather centripetally; dilutes and transports the central particles: just like using a high-pressure water gun to flush the accumulated sand, the jet of the water guide hole 5 instantly disperses the central accumulated "wet particle group" that may be re-bonded, and wraps it into the main circulating flow channel, preventing them from "settling" in the center to form a mud cake; change the stress state of the particles: the jet gives the central particles additional kinetic energy, overcoming the microscopic forces such as van der Waals forces that make particles adsorb each other, and making the particles change from "sticky state" to "suspended flow state".

[0057] The role of the radial water channel 6: the water of the radial water channel 6 is provided by a downstream water processor, and a homogeneous pressure transmission medium is created: the core function of the radial water channel 6 is to make the entire "cut particle-fluid" mixture in front of the cutter head become homogeneous in properties. A homogeneous plastic fluid can uniformly transmit hydrostatic pressure like a liquid.

[0058] In the present application, the filter screen device 3 comprises a shell 301, the shell 301 has a feeding port and a discharging port at two ends respectively, and the shell 301 has an internal flow channel 302 therein, the internal flow channel 302 is located between the feeding port and the discharging port, and the two ends of the internal flow channel 302 are in communication with the feeding port and the discharging port respectively. The internal flow channel 302 is provided with a filter screen package 303 therein. The shell 301 of the filter screen device 3 is provided with a screen changing mechanism therein, and the screen changing mechanism is arranged in cooperation with the filter screen package 303.

[0059] In one embodiment of the present application, the shell 301 has two groups of internal flow channels 302 therein, the two groups of internal flow channels 302 are located between the feeding port and the discharging port, and the two ends of the internal flow channel 302 are in communication with the feeding port and the discharging port respectively; each group of internal flow channels 302 is provided with a filter screen package 303 therein.

[0060] The screen changing mechanism comprises two pistons 304. The filter screen packages 303 in the two groups of internal flow channels 302 are arranged at the ends of the two pistons 304 and are fixed relative to the pistons 304. Each piston 304 is connected with a group of hydraulic cylinder driving mechanisms and is driven to move by the hydraulic cylinder driving mechanisms. The filter screen package 303 has a replaceable filter screen. The filter screen package 303 and the piston 304 are provided with a blocking mechanism; after the piston 304 pushes the filter screen package 303 to move out of the shell 301, the blocking mechanism blocks the internal flow channel 302.

[0061] Two pressure sensing devices are arranged in the internal flow channel 302 of the two groups respectively, and the control output ends of the two pressure sensing devices are electrically connected with the control input ends of the hydraulic cylinder driving mechanism of the two pistons 304 respectively.

[0062] In the present application, the hot melt plastic and other thermoplastic materials heated and melted are usually divided into two groups of the filter screen packages 303 on the two pistons 304, and filtered at the same time, and each piston 304 contains one filter screen package 303. When the filter screen is blocked, the production process current rises and reaches the specified maximum pressure, one piston 304 is moved out in a hydraulic manner, such as Figure 3 Then the filter screen in the filter screen package 303 can be replaced. At the same time, the whole melt is guided through the second piston 304. After replacing the screen package, the piston 304 moves back, and the production process continues. Then the process is repeated through the other piston 304. In this way, the screen replacement during the production process is realized without stopping, and the continuous production is ensured.

[0063] In one embodiment of the present application, the structure of the filter screen package 303 is shown in the figure, and the filter screen package 303 includes a screen package shell, and a filter screen is arranged in the screen package shell. The screen package shell of the filter screen package 303 is internally constructed with a mounting groove for accommodating the filter screen, and a plurality of layers of filter screens are mounted in the mounting groove. The plurality of layers of filter screens are stacked and clamped in the mounting groove in the middle of the screen package shell.

[0064] The mesh numbers of the adjacent two filter screens are different. The filter screen package 303 is constructed with a filter flow channel penetrating through the filter screen package 303 in the middle, and the filter flow channel penetrates the mounting. In this embodiment, the filter screens with different mesh numbers are stacked together and clamped in the recess of the filter screen package. The filter screen package is in close contact with the internal flow channel, and both have the same thermal expansion and cold shrinkage performance, and no other sealing measures are required.

[0065] Of course, the above description is not a limitation of the present application, and the present application is not limited to the above examples. Within the scope of the present application, changes, modifications, additions or replacements made by ordinary skilled in the art should be within the scope of protection of the present application.

Claims

1. A double-screw underwater pelletizing device for high-voltage cable insulation material production, comprising a screw extruder (1) and an underwater pelletizing system (2), wherein the underwater pelletizing system (2) is arranged at the extrusion end of the screw extruder (1); characterized in that: a filter screen device (3) is further arranged between the extrusion end of the screw extruder (1) and the feeding end of the underwater pelletizing system (2), and the filter screen device (3) is arranged to communicate the extrusion end of the screw extruder (1) and the feeding end of the underwater pelletizing system (2). The filter screen device (3) comprises a housing (301) having a feeding port and a discharging port at two ends thereof, and an internal flow channel (302) in the housing (301) between the feeding port and the discharging port, wherein the two ends of the internal flow channel (302) communicate with the feeding port and the discharging port, respectively, and a filter screen package (303) is arranged in the internal flow channel (302). The housing (301) of the filter screen device (3) is provided with a screen changing mechanism which cooperates with the filter screen package (303). The housing (301) is provided with two groups of internal flow channels (302) between the feeding port and the discharging port, wherein the two ends of each group of internal flow channels (302) communicate with the feeding port and the discharging port, respectively, and a filter screen package (303) is arranged in each group of internal flow channels (302).

2. The double screw underwater pelletizing device for high voltage cable insulation material production according to claim 1, characterized in that: The filter screen device (3) comprises a screen changing mechanism.

3. The double screw underwater pelletizing device for high voltage cable insulation material production according to claim 2, characterized in that: The screen changing mechanism comprises two pistons (304), and the filter screen packages (303) in the two groups of internal flow channels (302) are arranged at the ends of the two pistons (304) and fixedly connected to the pistons (304), respectively. Each piston (304) is connected to a group of hydraulic cylinder driving mechanisms and driven to move by the hydraulic cylinder driving mechanisms. The filter screen package (303) is provided with replaceable filter screens, and a blocking mechanism is arranged between the filter screen package (303) and the piston (304).

4. The double screw underwater pelletizing device for high voltage cable insulation material production according to claim 3, characterized in that: After the piston (304) pushes the filter screen package (303) out of the housing (301), the blocking mechanism blocks the internal flow channel (302).

5. The double screw underwater pelletizing device for high voltage cable insulation compound production according to claim 1, characterized in that: Pressure sensing devices are arranged in the two groups of internal flow channels (302), respectively, and the control output ends of the two pressure sensing devices are electrically connected to the control input ends of the hydraulic cylinder driving mechanisms of the two pistons (304). The underwater pelletizing system (2) comprises a pelletizing unit (201), a downstream water processor (202), and a controller (203). The pelletizing unit (201) comprises a pelletizing chamber and a pelletizing head, wherein the pelletizing head is arranged at the extrusion end of the screw extruder (1), the pelletizing mechanism is arranged in the pelletizing chamber, the feeding end of the pelletizing head communicates with the extrusion end of the screw extruder (1), the discharging end of the pelletizing head is provided with a die plate, and the die plate is provided with discharging die holes; a cutter holder is arranged on the die plate. The water circulation port of the downstream water processor (202) communicates with the inside of the pelletizing chamber of the pelletizing unit (201) through a water pipe, and the controller (203) is electrically connected to the control end of the downstream water processor (202).

6. The double screw underwater pelletizing device for high voltage cable insulation compound production according to claim 1, characterized in that: The screw extruder (1) is a double-screw extruder, and the output of the screw extruder (1) ranges from 700 to 1000 kg / h.

7. The double screw underwater pelletizing device for high voltage cable insulation compound production according to claim 5, characterized in that: The downstream water treatment device (202) comprises a pipeline system and a centrifugal water pump (207) arranged in the middle section of the pipeline system and providing circulating power for water in the pipeline system; the pipeline system is in communication with the inside of the pelletizing chamber of the pelletizing unit (201); under the power of the centrifugal water pump (207), the water in the pelletizing chamber of the pelletizing unit (201) circulates in the pipeline system; a heat exchanger (204), which is a plate heat exchanger, and the water inlet and outlet ports of the heat exchanger (204) are connected to the pipeline system; a filtering device (206), through which the water in the pipeline system passes, and fine particle impurities generated in the pelletizing process are removed from the circulating water; a dewatering machine (205), which is in communication with the pelletizing chamber of the pelletizing unit (201) through the pipeline system, and the insulation material particles in the pelletizing chamber of the pelletizing unit (201) and the circulating water are separated from each other after being dewatered by the dewatering machine (205); a water tank (208) in communication with the pipeline system and storing the circulating water.

8. The double screw underwater pelletizing device for high voltage cable insulation compound production according to claim 1, characterized in that: The filter screen package (303) comprises a package shell, and a filter screen is arranged in the package shell; The package shell of the filter screen package (303) is internally provided with a mounting groove for accommodating the filter screen, and a plurality of layers of filter screens are mounted in the mounting groove; the plurality of layers of filter screens are clamped in the mounting groove in the middle of the package shell after being stacked.

9. The double screw underwater pelletizing device for high voltage cable insulation compound production according to claim 8, characterized in that: The mesh numbers of two adjacent filter screens are different; The filter screen package (303) is internally provided with a filtering flow channel penetrating through the filter screen package (303), and the filtering flow channel penetrates through the mounting groove.

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